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Sample records for major streams draining

  1. Spatial variation in basic chemistry of streams draining a volcanic landscape on Costa Rica's Caribbean slope

    Science.gov (United States)

    Pringle, C.M.; Triska, F.J.; Browder, G.

    1990-01-01

    Spatial variability in selected chemical, physical and biological parameters was examined in waters draining relatively pristine tropical forests spanning elevations from 35 to 2600 meters above sea level in a volcanic landscape on Costa Rica's Caribbean slope. Waters were sampled within three different vegetative life zones and two transition zones. Water temperatures ranged from 24-25 ??C in streams draining lower elevations (35-250 m) in tropical wet forest, to 10 ??C in a crater lake at 2600 m in montane forest. Ambient phosphorus levels (60-300 ??g SRP L-1; 66-405 ??g TP L-1) were high at sites within six pristine drainages at elevations between 35-350 m, while other undisturbed streams within and above this range in elevation were low (typically <30.0 ??g SRP L-1). High ambient phosphorus levels within a given stream were not diagnostic of riparian swamp forest. Phosphorus levels (but not nitrate) were highly correlated with conductivity, Cl, Na, Ca, Mg and SO4. Results indicate two major stream types: 1) phosphorus-poor streams characterized by low levels of dissolved solids reflecting local weathering processes; and 2) phosphorus-rich streams characterized by relatively high Cl, SO4, Na, Mg, Ca and other dissolved solids, reflecting dissolution of basaltic rock at distant sources and/or input of volcanic brines. Phosphorus-poor streams were located within the entire elevation range, while phosphorus-rich streams were predominately located at the terminus of Pleistocene lava flows at low elevations. Results indicate that deep groundwater inputs, rich in phosphorus and other dissolved solids, surface from basaltic aquifers at breaks in landform along faults and/or where the foothills of the central mountain range merge with the coastal plain. ?? 1990 Kluwer Academic Publishers.

  2. Upland and in-stream controls on baseflow nutrient dynamics in tile-drained agroecosystem watersheds

    Science.gov (United States)

    Ford, William I.; King, Kevin; Williams, Mark R.

    2018-01-01

    In landscapes with low residence times (e.g., rivers and reservoirs), baseflow nutrient concentration dynamics during sensitive timeframes can contribute to deleterious environmental conditions downstream. This study assessed upland and in-stream controls on baseflow nutrient concentrations in a low-gradient, tile-drained agroecosystem watershed. We conducted time-series analysis using Empirical mode decomposition of seven decade-long nutrient concentration time-series in the agricultural Upper Big Walnut Creek watershed (Ohio, USA). Four tributaries of varying drainage areas and three main-stem sites were monitored, and nutrient grab samples were collected weekly from 2006 to 2016 and analyzed for dissolved reactive phosphorus (DRP), nitrate-nitrogen (NO3-N), total nitrogen (TN), and total phosphorus (TP). Statistically significant seasonal fluctuations were compared with seasonality of baseflow, watershed characteristics (e.g., tile-drain density), and in-stream water quality parameters (pH, DO, temperature). Findings point to statistically significant seasonality of all parameters with peak P concentrations in summer and peak N in late winter-early spring. Results suggest that upland processes exert strong control on DRP concentrations in the winter and spring months, while coupled upland and in-stream conditions control watershed baseflow DRP concentrations during summer and early fall. Conversely, upland flow sources driving streamflow exert strong control on baseflow NO3-N, and in-stream attenuation through transient and permanent pathways impacts the magnitude of removal. Regarding TN and TP, we found that TN was governed by NO3-N, while TP was governed by DRP in summer and fluvial erosion of P-rich benthic sediments during higher baseflow conditions. Findings of the study highlight the importance of coupled in-stream and upland management for mitigating eutrophic conditions during environmentally sensitive timeframes.

  3. Importance of including small-scale tile drain discharge in the calibration of a coupled groundwater-surface water catchment model

    DEFF Research Database (Denmark)

    Hansen, Anne Lausten; Refsgaard, Jens Christian; Christensen, Britt Stenhøj Baun

    2013-01-01

    the catchment. In this study, a coupled groundwater-surface water model based on the MIKE SHE code was developed for the 4.7 km2 Lillebæk catchment in Denmark, where tile drain flow is a major contributor to the stream discharge. The catchment model was calibrated in several steps by incrementally including...... the observation data into the calibration to see the effect on model performance of including diverse data types, especially tile drain discharge. For the Lillebæk catchment, measurements of hydraulic head, daily stream discharge, and daily tile drain discharge from five small (1–4 ha) drainage areas exist....... The results showed that including tile drain data in the calibration of the catchment model improved its general performance for hydraulic heads and stream discharges. However, the model failed to correctly describe the local-scale dynamics of the tile drain discharges, and, furthermore, including the drain...

  4. Water-quality trends for a stream draining the Southern Anthracite Field, Pennsylvania

    Science.gov (United States)

    Cravotta, C.A.; Bilger, Michael D.

    2001-01-01

    Stream flow, chemical and biological data for the northern part of Swatara Creek, which drains a 112 km2 area in the Southern Anthracite Field of eastern Pennsylvania, indicate progressive improvement in water quality since 1959, after which most mines in the watershed had been flooded. Drainage from the flooded mines contributes substantially to base flow in Swatara Creek. Beginning in 1995, a variety of treatment systems and surface reclamation were implemented at some of the abandoned mines. At Ravine, Pa., immediately downstream of the mined area, median SO4 concentration declined from about 150 mg l-1 in 1959 to 75 mg l-1 in 1999 while pH increased from acidic to near-neutral values (medians: c. pH 4 before 1975; c. pH 6 after 1975). Fish populations rebounded from non-existent during 1959-1990 to 21 species identified in 1999. Nevertheless, recent monitoring indicates (1) episodic acidification and elevated concentrations and transport of Fe, Al, Mn, and trace metals during storm flow; (2) elevated concentrations of Fe, Mn, Co, Cu, Pb, Ni, and Zn in streambed sediments relative to unmined areas and to toxicity guidelines for aquatic invertebrates and fish; and (3) elevated concentrations of metals in fish tissue, notably Zn. The metals are ubiquitous in the fine fraction (water column are correlated, and those for storm flow typically exceed base flow. Nevertheless, the metals concentrations are poorly correlated with stream flow because concentrations of suspended solids and total metals typically peak prior to peak stream stage. In contrast, SO4, specific conductance and pH are inversely correlated with stream flow as a result of dilution of poorly buffered stream water with weakly acidic storm runoff derived mainly from low-pH rainfall. Declines in pH to values approaching 5.0 during storm flow events or declines in redox potential during burial of sediment could result in the remobilization of metals associated with suspended solids and streambed deposits.

  5. Water-quality trends for a stream draining the Southern Anthracite Field, Pennsylvania

    Science.gov (United States)

    Cravotta, C.A.; Bilger, Michael D.

    2001-01-01

    Stream flow, chemical and biological data for the northern part of Swatara Creek, which drains a 112 km2 area in the Southern Anthracite Field of eastern Pennsylvania, indicate progressive improvement in water quality since 1959, after which most mines in the watershed had been flooded. Drainage from the flooded mines contributes substantially to base flow in Swatara Creek. Beginning in 1995, a variety of treatment systems and surface reclamation were implemented at some of the abandoned mines. At Ravine, Pa., immediately downstream of the mined area, median SO4 concentration declined from about 150 mg l-1 in 1959 to 75 mg l-1 in 1999 while pH increased from acidic to near-neutral values (medians: c. pH 4 before 1975; c. pH 6 after 1975). Fish populations rebounded from non-existent during 1959-1990 to 21 species identified in 1999. Nevertheless, recent monitoring indicates (1) episodic acidification and elevated concentrations and transport of Fe, Al, Mn, and trace metals during storm flow; (2) elevated concentrations of Fe, Mn, Co, Cu, Pb, Ni, and Zn in streambed sediments relative to unmined areas and to toxicity guidelines for aquatic invertebrates and fish; and (3) elevated concentrations of metals in fish tissue, notably Zn. The metals are ubiquitous in the fine fraction (mining-affected tributaries and the main stem of Swatara Creek. As a result of scour and transport of streambed deposits, concentrations of suspended solids and total metals in the water column are correlated, and those for storm flow typically exceed base flow. Nevertheless, the metals concentrations are poorly correlated with stream flow because concentrations of suspended solids and total metals typically peak prior to peak stream stage. In contrast, SO4, specific conductance and pH are inversely correlated with stream flow as a result of dilution of poorly buffered stream water with weakly acidic storm runoff derived mainly from low-pH rainfall. Declines in pH to values approaching 5

  6. An investigation of the stable isotopes, geochemistry and morphology of major streams in Dominica, Lesser Antilles: 2014 - 2017

    Science.gov (United States)

    Kopas, D. C.; Joseph, E. P.; Frey, H. M.

    2017-12-01

    The island of Dominica is a recently active (pH and temperature, were recorded and water samples taken and analyzed for alkalinity, major elements (cations and anions), trace elements and stable isotopes (carbon, deuterium, and oxygen). Variations in water chemistry and river morphology were compared to various parameters, including precipitation, landslide locations, and lithology for each of the catchments. Within the study period, on August 27th, 2015, a significant tropical storm, Erika, made landfall in Dominica, depositing more than 500 mm of rainfall in 10 hours. There was little infiltration of the rainwater (over 50-60% run-off), which resulted in significant landslides, flash floods and damage to infrastructure and loss of life. Despite the obvious morphologic changes to the streams and high discharge during the storm event, preliminary analysis has shown little change in major stream geochemistry following the passage of Tropical Storm Erika. The 10-month time gap between the storm and the post-storm field sampling in June 2016 may be a factor of why geochemical changes were not observed. One of the most significant variations of stream composition during the study period was annual shifts in δD between -1.3 to -5.8 ‰ and δ18O between -1.98 to -2.61 ‰. A possible factor influencing the δ18O of surface waters is seasonal variation in rainfall. The dominant control on precipitation δ18O values is the amount effect, whereby rainfall amount and δ18O are inversely correlated. This relationship is a proxy for changes in δ18O values of surface waters. The data also suggest that hydrothermal fluids are not a prominent contributor to Dominican rivers, despite the presence of active volcanism and numerous hydrothermal systems on the island. The exceptions are the White River, which drains the Valley of Desolation and Boiling Lake and the Lamothe River, which drains the Cold Soufrierre.

  7. Cover Crops for Managing Stream Water Quantity and Improving Stream Water Quality of Non-Tile Drained Paired Watersheds

    Directory of Open Access Journals (Sweden)

    Gurbir Singh

    2018-04-01

    Full Text Available In the Midwestern United States, cover crops are being promoted as a best management practice for managing nutrient and sediment losses from agricultural fields through surface and subsurface water movement. To date, the water quality benefits of cover crops have been inferred primarily from plot scale studies. This project is one of the first to analyze the impacts of cover crops on stream water quality at the watershed scale. The objective of this research was to evaluate nitrogen, phosphorus, and sediment loss in stream water from a no-till corn-soybean rotation planted with winter cover crops cereal rye (Secale cereale and hairy vetch (Vicia villosa in non-tile drained paired watersheds in Illinois, USA. The paired watersheds are under mixed land use (agriculture, forest, and pasture. The control watershed had 27 ha of row-crop agriculture, and the treatment watershed had 42 ha of row crop agriculture with cover crop treatment (CC-treatment. During a 4-year calibration period, 42 storm events were collected and Event Mean Concentrations (EMCs for each storm event were calculated for total suspended solids (TSS, nitrate-N (NO3-N, ammonia-N (NH4-N, dissolved reactive phosphorus (DRP, and total discharge. Predictive regression equations developed from the calibration period were used for calculating TSS, NO3-N, NH4-N, and DRP losses of surface runoff for the CC-treatment watershed. The treatment period consisted of total 18 storm events, seven of which were collected during the cereal rye, eight in the hairy vetch cover crop season and three during cash crop season. Cover crops reduced TSS and discharge by 33% and 34%, respectively in the CC-treatment watershed during the treatment period. However, surprisingly, EMCs for NO3-N, NH4-N, and DRP did not decrease. Stream discharge from the paired-watersheds will continue to be monitored to determine if the current water quality results hold or new patterns emerge.

  8. Globalization, Brain Drain, and Development

    OpenAIRE

    Docquier, Frédéric; Rapoport, Hillel

    2012-01-01

    This paper reviews four decades of economics research on the brain drain, with a focus on recent contributions and on development issues. We first assess the magnitude, intensity, and determinants of the brain drain, showing that brain drain (or high-skill) migration is becoming a dominant pattern of international migration and a major aspect of globalization. We then use a stylized growth model to analyze the various channels through which a brain drain affects the sending countries and revi...

  9. The Validation of a No-Drain Policy After Thoracoscopic Major Lung Resection.

    Science.gov (United States)

    Murakami, Junichi; Ueda, Kazuhiro; Tanaka, Toshiki; Kobayashi, Taiga; Kunihiro, Yoshie; Hamano, Kimikazu

    2017-09-01

    The omission of postoperative chest tube drainage may contribute to early recovery after thoracoscopic major lung resection; however, a validation study is necessary before the dissemination of a selective drain policy. A total of 162 patients who underwent thoracoscopic anatomical lung resection for lung tumors were enrolled in this study. Alveolar air leaks were sealed with a combination of bioabsorbable mesh and fibrin glue. The chest tube was removed just after the removal of the tracheal tube in selected patients in whom complete pneumostasis was obtained. Alveolar air leaks were identified in 112 (69%) of the 162 patients in an intraoperative water-seal test performed just after anatomical lung resection. The chest tube could be removed in the operating room in 102 (63%) of the 162 patients. There were no cases of 30-day postoperative mortality or in-hospital death. None of the 102 patients who did not undergo postoperative chest tube placement required redrainage for a subsequent air leak or subcutaneous emphysema. The mean length of postoperative hospitalization was shorter in patients who had not undergone postoperative chest tube placement than in those who had. The omission of chest tube placement was associated with a reduction in the visual analog scale for pain from postoperative day 0 until postoperative day 3, in comparison with patients who underwent chest tube placement. The outcome of our validation cohort revealed that a no-drain policy is safe in selected patients undergoing thoracoscopic major lung resection and that it may contribute to an early recovery. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  10. Factors affecting distribution of wood, detritus, and sediment in headwater streams draining managed young-growth red alder - Conifer forests in southeast Alaska

    Science.gov (United States)

    Gomi, T.; Johnson, A.C.; Deal, R.L.; Hennon, P.E.; Orlikowska, E.H.; Wipfli, M.S.

    2006-01-01

    Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) - conifer riparian forests (40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder-conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width (0.5-3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels. ?? 2006 NRC.

  11. Pesticide transport to tile-drained fields in SWAT model – macropore flow and sediment

    DEFF Research Database (Denmark)

    Lu, Shenglan; Trolle, Dennis; Blicher-Mathiesen, Gitte

    2015-01-01

    Tool (SWAT) to simulate transport of both mobile (e.g. Bentazon) and strongly sorbed (e.g. Diuron) pesticides in tile drains. Macropore flow is initiated when soil water content exceeds a threshold and rainfall intensity exceeds infiltration capacity. The amount of macropore flow is calculated...... to macropore sediment transport. Simulated tile drain discharge, sediment and pesticide loads are calibrated against data from intensively monitored tile-drained fields and streams in Denmark....

  12. Prediction of phosphorus loads in an artificially drained lowland catchment using a modified SWAT model

    Science.gov (United States)

    Bauwe, Andreas; Eckhardt, Kai-Uwe; Lennartz, Bernd

    2017-04-01

    Eutrophication is still one of the main environmental problems in the Baltic Sea. Currently, agricultural diffuse sources constitute the major portion of phosphorus (P) fluxes to the Baltic Sea and have to be reduced to achieve the HELCOM targets and improve the ecological status. Eco-hydrological models are suitable tools to identify sources of nutrients and possible measures aiming at reducing nutrient loads into surface waters. In this study, the Soil and Water Assessment Tool (SWAT) was applied to the Warnow river basin (3300 km2), the second largest watershed in Germany discharging into the Baltic Sea. The Warnow river basin is located in northeastern Germany and characterized by lowlands with a high proportion of artificially drained areas. The aim of this study were (i) to estimate P loadings for individual flow fractions (point sources, surface runoff, tile flow, groundwater flow), spatially distributed on sub-basin scale. Since the official version of SWAT does not allow for the modeling of P in tile drains, we tested (ii) two different approaches of simulating P in tile drains by changing the SWAT source code. The SWAT source code was modified so that (i) the soluble P concentration of the groundwater was transferred to the tile water and (ii) the soluble P in the soil was transferred to the tiles. The SWAT model was first calibrated (2002-2011) and validated (1992-2001) for stream flow at 7 headwater catchments at a daily time scale. Based on this, the stream flow at the outlet of the Warnow river basin was simulated. Performance statistics indicated at least satisfactory model results for each sub-basin. Breaking down the discharge into flow constituents, it becomes visible that stream flow is mainly governed by groundwater and tile flow. Due to the topographic situation with gentle slopes, surface runoff played only a minor role. Results further indicate that the prediction of soluble P loads was improved by the modified SWAT versions. Major sources of

  13. Controls on methane concentrations and fluxes in streams draining human-dominated landscapes

    Science.gov (United States)

    Crawford, John T.; Stanley, Emily H.

    2016-01-01

    Streams and rivers are active processors of carbon, leading to significant emissions of CO2 and possibly CH4 to the atmosphere. Patterns and controls of CH4 in fluvial ecosystems remain relatively poorly understood. Furthermore, little is known regarding how major human impacts to fluvial ecosystems may be transforming their role as CH4 producers and emitters. Here, we examine the consequences of two distinct ecosystem changes as a result of human land use: increased nutrient loading (primarily as nitrate), and increased sediment loading and deposition of fine particles in the benthic zone. We did not find support for the hypothesis that enhanced nitrate loading down-regulates methane production via thermodynamic or toxic effects. We did find strong evidence that increased sedimentation and enhanced organic matter content of the benthos lead to greater methane production (diffusive + ebullitive flux) relative to pristine fluvial systems in northern Wisconsin (upper Midwest, USA). Overall, streams in a human-dominated landscape of southern Wisconsin were major regional sources of CH4 to the atmosphere, equivalent to ~20% of dairy cattle emissions, or ~50% of a landfill’s annual emissions. We suggest that restoration of the benthic environment (reduced fine deposits) could lead to reduced CH4 emissions, while decreasing nutrient loading is likely to have limited impacts to this ecosystem process.

  14. Use of ESI-FTICR-MS to Characterize Dissolved Organic Matter in Headwater Streams Draining Forest-Dominated and Pasture-Dominated Watersheds.

    Directory of Open Access Journals (Sweden)

    YueHan Lu

    Full Text Available Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS has proven to be a powerful technique revealing complexity and diversity of natural DOM molecules, but its application to DOM analysis in grazing-impacted agricultural systems remains scarce. In the present study, we presented a case study of using ESI-FTICR-MS in analyzing DOM from four headwater streams draining forest- or pasture-dominated watersheds in Virginia, USA. In all samples, most formulas were CHO compounds (71.8-87.9%, with other molecular series (CHOS, CHON, CHONS, and CHOP (N, S accounting for only minor fractions. All samples were dominated by molecules falling in the lignin-like region (H/C = 0.7-1.5, O/C = 0.1-0.67, suggesting the predominance of allochthonous, terrestrial plant-derived DOM. Relative to the two pasture streams, DOM formulas in the two forest streams were more similar, based on Jaccard similarity coefficients and nonmetric multidimensional scaling calculated from Bray-Curtis distance. Formulas from the pasture streams were characterized by lower proportions of aromatic formulas and lower unsaturation, suggesting that the allochthonous versus autochthonous contributions of organic matter to streams were modified by pasture land use. The number of condensed aromatic structures (CAS was higher for the forest streams, which is possibly due to the controlled burning in the forest-dominated watersheds and suggests that black carbon was mobilized from soils to streams. During 15-day biodegradation experiments, DOM from the two pasture streams was altered to a greater extent than DOM from the forest streams, with formulas with H/C and O/C ranges similar to protein (H/C = 1.5-2.2, O/C = 0.3-0.67, lipid (H/C = 1.5-2.0, O/C = 0-0.3, and unsaturated hydrocarbon (H/C = 0.7-1.5, O/C = 0-0.1 being the most bioreactive groups. Aromatic compound formulas including CAS were preferentially removed during combined light

  15. Identifying environmental and geochemical variables governing metal concentrations in a stream draining headwaters in NW Spain

    International Nuclear Information System (INIS)

    Soto-Varela, F.; Rodríguez-Blanco, M.L.; Taboada-Castro, M.M.; Taboada-Castro, M.T.

    2014-01-01

    Highlights: • All metals occur in association with suspended sediment. • DOC and SS appeared to influence the partitioning of metals. • The SS was a good predictor of particulate metal levels. • The most important variable to explain storm-event K D for Al and Fe is DOC. • Enrichment factor values suggest a natural origin for the particulate metals. - Abstract: Headwater stream, draining from a rural catchment in NW Spain, was sampled during baseflow and storm-event conditions to investigate the temporal variability in dissolved and particulate Al, Fe, Mn, Cu and Zn concentrations and the role of discharge (Q), pH, dissolved organic carbon (DOC) and suspended sediment (SS) in the transport of dissolved and particulate metals. Under baseflow and storm-event conditions, concentrations of the five metals were highly variable. The results of this study reveal that all metal concentrations are correlated with SS. DOC and SS appeared to influence both the metal concentrations and the partitioning of metals between dissolved and particulate. The SS was a good predictor of particulate metal levels. Distribution coefficients (K D ) were similar between metals (4.72–6.55) and did not change significantly as a function of discharge regime. Stepwise multiple linear regression analysis reveals that the most important variable to explain storm-event K D for Al and Fe is DOC. The positive relationships found between metals, in each fraction, indicate that these elements mainly come from the same source. Metal concentrations in the stream were relatively low

  16. The Ribble/Wyre observatory: Major, minor and trace elements in rivers draining from rural headwaters to the heartlands of the NW England historic industrial base

    International Nuclear Information System (INIS)

    Neal, Colin; Rowland, Phil; Scholefield, Paul; Vincent, Colin; Woods, Clive; Sleep, Darren

    2011-01-01

    Information on a new observatory study of the water quality of two major river basins in northwestern England (the Ribble and Wyre) is presented. It covers upland, intermediate and lowland environments of contrasting pollution history with sufficient detail to examine transitional gradients. The upland rivers drain acidic soils subjected to long-term acidic deposition. Nonetheless, the acidic runoff from the soils is largely neutralised by high alkalinity groundwaters, although the rivers retain, perhaps as colloids, elements such as Al and Fe that are mobilised under acid conditions. The lowland rivers are contaminated and have variable water quality due to variable urban/industrial point and diffuse inputs reflecting local and regional differences in historic and contemporary sources. For most determinands, pollutant concentrations are not a major cause for concern although phosphate levels remain high. Set against earlier studies for other regions, there may be a general decline in pollutant levels and this is most clearly observed for boron where effluent inputs have declined significantly due to reductions in household products that are flushed down the drain. High concentrations of sodium and chloride occurred briefly after a severe cold spell due to flushing of road salts. A major inventory for water quality within rural, urban, industrial and agricultural typologies is provided within data summary attachments for over 50 water quality determinands. Within the next year, the full dataset will be made available from the CEH website. This, with ongoing monitoring, represents a platform for water quality studies across a wide range of catchment typologies pertinent to environmental management of clean and impacted systems within the UK. The study provides a base of research 'from source to sea' including extensions to the estuary and open sea for a semi-confined basin, the Irish Sea, where there are many issues of pollution inputs and contamination. - Research

  17. The Ribble/Wyre observatory: Major, minor and trace elements in rivers draining from rural headwaters to the heartlands of the NW England historic industrial base

    Energy Technology Data Exchange (ETDEWEB)

    Neal, Colin [Centre for Ecology and Hydrology, Wallingford, Crowmarsh Gifford, Wallingford, OXON, OX10 8BB (United Kingdom); Rowland, Phil, E-mail: apr@ceh.ac.uk [Centre for Ecology and Hydrology, Lancaster. Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP (United Kingdom); Scholefield, Paul; Vincent, Colin; Woods, Clive; Sleep, Darren [Centre for Ecology and Hydrology, Lancaster. Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP (United Kingdom)

    2011-03-15

    Information on a new observatory study of the water quality of two major river basins in northwestern England (the Ribble and Wyre) is presented. It covers upland, intermediate and lowland environments of contrasting pollution history with sufficient detail to examine transitional gradients. The upland rivers drain acidic soils subjected to long-term acidic deposition. Nonetheless, the acidic runoff from the soils is largely neutralised by high alkalinity groundwaters, although the rivers retain, perhaps as colloids, elements such as Al and Fe that are mobilised under acid conditions. The lowland rivers are contaminated and have variable water quality due to variable urban/industrial point and diffuse inputs reflecting local and regional differences in historic and contemporary sources. For most determinands, pollutant concentrations are not a major cause for concern although phosphate levels remain high. Set against earlier studies for other regions, there may be a general decline in pollutant levels and this is most clearly observed for boron where effluent inputs have declined significantly due to reductions in household products that are flushed down the drain. High concentrations of sodium and chloride occurred briefly after a severe cold spell due to flushing of road salts. A major inventory for water quality within rural, urban, industrial and agricultural typologies is provided within data summary attachments for over 50 water quality determinands. Within the next year, the full dataset will be made available from the CEH website. This, with ongoing monitoring, represents a platform for water quality studies across a wide range of catchment typologies pertinent to environmental management of clean and impacted systems within the UK. The study provides a base of research 'from source to sea' including extensions to the estuary and open sea for a semi-confined basin, the Irish Sea, where there are many issues of pollution inputs and contamination

  18. Assessment of Energetic Compounds, Semi-volatile Organic Compounds, and Trace Elements in Streambed Sediment and Stream Water from Streams Draining Munitions Firing Points and Impact Areas, Fort Riley, Kansas, 2007-08

    Science.gov (United States)

    Coiner, R.L.; Pope, L.M.; Mehl, H.E.

    2010-01-01

    An assessment of energetic compounds (explosive and propellant residues) and associated semi-volatile organic compounds (SVOCs) and trace elements in streambed sediment and stream water from streams draining munitions firing points and impact areas at Fort Riley, northeast Kansas, was performed during 2007-08 by the U.S. Geological Survey (USGS) in cooperation with the U.S. Army. Streambed sediment from 16 sampling sites and stream-water samples from 5 sites were collected at or near Fort Riley and analyzed for as many as 17 energetic compounds, 65 SVOCs, and 27 trace elements. None of the energetic compounds or SVOCs were detected in streambed sediment collected from sites within the Fort Riley Military Reservation. This may indicate that these compounds either are not transported from dispersal areas or that analytical methods are not sensitive enough to detect the small concentrations that may be transported. Concentrations of munitions-associated trace elements did not exceed sediment-quality guidelines recommended by the U.S. Environmental Protection Agency (USEPA) and are not indicative of contamination of streambed sediment at selected streambed sampling sites, at least in regards to movement from dispersal areas. Analytical results of stream-water samples provided little evidence of contamination by energetic compounds, SVOCs, or associated trace elements. Perchlorate was detected in 19 of 20 stream-water samples at concentrations ranging from an estimated 0.057 to an estimated 0.236 ug/L (micrograms per liter) with a median concentration of an estimated 0.114 ug/L, substantially less than the USEPA Interim Health Advisory criterion (15 ug/L), and is in the range of documented background concentrations. Because of these small concentrations and possible natural sources (precipitation and groundwater), it is likely that the occurrence of perchlorate in stream water is naturally occurring, although a definitive identification of the source of perchlorate in

  19. SPATIO-TEMPORAL VARIATIONS IN MACROINVERTEBRATE ASSEMBLAGES OF NEW CALEDONIAN STREAMS.

    Directory of Open Access Journals (Sweden)

    MARY N. J.

    2002-01-01

    Full Text Available Forty-one sites located on 14 New Caledonian streams were surveyed four times between October 1996 and October 1997 in order to examine the spatial and temporal changes in the structure of the benthic macroinvertebrate communities. About 250 000 invertebrates representing 167 taxa were collected in the streams. Seventy-five percent of identified taxa and 67% of individuals were insects. Major spatial and temporal changes in the composition of the fauna were detected by multivariate analyses (ordination and classification. Overall, the number of individuals was significantly higher in the dry season (October than in the wetter seasons (January and June. However, a low temporal variability was detected in the structure of benthic communities during the sampling period. A cluster analysis based on taxonomic composition separated five groups of sites in relation with rock type, land use, and geographic characteristics. Several metrics (total invertebrate density, taxon richness, relative abundance of major invertebrate groups, diversity indices were used to characterize each group of sites. Forested streams, where the highest specific diversity occurred, represented the most speciose habitat for benthic fauna. A less rich and abundant fauna occurred in streams draining ultramafic rocks probably because of their low content in food resources and organic matter.

  20. Plant litter dynamics in the forest-stream interface: precipitation is a major control across tropical biomes.

    Science.gov (United States)

    Tonin, Alan M; Gonçalves, José F; Bambi, Paulino; Couceiro, Sheyla R M; Feitoza, Lorrane A M; Fontana, Lucas E; Hamada, Neusa; Hepp, Luiz U; Lezan-Kowalczuk, Vânia G; Leite, Gustavo F M; Lemes-Silva, Aurea L; Lisboa, Leonardo K; Loureiro, Rafael C; Martins, Renato T; Medeiros, Adriana O; Morais, Paula B; Moretto, Yara; Oliveria, Patrícia C A; Pereira, Evelyn B; Ferreira, Lidiane P; Pérez, Javier; Petrucio, Mauricio M; Reis, Deusiano F; S Rezende, Renan; Roque, Nadia; Santos, Luiz E P; Siegloch, Ana E; Tonello, Gabriela; Boyero, Luz

    2017-09-07

    Riparian plant litter is a major energy source for forested streams across the world and its decomposition has repercussions on nutrient cycling, food webs and ecosystem functioning. However, we know little about plant litter dynamics in tropical streams, even though the tropics occupy 40% of the Earth's land surface. Here we investigated spatial and temporal (along a year cycle) patterns of litter inputs and storage in multiple streams of three tropical biomes in Brazil (Atlantic forest, Amazon forest and Cerrado savanna), predicting major differences among biomes in relation to temperature and precipitation regimes. Precipitation explained most of litter inputs and storage, which were generally higher in more humid biomes (litterfall: 384, 422 and 308 g m -2 y -1 , storage: 55, 113 and 38 g m -2 , on average in Atlantic forest, Amazon and Cerrado, respectively). Temporal dynamics varied across biomes in relation to precipitation and temperature, with uniform litter inputs but seasonal storage in Atlantic forest streams, seasonal inputs in Amazon and Cerrado streams, and aseasonal storage in Amazon streams. Our findings suggest that litter dynamics vary greatly within the tropics, but point to the major role of precipitation, which contrasts with the main influence of temperature in temperate areas.

  1. NITROUS OXIDE CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

    Science.gov (United States)

    We are measuring the dissolved nitrous oxide concentration in 17 headwater streams in the South Fork Broad River, Georgia watershed on a monthly basis. The selected small streams drain watersheds dominated by forest, pasture, developed, or mixed land uses. Nitrous oxide concentr...

  2. Drains and Drainage Capabilities: Quantitative Analysis of Drain Efficiencies

    Directory of Open Access Journals (Sweden)

    Andaç Aykan

    2016-03-01

    Full Text Available Objective: In this study, it was aimed to compare the efficiency of the same type of but different-sized silicone drains at different surgical procedures. Material and Methods: Twenty-four patients, who had different diagnoses and were operated between 2011 and 2013, were included. In all patients, 7- and 10-mm silicone-ended, Jackson–Pratt drains were used. Drains that were under 30 cc/day removed. The connection tube and perforated silicone end were examined due to the clot content. All drain efficiencies were calculated, and the results were statistically analyzed. Results: Seven of the 24 patients (29.2% were males and 17 (70.8% were females; the mean age was 39.0±11.4 years. Totally, 49 drains were used, of which 25 (51% were 7 mm and 24 (49% were 10 mm in size. Median removal time was the 5th day (2–12 for the 7-mm drains and the 6th day (3–14 for the 10-mm drains. There was no statistically significant difference between the groups for drain removal time (p=0.268. Further, there was no difference at the connection tube and silicone end for clot content between the 7- and 10-mm drains (p=0.58. For the drainage volume and efficiency, no difference was observed between the groups (p=0.146. Conclusion: In this study it was observed that there is no difference in the drainage volume and efficiency between different-sized Jackson–Pratt drains.

  3. The effect of industrial effluent stream on the groundwater

    International Nuclear Information System (INIS)

    Yasar, A.; Ahmad, N.; Chaudhry, M.N.; Sarwar, M.

    2005-01-01

    This study was performed to investigate the effect of the industrial wastewater stream on the groundwater. Wastewater was characterized in terms of inorganic and organic constituents. Inorganic constituents included Na/sup +/, Ca/sup 2+/ K/sup +/, Cl/sup -/, NO/sub 3//sup -/ and SO/sub 4//sup 2-/ coupled with heavy metal elements such as, Cd, Cr, Pb, Mn, Cu, Ni, Fe and In. Organic load of the stream was determined in terms of chemical oxygen demand (COD), biological oxygen demand (BOD/sub 5/) and ammonia-nitrogen (NH/sub 3/-N) contents. Other characteristics were pH, electrical conductivity (EC) and total dissolved solids (TDS). The correlation coefficients between quality parameter pairs of stream water and groundwater were determined to ascertain the source of groundwater contamination. At station 1, BOD/sub 5/ and COD contents were 20 times and Cr concentration was 10 times higher than the permissible limits for stream water [1]. Contents of these parameters reflected the level of industrial and domestic pollution coming from India. However, large variations in the levels of these parameters at down stream sites of the drain were characteristic of type and nature of industrial effluents and domestic sewage joining the stream. Analysis results of more than one hundred groundwater samples from shallow and deep wells around the drain showed that groundwater of shallow aquifers was contaminated due to drain water. A comparison of the contents of these parameters in shallow wells with WHO standards showed that some parameters such as turbidity, TDS, Na/sup +/, F -and heavy metals like Cr were found higher than the permissible limits. (author)

  4. Trends in nitrogen concentrations and load in 48 minor streams draining intensively farmed Danish catchments, 1990-2014. How can the observed trend be explained?

    Science.gov (United States)

    Windolf, Jørgen; Børgesen, Christen; Blicher-Mathiesen, Gitte; Kronvang, Brian; Larsen, Søren E.; Tornbjerg, Henrik

    2016-04-01

    The total land-based nitrogen load to Danish coastal waters has decreased by 50% since 1990 through a reduction of the outlet of nitrogen from sewage point sources and diffuse sources. On a national scale nitrogen load from diffuse sources, has been reduced by 43% , mainly due to limitation of the amount of N input to different crops, rules for timing and application of manure, mandatory demands for catch crops and restoration of wetlands. The latter increasing the nitrogen retention capacity in surface waters. However, on a local scale huge variations exist in the reduction of the diffuse nitrogen load. Since 1990, an important part of the Danish national monitoring program on the aquatic environment (NOVANA) has been directed at quantifying the nitrogen concentrations and load in 48 minor streams draining small intensively farmed catchments. The 48 catchments have a mean size of 18 km2, farmed area constitutes more than 60% of the catchment area and the catchments have no significant outlets of sewage to the streams. The statistical trend results (based on a seasonal Mann-Kendall) from these 48 streams show a 9-65% reduction in the diffuse nitrogen load (mean: 48%). The large differences in trends in the diffuse N load are related to differences in catchment-specific variables such as nitrogen surpluses, nitrogen leaching from the root zone, hydrogeology and nitrogen retention in ground and surface waters.

  5. Spatio-temporal variation in stream water chemistry in a tropical urban watershed

    Science.gov (United States)

    A. Ramirez; K.G. Rosas; A.E. Lugo; O.M. Ramos-Gonzalez

    2014-01-01

    Urban activities and related infrastructure alter the natural patterns of stream physical and chemical conditions. According to the Urban Stream Syndrome, streams draining urban landscapes are characterized by high concentrations of nutrients and ions, and might have elevated water temperatures and variable oxygen concentrations. Here, we report temporal and spatial...

  6. The effects of human land use on flow regime and water chemistry of headwater streams in the highlands of Chiapas

    Directory of Open Access Journals (Sweden)

    Castillo M.M.

    2013-03-01

    Full Text Available We studied the effects of land use changes on flow regime and water chemistry of headwater streams in the highlands of Chiapas, a region in southern Mexico that has experienced high rates of deforestation in the last decades. Samples for water chemistry were collected and discharge was measured between September 2007 and August 2008 at eight streams that differed in the land uses of their riparian and catchment areas, including streams draining protected forested areas. Streams with high forest cover (>70% in their catchments maintained flow through the year. Streams draining more disturbed catchments exhibited reduced or no flow for 4 − 6 months during the dry season. Nitrate concentrations were lower at streams draining forested catchments while highest concentrations were measured where conventional agriculture covered a high proportion of the catchment and riparian zone. Highest phosphorus concentrations occurred at the catchment where poultry manure was applied as fertilizer. Differences between forest streams and those draining disturbed areas were correlated with the proportion of forest and agriculture in the riparian zone. Variation in stream variables among sampling dates was lower at the forest sites than at the more disturbed study streams. Conversion of forest into agriculture and urban areas is affecting flow regime and increasing nutrient concentrations, although the magnitude of the impacts are influenced by the type of agricultural practices and the alteration of the riparian zone.

  7. Low-flow characteristics of streams in the Puget Sound region, Washington

    Science.gov (United States)

    Hidaka, F.T.

    1973-01-01

    Periods of low streamflow are usually the most critical factor in relation to most water uses. The purpose of this report is to present data on low-flow characteristics of streams in the Puget Sound region, Washington, and to briefly explain some of the factors that influence low flow in the various basins. Presented are data on low-flow frequencies of streams in the Puget Sound region, as gathered at 150 gaging stations. Four indexes were computed from the flow-flow-frequency curves and were used as a basis to compare the low-flow characteristics of the streams. The indexes are the (1) low-flow-yield index, expressed in unit runoff per square mile; (2) base-flow index, or the ratio of the median 7-day low flow to the average discharge; (3) slope index, or slope of annual 7-day low-flow-frequency curve; and (4) spacing index, or spread between the 7-day and 183-day low-flow-frequency curves. The indexes showed a wide variation between streams due to the complex interrelation between climate, topography, and geology. The largest low-flow-yield indexes determined--greater than 1.5 cfs (cubic feet per second) per square mile--were for streams that head at high altitudes in the Cascade and Olympic Mountains and have their sources at glaciers. The smallest low-flow-yield indexes--less than 0.5 cfs per square mile--were for the small streams that drain the lowlands adjacent to Puget Sound. Indexes between the two extremes were for nonglacial streams that head at fairly high altitudes in areas of abundant precipitation. The base-flow index has variations that can be attributed to a basin's hydrogeology, with very little influence from climate. The largest base-flow indexes were obtained for streams draining permeable unconsolidated glacial and alluvial sediments in parts of the lowlands adjacent to Puget Sound. Large volume of ground water in these materials sustain flows during late summer. The smallest indexes were computed for streams draining areas underlain by

  8. NITRATE AND NITROUS OXIDE CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

    Science.gov (United States)

    We are measuring dissolved nitrate and nitrous oxide concentrations and related parameters in 17 headwater streams in the South Fork Broad River, Georgia watershed on a monthly basis. The selected small streams drain watersheds dominated by forest, pasture, residential, or mixed...

  9. The Midwest Stream Quality Assessment—Influences of human activities on streams

    Science.gov (United States)

    Van Metre, Peter C.; Mahler, Barbara J.; Carlisle, Daren M.; Coles, James F.

    2018-04-16

    Healthy streams and the fish and other organisms that live in them contribute to our quality of life. Extensive modification of the landscape in the Midwestern United States, however, has profoundly affected the condition of streams. Row crops and pavement have replaced grasslands and woodlands, streams have been straightened, and wetlands and fields have been drained. Runoff from agricultural and urban land brings sediment and chemicals to streams. What is the chemical, physical, and biological condition of Midwestern streams? Which physical and chemical stressors are adversely affecting biological communities, what are their origins, and how might we lessen or avoid their adverse effects?In 2013, the U.S. Geological Survey (USGS) conducted the Midwest Stream Quality Assessment to evaluate how human activities affect the biological condition of Midwestern streams. In collaboration with the U.S. Environmental Protection Agency National Rivers and Streams Assessment, the USGS sampled 100 streams, chosen to be representative of the different types of watersheds in the region. Biological condition was evaluated based on the number and diversity of fish, algae, and invertebrates in the streams. Changes to the physical habitat and chemical characteristics of the streams—“stressors”—were assessed, and their relation to landscape factors and biological condition was explored by using mathematical models. The data and models help us to better understand how the human activities on the landscape are affecting streams in the region.

  10. Mercury Pollution Studies of Some Rivers Draining the Bibiani-Anwiaso-Bekwai Mining Community of South Western Ghana

    OpenAIRE

    V.K. Nartey; L.K. Doamekpor; S. Sarpong-Kumankuma; T. Akabzaa; F.K. Nyame; J.K. Kutor; D. Adotey

    2011-01-01

    The project assessed the extent of mercury pollution of some rivers that drain the Bibiani-Anwiaso- Bekwai district which is a typical mining community in the south western part of Ghana. In the study, surfacewater and sediment samples were collected from seven streams that drain this mining community and analyzed for total mercury, organic mercury and elemental mercury. Mercury concentrations of non-filtered water was determined using the ICP-OES after reduction with stannous chloride (SnCl2...

  11. Does the suction drain diameter matter? Bleeding analysis after total knee replacement comparing different suction drain gauges

    Directory of Open Access Journals (Sweden)

    Marcos George de Souza Leao

    Full Text Available ABSTRACT OBJECTIVES: To evaluate bleeding and the estimated blood loss in patients who underwent total knee replacement (TKR with different closed suction drains (3.2-mm and 4.8-mm gauge. METHODS: This was a randomized controlled trial with 22 patients who underwent TKR and were divided into two groups: Group I, with 11 patients in whom the 3.2-mm suction drain was used, and Group II, with 11 patients in whom the 4.8-mm suction drain was used. The hematocrit was measured after 24, 48 and 72 h after surgery in order to calculate the estimated blood loss. The drained volume was measured 3, 6, 12, 24, and 48 h after TKR, and thereafter both groups were compared. RESULTS: Regarding the hematocrit, there were no differences between groups in measured periods (24, 48, and 72 h after surgery. The total bleeding measured at the suction drains within 48 h was higher in Group II, with a statistically significant difference (p = 0.005; in the first 24 h, there was major bleeding in Group II (mean 893 mL, with a significant difference (p = 0.004. Between 24 and 48 h, there was no statistically significant difference in both groups (p = 0.710. The total estimated bleeding was higher in Group I, with mean of 463 mL, versus 409 mL in Group II, with no statistical significance (p = 0.394. CONCLUSIONS: Bleeding was higher in the group that used the 4.8 mm gauge suction drain, with no differences in hematocrit and estimated blood loss.

  12. Plant litter dynamics in the forest-stream interface: precipitation is a major control across tropical biomes

    OpenAIRE

    Tonin, Alan M.; Gon?alves, Jos? F.; Bambi, Paulino; Couceiro, Sheyla R. M.; Feitoza, Lorrane A. M.; Fontana, Lucas E.; Hamada, Neusa; Hepp, Luiz U.; Lezan-Kowalczuk, V?nia G.; Leite, Gustavo F. M.; Lemes-Silva, Aurea L.; Lisboa, Leonardo K.; Loureiro, Rafael C.; Martins, Renato T.; Medeiros, Adriana O.

    2017-01-01

    Riparian plant litter is a major energy source for forested streams across the world and its decomposition has repercussions on nutrient cycling, food webs and ecosystem functioning. However, we know little about plant litter dynamics in tropical streams, even?though the tropics occupy 40% of the Earth?s land surface. Here we investigated spatial and temporal (along a year cycle) patterns of litter inputs and storage in multiple streams of three tropical biomes in Brazil (Atlantic forest, Ama...

  13. Current practice patterns of drain usage amongst UK and Irish surgeons performing bilateral breast reductions: Evidence down the drain.

    Science.gov (United States)

    Sugrue, Conor M; McInerney, Niall; Joyce, Cormac W; Jones, Deidre; Hussey, Alan J; Kelly, Jack L; Kerin, Michael J; Regan, Padraic J

    2015-01-01

    Bilateral breast reduction (BBR) is one of the most frequently performed female breast operations. Despite no evidence supporting efficacy of drain usage in BBRs, postoperative insertion is common. Recent high quality evidence demonstrating potential harm from drain use has subsequently challenged this traditional practice. The aim of this study is to assess the current practice patterns of drains usage by Plastic & Reconstructive and Breast Surgeons in UK and Ireland performing BBRs. An 18 question survey was created evaluating various aspects of BBR practice. UK and Irish Plastic & Reconstructive and Breast Surgeons were invited to participate by an email containing a link to a web-based survey. Statistical analysis was performed with student t-test and chi-square test. Two hundred and eleven responding surgeons were analysed, including 80.1% (171/211) Plastic Surgeons and 18.9% (40/211) Breast Surgeons. Of the responding surgeons, 71.6% (151/211) routinely inserted postoperative drains, for a mean of 1.32 days. Drains were used significantly less by surgeons performing ≥20 BBRs (p = 0.02). With the majority of BBRs performed as an inpatient procedure, there was a trend towards less drain usage in surgeons performing this procedure as an outpatient; however, this was not statistically significant (p = 0.07). Even with the high level of evidence demonstrating the safety of BBR without drains, they are still routinely utilised. In an era of evidence- based medicine, surgeons performing breast reductions must adopt the results from scientific research into their clinical practice.

  14. Legacy effects of wildfire on stream thermal regimes and rainbow trout ecology: an integrated analysis of observation and individual-based models

    Science.gov (United States)

    Rosenberger, Amanda E.; Dunham, Jason B.; Neuswanger, Jason R.; Railsback, Steven F.

    2015-01-01

    Management of aquatic resources in fire-prone areas requires understanding of fish species’ responses to wildfire and of the intermediate- and long-term consequences of these disturbances. We examined Rainbow Trout populations in 9 headwater streams 10 y after a major wildfire: 3 with no history of severe wildfire in the watershed (unburned), 3 in severely burned watersheds (burned), and 3 in severely burned watersheds subjected to immediate events that scoured the stream channel and eliminated streamside vegetation (burned and reorganized). Results of a previous study of this system suggested the primary lasting effects of this wildfire history on headwater stream habitat were differences in canopy cover and solar radiation, which led to higher summer stream temperatures. Nevertheless, trout were present throughout streams in burned watersheds. Older age classes were least abundant in streams draining watersheds with a burned and reorganized history, and individuals >1 y old were most abundant in streams draining watersheds with an unburned history. Burned history corresponded with fast growth, low lipid content, and early maturity of Rainbow Trout. We used an individual-based model of Rainbow Trout growth and demographic patterns to determine if temperature interactions with bioenergetics and competition among individuals could lead to observed phenotypic and ecological differences among populations in the absence of other plausible mechanisms. Modeling suggested that moderate warming associated with wildfire and channel disturbance history leads to faster individual growth, which exacerbates competition for limited food, leading to decreases in population densities. The inferred mechanisms from this modeling exercise suggest the transferability of ecological patterns to a variety of temperature-warming scenarios.

  15. Continuous 'Passive' Registration of Non-Point Contaminant Loads Via Agricultural Subsurface Drain Tubes

    Science.gov (United States)

    Rozemeijer, J.; Jansen, S.; de Jonge, H.; Lindblad Vendelboe, A.

    2014-12-01

    Considering their crucial role in water and solute transport, enhanced monitoring and modeling of agricultural subsurface tube drain systems is important for adequate water quality management. For example, previous work in lowland agricultural catchments has shown that subsurface tube drain effluent contributed up to 80% of the annual discharge and 90-92% of the annual NO3 loads from agricultural fields towards the surface water. However, existing monitoring techniques for flow and contaminant loads from tube drains are expensive and labor-intensive. Therefore, despite the unambiguous relevance of this transport route, tube drain monitoring data are scarce. The presented study aimed developing a cheap, simple, and robust method to monitor loads from tube drains. We are now ready to introduce the Flowcap that can be attached to the outlet of tube drains and is capable of registering total flow, contaminant loads, and flow-averaged concentrations. The Flowcap builds on the existing SorbiCells, a modern passive sampling technique that measures average concentrations over longer periods of time (days to months) for various substances. By mounting SorbiCells in our Flowcap, a flow-proportional part of the drain effluent is sampled from the main stream. Laboratory testing yielded good linear relations (R-squared of 0.98) between drainage flow rates and sampling rates. The Flowcap was tested in practice for measuring NO3 loads from two agricultural fields and one glasshouse in the Netherlands. The Flowcap registers contaminant loads from tube drains without any need for housing, electricity, or maintenance. This enables large-scale monitoring of non-point contaminant loads via tube drains, which would facilitate the improvement of contaminant transport models and would yield valuable information for the selection and evaluation of mitigation options to improve water quality.

  16. Natural and anthropogenic sources and processes affecting water chemistry in two South Korean streams

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Woo-Jin [Division of Earth and Environmental Sciences, Korea Basic Science Institute, Cheongwon-gun, Chungbuk 363-883 (Korea, Republic of); Department of Geoscience, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); Ryu, Jong-Sik [Division of Earth and Environmental Sciences, Korea Basic Science Institute, Cheongwon-gun, Chungbuk 363-883 (Korea, Republic of); Mayer, Bernhard [Department of Geoscience, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); Lee, Kwang-Sik, E-mail: kslee@kbsi.re.kr [Division of Earth and Environmental Sciences, Korea Basic Science Institute, Cheongwon-gun, Chungbuk 363-883 (Korea, Republic of); Lee, Sin-Woo [Division of Earth and Environmental Sciences, Korea Basic Science Institute, Cheongwon-gun, Chungbuk 363-883 (Korea, Republic of); Department of Geology, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of)

    2014-07-01

    Acid mine drainage (AMD) in a watershed provides potential sources of pollutants for surface and subsurface waters that can deteriorate water quality. Between March and early August 2011, water samples were collected from two streams in South Korea, one dominantly draining a watershed with carbonate bedrock affected by coal mines and another draining a watershed with silicate bedrock and a relatively undisturbed catchment area. The objective of the study was to identify the sources and processes controlling water chemistry, which was dependent on bedrock and land use. In the Odae stream (OS), the stream in the silicate-dominated catchment, Ca, Na, and HCO{sub 3} were the dominant ions and total dissolved solids (TDS) was low (26.1–165 mg/L). In the Jijang stream (JS), in the carbonate-dominated watershed, TDS (224–434 mg/L) and ion concentrations were typically higher, and Ca and SO{sub 4} were the dominant ions due to carbonate weathering and oxidation of pyrite exposed at coal mines. Dual isotopic compositions of sulfate (δ{sup 34}S{sub SO4} and δ{sup 18}O{sub SO4}) verified that the SO{sub 4} in JS is derived mainly from sulfide mineral oxidation in coal mines. Cl in JS was highest upstream and decreased progressively downstream, which implies that pollutants from recreational facilities in the uppermost part of the catchment are the major source governing Cl concentrations within the discharge basin. Dual isotopic compositions of nitrate (δ{sup 15}N{sub NO3} and δ{sup 18}O{sub NO3}) indicated that NO{sub 3} in JS is attributable to nitrification of soil organic matter but that NO{sub 3} in OS is derived mostly from manure. Additionally, the contributions of potential anthropogenic sources to the two streams were estimated in more detail by using a plot of δ{sup 34}S{sub SO4} and δ{sup 15}N{sub NO3}. This study suggests that the dual isotope approach for sulfate and nitrate is an excellent additional tool for elucidating the sources and processes

  17. Natural and anthropogenic sources and processes affecting water chemistry in two South Korean streams

    International Nuclear Information System (INIS)

    Shin, Woo-Jin; Ryu, Jong-Sik; Mayer, Bernhard; Lee, Kwang-Sik; Lee, Sin-Woo

    2014-01-01

    Acid mine drainage (AMD) in a watershed provides potential sources of pollutants for surface and subsurface waters that can deteriorate water quality. Between March and early August 2011, water samples were collected from two streams in South Korea, one dominantly draining a watershed with carbonate bedrock affected by coal mines and another draining a watershed with silicate bedrock and a relatively undisturbed catchment area. The objective of the study was to identify the sources and processes controlling water chemistry, which was dependent on bedrock and land use. In the Odae stream (OS), the stream in the silicate-dominated catchment, Ca, Na, and HCO 3 were the dominant ions and total dissolved solids (TDS) was low (26.1–165 mg/L). In the Jijang stream (JS), in the carbonate-dominated watershed, TDS (224–434 mg/L) and ion concentrations were typically higher, and Ca and SO 4 were the dominant ions due to carbonate weathering and oxidation of pyrite exposed at coal mines. Dual isotopic compositions of sulfate (δ 34 S SO4 and δ 18 O SO4 ) verified that the SO 4 in JS is derived mainly from sulfide mineral oxidation in coal mines. Cl in JS was highest upstream and decreased progressively downstream, which implies that pollutants from recreational facilities in the uppermost part of the catchment are the major source governing Cl concentrations within the discharge basin. Dual isotopic compositions of nitrate (δ 15 N NO3 and δ 18 O NO3 ) indicated that NO 3 in JS is attributable to nitrification of soil organic matter but that NO 3 in OS is derived mostly from manure. Additionally, the contributions of potential anthropogenic sources to the two streams were estimated in more detail by using a plot of δ 34 S SO4 and δ 15 N NO3 . This study suggests that the dual isotope approach for sulfate and nitrate is an excellent additional tool for elucidating the sources and processes controlling the water chemistry of streams draining watersheds having different

  18. Macroinvertebrate community structure and function along gradients of physical stream quality and pesticide contamination in Danish streams

    DEFF Research Database (Denmark)

    Rasmussen, Jes

    to stream are surface runoff and tile drainage giving rise to short pulses of acute contamination strongly coinciding with high levels of precipitation. Field studies indicate that macroinvertebrate community structure can be impacted by pesticides during spraying seasons in May and June, but also...... was calculated for 1 km2 catchments (produced from topographical maps) on Funen, Denmark. The physical condition (substrate, meandering etc.) of 1st and 2nd order streams (based on existing data from the National Monitoring Programme and personal exploring) draining these catchments was, additionally, assessed...

  19. Spatiotemporal dynamics of spring and stream water chemistry in a high-mountain area

    International Nuclear Information System (INIS)

    Zelazny, Miroslaw; Astel, Aleksander; Wolanin, Anna; Malek, Stanislaw

    2011-01-01

    The present study deals with the application of the self-organizing map (SOM) technique in the exploration of spatiotemporal dynamics of spring and stream water samples collected in the Chocholowski Stream Basin located in the Tatra Mountains (Poland). The SOM-based classification helped to uncover relationships between physical and chemical parameters of water samples and factors determining the quality of water in the studied high-mountain area. In the upper part of the Chocholowski Stream Basin, located on the top of the crystalline core of the Tatras, concentrations of the majority of ionic substances were the lowest due to limited leaching. Significantly higher concentration of ionic substances was detected in spring and stream samples draining sedimentary rocks. The influence of karst-type springs on the quality of stream water was also demonstrated. - Highlights: → We use SOM approach to explore physiochemical data for mountain waters. → Geologic structure and hydrological events impact water chemistry. → Limited leaching, typical of crystalline core, reflects in low water mineralization. → Sedimentary rocks are susceptible for leaching. → Eutrophication has not been shown to be a threat in the Chocholowska Valley. - Spatiotemporal dynamics of spring and stream water chemistry in unique high-mountain area was evaluated by the self-organizing map technique.

  20. Containment vessel drain system

    Science.gov (United States)

    Harris, Scott G.

    2018-01-30

    A system for draining a containment vessel may include a drain inlet located in a lower portion of the containment vessel. The containment vessel may be at least partially filled with a liquid, and the drain inlet may be located below a surface of the liquid. The system may further comprise an inlet located in an upper portion of the containment vessel. The inlet may be configured to insert pressurized gas into the containment vessel to form a pressurized region above the surface of the liquid, and the pressurized region may operate to apply a surface pressure that forces the liquid into the drain inlet. Additionally, a fluid separation device may be operatively connected to the drain inlet. The fluid separation device may be configured to separate the liquid from the pressurized gas that enters the drain inlet after the surface of the liquid falls below the drain inlet.

  1. Hydrogeochemical and stream sediment reconnaissance basic data for Seguin NTMS quadrangle, Texas

    International Nuclear Information System (INIS)

    1978-01-01

    Results of a reconnaissance geochemical survey of the Sequin Quadrangle, Texas are reported. Field and laboratory data are presented for 848 groundwater, 950 stream sediment, and 406 stream water samples. Statistical and areal distributions of uranium and other possible uranium-related variables are displayed. A generalized geologic map of the survey area is provided, and pertinent geologic factors which may be of significance in evaluating the potential for uranium mineralization are briefly discussed. Groundwater data indicate that uranium concentrations above the 85th percentile occur along several northeast-southwest trends paralleling the regional strike of the major formations located within the survey area. The stream sediment data indicate that uranium is associated with heavy and/or resistate minerals in the Carrizo Sand and certain members of the Claiborne Group. Soluble uranium is primarily associated with the Cretaceous Formations, the Whitsett and Catahoula Formations, and sections of the Oakville and Fleming Formations. Stream water data corroborate well with both groundwater and stream sediment data. Anomalous values for uranium and associated pathfinder elements indicate that the Whitsett and Catahoula Formations and sections of the Oakville and Fleming Formations are potentially favorable for uranium mineralization. Anomalous values for certain pathfinder elements also occur in basins draining from the Beaumont Formation and may warrant further investigation

  2. Delay in catchment nitrogen load to streams following restrictions on fertilizer application

    DEFF Research Database (Denmark)

    Vervloet, Lidwien S. C.; Binning, Philip John; Borgesen, Christen D.

    2018-01-01

    A MIKE SHE hydrological-solute transport model including nitrate reduction is employed to evaluate the delayed response in nitrogen loads in catchment streams following the implementation of nitrogen mitigation measures since the 1980s. The nitrate transport lag times between the root zone...... and the streams for the period 1950-2011 were simulated for two catchments in Denmark and compared with observational data. Results include nitrogen concentration and mass discharge to streams. By automated baseflow separation, stream discharge was separated into baseflow and drain flow components...

  3. Characterization of water quality for streams in the southern Yampa River basin, northwestern Colorado. Water Resources Investigation

    International Nuclear Information System (INIS)

    Parker, R.S.

    1991-01-01

    Historically, the Yampa River basin in northwestern Colorado has been an area of coal-mining development. Coal mining generally has been developed in the southern part of the basin and at lower elevations. The purpose of the report is to characterize the stream water quality by summarizing selected major dissolved constituents for the streams that drain the southern part of the Yampa River basin. Characterization is done initially by providing a statistical summary of the constituents for individual water-quality sites in the study area. These statistical summaries can be used to help assess water-quality within specified stream reaches. Water-quality data are available for sites on most perennial streams in the study area, and these data provide the best information about the immediate stream reach. Water-quality data from all sites are combined into regions, and linear-regression equations between dissolved constituents and specific conductance are calculated. Such equations provide an estimate of the water-quality relations within these regions. The equations also indicate an increase in error as individual sites are combined

  4. A retrospective study of the use of active suction wound drains in dogs and cats.

    Science.gov (United States)

    Bristow, P C; Halfacree, Z J; Baines, S J

    2015-05-01

    To report indications for use and complications associated with commonly used closed active suction wound drains in a large number of clinical cases. Retrospective review of medical case records (from 2004 to 2010) for dogs and cats that had a closed active suction drain placed into a wound. Only the four most common drain types were included: Mini Redovac®, Redovac®, Jackson Pratt® and Wound Evac®. Two hundred and fifty-three drains were placed in 33 cats and 195 dogs. Mini Redovac drains were used most frequently in cats (76 · 5%) and Redovac drains in dogs (54 · 3%). The infection rate for clean surgeries in dogs was 15 · 6% (unattainable in cats). Major complications occurred in four dogs; minor complications occurred in 12 drains in cats (35 · 3%), and in 74 drains in dogs (33 · 8%). There was no statistically significant association between the type of drain and complication rate for either species. Although closed active suction drains can be used with low risk of major complications, they lead to a high rate of infection in clean surgeries in dogs. It is recommended that such drains are kept in place for the shortest time possible and that strict asepsis is adhered to both during placement and management. © 2015 British Small Animal Veterinary Association.

  5. Climate and land cover effects on the temperature of Puget Sound streams: Assessment of Climate and Land Use Impacts on Stream Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Qian [Department of Geography, University of California, Los Angeles, Los Angeles CA USA; Sun, Ning [Civil and Environmental Engineering, University of Washington, Seattle WA USA; Pacific Northwest National Laboratory, Richland WA USA; Yearsley, John [Civil and Environmental Engineering, University of Washington, Seattle WA USA; Nijssen, Bart [Civil and Environmental Engineering, University of Washington, Seattle WA USA; Lettenmaier, Dennis P. [Department of Geography, University of California, Los Angeles, Los Angeles CA USA

    2016-03-06

    We apply an integrated hydrology-stream temperature modeling system, DHSVM-RBM, to examine the response of the temperature of the major streams draining to Puget Sound to land cover and climate change. We first show that the model construct is able to reconstruct observed historic streamflow and stream temperature variations at a range of time scales. We then explore the relative effect of projected future climate and land cover change, including riparian vegetation, on streamflow and stream temperature. Streamflow in summer is likely to decrease as the climate warms especially in snowmelt-dominated and transient river basins despite increased streamflow in their lower reaches associated with urbanization. Changes in streamflow also result from changes in land cover, and changes in stream shading result from changes in riparian vegetation, both of which influence stream temperature. However, we find that the effect of riparian vegetation changes on stream temperature is much greater than land cover change over the entire basin especially during summer low flow periods. Furthermore, while future projected precipitation change will have relatively modest effects on stream temperature, projected future air temperature increases will result in substantial increases in stream temperature especially in summer. These summer stream temperature increases will be associated both with increasing air temperature, and projected decreases in low flows. We find that restoration of riparian vegetation could mitigate much of the projected summer stream temperature increases. We also explore the contribution of riverine thermal loadings to the heat balance of Puget Sound, and find that the riverine contribution is greatest in winter, when streams account for up to 1/8 of total thermal inputs (averaged from December through February), with larger effects in some sub-basins. We project that the riverine impact on thermal inputs to Puget Sound will become greater with both urbanization

  6. Nitrous oxide emission from denitrification in stream and river networks

    Science.gov (United States)

    Beaulieu, J.J.; Tank, J.L.; Hamilton, S.K.; Wollheim, W.M.; Hall, R.O.; Mulholland, P.J.; Peterson, B.J.; Ashkenas, L.R.; Cooper, L.W.; Dahm, Clifford N.; Dodds, W.K.; Grimm, N. B.; Johnson, S.L.; McDowell, W.H.; Poole, G.C.; Maurice, Valett H.; Arango, C.P.; Bernot, M.J.; Burgin, A.J.; Crenshaw, C.L.; Helton, A.M.; Johnson, L.T.; O'Brien, J. M.; Potter, J.D.; Sheibley, R.W.; Sobota, D.J.; Thomas, S.M.

    2011-01-01

    Nitrous oxide (N2O) is a potent greenhouse gas that contributes to climate change and stratospheric ozone destruction. Anthropogenic nitrogen (N) loading to river networks is a potentially important source of N 2O via microbial denitrification that converts N to N2O and dinitrogen (N2). The fraction of denitrified N that escapes as N2O rather than N2 (i.e., the N2O yield) is an important determinant of how much N2O is produced by river networks, but little is known about the N2O yield in flowing waters. Here, we present the results of whole-stream 15N-tracer additions conducted in 72 headwater streams draining multiple land-use types across the United States. We found that stream denitrification produces N2O at rates that increase with stream water nitrate (NO3-) concentrations, but that production, but does not increase the N2O yield. In our study, most streams were sources of N2O to the atmosphere and the highest emission rates were observed in streams draining urban basins. Using a global river network model, we estimate that microbial N transformations (e.g., denitrification and nitrification) convert at least 0.68 Tg??y -1 of anthropogenic N inputs to N2O in river networks, equivalent to 10% of the global anthropogenic N2O emission rate. This estimate of stream and river N2O emissions is three times greater than estimated by the Intergovernmental Panel on Climate Change.

  7. Link between DOC in near surface peat and stream water in an upland catchment.

    Science.gov (United States)

    Clark, Joanna M; Lane, Stuart N; Chapman, Pippa J; Adamson, John K

    2008-10-15

    Hydrologic transport of dissolved organic carbon (DOC) from peat soils may differ to organo-mineral soils in how they responded to changes in flow, because of differences in soil profile and hydrology. In well-drained organo-mineral soils, low flow is through the lower mineral layer where DOC is absorbed and high flow is through the upper organic layer where DOC is produced. DOC concentrations in streams draining organo-mineral soils typically increase with flow. In saturated peat soils, both high and low flows are through an organic layer where DOC is produced. Therefore, DOC in stream water draining peat may not increase in response to changes in flow as there is no switch in flow path between a mineral and organic layer. To verify this, we conducted a high-resolution monitoring study of soil and stream water at an upland peat catchment in northern England. Our data showed a strong positive correlation between DOC concentrations at -1 and -5 cm depth and stream water, and weaker correlations between concentrations at -20 to -50 cm depth and stream water. Although near surface organic material appears to be the key source of stream water DOC in both peat and organo-mineral soils, we observed a negative correlation between stream flow and DOC concentrations instead of a positive correlation as DOC released from organic layers during low and high flow was diluted by rainfall. The differences in DOC transport processes between peat and organo-mineral soils have different implications for our understanding of long-term changes in DOC exports. While increased rainfall may cause an increase in DOC flux from peat due to an increase in water volume, it may cause a decrease in concentrations. This response is contrary to expected changes in DOC exports from organo-mineral soils, where increase rainfall is likely to result in an increase in flux and concentration.

  8. Instream flow assessment of streams draining the Arbuckle-Simpson Aquifer

    Science.gov (United States)

    Seilheimer, Titus S.; Fisher, William L.

    2008-01-01

    The availability of high quality water is critical to both humans and ecosystems. A recent proposal was made by rapidly expanding municipalities in central Oklahoma to begin transferring groundwater from the Arbuckle-Simpson aquifer, a sensitive sole-source aquifer in south-central Oklahoma. Concerned citizens and municipalities living on and getting their drinking water from the Arbuckle-Simpson lobbied the legislature to pass a temporary moratorium on groundwater transfer to allow for a comprehensive study of the aquifer and its ecosystems. We conducted an instream flow assessment using Physical Habitat Simulation (PHABSIM) on springs and streams with four spring-dependent species: two minnows, southern redbelly dace (Phoxinus erthyrogaster) and redspot chub (Nocomis asper); and two darters, least darter (Etheostoma microperca) and orangethroat darter (Etheostoma spectabile). Spring habitats are unique compared to other river habitats because they have constant flow and temperature, small and isolated habitat patches, and a general lack of predators. Our study sites included two spring-fed streams, one larger stream with high groundwater inputs, and a river with both groundwater and surface water inputs that is adjacent to the small spring-fed streams. These habitats meet the criteria for groundwater dependent ecosystems because they would not exist without the surface expression of groundwater. A total of 99 transects in all four sites were surveyed for channel elevation, and three sets of water surface elevation and water velocity were measured. Habitat suitability criteria were derived for the species at each site using nonparametric confidence limits based on underwater observations made by snorkelers. Simulations of flow were focused on declines in discharge, which is the expected effect of the proposed groundwater diversion. Our results show that only a small proportion of the total available area in each habitat is considered to be preferred habitat

  9. Influence of Soils, Riparian Zones, and Hydrology on Nutrients, Herbicides, and Biological Relations in Midwestern Agricultural Streams

    Science.gov (United States)

    Porter, S.

    2001-12-01

    Chemical, biological, and habitat conditions were characterized in 70 streams in the upper Mississippi River basin during August 1997, as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. The study was designed to evaluate algal and macroinvertebrate responses to high agricultural intensity in relation to nonpoint sources of nutrients and herbicides, characteristics of basin soils, wooded-riparian vegetation, and hydrology. Concentrations and forms of nutrients, herbicides and their metabolites, and seston constituents varied significantly with regional differences in soil properties, ground and surface water relations, density of riparian trees, and precedent rainfall-runoff conditions. Dissolved nitrate concentrations were relatively low in streams with high algal productivity; however, nitrate concentrations increased with basin water yield, which was associated with the regional distribution of rainfall during the month prior to the study. Stream productivity and respiration were positively correlated with seston (phytoplankton) chlorophyll concentrations, which were significantly larger in streams in areas with poorly drained soils and low riparian-tree density. Concentrations of dissolved phosphorus were low in streams where periphyton biomass was high. Periphyton biomass was relatively larger in streams with clear water and low abundance of macroinvertebrates that consume algae. Periphyton biomass decreased rapidly with modest increases in the abundance of scrapers such as snails and certain mayfly taxa. Differences in dissolved oxygen, organic carbon, stream velocity, and precedent hydrologic conditions explained much of the variance in macroinvertebrate community structure. The overall number of macroinvertebrate species and number of mayfly, caddisfly, and stonefly (EPT) taxa that are sensitive to organic enrichment were largest in streams with moderate periphyton biomass, in areas with moderately-well drained soils

  10. Streams in the urban heat island: spatial and temporal variability in temperature

    Science.gov (United States)

    Somers, Kayleigh A.; Bernhardt, Emily S.; Grace, James B.; Hassett, Brooke A.; Sudduth, Elizabeth B.; Wang, Siyi; Urban, Dean L.

    2013-01-01

    Streams draining urban heat islands tend to be hotter than rural and forested streams at baseflow because of warmer urban air and ground temperatures, paved surfaces, and decreased riparian canopy. Urban infrastructure efficiently routes runoff over hot impervious surfaces and through storm drains directly into streams and can lead to rapid, dramatic increases in temperature. Thermal regimes affect habitat quality and biogeochemical processes, and changes can be lethal if temperatures exceed upper tolerance limits of aquatic fauna. In summer 2009, we collected continuous (10-min interval) temperature data in 60 streams spanning a range of development intensity in the Piedmont of North Carolina, USA. The 5 most urbanized streams averaged 21.1°C at baseflow, compared to 19.5°C in the 5 most forested streams. Temperatures in urban streams rose as much as 4°C during a small regional storm, whereas the same storm led to extremely small to no changes in temperature in forested streams. Over a kilometer of stream length, baseflow temperature varied by as much as 10°C in an urban stream and as little as 2°C in a forested stream. We used structural equation modeling to explore how reach- and catchment-scale attributes interact to explain maximum temperatures and magnitudes of storm-flow temperature surges. The best predictive model of baseflow temperatures (R2  =  0.461) included moderately strong pathways directly (extent of development and road density) and indirectly, as mediated by reach-scale factors (canopy closure and stream width), from catchment-scale factors. The strongest influence on storm-flow temperature surges appeared to be % development in the catchment. Reach-scale factors, such as the extent of riparian forest and stream width, had little mitigating influence (R2  =  0.448). Stream temperature is an essential, but overlooked, aspect of the urban stream syndrome and is affected by reach-scale habitat variables, catchment-scale urbanization

  11. Fish diversity in adjacent ambient, thermal, and post-thermal freshwater streams

    International Nuclear Information System (INIS)

    McFarlane, R.W.

    1976-01-01

    The Savannah River Plant area is drained by five streams of various sizes and thermal histories. One has never been thermally stressed, two presently receive thermal effluent, and two formerly received thermal effluent from nuclear production reactors. Sixty-four species of fishes are known to inhabit these streams; 55 species is the highest number obtained from any one stream. Thermal effluent in small streams excludes fish during periods of high temperatures, but the streams are rapidly reinvaded when temperatures subside below lethal limits. Some cyprinids become extinct in nonthermal tributaries upstream from the thermal effluents after extended periods of thermal stress. This extinction is similar to that which follows stream impoundment. Post-thermal streams rapidly recover their fish diversity and abundance. The alteration of the streambed and removal of overhead canopy may change the stream characteristics and modify the post-thermal fish fauna

  12. Spatio-temporal variation in stream water chemistry in a tropical urban watershed

    Directory of Open Access Journals (Sweden)

    Alonso Ramírez

    2014-06-01

    Full Text Available Urban activities and related infrastructure alter the natural patterns of stream physical and chemical conditions. According to the Urban Stream Syndrome, streams draining urban landscapes are characterized by high concentrations of nutrients and ions, and might have elevated water temperatures and variable oxygen concentrations. Here, we report temporal and spatial variability in stream physicochemistry in a highly urbanized watershed in Puerto Rico. The main objective of the study was to describe stream physicochemical characteristics and relate them to urban intensity, e.g., percent impervious surface cover, and watershed infrastructure, e.g., road and pipe densities. The Río Piedras Watershed in the San Juan Metropolitan Area, Puerto Rico, is one of the most urbanized regions on the island. The Río Piedras presented high solute concentrations that were related to watershed factors, such as percent impervious cover. Temporal variability in ion concentrations lacked seasonality, as did all other parameters measured except water temperature, which was lower during winter and highest during summer, as expected based on latitude. Spatially, stream physicochemistry was strongly related to watershed percent impervious cover and also to the density of urban infrastructure, e.g., roads, pipe, and building densities. Although the watershed is serviced by a sewage collection system, illegal discharges and leaky infrastructure are probably responsible for the elevated ion concentration found. Overall, the Río Piedras is an example of the response of a tropical urban watershed after major sewage inputs are removed, thus highlighting the importance of proper infrastructure maintenance and management of runoff to control ion concentrations in tropical streams.

  13. Identification and Selection of Major Carbon Dioxide Stream Compositions

    Energy Technology Data Exchange (ETDEWEB)

    Last, George V.; Schmick, Mary T.

    2011-06-30

    A critical component in the assessment of long-term risk from geologic sequestration of CO2 is the ability to predict mineralogical and geochemical changes within storage reservoirs due to rock-brine-CO2 reactions. Impurities and/or other constituents selected for co-sequestration can affect both the chemical and physical (e.g. density, viscosity, interfacial tension) behavior of CO2 in the deep subsurface. These impurities and concentrations are a function of both the industrial source(s) of the CO2, as well as the carbon capture technology used to extract the CO2 and produce a concentrated stream for geologic sequestration. This report summarizes the relative concentrations of CO2 and other constituents in exhaust gases from major non-energy related industrial sources of CO2. Assuming that carbon-capture technology would remove most of the incondensable gases N2, O2, and Ar, leaving SO2 and NOx as the main impurities, we selected four test fluid compositions for use in geochemical experiments. These included: 1) a pure CO2 stream representative of food grade CO2 used in most enhanced oil recovery projects: 2) a test fluid composition containing low concentrations (0.5 mole %) SO2 and NOx (representative of that generated from cement production), 3) a test fluid composition with higher concentrations (2.5 mole %) of SO2, and 4) and test fluid composition containing 3 mole % H2S.

  14. The hydrology of a drained topographical depression within an agricutlural field in north-central Iowa

    Science.gov (United States)

    Roth, Jason L.; Capel, Paul D.

    2012-01-01

    North-central Iowa is an agriculturally intensive area comprising the southeastern portion of the Prairie Pothole Region, a landscape containing a high density of enclosed topographical depressions. Artificial drainage practices have been implemented throughout the area to facilitate agricultural production. Vertical surface drains are utilized to drain the topographical depressions that accumulate water. This study focuses on the hydrology of a drained topographical depression located in a 39.5 ha agricultural field. To assess the hydrology of the drained depression, a water balance was constructed for 11 ponding events during the 2008 growing season. Continuous pond and groundwater level data were obtained with pressure transducers. Flows into the vertical surface drain were calculated based on pond depth. Precipitation inflows and evaporative outflows of the ponds were calculated using climatic data. Groundwater levels were used to assess groundwater/pond interactions. Results of the water balances show distinct differences between the inflows to and outflows from the depression based on antecedent conditions. In wet conditions, groundwater inflow sustained the ponds. The ponds receded only after the groundwater level declined to below the land surface. In drier conditions, groundwater was not a source of water to the depression. During these drier conditions, infiltration comprised 30% of the outflows from the depression during declining pond stages. Over the entire study period, the surface drain, delivering water to the stream, was the largest outflow from the pond, accounting for 97% of the outflow, while evapotranspiration was just 2%. Precipitation onto the pond surface proved to be a minor component, accounting for 4% of the total inflows.

  15. Beyond cool: adapting upland streams for climate change using riparian woodlands.

    Science.gov (United States)

    Thomas, Stephen M; Griffiths, Siân W; Ormerod, Steve J

    2016-01-01

    Managed adaptation could reduce the risks of climate change to the world's ecosystems, but there have been surprisingly few practical evaluations of the options available. For example, riparian woodland is advocated widely as shade to reduce warming in temperate streams, but few studies have considered collateral effects on species composition or ecosystem functions. Here, we use cross-sectional analyses at two scales (region and within streams) to investigate whether four types of riparian management, including those proposed to reduce potential climate change impacts, might also affect the composition, functional character, dynamics and energetic resourcing of macroinvertebrates in upland Welsh streams (UK). Riparian land use across the region had only small effects on invertebrate taxonomic composition, while stable isotope data showed how energetic resources assimilated by macroinvertebrates in all functional guilds were split roughly 50:50 between terrestrial and aquatic origins irrespective of riparian management. Nevertheless, streams draining the most extensive deciduous woodland had the greatest stocks of coarse particulate matter (CPOM) and greater numbers of 'shredding' detritivores. Stream-scale investigations showed that macroinvertebrate biomass in deciduous woodland streams was around twice that in moorland streams, and lowest of all in streams draining non-native conifers. The unexpected absence of contrasting terrestrial signals in the isotopic data implies that factors other than local land use affect the relative incorporation of allochthonous subsidies into riverine food webs. Nevertheless, our results reveal how planting deciduous riparian trees along temperate headwaters as an adaptation to climate change can modify macroinvertebrate function, increase biomass and potentially enhance resilience by increasing basal resources where cover is extensive (>60 m riparian width). We advocate greater urgency in efforts to understand the ecosystem

  16. Flocculation of organic carbon from headwaters to estuary - the impact of soil erosion, water quality and land use on carbon transformation processes in eight streams draining Exmoor, UK

    Science.gov (United States)

    Snoalv, J.; Groeneveld, M.; Quine, T. A.; Tranvik, L.

    2017-12-01

    Flocculation of dissolved organic carbon (DOC) in streams and rivers is a process that contributes to the pool of particulate organic carbon (POC) in the aquatic system. In low-energy waters the increased sedimentation rates of this higher-density fraction of organic carbon (OC) makes POC important in allocating organic carbon into limnic storage, which subsequently influences emissions of greenhouse gases from the continental environment to the atmosphere. Allochthonous OC, derived from the terrestrial environment by soil erosion and litterfall, import both mineral aggregate-bound and free OC into freshwaters, which comprise carbon species of different quality and recalcitrance than autochthonous in-stream produced OC, such as from biofilms, aquatic plants and algae. Increased soil erosion due to land use change (e.g. agriculture, deforestation etc.) influences the input of allochthonous OC, which can lead to increased POC formation and sedimentation of terrestrial OC at flocculation boundaries in the landscape, i.e. where coagulation and flocculation processes are prone to occur in the water column. This study investigates the seasonal variation in POC content and flocculation capacity with respect to water quality (elemental composition) in eight river systems (four agricultural and four wooded streams) with headwaters in Exmoor, UK, that drain managed and non-managed land into Bristol Channel. Through flocculation experiments the samples were allowed to flocculate by treatments with added clay and salt standards that simulate the flocculation processes by 1) increased input of sediment into streams, and 2) saline mixing at the estuarine boundary, in order to quantify floc production and investigate POC quality by each process respectively. The results show how floc production, carbon quality and incorporation (e.g. complexation) of metals and rare earth elements (REE) in produced POC and remaining DOC in solution vary in water samples over the season and how

  17. Leaching of dissolved phosphorus from tile-drained agricultural areas.

    Science.gov (United States)

    Andersen, H E; Windolf, J; Kronvang, B

    2016-01-01

    We investigated leaching of dissolved phosphorus (P) from 45 tile-drains representing animal husbandry farms in all regions of Denmark. Leaching of P via tile-drains exhibits a high degree of spatial heterogeneity with a low concentration in the majority of tile-drains and few tile-drains (15% in our investigation) having high to very high concentration of dissolved P. The share of dissolved organic P (DOP) was high (up to 96%). Leaching of DOP has hitherto been a somewhat overlooked P loss pathway in Danish soils and the mechanisms of mobilization and transport of DOP needs more investigation. We found a high correlation between Olsen-P and water extractable P. Water extractable P is regarded as an indicator of risk of loss of dissolved P. Our findings indicate that Olsen-P, which is measured routinely in Danish agricultural soils, may be a useful proxy for the P leaching potential of soils. However, we found no straight-forward correlation between leaching potential of the top soil layer (expressed as either degree of P saturation, Olsen-P or water extractable P) and the measured concentration of dissolved P in the tile-drain. This underlines that not only the source of P but also the P loss pathway must be taken into account when evaluating the risk of P loss.

  18. Effects of residential and agricultural land uses on the chemical quality of baseflow of small streams in the Croton Watershed, southeastern New York

    Science.gov (United States)

    Heisig, Paul M.

    2000-01-01

    Data on the chemical quality of baseflow from 33 small streams that drain basins of differing land-use type and intensity within the Croton watershed were collected seasonally for 1 year to identify and characterize the quality of ground-water contributions to surface water. The watershed includes twelve of New York City's water-supply reservoirs. Baseflow samples were collected a minimum of three days after the most recent precipitation and were analyzed for major ions, boron, and nutrients.

  19. Water-quality assessment of part of the Upper Mississippi River Basin Study Unit, Minnesota and Wisconsin- Nutrients, chlorophyll a, phytoplankton, and suspended sediment in streams, 1996-98

    Science.gov (United States)

    Kroening, Sharon E.; Lee, Kathy E.; Goldstein, R.M.

    2003-01-01

    Stream water-quality data from part of the Upper Mississippi River Basin Study Unit (Study Unit) from 1995 through 1998 was used to describe the distribution of nutrients, chlorophyll a, phytoplankton, and suspended sediment; and the influence of natural and anthropogenic factors on reported concentrations, loads, and yields. During the study period, streamflows generally were near to greater than average. Agricultural land cover, particularly on tile-drained soils, had the most substantial influence on nutrients, chlorophyll a, and suspended sediment in the Study Unit. The greatest concentrations and yields of total nitrogen, dissolved nitrite plus nitrate nitrogen, dissolved nitrite nitrogen, total organic plus ammonia nitrogen, total phosphorus, and suspended sediment were measured in a stream representing agricultural land cover on tile-drained soils. Total nitrogen yields also were about 6 times greater in a stream representing agricultural land cover on tile-drained soils than in a stream representing agricultural land cover on naturally welldrained soils.

  20. Characterizing subsurface water flow to artificial drain lines using fiber-optic distributed temperature sensing

    Science.gov (United States)

    Shults, D.; Brooks, E. S.; Heinse, R.; Keller, C. K.

    2017-12-01

    Over the last several years growers have experienced increasingly wet spring conditions in the Palouse Region located in North Idaho, Eastern Washington and Eastern Oregon. As a result more artificial drain lines are being installed so growers can access their fields earlier in the growing season. Additionally there has been increasing adoption of no-tillage practices among growers in order minimize erosion and runoff in the region. There is a growing body of evidence that suggests long-term no-tillage may lead to the establishment of large macropore networks through increased earthworm activity and the preservation of root channels. These macropore networks, in conjunctions with the presence of artificial drains lines, may create connected preferential flow paths from agricultural fields to receiving streams. This connectivity of flow paths from agricultural fields to receiving water bodies may increase the loading of nutrients and agricultural chemicals as some flow paths may largely bypass soil matrix interaction where materials can be sequestered. Our primary objective for this study was to characterize subsurface flow to two artificial drain lines, one under conventional tillage and the other under no-tillage, using distributed temperature sensing (DTS) technology. During the study (November 2016-April 2017) the near surface soil-water temperature was consistently colder than that of deeper depths. Temperature was thus used as a tracer as snow melt and soil-water moved from the near surface to the drain lines during snowmelt and precipitation events. The spatial and temporal variability of the temperature along the artificial drain line under no-tillage practices was found to be greater than that of the conventional tilled field. It is hypothesized that preferential flow paths are responsible for the increased variability of temperature seen in the drain line under long term no-till management. The temperature along the conventional till drain line showed a

  1. Using Smoke Injection in Drains to Identify Potential Preferential Pathways in a Drained Arable Field

    Science.gov (United States)

    Nielsen, M. H.; Petersen, C. T.; Hansen, S.

    2014-12-01

    Macropores forming a continuous pathway between the soil surface and subsurface drains favour the transport of many contaminants from agricultural fields to surface waters. The smoke injection method presented by Shipitalo and Gibbs (2000) used for demonstrating and quantifying such pathways has been further developed and used on a drained Danish sandy loam. In order to identify the preferential pathways to drains, smoke was injected in three 1.15 m deep tile drains (total drain length 93 m), and smoke emitting macropores (SEMP) at the soil surface were counted and characterized as producing either strong or weak plumes compared to reference plumes from 3 and 6 mm wide tubes. In the two situations investigated in the present study - an early spring and an autumn situation, smoke only penetrated the soil surface layer via earthworm burrows located in a 1.0 m wide belt directly above the drain lines. However, it is known from previous studies that desiccation fractures in a dry summer situation also can contribute to the smoke pattern. The distance between SEMP measured along the drain lines was on average 0.46 m whereas the average spacing between SEMP with strong plumes was 2.3 m. Ponded water was applied in 6 cm wide rings placed above 52 burrows including 17 reference burrows which did not emit smoke. Thirteen pathways in the soil were examined using dye tracer and profile excavation. SEMP with strong plumes marked the entrance of highly efficient transport pathways conducting surface applied water and dye tracer into the drain. However, no single burrow was traced all the way from the surface into the drain, the dye patterns branched off in a network of other macropores. Water infiltration rates were significantly higher (P drains and surface waters, pathways being associated primarily with unevenly distributed SEMP producing strong smoke plumes.

  2. Instream wood loads in montane forest streams of the Colorado Front Range, USA

    Science.gov (United States)

    Jackson, Karen J.; Wohl, Ellen

    2015-04-01

    Although several studies examine instream wood loads and associated geomorphic effects in streams of subalpine forests in the U.S. Southern Rocky Mountains, little is known of instream wood loads in lower elevation, montane forests of the region. We compare instream wood loads and geomorphic effects between streams draining montane forest stands of differing age (old growth versus younger) and disturbance history (healthy versus infested by mountain pine beetles). We examined forest stand characteristics, instream wood load, channel geometry, pool volume, and sediment storage in 33 pool-riffle or plane-bed stream reaches with objectives of determining whether (i) instream wood and geomorphic effects differed significantly among old-growth, younger, healthy, and beetle-infested forest stands and (ii) wood loads correlated with valley and channel characteristics. Wood loads were standardized to drainage area, stream gradient, reach length, bankfull width, and floodplain area. Streams flowing through old-growth forests had significantly larger wood loads and logjam volumes (pairwise t-tests), as well as logjam frequencies (Kruskal-Wallis test), residual pool volume, and fine sediment storage around wood than streams flowing through younger forests. Wood loads in streams draining beetle-infested forest did not differ significantly from those in healthy forest stands, but best subset regression models indicated that elevation, stand age, and beetle infestation were the best predictors of wood loads in channels and on floodplains, suggesting that beetle infestation is affecting instream wood characteristics. Wood loads are larger than values from subalpine streams in the same region and jams are larger and more closely spaced. We interpret these differences to reflect greater wood piece mobility in subalpine zone streams. Stand age appears to exert the dominant influence on instream wood characteristics within pool-riffle streams in the study area rather than beetle

  3. The influence of riparian-hyporheic zone on the hydrological responses in an intermittent stream

    Directory of Open Access Journals (Sweden)

    A. Butturini

    2002-01-01

    Full Text Available Stream and riparian groundwater hydrology has been studied in a small intermittent stream draining a forested catchment for a system representative of a Mediterranean climate. The relationship between precipitation and stream runoff and the interactions between stream water and the surrounding riparian groundwater have been analysed under a wide spectrum of meteorological conditions. The hypothesis that the hydrological condition of the near-stream groundwater compartment can regulate the runoff generation during precipitation events was tested. Stream runoff is characterised by a summer dry period, and precipitation input explained only 25% of runoff variability over the study period (r2 =0.25, d.f.=51, p2=0.80, d.f.=34, p Keywords: riparian zone, groundwater hydrology, runoff, intermittent stream, Mediterranean climate

  4. Ammonium release from a blanket peatland into headwater stream systems

    International Nuclear Information System (INIS)

    Daniels, S.M.; Evans, M.G.; Agnew, C.T.; Allott, T.E.H.

    2012-01-01

    Hydrochemical sampling of South Pennine (UK) headwater streams draining eroded upland peatlands demonstrates these systems are nitrogen saturated, with significant leaching of dissolved inorganic nitrogen (DIN), particularly ammonium, during both stormflow and baseflow conditions. DIN leaching at sub-catchment scale is controlled by geomorphological context; in catchments with low gully densities ammonium leaching dominates whereas highly gullied catchments leach ammonium and nitrate since lower water tables and increased aeration encourages nitrification. Stormflow flux calculations indicate that: approximately equivalent amounts of nitrate are deposited and exported; ammonium export significantly exceeds atmospheric inputs. This suggests two ammonium sources: high atmospheric loadings; and mineralisation of organic nitrogen stored in peat. Downstream trends indicate rapid transformation of leached ammonium into nitrate. It is important that low-order headwater streams are adequately considered when assessing impacts of atmospheric loads on the hydrochemistry of stream networks, especially with respect to erosion, climate change and reduced precipitation. - Highlights: ► Headwaters draining eroded South Pennine (UK) peatlands are nitrogen saturated. ► Ammonium and nitrate leaching arises from aeration due to lower water tables. ► Nitrate deposition equals export during storms; ammonium export exceeds input. ► Ammonia input from high atmospheric loading and mineralisation of organic nitrogen. ► Downstream nitrogen trends indicate rapid transformation of ammonium into nitrate. - Inorganic nitrogen leaching from South Pennine peatlands is dominated by ammonium that is rapidly transformed within-streams to nitrate.

  5. A prospective randomized study of use of drain versus no drain after burr-hole evacuation of chronic subdural hematoma.

    Science.gov (United States)

    Singh, Amit Kumar; Suryanarayanan, Bhaskar; Choudhary, Ajay; Prasad, Akhila; Singh, Sachin; Gupta, Laxmi Narayan

    2014-01-01

    Chronic subdural hematoma (CSDH) recurs after surgical evacuation in 5-30% of patients. Inserting subdural drain might reduce the recurrence rate, but is not commonly practiced. There are few prospective studies to evaluate the effect of subdural drains. A prospective randomized study to investigate the effect of subdural drains in the on recurrence rates and clinical outcome following burr-hole drainage (BHD) of CSDH was undertaken. During the study period, 246 patients with CSDH were assessed for eligibility. Among 200 patients fulfilling the eligibility criteria, 100 each were assigned to "drain group" (drain inserted into the subdural space following BHD) and "without drain group" (subdural drain was not inserted following BHD) using random allocation software. The primary end point was recurrence needing re-drainage up to a period of 6 months from surgery. Recurrence occurred in 9 of 100 patients with a drain, and 26 of 100 patients in without drain group (P = 0.002). The mortality was 5% in patients with drain and 4% in patients without drain group (P = 0.744). The medical and surgical complications were comparable between the two study groups. Use of a subdural drain after burr-hole evacuation of a CSDH reduces the recurrence rate and is not associated with increased complications.

  6. Americium/curium bushing melter drain tests

    International Nuclear Information System (INIS)

    Smith, M.E.; Hardy, B.J.; Smith, M.E.

    1997-01-01

    Americium and curium were produced in the past at the Savannah River Site (SRS) for research, medical, and radiological applications. They have been stored in a nitric acid solution in an SRS reprocessing facility for a number of years. Vitrification of the americium/curium (Am/Cm) solution will allow the material to be safely stored or transported to the DOE Oak Ridge Reservation. Oak Ridge is responsible for marketing radionuclides for research and medical applications. The bushing melter technology being used in the Am/Cm vitrification research work is also under consideration for the stabilization of other actinides such as neptunium and plutonium. A series of melter drain tests were conducted at the Savannah River Technology Center to determine the relationship between the drain tube assembly operating variables and the resulting pour initiation times, glass flowrates, drain tube temperatures, and stop pour times. Performance criteria such as ability to start and stop pours in a controlled manner were also evaluated. The tests were also intended to provide support of oil modeling of drain tube performance predictions and thermal modeling of the drain tube and drain tube heater assembly. These drain tests were instrumental in the design of subsequent melter drain tube and drain tube heaters for the Am/Cm bushing melter, and therefore in the success of the Am/Cm vitrification and plutonium immobilization programs

  7. Water-supply potential of major streams and the Upper Floridan Aquifer in the vicinity of Savannah, Georgia

    Science.gov (United States)

    Garza, Reggina; Krause, Richard E.

    1997-01-01

    Surface- and ground-water resources in the Savannah, Georgia, area were evaluated for potential water-supply development. Stream-discharge and water-quality data were analyzed for two major streams considered to be viable water-supply sources. A ground-water flow model was developed to be used in conjunction with other previously calibrated models to simulate the effects of additional pumpage on water levels near areas of saltwater intrusion at Brunswick and seawater encroachment at Hilton Head Island. Hypothetical scenarios also were simulated involving redistributions and small increases, and decreases in pumpage.

  8. Verifiable metamodels for nitrate losses to drains and groundwater in the Corn Belt, USA

    Science.gov (United States)

    Nolan, Bernard T.; Malone, Robert W.; Gronberg, Jo Ann M.; Thorp, K.R.; Ma, Liwang

    2012-01-01

    Nitrate leaching in the unsaturated zone poses a risk to groundwater, whereas nitrate in tile drainage is conveyed directly to streams. We developed metamodels (MMs) consisting of artificial neural networks to simplify and upscale mechanistic fate and transport models for prediction of nitrate losses by drains and leaching in the Corn Belt, USA. The two final MMs predicted nitrate concentration and flux, respectively, in the shallow subsurface. Because each MM considered both tile drainage and leaching, they represent an integrated approach to vulnerability assessment. The MMs used readily available data comprising farm fertilizer nitrogen (N), weather data, and soil properties as inputs; therefore, they were well suited for regional extrapolation. The MMs effectively related the outputs of the underlying mechanistic model (Root Zone Water Quality Model) to the inputs (R2 = 0.986 for the nitrate concentration MM). Predicted nitrate concentration was compared with measured nitrate in 38 samples of recently recharged groundwater, yielding a Pearson’s r of 0.466 (p = 0.003). Predicted nitrate generally was higher than that measured in groundwater, possibly as a result of the time-lag for modern recharge to reach well screens, denitrification in groundwater, or interception of recharge by tile drains. In a qualitative comparison, predicted nitrate concentration also compared favorably with results from a previous regression model that predicted total N in streams.

  9. Assessing pesticide concentrations and fluxes in the stream of a small vineyard catchment - Effect of sampling frequency

    International Nuclear Information System (INIS)

    Rabiet, M.; Margoum, C.; Gouy, V.; Carluer, N.; Coquery, M.

    2010-01-01

    This study reports on the occurrence and behaviour of six pesticides and one metabolite in a small stream draining a vineyard catchment. Base flow and flood events were monitored in order to assess the variability of pesticide concentrations according to the season and to evaluate the role of sampling frequency on the evaluation of fluxes estimates. Results showed that dissolved pesticide concentrations displayed a strong temporal and spatial variability. A large mobilisation of pesticides was observed during floods, with total dissolved pesticide fluxes per event ranging from 5.7 x 10 -3 g/Ha to 0.34 g/Ha. These results highlight the major role of floods in the transport of pesticides in this small stream which contributed to more than 89% of the total load of diuron during August 2007. The evaluation of pesticide loads using different sampling strategies and method calculation, showed that grab sampling largely underestimated pesticide concentrations and fluxes transiting through the stream. - This work brings new insights about the fluxes of pesticides in surface water of a vineyard catchment, notably during flood events.

  10. Assessing pesticide concentrations and fluxes in the stream of a small vineyard catchment - Effect of sampling frequency

    Energy Technology Data Exchange (ETDEWEB)

    Rabiet, M., E-mail: marion.rabiet@unilim.f [Cemagref, UR QELY, 3bis quai Chauveau, CP 220, F-69336 Lyon (France); Margoum, C.; Gouy, V.; Carluer, N.; Coquery, M. [Cemagref, UR QELY, 3bis quai Chauveau, CP 220, F-69336 Lyon (France)

    2010-03-15

    This study reports on the occurrence and behaviour of six pesticides and one metabolite in a small stream draining a vineyard catchment. Base flow and flood events were monitored in order to assess the variability of pesticide concentrations according to the season and to evaluate the role of sampling frequency on the evaluation of fluxes estimates. Results showed that dissolved pesticide concentrations displayed a strong temporal and spatial variability. A large mobilisation of pesticides was observed during floods, with total dissolved pesticide fluxes per event ranging from 5.7 x 10{sup -3} g/Ha to 0.34 g/Ha. These results highlight the major role of floods in the transport of pesticides in this small stream which contributed to more than 89% of the total load of diuron during August 2007. The evaluation of pesticide loads using different sampling strategies and method calculation, showed that grab sampling largely underestimated pesticide concentrations and fluxes transiting through the stream. - This work brings new insights about the fluxes of pesticides in surface water of a vineyard catchment, notably during flood events.

  11. Consequences of variation in stream-landscape connections for stream nitrate retention and export

    Science.gov (United States)

    Handler, A. M.; Helton, A. M.; Grimm, N. B.

    2017-12-01

    Hydrologic and material connections among streams, the surrounding terrestrial landscape, and groundwater systems fluctuate between extremes in dryland watersheds, yet the consequences of this variation for stream nutrient retention and export remain uncertain. We explored how seasonal variation in hydrologic connection among streams, landscapes, and groundwater affect nitrate and ammonium concentrations across a dryland stream network and how this variation mediates in-stream nitrate uptake and watershed export. We conducted spatial surveys of stream nitrate and ammonium concentration across the 1200 km2 Oak Creek watershed in central Arizona (USA). In addition, we conducted pulse releases of a solution containing biologically reactive sodium nitrate, with sodium chloride as a conservative hydrologic tracer, to estimate nitrate uptake rates in the mainstem (Q>1000 L/s) and two tributaries. Nitrate and ammonium concentrations generally increased from headwaters to mouth in the mainstem. Locally elevated concentrations occurred in spring-fed tributaries draining fish hatcheries and larger irrigation ditches, but did not have a substantial effect on the mainstem nitrogen load. Ambient nitrate concentration (as N) ranged from below the analytical detection limit of 0.005 mg/L to 0.43 mg/L across all uptake experiments. Uptake length—average stream distance traveled for a nutrient atom from the point of release to its uptake—at ambient concentration ranged from 250 to 704 m and increased significantly with higher discharge, both across streams and within the same stream on different experiment dates. Vertical uptake velocity and aerial uptake rate ranged from 6.6-10.6 mm min-1 and 0.03 to 1.4 mg N m-2 min-1, respectively. Preliminary analyses indicate potentially elevated nitrogen loading to the lower portion of the watershed during seasonal precipitation events, but overall, the capacity for nitrate uptake is high in the mainstem and tributaries. Ongoing work

  12. Switch of flow direction in an Antarctic ice stream.

    Science.gov (United States)

    Conway, H; Catania, G; Raymond, C F; Gades, A M; Scambos, T A; Engelhardt, H

    2002-10-03

    Fast-flowing ice streams transport ice from the interior of West Antarctica to the ocean, and fluctuations in their activity control the mass balance of the ice sheet. The mass balance of the Ross Sea sector of the West Antarctic ice sheet is now positive--that is, it is growing--mainly because one of the ice streams (ice stream C) slowed down about 150 years ago. Here we present evidence from both surface measurements and remote sensing that demonstrates the highly dynamic nature of the Ross drainage system. We show that the flow in an area that once discharged into ice stream C has changed direction, now draining into the Whillans ice stream (formerly ice stream B). This switch in flow direction is a result of continuing thinning of the Whillans ice stream and recent thickening of ice stream C. Further abrupt reorganization of the activity and configuration of the ice streams over short timescales is to be expected in the future as the surface topography of the ice sheet responds to the combined effects of internal dynamics and long-term climate change. We suggest that caution is needed when using observations of short-term mass changes to draw conclusions about the large-scale mass balance of the ice sheet.

  13. Microbial enzyme activity, nutrient uptake and nutrient limitation in forested streams

    Science.gov (United States)

    Brian H. Hill; Frank H. McCormick; Bret C. Harvey; Sherri L. Johnson; Melvin L. Warren; Colleen M. Elonen

    2010-01-01

    The flow of organic matter and nutrients from catchments into the streams draining them and the biogeochemical transformations of organic matter and nutrients along flow paths are fundamental processes instreams (Hynes,1975; Fisher, Sponseller & Heffernan, 2004). Microbial biofilms are often the primary interface for organic matter and nutrient uptake and...

  14. Clearcutting affects stream chemistry in the White Mountains of New Hampshire

    Science.gov (United States)

    C. Wayne Martin; Robert S. Pierce; Gene E. Likens; F. Herbert Bormann; F. Herbert Bormann

    1986-01-01

    Commercial clearcutting of northern hardwood forests changed the chemistry of the streams that drained from them. By the second year after cutting, specific conductance doubled, nitrate increased tenfold, calcium tripled, and sodium, magnesium, and potassium doubled. Chloride and ammonium did not change; sulfate decreased. Concentrations of most ions returned to...

  15. Tracking Changes in Dissolved Organic Matter Patterns in Perennial Headwater Streams Throughout a Hydrologic Year Using In-situ Sensors and Optical Properties

    Science.gov (United States)

    Armstrong, A.; Epting, S.; Hosen, J. D.; Palmer, M.

    2015-12-01

    Dissolved organic matter (DOM) plays a central role in freshwater streams but key questions remain unanswered about temporal patterns in its quantity and composition. DOM in perennial streams in the temperate zone is a complex mixture reflecting a variety of sources such as leached plant material, organic matter from surrounding soils, and microbial processes in the streams themselves. Headwater perennial streams in the Tuckahoe Creek watershed of the Atlantic coastal plain (Maryland, USA) drain a mosaic of land cover types including row crops, forests, and both forested and marshy small depressional wetlands. Wetland-stream surface hydrologic connections generally occur between mid-fall and late spring, coinciding with peak wetland hydrologic expression (i.e. highest groundwater levels and surface inundation extent). When inundated, these wetlands contain high DOM concentrations, and surface connections may serve as conduits for downstream export. We hypothesized that changes in wetland-stream surface hydrologic connectivity would affect patterns of DOM concentration and composition in these streams. We deployed 6 sondes equipped with fluorescent DOM sensors in 4 perennial streams, 1 forested wetland, and the larger downstream channel draining all study sites for the 2015 water year. The 4 headwater streams drain areas containing forested wetlands and have documented temporary channel connections. Combined with baseflow and stormflow sampling, the sondes provided 15 minute estimates of dissolved organic carbon (DOC) concentrations. This resolution provided insights into patterns of DOC concentration across temporal scales from daily rhythms to seasonal changes, during both baseflow and storm conditions. Discrete measurements of absorbance and fluorescence provided information about DOM composition throughout the study. Together these measurements give a detailed record of DOM dynamics in multiple perennial headwater streams for an entire year. This information

  16. An Improvised Active Drain | Ogirima | Nigerian Journal of Surgical ...

    African Journals Online (AJOL)

    An improvised active drain is designed from intravenous infusion set and recycled RedivacR or Haemovac® bottle. Outcome of the use of this system on 100 patients is presented. This suction drainage system had been used in major orthopaedic and common minor surgical procedures and no significant complication was ...

  17. On the use of drains in orthopedic and trauma

    African Journals Online (AJOL)

    2013-11-08

    Nov 8, 2013 ... Even major procedures like total knee and arthroplasties are being performed without drains. We set to find ... discourage wound healing while encouraging bacterial ... a period of two days or if drainage over the first twenty‑four hours was found ... Three of the twenty Kuntscher nailings for femoral fracture.

  18. Nurses’ knowledge of care of chest drain: A survey in a Nigerian semiurban university hospital

    Science.gov (United States)

    Kesieme, Emeka Blessius; Essu, Ifeanyichukwu Stanley; Arekhandia, Bruno Jeneru; Welcker, Katrin; Prisadov, Georgi

    2016-01-01

    Background/Objective: Inefficient nursing care of chest drains may associated with unacceptable and sometimes life-threatening complications. This report aims to ascertain the level of knowledge of care of chest drains among nurses working in wards in a teaching hospital in Nigeria. Methods: A cross-sectional study among nurses at teaching hospital using pretested self-administered questionnaires. Results: The majority were respondents aged between 31 and 40 years (45.4%) and those who have nursing experience between 6 and 10 years. Only 37 respondents (26.2%) had a good knowledge of nursing care of chest drains. Knowledge was relatively higher among nurses who cared for chest drains daily, nurses who have a work experience of 0.05). Performance was poor on the questions on position of drainage system were not statistically significant with relationship to waist level while mobilizing the patient, application of suction to chest drains, daily changing of dressing over chest drain insertion site, milking of tubes and drainage system with dependent loop. Conclusion: The knowledge of care of chest drains among nurses is poor, especially in the key post procedural care. There is an urgent need to train them so as to improve the nursing care of patients managed with chest drains. PMID:26857934

  19. Nutrient uptake and community metabolism in streams draining harvested and old-growth watersheds: A preliminary assessment

    Science.gov (United States)

    Brian H. Hill; Frank H. McCormick

    2004-01-01

    The effect of timber harvesting on streams is assessed using two measures of ecosystem function: nutrient spiraling and community metabolism. This research is being conducted in streams of the southern Appalachian Mountains of North Carolina, the Ouachita Mountains of Arkansas, the Cascade Mountains of Oregon, and the redwood forests of northern California, in order to...

  20. Quantity and quality of phosphorus losses from an artificially drained lowland catchment

    Science.gov (United States)

    Nausch, Monika; Woelk, Jana; Kahle, Petra; Nausch, Günther; Leipe, Thomas; Lennartz, Bernd

    2017-04-01

    Currently, agricultural diffuse sources constitute the major portion of phosphorus (P) fluxes to the Baltic Sea and have to reach the good ecological status aimed by the Baltic Sea Action Plan and the Marine Strategy Framework Directive. The objective of this study was to uncover the change in phosphorus loading as well as in P fractions along the flow path of a mid-size river basin in order to derive risk assessment and management strategies for a sustainable P reduction. P-fractions and the mineral composition of particulate P were investigated in a sub-basin of the river Warnow, the second largest German catchment discharging to the Baltic Sea. Samples were collected from the sources (tile drain, ditch) and along the subsequent brook up to the river Warnow representing spatial scales of a few hectars up to 3300 km2. The investigations were performed during the discharge season from November 1th 2013 until April 30th 2014 covering a relative dry and mild winter period. We observed an increase of total phosphorus (TP) concentrations from 15.5 ± 3.9 µg L-1 in the drain outlet to 72.0 ± 7.2 µg L-1 in the river Warnow emphasizing the importance of sediment-bound P mobilization along the flow path. Particulate phosphorus (PP) of 36.6 - 61.2% accounted for the largest share of TP in the streams. Clay minerals and Fe(hydr)oxides were the main carrier of particle bound P followed by apatite. A transformation of dissolved inorganic phosphorus (DIP) into particulate organic P was observed in the river Warnow with the beginning of the growth season in February. Our investigations indicate that the overall P load could be reduced by half when PP is removed.

  1. Reducing resin use in floor drain processing system

    International Nuclear Information System (INIS)

    Flint, W.; Hobart, S.A.; Miller, A.D.

    1995-01-01

    The Kewaunee Nuclear Power Plant utilizes two mixed bed demineralizers for processing floor drain wastes. These demineralizers were originally designed for stream generator blowdown treatment, but were not needed for that purpose. Effluent from the resin beds is monitored for radioactivity and released for discharge. Plant radwaste inleakage volumes and resin disposal volumes were low in comparison with industry averages, but decontamination factors through the treatment system were less than desirable. Release criteria for discharges always had been met, but plant personnel wished to decrease their already low discharges of radioactive species, reduce their resin disposal costs, and provide a margin of safety in the unlikely event that fuel damage would be experienced during an operating cycle. This paper describes the study initiated to address those issues, the findings of the study, and results of implementing some of the study recommendations

  2. Drain Current Modulation of a Single Drain MOSFET by Lorentz Force for Magnetic Sensing Application.

    Science.gov (United States)

    Chatterjee, Prasenjit; Chow, Hwang-Cherng; Feng, Wu-Shiung

    2016-08-30

    This paper reports a detailed analysis of the drain current modulation of a single-drain normal-gate n channel metal-oxide semiconductor field effect transistor (n-MOSFET) under an on-chip magnetic field. A single-drain n-MOSFET has been fabricated and placed in the center of a square-shaped metal loop which generates the on-chip magnetic field. The proposed device designed is much smaller in size with respect to the metal loop, which ensures that the generated magnetic field is approximately uniform. The change of drain current and change of bulk current per micron device width has been measured. The result shows that the difference drain current is about 145 µA for the maximum applied magnetic field. Such changes occur from the applied Lorentz force to push out the carriers from the channel. Based on the drain current difference, the change in effective mobility has been detected up to 4.227%. Furthermore, a detailed investigation reveals that the device behavior is quite different in subthreshold and saturation region. A change of 50.24 µA bulk current has also been measured. Finally, the device has been verified for use as a magnetic sensor with sensitivity 4.084% (29.6 T(-1)), which is very effective as compared to other previously reported works for a single device.

  3. Radiation dose associated with CT-guided drain placement for pediatric patients

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, Cody J.; Isaacson, Ari J.; Fordham, Lynn Ansley; Ivanovic, Marija; Dixon, Robert G. [University of North Carolina at Chapel Hill, Department of Radiology, UNC Health Care, Chapel Hill, NC (United States); Taylor, J.B. [University of North Carolina at Chapel Hill, Environment, Health and Safety, Chapel Hill, NC (United States)

    2017-05-15

    To date, there are limited radiation dose data on CT-guided procedures in pediatric patients. Our goal was to quantify the radiation dose associated with pediatric CT-guided drain placement and follow-up drain evaluations in order to estimate effective dose. We searched the electronic medical record and picture archiving and communication system (PACS) to identify all pediatric (<18 years old) CT-guided drain placements performed between January 2008 and December 2013 at our institution. We compiled patient data and radiation dose information from CT-guided drain placements as well as pre-procedural diagnostic CTs and post-procedural follow-up fluoroscopic abscess catheter injections (sinograms). Then we converted dose-length product, fluoroscopy time and number of acquisitions to effective doses using Monte Carlo simulations and age-appropriate conversion factors based on annual quality-control testing. Fifty-two drainages were identified with mean patient age of 11.0 years (5 weeks to 17 years). Most children had diagnoses of appendicitis (n=23) or inflammatory bowel disease (n=11). Forty-seven patients had diagnostic CTs, with a mean effective dose of 7.3 mSv (range 1.1-25.5 mSv). Drains remained in place for an average of 16.9 days (range 0-75 days), with an average of 0.9 (0-5) sinograms per patient in follow-up. The mean effective dose for all drainages and follow-up exams was 5.3 mSv (0.7-17.1) and 62% (32/52) of the children had effective doses less than 5 mSv. The majority of pediatric patients who have undergone CT-guided drain placements at our institution have received total radiation doses on par with diagnostic ranges. This information could be useful when describing the dose of radiation to parents and providers when CT-guided drain placement is necessary. (orig.)

  4. Radiation dose associated with CT-guided drain placement for pediatric patients

    International Nuclear Information System (INIS)

    Schwartz, Cody J.; Isaacson, Ari J.; Fordham, Lynn Ansley; Ivanovic, Marija; Dixon, Robert G.; Taylor, J.B.

    2017-01-01

    To date, there are limited radiation dose data on CT-guided procedures in pediatric patients. Our goal was to quantify the radiation dose associated with pediatric CT-guided drain placement and follow-up drain evaluations in order to estimate effective dose. We searched the electronic medical record and picture archiving and communication system (PACS) to identify all pediatric (<18 years old) CT-guided drain placements performed between January 2008 and December 2013 at our institution. We compiled patient data and radiation dose information from CT-guided drain placements as well as pre-procedural diagnostic CTs and post-procedural follow-up fluoroscopic abscess catheter injections (sinograms). Then we converted dose-length product, fluoroscopy time and number of acquisitions to effective doses using Monte Carlo simulations and age-appropriate conversion factors based on annual quality-control testing. Fifty-two drainages were identified with mean patient age of 11.0 years (5 weeks to 17 years). Most children had diagnoses of appendicitis (n=23) or inflammatory bowel disease (n=11). Forty-seven patients had diagnostic CTs, with a mean effective dose of 7.3 mSv (range 1.1-25.5 mSv). Drains remained in place for an average of 16.9 days (range 0-75 days), with an average of 0.9 (0-5) sinograms per patient in follow-up. The mean effective dose for all drainages and follow-up exams was 5.3 mSv (0.7-17.1) and 62% (32/52) of the children had effective doses less than 5 mSv. The majority of pediatric patients who have undergone CT-guided drain placements at our institution have received total radiation doses on par with diagnostic ranges. This information could be useful when describing the dose of radiation to parents and providers when CT-guided drain placement is necessary. (orig.)

  5. Influence of eastern hemlock (Tsuga canadensis L.) on fish community structure and function in headwater streams of the Delaware River basin

    Science.gov (United States)

    Ross, R.M.; Bennett, R.M.; Snyder, C.D.; Young, J.A.; Smith, D.R.; Lemarie, D.P.

    2003-01-01

    Hemlock (Tsuga canadensis) forest of the eastern U.S. are in decline due to invasion by the exotic insect hemlock woolly adelgid (Adelges tsugae). Aquatic biodiversity in hemlock ecosystems has not been documented; thus the true impact of the infestation cannot be assessed. We compared ichthyofaunal assemblages and trophic structure of streams draining hemlock and hardwood forests by sampling first- and second-order streams draining 14 paired hemlock and hardwood stands during base flows in July 1997 at the Delaware Water Gap National Recreation Area of Pennsylvania and New Jersey. Over 1400 fish of 15 species and 7 families were collected, but hemlock and hardwood streams individually harbored only one to four species. Brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) were two to three times as prevalent in hemlock than hardwood streams. Insectivorous fishes occurred in significantly higher proportion in streams of hardwood (0.90) than hemlock (0.46) stands, while piscivores occurred more often in hemlock (0.85) than hardwood (0.54) stands. Functional (trophic) diversity of fishes in hemlock and second-order streams was numerically greater than that of hardwood and first-order streams. Species composition also differed by stream order and terrain type. Biodiversity is threatened at several levels within hemlock ecosystems at risk to the hemlock woolly adelgid in eastern U.S. forests.

  6. Ebullitive methane emissions from oxygenated wetland streams

    Science.gov (United States)

    Crawford, John T.; Stanley, Emily H.; Spawn, Seth A.; Finlay, Jacques C.; Striegl, Robert G.

    2014-01-01

    Stream and river carbon dioxide emissions are an important component of the global carbon cycle. Methane emissions from streams could also contribute to regional or global greenhouse gas cycling, but there are relatively few data regarding stream and river methane emissions. Furthermore, the available data do not typically include the ebullitive (bubble-mediated) pathway, instead focusing on emission of dissolved methane by diffusion or convection. Here, we show the importance of ebullitive methane emissions from small streams in the regional greenhouse gas balance of a lake and wetland-dominated landscape in temperate North America and identify the origin of the methane emitted from these well-oxygenated streams. Stream methane flux densities from this landscape tended to exceed those of nearby wetland diffusive fluxes as well as average global wetland ebullitive fluxes. Total stream ebullitive methane flux at the regional scale (103 Mg C yr−1; over 6400 km2) was of the same magnitude as diffusive methane flux previously documented at the same scale. Organic-rich stream sediments had the highest rates of bubble release and higher enrichment of methane in bubbles, but glacial sand sediments also exhibited high bubble emissions relative to other studied environments. Our results from a database of groundwater chemistry support the hypothesis that methane in bubbles is produced in anoxic near-stream sediment porewaters, and not in deeper, oxygenated groundwaters. Methane interacts with other key elemental cycles such as nitrogen, oxygen, and sulfur, which has implications for ecosystem changes such as drought and increased nutrient loading. Our results support the contention that streams, particularly those draining wetland landscapes of the northern hemisphere, are an important component of the global methane cycle.

  7. Stream carbon dynamics in low-gradient headwaters of a forested watershed

    Science.gov (United States)

    April Bryant-Mason; Y. Jun Xu; Johnny M. Grace

    2013-01-01

    Headwater streams drain more than 70 percent of the total watershed area in the United States. Understanding of carbon dynamics in the headwater systems is of particular relevance for developing best silvicultural practices to reduce carbon export. This study was conducted in a low-gradient, predominantly forested watershed located in the Gulf Coastal Plain region, to...

  8. Effect of an intervention in storm drains to prevent Aedes aegypti reproduction in Salvador, Brazil.

    Science.gov (United States)

    Souza, Raquel Lima; Mugabe, Vánio André; Paploski, Igor Adolfo Dexheimer; Rodrigues, Moreno S; Moreira, Patrícia Sousa Dos Santos; Nascimento, Leile Camila Jacob; Roundy, Christopher Michael; Weaver, Scott C; Reis, Mitermayer Galvão; Kitron, Uriel; Ribeiro, Guilherme Sousa

    2017-07-11

    Aedes aegypti, the principal vector for dengue, chikungunya and Zika viruses, is a synanthropic species that uses stagnant water to complete its reproductive cycle. In urban settings, rainfall water draining structures, such as storm drains, may retain water and serve as a larval development site for Aedes spp. reproduction. Herein, we describe the effect of a community-based intervention on preventing standing water accumulation in storm drains and their consequent infestation by adult and immature Ae. aegypti and other mosquitoes. Between April and May of 2016, local residents association of Salvador, Brazil, after being informed of water accumulation and Ae. aegypti infestation in the storm drains in their area, performed an intervention on 52 storm drains. The intervention consisted of placing concrete at the bottom of the storm drains to elevate their base to the level of the outflow tube, avoiding water accumulation, and placement of a metal mesh covering the outflow tube to avoid its clogging with debris. To determine the impact of the intervention, we compared the frequency at which the 52 storm drains contained water, as well as adult and immature mosquitoes using data from two surveys performed before and two surveys performed after the intervention. During the pre-intervention period, water accumulated in 48 (92.3%) of the storm drains, and immature Ae. aegypti were found in 11 (21.2%) and adults in 10 (19.2%). After the intervention, water accumulated in 5 (9.6%) of the storm drains (P Aedes mosquitoes (mainly Culex spp.) in the storm drains also decreased after the intervention. This study exemplifies how a simple intervention targeting storm drains can result in a major reduction of water retention, and, consequently, impact Ae. aegypti larval populations. Larger and multi-center evaluations are needed to confirm the potential of citywide structural modifications of storm drains to reduce Aedes spp. infestation level.

  9. A Rare Complication of Abdominal Drain: Fallopian Tube Herniation Through the Drain Site

    OpenAIRE

    Dilek Uygur; Seval Erdinç; Hülya Dede; Ümit Taşdemir; Oktay Kaymak; Nuri Danışman

    2016-01-01

    Prophylactic drainage of the peritoneal cavity after obstetrical and gynecological surgery is widely practiced. The idea of “when in doubt, drain” is accepted and applied clinically by many surgeons. However, surgically placed drains are not without risk. The present case describes herniation of fallopian tube during the removal of a surgical drain placed after a cesarean section.

  10. Sources and transformations of nitrate from streams draining varying land uses: Evidence from dual isotope analysis

    Science.gov (United States)

    Burns, Douglas A.; Boyer, E.W.; Elliott, E.M.; Kendall, C.

    2009-01-01

    Knowledge of key sources and biogeochemical processes that affect the transport of nitrate (NO3-) in streams can inform watershed management strategies for controlling downstream eutrophication. We applied dual isotope analysis of NO3- to determine the dominant sources and processes that affect NO3- concentrations in six stream/river watersheds of different land uses. Samples were collected monthly at a range of flow conditions for 15 mo during 2004-05 and analyzed for NO3- concentrations, ?? 15NNO3, and ??18ONO3. Samples from two forested watersheds indicated that NO3- derived from nitrification was dominant at baseflow. A watershed dominated by suburban land use had three ??18ONO3 values greater than +25???, indicating a large direct contribution of atmospheric NO 3- transported to the stream during some high flows. Two watersheds with large proportions of agricultural land use had many ??15NNO3 values greater than +9???, suggesting an animal waste source consistent with regional dairy farming practices. These data showed a linear seasonal pattern with a ??18O NO3:??15NNO3 of 1:2, consistent with seasonally varying denitrification that peaked in late summer to early fall with the warmest temperatures and lowest annual streamflow. The large range of ?? 15NNO3 values (10???) indicates that NO 3- supply was likely not limiting the rate of denitrification, consistent with ground water and/or in-stream denitrification. Mixing of two or more distinct sources may have affected the seasonal isotope patterns observed in these two agricultural streams. In a mixed land use watershed of large drainage area, none of the source and process patterns observed in the small streams were evident. These results emphasize that observations at watersheds of a few to a few hundred km2 may be necessary to adequately quantify the relative roles of various NO 3- transport and process patterns that contribute to streamflow in large basins. Copyright ?? 2009 by the American Society of

  11. Dating base flow in streams using dissolved gases and diurnal temperature changes

    Science.gov (United States)

    Sanford, Ward E.; Casile, Gerolamo C.; Haase, Karl B.

    2015-01-01

    A method is presented for using dissolved CFCs or SF6 to estimate the apparent age of stream base flow by indirectly estimating the mean concentration of the tracer in the inflowing groundwater. The mean value is estimated simultaneously with the mean residence times of the gas and water in the stream by sampling the stream for one or both age tracers, along with dissolved nitrogen and argon at a single location over a period of approximately 12–14 h. The data are fitted to an equation representing the temporal in-stream gas exchange as it responds to the diurnal temperature fluctuation. The efficacy of the method is demonstrated by collecting and analyzing samples at six different stream locations across parts of northern Virginia, USA. The studied streams drain watersheds with areas of between 2 and 122 km2 during periods when the diurnal stream temperature ranged between 2 and 5°C. The method has the advantage of estimating the mean groundwater residence time of discharge from the watershed to the stream without the need for the collection of groundwater infiltrating to streambeds or local groundwater sampled from shallow observation wells near the stream.

  12. EXPERIMENTAL EFFECTS OF CONDUCTIVITY AND MAJOR IONS ON STREAM PERIPHYTON - abstract

    Science.gov (United States)

    Our study examined if specific conductivities comprised of different ions associated with resource extraction affected stream periphyton assemblages, which are important sources of primary production. Sixteen artificial streams were dosed with two ion recipes intended to mimic so...

  13. Stream capture to form Red Pass, northern Soda Mountains, California

    Science.gov (United States)

    Miller, David; Mahan, Shannon

    2014-01-01

    Red Pass, a narrow cut through the Soda Mountains important for prehistoric and early historic travelers, is quite young geologically. Its history of downcutting to capture streams west of the Soda Mountains, thereby draining much of eastern Fort Irwin, is told by the contrast in alluvial fan sediments on either side of the pass. Old alluvial fan deposits (>500 ka) were shed westward off an intact ridge of the Soda Mountains but by middle Pleistocene time, intermediate-age alluvial fan deposits (~100 ka) were laid down by streams flowing east through the pass into Silurian Valley. The pass was probably formed by stream capture driven by high levels of groundwater on the west side. This is evidenced by widespread wetland deposits west of the Soda Mountains. Sapping and spring discharge into Silurian Valley over millennia formed a low divide in the mountains that eventually was overtopped and incised by a stream. Lessons include the importance of groundwater levels for stream capture and the relatively youthful appearance of this ~100-200 ka feature in the slowly changing Mojave Desert landscape.

  14. Assimilation of old carbon by stream food webs in arctic Alaska

    Science.gov (United States)

    O'Donnell, J. A.; Carey, M.; Xu, X.; Koch, J. C.; Walker, J. C.; Zimmerman, C. E.

    2017-12-01

    Permafrost thaw in arctic and sub-arctic region is mobilizing old carbon (C) from perennially frozen soils, driving the release of old C to the atmosphere and to aquatic ecosystems. Much research has focused on the transport and lability of old dissolved organic C (DOC) as a possible feedback to the climate system following thaw. However, little is known about the role of old C as a source to aquatic food webs in watersheds underlain by thawing permafrost. To quantify the contributions of old C to Arctic stream food-webs, we measured the radiocarbon (Δ14C) and stable isotope (δ13C, δ15N) contents of periphyton, macroinvertebrates, and resident fish species (Arctic Grayling (Thymallus arcticus) and Dolly Varden (Salvelinus malma)). We also characterized the isotopic composition of possible C sources, including DOC, dissolved inorganic carbon (DIC), and soil organic matter. Samples were collected across 10 streams in Arctic Alaska, draining watersheds underlain by varying parent material and ground-ice content, from ice-poor bedrock to ice-rich loess (i.e. Yedoma). Fraction modern (FM) values for Arctic Grayling and Dolly Varden ranged from 0.6720 to 1.0101 (3195 years BP to modern) across all streams, and closely tracked spatial variation in Δ14C content of periphyton. Parent material and ground-ice content appear to govern the age and form of dissolved C sources to stream biota. For instance, in watersheds underlain by ice-poor bedrock, old DIC (< 5000 years BP) was the dominant C source to stream biota, reflecting contributions from carbonate weathering and soil respiration. In streams draining ice-rich Yedoma, high concentrations of younger DOC were the primary C source to stream biota, reflecting leaching of DOC from saturated, peaty soils of the active layer. These findings highlight the importance of permafrost characteristics as a control on subsurface hydrology and the delivery of aged C to surface waters. Given the large stores Pleistocene-aged organic

  15. A Rare Complication of Abdominal Drain: Fallopian Tube Herniation Through the Drain Site

    Directory of Open Access Journals (Sweden)

    Dilek Uygur

    2016-05-01

    Full Text Available Prophylactic drainage of the peritoneal cavity after obstetrical and gynecological surgery is widely practiced. The idea of “when in doubt, drain” is accepted and applied clinically by many surgeons. However, surgically placed drains are not without risk. The present case describes herniation of fallopian tube during the removal of a surgical drain placed after a cesarean section.

  16. Cover Crops for Managing Stream Water Quantity and Improving Stream Water Quality of Non-Tile Drained Paired Watersheds

    OpenAIRE

    Gurbir Singh; Jon E. Schoonover; Karl W. J. Williard

    2018-01-01

    In the Midwestern United States, cover crops are being promoted as a best management practice for managing nutrient and sediment losses from agricultural fields through surface and subsurface water movement. To date, the water quality benefits of cover crops have been inferred primarily from plot scale studies. This project is one of the first to analyze the impacts of cover crops on stream water quality at the watershed scale. The objective of this research was to evaluate nitrogen, phosphor...

  17. Changing Groundwater-Surface Water Interactions Impact Stream Chemistry and Ecology at the Arctic-Boreal Transition in Western Alaska

    Science.gov (United States)

    Koch, J. C.; Carey, M.; O'Donnell, J.; Sjoberg, Y.; Zimmerman, C. E.

    2016-12-01

    The arctic-boreal transition zone of Alaska is experiencing rapid change related to unprecedented warming and subsequent loss of permafrost. These changes in turn may affect groundwater-surface water (GW-SW) interactions, biogeochemical cycling, and ecosystem processes. While recent field and modeling studies have improved our understanding of hydrology in watersheds underlain by thawing permafrost, little is known about how these hydrologic shifts will impact bottom-up controls on stream food webs. To address this uncertainty, we are using an integrative experimental design to link GW-SW interactions to stream biogeochemistry and biota in 10 first-order streams in northwest Alaska. These study streams drain watersheds that span several gradients, including elevation, aspect, and vegetation (tundra vs. forest). We have developed a robust, multi-disciplinary data set to characterize GW-SW interactions and to mechanistically link GW-SW dynamics to water quality and the stream ecosystem. Data includes soil hydrology and chemistry; stream discharge, temperature, and inflow rates; water chemistry (including water isotopes, major ions, carbon concentration and isotopes, nutrients and chlorophyll-a), and invertebrate and fish communities. Stream recession curves indicate a decreasing rate later in the summer in some streams, consistent with seasonal thaw in lower elevation and south-facing catchments. Base cation and water isotope chemistry display similar impacts of seasonal thaw and also suggest the dominance of groundwater in many streams. Coupled with estimates of GW-SW exchange at point, reach, and catchment scales, these results will be used to predict how hydrology and water quality are likely to impact fish habitat and growth given continued warming at the arctic-boreal transition.

  18. Roundtable. Strategies to discourage brain drain.

    Science.gov (United States)

    Kupfer, Linda; Hofman, Karen; Jarawan, Raya; McDermott, Jeanne; Bridbord, Ken

    2004-08-01

    Building health research expertise in developing countries often requires personnel to receive training beyond national borders. For research funding agencies that sponsor this type of training, a major goal is to ensure that trainees return to their country of origin: attaining this objective requires the use of proactive strategies. The strategies described were developed under the extramural acquired immunodeficiency syndrome (AIDS) International Training and Research Program (AITRP) funded by the Fogarty International Center (FIC) at the National Institutes of Health, United States. This programme supports universities in the United States that provide research training to scientists from developing countries to enable them to address the global epidemic of human immunodeficiency virus (HIV)/AIDS and the related tuberculosis (TB) epidemic. This paper describes the strategies employed to discourage brain drain by the principle investigators (PIs) of five of the longest-funded AITRPs (funded for 15 years). Long-term trainees in these programmes spent from 11 to 96 months (an average of 26 months) studying. Using scientific, political and economic strategies that address brain drain issues, PIs working in AITRPs have attained an average rate of return home for their trainees of 80%.

  19. Forested wetland mitigation resulting from discharges of cooling water into streams

    International Nuclear Information System (INIS)

    Nelson, E.A.

    1993-01-01

    The Savannah River Swamp is a 3020-ha forested wetland on the floodplain of the Savannah River and is located on the US Department of Energy's Savannah River Site (SRS) near Aiken, South Carolina. Historically, the swamp consisted of ∼50% bald cypress-water tupelo stands, 40% mixed bottomland hardwood stands, and 10% shrub, marsh, and open water. The hydrology was controlled by flooding the Savannah River and by flow from four creeks that drain into the swamp prior to flow into the Savannah River. Upstream dams have caused some alteration of the water levels and timing of flooding within the floodplain. Major impacts to the swamp hydrology occurred with the completion of the production reactors and one coal-fired powerhouse at the SRS in the early 1950s. Water, often in excess of 40 to 50 degrees C was discharged into one of the small streams from 1954 to 1988, at various levels, ranging from 20 to 40 times the prior flow rate of the stream. This had a major impact on the adjacent swamp land, with erosion, silting, and vegetation destruction. The Final Environmental Impact Statement, Continued Operation of K, L, and P Reactors, Savannah River Site, Aiken, South Carolina, and the subsequent record of decision directed that these areas be restored to functional forested wetland status to the extent possible. This paper describes work begun to reach that objective

  20. Necessity of suction drains in gynecomastia surgery.

    Science.gov (United States)

    Keskin, Mustafa; Sutcu, Mustafa; Cigsar, Bulent; Karacaoglan, Naci

    2014-05-01

    The aim of gynecomastia surgery is to restore a normal chest contour with minimal signs of breast surgery. The authors examine the rate of complications in gynecomastia surgery when no closed-suction drains are placed. One hundred thirty-eight consecutive male patients who underwent gynecomastia surgery without drains were retrospectively analyzed to determine whether the absence of drains adversely affected patient outcomes. Patients were managed by ultrasonic-assisted liposuction both with and without the pull-through technique. The mean age of the patients was 29 years, and the mean volume of breast tissue aspirated was 350 mL per beast. Pull-through was needed in 23 cases. There was only 1 postoperative hematoma. These results are comparable with previously published data for gynecomastia surgery in which drains were placed, suggesting that the absence of drains does not adversely affect postoperative recovery. Routine closed-suction drainage after gynecomastia surgery is unnecessary, and it may be appropriate to omit drains after gynecomastia surgery.

  1. Long-Term Trends in Nutrient Concentrations and Fluxes in Streams Draining to Lake Tahoe, California

    Science.gov (United States)

    Domagalski, J. L.

    2017-12-01

    Lake Tahoe, situated in the rain shadow of the eastern Sierra Nevada at an elevation of 1,897 meters, has numerous small to medium sized tributaries that are sources of nutrients and fine sediment. The Tahoe watershed is relatively small and the surface area of the lake occupies about 38% of the total watershed area (1,313 km2). Each stream contributing water to the lake therefore also occupies a small watershed, mostly forested, with typical trees being Jeffrey, Ponderosa, or Sugar Pine and White Fir. Outflow from the lake contributes to downstream uses such as water supply and ecological resources. Only about 6% of the watershed is urbanized or residential land, and wastewater is exported to adjacent basins and not discharged to the lake as part of a plan to maintain water clarity. The lake's exceptional clarity has been diminishing due to phytoplankton and fine sediment, prompting development of management plans to improve water quality. Much of the annual discharge and flux of nutrients to the lake results from snowmelt in the spring and summer months, and climatic changes have begun to shift this melt to earlier time frames. Winter rains on urbanized land also contribute to nutrient loads. To understand the relative importance of land use, climate, and other factors affecting stream concentrations and fluxes, a Weighted Regression on Time Discharge and Season (WRTDS) model documented trends over a time frame of greater than 25 years. Ten streams have records of discharge, nutrient (NO3, NH3, OP, TP, TKN) and sediment data to complete this analysis. Both urbanized and non-urbanized locations generally show NO3 trending down in the 1980s. Some locations show initially decreasing orthophosphate trends, followed by small significant increases in concentration and fluxes starting around 2000 to 2005. Although no wastewater enters the streams, ammonia concentrations mimic those of orthophosphate, with initially negative trends in concentration and flux followed by

  2. 21 CFR 868.5995 - Tee drain (water trap).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tee drain (water trap). 868.5995 Section 868.5995...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5995 Tee drain (water trap). (a) Identification. A tee drain (water trap) is a device intended to trap and drain water that collects in ventilator...

  3. Development of rationalized system treating floor drain

    International Nuclear Information System (INIS)

    Nakamura, Yasuyuki; Serizawa, Kenichi; Komatsu, Akihiro; Shimizu, Takayuki

    1998-01-01

    Radioactive liquid wastes generated at BWR plants are collected and treated as required. These days, however, generation of floor drain has deceased and HFF (Hollow Fiber Filter) has experienced a wide applicability to several kinds of liquid wastes. We should consider that the floor drain can be mixed and diluted with equipment drain and be purified by HFF. That enables some of the sumps and long priming pipes to be combined. From this point of view, we have developed a highly rationalized waste liquid system. We have evaluated the applicability of this system after an investigation into the generation and properties of floor drain and equipment drain at the latest BWR'S and an on-site test at a typical BWR. (author)

  4. How to remove a chest drain.

    Science.gov (United States)

    Allibone, Elizabeth

    2015-10-07

    RATIONALE AND KEY POINTS: This article aims to help nurses to undertake the removal of a chest drain in a safe, effective and patient-centred manner. This procedure requires two practitioners. The chest drain will have been inserted aseptically to remove air, blood, fluid or pus from the pleural cavity. ▶ Chest drains may be small or wide bore depending on the underlying condition and clinical setting. They may be secured with a mattress suture and/or an anchor suture. ▶ Chest drains are usually removed under medical instructions when the patient's lung has inflated, the underlying condition has resolved, there is no evidence of respiratory compromise or failure, and their anticoagulation status has been assessed as satisfactory. ▶ Chest drains secured with a mattress suture should be removed by two practitioners. One practitioner is required to remove the tube and the other to tie the mattress suture (if present) and secure the site. REFLECTIVE ACTIVITY: Clinical skills articles can help update your practice and ensure it remains evidence based. Apply this article to your practice. Reflect on and write a short account of: 1. How reading this article will change your practice. 2. How this article could be used to educate patients with chest drains. Subscribers can upload their reflective accounts at: rcni.com/portfolio .

  5. Nitrogen Dynamics Along a Headwater Stream Draining a Fen, Swamp, and Marsh in a Fractured Dolomite Watershed

    Science.gov (United States)

    Duval, T. P.; Waddington, J. M.

    2009-05-01

    Stream-wetland interaction has been shown to have a significant effect on nutrient cycling and downstream water quality. Additionally, connection to regional groundwater systems can dilute or enrich stream water with a number of dissolved constituents. This study demonstrates the resultant downstream change in dissolved nitrogen species as a hardwater stream emerges from a calcareous aquifer and traverses a calcareous fen, a cedar swamp, and a cattail marsh over two growing seasons, a very dry 2006 and a very wet 2007. Upon emergence at a number of groundwater seeps, the water contained appreciable nitrate levels averaging 2.72±0.42 mg NO3-N L-1, minimal organic nitrogen, and ammonium below detectable levels. Through the gently sloping calcareous fen, with a stream residence time of ~ 5 hours, NO3-N concentration decreases of 0.35 mg L-1 were observed. Concomitantly, stream recharge into the dolomite bedrock depressed stream discharge values significantly, further removing nitrate from the stream system. This resulted in the fen-bedrock system acting as an estimated net sink of 432 kg of NO3-N in the early summer of 2007, for example. In contrast, the hydrological-biogeochemical systems became decoupled through the swamp during the same period, where concentrations increased from 2.58±0.34 mg L-1 entering the swamp to 2.65±0.58 mg L-1 exiting, but streamflow decreased in general by 5 L s- 1. This resulted in the swamp, with its large depression storage, acting as a small net sink of nitrate (75 kg through the early summer), which would not be detected simply from concentration changes. The concentration-discharge relation realigned through the marsh, where significant groundwater entered the wetland, increasing both concentration and discharge, yielding a small export of 93 kg over the same time period. A series of tracer injections in each wetland type will be presented to compare the streamflow- concentration patterns with the measured nutrient spiralling

  6. In patients with extensive subcutaneous emphysema, which technique achieves maximal clinical resolution: infraclavicular incisions, subcutaneous drain insertion or suction on in situ chest drain?

    Science.gov (United States)

    Johnson, Charles H N; Lang, Sommer A; Bilal, Haris; Rammohan, Kandadai S

    2014-06-01

    A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: 'In patients with extensive subcutaneous emphysema, which technique achieves maximal clinical resolution: infraclavicular incisions, subcutaneous drain insertion or suction on in situ chest drain?'. Altogether more than 200 papers were found using the reported search, of which 14 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Subcutaneous emphysema is usually a benign, self-limiting condition only requiring conservative management. Interventions are useful in the context of severe patient discomfort, respiratory distress or persistent air leak. In the absence of any comparative study, it is not possible to choose definitively between infraclavicular incisions, drain insertion and increasing suction on an in situ drain as the best method for managing severe subcutaneous emphysema. All the three techniques described have been shown to provide effective relief. Increasing suction on a chest tube already in situ provided rapid relief in patients developing SE following pulmonary resection. A retrospective study showed resolution in 66%, increasing to 98% in those who underwent video-assisted thoracic surgery with identification and closure of the leak. Insertion of a drain into the subcutaneous tissue also provided rapid sustained relief. Several studies aided drainage by using regular compressive massage. Infraclavicular incisions were also shown to provide rapid relief, but were noted to be more invasive and carried the potential for cosmetic defect. No major complications were illustrated. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  7. 216-Z-8 French drain characterization study

    International Nuclear Information System (INIS)

    Marratt, M.C.; Kasper, R.B.; Van Luik, A.E.

    1984-09-01

    The 216-Z-8 French drain study is one of a series of studies examining historical transuranic waste facilities no longer in use at the Hanford Site. The 216-Z-8 French drain underground disposal system consisted of a large settling tank that overflowed into a French drain. The French drain consisted of two large-diameter, gravel filled, vitrified clay pipes placed on end, end-to-end, over a gravel-filled excavation. The top of the drain was sealed with concrete to prevent the upward flow of waste solution. The waste solution discharged to the 216-Z-8 waste disposal system was a neutralized, transuranic recovery process, filter cake, backflush slurry. The primary objective of this study was to determine the distribution of plutonium and americium beneath the French drain. Transuranic activity under the French drain did not exceed 5 nCi/g in the soil samples obtained from a well within 1 m of the drain structure. Conservative estimates indicated that 4 to 5 m 3 of radioactive contaminated sediments, 10 nCi/g may lie directly under the 216-Z-8 French drain. The secondary objective of the study was to evaluate the possibility of a leak in the settling tank. Results from the analysis of soil samples from wells drilled around the settling tank indicated the presence of low-level transuranic contamination (on the order of 0.001 nci/g) in the soil surrounding the tank. However, the distribution of the contamination does not support a leak as a plausible mechanism to account for the observed activity surrounding the tank. The bulk of the plutonium was confirmed to be in the sludge that remained in the tank; thus, no significant environmental impact would be expected even if there has been a leak

  8. Investigating high zircon concentrations in the fine fraction of stream sediments draining the Pan-African Dahomeyan Terrane in Nigeria

    International Nuclear Information System (INIS)

    Key, Roger M.; Johnson, Christopher C.; Horstwood, Matthew S.A.; Lapworth, Dan J.; Knights, Katherine V.; Kemp, Simon J.; Watts, Michael; Gillespie, Martin; Adekanmi, Michael; Arisekola, Tunde

    2012-01-01

    Sixteen hundred stream sediments (<150 μm fraction) collected during regional geochemical surveys in central and SW Nigeria have high median and maximum concentrations of Zr that exceed corresponding Zr concentrations found in stream sediments collected from elsewhere in the World with similar bedrock geology. X-ray diffraction studies on a sub-set of the analysed stream sediments showed that Zr is predominantly found in detrital zircon grains. However, the main proximal source rocks (Pan-African ‘Older Granites’ of Nigeria and their Proterozoic migmatitic gneiss country rocks) are not enriched in zircon (or Zr). Nevertheless, U–Pb LA-ICP-MS dating with cathodoluminescence imaging on detrital zircons, both from stream sediment samples and underlying Pan-African ‘Older Granites’ confirms a local bedrock source for the stream sediment zircons. A combination of tropical/chemical weathering and continuous physical weathering, both by ‘wet season’ flash flooding and ‘dry season’ unidirectional winds are interpreted to have effectively broken down bedrock silicate minerals and removed much of the resultant clay phases, thereby increasing the Zr contents in stream sediments. The strong correlation between winnowing index (Th/Al) and Zr concentration across the study area support this interpretation. Therefore, ‘anomalous’ high values of Zr, as well as other elements concentrated in resistant ‘heavy’ minerals in Nigeria’s streams may not reflect proximal bedrock concentrations of these elements. This conclusion has important implications for using stream sediment chemistry as an exploration tool in Nigeria for primary metal deposits associated with heavy minerals.

  9. Drain site evisceration of fallopian tube, another reason to discourage abdominal drain: report of a case and brief review of literature.

    Science.gov (United States)

    Saini, Pradeep; Faridi, M S; Agarwal, Nitin; Gupta, Arun; Kaur, Navneet

    2012-04-01

    Placement of a drain following abdominal surgery is common despite a lack of convincing evidence in the current literature to support this practice. The use of intra-abdominal drain is associated with many potential and serious complications. We report a drain site evisceration of the right fallopian tube after the removal of an intra-abdominal drain. The drain was placed in the right iliac fossa in a patient who underwent a lower segment Caesarean section (LSCS) for meconium liquor with fetal distress. The Pfannenstiel incision made for LSCS was reopened and the protruding inflamed fimbrial end of the right fallopian tube was excised. The patient made an uneventful recovery. Routine intra-abdominal prophylactic drain following an abdominal surgery including LSCS should be discouraged.

  10. Seasonal pattern of anthropogenic salinization in temperate forested headwater streams.

    Science.gov (United States)

    Timpano, Anthony J; Zipper, Carl E; Soucek, David J; Schoenholtz, Stephen H

    2018-04-15

    Salinization of freshwaters by human activities is of growing concern globally. Consequences of salt pollution include adverse effects to aquatic biodiversity, ecosystem function, human health, and ecosystem services. In headwater streams of the temperate forests of eastern USA, elevated specific conductance (SC), a surrogate measurement for the major dissolved ions composing salinity, has been linked to decreased diversity of aquatic insects. However, such linkages have typically been based on limited numbers of SC measurements that do not quantify intra-annual variation. Effective management of salinization requires tools to accurately monitor and predict salinity while accounting for temporal variability. Toward that end, high-frequency SC data were collected within the central Appalachian coalfield over 4 years at 25 forested headwater streams spanning a gradient of salinity. A sinusoidal periodic function was used to model the annual cycle of SC, averaged across years and streams. The resultant model revealed that, on average, salinity deviated approximately ±20% from annual mean levels across all years and streams, with minimum SC occurring in late winter and peak SC occurring in late summer. The pattern was evident in headwater streams influenced by surface coal mining, unmined headwater reference streams with low salinity, and larger-order salinized rivers draining the study area. The pattern was strongly responsive to varying seasonal dilution as driven by catchment evapotranspiration, an effect that was amplified slightly in unmined catchments with greater relative forest cover. Evaluation of alternative sampling intervals indicated that discrete sampling can approximate the model performance afforded by high-frequency data but model error increases rapidly as discrete sampling intervals exceed 30 days. This study demonstrates that intra-annual variation of salinity in temperate forested headwater streams of Appalachia USA follows a natural seasonal

  11. Obtaining Streamflow Statistics for Massachusetts Streams on the World Wide Web

    Science.gov (United States)

    Ries, Kernell G.; Steeves, Peter A.; Freeman, Aleda; Singh, Raj

    2000-01-01

    A World Wide Web application has been developed to make it easy to obtain streamflow statistics for user-selected locations on Massachusetts streams. The Web application, named STREAMSTATS (available at http://water.usgs.gov/osw/streamstats/massachusetts.html ), can provide peak-flow frequency, low-flow frequency, and flow-duration statistics for most streams in Massachusetts. These statistics describe the magnitude (how much), frequency (how often), and duration (how long) of flow in a stream. The U.S. Geological Survey (USGS) has published streamflow statistics, such as the 100-year peak flow, the 7-day, 10-year low flow, and flow-duration statistics, for its data-collection stations in numerous reports. Federal, State, and local agencies need these statistics to plan and manage use of water resources and to regulate activities in and around streams. Engineering and environmental consulting firms, utilities, industry, and others use the statistics to design and operate water-supply systems, hydropower facilities, industrial facilities, wastewater treatment facilities, and roads, bridges, and other structures. Until now, streamflow statistics for data-collection stations have often been difficult to obtain because they are scattered among many reports, some of which are not readily available to the public. In addition, streamflow statistics are often needed for locations where no data are available. STREAMSTATS helps solve these problems. STREAMSTATS was developed jointly by the USGS and MassGIS, the State Geographic Information Systems (GIS) agency, in cooperation with the Massachusetts Departments of Environmental Management and Environmental Protection. The application consists of three major components: (1) a user interface that displays maps and allows users to select stream locations for which they want streamflow statistics (fig. 1), (2) a data base of previously published streamflow statistics and descriptive information for 725 USGS data

  12. Variation in summer nitrogen and phosphorus uptake among Siberian headwater streams

    Directory of Open Access Journals (Sweden)

    John D. Schade

    2016-06-01

    Full Text Available Arctic streams are likely to receive increased inputs of dissolved nutrients and organic matter from thawing permafrost as climate warms. Documenting how Arctic streams process inorganic nutrients is necessary to understand mechanisms that regulate watershed fluxes of permafrost-derived materials to downstream ecosystems. We report on summer nitrogen (N and phosphorus (P uptake in streams draining upland soils from the Pleistocene, and lowland floodplain soils from the Holocene, in Siberia's Kolyma River watershed. Uptake of N and P differed between upland and floodplain streams, suggesting topographic variation in nutrient limitation. In floodplain streams, P uptake rate and uptake velocity were higher than N, while upland streams had similar values for all N and P uptake metrics. Phosphorus uptake velocity and size of the transient hydrologic storage zone were negatively related across all study streams, indicating strong influence of hydrologic processes on nutrient fluxes. Physical sorption of P was higher in floodplain stream sediments relative to upland stream sediments, suggesting more physically driven uptake in floodplain streams and higher biological activity in upland streams. Overall, these results demonstrate that high-latitude headwater streams actively retain N and P during summer base flows; however, floodplain and upland streams varied substantially in N and P uptake and may respond differently to inorganic nutrient and organic matter inputs. Our results highlight the need for a comprehensive assessment of N and P uptake and retention in Arctic streams in order to fully understand the impact of permafrost-derived materials on ecosystem processes, and their fate in continental drainage networks.

  13. Penrose Drain Migration After Laparoscopic Surgery

    Directory of Open Access Journals (Sweden)

    Pazouki AbdolReza

    2009-05-01

    Full Text Available Laparoscopy has made a revolution in surgical procedures and treatment of various diseases but its complications are still under investigation. Intra-abdominal visceral and vessel injuries, trocar site hernia, and leaving foreign bodies into the peritoneal cavity are among some laparoscopic surgery complications. This is a rare report of Penrose drain migration following incomplete laparoscopic Fundoplication surgery. The patient was a 47- year- old woman, who was a candidate for Touplet Fundoplication via laparoscopic approach due to refractory gastro-esophageal reflux disease (GERD. While wrapping a Penrose drain around the esophagus, the patient had a cardiorespiratory arrest. Attempts to remove the Penrose drain were unsuccessful and the surgical procedure was terminated due to patient's condition. Four months later, after a long period of dysphagia and abdominal pain, the Penrose drain was defecated via rectum.

  14. Beyond the edge: Linking agricultural landscapes, stream networks, and best management practices

    Science.gov (United States)

    Kreiling, Rebecca M.; Thoms, Martin C.; Richardson, William B.

    2018-01-01

    Despite much research and investment into understanding and managing nutrients across agricultural landscapes, nutrient runoff to freshwater ecosystems is still a major concern. We argue there is currently a disconnect between the management of watershed surfaces (agricultural landscape) and river networks (riverine landscape). These landscapes are commonly managed separately, but there is limited cohesiveness between agricultural landscape-focused research and river science, despite similar end goals. Interdisciplinary research into stream networks that drain agricultural landscapes is expanding but is fraught with problems. Conceptual frameworks are useful tools to order phenomena, reveal patterns and processes, and in interdisciplinary river science, enable the joining of multiple areas of understanding into a single conceptual–empirical structure. We present a framework for the interdisciplinary study and management of agricultural and riverine landscapes. The framework includes components of an ecosystems approach to the study of catchment–stream networks, resilience thinking, and strategic adaptive management. Application of the framework is illustrated through a study of the Fox Basin in Wisconsin, USA. To fully realize the goal of nutrient reduction in the basin, we suggest that greater emphasis is needed on where best management practices (BMPs) are used within the spatial context of the combined watershed–stream network system, including BMPs within the river channel. Targeted placement of BMPs throughout the riverine landscape would increase the overall buffering capacity of the system to nutrient runoff and thus its resilience to current and future disturbances.

  15. Leak or Fistula After Sleeve Gastrectomy: Treatment with Pigtail Drain by the Rendezvous Technique.

    Science.gov (United States)

    Soufron, Jacques

    2015-10-01

    After a sleeve gastrectomy, a leak or fistula is a serious complication. Laparoscopic drainage, drainage under US or CT scan control, or endoscopic insertion of a stent can be used, but a major re-operation is sometimes unavoidable. Endoscopic drainage with a pigtail catheter could give more success and fewer complications, but the insertion of the drain is not always possible nor does it always provide a perfect drainage. If a laparoscopic second look appears necessary, it is possible to insert a pigtail drain laparoscopically, but under endoscopic control, ensuring a correct positioning of the drain both in the peritoneal cavity and in the gastric tube. This simultaneous "rendezvous" technique could combine in this situation the advantages of purely surgical techniques and of purely endoscopic or image-guided techniques.

  16. Physical, chemical, and biological characteristics of selected headwater streams along the Allegheny Front, Blair County, Pennsylvania, July 2011–September 2013

    Science.gov (United States)

    Low, Dennis J.; Brightbill, Robin A.; Eggleston, Heather L.; Chaplin, Jeffrey J.

    2016-02-29

    The Altoona Water Authority (AWA) obtains all of its water supply from headwater streams that drain western Blair County, an area underlain in part by black shale of the Marcellus Formation. Development of the shale-gas reservoirs will require new access roads, stream crossing, drill-pad construction, and pipeline installation, activities that have the potential to alter existing stream channel morphology, increase runoff and sediment supply, alter streamwater chemistry, and affect aquatic habitat. The U.S. Geological Survey, in cooperation with Altoona Water Authority and Blair County Conservation District, investigated the water quality of 12 headwater streams and biotic health of 10 headwater streams.

  17. Geological differentiation explains diversity and composition of fish communities in upland streams in the southern Amazon of Colombia

    NARCIS (Netherlands)

    Arbeláez, F.; Duivenvoorden, J.F.; Maldonado-Ocampo, J.A.

    2008-01-01

    Fish biomass, species richness and composition were compared between upland streams draining two contrasting geological units (Pebas and Tsa) in Colombian Amazonia. Because Pebas sediments reportedly show higher levels of base concentrations than Tsa sediments, we expected that the fish communities

  18. The water quality of streams draining a plantation forest on gley soils: the Nant Tanllwyth, Plynlimon mid-Wales

    Directory of Open Access Journals (Sweden)

    C. Neal

    2004-01-01

    Full Text Available The water quality of the Nant Tanllwyth stream in the Plynlimon region of mid-Wales is related to the key hydrobiogeological controls and the effects of conifer harvesting based on an analysis of rain, cloud, stream and groundwater measurements. The results show the normal patterns of stream water quality response to hydrology. Thus, there is a high damping of atmospheric inputs due to storage in a highly heterogeneous soil and groundwater system. Correspondingly, there is a highly dynamic response for components such as calcium, bicarbonate and aluminium. This response links to the relative inputs of acidic and aluminium-bearing soil waters under high flow conditions and base enriched bicarbonate bearing waters from the groundwater areas under baseflow conditions. The introduction of a deep borehole near the main stem of the river opened up a groundwater flow route to the stream and other parts of the catchment. There were two aspects to this. Firstly, it caused a change to the stream water quality, particularly under baseflow conditions, by increasing the concentrations of calcium and magnesium and by reducing the acidity. The monitoring shows that this change has persisted for over eight years and that there is no sign of reversion to pre-borehole times. Secondly, it caused a change in the groundwater level and chemistry at a borehole on the other side of the river. This feature shows that the fracture system is of hydrogeochemical and hydrogeological complexity. The effects of conifer harvesting are remarkable. At the local scale, felling leads to the expected short term increase in nitrate, ammonium and phosphate from the disturbance of the soil and the reduction in uptake into the vegetation. Correspondingly, there is a reduction in sodium and chloride linked to reduced scavenging of atmospheric inputs from cloud water by the vegetation and also due to increased dilution potential due to reductions in transpiration by the trees. However

  19. The health workforce crisis: the brain drain scourge.

    Science.gov (United States)

    Ike, Samuel O

    2007-01-01

    The magnitude of the health workforce crisis engendered by brain drain particularly in Africa, and nay more especially Nigeria, has been assuming increasingly alarming proportions in the past three decades. The challenge it poses in meeting the manpower needs in the healthcare sector as well as in the larger economy of the sending countries is enormous. This paper thus sets out to highlight the scope of this brain drain, its effects and the reasons sustaining it, as well as makes concrete suggestions to help stern the tide. A review of the literature on brain drain with particular emphasis on the health workforce sector was done, with focus on Africa, and specifically Nigeria. Literature search was done using mainly the Medline, as well as local journals. The historical perspectives, with the scope of external and internal brain drain are explored. The glaring effects of brain drain both in the global workforce terrain and specifically in the health sectors are portrayed. The countries affected most and the reasons for brain drain are outlined. Strategic steps to redress the brain drain crisis are proffered in this paper. The health workforce crisis resulting from brain drain must be brought to the front-burner of strategic policy decisions leading to paradigm shift in political, social and economic conditions that would serve as incentives to curb the scourge.

  20. Evapotranspiration from drained wetlands: drivers, modeling, storage functions, and restoration implications

    Science.gov (United States)

    Shukla, S.; Wu, C. L.; Shrestha, N.

    2017-12-01

    Abstract Evapotranspiration (ET) is a major component of wetland and watershed water budgets. The effect of wetland drainage on ET is not well understood. We tested whether the current understanding of insignificant effect of drainage on ET in the temperate region wetlands applies to those in the sub-tropics. Eddy covariance (EC) based ET measurements were made for two years at two previously drained and geographically close wetlands in the Everglades region of Florida. One wetland was significantly drained with 97% of its storage capacity lost. The other was a more functional wetland with 42% of storage capacity lost. Annual average ET at the significantly drained wetland was 836 mm, 34% less than the function wetland (1271 mm) and the difference was statistically significant (p = 0.001). Such differences in wetland ET in the same climatic region have not been observed. The difference in ET was mainly due to drainage driven differences in inundation and associated effects on net radiation (Rn) and local relative humidity. Two daily ET models, a regression (r2 = 0.80) and a Relevance Vector Machine (RVM) model (r2 = 0.84), were developed with the latter being more robust. These models, when used in conjunction with hydrologic models, improved ET predictions for drained wetlands. Predictions from an integrated model showed that more intensely drained wetlands at higher elevation should be targeted for restoration of downstream flows (flooding) because they have the ability to loose higher water volume through ET which increases available water storage capacity of wetlands. Daily ET models can predict changes in ET for improved evaluation of basin-scale effects of restoration programs and climate change scenarios.

  1. Water quality and ecological condition of urban streams in Independence, Missouri, June 2005 through December 2008

    Science.gov (United States)

    Christensen, D.; Harris, Thomas E.; Niesen, Shelley L.

    2010-01-01

    To identify the sources of selected constituents in urban streams and better understand processes affecting water quality and their effects on the ecological condition of urban streams and the Little Blue River in Independence, Missouri the U.S. Geological Survey in cooperation with the City of Independence Water Pollution Control Department initiated a study in June 2005 to characterize water quality and evaluate the ecological condition of streams within Independence. Base-flow and stormflow samples collected from five sites within Independence, from June 2005 to December 2008, were used to characterize the physical, chemical, and biologic effects of storm runoff on the water quality in Independence streams and the Little Blue River. The streams draining Independence-Rock Creek, Sugar Creek, Mill Creek, Fire Prairie Creek, and the Little Blue River-drain to the north and the Missouri River. Two small predominantly urban streams, Crackerneck Creek [12.9-square kilometer (km2) basin] and Spring Branch Creek (25.4-km2 basin), were monitored that enter into the Little Blue River between upstream and downstream monitoring sites. The Little Blue River above the upstream site is regulated by several reservoirs, but streamflow is largely uncontrolled. The Little Blue River Basin encompasses 585 km2 with about 168 km2 or 29 percent of the basin lying within the city limits of Independence. Water-quality samples also were collected for Rock Creek (24.1-km2 basin) that drains the western part of Independence. Data collection included streamflow, physical properties, dissolved oxygen, chloride, metals, nutrients, common organic micro-constituents, and fecal indicator bacteria. Benthic macroinvertebrate community surveys and habitat assessments were conducted to establish a baseline for evaluating the ecological condition and health of streams within Independence. Additional dry-weather screenings during base flow of all streams draining Independence were conducted to

  2. A new specifically designed forceps for chest drain insertion.

    LENUS (Irish Health Repository)

    Andrews, Emmet

    2012-02-03

    Insertion of a chest drain can be associated with serious complications. It is recommended that the drain is inserted with blunt dissection through the chest wall but there is no specific instrument to aid this task. We describe a new reusable forceps that has been designed specifically to facilitate the insertion of chest drains.A feasibility study of its use in patients who required a chest drain as part of elective cardiothoracic operations was undertaken. The primary end-point was successful and accurate placement of the drain. The operators also completed a questionnaire rating defined aspects of the procedure. The new instrument was used to insert the chest drain in 30 patients (19 male, 11 female; median age 61.5 years (range 16-81 years)). The drain was inserted successfully without the trocar in all cases and there were no complications. Use of the instrument rated as significantly easier relative to experience of previous techniques in all specified aspects. The new device can be used to insert intercostal chest drains safely and efficiently without using the trocar or any other instrument.

  3. Device for discharging drain in a control rod driving apparatus

    International Nuclear Information System (INIS)

    Ikeda, Tadasu; Ikuta, Takuzo; Yoshida, Tomiji; Tsukahara, Katsumi.

    1975-01-01

    Object: To efficiently and safely collect and discharge drain by a simple construction in which a drain cover and a drain tank in a control rod driving apparatus are integrally formed, and an overhauling wrench of said apparatus and a drain hose are mounted on the drain tank. Structure: When a mounting bolt is untightened by a torque wrench so as to be removed from a flange surface of the control rod driving apparatus in a nuclear reactor, axial movement of said apparatus is absorbed by a spring so that drain containing a radioactive material is discharged into a drain tank through the flange surface of said apparatus and is then guided into a collecting tank through a drain hose. (Kamimura, M.)

  4. Timing of Re-Transfusion Drain Removal Following Total Knee Replacement

    Science.gov (United States)

    Leeman, MF; Costa, ML; Costello, E; Edwards, D

    2006-01-01

    INTRODUCTION The use of postoperative drains following total knee replacement (TKR) has recently been modified by the use of re-transfusion drains. The aim of our study was to investigate the optimal time for removal of re-transfusion drains following TKR. PATIENTS AND METHODS The medical records of 66 patients who had a TKR performed between October 2003 and October 2004 were reviewed; blood drained before 6 h and the total volume of blood drained was recorded. RESULTS A total of 56 patients had complete records of postoperative drainage. The mean volume of blood collected in the drain in the first 6 h was 442 ml. The mean total volume of blood in the drain was 595 ml. Therefore, of the blood drained, 78% was available for transfusion. CONCLUSION Re-transfusion drains should be removed after 6 h, when no further re-transfusion is permissible. PMID:16551400

  5. Laparoscopic radical prostatectomy: omitting a pelvic drain

    Directory of Open Access Journals (Sweden)

    David Canes

    2008-03-01

    Full Text Available PURPOSE: Our goal was to assess outcomes of a selective drain placement strategy during laparoscopic radical prostatectomy (LRP with a running urethrovesical anastomosis (RUVA using cystographic imaging in all patients. Materials and Methods: A retrospective chart review was performed for all patients undergoing LRP between January 2003 and December 2004. The anastomosis was performed using a modified van Velthoven technique. A drain was placed at the discretion of the senior surgeon when a urinary leak was demonstrated with bladder irrigation, clinical suspicion for a urinary leak was high, or a complex bladder neck reconstruction was performed. Routine postoperative cystograms were obtained. RESULTS: 208 patients underwent LRP with a RUVA. Data including cystogram was available for 206 patients. The overall rate of cystographic urine leak was 5.8%. A drain was placed in 51 patients. Of these, 8 (15.6% had a postoperative leak on cystogram. Of the 157 undrained patients, urine leak was radiographically visible in 4 (2.5%. The higher leak rate in the drained vs. undrained cohort was statistically significant (p = 0.002. Twenty-four patients underwent pelvic lymph node dissection (8 drained, 16 undrained. Three undrained patients developed lymphoceles, which presented clinically on average 3 weeks postoperatively. There were no urinomas or hematomas in either group. CONCLUSIONS: Routine placement of a pelvic drain after LRP with a RUVA is not necessary, unless the anastomotic integrity is suboptimal intraoperatively. Experienced clinical judgment is essential and accurate in identifying patients at risk for postoperative leakage. When suspicion is low, omitting a drain does not increase morbidity.

  6. Importance of terrestrial arthropods as subsidies in lowland Neotropical rain forest stream ecosystems

    Science.gov (United States)

    Small, Gaston E.; Torres, Pedro J.; Schwizer, Lauren M.; Duff, John H.; Pringle, Catherine M.

    2013-01-01

    The importance of terrestrial arthropods has been documented in temperate stream ecosystems, but little is known about the magnitude of these inputs in tropical streams. Terrestrial arthropods falling from the canopy of tropical forests may be an important subsidy to tropical stream food webs and could also represent an important flux of nitrogen (N) and phosphorus (P) in nutrient-poor headwater streams. We quantified input rates of terrestrial insects in eight streams draining lowland tropical wet forest in Costa Rica. In two focal headwater streams, we also measured capture efficiency by the fish assemblage and quantified terrestrially derived N- and P-excretion relative to stream nutrient uptake rates. Average input rates of terrestrial insects ranged from 5 to 41 mg dry mass/m2/d, exceeding previous measurements of aquatic invertebrate secondary production in these study streams, and were relatively consistent year-round, in contrast to values reported in temperate streams. Terrestrial insects accounted for half of the diet of the dominant fish species, Priapicthys annectens. Although terrestrially derived fish excretion was found to be a small flux relative to measured nutrient uptake rates in the focal streams, the efficient capture and processing of terrestrial arthropods by fish made these nutrients available to the local stream ecosystem. This aquatic-terrestrial linkage is likely being decoupled by deforestation in many tropical regions, with largely unknown but potentially important ecological consequences.

  7. Flood-hazard analysis of four headwater streams draining the Argonne National Laboratory property, DuPage County, Illinois

    Science.gov (United States)

    Soong, David T.; Murphy, Elizabeth A.; Straub, Timothy D.; Zeeb, Hannah L.

    2016-11-22

    Results of a flood-hazard analysis conducted by the U.S. Geological Survey, in cooperation with the Argonne National Laboratory, for four headwater streams within the Argonne National Laboratory property indicate that the 1-percent and 0.2-percent annual exceedance probability floods would cause multiple roads to be overtopped. Results indicate that most of the effects on the infrastructure would be from flooding of Freund Brook. Flooding on the Northeast and Southeast Drainage Ways would be limited to overtopping of one road crossing for each of those streams. The Northwest Drainage Way would be the least affected with flooding expected to occur in open grass or forested areas.The Argonne Site Sustainability Plan outlined the development of hydrologic and hydraulic models and the creation of flood-plain maps of the existing site conditions as a first step in addressing resiliency to possible climate change impacts as required by Executive Order 13653 “Preparing the United States for the Impacts of Climate Change.” The Hydrological Simulation Program-FORTRAN is the hydrologic model used in the study, and the Hydrologic Engineering Center‒River Analysis System (HEC–RAS) is the hydraulic model. The model results were verified by comparing simulated water-surface elevations to observed water-surface elevations measured at a network of five crest-stage gages on the four study streams. The comparison between crest-stage gage and simulated elevations resulted in an average absolute difference of 0.06 feet and a maximum difference of 0.19 feet.In addition to the flood-hazard model development and mapping, a qualitative stream assessment was conducted to evaluate stream channel and substrate conditions in the study reaches. This information can be used to evaluate erosion potential.

  8. Transport of bedload sediment and channel morphology of a southeast Alaska stream.

    Science.gov (United States)

    Margaret A. Estep; Robert L. Beschta

    1985-01-01

    During 1980-81, transport of bedload sediment and channel morphology were determined at Trap Bay Creek, a third-order stream that drains a 13.5-square kilometer watershed on Chichagof island in southeast Alaska. Bedload sediment was sampled for 10 storms: peak flows ranged from 0.6 to 19.0 cubic meters per second, and transport rates ranged from 4 to 4400 kilograms per...

  9. 46 CFR 45.157 - Scuppers and gravity drains.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Scuppers and gravity drains. 45.157 Section 45.157 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Conditions of Assignment § 45.157 Scuppers and gravity drains. Scuppers and gravity deck drains from spaces...

  10. QUALIFIED VERSION OF MIGRATION: BRAIN DRAIN

    Directory of Open Access Journals (Sweden)

    Ayhan GENCLER

    2009-07-01

    Full Text Available Though globalization suggests an international exchange of people besides goods and capital, developed countries often tended to put forward some restrictions on the migration of workers from developed countries. However, there has been an increase in skilled international migration especially during the last two decades. Skilled international migration or brain drain points out the emigration of educated and highly skilled workers. It seems that, in general, developing or underdeveloped countries experience the negative consequences of the brain drain and suffer from the decreases in their human capital. The paper explains the phenomenon of skilled international migration, or brain drain, and summarizes the main global trends in this area.

  11. The management of vacuum neck drains in head and neck surgery and the comparison of two different practice protocols for drain removal.

    Science.gov (United States)

    Kasbekar, A V; Davies, F; Upile, N; Ho, M W; Roland, N J

    2016-01-01

    Introduction The management of vacuum neck drains in head and neck surgery is varied. We aimed to improve early drain removal and therefore patient discharge in a safe and effective manner. Methods The postoperative management of head and neck surgical patients with vacuum neck drains was reviewed retrospectively. A new policy was then implemented to measure drainage three times daily (midnight, 6am, midday). The decision for drain removal was based on the most recent drainage period (at Measuring drainage volumes three times daily allows for more accurate assessment of wound drainage, and this can lead to earlier removal of neck drains and safe discharge.

  12. Leaf litter processing in West Virginia mountain streams: effects of temperature and stream chemistry

    Science.gov (United States)

    Jacquelyn M. Rowe; William B. Perry; Sue A. Perry

    1996-01-01

    Climate change has the potential to alter detrital processing in headwater streams, which receive the majority of their nutrient input as terrestrial leaf litter. Early placement of experimental leaf packs in streams, one month prior to most abscission, was used as an experimental manipulation to increase stream temperature during leaf pack breakdown. We studied leaf...

  13. On the dynamics of stream piracy

    Science.gov (United States)

    Goren, L.; Willett, S. D.

    2012-04-01

    Drainage network reorganization by stream piracy is invoked repeatedly to explain the morphology of unique drainage patterns and as a possible mechanism inducing abrupt variations of sediment accumulation rates. However, direct evidence of stream piracy is usually rare, and is highly interpretation dependent. As a first step in assessing how probable capture events are and establishing the conditions that favor stream piracy versus the those that favor stable landscapes, we formulate analytically the physics of divide migration and capture events and study this formulation from a dynamical system point of view. The formulation is based on a one-dimensional topographic cross section between two channels that share a water divide. Two hillslope profiles diverge from the divide and drain into two fluvial bedrock tributaries, whose erosion rate is controlled by a stream power law. The rate of erosion at the bounding channels is thus a function of the upstream drainage area and local slope. A tectonically induced downward perturbation of the elevation of one of the bounding channels lowers the channel slope but at the same time increases the drainage area due to outward migration of the water divide. The changes in slope and area have opposing effect on the erosion rate at the bounding channels, so that the perturbation may either grow or be damped. We define the geomorphic and tectonic parameters that control the behavior of the system and find the regimes that lead to stable landscapes and to capture events.

  14. Effects of golf course construction and operation on water chemistry of headwater streams on the Precambrian Shield

    International Nuclear Information System (INIS)

    Winter, Jennifer G.; Dillon, Peter J.

    2005-01-01

    To investigate the effects of golf course construction and operation on the water chemistry of Shield streams, we compared the water chemistry in streams draining golf courses under construction (2) and in operation (5) to streams in forested reference locations and to upstream sites where available. Streams were more alkaline and higher in base cation and nitrate concentrations downstream of operational golf courses. Levels of these parameters and total phosphorus increased over time in several streams during golf course construction through to operation. There was evidence of inputs of mercury to streams on two of the operational courses. Nutrient (phosphorus and nitrogen) concentrations were significantly related to the area of unmanaged vegetation in a 30 x 30 m area on either side of the sampling sites, and to River Bank Quality Index scores, suggesting that maintaining vegetated buffers along the stream on golf courses will reduce in-stream nutrient concentrations. - Golf course construction and operation had a significant impact on alkalinity, nitrogen and base cation concentrations of streams

  15. Generation of airborne Listeria innocua from model floor drains.

    Science.gov (United States)

    Berrang, Mark E; Frank, Joseph F

    2012-07-01

    Listeria monocytogenes can colonize floor drains in poultry processing and further processing facilities, remaining present even after cleaning and disinfection. Therefore, during wash down, workers exercise caution to avoid spraying hoses directly into drains in an effort to prevent the escape and transfer of drain microflora to food contact surfaces. The objective of this study was to examine the extent to which an inadvertent water spray into a colonized floor drain can cause the spread of airborne Listeria. Listeria innocua was used to inoculate a polyvinyl chloride model floor drain, resulting in approximately 10(8) cells per ml of phosphate-buffered saline and 10(4) attached cells per square centimeter of inner surface. Each model drain was subjected to a 2-s spray of tap water at 68.9 kPa from a distance of 1 m. Drains were sprayed while filled and again after emptying. Airborne cells were collected by using sedimentation plates containing Listeria selective agar which were placed on the floor and walls of a contained room at incremental horizontal and vertical distances of 0.6, 1.2, 2.4, or 4.0 m from the drain. Sedimentation plates were exposed for 10 min. A mechanical sampler was used to also collect air by impaction on the surface of Listeria selective agar to determine the number of cells per liter of air. The experiment was conducted in triplicate rooms for each of four replications. L. innocua was detected on sedimentation plates on the floor as far as 4.0 m from the drain and on walls as high as 2.4 m above the floor and 4 m from the drain. A 2-s spray with a water hose into a contaminated drain can cause airborne spread of Listeria, resulting in the potential for cross-contamination of food contact surfaces, equipment, and exposed product.

  16. Lithological and fluvial controls on the geomorphology of tropical montane stream channels in Puerto Rico

    Science.gov (United States)

    Andrew S. Pike; F.N. Scatena; Ellen E. Wohl

    2010-01-01

    An extensive survey and topographic analysis of fi ve watersheds draining the Luquillo Mountains in north-eastern Puerto Rico was conducted to decouple the relative infl uences of lithologic and hydraulic forces in shaping the morphology of tropical montane stream channels. The Luquillo Mountains are a steep landscape composed of volcaniclastic and igneous rocks that...

  17. Fallopian Tube Herniation through Left Sided Abdominal Drain Site.

    Science.gov (United States)

    Hussain, Khalid; Masood, Jovaria

    2016-06-01

    Intra-abdominal drains have been used since long to prevent intra-abdominal collection, and detect any anastomotic leaks. We report a case of left sided fallopian tube herniation from a left lower abdominal drain site in a 27-year female who underwent caesarian section for breach presentation. Several complications related to drain usage has been described but left sided fallopian tube prolapse through drain site has not been reported in literature.

  18. Phylogenetic signal and major ecological shifts in the ecomorphological structure of stream fish in two river basins in Brazil

    Directory of Open Access Journals (Sweden)

    Camilo Andrés Roa-Fuentes

    Full Text Available We tested the contribution of the phylogenetic and specific components to the ecomorphological structure of stream fish from the upper Paraguai River and upper São Francisco River basins, and identified nodes in the phylogenetic tree at which major ecological shifts occurred. Fish were sampled between June and October of 2008 in 12 streams (six in each basin. In total, 22 species from the upper Paraguai River basin and 12 from the upper São Francisco River were analyzed. The ecomorphological patterns exhibited phylogenetic signal, indicating that the ecomorphological similarity among species is associated with the degree of relatedness. A strong habitat template is most likely to be the primary cause for a high phylogenetic signal. A significant contribution from the specific component was also detected, supporting the idea that the phylogenetic signal occurs in some clades for some traits, but not in others. The major ecological shifts were observed in the basal nodes, suggesting that ecological niche differences appear to accumulate early in the evolutionary history of major clades. This finding reinforces the role of key traits in the diversification of Neotropical fishes. Ecological shifts in recent groups could be related to morphological modifications associated with habitat use.

  19. Improved age constraints for the retreat of the Irish Sea Ice Stream

    Science.gov (United States)

    Smedley, Rachel; Chiverrell, Richard; Duller, Geoff; Scourse, James; Small, David; Fabel, Derek; Burke, Matthew; Clarke, Chris; McCarroll, Danny; McCarron, Stephen; O'Cofaigh, Colm; Roberts, David

    2016-04-01

    BRITICE-CHRONO is a large (> 45 researchers) consortium project working to provide an extensive geochronological dataset constraining the rate of retreat of a number of ice streams of the British-Irish Ice Sheet following the Last Glacial Maximum. When complete, the large empirical dataset produced by BRITICE-CHRONO will be integrated into model simulations to better understand the behaviour of the British-Irish Ice Sheet in response to past climate change, and provide an analogue for contemporary ice sheets. A major feature of the British-Irish Ice Sheet was the dynamic Irish Sea Ice Stream, which drained a large proportion of the ice sheet and extended to the proposed southern limit of glaciation upon the Isles of Scilly (Scourse, 1991). This study will focus on a large suite of terrestrial samples that were collected along a transect of the Irish Sea basin, covering the line of ice retreat from the Isles of Scilly (50°N) in the south, to the Isle of Man (54°N) in the north; a distance of 500 km. Ages are determined for both the eastern and western margins of the Irish Sea using single-grain luminescence dating (39 samples) and terrestrial cosmogenic nuclide dating (10 samples). A Bayesian sequence model is then used in combination with the prior information determined for deglaciation to integrate the geochronological datasets, and assess retreat rates for the Irish Sea Ice Stream. Scourse, J.D., 1991. Late Pleistocene stratigraphy and palaeobotany of the Isles of Scilly. Philosophical Transactions of the Royal Society of London B334, 405 - 448.

  20. Occurrence, distribution, and volume of metals-contaminated sediment of selected streams draining the Tri-State Mining District, Missouri, Oklahoma, and Kansas, 2011–12

    Science.gov (United States)

    Smith, D. Charlie

    2016-12-14

    Lead and zinc were mined in the Tri-State Mining District (TSMD) of southwest Missouri, northeast Oklahoma, and southeast Kansas for more than 100 years. The effects of mining on the landscape are still evident, nearly 50 years after the last mine ceased operation. The legacies of mining are the mine waste and discharge of groundwater from underground mines. The mine-waste piles and underground mines are continuous sources of trace metals (primarily lead, zinc, and cadmium) to the streams that drain the TSMD. Many previous studies characterized the horizontal extent of mine-waste contamination in streams but little information exists on the depth of mine-waste contamination in these streams. Characterizing the vertical extent of contamination is difficult because of the large amount of coarse-grained material, ranging from coarse gravel to boulders, within channel sediment. The U.S. Geological Survey, in cooperation with U.S. Fish and Wildlife service, collected channel-sediment samples at depth for subsequent analyses that would allow attainment of the following goals: (1) determination of the relation between concentration and depth for lead, zinc and cadmium in channel sediments and flood-plain sediments, and (2) determination of the volume of gravel-bar sediment from the surface to the maximum depth with concentrations of these metals that exceeded sediment-quality guidelines. For the purpose of this report, volume of gravel-bar sediment is considered to be distributed in two forms, gravel bars and the wetted channel, and this study focused on gravel bars. Concentrations of lead, zinc, and cadmium in samples were compared to the consensus probable effects concentration (CPEC) and Tri-State Mining District specific probable effects concentration (TPEC) sediment-quality guidelines.During the study, more than 700 sediment samples were collected from borings at multiple sites, including gravel bars and flood plains, along Center Creek, Turkey Creek, Shoal Creek

  1. Dissolved trace and minor elements in cryoconite holes and supraglacial streams, Canada Glacier, Antarctica

    Science.gov (United States)

    Fortner, Sarah K.; Lyons, W. Berry

    2018-04-01

    Here we present a synthesis of the trace element chemistry in melt on the surface Canada Glacier, Taylor Valley, McMurdo Dry Valleys (MDV), Antarctica ( 78°S). The MDV is largely ice-free. Low accumulation rates, strong winds, and proximity to the valley floor make these glaciers dusty in comparison to their inland counterparts. This study examines both supraglacial melt streams and cryoconite holes. Supraglacial streams on the lower Canada Glacier have median dissolved (<0.4 µm) concentrations of Fe, Mn, As, Cu, and V of 71.5, 75.5, 3.7, 4.6, and 4.3 nM. All dissolved Cd concentrations and the vast majority of Pb values are below our analytical detection (i.e. 0.4 and 0.06 nM). Chemical behavior did not follow similar trends for eastern and western draining waters. Heterogeneity likely reflects distinctions eolian deposition, rock:water ratios, and hydrologic connectivity. Future increases in wind-delivered sediment will likely drive dynamic responses in melt chemistry. For elements above detection limits, dissolved concentrations in glacier surface melt are within an order of magnitude of concentrations observed in proglacial streams (i.e. flowing on the valley floor). This suggests that glacier surfaces are an important source of downstream chemistry. The Fe enrichment of cryoconite water relative to N, P, or Si exceeds enrichment observed in marine phytoplankton. This suggests that the glacier surface is an important source of Fe to downstream ecosystems.

  2. Fallopian Tube Herniation: An Unusual Complication of Surgical Drain

    OpenAIRE

    Sharma, Lipi; Singh, Alpana; Bhaskaran, Sruthi; Radhika, A. G.; Radhakrishnan, Gita

    2012-01-01

    Background. Surgical drains have been used since time immemorial, but their use is not without complications. By presenting this case we aim to describe an uncommon complication of herniation of fallopian tube following the simple procedure of surgical drain removal. Case Presentation. This case describes a 23-year G2P1L1 who underwent an emergency cesarean section for obstructed labor with intraperitoneal drain insertion. The patient had an uneventful postoperative period, drain was removed ...

  3. Principles for urban stormwater management to protect stream ecosystems

    Science.gov (United States)

    Walsh, Christopher J.; Booth, Derek B.; Burns, Matthew J.; Fletcher, Tim D.; Hale, Rebecca L.; Hoang, Lan N.; Livingston, Grant; Rippy, Megan A.; Roy, Allison; Scoggins, Mateo; Wallace, Angela

    2016-01-01

    Urban stormwater runoff is a critical source of degradation to stream ecosystems globally. Despite broad appreciation by stream ecologists of negative effects of stormwater runoff, stormwater management objectives still typically center on flood and pollution mitigation without an explicit focus on altered hydrology. Resulting management approaches are unlikely to protect the ecological structure and function of streams adequately. We present critical elements of stormwater management necessary for protecting stream ecosystems through 5 principles intended to be broadly applicable to all urban landscapes that drain to a receiving stream: 1) the ecosystems to be protected and a target ecological state should be explicitly identified; 2) the postdevelopment balance of evapotranspiration, stream flow, and infiltration should mimic the predevelopment balance, which typically requires keeping significant runoff volume from reaching the stream; 3) stormwater control measures (SCMs) should deliver flow regimes that mimic the predevelopment regime in quality and quantity; 4) SCMs should have capacity to store rain events for all storms that would not have produced widespread surface runoff in a predevelopment state, thereby avoiding increased frequency of disturbance to biota; and 5) SCMs should be applied to all impervious surfaces in the catchment of the target stream. These principles present a range of technical and social challenges. Existing infrastructural, institutional, or governance contexts often prevent application of the principles to the degree necessary to achieve effective protection or restoration, but significant potential exists for multiple co-benefits from SCM technologies (e.g., water supply and climate-change adaptation) that may remove barriers to implementation. Our set of ideal principles for stream protection is intended as a guide for innovators who seek to develop new approaches to stormwater management rather than accept seemingly

  4. Thailand and brain drain

    Directory of Open Access Journals (Sweden)

    Terry Commins

    2009-01-01

    Full Text Available Brain drain has been the subject of research since the 1960s. This research has been hampered by a lack of accurate data from both source and receiving countries on migration and on the losses and gains to developing economies of skilled migration. However, despite these handicaps, research has been able to clearly show that trends are changing and the effect this is having is usually quite different for individual source countries.Thailand, as a developing economy, could be regarded as a source country. Fortunately, Thailand has never ranked highly in terms of brain drain when compared to other states in Asia and while it may not be a significant problem it nonetheless needs to be monitored. Thailand is also somewhat unique in that the migration that has occurred has been almost equally split between secondary and tertiary educated Thais. Thailand also ranks low in terms of tertiary educated population who have migrated when compared to other countries in the region. Globalisation is having a profound effect on the migration of skilled workers. As trade becomes increasingly free, barriers to the movement of services or people are also freed. As the better educated are encouraged to think globally, so too will they be inclined to move globally into the world community.This paper examines Thailand’s position with respect to brain drain, some of the lessons we have learned and some of the steps that are being taken to minimise the impact of the loss of skilled workers, with a particular focus on science and technology. The conclusion is that brain drain should not be viewed as an entirely negative development and that the positive outcomes should be recognised, encouraged and incorporated into policy.

  5. Stream-Groundwater Interaction Buffers Seasonal Changes in Urban Stream Water Quality

    Science.gov (United States)

    Ledford, S. H.; Lautz, L. K.

    2013-12-01

    Urban streams in the northeastern United States have large road salt inputs during winter, increased nonpoint sources of inorganic nitrogen, and decreased short-term and permanent storage of nutrients. Meadowbrook Creek, a first order stream in Syracuse, New York, flows along a negative urbanization gradient, from a channelized and armored stream running through the middle of a roadway to a pool-riffle stream meandering through a broad, vegetated floodplain with a riparian aquifer. In this study we investigated how reconnection to groundwater and introduction of riparian vegetation impacted surface water chemistry by making bi-weekly longitudinal surveys of stream water chemistry in the creek from May 2012 until June 2013. Chloride concentrations in the upstream, urban reach of Meadowbrook Creek were strongly influenced by discharge of road salt to the creek during snow melt events in winter and by the chemistry of water draining an upstream retention basin in summer. Chloride concentrations ranged from 161.2 mg/L in August to 2172 mg/L in February. Chloride concentrations in the downstream, 'connected' reach had less temporal variation, ranging from 252.0 mg/L in August to 1049 mg/L in January, and were buffered by groundwater discharge, as the groundwater chloride concentrations during the sampling period ranged from 84.0 to 655.4 mg/L. Groundwater discharge resulted in higher chloride concentrations in summer and lower concentrations in winter in the connected reach relative to the urban reach, minimizing annual variation. In summer, there was little-to-no nitrate in the urban reach due to a combination of limited sources and high primary productivity. In contrast, during the summer, nitrate concentrations reached over 1 mg N/L in the connected reach due to the presence of riparian vegetation and lower nitrate uptake due to cooler temperatures and shading. During the winter, when temperatures fell below freezing, nitrate concentrations in the urban reach

  6. Spatial distribution of mercury in southeastern Alaskan streams influenced by glaciers, wetlands, and salmon

    International Nuclear Information System (INIS)

    Nagorski, Sonia A.; Engstrom, Daniel R.; Hudson, John P.; Krabbenhoft, David P.; Hood, Eran; DeWild, John F.; Aiken, George R.

    2014-01-01

    Southeastern Alaska is a remote coastal-maritime ecosystem that is experiencing increased deposition of mercury (Hg) as well as rapid glacier loss. Here we present the results of the first reported survey of total and methyl Hg (MeHg) concentrations in regional streams and biota. Overall, streams draining large wetland areas had higher Hg concentrations in water, mayflies, and juvenile salmon than those from glacially-influenced or recently deglaciated watersheds. Filtered MeHg was positively correlated with wetland abundance. Aqueous Hg occurred predominantly in the particulate fraction of glacier streams but in the filtered fraction of wetland-rich streams. Colonization by anadromous salmon in both glacier and wetland-rich streams may be contributing additional marine-derived Hg. The spatial distribution of Hg in the range of streams presented here shows that watersheds are variably, yet fairly predictably, sensitive to atmospheric and marine inputs of Hg. -- Highlights: • We sampled 21 streams in southeastern Alaska for water, sediments, and biota. • Aqueous Hg showed significant relationships with wetlands and DOC. • Biota had higher mercury in wetland-rich streams than in glacier-fed streams. • Spawning salmon appear to contribute methylmercury to stream foodwebs. -- This original survey of mercury concentration and form in southeastern Alaskan streamwater and biota shows substantial spatial variation linked to landscape factors and salmon influence

  7. Soluble reactive phosphorus (SRP) transport and retention in tropical, rain forest streams draining a volcanic landscape in Costa Rica: In situ SRP amendment to streams and laboratory studies

    Science.gov (United States)

    Triska, F.; Pringle, C.M.; Duff, J.H.; Avanzino, R.J.; Zellweger, G.

    2006-01-01

    Soluble reactive phosphorus (SRP) transport/retention was determined in two rain forest streams (Salto, Pantano) draining La Selva Biological Station, Costa Rica. There, SRP levels can be naturally high due to groundwater enriched by geothermal activity within the surfically dormant volcanic landscape, and subsequently discharged at ambient temperature. Combined field and laboratory approaches simulated high but natural geothermal SRP input with the objective of estimating the magnitude of amended SRP retention within high and low SRP settings and determining the underlying mechanisms of SRP retention. First, we examined short-term SRP retention/transport using combined SRP-conservative tracer additions at high natural in situ concentrations. Second, we attempted to observe a DIN response during SRP amendment as an indicator of biological uptake. Third, we determined SRP release/retention using laboratory sediment assays under control and biologically inhibited conditions. Short-term in situ tracer-SRP additions indicated retention in both naturally high and low SRP reaches. Retention of added SRP mass in Upper Salto (low SRP) was 17% (7.5 mg-P m-2 h-1), and 20% (10.9 mg-P m-2 h -1) in Lower Salto (high SRP). No DIN response in either nitrate or ammonium was observed. Laboratory assays using fresh Lower Salto sediments indicated SRP release (15.4 ?? 5.9 ??g-P g dry wt.-1 h -1), when incubated in filter sterilized Salto water at ambient P concentration, but retention when incubated in filter sterilized river water amended to 2.0 mg SRP l-1 (233.2 ?? 5.8 ??g-P g dry wt. -1 h-1). SRP uptake/release was similar in both control- and biocide-treated sediments indicating predominantly abiotic retention. High SRP retention even under biologically saturated conditions, absence of a DIN response to amendment, patterns of desorption following amendment, and similar patterns of retention and release under control and biologically inhibited conditions all indicated

  8. Drain Insertion in Chronic Subdural Hematoma: An International Survey of Practice.

    Science.gov (United States)

    Soleman, Jehuda; Kamenova, Maria; Lutz, Katharina; Guzman, Raphael; Fandino, Javier; Mariani, Luigi

    2017-08-01

    To investigate whether, after the publication of grade I evidence that it reduces recurrence rates, the practice of drain insertion after burr-hole drainage of chronic subdural hematoma has changed. Further, we aimed to document various practice modalities concerning the insertion of a drain adopted by neurosurgeons internationally. We administered a survey to neurosurgeons worldwide with questions relating to the surgical treatment of chronic subdural hematoma, with an emphasis on their practices concerning the use of a drain. The preferred surgical technique was burr-hole drainage (89%). Most surgeons prefer to place a drain (80%), whereas in 56% of the cases the reason for not placing a drain was brain expansion after evacuation. Subdural drains are placed by 50% and subperiosteal drains by 27% of the responders, whereas 23% place primarily a subdural drain if possible and otherwise a subperiosteal drain. Three quarters of the responders leave the drain for 48 hours and give prophylactic antibiotic treatment, mostly a single-shot dose intraoperatively (70%). Routine postoperative computed tomography is done by 59% mostly within 24-48 hours after surgery (94%). Adjunct treatment to surgery rarely is used (4%). The publication of grade I evidence in favor of drain use influenced positively this practice worldwide. Some surgeons are still reluctant to insert a drain, especially when the subdural space is narrow after drainage of the hematoma. The insertion of a subperiosteal drain could be a good alternative solution. However, its outcome and efficacy must be evaluated in larger studies. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. A study of the complications of small bore 'Seldinger' intercostal chest drains.

    Science.gov (United States)

    Davies, Helen E; Merchant, Shairoz; McGown, Anne

    2008-06-01

    Use of small bore chest drains (drainage over a 12-month period. One hundred consecutive small bore Seldinger (12F) chest drain insertions were evaluated. Few serious complications occurred. However, 21% of the chest drains were displaced ('fell out') and 9% of the drains became blocked. This contributed to high morbidity rates, with 13% of patients requiring repeat pleural procedures. The frequency of drain blockage in pleural effusion was reduced by administration of regular normal saline drain flushes (odds ratio for blockage in flushed drains compared with non-flushed drains 0.04, 95% CI: 0.01-0.37, P < 0.001). Regular chest drain flushes are advocated in order to reduce rates of drain blockage, and further studies are needed to determine optimal fixation strategies that may reduce associated patient morbidity.

  10. Multiyear nutrient removal performance of three constructed wetlands intercepting tile drain flows from grazed pastures.

    Science.gov (United States)

    Tanner, Chris C; Sukias, James P S

    2011-01-01

    Subsurface tile drain flows can be a major s ource of nurient loss from agricultural landscapes. This study quantifies flows and nitrogen and phosphorus yields from tile drains at three intensively grazed dairy pasture sites over 3- to 5-yr periods and evaluates the capacity of constructed wetlands occupying 0.66 to 1.6% of the drained catchments too reduce nutrient loads. Continuous flow records are combined with automated flow-proportional sampling of nutrient concentrations to calculate tile drain nutrient yields and wetland mass removal rates. Annual drainage water yields rangedfrom 193 to 564 mm (16-51% of rainfall) at two rain-fed sites and from 827 to 853 mm (43-51% of rainfall + irrigation) at an irrigated site. Annually, the tile drains exported 14 to 109 kg ha(-1) of total N (TN), of which 58 to 90% was nitrate-N. Constructed wetlands intercepting these flows removed 30 to 369 gTN m(-2) (7-63%) of influent loadings annually. Seasonal percentage nitrate-N and TN removal were negatively associated with wetland N mass loadings. Wetland P removal was poor in all wetlands, with 12 to 115% more total P exported annually overall than received. Annually, the tile drains exported 0.12 to 1.38 kg ha of total P, of which 15 to 93% was dissolved reactive P. Additional measures are required to reduce these losses or provide supplementary P removal. Wetland N removal performance could be improved by modifying drainage systems to release flows more gradually and improving irrigation practices to reduce drainage losses.

  11. Decoupling of stream and vegetation solutes during the late stages of weathering: insights from elemental and Mg isotope trends at the Luquillo Critical Zone Observatory, Puerto Rico

    Science.gov (United States)

    Chapela Lara, M.; Schuessler, J. A.; Buss, H. L.; McDowell, W. H.

    2017-12-01

    During the evolution of the critical zone, the predominant source of nutrients to the vegetation changes from bedrock weathering to atmospheric inputs and biological recycling. In parallel, the architecture of the critical zone changes with time, promoting a change in water flow regime from near-surface porous flow during early weathering stages to more complex flow regimes modulated by clay-rich regolith during the late stages of weathering. As a consequence of these two concurrent processes, we can expect the predominant sources and pathways of solutes to the streams to also change during critical zone evolution. If this is true, we would observe a decoupling between the solutes used by the vegetation and those that determine the composition of the streams during the late stages of weathering, represented by geomorphically stable tropical settings. To test these hypotheses, we are analyzing the elemental and Mg isotopic composition of regolith and streams at the humid tropical Luquillo Critical Zone Observatory. We aim to trace the relative contributions of the surficial, biologically mediated pathways and the deeper, weathering controlled nutrient pathways. We also investigate the role of lithology on the solute decoupling between the vegetation and the stream, by examining two similar headwater catchments draining two different bedrocks (andesitic volcaniclastic and granitic). Our preliminary elemental and Mg isotope results are consistent with atmospheric inputs in the upper 2 m of regolith in both lithologies and with bedrock weathering at depth. During a short storm event ( 6 h), a headwater stream draining volcaniclastic bedrock showed a large variation in Mg and δ26Mg, correlated with total suspended solids, while another similar headwater granitic stream showed a much narrower variation. A larger stream draining volcaniclastic bedrock showed changes in Mg concentration in response to rain during the same storm event, but did not change in δ26Mg

  12. Drain Back, Low Flow Solar Combi Systems

    DEFF Research Database (Denmark)

    Perers, Bengt; Furbo, Simon; Fan, Jianhua

    2014-01-01

    Drain Back systems with ETC collectors are tested and analyzed in a Danish - Chinese cooperation project. Experiences from early work at DTU, with drain back, low flow systems, was used to design two systems: 1) One laboratory system at DTU and 2) One demonstration system in a single family house...... in Sorö Denmark. Detailed monitoring and modelling of the system in the DTU lab is done to be able to generalize the results, to other climates and loads and to make design optimizations. The advantage with drain back, low flow systems, is that the system can be made more simple with less components...... and that the performance can be enhanced. A combination of the drain back- and system expansion vessel was tested successfully. Small initial problems with installation and proposals for design improvements to avoid these in practice are described in the paper. Installer education and training is an important step to have...

  13. Thinking beyond the Bioreactor Box: Incorporating Stream Ecology into Edge-of-Field Nitrate Management.

    Science.gov (United States)

    Goeller, Brandon C; Febria, Catherine M; Harding, Jon S; McIntosh, Angus R

    2016-05-01

    Around the world, artificially drained agricultural lands are significant sources of reactive nitrogen to stream ecosystems, creating substantial stream health problems. One management strategy is the deployment of denitrification enhancement tools. Here, we evaluate the factors affecting the potential of denitrifying bioreactors to improve stream health and ecosystem services. The performance of bioreactors and the structure and functioning of stream biotic communities are linked by environmental parameters like dissolved oxygen and nitrate-nitrogen concentrations, dissolved organic carbon availability, flow and temperature regimes, and fine sediment accumulations. However, evidence of bioreactors' ability to improve waterway health and ecosystem services is lacking. To improve the potential of bioreactors to enhance desirable stream ecosystem functioning, future assessments of field-scale bioreactors should evaluate the influences of bioreactor performance on ecological indicators such as primary production, organic matter processing, stream metabolism, and invertebrate and fish assemblage structure and function. These stream health impact assessments should be conducted at ecologically relevant spatial and temporal scales. Bioreactors have great potential to make significant contributions to improving water quality, stream health, and ecosystem services if they are tailored to site-specific conditions and implemented strategically with land-based and stream-based mitigation tools within watersheds. This will involve combining economic, logistical, and ecological information in their implementation. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  14. Circuital model for the spherical geodesic waveguide perfect drain

    Science.gov (United States)

    González, Juan C.; Grabovičkić, Dejan; Benítez, Pablo; Miñano, Juan C.

    2012-08-01

    The perfect drain for the Maxwell fish eye (MFE) is a non-magnetic dissipative region placed in the focal point to absorb all the incident radiation without reflection or scattering. The perfect drain was recently designed as a material with complex permittivity that depends on frequency. However, this material is only a theoretical material, so it cannot be used in practical devices. The perfect drain has been claimed as necessary for achieving super-resolution (Leonhardt 2009 New J. Phys. 11 093040), which has increased the interest in practical perfect drains suitable for manufacturing. Here, we present a practical perfect drain that is designed using a simple circuit (made of a resistance and a capacitor) connected to the coaxial line. Moreover, we analyze the super-resolution properties of a device equivalent to the MFE, known as a spherical geodesic waveguide, loaded with this perfect drain. The super-resolution analysis for this device is carried out using COMSOL Multiphysics. The results of simulations predict a super-resolution of up to λ/3000.

  15. Circuital model for the spherical geodesic waveguide perfect drain

    International Nuclear Information System (INIS)

    González, Juan C; Grabovičkić, Dejan; Benítez, Pablo; Miñano, Juan C

    2012-01-01

    The perfect drain for the Maxwell fish eye (MFE) is a non-magnetic dissipative region placed in the focal point to absorb all the incident radiation without reflection or scattering. The perfect drain was recently designed as a material with complex permittivity that depends on frequency. However, this material is only a theoretical material, so it cannot be used in practical devices. The perfect drain has been claimed as necessary for achieving super-resolution (Leonhardt 2009 New J. Phys. 11 093040), which has increased the interest in practical perfect drains suitable for manufacturing. Here, we present a practical perfect drain that is designed using a simple circuit (made of a resistance and a capacitor) connected to the coaxial line. Moreover, we analyze the super-resolution properties of a device equivalent to the MFE, known as a spherical geodesic waveguide, loaded with this perfect drain. The super-resolution analysis for this device is carried out using COMSOL Multiphysics. The results of simulations predict a super-resolution of up to λ/3000. (paper)

  16. DETERMINATION OF LIQUID FILM THICKNESS FOLLOWING DRAINING OF CONTACTORS, VESSELS, AND PIPES IN THE MCU PROCESS

    International Nuclear Information System (INIS)

    Poirier, M; Fernando Fondeur, F; Samuel Fink, S

    2006-01-01

    The Department of Energy (DOE) identified the caustic side solvent extraction (CSSX) process as the preferred technology to remove cesium from radioactive waste solutions at the Savannah River Site (SRS). As a result, Washington Savannah River Company (WSRC) began designing and building a Modular CSSX Unit (MCU) in the SRS tank farm to process liquid waste for an interim period until the Salt Waste Processing Facility (SWPF) begins operations. Both the solvent and the strip effluent streams could contain high concentrations of cesium which must be removed from the contactors, process tanks, and piping prior to performing contactor maintenance. When these vessels are drained, thin films or drops will remain on the equipment walls. Following draining, the vessels will be flushed with water and drained to remove the flush water. The draining reduces the cesium concentration in the vessels by reducing the volume of cesium-containing material. The flushing, and subsequent draining, reduces the cesium in the vessels by diluting the cesium that remains in the film or drops on the vessel walls. MCU personnel requested that Savannah River National Laboratory (SRNL) researchers conduct a literature search to identify models to calculate the thickness of the liquid films remaining in the contactors, process tanks, and piping following draining of salt solution, solvent, and strip solution. The conclusions from this work are: (1) The predicted film thickness of the strip effluent is 0.010 mm on vertical walls, 0.57 mm on horizontal walls and 0.081 mm in horizontal pipes. (2) The predicted film thickness of the salt solution is 0.015 mm on vertical walls, 0.74 mm on horizontal walls, and 0.106 mm in horizontal pipes. (3) The predicted film thickness of the solvent is 0.022 mm on vertical walls, 0.91 mm on horizontal walls, and 0.13 mm in horizontal pipes. (4) The calculated film volume following draining is: (a) Salt solution receipt tank--1.6 gallons; (b) Salt solution feed

  17. Method of processing laundry drain

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, Y; Oda, A; Yusa, H; Kitamura, M; Horiuchi, S

    1979-09-28

    Purpose: To subject the laundry drain to flocculation precipitation treatment in the prior stage of an inverse osmotic treatment, and subject only the supernatant to the inverse osmotic treatment and the precipitate directly to the condensation treatment, thereby decreasing the frequency of exchange of the inverse osmotic membranes, and reducing the quantity of purifying water. Method: The laundry drain is supplied to a flocculation precipitation tank, and added and mixed with a flocculant and a neutralizing agent, thus being subjected to a flocculation precipitation treatment. The supernatant is transported to a circulation tank through a transportation pipe, and is subjected to an inverse osmotic treatment in inverse osmotic module through the circulation tank, a filter and a high tension pump, and then returned to the circulation tank. The supernatant is thus concentrated to a predetermined concentration by repeating such operations. On the other hand, the precipitate at the bottom part of the flocculation precipitation tank is supplied through the transportation pipe to an evaporator supply tank together with the concentrate from the drain circulation tank, and evaporated and concentrated in the evaporator.

  18. Evisceration of Appendix through the Drain Site: A Rare Case Report.

    Science.gov (United States)

    Ravishankaran, Praveen; Rajamani, A

    2013-06-01

    Placing a drain after surgery is a usual procedure in any emergency abdominal operation. The drain is removed as soon as its purpose of draining the intraabdominal collection in served. Evisceration of intraabdominal organs through the drain site is a rare occurance. This case report is about an 12 year old girl who was admitted with blunt trauma abdomen. After completion of emergency laparotomy a drain was placed in the right lower quadrant. When the drain was removed on the 6th post operative day, the appendix eviscerated out of the drain site. The wound was extended a little and an appendectomy was done. This case is presented for its rarity as only two similar instances have been reported in literature so far.

  19. Major and trace elements in sediments of the upper course of Lerma river

    International Nuclear Information System (INIS)

    Tejeda, S.; Zarazua-Ortega, G.; Avila-Perez, P.; Garcia-Mejia, A.; Carapia-Morales, L.; Diaz-Delgado

    2006-01-01

    The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The concentration of six major and trace elements: titanium, manganese, iron, zinc, copper and lead in the surface sediments of the upper course of Lerma river was investigated, in order to identify its distribution along the river and to recognize the principal sites of pollution. The surface sediment samples were collected at 8 sites distributed following the stream flow direction of the river. Major and trace elements concentrations were determined by energy dispersive X-ray spectrometry. The results show that the metal concentrations in the sediments decrease in the sequence: Fe > Ti > Mn > Zn > Cu > Pb. Concentration of Fe, Mn and Ti were significantly higher than the other metals in site 8,200 meters downstream the Alzate Dam. The high concentrations and spatial variations of Zn, Cu and Pb in the middle sites of the upper course of the Lerma River indicate that the river pollution is probably associated with urban and industrial discharges. (author)

  20. Regional Relations in Bankfull Channel Characteristics determined from flow measurements at selected stream-gaging stations in West Virginia, 1911-2002

    Science.gov (United States)

    Messinger, Terence; Wiley, Jeffrey B.

    2004-01-01

    Three bankfull channel characteristics?cross-sectional area, width, and depth?were significantly correlated with drainage area in regression equations developed for two regions in West Virginia. Channel characteristics were determined from analysis of flow measurements made at 74 U.S. Geological Survey stream-gaging stations at flows between 0.5 and 5.0 times bankfull flow between 1911 and 2002. Graphical and regression analysis were used to delineate an 'Eastern Region' and a 'Western Region,' which were separated by the boundary between the Appalachian Plateaus and Valley and Ridge Physiographic Provinces. Streams that drained parts of both provinces had channel characteristics typical of the Eastern Region, and were grouped with it. Standard error for the six regression equations, three for each region, ranged between 8.7 and 16 percent. Cross-sectional area and depth were greater relative to drainage area for the Western Region than they were for the Eastern Region. Regression equations were defined for streams draining between 46.5 and 1,619 square miles for the Eastern Region, and between 2.78 and 1,354 square miles for the Western Region. Stream-gaging stations with two or more cross sections where flow had been measured at flows between 0.5 and 5.0 times the 1.5-year flow showed poor replication of channel characteristics compared to the 95-percent confidence intervals of the regression, suggesting that within-reach variability for the stream-gaging stations may be substantial. A disproportionate number of the selected stream-gaging stations were on large (drainage area greater than 100 square miles) streams in the central highlands of West Virginia, and only one stream-gaging station that met data-quality criteria was available to represent the region within about 50 miles of the Ohio River north of Parkersburg, West Virginia. Many of the cross sections were at bridges, which can change channel shape. Although the data discussed in this report may not be

  1. Mechanical decontamination techniques for floor drain systems

    International Nuclear Information System (INIS)

    Palau, G.L.

    1987-01-01

    The unprecedented nature of cleanup activities at Three Mile Island Unit 2 (TMI-2) following the 1979 accident has necessitated the development of new techniques to deal with radiation and contamination in the plant. One of these problems was decontamination of floor drain systems, which had become highly contaminated with various forms of dirt and sludge containing high levels of fission products and fuel from the damaged reactor core. The bulk of this contamination is loosely adherent to the drain pipe walls; however, significant amounts of contamination have become incorporated into pipe wall oxide and corrosion layers and embedded in microscopic pits and fissures in the pipe wall material. The need to remove this contamination was recognized early in the TMI-2 cleanup effort. A program consisting of development and laboratory testing of floor drain decontamination techniques was undertaken early in the cleanup with support from the Electric Power Research Institute (EPRI). Based on this initial research, two techniques were judged to show promise for use at TMI-2: a rotating brush hone system and a high-pressure water mole nozzle system. Actual use of these devices to clean floor drains at TMI-2 has yielded mixed decontamination results. The decontamination effectiveness that has been obtained is highly dependent on the nature of the contamination in the drain pipe and the combination of decontamination techniques used

  2. Contaminant Dynamics and Trends in Hyperalkaline Urban Streams

    Science.gov (United States)

    Riley, Alex; Mayes, William

    2015-04-01

    Streams in post-industrial urban areas can have multiple contemporary and historic pressures impacting upon their chemical and ecological status. This paper presents analysis of long term data series (up to 36 years in length) from two small streams in northern England (catchment areas 0.5-0.6km2). Around 3.5 million m3 of steel making slags and other wastes were deposited in the headwater areas of the Howden Burn and Dene Burn in northeast England up to the closure of the workings in the early 1980s. This has led to streams draining from the former workings which have a hyperalkaline ambient pH (mean of 10.3 in both streams), elevated alkalinity (up to 487 mg/L as CaCO3) from leaching of lime and other calcium oxides / silicates within the slag, and enrichment of some trace elements (e.g. aluminium (Al), lithium (Li) and zinc (Zn)) including those which form oxyanions mobile at high pH such as vanadium (V). The high ionic strength of the waters and calcium enrichment also leads to waters highly supersaturated with calcium carbonate. Trace contaminant concentrations are strongly positively correlated, and concentrations generally diminish with increased flow rate suggesting the key source of metals in the system is the highly alkaline groundwater draining from the slag mounds. Some contaminants (notably Cr and ammonium) increase with high flow suggesting sources related to urban runoff and drainage from combined sewer overflows into one of the catchments. Loading estimates instream show that many of the contaminants (e.g. Al, V and Zn) are rapidly attenuated in secondary calcium carbonate-dominated deposits that precipitate vigorously on the streambeds with rates of up to 250 g CaCO3/m2/day. These secondary sinks limit the mobility of many contaminants in the water column, while concentrations in secondary deposits are relatively low given the rapid rates at which Ca is also attenuated. Long-term trend analysis showed modest declines in calcium and alkalinity over

  3. Brain drain of China and India

    OpenAIRE

    Li, Yuan

    2012-01-01

    Abstract Under the background of globalization, brain drain is a common phenomenon in many countries. Talents flow from developing countries to developed countries, and this phenomenon unavoidably exerts various and profound influences to both the source countries and the receiving countries. This thesis deals with the phenomenon of brain drain with the aim to investigate the phenomenon further and carry out two case studies of China and India. The research method is main...

  4. STREAM2016: Streaming Requirements, Experience, Applications and Middleware Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Fox, Geoffrey [Indiana Univ., Bloomington, IN (United States); Jha, Shantenu [Rutgers Univ., New Brunswick, NJ (United States); Ramakrishnan, Lavanya [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-10-01

    The Department of Energy (DOE) Office of Science (SC) facilities including accelerators, light sources and neutron sources and sensors that study, the environment, and the atmosphere, are producing streaming data that needs to be analyzed for next-generation scientific discoveries. There has been an explosion of new research and technologies for stream analytics arising from the academic and private sectors. However, there has been no corresponding effort in either documenting the critical research opportunities or building a community that can create and foster productive collaborations. The two-part workshop series, STREAM: Streaming Requirements, Experience, Applications and Middleware Workshop (STREAM2015 and STREAM2016), were conducted to bring the community together and identify gaps and future efforts needed by both NSF and DOE. This report describes the discussions, outcomes and conclusions from STREAM2016: Streaming Requirements, Experience, Applications and Middleware Workshop, the second of these workshops held on March 22-23, 2016 in Tysons, VA. STREAM2016 focused on the Department of Energy (DOE) applications, computational and experimental facilities, as well software systems. Thus, the role of “streaming and steering” as a critical mode of connecting the experimental and computing facilities was pervasive through the workshop. Given the overlap in interests and challenges with industry, the workshop had significant presence from several innovative companies and major contributors. The requirements that drive the proposed research directions, identified in this report, show an important opportunity for building competitive research and development program around streaming data. These findings and recommendations are consistent with vision outlined in NRC Frontiers of Data and National Strategic Computing Initiative (NCSI) [1, 2]. The discussions from the workshop are captured as topic areas covered in this report's sections. The report

  5. Ferrihydrite flocs, native copper nanocrystals and spontaneous remediation in the Fosso dei Noni stream, Tuscany, Italy

    International Nuclear Information System (INIS)

    Genovese, Alessandro; Mellini, Marcello

    2007-01-01

    The Fosso dei Noni stream drains the abandoned mixed-sulfide mining area of Fenice Capanne in Italy. Water pollution mostly derives from two tributaries, one of which adds Cu and the other Zn. Downstream, water pollution is progressively remediated through the spontaneous precipitation of abundant, deeply-colored flocs. Within 1 km, flocs change from yellow-red to whitish and green, as the pH increases from 4.59 to 7.70 and the Eh decreases from +311 to +165 mV. Flocs are initially amorphous; with a near-neutral pH, their X-ray diffraction properties suggest the presence of two-line ferrihydrite. Transmission electron microscopy reveals major nanotextural modifications in flocs along the entire stream. Upstream, flocs consist of globular particles with a radius of 25-50 nm. Downstream, they change to globular particles with elongated features. Lastly, further downstream, flocs consist of elongated features interconnected by continuous films. Nanochemical data are consistent with Al and Fe hydroxides (largely contaminated by S, Si, Ca, Cu and Zn); the Cu content increases progressively downstream to a maximum of 18 at. %. The increasing Cu content is paralleled by the appearance of isolated Cu nanocrystals adsorbed on floc surfaces. Spontaneous processes in the Fosso dei Noni stream (water neutralization, formation of ferrihydrite-like flocs and crystallization of native Cu) allow the temporary storage of Cu, providing hints on how to optimize remediation processes and Cu recovery

  6. Reproductive effects assessment of fish in streams on the Oak Ridge Reservation

    International Nuclear Information System (INIS)

    McCracken, M.K.; Ivey, L.J.; Niemela, S.L.; Greeley, M.S. Jr.

    1995-01-01

    The Department of Energy has three large facilities located on the Oak Ridge Reservation Site, the Y-12 Plant, and the Oak Ridge National Laboratory. Several Biological Monitoring and Abatement Programs (BMAP) monitor and assess the effects of these facilities on the aquatic and terrestrial resources of the reservation. One BMAP task concerns the potential role of contaminant-related reproductive dysfunction in shaping the composition of fish communities in creeks draining the facilities. This task addresses specific questions concerning (1) the reproductive competence of adult fish in the streams, and (2) the capacity of fish embryos and fry to survive and develop sequent reproductive cohorts. Evidence for current or potential reproductive impacts in several of the streams include abnormal fecundity at some sites, increased incidences of oocyte atresia, and a marked toxicity of surface water samples from several stream reaches to fish embryos in periodic embryo-larval tests. Recovery of certain of the monitored streams in response to ongoing remedial actions is documented by positive changes over time in many these indicators of reproductive dysfunction. These results suggest that the monitoring of reproductive indicators can be a sensitive tool for assessing the effects of both industrial discharges and remedial activities on the fish resources of receiving streams

  7. Impact of landscape characteristics on the stream carbon and nitrogen export: example of a small agricultural catchment in Denmark

    DEFF Research Database (Denmark)

    Wohlfart, T.; Exbrayat, J.F.; Schelde, Kirsten

    2012-01-01

    Agriculture plays an important role on the environment, notably the quality of water draining cultivated soils. Understanding the relationship between landscape characteristics and stream quality is crucial to sustain a good quality of water and to develop adapted policies. Therefore, this study...... point between the chemical data and landscape characteristics (e.g. topography, land-use and soil type distributions) of the corresponding contributing area. Results show that, in spite of an overall little share, the influence of organic soil types seems to impact N losses to streams stronger than...... local land use by farming....

  8. CSER 94-011: Use of glovebags for demister draining operations

    International Nuclear Information System (INIS)

    Hess, A.L.

    1994-01-01

    A criticality safety review is presented for the use of plastic-sheet glovebags for the operations of draining demisters on the 26-inch vacuum system headers. A criticality drain is required because of the possibility for spilling liquid of sufficient volume and fissile content for criticality. It is recommended that the glovebag design include a rigid, 2ft x 2ft floor with a central drain feeding a geometrically favorable spill-catch vessel, plus a screen grid above the bottom for drain protection

  9. Draining after breast reduction: a randomised controlled inter-patient study

    NARCIS (Netherlands)

    Corion, Leonard U. M.; Smeulders, Mark J. C.; van Zuijlen, Paul P. M.; van der Horst, Chantal M. A. M.

    2009-01-01

    One hundred and seven bilateral breast reductions were prospectively randomised during surgery to receive or not receive wound drains. Fifty-five patients were randomised to have a drain and 52 to not have a drain. There was no statistical difference in the number of complications between the

  10. The "brain drain" of health care workers: causes, solutions and the example of Jamaica.

    Science.gov (United States)

    Lofters, Aisha K

    2012-07-18

    Despite much media attention being given to the physician shortage in Canada in recent years, this shortage pales in comparison to that seen in many middle- and low-income countries. A major cause of the shortage in these countries is the migration of health care workers from developing to developed nations, a phenomenon known as the "brain drain". The loss of these workers is having devastating impacts globally, particularly in Sub-Saharan Africa and the Caribbean. Causes of the "brain drain" are numerous and include poor working conditions in poorer countries and active recruitment by richer countries. Jamaica has been one of the countries in the Caribbean hardest hit by mass migration of health care workers. The multiple dimensions of Jamaica's health worker "brain drain" illustrate both the complexity of the issues reviewed in this commentary, and the net loss for low- and middle-income countries. Creative and sustainable solutions to the problem are actively being sought globally, but will require commitment and support from all nations as well as from international funding bodies if meaningful impacts on health are to be realized.

  11. Study of the patency of different peritoneal drains used prophylactically in bariatric surgery.

    Science.gov (United States)

    Salgado Júnior, Wilson; Macedo Neto, Marcelo Martins; dos Santos, José Sebastião; Sakarankutty, Ajith Kumar; Ceneviva, Reginaldo; de Castro e Silva, Orlando

    2009-05-21

    To compare the performance of different types of abdominal drains used in bariatric surgery. A vertical banded Roux-en-Y gastric bypass was performed in 33 morbidly obese patients. Drainage of the peritoneal cavity was performed in each case using three different types of drain selected in a randomized manner: a latex tubular drain, a Watterman tubulolaminar drain, and a silicone channeled drain. Drain permeability, contamination of the drained fluid, ease of handling, and patient discomfort were evaluated postoperatively over a period of 7 d. The patients with the silicone channeled drain had larger volumes of drainage compared to patients with tubular and tubulolaminar drains between the third and seventh postoperative days. In addition, a lower incidence of discomfort and of contamination with bacteria of a more pathogenic profile was observed in the patients with the silicone channeled drain. The silicone channeled drain was more comfortable and had less chance of occlusion, which is important in the detection of delayed dehiscence.

  12. Intrinsic stream-capture control of stepped fan pediments in the High Atlas piedmont of Ouarzazate (Morocco)

    Science.gov (United States)

    Pastor, A.; Babault, J.; Teixell, A.; Arboleya, M. L.

    2012-11-01

    The Ouarzazate basin is a Cenozoic foreland basin located to the south of the High Atlas Mountains. The basin has been externally drained during the Quaternary, with fluvial dynamics dominated by erosive processes from a progressive base level drop. The current drainage network is composed of rivers draining the mountain and carrying large amounts of coarse sediments and by piedmont streams with smaller catchments eroding the soft Cenozoic rocks of the Ouarzazate basin. The coarse-grained sediments covering the channel beds of main rivers cause the steepening of the channel gradient and act as a shield inhibiting bedrock incision. Under such circumstances, piedmont streams that incise to lower gradients evolve to large, depressed pediments at lower elevations and threaten to capture rivers originating in the mountain. Much of the current surface of the Ouarzazate basin is covered by coarse sediments forming large systems of stepped fan pediments that developed by the filling of low elevation pediments after a capture event. We identified 14 capture events, and previously published geochronology support an ~ 100 ka frequency for fan pediment formation. Our study indicates that the reorganization of the fluvial network in the Ouarzazate basin during the late Pleistocene and Holocene has been controlled by the piedmont-stream piracy process, a process ultimately controlled by the cover effect. The stream capture is influenced by erosion, sediment supply and transport, and therefore may not be entirely decoupled from tectonic and climatic forcing. Indeed, we show that at least two capture events may have occurred during climate changes, and local tectonic structures control at most the spatial localization of capture events.

  13. Advances in chest drain management in thoracic disease

    Science.gov (United States)

    George, Robert S.

    2016-01-01

    An adequate chest drainage system aims to drain fluid and air and restore the negative pleural pressure facilitating lung expansion. In thoracic surgery the post-operative use of the conventional underwater seal chest drainage system fulfills these requirements, however they allow great variability amongst practices. In addition they do not offer accurate data and they are often inconvenient to both patients and hospital staff. This article aims to simplify the myths surrounding the management of chest drains following chest surgery, review current experience and explore the advantages of modern digital chest drain systems and address their disease-specific use. PMID:26941971

  14. Effect of road salt application on seasonal chloride concentrations and toxicity in south-central Indiana streams.

    Science.gov (United States)

    Gardner, Kristin M; Royer, Todd V

    2010-01-01

    Contemporary information on road salt runoff is needed for management of water resources in regions experiencing urbanization and increased road density. We investigated seasonal Cl(-) concentrations among five streams in south-central Indiana that drained watersheds varying in degree of urbanization and ranging in size from 9.3 to 27 km(2). We also conducted acute toxicity tests with Daphnia pulex to assess the potential effects of the observed Cl(-) concentrations on aquatic life. Periods of elevated Cl(-) concentrations were observed during the winters of 2007-08 and 2008-09 at all sites except the reference site. The highest Cl(-) concentration observed during the study was 2100 mg L(-1) and occurred at the most urbanized site. The Cl(-) concentration at the reference site never exceeded 22 mg L(-1). The application of road salt caused large increases in stream Cl(-) concentrations, but the elevated Cl(-) levels did not appear to be a significant threat to aquatic life based on our toxicity testing. Only the most urbanized site showed evidence of salt retention within the watershed, whereas the other sites exported the road salt relatively quickly after its application, suggesting storm drains and impervious surfaces minimized interaction between soils and salt-laden runoff. During winter at these sites, the response in stream Cl(-) concentrations appeared to be controlled by the timing and intensity of road salt application, the magnitude of precipitation, and the occurrence of air temperatures that caused snowmelt and generated runoff.

  15. An Equal-Strain Analytical Solution for the Radial Consolidation of Unsaturated Soils by Vertical Drains considering Drain Resistance

    Directory of Open Access Journals (Sweden)

    Feng Zhou

    2018-01-01

    Full Text Available Developing an analytical solution for the consolidation of unsaturated soils remains a challenging task due to the complexity of coupled governing equations for air and water phases. This paper presents an equal-strain model for the radial consolidation of unsaturated soils by vertical drains, and the effect of drain resistance is also considered. Simplified governing equations are established, and an analytical solution to calculate the excess pore-air and pore-water pressures is derived by using the methods of matrix analysis and eigenfunction expansion. The average degrees of consolidation for air and water phases and the ground surface settlement are also given. The solutions of the equal-strain model are verified by comparing the proposed free-strain model with the equal-strain model, and reasonably good agreement is obtained. Moreover, parametric studies regarding the drain resistance effect are graphically presented.

  16. Relationship of bleeding complications and impairment of draining veins after α-n-butyl cyanoacrylate embolization of brain arteriovenous malformations

    International Nuclear Information System (INIS)

    Fang Bing; Wang Yirong; Li Tielin; Duan Chuanzhi; Wang Qiujing; Zhao Qingping

    2007-01-01

    Objective: To investigate the causes, consequences and management of injuries to the draining veins after embolization of brain arterioven0us malformations (BAVMs) with α-n-butyl cyanoacrylate (NBCA). Methods: The angiographic imaging data of 189 BAVMs patients who underwent NBCA embolization were studied retrospectively. The status of the draining veins before and after NBCA embolization was observed and compared. The intracerebral hemorrhage (ICH)complications and their relation to their angiographic features were analyzed. Results: Twenty-three patients out of 189 patients showed injuries to the draining venous system, including 10 low-grade injury, 6 moderate injury, and 7 high-grade injury. Six patients suffered from ICH after embolization, of whom 4 patients were due to injuries of the draining veins (2 moderate and 2 high-grade). In the 3 months follow-up evaluation of 4 patients with ICH, one died, one was in vegetative state, and the other two patients suffered from residual severe or minor (1 patient for each) permanent neurological deficits. Conclusion: Our findings suggest that injury of the draining veins is the major cause of ICH and may lead to serious consequences after embolization of BAVMs with NBCA. (authors)

  17. Percutaneous Retrieval of a Retained Jackson-Pratt Drain Fragment

    International Nuclear Information System (INIS)

    Namyslowski, Jan; Halin, Neil J.; Greenfield, Alan J.

    1996-01-01

    A retained intraabdominal Jackson-Pratt drain fragment was percutaneously retrieved using an inflated angioplasty balloon that had been maneuvered inside of the drain lumen over a hydrophilic-coated steerable guidewire

  18. The Effects of Agricultural Land-use on Stream Fish and Invertebrate Communities and Food-web Structure.

    Science.gov (United States)

    North, C. A.; Fischer, R. U.

    2005-05-01

    Incorporating knowledge of the surrounding landscape can further the understanding of stream processes. This is particularly true in areas like the Midwest where human alteration of the landscape, such as conversion of natural cover types into cultivated row crops, is widespread. When assessing stream health, the composition and structure of biological communities themselves often are the best indicators of water quality. Previous work in Hurricane Creek (Coles and Cumberland Counties, IL) demonstrated significant differences in water chemistry and community metabolism between sites subject to differing intensities of farming in the upstream watershed. Our objective was to examine differences in fish and invertebrate communities at four sites along the stream representing varying degrees of agricultural land-use. Fish were sampled using electroseining techniques and invertebrates were collected using the 20-jab method in each of four seasons. Sites were compared using fish and invertebrate community metrics, including indices of biotic integrity (IBI, MBI). Stable isotope analyses were also performed to quantify differences in food-web structure in streams draining watersheds characterized by different degrees of agricultural land-use. This study improves understanding of how landscape alteration impacts stream biota and will facilitate more informed decisions concerning stream rehabilitation.

  19. Test of a simplified modeling approach for nitrogen transfer in agricultural subsurface-drained catchments

    Science.gov (United States)

    Henine, Hocine; Julien, Tournebize; Jaan, Pärn; Ülo, Mander

    2017-04-01

    In agricultural areas, nitrogen (N) pollution load to surface waters depends on land use, agricultural practices, harvested N output, as well as the hydrology and climate of the catchment. Most of N transfer models need to use large complex data sets, which are generally difficult to collect at larger scale (>km2). The main objective of this study is to carry out a hydrological and a geochemistry modeling by using a simplified data set (land use/crop, fertilizer input, N losses from plots). The modelling approach was tested in the subsurface-drained Orgeval catchment (Paris Basin, France) based on following assumptions: Subsurface tile drains are considered as a giant lysimeter system. N concentration in drain outlets is representative for agricultural practices upstream. Analysis of observed N load (90% of total N) shows 62% of export during the winter. We considered prewinter nitrate (NO3) pool (PWNP) in soils at the beginning of hydrological drainage season as a driving factor for N losses. PWNP results from the part of NO3 not used by crops or the mineralization part of organic matter during the preceding summer and autumn. Considering these assumptions, we used PWNP as simplified input data for the modelling of N transport. Thus, NO3 losses are mainly influenced by the denitrification capacity of soils and stream water. The well-known HYPE model was used to perform water and N losses modelling. The hydrological simulation was calibrated with the observation data at different sub-catchments. We performed a hydrograph separation validated on the thermal and isotopic tracer studies and the general knowledge of the behavior of Orgeval catchment. Our results show a good correlation between the model and the observations (a Nash-Sutcliffe coefficient of 0.75 for water discharge and 0.7 for N flux). Likewise, comparison of calibrated PWNP values with the results from a field survey (annual PWNP campaign) showed significant positive correlation. One can conclude that

  20. Laparoscopic elective cholecystectomy with and without drain: A controlled randomised trial

    Directory of Open Access Journals (Sweden)

    Gouda El-labban

    2012-01-01

    Full Text Available Background : Laparoscopic cholecystectomy is the main method of treatment of symptomatic gallstones. Routine drainage after laparoscopic cholecystectomy is an issue of considerable debate. Therefore, a controlled randomised trial was designed to assess the value of drains in elective laparoscopic cholecystectomy. Materials and Methods: During a two-year period (From April 2008 to January 2010, 80 patients were simply randomised to have a drain placed (group A, an 8-mm pentose tube drain was retained below the liver bed, whereas 80 patients were randomised not to have a drain (group B placed in the subhepatic space. End points of this trial were to detect any differences in morbidity, postoperative pain, wound infection and hospital stay between the two groups. Results : There was no mortality in either group and no statistically significant difference in postoperative pain, nausea and vomiting, wound infection or abdominal collection between the two groups. However, hospital stay was longer in the drain group than in group without drain and it is appearing that the use of drain delays hospital discharge. Conclusion : The routine use of a drain in non-complicated laparoscopic cholecystectomy has nothing to offer; in contrast, it is associated with longer hospital stay.

  1. The Then and Now of Reference Conditions in Streams of the Central Plains

    Science.gov (United States)

    Huggins, D.; Angelo, R.; Baker, D. S.; Welker, G.

    2005-05-01

    Models of contemporary and pre-settlement reference conditions were constructed for streams that once drained the tallgrass prairies of Iowa, Nebraska, Kansas and Missouri (e.g. Western Corn Belt Plains ecoregion), and for streams within the heart of the mixed grass prairie (e.g. Southwestern Tablelands ecoregion). Data on watershed, habitat, chemistry and biology compiled for existing reference streams (least or minimally impacted systems) were used to characterize contemporary reference conditions. Contemporary reference conditions within these two prairie regions are contrasted against hypothetical pre-settlement conditions using information from the best streams (upper 25%) of the current reference population, historical accounts, museum records, natural heritage programs, Public Land Survey and current remote sensing data. Similar comparisons were made between historical and current reference conditions for the Southwestern Tablelands located in central Kansas and Oklahoma. Much of this region remains in mixed grass prairie; has limited hydrological alterations (e.g. impoundments, dewatering) and low human and livestock densities. Within the tablelands these factors have preserved reference conditions that resemble historic conditions. Qualitative and quantitative comparisons indicate that many regions within the Central Plains require caution when using "least disturbed" reference streams and conditions to identify regional biological integrity goals relative to the Clean Water Act.

  2. Powerful Software to Simulate Soil Consolidation Problems with Prefabricated Vertical Drains

    OpenAIRE

    Gonzalo García-Ros; Iván Alhama; Manuel Cánovas

    2018-01-01

    The present work describes the program Simulation of Consolidation with Vertical Drains (SICOMED_2018), a tool for the solution of consolidation processes in heterogeneous soils, with totally or partially penetrating prefabricated vertical drains (PVD) and considering both the effects of the smear zone, generated when introducing the drain into the ground, and the limitation in the discharge capacity of the drain. In order to provide a completely free program, the code Next-Generation Simulat...

  3. Investigation of radioactive contamination at non-radioactive drains of the Tsuruga Nuclear Power Station

    International Nuclear Information System (INIS)

    Koide, Hiroaki; Imanaka, Tetsuji; Ebisawa, Toru; Kawano, Shinji; Kobayashi, Keiji.

    1982-05-01

    In April, 1981, it was disclosed that a drainage area at the Tsuruga Nuclear Power Station was so much contaminated with radioactivites. Although Ministry of International Trade and Industry (MITI) officially provided an explanation of a process that resulted in the contamination, many problems remain unsolved on account of insufficient and limited investigations. The authors collected mud samples from contaminated manholes and examined radioactivities in them through the measurement of #betta#- and #betta#-spectra. Chemical separation of the samples was carried out in order to obtain precise concentration of radioactive cesium. Results are as follows: i) the concentration of radioactivities does not show monotonous decrease along the stream line but an anomalous peak at downstream manholes, ii) at the manhole specified No. 6 located rather downstream, 137 Cs concentration is significantly high and the composition of radioactive nuclides is quite different from that in the other manholes, and iii) additional radioactive contamination was observed in other manholes of non-radioactive drains which would not be influenced by the accident explained by MITI. Our present work has provided much more data than by MITI and made it clear that the overall data cnnot be consistent with the simple MITI explanation; a single radioactive release accident caused the disclosed contamination. It is concluded that non-radioactive water drains at the Tsuruga Nuclear Power Station had been under continual contamination. (author)

  4. VARIABILITY OF VALUES OF PHYSICOCHEMICAL WATER QUALITY INDICES ALONG THE LENGTH OF THE IWONICZANKA STREAM

    Directory of Open Access Journals (Sweden)

    Andrzej Bogdał

    2015-11-01

    Full Text Available The paper aims at presentation of the effect of changes in the catchment area management on the value of water quality physicochemical indices along the length of the Iwoniczanka stream, which flows through Iwonicz-Zdrój, one of the oldest health resorts in Poland. Analyses of 14 water quality indices were conducted from November 2013 to May 2014 in five measurement points: two situated in the upper course of the stream – in forest areas, two located in the area of Iwonicz-Zdrój town, and one below the rural built-up area. On the basis of the conducted data analysis it was found that the mean values of pH, electrolytic conductivity, sulphates, calcium, total iron and manganese were increasing with the course of flowing water, as evidenced by the water enrichment in substances which had their sources in built-up areas. On average, the highest values of biogenic indices and chlorides but the lowest values of oxygen indices were registered immediately below the location of drain collector from the closed sewage treatment plant, which resulted in pollution of the analysed stream bed with the substances previously drained from the treatment plant. Water flowing through the forest areas had the maximum ecological potential in the built-up areas and due to phosphate concentrations it was classified to class II and then, due to self-purification, returned to the physicochemical parameters appropriate for class I water. The conducted hydro-chemical tests confirmed a significant negative effect of built-up areas on the quality of the flowing waters.

  5. Iatrogenic Perforation of the Left Ventricle during Insertion of a Chest Drain

    OpenAIRE

    Kim, Dongmin; Lim, Seong-Hoon; Seo, Pil Won

    2013-01-01

    Chest draining is a common procedure for treating pleural effusion. Perforation of the heart is a rare often fatal complication of chest drain insertion. We report a case of a 76-year-old female patient suffering from congestive heart failure. At presentation, unilateral opacity of the left chest observed on a chest X-ray was interpreted as massive pleural effusion, so an attempt was made to drain the left pleural space. Malposition of the chest drain was suspected because blood was draining ...

  6. Horner's syndrome caused by an intercostal chest drain.

    OpenAIRE

    Campbell, P; Neil, T; Wake, P N

    1989-01-01

    Horner's syndrome occurred in a young woman as a complication of the treatment of a traumatic pneumothorax with an intercostal drain. The nerve damage probably occurred when the lung had fully re-expanded, pressing the tip of the intercostal drain, lying at the apex of the pleural cavity, on to the sympathetic chain.

  7. Rethinking "Brain Drain" in the Era of Globalisation

    Science.gov (United States)

    Rizvi, Fazal

    2005-01-01

    This paper discusses a range of issues concerning the idea of "brain drain" within the context of recent thinking on transnational mobility. It argues that the traditional analyses of brain drain are not sufficient, and that we can usefully approach the topic from a postcolonial perspective concerned with issues of identity, national…

  8. Partitioning Hydrologic and Biological Drivers of Discharge Loss in Arctic Headwater Streams

    Science.gov (United States)

    Koch, J. C.; Carey, M.; O'Donnell, J. A.; Records, M. K.; Sjoberg, Y.; Zimmerman, C. E.

    2017-12-01

    The Arctic-Boreal transition (ABT) zone of Alaska is experiencing unprecedented warming, leading to permafrost thaw and vegetation change. Both of these processes are likely to affect streams and stream ecosystems, but there is little direct empirical evidence regarding the magnitude of these effects and their relative importance. To understand how permafrost thaw and vegetation are affecting streams at the ABT, we monitored 8 first-order streams that drain catchments varying in elevation, aspect, and vegetation cover. Data were obtained from meteorological stations, continuous stream discharge, seepage runs, and stream tracer experiments. Hydrograph analysis indicated that runoff ratios in south-facing catchments were lower than north-facing catchments and decreased over the season. Seepage runs indicated that south-facing catchments lost a large portion of water (up to 50% per km stream reach) in the late summer, while north-facing catchments were gaining water. All streams displayed diel variability in discharge, but with different daily and seasonal trends related to aspect and elevation. South-facing, forested catchment streams showed diel discharge timing consistent with cycles in evapotranspiration rates, while the signal in north-facing catchments and those dominated by tundra was more consistent with thermal controls on water viscosity and groundwater discharge to streams. Together, these signals indicate that the warmer, south-facing catchments are losing a large portion of water to a combination of infiltration and evapotranspiration. The seasonal trends are consistent with higher infiltration rates beneath south-facing streams as the ground thaws over the summer. The magnitude and seasonal dynamics of the diel signatures help separate biological (i.e. evapotranspiration) vs. physical controls (i.e. frozen ground hydrology) on stream-catchment interactions, which vary depending on aspect, elevation, and vegetation cover. Warming, and subsequent increases

  9. Comparison of a large and small-calibre tube drain for managing spontaneous pneumothoraces.

    Science.gov (United States)

    Benton, Ian J; Benfield, Grant F A

    2009-10-01

    To compare treatment success of large- and small-bore chest drains in the treatment of spontaneous pneumothoraces the case-notes were reviewed of those admitted to our hospital with a total of 73 pneumothoraces and who were treated by trainee doctors of varying experience. Both a large- and a small-bore intercostal tube drain system were in use during the two-year period reviewed. Similar pneumothorax profile and numbers treated with both drains were recorded, resulting in a similar drain time and numbers of successful and failed re-expansion of pneumothoraces. Successful pneumothorax resolution was the same for both drain types and the negligible tube drain complications observed with the small-bore drain reflected previously reported experiences. However the large-bore drain was associated with a high complication rate (32%) with more infectious complications (24%). The small-bore drain was prone to displacement (21%). There was generally no evidence of an increased failure and morbidity, reflecting poorer expertise, in the non-specialist trainees managing the pneumothoraces. A practical finding however was that in those large pneumothoraces where re-expansion failed, the tip of the drain had not been sited at the apex of the pleural cavity irrespective of the drain type inserted.

  10. Watershed regressions for pesticides (WARP) for predicting atrazine concentration in Corn Belt streams

    Science.gov (United States)

    Stone, Wesley W.; Gilliom, Robert J.

    2011-01-01

    Watershed Regressions for Pesticides (WARP) models, previously developed for atrazine at the national scale, can be improved for application to the U.S. Corn Belt region by developing region-specific models that include important watershed characteristics that are influential in predicting atrazine concentration statistics within the Corn Belt. WARP models for the Corn Belt (WARP-CB) were developed for predicting annual maximum moving-average (14-, 21-, 30-, 60-, and 90-day durations) and annual 95th-percentile atrazine concentrations in streams of the Corn Belt region. All streams used in development of WARP-CB models drain watersheds with atrazine use intensity greater than 17 kilograms per square kilometer (kg/km2). The WARP-CB models accounted for 53 to 62 percent of the variability in the various concentration statistics among the model-development sites.

  11. Endocrine disrupting alkylphenolic chemicals and other contaminants in wastewater treatment plant effluents, urban streams, and fish in the Great Lakes and Upper Mississippi River Regions.

    Science.gov (United States)

    Barber, Larry B; Loyo-Rosales, Jorge E; Rice, Clifford P; Minarik, Thomas A; Oskouie, Ali K

    2015-06-01

    Urban streams are an integral part of the municipal water cycle and provide a point of discharge for wastewater treatment plant (WWTP) effluents, allowing additional attenuation through dilution and transformation processes, as well as a conduit for transporting contaminants to downstream water supplies. Domestic and commercial activities dispose of wastes down-the-drain, resulting in wastewater containing complex chemical mixtures that are only partially removed during treatment. A key issue associated with WWTP effluent discharge into streams is the potential to cause endocrine disruption in fish. This study provides a long-term (1999-2009) evaluation of the occurrence of alkylphenolic endocrine disrupting chemicals (EDCs) and other contaminants discharged from WWTPs into streams in the Great Lakes and Upper Mississippi River Regions (Indiana, Illinois, Michigan, Minnesota, and Ohio). The Greater Metropolitan Chicago Area Waterways, Illinois, were evaluated to determine contaminant concentrations in the major WWTP effluents and receiving streams, and assess the behavior of EDCs from their sources within the sewer collection system, through the major treatment unit processes at a WWTP, to their persistence and transport in the receiving stream. Water samples were analyzed for alkylphenolic EDCs and other contaminants, including 4-nonylphenol (NP), 4-nonylphenolpolyethoxylates (NPEO), 4-nonylphenolethoxycarboxylic acids (NPEC), 4-tert-octylphenol (OP), 4-tert-octylphenolpolyethoxylates (OPEO), bisphenol A, triclosan, ethylenediaminetetraacetic acid (EDTA), and trace elements. All of the compounds were detected in all of the WWTP effluents, with EDTA and NPEC having the greatest concentrations. The compounds also were detected in the WWTP effluent dominated rivers. Multiple fish species were collected from river and lake sites and analyzed for NP, NPEO, NPEC, OP, and OPEO. Whole-body fish tissue analysis indicated widespread occurrence of alkylphenolic compounds

  12. Endocrine disrupting alkylphenolic chemicals and other contaminants in wastewater treatment plant effluents, urban streams, and fish in the Great Lakes and Upper Mississippi River Regions

    Science.gov (United States)

    Barber, Larry B.; Loyo-Rosales, Jorge E.; Rice, Clifford P.; Minarik, Thomas A.; Oskouie, Ali K.

    2015-01-01

    Urban streams are an integral part of the municipal water cycle and provide a point of discharge for wastewater treatment plant (WWTP) effluents, allowing additional attenuation through dilution and transformation processes, as well as a conduit for transporting contaminants to downstream water supplies. Domestic and commercial activities dispose of wastes down-the-drain, resulting in wastewater containing complex chemical mixtures that are only partially removed during treatment. A key issue associated with WWTP effluent discharge into streams is the potential to cause endocrine disruption in fish. This study provides a long-term (1999-2009) evaluation of the occurrence of alkylphenolic endocrine disrupting chemicals (EDCs) and other contaminants discharged from WWTPs into streams in the Great Lakes and Upper Mississippi River Regions (Indiana, Illinois, Michigan, Minnesota, and Ohio). The Greater Metropolitan Chicago Area Waterways, Illinois, were evaluated to determine contaminant concentrations in the major WWTP effluents and receiving streams, and assess the behavior of EDCs from their sources within the sewer collection system, through the major treatment unit processes at a WWTP, to their persistence and transport in the receiving stream. Water samples were analyzed for alkylphenolic EDCs and other contaminants, including 4-nonylphenol (NP), 4-nonylphenolpolyethoxylates (NPEO), 4-nonylphenolethoxycarboxylic acids (NPEC), 4-tert-octylphenol (OP), 4-tert-octylphenolpolyethoxylates (OPEO), bisphenol A, triclosan, ethylenediaminetetraacetic acid (EDTA), and trace elements. All of the compounds were detected in all of the WWTP effluents, with EDTA and NPEC having the greatest concentrations. The compounds also were detected in the WWTP effluent dominated rivers. Multiple fish species were collected from river and lake sites and analyzed for NP, NPEO, NPEC, OP, and OPEO. Whole-body fish tissue analysis indicated widespread occurrence of alkylphenolic compounds

  13. FROM BRAIN DRAIN TO BRAIN NETWORKING

    Directory of Open Access Journals (Sweden)

    Irina BONCEA

    2015-06-01

    Full Text Available Scientific networking is the most accessible way a country can turn the brain drain into brain gain. Diaspora’s members offer valuable information, advice or financial support from the destination country, without being necessary to return. This article aims to investigate Romania’s potential of turning brain drain into brain networking, using evidence from the medical sector. The main factors influencing the collaboration with the country of origin are investigated. The conclusions suggest that Romania could benefit from the diaspora option, through an active implication at institutional level and the implementation of a strategy in this area.

  14. Carbon accumulation in pristine and drained mires

    Energy Technology Data Exchange (ETDEWEB)

    Maekilae, M.

    2011-07-01

    The carbon accumulation of 73 peat columns from 48 pristine and drained mires was investigated using a total of 367 dates and age-depth models derived from bulk density measurements. Peat columns were collected from mires of varying depth, age, degree of natural state and nutrient conditions in aapa mire and raised bog regions and coastal mires from southern and central Finland and Russian Karelia. Particular attention was paid to the accumulation of carbon over the last 300 years, as this period encompasses the best estimates of the oxic layer (acrotelm) age across the range of sites investigated. In general, drained mires are initially more nutrient-rich than pristine mires. Organic matter decomposes more rapidly at drained sites than at pristine sites, resulting in thinner peat layers and carbon accumulation but a higher dry bulk density and carbon content. The average carbon accumulation was calculated as 24.0 g m-2 yr-1 at pristine sites and 19.4 g m-2 yr-1 at drained sites, while for peat layers younger than 300 years the respective figures were 45.3 and 34.5 g m-2 yr-1 at pristine and drained sites. For the <300-year-old peat layers studied here, the average thickness was 19 cm less and the carbon accumulation rate 10.8 g m-2 yr-1 lower in drained areas than in pristine areas. The amount carbon accumulation of surface peat layers depends upon the mire site type, vegetation and natural state; variations reflect differences in plant communities as well as factors that affect biomass production and decay rates. The highest accumulation rates and thus carbon binding for layers younger than 300 years were measured in the ombrotrophic mire site types (Sphagnum fuscum bog and Sphagnum fuscum pine bog), and the second highest rates in wet, treeless oligotrophic and minerotrophic mire site types. The lowest values of carbon accumulation over the last 300 years were obtained for the most transformed, sparsely forested and forested mire site types, where the water

  15. Climate mitigation scenarios of drained peat soils

    Science.gov (United States)

    Kasimir Klemedtsson, Åsa; Coria, Jessica; He, Hongxing; Liu, Xiangping; Nordén, Anna

    2014-05-01

    The national inventory reports (NIR) submitted to the UNFCCC show Sweden - which as many other countries has wetlands where parts have been drained for agriculture and forestry purposes, - to annually emit 12 million tonnes carbon dioxide equivalents, which is more GHG'es than industrial energy use release in Sweden. Similar conditions can be found in other northern countries, having cool and wet conditions, naturally promoting peat accumulation, and where land use management over the last centuries have promoted draining activities. These drained peatland, though covering only 2% of the land area, have emissions corresponding to 20% of the total reported NIR emissions. This substantial emission contribution, however, is hidden within the Land Use Land Use Change and Forestry sector (LULUCF) where the forest Carbon uptake is even larger, which causes the peat soil emissions become invisible. The only drained soil emission accounted in the Swedish Kyoto reporting is the N2O emission from agricultural drained organic soils of the size 0.5 million tonnes CO2e yr-1. This lack of visibility has made incentives for land use change and management neither implemented nor suggested, however with large potential. Rewetting has the potential to decrease soil mineralization, why CO2 and N2O emissions are mitigated. However if the soil becomes very wet CH4 emission will increase together with hampered plant growth. By ecological modeling, using the CoupModel the climate change mitigation potential have been estimated for four different land use scenarios; 1, Drained peat soil with Spruce (business as usual scenario), 2, raised ground water level to 20 cm depth and Willow plantation, 3, raised ground water level to 10 cm depth and Reed Canary Grass, and 4, rewetting to an average water level in the soil surface with recolonizing wetland plants and mosses. We calculate the volume of biomass production per year, peat decomposition, N2O emission together with nitrate and DOC

  16. Method of draining water through a solid waste site without leaching

    Science.gov (United States)

    Treat, Russell L.; Gee, Glendon W.; Whyatt, Greg A.

    1993-01-01

    The present invention is a method of preventing water from leaching solid waste sites by preventing atmospheric precipitation from contacting waste as the water flows through a solid waste site. The method comprises placing at least one drain hole through the solid waste site. The drain hole is seated to prevent waste material from entering the drain hole, and the solid waste site cover material is layered and graded to direct water to flow toward the drain hole and to soil beneath the waste site.

  17. Estimation of snow and glacier melt contribution to Liddar stream in a mountainous catchment, western Himalaya: an isotopic approach.

    Science.gov (United States)

    Jeelani, Gh; Shah, Rouf A; Jacob, Noble; Deshpande, Rajendrakumar D

    2017-03-01

    Snow- and glacier-dominated catchments in the Himalayas are important sources of fresh water to more than one billion people. However, the contribution of snowmelt and glacier melt to stream flow remains largely unquantified in most parts of the Himalayas. We used environmental isotopes and geochemical tracers to determine the source water and flow paths of stream flow draining the snow- and glacier-dominated mountainous catchment of the western Himalaya. The study suggested that the stream flow in the spring season is dominated by the snowmelt released from low altitudes and becomes isotopically depleted as the melt season progressed. The tracer-based mixing models suggested that snowmelt contributed a significant proportion (5-66 %) to stream flow throughout the year with the maximum contribution in spring and summer seasons (from March to July). In 2013 a large and persistent snowpack contributed significantly (∼51 %) to stream flow in autumn (September and October) as well. The average annual contribution of glacier melt to stream flow is little (5 %). However, the monthly contribution of glacier melt to stream flow reaches up to 19 % in September during years of less persistent snow pack.

  18. Managing Artificially Drained Low-Gradient Agricultural Headwaters for Enhanced Ecosystem Functions

    Science.gov (United States)

    Pierce, Samuel C.; Kröger, Robert; Pezeshki, Reza

    2012-01-01

    Large tracts of lowlands have been drained to expand extensive agriculture into areas that were historically categorized as wasteland. This expansion in agriculture necessarily coincided with changes in ecosystem structure, biodiversity, and nutrient cycling. These changes have impacted not only the landscapes in which they occurred, but also larger water bodies receiving runoff from drained land. New approaches must append current efforts toward land conservation and restoration, as the continuing impacts to receiving waters is an issue of major environmental concern. One of these approaches is agricultural drainage management. This article reviews how this approach differs from traditional conservation efforts, the specific practices of drainage management and the current state of knowledge on the ecology of drainage ditches. A bottom-up approach is utilized, examining the effects of stochastic hydrology and anthropogenic disturbance on primary production and diversity of primary producers, with special regard given to how management can affect establishment of macrophytes and how macrophytes in agricultural landscapes alter their environment in ways that can serve to mitigate non-point source pollution and promote biodiversity in receiving waters. PMID:24832519

  19. Managing Artificially Drained Low-Gradient Agricultural Headwaters for Enhanced Ecosystem Functions

    Directory of Open Access Journals (Sweden)

    Reza Pezeshki

    2012-12-01

    Full Text Available Large tracts of lowlands have been drained to expand extensive agriculture into areas that were historically categorized as wasteland. This expansion in agriculture necessarily coincided with changes in ecosystem structure, biodiversity, and nutrient cycling. These changes have impacted not only the landscapes in which they occurred, but also larger water bodies receiving runoff from drained land. New approaches must append current efforts toward land conservation and restoration, as the continuing impacts to receiving waters is an issue of major environmental concern. One of these approaches is agricultural drainage management. This article reviews how this approach differs from traditional conservation efforts, the specific practices of drainage management and the current state of knowledge on the ecology of drainage ditches. A bottom-up approach is utilized, examining the effects of stochastic hydrology and anthropogenic disturbance on primary production and diversity of primary producers, with special regard given to how management can affect establishment of macrophytes and how macrophytes in agricultural landscapes alter their environment in ways that can serve to mitigate non-point source pollution and promote biodiversity in receiving waters.

  20. Inverse problem in anisotropic poroelasticity: drained constants from undrained ultrasound measurements.

    Science.gov (United States)

    Berryman, James G; Nakagawa, Seiji

    2010-02-01

    Poroelastic analysis has traditionally focused on the relationship between dry and drained constants, which are assumed known, and the saturated or undrained constants, which are assumed unknown. However, there are many applications in this field of study for which the main measurements can only be made on the saturated/undrained system, and then it is uncertain what the effects of the fluids were on the system, since the drained constants remain a mystery. The work presented here shows how to deduce drained constants from undrained constants for anisotropic systems having symmetries ranging from isotropic to orthotropic. Laboratory ultrasound data are then inverted for the drained constants in three granular packings: one of glass beads, and two others for distinct types of more or less angular sand grain packings. Experiments were performed under uniaxial stress, which resulted in hexagonal (transversely isotropic) symmetry of the poroelastic response. One important conclusion from the general analysis is that the drained constants are uniquely related to the undrained constants, assuming that porosity, grain bulk modulus, and pore fluid bulk modulus are already known. Since the resulting system of equations for all the drained constants is linear, measurement error in undrained constants also propagates linearly into the computed drained constants.

  1. Inverse problem in anisotropic poroelasticity: Drained constants from undrained ultrasound measurements

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J.G.; Nakagawa, S.

    2009-11-20

    Poroelastic analysis has traditionally focused on the relationship between dry or drained constants which are assumed known and the saturated or undrained constants which are assumed unknown. However, there are many applications in this field of study for which the main measurements can only be made on the saturated/undrained system, and then it is uncertain what the eects of the uids were on the system, since the drained constants remain a mystery. The work presented here shows how to deduce drained constants from undrained constants for anisotropic systems having symmetries ranging from isotropic to orthotropic. Laboratory ultrasound data are then inverted for the drained constants in three granular packings: one of glass beads, and two others for distinct types of more or less angular sand grain packings. Experiments were performed under uniaxial stress, which resulted in hexagonal (transversely isotropic) symmetry of the poroelastic response. One important conclusion from the general analysis is that the drained constants are uniquely related to the undrained constants, assuming that porosity, grain bulk modulus, and pore uid bulk modulus are already known. Since the resulting system of equations for all the drained constants is linear, measurement error in undrained constants also propagates linearly into the computed drained constants.

  2. Detecting peatland drains with Object Based Image Analysis and Geoeye-1 imagery.

    Science.gov (United States)

    Connolly, J; Holden, N M

    2017-12-01

    Peatlands play an important role in the global carbon cycle. They provide important ecosystem services including carbon sequestration and storage. Drainage disturbs peatland ecosystem services. Mapping drains is difficult and expensive and their spatial extent is, in many cases, unknown. An object based image analysis (OBIA) was performed on a very high resolution satellite image (Geoeye-1) to extract information about drain location and extent on a blanket peatland in Ireland. Two accuracy assessment methods: Error matrix and the completeness, correctness and quality (CCQ) were used to assess the extracted data across the peatland and at several sub sites. The cost of the OBIA method was compared with manual digitisation and field survey. The drain maps were also used to assess the costs relating to blocking drains vs. a business-as-usual scenario and estimating the impact of each on carbon fluxes at the study site. The OBIA method performed well at almost all sites. Almost 500 km of drains were detected within the peatland. In the error matrix method, overall accuracy (OA) of detecting the drains was 94% and the kappa statistic was 0.66. The OA for all sub-areas, except one, was 95-97%. The CCQ was 85%, 85% and 71% respectively. The OBIA method was the most cost effective way to map peatland drains and was at least 55% cheaper than either field survey or manual digitisation, respectively. The extracted drain maps were used constrain the study area CO 2 flux which was 19% smaller than the prescribed Peatland Code value for drained peatlands. The OBIA method used in this study showed that it is possible to accurately extract maps of fine scale peatland drains over large areas in a cost effective manner. The development of methods to map the spatial extent of drains is important as they play a critical role in peatland carbon dynamics. The objective of this study was to extract data on the spatial extent of drains on a blanket bog in the west of Ireland. The

  3. Detecting peatland drains with Object Based Image Analysis and Geoeye-1 imagery

    Directory of Open Access Journals (Sweden)

    J. Connolly

    2017-03-01

    Full Text Available Abstract Background Peatlands play an important role in the global carbon cycle. They provide important ecosystem services including carbon sequestration and storage. Drainage disturbs peatland ecosystem services. Mapping drains is difficult and expensive and their spatial extent is, in many cases, unknown. An object based image analysis (OBIA was performed on a very high resolution satellite image (Geoeye-1 to extract information about drain location and extent on a blanket peatland in Ireland. Two accuracy assessment methods: Error matrix and the completeness, correctness and quality (CCQ were used to assess the extracted data across the peatland and at several sub sites. The cost of the OBIA method was compared with manual digitisation and field survey. The drain maps were also used to assess the costs relating to blocking drains vs. a business-as-usual scenario and estimating the impact of each on carbon fluxes at the study site. Results The OBIA method performed well at almost all sites. Almost 500 km of drains were detected within the peatland. In the error matrix method, overall accuracy (OA of detecting the drains was 94% and the kappa statistic was 0.66. The OA for all sub-areas, except one, was 95–97%. The CCQ was 85%, 85% and 71% respectively. The OBIA method was the most cost effective way to map peatland drains and was at least 55% cheaper than either field survey or manual digitisation, respectively. The extracted drain maps were used constrain the study area CO2 flux which was 19% smaller than the prescribed Peatland Code value for drained peatlands. Conclusions The OBIA method used in this study showed that it is possible to accurately extract maps of fine scale peatland drains over large areas in a cost effective manner. The development of methods to map the spatial extent of drains is important as they play a critical role in peatland carbon dynamics. The objective of this study was to extract data on the spatial extent of

  4. Culturable yeasts in meltwaters draining from two glaciers in the Italian Alps

    Science.gov (United States)

    Buzzini, Pietro; Turchetti, Benedetta; Diolaiuti, Guglielmina; D'Agata, Carlo; Martini, Alessandro; Smiraglia, Claudio

    The meltwaters draining from two glaciers in the Italian Alps contain metabolically active yeasts isolable by culture-based laboratory procedures. The average number of culturable yeast cells in the meltwaters was 10 20 colony-forming units (CFU) L-1, whereas supraglacial stream waters originating from overlying glacier ice contained 80% of isolated strains (Cryptococcus spp. and Rhodotorula spp. were 33.3% and 17.8% of total strains, respectively). Culturable yeasts were psychrotolerant, predominantly obligate aerobes and able to degrade organic macromolecules (e.g. starch, esters, lipids, proteins). To the authors' knowledge, this is the first study to report the presence of culturable yeasts in meltwaters originating from glaciers. On the basis of these results, it is reasonable to suppose that the viable yeasts observed in meltwaters derived predominantly from the subglacial zone and that they originated from the subglacial microbial community. Their metabolic abilities could contribute to the microbial activity occurring in subglacial environments.

  5. Nurses’ Knowledge Levels of Chest Drain Management: A Descriptive Study

    Directory of Open Access Journals (Sweden)

    Merve Tarhan

    2016-12-01

    Full Text Available Objective: The physician is responsible for inserting one or more chest tubes into the pleural space or the mediastinal space and connecting them to an appropriate drainage system. When the general principles about care of patients with chest drains were implemented correctly and effectively by nurses, nurse will contribute to accelerate the healing process of patients. In this context, the aim of this study was to determine the nurses’ level of knowledge regarding the care of patients with chest drains. Methods: The study was conducted with 153 nurses who worked in a chest diseases and thoracic surgery hospital in July 2014. Questionnaire form of 35 questions prepared by investigators was used to collect data. For the analysis of results, frequency tests, independent sample t-test and oneway ANOVA test were used. Results: 69.3% of nurses stated that they had obtained information from colleguages. 35.3% considered their knowledge about chest drain management to be inadequate. 55.6% scored 13 points and above from knowledge questionnaire about chest drain management. There were statistically significant difference between knowledge level and educational background, clinic work type, working unit, years of professional experience and institutional experience, frequency of contact patients with chest drain and perception of knowledge level (p<0.05. Conclusion: Results of this study indicate that lack of evidence-based nursing care and insufficient training has resulted in uncertainty and knowledge deficit in important aspects of chest drain care. It can be concluded that nurses receive training needs and training protocols are about chest drain management.

  6. Controlling the ambipolarity and improvement of RF performance using Gaussian Drain Doped TFET

    Science.gov (United States)

    Nigam, Kaushal; Gupta, Sarthak; Pandey, Sunil; Kondekar, P. N.; Sharma, Dheeraj

    2018-05-01

    Ambipolar conduction in tunnel field-effect transistors (TFETs) has been occurred as an inherent issue due to drain-channel tunneling. It makes TFET less efficient and restricts its application in complementary digital circuits. Therefore, this manuscript reports the application of Gaussian doping profile on nanometer regime silicon channel TFETs to completely eliminate the ambipolarity. For this, Gaussian doping is used in the drain region of conventional gate-drain overlap TFET to control the tunneling of electrons from the valence band of channel to the conduction band of drain. As a result, barrier width at the drain/channel junction increases significantly leading to the suppression of an ambipolar current even when higher doping concentration (1 ? 10 ? cm ?) is considered in the drain region. However, significant improvement in terms of RF figure-of-merits such as cut-off frequency (f ?), gain bandwidth product (GBW), and gate-to-drain capacitance (C ?) is achieved with Gaussian doped gate on drain overlap TFET as compared to its counterpart TFET.

  7. Coal-tar-based sealcoated pavement: A major PAH source to urban stream sediments

    International Nuclear Information System (INIS)

    Witter, Amy E.; Nguyen, Minh H.; Baidar, Sunil; Sak, Peter B.

    2014-01-01

    We used land-use analysis, PAH concentrations and assemblages, and multivariate statistics to identify sediment PAH sources in a small (∼1303 km 2 ) urbanizing watershed located in South-Central, Pennsylvania, USA. A geographic information system (GIS) was employed to quantify land-use features that may serve as PAH sources. Urban PAH concentrations were three times higher than rural levels, and were significantly and highly correlated with combined residential/commercial/industrial land use. Principal components analysis (PCA) was used to group sediments with similar PAH assemblages, and correlation analysis compared PAH sediment assemblages to common PAH sources. The strongest correlations were observed between rural sediments (n = 7) and coke-oven emissions sources (r = 0.69–0.78, n = 5), and between urban sediments (n = 22) and coal-tar-based sealcoat dust (r = 0.94, n = 47) suggesting that coal-tar-based sealcoat is an important urban PAH source in this watershed linked to residential and commercial/industrial land use. -- Highlights: • Total PAH concentrations were measured at 35 sites along an urbanizing land-use gradient. • PAH concentrations increased with increasing urban land-use. • Urban land-use metrics were measured at three spatial scales using GIS. • PAH assemblages indicate coal-tar-based sealcoat is a major urban PAH source. • PAH assemblages indicate coke-oven emissions are an important rural PAH source. -- Coal-tar-based sealcoated pavement is a major PAH source to urban freshwater stream sediments in south-central Pennsylvania, USA

  8. MEDICAL BRAIN DRAIN - A THEORETICAL APPROACH

    Directory of Open Access Journals (Sweden)

    Boncea Irina

    2013-07-01

    Full Text Available Medical brain drain is defined as the migration of health personnel from developing countries to developed countries and between industrialized nations in search for better opportunities. This phenomenon became a global growing concern due to its impact on both the donor and the destination countries. This article aims to present the main theoretical contributions starting from 1950 until today and the historical evolution, in the attempt of correlating the particular case of medical brain drain with the theory and evolution of the brain drain in general. This article raises questions and offers answers, identifies the main issues and looks for possible solutions in order to reduce the emigration of medical doctors. Factors of influence include push (low level of income, poor working conditions, the absence of job openings and social recognition, oppressive political climate and pull (better remuneration and working conditions, prospects for career development, job satisfaction, security factors. Developing countries are confronting with the loss of their most valuable intellectuals and the investment in their education, at the benefit of developed nations. An ethical debate arises as the disparities between countries increases, industrialized nations filling in the gaps in health systems with professionals from countries already facing shortages. However, recent literature emphasizes the possibility of a “beneficial brain drain” through education incentives offered by the emigration prospects. Other sources of “brain gain” for donor country are the remittances, the scientific networks and return migration. Measures to stem the medical brain drain involve the common effort and collaboration between developing and developed countries and international organizations. Measures adopted by donor countries include higher salaries, better working conditions, security, career opportunities, incentives to stimulate return migration. Destination

  9. Implications of 36Cl exposure ages from Skye, northwest Scotland for the timing of ice stream deglaciation and deglacial ice dynamics

    Science.gov (United States)

    Small, David; Rinterknecht, Vincent; Austin, William E. N.; Bates, Richard; Benn, Douglas I.; Scourse, James D.; Bourlès, Didier L.; Hibbert, Fiona D.

    2016-10-01

    Geochronological constraints on the deglaciation of former marine based ice streams provide information on the rates and modes by which marine based ice sheets have responded to external forcing factors such as climate change. This paper presents new 36Cl cosmic ray exposure dating from boulders located on two moraines (Glen Brittle and Loch Scavaig) in southern Skye, northwest Scotland. Ages from the Glen Brittle moraines constrain deglaciation of a major marine terminating ice stream, the Barra-Donegal Ice Stream that drained the former British-Irish Ice Sheet, depending on choice of production method and scaling model this occurred 19.9 ± 1.5-17.6 ± 1.3 ka ago. We compare this timing of deglaciation to existing geochronological data and changes in a variety of potential forcing factors constrained through proxy records and numerical models to determine what deglaciation age is most consistent with existing evidence. Another small section of moraine, the Scavaig moraine, is traced offshore through multibeam swath-bathymetry and interpreted as delimiting a later stillstand/readvance stage following ice stream deglaciation. Additional cosmic ray exposure dating from the onshore portion of this moraine indicate that it was deposited 16.3 ± 1.3-15.2 ± 0.9 ka ago. When calculated using the most up-to-date scaling scheme this time of deposition is, within uncertainty, the same as the timing of a widely identified readvance, the Wester Ross Readvance, observed elsewhere in northwest Scotland. This extends the area over which this readvance has potentially occurred, reinforcing the view that it was climatically forced.

  10. Brain drain: Propulsive factors and consequences

    Directory of Open Access Journals (Sweden)

    Dragan ILIC

    2018-01-01

    Full Text Available When speaking about the total number of highly educated individuals’ migration, it is easy to spot that it is rapidly increasing. The brain drain issues should be taken very seriously especially in under developed and in the developing countries, knowing that the human capital is globally mobile and that highly educated individuals can without any issues market their knowledge around the globe. Dealing with it requires a carefully tailored strategy for these countries, which are suffering from severe human capital losses on annual basis. Since the labor markets of today are highly competitive, it is necessary for these countries to secure good advancement and doing business opportunities. The purpose of this research is to provide an insight into the key propulsive factors and potential consequences caused by the brain drain. The method used in order to conduct the research was a carefully designed questionnaire taken by the date subject enrolled at the third and fourth years of state governed and privately owned universities. This research shows that one of the key reasons for brain drain in underdeveloped and in the developing countries is shortage of further educational advancement opportunities.

  11. Stream network responses to evapotranspiration in mountain systems: evidence from spatially-distributed network mapping and sapflow measurements

    Science.gov (United States)

    Godsey, S.; Whiting, J. A.; Reinhardt, K.

    2015-12-01

    Stream networks respond to decreased inputs by shrinking from their headwaters and disconnecting along their length. Both the relative stability of the stream network and the degree of disconnection along the network length can strongly affect stream ecology, including fish migration and nutrient spiraling. Previous data suggests that stream network lengths decrease measurably as discharge decreases, and that evapotranspiration may be an important control on stream network persistence. We hypothesized that changes in sapflow timing and magnitude across a gradient from rain-dominated to snow-dominated elevations would be reflected in the stability of the stream network in a steep watershed draining to the Middle Fork Salmon in central Idaho. We expected that the relative timing of water availability across the gradient would drive differences in water delivery to both trees and the stream network. Here we present results that highlight the stability of sapflow timing across the gradient and persistence of the stream network at this site. We discuss geologic controls on network stability and present a conceptual framework identifying characteristics of stable flowheads. We test this framework at four sites in central Idaho with mapped stream networks. We also discuss late summer sapflow patterns across the elevation gradient and their linkages to soil and atmospheric characteristics. Finally, we compare these patterns to those observed at other sites and discuss the role of vegetation in controlling spatiotemporal patterns across the stream network.

  12. Spatial and temporal distribution of mosquitoes in underground storm drain systems in Orange County, California.

    Science.gov (United States)

    Su, Tianyun; Webb, James P; Meyer, Richard P; Mulla, Mir S

    2003-06-01

    Underground storm drain systems in urban areas of Orange County include thousands of miles of gutters and underground pipelines, plus hundreds of thousands of catch basins and manhole chambers, all of which drain runoff water from residential, business and commercial establishments as well as highways and streets. These systems serve as major developmental and resting sites for anthropophilic and zoophilic mosquitoes. Investigations on spatial and temporal distribution of mosquitoes in these systems were conducted during November 1999 to October 2001. Immature mosquitoes were sampled by dipper or dipping net and adult mosquitoes by non-attractive CDC traps in manhole chambers, catch basins and a large drain. Culex quinquefasciatus Say prevailed at all 15 structures of the study in 4 cities of Orange County as the predominant species (> 99.9%). Larvae and pupae were present from April to October, peaking from May to September. The population density of adults was the lowest in February with 2 peaks of abundance occurring from May to July and from September to October. Manhole chambers and catch basins harbored more mosquitoes than did the large drain. Minimum and maximum temperatures during a 24 h sampling period was an important factor influencing adult mosquito activity and catches; more mosquitoes were caught in traps when it was warmer, especially when the minimum temperatures were higher. The proportion of females to males in general increased during winter and early spring an ddeclined during summer. The proportion of gravid females to empty females was higher during the winter than in summer. Other dipteran taxa such as psychodid moth flies and chironomid midges exhibited somewhat similar seasonal patterns as did mosquito populations. Average water temperature was relatively stable throughout the year, and water quality in underground drain systems was characterized by low dissolved oxygen, coupled with above normal electrical conductivity and salinity levels

  13. Drain Tube-Induced Jejunal Penetration Masquerading as Bile Leak following Whipple's Operation.

    Science.gov (United States)

    Bae, Sang Ho; Lee, Tae Hoon; Lee, Sae Hwan; Lee, Suck-Ho; Park, Sang-Heum; Kim, Sun-Joo; Kim, Chang Ho

    2011-05-01

    A 70-year-old man had undergone pancreaticoduodenectomy due to a distal common bile duct malignancy. After the operation, serous fluid discharge decreased from two drain tubes in the retroperitoneum. Over four weeks, the appearance of the serous fluid changed to a greenish bile color and the patient persistently drained over 300 ml/day. Viewed as bile leak at the choledochojejunostomy, treatment called for endoscopic diagnosis and therapy. Cap-fitted forward-viewing endoscopy demonstrated that the distal tip of a pancreatic drain catheter inserted at the pancreaticojejunostomy site had penetrated the opposite jejunum wall. One of the drain tubes primarily placed in the retroperitoneum had also penetrated the jejunum wall, with the distal tip positioned near the choledochojejunostomy site. No leak of contrast appeared beyond the jejunum or anastomosis site. Following repositioning of a penetrating catheter of the pancreaticojejunostomy, four days later, the patient underwent removal of two drain tubes without additional complications. In conclusion, the distal tip of the catheter, placed to drain pancreatic juice, penetrated the jejunum wall and may have caused localized perijejunal inflammation. The other drain tube, placed in the retroperitoneal space, might then have penetrated the inflamed wall of the jejunum, allowing persistent bile drainage via the drain tube. The results masqueraded as bile leakage following pancreaticoduodenectomy.

  14. Experimental acidification of two biogeochemically-distinct neotropical streams: Buffering mechanisms and macroinvertebrate drift

    International Nuclear Information System (INIS)

    Ardón, Marcelo; Duff, John H.; Ramírez, Alonso; Small, Gaston E.; Jackman, Alan P.; Triska, Frank J.; Pringle, Catherine M.

    2013-01-01

    Research into the buffering mechanisms and ecological consequences of acidification in tropical streams is lacking. We have documented seasonal and episodic acidification events in streams draining La Selva Biological Station, Costa Rica. Across this forested landscape, the severity in seasonal and episodic acidification events varies due to interbasin groundwater flow (IGF). Streams that receive IGF have higher concentrations of solutes and more stable pH (∼ 6) than streams that do not receive IGF (pH ∼ 5). To examine the buffering capacity and vulnerability of macroinvertebrates to short-term acidification events, we added hydrochloric acid to acidify a low-solute, poorly buffered (without IGF) and a high-solute, well buffered stream (with IGF). We hypothesized that: 1) protonation of bicarbonate (HCO 3 − ) would neutralize most of the acid added in the high-solute stream, while base cation release from the sediments would be the most important buffering mechanism in the low-solute stream; 2) pH declines would mobilize inorganic aluminum (Ali) from sediments in both streams; and 3) pH declines would increase macroinvertebrate drift in both streams. We found that the high-solute stream neutralized 745 μeq/L (96% of the acid added), while the solute poor stream only neutralized 27.4 μeq/L (40%). Protonation of HCO 3 − was an important buffering mechanism in both streams. Base cation, Fe 2+ , and Ali release from sediments and protonation of organic acids also provided buffering in the low-solute stream. We measured low concentrations of Ali release in both streams (2-9 μeq/L) in response to acidification, but the low-solute stream released double the amount Ali per 100 μeq of acid added than the high solute stream. Macroinvertebrate drift increased in both streams in response to acidification and was dominated by Ephemeroptera and Chironomidae. Our results elucidate the different buffering mechanisms in tropical streams and suggest that low

  15. Concentration-Discharge Behavior of Contaminants in a Stream Impacted by Acid Mine Drainage

    Science.gov (United States)

    Shaw, M. E.; Klein, M.; Herndon, E.

    2017-12-01

    Acid mine drainage (AMD) has severely degraded streams throughout the Appalachian coal region of the United States. AMD occurs when pyrite contained in coal is exposed to water and air during mining activities and oxidized to release high concentrations of sulfate, metals, and acidity into water bodies. Little is known about the concentration-discharge (CQ) relationships of solutes in AMD-impacted streams due to the complicated nature of acid mine drainage systems. For example, streams may receive inputs from multiple sources that include runoff, constructed treatment systems, and abandoned mines that bypass these systems to continue to contaminate the streams. It is important to understand the CQ relationships of contaminants in AMD-impacted streams in order to elucidate contaminant sources and to predict effects on aquatic ecosystems. Here, we study the CQ behaviors of acid and metals in a contaminated watershed in northeastern Ohio where limestone channels have been installed to remediate water draining from a mine pool into the stream. Stream chemistry was measured in samples collected once per day or once per hour during storm events, and stream flow was measured continuously at the watershed outlet. Increases in stream velocity during storm events resulted in an increase in pH (from 3 to 6) that subsequently decreased back to 3 as flow decreased. Additionally, Fe and Mn concentrations in the stream were high during baseflow (7 and 15 mg/L, respectively) and decreased with increasing discharge during storm events. These results indicate that the treatment system is only effective at neutralizing stream acidity and removing metals when water flow through the limestone channel is continuous. We infer that the acidic and metal-rich baseflow derives from upwelling of contaminated groundwater or subsurface flow from a mine pool. Ongoing studies aim to isolate the source of this baseflow contamination and evaluate the geochemical transformations that occur as it

  16. Hydrogeochemical and stream sediment sampling for uranium in the sandstone environment

    International Nuclear Information System (INIS)

    Wenrich, K.J.

    1985-01-01

    Sandstone terranes commonly host uranium occurrences in the western United States. In addition, because sedimentary terranes, particularly shales and immature, not well cemented sandstone, contribute more sediment and soluble material than do plutonic, volcanic, or metamorphic terranes they are an excellent regime for hydrogeochemical and stream-sediment prospecting. Because of higher conductivity, and hence higher uranium content, of waters draining such environments the sampling need not be as precise nor the analytical detection limit as low as in other terranes to yield a successful survey. Nevertheless, reasonable preparation and care of the samples is recommended: (1) The water samples should be filtered through 0.45 μm membranes and acidified to a pH of less than 1. (2) Because the adsorption of uranium by organic material is so significant it is recommended that the reasonable finest stream-sediment fraction, 4 , conductivity, etc.) are useful in the data reduction towards the elimination of false anomalies. (author)

  17. Carbon and nitrogen stoichiometry across stream ecosystems

    Science.gov (United States)

    Wymore, A.; Kaushal, S.; McDowell, W. H.; Kortelainen, P.; Bernhardt, E. S.; Johnes, P.; Dodds, W. K.; Johnson, S.; Brookshire, J.; Spencer, R.; Rodriguez-Cardona, B.; Helton, A. M.; Barnes, R.; Argerich, A.; Haq, S.; Sullivan, P. L.; López-Lloreda, C.; Coble, A. A.; Daley, M.

    2017-12-01

    Anthropogenic activities are altering carbon and nitrogen concentrations in surface waters globally. The stoichiometry of carbon and nitrogen regulates important watershed biogeochemical cycles; however, controls on carbon and nitrogen ratios in aquatic environments are poorly understood. Here we use a multi-biome and global dataset (tropics to Arctic) of stream water chemistry to assess relationships between dissolved organic carbon (DOC) and nitrate, ammonium and dissolved organic nitrogen (DON), providing a new conceptual framework to consider interactions between DOC and the multiple forms of dissolved nitrogen. We found that across streams the total dissolved nitrogen (TDN) pool is comprised of very little ammonium and as DOC concentrations increase the TDN pool shifts from nitrate to DON dominated. This suggests that in high DOC systems, DON serves as the primary source of nitrogen. At the global scale, DOC and DON are positively correlated (r2 = 0.67) and the average C: N ratio of dissolved organic matter (molar ratio of DOC: DON) across our data set is approximately 31. At the biome and smaller regional scale the relationship between DOC and DON is highly variable (r2 = 0.07 - 0.56) with the strongest relationships found in streams draining the mixed temperate forests of the northeastern United States. DOC: DON relationships also display spatial and temporal variability including latitudinal and seasonal trends, and interactions with land-use. DOC: DON ratios correlated positively with gradients of energy versus nutrient limitation pointing to the ecological role (energy source versus nutrient source) that DON plays with stream ecosystems. Contrary to previous findings we found consistently weak relationships between DON and nitrate which may reflect DON's duality as an energy or nutrient source. Collectively these analyses demonstrate how gradients of DOC drive compositional changes in the TDN pool and reveal a high degree of variability in the C: N ratio

  18. Steam generator fitted with a dynamic draining device

    International Nuclear Information System (INIS)

    Chaix, J.E.

    1982-01-01

    This generator has, at its upper part, at least one drying structure for holding the water carried with the steam and communicating at its lower part with at least one discharge pipe for draining off the water, each pipe communicating with a dynamic draining device capable of creating a depression in order to suck up the water contained in the drying structure. Application is for pressurized water nuclear reactors [fr

  19. Numerical Simulation of Liquids Draining From a Tank Using OpenFOAM

    Science.gov (United States)

    Sakri, Fadhilah Mohd; Sukri Mat Ali, Mohamed; Zaki Shaikh Salim, Sheikh Ahmad; Muhamad, Sallehuddin

    2017-08-01

    Accurate simulation of liquids draining is a challenging task. It involves two phases flow, i.e. liquid and air. In this study draining a liquid from a cylindrical tank is numerically simulated using OpenFOAM. OpenFOAM is an open source CFD package and it becomes increasingly popular among the academician and also industries. Comparisons with theoretical and results from previous published data confirmed that OpenFOAM is able to simulate the liquids draining very well. This is done using the gas-liquid interface solver available in the standard library of OpenFOAM. Additionally, this study was also able to explain the physics flow of the draining tank.

  20. Closed suction drain with bulb

    Science.gov (United States)

    ... of gloves. Put a new bandage around the drain tube site. Use surgical tape to hold it down ... small amount of redness is normal). There is drainage from the skin around the tube site. There is more tenderness and swelling at ...

  1. BLOSTREAM: A HIGH SPEED STREAM CIPHER

    Directory of Open Access Journals (Sweden)

    ALI H. KASHMAR

    2017-04-01

    Full Text Available Although stream ciphers are widely utilized to encrypt sensitive data at fast speeds, security concerns have led to a shift from stream to block ciphers, judging that the current technology in stream cipher is inferior to the technology of block ciphers. This paper presents the design of an improved efficient and secure stream cipher called Blostream, which is more secure than conventional stream ciphers that use XOR for mixing. The proposed cipher comprises two major components: the Pseudo Random Number Generator (PRNG using the Rabbit algorithm and a nonlinear invertible round function (combiner for encryption and decryption. We evaluate its performance in terms of implementation and security, presenting advantages and disadvantages, comparison of the proposed cipher with similar systems and a statistical test for randomness. The analysis shows that the proposed cipher is more efficient, high speed, and secure than current conventional stream ciphers.

  2. Agricultural herbicide transport in a first-order intermittent stream, Nebraska, USA

    Science.gov (United States)

    Vogel, J.R.; Linard, J.I.

    2011-01-01

    The behavior of herbicides in surface waters is a function of many variables, including scale of the watershed, physical and chemical properties of the herbicide, physical and chemical properties of the soil, rainfall intensity, and time of year. In this study, the transport of 6 herbicides and 12 herbicide degradates was examined during the 2004 growing season in an intermediate-scale agricultural watershed (146 ha) that is drained by a first-order intermittent stream, and the mass load for each herbicide in the stream was estimated. The herbicide load during the first week of storm events after application ranged from 17% of annual load for trifluralin to 84% of annual load for acetochlor. The maximum weekly herbicide load in the stream was generally within the first 3 weeks after application for those compounds that were applied within the watershed during 2004, and later for herbicides not applied within the watershed during 2004 but still detected in the stream. The apparent dominant mode of herbicide transport in the stream-determined by analysis amongst herbicide and conservative ion concentrations at different points in the hydrograph and in base flow samples-was either overland runoff or shallow subsurface flow, depending on the elapsed time after application and type of herbicide. The load as a percentage of use (LAPU) for the parent compounds in this study was similar to literature values for those compounds applied by the farmer within the watershed, but smaller for those herbicides that had rainfall as their only source within the watershed.

  3. Physical characterization of a watershed through GIS: a study in the Schmidt stream, Brazil.

    Science.gov (United States)

    Reis, D R; Plangg, R; Tundisi, J G; Quevedo, D M

    2015-12-01

    Remote sensing and geoprocessing are essential tools for obtaining and maintaining records of human actions on space over the course of time; these tools offer the basis for diagnoses of land use, environmental interference and local development. The Schmidt stream watershed, located in the Sinos River basin, in southern Brazil, has an environmental situation similar to that of the majority of small streams draining rural and urban areas in southern Brazil: agricultural and urbanization practices do not recognize the riparian area and there is removal of original vegetation, disregarding the suitability of land use; removal of wetlands; intensive water use for various activities; and lack of control and monitoring in the discharge of wastewater, among other factors, deteriorate the quality of this important environment.This article aims to achieve a physical characterization of the Schmidt stream watershed (Sinos river basin) identifying elements such as land use and occupation, soil science, geology, climatology, extent and location of watershed, among others, so as to serve as the basis for a tool that helps in the integrated environmental management of watersheds. By applying geographic information system - GIS to the process of obtaining maps of land use and occupation, pedologicaland geological, and using climatological data from the Campo Bom meteorological station, field visit, review of literature and journals, and publicly available data, the physical characterization of the Schmidt stream watershed was performed, with a view to the integrated environmental management of this watershed. Out of the total area of the Schmidt stream watershed (23.92 km(2)), in terms of geology, it was observed that 23.7% consist of colluvial deposits, 22.6% consist of grass facies, and 53.7% consist of Botucatu formation. Major soil types of the watershed: 97.4% Argisols and only 2.6% Planosols. Land use and occupation is characterized by wetland (0.5%), Native Forest (12

  4. Predicting artificailly drained areas by means of selective model ensemble

    DEFF Research Database (Denmark)

    Møller, Anders Bjørn; Beucher, Amélie; Iversen, Bo Vangsø

    . The approaches employed include decision trees, discriminant analysis, regression models, neural networks and support vector machines amongst others. Several models are trained with each method, using variously the original soil covariates and principal components of the covariates. With a large ensemble...... out since the mid-19th century, and it has been estimated that half of the cultivated area is artificially drained (Olesen, 2009). A number of machine learning approaches can be used to predict artificially drained areas in geographic space. However, instead of choosing the most accurate model....... The study aims firstly to train a large number of models to predict the extent of artificially drained areas using various machine learning approaches. Secondly, the study will develop a method for selecting the models, which give a good prediction of artificially drained areas, when used in conjunction...

  5. The Simple Urine Bag as Wound Drain Post-Craniotomy in a Low ...

    African Journals Online (AJOL)

    Methods: A 4-year prospective cohort study of the effectiveness, outcome with use and complications of the Uribag as post craniotomy wound drain in a consecutive cohort of neurosurgical patients. Data analyzed include the patients' brief demographics; the types of cranial surgery in which drain was used; the drain ...

  6. Frequency dependence and passive drains in fish-eye lenses

    Science.gov (United States)

    Quevedo-Teruel, O.; Mitchell-Thomas, R. C.; Hao, Y.

    2012-11-01

    The Maxwell fish eye lens has previously been reported as being capable of the much sought after phenomenon of subwavelength imaging. The inclusion of a drain in this system is considered crucial to the imaging ability, although its role is the topic of much debate. This paper provides a numerical investigation into a practical implementation of a drain in such systems, and analyzes the strong frequency dependence of both the Maxwell fish eye lens and an alternative, the Miñano lens. The imaging capability of these types of lens is questioned, and it is supported by simulations involving various configurations of drain arrays. Finally, a discussion of the near-field and evanescent wave contribution is given.

  7. Shearon Harris steam generator channel head drain line leakage

    International Nuclear Information System (INIS)

    Bauer, P.A.

    1992-01-01

    All three Shearon Harris steam generators were equipped with Inconel 600 drain penetrations inserted into clearance holes on the bottom center line of the plenums, roll expanded into the plenum shell, and seal welded to the stainless steel cladding. Eddy current inspections showed axial cracks in the drain lines of B and C generators, but not on the leaking A generator. The drain lines of the three generators were repaired by cutting off the pipe under the plenum, applying Inconel 600 cladding to the underside of the plenum by a temper bead process, spot facing the overlay cladding and welding a new Inconel 600 pipe coupling to the clad surface. 3 figs

  8. Intra-articular injection of tranexamic acid via a drain plus drain-clamping to reduce blood loss in cementless total knee arthroplasty

    Directory of Open Access Journals (Sweden)

    Mutsuzaki Hirotaka

    2012-09-01

    Full Text Available Abstract Background Patients undergoing cementless total knee arthroplasty (TKA sometimes suffer large blood loss. In a retrospective study, we explored whether postoperative intra-articular retrograde injection of tranexamic acid (TA and leaving a drain clamp in place for 1 h reduced blood loss. Patients and methods Patients (n = 140 treated with unilateral primary cementless TKA (posterior cruciate ligament retained were divided into two groups: those who had an intra-articular injection of TA (1000 mg and drain clamping for 1 h postoperatively (study group, n = 70 and those who were not given TA and did not undergo clamping of their drains (control group, n = 70. Postoperative total blood loss, volume of drainage, hemoglobin level, transfusion amounts and rates, D-dimer level at postoperative day (POD 7, and complications were recorded. Results Total blood loss, total drainage, mean transfusion volume, and transfusion rates were lower in the study group than in controls (P P P  Conclusions Immediately postoperative intra-articular retrograde injection of TA and 1 h of drain-clamping effectively reduced blood loss and blood transfusion after cementless TKA. We believe that this method is simple, easy, and suitable for these patients.

  9. Comparative Evaluation of Immediate Post-Operative Sequelae after Surgical Removal of Impacted Mandibular Third Molar with or without Tube Drain - Split-Mouth Study.

    Science.gov (United States)

    Kumar, Barun; Bhate, Kalyani; Dolas, R S; Kumar, Sn Santhosh; Waknis, Pushkar

    2016-12-01

    Third molar surgery is one of the most common surgical procedures performed in general dentistry. Post-operative variables such as pain, swelling and trismus are major concerns after impacted mandibular third molar surgery. Use of passive tube drain is supposed to help reduce these immediate post-operative sequelae. The current study was designed to compare the effect of tube drain on immediate post-operative sequelae following impacted mandibular third molar surgery. To compare the post-operative sequelae after surgical removal of impacted mandibular third molar surgery with or without tube drain. Thirty patients with bilateral impacted mandibular third molars were divided into two groups: Test (with tube drain) and control (without tube drain) group. In the test group, a tube drain was inserted through the releasing incision, and kept in place for three days. The control group was left without a tube drain. The post-operative variables like, pain, swelling, and trismus were calculated after 24 hours, 72 hours, 7 days, and 15 days in both the groups and analyzed statistically using chi-square and t-test analysis. The test group showed lesser swelling as compared to control group, with the swelling variable showing statistically significant difference at post-operative day 3 and 7 (p≤ 0.05) in both groups. There were no statistically significant differences in pain and trismus variables in both the groups. The use of tube drain helps to control swelling following impacted mandibular third molar surgery. However, it does not have much effect on pain or trismus.

  10. A stream sediment orientation programme for Uranium in the Alligator River Province, Northern Territory, Australia

    International Nuclear Information System (INIS)

    Gingrich, J.E.; Foy, M.F.

    1977-01-01

    Sediments samples were collected from streams draining the Koongarra uranium deposit and the small uranium mines in the South Alligator Valley. Determinations for U, Cu and Pb on various size fractions taken from each of these samples indicated that the best results were obtained for U from the minus 200-mesh fraction, but the train from the Koongarra ore deposit was very short. Cu and Pb were not found to be very useful as indicator elements for U. Alpha-track films were used to determine the Rn content of each sample and the ratio of alpha-track film reading to U content was found to define anomalous drainage areas around the mineralization in the Koongarra area. The areas so defined were of sufficient magnitude to be defined in a reconnaissance stream sediment programme

  11. A mathematical model to optimize the drain phase in gravity-based peritoneal dialysis systems.

    Science.gov (United States)

    Akonur, Alp; Lo, Ying-Cheng; Cizman, Borut

    2010-01-01

    Use of patient-specific drain-phase parameters has previously been suggested to improve peritoneal dialysis (PD) adequacy. Improving management of the drain period may also help to minimize intraperitoneal volume (IPV). A typical gravity-based drain profile consists of a relatively constant initial fast-flow period, followed by a transition period and a decaying slow-flow period. That profile was modeled using the equation VD(t) = (V(D0) - Q(MAX) x t) xphi + (V(D0) x e(-alphat)) x (1 - phi), where V(D)(t) is the time-dependent dialysate volume; V(D0), the dialysate volume at the start of the drain; Q(MAX), the maximum drain flow rate; alpha, the exponential drain constant; and phi, the unit step function with respect to the flow transition. We simulated the effects of the assumed patient-specific maximum drain flow (Q(MAX)) and transition volume (psi), and the peritoneal volume percentage when transition occurs,for fixed device-specific drain parameters. Average patient transport parameters were assumed during 5-exchange therapy with 10 L of PD solution. Changes in therapy performance strongly depended on the drain parameters. Comparing 400 mL/85% with 200 mL/65% (Q(MAX/psi), drain time (7.5 min vs. 13.5 min) and IPV (2769 mL vs. 2355 mL) increased when the initial drain flow was low and the transition quick. Ultrafiltration and solute clearances remained relatively similar. Such differences were augmented up to a drain time of 22 minutes and an IPV of more than 3 L when Q(MAX) was 100 mL/min. The ability to model individual drain conditions together with water and solute transport may help to prevent patient discomfort with gravity-based PD. However, it is essential to note that practical difficulties such as displaced catheters and obstructed flow paths cause variability in drain characteristics even for the same patient, limiting the clinical applicability of this model.

  12. N loss to drain flow and N2O emissions from a corn-soybean rotation with winter rye.

    Science.gov (United States)

    Gillette, K; Malone, R W; Kaspar, T C; Ma, L; Parkin, T B; Jaynes, D B; Fang, Q X; Hatfield, J L; Feyereisen, G W; Kersebaum, K C

    2018-03-15

    Anthropogenic perturbation of the global nitrogen cycle and its effects on the environment such as hypoxia in coastal regions and increased N 2 O emissions is of increasing, multi-disciplinary, worldwide concern, and agricultural production is a major contributor. Only limited studies, however, have simultaneously investigated NO 3 - losses to subsurface drain flow and N 2 O emissions under corn-soybean production. We used the Root Zone Water Quality Model (RZWQM) to evaluate NO 3 - losses to drain flow and N 2 O emissions in a corn-soybean system with a winter rye cover crop (CC) in central Iowa over a nine year period. The observed and simulated average drain flow N concentration reductions from CC were 60% and 54% compared to the no cover crop system (NCC). Average annual April through October cumulative observed and simulated N 2 O emissions (2004-2010) were 6.7 and 6.0kgN 2 O-Nha -1 yr -1 for NCC, and 6.2 and 7.2kgNha -1 for CC. In contrast to previous research, monthly N 2 O emissions were generally greatest when N loss to leaching were greatest, mostly because relatively high rainfall occurred during the months fertilizer was applied. N 2 O emission factors of 0.032 and 0.041 were estimated for NCC and CC using the tested model, which are similar to field results in the region. A local sensitivity analysis suggests that lower soil field capacity affects RZWQM simulations, which includes increased drain flow nitrate concentrations, increased N mineralization, and reduced soil water content. The results suggest that 1) RZWQM is a promising tool to estimate N 2 O emissions from subsurface drained corn-soybean rotations and to estimate the relative effects of a winter rye cover crop over a nine year period on nitrate loss to drain flow and 2) soil field capacity is an important parameter to model N mineralization and N loss to drain flow. Published by Elsevier B.V.

  13. Drain Back Systems in Laboratory and in Practice

    DEFF Research Database (Denmark)

    Perers, Bengt; Furbo, Simon; Fan, Jianhua

    2015-01-01

    in the collector loop to have a safe reliable operation. The components should also be designed and marked so that only one correct mounting option is possible, like forward and return pipes to/from the collector of slightly different sizes or color. Adapted installer education and training is a very important...... step to have success with drain back systems. Practices used in glycol systems may give serious failures. Key-words: Drain Back, Low Flow, Solar Combi System, ETC collectors....

  14. Drain Tube-Induced Jejunal Penetration Masquerading as Bile Leak following Whipple’s Operation

    Directory of Open Access Journals (Sweden)

    Sang Ho Bae

    2011-05-01

    Full Text Available A 70-year-old man had undergone pancreaticoduodenectomy due to a distal common bile duct malignancy. After the operation, serous fluid discharge decreased from two drain tubes in the retroperitoneum. Over four weeks, the appearance of the serous fluid changed to a greenish bile color and the patient persistently drained over 300 ml/day. Viewed as bile leak at the choledochojejunostomy, treatment called for endoscopic diagnosis and therapy. Cap-fitted forward-viewing endoscopy demonstrated that the distal tip of a pancreatic drain catheter inserted at the pancreaticojejunostomy site had penetrated the opposite jejunum wall. One of the drain tubes primarily placed in the retroperitoneum had also penetrated the jejunum wall, with the distal tip positioned near the choledochojejunostomy site. No leak of contrast appeared beyond the jejunum or anastomosis site. Following repositioning of a penetrating catheter of the pancreaticojejunostomy, four days later, the patient underwent removal of two drain tubes without additional complications. In conclusion, the distal tip of the catheter, placed to drain pancreatic juice, penetrated the jejunum wall and may have caused localized perijejunal inflammation. The other drain tube, placed in the retroperitoneal space, might then have penetrated the inflamed wall of the jejunum, allowing persistent bile drainage via the drain tube. The results masqueraded as bile leakage following pancreaticoduodenectomy.

  15. Perioperative lumbar drain utilization in transsphenoidal pituitary resection.

    Science.gov (United States)

    Alharbi, Shatha; Harsh, Griffith; Ajlan, Abdulrazag

    2018-01-01

    To evaluate lumbar drain (LD) efficacy in transnasal resection of pituitary macroadenomas in preventing postoperative cerebrospinal fluid (CSF) leak, technique safety, and effect on length of hospital stay. We conducted a retrospective data review of pituitary tumor patients in our institution who underwent surgery between December 2006 and January 2013. All patients were operated on for complete surgical resection of pituitary macroadenoma tumors. Patients were divided into 2 groups: group 1 received a preoperative drain, while LD was not preoperatively inserted in group 2. In cases of tumors with suprasellar extension with anticipation of high-flow leak, LD was inserted after the patient was intubated and in a lateral position. Lumbar drain was used for 48 hours, and the drain was removed if no leak was observed postoperatively. In documented postoperative CSF leak patients with no preoperative drain, the leak was treated by LD trial prior to surgical reconstruction. Cases in which leak occurred 6 months postoperatively were excluded. Our study population consisted of 186 patients, 99 women (53%) and 87 men (47%), with a mean age of 50.3+/-16.1 years. Complications occurred in 7 patients (13.7%) in group 1 versus 21 (15.5%) in group 2 (p=0.72). Postoperative CSF leak was observed in 1 patient (1.9%) in group 1 and 7 (5%) in group 2 (Fisher exact test=0.3). Length of hospital stay was a mean of 4.7+/-1.9 days in group 1 and a mean of 2.7+/-2.4 days in group 2 (pLD insertion is generally considered safe with a low risk of complications, it increases the length of hospitalization. Minor complications include headaches and patient discomfort.

  16. A method to assess longitudinal riverine connectivity in tropical streams dominated by migratory biota

    Science.gov (United States)

    Crook, K.E.; Pringle, C.M.; Freeman, Mary C.

    2009-01-01

    1. One way in which dams affect ecosystem function is by altering the distribution and abundance of aquatic species. 2. Previous studies indicate that migratory shrimps have significant effects on ecosystem processes in Puerto Rican streams, but are vulnerable to impediments to upstream or downstream passage, such as dams and associated water intakes where stream water is withdrawn for human water supplies. Ecological effects of dams and water withdrawals from streams depend on spatial context and temporal variability of flow in relation to the amount of water withdrawn. 3. This paper presents a conceptual model for estimating the probability that an individual shrimp is able to migrate from a stream's headwaters to the estuary as a larva, and then return to the headwaters as a juvenile, given a set of dams and water withdrawals in the stream network. The model is applied to flow and withdrawal data for a set of dams and water withdrawals in the Caribbean National Forest (CNF) in Puerto Rico. 4. The index of longitudinal riverine connectivity (ILRC), is used to classify 17 water intakes in streams draining the CNF as having low, moderate, or high connectivity in terms of shrimp migration in both directions. An in-depth comparison of two streams showed that the stream characterized by higher water withdrawal had low connectivity, even during wet periods. Severity of effects is illustrated by a drought year, where the most downstream intake caused 100% larval shrimp mortality 78% of the year. 5. The ranking system provided by the index can be used as a tool for conservation ecologists and water resource managers to evaluate the relative vulnerability of migratory biota in streams, across different scales (reach-network), to seasonally low flows and extended drought. This information can be used to help evaluate the environmental tradeoffs of future water withdrawals. ?? 2008 John Wiley & Sons, Ltd.

  17. Mixing zone and drinking water intake dilution factor and wastewater generation distributions to enable probabilistic assessment of down-the-drain consumer product chemicals in the U.S.

    Science.gov (United States)

    Kapo, Katherine E; McDonough, Kathleen; Federle, Thomas; Dyer, Scott; Vamshi, Raghu

    2015-06-15

    Environmental exposure and associated ecological risk related to down-the-drain chemicals discharged by municipal wastewater treatment plants (WWTPs) are strongly influenced by in-stream dilution of receiving waters which varies by geography, flow conditions and upstream wastewater inputs. The iSTREEM® model (American Cleaning Institute, Washington D.C.) was utilized to determine probabilistic distributions for no decay and decay-based dilution factors in mean annual and low (7Q10) flow conditions. The dilution factors derived in this study are "combined" dilution factors which account for both hydrologic dilution and cumulative upstream effluent contributions that will differ depending on the rate of in-stream decay due to biodegradation, volatilization, sorption, etc. for the chemical being evaluated. The median dilution factors estimated in this study (based on various in-stream decay rates from zero decay to a 1h half-life) for WWTP mixing zones dominated by domestic wastewater flow ranged from 132 to 609 at mean flow and 5 to 25 at low flow, while median dilution factors at drinking water intakes (mean flow) ranged from 146 to 2×10(7) depending on the in-stream decay rate. WWTPs within the iSTREEM® model were used to generate a distribution of per capita wastewater generated in the U.S. The dilution factor and per capita wastewater generation distributions developed by this work can be used to conduct probabilistic exposure assessments for down-the-drain chemicals in influent wastewater, wastewater treatment plant mixing zones and at drinking water intakes in the conterminous U.S. In addition, evaluation of types and abundance of U.S. wastewater treatment processes provided insight into treatment trends and the flow volume treated by each type of process. Moreover, removal efficiencies of chemicals can differ by treatment type. Hence, the availability of distributions for per capita wastewater production, treatment type, and dilution factors at a national

  18. Experimental acidification of two biogeochemically-distinct neotropical streams: Buffering mechanisms and macroinvertebrate drift

    Energy Technology Data Exchange (ETDEWEB)

    Ardón, Marcelo, E-mail: ardonsayaom@ecu.edu [Department of Biology and North Carolina Center for Biodiversity, East Carolina University, Greenville, NC 27858 (United States); Duff, John H. [U.S. Geological Survey, Menlo Park, CA 94025 (United States); Ramírez, Alonso [Department of Environmental Sciences, University of Puerto Rico, San Juan, PR 00931 (Puerto Rico); Small, Gaston E. [Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108 (United States); Jackman, Alan P. [University of California, Davis, CA 95616 (United States); Triska, Frank J. [U.S. Geological Survey, Menlo Park, CA 94025 (United States); Pringle, Catherine M. [Odum School of Ecology, University of Georgia, Athens, GA 30602 (United States)

    2013-01-15

    Research into the buffering mechanisms and ecological consequences of acidification in tropical streams is lacking. We have documented seasonal and episodic acidification events in streams draining La Selva Biological Station, Costa Rica. Across this forested landscape, the severity in seasonal and episodic acidification events varies due to interbasin groundwater flow (IGF). Streams that receive IGF have higher concentrations of solutes and more stable pH (∼ 6) than streams that do not receive IGF (pH ∼ 5). To examine the buffering capacity and vulnerability of macroinvertebrates to short-term acidification events, we added hydrochloric acid to acidify a low-solute, poorly buffered (without IGF) and a high-solute, well buffered stream (with IGF). We hypothesized that: 1) protonation of bicarbonate (HCO{sub 3}{sup −}) would neutralize most of the acid added in the high-solute stream, while base cation release from the sediments would be the most important buffering mechanism in the low-solute stream; 2) pH declines would mobilize inorganic aluminum (Ali) from sediments in both streams; and 3) pH declines would increase macroinvertebrate drift in both streams. We found that the high-solute stream neutralized 745 μeq/L (96% of the acid added), while the solute poor stream only neutralized 27.4 μeq/L (40%). Protonation of HCO{sub 3}{sup −} was an important buffering mechanism in both streams. Base cation, Fe{sup 2+}, and Ali release from sediments and protonation of organic acids also provided buffering in the low-solute stream. We measured low concentrations of Ali release in both streams (2-9 μeq/L) in response to acidification, but the low-solute stream released double the amount Ali per 100 μeq of acid added than the high solute stream. Macroinvertebrate drift increased in both streams in response to acidification and was dominated by Ephemeroptera and Chironomidae. Our results elucidate the different buffering mechanisms in tropical streams and

  19. The role of remediation, natural alkalinity sources and physical stream parameters in stream recovery.

    Science.gov (United States)

    Kruse, Natalie A; DeRose, Lisa; Korenowsky, Rebekah; Bowman, Jennifer R; Lopez, Dina; Johnson, Kelly; Rankin, Edward

    2013-10-15

    Acid mine drainage (AMD) negatively impacts not only stream chemistry, but also aquatic biology. The ultimate goal of AMD treatment is restoration of the biological community, but that goal is rarely explicit in treatment system design. Hewett Fork in Raccoon Creek Watershed, Ohio, has been impacted by historic coal mining and has been treated with a calcium oxide doser in the headwaters of the watershed since 2004. All of the acidic inputs are isolated to a 1.5 km stretch of stream in the headwaters of the Hewett Fork watershed. The macroinvertebrate and fish communities have begun to recover and it is possible to distinguish three zones downstream of the doser: an impaired zone, a transition zone and a recovered zone. Alkalinity from both the doser and natural sources and physical stream parameters play a role in stream restoration. In Hewett Fork, natural alkaline additions downstream are higher than those from the doser. Both, alkaline additions and stream velocity drive sediment and metal deposition. Metal deposition occurs in several patterns; aluminum tends to deposit in regions of low stream velocity, while iron tends to deposit once sufficient alkalinity is added to the system downstream of mining inputs. The majority of metal deposition occurs upstream of the recovered zone. Both the physical stream parameters and natural alkalinity sources influence biological recovery in treated AMD streams and should be considered in remediation plans. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Underground waters in Kamnik and Savinja Alps

    Directory of Open Access Journals (Sweden)

    Dušan Novak

    1995-12-01

    Full Text Available Dye-tracing tests in the region of the alps Velika planina and Mala planina have shown that the major part of the region drains towards the spring of the Lučnica at Podvolovljek where is also a small fish farm. As to the water level, the marginal and central parts also drain into the stream Lučka Bela or the springs at Volovljek.Quite interesting is the high-mountain plateau Veža, a karstified territory surrounded by the valleys Robanov kot and Podvolovljek, as well as the tributary area of the stream Kamniška Bistrica. Here there is every indication of the deep runoff into the springs above Luče, the spring Pečovski izvir, the temporary springswhich are close to the stream Savinja and into the unknown springs in the gorge below the rocky needle Igla. With regard to the water level, the higher parts of the massif can drain towards the valleys Robanov kot, Podvolovljek and Kamniška Bistrica.The tributary area of the Bistrica is quite well known, too. It has been discovered that the area of the saddle Kamniško sedlo drains towards the springs of the Savinja. The territories of the saddle Kokrsko sedlo, the alps Dolge njive and Kalce drain into the spring Studenci below Mokrica.

  1. Effects of pond draining on biodiversity and water quality of farm ponds.

    Science.gov (United States)

    Usio, Nisikawa; Imada, Miho; Nakagawa, Megumi; Akasaka, Munemitsu; Takamura, Noriko

    2013-12-01

    Farm ponds have high conservation value because they contribute significantly to regional biodiversity and ecosystem services. In Japan pond draining is a traditional management method that is widely believed to improve water quality and eradicate invasive fish. In addition, fishing by means of pond draining has significant cultural value for local people, serving as a social event. However, there is a widespread belief that pond draining reduces freshwater biodiversity through the extirpation of aquatic animals, but scientific evaluation of the effectiveness of pond draining is lacking. We conducted a large-scale field study to evaluate the effects of pond draining on invasive animal control, water quality, and aquatic biodiversity relative to different pond-management practices, pond physicochemistry, and surrounding land use. The results of boosted regression-tree models and analyses of similarity showed that pond draining had little effect on invasive fish control, water quality, or aquatic biodiversity. Draining even facilitated the colonization of farm ponds by invasive red swamp crayfish (Procambarus clarkii), which in turn may have detrimental effects on the biodiversity and water quality of farm ponds. Our results highlight the need for reconsidering current pond management and developing management plans with respect to multifunctionality of such ponds. Efectos del Drenado de Estanques sobre la Biodiversidad y la Calidad del Agua en Estanques de Cultivo. © 2013 Society for Conservation Biology.

  2. Placement of percutaneous transhepatic biliary stent using a silicone drain with channels

    Science.gov (United States)

    Yoshida, Hiroshi; Mamada, Yasuhiro; Taniai, Nobuhiko; Mineta, Sho; Mizuguchi, Yoshiaki; Kawano, Yoichi; Sasaki, Junpei; Nakamura, Yoshiharu; Aimoto, Takayuki; Tajiri, Takashi

    2009-01-01

    This report describes a method for percutaneous transhepatic biliary stenting with a BLAKE Silicone Drain, and discusses the usefulness of placement of the drain connected to a J-VAC Suction Reservoir for the treatment of stenotic hepaticojejunostomy. Percutaneous transhepatic biliary drainage was performed under ultrasonographic guidance in a patient with stenotic hepaticojejunostomy after hepatectomy for hepatic hilum malignancy. The technique used was as follows. After dilatation of the drainage root, an 11-Fr tube with several side holes was passed through the stenosis of the hepaticojejunostomy. A 10-Fr BLAKE Silicone Drain is flexible, which precludes one-step insertion. One week after insertion of the 11-Fr tube, a 0.035-inch guidewire was inserted into the tube. After removal of the 11-Fr tube, the guidewire was put into the channel of a 10-Fr BLAKE Silicone Drain. The drain was inserted into the jejunal limb through the intrahepatic bile duct and was connected to a J-VAC Suction Reservoir. Low-pressure continued suction was applied. Patients can be discharged after insertion of the 10-Fr BLAKE Silicone Drain connected to the J-VAC Suction Reservoir. Placement of a percutaneous transhepatic biliary stent using a 10-Fr BLAKE Silicone Drain connected to a J-VAC Suction Reservoir is useful for the treatment of stenotic hepaticojejunostomy. PMID:19725159

  3. The ecology and biogeochemistry of stream biofilms.

    Science.gov (United States)

    Battin, Tom J; Besemer, Katharina; Bengtsson, Mia M; Romani, Anna M; Packmann, Aaron I

    2016-04-01

    Streams and rivers form dense networks, shape the Earth's surface and, in their sediments, provide an immensely large surface area for microbial growth. Biofilms dominate microbial life in streams and rivers, drive crucial ecosystem processes and contribute substantially to global biogeochemical fluxes. In turn, water flow and related deliveries of nutrients and organic matter to biofilms constitute major constraints on microbial life. In this Review, we describe the ecology and biogeochemistry of stream biofilms and highlight the influence of physical and ecological processes on their structure and function. Recent advances in the study of biofilm ecology may pave the way towards a mechanistic understanding of the effects of climate and environmental change on stream biofilms and the biogeochemistry of stream ecosystems.

  4. The value of cholangiography through Jackson-Pratt drains in the management of postoperative biliary injuries.

    Science.gov (United States)

    Macedo, Francisco Igor B; Casillas, Victor J; Davis, James S; Levi, Joe U; Sleeman, Danny

    2014-01-01

    Iatrogenic biliary injury is the most significant complication after laparoscopic cholecystectomy. We present our experience with an alternative diagnostic approach using transcatheter cholangiography (TCC) through a Jackson-Pratt (JP) drain and discuss potential benefits and limitations of the technique. From March 2002 to February 2012, 40 patients with major postoperative biliary injury underwent biliary reconstruction at our institution. Mean age was 51.7 ± 18.1 years (range, 19 to 86 years) with 30 (75%) females. Seventeen (42.5%) injuries were detected intraoperatively and in 13 (32.5%) cases, JP drains were placed for biliary drainage. Lesions were classified according to Bismuth grade: I (10 patients [25%]), II (10 patients [25%]), III (six patients [15%]), IV (10 patients [25%]), and V (four patients [10%]). TCC was performed in seven patients with JP drains (53.8%). It fully defined the injury site in three cases of limited magnetic resonance cholangiopancreatography (MRCP) such as common hepatic duct and common bile duct leaks and in four cases (57.1%) that endoscopic retrograde cholangiopancreatography (ERCP) was limited as a result of clipping of the distal common bile duct. TCC showed promising results in cases of limited MRCP and ERCP such as fistulous orifices or leakage. It may represent an alternative adjunct in the diagnostic armamentarium of complex biliary injuries.

  5. Management of extensive surgical emphysema with subcutaneous drain: A case report

    Directory of Open Access Journals (Sweden)

    Quoc Tran

    Full Text Available Introduction: Subcutaneous emphysema (SE is a frequent and often self-limiting complication of tube thoracostomy or other cardiothoracic procedures. On rare occasions, severe and extensive surgical emphysema marked by palpable cutaneous tension, dysphagia, dysphonia, palpebral closure or associated with pneumoperitoneum, airway compromise, “tension phenomenon” and respiratory failure require treatment. Presentation of case: A 67 year old lady presented with a large spontaneous pneumothorax on the background of end-stage chronic obstructive pulmonary disease (COPD and newly diagnosed lung cancer, developed extensive surgical emphysema following insertion of a chest drain. Immediate improvement was observed after insertion of a large-bore, 26 French (Fr. intercostal catheter, subcutaneous drain which was maintained under low suction (−5 cm H2O for a further 24 h. Discussion: Several methods have been described in the literature for the treatment of extensive subcutaneous emphysema, including: emergency tracheostomy, multisite subcutaneous drainage, infraclavicular “blow holes” incisions and subcutaneous drains or simply increasing suction on an in situ chest drain. Here a large-bore, fenestrated, subcutaneous drain maintained on low negative pressure also provided the necessary decompression. Conclusion: In the absence of a comparative study to identify the most effective method to manage extensive subcutaneous emphysema, this case highlights an effective, simple and safe management option. Keywords: Pneumothorax, Subcutaneous emphysema, Drain, Low suction, Intercostal catheter, Case report

  6. Stream Ammonium Uptake Across Scales in Headwater Catchments of a Tropical Rainforest, Luquillo Mountains, Puerto Rico

    Science.gov (United States)

    Brereton, R. L.; McDowell, W. H.; Wymore, A.

    2015-12-01

    Many tropical forest streams export high amounts of nitrogen relative to streams draining undisturbed watersheds of other biomes. With their low DOC concentrations and high rates of respiration, headwater streams in the Luquillo Mountains have been previously characterized as energy-limited, suggesting that NH4+ uptake is dominated not by N demand but by energy demand. In the Rio Icacos watershed, high concentrations of NH4+ (>1 mg N/L) are found in groundwater adjacent to the streams, making high inputs of NH4+ to the stream channel via groundwater seepage likely. Stream nutrient spiraling metrics can be used to quantify uptake and retention rates of specific nutrients, and can be measured by solute additions. Tracer Additions for Spiraling Curve Characterization (TASCC) is a recently developed method (Covino et al. 2010) for quantifying nutrient uptake with a single slug addition of nutrient and conservative tracer. Here we present NH4+ uptake metrics from TASCC additions in three Luquillo streams of different sizes, ranging from 2nd to 4th order: the Rio Icacos, a larger, 3rd order tributary and a smaller 2nd order tributary. Background NH4+ concentrations vary by up to an order of magnitude, with highest concentrations (27 μg N/L) found in the smaller tributary. Background DOC concentrations are uniformly low and show no difference between the three streams (500-600 μg C/L). The smaller tributary has the shortest uptake length (155 m) and highest uptake velocity (2.9 mm/min) of the three streams. Unexpectedly, the Rio Icacos has a higher uptake velocity (1.7 mm/min) than the larger tributary (1.0 mm/min), despite having an uptake length more than double (1400 m) that of the larger tributary (596 m). Overall, NH4+ uptake is substantial in all three streams and varies with background concentrations, not stream size.

  7. Groundwater data improve modelling of headwater stream CO2 outgassing with a stable DIC isotope approach

    Science.gov (United States)

    Marx, Anne; Conrad, Marcus; Aizinger, Vadym; Prechtel, Alexander; van Geldern, Robert; Barth, Johannes A. C.

    2018-05-01

    A large portion of terrestrially derived carbon outgasses as carbon dioxide (CO2) from streams and rivers to the atmosphere. Particularly, the amount of CO2 outgassing from small headwater streams is highly uncertain. Conservative estimates suggest that they contribute 36 % (i.e. 0.93 petagrams (Pg) C yr-1) of total CO2 outgassing from all fluvial ecosystems on the globe. In this study, stream pCO2, dissolved inorganic carbon (DIC), and δ13CDIC data were used to determine CO2 outgassing from an acidic headwater stream in the Uhlířská catchment (Czech Republic). This stream drains a catchment with silicate bedrock. The applied stable isotope model is based on the principle that the 13C / 12C ratio of its sources and the intensity of CO2 outgassing control the isotope ratio of DIC in stream water. It avoids the use of the gas transfer velocity parameter (k), which is highly variable and mostly difficult to constrain. Model results indicate that CO2 outgassing contributed more than 80 % to the annual stream inorganic carbon loss in the Uhlířská catchment. This translated to a CO2 outgassing rate from the stream of 34.9 kg C m-2 yr-1 when normalised to the stream surface area. Large temporal variations with maximum values shortly before spring snowmelt and in summer emphasise the need for investigations at higher temporal resolution. We improved the model uncertainty by incorporating groundwater data to better constrain the isotope compositions of initial DIC. Due to the large global abundance of acidic, humic-rich headwaters, we underline the importance of this integral approach for global applications.

  8. New marine geophysical and sediment record of the Northeast Greenland Ice Stream.

    Science.gov (United States)

    Callard, L.; Roberts, D. H.; O'Cofaigh, C.; Lloyd, J. M.; Smith, J. A.; Dorschel, B.

    2017-12-01

    The NE Greenland Ice Stream (NEGIS) drains 16% of the Greenland Ice Sheet (GrIS) and has a sea-level equivalent of 1.1-1.4 m. Stabilised by two floating ice shelves, 79N and Zachariae Isstrom, until recently it has shown little response to increased atmospheric and oceanic warming. However, since 2010 it has experienced an accelerated rate of grounding line retreat ( 4 km) and significant ice shelf loss that indicates that this sector of the GrIS is now responding to current oceanic and/or climatic change and has the potential to be a major contributor to future global sea-level rise. The project `NEGIS', a collaboration between Durham University and AWI, aims to reconstruct the history of the NE Greenland Ice Stream from the Last Glacial Maximum (LGM) to present using both onshore and offshore geological archives to better understand past ice stream response to a warming climate. This contribution presents results and interpretations from an offshore dataset collected on the RV Polarstern, cruises PS100 and PS109 in 2016 and 2017. Gravity and box cores, supplemented by swath bathymetric and sub-bottom profiler data, were acquired and initial core analysis including x-radiographs and MSCL data logging has been performed. Data collection focused principally in the Norske Trough and the area directly in front of the 79N ice shelf, a sub-ice shelf environment as recently as two years ago. On the outer shelf streamlined subglacial bedforms, grounding-zone wedges and moraines as well as overconsolidated subglacial tills, record an extensive ice sheet advance to the shelf edge. On the inner shelf and in front of the 79N ice shelf, deep, glacially-eroded bedrock basins are infilled with stratified sediment. The stratified muds represent deglacial and Holocene glacimarine sedimentation, and capture the recent transition from sub-ice shelf to shelf free conditions. Multiproxy palaeoenvironmental reconstructions, including foraminifera and diatom analysis, and radiocarbon

  9. Human impacts to mountain streams

    Science.gov (United States)

    Wohl, Ellen

    2006-09-01

    Mountain streams are here defined as channel networks within mountainous regions of the world. This definition encompasses tremendous diversity of physical and biological conditions, as well as history of land use. Human effects on mountain streams may result from activities undertaken within the stream channel that directly alter channel geometry, the dynamics of water and sediment movement, contaminants in the stream, or aquatic and riparian communities. Examples include channelization, construction of grade-control structures or check dams, removal of beavers, and placer mining. Human effects can also result from activities within the watershed that indirectly affect streams by altering the movement of water, sediment, and contaminants into the channel. Deforestation, cropping, grazing, land drainage, and urbanization are among the land uses that indirectly alter stream processes. An overview of the relative intensity of human impacts to mountain streams is provided by a table summarizing human effects on each of the major mountainous regions with respect to five categories: flow regulation, biotic integrity, water pollution, channel alteration, and land use. This table indicates that very few mountains have streams not at least moderately affected by land use. The least affected mountainous regions are those at very high or very low latitudes, although our scientific ignorance of conditions in low-latitude mountains in particular means that streams in these mountains might be more altered than is widely recognized. Four case studies from northern Sweden (arctic region), Colorado Front Range (semiarid temperate region), Swiss Alps (humid temperate region), and Papua New Guinea (humid tropics) are also used to explore in detail the history and effects on rivers of human activities in mountainous regions. The overview and case studies indicate that mountain streams must be managed with particular attention to upstream/downstream connections, hillslope

  10. Managing health worker migration: a qualitative study of the Philippine response to nurse brain drain

    Directory of Open Access Journals (Sweden)

    Dimaya Roland M

    2012-12-01

    Full Text Available Abstract Background The emigration of skilled nurses from the Philippines is an ongoing phenomenon that has impacted the quality and quantity of the nursing workforce, while strengthening the domestic economy through remittances. This study examines how the development of brain drain-responsive policies is driven by the effects of nurse migration and how such efforts aim to achieve mind-shifts among nurses, governing and regulatory bodies, and public and private institutions in the Philippines and worldwide. Methods Interviews and focus group discussions were conducted to elicit exploratory perspectives on the policy response to nurse brain drain. Interviews with key informants from the nursing, labour and immigration sectors explored key themes behind the development of policies and programmes that respond to nurse migration. Focus group discussions were held with practising nurses to understand policy recipients’ perspectives on nurse migration and policy. Results Using the qualitative data, a thematic framework was created to conceptualize participants’ perceptions of how nurse migration has driven the policy development process. The framework demonstrates that policymakers have recognised the complexity of the brain drain phenomenon and are crafting dynamic policies and programmes that work to shift domestic and global mindsets on nurse training, employment and recruitment. Conclusions Development of responsive policy to Filipino nurse brain drain offers a glimpse into a domestic response to an increasingly prominent global issue. As a major source of professionals migrating abroad for employment, the Philippines has formalised efforts to manage nurse migration. Accordingly, the Philippine paradigm, summarised by the thematic framework presented in this paper, may act as an example for other countries that are experiencing similar shifts in healthcare worker employment due to migration.

  11. Theory of Maxwell's fish eye with mutually interacting sources and drains

    Science.gov (United States)

    Leonhardt, Ulf; Sahebdivan, Sahar

    2015-11-01

    Maxwell's fish eye is predicted to image with a resolution not limited by the wavelength of light. However, interactions between sources and drains may ruin the subwavelength imaging capabilities of this and similar absolute optical instruments. Nevertheless, as we show in this paper, at resonance frequencies of the device, an array of drains may resolve a single source, or alternatively, a single drain may scan an array of sources, no matter how narrowly spaced they are. It seems that near-field information can be obtained from far-field distances.

  12. Role of wound instillation with bupivacaine through surgical drains for postoperative analgesia in modified radical mastectomy

    Directory of Open Access Journals (Sweden)

    Nirmala Jonnavithula

    2015-01-01

    Full Text Available Background and Aims: Modified Radical Mastectomy (MRM is the commonly used surgical procedure for operable breast cancer, which involves extensive tissue dissection. Therefore, wound instillation with local anaesthetic may provide better postoperative analgesia than infiltration along the line of incision. We hypothesised that instillation of bupivacaine through chest and axillary drains into the wound may provide postoperative analgesia. Methods: In this prospective randomised controlled study 60 patients aged 45-60 years were divided into three groups. All patients were administered general anaesthesia. At the end of the surgical procedure, axillary and chest wall drains were placed before closure. Group C was the control with no instillation; Group S received 40 ml normal saline, 20 ml through each drain; and Group B received 40 ml of 0.25% bupivacaine and the drains were clamped for 10 min. After extubation, pain score for both static and dynamic pain was evaluated using visual analog scale and then 4 th hourly till 24 h. Rescue analgesia was injection tramadol, if the pain score exceeds 4. Statistical analysis was performed using SPSS version 13. Results : There was a significant difference in the cumulative analgesic requirement and the number of analgesic demands between the groups (P: 0.000. The mean duration of analgesia in the bupivacaine group was 14.6 h, 10.3 in the saline group and 4.3 h in the control group. Conclusion : Wound instillation with local anaesthetics is a simple and effective means of providing good analgesia without any major side-effects.

  13. Improved simulation of poorly drained forests using Biome-BGC.

    Science.gov (United States)

    Bond-Lamberty, Ben; Gower, Stith T; Ahl, Douglas E

    2007-05-01

    Forested wetlands and peatlands are important in boreal and terrestrial biogeochemical cycling, but most general-purpose forest process models are designed and parameterized for upland systems. We describe changes made to Biome-BGC, an ecophysiological process model, that improve its ability to simulate poorly drained forests. Model changes allowed for: (1) lateral water inflow from a surrounding watershed, and variable surface and subsurface drainage; (2) adverse effects of anoxic soil on decomposition and nutrient mineralization; (3) closure of leaf stomata in flooded soils; and (4) growth of nonvascular plants (i.e., bryophytes). Bryophytes were treated as ectohydric broadleaf evergreen plants with zero stomatal conductance, whose cuticular conductance to CO(2) was dependent on plant water content. Individual model changes were parameterized with published data, and ecosystem-level model performance was assessed by comparing simulated output to field data from the northern BOREAS site in Manitoba, Canada. The simulation of the poorly drained forest model exhibited reduced decomposition and vascular plant growth (-90%) compared with that of the well-drained forest model; the integrated bryophyte photosynthetic response accorded well with published data. Simulated net primary production, biomass and soil carbon accumulation broadly agreed with field measurements, although simulated net primary production was higher than observed data in well-drained stands. Simulated net primary production in the poorly drained forest was most sensitive to oxygen restriction on soil processes, and secondarily to stomatal closure in flooded conditions. The modified Biome-BGC remains unable to simulate true wetlands that are subject to prolonged flooding, because it does not track organic soil formation, water table changes, soil redox potential or anaerobic processes.

  14. Management of Chest Drains: A National Survey on Surgeons‑in ...

    African Journals Online (AJOL)

    triangle of safety [Figure 1]. Just above a quarter of respondents (27.2%) always utilized different sizes of tubes for different pathologies and the same proportion of respondents always positioned the tip of the tube apically to drain pneumothorax and basally to drain pleural effusion. In contrast, 9.9% and 6.2% of respondents.

  15. Water and bed-material quality of selected streams and reservoirs in the Research Triangle area of North Carolina, 1988-94

    Science.gov (United States)

    Oblinger, C.J.; Treece, M.W.

    1996-01-01

    The Triangle Area Water Supply Monitoring Project was formed by a consortium of local governments and governmental agencies in cooperation with the U.S. Geological Survey to supplement existing data on conventional pollutants, nutrients, and metals to enable eventual determination of long-term trends; to examine spatial differences among water supplies within the region, especially differences between smaller upland sources, large multipurpose reservoirs, and run-of-river supplies; to provide tributary loading inlake data for predictive modeling of Falls of the Neuse and B. Everett Jordan reservoirs; and to establish a database for synthetic organic compounds. Water-quality sampling began in October 1988 at 35 sites located on area run-of-river and reservoir water supplies and their tributaries. Sampling has continued through 1994. Samples were analyzed for major ions, nutrients, trace metals, pesticides, and semivolatile and volatile organic compounds. Monthly concentration data, high-flow concentration data, and data on daily mean streamflow at most stream sites were used to calculate loadings of nitrogen, phosphorus, suspended sediment, and trace metals to reservoirs. Stream and lake sites were assigned to one of five site categories-- (1) rivers, (2) large multipurpose reservoirs, (3) small water-supply reservoirs, (4) streams below urban areas and wastewater-treatment plants, and (5) headwater streams--according to general site characteristics. Concentrations of nitrogen species, phosphorus species, and selected trace metals were compared by site category using nonparametric analysis of variance techniques and qualitatively (trace metals). Wastewater-treatment plant effluents and urban runoff had a significant impact on water quality compared to reservoirs and headwater streams. Streams draining these areas had more mineralized water than streams draining undeveloped areas. Moreover, median nitrogen and nitrite plus nitrate concentrations were significantly

  16. Nitrate concentration-drainage flow (C-Q) relationship for a drained agricultural field in Eastern North Carolina Plain

    Science.gov (United States)

    Liu, W.; Youssef, M.; Birgand, F.; Chescheir, G. M.; Maxwell, B.; Tian, S.

    2017-12-01

    Agricultural drainage is a practice used to artificially enhance drainage characteristics of naturally poorly drained soils via subsurface drain tubing or open-ditch systems. Approximately 25% of the U.S. agricultural land requires improved drainage for economic crop production. However, drainage increases the transport of dissolved agricultural chemicals, particularly nitrates to downstream surface waters. Nutrient export from artificially drained agricultural landscapes has been identified as the leading source of elevated nutrient levels in major surface water bodies in the U.S. Controlled drainage has long been practiced to reduce nitrogen export from agricultural fields to downstream receiving waters. It has been hypothesized that controlled drainage reduces nitrogen losses by promoting denitrification, reducing drainage outflow from the field, and increasing plant uptake. The documented performance of the practice was widely variable as it depends on several site-specific factors. The goal of this research was to utilize high frequency measurements to investigate the effect of agricultural drainage and related management practices on nitrate fate and transport for an artificially drained agricultural field in eastern North Carolina. We deployed a field spectrophotometer to measure nitrate concentration every 45 minutes and measured drainage flow rate using a V-notch weir every 15 minutes. Furthermore, we measured groundwater level, precipitation, irrigation amount, temperature to characterize antecedent conditions for each event. Nitrate concentration-drainage flow (C-Q) relationships generated from the high frequency measurements illustrated anti-clockwise hysteresis loops and nitrate flushing mechanism in response to most precipitation and irrigation events. Statistical evaluation will be carried out for the C-Q relationships. The results of our analysis, combined with numerical modeling, will provide a better understanding of hydrological and

  17. Gazetteer of hydrologic characteristics of streams in Massachusetts; Blackstone River basin

    Science.gov (United States)

    Wandle, S.W.; Phipps, A.F.

    1984-01-01

    The Blackstone River basin encompasses 335 square miles in south-central Massachusetts, including parts of Bristol, Middlesex, Norfolk, and Worcester Counties. Drainage areas, using the latest available 1:24,000 scale topographic maps, were computed for the first time for streams draining more than 3 square miles and were recomputed for data-collection sites. Streamflow characteristics, were calculated using a new data base with records through 1980. These characteristics include annual and monthly flow statistics, duration of daily flow values, and the annual 7-day mean low flow at the 2-year and 10-year recurrence intervals. The 7-day, 10-year low-flow values are presented for 31 partial-record sites and the procedures used to determine the hydrologic characteristics of the basin are summarized. Basin characteristics representing 14 commonly used indices to estimate various streamflows are presented for the six gaged streams in the Blackstone River basin. This gazetteer will aid in the planning and siting of water-resources-related activities and will provide a common data base for governmental agencies and the engineering and planning communities. (USGS)

  18. The stable stiffness triangle - drained sand during deformation cycles

    DEFF Research Database (Denmark)

    Sabaliauskas, Tomas; Ibsen, Lars Bo

    2017-01-01

    Cyclic, drained sand stiffness was observed using the Danish triaxial appa- ratus. New, deformation dependant soil property (the stable stiffness triangle) was detected. Using the the stable stiffness triangle, secant stiffness of drained sand was plausible to predict (and control) even during ir...... findings can find application in off-shore, seismic and other engi- neering practice, or inspire new branches of research and modelling wherever dynamic, cyclic or transient loaded sand is encountered....

  19. Cold Vacuum Drying facility effluent drain system design description

    International Nuclear Information System (INIS)

    PITKOFF, C.C.

    1999-01-01

    This document describes the Cold Vacuum Drying Facility (CVDF) effluent drain system (EFS). The primary function of the EFS is to collect and transport fire suppression water discharged into a CVDF process bay to a retention basin located outside the facility. The EFS also provides confinement of spills that occur inside a process bay and allows non-contaminated water that drains to the process bay sumps to be collected until sampling and analysis are complete

  20. PEAT-CO2. Assessment of CO2 emissions from drained peatlands in SE Asia

    International Nuclear Information System (INIS)

    Hooijer, A.; Silvius, M.; Woesten, H.; Page, S.

    2006-12-01

    Forested tropical peatlands in SE Asia store at least 42,000 Megatonnes of soil carbon. This carbon is increasingly released to the atmosphere due to drainage and fires associated with plantation development and logging. Peatlands make up 12% of the SE Asian land area but account for 25% of current deforestation. Out of 27 million hectares of peatland, 12 million hectares (45%) are currently deforested and mostly drained. One important crop in drained peatlands is palm oil, which is increasingly used as a biofuel in Europe. In the PEAT-CO2 project, present and future emissions from drained peatlands were quantified using the latest data on peat extent and depth, present and projected land use and water management practice, decomposition rates and fire emissions. It was found that current likely CO2 emissions caused by decomposition of drained peatlands amounts to 632 Mt/y (between 355 and 874 Mt/y). This emission will increase in coming decades unless land management practices and peatland development plans are changed, and will continue well beyond the 21st century. In addition, over 1997-2006 an estimated average of 1400 Mt/y in CO2 emissions was caused by peatland fires that are also associated with drainage and degradation. The current total peatland CO2 emission of 2000 Mt/y equals almost 8% of global emissions from fossil fuel burning. These emissions have been rapidly increasing since 1985 and will further increase unless action is taken. Over 90% of this emission originates from Indonesia, which puts the country in 3rd place (after the USA and China) in the global CO2 emission ranking. It is concluded that deforested and drained peatlands in SE Asia are a globally significant source of CO2 emissions and a major obstacle to meeting the aim of stabilizing greenhouse gas emissions, as expressed by the international community. It is therefore recommended that international action is taken to help SE Asian countries, especially Indonesia, to better conserve

  1. Preservation of labile organic matter in soils of drained thaw lakes in Northern Alaska

    Science.gov (United States)

    Mueller, Carsten W.; Rethemeyer, Janet; Kao-Kniffin, Jenny; Löppmann, Sebastian; Hinkel, Kenneth; Bockheim, James

    2014-05-01

    A large number of studies predict changing organic matter (OM) dynamics in arctic soils due to global warming. In contrast to rather slowly altering bulk soil properties, single soil organic matter (SOM) fractions can provide a more detailed picture of the dynamics of differently preserved SOM pools in climate sensitive arctic regions. By the study of the chemical composition of such distinctive SOM fractions using nuclear magnetic resonance spectroscopy (NMR) together with radiocarbon analyses it is possible to evaluate the stability of the major OM pools. Approximately 50-75% of Alaska's Arctic Coastal Plain is covered with thaw lakes and drained thaw lakes that follow a 5,000 yr cycle of development (between creation and final drainage), thus forming a natural soil chronosequence. The drained thaw lakes offer the possibility to study SOM dynamics affected by permafrost processes over millennial timescales. In April 2010 we sampled 16 soil cores (including the active and permanent layer) reaching from young drained lakes (0-50 years since drainage) to ancient drained lakes (3000-5500 years since drainage). Air dried soil samples from soil horizons of the active and permanent layer were subjected to density fractionation in order to differentiate particulate OM and mineral associated OM. The chemical composition of the SOM fractions was analyzed by 13C CPMAS NMR spectroscopy. For a soil core of a young and an ancient drained thaw lake basin we also analyzed the 14C content. For the studied soils we can show that up to over 25 kg OC per square meter are stored mostly as labile, easily degradable organic matter rich in carbohydrates. In contrast only 10 kg OC per square meter were sequestered as presumably more stable mineral associated OC dominated by aliphatic compounds. Comparable to soils of temperate regions, we found small POM (dating we could show the stabilization of younger more labile OM at greater depth in buried O horizons. Additionally the study of the

  2. 241-AY-102 Leak Detection Pit Drain Line Inspection Report

    International Nuclear Information System (INIS)

    Boomer, Kayle D.; Engeman, Jason K.; Gunter, Jason R.; Joslyn, Cameron C.; Vazquez, Brandon J.; Venetz, Theodore J.; Garfield, John S.

    2014-01-01

    This document provides a description of the design components, operational approach, and results from the Tank AY-102 leak detection pit drain piping visual inspection. To perform this inspection a custom robotic crawler with a deployment device was designed, built, and operated by IHI Southwest Technologies, Inc. for WRPS to inspect the 6-inch leak detection pit drain line

  3. Mixing of Process Heels, Process Solutions and Recycle Streams: Small-Scale Simulant

    International Nuclear Information System (INIS)

    Kaplan, D.I.

    2001-01-01

    The overall objective of this small-scale simulant mixing study was to identify the processes within the Hanford Site River Protection Project - Waste Treatment Plant (RPP-WTP) that may generate precipitates and to identify the types of precipitates formed. This information can be used to identify where mixtures of various solutions will cause precipitation of solids, potentially causing operational problems such as fouling equipment or increasing the amount of High Level Waste glass produced. Having this information will help guide protocols for flushing or draining tanks, mixing internal recycle streams, and mixing waste tank supernates. This report contains the discussion and thermodynamic chemical speciation modeling of the raw data

  4. Coldwater fish in wadeable streams [Chapter 8

    Science.gov (United States)

    Jason B. Dunham; Amanda E. Rosenberger; Russell F. Thurow; C. Andrew Dolloff; Philip J. Howell

    2009-01-01

    Small, wadeable streams comprise the majority of habitats available to fishes in fluvial networks. Wadeable streams are generally less than 1 m deep, and fish can be sampled without the use of water craft. Cold waters are defined as having mean 7-d summer maximum water temperatures of less than 20°C and providing habitat for coldwater fishes.

  5. Drain-Site Hernia Containing the Vermiform Appendix: Report of a Case

    Directory of Open Access Journals (Sweden)

    Markus Gass

    2013-01-01

    Full Text Available The herniated vermiform appendix has been described as content of every hernia orifice in the right lower quadrant. While the femoral and inguinal herniated vermiform appendix is frequent enough to result in an own designation, port-site or even drain-site hernias are less frequently described. We report the case of a 62-year-old woman who presented with right lower quadrant pain seven years after Roux-en-Y Cystojejunostomy for a pancreatic cyst. CT scan showed herniation of the vermiform appendix through a former drain-site. A diagnostic laparoscopy with appendectomy and direct closure of the abdominal wall defect combined with mesh reinforcement was performed. Despite the decreasing use of intraperitoneal drains over the recent years, a multitude of patients had intraperitoneal drainage in former times. These patients face nowadays the risk of drain-site hernias with sometimes even unexpected structures inside.

  6. An initial SPARROW model of land use and in-stream controls on total organic carbon in streams of the conterminous United States

    Science.gov (United States)

    Shih, Jhih-Shyang; Alexander, Richard B.; Smith, Richard A.; Boyer, Elizabeth W.; Shwarz, Grogory E.; Chung, Susie

    2010-01-01

    Watersheds play many important roles in the carbon cycle: (1) they are a site for both terrestrial and aquatic carbon dioxide (CO2) removal through photosynthesis; (2) they transport living and decomposing organic carbon in streams and groundwater; and (3) they store organic carbon for widely varying lengths of time as a function of many biogeochemical factors. Using the U.S. Geological Survey (USGS) Spatially Referenced Regression on Watershed Attributes (SPARROW) model, along with long-term monitoring data on total organic carbon (TOC), this research quantitatively estimates the sources, transport, and fate of the long-term mean annual load of TOC in streams of the conterminous United States. The model simulations use surrogate measures of the major terrestrial and aquatic sources of organic carbon to estimate the long-term mean annual load of TOC in streams. The estimated carbon sources in the model are associated with four land uses (urban, cultivated, forest, and wetlands) and autochthonous fixation of carbon (stream photosynthesis). Stream photosynthesis is determined by reach-level application of an empirical model of stream chlorophyll based on total phosphorus concentration, and a mechanistic model of photosynthetic rate based on chlorophyll, average daily solar irradiance, water column light attenuation, and reach dimensions. It was found that the estimate of in-stream photosynthesis is a major contributor to the mean annual TOC load per unit of drainage area (that is, yield) in large streams, with a median share of about 60 percent of the total mean annual carbon load in streams with mean flows above 500 cubic feet per second. The interquartile range of the model predictions of TOC from in-stream photosynthesis is from 0.1 to 0.4 grams (g) carbon (C) per square meter (m-2) per day (day-1) for the approximately 62,000 stream reaches in the continental United States, which compares favorably with the reported literature range for net carbon fixation by

  7. Selenium in aquatic biota inhabiting agricultural drains in the Salton Sea Basin, California

    Science.gov (United States)

    Saiki, Michael K.; Martin, Barbara A.; May, Thomas W.

    2012-01-01

    Resource managers are concerned that water conservation practices in irrigated farmlands along the southern border of the Salton Sea, Imperial County, California, could increase selenium concentrations in agricultural drainwater and harm the desert pupfish (Cyprinodon macularius), a federally protected endangered species. As part of a broader attempt to address this concern, we conducted a 3-year investigation to collect baseline information on selenium concentrations in seven agricultural drains inhabited by pupfish. We collected water, sediment, selected aquatic food-chain taxa (particulate organic detritus, filamentous algae, net plankton, and midge [Chironomidae] larvae), and two poeciliid fishes (western mosquitofish Gambusia affinis and sailfin molly Poecilia latipinna) for selenium determinations. The two fish species served as ecological surrogates for pupfish, which we were not permitted to sacrifice. Dissolved selenium ranged from 0.70 to 32.8 μg/L, with selenate as the major constituent. Total selenium concentrations in other environmental matrices varied widely among drains, with one drain (Trifolium 18) exhibiting especially high concentrations in detritus, 5.98–58.0 μg Se/g; midge larvae, 12.7–50.6 μg Se/g; mosquitofish, 13.2–20.2 μg Se/g; and mollies, 12.8–30.4 μg Se/g (all tissue concentrations are based on dry weights). Although toxic thresholds for selenium in fishes from the Salton Sea are still poorly understood, available evidence suggests that ambient concentrations of this element may not be sufficiently elevated to adversely affect reproductive success and survival in selenium-tolerant poeciliids and pupfish.

  8. Selenium in aquatic biota inhabiting agricultural drains in the Salton Sea Basin, California.

    Science.gov (United States)

    Saiki, Michael K; Martin, Barbara A; May, Thomas W

    2012-09-01

    Resource managers are concerned that water conservation practices in irrigated farmlands along the southern border of the Salton Sea, Imperial County, California, could increase selenium concentrations in agricultural drainwater and harm the desert pupfish (Cyprinodon macularius), a federally protected endangered species. As part of a broader attempt to address this concern, we conducted a 3-year investigation to collect baseline information on selenium concentrations in seven agricultural drains inhabited by pupfish. We collected water, sediment, selected aquatic food-chain taxa (particulate organic detritus, filamentous algae, net plankton, and midge [Chironomidae] larvae), and two poeciliid fishes (western mosquitofish Gambusia affinis and sailfin molly Poecilia latipinna) for selenium determinations. The two fish species served as ecological surrogates for pupfish, which we were not permitted to sacrifice. Dissolved selenium ranged from 0.70 to 32.8 μg/L, with selenate as the major constituent. Total selenium concentrations in other environmental matrices varied widely among drains, with one drain (Trifolium 18) exhibiting especially high concentrations in detritus, 5.98-58.0 μg Se/g; midge larvae, 12.7-50.6 μg Se/g; mosquitofish, 13.2-20.2 μg Se/g; and mollies, 12.8-30.4 μg Se/g (all tissue concentrations are based on dry weights). Although toxic thresholds for selenium in fishes from the Salton Sea are still poorly understood, available evidence suggests that ambient concentrations of this element may not be sufficiently elevated to adversely affect reproductive success and survival in selenium-tolerant poeciliids and pupfish.

  9. Homogenization of one-dimensional draining through heterogeneous porous media including higher-order approximations

    Science.gov (United States)

    Anderson, Daniel M.; McLaughlin, Richard M.; Miller, Cass T.

    2018-02-01

    We examine a mathematical model of one-dimensional draining of a fluid through a periodically-layered porous medium. A porous medium, initially saturated with a fluid of a high density is assumed to drain out the bottom of the porous medium with a second lighter fluid replacing the draining fluid. We assume that the draining layer is sufficiently dense that the dynamics of the lighter fluid can be neglected with respect to the dynamics of the heavier draining fluid and that the height of the draining fluid, represented as a free boundary in the model, evolves in time. In this context, we neglect interfacial tension effects at the boundary between the two fluids. We show that this problem admits an exact solution. Our primary objective is to develop a homogenization theory in which we find not only leading-order, or effective, trends but also capture higher-order corrections to these effective draining rates. The approximate solution obtained by this homogenization theory is compared to the exact solution for two cases: (1) the permeability of the porous medium varies smoothly but rapidly and (2) the permeability varies as a piecewise constant function representing discrete layers of alternating high/low permeability. In both cases we are able to show that the corrections in the homogenization theory accurately predict the position of the free boundary moving through the porous medium.

  10. Magnetic minerals in three Asian rivers draining into the South China Sea: Pearl, Red, and Mekong Rivers

    Science.gov (United States)

    Kissel, Catherine; Liu, Zhifei; Li, Jinhua; Wandres, Camille

    2016-05-01

    The use of the marine sedimentary magnetic properties, as tracers for changes in precipitation rate and in oceanic water masses transport and exchanges, implies to identify and to characterize the different sources of the detrital fraction. This is of particular importance in closed and/or marginal seas such as the South China Sea. We report on the magnetic properties of sedimentary samples collected in three main Asian rivers draining into the South China Sea: the Pearl, Red, and Mekong Rivers. The geological formations as well as the present climatic conditions are different from one catchment to another. The entire set of performed magnetic analyses (low-field magnetic susceptibility, ARM acquisition and decay, IRM acquisition and decay, back-field acquisition, thermal demagnetization of three-axes IRM, hysteresis parameters, FORC diagrams, and low-temperature magnetic measurements) allow us to identify the magnetic mineralogy and the grain-size distribution when magnetite is dominant. Some degree of variability is observed in each basin, illustrating different parent rocks and degree of weathering. On average it appears that the Pearl River is rich in magnetite along the main stream while the Mekong River is rich in hematite. The Red River is a mixture of the two. Compared to clay mineral assemblages and major element contents previously determined on the same samples, these new findings indicate that the magnetic fraction brings complementary information of great interest for environmental reconstructions based on marine sediments from the South China Sea.

  11. Origin of the water drained by the tunnel Graton

    International Nuclear Information System (INIS)

    Plata B, A.

    1992-12-01

    The research of the origin of the water drained by the Graton tunnel was attempted using isotope techniques. During the period of studies (April 1989-October 1992), four field work was executed to sample waters for chemistry, stable isotope and Tritium analysis, an to inject tracers and verify the possible infiltration from the Rimac and Blanco rivers to the tunnel. The results of the stable isotope analysis show that the water drained by the Graton tunnel comes from a basin around 300 meters above the average altitude of the basin where the Graton is located. The Tritium analysis show that the water is relatively modern. Using the model of total mixing, the residence times of the water drained at the km 0.5 and 2.5 are in the order to 45 years. The conductivities of the water of the tunnel is higher than the Rimac river ones because the influence of mine water. The chemical analysis of the water sampled at the downstream end of the tunnel, show that the conservative ions of the water kept almost constant during more than two years. The results of the work with artificial tracer show that there is no significant leakage from the Rimac and Blanco rivers to the Graton tunnel. So far, it can be concluded as a preliminary approach that the Graton tunnel drains relatively modern water originated in another basin. The hydrodynamics of the area of study seems to include a large storage on underground water in the system. The topography, geology and isotopic composition of the water samples, points to the upper Mantaro river basin as the possible source of part of the water drained by the Graton tunnel. (authors). 20 p. 2 figs., 7 ills., 4 tabs

  12. Radiation streaming: the continuing problem of shield design

    International Nuclear Information System (INIS)

    Avery, A.F.

    1977-01-01

    The practical problems of shield design are reviewed and the major difficulties are shown to be those associated with streaming problems. The situations in which streaming occurs in various types of reactor are described including LMFBR's and fusion devices, and examples are given of ways in which the problems have been solved

  13. Streams with Strahler Stream Order

    Data.gov (United States)

    Minnesota Department of Natural Resources — Stream segments with Strahler stream order values assigned. As of 01/08/08 the linework is from the DNR24K stream coverages and will not match the updated...

  14. Optimization design for drain to nuclear power condenser

    International Nuclear Information System (INIS)

    Ding Jiapeng; Jiang Chengren

    2010-01-01

    Characters and varieties of drain to nuclear power condenser are discussed in this paper. Take the main steam system of a nuclear power as an example, normal and detailed optimization design are introduced, related expatiate are used as a reference for the drain of other systems. According to the characters of nuclear power instant operation, the influence and needed actions related with the optimization design are also analyzed. Based on the above research, the scheme has been carried out in a nuclear power station and safety for the condenser operation of the nuclear power has been improved largely. (authors)

  15. Groundwater data improve modelling of headwater stream CO2 outgassing with a stable DIC isotope approach

    Directory of Open Access Journals (Sweden)

    A. Marx

    2018-05-01

    Full Text Available A large portion of terrestrially derived carbon outgasses as carbon dioxide (CO2 from streams and rivers to the atmosphere. Particularly, the amount of CO2 outgassing from small headwater streams is highly uncertain. Conservative estimates suggest that they contribute 36 % (i.e. 0.93 petagrams (Pg C yr−1 of total CO2 outgassing from all fluvial ecosystems on the globe. In this study, stream pCO2, dissolved inorganic carbon (DIC, and δ13CDIC data were used to determine CO2 outgassing from an acidic headwater stream in the Uhlířská catchment (Czech Republic. This stream drains a catchment with silicate bedrock. The applied stable isotope model is based on the principle that the 13C ∕ 12C ratio of its sources and the intensity of CO2 outgassing control the isotope ratio of DIC in stream water. It avoids the use of the gas transfer velocity parameter (k, which is highly variable and mostly difficult to constrain. Model results indicate that CO2 outgassing contributed more than 80 % to the annual stream inorganic carbon loss in the Uhlířská catchment. This translated to a CO2 outgassing rate from the stream of 34.9 kg C m−2 yr−1 when normalised to the stream surface area. Large temporal variations with maximum values shortly before spring snowmelt and in summer emphasise the need for investigations at higher temporal resolution. We improved the model uncertainty by incorporating groundwater data to better constrain the isotope compositions of initial DIC. Due to the large global abundance of acidic, humic-rich headwaters, we underline the importance of this integral approach for global applications.

  16. Charge plasma based source/drain engineered Schottky Barrier MOSFET: Ambipolar suppression and improvement of the RF performance

    Science.gov (United States)

    Kale, Sumit; Kondekar, Pravin N.

    2018-01-01

    This paper reports a novel device structure for charge plasma based Schottky Barrier (SB) MOSFET on ultrathin SOI to suppress the ambipolar leakage current and improvement of the radio frequency (RF) performance. In the proposed device, we employ dual material for the source and drain formation. Therefore, source/drain is divided into two parts as main source/drain and source/drain extension. Erbium silicide (ErSi1.7) is used as main source/drain material and Hafnium metal is used as source/drain extension material. The source extension induces the electron plasma in the ultrathin SOI body resulting reduction of SB width at the source side. Similarly, drain extension also induces the electron plasma at the drain side. This significantly increases the SB width due to increased depletion at the drain end. As a result, the ambipolar leakage current can be suppressed. In addition, drain extension also reduces the parasitic capacitances of the proposed device to improve the RF performance. The optimization of length and work function of metal used in the drain extension is performed to achieve improvement in device performance. Moreover, the proposed device makes fabrication simpler, requires low thermal budget and free from random dopant fluctuations.

  17. Estimating drain flow from measured water table depth in layered soils under free and controlled drainage

    Science.gov (United States)

    Saadat, Samaneh; Bowling, Laura; Frankenberger, Jane; Kladivko, Eileen

    2018-01-01

    Long records of continuous drain flow are important for quantifying annual and seasonal changes in the subsurface drainage flow from drained agricultural land. Missing data due to equipment malfunction and other challenges have limited conclusions that can be made about annual flow and thus nutrient loads from field studies, including assessments of the effect of controlled drainage. Water table depth data may be available during gaps in flow data, providing a basis for filling missing drain flow data; therefore, the overall goal of this study was to examine the potential to estimate drain flow using water table observations. The objectives were to evaluate how the shape of the relationship between drain flow and water table height above drain varies depending on the soil hydraulic conductivity profile, to quantify how well the Hooghoudt equation represented the water table-drain flow relationship in five years of measured data at the Davis Purdue Agricultural Center (DPAC), and to determine the impact of controlled drainage on drain flow using the filled dataset. The shape of the drain flow-water table height relationship was found to depend on the selected hydraulic conductivity profile. Estimated drain flow using the Hooghoudt equation with measured water table height for both free draining and controlled periods compared well to observed flow with Nash-Sutcliffe Efficiency values above 0.7 and 0.8 for calibration and validation periods, respectively. Using this method, together with linear regression for the remaining gaps, a long-term drain flow record for a controlled drainage experiment at the DPAC was used to evaluate the impacts of controlled drainage on drain flow. In the controlled drainage sites, annual flow was 14-49% lower than free drainage.

  18. Reconciling records of ice streaming and ice margin retreat to produce a palaeogeographic reconstruction of the deglaciation of the Laurentide Ice Sheet

    Science.gov (United States)

    Margold, Martin; Stokes, Chris R.; Clark, Chris D.

    2018-06-01

    This paper reconstructs the deglaciation of the Laurentide Ice Sheet (LIS; including the Innuitian Ice Sheet) from the Last Glacial Maximum (LGM), with a particular focus on the spatial and temporal variations in ice streaming and the associated changes in flow patterns and ice divides. We build on a recent inventory of Laurentide ice streams and use an existing ice margin chronology to produce the first detailed transient reconstruction of the ice stream drainage network in the LIS, which we depict in a series of palaeogeographic maps. Results show that the drainage network at the LGM was similar to modern-day Antarctica. The majority of the ice streams were marine terminating and topographically-controlled and many of these continued to function late into the deglaciation, until the ice sheet lost its marine margin. Ice streams with a terrestrial ice margin in the west and south were more transient and ice flow directions changed with the build-up, peak-phase and collapse of the Cordilleran-Laurentide ice saddle. The south-eastern marine margin in Atlantic Canada started to retreat relatively early and some of the ice streams in this region switched off at or shortly after the LGM. In contrast, the ice streams draining towards the north-western and north-eastern marine margins in the Beaufort Sea and in Baffin Bay appear to have remained stable throughout most of the Late Glacial, and some of them continued to function until after the Younger Dryas (YD). The YD influenced the dynamics of the deglaciation, but there remains uncertainty about the response of the ice sheet in several sectors. We tentatively ascribe the switching-on of some major ice streams during this period (e.g. M'Clintock Channel Ice Stream at the north-west margin), but for other large ice streams whose timing partially overlaps with the YD, the drivers are less clear and ice-dynamical processes, rather than effects of climate and surface mass balance are viewed as more likely drivers. Retreat

  19. Estimation of local and regional components of drain - flow from an irrigated field

    International Nuclear Information System (INIS)

    Eching, S.O.; Hopmans, J.W.; Wallender, W.W.; Macyntyre, J.L.; Peters, D.

    1995-01-01

    The contribution of regional ground water and deep percolation from a furrow irrigated field to total drain flow was estimated using salt load analysis. It was found that 64% of the drain flow comes from regional ground water flow. The electrical conductivity of the drain water was highly correlated with the drain flow rate. From the field water balance with deep percolation as estimated from the salt load analysis, using yield function derived evapotranspiration, and measured changes in root zone water storage, it was shown that 14% of the crop evapotranspiration comes from ground water during the study period. 8 figs; 5 tabs; 15 refs ( Author )

  20. Strip-drains for in situ clean up of contaminated fine-grained soils

    International Nuclear Information System (INIS)

    Bowders, J.J.; Gabr, M.A.

    1995-01-01

    Methods for in situ remediation of contaminated soils, such as bioremediation, vacuum/air stripping and soil flushing have been found to be less effective under fine-grained soil conditions. To enhance the performance of these techniques, it was proposed that strip-drains or wick drains also known as prefabricated vertical (PV) drains be used. The research objective was to determine the feasibility of using PV drains to enhance the soil flushing process. Bench top and intermediate-scale laboratory experiments were conducted. An overview of the work, results and future considerations were presented. Results indicated that the technology is feasible. A preliminary model for the technology to be used in any field situation was developed. The model is currently being tested with data from physical experiments on both intermediate and field tests. 5 figs

  1. Modeling the effects of LID practices on streams health at watershed scale

    Science.gov (United States)

    Shannak, S.; Jaber, F. H.

    2013-12-01

    Increasing impervious covers due to urbanization will lead to an increase in runoff volumes, and eventually increase flooding. Stream channels adjust by widening and eroding stream bank which would impact downstream property negatively (Chin and Gregory, 2001). Also, urban runoff drains in sediment bank areas in what's known as riparian zones and constricts stream channels (Walsh, 2009). Both physical and chemical factors associated with urbanization such as high peak flows and low water quality further stress aquatic life and contribute to overall biological condition of urban streams (Maxted et al., 1995). While LID practices have been mentioned and studied in literature for stormwater management, they have not been studied in respect to reducing potential impact on stream health. To evaluate the performance and the effectiveness of LID practices at a watershed scale, sustainable detention pond, bioretention, and permeable pavement will be modeled at watershed scale. These measures affect the storm peak flows and base flow patterns over long periods, and there is a need to characterize their effect on stream bank and bed erosion, and aquatic life. These measures will create a linkage between urban watershed development and stream conditions specifically biological health. The first phase of this study is to design and construct LID practices at the Texas A&M AgriLife Research and Extension Center-Dallas, TX to collect field data about the performance of these practices on a smaller scale. The second phase consists of simulating the performance of LID practices on a watershed scale. This simulation presents a long term model (23 years) using SWAT to evaluate the potential impacts of these practices on; potential stream bank and bed erosion, and potential impact on aquatic life in the Blunn Watershed located in Austin, TX. Sub-daily time step model simulations will be developed to simulate the effectiveness of the three LID practices with respect to reducing

  2. Reverse blocking characteristics and mechanisms in Schottky-drain AlGaN/GaN HEMT with a drain field plate and floating field plates

    International Nuclear Information System (INIS)

    Mao Wei; She Wei-Bo; Zhang Jin-Feng; Zheng Xue-Feng; Wang Chong; Hao Yue; Yang Cui

    2016-01-01

    In this paper, a novel AlGaN/GaN HEMT with a Schottky drain and a compound field plate (SD-CFP HEMT) is presented for the purpose of better reverse blocking capability. The compound field plate (CFP) consists of a drain field plate (DFP) and several floating field plates (FFPs). The physical mechanisms of the CFP to improve the reverse breakdown voltage and to modulate the distributions of channel electric field and potential are investigated by two-dimensional numerical simulations with Silvaco-ATLAS. Compared with the HEMT with a Schottky drain (SD HEMT) and the HEMT with a Schottky drain and a DFP (SD-FP HEMT), the superiorities of SD-CFP HEMT lie in the continuous improvement of the reverse breakdown voltage by increasing the number of FFPs and in the same fabrication procedure as the SD-FP HEMT. Two useful optimization laws for the SD-CFP HEMTs are found and extracted from simulation results. The relationship between the number of the FFPs and the reverse breakdown voltage as well as the FP efficiency in SD-CFP HEMTs are discussed. The results in this paper demonstrate a great potential of CFP for enhancing the reverse blocking ability in AlGaN/GaN HEMT and may be of great value and significance in the design and actual manufacture of SD-CFP HEMTs. (paper)

  3. Stream Insect Production as a Function of Alkalinity and Detritus Processing

    OpenAIRE

    Osborn, Thomas G.

    1981-01-01

    The study was conducted to determine if aquatic insect production was significantly different between high and low alkalinity mountain streams and if any differences were associated with food availability factors. The major objectives included determining: (1) if annual production differences occur between high and low alkalinity streams; (2) if processing rates of terrestrial detritus differs between high and low alkalinity streams; (3) if detrital processing rates are related to stream inse...

  4. Thailand and brain drain

    OpenAIRE

    Terry Commins

    2009-01-01

    Brain drain has been the subject of research since the 1960s. This research has been hampered by a lack of accurate data from both source and receiving countries on migration and on the losses and gains to developing economies of skilled migration. However, despite these handicaps, research has been able to clearly show that trends are changing and the effect this is having is usually quite different for individual source countries.Thailand, as a developing economy, could be regarded as a sou...

  5. Experiments of draining and filling processes in a collapsible tube at high external pressure

    Science.gov (United States)

    Flaud, P.; Guesdon, P.; Fullana, J.-M.

    2012-02-01

    The venous circulation in the lower limb is mainly controlled by the muscular action of the calf. To study the mechanisms governing the venous draining and filling process in such a situation, an experimental setup, composed by a collapsible tube under external pressure, has been built. A valve preventing back flows is inserted at the bottom of the tube and allows to model two different configurations: physiological when the fluid flow is uni-directional and pathological when the fluid flows in both directions. Pressure and flow rate measurements are carried out at the inlet and outlet of the tube and an original optical device with three cameras is proposed to measure the instantaneous cross-sectional area. The experimental results (draining and filling with physiological or pathological valves) are confronted to a simple one-dimensional numerical model which completes the physical interpretation. One major observation is that the muscular contraction induces a fast emptying phase followed by a slow one controlled by viscous effects, and that a defect of the valve decreases, as expected, the ejected volume.

  6. The European Politics of Brain Drain

    DEFF Research Database (Denmark)

    Hasselbalch, Jacob

    This qualitative multi-method studymaps the politics of brain drain at the level of the European Union and follows the evolution of the issue over the last four parliamentary periods. By utilizing a novel combination of interviews with a content and network analysis of parliamentary questions...

  7. An economic perspective on Malawi's medical "brain drain"

    Directory of Open Access Journals (Sweden)

    Mohiddin Abdu

    2006-12-01

    Full Text Available Abstract Background The medical "brain drain" has been described as rich countries "looting" doctors and nurses from developing countries undermining their health systems and public health. However this "brain-drain" might also be seen as a success in the training and "export" of health professionals and the benefits this provides. This paper illustrates the arguments and possible policy options by focusing on the situation in one of the poorest countries in the world, Malawi. Discussion Many see this "brain drain" of medical staff as wrong with developed countries exploiting poorer ones. The effects are considerable with Malawi facing high vacancy rates in its public health system, and with migration threatening to outstrip training despite efforts to improve pay and conditions. This shortage of staff has made it more challenging for Malawi to deliver on its Essential Health Package and to absorb new international health funding. Yet, without any policy effort Malawi has been able to demonstrate its global competitiveness in the training ("production" of skilled health professionals. Remittances from migration are a large and growing source of foreign exchange for poor countries and tend to go directly to households. Whilst the data for Malawi is limited, studies from other poor countries demonstrate the power of remittances in significantly reducing poverty. Malawi can benefit from the export of health professionals provided there is a resolution of the situation whereby the state pays for training and the benefits are gained by the individual professional working abroad. Solutions include migrating staff paying back training costs, or rich host governments remitting part of a tax (e.g. income or national insurance to the Malawi government. These schemes would allow Malawi to scale up training of health professionals for local needs and to work abroad. Summary There is concern about the negative impacts of the medical "brain-drain". However a

  8. An economic perspective on Malawi's medical "brain drain"

    Science.gov (United States)

    Record, Richard; Mohiddin, Abdu

    2006-01-01

    Background The medical "brain drain" has been described as rich countries "looting" doctors and nurses from developing countries undermining their health systems and public health. However this "brain-drain" might also be seen as a success in the training and "export" of health professionals and the benefits this provides. This paper illustrates the arguments and possible policy options by focusing on the situation in one of the poorest countries in the world, Malawi. Discussion Many see this "brain drain" of medical staff as wrong with developed countries exploiting poorer ones. The effects are considerable with Malawi facing high vacancy rates in its public health system, and with migration threatening to outstrip training despite efforts to improve pay and conditions. This shortage of staff has made it more challenging for Malawi to deliver on its Essential Health Package and to absorb new international health funding. Yet, without any policy effort Malawi has been able to demonstrate its global competitiveness in the training ("production") of skilled health professionals. Remittances from migration are a large and growing source of foreign exchange for poor countries and tend to go directly to households. Whilst the data for Malawi is limited, studies from other poor countries demonstrate the power of remittances in significantly reducing poverty. Malawi can benefit from the export of health professionals provided there is a resolution of the situation whereby the state pays for training and the benefits are gained by the individual professional working abroad. Solutions include migrating staff paying back training costs, or rich host governments remitting part of a tax (e.g. income or national insurance) to the Malawi government. These schemes would allow Malawi to scale up training of health professionals for local needs and to work abroad. Summary There is concern about the negative impacts of the medical "brain-drain". However a closer look at the evidence

  9. Reduction in wick drain effectiveness with spacing for Utah silts and clays.

    Science.gov (United States)

    2012-04-01

    Although decreasing the spacing of vertical drains usually decreases the time for consolidation, previous field tests have shown that there is a critical drain spacing for which tighter spacing does not decrease the time for consolidation. This...

  10. Processing method of radioactive cleaning drain

    International Nuclear Information System (INIS)

    Otsuka, Shigemitsu; Murakami, Tadashi; Kitao, Hideo

    1998-01-01

    Upon processing of radioactive cleaning drains, contained Co-60 is removed by a selectively adsorbing adsorbent. In addition, after removing suspended materials by a filtering device, Co-60 as predominant nuclides in the drain is selectively adsorbed. The concentration of objective Co-60 is in the order of 0.1 Bq/cc, and non-radioactive metal ions such as Na + ions are present in the order of ppm in addition to Co-60. A granular adsorbent for selectively adsorbing Co-60 is oxine-added activated carbon, and has a grain size of from 20 to 48 mesh. The granular adsorbent is used while being filled in an adsorbing tower. Since a relatively simple device comprising the filtering device and the adsorbing tower in combination is provided, the reduction of the construction cost can be expected. In addition, since no filtering aid is used in the filtering device, the amount of secondary wastes is small. (N.H.)

  11. Autologous transfusion of drain contents in elective primary knee arthroplasty: its value and relevance.

    Science.gov (United States)

    Singh, Vinay Kumar; Singh, Pankaj Kumar; Javed, Sadaf; Kumar, Kuldeep; Tomar, Juhi

    2011-07-01

    Total knee arthroplasty is associated with significant post-operative blood loss often necessitating blood transfusions. Blood transfusions may be associated with transfusion reactions and may transmit human immunodeficiency virus, hepatitis C virus and hepatitis B virus, with devastating consequences. After total knee arthroplasty, transfusion of the contents of an autologous drain is becoming common practice. The aim of our study was to look at the effectiveness of these drains in elective primary total knee arthroplasty. A prospective study was conducted including 70 non-randomised patients. A normal suction drain was used in 35 patients (group A), whereas in the other 35 patients, a CellTrans™ drain was used (group B). All the operations were performed by four surgeons using a tourniquet with a medial parapatellar approach. Pre- and post-operative haemoglobin concentrations were recorded in both groups. A Student's t-test was applied to determine the statistical significance of the data collected. The average fall in post-operative haemoglobin was 3.66 g/dL (SD 1.46; range, 0.6-7.0) among patients in whom the simple drain was used (group A) and 2.29 g/dL (SD 0.92; range, 0.6-5.9) among those in whom the CellTrans™ drain was used (group B) (p<0.0001). Twenty-five units of allogeneic blood were required in group A compared to four units in group B. The rate of transfusion was 5.7% (2 patients) in the group in which CellTrans™ drain was used and 25.7% (9 patients) in the group in which a simple suction drain was used. Total knee arthroplasty is associated with significant post-operative blood loss despite best operative technique. Autologous reinfusion of the contents of a CellTrans™ drain significantly reduces the rate of post-operative blood transfusion. This study indicates that the use of an autologous drain could be recommended as routine practice in primary total knee arthroplasty.

  12. Is a drain tube necessary for minimally invasive lumbar spine fusion surgery?

    Science.gov (United States)

    Hung, Pei-I; Chang, Ming-Chau; Chou, Po-Hsin; Lin, Hsi-Hsien; Wang, Shih-Tien; Liu, Chien-Lin

    2017-03-01

    This study aimed to evaluate if closed suction wound drainage is necessary in minimally invasive surgery of transforaminal lumbar interbody fusion (MIS TLIF). This is a prospective randomized clinical study. Fifty-six patients who underwent MIS TLIF were randomly divided into groups A (with a closed suction wound drainage) and B (without tube drainage). Surgical duration, intraoperative blood loss, timing of ambulation, length of hospital stay and complications were recorded. Patients were followed up for an average of 25.3 months. Clinical outcome was assessed using the Oswestry disability index and visual analogue scale (VAS). Fusion rate was classified with the Bridwell grading system, based on plain radiograph. Both groups had similar patient demographics. The use of drains had no significant influence on perioperative parameters including operative time, estimated blood loss, length of stay and complications. Patients in group B started ambulation 1 day earlier than patients in group A (p drain tube can lead to pain, anxiety and discomfort during the postoperative period. We conclude that drain tubes are not necessary for MIS TLIF. Patients without drains had the benefit of earlier ambulation than those with drains.

  13. STREAMS - Supporting Underrepresented Groups in Earth Sciences

    Science.gov (United States)

    Carvalho-Knighton, K.; Johnson, A.

    2009-12-01

    In Fall 2008, STREAMS (Supporting Talented and Remarkable Environmental And Marine Science students) Scholarship initiative began at the University of South Florida St. Petersburg, the only public university in Pinellas County. STREAMS is a partnership between the University of South Florida St. Petersburg’s (USFSP) Environmental Science and Policy Program and University of South Florida’s (USF) College of Marine Science. The STREAMS Student Scholarship Program has facilitated increased recruitment, retention, and graduation of USFSP environmental science and USF marine science majors. The STREAMS program has increased opportunities for minorities and women to obtain undergraduate and graduate degrees, gain valuable research experience and engage in professional development activities. STREAMS scholars have benefited from being mentored by USFSP and USF faculty and as well as MSPhDs students and NSF Florida-Georgia LSAMP Bridge to Doctorate graduate fellows. In addition, STREAMS has facilitated activities designed to prepare student participants for successful Earth system science-related careers. We will elucidate the need for this initiative and vision for the collaboration.

  14. Drainage of shallow peat harvesting areas with pipe drains; Madaltuneen turvetuotantokentaen kuivatustutkimus

    Energy Technology Data Exchange (ETDEWEB)

    Klemetti, V. [Vapo Oy, Jyvaeskylae (Finland)

    1997-12-01

    This study aims to develop pipe draining techniques in peat harvesting areas, which have been in active use so long time that the remaining peat layer is about one meter thick. The method should be technically and economically feasible as well as environmentally acceptable. Special attention is paid to pipe installation techniques, drain spacing and impacts on watercourses, which receive the drainage waters. After pipe installation the area was monitored by measuring pipe runoffs, water tables, moisture content of peat and quality of drain water. These are the results of second year. (orig.)

  15. Hydrogeochemical and stream sediment detailed geochemical survey for Edgemont, South Dakota; Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Butz, T.R.; Dean, N.E.; Bard, C.S.; Helgerson, R.N.; Grimes, J.G.; Pritz, P.M.

    1980-05-31

    Results of the Edgemont detailed geochemical survey are reported. Field and laboratory data are presented for 109 groundwater and 419 stream sediment samples. Statistical and areal distributions of uranium and possible uranium-related variables are given. A generalized geologic map of the survey area is provided, and pertinent geologic factors which may be of significance in evaluating the potential for uranium mineralization are briefly discussed. Groundwaters containing greater than or equal to 7.35 ppB uranium are present in scattered clusters throughout the area sampled. Most of these groundwaters are from wells drilled where the Inyan Kara Group is exposed at the surface. The exceptions are a group of samples in the northwestern part of the area sampled and south of the Dewey Terrace. These groundwaters are also produced from the Inyan Kara Group where it is overlain by the Graneros Group and alluvium. The high uranium groundwaters along and to the south of the terrace are characterized by high molybdenum, uranium/specific conductance, and uranium/sulfate values. Many of the groundwaters sampled along the outcrop of the Inyan Kara Group are near uranium mines. Groundwaters have high amounts of uranium and molybdenum. Samples taken downdip are sulfide waters with low values of uranium and high values of arsenic, molybdenum, selenium, and vanadium. Stream sediments containing greater than or equal to 5.50 ppM soluble uranium are concentrated in basins draining the Graneros and Inyan Kara Groups. These values are associated with high values for arsenic, selenium, and vanadium in samples from both groups. Anomalous values for these elements in the Graneros Group may be caused by bentonite beds contained in the rock units. As shown on the geochemical distribution plot, high uranium values that are located in the Inyan Kara Group are almost exclusively draining open-pit uranium mines.

  16. Hydrogeochemical and stream sediment detailed geochemical survey for Edgemont, South Dakota; Wyoming

    International Nuclear Information System (INIS)

    Butz, T.R.; Dean, N.E.; Bard, C.S.; Helgerson, R.N.; Grimes, J.G.; Pritz, P.M.

    1980-01-01

    Results of the Edgemont detailed geochemical survey are reported. Field and laboratory data are presented for 109 groundwater and 419 stream sediment samples. Statistical and areal distributions of uranium and possible uranium-related variables are given. A generalized geologic map of the survey area is provided, and pertinent geologic factors which may be of significance in evaluating the potential for uranium mineralization are briefly discussed. Groundwaters containing greater than or equal to 7.35 ppB uranium are present in scattered clusters throughout the area sampled. Most of these groundwaters are from wells drilled where the Inyan Kara Group is exposed at the surface. The exceptions are a group of samples in the northwestern part of the area sampled and south of the Dewey Terrace. These groundwaters are also produced from the Inyan Kara Group where it is overlain by the Graneros Group and alluvium. The high uranium groundwaters along and to the south of the terrace are characterized by high molybdenum, uranium/specific conductance, and uranium/sulfate values. Many of the groundwaters sampled along the outcrop of the Inyan Kara Group are near uranium mines. Groundwaters have high amounts of uranium and molybdenum. Samples taken downdip are sulfide waters with low values of uranium and high values of arsenic, molybdenum, selenium, and vanadium. Stream sediments containing greater than or equal to 5.50 ppM soluble uranium are concentrated in basins draining the Graneros and Inyan Kara Groups. These values are associated with high values for arsenic, selenium, and vanadium in samples from both groups. Anomalous values for these elements in the Graneros Group may be caused by bentonite beds contained in the rock units. As shown on the geochemical distribution plot, high uranium values that are located in the Inyan Kara Group are almost exclusively draining open-pit uranium mines

  17. Draining Collars and Lenses in Liquid-Lined Vertical Tubes.

    Science.gov (United States)

    Jensen

    2000-01-01

    The speed at which an annular liquid collar drains under gravity g in a vertical tube of radius a, when the tube has an otherwise thin viscous liquid lining on its interior, is determined by a balance between the collar's weight and viscous shear stresses confined to narrow regions in the neighborhood of the collar's effective contact lines. Whether a collar grows or shrinks in volume as it drains depends on the modified Bond number B=rho g a(2)/(sigmaepsilon), where rho is the fluid density, sigma is its surface tension, and epsilona is the thickness of the thin film immediately ahead of the collar. Asymptotic methods are used here to determine the following nonlinear stability criteria for an individual collar, valid in the limit of small epsilon. For 0draining collars grow in volume and, in sufficiently long tubes, ultimately "snap off" to form stable lenses. For 0.5960drain, so that any lens ultimately ruptures, unless stabilizing intermolecular forces allow the formation of a lamella supported by a macroscopic Plateau border. If surfactant immobilizes the liquid's free surface, these critical values of B are reduced by a factor of 2 but the distance a collar must travel before it snaps off is unchanged. Gravitationally driven snap off is therefore most likely to occur in long tubes with radii substantially less than the capillary lengthscale sigma/rhog)(1/2). Copyright 2000 Academic Press.

  18. Brain drain in globalization A general equilibrium analysis from the sending countries’ perspective

    OpenAIRE

    Luca MARCHIORI; I-Ling SHEN; Frederic DOCQUIER

    2009-01-01

    The paper assesses the global effects of brain drain on developing economies and quantifies the relative sizes of various static and dynamic impacts. By constructing a unified generic framework characterized by overlapping generations dynamics and calibrated to real data, this study incorporates many direct impacts of brain drain whose interactions, along with other indirect effects, are endogenously and dynamically generated. Our findings suggest that the short-run impact of brain drain on r...

  19. Restructuring brain drain: strengthening governance and financing for health worker migration.

    Science.gov (United States)

    Mackey, Tim K; Liang, Bryan A

    2013-01-15

    Health worker migration from resource-poor countries to developed countries, also known as ''brain drain'', represents a serious global health crisis and a significant barrier to achieving global health equity. Resource-poor countries are unable to recruit and retain health workers for domestic health systems, resulting in inadequate health infrastructure and millions of dollars in healthcare investment losses. Using acceptable methods of policy analysis, we first assess current strategies aimed at alleviating brain drain and then propose our own global health policy based solution to address current policy limitations. Although governments and private organizations have tried to address this policy challenge, brain drain continues to destabilise public health systems and their populations globally. Most importantly, lack of adequate financing and binding governance solutions continue to fail to prevent health worker brain drain. In response to these challenges, the establishment of a Global Health Resource Fund in conjunction with an international framework for health worker migration could create global governance for stable funding mechanisms encourage equitable migration pathways, and provide data collection that is desperately needed.

  20. Powerful Software to Simulate Soil Consolidation Problems with Prefabricated Vertical Drains

    Directory of Open Access Journals (Sweden)

    Gonzalo García-Ros

    2018-02-01

    Full Text Available The present work describes the program Simulation of Consolidation with Vertical Drains (SICOMED_2018, a tool for the solution of consolidation processes in heterogeneous soils, with totally or partially penetrating prefabricated vertical drains (PVD and considering both the effects of the smear zone, generated when introducing the drain into the ground, and the limitation in the discharge capacity of the drain. In order to provide a completely free program, the code Next-Generation Simulation Program with Integrated Circuit Emphasis (Ngspice has been used as a numerical tool while the Matrix Laboratory (MATLAB code was used to program and create an interface with the user through interactive screens. In this way, SICOMED_2018 is presented as an easy-to-use and intuitive program, with a simple graphical interface that allows the user to enter all the soil properties and geometry of the problem without having to resort to a complex software package that requires programming. Illustrative applications describe both the versatility of the program and the reliability of its numerical solutions.

  1. Year 3 Summary Report: Baseline Selenium Monitoring of Agricultural Drains Operated by the Imperial Irrigation District in the Salton Sea Basin

    Science.gov (United States)

    Saiki, Michael K.; Martin, Barbara A.; May, Thomas W.

    2008-01-01

    This report summarizes findings from the third year of a 4-year-long field investigation to document selected baseline environmental conditions in 29 agricultural drains and ponds operated by the Imperial Irrigation District along the southern border of the Salton Sea. Routine water quality and fish species were measured at roughly quarterly intervals from April 2007 to January 2008. The water quality measurements included total suspended solids and total (particulate plus dissolved) selenium. In addition, during April and October 2007, water samples were collected from seven intensively monitored drains for measurement of particulate and dissolved selenium, including inorganic and organic fractions. In addition, sediment, aquatic food chain matrices (particulate organic detritus, filamentous algae, net plankton, and midge [chironomid] larvae), and two fish species (western mosquitofish, Gambusia affinis; and sailfin molly, Poecilia latipinna) were sampled from the seven drains for measurement of total selenium concentrations. The mosquitofish and mollies were intended to serve as surrogates for desert pupfish (Cyprinodon macularius), an endangered species that we were not permitted to take for selenium determinations. Water quality values were typical of surface waters in a hot desert climate. A few drains exhibited brackish, near anoxic conditions especially during the summer and fall when water temperatures occasionally exceeded 30 degrees C. In general, total selenium concentrations in water varied directly with conductivity and inversely with pH. Although desert pupfish were found in several drains, sometimes in relatively high numbers, the fish faunas of most drains and ponds were dominated by nonnative species, especially red shiner (Cyprinella lutrensis), mosquitofish, and mollies. Dissolved selenium in water samples from the seven intensively monitored drains ranged from 0.700 to 24.1 ug/L, with selenate as the major constituent in all samples. Selenium

  2. Brain drain from developing countries: how can brain drain be converted into wisdom gain?

    OpenAIRE

    Dodani, Sunita; LaPorte, Ronald E

    2005-01-01

    Brain drain is defined as the migration of health personnel in search of the better standard of living and quality of life, higher salaries, access to advanced technology and more stable political conditions in different places worldwide. This migration of health professionals for better opportunities, both within countries and across international borders, is of growing concern worldwide because of its impact on health systems in developing countries. Why do talented people leave their count...

  3. Quality and mutagenicity of water and sediment of the streams impacted by the former uranium mine area Olší-Drahonín (Czech Republic).

    Science.gov (United States)

    Hudcová, H; Badurová, J; Rozkošný, M; Sova, J; Funková, R; Svobodová, J

    2013-02-01

    The water quality research performed in the years 2003-2010 demonstrated an impact of the mine water pumped from the closed Olší uranium mine and discharged from the mine water treatment plant (MWTP) and groundwater from springs in the area on the water quality of the Hadůvka stream. The water ecosystems of the lower part of the Hadůvka stream are impacted mainly by water originated from the springs located in the stream valley and drained syenit subsoil, naturally rich in uranium. Those inflows caused a very high concentration of uranium measured in the water of the stream, which exceeds the given limit value. No negative impact on the water ecosystems of the receiving Bobrůvka River was found. This reduction of impact is caused by five times higher average daily flow rate of the Bobrůvka River in comparison with the Hadůvka stream, which results in a sufficient dilution of pollution from the Hadůvka. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Outcome in Chronic Subdural Hematoma After Subdural vs. Subgaleal Drain.

    Science.gov (United States)

    Ishfaq, Asim

    2017-07-01

    To compare the outcome after surgery for chronic subdural hematoma when the drain is placed in subdural space or subgaleal space. Quasi experimental study. Combined Military Hospital, Lahore, from July 2015 to June 2016. Patients with chronic subdural hematoma of both genders and age, ranging between 55 to 85 years, were included. Patients on antiplatelet/anticoagulant therapy and acute on chronic subdural hematoma were excluded. Patients were divided in two equal groups each depending on whether drain was placed in subgaleal space (Group 1), and subdual space (Group 2), (n=31 patients each). Patients were positioned flat in bed after surgery. Clinical and radiological parameters and clinical outcome were compared between the two groups. Statistical test with significance of p hematoma was 15 ±6.5 mm. Patients with subdural drain placement had more complications such as pneumocephalus 11 (35.4%) vs. 6 (19.3%), and intracerebral hemorrhage 4 (12.9%) vs. 2 (6.4%). Clinical outcome was good in both groups 27 (87%) in Group 1 and 28 (90%) in Group 2. Patients of both groups had good outcome after surgery. Complications like pneumocephalus and intracerebral hemorrhage were more common in subdural location of drain, though not reaching statistically significance level to favor one technique over another.

  5. Prefabricated vertical drains, vol. I : engineering guidelines.

    Science.gov (United States)

    1986-09-01

    This volume presents procedures and guidelines applicable to the design and instal : tion of prefabricated vertical drains to accelerate consolidation of soils. The : contents represent the Consultant's interpretation of the state-of-the-art as of : ...

  6. The effect of drains on the alkalinity of agricultural soils

    International Nuclear Information System (INIS)

    Iqbal, M.A.; Butt, T.; Anwar-ul-Haque; Haroon, M.; Haq, I.U.

    2009-01-01

    The purpose of the study was to observe the effect of industrial and domestic drains on the nearby agricultural areas which are either irrigated or not by the waste water but are close to drains. For this purpose 48 soil samples were collected from the selected areas of Faisalabad and were analyzed for alkali metals like Na/sup +/, K/sup +/, Li/sup +/ and some alkaline earth metals like Ba/sup 2+/> Mg/sup 3+/> Na/sup +/> K/sup +/> Li/sup +/ the levels of Ba/sup +2/ and K/sup +/ were found higher than permissible levels in almost all the soil samples. It was also concluded that the agricultural areas near the industrial drain which are either irrigated or not by the industrial waste water are found highly contaminated with mobile alkali metals (K, Na etc.) and higher values of percentage salinity. (author)

  7. An analytical drain current model for symmetric double-gate MOSFETs

    Science.gov (United States)

    Yu, Fei; Huang, Gongyi; Lin, Wei; Xu, Chuanzhong

    2018-04-01

    An analytical surface-potential-based drain current model of symmetric double-gate (sDG) MOSFETs is described as a SPICE compatible model in this paper. The continuous surface and central potentials from the accumulation to the strong inversion regions are solved from the 1-D Poisson's equation in sDG MOSFETs. Furthermore, the drain current is derived from the charge sheet model as a function of the surface potential. Over a wide range of terminal voltages, doping concentrations, and device geometries, the surface potential calculation scheme and drain current model are verified by solving the 1-D Poisson's equation based on the least square method and using the Silvaco Atlas simulation results and experimental data, respectively. Such a model can be adopted as a useful platform to develop the circuit simulator and provide the clear understanding of sDG MOSFET device physics.

  8. Postoperative use of drain in thyroid lobectomy – a randomized clinical trial conducted at Civil Hospital, Karachi, Pakistan

    Directory of Open Access Journals (Sweden)

    Memon Zahid

    2012-09-01

    Full Text Available Abstract Background Thyroidectomy is a common surgical procedure, after which drains are placed routinely. This study aims to assess the benefits of placing postoperative drains, its complications and affects on postoperative stay, in thyroid lobectomy. Methodology Randomized Clinical Trial of 60 goitre patients undergoing lobectomy was conducted at Civil Hospital Karachi, during July’11-December’11. Patients were randomly assigned into drain and non drain groups. Patient demographics, labs and complications were noted. Ultrasound of neck was performed on both groups. For drain group, the amount of fluid present in the surgical bed and redivac drain was added to calculate fluid collection while in non drain group it was calculated by ultrasound of neck on first and second post-op days. Data was entered and analyzed on SPSS v16 using Independent T tests. Result The mean total drain output for 2 days in non-drain group was significantly lower 10.67 (±9.072 ml while in drain group was 30.97 (±42.812 ml (p = 0.014. The mean postoperative stay of drain group (79.2 ±15.63 hours was significantly higher, as compared to mean postoperative stay of non drain group (50.4 ±7.32 hours. Mean Visual Analogue Score (VAS for pain day 1 (6.2 ±0.997 and day 2 (4.17 ±0.95 in drain group were significantly higher compared to day 1 (2.6 ±1.163 and day 2 (1.3 ±0.877 of non drain group. From drain group, 2 patients complained of stridor, dyspnea on Day 1 which subsided by Day 2 and 1 case of voice change, with no such complains in non drain group. No patients from both groups developed seroma, wound infection or hematoma. Conclusion In uncomplicated surgeries especially for lobectomy, use of drain can be omitted.

  9. High contents of rare earth elements (REEs) in stream waters of a Cu-Pb-Zn mining area.

    Science.gov (United States)

    Protano, G; Riccobono, F

    2002-01-01

    Stream waters draining an old mining area present very high rare earth element (REE) contents, reaching 928 microg/l as the maximum total value (sigmaREE). The middle rare earth elements (MREEs) are usually enriched with respect to both the light (LREEs) and heavy (HREEs) elements of this group, producing a characteristic "roof-shaped" pattern of the shale Post-Archean Australian Shales-normalized concentrations. At the Fenice Capanne Mine (FCM), the most important base metal mine of the study area, the REE source coincides with the mine tailings, mostly the oldest ones composed of iron-rich materials. The geochemical history of the REEs released into Noni stream from wastes in the FCM area is strictly determined by the pH, which controls the REE speciation and in-stream processes. The formation of Al-rich and mainly Fe-rich flocs effectively scavenges the REEs, which are readily and drastically removed from the solution when the pH approaches neutrality. Leaching experiments performed on flocs and waste materials demonstrate that Fe-oxides/oxyhydroxides play a key role in the release of lanthanide elements into stream waters. The origin of the "roof-shaped" REE distribution pattern as well as the peculiar geochemical behavior of some lanthanide elements in the aqueous system are discussed.

  10. Reverse blocking characteristics and mechanisms in Schottky-drain AlGaN/GaN HEMT with a drain field plate and floating field plates

    Science.gov (United States)

    Wei, Mao; Wei-Bo, She; Cui, Yang; Jin-Feng, Zhang; Xue-Feng, Zheng; Chong, Wang; Yue, Hao

    2016-01-01

    In this paper, a novel AlGaN/GaN HEMT with a Schottky drain and a compound field plate (SD-CFP HEMT) is presented for the purpose of better reverse blocking capability. The compound field plate (CFP) consists of a drain field plate (DFP) and several floating field plates (FFPs). The physical mechanisms of the CFP to improve the reverse breakdown voltage and to modulate the distributions of channel electric field and potential are investigated by two-dimensional numerical simulations with Silvaco-ATLAS. Compared with the HEMT with a Schottky drain (SD HEMT) and the HEMT with a Schottky drain and a DFP (SD-FP HEMT), the superiorities of SD-CFP HEMT lie in the continuous improvement of the reverse breakdown voltage by increasing the number of FFPs and in the same fabrication procedure as the SD-FP HEMT. Two useful optimization laws for the SD-CFP HEMTs are found and extracted from simulation results. The relationship between the number of the FFPs and the reverse breakdown voltage as well as the FP efficiency in SD-CFP HEMTs are discussed. The results in this paper demonstrate a great potential of CFP for enhancing the reverse blocking ability in AlGaN/GaN HEMT and may be of great value and significance in the design and actual manufacture of SD-CFP HEMTs. Project supported by the National Natural Science Foundation of China (Grant Nos. 61204085, 61334002, 61306017, 61474091, 61574112, and 61574110).

  11. Effects of Drains on Pain, Comfort and Anxiety in Patients Undergone Surgery

    Directory of Open Access Journals (Sweden)

    Ummu Yildiz Findik

    2013-01-01

    Full Text Available Backround: Surgical drains negatively affect patients’ comfort, cause anxiety along with pain, as they are used to promote healing after surgery.Purpose: This study aimed to determine pain, comfort and anxiety levels of patients with drains postoperatively.Methodology: Research was performed with 192 patients undergone abdominal, neck, breast and open heart surgery and had surgical and underwater chest drains at the postoperative period. Patient Information Form, Numerical Pain Scale, General Comfort Questionnaire and Trait Anxiety Scale was used for collection of data. In evaluating the data, we used the t-test, variance and correlation analysis, mean, percentage and frequency.Results: The patients’ mean score of pain was 4.67±2.93, comfort was 2.75±0.29 and anxiety was 39.31±9.21. It was found statistically significant that the comfort level decreases as the pain level increases and that the patients undergone open heart surgery and with underwater chest drains have higher pain levels. It was found statistically significant that, comfort level in patients undergone abdominal or cardiac surgery is lower than patients undergone breast or neck surgery, and that the comfort level decreases as the duration of drains increases. The increasing state anxiety while pain increases and comfort decreases was found statistically significant.Conclusions: Surgeries and drains applied after these procedures decrease the comfort level of the patients as increases the pain level. Also, pain and discomfort increase the patients’ anxiety. Nurses who providing care to these patients are suggested to improve measures about pain and anxiety reduction for maintaining of comfort.

  12. Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes

    Science.gov (United States)

    Arp, Christopher D.; Whitman, Matthew S.; Jones, Benjamin M.; Grosse, Guido; Gaglioti, Benjamin V.; Heim, Kurt C.

    2015-01-01

    Beaded streams are widespread in permafrost regions and are considered a common thermokarst landform. However, little is known about their distribution, how and under what conditions they form, and how their intriguing morphology translates to ecosystem functions and habitat. Here we report on a Circum-Arctic survey of beaded streams and a watershed-scale analysis in northern Alaska using remote sensing and field studies. We mapped over 400 channel networks with beaded morphology throughout the continuous permafrost zone of northern Alaska, Canada, and Russia and found the highest abundance associated with medium- to high- ground ice content permafrost in moderately sloping terrain. In the Fish Creek watershed, beaded streams accounted for half of the drainage density, occurring primarily as low-order channels initiating from lakes and drained lake basins. Beaded streams predictably transition to alluvial channels with increasing drainage area and decreasing channel slope, although this transition is modified by local controls on water and sediment delivery. Comparison of one beaded channel using repeat photography between 1948 and 2013 indicate a relatively stable landform and 14C dating of basal sediments suggest channel formation may be as early as the Pleistocene-Holocene transition. Contemporary processes, such as deep snow accumulation in riparian zones effectively insulates channel ice and allows for perennial liquid water below most beaded stream pools. Because of this, mean annual temperatures in pool beds are greater than 2°C, leading to the development of perennial thaw bulbs or taliks underlying these thermokarst features. In the summer, some pools thermally stratify, which reduces permafrost thaw and maintains coldwater habitats. Snowmelt generated peak-flows decrease rapidly by two or more orders of magnitude to summer low flows with slow reach-scale velocity distributions ranging from 0.1 to 0.01 m/s, yet channel runs still move water rapidly

  13. ECOLOGICAL ANALYSIS OF HYDROLOGIC DISTURBANCE REGIMES IN STREAMS OF NORTH AND SOUTH DAKOTA

    Science.gov (United States)

    Streamflow variability is an important component of physical disturbance in streams, and is likely to be a major organizing feature of habitat for stream fishes. The disturbance regime in streams is frequently described by the variability in streamflow from both floods and prolo...

  14. The molecular mechanism and physiological role of cytoplasmic streaming.

    Science.gov (United States)

    Tominaga, Motoki; Ito, Kohji

    2015-10-01

    Cytoplasmic streaming occurs widely in plants ranging from algae to angiosperms. However, the molecular mechanism and physiological role of cytoplasmic streaming have long remained unelucidated. Recent molecular genetic approaches have identified specific myosin members (XI-2 and XI-K as major and XI-1, XI-B, and XI-I as minor motive forces) for the generation of cytoplasmic streaming among 13 myosin XIs in Arabidopsis thaliana. Simultaneous knockout of these myosin XI members led to a reduced velocity of cytoplasmic streaming and marked defects of plant development. Furthermore, the artificial modifications of myosin XI-2 velocity changed plant and cell sizes along with the velocity of cytoplasmic streaming. Therefore, we assume that cytoplasmic streaming is one of the key regulators in determining plant size. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Final Report: Baseline Selenium Monitoring of Agricultural Drains Operated by the Imperial Irrigation District in the Salton Sea Basin, California

    Science.gov (United States)

    Saiki, Michael K.; Martin, Barbara A.; May, Thomas W.

    2010-01-01

    inversely correlated with total suspended-solids concentrations. Although pupfish were found in several drains, sometimes in relatively high numbers, the fish faunas of most drains and ponds were dominated by nonnative species, especially mosquitofish, mollies, and red shiner (Cyprinella lutrensis). Dissolved selenium in water samples from the seven intensively monitored drains ranged from 0.700 to 32.8 micrograms per liter (?g/L), with selenate as the major constituent. Selenium concentrations in other matrices varied widely among drains and ponds, with one drain (Trifolium 18) exhibiting especially high concentrations in food chain matrices [particulate organic detritus, 5.98-58.0 micrograms of selenium per gram (?g Se/g); midge larvae, 12.7-50.6 ?g Se/g] and in fish (mosquitofish, 13.2-20.2 ?g Se/g; sailfin mollies, 12.8-30.4 ?g Se/g; all concentrations are based on dry weights). Although selenium was accumulated by all trophic levels, biomagnification (defined as a progressive increase in selenium concentration from one trophic level to the next higher level) in midge larvae and fish occurred only at lower exposure concentrations. Judging mostly from circumstantial evidence, the health and wellbeing of poeciliids and pupfish are not believed to be threatened by ambient exposure to selenium in the drains and ponds.

  16. Drain tube migration into the anastomotic site of an esophagojejunostomy for gastric small cell carcinoma: short report.

    Science.gov (United States)

    Lai, Peng-Sheng; Lo, Chiao; Lin, Long-Wei; Lee, Po-Chu

    2010-05-21

    Intraluminal migration of a drain through an anastomotic site is a rare complication of gastric surgery. We herein report the intraluminal migration of a drain placed after a lower esophagectomy and total gastrectomy with Roux-en-Y anastomosis for gastric small cell carcinoma. Persistent drainage was noted 1 month after surgery, and radiographic studies were consistent with drain tube migration. Endoscopy revealed the drain had migrated into the esophagojejunostomy anastomotic site. The drain was removed from outside of abdominal wound while observing the anastomotic site endoscopically. The patient was treated with suction via a nasogastric tube drain for 5 days, and thereafter had an uneventful recovery. Though drain tube migration is a rare occurrence, it should be considered in patients with persistent drainage who have undergone gastric surgery.

  17. An analytical drain current model for symmetric double-gate MOSFETs

    Directory of Open Access Journals (Sweden)

    Fei Yu

    2018-04-01

    Full Text Available An analytical surface-potential-based drain current model of symmetric double-gate (sDG MOSFETs is described as a SPICE compatible model in this paper. The continuous surface and central potentials from the accumulation to the strong inversion regions are solved from the 1-D Poisson’s equation in sDG MOSFETs. Furthermore, the drain current is derived from the charge sheet model as a function of the surface potential. Over a wide range of terminal voltages, doping concentrations, and device geometries, the surface potential calculation scheme and drain current model are verified by solving the 1-D Poisson’s equation based on the least square method and using the Silvaco Atlas simulation results and experimental data, respectively. Such a model can be adopted as a useful platform to develop the circuit simulator and provide the clear understanding of sDG MOSFET device physics.

  18. Recent and historic sediment dynamics along Difficult Run, a suburban Virginia Piedmont stream

    Science.gov (United States)

    Hupp, Cliff R.; Noe, Gregory B.; Schenk, Edward R.; Bentham, Adam J.

    2012-01-01

    Suspended sediment is one of the major concerns regarding the quality of water entering the Chesapeake Bay. Some of the highest suspended-sediment concentrations occur on Piedmont streams, including Difficult Run, a tributary of the Potomac River draining urban and suburban parts of northern Virginia. Accurate information on catchment level sediment budgets is rare and difficult to determine. Further, the sediment trapping portion of sediment budget represents an important ecosystem service that profoundly affects downstream water quality. Our objectives, with special reference to human alterations to the landscape, include the documentation and estimation of floodplain sediment trapping (present and historic) and bank erosion along an urbanized Piedmont stream, the construction of a preliminary sediment balance, and the estimation of legacy sediment and recent development impacts. We used white feldspar markers to measure floodplain sedimentation rates and steel pins to measure erosion rates on floodplains and banks, respectively. Additional data were collected for/from legacy sediment thickness and characteristics, mill pond impacts, stream gaging station records, topographic surveying, and sediment density, texture, and organic content. Data were analyzed using GIS and various statistical programs. Results are interpreted relative to stream equilibrium affected by both post-colonial bottomland sedimentation (legacy) and modern watershed hardening associated with urbanization. Six floodplain/channel sites, from high to low in the watershed, were selected for intensive study. Bank erosion ranges from 0 to 470 kg/m/y and floodplain sedimentation ranges from 18 to 1369 kg/m/y (m refers to meters of stream reach). Upstream reaches are net erosional, while downstream reaches have a distinctly net depositional flux providing a watershed sediment balance of 2184 kg/m/y trapped within the system. The amounts of both deposition and erosion are large and suggest

  19. Recent and historic sediment dynamics along Difficult Run, a suburban Virginia Piedmont stream

    Science.gov (United States)

    Hupp, Cliff R.; Noe, Gregory B.; Schenk, Edward R.; Benthem, Adam J.

    2013-01-01

    Suspended sediment is one of the major concerns regarding the quality of water entering the Chesapeake Bay. Some of the highest suspended-sediment concentrations occur on Piedmont streams, including Difficult Run, a tributary of the Potomac River draining urban and suburban parts of northern Virginia. Accurate information on catchment level sediment budgets is rare and difficult to determine. Further, the sediment trapping portion of sediment budget represents an important ecosystem service that profoundly affects downstream water quality. Our objectives, with special reference to human alterations to the landscape, include the documentation and estimation of floodplain sediment trapping (present and historic) and bank erosion along an urbanized Piedmont stream, the construction of a preliminary sediment balance, and the estimation of legacy sediment and recent development impacts. We used white feldspar markers to measure floodplain sedimentation rates and steel pins to measure erosion rates on floodplains and banks, respectively. Additional data were collected for/from legacy sediment thickness and characteristics, mill pond impacts, stream gaging station records, topographic surveying, and sediment density, texture, and organic content. Data were analyzed using GIS and various statistical programs. Results are interpreted relative to stream equilibrium affected by both post-colonial bottomland sedimentation (legacy) and modern watershed hardening associated with urbanization. Six floodplain/channel sites, from high to low in the watershed, were selected for intensive study. Bank erosion ranges from 0 to 470 kg/m/y and floodplain sedimentation ranges from 18 to 1369 kg/m/y (m refers to meters of stream reach). Upstream reaches are net erosional, while downstream reaches have a distinctly net depositional flux providing a watershed sediment balance of 2184 kg/m/y trapped within the system. The amounts of both deposition and erosion are large and suggest

  20. Assessment

    Directory of Open Access Journals (Sweden)

    Ahmed Ali Rashed

    2014-01-01

    Full Text Available This research was set in order to estimate aquatic plants evapotranspiration, (ET in Edfina drain, Nile Delta, Egypt, which had an in-stream treatment wetland that was taken as a case study. A simple field scale approach is presented to measure drain water evaporation and water consumption of five aquatic plants, cultivated in floating tanks. Plants ET, (ETp values were obtained by measuring the daily quantity of water required to renovate the tank’s initial volume. Crop coefficients (Kc were obtained and water loss from the drain wetland was calculated due to evaporation and plants cells ETp. Results presented values of ETp and Kc which were controlled by plant leaf area and growing stage. The major ETp was for Hyacinth followed by Cattail, Reeds, Torpedo grass, and then duckweeds. All ETp values exceeded twice the adjacent non-vegetated water evaporation. The obtained Kc values referenced to the drain water evaporation were almost twice the Kc values of FAO Penman–Monteith ET, due to the landscape effects, as hot dry air can cause extra heat input and water loss. Total losses from in-stream treatment series of pond, 4 plants reaches and open disinfection zone did not exceed 0.55% of drain discharge.

  1. Dynamics of Upernavik Isstrøm

    DEFF Research Database (Denmark)

    Larsen, Signe Hillerup

    Fast flowing ice streams are responsible for draining the vast majority of the Greenland ice sheet. During the past few decades, the ice streams have undergone rapid acceleration and retreat Greenland wide. However, the controlling mechanism of the dynamic changes are still not well understood. Due...... to the ice streams' importance for the drainage of the entire ice sheet, the fifth assessment report (AR5) of the Intergovernmental Climate Panel (IPCC) deemed uncertainties in the flow of ice streams one of the major uncertainties in predicting future changes of the Greenland ice sheet. In this thesis......, the dynamical changes at Upernavik Isstrøm (UI), Northwest Greenland, are analysed and an ice flow model is used to study specific controlling mechanisms of the ice stream flow. The analysis of observations of velocity, thickness and calving front position changes, reveals asynchronous behaviour...

  2. Evolution of soil and vegetation cover on the bottom of drained thermokarst lake (a case study in the European Northeast of Russia)

    Science.gov (United States)

    Kaverin, Dmitry; Pastukhov, Alexander

    2015-04-01

    The evolution of soils and landscapes has been studied in a lake bed of former thermokarst lake, which was totally drained in 1979. Melioration of thermokarst lakes was conducted experimentally and locally under Soviet economics program during 1970-s. The aim of the program was to increase in biomass productivity of virgin tundra permafrost-thermokarst sites under agricultural activities. The former thermokarst lake "Opytnoe" located in the Bolshezemelskaya Tundra, Russian European Northeast. The lake bed is covered by peat-mineral sediments, which serves as soil-forming sediments favoring subsequent permafrost aggradation and cryogenic processes as well. Initially, after drainage, swampy meadows had been developed almost all over the lake bed. Further on, succession of landscape went diversely, typical and uncommon tundra landscapes formed. When activated, cryogenic processes favored the formation of peat mounds under dwarf shrub - lichen vegetation (7% of the area). Frost cracks and peat circles affected flat mounds all over the former lake bottom. On drained peat sites, with no active cryogenic processes, specific grass meadows on Cryic Sapric Histosols were developed. Totally, permafrost-affected soils occupy 77% of the area (2011). In some part of the lake bed further development of waterlogging leads to the formation of marshy meadows and willow communities where Gleysols prevail. During last twenty years, permafrost degradation has occurred under tall shrub communities, and it will progress in future. Water erosion processes in the drained lake bottom promoted the formation of local hydrographic network. In the stream floodplain grassy willow-stands formed on Fluvisols (3% of the area). The study has been conducted under Clima-East & RFBR 14-05-31111 projects.

  3. Drain tube migration into the anastomotic site of an esophagojejunostomy for gastric small cell carcinoma: short report

    Directory of Open Access Journals (Sweden)

    Lin Long-Wei

    2010-05-01

    Full Text Available Abstract Background Intraluminal migration of a drain through an anastomotic site is a rare complication of gastric surgery. Case Presentation We herein report the intraluminal migration of a drain placed after a lower esophagectomy and total gastrectomy with Roux-en-Y anastomosis for gastric small cell carcinoma. Persistent drainage was noted 1 month after surgery, and radiographic studies were consistent with drain tube migration. Endoscopy revealed the drain had migrated into the esophagojejunostomy anastomotic site. The drain was removed from outside of abdominal wound while observing the anastomotic site endoscopically. The patient was treated with suction via a nasogastric tube drain for 5 days, and thereafter had an uneventful recovery. Conclusions Though drain tube migration is a rare occurrence, it should be considered in patients with persistent drainage who have undergone gastric surgery.

  4. Geology, Streamflow, and Water Chemistry of the Talufofo Stream Basin, Saipan, Northern Mariana Islands

    Science.gov (United States)

    Izuka, Scot K.; Ewart, Charles J.

    1995-01-01

    ions in water samples from Talufofo Stream are characteristic of water draining a heavily vegetated basin near the ocean. The streamflow and water-chemistry data indicate that discharge from springs is in hydraulic connection with the limestone aquifer near the headwaters of the basin. The base flow therefore is subject to stresses placed on the nearby limestone ground-water system. Pumping from wells in the limestones at the headwaters of Talufofo Stream Basin may decrease spring flow in Talufofo Stream.

  5. Plumbing the brain drain.

    Science.gov (United States)

    Saravia, Nancy Gore; Miranda, Juan Francisco

    2004-08-01

    Opportunity is the driving force of migration. Unsatisfied demands for higher education and skills, which have been created by the knowledge-based global economy, have generated unprecedented opportunities in knowledge-intensive service industries. These multi-trillion dollar industries include information, communication, finance, business, education and health. The leading industrialized nations are also the focal points of knowledge-intensive service industries and as such constitute centres of research and development activity that proactively draw in talented individuals worldwide through selective immigration policies, employment opportunities and targeted recruitment. Higher education is another major conduit of talent from less-developed countries to the centres of the knowledge-based global economy. Together career and educational opportunities drive "brain drain and recirculation". The departure of a large proportion of the most competent and innovative individuals from developing nations slows the achievement of the critical mass needed to generate the enabling context in which knowledge creation occurs. To favourably modify the asymmetric movement and distribution of global talent, developing countries must implement bold and creative strategies that are backed by national policies to: provide world-class educational opportunities, construct knowledge-based research and development industries, and sustainably finance the required investment for these strategies. Brazil, China and India have moved in this direction, offering world-class education in areas crucial to national development, such as biotechnology and information technology, paralleled by investments in research and development. As a result, only a small proportion of the most highly educated individuals migrate from these countries, and research and development opportunities employ national talent and even attract immigrants.

  6. Method of bilateral pleural drainage by single Blake drain after esophagectomy.

    Science.gov (United States)

    Niwa, Yukiko; Koike, Masahiko; Oya, Hisaharu; Iwata, Naoki; Kobayashi, Daisuke; Kanda, Mitsuro; Tanaka, Chie; Yamada, Suguru; Fujii, Tsutomu; Nakayama, Goro; Sugimoto, Hiroyuki; Nomoto, Shuji; Fujiwara, Michitaka; Kodera, Yasuhiro

    2015-03-01

    Clinicians often encounter left pleural effusion after esophagectomy, which sometimes necessitates thoracentesis. We have introduced a new drainage method, bilateral pleural drainage by single Blake drain (BDSD), which we have been using since April 2013. This study aims to evaluate the performance of the BDSD. The BDSD method employs a 15-F Blake drain inserted from the right thoracic cavity to the left thoracic cavity across the posterior mediastinum. The conventional drain (CD) group consisted of 50 patients with a 19-F Blake drain placed in the right thoracic cavity during the period from April 2012 to March 2013. The BDSD group consisted of 54 patients treated from April 2013 to June 2014. The amount of total drainage in the BDSD group was significantly higher than that in the CD group (P pleural effusion and left lower lobe atelectasis in the BDSD group were significantly lower than those in the CD group (P pleural effusion necessitating thoracentesis drainage in the BDSD group. Compared with the conventional method, BDSD was able to evacuate bilateral pleural effusion more effectively, and the incidences of left pleural effusion and left atelectasis were lower. This method is therefore clinically useful after esophagectomy.

  7. State waste discharge permit application, 200-E chemical drain field

    Energy Technology Data Exchange (ETDEWEB)

    1994-06-01

    As part of the Hanford Federal Facility Agreement and Consent Order negotiations (Ecology et al. 1994), the US Department of Energy, Richland Operations Office, the US Environmental Protection Agency, and the Washington State Department of Ecology agreed that liquid effluent discharges to the ground on the Hanford Site which affect groundwater or have the potential to affect ground would be subject to permitting under the structure of Chapter 173-216 (or 173-218 where applicable) of the Washington Administrative Code, the State Waste Discharge Permit Program. As a result of this decision, the Washington State Department of Ecology and the US Department of Energy, Richland Operations Office entered into Consent Order No. DE 91NM-177, (Ecology and DOE-RL 1991). The Consent Order No. DE 91NM-177 requires a series of permitting activities for liquid effluent discharges. This document presents the State Waste Discharge Permit (SWDP) application for the 200-E Chemical Drain Field. Waste water from the 272-E Building enters the process sewer line directly through a floor drain, while waste water from the 2703-E Building is collected in two floor drains, (north and south) that act as sumps and are discharged periodically. The 272-E and 2703-E Buildings constitute the only discharges to the process sewer line and the 200-E Chemical Drain Field.

  8. State waste discharge permit application, 200-E chemical drain field

    International Nuclear Information System (INIS)

    1994-06-01

    As part of the Hanford Federal Facility Agreement and Consent Order negotiations (Ecology et al. 1994), the US Department of Energy, Richland Operations Office, the US Environmental Protection Agency, and the Washington State Department of Ecology agreed that liquid effluent discharges to the ground on the Hanford Site which affect groundwater or have the potential to affect ground would be subject to permitting under the structure of Chapter 173-216 (or 173-218 where applicable) of the Washington Administrative Code, the State Waste Discharge Permit Program. As a result of this decision, the Washington State Department of Ecology and the US Department of Energy, Richland Operations Office entered into Consent Order No. DE 91NM-177, (Ecology and DOE-RL 1991). The Consent Order No. DE 91NM-177 requires a series of permitting activities for liquid effluent discharges. This document presents the State Waste Discharge Permit (SWDP) application for the 200-E Chemical Drain Field. Waste water from the 272-E Building enters the process sewer line directly through a floor drain, while waste water from the 2703-E Building is collected in two floor drains, (north and south) that act as sumps and are discharged periodically. The 272-E and 2703-E Buildings constitute the only discharges to the process sewer line and the 200-E Chemical Drain Field

  9. Drainage of shallow peat harvesting areas with pipe drains; Mataloituneen turvekentaen kuivatus putkisalaojilla

    Energy Technology Data Exchange (ETDEWEB)

    Klemetti, V.; Saenkiaho, K. [Vapo Oy, Jyvaeskylae (Finland); Rautiainen, O. [Ojamarkkinointi Oy, Heinola (Finland)

    1996-12-31

    This study aims to develop pipe draining technics in peat harvesting areas, which have been in active use so long time that the remaining peat layer is about one meter thick. The method should be technically and economically feasible as well as environmentally acceptable. Special attention is paid to pipe installation techniques, drain spacing and impacts on watercourses, which receive the drainage waters. After pipe installation the area is monitored by measuring pipe runoffs, water tables, moisture content of peat and quality of drain water

  10. Sampling and analysis plan (SAP) for WESF drains and TK-100 sump

    International Nuclear Information System (INIS)

    Simmons, F.M.

    1998-01-01

    The intent of this project is to determine whether the Waste Encapsulation and Storage Facility (WESF) floor drain piping and the TK-100 sump are free from contamination. TK-100 is currently used as a catch tank to transfer low level liquid waste from WESF to Tank Farms via B Plant. This system is being modified as part of the WESF decoupling since B Plant is being deactivated. As a result of the 1,1,1-trichloroethane (TCA) discovery in TK-100, the associated WESF floor drains and the pit sump need to be sampled. Breakdown constituents have been reviewed and found to be non-hazardous. There are 29 floor drains that tie into a common header leading into the tank. To prevent high exposure during sampling of the drains, TK-100 will be removed into the B Plant canyon and a new tank will be placed in the pit before any floor drain samples are taken. The sump will be sampled prior to TK-100 removal. A sample of the sludge and any liquid in the sump will be taken and analyzed for TCA and polychlorinated biphenyl (PCB). After the sump has been sampled, the vault floor will be flushed. The flush will be transferred from the sump into TK-100. TK-100 will be moved into B Plant. The vault will then be cleaned of debris and visually inspected. If there is no visual indication of TCA or PCB staining, the vault will be painted and a new tank installed. If there is an indication of TCA or PCB from laboratory analysis or staining, further negotiations will be required to determine a path forward. A total of 8 sets of three 40ml samples will be required for all of the floor drains and sump. The sump set will include one 125ml solid sample. The only analysis required will be for TCA in liquids. PCBs will be checked in sump solids only. The Sampling and Analysis Plan (SAP) is written to provide direction for the sampling and analytical activities of the 29 WESF floor drains and the TK-100 sump. The intent of this plan is to define the responsibilities of the various organizations

  11. Safety of peritoneal and pleural drain placement in pediatric stem cell transplant recipients with severe veno-occlusive disease.

    Science.gov (United States)

    Madenci, Arin L; Stetson, Alyssa; Weldon, Christopher B; Lehmann, Leslie E

    2016-08-01

    Hepatic VOD (veno-occlusive disease) is a serious complication of HSCT (hematopoietic stem cell transplantation) and has historically been associated with high mortality. This obstruction to hepatic flow often results in fluid collections in the peritoneal and pleural cavities. Catheter placement to drain ascites or pleural fluid may reduce intra-abdominal hypertension and/or improve respiratory parameters. The safety of these interventions among critically ill, immunocompromised children is unknown. Among 32 HSCT recipients (2000-2012) with severe VOD, we assessed the primary outcome of procedural complication from peritoneal drain placement. Twenty-four (75%) patients underwent peritoneal drain placement. No patient sustained visceral perforation or hemorrhage with drain placement. Overall mortality was 47% (n = 15). The procedure was not associated with increased overall mortality (p > 0.99). Eight (25%) peritoneal drains required replacement for malfunction. Of 24 patients with peritoneal drains, one (4%) patient had a positive culture from ascitic fluid. Eight (25%) patients underwent pleural drain placement. No pleural drain-related procedural complication or infection occurred. Four (50%) of the eight patients with pleural drains had de-escalation in oxygen requirement at drain removal, compared to time of placement. In this study, peritoneal and pleural drains were safe interventions for children with severe VOD. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. Sources of suspended-sediment flux in streams of the chesapeake bay watershed: A regional application of the sparrow model

    Science.gov (United States)

    Brakebill, J.W.; Ator, S.W.; Schwarz, G.E.

    2010-01-01

    We describe the sources and transport of fluvial suspended sediment in nontidal streams of the Chesapeake Bay watershed and vicinity. We applied SPAtially Referenced Regressions on Watershed attributes, which spatially correlates estimated mean annual flux of suspended sediment in nontidal streams with sources of suspended sediment and transport factors. According to our model, urban development generates on average the greatest amount of suspended sediment per unit area (3,928 Mg/km2/year), although agriculture is much more widespread and is the greatest overall source of suspended sediment (57 Mg/km2/year). Factors affecting sediment transport from uplands to streams include mean basin slope, reservoirs, physiography, and soil permeability. On average, 59% of upland suspended sediment generated is temporarily stored along large rivers draining the Coastal Plain or in reservoirs throughout the watershed. Applying erosion and sediment controls from agriculture and urban development in areas of the northern Piedmont close to the upper Bay, where the combined effects of watershed characteristics on sediment transport have the greatest influence may be most helpful in mitigating sedimentation in the bay and its tributaries. Stream restoration efforts addressing floodplain and bank stabilization and incision may be more effective in smaller, headwater streams outside of the Coastal Plain. ?? 2010 American Water Resources Association. No claim to original U.S. government works.

  13. 76 FR 62605 - Virginia Graeme Baker Pool and Spa Safety Act; Interpretation of Unblockable Drain

    Science.gov (United States)

    2011-10-11

    ... the VGB Act defines an ``unblockable drain'' as ``a drain of any size and shape that a human body... intentions. They claim that for this reason, backup systems are necessary, and a swimming pool or spa with a... of an ``unblockable drain,'' at 16 CFR 1450.2(b) and believe it was in error. Regardless of the size...

  14. Interaction of the Bored Sand and Gravel Drain Pile with the Surrounding Compacted Loam Soil and Foundation Raft Taking into Account Rheological Properties of the Loam Soil and Non-Linear Properties of the Drain Pile

    Science.gov (United States)

    Ter-Martirosyan, Z. G.; Ter-Martirosyan, A. Z.; Anzhelo, G. O.; Buslov, A. S.

    2018-01-01

    The task of the interaction of the sand and gravel drain pile with the surrounding loam soil after its preliminary deep compaction and formation of the composite ground cylinder from the drain pile and surrounding compacted loam soil (cells) is considered in the article. It is seen that the subsidence and carrying capacity of such cell considerably depends on physical and mechanical properties of the compacted drain piles and surrounding loam soil as well as their diameter and intercellular distance. The strain-stress state of the cell is considered not taking into account its component elements, but taking into account linear and elastic-plastic properties of the drain pile and creep flow of the surrounding loam soil. It is stated that depending on these properties the distribution and redistribution of the load on a cell takes place from the foundation raft between the drain pile and surrounding soil. Based on the results of task solving the formulas and charts are given demonstrating the ratio of the load between the drain pile and surrounding loam soil in time.

  15. Integrated analysis of hydrological system, use and management. Langueyu stream basin, Tandil, Argentina

    International Nuclear Information System (INIS)

    Ruiz de Galarreta, V.A.; Banda Noriega, R.B.; Barranquero, R.S.; Diaz, A.A.; Rodriguez, C.I.; Miguel, R.E.

    2010-01-01

    This work is aim to hydrological and environmental characterization of Langueyu stream basin, where Tandil city is located. This basin is developed on northern hillside of Tandilia system, in Buenos Aires province, and it drains to NE. There are two different hydrogeological units: crystalline rocks and Cenozoic sediments, which correspond with two hydrolithological characters, fissured and clastic porous, respectively. The population is supplied by groundwater sources. Water exploitation and use were analyzed, according to the growing demands from industrial, agricultural and urban uses. The impacts of intense exploitation were evaluated. High levels of nitrate were corroborated in older wells of the city, which nowadays are in use. The hydrodynamic change in a section of the stream, where it converts to influent, was detected. This disturbance of the natural relation could be a potential source of contamination to the aquifer, due to high charges of industrial and urban effluents which the stream receives. Several population sectors, which have neither a drinking water net nor a sewer system, showed microbiological and chemical water contamination. Other water impact is constituted by several abandoned quarries which have historically received wastes, mainly from foundry industries. In conclusion, water management basin does not aim to sustainable development, due to its lack of integration. It demands the knowledge of hydrological system, according with the goal to avoid water quality degradation and to guarantee its protection. (Author).

  16. Modeling Air Temperature/Water Temperature Relations Along a Small Mountain Stream Under Increasing Urban Influence

    Science.gov (United States)

    Fedders, E. R.; Anderson, W. P., Jr.; Hengst, A. M.; Gu, C.

    2017-12-01

    Boone Creek is a headwater stream of low to moderate gradient located in Boone, North Carolina, USA. Total impervious surface coverage in the 5.2 km2 catchment drained by the 1.9 km study reach increases from 13.4% in the upstream half of the reach to 24.3% in the downstream half. Other markers of urbanization, including culverting, lack of riparian shade vegetation, and bank armoring also increase downstream. Previous studies have shown the stream to be prone to temperature surges on short timescales (minutes to hours) caused by summer runoff from the urban hardscaping. This study investigates the effects of urbanization on the stream's thermal regime at daily to yearly timescales. To do this, we developed an analytical model of daily average stream temperatures based on daily average air temperatures. We utilized a two-part model comprising annual and biannual components and a daily component consisting of a 3rd-order Markov process in order to fit the thermal dynamics of our small, gaining stream. Optimizing this model at each of our study sites in each studied year (78 total site-years of data) yielded annual thermal exchange coefficients (K) for each site. These K values quantify the strength of the relationship between stream and air temperature, or inverse thermal stability. In a uniform, pristine catchment environment, K values are expected to decrease downstream as the stream gains discharge volume and, therefore, thermal inertia. Interannual average K values for our study reach, however, show an overall increase from 0.112 furthest upstream to 0.149 furthest downstream, despite a near doubling of stream discharge between these monitoring points. K values increase only slightly in the upstream, less urban, half of the reach. A line of best fit through these points on a plot of reach distance versus K value has a slope of 2E-6. But the K values of downstream, more urbanized sites increase at a rate of 2E-5 per meter of reach distance, an order of magnitude

  17. Influence of rural land use on streamwater nutrients and their ecological significance

    Science.gov (United States)

    Jarvie, Helen P.; Withers, Paul J. A.; Hodgkinson, Robin; Bates, Adam; Neal, Margaret; Wickham, Heather D.; Harman, Sarah A.; Armstrong, Linda

    2008-02-01

    SummaryConcentrations and loads of N and P fractions were examined for lowland rivers, the Wye and Avon, draining a range of representative agricultural land-use types in two major UK river basins. Data collected over a 2-year period demonstrated important diffuse agricultural source contributions to N and P loads in these rivers. Ground water provided a major source of total dissolved nitrogen (TDN) loads, whereas near-surface sources provided a major contribution to total phosphorus (TP) loads. In terms of aquatic ecology, concentrations of nutrients, at times of eutrophication risk (spring and summer low flows) were of key environmental and management significance. Agricultural diffuse sources provided the major source of long-term P loads across the two basins. However, the results demonstrated the dominance of point-source contributions to TP and SRP concentrations at times of ecological risk. Point sources typically 'tip the balance' of dissolved inorganic P (soluble reactive P, SRP) above the 100 μg l -1 guideline value indicative of eutrophication risk. The significance of point sources for TP and SRP concentrations was shown by (a) the strong correlations between TP, SRP and B concentrations, using B as a tracer of sewage effluent, (b) the dominant contribution of SRP to TP concentrations and (c) the predominant pattern of dilution of SRP and B with flow. The clean Chalk streams draining low intensity grassland in areas of the Avon with sparse human settlement were oligotrophic and P limited with low SRP concentrations under spring and summer baseflows attributable to groundwater sources. The data provide important insights into the ecological functioning of different lowland stream systems. There was evidence of greater SRP losses and N-limitation in a stream which drains a pond system, demonstrating the importance of longer water residence times for biological nutrient uptake.

  18. Nutrients, Dissolved Organic Carbon, Color, and Disinfection Byproducts in Base Flow and Stormflow in Streams of the Croton Watershed, Westchester and Putnam Counties, New York, 2000-02

    Science.gov (United States)

    Heisig, Paul M.

    2009-01-01

    The Croton Watershed is unique among New York City's water-supply watersheds because it has the highest percentages of suburban development (52 percent) and wetland area (6 percent). As the City moves toward filtration of this water supply, there is a need to document water-quality contributions from both human and natural sources within the watershed that can inform watershed-management decisions. Streamwater samples from 24 small (0.1 to 1.5 mi2) subbasins and three wastewater-treatment plants (2000-02) were used to document the seasonal concentrations, values, and formation potentials of selected nutrients, dissolved organic carbon (DOC), color, and disinfection byproducts (DBPs) during stormflow and base-flow conditions. The subbasins were categorized by three types of drainage efficiency and a range of land uses and housing densities. Analyte concentrations in subbasin streams differed in response to the subbasin charateristics. Nutrient concentrations were lowest in undeveloped, forested subbasins that were well drained and increased with all types of development, which included residential, urban commercial/industrial, golf-course, and horse-farm land uses. These concentrations were further modified by subbasin drainage efficiency. DOC, in contrast, was highly dependent on drainage efficiency. Color intensity and DBP formation potentials were, in turn, associated with DOC and thus showed a similar response to drainage efficiency. Every constituent exhibited seasonal changes in concentration. Nutrients. Total (unfiltered) phosphorus (TP), soluble reactive phosphorus (SRP), and nitrate were associated primarily with residential development, urban, golf-course, and horse-farm land uses. Base-flow and stormflow concentrations of the TP, SRP, and nitrate generally increased with increasing housing density. TP and SRP concentrations were nearly an order of magnitude higher in stormflow than in base flow, whereas nitrate concentrations showed little difference

  19. Selected Metals in Sediments and Streams in the Oklahoma Part of the Tri-State Mining District, 2000-2006

    Science.gov (United States)

    Andrews, William J.; Becker, Mark F.; Mashburn, Shana L.; Smith, S. Jerrod

    2009-01-01

    The abandoned Tri-State mining district includes 1,188 square miles in northeastern Oklahoma, southeastern Kansas, and southwestern Missouri. The most productive part of the Tri-State mining district was the 40-square mile part in Oklahoma, commonly referred to as 'the Picher mining district' in north-central Ottawa County, Oklahoma. The Oklahoma part of the Tri-State mining district was a primary producing area of lead and zinc in the United States during the first half of the 20th century. Sulfide minerals of cadmium, iron, lead, and zinc that remained in flooded underground mine workings and in mine tailings on the land surface oxidized and dissolved with time, forming a variety of oxide, hydroxide, and hydroxycarbonate metallic minerals on the land surface and in streams that drain the district. Metals in water and sediments in streams draining the mining district can potentially impair the habitat and health of many forms of aquatic and terrestrial life. Lakebed, streambed and floodplain sediments and/or stream water were sampled at 30 sites in the Oklahoma part of the Tri-State mining district by the U.S. Geological Survey and the Oklahoma Department of Environmental Quality from 2000 to 2006 in cooperation with the U.S. Environmental Protection Agency, and the Quapaw and Seneca-Cayuga Tribes of Oklahoma. Aluminum and iron concentrations of several thousand milligrams per kilogram were measured in sediments collected from the upstream end of Grand Lake O' the Cherokees. Manganese and zinc concentrations in those sediments were several hundred milligrams per kilogram. Lead and cadmium concentrations in those sediments were about 10 percent and 0.1 percent of zinc concentrations, respectively. Sediment cores collected in a transect across the floodplain of Tar Creek near Miami, Oklahoma, in 2004 had similar or greater concentrations of those metals than sediment cores collected at the upstream end of Grand Lake O' the Cherokees. The greatest concentrations of

  20. Modelling Technique for the Assessment of the Sub-Soil Drain for Groundwater Seepage Remediation

    Directory of Open Access Journals (Sweden)

    Tajul Baharuddin Mohamad Faizal

    2017-01-01

    Full Text Available Groundwater simulation technique was carried out for examining the performance of sub-soil drain at problematic site area. Subsoil drain was proposed as one of solution for groundwater seepage occurred at the slope face by reducing groundwater table at Taman Botani Park Kuala Lumpur. The simulation technique used Modular Three-Dimensional Finite Difference Groundwater Flow (MODFLOW software. In transient conditions, the results of simulation showed that heads increases surpass 1 to 2 m from the elevation level of the slope area that caused groundwater seepage on slope face. This study attempt to decrease the heads increase surpass by using different sub-soil drain size in simulation technique. The sub-soil drain capable to decline the heads ranges of 1 to 2 m.

  1. Biodiversity on mire ecosystems and drained peatlands - a basis for environmental peat harvesting; Biologisk maangfald paa myrar och dikad torvmark - underlag foer ett miljoemaessigt torvbruk

    Energy Technology Data Exchange (ETDEWEB)

    Stedingk, Henrik von (Swedish Biodiversity Centre, Uppsala (Sweden))

    2009-07-01

    biodiversity than not drained peatlands. The plant succession following drainage leads to denser vegetation and dominance of forest plants. Often drainage is followed by forestry, leading to even lower nature conservation values. Conservation values on drained peatlands are rarely studied. Potential environments for nature conservation in drained peatlands are: 1) Areas with little drainage influence and preserved mire function. 2) Late forest successions after drainage with deciduous trees and dead wood. 3) Open pine forest or swamp forest that act as refugia for old growth lichens and wood fungi. 4) Pools and stream like older ditches with running water. An inventory focused on conservation values on drained peatlands is recommended. Peat harvesting causes ecosystem shift and species living on the mire disappear. An estimation of biodiversity effects from peat harvesting must include the lost mire, time of exploitation, as well as the after-treatment. A longer time perspective is therefore required when evaluating consequences of peat harvesting. The development of a broader spectra of after-treatment involving biodiversity is essential, as well as a system that guarantees a long term perspective in after-treatment for biodiversity. Methods for evaluating effects on the landscape level from increased peat harvesting are required. Increased peat harvesting on drained peatlands could be in convergence with the Swedish environmental goals, if choice of site and after-treatment is based on landscape analysis focusing on biodiversity

  2. The role of groundwater discharge fluxes on Si:P ratios in a major tributary to Lake Erie.

    Science.gov (United States)

    Maavara, Taylor; Slowinski, Stephanie; Rezanezhad, Fereidoun; Van Meter, Kimberly; Van Cappellen, Philippe

    2018-05-01

    Groundwater discharge can be a major source of nutrients to river systems. Although quantification of groundwater nitrate loading to streams is common, the dependence of surface water silicon (Si) and phosphorus (P) concentrations on groundwater sources has rarely been determined. Additionally, the ability of groundwater discharge to drive surface water Si:P ratios has not been contextualized relative to riverine inputs or in-stream transformations. In this study, we quantify the seasonal dynamics of Si and P cycles in the Grand River (GR) watershed, the largest Canadian watershed draining into Lake Erie, to test our hypothesis that regions of Si-rich groundwater discharge increase surface water Si:P ratios. Historically, both the GR and Lake Erie have been considered stoichiometrically P-limited, where the molar Si:P ratio is greater than the ~16:1 phytoplankton uptake ratio. However, recent trends suggest that eastern Lake Erie may be approaching Si-limitation. We sampled groundwater and surface water for dissolved and reactive particulate Si as well as total dissolved P for 12months within and downstream of a 50-km reach of high groundwater discharge. Our results indicate that groundwater Si:P ratios are lower than the corresponding surface water and that groundwater is a significant source of bioavailable P to surface water. Despite these observations, the watershed remains P-limited for the majority of the year, with localized periods of Si-limitation. We further find that groundwater Si:P ratios are a relatively minor driver of surface water Si:P, but that the magnitude of Si and P loads from groundwater represent a large proportion of the overall fluxes to Lake Erie. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Stream Intermittency Sensors Monitor the Onset and Duration of Stream Flow Along a Channel Network During Storms

    Science.gov (United States)

    Jensen, C.; McGuire, K. J.

    2017-12-01

    Headwater streams are spatially extensive, accounting for a majority of global stream length, and supply downstream water bodies with water, sediment, organic matter, and pollutants. Much of this transmission occurs episodically during storms when stream flow and connectivity are high. Many headwaters are temporary streams that expand and contract in length in response to storms and seasonality. Understanding where and when streams carry flow is critical for conserving headwaters and protecting downstream water quality, but storm events are difficult to study in small catchments. The rise and fall of stream flow occurs rapidly in headwaters, making observation of the entire stream network difficult. Stream intermittency sensors that detect the presence or absence of water can reveal wetting and drying patterns over short time scales. We installed 50 intermittency sensors along the channel network of a small catchment (35 ha) in the Valley and Ridge of southwest Virginia. Previous work shows stream length is highly variable in this shale catchment, as the drainage density spans two orders of magnitude. The sensors record data every 15 minutes for one year to capture different seasons, antecedent moisture conditions, and precipitation rates. We seek to determine whether hysteresis between stream flow and network length occurs on the rising and falling limbs of events and if reach-scale characteristics such as valley width explain spatial patterns of flow duration. Our results indicate reaches with a wide, sediment-filled valley floor carry water for shorter periods of time than confined channel segments with steep valley side slopes. During earlier field mapping surveys, we only observed flow in a few of the tributaries for the wettest conditions mapped. The sensors now show that these tributaries flow more frequently during much smaller storms, but only for brief periods of time (hour). The high temporal sampling resolution of the sensors permits a more realistic

  4. Development of Charge Drain Coatings: Final CRADA Report

    Energy Technology Data Exchange (ETDEWEB)

    Elam, Jeffrey W. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-01-17

    The primary goal of this CRADA project was to develop and optimize tunable resistive coatings prepared by atomic layer deposition (ALD) for use as charge-drain coatings on the KLA-Tencor digital pattern generators (DPGs).

  5. Cryogenic Fuel Tank Draining Analysis Model

    Science.gov (United States)

    Greer, Donald

    1999-01-01

    One of the technological challenges in designing advanced hypersonic aircraft and the next generation of spacecraft is developing reusable flight-weight cryogenic fuel tanks. As an aid in the design and analysis of these cryogenic tanks, a computational fluid dynamics (CFD) model has been developed specifically for the analysis of flow in a cryogenic fuel tank. This model employs the full set of Navier-Stokes equations, except that viscous dissipation is neglected in the energy equation. An explicit finite difference technique in two-dimensional generalized coordinates, approximated to second-order accuracy in both space and time is used. The stiffness resulting from the low Mach number is resolved by using artificial compressibility. The model simulates the transient, two-dimensional draining of a fuel tank cross section. To calculate the slosh wave dynamics the interface between the ullage gas and liquid fuel is modeled as a free surface. Then, experimental data for free convection inside a horizontal cylinder are compared with model results. Finally, cryogenic tank draining calculations are performed with three different wall heat fluxes to demonstrate the effect of wall heat flux on the internal tank flow field.

  6. ENVIRONMENTAL FACTORS INFLUENCING THE VEGETATION IN MIDDLE-SIZED STREAMS IN LATVIA

    Directory of Open Access Journals (Sweden)

    L. GRINBERGA

    2011-04-01

    Full Text Available In this study the species diversity and distribution of macrophytes in 131 surveyed sites of middle-sized streams of Latvia were investigated. The aim of the study was to determine the composition of macrophyte vegetation in Latvian streams in relation to the environmental factors (stream width, water depth, substrate type, shading and flow velocity. On the basis of these factors, five major groups of streams were distinguished representing mutually different typical macrophyte communities – (1 fast flowing streams on gravelly and stony substrate, (2 slow flowing streams on gravelly and stony substrate, (3 fast flowing streams on sandy substrate, (4 slow flowing streams on sandy substrate, and (5 streams with soft, silty substrate. Totally, 47 macrophyte taxa were found in the streams. The most common macrophyte species were Nuphar lutea found in 65% of all sites, followed by Sparganium emersum (64%, S. erectum s.l. (48%, Phalaris arundinacea (50%, Alisma plantago-aquatica (54% and Lemna minor (41%. The highest species richness (22 was found in slow flowing streams with gravelly substrate. Species-poor macrophyte communities were characteristic for fast flowing streams on sandy substrate.

  7. ENVIRONMENTAL FACTORS INFLUENCING THE VEGETATION IN MIDDLE-SIZED STREAMS IN LATVIA

    Directory of Open Access Journals (Sweden)

    L. GRINBERGA

    2011-01-01

    Full Text Available In this study the species diversity and distribution of macrophytes in 131 surveyed sites of middle-sized streams of Latvia were investigated. The aim of the study was to determine the composition of macrophyte vegetation in Latvian streams in relation to the environmental factors (stream width, water depth, substrate type, shading and flow velocity. On the basis of these factors, five major groups of streams were distinguished representing mutually different typical macrophyte communities – (1 fast flowing streams on gravelly and stony substrate, (2 slow flowing streams on gravelly and stony substrate, (3 fast flowing streams on sandy substrate, (4 slow flowing streams on sandy substrate, and (5 streams with soft, silty substrate. Totally, 47 macrophyte taxa were found in the streams. The most common macrophyte species were Nuphar lutea found in 65% of all sites, followed by Sparganium emersum (64%, S. erectum s.l. (48%, Phalaris arundinacea (50%, Alisma plantago-aquatica (54% and Lemna minor (41%. The highest species richness (22 was found in slow flowing streams with gravelly substrate. Species-poor macrophyte communities were characteristic for fast flowing streams on sandy substrate.

  8. Effects of riparian buffer width on wood loading in headwater streams after repeated forest thinning

    Science.gov (United States)

    Julia I. Burton; Deanna H. Olson; Klaus J. Puettmann

    2016-01-01

    Forested riparian buffer zones are used in conjunction with upland forest management, in part, to provide for the recruitment for large wood to streams. Small headwater streams account for the majority of stream networks in many forested regions. Yet, our understanding of how riparian buffer width influences wood dynamics in headwater streams is relatively less...

  9. Postoperative intraabdominal fluid collections : a modified percutaneous drainage method using a surgical drain track

    International Nuclear Information System (INIS)

    Lee, Deok Hee; Kim, Gab Choul; Hwang, Jae Cheol; Yoon, Hyun Ki; Song, Ho Young; Sung, Kyu Bo

    2000-01-01

    In the management of postoperative fluid collection, the conventional percutaneous drainage method can be employed. Because of abdominal incisions and various types of surgical drains and/or T-tubes, the application of this method is not always easy, however. We inserted a drainage catheter through a pre-existing percutaneous track formed by a surgical drain located adjacent to the site of abnormal fluid collection. There was no need to remove the drain nor make an additional puncture in the abdominal wall. A dilator was inserted along the drain, and a guide wire was used to negotiate its intraperitoneal track and reach the accumulated fluid. The procedure was simple and safe. We briefly describe our experience of this modified percutaneous drainage technique, as used in three cases involving postoperative fluid collection. (author)

  10. High performance AlGaN/GaN HEMTs with 2.4 μm source-drain spacing

    International Nuclear Information System (INIS)

    Wang Dongfang; Wei Ke; Yuan Tingting; Liu Xinyu

    2010-01-01

    This paper describes the performance of AlGaN/GaN HEMTs with 2.4 μm source-drain spacing. So far these are the smallest source-drain spacing AlGaN/GaN HEMTs which have been implemented with a domestic wafer and domestic process. This paper also compares their performance with that of 4 μm source-drain spacing devices. The former exhibit higher drain current, higher gain, and higher efficiency. It is especially significant that the maximum frequency of oscillation noticeably increased. (semiconductor integrated circuits)

  11. The routine use of post-operative drains in thyroid surgery: an outdated concept.

    LENUS (Irish Health Repository)

    Prichard, R S

    2010-01-01

    The use of surgical drains in patients undergoing thyroid surgery is standard surgical teaching. Life-threatening complications, arising from post-operative haematomas, mandates their utilization. There is increasing evidence to suggest that this is an outdated practice. This paper determines whether thyroid surgery can be safely performed without the routine use of drains. A retrospective review of patients undergoing thyroid surgery, over a three year period was performed and post-operative complications documented. One hundred and four thyroidectomies were performed. 63 (60.6%) patients had a partial thyroidectomy, 27 (25.9%) had a total thyroidectomy and 14 (13.5%) had a sub-total thyroidectomy. Suction drains were not inserted in any patient. A cervical haematoma did not develop in any patient in this series and no patient required re-operation. There is no evidence to suggest the routine use of surgical drains following uncomplicated thyroid surgery reduces the rate of haematoma formation or re-operation rates and indeed is now unwarranted.

  12. Preliminary design studies of the draining tanks for the Molten Salt Fast Reactor

    International Nuclear Information System (INIS)

    Merle-Lucotte, E.; Allibert, M.; Heuer, D.; Brovchenko, M.; Laureau, A.; Ghetta, V.; Rubiolo, P.

    2014-01-01

    reactor called the Molten Salt Fast Reactor (MSFR). The reference MSFR design is a 3000 MWth reactor with a total fuel salt volume of 18 m3, operated at a mean fuel temperature of 750 deg. C. The first confinement barrier of the reactor includes a salt draining system. In case of a planned reactor shut down or in case of accidents leading to an excessive increase of the temperature in the fuel circuit, the fuel configuration may be changed passively by gravitational draining of the fuel salt in dedicated draining tank located under the reactor and designed to provide adequate reactivity margins while insuring a passive cooling of the fuel salt to extract the residual heat from the short to the long term. The present preliminary assessment of this sub-critical draining system has been performed to identify the physical constraints and to give some orders of magnitude of characteristic time periods (authors)

  13. Drain tube migration into the anastomotic site of an esophagojejunostomy for gastric small cell carcinoma: short report

    OpenAIRE

    Lin Long-Wei; Lo Chiao; Lai Peng-Sheng; Lee Po-Chu

    2010-01-01

    Abstract Background Intraluminal migration of a drain through an anastomotic site is a rare complication of gastric surgery. Case Presentation We herein report the intraluminal migration of a drain placed after a lower esophagectomy and total gastrectomy with Roux-en-Y anastomosis for gastric small cell carcinoma. Persistent drainage was noted 1 month after surgery, and radiographic studies were consistent with drain tube migration. Endoscopy revealed the drain had migrated into the esophagoj...

  14. QUALIFIED VERSION OF MIGRATION: BRAIN DRAIN

    OpenAIRE

    Ayhan GENCLER

    2009-01-01

    Though globalization suggests an international exchange of people besides goods and capital, developed countries often tended to put forward some restrictions on the migration of workers from developed countries. However, there has been an increase in skilled international migration especially during the last two decades. Skilled international migration or brain drain points out the emigration of educated and highly skilled workers. It seems tha...

  15. The carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica

    International Nuclear Information System (INIS)

    Lyons, W.B.; Leslie, D.L.; Harmon, R.S.; Neumann, K.; Welch, K.A.; Bisson, K.M.; McKnight, D.M.

    2013-01-01

    Highlights: ► δ 13 C-DIC reported from McMurdo Dry Valleys, Antarctica, streams. ► Stream water δ 13 C PDB values range −9.4‰ to +5.1‰, largely inorganic in character. ► Atmospheric exchange is the dominant control on δ 13 C-DIC. - Abstract: The McMurdo Dry Valleys region of Antarctica is the largest ice-free region on the continent. This study reports the first C stable isotope measurements for dissolved inorganic C present in ephemeral streams in four dry valleys that flow for four to twelve weeks during the austral summer. One of these valleys, Taylor Valley, has been the focus of the McMurdo Dry Valleys Long-Term Ecological Research (MCM-LTER) program since 1993. Within Taylor Valley, numerous ephemeral streams deliver water to three perennially ice-covered, closed-basin lakes: Lake Fryxell, Lake Hoare, and Lake Bonney. The Onyx River in the Wright Valley, the longest river in Antarctica, flows for 40 km from the Wright Lower Glacier and Lake Brownworth at the foot of the glacier to Lake Vanda. Streamflow in the McMurdo Dry Valley streams is produced primarily from glacial melt, as there is no overland flow. However, hyporheic zone exchange can be a major hydrogeochemical process in these streams. Depending on landscape position, these streams vary in gradient, channel substrate, biomass abundance, and hyporheic zone extent. This study sampled streams from Taylor, Wright, Garwood, and Miers Valleys and conducted diurnal sampling of two streams of different character in Taylor Valley. In addition, transect sampling was undertaken of the Onyx River in Wright Valley. The δ 13 C PDB values from these streams span a range of greater than 14‰, from −9.4‰ to +5.1‰, with the majority of samples falling between −3‰ and +2‰, suggesting that the C stable isotope composition of dissolved C in McMurdo Dry Valley streams is largely inorganic in character. Because there are no vascular plants on this landscape and no groundwater input to these

  16. Evaluation of the necessity for chest drain placement following thoracoscopic wedge resection.

    Science.gov (United States)

    Lu, Ting-Yu; Chen, Jian-Xun; Chen, Pin-Ru; Lin, Yu-Sen; Chen, Chien-Kuang; Kao, Pei-Yu; Huang, Tzu-Ming; Fang, Hsin-Yuan

    2017-05-01

    To evaluate the outcomes of patients who underwent thoracoscopic wedge resection without chest drain placement. The subjects of this retrospective study were 89 patients, who underwent thoracoscopic wedge resection at our hospital between January, 2013 and July, 2015. A total of 45 patients whose underlying condition did not meet the following criteria were assigned to the "chest drain placement group" (group A): peripheral lesions, healthy lung parenchyma, no intraoperative air leaks, hemorrhage or effusion accumulation, and no pleural adhesion. The other 44 patients whose underlying condition met the criteria were assigned to the "no chest drain placement group" (group B). Patient characteristics, specimen data, and postoperative conditions were analyzed and compared between the groups. Group A patients had poorer forced expiratory volume in one second (FEV1) values, less normal spirometric results, significantly higher resected lung volume, a greater maximum tumor-pleura distance, and a larger maximum tumor size. They also had a longer postoperative hospital stay. There was no difference between the two groups in postoperative complications. Avoiding chest drain placement after a thoracoscopic wedge resection appears to be safe and beneficial for patients who have small peripheral lesions and healthy lung parenchyma.

  17. Two different streams form the dorsal visual system: anatomy and functions.

    Science.gov (United States)

    Rizzolatti, Giacomo; Matelli, Massimo

    2003-11-01

    There are two radically different views on the functional role of the dorsal visual stream. One considers it as a system involved in space perception. The other is of a system that codes visual information for action organization. On the basis of new anatomical data and a reconsideration of previous functional and clinical data, we propose that the dorsal stream and its recipient parietal areas form two distinct functional systems: the dorso-dorsal stream (d-d stream) and the ventro-dorsal stream (v-d stream). The d-d stream is formed by area V6 (main d-d extrastriate visual node) and areas V6A and MIP of the superior parietal lobule. Its major functional role is the control of actions "on line". Its damage leads to optic ataxia. The v-d stream is formed by area MT (main v-d extrastriate visual node) and by the visual areas of the inferior parietal lobule. As the d-d stream, v-d stream is responsible for action organization. It, however, also plays a crucial role in space perception and action understanding. The putative mechanisms linking action and perception in the v-d stream is discussed.

  18. Outcome in Chronic Subdural Hematoma After Subdural vs. Subgaleal Drain

    International Nuclear Information System (INIS)

    Ishfaq, A.

    2017-01-01

    Objective: To compare the outcome after surgery for chronic subdural hematoma when the drain is placed in subdural space or subgaleal space. Study Design: Quasi experimental study. Place and Duration of Study: Combined Military Hospital, Lahore, from July 2015 to June 2016. Methodology: Patients with chronic subdural hematoma of both genders and age, ranging between 55 to 85 years, were included. Patients on antiplatelet/anticoagulant therapy and acute on chronic subdural hematoma were excluded. Patients were divided in two equal groups each depending on whether drain was placed in subgaleal space (Group 1), and subdual space (Group 2), (n=31 patients each). Patients were positioned flat in bed after surgery. Clinical and radiological parameters and clinical outcome were compared between the two groups. Statistical test with significance of p <0.05 was utilized using Statistical Package of Social Sciences (SPSS version 17). Results: Median age of the 62 patients was 72 +-12.5 years. Headache was the most common symptom reported in both groups, (n=47,75.8%) patients. Median thickness of hematoma was 15 +-6.5 mm. Patients with subdural drain placement had more complications such as pneumocephalus 11 (35.4%) vs. 6 (19.3%), and intracerebral hemorrhage 4 (12.9%) vs. 2 (6.4%). Clinical outcome was good in both groups 27 (87%) in Group 1 and 28 (90%) in Group 2. Conclusion: Patients of both groups had good outcome after surgery. Complications like pneumocephalus and intracerebral hemorrhage were more common in subdural location of drain, though not reaching statistically significance level to favor one technique over another. (author)

  19. Breakthrough of two pesticides into tile drain and shallow groundwater: comparison of tile drain reaction and soil profiles within a field scale irrigation experiment

    Science.gov (United States)

    Klaus, Julian; Zehe, Erwin; Elsner, Martin; Palm, Juliane; Schneider, Dorothee; Schröder, Boris; Steinbeiss, Sibylle; West, Stephanie

    2010-05-01

    Preferential flow in macropores is a key process which strongly affects infiltration and may cause rapid transport of pesticides into depths of 80 to 150 cm. At these depths they experience a much slower degradation, may leach into shallow groundwater or enter a tile-drain and are transported into surface water bodies. Therefore, preferential transport might be an environmental problem, if the topsoil is bypassed, which has been originally thought to act as a filter to protect the subsoil and shallow groundwater. To investigate the behaviour of two pesticides with different chemical characteristics and to compare their transport behaviour in soil and into the tile drain an irrigation experiment was performed on a 400 m² field site. The experimental plot is located in the Weiherbach valley, south-west Germany, which basic geology consists of Loess and Keuper layers, the soil at the test site is a gleyic Colluvisol. The distance of the irrigation site to the Weiherbach brook is approximately 12 m, the field is drained with a tile-drain in about 1.2 m depth and shows discharge over the entire year. Three hours before the irrigation started, the farmer applied a pesticide solution consisting of Isoproturon (80 g) and Flufenacet (20 g) (IPU and FLU) according to conventional agricultural practice on the field plot. The irrigation took place in three time blocks (80 min, 60 min, 80 min) with in total 33.6 mm of precipitation. During the first block 1600 g of Bromide were mixed in the irrigation water. The drainage outlet was instrumented with a pressure probe. About 50 water samples ware taken during the experimental day, and several samples more the days after the experiment. They were analysed for the pesticides, bromide and water isotopes. In the two days after the experiment three soil profiles were excavated and soil samples were taken on a 10x10 cm² scheme. One week after the experiment two additional profiles were excavated. The soil was analysed for IPU, FLU

  20. Replacement of the drain system of secondary circuit at Monju

    International Nuclear Information System (INIS)

    Itoh, Kenji; Onuki, Koji; Tomobe, Katsuma; Taniyama, Sadami

    2003-01-01

    Monju is as a Japan's prototype fast breeder reactor cooled by liquid sodium. In the course of power buildup tests, the sodium leakage accident broke out on 8th December 1995. Though Monju has been already equipped with countermeasure systems against the sodium leakage accident, some additional improvements will be taken in order to reduce the damage by the leaked sodium when another leakage accident should recur. The most characteristic work is the drain system modification that leads to shorten the drain time and to reduce the quantity of leaked sodium in the event of sodium leakage. (author)

  1. Drained Lava Tubes and Lobes From Eocretaceous Paraná-Etendeka Province, Brazil

    Science.gov (United States)

    Waichel, B. L.; Lima, E. F. D.; Mouro, L. D.; Briske, D. R.; Tratz, E. B.

    2017-12-01

    orientation of the Ponta Grossa swarm feeder dikes (NW). The drained lava lobes show variable dimensions, typical lobate morphology and form sub-crustal caves. The smaller are up to 1.5 m high, 10 m wide and 15 long; the majors are up to 6m high, 20 m wide and 25 m long. Collapsed roofs are observed in big caves and collapses of overlying thin pahoehoe lobes are common in smaller lobes.

  2. The quality of our Nation's waters-Nutrients in the Nation's streams and groundwater, 1992-2004

    Science.gov (United States)

    Dubrovsky, N.M.; Burow, K.R.; Clark, G.M.; Gronberg, J.M.; Hamilton, P.A.; Hitt, K.J.; Mueller, D.K.; Munn, M.D.; Nolan, B.T.; Puckett, L.J.; Rupert, M.G.; Short, T.M.; Spahr, N.E.; Sprague, L.A.; Wilber, W.G.

    2010-01-01

    National Findings and Their Implications Although the use of artificial fertilizer has supported increasing food production to meet the needs of a growing population, increases in nutrient loadings from agricultural and, to a lesser extent, urban sources have resulted in nutrient concentrations in many streams and parts of aquifers that exceed standards for protection of human health and (or) aquatic life, often by large margins. Do NAWQA findings substantiate national concerns for aquatic and human health? National Water-Quality Assessment (NAWQA) findings indicate that nutrient concentrations in streams and groundwater in basins with significant agricultural or urban development are substantially greater than naturally occurring or ?background? levels. For example, median concentrations of total nitrogen and phosphorus in agricultural streams are about 6 times greater than background levels. Findings also indicate that concentrations in streams routinely were 2 to 10 times greater than regional nutrient criteria recommended by the U.S. Environmental Protection Agency (USEPA) to protect aquatic life. Such large differences in magnitude suggest that significant reductions in sources of nutrients, as well as greater use of land management strategies to reduce the transport of nutrients to streams, are needed to meet recommended criteria for streams draining areas with significant agricultural and urban development. Nitrate concentrations above the Federal drinking-water standard-or Maximum Contaminant Level (MCL)-of 10 milligrams per liter (mg/L, as nit-ogen) are relatively uncommon in samples from streams used for drinking water or from relatively deep aquifers; the MCL is exceeded, however, in more than 20 percent of shallow (less than 100 feet below the water table) domestic wells in agricultural areas. This finding raises concerns for human health in rural agricultural areas where shallow groundwater is used for domestic supply and may warn of future

  3. QUALIFIED VERSION OF MIGRATION: BRAIN DRAIN

    OpenAIRE

    Gencler, Ayhan

    2009-01-01

    Though globalization suggests an international exchange of people besides goods and capital, developed countries often tended to put forward some restrictions on the migration of workers from developed countries. However, there has been an increase in skilled international migration especially during the last two decades. Skilled international migration or brain drain points out the emigration of educated and highly skilled workers. It seems that, in general, developing or underdeveloped...

  4. The Stream-Catchment (StreamCat) and Lake-Catchment ...

    Science.gov (United States)

    Background/Question/MethodsLake and stream conditions respond to both natural and human-related landscape features. Characterizing these features within contributing areas (i.e., delineated watersheds) of streams and lakes could improve our understanding of how biological conditions vary spatially and improve the use, management, and restoration of these aquatic resources. However, the specialized geospatial techniques required to define and characterize stream and lake watersheds has limited their widespread use in both scientific and management efforts at large spatial scales. We developed the StreamCat and LakeCat Datasets to model, predict, and map the probable biological conditions of streams and lakes across the conterminous US (CONUS). Both StreamCat and LakeCat contain watershed-level characterizations of several hundred natural (e.g., soils, geology, climate, and land cover) and anthropogenic (e.g., urbanization, agriculture, mining, and forest management) landscape features for ca. 2.6 million stream segments and 376,000 lakes across the CONUS, respectively. These datasets can be paired with field samples to provide independent variables for modeling and other analyses. We paired 1,380 stream and 1,073 lake samples from the USEPAs National Aquatic Resource Surveys with StreamCat and LakeCat and used random forest (RF) to model and then map an invertebrate condition index and chlorophyll a concentration, respectively. Results/ConclusionsThe invertebrate

  5. Modified APEX model for Simulating Macropore Phosphorus Contributions to Tile Drains.

    Science.gov (United States)

    Ford, William I; King, Kevin W; Williams, Mark R; Confesor, Remegio B

    2017-11-01

    The contribution of macropore flow to phosphorus (P) loadings in tile-drained agricultural landscapes remains poorly understood at the field scale, despite the recognized deleterious impacts of contaminant transport via macropore pathways. A new subroutine that couples existing matrix-excess and matrix-desiccation macropore flow theory and a modified P routine is implemented in the Agricultural Policy Environmental eXtender (APEX) model. The original and modified formulation were applied and evaluated for a case study in a poorly drained field in Western Ohio with 31 months of surface and subsurface monitoring data. Results highlighted that a macropore subroutine in APEX improved edge-of-field discharge calibration and validation for both tile and total discharge from satisfactory and good, respectively, to very good and improved dissolved reactive P load calibration and validation statistics for tile P loads from unsatisfactory to very good. Output from the calibrated macropore simulations suggested median annual matrix-desiccation macropore flow contributions of 48% and P load contributions of 43%, with the majority of loading occurring in winter and spring. While somewhat counterintuitive, the prominence of matrix-desiccation macropore flow during seasons with less cracking reflects the importance of coupled development of macropore pathways and adequate supply of the macropore flow source. The innovative features of the model allow for assessments of annual macropore P contributions to tile drainage and has the potential to inform P site assessment tools. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  6. Channel response in a semiarid stream to removal of tamarisk and Russian olive

    Science.gov (United States)

    Jaeger, Kristin L.; Wohl, Ellen

    2011-02-01

    We report observed short-term (3 years) channel adjustment in an incised, semiarid stream to the removal of invasive plants, tamarisk (Tamarix spp.) and Russian olive (Elaeagnus angustifolia) by (1) removing the above-ground portion of the plant (cut-stump method) and (2) removing the entire plant (whole-plant method). The stream flows through Canyon de Chelly National Monument in Arizona, USA., draining an ˜1500 km2 catchment. Average channel width is 13 m; average thalweg depth is 2-3 m, although channel banks exceed 8 m locally. Channels adjusted primarily through widening, with significantly larger changes occurring in whole-plant removal reaches; however, neither plant removal method elicited large-scale bank destabilization, and the channels remained entrenched. Particular site conditions limiting large-scale destabilization include the absence of sufficient streamflow magnitudes, the presence of clay layers at the bank toe, the remaining presence of native vegetation, and the entrenched morphology. Our findings serve as a cautionary note regarding the temporal and spatial variability in channel response to invasive plant removal and underscore the importance of considering site-specific conditions in future restoration projects that include invasive plant removal.

  7. Data Used in Analyses of Trends, and Nutrient and Suspended-Sediment Loads for Streams in the Southeastern United States, 1973-2005

    Science.gov (United States)

    Staub, Erik L.; Peak, Kelly L.; Tighe, Kirsten C.; Sadorf, Eric M.; Harned, Douglas A.

    2010-01-01

    Water-quality data from selected surface-water monitoring sites in the Southeastern United States were assessed for trends in concentrations of nutrients, suspended sediment, and major constituents and for in-stream nutrient and suspended-sediment loads for the period 1973-2005. The area of interest includes river basins draining into the southern Atlantic Ocean, the Gulf of Mexico, and the Tennessee River-drainage basins in Hydrologic Regions 03 (South Atlantic - Gulf) and 06 (Tennessee). This data assessment is related to studies of several major river basins as part of the U.S. Geological Survey National Water-Quality Assessment Program, which was designed to assess national water-quality trends during a common time period (1993-2004). Included in this report are data on which trend tests could be performed from 44 U.S. Geological Survey National Water Information System (NWIS) sampling sites. The constituents examined include major ions, nutrients, and suspended sediment; the physical properties examined include pH, specific conductance, dissolved oxygen, and streamflow. Also included are data that were tested for trends from an additional 290 sites from the U.S. Environmental Protection Agency Storage and Retrieval (STORET) database. The trend analyses of the STORET data were limited to total nitrogen and total phosphorus concentrations. Data from 48 U.S. Geological Survey NWIS sampling sites with sufficient water-quality and continuous streamflow data for estimating nutrient and sediment loads are included. The methods of data compilation and modification used prior to performing trend tests and load estimation are described. Results of the seasonal Kendall trend test and the Tobit trend test are given for the 334 monitoring sites, and in-stream load estimates are given for the 48 monitoring sites. Basin characteristics are provided, including regional landscape variables and agricultural nutrient sources (annual variations in cropping and fertilizer use

  8. Streaming Pool: reuse, combine and create reactive streams with pleasure

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    When connecting together heterogeneous and complex systems, it is not easy to exchange data between components. Streams of data are successfully used in industry in order to overcome this problem, especially in the case of "live" data. Streams are a specialization of the Observer design pattern and they provide asynchronous and non-blocking data flow. The ongoing effort of the ReactiveX initiative is one example that demonstrates how demanding this technology is even for big companies. Bridging the discrepancies of different technologies with common interfaces is already done by the Reactive Streams initiative and, in the JVM world, via reactive-streams-jvm interfaces. Streaming Pool is a framework for providing and discovering reactive streams. Through the mechanism of dependency injection provided by the Spring Framework, Streaming Pool provides a so called Discovery Service. This object can discover and chain streams of data that are technologically agnostic, through the use of Stream IDs. The stream to ...

  9. Establishment and application of the estimation model for pollutant concentrfation in agriculture drain

    Science.gov (United States)

    Li, Qiangkun; Hu, Yawei; Jia, Qian; Song, Changji

    2018-02-01

    It is the key point of quantitative research on agricultural non-point source pollution load, the estimation of pollutant concentration in agricultural drain. In the guidance of uncertainty theory, the synthesis of fertilization and irrigation is used as an impulse input to the farmland, meanwhile, the pollutant concentration in agricultural drain is looked as the response process corresponding to the impulse input. The migration and transformation of pollutant in soil is expressed by Inverse Gaussian Probability Density Function. The law of pollutants migration and transformation in soil at crop different growth periods is reflected by adjusting parameters of Inverse Gaussian Distribution. Based on above, the estimation model for pollutant concentration in agricultural drain at field scale was constructed. Taking the of Qing Tong Xia Irrigation District in Ningxia as an example, the concentration of nitrate nitrogen and total phosphorus in agricultural drain was simulated by this model. The results show that the simulated results accorded with measured data approximately and Nash-Sutcliffe coefficients were 0.972 and 0.964, respectively.

  10. Interaction between stream temperature, streamflow, and groundwater exchanges in alpine streams

    Science.gov (United States)

    Constantz, James E.

    1998-01-01

    Four alpine streams were monitored to continuously collect stream temperature and streamflow for periods ranging from a week to a year. In a small stream in the Colorado Rockies, diurnal variations in both stream temperature and streamflow were significantly greater in losing reaches than in gaining reaches, with minimum streamflow losses occurring early in the day and maximum losses occurring early in the evening. Using measured stream temperature changes, diurnal streambed infiltration rates were predicted to increase as much as 35% during the day (based on a heat and water transport groundwater model), while the measured increase in streamflow loss was 40%. For two large streams in the Sierra Nevada Mountains, annual stream temperature variations ranged from 0° to 25°C. In summer months, diurnal stream temperature variations were 30–40% of annual stream temperature variations, owing to reduced streamflows and increased atmospheric heating. Previous reports document that one Sierra stream site generally gains groundwater during low flows, while the second Sierra stream site may lose water during low flows. For August the diurnal streamflow variation was 11% at the gaining stream site and 30% at the losing stream site. On the basis of measured diurnal stream temperature variations, streambed infiltration rates were predicted to vary diurnally as much as 20% at the losing stream site. Analysis of results suggests that evapotranspiration losses determined diurnal streamflow variations in the gaining reaches, while in the losing reaches, evapotranspiration losses were compounded by diurnal variations in streambed infiltration. Diurnal variations in stream temperature were reduced in the gaining reaches as a result of discharging groundwater of relatively constant temperature. For the Sierra sites, comparison of results with those from a small tributary demonstrated that stream temperature patterns were useful in delineating discharges of bank storage following

  11. Disintegration of a marine-based ice stream - evidence from the Norwegian Channel, north-eastern North Sea

    Science.gov (United States)

    Morén, Björn M.; Petter Sejrup, Hans; Hjelstuen, Berit O.; Haflidason, Haflidi; Schäuble, Cathrina; Borge, Marianne

    2014-05-01

    The Norwegian Channel Ice Stream repeatedly drained large part of the Fennoscandian Ice Sheet through Mid and Late Pleistocene glacial stages. During parts of Marine Isotope Stages 2 and 3, glacial ice from Fennoscandia and the British Isles coalesced in the central North Sea and the Norwegian Channel Ice Stream reached the shelf edge on multiple occasions. Through the last decades a large amount of acoustic and sediment core data have been collected from the Norwegian Channel, providing a good background for studies focussing on stability- and development-controlling parameters for marine-based ice streams, the retreat rate of the Norwegian Channel Ice Stream, and the behaviour of the Fennoscandian Ice Sheet. Further, this improved understanding can be used to develop more accurate numerical climate models and models which can be used to model ice-sheet behaviour of the past as well as the future. This study presents new acoustic records and data from sediment cores which contribute to a better understanding of the retreat pattern and the retreat rate of the last ice stream that occupied the Norwegian Channel. From bathymetric and TOPAS seismic data, mega-scale glacial lineations, grounding-zone wedges, and end moraines have been mapped, thereby allowing us to reconstruct the pro- and subglacial conditions at the time of the creation of these landforms. It is concluded that the whole Norwegian Channel was deglaciated in just over 1 000 years and that for most of this time the ice margin was located at positions reflected by depositional grounding-zone wedges. Further work will explore the influence of channel shape and feeding of ice from western Norwegian fjords on this retreat pattern through numerical modelling.

  12. Viscosity-dependent drain current noise of AlGaN/GaN high electron mobility transistor in polar liquids

    International Nuclear Information System (INIS)

    Fang, J. Y.; Hsu, C. P.; Kang, Y. W.; Fang, K. C.; Kao, W. L.; Yao, D. J.; Chen, C. C.; Li, S. S.; Yeh, J. A.; Wang, Y. L.; Lee, G. Y.; Chyi, J. I.; Hsu, C. H.; Huang, Y. F.; Ren, F.

    2013-01-01

    The drain current fluctuation of ungated AlGaN/GaN high electron mobility transistors (HEMTs) measured in different fluids at a drain-source voltage of 0.5 V was investigated. The HEMTs with metal on the gate region showed good current stability in deionized water, while a large fluctuation in drain current was observed for HEMTs without gate metal. The fluctuation in drain current for the HEMTs without gate metal was observed and calculated as standard deviation from a real-time measurement in air, deionized water, ethanol, dimethyl sulfoxide, ethylene glycol, 1,2-butanediol, and glycerol. At room temperature, the fluctuation in drain current for the HEMTs without gate metal was found to be relevant to the dipole moment and the viscosity of the liquids. A liquid with a larger viscosity showed a smaller fluctuation in drain current. The viscosity-dependent fluctuation of the drain current was ascribed to the Brownian motions of the liquid molecules, which induced a variation in the surface dipole of the gate region. This study uncovers the causes of the fluctuation in drain current of HEMTs in fluids. The results show that the AlGaN/GaN HEMTs may be used as sensors to measure the viscosity of liquids within a certain range of viscosity

  13. A Drain Current Model Based on the Temperature Effect of a-Si:H Thin-Film Transistors

    International Nuclear Information System (INIS)

    Qiang Lei; Yao Ruo-He

    2012-01-01

    Based on the differential Ohm's law and Poisson's equation, an analytical model of the drain current for a-Si:H thin-film transistors is developed. This model is proposed to elaborate the temperature effect on the drain current, which indicates that the drain current is linear with temperature in the range of 290-360 K, and the results fit well with the experimental data

  14. Gauze Impregnated With Quaternary Ammonium Salt Reduces Bacterial Colonization of Surgical Drains After Breast Reconstruction.

    Science.gov (United States)

    Strong, Amy L; Wolfe, Emily T; Shank, Nina; Chaffin, Abigail E; Jansen, David A

    2018-06-01

    Surgical site infection after breast reconstruction is associated with increased length of hospital stay, readmission rates, cost, morbidity, and mortality. Identifying methods to reduce surgical site infection without the use of antibiotics may be beneficial at reducing antimicrobial resistance, reserving the use of antibiotics for more severe cases. Quaternary ammonium salts have previously been shown to be a safe and effective antimicrobial agent in the setting of in vitro and in vivo animal experiments. A retrospective study was conducted to investigate the antimicrobial properties of a quaternary ammonium salt, 3-trimethoxysilyl propyldimethyloctadecyl ammonium chloride (QAS-3PAC; Bio-spear), at reducing surgical drain site colonization and infection after breast reconstruction (deep inferior epigastric perforator flap reconstruction or tissue expander placement). Twenty patients were enrolled, with 14 surgical drains covered with nonimpregnated gauze and 17 surgical drains covered with QAS-3PAC impregnated gauze, for the purposes of investigating bacterial colonization. Antibiotic sensitivity analysis was also conducted when bacterial cultures were positive. The overall incidence of bacterial colonization of surgical drains was lower in the treatment group compared with the control group (17.6% vs 64.3%, respectively; P = 0.008). QAS-3PAC impregnated gauze reduced the incidence of bacterial colonization of surgical drains during the first (0.0% vs 33.3%) and second (33.3% vs 87.5%; P = 0.04) postoperative week. Furthermore, no enhanced antibiotic resistance was noted on drains treated with QAS-3PAC impregnated gauze. The results of this study suggest that QAS-3PAC impregnated gauze applied over surgical drains may be an effective method for reducing the incidence of bacterial colonization.

  15. Surface runoff and subsurface tile drain losses of neonicotinoids and companion herbicides at edge-of-field.

    Science.gov (United States)

    Chrétien, François; Giroux, Isabelle; Thériault, Georges; Gagnon, Patrick; Corriveau, Julie

    2017-05-01

    With their application as seed coatings, the use of neonicotinoid insecticides increased dramatically during the last decade. They are now frequently detected in aquatic ecosystems at concentrations susceptible to harm aquatic invertebrates at individual and population levels. This study intent was to document surface runoff and subsurface tile drain losses of two common neonicotinoids (thiamethoxam and clothianidin) compared to those of companion herbicides (atrazine, glyphosate, S-metolachlor and mesotrione) at the edge of a 22.5-ha field under a corn-soybean rotation. A total of 14 surface runoff and tile drain discharge events were sampled over two years. Events and annual unit mass losses were computed using flow-weighted concentrations and total surface runoff and tile drain flow volumes. Detection frequencies close to 100% in edge-of-field surface runoff and tile drain water samples were observed for thiamethoxam and clothianidin even though only thiamethoxam had been applied in the first year. In 2014, thiamethoxam median concentrations in surface runoff and tile drain samples were respectively 0.46 and 0.16 μg/L, while respective maximum concentrations of 2.20 and 0.44 μg/L were measured in surface runoff and tile drain samples during the first post-seeding storm event. For clothianidin, median concentrations in surface runoff and tile drain samples were 0.02 and 0.01, μg/L, and respective maximum concentrations were 0.07 μg/L and 0.05 μg/L. Surface runoff and tile drain discharge were key transport mechanisms with similar contributions of 53 and 47% of measured mass losses, respectively. Even if thiamethoxam was applied at a relatively low rate and had a low mass exportation value (0.3%), the relative toxicity was one to two orders of magnitude higher than those of the other chemicals applied in 2014 and 2015. Companion herbicides, except glyphosate in tile drains, exceeded their water quality guideline during one sampling campaign after

  16. Method of making a self-aligned schottky metal semi-conductor field effect transistor with buried source and drain

    International Nuclear Information System (INIS)

    Bol, I.

    1984-01-01

    A semi-conductor structure and particularly a high speed VLSI Self-Aligned Schottky Metal Semi-Conductor Field Effect Transistor with buried source and drain, fabricated by the ion implantation of source and drain areas at a predetermined range of depths followed by very localized laser annealing to electrically reactivate the amorphous buried source and drain areas thereby providing effective vertical separation of the channel from the buried source and drain respectively. Accordingly, spatial separations between the self-aligned gate-to-drain, and gate-to-source can be relatively very closely controlled by varying the doping intensity and duration of the implantation thereby reducing the series resistance and increasing the operating speed

  17. Relation between Streaming Potential and Streaming Electrification Generated by Streaming of Water through a Sandwich-type Cell

    OpenAIRE

    Maruyama, Kazunori; Nikaido, Mitsuru; Hara, Yoshinori; Tanizaki, Yoshie

    2012-01-01

    Both streaming potential and accumulated charge of water flowed out were measured simultaneously using a sandwich-type cell. The voltages generated in divided sections along flow direction satisfied additivity. The sign of streaming potential agreed with that of streaming electrification. The relation between streaming potential and streaming electrification was explained from a viewpoint of electrical double layer in glass-water interface.

  18. Rare bile duct anomaly: B3 duct draining to gallbladder

    Directory of Open Access Journals (Sweden)

    Seung Eun Lee

    2016-01-01

    Full Text Available A 10-year-old girl presented with recurrent right upper abdominal pain and dyspepsia. Magnetic resonance cholangiopancreatography revealed a dilated common channel of intrahepatic bile duct of segment 3 (B3 and segment 4 (B4 drained into the gallbladder directly. The patient underwent laparoscopic cholecystectomy and Roux-en Y hepaticojejunostomy (B3-jejunostomy. Among the anatomical variability of the biliary system, the cholecystohepatic ducts are controversial in existence and incidence. We report a very rare variant of a cholecystohepatic duct in which the B3 duct drained into gallbladder directly and to the best of our knowledge this is the first report.

  19. The fabrication of carbon nanotube field-effect transistors with semiconductors as the source and drain contact materials.

    Science.gov (United States)

    Xiao, Z; Camino, F E

    2009-04-01

    Sb(2)Te(3) and Bi(2)Te(2)Se semiconductor materials were used as the source and drain contact materials in the fabrication of carbon nanotube field-effect transistors (CNTFETs). Ultra-purified single-walled carbon nanotubes (SWCNTs) were ultrasonically dispersed in N-methyl pyrrolidone solvent. Dielectrophoresis was used to deposit and align SWCNTs for fabrication of CNTFETs. The Sb(2)Te(3)- and Bi(2)Te(2)Se-based CNTFETs demonstrate p-type metal-oxide-silicon-like I-V curves with high on/off drain-source current ratio at large drain-source voltages and good saturation of drain-source current with increasing drain-source voltage. The fabrication process developed is novel and has general meaning, and could be used for the fabrication of SWCNT-based integrated devices and systems with semiconductor contact materials.

  20. Xpand chest drain: assessing equivalence to current standard ...

    African Journals Online (AJOL)

    The Xpand chest drain is an external medical device made of plastic that incorporates a fluid reservoir, a one-way valve and an air-leak detection system ... conect ed to a 2 000 ml drainage bag) prevents exposure of body fluids to nursing staff.

  1. Drains after Thyroidectomy for Benign Thyroid Disorders; Are ...

    African Journals Online (AJOL)

    Prophylactic drainage after thyroidectomy has been a regular practice at Kenyatta National Hospital( KNH). This has been ... stay and post-operative pain. Introduction. Prophylactic drains are still regularly used in ..... Total versus subtotal thyroidectomy for the management of benign multinodular goiter in an endemic region.

  2. Monitoring stream temperatures—A guide for non-specialists

    Science.gov (United States)

    Heck, Michael P.; Schultz, Luke D.; Hockman-Wert, David; Dinger, Eric C.; Dunham, Jason B.

    2018-04-19

    Executive SummaryWater temperature influences most physical and biological processes in streams, and along with streamflows is a major driver of ecosystem processes. Collecting data to measure water temperature is therefore imperative, and relatively straightforward. Several protocols exist for collecting stream temperature data, but these are frequently directed towards specialists. This document was developed to address the need for a protocol intended for non-specialists (non-aquatic) staff. It provides specific step-by-step procedures on (1) how to launch data loggers, (2) check the factory calibration of data loggers prior to field use, (3) how to install data loggers in streams for year-round monitoring, (4) how to download and retrieve data loggers from the field, and (5) how to input project data into organizational databases.

  3. Whole ecosystem approaches for assessing the coupling of N and P cycles in small streams

    Science.gov (United States)

    Schade, J. D.; Thomas, S. A.; Seybold, E. C.; Drake, T.; Lewis, K.; MacNeill, K.; Zimov, N.

    2010-12-01

    The most pressing environmental problems faced by society are manifestations of changes in biogeochemical cycles. The urgency of mitigating these problems has brought into sharp focus the need for a stronger mechanistic understanding of the factors that control biogeochemical cycles and how these factors affect multiple elements. Our overarching goal is to assess the strength of coupling between carbon, nitrogen, and phosphorus cycles in small headwater streams, including streams draining small watersheds in Northern California and the East Siberian Arctic. We have used a range of whole ecosystem approaches, rooted in nutrient spiraling theory, including plateau and pulsed nutrient enrichment experiments at a range of N:P ratios in heterotrophic and autotrophic streams. We use these experiments to calculate changes in nutrient spiraling metrics in response to changes in absolute and relative supply of N and P, and we use these results to infer the strength of the linkage between N and P cycles. In all California study streams, ecological processes are N limited, and we have observed significant changes in the strength of N and P coupling depending on position along the stream network. In small heterotrophic streams, addition of N caused significant increases in P uptake, while P had little influence on N. In larger autotrophic streams, N and P were only weakly coupled, which we attributed to a shift towards dominance of uptake by algae rather than heterotrophic bacteria, which is associated with differences in cellular structures. In addition, we have observed a small but consistent reduction in P uptake at high N:P of supply in autotrophic streams, which we speculate may indicate a suppression of N fixers at high N supply. In the Arctic, we have observed less consistency in the response of streams to nutrient enrichment, with some streams showing very little change in N or P uptake with changes in supply N:P, and others showing a decrease in N uptake in response

  4. Accounting for the risks of phosphorus losses through tile drains in a phosphorus index.

    Science.gov (United States)

    Reid, D Keith; Ball, Bonnie; Zhang, T Q

    2012-01-01

    Tile drainage systems have been identified as a significant conduit for phosphorus (P) losses to surface water, but P indices do not currently account for this transport pathway in a meaningful way. Several P indices mention tile drains, but most account for either the reduction in surface runoff or the enhanced transport through tiles rather than both simultaneously. A summary of the current state of how tile drains are accounted for within P indices is provided, and the challenges in predicting the risk of P losses through tile drains that are relative to actual losses are discussed. A framework for a component P Index is described, along with a proposal to incorporate predictions of losses through tile drains as a component within this framework. Options for calibrating and testing this component are discussed. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  5. Multi-stream portrait of the Cosmic web

    Science.gov (United States)

    Ramachandra, Nesar; Shandarin, Sergei

    2016-03-01

    We report the results of the first study of the multi-stream environment of dark matter haloes in cosmological N-body simulations in the ΛCDM cosmology. The full dynamical state of dark matter can be described as a three-dimensional sub-manifold in six-dimensional phase space - the dark matter sheet. In our study we use a Lagrangian sub-manifold x = x (q , t) (where x and q are co-moving Eulerian and Lagrangian coordinates respectively), which is dynamically equivalent to the dark matter sheet but is more convenient for numerical analysis. Our major results can be summarized as follows. At the resolution of the simulation, the cosmic web represents a hierarchical structure: each halo is embedded in the filamentary framework of the web predominantly at the filament crossings, and each filament is embedded in the wall like fabric of the web at the wall crossings. Locally, each halo or sub-halo is a peak in the number of streams field. The number of streams in the neighbouring filaments is higher than in the neighbouring walls. The walls are regions where number of streams is equal to three or a few. Voids are uniquely defined by the local condition requiring to be a single-stream flow region.

  6. Contributions of Phosphorus from Groundwater to Streams in the Piedmont, Blue Ridge, and Valley and Ridge Physiographic Provinces, Eastern United States

    Science.gov (United States)

    Denver, Judith M.; Cravotta,, Charles A.; Ator, Scott W.; Lindsey, Bruce D.

    2011-01-01

    Phosphorus from natural and human sources is likely to be discharged from groundwater to streams in certain geochemical environments. Water-quality data collected from 1991 through 2007 in paired networks of groundwater and streams in different hydrogeologic and land-use settings of the Piedmont, Blue Ridge, and Valley and Ridge Physiographic Provinces in the eastern United States were compiled and analyzed to evaluate the sources, fate, and transport of phosphorus. The median concentrations of phosphate in groundwater from the crystalline and siliciclastic bedrock settings (0.017 and 0.020 milligrams per liter, respectively) generally were greater than the median for the carbonate setting (less than 0.01 milligrams per liter). In contrast, the median concentrations of dissolved phosphate in stream base flow from the crystalline and siliciclastic bedrock settings (0.010 and 0.014 milligrams per liter, respectively) were less than the median concentration for base-flow samples from the carbonate setting (0.020 milligrams per liter). Concentrations of phosphorus in many of the stream base-flow and groundwater samples exceeded ecological criteria for streams in the region. Mineral dissolution was identified as the dominant source of phosphorus in the groundwater and stream base flow draining crystalline or siliciclastic bedrock in the study area. Low concentrations of dissolved phosphorus in groundwater from carbonate bedrock result from the precipitation of minerals and (or) from sorption to mineral surfaces along groundwater flow paths. Phosphorus concentrations are commonly elevated in stream base flow in areas underlain by carbonate bedrock, however, presumably derived from in-stream sources or from upland anthropogenic sources and transported along short, shallow groundwater flow paths. Dissolved phosphate concentrations in groundwater were correlated positively with concentrations of silica and sodium, and negatively with alkalinity and concentrations of calcium

  7. StreamMap: Smooth Dynamic Visualization of High-Density Streaming Points.

    Science.gov (United States)

    Li, Chenhui; Baciu, George; Han, Yu

    2018-03-01

    Interactive visualization of streaming points for real-time scatterplots and linear blending of correlation patterns is increasingly becoming the dominant mode of visual analytics for both big data and streaming data from active sensors and broadcasting media. To better visualize and interact with inter-stream patterns, it is generally necessary to smooth out gaps or distortions in the streaming data. Previous approaches either animate the points directly or present a sampled static heat-map. We propose a new approach, called StreamMap, to smoothly blend high-density streaming points and create a visual flow that emphasizes the density pattern distributions. In essence, we present three new contributions for the visualization of high-density streaming points. The first contribution is a density-based method called super kernel density estimation that aggregates streaming points using an adaptive kernel to solve the overlapping problem. The second contribution is a robust density morphing algorithm that generates several smooth intermediate frames for a given pair of frames. The third contribution is a trend representation design that can help convey the flow directions of the streaming points. The experimental results on three datasets demonstrate the effectiveness of StreamMap when dynamic visualization and visual analysis of trend patterns on streaming points are required.

  8. Analyzing indicators of stream health for Minnesota streams

    Science.gov (United States)

    Singh, U.; Kocian, M.; Wilson, B.; Bolton, A.; Nieber, J.; Vondracek, B.; Perry, J.; Magner, J.

    2005-01-01

    Recent research has emphasized the importance of using physical, chemical, and biological indicators of stream health for diagnosing impaired watersheds and their receiving water bodies. A multidisciplinary team at the University of Minnesota is carrying out research to develop a stream classification system for Total Maximum Daily Load (TMDL) assessment. Funding for this research is provided by the United States Environmental Protection Agency and the Minnesota Pollution Control Agency. One objective of the research study involves investigating the relationships between indicators of stream health and localized stream characteristics. Measured data from Minnesota streams collected by various government and non-government agencies and research institutions have been obtained for the research study. Innovative Geographic Information Systems tools developed by the Environmental Science Research Institute and the University of Texas are being utilized to combine and organize the data. Simple linear relationships between index of biological integrity (IBI) and channel slope, two-year stream flow, and drainage area are presented for the Redwood River and the Snake River Basins. Results suggest that more rigorous techniques are needed to successfully capture trends in IBI scores. Additional analyses will be done using multiple regression, principal component analysis, and clustering techniques. Uncovering key independent variables and understanding how they fit together to influence stream health are critical in the development of a stream classification for TMDL assessment.

  9. Applying four principles of headwater system aquatic biology to forest management

    Science.gov (United States)

    Robert J. Danehy; Sherri L. Johnson

    2013-01-01

    Headwater systems, including the channel and the adjacent riparian forest, are a dominant landscape feature in forested watersheds, draining most of the watershed area, and comprising the majority of channel length in drainage networks. Being at the upper extent of watersheds, these systems are smaller and steeper than large streams, and create microhabitats that...

  10. Parametric analysis of neutron streaming through major penetrations in the 0.914 m TFTR test cell floor

    International Nuclear Information System (INIS)

    Ku, L.P.; Liew, S.L.; Kolibal, J.G.

    1985-09-01

    Neutron streaming through penetrations in the 0.914 m TFTR test cell floor has two distinct features: (1) the oblique angle of incidence; and (2) the high order of anisotropy in the angular distribution for incident neutrons with energies > 10 keV. The effects of these features on the neutron streaming into the TFTR basement were studied parametrically for isolated penetrations. Variations with respect to the source energies, angular distributions, and sizes of the penetrations were made. The results form a data base from which the spatial distribution of the neutron flux in the basement due to multiple penetrations may be evaluated

  11. The development of stream temperature model in a mountainous river of Taiwan.

    Science.gov (United States)

    Tung, Ching-Pin; Lee, Tsung-Yu; Huang, Jr-Chuang; Perng, Po-Wen; Kao, Shih-Ji; Liao, Lin-Yen

    2014-11-01

    Formosan landlocked salmon is an endangered species and is very sensitive to stream temperature change. This study attempts to improve a former stream temperature model (STM) which was developed for the salmon's habitat to simulate stream temperature more realistically. Two modules, solar radiation modification (SRM) and surface/subsurface runoff mixing (RM), were incorporated to overcome the limitation of STM designed only for clear-sky conditions. It was found that daily temperature difference is related to cloud cover and can be used to adjust the effects of cloud cover on incident solar radiation to the ground level. The modified model (STM + SRM) improved the simulation during a baseflow period in both winter and summer with the Nash-Sutcliffe efficiency coefficient improved from 0.37 (by STM only) to 0.71 for the winter and from -0.18 to 0.70 for the summer. On the days with surface/subsurface runoff, the incorporation of the two new modules together (STM + SRM + RM) improved the Nash-Sutcliffe efficiency coefficient from 0.00 to 0.65 and from 0.29 to 0.83 in the winter and the summer, respectively. Meanwhile, the contributions of major thermal sources to stream temperature changes were identified. Groundwater is a major controlling factor for regulating seasonal changes of stream temperature while solar radiation is the primary factor controlling daily stream temperature variations. This study advanced our understanding on short-term stream temperature variation, which could be useful for the authorities to restore the salmon's habitat.

  12. Impact of a drain field plate on the breakdown characteristics of AlInN/GaN MOSHEMT

    Science.gov (United States)

    Jena, Kanjalochan; Swain, Raghunandan; Lenka, T. R.

    2015-11-01

    In this paper, a novel AlInN/GaN metal oxide semiconductor high electron mobility transistor (MOSHEMT) employing the drain field plate technique is proposed and the effect of a drain field plate on the breakdown voltage (BV) is investigated. A reduction of the peak electric field is required to achieve AlInN/GaN MOSHEMTs with a high BV. The proposed AlInN/GaN MOSHEMT with both gate and drain field plates simultaneously reduces the electric field concentration at the gate and the drain edge by decreasing the potential gradient along the channel for the 2 dimensional electron gas (2DEG). The reduction in the peak electric field at the drain edge of the proposed device leads to a 57% increase in BV compared with the BV for an AlInN/GaN MOSHEMT with a gate field plate only. A significantly higher BV can be achieved by optimizing the gate-to-drain distance (L gd ), the length of the drain field plate (L dfp ) and the thickness of the SiN passivation layer thickness (T SiN ). A detailed breakdown analysis of the device was carried out using Silvaco Technology Computer Aided Design (TCAD). The detailed numerical simulations were done by using the non-local energy balance (EB) transport model, which was calibrated with the previously published experimental results. The results showed a great potential for applications of the drain-field-plated AlInN/GaN MOSHEMT to deliver high currents and high powers in microwave technologies.

  13. Outcomes of Transhiatal and Intercostal Pleural Drain After Ivor Lewis Esophagectomy: Comparative Analysis of Two Consecutive Patient Cohorts.

    Science.gov (United States)

    Asti, Emanuele; Bernardi, Daniele; Bonitta, Gianluca; Bonavina, Luigi

    2018-05-01

    In a previous proof of concept study, transhiatal pleural drain has been shown to be safe and effective after hybrid Ivor Lewis esophagectomy. Aim of this study was to compare the short-term outcomes of transhiatal and intercostal pleural drainage. This is an observational retrospective cohort study. Two methods of pleural drainage were compared in patients undergoing hybrid Ivor Lewis esophagectomy. Patients treated with a transhiatal drain connected to a vacuum bag were compared to a historical cohort of patients treated with the conventional intercostal drain connected to underwater seal and suction. Postoperative morbidity, total and daily drainage output, serum albumin levels, and total dose of paracetamol and ketorolac administered on demand were recorded. Between January 2014 and December 2016, 50 patients with transhiatal drain and 50 with intercostal drains met the criteria for inclusion in the study. Demographic and clinicopathological variables were similar in the two groups. There was no statistically significant difference in the rate of postoperative complications. The total volume of drain output and the serum albumin levels were similar in the two groups. The total dose of ketorolac was significantly reduced in patients with transhiatal drain (P pleural drainage connected to a portable vacuum system could safely replace the intercostal drain after hybrid Ivor Lewis esophagectomy. It has the potential to reduce postoperative pain and use of nonsteroidal anti-inflammatory drugs, and to enhance recovery from surgery.

  14. Soil Erosion from Agriculture and Mining: A Threat to Tropical Stream Ecosystems

    Directory of Open Access Journals (Sweden)

    Jan H. Mol

    2013-09-01

    Full Text Available In tropical countries soil erosion is often increased due to high erodibility of geologically old and weathered soils; intensive rainfall; inappropriate soil management; removal of forest vegetation cover; and mining activities. Stream ecosystems draining agricultural or mining areas are often severely impacted by the high loads of eroded material entering the stream channel; increasing turbidity; covering instream habitat and affecting the riparian zone; and thereby modifying habitat and food web structures. The biodiversity is severely threatened by these negative effects as the aquatic and riparian fauna and flora are not adapted to cope with excessive rates of erosion and sedimentation. Eroded material may also be polluted by pesticides or heavy metals that have an aggravating effect on functions and ecosystem services. Loss of superficial material and deepening of erosion gullies impoverish the nutrient and carbon contents of the soils; and lower the water tables; causing a “lose-lose” situation for agricultural productivity and environmental integrity. Several examples show how to interrupt this vicious cycle by integrated catchment management and by combining “green” and “hard” engineering for habitat restoration. In this review; we summarize current findings on this issue from tropical countries with a focus on case studies from Suriname and Brazil.

  15. Percutaneous trans-papillary elimination of common bile duct stones using an existing gallbladder drain for access.

    Science.gov (United States)

    Atar, Eli; Neiman, Chaim; Ram, Eduard; Almog, Mazal; Gadiel, Itai; Belenky, Alexander

    2012-06-01

    The presence of stones in the common bile duct (CBD) may cause complications such as obstructing jaundice or ascending cholangitis, and the stones should be removed. To assess the efficacy of percutaneous elimination of CBD stones from the gallbladder through the papilla. During a 4 year period, six patients (five men and one woman, mean age 71.5 years) who had CBD stones and an existing gallbladder drain underwent percutaneous stone push into the duodenum after balloon dilatation of the papilla, with a diameter equal to that of the largest stone. Access into the CBD was from the gallbladder, using an already existing percutaneous gallbladder drain (cholecystostomy tube). Each patient had one to three CBD stones measuring 7-14 mm. Successful CBD stone elimination into the duodenum was achieved in five of the six patients. The single failure occurred in a patient with choledochal diverticulum, who was operated successfully. There were no major or minor complications during or after the procedures. Trans-cholecystic CBD stone elimination is a safe and feasible percutaneous technique that utilizes existing tracts, thus obviating the need to create new percutaneous access. This procedure can replace endoscopic or surgical CBD exploration.

  16. Characterization of Drain Surface Water: Environmental Profile, Degradation Level and Geo-statistic Monitoring

    International Nuclear Information System (INIS)

    Mumtaz, M.W.; Raza, M.A.; Ahmed, Z.; Abbas, M.N.; Hussain, M.

    2015-01-01

    The physico-chemical characterization of the surface water. Samples was carried out collected from nine sampling points of drain passing by the territory of Hafizabad city, Punjab, Pakistan. The water of drain is used by farmers for irrigation purposes in nearby agricultural fields. Twenty water quality parameters were evaluated in three turns and the results obtained were compared with the National Environmental Quality Standards (NEQS) municipal and industrial effluents prescribed limits. The highly significant difference (p<0.01) was recorded for the content of phenols, carbonyl compounds, cyanides, dissolved oxygen, biological oxygen demand, total soluble salts, total dissolved salts, nitrates and sulphates, whereas, the concentration of magnesium, potassium and oil and grease differed significantly (p<0.05) with respect to the sampling points on average basis. Non-significant difference (p>0.05) was noted for temperature, pH, electrical conductivity, hardness, calcium, sodium, chemical oxygen demand and chloride among water samples from different sampling points. Furthermore, the experimental results of different water quality parameters studied at nine sampling points of the drain were used and interpolated in ArcGIS 9.3 environment system using kriging techniques to obtain calculated values for the remaining locations of the Drain. (author)

  17. STREAM: A First Programming Process

    DEFF Research Database (Denmark)

    Caspersen, Michael Edelgaard; Kölling, Michael

    2009-01-01

    to derive a programming process, STREAM, designed specifically for novices. STREAM is a carefully down-scaled version of a full and rich agile software engineering process particularly suited for novices learning object-oriented programming. In using it we hope to achieve two things: to help novice......Programming is recognized as one of seven grand challenges in computing education. Decades of research have shown that the major problems novices experience are composition-based—they may know what the individual programming language constructs are, but they do not know how to put them together....... Despite this fact, textbooks, educational practice, and programming education research hardly address the issue of teaching the skills needed for systematic development of programs. We provide a conceptual framework for incremental program development, called Stepwise Improvement, which unifies best...

  18. Enhanced performance of amorphous In-Ga-Zn-O thin-film transistors using different metals for source/drain electrodes

    Science.gov (United States)

    Pyo, Ju-Young; Cho, Won-Ju

    2017-09-01

    In this paper, we propose an amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor (TFT) with off-planed source/drain electrodes. We applied different metals for the source/drain electrodes with Ni and Ti to control the work function as high and low. When we measured the configuration of Ni to drain and source to Ti, the a-IGZO TFT showed increased driving current, decreased leakage current, a high on/off current ratio, low subthreshold swing, and high mobility. In addition, we conducted a reliability test with a gate bias stress test at various temperatures. The results of the reliability test showed the Ni drain and Ti drain had an equivalent effective energy barrier height. Thus, we confirmed that the proposed off-planed structure improved the electrical characteristics of the fabricated devices without any degradation of characteristics. Through the a-IGZO TFT with different source/drain electrode metal engineering, we realized high-performance TFTs for next-generation display devices.

  19. PGG: An Online Pattern Based Approach for Stream Variation Management

    Institute of Scientific and Technical Information of China (English)

    Lu-An Tang; Bin Cui; Hong-Yan Li; Gao-Shan Miao; Dong-Qing Yang; Xin-Biao Zhou

    2008-01-01

    Many database applications require efficient processing of data streams with value variations and fiuctuant sampling frequency. The variations typically imply fundamental features of the stream and important domain knowledge of underlying objects. In some data streams, successive events seem to recur in a certain time interval, but the data indeed evolves with tiny differences as time elapses. This feature, so called pseudo periodicity, poses a new challenge to stream variation management. This study focuses on the online management for variations over such streams. The idea can be applied to many scenarios such as patient vital signal monitoring in medical applications. This paper proposes a new method named Pattern Growth Graph (PGG) to detect and manage variations over evolving streams with following features: 1) adopts the wave-pattern to capture the major information of data evolution and represent them compactly;2) detects the variations in a single pass over the stream with the help of wave-pattern matching algorithm; 3) only stores different segments of the pattern for incoming stream, and hence substantially compresses the data without losing important information; 4) distinguishes meaningful data changes from noise and reconstructs the stream with acceptable accuracy.Extensive experiments on real datasets containing millions of data items, as well as a prototype system, are carried out to demonstrate the feasibility and effectiveness of the proposed scheme.

  20. External Suction and Fluid Output in Chest Drains After Lobectomy

    DEFF Research Database (Denmark)

    Lijkendijk, Marike; Neckelmann, Kirsten; Licht, Peter B

    2018-01-01

    influences the amount of fluid. METHODS: We randomly assigned (1:1) 106 patients who underwent lobectomy to either low (-5 cm H2O) or high (-20 cm H2O) external suction using an electronic chest drainage system. Only one chest drain was allowed, and we used strict algorithms for chest drain removal, which...... was delegated to staff nurses: air leakage less than 20 mL/min for 6 hours regardless of fluid output, provided it was serous. The primary end point was fluid output after 24 and 48 hours. RESULTS: Mean fluid output was significantly higher with high suction after both 24 (338 ± 265 mL versus 523 ± 215 m...

  1. Photoactive TiO2 Films Formation by Drain Coating for Endosulfan Degradation

    Directory of Open Access Journals (Sweden)

    Natalia Tapia-Orozco

    2013-01-01

    Full Text Available Heterogeneous photocatalysis is an advanced oxidation process in which a photoactive catalyst, such as TiO2, is attached to a support to produce free radical species known as reactive oxygen species (ROS that can be used to break down toxic organic compounds. In this study, the draining time, annealing temperature, and draining/annealing cycles for TiO2 films grown by the drain coating method were evaluated using a 23 factorial experimental design to determine the photoactivity of the films via endosulfan degradation. The TiO2 films prepared with a large number of draining/annealing cycles at high temperatures enhanced (P>0.05 endosulfan degradation and superoxide radical generation after 30 minutes of illumination with UV light. We demonstrated a negative correlation (R2=0.69; P>0.01 between endosulfan degradation and superoxide radical generation. The endosulfan degradation rates were the highest at 30 minutes with the F6 film. In addition, films prepared using conditions F1, F4, and F8 underwent an adsorption/desorption process. The kinetic reaction constants, Kapp (min−1, were 0.0101, 0.0080, 0.0055, 0.0048, and 0.0035 for F6, F2, F5, F3, and F1, respectively. The endosulfan metabolites alcohol, ether, and lactone were detected and quantified at varying levels in all photocatalytic assays.

  2. Benthic macroinvertebrates and the use of stable isotopes (δ13C and δ15N) in the impact assessment of peatland use on boreal stream ecosystems

    Science.gov (United States)

    Nieminen, Mika L.; Daza Secco, Emmanuela; Nykänen, Hannu; Meissner, Kristian

    2013-04-01

    Stable isotope analysis (SIA) can provide insights into carbon flow dynamics and trophic positions of consumers in food webs. SIA is used in this study, where we assess the possible changes in the basal resources of Finnish boreal stream ecosystems and differences in the impact of two forms of peatland use, forestry and peat mining. About 30% of the total land area of Finland is classified as peatland, of which about 55% has been drained for forestry and about 0.6% is in peat production. Unlike forestry, peat production is regionally less scattered and can thus have measurable local impacts although the total area of peat production is small. Three watersheds were used as study areas. Within each watershed, one stream drains a subcatchment affected only by peat mining, whereas the other stream flows through a subcatchment affected by forestry. The two subcatchment streams merge to form a single stream flowing into a lake. Studied watersheds were subject to no other forms of land use. In addition to the impacted sites, we used two pristine natural mire and two natural forest catchments as controls. We analysed the stable isotopes of carbon (δ13C) and nitrogen (δ15N) from benthic macroinvertebrates, stream bank soil, stream sediment, and dissolved organic carbon (DOC) in stream water. Samples for stable isotope analyses were collected in the summer of 2011 and samples for invertebrate community analyses in the autumn of 2011. Upon sampling we measured several physical parameters at each sampling site. In addition, stream water samples collected in summer and autumn 2012 were analysed for CH4 and CO2 gas concentrations and autumn gas samples also for their δ13C values. Our initial SIA results of invertebrates suggest some degree of discrimination between different sources of OM and possible effects on feeding habits, presumably due to the quality of the basal resources. We will explore this result further by examining not only taxonomical structure, but also the

  3. Examining the role of dissolved organic nitrogen in stream ecosystems across biomes and Critical Zone gradients

    Science.gov (United States)

    Wymore, A.; Rodriguez-Cardona, B.; Coble, A. A.; Potter, J.; Lopez Lloreda, C.; Perez Rivera, K.; De Jesus Roman, A.; Bernal, S.; Martí Roca, E.; Kram, P.; Hruska, J.; Prokishkin, A. S.; McDowell, W. H.

    2016-12-01

    Watershed nitrogen exports are often dominated by dissolved organic nitrogen (DON); yet, little is known about the role ambient DON plays in ecosystems. As an organic nutrient, DON may serve as either an energy source or as a nutrient source. One hypothesized control on DON is nitrate (NO3-) availability. Here we examine the interaction of NO3- and DON in streams across temperate forests, tropical rainforests, and Mediterranean and taiga biomes. Experimental streams also drain contrasting Critical Zones which provide gradients of vegetation, soil type and lithology (e.g. volcaniclastic, granitic, ultramafic, Siberian Traps Flood Basalt) in which to explore how the architecture of the Critical Zone affects microbial biogeochemical reactions. Streams ranged in background dissolved organic carbon (DOC) concentration (1-50 mg C/L) and DOC: NO3- ratios (10-2000). We performed a series of ecosystem-scale NO3- additions in multiple streams within each environment and measured the change in DON concentration. Results demonstrate that there is considerable temporal and spatial variation across systems with DON both increasing and decreasing in response to NO3- addition. Ecologically this suggests that DON can serve as both a nutrient source and an energy source to aquatic microbial communities. In contrast, DOC concentrations rarely changed in response to NO3- additions suggesting that the N-rich fraction of the ambient dissolved organic matter pool is more bioreactive than the C-rich fraction. Contrasting responses of the DON and DOC pools indicate different mechanisms controlling their respective cycling. It is likely that DON plays a larger role in ecosystems than previously recognized.

  4. Characteristics of mercury speciation in Minnesota rivers and streams

    Energy Technology Data Exchange (ETDEWEB)

    Balogh, Steven J. [Metropolitan Council Environmental Services, 2400 Childs Road, St. Paul, MN 55106-6724 (United States)], E-mail: steve.balogh@metc.state.mn.us; Swain, Edward B. [Minnesota Pollution Control Agency, 520 Lafayette Road, St. Paul, MN 55155-4194 (United States)], E-mail: edward.swain@state.mn.us; Nollet, Yabing H. [Metropolitan Council Environmental Services, 2400 Childs Road, St. Paul, MN 55106-6724 (United States)], E-mail: yabing.nollet@metc.state.mn.us

    2008-07-15

    Patterns of mercury (Hg) speciation were examined in four Minnesota streams ranging from the main-stem Mississippi River to small tributaries in the basin. Filtered phase concentrations of methylmercury (MeHg), inorganic Hg (IHg), and dissolved organic carbon (DOC) were higher in all streams during a major summertime runoff event, and DOC was enriched with MeHg but not with IHg. Particulate-phase MeHg and IHg concentrations generally increased with total suspended solids (TSS) concentrations but the event data did not diverge greatly from the non-event data, suggesting that sources of suspended sediments in these streams did not vary significantly between event and non-event samplings. The dissolved fractions (filtered concentration/unfiltered concentration) of both MeHg and IHg increased with increasing DOC concentrations, but varied inversely with TSS concentrations. While MeHg typically constitutes only a minor portion of the total Hg (THg) in these streams, this contribution is not constant and can vary greatly over time in response to watershed inputs. - Methylmercury and inorganic mercury concentrations in four Minnesota streams were characterized to determine controlling variables.

  5. Characteristics of mercury speciation in Minnesota rivers and streams

    International Nuclear Information System (INIS)

    Balogh, Steven J.; Swain, Edward B.; Nollet, Yabing H.

    2008-01-01

    Patterns of mercury (Hg) speciation were examined in four Minnesota streams ranging from the main-stem Mississippi River to small tributaries in the basin. Filtered phase concentrations of methylmercury (MeHg), inorganic Hg (IHg), and dissolved organic carbon (DOC) were higher in all streams during a major summertime runoff event, and DOC was enriched with MeHg but not with IHg. Particulate-phase MeHg and IHg concentrations generally increased with total suspended solids (TSS) concentrations but the event data did not diverge greatly from the non-event data, suggesting that sources of suspended sediments in these streams did not vary significantly between event and non-event samplings. The dissolved fractions (filtered concentration/unfiltered concentration) of both MeHg and IHg increased with increasing DOC concentrations, but varied inversely with TSS concentrations. While MeHg typically constitutes only a minor portion of the total Hg (THg) in these streams, this contribution is not constant and can vary greatly over time in response to watershed inputs. - Methylmercury and inorganic mercury concentrations in four Minnesota streams were characterized to determine controlling variables

  6. Impact of Roadway Stormwater Runoff on Microbial Contamination in the Receiving Stream.

    Science.gov (United States)

    Wyckoff, Kristen N; Chen, Si; Steinman, Andrew J; He, Qiang

    2017-09-01

    Stormwater runoff from roadways has increasingly become a regulatory concern for water pollution control. Recent work has suggested roadway stormwater runoff as a potential source of microbial pollutants. The objective of this study was to determine the impact of roadway runoff on the microbiological quality of receiving streams. Microbiological quality of roadway stormwater runoff and the receiving stream was monitored during storm events with both cultivation-dependent fecal bacteria enumeration and cultivation-independent high-throughput sequencing techniques. Enumeration of total coliforms as a measure of fecal microbial pollution found consistently lower total coliform counts in roadway runoff than those in the stream water, suggesting that roadway runoff was not a major contributor of microbial pollutants to the receiving stream. Further characterization of the microbial community in the stormwater samples by 16S ribosomal RNA gene-based high-throughput amplicon sequencing revealed significant differences in the microbial composition of stormwater runoff from the roadways and the receiving stream. The differences in microbial composition between the roadway runoff and stream water demonstrate that roadway runoff did not appear to have a major influence on the stream in terms of microbiological quality. Thus, results from both fecal bacteria enumeration and high-throughput amplicon sequencing techniques were consistent that roadway stormwater runoff was not the primary contributor of microbial loading to the stream. Further studies of additional watersheds with distinct characteristics are needed to validate these findings. Understanding gained in this study could support the development of more effective strategies for stormwater management in sensitive watersheds. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  7. Discharge/Stage Relations in Vegetated Danish Streams

    DEFF Research Database (Denmark)

    Larsen, Torben; Frier, Jens-Ole; Vestergaard, Kristian

    1990-01-01

    This paper describes how the friction in danish streams varies as function of the vegetation. The major species of vegetation are represented. A series of laboratory and field experiments are described, and a hypothesis for the influence of the vegetation on the Manning's n is discussed....

  8. Carbon balance of rewetted and drained peat soils used for biomass production: A mesocosm study

    DEFF Research Database (Denmark)

    Karki, Sandhya; Elsgaard, Lars; Kandel, Tanka

    2016-01-01

    of lower CO2 emissions without losing agricultural land. The present study quantified the carbon balance (CO2, CH4 and harvested biomass C) of rewetted and drained peat soils under intensively managed reed canary grass (RCG) cultivation. Mesocosms were maintained at five different ground water levels (GWL......), i.e., 0, 10, 20 cm below the soil surface, representing rewetted peat soils, and 30 and 40 cm below the soil surface, representing drained peat soils. Net ecosystem exchange (NEE) of CO2 and CH4 emissions were measured during the growing period of RCG (May to September) using transparent and opaque...... closed chamber methods. The average dry biomass yield was significantly lower from rewetted peat soils (12 Mg ha−1) than drained peat soils (15 Mg ha−1). Also, CO2 fluxes of gross primary production (GPP) and ecosystem respiration (ER) from rewetted peat soils were significantly lower than drained peat...

  9. English and the Brain Drain : An Uncertain Relationship

    NARCIS (Netherlands)

    Houtkamp, C.

    2016-01-01

    In his book Linguistic Justice for Europe and the World, Van Parijs analyses in one of his chapters the brain drain from non-Anglophone to Anglophone countries, which hurts the economic development of the nonAnglophone states. Van Parijs deems it clear that English is a very important factor to

  10. Technical meeting on decommissioning of fast reactors after sodium draining. Working material

    International Nuclear Information System (INIS)

    2005-01-01

    The objective of the technical meeting was to provide a forum for in-depth scientific and technical exchange on topics related to the decommissioning experience with fast reactors, in particular with regard to the decommissioning of components after sodium draining. Accordingly, the scope of the meeting covers the review and analyses of the experience gained from the decommissioning of both active sodium loops and sodium cooled fast reactors (e.g., KNK II, Superphenix, RAPSODIE, EBR-II, FERMI, BN-350, BR-10). It is expected that the outcome of the meeting will contribute to the Agency initiative to preserve fast reactor data and knowledge. The main focus of the technical meeting was given on the decommissioning of both active loop and reactor components (e.g., the primary vessel of a sodium-cooled reactor) that have been drained of sodium, but that still conserve some residual amounts of sodium (e.g., films covering the entire surface of the component, or particular sodium heels that cannot be drained)

  11. Soil disturbance as a driver of increased stream salinity in a semiarid watershed undergoing energy development

    Science.gov (United States)

    Bern, Carleton R.; Clark, Melanie L.; Schmidt, Travis S.; Holloway, JoAnn M.; Mcdougal, Robert

    2015-01-01

    Salinization is a global threat to the quality of streams and rivers, but it can have many causes. Oil and gas development were investigated as one of several potential causes of changes in the salinity of Muddy Creek, which drains 2470 km2 of mostly public land in Wyoming, U.S.A. Stream discharge and salinity vary with seasonal snowmelt and define a primary salinity-discharge relationship. Salinity, measured by specific conductance, increased substantially in 2009 and was 53-71% higher at low discharge and 33-34% higher at high discharge for the years 2009-2012 compared to 2005-2008. Short-term processes (e.g., flushing of efflorescent salts) cause within-year deviations from the primary relation but do not obscure the overall increase in salinity. Dissolved elements associated with increased salinity include calcium, magnesium, and sulfate, a composition that points to native soil salts derived from marine shales as a likely source. Potential causes of the salinity increase were evaluated for consistency by using measured patterns in stream chemistry, slope of the salinity-discharge relationship, and inter-annual timing of the salinity increase. Potential causes that were inconsistent with one or more of those criteria included effects from precipitation, evapotranspiration, reservoirs, grazing, irrigation return flow, groundwater discharge, discharge of energy co-produced waters, and stream habitat restoration. In contrast, surface disturbance of naturally salt-rich soil by oil and gas development activities, such as pipeline, road, and well pad construction, is a reasonable candidate for explaining the salinity increase. As development continues to expand in semiarid lands worldwide, the potential for soil disturbance to increase stream salinity should be considered, particularly where soils host substantial quantities of native salts.

  12. Distribution and accumulation of metals in tadpoles inhabiting the metalliferous streams of eastern Chalkidiki, northeast Greece.

    Science.gov (United States)

    Kelepertzis, Efstratios; Argyraki, Ariadne; Valakos, Efstratios; Daftsis, Emmanouil

    2012-10-01

    The present study investigates the accumulation of heavy metals [copper (Cu), lead (Pb), zinc (Zn), magnesium (Mn), cadmium (Cd), nickel (Ni), and chromium (Cr)] in tadpoles inhabiting the metalliferous streams flowing within the Asprolakkas River basin (northeast Chalkidiki peninsula, Greece) and the effect of potentially harmful elements in stream water and sediment on the corresponding levels in their tissue. Animals were collected from six sampling sites influenced by a wide range of surface water and stream sediment trace element concentrations. The results of the chemical analyses showed that tadpoles accumulated significant levels of all of the examined metals. The range of whole-body mean measured concentrations were (in dry mass) as follows: Cu (46-182 mg/kg), Pb (103-4,490 mg/kg), Zn (494-11,460 mg/kg), Mn (1,620-13,310 mg/kg), Cd (1.2-82 mg/kg), Ni (57-163 mg/kg), and Cr (38-272 mg/kg). The mean concentrations of Pb, Zn, Mn, Ni, Cr, and Cd in Kokkinolakkas stream, which drains a currently active mining area, were the highest ever reported in tadpoles. Our results indicate that whole-body levels of Pb, Zn, Cu, and Cd increase with stream sediment concentrations and that these organisms tend to accumulate metals bound to Fe and Mn oxides. In addition, high dissolved concentrations and significant concentrations associated with more labile geochemical phases of sediments for specific metals were contributing factors determining whole-body levels. Given the observed bioconcentration factors, as well as the correlation with sediment concentrations, it is proposed that these organisms could be considered as bioindicators of environmental contamination and may be used for monitoring purposes within this metal-rich zone and, perhaps, within other rivers affected by metal mining.

  13. Differences in microbial community structure and nitrogen cycling in natural and drained tropical peatland soils.

    Science.gov (United States)

    Espenberg, Mikk; Truu, Marika; Mander, Ülo; Kasak, Kuno; Nõlvak, Hiie; Ligi, Teele; Oopkaup, Kristjan; Maddison, Martin; Truu, Jaak

    2018-03-16

    Tropical peatlands, which play a crucial role in the maintenance of different ecosystem services, are increasingly drained for agriculture, forestry, peat extraction and human settlement purposes. The present study investigated the differences between natural and drained sites of a tropical peatland in the community structure of soil bacteria and archaea and their potential to perform nitrogen transformation processes. The results indicate significant dissimilarities in the structure of soil bacterial and archaeal communities as well as nirK, nirS, nosZ, nifH and archaeal amoA gene-possessing microbial communities. The reduced denitrification and N 2 -fixing potential was detected in the drained tropical peatland soil. In undisturbed peatland soil, the N 2 O emission was primarily related to nirS-type denitrifiers and dissimilatory nitrate reduction to ammonium, while the conversion of N 2 O to N 2 was controlled by microbes possessing nosZ clade I genes. The denitrifying microbial community of the drained site differed significantly from the natural site community. The main reducers of N 2 O were microbes harbouring nosZ clade II genes in the drained site. Additionally, the importance of DNRA process as one of the controlling mechanisms of N 2 O fluxes in the natural peatlands of the tropics revealed from the results of the study.

  14. Water and nutrient balances in a large tile-drained agricultural catchment: a distributed modeling study

    Directory of Open Access Journals (Sweden)

    H. Li

    2010-11-01

    Full Text Available This paper presents the development and implementation of a distributed model of coupled water nutrient processes, based on the representative elementary watershed (REW approach, to the Upper Sangamon River Basin, a large, tile-drained agricultural basin located in central Illinois, mid-west of USA. Comparison of model predictions with the observed hydrological and biogeochemical data, as well as regional estimates from literature studies, shows that the model is capable of capturing the dynamics of water, sediment and nutrient cycles reasonably well. The model is then used as a tool to gain insights into the physical and chemical processes underlying the inter- and intra-annual variability of water and nutrient balances. Model predictions show that about 80% of annual runoff is contributed by tile drainage, while the remainder comes from surface runoff (mainly saturation excess flow and subsurface runoff. It is also found that, at the annual scale nitrogen storage in the soil is depleted during wet years, and is supplemented during dry years. This carryover of nitrogen storage from dry year to wet year is mainly caused by the lateral loading of nitrate. Phosphorus storage, on the other hand, is not affected much by wet/dry conditions simply because the leaching of it is very minor compared to the other mechanisms taking phosphorous out of the basin, such as crop harvest. The analysis then turned to the movement of nitrate with runoff. Model results suggested that nitrate loading from hillslope into the channel is preferentially carried by tile drainage. Once in the stream it is then subject to in-stream denitrification, the significant spatio-temporal variability of which can be related to the variation of the hydrologic and hydraulic conditions across the river network.

  15. Xpand chest drain: assessing equivalence to current standard ...

    African Journals Online (AJOL)

    leakage from 'open to air' system or breakage of glass bottle (with associated risk to ... and an air-leak detection system. It is connected to a ... need to add water. Xpand chest drain: assessing equivalence to current standard therapy – a randomised controlled trial. CHARL COOPER, M.B. CH.B. TIMOTHY HARDCASTLE ...

  16. Anomie and the "Brain Drain": A Sociological Explanation.

    Science.gov (United States)

    Karadima, Oscar

    The concept of anomie is proposed as one sociological variable that may explain the "brain drain" phenomenon (i.e., the movement of highly qualified personnel from their country of origin to another, most often a more developed, technologically advanced country). It is hypothesized that the higher the level of anomie found among…

  17. Organic loss in drained wetland: managing the carbon footprint

    NARCIS (Netherlands)

    Durham, B.; van de Noort, R.; Martens, V.V.; Vorenhout, M.

    2012-01-01

    The recent installation of land drains at Star Carr, Yorkshire, UK, has been linked with loss of preservation quality in this important Mesolithic buried landscape, challenging the PARIS principle. Historically captured organic carbon, including organic artefacts, is being converted to soluble

  18. Shifting stream planform state decreases stream productivity yet increases riparian animal production

    Science.gov (United States)

    Venarsky, Michael P.; Walters, David M.; Hall, Robert O.; Livers, Bridget; Wohl, Ellen

    2018-01-01

    In the Colorado Front Range (USA), disturbance history dictates stream planform. Undisturbed, old-growth streams have multiple channels and large amounts of wood and depositional habitat. Disturbed streams (wildfires and logging tested how these opposing stream states influenced organic matter, benthic macroinvertebrate secondary production, emerging aquatic insect flux, and riparian spider biomass. Organic matter and macroinvertebrate production did not differ among sites per unit area (m−2), but values were 2 ×–21 × higher in undisturbed reaches per unit of stream valley (m−1 valley) because total stream area was higher in undisturbed reaches. Insect emergence was similar among streams at the per unit area and per unit of stream valley. However, rescaling insect emergence to per meter of stream bank showed that the emerging insect biomass reaching the stream bank was lower in undisturbed sites because multi-channel reaches had 3 × more stream bank than single-channel reaches. Riparian spider biomass followed the same pattern as emerging aquatic insects, and we attribute this to bottom-up limitation caused by the multi-channeled undisturbed sites diluting prey quantity (emerging insects) reaching the stream bank (riparian spider habitat). These results show that historic landscape disturbances continue to influence stream and riparian communities in the Colorado Front Range. However, these legacy effects are only weakly influencing habitat-specific function and instead are primarily influencing stream–riparian community productivity by dictating both stream planform (total stream area, total stream bank length) and the proportional distribution of specific habitat types (pools vs riffles).

  19. A vapor generator equipped with an advanced drain device for the secondary side of the tubes plate

    International Nuclear Information System (INIS)

    Valadon, C.

    1995-01-01

    A draining design is proposed for the tube plate secondary side in a PWR type reactor, that does not interfere with the water flush 'street' thus allowing for an easy inspection and maintenance in the lower part of the tube bundle. The draining system is composed of a main groove on the upper side of the tube plate, which is connected to draining means situated outside the vapor generator. 6 fig

  20. Nitrate transport and supply limitations quantified using high-frequency stream monitoring and turning point analysis

    Science.gov (United States)

    Jones, Christopher S.; Wang, Bo; Schilling, Keith E.; Chan, Kung-sik

    2017-06-01

    Agricultural landscapes often leak inorganic nitrogen to the stream network, usually in the form of nitrate-nitrite (NOx-N), degrading downstream water quality on both the local and regional scales. While the spatial distribution of nitrate sources has been delineated in many watersheds, less is known about the complicated temporal dynamics that drive stream NOx-N because traditional methods of stream grab sampling are often conducted at a low frequency. Deployment of accurate real-time, continuous measurement devices that have been developed in recent years enables high-frequency sampling that provides detailed information on the concentration-discharge relation and the timing of NOx-N delivery to streams. We aggregated 15-min interval NOx-N and discharge data over a nine-year period into daily averages and then used robust statistical methods to identify how the discharge regime within an artificially-drained agricultural watershed reflected catchment hydrology and NOx-N delivery pathways. We then quantified how transport and supply limitations varied from year-to-year and how dependence of these limitations varied with climate, especially drought. Our results show NOx-N concentrations increased linearly with discharge up to an average "turning point" of 1.42 mm of area-normalized discharge, after which concentrations decline with increasing discharge. We estimate transport and supply limitations to govern 57 and 43 percent, respectively, of the NOx-N flux over the nine-year period. Drought effects on the NOx-N flux linger for multiple years and this is reflected in a greater tendency toward supply limitations in the three years following drought. How the turning point varies with climate may aid in prediction of NOx-N loading in future climate regimes.

  1. Evapotranspiration from drained wetlands with different hydrologic regimes: Drivers, modeling, and storage functions

    Science.gov (United States)

    Wu, Chin-Lung; Shukla, Sanjay; Shrestha, Niroj K.

    2016-07-01

    We tested whether the current understanding of insignificant effect of drainage on evapotranspiration (ET) in the temperate region wetlands applies to those in the subtropics. Hydro-climatic drivers causing the changes in drained wetlands were identified and used to develop a generic model to predict wetland ET. Eddy covariance (EC)-based ET measurements were made for two years at two differently drained but close by wetlands, a heavily drained wetland (SW) (97% reduced surface storage) and a more functional wetland (DW) (42% reduced storage). Annual ET for more intensively drained SW was 836 mm, 34% less than DW (1271 mm) and the difference was significant (p = 0.001). This difference was mainly due to drainage driven differences in inundation and associated effects on net radiation (Rn) and local relative humidity. Two generic daily ET models, a regression model (MSE = 0.44 mm2, R2 = 0.80) and a machine learning-based Relevance Vector Machine (RVM) model (MSE = 0.36 mm2, R2 = 0.84), were developed with the latter being more robust. The RVM model can predict changes in ET for different restoration scenarios; a 1.1 m rise in drainage level showed 7% increase ET (18 mm) at SW while the increase at DW was negligible. The additional ET, 28% of surface flow, can enhance water storage, flood protection, and climate mitigation services at SW compared to DW. More intensely drained wetlands at higher elevation should be targeted for restoration for enhanced storage through increased ET. The models developed can predict changes in ET for improved evaluation of basin-scale effects of restoration programs and climate change scenarios.

  2. Use of laterally placed vacuum drains for management of aural hematomas in five dogs.

    Science.gov (United States)

    Pavletic, Michael M

    2015-01-01

    5 dogs (a Newfoundland, Golden Retriever, Shiba Inu, Staffordshire Terrier, and Vizsla) were referred for evaluation and treatment of unilateral aural hematomas within a week after their formation. Aural hematomas involved the left (3) or right (2) ears. With patients under anesthesia, the aural hematomas were approached surgically from the convex, or lateral, pinnal surface. Two small incisions were used to position a vacuum drain into the incised hematoma cavity. The drain exited at the base of the pinna and adjacent cervical skin. The free end of the drain was attached to a vacuum reservoir for 18 to 21 days. Drains and skin sutures were removed at this time along with the protective Elizabethan collar. All hematomas resolved and surgical sites healed during the minimum 6-month follow-up period. Cosmetic results were considered excellent in 4 of 5 patients. Slight wrinkling of the pinna in 1 patient resulted from asymmetric enlargement of the cartilaginous walls of the hematoma, where vacuum application resulted in a slight folding of the redundant lateral cartilage wall. The described treatment was efficient, economical, and minimally invasive and required no bandaging or wound care. Placement of the drain tubing on the convex (lateral) aspect sheltered the system from displacement by patients with an Elizabethan collar in place. Overall cosmetic results were excellent; asymmetric enlargement of the cartilaginous walls of the hematoma with slight folding of the pinna was seen in 1 patient.

  3. Shifting stream planform state decreases stream productivity yet increases riparian animal production

    Science.gov (United States)

    Venarsky, Michael P.; Walters, David M.; Hall, Robert O.; Livers, Bridget; Wohl, Ellen

    2018-01-01

    In the Colorado Front Range (USA), disturbance history dictates stream planform. Undisturbed, old-growth streams have multiple channels and large amounts of wood and depositional habitat. Disturbed streams (wildfires and logging production, emerging aquatic insect flux, and riparian spider biomass. Organic matter and macroinvertebrate production did not differ among sites per unit area (m−2), but values were 2 ×–21 × higher in undisturbed reaches per unit of stream valley (m−1 valley) because total stream area was higher in undisturbed reaches. Insect emergence was similar among streams at the per unit area and per unit of stream valley. However, rescaling insect emergence to per meter of stream bank showed that the emerging insect biomass reaching the stream bank was lower in undisturbed sites because multi-channel reaches had 3 × more stream bank than single-channel reaches. Riparian spider biomass followed the same pattern as emerging aquatic insects, and we attribute this to bottom-up limitation caused by the multi-channeled undisturbed sites diluting prey quantity (emerging insects) reaching the stream bank (riparian spider habitat). These results show that historic landscape disturbances continue to influence stream and riparian communities in the Colorado Front Range. However, these legacy effects are only weakly influencing habitat-specific function and instead are primarily influencing stream–riparian community productivity by dictating both stream planform (total stream area, total stream bank length) and the proportional distribution of specific habitat types (pools vs riffles).

  4. Comparative effect of tube drain on post operative inflammatory complications of impacted mandibular third molar surgery College Hospital, Ibadan, Nigeria.

    Science.gov (United States)

    Obimakinde, O S; Fasola, A O; Arotiba, J T; Okoje, V N; Obiechina, A E

    2010-09-01

    Swelling, pain and trismus are acute reversible inflammatory complications of impacted mandibular third molar (M3) surgery. They contribute to the deterioration of quality of life and loss of several useful working hours. This study aimed to investigate whether the use of a surgical drain following M3 surgery can minimise these inflammatory complications. Eighty consecutive patients who gave consent were enrolled into the study. Patients were assigned into two groups (drain and no drain) by systematic sampling method which was modified to ensure matching of patients by age, sex and spatial relationship of the impacted mandibular third molar. The patients in the drain group (n=40) had a Foley's catheter drain inserted into the wound after the surgical procedure while the patients in the no drain group (n=40) had their wound closed without the use of drain. All patients had primary wound closure with 3.0 black silk sutures after the procedure. Demographic data, cheek dimension and maximal mouth opening were recorded before the procedure. Pain, swelling and trismus were evaluated in the two groups at 24 hours, 48 hours and 7th day after surgery. Post operative swelling and visual analogue scale score for pain were comparatively lesser in the drain group patients. The maximal interincisal distance was also more in the drain group patients. The findings from this study indicated that there is a significant benefit of using a surgical drain in minimising postoperative oedema, pain and trismus following surgical removal of impacted mandibular third molar.

  5. ADAPTIVE STREAMING OVER HTTP (DASH UNTUK APLIKASI VIDEO STREAMING

    Directory of Open Access Journals (Sweden)

    I Made Oka Widyantara

    2015-12-01

    Full Text Available This paper aims to analyze Internet-based streaming video service in the communication media with variable bit rates. The proposed scheme on Dynamic Adaptive Streaming over HTTP (DASH using the internet network that adapts to the protocol Hyper Text Transfer Protocol (HTTP. DASH technology allows a video in the video segmentation into several packages that will distreamingkan. DASH initial stage is to compress the video source to lower the bit rate video codec uses H.26. Video compressed further in the segmentation using MP4Box generates streaming packets with the specified duration. These packages are assembled into packets in a streaming media format Presentation Description (MPD or known as MPEG-DASH. Streaming video format MPEG-DASH run on a platform with the player bitdash teritegrasi bitcoin. With this scheme, the video will have several variants of the bit rates that gave rise to the concept of scalability of streaming video services on the client side. The main target of the mechanism is smooth the MPEG-DASH streaming video display on the client. The simulation results show that the scheme based scalable video streaming MPEG-DASH able to improve the quality of image display on the client side, where the procedure bufering videos can be made constant and fine for the duration of video views

  6. Influence of pleural drain insertion in lung function of patients undergoing coronary artery bypass grafting.

    Science.gov (United States)

    Ozelami Vieira, Irinea Beatriz Carvalho; Vieira, Fabiano F; Abrão, João; Gastaldi, Ada Clarice

    2012-01-01

    Longitudinal, prospective, randomized, blinded Trial to assess the influence of pleural drain (non-toxic PVC) site of insertion on lung function and postoperative pain of patients undergoing coronary artery bypass grafting in the first three days post-surgery and immediately after chest tube removal. Thirty six patients scheduled for elective myocardial revascularization with cardiopulmonary bypass (CPB) were randomly allocated into two groups: SX group (subxiphoid) and IC group (intercostal drain). Spirometry, arterial blood gases, and pain tests were recorded. Thirty one patients were selected, 16 in SX group and 15 in IC group. Postoperative (PO) spirometric values were higher in SX than in IC group (ppleural drain location on breathing. PaO(2) on the second PO increased significantly in SX group compared with IC group (pDrain with insertion in the subxiphoid region causes less change in lung function and discomfort, allowing better recovery of respiratory parameters. Copyright © 2012 Elsevier Editora Ltda. All rights reserved.

  7. Effects of watershed history on dissolved organic matter characteristics in headwater streams

    Science.gov (United States)

    Youhei Yamashita; Brian D. Kloeppel; Jennifer Knoepp; Gregory L. Zausen; Rudolf Jaffe'

    2011-01-01

    Dissolved organic matter (DOM) is recognized as a major component in the global carbon cycle and is an important driver in aquatic ecosystem function. Climate, land use, and forest cover changes all impact stream DOM and alter biogeochemical cycles in terrestrial environments. We determined the temporal variation in DOM quantity and quality in headwater streams at a...

  8. Microtubule–microtubule sliding by kinesin-1 is essential for normal cytoplasmic streaming in Drosophila oocytes

    Science.gov (United States)

    Lu, Wen; Winding, Michael; Lakonishok, Margot; Wildonger, Jill

    2016-01-01

    Cytoplasmic streaming in Drosophila oocytes is a microtubule-based bulk cytoplasmic movement. Streaming efficiently circulates and localizes mRNAs and proteins deposited by the nurse cells across the oocyte. This movement is driven by kinesin-1, a major microtubule motor. Recently, we have shown that kinesin-1 heavy chain (KHC) can transport one microtubule on another microtubule, thus driving microtubule–microtubule sliding in multiple cell types. To study the role of microtubule sliding in oocyte cytoplasmic streaming, we used a Khc mutant that is deficient in microtubule sliding but able to transport a majority of cargoes. We demonstrated that streaming is reduced by genomic replacement of wild-type Khc with this sliding-deficient mutant. Streaming can be fully rescued by wild-type KHC and partially rescued by a chimeric motor that cannot move organelles but is active in microtubule sliding. Consistent with these data, we identified two populations of microtubules in fast-streaming oocytes: a network of stable microtubules anchored to the actin cortex and free cytoplasmic microtubules that moved in the ooplasm. We further demonstrated that the reduced streaming in sliding-deficient oocytes resulted in posterior determination defects. Together, we propose that kinesin-1 slides free cytoplasmic microtubules against cortically immobilized microtubules, generating forces that contribute to cytoplasmic streaming and are essential for the refinement of posterior determinants. PMID:27512034

  9. Flood-frequency characteristics of Wisconsin streams

    Science.gov (United States)

    Walker, John F.; Peppler, Marie C.; Danz, Mari E.; Hubbard, Laura E.

    2017-05-22

    Flood-frequency characteristics for 360 gaged sites on unregulated rural streams in Wisconsin are presented for percent annual exceedance probabilities ranging from 0.2 to 50 using a statewide skewness map developed for this report. Equations of the relations between flood-frequency and drainage-basin characteristics were developed by multiple-regression analyses. Flood-frequency characteristics for ungaged sites on unregulated, rural streams can be estimated by use of the equations presented in this report. The State was divided into eight areas of similar physiographic characteristics. The most significant basin characteristics are drainage area, soil saturated hydraulic conductivity, main-channel slope, and several land-use variables. The standard error of prediction for the equation for the 1-percent annual exceedance probability flood ranges from 56 to 70 percent for Wisconsin Streams; these values are larger than results presented in previous reports. The increase in the standard error of prediction is likely due to increased variability of the annual-peak discharges, resulting in increased variability in the magnitude of flood peaks at higher frequencies. For each of the unregulated rural streamflow-gaging stations, a weighted estimate based on the at-site log Pearson type III analysis and the multiple regression results was determined. The weighted estimate generally has a lower uncertainty than either the Log Pearson type III or multiple regression estimates. For regulated streams, a graphical method for estimating flood-frequency characteristics was developed from the relations of discharge and drainage area for selected annual exceedance probabilities. Graphs for the major regulated streams in Wisconsin are presented in the report.

  10. Changes in the isotopic and chemical composition of ground water resulting from a recharge pulse from a sinking stream

    Science.gov (United States)

    Katz, Brian G.; Catches, John S.; Bullen, Thomas D.; Michel, Robert L.

    1998-11-01

    The Little River, an ephemeral stream that drains a watershed of approximately 88 km 2 in northern Florida, disappears into a series of sinkholes along the Cody Scarp and flows directly into the carbonate Upper Floridan aquifer, the source of water supply in northern Florida. The changes in the geochemistry of ground water caused by a major recharge pulse from the sinking stream were investigated using chemical and isotopic tracers and mass-balance modeling techniques. Nine monitoring wells were installed open to the uppermost part of the aquifer in areas near the sinks where numerous subterranean karst solution features were identified using ground penetrating radar. During high-flow conditions in the Little River, the chemistry of water in some of the monitoring wells changed, reflecting the mixing of river water with ground water. Rapid recharge of river water into some parts of the aquifer during high-flow conditions was indicated by enriched values of delta 18O and delta deuterium (-1.67 to -3.17 per mil and -9.2 to -15.6 per mil, respectively), elevated concentrations of tannic acid, higher (more radiogenic) 87Sr/ 86Sr ratios, and lower concentrations of 222Rn, silica, and alkalinity compared to low-flow conditions. The proportion of river water that mixed with ground water ranged from 0.10 to 0.67 based on binary mixing models using the tracers 18O, deuterium, tannic acid, silica, 222Rn, and 87Sr/ 86Sr. On the basis of mass-balance modeling during steady-state flow conditions, the dominant processes controlling carbon cycling in ground water are the dissolution of calcite and dolomite in aquifer material, and aerobic degradation of organic matter.

  11. Navajo Nation Brain Drain: An Exploration of Returning College Graduates’ Perspectives

    Directory of Open Access Journals (Sweden)

    Quintina Ava Bearchief-Adolpho

    2017-01-01

    Full Text Available American Indian tribes face the phenomenon known across the world as the brain drain. They invest millions of dollars in educating their members only to have little return on their investment. Many nation members leave reservations to get postsecondary education but never return. Those who get education off the reservation and choose to return are the exception to this rule. Although there is an abundance of literature regarding brain drain across the world, there has been little research done with American Indians. In order to begin to understand the brain drain phenomenon, this study analyzed unstructured qualitative interviews with 17 Navajo Nation members who left their reservation, obtained a degree, and returned to work on the reservation. Themes resulting from the hermeneutic analysis of transcribed interviews were (a Family Support, (b Community, (c Cultural Identity, (d the Simple Life, (e Reservation Economy, and (f Commitment to the Reservation. The analysis found that constant, lengthy, and meaningful relationships were motivating factors in drawing participants back to contribute to their reservations. Further study is needed to understand how communities and tribes can ensure that these relationships are built and maintained.

  12. Restructuring brain drain: strengthening governance and financing for health worker migration

    Directory of Open Access Journals (Sweden)

    Tim K. Mackey

    2013-01-01

    Full Text Available Background: Health worker migration from resource-poor countries to developed countries, also known as ‘‘brain drain’’, represents a serious global health crisis and a significant barrier to achieving global health equity. Resource-poor countries are unable to recruit and retain health workers for domestic health systems, resulting in inadequate health infrastructure and millions of dollars in healthcare investment losses. Methods: Using acceptable methods of policy analysis, we first assess current strategies aimed at alleviating brain drain and then propose our own global health policy based solution to address current policy limitations. Results: Although governments and private organizations have tried to address this policy challenge, brain drain continues to destabilise public health systems and their populations globally. Most importantly, lack of adequate financing and binding governance solutions continue to fail to prevent health worker brain drain. Conclusions: In response to these challenges, the establishment of a Global Health Resource Fund in conjunction with an international framework for health worker migration could create global governance for stable funding mechanisms encourage equitable migration pathways, and provide data collection that is desperately needed.

  13. Mechanism of improving forward and reverse blocking voltages in AlGaN/GaN HEMTs by using Schottky drain

    International Nuclear Information System (INIS)

    Zhao Sheng-Lei; Mi Min-Han; Luo Jun; Wang Yi; Dai Yang; Zhang Jin-Cheng; Ma Xiao-Hua; Hao Yue; Hou Bin

    2014-01-01

    In this paper, we demonstrate that a Schottky drain can improve the forward and reverse blocking voltages (BVs) simultaneously in AlGaN/GaN high-electron mobility transistors (HEMTs). The mechanism of improving the two BVs is investigated by analysing the leakage current components and by software simulation. The forward BV increases from 72 V to 149 V due to the good Schottky contact morphology. During the reverse bias, the buffer leakage in the Ohmicdrain HEMT increases significantly with the increase of the negative drain bias. For the Schottky-drain HEMT, the buffer leakage is suppressed effectively by the formation of the depletion region at the drain terminal. As a result, the reverse BV is enhanced from −5 V to −49 V by using a Schottky drain. Experiments and the simulation indicate that a Schottky drain is desirable for power electronic applications. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  14. Water chemistry in 179 randomly selected Swedish headwater streams related to forest production, clear-felling and climate.

    Science.gov (United States)

    Löfgren, Stefan; Fröberg, Mats; Yu, Jun; Nisell, Jakob; Ranneby, Bo

    2014-12-01

    From a policy perspective, it is important to understand forestry effects on surface waters from a landscape perspective. The EU Water Framework Directive demands remedial actions if not achieving good ecological status. In Sweden, 44 % of the surface water bodies have moderate ecological status or worse. Many of these drain catchments with a mosaic of managed forests. It is important for the forestry sector and water authorities to be able to identify where, in the forested landscape, special precautions are necessary. The aim of this study was to quantify the relations between forestry parameters and headwater stream concentrations of nutrients, organic matter and acid-base chemistry. The results are put into the context of regional climate, sulphur and nitrogen deposition, as well as marine influences. Water chemistry was measured in 179 randomly selected headwater streams from two regions in southwest and central Sweden, corresponding to 10 % of the Swedish land area. Forest status was determined from satellite images and Swedish National Forest Inventory data using the probabilistic classifier method, which was used to model stream water chemistry with Bayesian model averaging. The results indicate that concentrations of e.g. nitrogen, phosphorus and organic matter are related to factors associated with forest production but that it is not forestry per se that causes the excess losses. Instead, factors simultaneously affecting forest production and stream water chemistry, such as climate, extensive soil pools and nitrogen deposition, are the most likely candidates The relationships with clear-felled and wetland areas are likely to be direct effects.

  15. Firn thickness variations across the Northeast Greenland Ice Stream margins indicating nonlinear densification rates

    Science.gov (United States)

    Riverman, K. L.; Anandakrishnan, S.; Alley, R. B.; Peters, L. E.; Christianson, K. A.; Muto, A.

    2013-12-01

    Northeast Greenland Ice Stream (NEGIS) is the largest ice stream in Greenland, draining approximately 8.4% of the ice sheet's area. The flow pattern and stability mechanism of this ice stream are unique to others in Greenland and Antarctica, and merit further study to ascertain the sensitivity of this ice stream to future climate change. Geophysical methods are valuable tools for this application, but their results are sensitive to the structure of the firn and any spatial variations in firn properties across a given study region. Here we present firn data from a 40-km-long seismic profile across the upper reaches of NEGIS, collected in the summer of 2012 as part of an integrated ground-based geophysical survey. We find considerable variations in firn thickness that are coincident with the ice stream shear margins, where a thinner firn layer is present within the margins, and a thicker, more uniform firn layer is present elsewhere in our study region. Higher accumulation rates in the marginal surface troughs due to drift-snow trapping can account for some of this increased densification; however, our seismic results also highlight enhanced anisotropy within the firn and upper ice column that is confined to narrow bands within the shear margins. We thus interpret these large firn thickness variations and abrupt changes in anisotropy as indicators of firn densification dependent on the effective stress state as well as the overburden pressure, suggesting that the strain rate increases nonlinearly with stress across the shear margins. A GPS strain grid maintained for three weeks across both margins observed strong side shearing, with rapid stretching and then compression along particle paths, indicating large deviatoric stresses in the margins. This work demonstrates the importance of developing a high-resolution firn densification model when conducting geophysical field work in regions possessing a complex ice flow history; it also motivates the need for a more

  16. Using heat to characterize streambed water flux variability in four stream reaches

    Science.gov (United States)

    Essaid, H.I.; Zamora, C.M.; McCarthy, K.A.; Vogel, J.R.; Wilson, J.T.

    2008-01-01

    Estimates of streambed water flux are needed for the interpretation of streambed chemistry and reactions. Continuous temperature and head monitoring in stream reaches within four agricultural watersheds (Leary Weber Ditch, IN; Maple Creek, NE; DR2 Drain, WA; and Merced River, CA) allowed heat to be used as a tracer to study the temporal and spatial variability of fluxes through the streambed. Synoptic methods (seepage meter and differential discharge measurements) were compared with estimates obtained by using heat as a tracer. Water flux was estimated by modeling one-dimensional vertical flow of water and heat using the model VS2DH. Flux was influenced by physical heterogeneity of the stream channel and temporal variability in stream and ground-water levels. During most of the study period (April-December 2004), flux was upward through the streambeds. At the IN, NE, and CA sites, high-stage events resulted in rapid reversal of flow direction inducing short-term surface-water flow into the streambed. During late summer at the IN site, regional ground-water levels dropped, leading to surface-water loss to ground water that resulted in drying of the ditch. Synoptic measurements of flux generally supported the model flux estimates. Water flow through the streambed was roughly an order of magnitude larger in the humid basins (IN and NE) than in the arid basins (WA and CA). Downward flux, in response to sudden high streamflows, and seasonal variability in flux was most pronounced in the humid basins and in high conductivity zones in the streambed. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  17. Novel technique of source and drain engineering for dual-material double-gate (DMDG) SOI MOSFETS

    Science.gov (United States)

    Yadav, Himanshu; Malviya, Abhishek Kumar; Chauhan, R. K.

    2018-04-01

    The dual-metal dual-gate (DMDG) SOI has been used with Dual Sided Source and Drain Engineered 50nm SOI MOSFET with various high-k gate oxide. It has been scrutinized in this work to enhance its electrical performance. The proposed structure is designed by creating Dual Sided Source and Drain Modification and its characteristics are evaluated on ATLAS device simulator. The consequence of this dual sided assorted doping on source and drain side of the DMDG transistor has better leakage current immunity and heightened ION current with higher ION to IOFF Ratio. Which thereby vesting the proposed device appropriate for low power digital applications.

  18. Akamai Streaming

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Akamai offers world-class streaming media services that enable Internet content providers and enterprises to succeed in today's Web-centric marketplace. They deliver live event Webcasts (complete with video production, encoding, and signal acquisition services), streaming media on demand, 24/7 Webcasts and a variety of streaming application services based upon their EdgeAdvantage.

  19. Influence of Channel Geomorphology on Retention of Dissolved and Particulate Matter in a Cascade Mountain Stream

    Science.gov (United States)

    Gary A. Lamberti; Stan V. Gregory; Linda R. Ashkenas; Randall C. Wildman; Alan G. Steinman

    1989-01-01

    Retention of particulate and dissolved nutrients in streams is a major determinant of food avail-ability to stream biota. Retention of particulate matter (leaves) and dissolved nutrients (nitrogen) was studied experimentally during summer 1987 in four 300-500 m reaches of Lookout Creek, a fifth-order stream in the Cascade Mountains of Oregon. Constrained (narrow valley...

  20. Comparison consequences of Jackson-Pratt drain versus chest tube after coronary artery bypass grafting: A randomized controlled clinical trial.

    Science.gov (United States)

    Mirmohammad-Sadeghi, Mohsen; Pourazari, Pejman; Akbari, Mojtaba

    2017-01-01

    Chest tubes are used in every case of coronary artery bypass grafting (CABG) to evacuate shed blood from around the heart and lungs. This study was designed to assess the effective of Jackson-Pratt drain in compare with conventional chest drains after CABG. This was a randomized controlled trial that conducted on 218 patients in Chamran hospital from February to December 2016. Eligible patients were randomized in a 1:1 ratio. Jackson-Pratt drain group had 109 patients who received a chest tube insertion in the pleural space of the left lung and a Jackson-Pratt drain in mediastinum, and Chest tube drainage group had 109 patients who received double chest tube insertion in the pleural space of the left lung and the mediastinum. The incidence of pleural effusions in Jackson-Pratt drain group and chest tube group were not statistically different. The pain score at 2-h in Drain group was significantly higher than chest tube group ( P = 0.001), but the trend of pain score between groups was not significantly different ( P = 0.097). The frequency of tamponade and atrial fibrillation (AF) were significantly lower in Jackson-Pratt drain group ( P drain is equally effective for preventing cardiac tamponade, pleural effusions, and pain intensity in patients after CABG when compared with conventional chest tubes, but was significantly superior regarding efficacy to hospital and Intensive Care Unit length of stay and the incidence of AF.

  1. Stream nitrogen sources apportionment and pollution control scheme development in an agricultural watershed in eastern China.

    Science.gov (United States)

    Chen, Dingjiang; Lu, Jun; Huang, Hong; Liu, Mei; Gong, Dongqin; Chen, Jiabo

    2013-08-01

    A modeling system that couples a land-usebased export coefficient model, a stream nutrient transport equation, and Bayesian statistics was developed for stream nitrogen source apportionment. It divides a watershed into several sub-catchments, and then considers the major landuse categories as stream nitrogen sources in each subcatchment. The runoff depth and stream water depth are considered as the major factors influencing delivery of nitrogen from land to downstream stream node within each sub-catchment. The nitrogen sources and delivery processes are lumped into several constant parameters that were calibrated using Bayesian statistics from commonly available stream monitoring and land-use datasets. This modeling system was successfully applied to total nitrogen (TN) pollution control scheme development for the ChangLe River watershed containing six sub-catchments and four land-use categories. The temporal (across months and years) and spatial (across sub-catchments and land-use categories) variability of nonpoint source (NPS) TN export to stream channels and delivery to the watershed outlet were assessed. After adjustment for in-stream TNretention, the time periods and watershed areas with disproportionately high-TN contributions to the stream were identified. Aimed at a target stream TN level of 2 mg L-1, a quantitative TN pollution control scheme was further developed to determine which sub-catchments, which land-use categories in a sub-catchment, which time periods, and how large of NPS TN export reduction were required. This modeling system provides a powerful tool for stream nitrogen source apportionment and pollution control scheme development at the watershed scale and has only limited data requirements.

  2. Brain drain or brain gain : The case of Suriname

    NARCIS (Netherlands)

    T.W. Dulam (Tina)

    2015-01-01

    markdownabstractAbstract Brain drain refers to the emigration of highly skilled individuals mostly from a less developed (home) to a developed country (destination) thereby reducing the capacity of the home country to generate welfare for its population. In the literature there is much written

  3. Phosphorus modeling in tile drained agricultural systems using APEX

    Science.gov (United States)

    Phosphorus losses through tile drained systems in agricultural landscapes may be causing the persistent eutrophication problems observed in surface water. The purpose of this paper is to evaluate the state of the science in the Agricultural Policy/Environmental eXtender (APEX) model related to surf...

  4. Event-Based Analysis of Rainfall-Runoff Response to Assess Wetland-Stream Interaction in the Prairie Pothole Region

    Science.gov (United States)

    Haque, M. A.; Ross, C.; Schmall, A.; Bansah, S.; Ali, G.

    2016-12-01

    Process-based understanding of wetland response to precipitation is needed to quantify the extent to which non-floodplain wetlands - such as Prairie potholes - generate flow and transmit that flow to nearby streams. While measuring wetland-stream (W-S) interaction is difficult, it is possible to infer it by examining hysteresis characteristics between wetland and stream stage during individual precipitation events. Hence, to evaluate W-S interaction, 10 intact and 10 altered/lost potholes were selected for study; they are located in Broughton's Creek Watershed (Manitoba, Canada) on both sides of a 5 km creek reach. Stilling wells (i.e., above ground wells) were deployed in the intact and altered wetlands to monitor surface water level fluctuations while water table wells were drilled below drainage ditches to a depth of 1 m to monitor shallow groundwater fluctuations. All stilling wells and water table wells were equipped with capacitance water level loggers to monitor fluctuations in surface water and shallow groundwater every 15 minutes. In 2013 (normal year) and 2014 (wet year), 15+ precipitation events were identified and scatter plots of wetland (x-axis) versus stream (y-axis) stage were built to identify W-S hysteretic dynamics. Initial data analysis reveals that in dry antecedent conditions, intact and altered wetlands show clockwise W-S relations, while drained wetlands show anticlockwise W-S hysteresis. However, in wetter antecedent conditions, all wetland types show anticlockwise hysteresis. Future analysis will target the identification of thresholds in antecedent moisture conditions that determine significant changes in event wetland response characteristics (e.g., the delay between the start of rainfall and stream stage, the maximum water level rise in each wetland during each event, the delay between the start of rainfall and peak wetland stage) as well as hysteresis properties (e.g., gradient and area of the hysteresis loop).

  5. Nord Stream 2: May Cooler Heads Prevail

    International Nuclear Information System (INIS)

    Aoun, Marie-Claire

    2016-01-01

    Since the announcement of the Nord Stream 2 project in June 2015, the debate around the benefits of this project for Europe is raging, putting forward political, economic and commercial arguments. Within the space of a few months, Russia has conducted a radical strategic change towards Europe in its gas policy. Following the announcements in 2014 of a major shift towards Asia, the cancellation of the South Stream project and its replacement by the Turkish Stream, relations with European gas companies have been strengthened since mid-2015. Russia's initiatives to replace its European partners are now to be viewed as part of a transformed international gas landscape. Tensions in the liquefied natural gas (LNG) market following Fukushima have given way to market surpluses. These are characterised on the one hand by lower growth in Asian demand for LNG gas, and on the other hand by the arrival on the market of new major exporters such as Australia and the United States. A new era, more favourable to gas importing countries, has opened up since the end of 2014. Moreover, the key pivot to Asia, expected by Moscow in 2014, is still far off. Discussions with Beijing about the project for a Western route proved to be more difficult than expected. Similarly, negotiations between Turkey and Russia on the Turkish Stream project have been very laborious, having been interrupted for several months because of diplomatic rows between the two countries. Finally, Russia's room for manoeuvre has narrowed, given the collapse in oil and gas prices and Western economic sanctions, which are weighing heavily on its economy. And the increased competitiveness of Russian oil companies due to the ruble devaluation will not transform this situation sustainably

  6. Interactions between lithology and biology drive the long-term response of stream chemistry to major hurricanes in a tropical landscape

    Science.gov (United States)

    W.H. McDowell; R.L. Brereton; F.N. Scatena; J.B. Shanley; N.V. Brokaw; A.E. Lugo

    2013-01-01

    Humid tropical forests play a dominant role in many global biogeochemical cycles, yet long-term records of tropical stream chemistry and its response to disturbance events such as severe storms and droughts are rare. Here we document the long-term variability in chemistry of two streams in the Luquillo Mountains, Puerto Rico over a period of 27 years. Our two focal...

  7. Use of the PISCES Database: power plant aqueous stream compositions

    International Nuclear Information System (INIS)

    Behrens, G.P.; Orr, D.A.; Wetherold, R.G.; O'Neil, B.T.

    1996-01-01

    The Power Plant Integrated Systems: Chemical Emissions Studies (PISCES) Database sponsored by the Electric Power Research Institute is a powerful tool for evaluating and comparing the level of trace substances in power plant process streams. In this paper, data are presented on the level of several selected trace metals found in a few of the aqueous streams present in power plants. A brief discussion of other features of the Database is presented. The majority of the data is for coal fired power plants, with only 5% pertaining to oil and gas. Sources of pollution include: ash streams; cooling water; coal pile runoff; FGD liquids; makeup water; and wastewater. 11 refs., 10 figs., 1 tab

  8. Petroleum Hydrocarbons Contamination Profile of Ochani Stream in ...

    African Journals Online (AJOL)

    Petroleum hydrocarbon contamination profile, heavy metals and some physicochemical parameters were investigated in Ochani Stream site in Ejamah Ebubu, Eleme Local Government Area of Rivers State. The results show that a major crude oil spillage occurred at Ejamah Ebubu, Rivers State, Nigeria approximately 30 ...

  9. Structural alterations in tumor-draining lymph nodes before papillary thyroid carcinoma metastasis.

    Science.gov (United States)

    Hinson, Andrew M; Massoll, Nicole A; Jolly, Lee Ann; Stack, Brendan C; Bodenner, Donald L; Franco, Aime T

    2017-08-01

    The purpose of this study was to define and characterize the thyroid tumor-draining lymph nodes in genetically engineered mice harboring thyroid-specific expression of oncogenic Braf V600E with and without Pten insufficiency. After intratumoral injection of methylene blue, the lymphatic drainage of the thyroid gland was visualized in real time. The thyroid gland/tumor was resected en bloc with the respiratory system for histological analysis. Although mice harboring Braf V600E mutations were smaller in body size compared with their wild-type (WT) littermates, the size of their thyroid glands and deep cervical lymph nodes were significantly larger. Additionally, the tumor-draining lymph nodes showed increased and enlarged lymphatic sinuses that were distributed throughout the cortex and medulla. Tumor-reactive lymphadenopathy and histiocytosis, but no frank metastases, were observed in all mice harboring Braf V600E mutations. The tumor-draining lymph nodes undergo significant structural alterations in immunocompetent mice, and this may represent a primer for papillary thyroid carcinoma (PTC) metastasis. © 2017 Wiley Periodicals, Inc.

  10. 'Brain drain' from Serbia: One face of globalization of education?

    Directory of Open Access Journals (Sweden)

    Avramović Zoran

    2012-01-01

    Full Text Available In this paper we point out the role of the practice and ideology of globalization in brain drain process from Serbia. The listed data are based on the large-scale departure of highly educated persons from Serbia to the counties of West Europe and the USA. The dynamics, proportions and tendencies are analysed the role of the educational system in the process of departure of highly educated people and the reasons and consequences of the departure of scientist and engineering experts. In this article, education policy as state financial support are critical analysed. For Serbia, as the relatively undeveloped country in the middle of the modernization processes, this process has far-reaching effects on the social development. So, here we implied the possible solutions for the problem of brain drain.

  11. Analysis of hydraulic characteristics for stream diversion in small stream

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sang-Jin; Jun, Kye-Won [Chungbuk National University, Cheongju(Korea)

    2001-10-31

    This study is the analysis of hydraulic characteristics for stream diversion reach by numerical model test. Through it we can provide the basis data in flood, and in grasping stream flow characteristics. Analysis of hydraulic characteristics in Seoknam stream were implemented by using computer model HEC-RAS(one-dimensional model) and RMA2(two-dimensional finite element model). As a result we became to know that RMA2 to simulate left, main channel, right in stream is more effective method in analysing flow in channel bends, steep slope, complex bed form effect stream flow characteristics, than HEC-RAS. (author). 13 refs., 3 tabs., 5 figs.

  12. Streaming potential near a rotating porous disk.

    Science.gov (United States)

    Prieve, Dennis C; Sides, Paul J

    2014-09-23

    Theory and experimental results for the streaming potential measured in the vicinity of a rotating porous disk-shaped sample are described. Rotation of the sample on its axis draws liquid into its face and casts it from the periphery. Advection within the sample engenders streaming current and streaming potential that are proportional to the zeta potential and the disk's major dimensions. When Darcy's law applies, the streaming potential is proportional to the square of the rotation at low rate but becomes invariant with rotation at high rate. The streaming potential is invariant with the sample's permeability at low rate and is proportional to the inverse square of the permeability at high rate. These predictions were tested by determining the zeta potential and permeability of the loop side of Velcro, a sample otherwise difficult to characterize; reasonable values of -56 mV for zeta and 8.7 × 10(-9) m(2) for the permeability were obtained. This approach offers the ability to determine both the zeta potential and the permeability of materials having open structures. Compressing them into a porous plug is unnecessary. As part of the development of the theory, a convenient formula for a flow-weighted volume-averaged space-charge density of the porous medium, -εζ/k, was obtained, where ε is the permittivity, ζ is the zeta potential, and k is the Darcy permeability. The formula is correct when Smoluchowski's equation and Darcy's law are both valid.

  13. The metaphors we stream by: Making sense of music streaming

    OpenAIRE

    Hagen, Anja Nylund

    2016-01-01

    In Norway music-streaming services have become mainstream in everyday music listening. This paper examines how 12 heavy streaming users make sense of their experiences with Spotify and WiMP Music (now Tidal). The analysis relies on a mixed-method qualitative study, combining music-diary self-reports, online observation of streaming accounts, Facebook and last.fm scrobble-logs, and in-depth interviews. By drawing on existing metaphors of Internet experiences we demonstrate that music-streaming...

  14. Miniinvasive paracentetic drain surgical interventions under ultrasonic control concerning liquid formations of abdominal cavity

    Directory of Open Access Journals (Sweden)

    G.I. Ohrimenko

    2013-08-01

    Full Text Available Entry. Presently miniinvasive surgical interventions under ultrasonic control became the method of choice in treatment of quite a number of abdominal and retroperitoneal organs diseases, and their complications. These operations have a row of advantages, as compared to open and laparoscopic ones: comparative simplicity, insignificant infecting of abdominal region, least of intra- and postoperative complications. Actuality of problem is conditioned by that indications to the use of paracentetic drain surgical interventions, most optimal methods of preoperative diagnostic, features of postoperative treatment of patients remain not enough studied. Research aim. To study the results of diagnostics and treatment of patients with liquid formations of abdominal cavity that were exposed to miniinvasive surgical interventions under ultrasonic control and, on the basis of it, to work out an optimal curative diagnostic algorithm. Materials and research methods. The results of treatment of 25 patients with liquid formations of abdominal cavity are analyzed. They were submitted to miniinvasive paracentetic drain surgical interventions under ultrasonic control. The pseudocysts of pancreas were in 16 patients, abscesses of abdominal cavity – in 2 patients. Research results. Intraoperative complications were not marked. Postoperative complications were observed in 5 patients. Among them there were inadequate drainage of all cavities of multicamerate abscess of the liver in 2 patients, progress of sacculated uremic peritonitis developing in presence of ascites in one patient, and arrosive hemorrhage in the cavity of pancreas pseudocyst in 2 persons. It is determined that it is necessary to include the spiral computer tomography to the complex of preoperative inspection of patients that allows to diagnose multicamerate abscess of the liver in time and to drain all the additional cavities adequately. 2 patients after paracentetic drain surgical interventions

  15. Thermal Fluxes and Temperatures in Small Urban Headwater Streams of the BES LTER: Landscape Forest and Impervious Patches and the Importance of Spatial and Temporal Scales

    Science.gov (United States)

    Kim, H.; Belt, K. T.; Welty, C.; Heisler, G.; Pouyat, R. V.; McGuire, M. P.; Stack, W. P.

    2006-05-01

    Water and material fluxes from urban landscape patches to small streams are modulated by extensive "engineered" drainage networks. Small urban headwater catchments are different in character and function from their larger receiving streams because of their extensive, direct connections to impervious surface cover (ISC) and their sometimes buried nature. They need to be studied as unique functional hydrologic units if impacts on biota are to be fully understood. As part of the Baltimore Ecosystem Study LTER project, continuous water temperature data are being collected at 2-minute intervals at over twenty small catchments representing various mixtures of forest and ISC. Suburban stream sites with greater ISC generally have higher summer water temperatures. Suburban catchments with most of their channel drainage contained within storm drain pipes show subdued diurnal variation and cool temperatures, but with very large spikes in summer runoff events. Conversely, high ISC urban piped streams have elevated "baseline" temperatures that stand well above all the other monitoring sites. There is a pronounced upstream-downstream effect; nested small headwater catchments experience more frequent, larger temperature spikes related to runoff events than downstream sites. Also, runoff-initiated temperature elevations at small stream sites unexpectedly last much longer than the storm runoff hydrographs. These observations suggest that for small headwater catchments, urban landscapes not only induce an ambient, "heat island" effect on stream temperatures, but also introduce thermal disturbance regimes and fluxes that are not trivial to aquatic biota.

  16. Peat accumulation in drained thermokarst lake basins in continuous, ice-rich permafrost, northern Seward Peninsula, Alaska

    Science.gov (United States)

    Jones, Miriam C.; Grosse, Guido; Jones, Benjamin M.; Anthony, Katey Walter

    2012-01-01

    Thermokarst lakes and peat-accumulating drained lake basins cover a substantial portion of Arctic lowland landscapes, yet the role of thermokarst lake drainage and ensuing peat formation in landscape-scale carbon (C) budgets remains understudied. Here we use measurements of terrestrial peat thickness, bulk density, organic matter content, and basal radiocarbon age from permafrost cores, soil pits, and exposures in vegetated, drained lake basins to characterize regional lake drainage chronology, C accumulation rates, and the role of thermokarst-lake cycling in carbon dynamics throughout the Holocene on the northern Seward Peninsula, Alaska. Most detectable lake drainage events occurred within the last 4,000 years with the highest drainage frequency during the medieval climate anomaly. Peat accumulation rates were highest in young (50–500 years) drained lake basins (35.2 g C m−2 yr−1) and decreased exponentially with time since drainage to 9 g C m−2 yr−1 in the oldest basins. Spatial analyses of terrestrial peat depth, basal peat radiocarbon ages, basin geomorphology, and satellite-derived land surface properties (Normalized Difference Vegetation Index (NDVI); Minimum Noise Fraction (MNF)) from Landsat satellite data revealed significant relationships between peat thickness and mean basin NDVI or MNF. By upscaling observed relationships, we infer that drained thermokarst lake basins, covering 391 km2 (76%) of the 515 km2 study region, store 6.4–6.6 Tg organic C in drained lake basin terrestrial peat. Peat accumulation in drained lake basins likely serves to offset greenhouse gas release from thermokarst-impacted landscapes and should be incorporated in landscape-scale C budgets.

  17. 77 FR 30886 - Virginia Graeme Baker Pool and Spa Safety Act; Interpretation of Unblockable Drain

    Science.gov (United States)

    2012-05-24

    ... interpretation and installed unblockable drain covers and now would have to go back and ``re-do'' their work... compliance and whether the pool operator is seeking a plan review and not just limited advice about how to... secondary anti-entrapment system to come into compliance, unless the pool uses a gravity drain system or the...

  18. An analysis of molten-corium-induced failure of drain pipes in BWR Mark 2 containments

    International Nuclear Information System (INIS)

    Taleyarkhan, R.P.; Podowski, M.Z.

    1991-01-01

    This study has focused on mechanistic simulation and analysis of potential failure modes for inpedestal drywell drain pipes in the Limerick boiling water reactor (BWR) Mark 2 containment. Physical phenomena related to surface tension breakdown, heatup, melting, ablation, crust formation and failure, and core material relocation into drain pipes with simultaneous melting of pipe walls were modeled and analyzed. The results of analysis have been used to assess the possibility of drain pipe failure and the resultant loss of pressure-suppression capability. Estimates have been made for the timing and amount of molten corium released to the wetwell. The study has revealed that significantly different melt progression sequences can result depending upon the failure characteristics of the frozen metallic crust which forms over the drain cover during the initial stages of debris pour. Another important result is that it can take several days for the molten fuel to ablate the frozen metallic debris layer -- if the frozen layer has cooled below 1100 K before fuel attack. 10 refs., 3 figs., 4 tabs

  19. An experimental study about efficacy of the drain catheters

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Bum Gyu; Nho, Joon Young; Woo, Hyo Cheol; Hwang, Woo Cheol; Park, Choong Ki; Yoon, Jong Sup [Hallym University College of Medicine, Seoul (Korea, Republic of)

    1993-09-15

    Although percutaneous abscess drainage has become and accepted alternative from of therapy for selected patients with abscess, it is well known that there are several factors in the failure of adequate drainage such as pre- and post-procedural management, technique itself, various features of abscess, and selection and application of catheters. Among these factors, we made an experiment about drainage efficacy of commonly used various catheters with different viscosities of water-glycerin solution under the two different pressure gradients. The experimental values of flow rate were very lower than the calculated values. An efficacy of experimental value was 4-14%. Because the inner diameter of fittings and stopcocks was usually smaller than the inner diameter of catheters, these factors also affected the drain efficacy. Finally, we thought that it will be very helpful to the treatment of patient as well as to study about the catheter drainage, if the drain efficacy of individual catheters has been notified.

  20. Evaluation of stream crossing methods prior to gas pipeline construction

    International Nuclear Information System (INIS)

    Murphy, M.H.; Rogers, J.S.; Ricca, A.

    1995-01-01

    Stream surveys are conducted along proposed gas pipeline routes prior to construction to assess potential impacts to stream ecosystems and to recommend preferred crossing methods. Recently, there has been a high level of scrutiny from the Public Service Commission (PSC) to conduct these stream crossings with minimal effects to the aquatic community. PSC's main concern is the effect of sediment on aquatic biota. Smaller, low flowing or intermittent streams are generally crossed using a wet crossing technique. This technique involves digging a trench for the pipeline while the stream is flowing. Sediment control measures are used to reduce sediment loads downstream. Wider, faster flowing, or protected streams are typically crossed with a dry crossing technique. A dry crossing involves placing a barrier upstream of the crossing and diverting the water around the crossing location. The pipeline trench is then dug in the dry area. O'Brien and Gere and NYSEG have jointly designed a modified wet crossing for crossing streams that exceed maximum flows for a dry crossing, and are too wide for a typical wet crossing. This method diverts water around the crossing using a pumping system, instead of constructing a dam. The trench is similar to a wet crossing, with sediment control devices in place upstream and downstream. If streams are crossed during low flow periods, the pumping system will be able to reduce the majority of water flow and volume form the crossing area, thereby reducing ecological impacts. Evaluation of effects of this crossing type on the stream biota are currently proposed and may proceed when construction begins

  1. Should I stay or should I go? An institutional approach to brain drain

    OpenAIRE

    Cassar, Lea; Frey, Bruno S

    2010-01-01

    This paper suggests that institutional factors which reward social net- works at the expenses of productivity can play an important role in ex- plaining brain drain. The e€ects of social networks on brain drain are analyzed in a decision theory framework with asymmetric information. We distinguish between the role of insidership and personal connections. The larger the cost of being an outsider, the smaller is the number and the average ability of researchers working in the domestic job mar...

  2. Risk assessment of K basin twelve-inch drain valve failure from a postulated seismic initiating event

    International Nuclear Information System (INIS)

    MORGAN, R.G.

    1999-01-01

    The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rates which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations suggest that only the valve's bonnet and stem are exposed above the basin concrete floor. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this activity are to: (1) evaluate the risk of damaging the three twelve-inch drain valves located along the north wall of the main basin from a seismic initiating event, and (2) determine the associated potential leak rate from a damaged valve

  3. Risk assessment of K basin twelve-inch drain valve failure from a postulated seismic initiating event

    Energy Technology Data Exchange (ETDEWEB)

    MORGAN, R.G.

    1999-04-06

    The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rates which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations suggest that only the valve's bonnet and stem are exposed above the basin concrete floor. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this activity are to: (1) evaluate the risk of damaging the three twelve-inch drain valves located along the north wall of the main basin from a seismic initiating event, and (2) determine the associated potential leak rate from a damaged valve.

  4. Comparison consequences of Jackson-Pratt drain versus chest tube after coronary artery bypass grafting: A randomized controlled clinical trial

    Directory of Open Access Journals (Sweden)

    Mohsen Mirmohammad-Sadeghi

    2017-01-01

    Full Text Available Background: Chest tubes are used in every case of coronary artery bypass grafting (CABG to evacuate shed blood from around the heart and lungs. This study was designed to assess the effective of Jackson-Pratt drain in compare with conventional chest drains after CABG. Materials and Methods: This was a randomized controlled trial that conducted on 218 patients in Chamran hospital from February to December 2016. Eligible patients were randomized in a 1:1 ratio. Jackson-Pratt drain group had 109 patients who received a chest tube insertion in the pleural space of the left lung and a Jackson-Pratt drain in mediastinum, and Chest tube drainage group had 109 patients who received double chest tube insertion in the pleural space of the left lung and the mediastinum. Results: The incidence of pleural effusions in Jackson-Pratt drain group and chest tube group were not statistically different. The pain score at 2-h in Drain group was significantly higher than chest tube group (P = 0.001, but the trend of pain score between groups was not significantly different (P = 0.097. The frequency of tamponade and atrial fibrillation (AF were significantly lower in Jackson-Pratt drain group (P < 0.05. Conclusion: The Jackson-Pratt drain is equally effective for preventing cardiac tamponade, pleural effusions, and pain intensity in patients after CABG when compared with conventional chest tubes, but was significantly superior regarding efficacy to hospital and Intensive Care Unit length of stay and the incidence of AF.

  5. Groundwater declines are linked to changes in Great Plains stream fish assemblages.

    Science.gov (United States)

    Perkin, Joshuah S; Gido, Keith B; Falke, Jeffrey A; Fausch, Kurt D; Crockett, Harry; Johnson, Eric R; Sanderson, John

    2017-07-11

    Groundwater pumping for agriculture is a major driver causing declines of global freshwater ecosystems, yet the ecological consequences for stream fish assemblages are rarely quantified. We combined retrospective (1950-2010) and prospective (2011-2060) modeling approaches within a multiscale framework to predict change in Great Plains stream fish assemblages associated with groundwater pumping from the United States High Plains Aquifer. We modeled the relationship between the length of stream receiving water from the High Plains Aquifer and the occurrence of fishes characteristic of small and large streams in the western Great Plains at a regional scale and for six subwatersheds nested within the region. Water development at the regional scale was associated with construction of 154 barriers that fragment stream habitats, increased depth to groundwater and loss of 558 km of stream, and transformation of fish assemblage structure from dominance by large-stream to small-stream fishes. Scaling down to subwatersheds revealed consistent transformations in fish assemblage structure among western subwatersheds with increasing depths to groundwater. Although transformations occurred in the absence of barriers, barriers along mainstem rivers isolate depauperate western fish assemblages from relatively intact eastern fish assemblages. Projections to 2060 indicate loss of an additional 286 km of stream across the region, as well as continued replacement of large-stream fishes by small-stream fishes where groundwater pumping has increased depth to groundwater. Our work illustrates the shrinking of streams and homogenization of Great Plains stream fish assemblages related to groundwater pumping, and we predict similar transformations worldwide where local and regional aquifer depletions occur.

  6. Watershed regressions for pesticides (warp) models for predicting atrazine concentrations in Corn Belt streams

    Science.gov (United States)

    Stone, Wesley W.; Gilliom, Robert J.

    2012-01-01

    Watershed Regressions for Pesticides (WARP) models, previously developed for atrazine at the national scale, are improved for application to the United States (U.S.) Corn Belt region by developing region-specific models that include watershed characteristics that are influential in predicting atrazine concentration statistics within the Corn Belt. WARP models for the Corn Belt (WARP-CB) were developed for annual maximum moving-average (14-, 21-, 30-, 60-, and 90-day durations) and annual 95th-percentile atrazine concentrations in streams of the Corn Belt region. The WARP-CB models accounted for 53 to 62% of the variability in the various concentration statistics among the model-development sites. Model predictions were within a factor of 5 of the observed concentration statistic for over 90% of the model-development sites. The WARP-CB residuals and uncertainty are lower than those of the National WARP model for the same sites. Although atrazine-use intensity is the most important explanatory variable in the National WARP models, it is not a significant variable in the WARP-CB models. The WARP-CB models provide improved predictions for Corn Belt streams draining watersheds with atrazine-use intensities of 17 kg/km2 of watershed area or greater.

  7. Wound healing without drains in posterior spinal fusion in idiopathic scoliosis

    International Nuclear Information System (INIS)

    Alsiddiky, A.; Nisar, K.A.; Alhuzaimi, F.; Albishi, W.; Alnuaim, B.; Albarrag, M.; Meo, S.A.

    2013-01-01

    To determine the frequency of wound infection and neurological injuries in patients with idiopathic scoliosis who underwent posterior spinal fusion without use of drains. Study Design: Case series. Place and Duration of Study: Department of Orthopaedics, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia, from February 2007 to June 2010. Methodology: Patients who underwent similar technique of posterior spinal fusion instrumentation for the correction of scoliosis without use of drain were included. Wound Demographics, wound healing, complications and duration of hospital stay were considered and described as frequency and mean values. Results: The average age at the time of surgery was 12.80 +- 1.30 years, duration of surgery was 3.80 +- 0.86 hours, hospital stay was 3.84 +- 0.78 days and patients were followed-up over the last 30 months. There was no incidence of any neurological complication and deep infection. However, only 2 (4.16%) cases with superficial skin infection were treated with dressing and antibiotics with full recovery. Conclusion: The wound healing is adequate without using drain for patients with idiopathic scoliosis who underwent posterior spinal fusion and instrumentation when good wash, watertight closure technique and appropriate antibiotics coverage is provided. (author)

  8. Short-channel drain current model for asymmetric heavily/lightly ...

    Indian Academy of Sciences (India)

    The paper presents a drain current model for double gate metal oxide semiconductor field effect transistors (DG MOSFETs) based on a new velocity saturation model that accounts for short-channel velocity saturation effect independently in the front and the back gate controlled channels under asymmetric front and back ...

  9. SEDIMENTATION IN PACIFIC NORTHWEST COASTAL STREAMS -- EVIDENCE FROM REGIONAL SURVEY OF BED SUBSTRATE SIZE AND STABILITY

    Science.gov (United States)

    Excessive erosion, transport and deposition of sediment are major problems in streams and rivers throughout the United States. We examined evidence of anthropogenic sedimentation in Oregon and Washington coastal streams using relatively rapid measurements taken from surveys duri...

  10. Design and construction of a French drain for groundwater diversion in solid waste storage area six at the Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    Davis, E.C.; Stansfield, R.G.

    1984-05-01

    Engineering modifiations or engineered barriers have been suggested as a possible means of improving the performance of low-level waste disposal sites located in the humid eastern United States. Design and construction of a passive French drain, located in Solid Waste Storage Area No. 6 at the Oak Ridge National Laboratory. The drain was designed to hydrologically isolate a 0.44-ha area that contains a group of 49 low-level waste trenches by separating it from upgradient groundwater recharge areas. The 252-m drain (maximum depth = 9 m) that surrounds the group of trenches on the north and east sides was excavated, lined with filter fabric, backfilled with crushed stone, and covered with a 0.6 m layer of excavated material at an estimated cost of $153,000. Of the 17 days it took to complete the work, about 5 days were spent excavating sidewall slide material that fell into the drain during excavation. Photography of the drain wall revealed the contorted structure of the weathered shale, which was responsible for many of the slides. Monitoring wells placed at intervals on the drain centerline indicate that groundwater is draining from the surrounding Maryville Formation (Conasauga Group); flows at catch basin No. 2 ranged from a base flow of 4 to 7 L/min to a maximum of 35 L/min, recorded on October 13. In response to groundwater flow in the drain, water levels in several monitoring wells adjacent to the drain have dropped by as much as 2.24 m to an elevation only slightly higher than the bottom of the French drain. In addition to the general lowering of the water table in the vicinity of the drain, water levels in three trenches began to subside, indicating that the drain is beginning to have an effect on the water in the trenches as well. Further monitoring of both drain discharge and water levels in monitoring wells across the site is continuing

  11. Drained Triaxial Tests on Eastern Scheldt Sand

    DEFF Research Database (Denmark)

    Praastrup, U.; Jakobsen, Kim Parsberg

    In the process of understanding and developing models for geomaterials, the stress-strain behaviour is commonly studied by performing triaxial tests. In the present study static triaxial tests have been performed to gain knowledge of the stress-strain behaviour of frictional materials during...... monotonic loading. The tests reported herein are all drained tests, starting from different initial states of stress and following various stress paths. AIl the tests are performed on reconstituted medium dense specimens of Eastern Scheldt Sand....

  12. Water Table Recession in Subsurface Drained Soils

    OpenAIRE

    Moustafa, Mahmoud Mohamed; Yomota, Atsushi

    1999-01-01

    Theoretical drainage equations are intensively tested in many parts of humid and arid regions and are commonly used in drainage design. However, this is still a great concern in Japan as the drainage design is exclusively based on local experiences and empirical basis. There is a need therefore to evaluate the theoretical drainage equations under Japanese field conditions to recommend equations for design of subsurface drainage systems. This was the main motivation for this study. While drain...

  13. No-Drain Single Incision Liposuction Pull-Through Technique for Gynecomastia.

    Science.gov (United States)

    Khalil, Ashraf A; Ibrahim, Amr; Afifi, Ahmed M

    2017-04-01

    Several different methods have been proposed for treatment of gynecomastia, depending on the amount of breast enlargement and skin redundancy. The liposuction pull-through technique has been proposed as an efficacious treatment for many gynecomastia cases. This work aims to study the outcome of this technique when applied as an outpatient procedure, without the use of drains and through a single incision. Fifty-two patients with bilateral gynecomastia without significant skin excess were included in this study. The liposuction pull-through technique was performed through a single incision just above the inframammary fold and without the use of drains. Patients were followed up for 6 months. The proposed technique was able to treat the gynecomastia in all patients, with a revision rate of 1.9% to remove residual glandular tissues. There were no seromas, hematomas, nipple distortion, permanent affection of nipple sensation or wound healing problems. The liposuction pull-through technique is an effective treatment for gynecomastia without significant skin redundancy. It combines the benefits of the direct excision of glandular tissues, with the minimally invasive nature of liposuction. Performing the procedure through a single incision without the use of drains and without general anesthesia is a safe alternative. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266 .

  14. Theoretical computation background for transformation of foundations using pile drains

    Directory of Open Access Journals (Sweden)

    Ter-Martirosyan Zaven

    2017-01-01

    Full Text Available In the design of foundations for buildings and structures of various purposes, including improved risk, weak water-saturated clay soils with low mechanical characteristics are often found on a construction site. One of the possible ways of using them as a foundation is to seal them in various ways, including using pile drains of sand or rock stone material that are capable of both absorbing the load at the base and accelerating the process of filtration consolidation. This paper describes an analytical solution to the problem of interaction between the pile and the mattress with the surrounding soil of the foundation, taking into account the possibility of expanding the pile shaft. Solutions are obtained for determining the stresses in the shaft of the pile drain and in the soil under the mattress. The solution takes into account the influence of the pre-stressed state of the foundation after compaction on the formation of a stress-strain state during the erection and operation of structures. The solutions are relevant for consolidating pile drains made of rubble or for jet grouting piles, the rigidity of which is comparable to the rigidity of the surrounding soil. The paper describes the technique for determining the characteristics of the strength and deformability of the converted foundation and the results of large-scale tests at the experimental site for the construction of a large energy facility in Russia.

  15. Effects of low concentrations of glyphosate-based herbicide factor 540® on an agricultural stream freshwater phytoplankton community.

    Science.gov (United States)

    Smedbol, Élise; Gomes, Marcelo Pedrosa; Paquet, Serge; Labrecque, Michel; Lepage, Laurent; Lucotte, Marc; Juneau, Philippe

    2018-02-01

    Residual glyphosate from glyphosate based herbicides (GBH) are ubiquitously detected in streams draining agricultural fields, and may affect phytoplankton communities present in these ecosystems. Here, the effects of the exposure (96 h) of a phytoplankton community collected in an agricultural stream to various glyphosate concentrations (1, 5, 10, 50, 100, 500 and 1000 μg l -1 ) of Factor 540 ® GBH were investigated. The lowest GBH concentration of 1 μg l -1 reduced chlorophyll a and carotenoid contents. Low glyphosate concentrations, such as 5 and 10 μg l -1 , promoted changes in the community's structure and reduced the diversity of the main algal species. At glyphosate concentrations ranging from 50 to 1000 μg l -1 , the phytoplankton community's composition was modified and new main species appeared. The highest glyphosate concentrations (500 and 1000 μg l -1 ) affected the shikimate content, the lipid peroxidation and the activity of antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase). These results indicate that GBH can modify structural and functional properties of freshwater phytoplankton communities living in streams located in agricultural areas at glyphosate concentrations much inferior to the 800 μg l -1 threshold set by the Canadian guidelines for the protection of aquatic life. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  16. Uranium hydrogeochemical and stream sediment reconnaissance of the Bozeman NTMS quadrangle, Montana

    International Nuclear Information System (INIS)

    Bolivar, S.L.

    1978-11-01

    A total of 1251 water and 1536 sediment samples were collected from 1586 locations over a 17 400-km 2 area at a nominal density of one location per 10 km 2 . Samples were collected predominantly from surface streams although 38 ground water locations were also sampled. The uranium concentrations in waters sampled range from below the detection limit of 0.20 ppB to 41.35 ppB, with a mean concentration of 1.17 ppB. Waters with anomalous uranium concentrations as defined were found in tributaries of the Boulder River which drain Precambrian rocks in the Beartooth Mountains and in tributaries of the Three Forks basin which are underlain predominantly by Tertiary-Quaternary sediments. The two areas appearing most favorable for future exploration on the basis of water data are in the Three Forks basin in the vicinity of the Madison plateau and in a district about 20 km due west of Three Forks. Sediment samples from the quadrangle were found to have uranium concentrations that range from 0.90 ppM to 94.30 ppM, with a mean concentration of 3.71 ppM. The majority of anomalous sediment samples were collected from areas underlain by Precambrian rocks. Based on the data from sediments, the areas appearing most favorable for future exploration include the tributaries of the Boulder River in the Beartooth Mountains, the northern part of the Madison Range, and the Tobacco Root Mountains just north of Virginia City. The uranium concentrations in the sediments from these areas are probably associated with uraniferous siliceous veins or pegmatites

  17. 40 CFR 63.136 - Process wastewater provisions-individual drain systems.

    Science.gov (United States)

    2010-07-01

    ... restricts wind motion across the open area between the pipe and the drain) that encloses the space between...., there is no pump) or is operated with no more than slight fluctuations in the liquid level, the owner or...

  18. Thermal-fluid analysis of the fill and drain operations of a cryrogenic fuel tank

    Science.gov (United States)

    Stephens, Craig A.; Hanna, Gregory J.; Gong, Leslie

    1993-01-01

    The Generic Research Cryogenic Tank was designed to establish techniques for testing and analyzing the behavior of reusable fuel tank structures subjected to cryogenic fuels and aerodynamic heating. The Generic Research Cryogenic Tank tests will consist of filling a pressure vessel to a prescribed fill level, waiting for steady-state conditions, then draining the liquid while heating the external surface to simulate the thermal environment associated with hypersonic flight. Initial tests of the Generic Research Cryogenic Tank will use liquid nitrogen with future tests requiring liquid hydrogen. Two-dimensional finite-difference thermal-fluid models were developed for analyzing the behavior of the Generic Research Cryogenic Tank during fill and drain operations. The development and results of the two-dimensional fill and drain models, using liquid nitrogen, are provided, along with results and discussion on extrapolating the model results to the operation of the full-size Generic Research Cryogenic Tank. These numerical models provided a means to predict the behavior of the Generic Research Cryogenic Tank during testing and to define the requirements for the Generic Research Cryogenic Tank support systems such as vent, drain, pressurization, and instrumentation systems. In addition, the fill model provided insight into the unexpected role of circumferential conduction in cooling the Generic Research Cryogenic Tank pressure vessel during fill operations.

  19. Low-frequency variation of a zonally localized jet stream: Observation and theory

    International Nuclear Information System (INIS)

    Cai, M.

    1994-01-01

    The climatological mean circulation in the extratropics of the Northern Hemisphere is characterized by two zonally localized jet streams over the east coasts of the two major continents. The zonal inhomogeneity of the climatological mean circulation is believed to be a primary factor determining the geographical locations of the maximum activity centers of the atmospheric transients, such as storm tracks over the east coasts of the two major continents and frequent blocking episodes occurring over the central regions of the two oceans. The impact of the transients on the zonally localized jet streams is studied mostly in the linear dynamics framework in terms of so-called open-quotes feedbackclose quotes diagnosis. This study investigates nonlinear instability of a zonally localized jet stream. The emphasis is on the nonlinear adjustment of a zonally localized jet stream associated with the development of the transients via local instability. The adjustment of a zonally localized jet stream would naturally consists of two parts: One is the time-invariant part and the other is the transient part (temporal variation of the adjustment). In conjunction with the observation, the time-mean adjustment is part of the climatological mean flow and hence is open-quotes invisible.close quotes The transient part of the adjustment is evidenced by the changes of the jet streams in terms of both location and intensity. In this study, we tend to relate the transient part of the adjustment of the jet stream to the maximum activity centers of low-frequency variability. The underlying mechanisms that are responsible for the temporal variation of the adjustment will be investigated. The time-mean adjustment will be also studied to better understand the temporal variation of the adjustment

  20. Waste streams that preferentially corrode 55-gallon steel storage drums

    International Nuclear Information System (INIS)

    Zirker, L.R.; Beitel, G.A.; Reece, C.M.

    1995-06-01

    When 55-gal steel drum waste containers fail in service, i.e., leak, corrode or breach, the standard fix has been to overpack the drum. When a drum fails and is overpacked into an 83-gal overpack drum, there are several negative consequences. Identifying waste streams that preferentially corrode steel drums is essential to the pollution prevention philosophy that ''an ounce of prevention is worth a pound of cure.'' It is essential that facilities perform pollution prevention measures at the front end of processes to reduce pollution on the back end. If these waste streams can be identified before they are packaged, the initial drum packaging system could be fortified or increased to eliminate future drum failures, breaches, clean-ups, and the plethora of other consequences. Therefore, a survey was conducted throughout the US Department of Energy complex for information concerning waste streams that have demonstrated preferential corrosion of 55-gal steel drums. From 21 site contacts, 21 waste streams were so identified. The major components of these waste streams include acids, salts, and solvent liquids, sludges, and still bottoms. The solvent-based waste streams typically had the shortest time to failure, 0.5 to 2 years. This report provides the results of this survey and research

  1. A comparison of high-resolution specific conductance-based end-member mixing analysis and a graphical method for baseflow separation of four streams in hydrologically challenging agricultural watersheds

    Science.gov (United States)

    Kronholm, Scott C.; Capel, Paul D.

    2015-01-01

    Quantifying the relative contributions of different sources of water to a stream hydrograph is important for understanding the hydrology and water quality dynamics of a given watershed. To compare the performance of two methods of hydrograph separation, a graphical program [baseflow index (BFI)] and an end-member mixing analysis that used high-resolution specific conductance measurements (SC-EMMA) were used to estimate daily and average long-term slowflow additions of water to four small, primarily agricultural streams with different dominant sources of water (natural groundwater, overland flow, subsurface drain outflow, and groundwater from irrigation). Because the result of hydrograph separation by SC-EMMA is strongly related to the choice of slowflow and fastflow end-member values, a sensitivity analysis was conducted based on the various approaches reported in the literature to inform the selection of end-members. There were substantial discrepancies among the BFI and SC-EMMA, and neither method produced reasonable results for all four streams. Streams that had a small difference in the SC of slowflow compared with fastflow or did not have a monotonic relationship between streamflow and stream SC posed a challenge to the SC-EMMA method. The utility of the graphical BFI program was limited in the stream that had only gradual changes in streamflow. The results of this comparison suggest that the two methods may be quantifying different sources of water. Even though both methods are easy to apply, they should be applied with consideration of the streamflow and/or SC characteristics of a stream, especially where anthropogenic water sources (irrigation and subsurface drainage) are present.

  2. Physicochemical, Proximate and Sensory Properties of Pineapple (Ananas sp.) Syrup Developed from Its Organic Side-Stream

    NARCIS (Netherlands)

    Tortoe, C.; Johnson, P.N.T.; Slaghek, T.; Miedema, M.; Timmermans, T.

    2013-01-01

    A major economical industrial challenge from pineapple (Ananas sp.) processing contributing to environmental pollu- tion is the organic side-streams of pineapple. The physicochemical, proximate and sensory properties of organic side- stream pineapple syrup (OSPS) developed from Smooth cayenne, Sugar

  3. Subsurface lateral flow from hillslope and its contribution to nitrate loading in streams through an agricultural catchment during subtropical rainstorm events

    Directory of Open Access Journals (Sweden)

    B. Zhang

    2011-10-01

    Full Text Available Subsurface lateral flow from agricultural hillslopes is often overlooked compared with overland flow and tile drain flow, partly due to the difficulties in monitoring and quantifying. The objectives of this study were to examine how subsurface lateral flow generated through soil pedons from cropped hillslopes and to quantify its contribution to nitrate loading in the streams through an agricultural catchment in the subtropical region of China. Profiles of soil water potential along hillslopes and stream hydro-chemographs in a trenched stream below a cropped hillslope and at the catchment outlet were simultaneously recorded during two rainstorm events. The dynamics of soil water potential showed positive matrix soil water potential over impermeable soil layer at 0.6 to 1.50 m depths during and after the storms, indicating soil water saturation and drainage processes along the hillslopes irrespective of land uses. The hydro-chemographs in the streams, one trenched below a cropped hillslope and one at the catchment outlet, showed that the concentrations of particulate nitrogen and phosphorus corresponded well to stream flow during the storm, while the nitrate concentration increased on the recession limbs of the hydrographs after the end of the storm. All the synchronous data revealed that nitrate was delivered from the cropped hillslope through subsurface lateral flow to the streams during and after the end of the rainstorms. A chemical mixing model based on electricity conductivity (EC and H+ concentration was successfully established, particularly for the trenched stream. The results showed that the subsurface lateral flow accounted for 29% to 45% of total stream flow in the trenched stream, responsible for 86% of total NO3-N loss (or 26% of total N loss, and for 5.7% to 7.3% of total stream flow at the catchment outlet, responsible for about 69% of total NO3-N loss (or 28% of total N

  4. Systematic review and meta-analysis of wound drains after thyroid surgery.

    LENUS (Irish Health Repository)

    Woods, R S R

    2014-04-01

    Drainage after routine thyroid and parathyroid surgery remains controversial. However, there is increasing evidence from a number of randomized clinical trials (RCTs) suggesting no benefit from the use of drains.

  5. StreamCat

    Data.gov (United States)

    U.S. Environmental Protection Agency — The StreamCat Dataset provides summaries of natural and anthropogenic landscape features for ~2.65 million streams, and their associated catchments, within the...

  6. Stream Crossings

    Data.gov (United States)

    Vermont Center for Geographic Information — Physical measurements and attributes of stream crossing structures and adjacent stream reaches which are used to provide a relative rating of aquatic organism...

  7. Brain drain and health workforce distortions in Mozambique.

    Science.gov (United States)

    Sherr, Kenneth; Mussa, Antonio; Chilundo, Baltazar; Gimbel, Sarah; Pfeiffer, James; Hagopian, Amy; Gloyd, Stephen

    2012-01-01

    Trained human resources are fundamental for well-functioning health systems, and the lack of health workers undermines public sector capacity to meet population health needs. While external brain drain from low and middle-income countries is well described, there is little understanding of the degree of internal brain drain, and how increases in health sector funding through global health initiatives may contribute to the outflow of health workers from the public sector to donor agencies, non-governmental organisations (NGOs), and the private sector. An observational study was conducted to estimate the degree of internal and external brain drain among Mozambican nationals qualifying from domestic and foreign medical schools between 1980-2006. Data were collected 26-months apart in 2008 and 2010, and included current employment status, employer, geographic location of employment, and main work duties. Of 723 qualifying physicians between 1980-2006, 95.9% (693) were working full-time, including 71.1% (493) as clinicians, 20.5% (142) as health system managers, and 6.9% (48) as researchers/professors. 25.5% (181) of the sample had left the public sector, of which 62.4% (113) continued working in-country and 37.6% (68) emigrated from Mozambique. Of those cases of internal migration, 66.4% (75) worked for NGOs, 21.2% (24) for donor agencies, and 12.4% (14) in the private sector. Annual incidence of physician migration was estimated to be 3.7%, predominately to work in the growing NGO sector. An estimated 36.3% (41/113) of internal migration cases had previously held senior-level management positions in the public sector. Internal migration is an important contributor to capital flight from the public sector, accounting for more cases of physician loss than external migration in Mozambique. Given the urgent need to strengthen public sector health systems, frank reflection by donors and NGOs is needed to assess how hiring practices may undermine the very systems they seek

  8. India: 'brain drain' or the migration of talent?

    Science.gov (United States)

    Oommen, T K

    1989-09-01

    2 views on "brain drain" exist: 1) LDCs lose their enormous investments on higher education when skilled people migrate to other countries and 2) LDCs are exaggerating the problem and only a few skilled people migrate at 1 time. India does not completely lose its investment in education when professionals migrate, since the migrants still contribute to knowledge and also send remittances to relatives in India. Unemployed educated people would cause a greater drain on India's resources than educated migrants. The author prefers the phrase migration of talent to brain drain, since the former indicates a 2-way movement. Most migrants from LDCs are students. About 11,000 university graduates leave India every year for advanced study and/or work. A conservative estimate is that 2500 will remain abroad permanently. Most professionals who migrate go to the US and Canada. Factors promoting migration include 1) unemployment, 2) immigration rules, 3) colonial links, 4) financial incentives and material benefits, 5) pursuit of higher education, 6) improvement of working conditions and facilities, 7) avoidance of excessive bureaucratic procedures, and 8) compensation for the mismatch between Indian education and employment. Reasons for returning to India include 1) deference to wives who were unable to adjust to a foreign way of life, 2) contributing to Indian development, and 3) racial discrimination. It will probably not be possible to lure back migrants who left for material reasons. Attractive job offers could entice back those who left for advanced training. To encourage the return of those who left to pursue high quality research, India must 1) increase expenditure on research and development, possibly through the private industrial sector, 2) promote travel to other countries for professional enrichment, and 3) improve conditions of research work. The article concludes with an analysis of migration of talent from 3 perspectives: 1) the individual, 2) the nation

  9. Brain drain and health workforce distortions in Mozambique.

    Directory of Open Access Journals (Sweden)

    Kenneth Sherr

    Full Text Available Trained human resources are fundamental for well-functioning health systems, and the lack of health workers undermines public sector capacity to meet population health needs. While external brain drain from low and middle-income countries is well described, there is little understanding of the degree of internal brain drain, and how increases in health sector funding through global health initiatives may contribute to the outflow of health workers from the public sector to donor agencies, non-governmental organisations (NGOs, and the private sector.An observational study was conducted to estimate the degree of internal and external brain drain among Mozambican nationals qualifying from domestic and foreign medical schools between 1980-2006. Data were collected 26-months apart in 2008 and 2010, and included current employment status, employer, geographic location of employment, and main work duties.Of 723 qualifying physicians between 1980-2006, 95.9% (693 were working full-time, including 71.1% (493 as clinicians, 20.5% (142 as health system managers, and 6.9% (48 as researchers/professors. 25.5% (181 of the sample had left the public sector, of which 62.4% (113 continued working in-country and 37.6% (68 emigrated from Mozambique. Of those cases of internal migration, 66.4% (75 worked for NGOs, 21.2% (24 for donor agencies, and 12.4% (14 in the private sector. Annual incidence of physician migration was estimated to be 3.7%, predominately to work in the growing NGO sector. An estimated 36.3% (41/113 of internal migration cases had previously held senior-level management positions in the public sector.Internal migration is an important contributor to capital flight from the public sector, accounting for more cases of physician loss than external migration in Mozambique. Given the urgent need to strengthen public sector health systems, frank reflection by donors and NGOs is needed to assess how hiring practices may undermine the very systems they

  10. Transition and the problem of 'brain drain' from the perspective of students of a privately owned university

    Directory of Open Access Journals (Sweden)

    Vasiljević-Blagojević Milica R.

    2016-01-01

    Full Text Available The problem of brain drain is not a new problem in underdeveloped countries and those in transition. Young educated people leave their countries seeking better future, which further damages already weakened economy while the developed countries become even stronger. According to the data of the World Economic Forum, Srbija holds the second place in brain drain. The cited problem is usually analyzed by checking the students of the state owned universities whose studies are financed by the Republic of Serbia. The authors were motivated to explore the same problem but with the students of privately owned universities. Our explorative research was aimed at revealing the attitudes of these students towards leaving the country and work or study abroad. The research included 226 graduate and master students of the Faculty of digital arts, IT Faculty, the Faculty of Management and the Metropolitan University. The sample was deliberately selected. The majority of the responders (two thirds are increasingly interested in finding jobs abroad. This initial research was aimed at identification of the reasons for leaving the country. The respondents state that the reasons are better life conditions, chances for getting job, further studying and bad political and economic situation in the country, poorly paid jobs, new experiences and possibilities of promotion.

  11. Remote sensing for assessing the zone of benefit where deep drains improve productivity of land affected by shallow saline groundwater.

    Science.gov (United States)

    Kobryn, H T; Lantzke, R; Bell, R; Admiraal, R

    2015-03-01

    The installation of deep drains is an engineering approach to remediate land salinised by the influence of shallow groundwater. It is a costly treatment and its economic viability is, in part, dependent on the lateral extent to which the drain increases biological productivity by lowering water tables and soil salinity (referred to as the drains' zone of benefit). Such zones may be determined by assessing the biological productivity response of adjacent vegetation over time. We tested a multi-temporal satellite remote sensing method to analyse temporal and spatial changes in vegetation condition surrounding deep drainage sites at five locations in the Western Australian wheatbelt affected by dryland salinity-Morawa, Pithara, Beacon, Narembeen and Dumbleyung. Vegetation condition as a surrogate for biological productivity was assessed by Normalised Difference Vegetation Index (NDVI) during the peak growing season. Analysis was at the site scale within a 1000 m buffer zone from the drains. There was clear evidence of NDVI increasing with elevation, slope and distance from the drain. After accounting for elevation, slope and distance from the drain, there was a significant increase in NDVI across the five locations after installation of deep drains. Changes in NDVI after drainage were broadly consistent with measured changes at each site in groundwater levels after installation of the deep drains. However, this study assessed the lateral extent of benefit for biological productivity and gave a measure of the area of benefit along the entire length of the drain. The method demonstrated the utility of spring NDVI images for rapid and relatively simple assessment of the change in site condition after implementation of drainage, but approaches for further improvement of the procedure were identified. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. A COMPARATIVE STUDY IN HERNIOPLASTY WITH AND WITHOUT DRAIN AND THE ASSOCIATED COMPLICATIONS

    Directory of Open Access Journals (Sweden)

    Amruthavalli Bayya Venkatesulu

    2017-03-01

    Full Text Available BACKGROUND The present study is a comparative study to compare in Lichtenstein’s mesh repair, the need of a subcutaneous suction drain in inguinal hernias at Government General Hospital, Guntur. To study the advantages and disadvantages of using subcutaneous suction drain in Lichtenstein’s hernioplasty. MATERIALS AND METHODS In the present study, out of 50 patients,32% of patients who had undergone drainage group complained of pain and 8% of patients who had undergone non-drainage complained of pain. In our study, 0% and 4% of patients developed haematoma in drainage and non-drainage group, respectively. 12% of patients in drainage group developed seroma and 12% of patients in non-drainage group developed seroma. In the present study, 16% of cases in drainage and 20% in non-drainage group. In the present study, patients in drainage group mean postoperative hospital stay is 9.1 days and in non-drainage group is 6.7 days. The average duration of postoperative hospital stay in patients of drainage group is higher than in non-drainage group with the above results, the early postoperative complications like pain, mean postoperative stay in hospital are increased in Lichtenstein’s with drainage group. The early postoperative complications like seroma, haematoma and wound infection rates are similar in both drainage and non-drainage groups. So, it appears that suction drain usage can be restricted in Lichtenstein’s tension free mesh repair in simple inguinal hernias unless the hernia is complicated or there is extensive dissection. RESULTS The details of all the (50 cases were drawn as master chart with regard of relevance. Statistical analysis was done using Epi info version 3.5.3. P value is calculated using Chi-square test. CONCLUSION In the present study, 50 patients with inguinal hernia who had undergone Lichtenstein’s hernioplasty with subcutaneous suction drain are compared with those who had undergone Lichtenstein’s hernioplasty

  13. Prioritized Contact Transport Stream

    Science.gov (United States)

    Hunt, Walter Lee, Jr. (Inventor)

    2015-01-01

    A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

  14. Re-Meandering of Lowland Streams

    DEFF Research Database (Denmark)

    Pedersen, Morten Lauge; Kristensen, Klaus Kevin; Friberg, Nikolai

    2014-01-01

    We evaluated the restoration of physical habitats and its influence on macroinvertebrate community structure in 18 Danish lowland streams comprising six restored streams, six streams with little physical alteration and six channelized streams. We hypothesized that physical habitats...... and macroinvertebrate communities of restored streams would resemble those of natural streams, while those of the channelized streams would differ from both restored and near-natural streams. Physical habitats were surveyed for substrate composition, depth, width and current velocity. Macroinvertebrates were sampled...... along 100 m reaches in each stream, in edge habitats and in riffle/run habitats located in the center of the stream. Restoration significantly altered the physical conditions and affected the interactions between stream habitat heterogeneity and macroinvertebrate diversity. The substrate in the restored...

  15. A novel gate and drain engineered charge plasma tunnel field-effect transistor for low sub-threshold swing and ambipolar nature

    Science.gov (United States)

    Yadav, Dharmendra Singh; Raad, Bhagwan Ram; Sharma, Dheeraj

    2016-12-01

    In this paper, we focus on the improvement of figures of merit for charge plasma based tunnel field-effect transistor (TFET) in terms of ON-state current, threshold voltage, sub-threshold swing, ambipolar nature, and gate to drain capacitance which provides better channel controlling of the device with improved high frequency response at ultra-low supply voltages. Regarding this, we simultaneously employ work function engineering on the drain and gate electrode of the charge plasma TFET. The use of gate work function engineering modulates the barrier on the source/channel interface leads to improvement in the ON-state current, threshold voltage, and sub-threshold swing. Apart from this, for the first time use of work function engineering on the drain electrode increases the tunneling barrier for the flow of holes on the drain/channel interface, it results into suppression of ambipolar behavior. The lowering of gate to drain capacitance therefore enhanced high frequency parameters. Whereas, the presence of dual work functionality at the gate electrode and over the drain region improves the overall performance of the charge plasma based TFET.

  16. Effects of Urbanization on the Flow Regimes of Semi-Arid Southern California Streams

    Science.gov (United States)

    Hawley, R. J.; Bledsoe, B. P.; Stein, E. D.

    2010-12-01

    Stream channel erosion and associated habitat degradation are pervasive in streams draining urban areas in the southwestern US. The prevalence of these impacts results from the inherent sensitivity of streams in semi-arid climates to changes in flow and sediment regimes, and past inattention to management of geomorphically effective flows. Addressing this issue is difficult due to the lack of data linking ranges of flow (from small to large runoff events) to geomorphic channel response. Forty-three U. S. Geological Survey gages with record lengths greater than ~15 yrs and watershed areas less than ~250 square kilometers were used to empirically model the effects of urbanization on streams in southern California. The watersheds spanned a gradient of urban development and ranged from 0 to 23% total impervious area in 2001. With little flow control at the subdivision scale to date, most impervious area in the region is relatively well-connected to surface-drainage networks. Consequently, total impervious area was an effective surrogate for urbanization, and emerged as a significant (p approach expands on previous scaling procedures to produce histogram-style cumulative flow duration graphs for ungaged sites based on urbanization extent and other watershed descriptors. Urbanization resulted in proportionally-longer durations of all geomorphically-effective flows, with a more pronounced effect on the durations of moderate flows. For example, an average watershed from the study domain with ~20% imperviousness could experience five times as many days of mean daily flows on the order of 100 cfs (3 cubic meters per second) and approximately three times as many days on the order of 1,000 cfs (30 cubic meters per second) relative to the undeveloped setting. Increased duration of sediment-transporting flows is a primary driver of accelerated changes in channel form that are often concurrent with urbanization throughout southern California, particularly in unconfined, fine

  17. StreamExplorer: A Multi-Stage System for Visually Exploring Events in Social Streams.

    Science.gov (United States)

    Wu, Yingcai; Chen, Zhutian; Sun, Guodao; Xie, Xiao; Cao, Nan; Liu, Shixia; Cui, Weiwei

    2017-10-18

    Analyzing social streams is important for many applications, such as crisis management. However, the considerable diversity, increasing volume, and high dynamics of social streams of large events continue to be significant challenges that must be overcome to ensure effective exploration. We propose a novel framework by which to handle complex social streams on a budget PC. This framework features two components: 1) an online method to detect important time periods (i.e., subevents), and 2) a tailored GPU-assisted Self-Organizing Map (SOM) method, which clusters the tweets of subevents stably and efficiently. Based on the framework, we present StreamExplorer to facilitate the visual analysis, tracking, and comparison of a social stream at three levels. At a macroscopic level, StreamExplorer uses a new glyph-based timeline visualization, which presents a quick multi-faceted overview of the ebb and flow of a social stream. At a mesoscopic level, a map visualization is employed to visually summarize the social stream from either a topical or geographical aspect. At a microscopic level, users can employ interactive lenses to visually examine and explore the social stream from different perspectives. Two case studies and a task-based evaluation are used to demonstrate the effectiveness and usefulness of StreamExplorer.Analyzing social streams is important for many applications, such as crisis management. However, the considerable diversity, increasing volume, and high dynamics of social streams of large events continue to be significant challenges that must be overcome to ensure effective exploration. We propose a novel framework by which to handle complex social streams on a budget PC. This framework features two components: 1) an online method to detect important time periods (i.e., subevents), and 2) a tailored GPU-assisted Self-Organizing Map (SOM) method, which clusters the tweets of subevents stably and efficiently. Based on the framework, we present Stream

  18. Laparoscopic primary repair and isoperistaltic endoluminal drain for Boerhaave's Syndrome.

    Science.gov (United States)

    Prete, Francesco; Pezzolla, Angela; Nitti, Paolo; Prete, Fernando

    2015-01-01

    Spontaneous oesophageal rupture, also known as Boerhaave syndrome (BS), is a rare and potentially lethal pathological condition. BS recognition is difficult, while rapidity of diagnosis, along with extension of the lesion, affects type and outcome of treatment. BS was classically treated by thoracotomy, but laparoscopic (LS), thoracoscopic (TS) surgery, and nonsurgical procedures as endoscopic stent positioning or use of glues have been described. Still, there is no model treatment, and selection of the most appropriate therapeutic procedure is complex in the absence of standardised criteria. We successfully managed a patient affected with BS by LS approach and present our experience along with a review of treatment options so far described. Our treatment integrated positioning of an oesophageal isoperistaltic endoluminal drain (IED), that we routinely use in oesophageal sutures at risk of leakage, and of which there is no previous report in the setting of BS. A 68 year old man presented to our attention with true BS, suspected on chest-abdominal CT scan and confirmed by upper GI contrast swallow test, showing leakage of hydro-soluble contrast from the lower third of the oesophagus. Of note, pleural cavities appeared intact. We performed an urgent laparoscopy 12 hours after the onset of symptoms. Laparoscopic toilet of the inferior mediastinum and dual layer oesophageal repair with pedicled omental flap were complemented by positioning of IED, feeding jejunostomy and two tubular drains. The patient had a slow but consistent recovery where IED played as a means of oesophageal suture protection, until he could be discharged home. We think that, when integrity of the pleura is documented, LS should be priority choice to avoid contamination of the pleural cavities. We have to consider every type of oesophageal repair in BS at risk of failure, and every means of protection of the suture is opportune. In our patient the oesophageal suture, covered with a flap of omentum

  19. Effect of One versus Two Drain Insertion on Postoperative Seroma Formation after Modified Radical Mastectomy

    Directory of Open Access Journals (Sweden)

    farzaneh ebrahimifard

    2016-04-01

    Full Text Available Background: Modified radical mastectomy (MRM is still one of globally accepted surgical techniques for breast cancer and in some selected patient is the gold standard type of surgery. The most frequent complication of this procedure is seroma under skin flaps or in the axilla as reported as much as 30% in some studies. The use of closed suction drainage system to reduce the incidence of this complication has been routinely accepted by surgeons; however, length of catheter stay and the number of catheters inserted in the wound are still controversial. The present study compares the results of single versus double drain insertion in patients undergoing MRM for breast cancer.Materials and Methods: The study was conducted on 100 women with breast cancer who were candidate for MRM surgery during 2007-2010 referred to Modarres hospital, Tehran, Iran as a randomized group matched controlled trial.Results: There was no significant difference between the two groups in terms of age, BMI, and tumor weight (P=0.406 (Table 1. Similarly, the difference between the two groups was insignificant in tumor size (T and number of lymph nodes involved (P=0.145. There was no significant difference between the two groups in timing of axillary drain removal (P=0.064. No significant differences were observed between the two groups in mean aspirated fluid (P=0.071 and mean aspirated sera (P=0.484 after removal of drains.Conclusion: This study revealed one drain insertion in MRM surgery is as effective as two drain and probably less morbidity and cost.

  20. Local Geomorphology as a Determinant of Macrofaunal Production in a Mountain Stream.

    Science.gov (United States)

    Huryn, Alexander D; Wallace, J Bruce

    1987-12-01

    ), followed by bedrock-outcrop (517-mg/m 2 ) and pool (238 mg/m 2 ). Riffles constituted 58% of total stream area and were the source of 77% of the habitat-weighted scraper production. Annual production of engulfing predators was greatest in the pool habitat (2313 mg/m 2 ), followed by riffles (1765 mg/m 2 ) and bedrock-outcrop (687 mg/m 2 ). The relatively lower production of engulfing predators in the bedrock-outcrop habitat reflects a functional shift in mode of resource acquisition by predators, with predaceous collector-filterers (Arcto-psychinae: Trichoptera) predominating in the bedrock-outcrop. Collector-gatherer production was more evenly distributed, with the bedrock-outcrop, riffle, and pool habitats each contributing 14, 54, and 33% to the habitat-weighted production, respectively. Unlike all other functional groups, this distribution was not significantly different from the distribution of stream area among habitats and reflected lack of dependence on specific physical attributes of the local environment for access to food by members of this functional group. Local geomorphology determined the diversity and spatial distribution of bedrock-outcrops, riffles, and pools in the study stream. In turn, the functional structure of the macrofauna, when viewed holistically, was the result of the integration of the relative contributions of each habitat type of total stream area. Total habitat-weighted annual production in the study stream was estimated at 5093 and 1921 mg/m 2 for primary and secondary consumers, respectively. The distribution of habitat-weighted production among functional groups was: collector-gatherers (39%), followed by shredders (225), engulfing predators (22%), scrapers (13%), and collector-filterers (8%). This functional structure agrees favorably with current conceptual models of head water streams draining forested catchments. © 1987 by the Ecological Society of America.