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Analysis of environmental issues related to small-scale hydroelectric development. III. Water level fluctuation  

Energy Technology Data Exchange (ETDEWEB)

Potential environmental impacts in reservoirs and downstream river reaches below dams that may be caused by the water level fluctuation resulting from development and operation of small scale (under 25MW) hydroelectric projects are identified. The impacts discussed will be of potential concern at only those small-scale hydroelectric projects that are operated in a store and release (peaking) mode. Potential impacts on physical and chemical characteristics in reservoirs resulting from water level fluctuation include resuspension and redistribution of bank and bed sediment; leaching of soluble organic matter from sediment in the littoral zone; and changes in water quality resulting from changes in sediment and nutrient trap efficiency. Potential impacts on reservoir biota as a result of water level fluctuation include habitat destruction and the resulting partial or total loss of aquatic species; changes in habitat quality, which result in reduced standing crop and production of aquatic biota; and possible shifts in species diversity. The potential physical effects of water level fluctuation on downstream systems below dams are streambed and bank erosion and water quality problems related to resuspension and redistribution of these materials. Potential biological impacts of water level fluctuation on downstream systems below dams result from changes in current velocity, habitat reduction, and alteration in food supply. These alterations, either singly or in combination, can adversely affect aquatic populations below dams. The nature and potential significance of adverse impacts resulting from water level fluctuation are discussed. Recommendations for site-specific evaluation of water level fluctuation at small-scale hydroelectric projects are presented.

Hildebrand, S.G. (ed.)

1980-10-01

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Water-level Fluctuations in the Eberswalde crater (Mars)  

Science.gov (United States)

The Eberswalde crater represents a spectacularly exposed example of water-related activity on Mars past geological history [1,2,3,4,5,6,7]. Eberswalde Crater at about 24.9° S., 33.7° W., lies just NE of Holden Crater and Uzboi Valles in Margaritifer Terra, Mars. We investigated the geology of this crater using MOC NA and HRSC imagery in combination with MOLA and HRSC derived DTM in order to recognize water-related processes and to infer depositional environments and depositional architecture. The fan delta located in the easternmost part of the crater presents well developed morphologies [1,2,3,4,5,6,7]. It consists of five lobes, suggesting prevalence of input related processes [4], even if wave- related processes seem to have been present as well [7]. Some of these lobes are coeval with the emplacement of synsedimentary tectonics and their morphology appears at least partly structural-controlled. The delta is made of bright and dark interlayered deposits. Some of the bright layers consist of very poorly sorted material, with boulders up to 10 meters of diameter floating in a finer matrix suggesting an emplacement as mass flows. Other layers consist of finer and better-sorted material. Most of the lobes display a low-dipping proximal area (1°-2°), a distal high-dipping area (6°-10°) and a more distal low-dipping area (1°-2°). We interpret the low dipping proximal part as delta plain consisting of distributary areas, mostly built by coalescing point bars [4,5], and interdistributary areas, in which crevasse splays flooded into the plain [7]. At places the topset-foreset-bottomset architecture typical of fan delta is present. In other cases, friction-related processes appear to be dominant. We interpret the high-dipping part of the fan delta as delta front deposits [7]. The oldest lobe display a transgressive-regressive cycle with a retrogradational stacking pattern at the base on top of which progradation develops. We interpret the retrogradational stacking pattern as formed during a Transgressive System Tract and the progradational stacking pattern related to a HighStand System Tract. The transition among these systems is marked by a Maximum Flooding Surface. A change in the morphology of the distributary channels from meandering to braided associated with a distal shift of the system appear to be related to a drop of the water level depicting a forced regression scenario. We interpret this lobe as formed during a Falling Stage System Tract. Friction-related processes appear to be dominant in this shallow-water type fan delta. The following lobe was deposited during another phase of rising water table which displays an overall aggradational stacking pattern [6,7] suggesting a certain equilibrium between sedimentary input, tectonic subsidence and level of the water table. The youngest two lobes do not display such a well developed depositional architecture, suggesting more episodic sedimentary activity. References 1. Malin, and Edgett, Science, 302, 1931-1934, 2003.2. Moore et al., Geophys. Res. Lett., 30, 24, 2292, doi: 10.1029/2003GL019002, 2003.3. Jerolmack et al., Geophys. Res. Lett., 31, L21701, doi: 10.1029/2004GL021326, 2004.4. Bhattacharya et al., Geophys. Res. Lett., 32, L10201, doi: 10.1029/2005GL022747, 2005.5. Wood, GSA Bulletin, 118, 5-6, 557-566; doi: 10.1130/B25822.1, 2006.6. Lewis and Aharanson, J. Geophys. Res., 111, E06001, doi: 10.1029/2005JE002558, 2006.7. Pondrelli et al., LPSC XXXVII, abstract 1555, 2006.

Pondrelli, M.; Rossi, A. P.; Marinangeli, L.; Hauber, E.; Baliva, A.; Gwinner, K.

2006-12-01

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Assessment of impacts from water level fluctuations on fish in the Hanford Reach, Columbia River  

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Observations on the effects of water level fluctuations in the Hanford Reach of the Columbia River, Washington, were made in 1976 and 1977. The two years provided contrasting flow regimes: high water and fluctuations of greater magnitude prevailed in 1976; low water and higher temperatures prevailed in 1977. Situations where fish and other aquatic organisms were destroyed by changing water levels were observed and evaluated each year in three study areas: Hanford, F-Area, and White Bluffs sloughs. Losses primarily were due to stranding, entrapment (with or without complete dewatering), and predation. Juvenile fish were more susceptible to entrapment and stranding than were adult fish. Estimates of actual losses were biased and conservative because relatively few fish could be found after each decline of water level and dewatering. The most valued species of fish affected by water level fluctuations at Hanford were the anadromus fall chinook salmon (Oncorhynchus tshawytscha) and the resident smallmouth bass (Micropterus dolomieui). Crucial periods for chinook salmon occurred during winter when incubating eggs were in the gravel of the main channel, and before and during seaward migration in the spring when fry were abundant in shoreline zones. The crucial period for smallmouth bass was during spring and early summer when adults were spawning in warmed sloughs and shoreline zones. Chinook salmon and smallmouth bass fry were vulnerable to stranding and entrapment, and smallmouth bass nests were susceptible to exposure and temperature changes resulting from repeated water level fluctuations. Thus, flow manipulation may be crucial to their survival. The extent to which other species of riverine fish were affected by water level fluctuations depended upon their use of shoreline zones for spawning and rearing young.

Becker, C.D.; Fickeisen, D.H.; Montgomery, J.C.

1981-05-01

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Establishment of earth tides effect on water level fluctuations in an unconfined hard rock aquifer using spectral analysis  

CERN Document Server

Short-interval water level measurements using automatic water level recorder in a deep well in an unconfined crystalline rock aquifer at the campus of NGRI, near Hyderabad shows a cyclic fluctuation in the water levels. The observed values clearly show the principal trend due to rainfall recharge. Spectral analysis was carried out to evaluate correlation of the cyclic fluctuation to the synthetic earth tides as well as groundwater withdrawal time series in the surrounding. It was found that these fluctuations have considerably high correlation with earth tides whereas groundwater pumping does not show any significant correlation with water table fluctuations. It is concluded that earth tides cause the fluctuation in the water table. These fluctuations were hitherto unobserved during manual observations made over larger time intervals. It indicates that the unconfined aquifer is characterised by a low porosity.

Maréchal, Jean-Christophe; Ahmed, Shakeel; Lachassagne, Patrick

2010-01-01

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Response of littoral macrophytes to water level fluctuations in a storage reservoir  

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Full Text Available Lakes and reservoirs that are used for water supply and/or flow regulations have usually poorly developed littoral macrophyte communities, which impairs ecological potential in terms of the EU Water Framework Directive. The aim of our study was to reveal controlling factors for the growth of littoral macrophytes in a storage reservoir with fluctuating water level (Lipno Reservoir, Czech Republic. Macrophytes occurred in this reservoir only in the eulittoral zone i.e., the shoreline region between the highest and the lowest seasonal water levels. Three eulittoral sub-zones could be distinguished: the upper eulittoral with a stable community of perennial species with high cover, the middle eulittoral with relatively high richness of emergent and amphibious species present at low cover values, and the lower eulittoral devoid of permanent vegetation. Cover and species composition in particular sub-zones were primarily influenced by the duration and timing of flooding, followed by nutrient limitation and strongly reducing conditions in the flooded organic sediment. Our results stress the ecological importance of eulittoral zone in reservoirs with fluctuating water levels where macrophyte growth can be supported by targeted management of water level, thus helping reservoir managers in improving the ecological potential of this type of water bodies.

Krolová M.

2013-05-01

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Universal Fluctuations of the Danube Water Level a Link with Turbulence, Criticality and Company Growth  

CERN Document Server

A global quantity, regardless of its precise nature, will often fluctuate according to a Gaussian limit distribution. However, in highly correlated systems, other limit distributions are possible. We have previously calculated one such distribution and have argued that this function should apply specifically, and in many instances, to global quantities that define a steady state. Here we demonstrate, for the first time, the relevance of this prediction to natural phenomena. The river level fluctuations of the Danube are observed to obey our prediction, which immediately establishes a generic statistical connection between turbulence, criticality and company growth statistics.

Bramwell, S T; Holdsworth, P C W; Portelli, B; Bramwell, Steven.T.; Fennell, Tom; Holdsworth, Peter C. W.; Portelli, Baptiste

2001-01-01

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Revegetation Strategies for Water-Level Fluctuation Zone of the Three Gorges Reservoir Region  

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Full Text Available After the full functioning of the Three Gorges Dam (TGD, the hydrologic regime will be markedly changed and most of the pre-dam vegetation in the new Water-Level Fluctuation Zone (WLFZ may fail to persist. How to revegetate WLFZ of the Three Gorges Reservoir Region (TGRR has become a hot topic for the scientific community and the governments. Based on review of scientific literature and the findings of our research, we here bring forward a scheme addressing strategies for revegetation of WLFZ of TGRR. Firstly, monitor vegetation dynamics based on permanent plots along the Three Gorges upstream from TGD, potentially providing suitable plants for the future revegetation plans. Secondly, examine the potential of soil seed bank for revegetation of the above-ground vegetation, and evaluate self-regeneration of the post-dam vegetation. Based on these data, select suitable plants for revegetation that integrate desirable physiological and life-history traits.Specifically, wetland vegetation could be constructed with lotus (Nelumbo nucifera and aquatic plants. For sites with gentle terrain and fairly hospitable soil conditions, vertical planting of trees, shrubs and grasses / forbs along the elevation gradient could be considered. To attain the sustainable vegetation cover, the newly artificial vegetation should be monitored for at least 5 years.

JIANG Ming-xi

2012-05-01

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Can mercury in fish be reduced by water level management? Evaluating the effects of water level fluctuation on mercury accumulation in yellow perch (Perca flavescens)  

Science.gov (United States)

Mercury (Hg) contamination of fisheries is a major concern for resource managers of many temperate lakes. Anthropogenic Hg contamination is largely derived from atmospheric deposition within a lake’s watershed, but its incorporation into the food web is facilitated by bacterial activity in sediments. Temporal variation in Hg content of fish (young-of-year yellow perch) in the regulated lakes of the Rainy–Namakan complex (on the border of the United States and Canada) has been linked to water level (WL) fluctuations, presumably through variation in sediment inundation. As a result, Hg contamination of fish has been linked to international regulations of WL fluctuation. Here we assess the relationship between WL fluctuations and fish Hg content using a 10-year dataset covering six lakes. Within-year WL rise did not appear in strongly supported models of fish Hg, but year-to-year variation in maximum water levels (?maxWL) was positively associated with fish Hg content. This WL effect varied in magnitude among lakes: In Crane Lake, a 1 m increase in ?maxWL from the previous year was associated with a 108 ng increase in fish Hg content (per gram wet weight), while the same WL change in Kabetogama was associated with only a 5 ng increase in fish Hg content. In half the lakes sampled here, effect sizes could not be distinguished from zero. Given the persistent and wide-ranging extent of Hg contamination and the large number of regulated waterways, future research is needed to identify the conditions in which WL fluctuations influence fish Hg content.

Larson, James H.; Maki, Ryan P.; Knights, Brent C.; Gray, Brian R.

2014-01-01

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Can mercury in fish be reduced by water level management? Evaluating the effects of water level fluctuation on mercury accumulation in yellow perch (Perca flavescens).  

Science.gov (United States)

Mercury (Hg) contamination of fisheries is a major concern for resource managers of many temperate lakes. Anthropogenic Hg contamination is largely derived from atmospheric deposition within a lake's watershed, but its incorporation into the food web is facilitated by bacterial activity in sediments. Temporal variation in Hg content of fish (young-of-year yellow perch) in the regulated lakes of the Rainy-Namakan complex (on the border of the United States and Canada) has been linked to water level (WL) fluctuations, presumably through variation in sediment inundation. As a result, Hg contamination of fish has been linked to international regulations of WL fluctuation. Here we assess the relationship between WL fluctuations and fish Hg content using a 10-year dataset covering six lakes. Within-year WL rise did not appear in strongly supported models of fish Hg, but year-to-year variation in maximum water levels (?maxWL) was positively associated with fish Hg content. This WL effect varied in magnitude among lakes: In Crane Lake, a 1 m increase in ?maxWL from the previous year was associated with a 108 ng increase in fish Hg content (per gram wet weight), while the same WL change in Kabetogama was associated with only a 5 ng increase in fish Hg content. In half the lakes sampled here, effect sizes could not be distinguished from zero. Given the persistent and wide-ranging extent of Hg contamination and the large number of regulated waterways, future research is needed to identify the conditions in which WL fluctuations influence fish Hg content. PMID:25134675

Larson, James H; Maki, Ryan P; Knights, Brent C; Gray, Brian R

2014-10-01

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Deep bore well water level fluctuations in the Koyna region, India: the presence of a low order dynamical system in a seismically active environment  

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Full Text Available Water level fluctuations in deep bore wells in the vicinity of seismically active Koyna region in western India provides an opportunity to understand the causative mechanism underlying reservoir-triggered earthquakes. As the crustal porous rocks behave nonlinearly, their characteristics can be obtained by analysing water level fluctuations, which reflect an integrated response of the medium. A Fractal dimension is one such measure of nonlinear characteristics of porous rock as observed in water level data from the Koyna region. It is inferred in our study that a low nonlinear dynamical system with three variables can predict the water level fluctuations in bore wells.

D. V. Ramana

2009-05-01

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The best farm-level irrigation strategy changes seasonally with fluctuating water availability  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Around the globe farmers managing irrigated crops face a future with a decreased and more variable water supply. To investigate generic adaptation issues, a range of on-farm strategies were evaluated for apportioning limited water between fields and enterprises using a typical case-study farm from Australia's Riverina region. These strategies are compared for a range of seasonal water availability levels. The analysis did not address investment in new irrigation technologies or new crops, but...

Gaydon, D. S.; Meinke, H.; Rodriguez, D.

2012-01-01

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Water Level Fluctuations in the Congo Basin Derived from ENVISAT Satellite Altimetry  

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Full Text Available In the Congo Basin, the elevated vulnerability of food security and the water supply implies that sustainable development strategies must incorporate the effects of climate change on hydrological regimes. However, the lack of observational hydro-climatic data over the past decades strongly limits the number of studies investigating the effects of climate change in the Congo Basin. We present the largest altimetry-based dataset of water levels ever constituted over the entire Congo Basin. This dataset of water levels illuminates the hydrological regimes of various tributaries of the Congo River. A total of 140 water level time series are extracted using ENVISAT altimetry over the period of 2003 to 2009. To improve the understanding of the physical phenomena dominating the region, we perform a K-means cluster analysis of the altimeter-derived river level height variations to identify groups of hydrologically similar catchments. This analysis reveals nine distinct hydrological regions. The proposed regionalization scheme is validated and therefore considered reliable for estimating monthly water level variations in the Congo Basin. This result confirms the potential of satellite altimetry in monitoring spatio-temporal water level variations as a promising and unprecedented means for improved representation of the hydrologic characteristics in large ungauged river basins.

Mélanie Becker

2014-09-01

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Wetland Ecohydrology: stochastic description of water level fluctuations across the soil surface  

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Wetlands provide a suite of social and ecological critical functions such as being habitats of disease-carrying vectors, providing buffer zones against hurricanes, controlling sediment transport, filtering nutrients and contaminants, and a repository of great biological diversity. More recently, wetlands have also been recognized as crucial for carbon storage in the context of global climate change. Despite such importance, quantitative approaches to many aspects of wetlands are far from adequate. Therefore, improving our quantitative understanding of wetlands is necessary to our ability to maintain, manage, and restore these invaluable environments. In wetlands, hydrologic factors and ecosystem processes interplay and generate unique characteristics and a delicate balance between biotic and abiotic elements. The main hydrologic driver of wetland ecosystems is the position of the water level that, being above or below ground, determines the submergence or exposure of soil. When the water level is above the soil surface, soil saturation and lack of oxygen causes hypoxia, anaerobic functioning of microorganisms and anoxic stress in plants, that might lead to the death of non-adapted organisms. When the water level lies below the soil surface, the ecosystem becomes groundwater-dependent, and pedological and physiological aspects play their role in the soil water balance. We propose here a quantitative description of wetland ecohydrology, through a stochastic process-based water balance, driven by a marked compound Poisson noise representing rainfall events. The model includes processes such as rainfall infiltration, evapotranspiration, capillary rise, and the contribution of external water bodies, which are quantified in a simple yet realistic way. The semi-analytical steady-state probability distributions of water level spanning across the soil surface are validated with data from the Everglades (Florida, USA). The model and its results allow for a quantitative analysis of the long term behavior of biotic and abiotic factors which depend on the position of the water level and enable the assessment of impacts of climate changes on the wetland ecosystem.

Tamea, S.; Muneepeerakul, R.; Laio, F.; Ridolfi, L.; Rodriguez-Iturbe, I.

2009-12-01

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Properties of Adsorption-Desorption of Pb in Soil of the Water-Level-Fluctuating in Three Gorges Reservoir Region  

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Full Text Available The soil of water-level-fluctuating adsorption and desorption characterisitics of Pb2+ ion in the Three Gorges Reservoir region are studied on pH, organic matter, ionic strength and effect of Pb2+ ion concentration. It is revealed in the law of soil adsorption and desorption of Pb2+ ion in water-level-fluctuationg of the Three Gorges reservoir region, for providing the basis on lead contamination risk assessment and forecasting, pollution control and the use of land resources. Electing purple soil of the main soil type is also studied by using simulation experiments and constant temperature oscillation balance method. With atomic absorption spectrophotometer determination of Pb2+ ion adsorption and desorption volume. The results show that:1pH value very significantyly affects the soil adsorption capacity of Pb2+ ion (ppH>organic matter > Pb2+ ion concentration, affect the Pb2+ soil desorption amount in the order of :pHwater in the Three Gorges Reservoir region, the soil of water-level-fluctuating is affected by various factors, leading to change the soil properties and affect the environmental behavior of heavy metals and way cause enviromental pollution and ecological hazards.

FANG Lu-qiu

2010-05-01

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Dramatic water-level fluctuations in lakes under intense human impact: modelling the effect of vegetation, climate and hydrogeology  

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Lakes form a highly important ecosystem in the glacial terrain of northern Europe and America, but their hydrology remains understudied. When the water-level of a lake drops significantly and rises again in a time span of half a century and the widespread explanation of the fluctuations seems insufficient, then it raises a question: how do different anthropogenic and natural processes actually affect the formation of a lakes' water body. The abovementioned scenario applies to three small closed-basin Estonian lakes (L. Ahnejärv, L. Kuradijärv and L. Martiska) analysed in the current study. These lakes suffered a major water-level drop (up to 3.8 m) between 1946 and 1987 and a major rise between 1987 and 2010, from 1 m (L. Ahnejärv) to 2.5 m (L. Kuradijärv). Decreasing and increasing groundwater abstraction near the lakes has been widely considered to be the only reason for the fluctuations. It is true that the most severe drop in the lake levels did occur after 1972 when groundwater abstraction for drinking water started in the vicinity of the lakes. However, the lake levels started to fall before the groundwater abstraction began and for the time being the lake levels have risen to a higher level than in the 1970s when the quantity of annually abstracted groundwater was similar to nowadays. Therefore the processes affecting the formation of the lakes' water body prove to be more complex than purely the hydrogeological change caused by groundwater abstraction. A new deterministic water balance model (where the evaporation from the lake surface was calculated by Penman equation and the catchment runoff by Thornthwaite-Mather soil-moisture model), compiled for the study, coupled with LiDAR-based GIS-modelling of the catchments was used to identify the different factors influencing the lakes' water level. The modelling results reveal that the moderate drop in lake water levels before the beginning of groundwater abstraction was probably caused by the growth of a coniferous forest on the lake catchments, due to which evapotranspiration and subsequently runoff from the catchment decreased. The forest had been destroyed by wildfires during World War II. The water-level rise that the lakes have gone through in the last 20 years has in the case of L. Ahnejärv been caused by changing meteorological conditions (precipitation, air temperature and wind speed). In the case of Lakes Kuradijärv and Martiska the change has been caused by both the raise of groundwater level (caused by the decreasing groundwater abstraction) and the change of meteorological conditions. Therefore the vegetation change on the catchment and changes in meteorological conditions have played as important or, at times, even more important role in the water-level fluctuations than changes in the hydrogeological conditions. Although concentrating on three specific lakes in a specific region, the result of the study indicate the complexity of factors influencing the amount of water stored in a lake at a certain moment. Therefore it manifests a need for improved models in order to improve lake management around the world.

Vainu, M.

2012-04-01

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Evaluation of Radionuclides, Toxic Metals and Fluctuation ofRadioactivity Level in Muria Water  

International Nuclear Information System (INIS)

Study on Radionuclides, toxic metals and radioactivity level fluctuationin Water samples of Muria area have been carried out. The sampling locationwere Sepalung Tubanan, Hulu Putih, Balong, Geulis and Banjaran river, LemahAbang, Krakal and Baron coasts. Alpha, betha, and gamma radioactivity levelswere gross counted. Radionuclides identification were done by using gammaspectrometer. Pu-239/240 were analyzed by dilution and solvent extractionstep before counted by alpha spectrometer. Toxic metals were analyzed byInstrumental Neutron Activation Method, with the neutron flux of5.1010.n.cm-2.s-1. Data collection of toxic elements was carried outduring 4 years since 1996 to 1999, and 2 years for radioactivity level studysince 1998 and 1999. High concentration of Zn in Balong and Hulu Putih riverwater samples in 1999 higher than the governmental quality standard value foragriculture. The radionuclides contaminant as Pu-239/240 and Cs-137 were notdetected, and the radioactivity level and identified radionuclides were allnaturally. (author)

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Water level fluctuations in the Congo Basin derived from ENVISAT satellite altimetry  

Science.gov (United States)

In the Congo Basin, the elevated vulnerability of the food security and water supply implicates that the sustainable development strategies must take into account the climate change impacts. However, there are only a limited number of studies focusing on climate change impacts for the Congo basin, mainly due to the lack of observational climate and hydrological data. Recent improvements in remote sensing technology provide more data than ever before to support hydrological studies in tropical regions. In this work, 130 time series of water level in major rivers of the Congo basin are extracted using ENVISAT altimetry over the period 2002-2010. This dataset offers an unprecedented distributed view of the spatio-temporal variations of river stage throughout the basin. In order to provide valuable indications to improve the understanding of the dominant physical phenomena in the Congo Basin, we performed a K-Means cluster analysis of the altimeter-derived river level height variations to identify groups of hydrologically similar catchments. Each group is represented through a parsimonious set of morphometric (location, elevation and distance to the mouth) and hydrologic variables (amplitude), including also indexes that attempt to synthesize the variability (dates of low and high stages) and correlation properties (lag-1, Hurst exponent). This analysis revealed nine distinct regions. For each region the seasonal and interannual variabilities of the mean river level are discussed and compared to the TRMM rainfall data and to ordinary climate indices such as MEI, TNA, TSA and IOD. This analysis allowed us to identify the most sensitive subregions to climate change of the Congo Basin.

Becker, M.; Santos Da Silva, J.; Conchi, T.; Calmant, S.; Seyler, F.

2013-12-01

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Community metabolism in a deep (stratified) tropical reservoir during a period of high water-level fluctuations.  

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As long as lakes and reservoirs are an important component of the global carbon cycle, monitoring of their metabolism is required, especially in the tropics. In particular, the response of deep reservoirs to water-level fluctuations (WLF) is an understudied field. Here, we study community metabolism through oxygen dynamics in a deep monomictic reservoir where high WLF (~10 m) have recently occurred. Simultaneous monitoring of environmental variables and zooplankton dynamics was used to assess the effects of WLF on the metabolism of the eutrophic Valle de Bravo (VB) reservoir, where cyanobacteria blooms are frequent. Mean gross primary production (P g) was high (2.2 g C m(-2) day(-1)), but temporal variation of P g was low except for a drastic reduction during circulation attributed to zooplankton grazing. The trophogenic layer showed net autotrophy on an annual basis, but turned to net heterotrophy during mixing, and furthermore when the whole water-column oxygen balance was calculated, considering the aphotic respiration (Raphotic). The high total respiration resulting (3.1 g C m(-2) day(-1)) is considered to be partly due to mixing enhanced by WLF. Net ecosystem production was equivalent to a net export of 3.4 mg CO??m(-2) day(-1) to the atmosphere. Low water levels are posed to intensify boundary-mixing events driven by the wind during the stratification in VB. Long-term monitoring showed changes in the planktonic community and a strong silicon decrease that matched with low water-level periods. The effects of low water-level on metabolism and planktonic community in VB suggest that water-level manipulation could be a useful management tool to promote phytoplankton groups other than cyanobacteria. PMID:24994617

Valdespino-Castillo, Patricia M; Merino-Ibarra, Martín; Jiménez-Contreras, Jorge; Castillo-Sandoval, Fermín S; Ramírez-Zierold, Jorge A

2014-10-01

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Separated by sand, fused by dropping water: habitat barriers and fluctuating water levels steer the evolution of rock-dwelling cichlid populations in Lake Tanganyika.  

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The conditions of phenotypic and genetic population differentiation allow inferences about the evolution, preservation and loss of biological diversity. In Lake Tanganyika, water level fluctuations are assumed to have had a major impact on the evolution of stenotopic littoral species, though this hypothesis has not been specifically examined so far. The present study investigates whether subtly differentiated colour patterns of adjacent Tropheus moorii populations are maintained in isolation or in the face of continuous gene flow, and whether the presumed influence of water level fluctuations on lacustrine cichlids can be demonstrated in the small-scale population structure of the strictly stenotopic, littoral Tropheus. Distinct population differentiation was found even across short geographic distances and minor habitat barriers. Population splitting chronology and demographic histories comply with our expectation of old and rather stable populations on steeper sloping shore, and more recently established populations in a shallower region. Moreover, population expansions seem to coincide with lake level rises in the wake of Late Pleistocene megadroughts ~100 KYA. The imprint of hydrologic events on current population structure in the absence of ongoing gene flow suggests that phenotypic differentiation among proximate Tropheus populations evolves and persists in genetic isolation. Sporadic gene flow is effected by lake level fluctuations following climate changes and controlled by the persistence of habitat barriers during lake level changes. Since similar demographic patterns were previously reported for Lake Malawi cichlids, our data furthermore strengthen the hypothesis that major climatic events synchronized facets of cichlid evolution across the East African Great Lakes. PMID:21518059

Koblmüller, Stephan; Salzburger, Walter; Obermüller, Beate; Eigner, Eva; Sturmbauer, Christian; Sefc, Kristina M

2011-06-01

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Response of Eichhornia crassipes (Pontederiaceae to water level fluctuations in two lakes with different connectivity in the Paraná River floodplain  

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Full Text Available Floodplain lakes are especially dynamic due to the irregular flow regime of the Paraná River and its location along the geomorphologic gradient between the lakes and the river. The response of Eichhornia crassipes (Mart. Solms (one of the most frequent aquatic plant was studied in two floodplain lakes with different flooding regimes. Samples were taken between March 1997 and December 2001 on 13 different hydrologic conditions during prolonged hydrologic connection and prolonged hydrologic isolation. Leaf height, leaf density, biomass and nutrient content of the mature leaves of E. crassipes were measured and related to water level fluctuation and the hydrologic connectivity. The lake more connected with the main channel had a long lasting inundation phase. In this condition the surface area covered by water increased more than three times compared to prolonged hydrologic isolation condition. As river water entered the floodplain lakes, dissolved inorganic nitrogen increased to high values, especially NO3-, whereas the isolation condition was characterised by a decrease in NO3- concentrations to undetectable levels. Compared to plants growing in the more isolated lake, those growing in the more connected lake had a significantly lower leaf density, longer leaves, less root biomass and lower ratio between below-ground and above-ground biomasses. However, total and leaf biomasses were not significantly different between sites. In each lake, differences in leaf height, leaf biomass and root biomass between prolonged hydrologic connection and isolation, as well as the insignificant relationship between leaf size and leaf density, indicate that the morphological traits of E. crassipes respond to pluri-annual water level fluctuations. The highest nutrient concentration in mature leaves was registered at the end of the prolonged hydrologic connection in the more connected lake. During the prolonged isolation, leaves had more lignin and a higher L:N ratio than at high waters, at the same sites. The success of E. crassipes in occupying habitats subjected to wide and erratic fluctuations in water level, such as the Paraná River floodplain, appears to be related to its ability to modify morphological traits according to water level. Rev. Biol. Trop. 56 (2: 613-623. Epub 2008 June 30.Se analiza la respuesta de Eichhornia crassipes, una de las plantas acuáticas más frecuentes en la planicie de inundación del río Paraná, a las fluctuaciones del río en dos lagos con diferente conectividad. Las muestras fueron tomadas en 13 condiciones hidrológicas entre Marzo de 1997 y Diciembre de 2001. Durante el periodo de prolongada conectividad hidrológica, el área cubierta por el agua aumenta más de tres veces y el contenido de nitrógeno inorgánico disuelto fue mayor en comparación con la condición de prolongado aislamiento. En comparación con las plantas del lago más aislado del río, las del más conectado tuvieron significativamente menor densidad de hojas, hojas más largas, menor biomasa de raíces y menor cociente entre la biomasa de las partes aéreas y las partes sumergidas. Las diferencias en la altura y la biomasa de hojas y raíces entre diferentes condiciones hidrológicas y la no significativa relación entre el tamaño y su densidad, indican que las características morfológicas de las plantas responden a fluctuaciones del nivel del agua. Durante la prolongada conexión con el río el contenido de nutrientes de las hojas maduras fue alto, en tanto que durante el aislamiento prolongado las hojas tuvieron mayor contenido de lignina y alto cociente L:N. El éxito de Eichhornia crassipes en la ocupación de hábitats sujetos a amplias y erráticas fluctuaciones del nivel del agua parece estar relacionado con su capacidad para modificar sus características morfológicas en función de las fluctuaciones del nivel del agua.

Juan José Neiff

2008-06-01

 
 
 
 
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Cold-water Coral Mound Development Controlled by Sea Level Fluctuation on the Lower Slope of Great Bahama Bank  

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Cold-water coral mounds are constructed by a combined mechanism of coral growth and trapping of sediments. The interaction between these factors is complex; changes in the ratio of coral growth to sedimentation rates can result in mound burial or erosion. Thus, in addition to biological and hydrodynamic factors, sediment input is critical to mound formation, growth and senescence. We therefore conducted interdisciplinary Autonomous Underwater Vehicle (AUV) and submersible surveys on three coral mound fields on the slope of Great Bahama Bank. Our multibeam maps revealed a high abundance of coral mounds with diverse morphologies. Meanwhile, sub- bottom profiles showed differences on echo-characters; a high-amplitude reflection underlying the mounds is interpreted to have formed during sea level fall, while thick sediment deposits onlapping the strong reflection suggest more recent deposition. The sub-surface data indicate that cold-water coral mound development is controlled by sea level fluctuation. The mechanism proposed is the following: during lowstand period, the platform was exposed resulting in minimal sedimentation rates on slope areas of GBB. Furthermore, faster flow through a more restricted and narrow Straits, contributing to early cementation and exposure of hard substrates. These conditions facilitated colonization of the lower slope areas of GBB by cold-water corals during the last glacial maximum. When sea level began to rise again, flooding occurred on the bank and offbank sediments were transported to slope areas of GBB, contributing to mound growth or burial. Although the submersible samples do not reach the high-amplitude reflection, the sediment samples can be used to test whether or not platform-derived sediments of the GBB contribute to mound development. We are currently analyzing the modal composition and mineralogy of the sediments entrapped in the mounds to verify the provenance of grains and calculating the coral growth rates, so we can affirm that cold-water coral mounds are built up during sea level highstand.

Correa, T. B.; Eberli, G. P.; Grasmueck, M.; Reed, J.

2008-05-01

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Assessing spatial fluctuations, temporal variability, and measurement error in estimated levels of disinfection by-products in tap water: implications for exposure assessment  

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Aims: To assess spatial fluctuations, temporal variability, and errors due to sampling and analysis in levels of disinfection by-products in routine monitoring tap water samples and in water samples collected in households within the same distribution system for an exposure assessment study.

Symanski, E.; Savitz, D.; Singer, P.

2004-01-01

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Recovery approach affects soil quality in the water level fluctuation zone of the Three Gorges Reservoir, China: implications for revegetation.  

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Plants in the water level fluctuation zone of the Three Gorges Reservoir Region disappeared due to winter-flooding and prolonged inundation. Revegetation (plantation and natural recovery) have been promoted to restore and protect the riparian ecosystem in recent years. Revegetation may affect soil qualities and have broad important implications both for ecological services and soil recovery. In this study, we investigated soil properties including soil pH values, bulk density, soil organic matter (SOM), soil nutrients and heavy metals, soil microbial community structure, microbial biomass, and soil quality index under plantation and natural recovery in the Three Gorges Reservoir Region. Most soil properties showed significant temporal and spatial variations in both the plantation and natural recovery areas. Higher contents of SOM and NO3-N were found in plantation area, while higher contents of soil pH values, bulk density, and total potassium were observed in the natural recovery area. However, there were no significant differences in plant richness and diversity and soil microbial community structure between the two restoration approaches. A soil quality index derived from SOM, bulk density, Zn, Cd, and Hg indicated that natural recovery areas with larger herbaceous coverage had more effective capacity for soil restoration. PMID:24019143

Ye, Chen; Cheng, Xiaoli; Zhang, Quanfa

2014-02-01

24

Environmental assessment for the natural fluctuation of water level in Par Pond and reduced water flow in Steel Creek below L-Lake at the Savannah River Site  

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The Savannah River Operations Office Strategic Plan directs Savannah River Site (SRS) to find ways to reduce operating costs, and to determine what site infrastructure must be maintained and what infrastructure is surplus. Because of the mission change, L-Lake, Par Pond, and the river water system are no longer needed to support current missions and therefore provide an opportunity for operating cost reduction. If SRS determines that L-Lake, Par Pond, and the river water system are no longer needed to support future missions and are considered surplus, appropriate NEPA documentation will be prepared. The purpose of the proposed action in this Environmental Assessment is to begin an examination of the need for the Site`s river water system by (1) developing data needed to evaluate the potential environmental impacts of further reducing or eliminating the flow demands from the Site`s river water system and; (2) evaluating the potential of reducing operating costs by allowing the water level in Par Pond to fluctuate naturally through reduced pumping. This action also includes reducing the current flow rates from L-Lake to Steel Creek to natural stream flows while maintaining full pool. The recently approved Par Pond CERCLA Interim Action Proposed Plan (IAPP) committed to evaluate in a NEPA document the environmental consequences of this proposed action. This document evaluated the remediation of human health and ecological risks associated with the three year drawdown of Par Pond. Should any of the parameters sampled in the reservoir and streams (e.g., water quality, biota, etc.) exceed established threshold levels during the implementation of the proposed action, water would again be pumped into the reservoir to minimize any impacts by bringing the water level back to an appropriate level about 58.2 m (195 ft).

NONE

1995-08-01

25

Habitat selection by African buffalo (Syncerus caffer) in response to landscape-level fluctuations in water availability on two temporal scales.  

Science.gov (United States)

Seasonal fluctuations in water availability cause predictable changes in the profitability of habitats in tropical ecosystems, and animals evolve adaptive behavioural and spatial responses to these fluctuations. However, stochastic changes in the distribution and abundance of surface water between years can alter resource availability at a landscape scale, causing shifts in animal behaviour. In the Okavango Delta, Botswana, a flood-pulsed ecosystem, the volume of water entering the system doubled between 2008 and 2009, creating a sudden change in the landscape. We used African buffalo (Syncerus caffer) to test the hypotheses that seasonal habitat selection would be related to water availability, that increased floodwater levels would decrease forage abundance and affect habitat selection, and that this would decrease buffalo resting time, reduce reproductive success and decrease body condition. Buffalo selected contrasting seasonal habitats, using habitats far from permanent water during the rainy season and seasonally-flooded habitats close to permanent water during the early and late flood seasons. The 2009 water increase reduced forage availability in seasonally-flooded habitats, removing a resource buffer used by the buffalo during the late flood season, when resources were most limited. In response, buffalo used drier habitats in 2009, although there was no significant change in the time spent moving or resting, or daily distance moved. While their reproductive success decreased in 2009, body condition increased. A protracted period of high water levels could prove detrimental to herbivores, especially to smaller-bodied species that require high quality forage. Stochastic annual fluctuations in water levels, predicted to increase as a result of anthropogenically-induced climate change, are likely to have substantial impacts on the functioning of water-driven tropical ecosystems, affecting environmental conditions within protected areas. Buffer zones around critical seasonal resources are essential to allow animals to engage in compensatory behavioural and spatial mechanisms in response to changing environmental conditions. PMID:24983377

Bennitt, Emily; Bonyongo, Mpaphi Casper; Harris, Stephen

2014-01-01

26

Habitat Selection by African Buffalo (Syncerus caffer) in Response to Landscape-Level Fluctuations in Water Availability on Two Temporal Scales  

Science.gov (United States)

Seasonal fluctuations in water availability cause predictable changes in the profitability of habitats in tropical ecosystems, and animals evolve adaptive behavioural and spatial responses to these fluctuations. However, stochastic changes in the distribution and abundance of surface water between years can alter resource availability at a landscape scale, causing shifts in animal behaviour. In the Okavango Delta, Botswana, a flood-pulsed ecosystem, the volume of water entering the system doubled between 2008 and 2009, creating a sudden change in the landscape. We used African buffalo (Syncerus caffer) to test the hypotheses that seasonal habitat selection would be related to water availability, that increased floodwater levels would decrease forage abundance and affect habitat selection, and that this would decrease buffalo resting time, reduce reproductive success and decrease body condition. Buffalo selected contrasting seasonal habitats, using habitats far from permanent water during the rainy season and seasonally-flooded habitats close to permanent water during the early and late flood seasons. The 2009 water increase reduced forage availability in seasonally-flooded habitats, removing a resource buffer used by the buffalo during the late flood season, when resources were most limited. In response, buffalo used drier habitats in 2009, although there was no significant change in the time spent moving or resting, or daily distance moved. While their reproductive success decreased in 2009, body condition increased. A protracted period of high water levels could prove detrimental to herbivores, especially to smaller-bodied species that require high quality forage. Stochastic annual fluctuations in water levels, predicted to increase as a result of anthropogenically-induced climate change, are likely to have substantial impacts on the functioning of water-driven tropical ecosystems, affecting environmental conditions within protected areas. Buffer zones around critical seasonal resources are essential to allow animals to engage in compensatory behavioural and spatial mechanisms in response to changing environmental conditions. PMID:24983377

Bennitt, Emily; Bonyongo, Mpaphi Casper; Harris, Stephen

2014-01-01

27

[Transfer characteristic and source identification of soil heavy metals from water-level-fluctuating zone along Xiangxi River, three-Gorges Reservoir area].  

Science.gov (United States)

Transfer characteristics of heavy metals and their evaluation of potential risk were studied based on determining concentration of heavy metal in soils from water-level-fluctuating zone (altitude:145-175 m) and bank (altitude: 175-185 m) along Xiangxi River, Three Gorges Reservoir area. Factor analysis-multiple linear regression (FA-MLR) was employed for heavy metal source identification and source apportionment. Results demonstrate that, during exposing season, the concentration of soil heavy metals in water-level-fluctuation zone and bank showed the variation, and the concentration of soil heavy metals reduced in shallow soil, but increased in deep soil at water-level-fluctuation zone. However, the concentration of soil heavy metals reduced in both shallow and deep soil at bank during the same period. According to the geoaccumulation index,the pollution extent of heavy metals followed the order: Cd > Pb > Cu > Cr, Cd is the primary pollutant. FA and FA-MLR reveal that in soils from water-level-fluctuation zone, 75.60% of Pb originates from traffic, 62.03% of Cd is from agriculture, 64.71% of Cu and 75.36% of Cr are from natural rock. In soils from bank, 82.26% of Pb originates from traffic, 68.63% of Cd is from agriculture, 65.72% of Cu and 69.33% of Cr are from natural rock. In conclusion, FA-MLR can successfully identify source of heavy metal and compute source apportionment of heavy metals, meanwhile the transfer characteristic is revealed. All these information can be a reference for heavy metal pollution control. PMID:24946610

Xu, Tao; Wang, Fei; Guo, Qiang; Nie, Xiao-Qian; Huang, Ying-Ping; Chen, Jun

2014-04-01

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The effect of water-level fluctuations on swamp forest colonization by seedlings of Tabebuia cassinoides DC. (Bignoniaceae  

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Full Text Available Establishment of Tabebuia cassinoides seedlings is related to water-level fluctuations in southeastern Brazil swamp forests. Nine years of annual monitoring of 48 individuals established during a drought in November 1997, when the swamp was unflooded, suggested that their establishment depends on this unpredictable event. This conclusion is further sustained by the wide variability of the seedling cohort size structure, and the fascicular root conformation that holds the shoots erect.

Mariana de Andrade Iguatemy

2011-11-01

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Pattern and Biodiversity of Plant Community in Water-Level-Fluctuation Zone of Pengxi River After 156 m Impoundment of Three Gorges Reservoir  

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Full Text Available After impounding to altitude of 156 m, species, spatial pattern and biodiversity of plant community in water-level-fluctuation zone of Three Gorges Reservoir had significant changes. The plant community under altitude of 175 m beside Pengxi River and its tributary Baijia Stream in Kaixian County was studied from July to September, 2008. 108 herb sampling quadrates along five sampling transects, three beside Pengxi River and two beside Baijia Stream, were conducted. The results showed that there are 98 species of vascular plant belong to 38 families, 29 generas. 52 species of wetland plant were investigated. Therophytes(52.0% and cryptophyte (31.6% were the dominant compositions of Raunkiaer’s life. The plant community of study area belonged to 11 associations. Floodplain annual herb zone, Xanthium sibiricum zone, Paspalum paspaloides zone and Imperata cylindrica zone dispersed at the lateral side of Pengxi River and Baijia stream from riparian to altitude of 175 m. The variation and pattern of soil water content significantly influenced the distribution of plant community in water-level-fluctuation zone. There were a low herb biodiversity in water-lever fluctuation zone.

WANG Jian-xiu

2009-10-01

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Lake Level Fluctuations Boost Toxic Cyanobacterial "Oligotrophic Blooms"  

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Global warming has been shown to strongly influence inland water systems, producing noticeable increases in water temperatures. Rising temperatures, especially when combined with widespread nutrient pollution, directly favour the growth of toxic cyanobacteria. Climate changes have also altered natural water level fluctuations increasing the probability of extreme events as dry periods followed by heavy rains. The massive appearance of Dolichospermum lemmermannii (?=?planktonic Anabaena), a toxic species absent from the pelagic zone of the subalpine oligotrophic Lake Maggiore before 2005, could be a consequence of the unusual fluctuations of lake level in recent years. We hypothesized that these fluctuations may favour the cyanobacterium as result of nutrient pulses from the biofilms formed in the littoral zone when the lake level is high. To help verify this, we exposed artificial substrates in the lake, and evaluated their nutrient enrichment and release after desiccation, together with measurements of fluctuations in lake level, precipitation and D.lemmermannii population. The highest percentage of P release and the lowest C?P molar ratio of released nutrients coincided with the summer appearance of the D.lemmermannii bloom. The P pulse indicates that fluctuations in level counteract nutrient limitation in this lake and it is suggested that this may apply more widely to other oligotrophic lakes. In view of the predicted increase in water level fluctuations due to climate change, it is important to try to minimize such fluctuations in order to mitigate the occurrence of cyanobacterial blooms. PMID:25295866

Callieri, Cristiana; Bertoni, Roberto; Contesini, Mario; Bertoni, Filippo

2014-01-01

31

Sliding stones of Racetrack Playa, Death Valley, USA: The roles of rock thermal conductivity and fluctuating water levels  

Science.gov (United States)

On occasion, Racetrack playa in Death Valley National Park becomes flooded and temperatures then drop appreciably below freezing. The thermal conductivity of rock is greater than that of water, so heat is conducted from a partially-submerged rock faster than from water. Consequently, a collar of thicker ice forms at the water surface, a layer of ice forms on more deeply-submerged parts of the rock, and playa sediment beneath the rock may even become frozen to it. While this occurs, only a surface layer of ice forms on water away from the rock. Once the ice becomes thick enough, perhaps only 5-10 mm, either the buoyancy of the ice or additions of water to the playa by rain, snow-melt, or groundwater seepage then reduce the normal force between the rock and the playa to the point where wind shear can move the ice sheet with its entrained rocks, making trails (Stanley, 1955; Reid et al., 1995). After the ice melts, rocks are left at the ends of the trails, sometimes atop a pedestal of silt. A renewed increase in water level on the playa before the ice melts may lift a rock completely free of the playa surface and whisk it away, leaving a rockless trail. During a movement event, changes in rock orientation or water depth may result in changes in width along the track. Rock speeds are likely tens to hundreds of millimeters per second.

Kletetschka, Gunther; Hooke, Roger LeB.; Ryan, Andrew; Fercana, George; McKinney, Emerald; Schwebler, Kristopher P.

2013-08-01

32

Influence of water level fluctuation on the mortality and aboveground biomass of the aquatic macrophyte Eleocharis interstincta (VAHL) roemer et schults  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O objetivo deste trabalho foi verificar as alterações biométricas de Eleocharis interstincta em resposta às variações no nível da água da Lagoa de Cabiúnas, localizada na região norte do Estado do Rio de Janeiro, no município de Macaé (22º00' e 22º30' S, 41º30' e 42º00' O). Três quadrados de 0,0625 [...] m² foram coletados quinzenalmente de junho/1997 a junho/1998; as amostras separadas em caules, detritos e rizoma; medidas, secas e pesadas. O nível da água variou sazonalmente no estande das macrófitas, apresentando dois períodos de seca. O primeiro período ocorreu naturalmente, no final do inverno e início da primavera, quando a precipitação na região é menor. O segundo período de seca foi resultado da abertura artificial da barra de areia, que separa a lagoa do mar. A abertura da barra foi feita no verão, período de maior precipitação, quando o nível da água registrou o máximo valor durante o período de estudo (1,35 m). Foi encontrada uma forte correlação positiva entre o nível da água com o tamanho médio dos caules e a biomassa aérea, indicando que o nível da água desempenha um importante papel na determinação destes parâmetros. Houve uma diferença significativa no tamanho (ANOVA; p Abstract in english The goal of this study was to study the biometric alterations of Eleocharis interstincta in response to water level fluctuations in Cabiúnas Lagoon, located on the northern coast of the state of Rio de Janeiro, in the municipality of Macaé. Three quadrats of 0.0625 m² were harvested every two weeks [...] from June/1997 to June/1998; samples were separated into stems, dead stems (detritus) and rhizome; lenghted, dried and weighted. The water level fluctuated seasonally in the macrophyte stand with two periods of drawdown. The first period occurred naturally at the end of winter and beginning of spring, when rainfall in the area was normally lowest. The second period of drawdown was the result of an artificial breaching of the sandbar that isolate the lagoon from the sea. The breach was made in the summer, at the time of highest rainfall, when the water level in the lagoon reached the maximum value recorded during the study (1.35 m). There was a strongly positive correlation of the water level with stems mean height and aboveground biomass, indicating that water level played an important role in the determination of these parameters. There was a significant difference between stem height (ANOVA; p

Anderson Medeiros dos, Santos; Francisco de Assis, Esteves.

33

Influence of water level fluctuation on the mortality and aboveground biomass of the aquatic macrophyte Eleocharis interstincta (VAHL) roemer et schults  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O objetivo deste trabalho foi verificar as alterações biométricas de Eleocharis interstincta em resposta às variações no nível da água da Lagoa de Cabiúnas, localizada na região norte do Estado do Rio de Janeiro, no município de Macaé (22º00' e 22º30' S, 41º30' e 42º00' O). Três quadrados de 0,0625 [...] m² foram coletados quinzenalmente de junho/1997 a junho/1998; as amostras separadas em caules, detritos e rizoma; medidas, secas e pesadas. O nível da água variou sazonalmente no estande das macrófitas, apresentando dois períodos de seca. O primeiro período ocorreu naturalmente, no final do inverno e início da primavera, quando a precipitação na região é menor. O segundo período de seca foi resultado da abertura artificial da barra de areia, que separa a lagoa do mar. A abertura da barra foi feita no verão, período de maior precipitação, quando o nível da água registrou o máximo valor durante o período de estudo (1,35 m). Foi encontrada uma forte correlação positiva entre o nível da água com o tamanho médio dos caules e a biomassa aérea, indicando que o nível da água desempenha um importante papel na determinação destes parâmetros. Houve uma diferença significativa no tamanho (ANOVA; p Abstract in english The goal of this study was to study the biometric alterations of Eleocharis interstincta in response to water level fluctuations in Cabiúnas Lagoon, located on the northern coast of the state of Rio de Janeiro, in the municipality of Macaé. Three quadrats of 0.0625 m² were harvested every two weeks [...] from June/1997 to June/1998; samples were separated into stems, dead stems (detritus) and rhizome; lenghted, dried and weighted. The water level fluctuated seasonally in the macrophyte stand with two periods of drawdown. The first period occurred naturally at the end of winter and beginning of spring, when rainfall in the area was normally lowest. The second period of drawdown was the result of an artificial breaching of the sandbar that isolate the lagoon from the sea. The breach was made in the summer, at the time of highest rainfall, when the water level in the lagoon reached the maximum value recorded during the study (1.35 m). There was a strongly positive correlation of the water level with stems mean height and aboveground biomass, indicating that water level played an important role in the determination of these parameters. There was a significant difference between stem height (ANOVA; p

Anderson Medeiros dos, Santos; Francisco de Assis, Esteves.

2004-06-01

34

[Sediment risk assessment and heavy metal source analysis in typical country water level fluctuated zone (WLFZ) of the Three Gorges].  

Science.gov (United States)

Typical country WLFZ in Zhongxian located in the core region of the Three Gorges Reservoir was chosen as research subject in this study. In July 2012, sediment samples of WLFZ were collected after dam water level dropped. Heavy metals were analyzed for sediment potential risk assessment and then applied for sources analysis in this area, which supplied basic data for non-point pollutants control. The results showed that As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn ranged in 155-160 m:5.17-14.81, 0.06-0.57, 8.55-20.56, 62.79-93.04, 15.38-60.97, 425.72-782.32, 21.34-48.5, 23.03-43.39 and 57.78-130.10 mg x kg(-1), and 170-175 m: 7.05-12.57, 0.17-0.33, 10.71-18.89, 65.22-92.89, 18.89-42.91, 74.06-774.41, 22.47-42.49, 24.17-29.23, 55.67-103.18 mg x kg(-1), respectively. Index of geo-accumulation (Igeo) suggested the accumulation orders were Cd > Co > Mn > As > Cu > Pb > Zn in 155-160m WLFZ and Co > Mn > Cd > As in 170-175 m WLFZ. Sediment pollution index (SPI) showed that sediments in 155-160 m WLFZ had higher potential risk than that of 170-175 m with the highest risk appeared in 155-166 m WLFZ site located downstream of Zhongxian. In 155-160 m WLFZ, Cr, Cu, Pb and Zn were mainly originated from natural resources, while As, Ni, Cd, Co and Mn were possibly sourced from upland water. In contrast, in 170-175 m WLFZ, Cr, Ni, Pb and Zn in the sediment came from natural resources, while Cd, As, Co, Mn and Cu were probably rooted from both agricultural non-point source and upland water. PMID:24720202

Ao, Liang; Lei, Bo; Wang, Ye-Chun; Zhou, Xie; Zhang, Sheng

2014-01-01

35

Spatial and seasonal CH4 flux in the littoral zone of Miyun Reservoir near Beijing: the effects of water level and its fluctuation.  

Science.gov (United States)

Wetlands, and especially their littoral zones, are considered to be CH4 emissions hotspots. The recent creation of reservoirs has caused a rapid increase in the area of the world's littoral zones. To investigate the effects of water depth and water level fluctuation on CH4 fluxes, and how these are coupled with vegetation and nutrients, we used static closed chamber and gas chromatography techniques to measure CH4 fluxes in the littoral zone of a large reservoir near Beijing, China, from November 2011 to October 2012. We found that CH4 flux decreased significantly along a transect from open water to dry land, from 3.1 mg m(-2) h(-1) at the deep water site to approximately 1.3 mg m(-2) h(-1) at the shallow water site, and less than 0.01 mg m(-2) h(-1) in the non-flooded area. Water level influenced CH4 flux by affecting soil properties including soil redox potential, soil carbon and nitrogen, and bulk density. The largest emission of all was from the seasonally flooded site after a flooding event (up to 21.1 mg m(-2) h(-1)), which may have been caused by vegetation decomposition. Submerged sites had greater emissions, while the driest site had lower emissions. Immediately after the monthly measurements had been made, we removed the aboveground vegetation to enable an assessment of the gas transportation per unit of biomass. Removal of biomass decreased emissions by up to 53%. These results indicated the dominant effect of water depth on CH4 flux through effects of soil conditions, plant species composition and distribution. This study suggests that temporally flooded wetlands, including littoral zones, contribute significantly to the global CH4 burden. However, the current challenge is to capture their spatial extent and temporal variation in the fluxes. PMID:24710279

Yang, Meng; Geng, Xuemeng; Grace, John; Lu, Cai; Zhu, Yi; Zhou, Yan; Lei, Guangchun

2014-01-01

36

Global Warming and Caspian Sea Level Fluctuations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Coastal regions have a high social, economical and environmental importance. Due to this importance the sea level fluctuations can have many bad consequences. In this research the correlation between the increasing trend of temperature in coastal stations due to Global Warming and the Caspian Sea level has been established. The Caspian Sea level data has been received from the Jason-1 satellite. It was resulted that the monthly correlation between the temperature and sea lev...

Ardakanian, Reza; Alemohammad, Seyed Hamed

2013-01-01

37

Global Warming and Caspian Sea Level Fluctuations  

CERN Document Server

Coastal regions have a high social, economical and environmental importance. Due to this importance the sea level fluctuations can have many bad consequences. In this research the correlation between the increasing trend of temperature in coastal stations due to Global Warming and the Caspian Sea level has been established. The Caspian Sea level data has been received from the Jason-1 satellite. It was resulted that the monthly correlation between the temperature and sea level is high and also positive and almost the same for all the stations. But the yearly correlation was negative. It means that the sea level has decreased by the increase in temperature.

Ardakanian, Reza

2013-01-01

38

Influence of water level fluctuation on the mortality and aboveground biomass of the aquatic macrophyte Eleocharis interstincta (VAHL roemer et schults  

Directory of Open Access Journals (Sweden)

Full Text Available The goal of this study was to study the biometric alterations of Eleocharis interstincta in response to water level fluctuations in Cabiúnas Lagoon, located on the northern coast of the state of Rio de Janeiro, in the municipality of Macaé. Three quadrats of 0.0625 m² were harvested every two weeks from June/1997 to June/1998; samples were separated into stems, dead stems (detritus and rhizome; lenghted, dried and weighted. The water level fluctuated seasonally in the macrophyte stand with two periods of drawdown. The first period occurred naturally at the end of winter and beginning of spring, when rainfall in the area was normally lowest. The second period of drawdown was the result of an artificial breaching of the sandbar that isolate the lagoon from the sea. The breach was made in the summer, at the time of highest rainfall, when the water level in the lagoon reached the maximum value recorded during the study (1.35 m. There was a strongly positive correlation of the water level with stems mean height and aboveground biomass, indicating that water level played an important role in the determination of these parameters. There was a significant difference between stem height (ANOVA; p O objetivo deste trabalho foi verificar as alterações biométricas de Eleocharis interstincta em resposta às variações no nível da água da Lagoa de Cabiúnas, localizada na região norte do Estado do Rio de Janeiro, no município de Macaé (22º00' e 22º30' S, 41º30' e 42º00' O. Três quadrados de 0,0625 m² foram coletados quinzenalmente de junho/1997 a junho/1998; as amostras separadas em caules, detritos e rizoma; medidas, secas e pesadas. O nível da água variou sazonalmente no estande das macrófitas, apresentando dois períodos de seca. O primeiro período ocorreu naturalmente, no final do inverno e início da primavera, quando a precipitação na região é menor. O segundo período de seca foi resultado da abertura artificial da barra de areia, que separa a lagoa do mar. A abertura da barra foi feita no verão, período de maior precipitação, quando o nível da água registrou o máximo valor durante o período de estudo (1,35 m. Foi encontrada uma forte correlação positiva entre o nível da água com o tamanho médio dos caules e a biomassa aérea, indicando que o nível da água desempenha um importante papel na determinação destes parâmetros. Houve uma diferença significativa no tamanho (ANOVA; p < 0.001 e biomassa aérea dos caules (ANOVA; p < 0.001 entre os períodos amostrais, variando de 143,9 cm e 338,8 g peso seco.m-2, antes da abertura, a 16,3 cm e 20.2 g peso seco.m-2 respectivamente depois da abertura da barra. A drástica variação no nível da água, ocasionando a mortalidade em massa dos caules, juntamente com a menor razão biomassa /caule (0.057 g de peso seco.individuo-1, registrados depois da abertura de barra, não representou um grande distúrbio para E. interstincta, visto que o tempo de resiliência para esta população foi estimado em 30 dias.

Anderson Medeiros dos Santos

2004-06-01

39

Coupling of HEC-HMS and HEC-ResSim in Modeling the Fluctuation of Water Level in Devils Lake Using Heterogeneous Data  

Science.gov (United States)

Devils Lake, located in Ramsey and Benson County in North Dakota is a sub-basin of the Red River of the North. Although it lies entirely within the Red River Basin, it has no natural outlet at current water levels. Since its inception during the glacier period, Devils Lake has been either rising or falling over the last 10,000 years. Geologic evidence shows that the water level in Devils Lake has fluctuated widely from completely dry (about 1400 feet AMSL) to overflowing into the Sheyenne River (about 1459 feet AMSL). The uncontrolled growth of the lake has been an alarming issue for North Dakota for the past few years as it causes continuous flooding in the surrounding areas. A hydro-climatic model that can provide simulations of the water level of this lake for a 20 or 50 year time frame can be a useful decision making tool. In a mission to achieve that, heterogeneous data obtained from various sources were used to model the lake. Runoff from precipitation is one of the major inputs to the lake and to model that, eight major watersheds that feed directly to the lake were identified using Digital Elevation Models (DEMs) of thirty meter resolution in ArcGIS environment. Hydrology and Arc Hydro tools were used to delineate the watersheds and sub-basins to generate the runoff using the HEC HMS model. The precipitation time series data collected from both NASA and ground stations were used separately to calibrate the runoff model. The generation of time series runoff values for individual basins for four consecutive years (2001-2004) was applied into HEC-ResSim, a reservoir simulation model, to estimate the lake level series considering the elevation-area-storage relationship and evaporation series from previous USGS studies. It is eminent that seepage under the lake played a key role in calibrating the model with observed elevations. The value of seepage flow was varied over increasing elevations as it depends on the height of water column. The model showed an acceptable match for the later two years (2003, 2004). With the preliminary success in calibrating the hydro-climate model, we are getting closer in achieving the goal of the study to provide simulations of the lake level in 20 and 50 year period using the downscaled Global Climate Model (GCM) and generated time series values of precipitation and temperature.

Munna, H. S.; Lim, Y. H.

2010-12-01

40

Modeling the impact of in-stream water level fluctuations on stream-aquifer interactions at the regional scale  

Science.gov (United States)

SummaryThe main objective of this study is to provide a realistic simulation of river stage in regional river networks in order to improve stream-aquifer interactions and better assess stream discharge and hydraulic head in aquifer units. The study focuses on the Oise basin (a 17,000 km 2 sub-basin of the Seine River basin, in Northern France). An upscaling method is proposed to benefit from high resolution hydraulic modeling at local scale to improve the simulation of river stages at regional scale. The methodology is based on simulation of the main rivers with a 1D Saint-Venant approach, from which functional stage-discharge relationships, are derived and projected onto each grid-cell of the regional model. At regional scale, the rating curves are used as boundary conditions and allow to calculate river stage, which is then used to calculate the exchanges between aquifer units and river. The approach is efficient to better simulate water pathways and stream-aquifer interactions at regional scale with low computing cost. The model was used to quantify stream to aquifer exchanges, that are in average 39 mm yr -1 for aquifer to stream fluxes and 2 mm yr -1 for stream to aquifer fluxes, mainly due to storage in aquifer units during storm events.

Saleh, Firas; Flipo, Nicolas; Habets, Florence; Ducharne, Agnès; Oudin, Ludovic; Viennot, Pascal; Ledoux, Emmanuel

2011-04-01

 
 
 
 
41

[Fractions and adsorption characteristics of phosphorus on sediments and soils in water level fluctuating zone of the Pengxi River, a tributary of the Three Gorges Reservoir].  

Science.gov (United States)

The sediment, one of the key factors leading to the eutrophication of water bodies, is an important ecological component of natural water body. In order to investigate the morphological characteristics and moving-transiting rule of phosphorus in the sediments of the Pengxi River, a tributary of the Three Gorges Reservoir, the distributions of different phosphorus forms on the three cross-section in the sediments and three soil types of riparian zone were investigated using the sequential extraction method. The characteristics of phosphorus adsorption on the sediments were also investigated by batch experiments. The equilibrium phosphorus concentrations at zero adsorption (EPC0) on those sediments were estimated using the Henry linear models. The results show that the total phosphorus (TP) contents of these sediments and soils of riparian zone were 0.80-1.45 g x kg(-1) and 0.65-1.16 g x kg(-1), respectively. Phosphorus in sediments and soils were divided into inorganic phosphorus (IP) and organic phosphorus (Or-P), and the inorganic phosphorus was the dominant component of TP. Of the inorganic phosphorus fractions, the percentages of phosphorus bounded to calcium (Ca-P) and occluded phosphorus (O-P) from sediments were higher than 80%, implying that the contents of phosphorus were mainly influenced by their bedrocks and the sedimentary environmental conditions, not by the activities of human beings. The fractions of Ca-P and O-P were the dominant components of inorganic phosphorus in alluvial soil and purple soil, while the fraction of O-P was the highest in the paddy soil. The EPC0 values of the sediments from the sections of Huangshi, Shuangjiang and Gaoyang were 0.08, 0.13 and 0.11 mg x L(-1) respectively, but the EPC0 values of the alluvial soil, purple soil and paddy soil located in riparian zone were 0.08, 0.09 and 0.04 mg x L(-1), respectively. Correlation analysis shows that the values of EPC0 positively related to the contents of total phosphorus and clay content, and significantly related to the content of Ca-P and pH values. According to the phosphorus concentration in the water of Pengxi River, it concludes that sediments and soils in the zone of fluctuating water level of the Pengxi river can be the sink of phosphorus in summer and autumn, while can be the source of phosphorus in the spring and winter. Therefore, the inherent phosphorus present in sediments and soils would be a major threat to the water quality and ecosystem reservation in the watershed of the Pengxi River. PMID:23745421

Sun, Wen-Bin; Du, Bin; Zhao, Xiu-Lan; He, Bing-Hui

2013-03-01

42

River and cooling water temperature fluctuations  

International Nuclear Information System (INIS)

Cooling water discharged from a power plant changes the fluctuating water temperature characteristics of a receiving river in a clearly detectable way. Daily and hourly water temperature data from two power plant sites on the Upper Mississippi River were used to compute for illustration the magnitude of such differences. Extreme value analysis, autocovariance and spectral analysis, and nonlinear curve fitting methods were applied alternatively. Amplitudes of seasonal periodicities, of diurnal periodicities, and of random components were determined. The results indicate that time series analysis of water temperatures measured downstream from an existing cooling water outfall may provide equally or even more realistic and useful information on the size of a cooling water plume than quasi-instantaneous surveys of spatial water temperature distributions

43

Mesoscale wind fluctuations over Danish waters  

Energy Technology Data Exchange (ETDEWEB)

Mesoscale wind fluctuations affect the large scale integration of wind power because they undermine the day-ahead predictability of wind speed and power production, and because they can result in large fluctuations in power generation that must be balanced using reserve power. Large fluctuations in generated power are a particular problem for offshore wind farms because the typically high concentration of turbines within a limited geographical area means that fluctuations can be correlated across large numbers of turbines. Furthermore, organised mesoscale structures that often form over water, such as convective rolls and cellular convection, have length scales of tens of kilometers, and can cause large wind fluctuations on a time scale of around an hour. This thesis is an exploration of the predictability of mesoscale wind fluctuations using observations from the world's first two large offshore wind farms - Horns Rev I in the North Sea, and Nysted in the Baltic Sea. The thesis begins with a climatological analysis of wind fluctuations on time scales of 1-10 hours at the two sites. A novel method for calculating conditional climatologies of spectral information is proposed, based on binning and averaging the time axis of the Hilbert spectrum. Results reveal clear patterns between wind fluctuations and locally observed meteorological conditions. The analysis is expanded by classifying wind fluctuations on time scales of 1-3 hours according to synoptic patterns, satellite pictures and wind classes. Results indicate that cold air outbreaks and open cellular convection are a significant contributor to mesoscale wind variability at Horns Rev. The predictability of mesoscale wind fluctuations is tested by implementing standard statistical models that relate local wind variability to parameters based on a large scale weather analysis. The models show some skill, but only achieve a 15% improvement on a persistence forecast. The possibility of explicitly modelling mesoscale fluctuations in a mesoscale model is then examined using the weather research and forecasting (WRF) model. A set of case studies demonstrate that realistic hour-scale wind fluctuations and open cellular convection patterns develop in WRF simulations with 2 km horizontal grid spacing. The atmospheric conditions during one of the case studies are then used to initialise a simplified version of the model that has no large scale weather forcing, topography or surface inhomogeneties. Using the simplified model, the sensitivity of the modelled open cellular convection to choices in model setup and to aspects of the environmental forcing are tested. Finally, the cell-scale kinetic energy budget of the modelled cells is calculated, and it is shown that the buoyancy and pressure balance terms are important for cell maintenance. It is explained that the representation of mesoscale convection in a mesoscale model is not only important to end users such as wind farm operators, but to the treatment of energy transport within the boundary layer. (Author)

Vincent, C.L.

2010-12-15

44

Ecological Engineering of Drawdown Wetlands Based on Water-level Fluctuation-Baijia Stream in the Three Gorges Reservoir as a Case Study  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Three Gorges Reservoir (TGR) provides the benefits of flood control, electricity generation and improved transportation along the river corridor. For the purpose of flood control, the reservoir height varies between 145 m and 175 m above sea level, creating a reservoir littoral zone of about 350 km2 in total area distributed along more than 1200 km of shoreline. Most of the littoral zone is flooded during October to May and relatively dry during the remainder of the year. Water level regu...

Wang, Qiang; Li, Bo; Liu, Hong; Xiong, Sen; Yuan, Xing-zhong

2012-01-01

45

Hydrological processes and water resources management in a dryland environment IV: Long-term groundwater level fluctuations due to variation in rainfall  

Directory of Open Access Journals (Sweden)

Full Text Available To evaluate the effects of variations in rainfall on groundwater, long-term rainfall records were used to simulate groundwater levels over the period 1953-96 at an experimental catchment in south-east Zimbabwe. Two different modelling methods were adopted. Firstly, a soil water balance model (ACRU simulated drainage from daily rainfall and evaporative demand; groundwater levels were predicted as a function of drainage, specific yield and water table height. Secondly, the cumulative rainfall departure method was used to model groundwater levels from monthly rainfall. Both methods simulated observed groundwater levels over the period 1992-96 successfully, and long-term simulated trends in historical levels were comparable. Results suggest that large perturbations in groundwater levels area a normal feature of the response of a shallow aquifer to variations in rainfall. Long-term trends in groundwater levels are apparent and reflect the effect of cycles in rainfall. Average end of dry season water levels were simulated to be almost 3 m higher in the late 1970s compared to those of the early 1990s. The simulated effect of prolonged low rainfall on groundwater levels was particularly severe during the period 1981-92 with a series of low recharge years unprecedented in the earlier record. More recently, above average rainfall has resulted in generally higher groundwater levels. The modelling methods described may be applied in the development of guidelines for groundwater schemes to help ensure safe long-term yields and to predict future stress on groundwater resources in low rainfall periods; they are being developed to evaluate the effects of land use and management change on groundwater resources.

J. A. Butterworth

1999-01-01

46

Hydrophobic nanoconfinement suppresses fluctuations in supercooled water  

International Nuclear Information System (INIS)

We perform very efficient Monte Carlo simulations to study the phase diagram of a water monolayer confined in a fixed disordered matrix of hydrophobic nanoparticles between two hydrophobic plates. We consider different hydrophobic nanoparticle concentrations c. We adopt a coarse-grained model of water that, for c = 0, displays a first-order liquid-liquid phase transition (LLPT) line with negative slope in the pressure-temperature (P-T) plane, ending in a liquid-liquid critical point at about 174 K and 0.13 GPa. We show that upon increase of c the liquid-gas spinodal and the temperature of the maximum density line are shifted with respect to the c = 0 case. We also find dramatic changes in the region around the LLPT. In particular, we observe a substantial (more than 90%) decrease of isothermal compressibility, thermal expansion coefficient and constant-pressure specific heat upon increasing c, consistent with recent experiments. Moreover, we find that a hydrophobic nanoparticle concentration as small as c = 2.4% is enough to destroy the LLPT for P ? 0.16 GPa. The fluctuations of volume apparently diverge at P ? 0.16 GPa, suggesting that the LLPT line ends in an LL critical point at 0.16 GPa. Therefore, nanoconfinement reduces the range of P-T where the LLPT is observable. By increasing the hydrophobic nanoparticle concentration c, the LLPT becomes weaker and its P-T range smaller. The model allows us to explain these phenomena in terms of a proliferation of interf in terms of a proliferation of interfaces among domains with different local order, promoted by the hydrophobic effect of the water-hydrophobic-nanoparticle interfaces. (paper)

47

Impacts of Water Level Fluctuations on Kokanee Reproduction in Flathead Lake; Effects of Operation of Kerr and Hungry Horse Dam on Reproductive Success, 1983 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

Koktneesalmon (Oncorhvnchusnerka), the land-locked form of sockeye salmon, were originally introduced to Flathead Lake in 1916. My 1933, kokanee had become established in the lake and provided a popular summer trolling fishery as well as a fall snagging fishery in shoreline areas. Presently, Flathead Lake supports the second highest fishing pressure of any lake or reservoir in Montana (Montana Department of Fish and Game 1976). During 1981-82, the lake provided 168,792 man-days of fishing pressure. Ninety-two percent of the estimated 536,870 fish caught in Flathead Lake in 1981-82 were kokanee salmon. Kokanee also provided forage for bull trout seasonally and year round for lake trout. Kokanee rear to maturity in Flathead Lake, then return to various total grounds to spawn. Spawning occurred in lake outlet streams, springs, larger rivers and lake shoreline areas in suitable but often limited habitat. Shoreline spawning in Flathead Lake was first documented in the mid-1930's. Spawning kokanee were seized from shoreline areas in 1933 and 21,000 cans were processed and packed for distribution to the needy. Stefanich (1953 and 1954) later documented extensive but an unquantified amount of spawning along the shoreline as well as runs in Whitefish River and McDonald Creek in the 1950's. A creel census conducted in 1962-63 determined 11 to 13 percent of the kokanee caught annually were taken during the spawning period (Robbins 1966). During a 1981-82 creel census, less than one percent of the fishermen on Flathead Lake were snagging kokanee (Graham and Fredenberg 1982). The operation of Kerr Dam, located below Flathead Lake on the Flathead River, has altered seasonal fluctuations of Flathead Lake. Lake levels presently remain high during kokanee spawning in November and decline during the incubation and emergence periods. Groundwater plays an important role in embryo and fry survival in redds of shoreline areas exposed by lake drawdown. Stefanich (1954) and Domrose (1968) found live eggs and fry only in shoreline spawning areas wetted by groundwater seeps. Impacts of the operation of Kerr Dam on lakeshore spawning have not been quantified. Recent studies have revealed that operation of Hungry Horse Dam severely impacted successful kokanee spawning and incubation in the Flathead River above Flathead Lake (Graham et al. 1980, McMullin and Graham 1981, Fraley and Graham 1982 and Fraley and McMullin 1983). Flows from Hungry Horse Dam to enhance kokanee reproduction in the river system have been voluntarily met by the Bureau of Reclamation since 1981. In lakeshore spawning areas in other Pacific Northwest systems, spawning habitat for kokanee and sockeye salmon was characterized by seepage or groundwater flow where suitable substrate composition existed (Foerster 1968). Spawning primarily occurred in shallower depths (<6 m) where gravels were cleaned by wave action (Hassemer and Rieman 1979 and 1980, Stober et al. 1979a). Seasonal drawdown of reservoirs can adversely affect survival of incubating kokanee eggs and fry spawned in shallow shoreline areas. Jeppon (1955 and 1960) and Whitt (1957) estimated 10-75 percent kokanee egg loss in shoreline areas of Pend Oreille Lake, Idaho after regulation of the upper three meters occurred in 1952. After 20 years of operation, Bowler (1979) found Pend Oreille shoreline spawning to occur in fewer areas with generally lower numbers of adults. In studies on Priest Lake, Idaho, Bjornn (1957) attributed frozen eggs and stranded fry to winter fluctuations of the upper three meters of the lake. Eggs and fry frozen during winter drawdown accounted for a 90 percent loss to shoreline spawning kokanee in Donner Lake, California (Kimsey 1951). Stober et al. (1979a) determined irrigation drawdown of Banks Lake, Washington reduced shoreline survival during five of the seven years the system was studied. The goal of this phase of the study was to evaluate and document effects of the operation of Kerr Dam on kokanee shoreline reproduction in Flathead Lake. Specific objectives to meet this goal ar

Decker-Hess, Janet; McMullin, Steve L.

1983-11-01

48

Dietary factors and fluctuating levels of melatonin  

Directory of Open Access Journals (Sweden)

Full Text Available Melatonin is secreted principally by the pineal gland and mainly at nighttime. The primary physiological function is to convey information of the daily cycle of light and darkness to the body. In addition, it may have other health-related functions. Melatonin is synthesized from tryptophan, an essential dietary amino acid. It has been demonstrated that some nutritional factors, such as intake of vegetables, caffeine, and some vitamins and minerals, could modify melatonin production but with less intensity than light, the most dominant synchronizer of melatonin production. This review will focus on the nutritional factors apart from the intake of tryptophan that affect melatonin levels in humans. Overall, foods containing melatonin or promoting the synthesis of it by impacting the availability of tryptophan, as well those containing vitamins and minerals which are needed as co-factors and activators in the synthesis of melatonin, may modulate the levels of melatonin. Even so, the influence of daytime diet on the synthesis of nocturnal melatonin is limited, however, the influence of the diet seems to be more obvious on the daytime levels.

Katri Peuhkuri

2012-07-01

49

Temporal fluctuations of formaldehyde levels inside residences  

Energy Technology Data Exchange (ETDEWEB)

Excursions in the levels of formaldehyde were measured inside three houses. These were a 10-y-old home, a 3 y-old home prefitted with urea-formaldehyde foam insulation (UFFI), and a 2-y-old energy-efficient home. Measurements of formaldehyde were made using active and passive air-sampling devices with subsequent colorimetric analysis by the pararosaniline procedure. The variation of diurnal formaldehyde concentrations inside each house varied by up to a factor of two. Over the course of a year, the formaldehyde concentration within the 3-y-old UFFI house varied by an order of magnitude. These changes appeared to correlate with factors such as changes in the temperature, weather, and occupant activity. Inside the 2-y-old house the effects on formaldehyde levels of increased ventilation rate and the operation of a small charcoal-based air cleaner were studied. The results suggest that formaldehyde levels were not inversely proportional to the air exchange rate and that the air cleaner tested were ineffective.

Gammage, R.B.; Hingerty, B.E.; Matthews, T.G.; Hawthorne, A.R.; Womack, D.R.; Westley, R.R.; Gupta, K.C.

1983-01-01

50

Dietary factors and fluctuating levels of melatonin.  

Science.gov (United States)

Melatonin is secreted principally by the pineal gland and mainly at nighttime. The primary physiological function is to convey information of the daily cycle of light and darkness to the body. In addition, it may have other health-related functions. Melatonin is synthesized from tryptophan, an essential dietary amino acid. It has been demonstrated that some nutritional factors, such as intake of vegetables, caffeine, and some vitamins and minerals, could modify melatonin production but with less intensity than light, the most dominant synchronizer of melatonin production. This review will focus on the nutritional factors apart from the intake of tryptophan that affect melatonin levels in humans. Overall, foods containing melatonin or promoting the synthesis of it by impacting the availability of tryptophan, as well those containing vitamins and minerals which are needed as co-factors and activators in the synthesis of melatonin, may modulate the levels of melatonin. Even so, the influence of daytime diet on the synthesis of nocturnal melatonin is limited, however, the influence of the diet seems to be more obvious on the daytime levels. PMID:22826693

Peuhkuri, Katri; Sihvola, Nora; Korpela, Riitta

2012-01-01

51

Ground water head fluctuations in coastal aquifers. Sensitivity analysis and hydromechanical effects.  

Science.gov (United States)

Fluctuations of ground water head in response to sea level fluctuations have long been considered very informative of aquifer diffusivity and connectivity to the sea, which is critical for coastal aquifers management. We present a sensitivity analysis of the inland dampening of the fluctuations amplitude and of their time shift to show that their interpretation is quite robust. That is, fluctuations are not overly sensitive to heterogeneity or to density variations in the case of unconfined aquifers. However, fluctuations are observed in confined aquifers that are hydraulically connected to the sea far off shore. Such response is hydro-mechanically driven by the fluctuations in mechanical load over the sea floor caused by sea level fluctuations. We present the analytical solution to this problem that generalizes existing solutions. The solution contains a hydraulic and a mechanical response terms. The former would inform about the off-shore distance to the sea-aquifer connection, but is dampened in most practical situations, when the mechanical effect becomes significant. In fact, the amplitude of tide-induced head fluctuations at the shore for such cases is approximately one half of the tidal fluctuation. Therefore, large fluctuations cannot be associated to good sea-aquifer hydraulic connection. Fortunately, the amplitude and phase shift are easy to simulate and quite sensitive to aquifer diffusivity and aquitard sorptivity. Therefore, they can be reliably used for large scale model calibration, provided that a good conceptual model and other model parameters are available.

Carrera Ramirez, J.; Guarracino, L.; Slooten, L. J.; Vazquez-Sune, E.

2012-12-01

52

Capillary effect on water table fluctuations in unconfined aquifers  

Science.gov (United States)

Parlange and Brutsaert (1987) derived a modified Boussinesq equation to account for the capillary effect on water table dynamics in unconfined aquifers. Barry et al. (1996) solved this equation subject to a periodic boundary condition. Their solution shows significant influence of capillarity on water table fluctuations, which evolve to finite-amplitude standing waves at the high frequency limit. Here we propose a new governing equation for the water table, which considers both horizontal and vertical flows in an unsaturated zone of finite thickness. An approximate analytical solution for periodic water table fluctuations based on the new equation was derived. In agreement with previous results, the analytical solution shows that the unsaturated zone's storage capacity permits water table fluctuations to propagate more readily than predicted by the Boussinesq equation. Furthermore, the new solution reveals a capping effect of the unsaturated zone on both the amplitude and phase of the water table fluctuations as well as the water table overheight. Due to the finite thickness of the unsaturated zone, the capillary effect on water table fluctuations is modified mainly with reduced amplitude damping and phase shift.

Kong, Jun; Shen, Cheng-Ji; Xin, Pei; Song, Zhiyao; Li, Ling; Barry, D. A.; Jeng, D.-S.; Stagnitti, F.; Lockington, D. A.; Parlange, J.-Y.

2013-05-01

53

Noncritical behavior of density fluctuations in supercooled water  

International Nuclear Information System (INIS)

We have measured the absolute structure factor of liquid water over the wave-number range 0.05-1 and temperature range -34< T<25 degree C with small-angle x-ray scattering. The correlation lengths of density fluctuations are small and change very little with temperature, suggesting that supercooled water may not be approaching a proposed spinodal point. The increasing density fluctuations with supercooling in water appear to be due to an increasing fraction of water molecules participating in clusters, not an increasing range of correlations

54

Evolution of the Danube Deep-Sea Fan since the Last Glacial Maximum: insights into water level fluctuations in the Black Sea  

Science.gov (United States)

The Danube deep-sea fan is one of the most extensive deep-sea sedimentary systems in Europe. It lies in the base of slope of the north-western margin of the Black Sea, in front of Viteaz Canyon. Since the work of Popescu (2002) the detailed morphology and architecture of the fan is well known. During lowstand periods, the fan was fed by the Viteaz Canyon, which was directly connected to the Danube River. The fan has developed an impressive channel-levees network which is characterized by seven major channel avulsions (Popescu, 2002, Lericolais et al., 2013). Despite the numerous sedimentary cores retrieved during the Blason (1998, 2002) and Assemblage (2004) oceanographic cruises, the details of the factors controlling the turbiditic activity of the Danube deep-sea fan still remained largely unknown. The purpose of our study is to improve the chronology of the Danube deep-sea fan and to tie the expected results to the recent findings obtained by Soulet et al. (2011) regarding the chronostratigraphy and environmental changes in the Black Sea since the Last Glacial Maximum (~26-19 kyr before present). Seven küllenberg cores, retrieved from along the Viteaz Canyon and the deep depositional system, were analysed through detailed visual description, X-ray radiographs, spectrocolorimetry and X-Ray Fluorescence (XRF) scanner analysis. These analyses allow core-to-core correlation and the recognition of the well-known sedimentary units of Degens and Ross (1972; lacustrine and marine units) and Major et al. (2002; Red Layers), while using the revisited chronology of Soulet et al. (2011). Sediment accumulation rates and turbidite frequency were then determined, revealing a shift in the sedimentation activity from the southern channel-levee system (Unit 3; Lericolais et al., 2013) to the northern channel-levee system (Unit 6; Lericolais et al., 2013) after the deposition of the so-called Red Layers 15,700 +/-300 yr ago and before the onset of the Bölling-Alleröd (14,700 yr cal BP). The feeding of the northern channel-levee system continued until the marine invasion ca 9,000 yr ago, while no turbidite activity in the Danube deep-sea fan and the Viteaz canyon is observed thereafter. These results are of primary importance to understand sediment transfer from source (Danube River) to sink (Danube deep-sea fan) in Central Europe since the last glacial period, and we will discuss our results in the light of recent reconstructions of past terrestrial environmental (Soulet et al., 2013) and sea-level changes in the Black Sea region (Lericolais et al., 2009).

Constantinescu, Adriana-Maria; Toucanne, Samuel; Dennielou, Bernanrd; Jorry, Stephan; Panin, Nicolae; Lericolais, Gilles

2014-05-01

55

Fluctuation spectrum and size scaling of river flow and level  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We describe the statistical properties of two large river systems: the Danube and the Mississippi. The properties of the two rivers are compared qualitatively to the general properties of a critical steady state system. Specifically, we test the recent suggestion by Bramwell, Fennell, Holdsworth and Portelli [{\\it Europhys. Lett.} {\\bf 57}, 310 (2002)] that a universal probability density function (PDF) exists for the fluctuations in river level, namely the Bramwell-Holdswor...

Dahlstedt, Kajsa; Jensen, Henrik Jeldtoft

2003-01-01

56

Water level instrumentation simulation  

International Nuclear Information System (INIS)

Through simulation, evaluations of system performance can be made to increase efficiency, reduce costs, enhance safety and provide effective training. A full function simulation for evaluating water level measurement requires modeling the physical process, the process instrumentation response and where appropriate, the human input/response. This paper examines a full function application simulating the primary system water level in a Boiling Water Reactor (BWR). The physical processes associated with BWR vessel level response are modeled with the Modular Accident Analysis Program (MAAP). The MAAP code is used as the basis for providing primary system and containment thermal-hydraulic response to a compendium of expected plant transients. The BWR vessel level instruments is modeled with the FAI developed Instrumentation PACkage (IPAC). With the thermal-hydraulic input from MAAP, the IPAC software models the various phenomena associated with water level measurements including the effects due to: (1) instrument channel calibration, (2) instrument drift and (3) containment (drywell) environmental effects. This paper discusses the IPAC models (instrumentation components) along with the factors which influence the mass balance of water in the downcomer region. A comparison of the BWR vessel water level complete simulation package to data from a simulated BWR plant transient culminates the discussion of this paper. The full function simulation package presented in this papersimulation package presented in this paper, enables a software-based representation of the BWR vessel level to be evaluated under various hypothetical plant conditions including normal, accident, and severe accident events. (author)

57

Flux Lattice Melting and Lowest Landau Level Fluctuations  

Science.gov (United States)

We discuss the influence of lowest Landau level (LLL) fluctuations near H_c2(T) on flux lattice melting in YBa_2Cu_3O_7-? (YBCO). We show that the specific heat step(A. Schilling, R. A. Fisher, N. E. Phillips, U. Welp, W. K. Kwok, and G. W. Crabtree, Phys. Rev. Lett. 78), 4833 (1997). of the flux lattice melting transition in YBCO single crystals can be attributed largely to the degrees of freedom associated with LLL fluctuations. These degrees of freedom have already been shown to account for most of the latent heat.(J. Hu and A. H. MacDonald, Phys. Rev. B 56), 2788 (1997). We also show that these results are a consequence of the correspondence between flux lattice melting and the onset of LLL fluctuations, using the LLL prediction for the field dependence of the melting temperature of Herbut and Tešanovi?.(I. F. Herbut and Z. Tešanovi?, Physica C 225), 324 (1995). For further discussion on this topic, download the manuscript with the same name as this abstract from the first author's publications web page.

Pierson, Stephen W.; Valls, Oriol T.

1998-03-01

58

Fluctuations of water near extended hydrophobic and hydrophilic surfaces  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We use molecular dynamics simulations of the SPC-E model of liquid water to derive probability distributions for water density fluctuations in probe volumes of different shapes and sizes, both in the bulk as well as near hydrophobic and hydrophilic surfaces. To obtain our results, we introduce a biased sampling of coarse-grained densities, which in turn biases the actual solvent density. The technique is easily combined with molecular dynamics integration algorithms. Our pri...

Patel, Amish J.; Chandler, David

2009-01-01

59

Mesoscale wind fluctuations over Danish waters  

DEFF Research Database (Denmark)

Mesoscale wind uctuations aect the large scale integration of wind power because they undermine the day-ahead predictability of wind speed and power production, and because they can result in large uctuations in power generation that must be balanced using reserve power. Large uctuations in generated power are a particular problem for oshore wind farms because the typically high concentration of turbines within a limited geographical area means that uctuations can be correlated across large numbers of turbines. Furthermore, organised mesoscale structures that often form over water, such as convective rolls and cellular convection, have length scales of tens of kilometers, and can cause large wind uctuations on a time scale of around an hour. This thesis is an exploration of the predictability of mesoscale wind uctuations using observations from the world's rst two large oshore wind farms - Horns Rev I in the North Sea, and Nysted in the Baltic Sea. The thesis begins with a climatological analysis of wind uctuations on time scales of 1{10 hours at the two sites. A novel method for calculating conditional climatologies of spectral information is proposed, based on binning and averaging the time axis of the Hilbert spectrum. Results reveal clear patterns between wind uctuations and locally observed meteorological conditions. The analysis is expanded by classifying wind uctuations on time scales of 1{3 hours according to synoptic patterns, satellite pictures and wind classes. Results indicate that cold air outbreaks and open cellular convection are a signicant contributor to mesoscale wind variability at Horns Rev. The predictability of mesoscale wind uctuations is tested by implementing standard statistical models that relate local wind variability to parameters based on a large scale weather analysis. The models show some skill, but only achieve a 15% improvement on a persistence forecast. The possibility of explicitly modelling mesoscale uctuations in a mesoscale model is then examined using the weatherresearch and forecasting (WRF) model. A set of case studies demonstrate that realistic hour-scale wind uctuations and open cellular convection patterns develop in WRF simulations with 2km horizontal grid spacing. The atmospheric conditions during one of the case studies are then used to initialise a simplied version of the model that has no large scale weather forcing, topography or surface inhomogeneties. Using the simplied model, the sensitivity of the modelled open cellular convection to choices in model setup and to aspects of the environmental forcing are tested. Finally, the cell-scale kinetic energy budget of the modelled cells is calculated, and it is shown that the buoyancy and pressure balance terms are important for cell maintenance. It is explained that the representation of mesoscale convection in a mesoscale model is not only important to end users such as wind farm operators, but to the treatment of energy transport within the boundary layer.

Vincent, Claire Louise

2010-01-01

60

Correlation of Deep Water Chlorophyll Concentration Fluctuation with Cyclone Energy  

Science.gov (United States)

The deep water chlorophyll concentration global time series fluctuation from 1998 to 2007 has been studied using fractal analysis. The SeaWiFS global daily mean chlorophyll concentration time series were used. The Higuchi fractal algorithm was used to calculate fractal dimension, which is given by the slope of an associated length versus the lag. Short range fluctuation investigation using a six point slope gives fractal dimensions from 1.80 to 1.85, suggesting the presence of correlation, which was confirmed by computer simulations. The gradual increase of fractal dimension in about 15 lag-days suggests that a long-range de-correlation mechanism favoring random fluctuation is present. The correlation of fractal dimension of chlorophyll concentration with accumulated cyclone energy can be demonstrated when the chlorophyll concentration fluctuation includes a 30% contribution from the previous year. The chlorophyll concentration may have influence from previous year because it is a chemical inside a cell, consistent with the concept of bio-fluctuation. We observed a negative correlation for the earlier years (R-square ~ 0.96 for 1999-2002 data) and a positive correlation for the later years (R-square ~ 0.81 for 2002-2007 data). During the same 10-year period, the cyclone energy changed from a dipping trend to peaking trend around 2001. The analysis shows that yearly chlorophyll concentration is influenced by accumulated cyclone energy as well as last year yield.

Marchese, P.; Cotten, D.; Sunil, D.; Cheung, E.; Holden, T.; Nasar, T.; Cheung, T.

2009-12-01

 
 
 
 
61

Fluctuation spectrum and size scaling of river flow and level  

CERN Document Server

We describe the statistical properties of two large river systems: the Danube and the Mississippi. The properties of the two rivers are compared qualitatively to the general properties of a critical steady state system. Specifically, we test the recent suggestion by Bramwell, Fennell, Holdsworth and Portelli [{\\it Europhys. Lett.} {\\bf 57}, 310 (2002)] that a universal probability density function (PDF) exists for the fluctuations in river level, namely the Bramwell-Holdsworth-Pinton (BHP) PDF. The statistical properties investigated in this paper are: the PDF of the river flow and river level; moment scaling with basin area; moment to moment scaling or relative scaling; and power spectral properties of the data. We find that the moments of the flow scale approximately with basin area and that the seasonally adjusted flows exhibit relative moment scaling. Compared to the Mississippi, the Danube shows large deviations from spatial scaling and the power spectra show considerable dependence on system size. This ...

Dahlstedt, K; Dahlstedt, Kajsa; Jensen, Henrik Jeldtoft

2003-01-01

62

Deep-water chlorophyll concentration global time series fluctuation  

Science.gov (United States)

The deep water chlorophyll concentration fluctuation from 2003 to 2007 has been studied using fractal analysis. The SeaWiFS global daily mean chlorophyll concentration time series were used. The Higuchi fractal algorithm was used to calculate fractal dimension, which is given by the slope of an associated length versus the lag. Short range fluctuation investigation using a six point slope gives fractal dimensions from 1.80 to 1.85, suggesting the presence of correlation, which was confirmed by computer simulations. The gradual increase of fractal dimension to 1.9 in about 15 lag-days suggests that a long-range de-correlation mechanism favoring random fluctuation is present. The 2007 times series shows a relatively low overall fractal dimension and exhibits a peculiar multi-fractal behavior. This phenomenon and the observed low accumulated cyclone energy in 2007 support the interpretation that cyclone energy can promote deep-water chlorophyll concentration fluctuation. A regression of fractal dimension at 10 lag-days versus the log of cyclone energy gives an R2 value of 0.75 (N = 5)., which suggests the presence of additional or related de-correlation mechanisms.

Holden, T.; Sunil, D.; Cheung, E.; Cotten, D.; Klarberg, D.; Tremberger, G., Jr.; Nasar, T.; Taylor, J.; Marchese, P.; Cheung, T.

2009-08-01

63

Water level indication  

International Nuclear Information System (INIS)

The possibility of measuring the water level in a PWR by studying the natural frequency of its pendular oscillation is discussed. The effect is complicated both by the complex internals and by the generation of surface waves when the vessel is partially full. For small losses of inventory the effects are measurable, but not large. The principal advantages are that the method measures the mass of water directly, and, above all, that it is noninvasive. The method is described, and the general formulae and numerical examples are given for a greatly oversimplified model. Only testing on real vessels can determine whether the technique is truly useful. (orig.)

64

Heterophase fluctuations and thermodynamic properties in supercooled water  

International Nuclear Information System (INIS)

On looking at the experimental findings on the thermodynamic properties of ordinary liquid water in supercooled state it is found that they can be consistently interpreted if a new contribution due to heterophase fluctuations is superimposed to a ''regular'' behaviour as given by a reliable extrapolation from the stable region. The ''monomer'' liquid which transforms into ice nuclei is associated with a ''close packed'' component of a two-state model interpreting the bulk medium extrapolated properties. By supposing that the amount of ice clusters depends on Tsub(M)-T, where Tsub(M) is the melting temperature, it is found that a simple relationship exists between the slope of the liquid-solid equilibrium curve and the heterophase fluctuation contributions to the isothermal compressibility and thermal-expansion coefficient. The consequences are discussed and compared with sound velocity experiments in water and with the behaviour of thermodynamic properties in other supercooled liquids. A substantial agreement is found

65

Water level control device in nuclear reactor  

International Nuclear Information System (INIS)

Upon start-up and shutdown of a BWR type reactor, the reactor pressure often varies greatly, by which the water level in the reactor also varies greatly. In the conventional water level control method, althogh the change in the water level of the reactor is detected and calculated for the control, it can not sometime follow after the remarkable water level change due to the delay in the calculation. The present invention has been made taking notice of this. That is, an additon/subtraction calculator that conducts addition/subtraction by adding the output of a reactor pressure detector is additionally disposed to a conventional control system using a water level control device. Thus, the opening degree for the feedwater control valve or the discharge water control valve is directly changed depending on the change of the pressure in the reactor. Since the output signal of the reactor water level controller is compensated previously by the signal for the fluctuation of the reactor pressure, rapid response of the water level control can be improved to minimize the water level change. (K.M.)

66

Water level detection pipeline  

International Nuclear Information System (INIS)

In the present invention, water levels of a feedwater heater and a drain tank in a nuclear power plant are detected at high accuracy. Detection pipeline headers connected to the upper and lower portions of a feedwater heater or a drain tank are connected with each other. The connection line is branched at appropriate two positions and an upper detection pipeline and a lower detection pipeline are connected thereto, and a gauge entrance valve is disposed to each of the detection pipelines. A diaphragm of a pressure difference generator is connected to a flange formed to the end portion. When detecting the change of water level in the feedwater heater or the drain tank as a change of pressure difference, gauge entrance valves on the exit side of the upper and lower detection pipelines are connected by a connection pipe. The gauge entrance valve is closed, a tube is connected to the lower detection pipe to inject water to the diaphragm of the pressure difference generator passing through the connection pipe thereby enabling to calibrate the pressure difference generator. The accuracy of the calibration of instruments is improved and workability thereof upon flange maintenance is also improved. (I.S.)

67

Characterization of the level fluctuations in a physical model of the steel continuous casting mold through image processing  

Directory of Open Access Journals (Sweden)

configuration resembles a perfect control of the liquid level inside the water model. A high-speed video camera was used to get several video clips of the movement of the water level profile. Several techniques were tested in order to obtain the best lighting conditions for recording the water movement. The edge-detection technique of Sobel was used to determine the profile of the liquid level in each one of the images recorded. The analysis of the dynamic behavior of the water profile showed that the fluctuations of the liquid level inside the mold have a complex structure, which is repeated over large time periods.

J.R. Miranda-Tello

2012-01-01

68

Water budget and water-surface fluctuations, Great Salt Lake, Utah  

Science.gov (United States)

The water-budget equation for Great Salt Lakes is: Inflow = Outflow + or - Storage change. The average annual inflow for the period 1931-76 was about 2.9 million acre-feet; 1.9 million acre-feet from surface sources, about 900,000 acre-feet from direct precipitation, and about 75,000 acre-feet from ground water. The average annual outflow for the same period, all be evaportion, also was about 2.9 million acre-feet. Storage changes are computed on the basis of changes in the surface level of the lake. During the period of historic record, 1847-1978, the lake surface has fluctuated within a range of about 20 feet but has shown little overall change. The lake surface would have been about 5 feet higher in 1978 than it was in 1947 had there been no consumptive use of water caused by man 's activities in the lake basin. Since 1959 the lake has been divided into two parts by a railroad causeway, which has restricted the natural circulation. This has resulted in a difference of salinity and of surface level across the causeway. The difference in surface level between the two parts of the lake varies seasonally and annually and has been as much as 2.35 feet. (USGS)

Arnow, Ted

1978-01-01

69

Temporal scaling of groundwater level fluctuations near a stream  

Science.gov (United States)

Temporal scaling in stream discharge and hydraulic heads in riparian wells was evaluated to determine the feasibility of using spectral analysis to identify potential surface and groundwater interaction. In floodplains where groundwater levels respond rapidly to precipitation recharge, potential interaction is established if the hydraulic head (h) spectrum of riparian groundwater has a power spectral density similar to stream discharge (Q), exhibiting a characteristic breakpoint between high and low frequencies. At a field site in Walnut Creek watershed in central Iowa, spectral analysis of h in wells located 1 m from the channel edge showed a breakpoint in scaling very similar to the spectrum of Q (~20 h), whereas h in wells located 20 and 40 m from the channel showed temporal scaling from 1 to 10,000 h without a well-defined breakpoint. The spectral exponent (??) in the riparian zone decreased systematically from the channel into the floodplain as groundwater levels were increasingly dominated by white noise groundwater recharge. The scaling pattern of hydraulic head was not affected by land cover type, although the number of analyses was limited and site conditions were variable among sites. Spectral analysis would not replace quantitative tracer or modeling studies, but the method may provide a simple means of confirming potential interaction at some sites. ?? 2011, The Author(s). Ground Water ?? 2011, National Ground Water Association.

Schilling, K.E.; Zhang, Y.-K.

2012-01-01

70

Transfer Function Noise (TFN) Modeling of Dynamic Groundwater Level Fluctuation using Deseasonalized Rainfall Series  

Science.gov (United States)

A study to examine the effect of rainfall variable on groundwater level fluctuation was analyzed using transfer function noise (TFN) models for five representative wells from the study area of Adyar basin located in the north-east coastal part of Tamil Nadu, India. Five representative wells out of 43 were chosen based on maximum coefficient of determination (R2) value by simple linear regression analysis where rainfall and water level rise time series were used as independent and dependent variables respectively. An alternative method of zone wise Thiessen rainfall (ZTR), where the zones were separated by Thiessen method and the wells contained in the zones were regressed upon that particular zone station rainfall values with 100% weightage, was giving maximum R2 value compared to other traditional ways of estimating areal average rainfall methods such as simple arithmetic average (SAA) and Thiessen polygon (TP) methods. Water level fluctuation was further modeled using TFN modeling approach in which missing rainfall was filled using normal ratio (NR) method as it was giving maximum R2 value compared to simple station average (SSA) and inverse distance (ID) methods. A deseasonalized transfer function noise modeling (DS-TFN) approach has been adopted in the study which minimizes the number of numerator and denominator polynomial parameters and assures an improved method of forecasting groundwater level fluctuation in terms of maximum R2 and minimum root mean square error (RMSE) values compared to other traditional TFN models such as ARIMAX and SARIMAX. Before identifying suitable TFN model structure for input-output data, the data was analyzed for seasonality. Since both rainfall series and selected water level data show the seasonality behavior, it was adjusted with deseasonalizing process. Deseasonalizing process was carried out after detrending the data with 13-term moving average process and estimating seasonal component from the detrended series using seasonal indices. Deseasonalized data was then fitted with AR(1) model for both rainfall and water level series and the residual no serial correlation was verified with Ljung-Box Q-test. Pre-whitened residuals from both the series were stored and compared using cross correlation function (CCF). CCF for DS-TFN, ARIMAX and SARIMAX models show one month lag response of the input series over the output series for all 5 stations. ARIMAX and SARIMAX TFN model structure were identified using Box and Jenkins time series methodology where the best model was selected based on Akaike Information Criterion (AIC) values. Whereas DS-TFN model structure was identified with 1 numerator and 1 denominator polynomial coefficient which was enough to make the output residuals with white noise process that ultimately reduces the number of parameters for DS-TFN model.

Shanmugam, M.; Kumar, G.; Narasimhan, B.

2013-12-01

71

Structural Fluctuation of Protein in Water around Its Native State: A New Statistical Mechanics Formulation  

CERN Document Server

A new statistical mechanics formulation of characterizing the structural fluctuation of protein correlated with that of water is presented based on the generalized Langevin equation and the 3D-RISM/RISM theory of molecular liquids. The displacement vector of atom positions and their conjugated momentum, are chosen for the dynamic variables for protein, while the density fields of atoms and their momentum fields are chosen for water. Projection of other degrees of freedom onto those dynamic variables using the standard projection operator method produces essentially two equations which describe the time evolution of fluctuation concerning the density field of solvent and the conformation of protein around an equilibrium state, which are coupled with each other. The equation concerning the protein dynamics is formally akin to that of the coupled Langevin oscillators, and is a generalization of the latter, to atomic level. The most intriguing feature of the new equation is that it contains the variance-covarianc...

Kim, Bongsoo

2012-01-01

72

Large decrease of fluctuations for supercooled water in hydrophobic nanoconfinement.  

Science.gov (United States)

Using Monte Carlo simulations, we study a coarse-grained model of a water layer confined in a fixed disordered matrix of hydrophobic nanoparticles at different particle concentrations c. For c=0, we find a first-order liquid-liquid phase transition (LLPT) ending in one critical point at low pressure P. For c>0, our simulations are consistent with a LLPT line ending in two critical points at low and high P. For c=25%, at high P and low temperature, we find a dramatic decrease of compressibility, thermal expansion coefficient, and specific heat. Surprisingly, the effect is present also for c as low as 2.4%. We conclude that even a small presence of hydrophobic nanoparticles can drastically suppress thermodynamic fluctuations, making the detection of the LLPT more difficult. PMID:21561203

Strekalova, Elena G; Mazza, Marco G; Stanley, H Eugene; Franzese, Giancarlo

2011-04-01

73

Water levels in observation wells in Kentucky : 1935 through 1976  

Science.gov (United States)

Hydrographs show water levels in observation wells in Kentucky from 1935 through 1976. The water levels in these wells are measured as part of the national observation well network and in cooperation with the University of Kentucky, Kentucky Geological Survey. The hydrographs are arranged by the five physiograhic regions of Kentucky, alphabetically by county, and in ascending order of latitude. The collection and tabulation of ground-water levels and aquifer data are used to determine short-term changes and long-range trends in water-level fluctuations which reflect the changes in storage within ground-water reservoirs. (Woodard-USGS)

Whitesides, Douglas V.; Kernodle, John Michael; Leist, David W.

1978-01-01

74

Ground Water Recharge Estimation Using Water Table Fluctuation Method And By GIS Applications  

Science.gov (United States)

Quite often it has become a debating point that how much recharge is occurring to the groundwater table through rainfall on one hand and through recharge structures such as percolation ponds and checkdams on the other. In the present investigations Musi basin of Andhra Pradesh, India is selected for study during the period 2005-06. Pre-monsoon and Post-monsoon groundwater levels are collected through out the Musi basin at 89 locations covering an area11, 291.69 km2. Geology of the study area and rainfall data during the study period has been collected. The contour maps of rainfall and the change in groundwater level between Pre-monsoon and Post- monsoon have been prepared. First the change in groundwater storage is estimated for each successive strips of areas enclosed between two contours of groundwater level fluctuations. In this calculation Specific yield (Sy) values are adopted based on the local Geology. Areas between the contours are estimated through Arc GIS software package. All such storages are added to compute the total storage for the entire basin. In order to find out the percent of rainfall converted into groundwater storage as well as to find out the ground water recharge due to storageponds, a contour map of rainfall for the study area is prepared and areas between successive contours have been calculated. Based on the Geology map, Infiltration values are adopted for each successive strip of the contour area. Then the amount of water infiltrated into the ground is calculated by adjusting the infiltration values for each strip, so that the total infiltrated water for the entire basin is matched with change in Ground water storage, which is 1314.37 MCM for the upper Musi basin while it is 2827.29 MCM for entire Musi basin. With this procedure on an average 29.68 and 30.66 percent of Rainfall is converted into Groundwater recharge for Upper Musi and for entire Musi basin respectively. In the total recharge, the contribution of rainfall directly to Groundwater recharge is 8.53 and 8.81 percent and the remaining 21.15 and 21.85 percent is due to groundwater recharge from water conservation structures such as check dams, contour bunds, tanks, etc. for Upper Musi and for entire Musi basin respectively. The difference is attributable to the canal recharge in the case of Lower Musi. Therefore the Upper Musi values may be taken as a percent of Rainfall that is converted into Groundwater recharge.

Vajja, V.; Bekkam, V.; Nune, R.; M. v. S, R.

2007-05-01

75

A field investigation of phreatophyte-induced fluctuations in the water table  

Science.gov (United States)

Hydrographs from shallow wells in vegetated riparian zones frequently display a distinctive pattern of diurnal water table fluctuations produced by variations in plant water use. A multisite investigation assessed the major controls on these fluctuations and the ecohydrologic insights that can be gleaned from them. Spatial and temporal variations in the amplitude of the fluctuations are primarily a function of variations in (1) the meteorological drivers of plant water use, (2) vegetation density, type, and vitality, and (3) the specific yield of sediments in the vicinity of the water table. Past hydrologic conditions experienced by the riparian zone vegetation, either in previous years or earlier within the same growing season, are also an important control. Diurnal water table fluctuations can be considered a diagnostic indicator of groundwater consumption by phreatophytes at most sites, so the information embedded within these fluctuations should be more widely exploited in ecohydrologic studies. Copyright 2007 by the American Geophysical Union.

Butler, J.J., Jr.; Kluitenberg, G.J.; Whittemore, D.O.; Loheide, S.P., II; Jin, W.; Billinger, M.A.; Zhan, X.

2007-01-01

76

Fluctuation properties of nuclear energy levels: Do theory and experiment agree  

International Nuclear Information System (INIS)

The fluctuation properties of nuclear energy levels with new spectrally averaged measures are analyzed. A remarkably close agreement between the predictions of random-matrix theories and experiment is found

77

Fluctuation properties of nuclear energy levels and widths: comparison of theory with experiment  

International Nuclear Information System (INIS)

We analyze the fluctuation properties of nuclear energy levels and widths with new spectrally averaged measures. A remarkably close agreement between the predictions of random-matrix theories and experiment is found

78

Effect of water table fluctuations on phreatophytic root distribution.  

Science.gov (United States)

The vertical root distribution of riparian vegetation plays a relevant role in soil water balance, in the partition of water fluxes into evaporation and transpiration, in the biogeochemistry of hyporheic corridors, in river morphodynamics evolution, and in bioengineering applications. The aim of this work is to assess the effect of the stochastic variability of the river level on the root distribution of phreatophytic plants. A function describing the vertical root profile has been analytically obtained by coupling a white shot noise representation of the river level variability to a description of the dynamics of root growth and decay. The root profile depends on easily determined parameters, linked to stream dynamics, vegetation and soil characteristics. The riparian vegetation of a river characterized by a high variability turns out to have a rooting system spread over larger depths, but with shallower mean root depths. In contrast, a lower river variability determines root profiles with higher mean root depths. PMID:25014476

Tron, Stefania; Laio, Francesco; Ridolfi, Luca

2014-11-01

79

Investigation of wall temperature fluctuations by visualization tests and numerical simulation for steam-water two-phase flow in the pressurizer spray piping  

International Nuclear Information System (INIS)

In a PWR plant, a steam-water two phase flow may possibly exist in the pressurizer spray pipe under a rated power operating condition since the flow rate of the spray water is not sufficient to fill the horizontal section of the pipe completely. Under such thermally stratified two phase flow conditions, the initiation of high cycle fatigue cracks is suspected to occur due to the cyclic thermal stress fluctuations caused by oscillations of the water surface, which cannot be detected by the measurement of temperature on outer surface of the pipe. In order to clarify the flow and thermal structure in the pressurizer spray pipe and assess its impact on the pipe structure, an experiment was conducted for a steam-water flow at a low flow rate in a simulated pressurizer spray piping. By measuring wall temperature fluctuations, continuous temperature fluctuations, which were around 0.2 times of the steam water temperature difference in the maximum range, were observed at the inclined section where the water surface contacted the pipe wall. So we planed to investigate the causes of the fluctuations by visualization tests. As a result of the experiment, it seemed that wall temperature fluctuations were not caused by waves on water surface, but caused by liquid temperature fluctuation in the layer below the steam-water interface. The influence of small amount of noncondensable gas dissolved in the reactor coolant on the wall temperature fluctuations was investigated by injecting air into the experimental loop. Continuous water temperature fluctuations were attenuated after air was injected. A CFD analysis was performed adopting the VOF method for the experimental condition, and it successfully simulated the averaged temperature distribution but the level of water surface did not fluctuate, and no water temperature fluctuations below the gas-liquid interface were observed contrary to the experimental result. (author)

80

Level Density of a Fermi Gas: Average Growth and Fluctuations  

Science.gov (United States)

We compute the level density of a two-component Fermi gas as a function of the number of particles, angular momentum, and excitation energy. The result includes smooth low-energy corrections to the leading Bethe term (connected to a generalization of the partition problem and Hardy-Ramanujan formula) plus oscillatory corrections that describe shell effects. When applied to nuclear level densities, the theory provides a unified formulation valid from low-lying states up to levels entering the continuum. The comparison with experimental data from neutron resonances gives excellent results.

Leboeuf, Patricio; Roccia, Jérôme

2006-07-01

 
 
 
 
81

Level Density of a Fermi Gas: Average Growth and Fluctuations  

International Nuclear Information System (INIS)

We compute the level density of a two-component Fermi gas as a function of the number of particles, angular momentum, and excitation energy. The result includes smooth low-energy corrections to the leading Bethe term (connected to a generalization of the partition problem and Hardy-Ramanujan formula) plus oscillatory corrections that describe shell effects. When applied to nuclear level densities, the theory provides a unified formulation valid from low-lying states up to levels entering the continuum. The comparison with experimental data from neutron resonances gives excellent results

82

Shallow Water Internal Waves and Associated Acoustic Intensity Fluctuations  

Directory of Open Access Journals (Sweden)

Full Text Available Physical oceanographic and acoustic data were simultaneously collected from the coastal waters of the Arabian Sea. Acoustic transmissions were carried out from an anchored vessel using 620 Hz transducer and received by an array of hydrophones moored at ~5 km away from the anchorage. Thermal structure in this region was characterised by a tri-layer structure, ie, a strong thermocline (> 0.4 oC/m sandwiched between an upper ( 25 m homogeneous layer. High-resolution (sampled at 10 s interval temperature data from moored sensors revealed intense internal wave activity. The maximum value of Brunt-Vaisala frequency, which is the maximum frequency limit of internal waves in the thermocline, suggests that the upper frequency limit of the internal wave, which can be generated during this period, is 23 cph (2.6 min. High and low frequency waves caused variations of ~3 oC and ~5 oC respectively in the temperature field. But the low frequency internal waves were found to contain maximum energy compared to the high frequency waves. Fluctuations of 8-12 dB were noticed in the measured acoustic intensity values in the presence of low frequency internal waves. Simulation studies carried out using parabolic equation model using 620 Hz source indicated well-defined ducted propagation with minimum transmission loss, when the source was kept within the homogeneous layer. The presence of tri-layer thermal structure, ie, a strong gradient layer sandwiched between an upper and bottom homogeneous layer, caused surface and bottom channel propagation in this region.

P.V. Hareesh Kumar

2006-10-01

83

An algorithm based on sea level pressure fluctuations to identify major Baltic inflow events  

Science.gov (United States)

The Baltic Sea is one of world largest brackish water areas with an estuarine like circulation. It is connected to the world ocean through the narrow Danish straits limiting the exchange of water masses. The deep water of the Baltic Sea is mainly renewed by so called major Baltic inflows which are an important feature to sustain the sensitive steady state of the Baltic Sea. We introduce an algorithm to identify atmospheric variability favourable for major Baltic inflows. The algorithm is based on sea level pressure fields as the only parameter. Characteristic sea level pressure pattern fluctuations include a precursory phase of 30 days and 10 days of inflow period. The algorithm identifies successfully the majority of observed major Baltic inflows between 1961--2010. In addition, the algorithm finds some occurrences which cannot be related to observed inflows. In these cases with favourable atmospheric conditions inflows were precluded by contemporaneously existing saline water masses or strong freshwater supply. No event is registered during the stagnation period 1983-1993 indicating that the lack of inflows is a consequence of missing favourable atmospheric variability. The only striking inflow which is not identified by the algorithm is the event in January 2003. We demonstrate that this is due to the special evolution of sea level pressure fields which are not comparable with any other event. Finally, the algorithm is applied to an ensemble of scenario simulations. The result indicates that the number of atmospheric events favourable for major Baltic inflows increases slightly in all scenarios. Possible explanations as for instance more frequent atmospheric blockings or changes in the NAO will be discussed.

Schimanke, Semjon; Dieterich, Christian; Markus Meier, H. E.

2014-05-01

84

Entropic uncertainty measure for fluctuations in two-level electron-phonon models  

CERN Document Server

Two-level electron-phonon systems with reflection symmetry linearly coupled to one or two phonon modes (exciton and E$\\otimes(b_1+b_2)$ Jahn-Teller model) exhibit strong enhancement of quantum fluctuations of the phonon coordinates and momenta due to the complex interplay of quantum fluctuations and nonlinearities inherent to the models. We show that for the complex correlated quantum fluctuations of the anisotropic two-level systems the Shannon entropies of phonon coordinate and momentum and their sum yield their proper global description. On the other hand, the variance measures of the Heisenberg uncertainties suffer from several shortcomings to provide proper description of the fluctuations. Wave functions, related entropies and variances were determined by direct numerical simulations. Illustrative variational calculations were performed to demonstrate the effect on an analytically tractable exciton model.

Majernikova, E; Shpyrko, S

2004-01-01

85

A causal model for fluctuating sugar levels in diabetes patients  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background Causal models of physiological systems can be immensely useful in medicine as they may be used for both diagnostic and therapeutic reasoning. Aims In this paper we investigate how an agent may use the theory of belief change to rectify simple causal models of changing blood sugar levels in diabetes patients. Method We employ the semantic approach to belief change together with a popular measure of distance called Dalal distance between different state descriptions in order to imple...

Kinzang Chhogyal; Abhaya Nayak; Rolf Schwitter; Abdul Sattar

2012-01-01

86

Analytical Solutions for Examining Spatial Variations in Evapotranspiration-Driven Fluctuations in the Water Table in Vegetated Riparian Zones  

Science.gov (United States)

Diurnal water-table fluctuations observed in shallow wells in vegetated riparian zones are a diagnostic indicator of groundwater consumption by evapotranspiration (ETG). In order to better understand how these fluctuations vary across a riparian zone, analytical solutions for strip-sinks with periodic forcing functions were developed. The periodic forcing functions, which represent the evapotranspirative consumption of groundwater, are finite within the strips and zero outside. Linearity allows superposition of the strip solutions to simulate spatial variations in ETG due to variations in vegetation density within the riparian zone. The solution is applied to data from a field site in a riparian zone along the Arkansas River in west-central Kansas where groundwater levels in shallow wells have been monitored at 15-minute intervals for up to five years. A series of strips were used to represent the largely dry unvegetated river channel, two zones within the vegetated riparian zone, and adjacent pastures and cultivated fields. The spatial variations in the phase and amplitude of the simulated fluctuations were consistent with general patterns observed in the field data during both wet and dry years. Several empirical methods have been developed for estimating ET G using characteristics of the diurnal water-table fluctuations. This solution reveals where best to place wells for use with those methods. Similar solutions have been developed for circular sinks to assess the impact of phreatophyte-control activities on water-table fluctuations at wells in areas of cleared vegetation.

Jin, W.; Kluitenberg, G. J.; Butler, J. J.

2007-12-01

87

Lake level fluctuations synchronize genetic divergences of cichlid fishes in African lakes.  

Science.gov (United States)

Water level fluctuations are important modulators of speciation processes in tropical lakes, in that they temporarily form or break down barriers to gene flow among adjacent populations and/or incipient species. Time estimates of the most recent major lowstands of the three African Great Lakes are thus crucial to infer the relative timescales of explosive speciation events in cichlid species flocks. Our approach combines geological evidence with genetic divergence data of cichlid fishes from the three Great East African Lakes derived from the fastest-evolving mtDNA segment. Thereby, we show for each of the three lakes that individuals sampled from several populations which are currently isolated by long geographic distances and/or deep water form clusters of equally closely related haplotypes. The distribution of identical or equally closely related haplotypes in a lake basin allows delineation of the extent of lake level fluctuations. Our data suggest that the same climatic phenomenon synchronized the onset of genetic divergence of lineages in all three species flocks, such that their most recent evolutionary history seems to be linked to the same external modulators of adaptive radiation. A calibration of the molecular clock of the control region was elaborated by gauging the age of the Lake Malawi species flock through the divergence among the utaka-cichlid and the mbuna-cichlid lineages to minimally 570,000 years and maximally 1 Myr. This suggests that the low-lake-level period which established the observed patterns of genetic relatedness dates back less than 57,000 years, probably even to 17,000-12,400 years ago, when Lake Victoria dried up and Lakes Malawi and Tanganyika were also low. A rapid rise of all three lakes about 11,000 years ago established the large-scale population subdivisions observed today. Over that period of time, a multitude of species originated in Lakes Malawi and Victoria with an impressive degree of morphological and ecological differentiation, whereas the Tanganyikan taxa that were exposed to the same habitat changes hardly diverged ecologically and morphologically. Our findings also show that patterns of genetic divergences of stenotopic organisms provide valuable feedback on geological and sedimentological time estimates for lake level changes. PMID:11158373

Sturmbauer, C; Baric, S; Salzburger, W; Rüber, L; Verheyen, E

2001-02-01

88

Reconstruction of Caspian sea-level fluctuations: Radiocarbon dating coastal and bottom deposits  

Energy Technology Data Exchange (ETDEWEB)

Owing to the large basin area of the Caspian Sea, fluctuations in its level reflect climatic changes in the northern hemisphere. To reconstruct these fluctuations, they collected mollusk shells, plant debris, carbonates and organic matter samples for [sup 14]C dating from deposits of ancient salt marshes, depressions and bars formed during significant sea-level decline they studied the impact of eolian sedimentation via parallel dating of carbonates and other materials. The data demonstrate that sea level rises during periods of cooling and falls during warming periods; this is true for both long-term (2--2.5 ka) and short-term climatic changes.

Karpytchev, Yu.A. (Russian Academy of Sciences, Moscow (Russian Federation))

1993-01-01

89

A Causal Model for Fluctuating Sugar Levels in Diabetes Patients  

Directory of Open Access Journals (Sweden)

Full Text Available Background Causal models of physiological systems can be immensely useful in medicine as they may be used for both diagnostic and therapeutic reasoning. Aims In this paper we investigate how an agent may use the theory of belief change to rectify simple causal models of changing blood sugar levels in diabetes patients. Method We employ the semantic approach to belief change together with a popular measure of distance called Dalal distance between different state descriptions in order to implement a simple application that simulates the effectiveness of the proposed method in helping an agent rectify a simple causal model. Results Our simulation results show that distance-based belief change can help in improving the agent’s causal knowledge. However, under the current implementation there is no guarantee that the agent will learn the complete model and the agent may at times get stuck in local optima. Conclusion Distance-based belief change can help in refining simple causal models such as the example in this paper. Future work will include larger state-action spaces, better distance measures and strategies for choosing actions.

Kinzang Chhogyal

2012-09-01

90

Water Density Fluctuations Relevant to Hydrophobic Hydration are Unaltered by Attractions  

CERN Document Server

An understanding of density fluctuations in bulk water has made significant contributions to our understanding of the hydration and interactions of idealized, purely repulsive hydrophobic solutes. To similarly inform the hydration of realistic hydrophobic solutes that have dispersive interactions with water, here we characterize water density fluctuations in the presence of attractive fields that correspond to solute-water attractions. We find that when the attractive field acts only in the solute hydration shell, but not in the solute core, it does not significantly alter water density fluctuations in the solute core region. We further find that for a wide range of solute sizes and attraction strengths, the free energetics of turning on the attractive fields in bulk water are accurately captured by linear response theory. Our results also suggest strategies for more efficiently estimating hydration free energies of realistic solutes in bulk water and at interfaces.

Remsing, Richard C

2014-01-01

91

Geostatistical analysis of spatiotemporal variability of groundwater level fluctuations in Amman-Zarqa basin, Jordan: a case study  

Science.gov (United States)

The main objective of this study was to assess the spatial and temporal variability of groundwater level fluctuations in the Amman-Zarqa basin, during the period 2001-2005. In the year 2003, as a consequence of war, there was a sudden increase in the population in this basin. Knowing that the basin is already heavily populated and witnesses most of the human and industrial activities in Jordan, this study was prompted to help make wise water resources management decisions to cope with the new situation. Data from 31 fairly distributed wells in the upper aquifer of the basin were subjected to geostatistical treatment. Kriging interpolation techniques have indicated that the groundwater flow directions remained almost constant over the years. The two main directions are SW-NE and E-W. Kriging mapped fluctuations have also showed that drop and rise events are localized in the basin. Forecasting possibilities for management purposes were tackled using autocorrelation analysis. The constructed autocorrelograms indicated, in general, the temporal dependence of seasonal water level fluctuations, and that forecasting can be carried out within a period of 3-21 months. Several suggestions were made to mitigate the drop and rise hazards in the detected sites.

Ta?Any, Rakad A.; Tahboub, Alaeddin B.; Saffarini, Ghazi A.

2009-04-01

92

Characterization of the level fluctuations in a physical model of the steel continuous casting mold through image processing  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in english In this work is characterized the periodic behavior of the liquid level inside a scaled cold-model of the mold section of a steel continuous casting machine, which uses water as working fluid. The models are designed in order to simulate the dynamic forces acting on the molten steel inside a mold of [...] continuous casting. The force magnitude can induce choppy flow, waves and vortex formation in the mold. The experimental model uses a closed-loop hydraulic configuration. In the mold, the inlet and the outlet water flow rates are the same. This configuration resembles a perfect control of the liquid level inside the water model. A high-speed video camera was used to get several video clips of the movement of the water level profile. Several techniques were tested in order to obtain the best lighting conditions for recording the water movement. The edge-detection technique of Sobel was used to determine the profile of the liquid level in each one of the images recorded. The analysis of the dynamic behavior of the water profile showed that the fluctuations of the liquid level inside the mold have a complex structure, which is repeated over large time periods.

J.R., Miranda-Tello; F., Sánchez-Rangel; C.A., Real-Ramírez; G., Khatchatourov; J.A., Aragón-Lezama; L.F., Hoyos-Reyes; E.A., Andrade-González; J.I., González-Trejo.

2012-04-01

93

Characterization of the level fluctuations in a physical model of the steel continuous casting mold through image processing  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in english In this work is characterized the periodic behavior of the liquid level inside a scaled cold-model of the mold section of a steel continuous casting machine, which uses water as working fluid. The models are designed in order to simulate the dynamic forces acting on the molten steel inside a mold of [...] continuous casting. The force magnitude can induce choppy flow, waves and vortex formation in the mold. The experimental model uses a closed-loop hydraulic configuration. In the mold, the inlet and the outlet water flow rates are the same. This configuration resembles a perfect control of the liquid level inside the water model. A high-speed video camera was used to get several video clips of the movement of the water level profile. Several techniques were tested in order to obtain the best lighting conditions for recording the water movement. The edge-detection technique of Sobel was used to determine the profile of the liquid level in each one of the images recorded. The analysis of the dynamic behavior of the water profile showed that the fluctuations of the liquid level inside the mold have a complex structure, which is repeated over large time periods.

J.R., Miranda-Tello; F., Sánchez-Rangel; C.A., Real-Ramírez; G., Khatchatourov; J.A., Aragón-Lezama; L.F., Hoyos-Reyes; E.A., Andrade-González; J.I., González-Trejo.

94

Photosynthetic responses of Lupinus albus to soil water fluctuations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Lupinus albus plants were grown in 3 dm3 pots in a semi-controled greenhouse. Two water regimes were imposed: water deficit (S, 47% of soil capacity), and control (T, 86% of soil capacity). Plants water status was monitored through foliar relative water content (TRA) and pre-dawn (ypd) and midday water potential (ymd). Gas exchanges, chlorophyll a fluorescence and photosynthetic capacity (Amax) were measured. Pigments and soluble protein were quantified and antioxidant system enzy...

Barrote, Isabel; Oso?rio, Maria Leonor; Oso?rio, Ju?lio; David, Maria Manuela; Correia, Maria Joa?o

2002-01-01

95

Do fluctuations in endogenous melatonin levels predict the occurrence of postoperative cognitive dysfunction (POCD)?  

Science.gov (United States)

Delirium is a complex neuropsychiatric disorder that has an adverse impact on CNS function. Abnormal fluctuation of melatonin secretion occurs in the postoperative delirium (POD) in elderly patients. POD is strongly associated with early postoperative cognitive dysfunction (POCD). The aim of this study is to test if significant fluctuation of melatonin secretion perioperatively might indicates POCD. A total of 97 patients, ages 65-80 years, scheduled for major orthopedic surgery or abdominal surgery which was expected to last more than 2 h, were consecutively recruited into this study. Neuropsychological evaluation was performed 1 d before and one week after surgery. Morning urine samples were collected on the day of surgery and on days 1, 2 and 7 after surgery. The 6-SMT/creatinine ratio (M/C ratio) was employed to give an objective estimate of urine 6-SMT concentration. Ultimately, 95 patients completed assessments and were included in the analysis. POCD was found in 30 patients (31.6%) at 1 week after operation. There was significant fluctuation in urinary 6-SMT in 39 of the 95 patients (as evidenced by urinary 6-SMT levels increased or decreased by more than twofold compared with their preoperative baseline). Fluctuations in 6-SMT levels occurred on different days and in some patients lasted for more than 1 d. The incidence of POCD in patients with 6-SMT fluctuation was significantly higher (p < 0.01). The results indicate that in the first week after major noncardiac surgery, POCD occurs in a significant proportion of people, and is linked to fluctuations in endogenous melatonin levels. Measurement of urinary 6-SMT during the perioperative period may assist the diagnosis of POCD. PMID:24417656

Wu, Yan; Wang, Jiawan; Wu, AnShi; Yue, Yun

2014-11-01

96

Reactor water level control device  

International Nuclear Information System (INIS)

Purpose: To avoid the generation of abnormal impulse noises upon switching between single factor control for the detection of reactor water level and three factor control for the detection of reactor water level, feedwater rate and main steam rate. Constitution: Switching circuit has a contact actuated in response to the operation of a control system turning switch. The contact is opened for the single factor control and closed for the three factor control. Values for the detected main steam flow rate and feedwater flow rate are connected by way of a second adder and a coefficient multiplier to the input of the switching circuit to thereby input the deviation as a correction signal. While on the other hand, the output of the switching circuit is connected to the input of a third adder. A set value for the feedwater flow rate and a detection signal are connected by way of a first adder to the input of the above adder. This causes the deviation signal in the reactor water level to be inputted directly with no effects from the switching circuit. The output of the adder is inputted directly to a PI adjusting circuit having proportionating and integrating functions. (Kawakami, Y.)

97

The role of quantum effects on structural and electronic fluctuations in neat and charged water.  

Science.gov (United States)

In this work, we revisit the role of nuclear quantum effects on the structural and electronic properties of the excess proton in bulk liquid water using advanced molecular dynamics techniques. The hydronium ion is known to be a weak acceptor of a hydrogen bond which gives it some hydrophobic character. Quantum effects reduce the degree of this hydrophobicity which facilitates the fluctuations of the protons along the wires compared to the classical proton. Although the Eigen and Zundel species still appear to be dominant motifs, quantum fluctuations result in rather drastic events where both transient autoionization and delocalization over extended proton wires can simultaneously occur. These wild fluctuations also result in a significant change of the electronic properties of the system such as the broadening of the electronic density of states. An analysis of the Wannier functions indicate that quantum fluctuations of neat water molecules result in transient charging with subtle similarities and differences to that of the excess proton. PMID:25286281

Giberti, Federico; Hassanali, Ali A; Ceriotti, Michele; Parrinello, Michele

2014-11-20

98

Chemically-Driven Two Level Fluctuations in Single-Walled Carbon Nanotubes (SWCNTs) with Defects  

Science.gov (United States)

When a SWCNT conductor contains a defect, its electronic fluctuations are sensitive indicators of the surrounding chemical environment and of the chemical state of the defect itself. We demonstrate this effect by fabricating single SWCNT devices and then engineering their defect condition through the method of electrochemical point-functionalization. By characterizing the same SWCNT before and after the introduction of a point defect, we clearly establish the defect's contribution to the overall device noise. Carboxylate defects are particularly interesting because they have a deprotonated state that is sensitive to pH, electrolyte, and electrochemical potential. Large amplitude, two level fluctuations are observed from carboxylate sites when probed under conditions near the dissociation constant pKa, and the occupation statistics can be reversibly tuned by either pH or potential. We interpret the fluctuation in terms of the controlled protonation and deprotonation of the defect site, and describe a simple electrostatic gating model that supports this conclusion.

Wan, Danny; Hunt, Steven R.; Corso, Brad L.; Moody, Issa S.; Weiss, Gregory A.; Collins, Philip G.

2011-03-01

99

Fluctuation effects in the water-in-oil microemulsion systems near percolation threshold  

Energy Technology Data Exchange (ETDEWEB)

The fluctuation phenomena near the percolation line in microemulsion systems of decane-water-anionic surfactant kind are investigated. To describe their specificity, the Landau-Ginzburg approach and the method of frequency moments are applied. The explanation of experimental results on molecular light scattering is given on this basis. The behaviour of the dielectric permeability near the percolation line is discussed in detail. The influence of critical fluctuations on the disposition of percolation line is considered.

Fisenko, A.I.; Malomuzh, N.P. [Odessa Univ. (Ukraine). Dept. of Theoretical Physics; Magazu`, S.; Maisano, G. [Messina Univ. (Italy). Dipt. di Fisica

1998-05-01

100

The effect of pressurizer-water-level on the low frequency component of the pressure spectrum in a PWR  

International Nuclear Information System (INIS)

The pressure fluctuations were measured in the cooling system of the Paks-1 reactor. A shift of the peak was detected in low frequency component of the pressure fluctuation spectrum which is due to the fluctuations of water level in the pressurizer. Using the model of Katona and Nagy (1983), the eigenfrequencies, the magnitude of the shift and the sensitivity to the pressurizer water level were reproduced in good accordance with the experimental data. (D.Gy.)

 
 
 
 
101

Barometric pressure influence on water table fluctuations in coastal aquifers of partially enclosed seas: An example from the Adriatic coast, Italy  

Science.gov (United States)

SummaryThe water table level fluctuations in a coastal phreatic aquifer of the Adriatic coast (southern Po Plain - Italy) were recorded to characterize groundwater level response to sea level fluctuations. Tide-induced fluctuations, atmospheric pressure loading and recharge from rainfall have all been recognized in the measured water table changes. We also identified additional water table fluctuations that are not related to rain, atmospheric pressure or tides. We propose that these additional fluctuations are related to interaction of groundwater, seiche events and 'inverted barometric effects'. Their amplitude is important, because at a distance of 70 m from the coast they have a magnitude of 0.07 m, whereas the local tide has a 1 m amplitude. Seiches are standing waves that create sea water fluxes which affect groundwater below the first row of dunes in the study area. We propose that this 'inverted barometric effect' is an important process in creating water fluxes in the coastal zone that may strongly affect the position and width of the mixing zone between salt and fresh water.

Balugani, Enrico; Antonellini, Marco

2011-03-01

102

Solute Transport Under Water Table Fluctuations in a Fine Sand and a Sandy Clay Loam Soil  

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Full Text Available Drainage contributes to removing the excess of water from cultivated land. In general, most common drainage systems lead to loss of fertilizers applied for plant growth and yield improvement. Thus, the main objective of this work was to study experimentally the redistribution of solutes within the soil profile caused by water table fluctuations by making use of a non-reactive tracer in laboratory studies on soil columns. Two soil materials, namely fine sand and a sandy clay loam soil, were used in this study. Use was made of potassium chloride as a non-reactive tracer. Profiles of chloride redistribution as a function of depth caused by a first drainage of a saturated column with chloride in the surface layer, sub-irrigation and a second drainage were obtained for the fine sand columns with draining water levels at depths 25.5 and 44.5 cm, and for the sandy clay loam columns with a draining water level at depth 44.5 cm. Although only results for water table depth at 44.5 cm for both soils materials are presented. The redistribution of chloride in both the fine sand and the sandy clay loam columns was dominantly attributed to convective movement of solutes and was considered to be little influenced by diffusion. Preferential flow could have taken place through large sized pores of the fine sand columns. The knowledge and data of this study is a contribution towards that needed to define operation strategies for sub-irrigation-drainage systems which can lead to optimize fertilizers use by crops.

Cesáreo Landeros-Sánchez

2013-12-01

103

Changes in climate, catchment vegetation and hydrogeology as the causes of dramatic lake-level fluctuations in the Kurtna Lake District, NE Estonia  

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Full Text Available Numerous lakes in the world serve as sensitive indicators of climate change. Water levels for lakes Ahnejärv and Martiska, two vulnerable oligotrophic closed-basin lakes on sandy plains in northeastern Estonia, fell more than 3 m in 1946–1987 and rose up to 2 m by 2009. Earlier studies indicated that changes in rates of groundwater abstraction were primarily responsible for the changes, but scientifically sound explanations for water-level fluctuations were still lacking. Despite the inconsistent water-level dataset, we were able to assess the importance of changing climate, catchment vegetation and hydrogeology in water-level fluctuations in these lakes. Our results from water-balance simulations indicate that before the initiation of ground­water abstraction in 1972 a change in the vegetation composition on the catchments triggered the lake-level decrease. The water-level rise in 1990–2009 was caused, in addition to the reduction of groundwater abstraction rates, by increased precipitation and decreased evaporation. The results stress that climate, catchment vegetation and hydrogeology must all be considered while evaluating the causes of modern water-level changes in lakes.

Marko Vainu

2014-02-01

104

Lectures on Molecular- and Nano-scale Fluctuations in Water  

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This manuscript is the written form of three lectures delivered by David Chandler at the International School of Physics "Enrico Fermi", Course CLXXVI - "Complex materials in physics and biology", in Varenna, Italy in July 2010. It describes the physical properties of water from a molecular perspective and how these properties are reflected in the behaviors of water as a solvent. Theory of hydrophobicity and solvation of ions are topics included in the discussion.

Chandler, David; Varilly, Patrick

2011-01-01

105

Understanding connected surface-water/groundwater systems using Fourier analysis of daily and sub-daily head fluctuations  

Science.gov (United States)

The long-term monitoring records of hydraulic heads frequently contain fluctuations originating from different cyclic drivers. Fourier analysis applied to these records can reveal connected surface-water/groundwater system characteristics. The various components of the atmospheric tides, the earth tides and the presence of diurnal responses to evapotranspiration are identified and isolated through band-pass filtering of data recorded from both vented and absolute gauge transducers. The signature of the different cyclic drivers is contained in amplitude and phase of the various signal components and can be used to determine the degree of system confinement. A methodology is described for the calculation of barometric efficiency in confined aquifers based upon the amplitude of the M2 and S2 components of the earth and atmospheric tides. It is demonstrated that Fourier analysis of water-level fluctuations is a simple but underused tool that can help to characterise shallow groundwater systems.

Acworth, R. I.; Rau, Gabriel C.; McCallum, Andrew M.; Andersen, Martin S.; Cuthbert, Mark O.

2014-09-01

106

Calculated yields and fluctuations for electron degradation in liquid water and water vapor  

International Nuclear Information System (INIS)

Two sets of physical interaction cross sections for detailed electron track-structure calculations in liquid water and water vapor have been used to investigate the possible magnitude of phase-dependent differences in the primary yields of ionizations and their fluctuations produced during complete slowing down of electrons in the energy range from 10 eV to 10 keV. For fast electrons the calculated values of the mean energy absorbed per ion pair are 25.8 eV/ip for the liquid as compared to 30.0 eV/ip for the vapor; both results are consistent with experimental data. A similar phase effect is found in the ionization yields from each molecular subshell, since essentially the same partitioning of the total ionization cross section has been used in the calculations for the liquid and the vapor. The relative fluctuations of the ionization yields as described by the Fano factor are 0.15 for the liquid and 0.25 for the vapor; the Fano factors for each single molecular orbital are typically between 0.7 and 0.9 in both phases. The distributions in the total number of ionizations produced by the complete slowing down of electrons with initial energies above about 100 eV are Gaussian within about two standard deviations around the mean. The significance of the differences in the yields of ionizations and excitations calculated for both phases is discussed. In the absence of adequate experimental data for the basic processes, the differences are interpreted in terms of the respecces are interpreted in terms of the respective assumptions made for single scattering processes

107

Interannual lake level fluctuations (1993 1999) in Africa from Topex/Poseidon: connections with ocean atmosphere interactions over the Indian Ocean  

Science.gov (United States)

Water level fluctuations of continental lakes are related to regional to global scale climate changes. Water level fluctuations reflect variations in evaporation and precipitation over the lake area and its catchment area. Over such inland water bodies, the satellite altimetry technique offers both a world-wide coverage and a satisfying accuracy. We present here results of lake level variations of 12 African lakes based on 7 years of Topex/Poseidon (T/P) altimetry data acquired between 1993 and 1999. Among the 12 African lakes presented in this study, three are reservoirs whose level fluctuations are mainly driven by anthropogenic usage of the water. Either closed or open, the nine remaining lakes are sensitive indicators of the climate evolution over Africa during the 1990s. Seasonal signals of each lake are clearly identified and filtered out to focus on the interannual fluctuations. Clear correlated regional variations are reported among the east African lakes: several lakes exhibit a regular level decrease between 1993 and 1997, probably due to intense droughts. However, the most spectacular feature is an abrupt water level rise occurring in late 1997-early 1998 and affecting most of the lakes located within the Rift Valley. This major anomalous pattern, explained by a large excess rainfall anomaly occurring in late 1997, is quantified in both space and time domains through an EOF analysis of the lake level height time series. The spatial distribution of the leading mode of lake level height correlates with the dominant mode of precipitation computed over the same time span. Nevertheless, similar rainfall anomaly, but with lesser intensity, occurred in late 1994 without any noticeable consequence on lake level. The precipitation anomaly appears related to the equatorial Indian Ocean warming reported during the 1997-1998 ENSO event.

Mercier, Franck; Cazenave, Anny; Maheu, Caroline

2002-04-01

108

Fluctuations in serum magnesium levels during total intravenous anaesthesia with propofol.  

Science.gov (United States)

Forty patients who underwent eye surgery under total intravenous anaesthesia with propofol where investigated in order to determine the fluctuations of serum magnesium levels during anaesthesia. Six blood samples were taken before anaesthesia, after induction, 1 hour later, 2 hours later, after recovery, and 24 hours after surgery. In the same time intervals, systolic and diastolic blood pressure, heart rate and temperature were recorded. The results showed a statistically significant decrease in serum magnesium levels during anaesthesia. No correlations between this decrease and the fluctuations of blood pressure, heart rate or temperature were found. These results indicate that there is a shift of magnesium into the tissue stores due to the state of anaesthesia, possibly by a direct effect of the anaesthetic agents on the cell membrane itself. Further investigation is needed with other techniques and agents employed in general anaesthesia. PMID:8819094

Nastou, H; Sarros, G; Palta, M; Nastos, A; Sarrou, V; Anastassopoulou, J

1996-03-01

109

Large decrease of fluctuations for supercooled water in hydrophobic nanoconfinement  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study by Monte Carlo simulations a coarse-grained model of a water layer confined in a fixed disordered matrix of hydrophobic nanoparticles at different particle concentrations c. For c=0 (bulk water) we find a first order liquid-liquid phase transition (LLPT). For c>0 our simulations are consistent with a LLPT line ending in two critical points at low and high pressure P. For c=25% we find a dramatic decrease of compressibility K_T, thermal expansion coefficient \\alpha_P...

Strekalova, Elena G.; Mazza, Marco G.; Stanley, H. Eugene; Franzese, Giancarlo

2010-01-01

110

Analysis on the characteristics of parameters in groundwater table fluctuation model for predicting groundwater levels in Hancheon watershed, South Korea  

Science.gov (United States)

A novel application of groundwater table fluctuation method is suggested to predict groundwater level by means of groundwater table variation due to recharge and discharge under unsteady condition. This model analyzes transient groundwater characteristics by using reaction factor related with groundwater flow and specific yield related with recharge. The groundwater level varies according to the characteristics and composite materials of aquifer. In this study, specific yield and reaction factor which are the major two hydrogeological parameters in the WTF(Water Table Fluctuation) method were estimated and analyzed their spatial characteristics. 8 groundwater level stations which have enough measuring period and high correlation with rainfall in the Hancheon watershed were used. The results showed that specific yield was randomly distributed and reaction factor showed inverse trend with altitude. If the enough data were collected, reaction factor according to altitude in ungauged points could be estimated by using these parameter characteristics. keywords: Key words : Groundwater level, parameters, reaction factor, specific yield Acknowledgements This research was supported by the Regional Innovative Technology Project 2B from KICTTEP.

Kim, Nam Won; Kim, Youn Jung; Chung, Il-Moon; Lee, Jeongwoo

2014-05-01

111

An analysis of fluctuations in supercooled TIP4P/2005 water  

Science.gov (United States)

Large-scale, long-time molecular dynamics simulations are used to investigate fluctuations in the TIP4P/2005 water model in the supercooled region (240-190 K). Particular attention is focused in the vicinity of a previously reported liquid-liquid critical point [J. L. F. Abascal and C. Vega, J. Chem. Phys. 133, 234502 (2010)]. Water is viewed as an equimolar binary mixture with ``species'' defined based on a local tetrahedral order parameter. A Bhatia-Thornton fluctuation analysis is used to show that species concentration fluctuations couple to density fluctuations and completely account for the anomalous increase in the structure factor at small wave number observed under supercooled conditions. Although we find that both concentration and density fluctuations increase with decreasing temperature along the proposed critical isochore, we cannot confirm the existence of a liquid-liquid critical point. Our simulations suggest that the parameters previously reported are not a true liquid-liquid critical point and we find no evidence of two-phase coexistence in its vicinity. It is shown that very long simulations (on the order of 8 ?s for 500 molecules) are necessary to obtain well converged density distributions for deeply supercooled water and this is especially important if one is seeking direct evidence of a two-phase region.

Overduin, S. D.; Patey, G. N.

2013-05-01

112

An analysis of fluctuations in supercooled TIP4P/2005 water.  

Science.gov (United States)

Large-scale, long-time molecular dynamics simulations are used to investigate fluctuations in the TIP4P/2005 water model in the supercooled region (240-190 K). Particular attention is focused in the vicinity of a previously reported liquid-liquid critical point [J. L. F. Abascal and C. Vega, J. Chem. Phys. 133, 234502 (2010)]. Water is viewed as an equimolar binary mixture with "species" defined based on a local tetrahedral order parameter. A Bhatia-Thornton fluctuation analysis is used to show that species concentration fluctuations couple to density fluctuations and completely account for the anomalous increase in the structure factor at small wave number observed under supercooled conditions. Although we find that both concentration and density fluctuations increase with decreasing temperature along the proposed critical isochore, we cannot confirm the existence of a liquid-liquid critical point. Our simulations suggest that the parameters previously reported are not a true liquid-liquid critical point and we find no evidence of two-phase coexistence in its vicinity. It is shown that very long simulations (on the order of 8 ?s for 500 molecules) are necessary to obtain well converged density distributions for deeply supercooled water and this is especially important if one is seeking direct evidence of a two-phase region. PMID:23676051

Overduin, S D; Patey, G N

2013-05-14

113

Water Table Fluctuation in Tidal Lowland for Developing Agricultural Water Management Strategies  

Directory of Open Access Journals (Sweden)

Full Text Available The research objective is to evaluate the water status in the tertiary block of tidal lowland for developing water management strategies and cropping pattern for food crop agriculture. The research was conducted in tidal lowland reclamation areas of Delta Saleh South Sumatera. The methodology used in this research was survey and monitoring. The result showed that the study area has a potential of acid sulphate soil which is indicated by phyrite layer at 60 cm below the soil surface. Variation of water table was very high in the range of 0-2 cm at rainy season and it was drop up to 90 to 100 cm below soil surface at dry season. This conditions result in the soil oxidation and the pH drop up to 2.5-3.5 (very acid. Analysis of water surplus and deficit during one year period was calculated by surplus excess water under 30 cm (SEW-30 and showed that the area study was experienced water deficit. Analysis of groundwater effect on soil moisture content showed that the critical water level was in 60 cm below soil surface. The soil moisture content at this point in the root zone was dropped into the wilting point level. It means that the water availability for crop water requirement is inadequate. For sustainable agriculture in the area study, the water table should be maintained in 50-60 cm below soil surface. Therefore, the recommendation of water management strategies in the study area is water retention in combination with control drainage system.

Momon Sodik Imanudin

2010-09-01

114

Does temperature affect the accuracy of vented pressure transducer in fine-scale water level measurement?  

Science.gov (United States)

Submersible pressure transducers have been utilized for collecting water level data since early 1960s. Together with a digital datalogger, it is a convenient way to record water level fluctuations for long-term monitoring. Despite the widely use of pressure transducers for water level monitoring, little has been reported for their accuracy and performance under field conditions. The effect of temperature fluctuations on the output of vented pressure transducers were discussed in this study. The pressure transducer was tested under both laboratory and field conditions. The results of this study indicate that temperature fluctuation has a strong effect on the transducer output. Rapid changes in temperature introduce noise and fluctuations in the water level readings under a constant hydraulic head while the absolute temperature is also related to sensor errors. The former is attributed to venting and the latter is attributed to temperature compensation effect in the strain gauges. Individual pressure transducers responded differently to the thermal fluctuations in the same testing environment. In the field of surface hydrology, especially when monitoring fine-scale water level fluctuations, ignoring or failing to compensate for the temperature effect can introduce considerable error into pressure transducer readings. It is recommended that a performance test for the pressure transducer is conducted before field deployment.

Liu, Z.; Higgins, C. W.

2014-09-01

115

Water-table fluctuations in the Amargosa Desert, Nye County, Nevada  

Energy Technology Data Exchange (ETDEWEB)

Pleistocene ground-water discharge deposits approximately 20 km southwest of Yucca Mountain were previously thought to represent pluvial water-table rises of 80 to 120 m. Data from new boreholes at two of the three discharge sites indicate that the modern water-table is at depths of only 17 to 30 m and that this shallow water is part of the regional ground-water flow system rather than being perched. Calcite in equilibrium with this modern ground water would have isotopic compositions similar to those in Pleistocene calcite associated with the discharge deposits. Carbon and uranium isotopes in both ground water and discharge deposits imply that past discharge consisted of a mixture of both shallow and deep ground water. These data limit Pleistocene water-table fluctuations at the specified Amargosa Desert discharge sites to between 17 and 30 m and eliminate the need to invoke large water-table rises.

Paces, James B.; Whelan, Joseph

2001-04-29

116

Monitoring device for reactor water level  

International Nuclear Information System (INIS)

Purpose: To improve the reliability in the reactor water level monitoring by estimating the reactor water level in an abnormal transient state and thereby forecast the water level response in a BWR type nuclear power plant. Constitution: Main process parameters (main steam flow rate, feedwater flow rate, reactor water level and reactor pressure) for a nuclear power plant are taken into an input device. An estimation device for actual reactor water level estimates an actual reactor water level based on these parameter data. If the detection range for a reactor water level detector is exceeded, it is judged by a judging device for reactor water level indication and the estimated value is employed for the monitoring of the reactor water level. The output from an estimation device for actual water level variation coefficient and an estimation value for actual reactor water level variation coefficient prepared by integrating the above output with time are inputted into a forecasting calculator for reactor water level response and the calculator outputs a forecast value for reactor water level response as a time function. (Seki, T.)

117

Long-time correlations of sea-level and local atmospheric pressure fluctuations at Trieste  

Science.gov (United States)

A random walk analysis of pressure and sea-level fluctuations from daily data taken at Trieste during the period 1939-2002 is presented. It is shown that the associated time series display long-time autocorrelations up to time scales of several thousand of days, characterized by a Hurst exponent H?0.70 for sea-level and H?0.58 for pressure. The corresponding probability distribution functions depart from the Gaussian shape, displaying asymmetric tails. The series are found to be cross-correlated with a cross-correlation coefficient of about -0.76.

Beretta, Alessandro; Roman, H. Eduardo; Raicich, Fabio; Crisciani, Fulvio

2005-03-01

118

Time-Reversal Symmetry and Universal Conductance Fluctuations in a Driven Two-Level System  

CERN Document Server

In the presence of time-reversal symmetry, quantum interference gives strong corrections to the electric conductivity of disordered systems. The self-interference of an electron wavefunction traveling time-reversed paths leads to effects such as weak localization and universal conductance fluctuations. Here, we investigate the effects of broken time-reversal symmetry in a driven artificial two-level system. Using a superconducting flux qubit, we implement scattering events as multiple Landau-Zener transitions by driving the qubit periodically back and forth through an avoided crossing. Interference between different qubit trajectories give rise to a speckle pattern in the qubit transition rate, similar to the interference patterns created when coherent light is scattered off a disordered potential. Since the scattering events are imposed by the driving protocol, we can control the time-reversal symmetry of the system by making the drive waveform symmetric or asymmetric in time. We find that the fluctuations o...

Gustavsson, Simon; Oliver, William D

2012-01-01

119

Reconstructing the structure and dynamics of density fluctuations in water near a moving proton  

Science.gov (United States)

The structure and dynamics of water on femtosecond timescales is relevant to many topics in physical chemistry such as ion solvation. We computationally reconstruct the angstrom-scale spatial and femtosecond-scale temporal evolution of density fluctuations in water using high-resolution inelastic x-ray scattering (IXS). The imaginary part of density propagator ?(q,?) is directly extracted from the IXS data, and the real part recovered using Kramers-Kronig relations. The resultant complex-valued ?(q,?) is the Fourier transform of the real-space density-density response function ?(r,t) which measures the dynamical density fluctuations of water due to a point-like instantaneous pulse. We use this density propagator from IXS data and linear-response theory to reconstruct the hydration behavior of a proton moving at different speeds through water.

Coridan, Robert; Hwee Lai, Ghee; Schmidt, Nathan; Abbamonte, Peter; Wong, Gerard C. L.

2008-03-01

120

The effect of interaural-level-difference fluctuations on the externalization of sound  

DEFF Research Database (Denmark)

Real-world sound sources are usually perceived as externalized and thus properly localized in both direction and distance. This is largely due to (1) the acoustic filtering by the head, torso, and pinna, resulting in modifications of the signal spectrum and thereby a frequency-dependent shaping of interaural cues and (2) interaural cues provided by the reverberation inside an enclosed space. This study first investigated the effect of room reverberation on the spectro-temporal behavior of interaural level differences (ILDs) by analyzing dummy-head recordings of speech played at different distances in a standard listening room. Next, the effect of ILD fluctuations on the degree of externalization was investigated in a psychoacoustic experiment performed in the same listening room. Individual binaural impulse responses were used to simulate a distant sound source delivered via headphones. The ILDs were altered using a gammatone filterbank for analysis and resynthesis, where the envelopes of the left and right-ear signals were modified such that the naturally occurring fluctuations of the ILDs were restricted. This manipulation reduced the perceived degree of externalization. This was consistent with the analysis of short-term ILDs at different distances showing that a decreased distance to the sound source also reduced the ILD fluctuations. © 2013 Acoustical Society of America.

Catic, Jasmina; Santurette, Sébastien

2013-01-01

 
 
 
 
121

Time-Reversal Symmetry and Universal Conductance Fluctuations in a Driven Two-Level System  

Science.gov (United States)

In the presence of time-reversal symmetry, quantum interference gives strong corrections to the electric conductivity of disordered systems. The self-interference of an electron wave function traveling time-reversed paths leads to effects such as weak localization and universal conductance fluctuations. Here, we investigate the effects of broken time-reversal symmetry in a driven artificial two-level system. Using a superconducting flux qubit, we implement scattering events as multiple Landau-Zener transitions by driving the qubit periodically back and forth through an avoided crossing. Interference between different qubit trajectories gives rise to a speckle pattern in the qubit transition rate, similar to the interference patterns created when coherent light is scattered off a disordered potential. Since the scattering events are imposed by the driving protocol, we can control the time-reversal symmetry of the system by making the drive waveform symmetric or asymmetric in time. We find that the fluctuations of the transition rate exhibit a sharp peak when the drive is time symmetric, similar to universal conductance fluctuations in electronic transport through mesoscopic systems.

Gustavsson, Simon; Bylander, Jonas; Oliver, William D.

2013-01-01

122

Small angle x-ray scattering study of fluctuations in 1-propanol-water and 2-propanol-water systems  

International Nuclear Information System (INIS)

Small-angle x-ray scattering (SAXS) measurements have been carried out on the 1-propanol (NPA)-water system and on the 2-propanol (IPA)-water system at 20 degree C. In the NPA-water system, the zero angle intensity, the concentration fluctuation, the Kirkwood-Buff parameters, and Debye's correlation lengths have been determined at various concentrations. In the IPA-water system, the zero angle intensity and Debye's correlation lengths have also been determined. In both the NPA-water and IPA-water systems, all obtained parameters have maxima at about 0.2 of the mole fraction of alcohol. In terms of these parameters, the mixing state of the NPA-water and IPA-water systems is discussed and compared with that of the TBA-water system

123

An Application of Low-Order Arma and Garch Models for Sea Level Fluctuations  

Science.gov (United States)

The paper presents the analysis of geographically-dependent irregular sea level fluctuations, often referred to as residual terms around deterministic signals, carried out by means of stochastic low-order autoregressive moving average (ARMA) and generalised autoregressive conditional heteroscedastic (GARCH) models. The gridded sea level anomaly (SLA) time series from TOPEX/Poseidon (T/P) and Jason-1 (J-1) satellite altimetry, commencing on 10th January 1993 and finishing on 14th July 2003, has been examined. The aforementioned models, limited to low-orders being combinations of 0,1 and 2, have been fitted to the SLA data. The root mean square and the Shapiro-Wilk test for the normal distribution have been used to calculate statistics of the residuals from these models. It has been found that autoregressive (AR) models as well as ARMA ones serve well the purpose of adequate modelling irregular sea level fluctuations, with a successful fit in some patchy bits of the equatorial Pacific. In contrast, GARCH models have been shown to be rather inaccurate, specifically in the vicinity of the tropical Pacific, in the North Pacific and in the equatorial Indian Ocean. The pattern of the Tropical Instability Waves (TIWs) has been noticed in the statistics of AR and ARMA model residuals indicating that the dynamics of these waves cannot be captured by the aforementioned linear stochastic processes.

Niedzielski, Tomasz; Kosek, Wieslaw

2010-01-01

124

Geochemical Changes in the Caspian Salt Marshes Due to the Sea Level Fluctuations  

Directory of Open Access Journals (Sweden)

Full Text Available The Caspian Sea is subject to alternating transgressions and regressions that exert a strong impact on the topography, sediments, vegetation, and soils in coastal zones. The last transgression of the Caspian Sea (1978-1995 caused the development of a marsh-lagoon system along the accumulative seashore of the Central Dagestan. Salt marshes are complex and dynamic systems highly vulnerable to sea level fluctuations; therefore, they may be considered as a regional model of rapid environmental changes. Hazards in coastal zones may critically change the soil geochemistry affecting agricultural potential of large areas. Assessments of risks of the natural hazards in coastal zones are extremely difficult unless the end-to-end understanding of all natural factors. The research in the Caspian region shows the impact of extreme events in the coastal zones. Detailed landscape-geochemical investigations of the Caspian salt marshes were carried out in 1995-1996 (during the final stage of the transgression period and in 2001-2003 (during the period of the sea level stabilization. These coastal areas are influenced by different landscape-geochemical processes, such as sulfidization, gleyzation, ferrugination, humus accumulation, halogenesis, and changes of alkali-acidic conditions. The development of the processes characterizes different stages of the Caspian Sea level fluctuations. This paper presents a discussion on stages and rates of landscape-geochemical processes, formation of geochemical barriers, and trace elements distribution in soils of the salt marshes.

Nicolay S. Kasimov

2012-05-01

125

Water level detector for BWR type reactor  

International Nuclear Information System (INIS)

Purpose: To accurately detect the water level of reactor irrespective of the reactor water flow velocity. Constitution: A total pressure detecting port is opened at the upstream side of the reactor water flowing direction in a BWR type reactor, and the water level is detected from the differential pressure between the total pressure detected at the total pressure detecting port and a reference head pressure. Or, a total pressure detecting port and a static pressure detecting port are provided, static and dynamic pressures are thus separately detected, converted into electric signals, corrected and added, a signal corresponding to the differential pressure between the total pressure and the reference head pressure is thus obtained, and the water level is detected with the signal. Accordingly, the water level can be accurately obtained regardless of the reactor water flow velocity, the dynamic pressure having a relatively large error can be corrected, and the water level can be detected more accurately. (Yoshihara, H.)

126

Attenuation of concentration fluctuations of water vapor and other trace gases in turbulent tube flow  

Directory of Open Access Journals (Sweden)

Full Text Available Recent studies with closed-path eddy covariance (EC systems have indicated that the attenuation of fluctuations of water vapor concentration is dependent upon ambient relative humidity, presumably due to sorption/desorption of water molecules at the interior surface of the tube. Previous studies of EC-related tube attenuation effects have either not considered this issue at all or have only examined it superficially. Nonetheless, the attenuation of water vapor fluctuations is clearly much greater than might be expected from a passive tracer in turbulent tube flow. This study reexamines the turbulent tube flow issue for both passive and sorbing tracers with the intent of developing a physically-based semi-empirical model that describes the attenuation associated with water vapor fluctuations. Toward this end, we develop a new model of tube flow dynamics (radial profiles of the turbulent diffusivity and tube airstream velocity. We compare our new passive-tracer formulation with previous formulations in a systematic and unified way in order to assess how sensitive the passive-tracer results depend on fundamental modeling assumptions. We extend the passive tracer model to the vapor sorption/desorption case by formulating the model's wall boundary condition in terms of a physically-based semi-empirical model of the sorption/desorption vapor fluxes. Finally we synthesize all modeling and observational results into a single analytical expression that captures the effects of the mean ambient humidity and tube flow (Reynolds number on tube attenuation.

W. J. Massman

2008-05-01

127

Attenuation of concentration fluctuations of water vapor and other trace gases in turbulent tube flow  

Directory of Open Access Journals (Sweden)

Full Text Available Recent studies with closed-path eddy covariance (EC systems have indicated that the attenuation of fluctuations of water vapor concentration is dependent upon ambient relative humidity, presumably due to sorption/desorption of water molecules at the interior surface of the tube. Previous studies of EC-related tube attenuation effects have either not considered this issue at all or have only examined it superficially. Nonetheless, the attenuation of water vapor fluctuations is clearly much greater than might be expected from a passive tracer in turbulent tube flow. This study reexamines the turbulent tube flow issue for both passive and sorbing tracers with the intent of developing a physically-based semi-empirical model that describes the attenuation associated with water vapor fluctuations. Toward this end, we develop a new model of tube flow dynamics (radial profiles of the turbulent diffusivity and tube airstream velocity. We compare our new passive-tracer formulation with previous formulations in a systematic and unified way in order to assess how sensitive the passive-tracer results depend on fundamental modeling assumptions. We extend the passive tracer model to the vapor sorption/desorption case by formulating the model's wall boundary condition in terms of a physically-based semi-empirical model of the sorption/desorption vapor fluxes. Finally we synthesize all modeling and observational results into a single analytical expression that captures the effects of the mean ambient humidity and tube flow (Reynolds number on tube attenuation.

W. J. Massman

2008-10-01

128

Attenuation of concentration fluctuations of water vapor and other trace gases in turbulent tube flow  

DEFF Research Database (Denmark)

Recent studies with closed-path eddy covariance (EC) systems have indicated that the attenuation of fluctuations of water vapor concentration is dependent upon ambient relative humidity, presumably due to sorption/desorption of water molecules at the interior surface of the tube. Previous studies of EC-related tube attenuation effects have either not considered this issue at all or have only examined it superficially. Nonetheless, the attenuation of water vapor fluctuations is clearly much greater than might be expected from a passive tracer in turbulent tube flow. This study reexamines the turbulent tube flow issue for both passive and sorbing tracers with the intent of developing a physically-based semi-empirical model that describes the attenuation associated with water vapor fluctuations. Toward this end, we develop a new model of tube flow dynamics (radial profiles of the turbulent diffusivity and tube airstream velocity). We compare our new passive-tracer formulation with previous formulations in a systematic and unified way in order to assess how sensitive the passive-tracer results depend on fundamental modeling assumptions. We extend the passive tracer model to the vapor sorption/desorption case by formulating the model's wall boundary condition in terms of a physically-based semi-empirical model of the sorption/desorption vapor fluxes. Finally we synthesize all modeling and observational results into a single analytical expression that captures the effects of the mean ambient humidity and tube flow (Reynolds number) on tube attenuation.

Ibrom, Andreas

2008-01-01

129

Water level indicator for nuclear reactor  

International Nuclear Information System (INIS)

Purpose: To correctly indicate the water level in a reactor under all operating conditions by correcting the apparent decrease in the indication of a wide range water level indicator due to flow rate in the reactor core and apparent variations in the indication of the wide range water level indicator due to subcooling of the feedwater. Constitution: The water level signal of a wide range water level indicator is corrected in accordance with a flow rate correction signal and a subcooling correction signal by a water level deviation correcting adder, so the water level indicator will thus produce an actual water level signal, preferably matched with the indication of a narrow range water level indicator, to a wide range corrected water level indicator. The flow rate correction signal is obtained as an output signal of a function generator to which a reactor core flow rate signal is input and which incorporates a reactor core flow rate correction function. Further, the subcooling correction signal is obtained as an output signal of a function generator to which the temperature difference signal of a pump inlet temperature signal and a main steam temperature signal are input, and which also incorporates a subcooling correction function. (Yoshino, Y.)

130

Terrestrial Waters and Sea Level Variations on Interannual Time Scale  

Science.gov (United States)

On decadal to multi-decadal time scales, thermal expansion of sea waters and land ice loss are the main contributors to sea level variations. However, modification of the terrestrial water cycle due to climate variability and direct anthropogenic forcing may also affect sea level. For the past decades, variations in land water storage and corresponding effects on sea level cannot be directly estimated from observations because these are almost non-existent at global continental scale. However, global hydrological models developed for atmospheric and climatic studies can be used for estimating total water storage. For the recent years (since mid-2002), terrestrial water storage change can be directly estimated from observations of the GRACE space gravimetry mission. In this study, we analyse the interannual variability of total land water storage, and investigate its contribution to mean sea level variability at interannual time scale. We consider three different periods that, each, depend on data availability: (1) GRACE era (2003-2009), (2) 1993-2003 and (3) 1955-1995. For the GRACE era (period 1), change in land water storage is estimated using different GRACE products over the 33 largest river basins worldwide. For periods 2 and 3, we use outputs from the ISBA-TRIP (Interactions between Soil, Biosphere, and Atmosphere-Total Runoff Integrating Pathways) global hydrological model. For each time span, we compare change in land water storage (expressed in sea level equivalent) to observed mean sea level, either from satellite altimetry (periods 1 and 2) or tide gauge records (period 3). For each data set and each time span, a trend has been removed as we focus on the interannual variability. We show that whatever the period considered, interannual variability of the mean sea level is essentially explained by interannual fluctuations in land water storage, with the largest contributions arising from tropical river basins.

Llovel, W.; Becker, M.; Cazenave, A.; Jevrejeva, S.; Alkama, R.; Decharme, B.; Douville, H.; Ablain, M.; Beckley, B.

2011-01-01

131

The palaeo-lake Suguta and its importance for understanding lake level fluctuations in the East African Rift System  

Science.gov (United States)

We studied the most recent dry-wet-dry cycle in the presently arid Suguta Valley in the Northern Kenya Rift where a 300-m-deep lake has formed during the so-called African Humid Period (AHP, 14.8-5.5 ka BP). Hydromodeling suggests that a relatively moderate 25% increase in precipitation was responsible for this dramatic lake level rise, which demonstrates the character of the Suguta Valley as an amplifier lake system. To detect the response of this lake system to climate fluctuations and their possible driving mechanisms with a focus on abrupt vs. gradual changes, we reconstructed a palaeo-lake level record for the time between 14 and 5 ka BP from up to 40 m thick lake-sediment sequences at three locations in the ~2,500 km2 palaeo-lake Suguta area. The sediments have been investigated for sediment characteristics such as grain size distributions, detrital and authigenic mineral phases, geochemical properties and microfossil assemblages. The stratigraphy for the sequences is based on 38 AMS 14C ages of biogenic carbonate and charcoal samples. Parallel dating of charcoal and snail-shell samples show age differences between 1,570-2,240 years suggesting a remarkably high, but well-defined reservoir age for palaeo-Lake Suguta most likely due to aged groundwater or 14C depleted CO2 degassing from active volcanoes. The observed reservoir effect highlights the potential problems while correlating East African lake level records with chronologies based on 14C datings of aquatic materials. The new chronology of water level fluctuations in the amplifier-lake Suguta indicates a general dry-wet-dry cycle synchronous with other lake chronologies during the AHP and multiple short-term fluctuations with abrupt lake level drops between 100 to 300 m within 100 to 200 years at 12.8-11.6 (during Younger Dryas time), 11.1-10.9; 10.4-10.2; 9.5-9.1; 9.0-8.8; 8.5-8.1 (during the 8.2 ka event) cal ka BP that seem to be linked with changes in the coupling between atmosphere and ocean systems. In contrast, the termination of the overall lake episode during the AHP shows a relatively gradual (linear) response to the reduction of solar heating due to insolation changes. The results of the analysis provides new insights into the sensitivity of Rift Valley lakes to climate change on different time scales. Abrupt climate shifts most likely caused dramatic environmental pressure on the biosphere, including humans that were already able to adopt relatively quickly to environmnetal change by new technologies during this time.

Junginger, A.; Olago, D. O.; Trauth, M. H.

2010-12-01

132

Characterization of the temperature fluctuations generated in a thermal mixing tee (sodium versus water behavior)  

International Nuclear Information System (INIS)

The temperature fluctuations occurring in 1800 inlet-let angle pipe tee thermal mixers with and without inlet reducer pipes are characterized in both amplitude and frequency. Sodium and water data from different sized tees have allowed delineation of the size and fluid medium modeling laws required for the extrapolation of reduced-scale water model temperature fluctuation data to prototype LMFBR sodium mixers. The phenomena of flow corner cutoff and thermal buoyancy at a tee juncture have also been studied and their effects on mixer performance delineated. The information presented is vital both to the design of thermal-fatigue-free mixers and to the understanding of thermal mixing in complex flows; much of it has not been peviously available

133

On the Hofmeister effect: fluctuations at the protein-water interface and the surface tension.  

Science.gov (United States)

We performed molecular dynamics simulations on the tryptophane-cage miniprotein using a nonpolarizable force field, in order to model the effect of concentrated water solutions of neutral salts on protein conformation, which is a manifestation of Hofmeister effects. From the equilibrium values and the fluctuations of the solvent accessible surface area of the miniprotein, the salt-induced changes of the mean value of protein-water interfacial tension were determined. At 300 K, the chaotropic ClO4(-) and NO3(-) decreased the interfacial tension according to their position in the Hofmeister series (by approximately 5 and 2.7 mN/m, respectively), while the kosmotropic F(-) increased it (by 1 mN/m). These values were compared to those obtained from the Gibbs equation using the excess surface adsorption calculated from the probability distribution of the water molecules and ions around the miniprotein, and the two sets were found to be very close to each other. Our results present a direct evidence for the central role of interfacial tension and fluctuations at the protein-water interface in Hofmeister phenomena, and provide a computational method for the determination of the protein-water interfacial tension, establishing a link between the phenomenological and microscopic description of protein-water interfaces. PMID:24977301

Bogár, Ferenc; Bartha, Ferenc; Násztor, Zoltán; Fábián, László; Leitgeb, Balázs; Dér, András

2014-07-24

134

Kinetic parameters and intraindividual fluctuations of ochratoxin A plasma levels in humans  

International Nuclear Information System (INIS)

The mycotoxin ochratoxin A (OTA) is a rodent carcinogen produced by species of the ubiquitous fungal genera Aspergillus and Penicillium. OTA is found in a variety of food items and as a consequence is also found in human plasma (average concentrations found in this study: 0.1-1 ng OTA/ml plasma). To improve the scientific basis for cancer risk assessment the toxicokinetic profile of OTA was studied in one human volunteer following ingestion of 395 ng 3H-labeled OTA (3.8 ?Ci). A two-compartment open model consisting of a central compartment was found to best describe the in vivo data. This two-compartment model consisted of a fast elimination and distribution phase (T1/2 about 20 h) followed by a slow elimination phase (renal clearance about 0.11 ml/min.) and a calculated plasma half-life of 35.55 days. This half-life was approximately eight times longer than that determined previously in rats. In addition, the intraindividual fluctuation of OTA plasma levels was investigated in eight individuals over a period of 2 months. The concentrations determined ranged between 0.2 and 0.9 ng OTA/ml plasma. The plasma levels in some individuals remained nearly constant over time, while others varied considerably (e.g. increase of 0.4 ng/ml within 3 days, decrease of 0.3 ng/ml within 5 days) during the observation period. This intraindividual fluctuation in OTA plasma levels, which may represent differences in OTA exposure and/or metabolism, as well as the losure and/or metabolism, as well as the large difference in plasma half-life in humans compared to rats must be taken into consideration when the results of rat cancer study data are extrapolated to humans for risk assessment purposes. (orig.)

135

Kinetic parameters and intraindividual fluctuations of ochratoxin A plasma levels in humans  

Energy Technology Data Exchange (ETDEWEB)

The mycotoxin ochratoxin A (OTA) is a rodent carcinogen produced by species of the ubiquitous fungal genera Aspergillus and Penicillium. OTA is found in a variety of food items and as a consequence is also found in human plasma (average concentrations found in this study: 0.1-1 ng OTA/ml plasma). To improve the scientific basis for cancer risk assessment the toxicokinetic profile of OTA was studied in one human volunteer following ingestion of 395 ng {sup 3}H-labeled OTA (3.8 {mu}Ci). A two-compartment open model consisting of a central compartment was found to best describe the in vivo data. This two-compartment model consisted of a fast elimination and distribution phase (T{sub 1/2} about 20 h) followed by a slow elimination phase (renal clearance about 0.11 ml/min.) and a calculated plasma half-life of 35.55 days. This half-life was approximately eight times longer than that determined previously in rats. In addition, the intraindividual fluctuation of OTA plasma levels was investigated in eight individuals over a period of 2 months. The concentrations determined ranged between 0.2 and 0.9 ng OTA/ml plasma. The plasma levels in some individuals remained nearly constant over time, while others varied considerably (e.g. increase of 0.4 ng/ml within 3 days, decrease of 0.3 ng/ml within 5 days) during the observation period. This intraindividual fluctuation in OTA plasma levels, which may represent differences in OTA exposure and/or metabolism, as well as the large difference in plasma half-life in humans compared to rats must be taken into consideration when the results of rat cancer study data are extrapolated to humans for risk assessment purposes. (orig.)

Studer-Rohr, I. [Inst. of Toxicology, Swiss Federal Inst. of Tech. and Univ. of Zurich, Schwerzenbach (Switzerland); Dept. of Food Science, Swiss Federal Inst. of Tech., Zurich (Switzerland); Schlatter, J. [Toxicology Section, Div. of Food Science, Swiss Federal Office of Public Health, Zurich (Switzerland); Dietrich, D.R. [Dept. of Environmental Toxicology, Univ. of Konstanz, Konstanz (Germany); Inst. of Toxicology, Swiss Federal Inst. of Tech. and Univ. of Zurich, Schwerzenbach (Switzerland)

2000-11-01

136

Mesozoic sea level fluctuations documented on Exmouth Plateau off northwestern Australia  

Energy Technology Data Exchange (ETDEWEB)

The Exmouth Plateau is uniquely suited to the study of sea level changes because of the existence of an extensive seismic grid and industry well sites, an extended Mesozoic stratigraphic record punctuated with several major unconformities, and the relatively protected position of this high plateau. Thus, documenting sea level fluctuations was one of the major objectives of drilling on the Exmouth Plateau. This documentation depends on their ability to (1) isolate the tectonic overprint from the eustatic signal by retracing the subsidence histories of the drill sites and (2) accurately date the unconformities. Two transects of sites were drilled, one with four sites on the Wombat Plateau and the other with two sites on the central Exmouth Plateau, with one site located relatively proximally and another distally to the source of sediment supply. Preliminary shipboard work indicates that the age of Mesozoic unconformities can be accurately constrained and the subsidence-related tectonic events can be effectively isolated from sea level fluctuations. Sequence stratigraphic analysis of seismic, lithofacies, biofacies, and well-log data document important Upper Triassic sequence boundaries on the Wombat Plateau between the middle and upper Carnian (Norian-Rhaetian boundary) and in the upper most Rhaetian, whose timing and relative magnitude conform well with the eustatic cycle chart. The sequence boundary and systems tracts recognized in the central Exmouth Plateau Barrow Group equivalent strata (Berriasian-Valanginian) also correspond well with the global cycle chart. These preliminary results are of considerable importance in providing a test of the validity of the eustatic model.

Haq, B.U.; Blome, C.D.; Bralower, T.J.; Brenner, W.; Oda, M.; Siesser, W.; Wonders, A.A.H.

1989-03-01

137

Information-based system identification for predicting the groundwater-level fluctuations of hillslopes  

Science.gov (United States)

The analysis of pre-existing landslides and landslide-prone hillslopes requires an estimation of maximum groundwater levels. Rapid increase in groundwater levels may be a dominant factor for evaluating the occurrence of landslides. System identification—use of mathematical tools and algorithms for building dynamic models from measured data—is adopted in this study. The fluid mass-balance equation is used to model groundwater-level fluctuations, and the model is analytically solved using the finite-difference method. Entropy-based classification (EBC) is used as a data-mining technique to identify the appropriate ranges of influencing variables. The landslide area at Wushe Reservoir, Nantou County, Taiwan, is chosen as a field test site for verification. The study generated 65,535 sets of numbers for the groundwater-level variables of the governing equation, which is judged by root mean square errors. By applying cross-validation methods and EBC, limited numbers of validation samples are used to find the range of each parameter. For these ranges, a heuristic method is employed to find the best results of each parameter for the prediction model of groundwater level. The ranges for governing factors are evaluated and the resulting performance is examined.

Hong, Yao-Ming; Wan, Shiuan

2011-09-01

138

Drought impact on water use efficiency and intra-annual density fluctuations in Erica arborea on Elba (Italy).  

Science.gov (United States)

Erica arborea (L) is a widespread Mediterranean species, able to cope with water stress and colonize semiarid environments. The eco-physiological plasticity of this species was evaluated by studying plants growing at two sites with different soil moistures on the island of Elba (Italy), through dendrochronological, wood-anatomical analyses and stable isotopes measurements. Intra-annual density fluctuations (IADFs) were abundant in tree rings, and were identified as the key parameter to understand site-specific plant responses to water stress. Our findings showed that the formation of IADFs is mainly related to the high temperature, precipitation patterns and probably to soil water availability, which differs at the selected study sites. The recorded increase in the (13) C-derived intrinsic water use efficiency at the IADFs level was linked to reduced water loss rather than to increasing C assimilation. The variation in vessel size and the different absolute values of ?(18) O among trees growing at the two study sites underlined possible differences in stomatal control of water loss and possible differences in sources of water uptake. This approach not only helped monitor seasonal environmental differences through tree-ring width, but also added valuable information on E.?arborea responses to drought and their ecological implications for Mediterranean vegetation dynamics. PMID:23848555

Battipaglia, Giovanna; DE Micco, Veronica; Brand, Willi A; Saurer, Matthias; Aronne, Giovanna; Linke, Petra; Cherubini, Paolo

2014-02-01

139

Water level measurement uncertainty during BWR instability  

International Nuclear Information System (INIS)

This paper addresses the performance of the water-level measurement system in a boiling water reactor (BWR) during severe instability oscillations which, under some circumstances, can occur during an anticipated transient without SCRAM (ATWS). Test data from a prototypical mock-up of the water-level measurement system was used to refine and calibrate a water-level measurement system model. The model was then used to predict level measurement system response, using as boundary conditions vessel pressures calculated by ppercase RETRAN for an ATWS/instability event.The results of the study indicate that rapid pressure changes in the reactor pressure vessel which cause oscillations in downcomer water level, coupled with differences in instrument line lengths, can produce errors in the sensed water level. Using nominal parameters for the measurement system components, a severe instability transient which produced a 0.2 m peak-to-minimum water-level oscillation in the vessel downcomer was predicted to produce pressure difference equivalent to a 0.7 m level oscillation at the input to the differential pressure transmitter, 0.5 m oscillation at the output of the transmitter, and an oscillation of 0.3 m on the water-level indicator in the control room. The level measurement system error, caused by downcomer water-level oscillations and instrument line length differential, is mitigated by damping both in the differential pressure transmitter used to infer level and in the contritter used to infer level and in the control room display instrument. ((orig.))

140

Analysis of fluctuations of spacious distributed offshore wind farms in German territorial waters  

Energy Technology Data Exchange (ETDEWEB)

Offshore wind farms planned in the German part of the North Sea can only be connected to electricity grids at a few feedpoints. The integration of offshore wind power plants it is essential to exploit the wind resource potential which depends not only on the respective site of the wind farm, but also on the farm geometry. In order to successfully integrate the offshore sites into the electricity system, feed-in fluctuations of distributed wind farms must be checked. Natural reduction potentials of the fluctuations by suitable interconnection of the wind farms simplify this system integration and relieve conventional power plant parks. These potentials exist and must be included in energy management strategies. This paper focused on the comparison of time sequence modelling based on the autoregressive moving average (ARMA) approach with the actual wind measurements at a site of an offshore wind energy research platform. It was concluded that time sequence models are not an adequate alternative for measurements of real wind conditions at offshore sites for considering the encountered wind speed fluctuations. The authors showed that it is more appropriate to resort to measured hub level data of future wind energy plants. A detailed study of an offshore wind farm is necessary for forecasting the power output fluctuations. The short-term power output changes can reach the order of magnitude of the power rating of a conventional power plant block. 13 refs., 7 figs.

Splett, M.; Bendfeld, J.; Luttig, R.; Tigges, M.; Voss, J. [Paderborn Univ., Paderborn (Germany). Dept. for Sustainable Energy Concepts

2008-07-01

 
 
 
 
141

Optimal control of a qubit coupled to a two-level fluctuator  

CERN Document Server

A central challenge for implementing quantum computing in the solid state is decoupling the qubits from the intrinsic noise of the material. We investigate limits of controllability for a paradigmatic model: A single qubit coupled to a two-level fluctuator exposed to a heat bath. We systematically search for optimal pulses using a generalization of the novel open system Gradient Ascent Pulse Engineering (GRAPE) algorithm. We show and explain that next to the known optimal bias point of this model, there are optimal shapes which refocus unwanted terms in the Hamiltonian. We study the limitations of control set by the decoherence properties in the fast flipping regime, which go beyond a simple random telegraph noise model. This can lead to a significant improvement of quantum operations in hostile environments.

Rebentrost, P; Serban, I; Wilhelm, F K

2006-01-01

142

Development of Mechanical Water Level Controller  

Directory of Open Access Journals (Sweden)

Full Text Available The automatic water level controller is a device designed to regulate automatically the pumping of water to an overhead tank without allowing the water in the tank to be exhausted. The design of this mechanical device was achieved using the Archimedes principle of floatation; having a float which determines the water level in the tank depending on the choice of the minimum (lower and maximum (upper level inscribed in the tank. The fundamental attribute of this device is the ease in design, fabrication and mounting at a lower cost. Its testing had shown and proved that it works efficiently with Archimedes’ principle of floatation. This eliminates the frequent human intervention/monitoring of the water level in the overhead tank to control overflow manually, thereby eliminating water and energy wastages.

Akonyi Nasiru Sule

2012-10-01

143

Quantum fluctuations and isotope effects in ab initio descriptions of water  

CERN Document Server

Nuclear quantum effects, such as zero-point energy and tunneling, cause significant changes to the structure and dynamics of hydrogen bonded systems such as liquid water. However, due to the current inability to simulate liquid water using an exact description of its electronic structure, the interplay between nuclear and electronic quantum effects remains unclear. Here we use simulations that incorporate the quantum mechanical nature of both the nuclei and electrons to provide a fully ab initio determination of the particle quantum kinetic energies, free energy change upon exchanging hydrogen for deuterium and the isotope fractionation ratio in water. These properties, which selectively probe the quantum nature of the nuclear degrees of freedom, allow us to make direct comparison to recent experiments and elucidate how electronic exchange and correlation and nuclear quantum fluctuations determine the structure of the hydrogen bond in water.

Wang, Lu; Markland, Thomas E

2014-01-01

144

Quantum fluctuations and isotope effects in ab initio descriptions of water  

Science.gov (United States)

Isotope substitution is extensively used to investigate the microscopic behavior of hydrogen bonded systems such as liquid water. The changes in structure and stability of these systems upon isotope substitution arise entirely from the quantum mechanical nature of the nuclei. Here, we provide a fully ab initio determination of the isotope exchange free energy and fractionation ratio of hydrogen and deuterium in water treating exactly nuclear quantum effects and explicitly modeling the quantum nature of the electrons. This allows us to assess how quantum effects in water manifest as isotope effects, and unravel how the interplay between electronic exchange and correlation and nuclear quantum fluctuations determine the structure of the hydrogen bond in water.

Wang, Lu; Ceriotti, Michele; Markland, Thomas E.

2014-09-01

145

Numerical analysis of a three-phase system with a fluctuating water table  

International Nuclear Information System (INIS)

Numerical simulations are presented of a one-dimensional, multiphase flow system that involves the redistribution of aqueous-phase liquids and nonaqueous-phase liquids (NAPLs) by a fluctuating water table. The numerical analyses were completed using an integrated-volume, finite-difference-based solution scheme of the governing multiphase conservation equations and constitutive theory. Conservation equations were solved for two components water and oil, with the assumption of a passive gas-phase. Nonlinearities introduced into the governing conservation equations through the constitutive theory were handled with a multivariable Newton-Raphson iterative scheme. The functional relationships between the phase relative permeability, the phase saturation, and phase pressures in porous media were described with a general theoretical model that includes the effects of air and oil occlusion during imbibition. Parameters required for the theoretical model were defined for two-phase systems (e.g., air- water, air-oil, and oil-water). The theoretical model assumes that wettability decreases in the following order: water, oil, air. Results from the numerical simulations are compared against measurements taken from a previous multiphase flow experiment. The experiment involved subjecting an initially water-drained, three-phase system (i.e., air-oil-water), to a fluctuating water table. The experimental objective was to quantify the entrapment of air and NAPL by phases of greater wettability under dynamic conditions. Comparison of numerical and experimental results were made for two ratios of imbibition to drainage characteristic, curve-shape parameters and two models for relative permeability in two-phase systems. A description of the numerical methods used to solve the governing conservation and constitutive equations for multiphase hysteretic conditions is given

146

The roles of shear and cross-correlations on the fluctuation levels in simple stochastic models. Revision  

Energy Technology Data Exchange (ETDEWEB)

Highly simplified models of random flows interacting with background microturbulence are analyzed. In the limit of very rapid velocity fluctuations, it is shown rigorously that the fluctuation level of a passively advected scalar is not controlled by the rms shear. In a model with random velocities dependent only on time, the level of cross-correlations between the flows and the background turbulence regulates the saturation level. This effect is illustrated by considering a simple stochastic-oscillator model, both exactly and with analysis and numerical solutions of the direct-interaction approximation. Implications for the understanding of self-consistent turbulence are discussed briefly.

Krommes, J.A.

1999-11-03

147

KARST WATER LEVEL PREDICTION BY DATA OF THE BÜKK KARST WATER LEVEL MONITORING SYSTEM  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To define the exploitable water reserve of Bükk is important to support the sustainable water-supply of Miskolc. The prior water level prediction method was a trend line fitting method on measured data of a concrete monitoring point. The expectable character of water level change was determined by extension of trend line. End of 2011 the karst water level was decreased under absolute minimum value of 20 years database. Inspection of prior prediction method and find alternative prediction pos...

Le?na?rt, La?szlo?; Darabos, Eniko?

2012-01-01

148

Method of controlling pressure and water level in nuclear reactors  

International Nuclear Information System (INIS)

Purpose: To minimize thermal effects to a water feed spargers upon reactor start-up, while control reactor pressure at high accuracy upon reactor shutdown. Method: Detection signals from a level detector for detecting the water level in a pressure vessel and a pressure detector for detecting the pressure in the reactor are inputted to a controller, to thereby output control signals of valve opening degree for flow rate control valves disposed to main steam drain pipeways, feedwater pipeways and discharge pipeways. In this way, by balancing the main steam flow rate from the pressure vessel and the waterfeed amount to control the water level in the reactor at a constant level and controlling the main steam flow rate from the reactor vessel accurately within a minute flow rate range, pressure control characteristics of the nuclear reactor at high accuracy can be obtained. In this way, since no substantial water feeding is necessary upon reactor start-up and the pressure fluctuations can be minimized upon reactor shutdown, thermal stresses to the equipments or members can be reduced. (Kawakami, Y.)

149

Radon levels in a water distribution network  

International Nuclear Information System (INIS)

The capital city of Saudi Arabia, Riyadh, relies on both desalinated sea water as well as treated groundwater to meet all its water requirements. About 66% of the water demand is met by desalinated sea water, and the remaining is supplied by six groundwater treatment plants located in the vicinity of the city and supplied with water from 161 wells. The desalinated sea water is blended with only one plant product water and pumped to the distribution network, whereas the other five plants product water is pumped directly to the network. A study of 222Rn levels in the city distribution network was carried out in which 89 samples were collected from different locations representing the city districts. All samples have shown low radon levels with an average concentration of 0.2 Bq l-1 and a range values of 0.1-1.0 Bq l-1. The level of radon in different parts of the network was found to be influenced by the water sources to which they are supplied. The lowest radon levels were observed in districts supplied mostly by desalinated sea water. (Author)

150

Measurement of temperature fluctuations in plasma jet of the water stabilized DC arc torch  

International Nuclear Information System (INIS)

Knowledge of local temperature fluctuations in thermal plasma jets is of fundamental importance in the investigation of turbulence and other disturbance phenomena attending a plasma stream flowing from the wall stabilized arc torches into the surrounding atmosphere. Time resolved measurements of lateral intensity profiles of chosen spectral lines at the exit of the water stabilized plasma torch showed noticeable changes in profile shapes. On the basis of electrical and spectroscopic measurements it has turned out that the profile changes can be partially interpreted as the temperature fluctuations coupled with the quasi-periodical current changes resulting from imperfect current smoothing of the torch power supply. Our approach to studying temperature fluctuations in thermal plasma jets combines virtues of the two diagnostic methods. The spatially resolved emission spectroscopy enables us to measure the temperature and corresponding lateral intensity profiles. The relatively simple quick optoelectronic device is applied to monitoring changes in the lateral intensity profile with a time resolution unattainable in the first mentioned spectroscopic technique

151

Critical fluctuations of the micellar triethylene glycol monoheptyl ether-water system.  

Science.gov (United States)

Using the equal volume criterion and also the pseudospinodal conception the critical demixing point of the triethylene glycol monoheptyl ether/water system (C7E3H2O) has been determined as Ycrit=0.1 and Tcrit=296.46 K (Y, mass fraction of surfactant). From density measurements the critical micelle concentration (cmc) followed as Ycmc=0.007 at 288.15 K and Ycmc=0.0066 at 298.15 K. The (static) shear viscosity etas and the mutual diffusion coefficient D of the C7E3H2O mixture of critical composition have been evaluated to yield their singular and background parts. From a combined treatment of both quantities the relaxation rate Gamma of order parameter fluctuations has been derived. Gamma follows power law with universal critical exponent and amplitude Gamma0=3.1 x 10(9) s(-1). Broadband ultrasonic spectra of C7E3H2O mixtures exhibit a noncritical relaxation, reflecting the monomer exchange between micelles and the suspending phase, and a critical term due to concentration fluctuations. The former is subject to a relaxation time distribution that broadens when approaching the critical temperature. The latter can be well represented with the aid of the dynamic scaling model by Bhattacharjee and Ferrell (BF) [Phys. Rev. A. 31, 1788 (1985)]. The half-attenuation frequency in the scaling function of the latter model is noticeably smaller (Omega12 (BF) approximately 1) than the theoretically predicted value Omega12 (BF)=2.1. This result has been taken as an indication of a coupling between the fluctuations in the local concentration and the kinetics of micelle formation, in correspondence with the idea of a fluctuation controlled monomer exchange [T. Telgmann and U. Kaatze, Langmuir 18, 3068 (2002)]. PMID:16599728

Haller, J; Behrends, R; Kaatze, U

2006-03-28

152

Hunger games: fluctuations in blood glucose levels influence support for social welfare.  

Science.gov (United States)

Social-welfare policies are a modern instantiation of a phenomenon that has pervaded human evolutionary history: resource sharing. Ancestrally, food was a key shared resource in situations of temporary hunger. If evolved human psychology continues to shape how individuals think about current, evolutionarily novel conditions, this invites the prediction that attitudes regarding welfare politics are influenced by short-term fluctuations in hunger. Using blood glucose levels as a physiological indicator of hunger, we tested this prediction in a study in which participants were randomly assigned to conditions in which they consumed soft drinks containing either carbohydrates or an artificial sweetener. Analyses showed that participants with experimentally induced low blood glucose levels expressed stronger support for social welfare. Using an incentivized measure of actual sharing behavior (the dictator game), we further demonstrated that this increased support for social welfare does not translate into genuinely increased sharing motivations. Rather, we suggest that it is "cheap talk" aimed at increasing the sharing efforts of other individuals. PMID:24171932

Aarøe, Lene; Petersen, Michael Bang

2013-12-01

153

Fluctuation of Corrected Serum Calcium Levels Following Partial and Total Thyroidectomy  

Directory of Open Access Journals (Sweden)

Full Text Available Objectives: To identify any fluctuation of corrected serum calcium levels and to determine the presence of sub-clinical hypocalcaemia following partial and total thyroidectomy with preservation of at least two parathyroid glands. Design: A prospective study. Setting: Tertiary Head & Neck referral unit. Patients: Eighty five patients undergoing partial or total thyroidectomy with or without laryngectomy from April 2003 to April 2009 were included in the study. Corrected serum calcium levels (CCSL were noted preoperatively and postoperatively on day 1, day 7 and 6 months. Results: Forty six patients underwent hemi-thyroidectomy (HT, 29 underwent total thyroidectomy (TT and 10 underwent total thyroidectomy with laryngectomy (TTL. Nine (19.56% patients in the HT group, 6 (24.14% in the TT group and 3 (30.0% in the TTL group developed hypocalcaemia postoperatively which was most significant on 1st postoperative day. This improved by 7th postoperative day in each group when the change in calcium levels became statistically insignificant. Six patients (3 patients had HT, 2 had TT and 1 had TTL developed sub-clinical mild hypocalcaemia which was persistent at 6 months follow-up. Conclusion: The most significant changes in corrected serum calcium levels occur within first 24 hours after thyroid surgery. Thereafter most patients return to normocalcaemia within a seven-day period. Despite preservation of parathyroid glands there is a subgroup of patients who develop sub-clinical hypocalcaemia which persists even at six months but does not require treatment.

Vikas Malik

2011-09-01

154

Mitigation of radon levels in water  

International Nuclear Information System (INIS)

Potable well waters are used for drinking, various domestic usage, and for irrigation in many parts of the world. Because of the possibility of finding high concentrations of radioactive gas, a program will be conducted to determine the levels of 222Rn in local well waters. The liquid scintillation counting technique will be used in the survey. The US Environmental Protection Agency (EPA) has recently proposed that the upper limit for 222Rn in potable water should not exceed 300 pCi/l. According to the EPA, well waters found to have concentration of 222Rn higher than 300 pCi/l will need treatment to reduce radon to the accepted levels. The plan of current work is to study the effect of various radon-mitigating techniques. Activated charcoal treatment, aeration, and heat treatment of water high in 222Rn concentration have been investigated in the laboratory to determine their effectiveness for removing 222Rn from well waters

155

Water Level Detection Using Synthetic Aperture Radar Imagery  

International Nuclear Information System (INIS)

ion using Canada's RADARSAT-1 imagery. Three Canadian sites were chosen for our study: Niagara Area Hydro Reservoir; Quirke Lake uranium tailings management facility (TMF); and JEB Pit TMF. Initial results, using RADARSAT-1 data acquired over a three year period, show dramatic changes in both the total water surface area and markers (natural or man-made) becoming visible as the water level decreases. These very promising results indicated that SAR imagery can be used as an excellent tool for mapping remote location (which is useful for inspection planning), object detection (verification of declared activities, or detection of undeclared activities), and detection of water level fluctuation (which may be linked to a clandestine power generation during a period where optical sensors are not effective, e.g. at night or during adverse weather conditions). Additional analysis of RADARSAT-1 data, supportable by ground truth information and IKONOS imagery, is being carried out and further results are expected to be available soon. Large steep walled or terraced reservoirs, as in the case of JEB Pit TMF would require a different analysis technique. Scoping work indicated that it would be possible to deduce the water level by measuring the wall height using 'radar shadow', in a manner similar to the exploitation of shadows in optical images

156

Influence of short time scale water column fluctuations on broadband signal intensity.  

Science.gov (United States)

The KAM11 experiment was conducted in 100 m of water off the Western side of Kauai, Hawaii, in June/July, 2011 during which two identical bottom mounted tripods, separated by 1 km, transmitted reciprocal chirp sequences. A monitoring hydrophone was suspended at a depth of 25 m from the R/V Kilo Moana approximately midway between the tripod stations. Impulse response measurements at the suspended hydrophone show intermediate arrivals between direct-path/bottom-bounce and surface-bounce arrivals unique to only one tripod source. Focusing and defocussing of the intermediate arrivals show the influence of fluctuations in the sound speed profile over time scales from seconds to hours. Short term intensity variations arise from surface driven vertical undulations in the water column. Over longer time scales changes in the thermocline govern the evolution of the intermediate arrival. Data model comparison is conducted with ray tracing and parabolic equation modeling. [Work supported by ONR 322OA.]. PMID:25235654

Eickmeier, Justin; Mohsen, Badiey

2014-04-01

157

Isotopes reveal fluctuation in trophic levels of estuarine organisms, in space and time  

Science.gov (United States)

The estimation of the trophic level (TL) occupied by organisms in estuarine food webs, based on isotopic analysis, is generally done only for one season or averaged among seasons and sites. This does not allow the observation of possible alterations of TL in time and space. As estuaries are highly dynamic environments, it is plausible that the TLs of many of its organisms are not static, like usually portrayed in food web diagrams, but fluctuate in space and time. The TLs of marine juvenile fish, resident fish, shrimp, polychaetes, bivalves and amphipods were determined isotopically, in the Tagus estuary. Sampling was carried out in two nursery areas at each season. Significant changes in TL were observed, in space and time, for the vast majority of the organisms. A drop in TL in summer was observed for various species. The high availability of microalgae and macroalgae in summer may be the cause for this drop, which mainly affects low TL omnivores. These omnivores may opportunistically increase the proportion of primary producers in their diet, thus lowering their mean TL. Such an effect seems to cascade to secondary consumers, like Solea senegalensis and Pomatoschistus microps, which also presented a drop in TL in summer. This study also revealed that organisms that have been considered to be mainly primary consumers, like Liza ramada, and Scrobicularia plana, can actually assume considerably higher TLs seasonally, placing them as secondary consumers.

Vinagre, C.; Salgado, J. P.; Mendonça, V.; Cabral, H.; Costa, M. J.

2012-08-01

158

A Convective Model Conm That Simulates Solute Redistribution Caused by Water Table Fluctuations  

Directory of Open Access Journals (Sweden)

Full Text Available A study of the solute redistribution caused by water-table fluctuations in experimental packed columns of fine sand and a sandy clay loam soil using potassium chloride as a non-reactive tracer is modelled. With the water table initially at the soil surface, the redistribution of surface applied chloride down the profile was measured after the water table was lowered, then after it was raised again to the soil surface, and then after it was again lowered. In each case, sufficient time was allowed before measurements of chloride were made for the soil-water profile in the column to approach equilibrium conditions with the water table. A simple convection model (CONM was developed and used to simulate the chloride redistribution. This was compared with the LEACHM model of Wagenet and Hutson based on the convection-dispersion equation, and the physical basis of each critically discussed. It was found that the experimental results in general agreed better with simulated results using CONM than with those using LEACHM. It was concluded that the chloride movement observed in the experimental columns was dominantly convective. The application of this work to optimise fertiliser requirements when subirrigation-drainage systems are employed is discussed.

Cesáreo Landeros-Sánchez

2012-11-01

159

KARST WATER LEVEL PREDICTION BY DATA OF THE BÜKK KARST WATER LEVEL MONITORING SYSTEM  

Directory of Open Access Journals (Sweden)

Full Text Available To define the exploitable water reserve of Bükk is important to support the sustainable water-supply of Miskolc. The prior water level prediction method was a trend line fitting method on measured data of a concrete monitoring point. The expectable character of water level change was determined by extension of trend line. End of 2011 the karst water level was decreased under absolute minimum value of 20 years database. Inspection of prior prediction method and find alternative prediction possibility was justified by that enormous decrease. A characteristic curve was created from data line of 20 years which shows the draining process of karst in exorbitantly arid period. That curve can fitted to any water level and probable karst water level is predictable if infiltration is zero after that point.

LÉNÁRT, László

2012-08-01

160

Lowest Landau level scaling of the fluctuation conductivity for RFeAsO (R=Nd,Pr,Sm) superconductors  

International Nuclear Information System (INIS)

The fluctuation conductivity under magnetic fields is studied in RFeAsO (R=Nd,Pr,Sm) superconductors reported in literatures within the lowest Landau level (LLL) scaling approach. The mean filed critical temperature Tc(H) is determined by the crossing point technique. With the determined values of Tc(H), the fluctuation conductivity is scaled within both three-dimensional (3D) and two-dimensional (2D) LLL approach. For all the samples studied, the 3D-LLL scaling is found but in a relatively small temperature interval around Tc(H), while 2D-LLL scaling is observed in all other temperature region. These results suggest a 3D-2D crossover of the fluctuation conductivity in RFeAsO superconductors.

 
 
 
 
161

Hydrologic conditions and lake-level fluctuations at Long Lost Lake, 1939-2004, White Earth Indian Reservation, Clearwater County, Minnesota  

Science.gov (United States)

Long Lost Lake, a closed-basin lake in Clearwater County, Minnesota, has had a substantial rise in lake level since 1990. The increased level and surface area of the lake has led to the inundation of nearby homes and roads. The U.S. Geological Survey, in cooperation with the White Earth Band of Chippewa Indians, conducted a study to document the historical lake-level fluctuations, to investigate reasons for hydrologic change, and to develop a general understanding of the hydrology of lakes that have had rapid changes in lake level. Lake levels were recorded continuously from August 2003 through December 2004. The purpose was to establish a temporal, detailed record of lake levels and to connect this record to precipitation and ground-water-level data. A long-term record is critical to understanding the relation between surface water and ground water. This is especially true for closed-basin lakes. Between August 2003 and December 2004, the lake level generally declined. The highest lake altitude was 492.58 meters above NAVD 88 on August 5, 2003, and the low of 492.11 meters above NAVD 88 occurred on August 29, 2004. Results of water-level measurements in 5 observation wells and 14 wetlands and ponds show that the water-table level is substantially higher on the north side of the lake than the lake level, providing the head pressure necessary for ground-water discharge into Long Lost Lake. In contrast, on the south and east sides of the lake, water-table levels are similar to the lake level. This indicates a general north-northwest to south-southeast ground-water flow direction. Results of a synoptic survey of lake temperature and other measurements supported the direction of water inflow and outflow. Aerial photography and a geographic information system were used to construct a historical lake record from 1939 to 2001. Lake-level increases match similar increases in precipitation, indicating a strong link between the two. Results show that lake-level increases in Long Lost Lake appear to primarily be due to natural rather than anthropogenic effects.

Christensen, Victoria G.; Bergman, Andrea L.

2005-01-01

162

The Effects of Disconnect Entrapped Air on Hydraulic Conductivity in the Presence of Water Table Fluctuations  

Science.gov (United States)

The hydraulic conductivity of a natural groundwater system can possess high spatial and temporal variability in the presence of an entrapped air phase (quasi-saturated soils) which is a key factor in controlling hydraulic behavior (Faybishenko, 1995). Research conducted by Faybishenko (1995), Frye et al. (1997) and Zlotnik et al. (2007) provide evidence of reduced hydraulic conductivity caused by entrapped air which can be introduced by water table elevation changes. The hypothesis that the decreases in hydraulic conductivity caused by entrapped air are sensitive to fluctuations in the water table was tested using laboratory experiments. This work investigates the degree of air entrapment by immiscible displacement and the effects of applying increasing confining pressures (water table height) on the quasi-saturated hydraulic conductivity for a range of sands. Results to date indicate that the changes in the volume of entrapped gas caused by 2.5m changes in water table height induced changes in the quasi-saturated hydraulic conductivity by approximately a factor of 2. Such results have implications for site interpretation and simulation given that the behavior of quasi-saturated systems has not been incorporated into current general models of flow and transport. Faybishenko, B.A. 1995. Hydraulic behaviour of quasi-saturated soils in the presence of entrapped air: Laboratory experiments. Water Resources Research 31 (10): 2421-2435. Frye, V.A., Selker, J.S. and S.M. Gorelick. 1997. Experimental investigations for trapping oxygen gas in saturated porous media for in situ bioremediation. Water Resources Research 33 (12): 2687-2696. Zlotnik, V.A., Eisenhauer, D.E., Schlautman, D.J., Zurbuchen, B.R. and D. Van Peursem. 2007. Entrapped air effects on dipole flow test in sand tank experiments: Hydraulic conductivity and head distribution. Journal of Hydrology 339: 193-205.

Marinas, M.; Smith, J. E.; Roy, J. W.

2009-05-01

163

Impact of scaled-down on dissolved oxygen fluctuations at different levels of the lipase synthesis pathway of Yarrowia lipolytica  

Directory of Open Access Journals (Sweden)

Full Text Available The impact of the fluctuations in dissolved oxygen tension (DOT on the lipase production by Yarrowia lipolytica has been investigated in a scale-down reactor (SDR. This bioreactor comprises a 20 l agitated vessel with an automatic valve controlling the opening and closure of the air flow line. This kind of scale-down apparatus is used in order to generate DOT gradients encountered in large-scale, while maintaining the other environmental conditions constant. The impact of DOT fluctuations has been estimated at three levels of the lipase synthesis machinery: lipase gene expression, lipase translation, lipase excretion to the extracellular medium. Among these levels, the performance of lipase production under oscillating DOT was significantly affected at the lipase gene expression level.

Delvigne, F.

2010-01-01

164

Effects of a long term water level reduction on the ecology and water quality in an eastern Mediterranean lake  

Directory of Open Access Journals (Sweden)

Full Text Available Water level fluctuations play a significant role in the lake nutrient dynamics, and consequently may have a strong influence on the biological communities and productivity. In this article we investigated the effects of a long term water level reduction on key chemistry parameters and major biological communities in an eastern Mediterranean lake. Our approach is based on temporal data regarding water quality, fish, zooplankton and aquatic vegetation that are representative of different water level periods. The results revealed significant correlations between water level, conductivity and chloride concentration suggesting a clear effect of the water level reduction on the water quality. Among the key findings of this study is the significant increase of zoobenthivorous fish (roach and carp from 1973 to 1999 that correlates with the water level reduction. A decline of charophytes is also noted whereas the reed beds appear to have expanded at the shallower parts of the lake. The zooplankton composition of the lake is mostly dominated by nauplii, rotifer and small-sized crustaceans indicating a possible effect of fish predation. Overall, this article has ascertained an alarming shift of water quality and composition of biological communities that can be attributed to the combined effects of eutrophication and the extreme water level decrease.

Stefanidis K.

2013-09-01

165

Projecting Future Water Levels of the Laurentian Great Lakes  

Science.gov (United States)

The Laurentian Great Lakes are the largest freshwater system on Earth, containing 84% of North America's freshwater. The lakes are a valuable economic and recreational resource, valued at over 62 billion in annual wages and supporting a 7 billion fishery. Shipping, recreation, and coastal property values are significantly impacted by water level variability, with large economic consequences. Great Lakes water levels fluctuate both seasonally and long-term, responding to natural and anthropogenic climate changes. Due to the integrated nature of water levels, a prolonged small change in any one of the net basin supply components: over-lake precipitation, watershed runoff, or evaporation from the lake surface, may result in important trends in water levels. We utilize the Abdus Salam International Centre for Theoretical Physics's Regional Climate Model Version 4.5.6 to dynamically downscale three global global climate models that represent a spread of potential future climate change for the region to determine whether the climate models suggest a robust response of the Laurentian Great Lakes to anthropogenic climate change. The Model for Interdisciplinary Research on Climate Version 5 (MIROC5), the National Centre for Meteorological Research Earth system model (CNRM-CM5), and the Community Climate System Model Version 4 (CCSM4) project different regional temperature increases and precipitation change over the next century and are used as lateral boundary conditions. We simulate the historical (1980-2000) and late-century periods (2080-2100). Upon model evaluation we will present dynamically downscaled projections of net basin supply changes for each of the Laurentian Great Lakes.

Bennington, V.; Notaro, M.; Holman, K.

2013-12-01

166

Low level plutonium removal from surface waters  

International Nuclear Information System (INIS)

Methods have been developed to remove low level (1-10,000 pCi/L) plutonium from surface waters and ponds at Rocky Flats Plant, Colorado. The process involves the combining of two existing technologies to accomplish removal levels that are enhanced over the separate methods. The first step is the addition of a fine clay to the water so that sorption of plutonium is accomplished. A variety of clay types were studied including montmorillinite, kaolinte, and bentonite. Most clays were able to remove Pu V and Pu VI. The second step is the addition of a flocculating agent to settle the fine clay particles so negative surface charge, a cationic flocculent was used. A commercial clay already containing flocculent was also studied. Since this mixture contained both the flocculent and the clay the process was reduced to a one step procedure. Both methods showed that this procedure could removed up to 97% of the soluble and colloidal plutonium from surface waters

167

Hydro static water level systems at Fermilab  

Energy Technology Data Exchange (ETDEWEB)

Several Hydrostatic Water Leveling systems (HLS) are in use at Fermilab. Three systems are used to monitor quadrupoles in the Tevatron and two systems are used to monitor ground motion for potential sites for the International Linear Collider (ILC). All systems use capacitive sensors to determine the water level of water in a pool. These pools are connected with tubing so that relative vertical shifts between sensors can be determined. There are low beta quadrupoles at the B0 and D0 interaction regions of Tevatron accelerator. These quadrupoles use BINP designed and built sensors and have a resolution of 1 micron. All regular lattice superconducting quadrupoles (a total of 204) in the Tevatron use a Fermilab designed system and have a resolution of 6 microns. Data on quadrupole motion due to quenches, changes in temperature will be presented. In addition data for ground motion for ILC studies caused by natural and cultural factors will be presented.

Volk, J.T.; Guerra, J.A.; Hansen, S.U.; Kiper, T.E.; Jostlein, H.; Shiltsev, V.; Chupyra, A.; Kondaurov, M.; Singatulin, S.

2006-09-01

168

Analysis and improvements of module incidental interference faults of water level control system pressurize NPP  

International Nuclear Information System (INIS)

In Daya Bay nuclear power plant, there have been many times that the module used to value the water level outputs a small pulse interference when the pressurizer water level control system is in operation, and the interference exists only in analog storage operation module, which can directly impact the control of the water level of the pressurizer, causing the water level fluctuations and adversely affecting the safe operation of the reactor. This paper analyzes the module incidental interference faults of the water level control system of the NPP pressurizer from the point view of the system control and design of module hardware, and finds out the reasons by the system simulation experiment and power supply circuit test. It is suggested to further improve on the design of hardware loops, add more inductance and capacity to eliminate the interference. (authors)

169

Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

Chen, W.-Y. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Tsai, J.-W. [Institute of Ecology and Evolutionary Ecology, China Medical University, Taichung 40402, Taiwan (China); Ju, Y.-R. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Liao, C.-M., E-mail: cmliao@ntu.edu.t [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2010-05-15

170

Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam  

International Nuclear Information System (INIS)

The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

171

Seasonal fluctuations in water repellency and infiltration in a sandy loam soil after a forest fire in Galicia (NW Spain  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this work was to analyze, after a wildfire of moderate severity, the temporal fluctuations in water repellency and infiltration in a sandy loam soil under a mixed plantation of pine and eucalyptus and the comparison with an adjacent area not affected by the fire. In the burnt area and in a neighboring area not affected by the fire were collected during one year (1, 4, 6, 8 and 12 months after the fire 10 soil samples along a transect of 18 m at four depths: 0-2, 2-5, 5-10 and 10-20 cm. Soil water repellency was determined using the water drop penetration time test (WDPT test and the infiltration was measured with a mini-disc infiltrometer (pressure head h0 = -2 cm.The results show a temporal pattern of soil water repellency in the burnt and unburnt areas. Significant correlations between water repellency and soil moisture were observed, with higher correlation coefficients in the unburned area and in the surface soil layer.Soil water infiltration was significantly lower than would be expected by the coarse texture of the soil in both burnt and unburnt areas. Temporal fluctuations in unburnt soil infiltration seem to be clearly related to the transient nature of the soil water repellency, with no infiltration in samples extremely repellent. In the burned area, the soil infiltration showed much more variability and temporal fluctuations appear to be less dependent on the persistence of water repellency and more dependent on environmental conditions.The unburnt area show significant and negative correlations of soil water repellency with hydraulic conductivity and sorptivity and positive of these two parameters with soil moisture. These relationships were not observed in the burnt area. The temporal fluctuations of soil water repellency have an evident impact on soil infiltration and seem to be more influent than the effects of fire.

M. Rodríguez-Alleres

2013-05-01

172

Evaluation of the Chemcatcher and DGT passive samplers for monitoring metals with highly fluctuating water concentrations.  

Science.gov (United States)

Passive sampling devices accumulate chemicals continuously from water and can provide time weighted average (TWA) concentrations of pollutants over the exposure period. Hence, they offer a number of advantages over other conventional monitoring techniques such as spot or grab sampling. The diffusive gradient in thin film (DGT) and the Chemcatcher passive samplers can be used to provide TWA concentrations of labile metals, but the approaches to their calibration differ. DGT uses diffusion coefficients of metals in the hydrogel layer, whereas Chemcatcher uses metal specific uptake rates, with both sets of values obtained under controlled laboratory conditions with constant aqueous metal concentrations. However, little is known of how such samplers respond to fluctuating concentrations. We evaluated the responsiveness of these two passive sampling devices to rapidly changing concentrations of Cd, Cu, Ni, Pb and Zn in natural freshwater, over a relatively short deployment time. Maximum metal concentrations in water were varied between 70 and 140 microg L(-1). Experiments were carried out in a tank with a rotating carousel system and filled with Meuse river water, allowing a degree of control over experimental conditions while using natural river water. Fluctuating concentrations were obtained by stepwise addition of standard solutions of the metals. The reliability and accuracy of the TWA concentrations measured by the samplers were assessed by comparison with concentrations of the metals in spot samples of water taken regularly over the deployment period. The spot samples of water were either unfiltered (total), filtered (0.45 microm) or ultrafiltered (5 kDa). Predictive speciation modelling using the visual MINTEQ programme was also undertaken. There was reasonable agreement between the TWA concentrations of Cd and Ni obtained with Chemcatcher and DGT and the total Cd and Ni concentrations measured in repeated unfiltered spot samples. For elements (i.e. Cu, Pb, Zn) that associate to a significant degree with suspended solids, colloids or dissolved organic carbon, or form complexes with large organic ligands, optimum agreement was with the filtered or ultrafiltered fractions and with the predicted inorganic and inorganic-fulvic acid associated fractions. While Chemcatcher-based TWA concentration ranges for Cu and Zn were in best agreement with the total filtered fraction, there was lack of agreement for Pb. The combined use of DGT devices with open pore (OP) and restricted pore (RP) gels allowed the labile fraction of metal associated with large organic ligands or DOC to be differentiated and quantified, since this is available to DGT OP but unable to diffuse into the DGT RP. This evaluation of the two sampling devices clearly demonstrated their ability to react reliably to transient peaks in concentration of metal pollutants in water and indicated where future efforts are needed to improve calibration data. Such samplers may prove valuable in responding to the monitoring requirements of the European Union's Water Framework Directive. PMID:17607387

Allan, Ian J; Knutsson, Jesper; Guigues, Nathalie; Mills, Graham A; Fouillac, Anne-Marie; Greenwood, Richard

2007-07-01

173

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies  

Energy Technology Data Exchange (ETDEWEB)

Water–tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with x{sub TBA} ? 0.03–0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at x{sub TBA} ? 0.05. We note that “islands” of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, x{sub TBA} ? 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level.

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman, E-mail: bbagchi@sscu.iisc.ernet.in [SSCU, Indian Institute of Science, Bangalore 560012 (India)

2014-05-21

174

Fluctuating micro-heterogeneity in water-tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies.  

Science.gov (United States)

Water-tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with x(TBA) ? 0.03-0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at x(TBA) ? 0.05. We note that "islands" of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, x(TBA) ? 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level. PMID:24852545

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

2014-05-21

175

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies  

International Nuclear Information System (INIS)

Water–tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with xTBA ? 0.03–0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at xTBA ? 0.05. We note that “islands” of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, xTBA ? 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level

176

Development and evaluation of a water level proportional water sampler  

Science.gov (United States)

We developed and adapted a new type of sampler for time-integrated, water level proportional water quality sampling (e.g. nutrients, contaminants and stable isotopes). Our samplers are designed for sampling small to mid-size streams based on the law of Hagen-Poiseuille, where a capillary (or a valve) limits the sampling aliquot by reducing the air flux out of a submersed plastic (HDPE) sampling container. They are good alternatives to battery-operated automated water samplers when working in remote areas, or at streams that are characterized by pronounced daily discharge variations such as glacier streams. We evaluated our samplers against standard automated water samplers (ISCO 2900 and ISCO 6712) during the snowmelt in the Black Forest and the Alps and tested them in remote glacial catchments in Iceland, Switzerland and Kyrgyzstan. The results clearly showed that our samplers are an adequate tool for time-integrated, water level proportional water sampling at remote test sites, as they do not need batteries, are relatively inexpensive, lightweight, and compact. They are well suited for headwater streams - especially when sampling for stable isotopes - as the sampled water is perfectly protected against evaporation. Moreover, our samplers have a reduced risk of icing in cold environments, as they are installed submersed in water, whereas automated samplers (typically installed outside the stream) may get clogged due to icing of hoses. Based on this study, we find these samplers to be an adequate replacement for automated samplers when time-integrated sampling or solute load estimates are the main monitoring tasks.

Schneider, P.; Lange, A.; Doppler, T.

2013-12-01

177

Conductances, Conductance Fluctuations, and Level Statistics on the Surface of Multilayer Quantum Hall States  

CERN Document Server

The transport properties on the two-dimensional surface of coupled multilayer heterostructures are studied in the integer quantum Hall states. We emphasize the criticality of the surface state and the phase coherent transport properties in the thermodynamic limit. A new, stable numerical algorithm for large scale conductance calculations in the transfer matrix approach is discussed in detail. It is then applied to a directed network model describing the quantum mechanical tunneling and impurity scattering of the multilayer edge states. We calculate the two-probe conductance in the direction parallel to the external magnetic field, its fluctuations and statistical distributions as a function of the interlayer tunneling strength. Using finite size scaling, the asymptotic scaling functions of the ensemble averaged conductance and the conductance fluctuations are calculated for a fixed aspect ratio and found to be in remarkable agreement with the analytical results obtained using the supersymmetric nonlinear $\\si...

Plerou, V; Plerou, Vasiliki; Wang, Ziqiang

1998-01-01

178

Fluctuation studies at the subnuclear level of matter: Evidence for stability, stationarity, and scaling  

International Nuclear Information System (INIS)

It is pointed out that the concepts and methods introduced by Bachelier and by Mandelbrot to finance and economics can be used to examine the fluctuations observed in high-energy hadron production processes. Theoretical arguments and experimental evidence are presented which show that the relative variations of hadron numbers between successive rapidity intervals are non-Gaussian stable random variables, which exhibit stationarity and scaling. The implications of the obtained results are discussed

179

Gravimetric response of water table fluctuations in the Sahelian Diffa site (East Niger): local effects including poro-elasticity  

Science.gov (United States)

The GHYRAF project (Gravimetry and HYdrology in AFrica) is devoted to a regional study of the relationship between hydrological and gravimetric signals in the Western African Monsoon area. Three sites are monitored in a decreasing pluviometric gradient: Djougou (North Benin), Wankama (Niamey area) and Bagara (Eastern Niger) with annual rainfalls amounting to 1200 mm, 600 mm and 350 mm, respectively. The Diffa/Bagara site is located 640m away from the Yobé temporary river, a tributary of Lake Chad fed by rainfall on the Jos Plateau (Nigeria) and that is generally flowing between mid July and January. Apart from this period, the river bed includes a series of ponds that form the top of the aquifer and that are pumped for intensive irrigated cropping. The 50m thick uppermost unconfined aquifer is locally recharged by the Yobé River and is flowing northwards. It has been explored by geophysical methods involving RMS and TDEM soundings, which provided information on its porosity and electrical conductivity, respectively. A series of nearly 50 holes drilled down to a 10 m depth in the Bagara area allowed to define the detailed sedimentary structure of the aquifer. It consists mainly of fluvial deposits with alternating layers of fine sands, coarse grained sands and clays. The sedimentary pile includes clayed layer of centimetric to metric thickness with a mean lateral extension of 300 m. The groundwater level is monitored by a series of 4 piezometers located at 25 m, 270 m, 500 m and 640 m from the river axis. The shape of the piezometric curve at the Bagara station is 0.4 m amplitude sinusoid and presents a maximum level at mid January and a minimum one near mid July. Clearly, water level fluctuations are governed by infiltration from the Yobe river with an offset controlled by the distance to it. With the 20% porosity measured by MRS, this would imply a nearly 30 nms-2 gravimetric signal, which is in fair agreement with the observed amplitude. However both the observed gravimetic signal and the results of the global hydrological model GLDAS are offset with respect to the piezometric one. In order to assess the influence of local effects, the groundwater level is modeled with the USGS finite-difference ModFlow code using different properties sets of the aquifer deduced from statistical analysis of drill-holes data. Poroelasticity effects resulting from variable saturation of the clay layers observed near the water level on the Bagara site are assessed. The ability of gravity data for monitoring annual and long term water level changes in the uppermost aquifer is then discussed.

Hector, B.; Genthon, P.; Le Coz, M.; Hinderer, J.; Chalikakis, K.; Descloitres, M.

2010-12-01

180

GNSS-Reflectometry based water level monitoring  

Science.gov (United States)

Due to climate changing conditions severe changes in the Mekong delta in Vietnam have been recorded in the last years. The goal of the German Vietnamese WISDOM (Water-related Information system for the Sustainable Development Of the Mekong Delta) project is to build an information system to support and assist the decision makers, planners and authorities for an optimized water and land management. One of WISDOM's tasks is the flood monitoring of the Mekong delta. Earth reflected L-band signals from the Global Navigation Satellite System show a high reflectivity on water and ice surfaces or on wet soil so that GNSS-Reflectometry (GNSS-R) could contribute to monitor the water level in the main streams of the Mekong delta complementary to already existing monitoring networks. In principle, two different GNSS-R methods exist: the code- and the phase-based one. As the latter being more accurate, a new generation of GORS (GNSS Occultation, Reflectometry and Scatterometry) JAVAD DELTA GNSS receiver has been developed with the aim to extract precise phase observations. In a two week lasting measurement campaign, the receiver has been tested and several reflection events at the 150-200 m wide Can Tho river in Vietnam have been recorded. To analyze the geometrical impact on the quantity and quality of the reflection traces two different antennas height were tested. To track separately the direct and the reflected signal, two antennas were used. To derive an average height of the water level, for a 15 min observation interval, a phase model has been developed. Combined with the coherent observations, the minimum slope has been calculated based on the Least- Squares method. As cycle slips and outliers will impair the results, a preprocessing of the data has been performed. A cycle slip detection strategy that allows for automatic detection, identification and correction is proposed. To identify outliers, the data snooping method developed by Baarda 1968 is used. In this context, issues related to the stochastic modeling of GPS observations are addressed and a first model is proposed. First results of water level derivation with precisions below decimeter level are presented. These results could then be used as an approximation for the next computation step: the ambiguities fixing.

Beckheinrich, Jamila; Schön, Steffen; Beyerle, Georg; Apel, Heiko; Semmling, Maximilian; Wickert, Jens

2013-04-01

 
 
 
 
181

Temporal scaling properties and spatial synchronization of spontaneous blood oxygenation level-dependent (BOLD) signal fluctuations in rat sensorimotor network at different levels of isoflurane anesthesia.  

Science.gov (United States)

Spontaneous fluctuations in the blood oxygenation level-dependent (BOLD) MRI signal during the resting state are increasingly being studied in healthy and diseased brain in humans and animal models. Yet, the relationship between functional brain status and the characteristics of spontaneous BOLD fluctuations remains poorly understood. In order to obtain more insights into this relationship and, in particular, the effects of anesthesia thereupon, we investigated the spatial and temporal correlations of spontaneous BOLD fluctuations in somatosensory and motor regions of rat brain at different inhalation levels of the frequently applied anesthetic isoflurane. We found that the temporal scaling, characterized by the Hurst exponent (H), showed persistent behavior (H?>?0.5) at 0.5-1.0% isoflurane. Furthermore, low-pass-filtered spontaneous BOLD oscillations were correlated significantly in bilateral somatosensory and bilateral motor cortices, reflective of interhemispheric functional connectivity. Under 2.9% isoflurane anesthesia, the temporal scaling characteristics approached those of Gaussian white noise (H?=?0.5), the relative amplitude of BOLD low-frequency fluctuations declined, and cross-correlations of these oscillations between functionally connected regions decreased significantly. Loss of interhemispheric functional connectivity at 2.9% isoflurane anesthesia was stronger between bilateral motor regions than between bilateral somatosensory regions, which points to distinct effects of anesthesia on differentially organized neuronal networks. Although we cannot completely rule out a possible contribution from hemodynamic signals with a non-neuronal origin, our results emphasize that spatiotemporal characteristics of spontaneous BOLD fluctuations are related to the brain's specific functional status and network organization, and demonstrate that these are largely preserved under light to mild anesthesia with isoflurane. PMID:20669170

Wang, Kun; van Meer, Maurits P A; van der Marel, Kajo; van der Toorn, Annette; Xu, Lijuan; Liu, Yingjun; Viergever, Max A; Jiang, Tianzi; Dijkhuizen, Rick M

2011-01-01

182

Schlieren technique for the measurement of low-level concentration fluctuations.  

Science.gov (United States)

A device for the measurement of concentration fluctuations in flowing gases which can be used to establish and control the degree of mixing is described. The design is based on an improved laser-schlieren technique combined with photometric detection. The device operates on-line and has high sensitivity and fast response. A quantitative sensitivity evaluation is made and checked experimentally. The device is used to characterize the performance of some simple mixing configurations. The detection limits for various gas mixtures are given. PMID:18699671

Shilo, K; Appelbaum, G; Noter, Y

1979-09-01

183

Immersion in CO2-rich water containing NaCl diminishes blood pressure fluctuation in anesthetized rats.  

Science.gov (United States)

Remarkably, bathing in hot springs containing high concentrations of carbon dioxide (CO(2)) influences cardiovascular function more than bathing in fresh water. The CO(2)-enriched water in hot springs generally contains many salts, whose interactions remain unknown. We separately evaluated the actions of individual factors in CO(2)-enriched water and confirmed that CO(2) and NaCl have combined effects on blood pressure fluctuations in anesthetized rats. Animals equipped with sensor probes to monitor body temperature, skin blood flow and arterial blood pressure were immersed in bathwater (35 degrees C) containing CO(2) with NaCl, KCl or sucrose. The effects of these factors on cardiovascular function were evaluated using power-spectral analysis of fluctuations in blood pressure and heart rate. Compared with immersion in tap water, heart rate and skin vascular resistance were reduced during immersion in CO(2)-enriched water irrespective of the presence of other components. In terms of the very low frequency range (0.02-0.195 Hz), the power of blood pressure fluctuation during immersion was significantly reduced when the CO(2)-enriched water contained more than 1.5% NaCl but was not influenced by other components of similar osmotic pressure and the same specific gravity. The results indicated that the coexistence of CO(2) and sodium ions in bathwater reduce blood pressure fluctuations, and suggested that this combination effect of CO(2) and salt contributes to the sedative effect on human cardiovascular functions while bathing in CO(2)-hot springs. PMID:17569993

Yamamoto, Noriyuki; Hashimoto, Masaaki

2007-12-01

184

Construction of new reactor pool water level  

International Nuclear Information System (INIS)

One of the most important parameter in reactor safety system is a continuous measurements of the reactor pool water level, this measurement should be accurate and sensitive to any change. The existing system became unreliable beacuse of the aging, it needs continuous calibration and maintenance. For this reason a new modern system was designed and built. It consists of differentail pressure transmitter with its power supply from which the output signal is displayed on a digital panel meter via some electronic cards. The new system was tested in the laboratory, then the old system was replaced by new one, the later proved to be reliable and accurate

185

Brunhes Evolution of the Belize Mixed Siliciclastic Carbonate Margin: Source to Sink Dynamics Relative to Glacial-Interglacial Sea Level Fluctuations  

Science.gov (United States)

Mixed siliciclastic carbonate systems are developed on continental margins where significant volumes of terrigenous sand and mud interact with shallow water tropical carbonate barrier reefs and banks. These systems represent highly dynamic environments, directly influenced by sea level fluctuations and climatic changes. In current sequence stratigraphy models, neritic carbonates flourish, exporting sediments to the basins during sea level highstands, while siliciclastic input to the basins is maximum during lowstands. In contrast, this study demonstrates that siliciclastic and carbonate sedimentation is not in phase with late Quaternary glacial-interglacial lowstand/highstand cycles on the central Belize margin. This study is based on the analyses of a well-dated continuous 37.7 m long piston core, MD02 2532, collected 3 km offshore the central Belize Barrier reef in the distal slope of Gladden Basin at 333 m of water depth by the R/V Marion Dufresne (IPEV). A robust chronology is established using high resolution planktic oxygen isotope stratigraphy, anchored by several nannofossil stratigraphic and tephrochronologic markers, as well as radiocarbon ages in the upper part of the core, and demonstrates that the core represents most of the Brunhes (about 0.7 My). The upper 26m of MD02 2532 penetrated five subunits of the distal portion of a sedimentary wedge, likely corresponding to interglacial intervals from Marine Isotope Stage (MIS) 11 to MIS 1 (Holocene), while the lower 11.7m recovered the upper portion of an underling subparrallel reflector seismic unit. Bulk carbonate percent values cyclically vary down the core; low values of 40 to 50% typically occur during the interglacial to glacial transitions, whereas high values of 70 to 80% typically occur at the glacial to interglacial transitions. The Holocene interval is characterized by the highest values observed in the entire core, reaching 82-83%. Calculated siliciclastic fluxes to the slope are greatest during early sea level regressions, whereas the lowest values occur during transgressions and early highstands. In contrast, carbonate fluxes are maximum during transgressions and early highstands. These results show that the late Quaternary is an ideal interval to determine the timing relative to sea level fluctuations of siliciclastic and carbonate sediment maximum fluxes into slope and basinal environments and, therefore, to test some basic sequence stratigraphic principles, because the timing and amplitude of the late Quaternary sea level fluctuations are independently well established.

Olson, B. E.; Droxler, A. W.; Dickens, G.; Beaufort, L.

2004-12-01

186

Monitoring system for reactor water level  

International Nuclear Information System (INIS)

Purpose: To enable accurate judgement for reactor water level by measuring flow rate, temperature, pressure and the like of coolants flowing in and out of a BWR type reactor. Constitution: Flow rate, temperature and pressure are measured for all of the coolants flowing in and out of a reactor. The flowing-out coolants are measured in both vapor phase and liquid phase. These data are inputted into a computer, in which they are calibrated in comparison with the indication of a level detector during normal operation, or coolant amount in the reactor and the energy in the reactor are calculated upon abnormal stage, and displayed on a Braun tube. (J.P.N.)

187

Water level response in back-barrier bays unchanged following Hurricane Sandy  

Science.gov (United States)

28-30 October 2012, Hurricane Sandy caused severe flooding along portions of the northeast coast of the United States and cut new inlets across barrier islands in New Jersey and New York. About 30% of the 20 highest daily maximum water levels observed between 2007 and 2013 in Barnegat and Great South Bay occurred in 5 months following Hurricane Sandy. Hurricane Sandy provided a rare opportunity to determine whether extreme events alter systems protected by barrier islands, leaving the mainland more vulnerable to flooding. Comparisons between water levels before and after Hurricane Sandy at bay stations and an offshore station show no significant differences in the transfer of sea level fluctuations from offshore to either bay following Sandy. The post-Hurricane Sandy bay high water levels reflected offshore sea levels caused by winter storms, not by barrier island breaching or geomorphic changes within the bays.

Aretxabaleta, Alfredo L.; Butman, Bradford; Ganju, Neil K.

2014-05-01

188

[Fluctuations in the level of progesterone in the peripheral blood of nutria during pregnancy].  

Science.gov (United States)

The fluctuations in the concentrations of progesterone in peripheral blood of three intact coypus and three coypus after natural mating were investigated for the period of four months. Immediately after mating the concentrations of progesterone are low (1.5-2.4 ng.ml-1), the maximum values reach the peak between the 14th and 15th week of gravidity (12.50-20.72 ng.ml-1), whilst there is almost no change in the intact females. On the last days of gravidity the values of progesterone decrease rapidly and they are very low on the day of parturition (1.0-2.5 ng.ml-1). The concentration of progesterone in the blood plasma of intact females in the test period is low (0.09-3.18 ng.ml-1). PMID:2734993

Jakubicka, I; Barta, M; Nitray, J; Szeleszczuková, O

1989-04-01

189

Population-level mating patterns and fluctuating asymmetry in swordtail hybrids  

Science.gov (United States)

Morphological symmetry is a correlate of fitness-related traits or even a direct target of mate choice in a variety of taxa. In these taxa, when females discriminate among potential mates, increased selection on males should reduce fluctuating asymmetry (FA). Hybrid populations of the swordtails Xiphophorus birchmanni and Xiphophorus malinche vary from panmictic (unstructured) to highly structured, in which reproductive isolation is maintained among hybrids and parental species. We predicted that FA in flanking vertical bars used in sexual signalling should be lower in structured populations, where non-random mating patterns are observed. FA in vertical bars was markedly lower in structured populations than in parental and unstructured hybrid populations. There was no difference in FA between parentals and hybrids, suggesting that hybridisation does not directly affect FA. Rather, variation in FA likely results from contrasting mating patterns in unstructured and structured populations.

Culumber, Zachary W.; Rosenthal, Gil G.

2013-08-01

190

Prognostic Values of Fluctuations in Serum Levels of Alanine Transaminase in Inactive Carrier State of HBV Infection  

Science.gov (United States)

Background: Current guidelines introduce periodic monitoring of serum alanine transaminase (ALT) as the first-line modality in follow-up patients, with a hepatitis B virus (HBV) inactive carrier state. Objectives: This study aimed to determine the incidence rate and patterns of ALT fluctuations and prognostic values for the development of chronic HBV e antigen (HBeAg)-negative hepatitis B (CHB), HBV surface antigen (HBsAg) seroclearance, and liver-related complications. Patients and Methods: Treatment-naïve patients with a chronic HBV infection, HBeAg(-)/HBeAb(+), normal ALT levels, and HBV DNA upper limit of normal (ULN, i.e. 40 IU/L) was detected in 103 (25.8%) patients, with an annual incidence rate of 2.9%. ALT elevation was associated with; male gender, age, and higher serum ALT levels at study entry. Among the cases of ALT elevations, 16 (15.5%) patients had ALT levels > 2 × ULN. There were 38 (36.9%) patients who had ALT levels that remained > ULN over six months, and 21 (20.4%) patients experienced at least two episodes of ALT elevations. In 15 (14.6%) patients, elevated ALT levels were associated with increased HBV replication (i.e. HBV DNA > 2 000 IU/mL) and these were considered as CHB. However, elevation of ALT levels, even in the absence of HBV replication, increased the risk for the development of CHB up to 8-fold in prospective follow-ups. HBsAg seroclearance, cirrhosis, and hepatocellular carcinoma were detected in 43 (10.8%), 4 (1%), and 1 (0.25%) patients, respectively. Conclusions: Fluctuations in serum ALT levels may change the prognosis of a HBV inactive carrier state. PMID:24829590

Farzi, Hossein; Ebrahimi Daryani, Nasser; Mehrnoush, Leila; Salimi, Shima; Alavian, Seyed Moayed

2014-01-01

191

Diurnal lamotrigine plasma level fluctuations: clinical significance and indication of shorter half-life with chronic administration  

DEFF Research Database (Denmark)

For therapeutic monitoring of antiepileptic drugs (AEDs), morning trough levels (MTLs) are generally used. For specific questions like verification of breakthrough seizures or reported toxicity, however, other measures such as minimal and maximal concentrations (C(min), C(max)) can be important and may require daily profiles. For clinical reasons, 20 daily profiles of lamotrigine (LTG) plasma levels were determined in nine patients. The results revealed fluctuations exceeding those expected from its elimination half-life (t(1/2)) of 22h as reported in the literature. Patients on twice-daily regimens without pharmacokinetic interactions exhibited C(min)/C(max) ratios between 0.62 and 0.69. Fluctuations were smaller in those co-medicated with valproate, and reached a ratio of 0.55 in those co-medicated with phenobarbital. The C(max) was as much as 58% above the MTL. Therefore, verification of complaints indicating toxicity requires determination of drug levels when the symptoms are present. Our findings indicate that the t(1/2) of LTG with chronic treatment is shorter than generally assumed, and suggest that a slow-release formulation could be helpful in achieving full seizure control in patients with a narrow individual therapeutic index for LTG Udgivelsesdato: 2008/10

Nielsen, K.A.; Dahl, M.

2008-01-01

192

Evaluation of pore water pressure fluctuation around an advancing longwall face  

Science.gov (United States)

Large deformations that accompany longwall mining result in complex spatial and temporal distributions of changes in undrained pore fluid pressures around the advancing face. These seemingly anomalous changes are recorded in the rapid water level response of undermined and adjacent wells, and may be explained in the short-term as a undrained poroelastic effect. A three-dimensional finite element model is applied to define anticipated pore fluid response both around the advancing mining face, at depth, and in the near surface region. The results are carefully verified against the response recorded at three well-instrumented longwall sites. Pore pressure changes are indexed directly to volumetric strains defining zones of significant depressurization in the caving zone and in zones of extension adjacent to the subsidence trough on the ground surface. Overpressurization occurs in the abutment region, at panel depth, and in the surface compressive zone immediately inside the angle-of-draw. These results are confirmed with available, short-term water level response data, defining the strongly heterogeneous spatial response and the significance of well depth on anticipated water level response.

Liu, J.; Elsworth, D.

193

Fluctuations of Phytoplankton Community in the Coastal Waters of Caspian Sea in 2006  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: The Caspian Sea ecosystem has been suffered with many problems since 1980s. Aanthropogenic pollution from heavy metals, hydrocarbons, pesticides, changes in the quantity of nutrient inputs by rivers, are significant threats to biodiversity and biological resources such as plankton structure in the Caspian Sea. According to the significant of phytoplankton community in marine system. The state of the fluctuations of phytoplankton communities of the southwestern Caspian Sea was investigated and compared with the findings of before 2006. Approach: Phytoplankton abundance and species composition of the Caspian Sea were evaluated by using samples collected at 12 stations along three transects. Samplings were conducted seasonal in 2006 at 5, 10, 20 and 50 m depth were fixed for each transect in the southwestern Caspian Sea. Results: A total of 39 species phytoplankton species were distinguished during 2006, the annual phytoplankton abundance were calculated as 57, 300±15,550 cells.l-1, which ranged from 89, 250±35, 062 cells.l-1 in September to 16, 200±6,664 cells.l-1 in February. The diatoms formed more than half of the total abundance (61% while cyanophytes were the second important group in view of contribution to total phytoplankton (26% in 2006. The study showed that diatoms Thalassionema nitzschioides, Cyclotella meneghiniana and cyanophyte Osillatoria sp. numerically dominated in this area. Conclusion: The study revealed that diatoms were higher than other groups of phytoplankton in 2006. The hydrology variation, increased fresh water inflow via rivers and a rise in nutrients concentrations have played important roles in blooming of phytoplankton species, e.g., the diatoms in this study, which is also known from other marines. Similar studies on determination of the effects of environmental degradation on phytoplankton and hydrological processes should be taken into account in near future.

Siamak Bagheri

2011-01-01

194

Determination of the relative discharge rate from a uranium mine tailings pond by water level measurements  

International Nuclear Information System (INIS)

A method using water level measurements only was developed to determine the effectiveness of the revegetation or other selected materials as a seepage reducing agent for uranium mine tailings ponds. The effluence and thus the rate of the surface and subsurface water contamination around the tailings pond is directly proportional to the water head difference existing between the water tables inside and outside the pond. The method uses water level measurements taken before and after revegetation or taken simultaneously under revegetated and barren sections of the pond. Effluent rate variation of +- 1% can be detected with the measuring technique. For this reason the method is suitable for monitoring the fluctuation of the contamination rate from abandoned uranium mine tailing ponds. The method can predict the performance of the revegetation or other selected seepage reducing material before the commitment of any large expenditure

195

Water Pollution by Surfactants: Fluctuations Due to Tourism Exploitation in a Lagoon Ecosystem  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes recent levels of surfactants measured in a coastal lagoon ecosystem highly stressed by human activites: the Orbetello lagoon (Southern Tuscany, Italy, Ramsar Site IT008. Significance of difference among concentrations measured before and after summertime are explored in order to evaluate effects related to tourism exploitation. Among surfactants, methylene blue active anionic substances (MBAS are selected as tracers for untreated discharges originated by domestic and urban activities. Water samplings were performed in 2011 following a randomly replicated nested logic model (n = 144. MBAS mean level of 0.070 mg.L–1 (–1 and 0.530 mg.L–1 (–1 are respectively recorded in June and October evidencing a significant increase after the touristic season. Possible MBAS concentration phenomena could be induced by different evaportaton rates among sampling stations and between winter and summer seasons and were evaluated, in this study, using water salinity as possible factor affecting samples segregations. Results evidence that differences of MBAS levels related to evaporation rates are trascurabile if compared to the variability induced by the presence of not-collected wastewater hot-spot pollution sources located closed around the urban settlement and along sandbars. Measured levels of surfactants could act negatively on living organisms both animals and plants contributing to affect Orbetello lagoon biodiversity. In this ecosystem, after the complete reorganization of urban wastewater treatment plants occured in 2008, further management actions should be focalized on reducing untreated sources of MBAS.

Silvano E. Focardi

2012-09-01

196

EFECTOS DE LA FLUCTUACIÓN DEL NIVEL DEL AGUA SOBRE LA ESTRUCTURA DEL ENSAMBLAJE DE ROTÍFEROS EN EL LAGO LARGO (SISTEMA YAHUARCACA - LLANURA DE INUNDACIÓN DEL RÍO AMAZONAS - COLOMBIA) / Effects of water level fluctuation on rotifers assemblage structure in Largo lake (Yahuarcaca sistem - river Amazon floodplain - Colombia)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Se realizó un reconocimiento taxonómico y estimación de la densidad en el ensamblaje de rotíferos en el lago Largo, del sistema de lagos Yahuarcaca, en la ribera colombiana del río Amazonas, a partir de muestreos en las fases hidrológicas de aguas bajas, ascenso y descenso. Se identificaron 68 espec [...] ies, 28 de ellas son nuevos registros para ambientes colombianos. Se encontró aumento en la riqueza en las épocas de ascenso y descenso, siendo mayor en la zona litoral respecto de la limnética, y la tendencia a mayor similitud taxonómica entre ambas zonas en el periodo de aguas bajas, debido al mínimo desarrollo de macrófitas en esta fase y la consecuente menor heterogeneidad espacial. Se observó el predominio de rotíferos con trofi adaptados para moler y triturar partículas (maleado y maleorramado) en las épocas de aguas bajas (Brachionus ahlstromi) y descenso (Filina saltator) y en la época de ascenso de Polyarthra vulgaris, con trofi adaptado para perforar y succionar fluidos de algas y otros organismos (virgado) y apéndices que favorecen la rápida natación. En general, se establecieron posibles relaciones entre la riqueza y la densidad de rotíferos con cambios en características como el desarrollo de vegetación acuática en el litoral, profundidad del lago, nivel de conectividad con los otros lagos del sistema Yahuarcaca, influencia de aguas blancas del Amazonas y negras de origen local, potenciales recursos nutricionales y depredadores, y posible efecto de arrastre por la corriente. Abstract in english We conducted a taxonomic recognition and density estimation of the assemblage of rotifers in Lake Largo, in the floodplain system of Yahuarcaca, connected with the Amazon River, in Colombia. Two samplings were made for each hydrological phase (low water, filling and draining phases); 68 species were [...] identified, 28 of them are new records for Colombian environments. We found an increased in species richness in the filling and draining phases, being higher in the littoral than in limnetic region, and a tendency to a higher taxonomic similarity between the two areas during low water periods, due to the reduced macrophyte development in that period and consequent reduced spatial heterogeneity. We observed the predominance of rotifers with trophi adapted for grinding and crushing particles (malleate and malleorramate) in low water phase (Brachionus ahlstromi) and draining phase (Filina saltator) and Polyarthra vulgaris, with a trophi adapted to pierce and suck out the fluids of algae and other organisms (virgate), and appendices that support the rapid swimming, at the filling phase. In general, we established possible relations between rotifers richness and density with changes in characteristics as the development of aquatic vegetation in the littoral zone, lake depth, level of connectivity with other lakes of Yahuarcaca system, level of influence of white waters from the Amazon river, and black waters from local origin, potentials nutritional resources and predators, and drag effect by the current.

CAMILO, ANDRADE-SOSSA; MIGDALIA, GARCÍA-FOLLECO; CARLOS A., RODRÍGUEZ-MUNAR; SANTIAGO R., DUQUE; EMILIO, REALPE.

2011-12-30

197

The level of non-thermal velocity fluctuations deduced from Doppler spectroscopy and its role on TJ-II confinement  

CERN Document Server

The goal of this investigation is to study, in the line of previous works, the level of velocity fluctuations in different scenarios of the TJ-II stellarator. The method followed consists in measuring the apparent Doppler temperature of C4+ and protons with high spectral resolution techniques with spatial resolution. The level of turbulent velocities in the plasma has been deduced from the difference observed between the apparent temperature of both species, following a method previously presented and borrowed from astrophysics. The study of this difference, as a function of plasma density and injected power, provides a way to explore if this turbulence plays any role in the confinement of the hot TJ-II plasma.

Zurro, B

2009-01-01

198

Investigation of wall temperature fluctuations by visualization tests for steam-water two-phase flow in the pressurizer spray piping  

International Nuclear Information System (INIS)

In a PWR plant, a steam-water two phase flow may possibly exist in the pressurizer spray pipe under a rated power operating condition since the flow rate of the spray water is not sufficient to fill the horizontal section of the pipe completely. Under such thermally stratified two phase flow conditions, the initiation of high cycle fatigue cracks is suspected to occur due to cyclic thermal stress fluctuations caused by oscillations of the water surface, which cannot be detected by the measurement of temperature on outer surface of the pipe. In order to clarify the flow and thermal conditions in the pressurizer spray pipe and assess their impact on the pipe structure, an experiment was conducted for a steam-water flow at a low flow rate using a mock-up pressurizer spray pipe. By measuring inner wall temperature fluctuations, continuous temperature fluctuations, which were around 0.2 times of the steam water temperature difference in the maximum range, were observed at the inclined section where the water surface contacted the pipe wall. Then, we investigated the causes of the fluctuations by visualization tests. As a result of the experiment, it seemed that wall temperature fluctuations were not caused by waves on the water surface, but were caused by liquid temperature fluctuations a layer below the steam-water interface. The influence of a small amount of non-condensable gas dissolved in the reactor coolant on the wall temperature fluctuations was investigated by injecting air into the experimental loop. The liquid temperature fluctuations in the layer which caused wall temperature fluctuations were attenuated after air was injected. (author)

199

Model parameter uncertainty reduction of time series models using data-based learning algorithms for simulating groundwater level fluctuations  

Science.gov (United States)

Estimation of groundwater level (GWL) fluctuation has been an important and challenging topic in hydrology. In this study, time series models for GWL fluctuation were developed using artificial neural network (ANN) and support vector machine (SVM). This study defines 'prediction' as the estimation of GWL when the model includes past GWL measurements in input components and 'forecast' when it uses past GWL estimated values. In order to reduce model parameter uncertainty for GWL forecast, the classic model building process was modified introducing weighting factors to the objective function. The developed models were applied to rainfall and GWL time series data of 5 groundwater monitoring stations in National Groundwater Monitoring Network (NGMN) of Korea: HC, MH, YH, PC and CS station, in order to compare the models' performance for prediction and forecast of GWL fluctuation and evaluate the impact of the weighting factors on model stability. Results showed that root mean squared error (RMSE) values ranged from 0.05 m to 0.11 m for the GWL prediction and 0.072 m to 0.159 m for the GWL forecast. Correlation coefficient values were over 0.91 and 0.87 for the prediction and forecast, respectively. The ANN model was more frequently selected than SVM for the prediction, whereas vice versa for the forecast. In the present study, FC-TS value was defined as RMSE values in the forecast to testing stage for examining the model parameter uncertainty. The FC-TS values decreased significantly when the weighting factors were utilized, which implies that use of the weighting factors reduced the uncertainty of the developed time series models.

Yoon, H.; Hyun, Y.; Lee, K.; Ha, K.; Ko, K.

2012-12-01

200

Secondary mineral evidence of large-scale water table fluctuations at Yucca Mountain, Nye County, Nevada  

International Nuclear Information System (INIS)

At Yucca Mountain, currently under consideration as a potential permanent underground repository for high-level radioactive wastes, the present-day water table is 500 to 700 m deep. This thick unsaturated zone (UZ) is part of the natural barrier system and is regarded as a positive attribute of the potential site. The USGS has studied the stable isotopes and petrography of secondary calcite and silica minerals that coat open spaces in the UZ and form irregular veins and masses in the saturated zone (SZ). This paper reviews the findings from the several studies undertaken at Yucca Mountain on its mineralogy

 
 
 
 
201

Fluctuation in the Levels of Immunoglobulin M and Immunoglobulin G Antibodies for Cardiolipin and ?2-Glycoprotein among Healthy Pregnant Women  

Science.gov (United States)

Objectives: Antiphospholipid antibodies fluctuate during a healthy normal pregnancy. This study aimed to investigate the levels of both immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies for cardiolipin and ?2-glycoprotein (?2GP) among healthy pregnant women. Methods: This study was conducted between May 2010 and December 2012. A total of 75 healthy Omani pregnant women with no history of autoimmune disease were investigated during their pregnancy and 90 days after delivery at the Armed Forces Hospital in Muscat, Oman. A control group of 75 healthy Omani non-pregnant women were also investigated as a comparison. Levels of IgM and IgG antibodies for both anti-cardiolipin antibodies (ACAs) and ?2GP were measured using a standard enzyme-linked immunosorbent assay. Results: The ACA IgM levels were significantly higher in the control group compared to the pregnant women (P <0.001). No significant differences were observed in the ACA IgM levels between the control group and the pregnant women after delivery. In contrast, ACA IgG levels were significantly higher during pregnancy and after delivery compared with those of the healthy control group (P = 0.007 and 0.002, respectively). The levels of ?2GP IgG were significantly higher during pregnancy than after delivery and in the control group (P = 0.001 and <0.001, respectively). Conclusion: In this study, ACA IgG levels increased during healthy pregnancies and after normal deliveries whereas ?2GP IgG levels increased transiently during the pregnancies. Both phenomena were found to be significantly associated with a transient decline in the levels of IgM specific for these antigens. Therefore, the levels of these antibodies may be regulated during a healthy pregnancy. PMID:25364550

Al-Balushi, Mohammed S.; Hasson, Sidgi S.; Said, Elias A.; Al-Busaidi, Juma Z.; Al-Daihani, Muna S.; Othman, Mohammed S.; Sallam, Talal A.; Idris, Mohammed A.; Al-Kalbani, Moza; Woodhouse, Nicholas; Al-Jabri, Ali A.

2014-01-01

202

Fluctuation of TeV to EeV Energy Muons and Induced Muon Showers in Water  

CERN Document Server

By using the integral method in the muon propagation through water, we calculate the range fluctuation of high and ultra high energy muons. Many authors divide all radiative processes into two parts, namely, the continuous part and radiative part in their Monte Carlo simulation in order to consider the fluctuation in the both ranges and energies of the muons, while we treat all stochastic processes as exactly as possible, without the introduction of the continuous parts in all stochastic processes. The validity of our Monte Carlo method is checked by the corresponding analytical method which is methodologically independent on the Monte Carlo procedure. Accompanied cascade showers are generated by the direct electron pair production, bremsstrahlung and photo-nuclear interaction. These showers are calculated by the exact Monte Carlo Method in one dimensional way. We report survival probabilities, range distributions and examples of individual muon behavior.

Okumura, Y; Misaki, A

2010-01-01

203

Annual fluctuations of endocrine-disrupting compounds at the lower end of the Lima River, Portugal, and in adjacent coastal waters.  

Science.gov (United States)

The Lima River is a Spanish–Portuguese water body. Notwithstanding the fact that the river incorporates protected natural areas, levels of endocrine-disrupting compounds (EDCs) within its waters have never been measured; such EDCs include the following: natural and pharmaceutical oestrogens (17?-estradiol, E1, and 17?-ethynylestradiol), industrial and household pollutants (4-octylphenol, 4-nonylphenol, and their monoethoxylates and diethoxylates, and bisphenol A), phytoestrogens (formononetin, biochanin A, daidzein, genistein), and phytosterols (namely, sitosterol). To obtain an understanding of levels of EDCs, water samples were taken from eight sampling sites along the river every 2 months during a 1-year period (2011). The water samples were preconcentrated (Oasis HLB cartridges), cleaned (silica cartridges), and analysed using gas chromatography. Results showed that levels of oestrogens and industrial and household pollutants were higher in summer than in other seasons. Although oestrogens were more abundant (approximately 40 ng/L) on the southern margin of the river, levels of other pollutants were higher (approximately 124 ng/L) in the north. Phytoestrogens and sitosterol showed clear seasonal fluctuations with higher amounts of formononetin (approximately 389 ng/L), biochanin A (approximately 160 ng/L), and sitosterol (?5 µg/L) measured in summer. The overall oestrogenic load, expressed in ethynylestradiol equivalents, was 18 ng/L for oestrogens, 0.5 ng/L for industrial and household pollutants, and 13 ng/L for phytoestrogens. Water physicochemical parameters indicate anthropogenic pollution because ?nitrites,nitrates (>1 mg/L) and phosphates (approximately 0.4 mg/L) were high. The study showed that the waters of the Lima River are subject to impacts and that levels of EDCs pose risks to the river’s biota. PMID:25015732

Rocha, Maria João; Cruzeiro, Catarina; Peixoto, Cristiana; Rocha, Eduardo

2014-10-01

204

Small-angle X-ray scattering study on the fluctuations of supercritical aqueous solution of n-pentane along the critical isotherm of water  

Science.gov (United States)

Fluctuation terms of the supercritical aqueous solutions of n-pentane, i.e., those of densities, concentrations, and their correlation terms, were evaluated by small-angle X-ray scattering intensity in combination with isothermal compressibility and partial molar volumes. The fluctuations increased significantly with the fluid density up to the region of middle density, ˜0.2 g cm-3, and then decreased at higher density. In the region where the fluctuations took maxima or minima, the density was lower than those of water critical density. The particle-number fluctuations of individual components obtained from the fluctuation terms show that water molecules are distributed more inhomogeneously than n-pentane, especially in the region of ˜0.3 g cm-3.

Morita, Takeshi; Murai, Hiromi; Kase, Syunsuke; Nishikawa, Keiko

2012-08-01

205

Sea-level fluctuations and coastal evolution in the state of Rio de Janeiro, southeastern Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O presente trabalho tem como objetivo investigar as variações do nível relativo do mar e a evolução costeira durante o Holoceno no litoral do Estado do Rio de Janeiro, com base em indicadores geológicos e biológicos. Realizou-se levantamento altimétrico, execução de sondagens e datações ao 14C na pl [...] anície costeira e em afloramentos de rochas de praia. A partir dos dados obtidos, construiu-se uma curva do nível relativo do mar para o Holoceno. Pela primeira vez na costa brasileira foi identificado um recorde negativo do nível relativo do mar, envolvendo a transição final do Pleistoceno e início do Holoceno. Após a transição, iniciou-se um processo relativamente rápido de subida do nível do mar. Há aproximadamente 8.500 anos cal A.P., o nível marinho, encontrava-se a - 0.5 m abaixo do nível atual. O “zero” (nível médio atual) foi ultrapassado pela primeira vez no Holoceno há cerca de 7.500 anos A.P. Entre 5.500 - 4.500 cal anos A.P, o nível relativo do mar atingiu o primeiro máximo holocênico com altura máxima de +2.50 m acima do atual. A descida do nível relativo do mar subseqüente ao máximo transgressivo, levou à construção de terraços marinhos, resultando na progradação da linha de costa até o presente. A maioria dos resultados corroboram dados já obtidos em outros segmentos da costa atlântica da América do Sul. Resultados aqui apresentados são consistentes com pesquisas anteriores e ajudam refinar o registro do nível relativo do mar Holoceno na costa brasileira. Abstract in english The present paper aims to investigate the relative sea-level and the coastal evolution during the Holocene in the Rio de Janeiro coastline, based on geological and biological indicators. Using topographic survey, excavation and coring, and 14C dating of these coastal deposits and beachrocks outcrops [...] , we have reconstructed a sea-level curve for the Holocene. For the first time on the Brazilian coast it was identified a negative record of relative sea-level during Late Pleistocene and Early Holocene transition. After the transition, a relatively rapid increase of sea-level began. At approximately at 8500 cal yr BP, the sea-level was 0.5 m below the current level, was overtaken for the first time in the Holocene, at approximately 7500 cal yr BP. The maximum level of +2.5 m was reached between 4770 and 4490 cal yr BP. At the point of maximum transgression, the sea-level began a general behavior of lowering until the present. These results confirm other data already obtained elsewhere along the Atlantic coast of South America. The results of this study are consistent with previous researches and they help to refine the Holocene sea-level record along the Brazilian coast.

JOÃO WAGNER A., CASTRO; KENITIRO, SUGUIO; JOSÉ C.S., SEOANE; ALINE M. DA, CUNHA; FABIO F., DIAS.

2014-06-01

206

Current-induced two-level fluctuations in pseudo spin-valves (Co/Cu/Co) nanostructures  

CERN Document Server

Two-level fluctuations of the magnetization state of pseudo spin-valve pillars Co(10 nm)/Cu(10 nm)/Co(30 nm) embedded in electrodeposited nanowires (~40 nm in diameter, 6000 nm in length) are triggered by spin-polarized currents of 10^7 A/cm^2 at room temperature. The statistical properties of the relaxation times between transitions from parallel to antiparallel magnetization states (and vice versa) reveal two effects with qualitatively different dependences on current intensity. The current appears to have the effect of a bias field, evaluated experimentally as the counteracting applied field that equalizes the mean relaxation times. When the energy profile is a symmetric double well, the effect of a current density of 10^7 A/cm^2 is to decrease the effective energy barrier by 1000 K. The bias field changes sign when the current polarity is reversed. The barrier is lowered, irrespective of the sign of the current.

Fabian, A C; Guisan, S S; Hoffer, X; Dubey, M; Gravier, L; Ansermet, J P; Wegrowe, J E

2003-01-01

207

Late Quaternary sedimentation off the Queensland continental margin (northeast Australia) in response to sea level fluctuations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Drilling during ODP Leg 133 offshore Cairns, northeast Queensland, provided a unique opportunity to document carbonate production and facies development on a mixed carbonate-siliciclastic margin. Recent studies have shown that variations in the sedimentology of Late Quaternary and Pliocene periplatform sediments (Schlager and James, 1978), deposited on continental slopes and in deep basins surrounding shallow carbonate platforms, are linked to changes in sea-level (Droxler et al., 1993; Schla...

Alexander, Ian T.

1996-01-01

208

Performance of broilers submitted to high CO2 levels during incubation combined with temperature fluctuations at late post-hatch  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Incubation represents around 1/3 of the life cycle of broilers of modern strains; therefore, the appropriate management of this period is crucial to ensure the quality of the neonate. An experiment evaluated the effect of carbon dioxide concentrations during incubation on the live performance, heart [...] morphology, and differential leukocyte count in the blood of broilers submitted to fluctuating temperatures between 35 and 42 days of age. In total, 2,520 fertile eggs were distributed according to a completely randomized design with four CO2 concentrations (4,000; 6,000; 8,000 and 10,000 ppm) during the first ten days of incubation, after which all eggs were incubated at the same CO2 level (4,000 ppm). After hatching, male chicks were placed in the experimental broiler houses, and at 35 days of age, 25 birds from each level of CO2 were separated and placed in cages to study the effect of cyclic temperature variations up to 42 days of age on their live performance, heterophil:lymphocyte ratio, and heart morphology. At 42 days of age, blood was collected for hematology and two birds per replicate were sacrificed and evaluated for ascites score and heart and liver relative weights. Heart morphology was assessed by analyzing digital images. In this experiment, hypercapnia during incubation and fluctuating temperatures during the growout did not affect mortality, ascites score, heart and liver relative weights, or heart characteristics (p>0.05). However, heterophill:lymphocyte ratio increased (p

JIM, Fernandes; C, Bortoluzzi; AFG, Esser; JP, Contini; PB, Stokler; D, Faust.

2014-09-01

209

Performance of broilers submitted to high CO2 levels during incubation combined with temperature fluctuations at late post-hatch  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Incubation represents around 1/3 of the life cycle of broilers of modern strains; therefore, the appropriate management of this period is crucial to ensure the quality of the neonate. An experiment evaluated the effect of carbon dioxide concentrations during incubation on the live performance, heart [...] morphology, and differential leukocyte count in the blood of broilers submitted to fluctuating temperatures between 35 and 42 days of age. In total, 2,520 fertile eggs were distributed according to a completely randomized design with four CO2 concentrations (4,000; 6,000; 8,000 and 10,000 ppm) during the first ten days of incubation, after which all eggs were incubated at the same CO2 level (4,000 ppm). After hatching, male chicks were placed in the experimental broiler houses, and at 35 days of age, 25 birds from each level of CO2 were separated and placed in cages to study the effect of cyclic temperature variations up to 42 days of age on their live performance, heterophil:lymphocyte ratio, and heart morphology. At 42 days of age, blood was collected for hematology and two birds per replicate were sacrificed and evaluated for ascites score and heart and liver relative weights. Heart morphology was assessed by analyzing digital images. In this experiment, hypercapnia during incubation and fluctuating temperatures during the growout did not affect mortality, ascites score, heart and liver relative weights, or heart characteristics (p>0.05). However, heterophill:lymphocyte ratio increased (p

JIM, Fernandes; C, Bortoluzzi; AFG, Esser; JP, Contini; PB, Stokler; D, Faust.

210

Effects of Water Levels on Productivity of Canada Geese in the Northern Flathead Valley, Final Report.  

Energy Technology Data Exchange (ETDEWEB)

The Fish and Wildlife Program of the Northwest Power Planning Council calls for wildlife mitigation at hydroelectric projects in the Columbia River System. Beginning April, 1984, the Bonneville Power Administration funded a study of the effects of the operation of Hungry Horse and Kerr Dams on the western Canada goose (Branta canadensis moffittii) inhabitating the Flathead Valley of northwest Montana. The study was conducted by personnel of the Montana Department of Fish, Wildlife and Parks (MDFWP), to: (1) identify the size and productivity of this population, (2) identify current habitat conditions and losses of nesting and brood-rearing areas, (3) describe the effects of water level fluctuations on nesting and brood-rearing, and (4) identify mitigation alternatives to offset these effects. Annual pair and nest surveys were used to document the location and fate of goose nests. The number of known nesting attempts varied from 44 in 1984 to 108 in 1985, to 136 in 1986 and 134 in 1987. Fifty-four percent of the annual meeting nesting effort took place on elevated sites which were secure from the flooding and dewatering effects of fluctuating water levels. An average of 15 nests were found on stumps in the remnant Flathead River delta, however, an area strongly influenced by the operation of Kerr Dam. Annual nest losses to flooding and predation attributable to fluctuations caused by the dam were recorded. 53 refs., 24 figs., 35 tabs.

Casey, Daniel

1987-08-01

211

Collective Switching and Inversion without Fluctuation of Two-Level Atoms in Confined Photonic Systems  

Science.gov (United States)

We demonstrate population inversion and sub-Poissonian excitation statistics of N two-level atoms in the context of collective resonance fluorescence. This occurs within photonic band gap and other confined photonic systems that exhibit sharp features in the optical density of states. When the deviation in the photon density of states between the Mollow spectral components is considerable, the atoms switch collectively from ground to excited states at a critical value of the applied laser field. This suggests a new mechanism of sub-Poissonian pumping of lasers, fast optical switching, and optical transistor action.

John, Sajeev; Quang, Tran

1997-03-01

212

Sea level fluctuations in central California at subtidal to decadal and longer time scales with implications for San Francisco Bay, California  

Science.gov (United States)

Sea level elevations from near the mouth of San Francisco Bay are used to describe the low-frequency variability of forcing of the coastal ocean on the Bay at a variety of temporal scales. About 90% of subtidal fluctuations in sea level in San Francisco Bay are driven by the sea level variations in the coastal ocean that propagate into the Bay at the estuary mouth. We use the 100-year sea level record available at San Francisco to document a 1.9 mm/yr mean sea level rise, and to determine fluctuations related to El Nino-Southern Oscillation (ENSO) and other climatic events. At time scales greater than 1 year, ENSO dominates the sea level signal and can result in fluctuations in sea level of 10-15 cm. Alongshore wind stress data from central California are also analyzed to determine the impact of changes in coastal elevation at the mouth of San Francisco Bay within the synoptic wind band of 2-30 days. At least 40% of the subtidal fluctuations in sea level of the Bay are tied to the large-scale regional wind field affecting sea level variations in the coastal ocean, with little local, direct wind forcing of the Bay itself. The majority of the subtidal sea level fluctuations within the Bay that are not related to the coastal ocean sea level signal are forced by an east-west sea level gradient resulting from tidally induced variations in sea level at specific beat frequencies that are enhanced in the northern reach of the Bay. River discharge into the Bay through the Sacramento and San Joaquin River Delta also contributes to the east-west gradient, but to a lesser degree. ?? 2007 Elsevier Ltd. All rights reserved.

Ryan, H.F.; Noble, M.A.

2007-01-01

213

Determination of heterogeneities in the hydraulic properties of a phreatic aquifer from tidal level fluctuations: a case in Argentina  

Science.gov (United States)

A well-known analytical solution of Jacob (1950) for groundwater flow due to tidal-wave propagation, together with field measurements along a complete tidal cycle and geological data, were used to evaluate the heterogeneities in the hydraulic properties of a phreatic aquifer located next to the River Ajo in the coastal plain environment of the southern sector of the Samborombon Bay wetland, Argentina. From the analysis of water-table fluctuations in a set of monitoring wells located along a riverbank-normal transect, it was possible to quantify the piecewise spatial variations of the hydraulic diffusivity of the phreatic aquifer. The results show the strong lateral variations of the sedimentary environment due to the influence of the different transport and deposition agents that characterize the coastal plain. The known thickness of the phreatic aquifer and the estimated range of the specific yield allowed the hydraulic conductivity to be identified as the most influential factor. [Jacob CE (1950) Flow of ground water. In: Rouse H (ed) Engineering Hydraulics. Wiley, New York

Carol, Eleonora S.; Kruse, Eduardo E.; Pousa, Jorge L.; Roig, Alejandro R.

2009-11-01

214

Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap System  

Directory of Open Access Journals (Sweden)

Full Text Available The rapid rate of water infrastructure development in the Mekong basin is a cause for concern due to its potential impact on fisheries and downstream natural ecosystems. In this paper we analyse the historical water levels of the Mekong River and Tonle Sap system by comparing pre and post 1991 daily observations from six stations along the Mekong mainstream from Chiang Sean (northern Laos, to Stung Treng (Cambodia, and the Prek Kdam station on the Tonle Sap River. Observed alterations in water level patterns along the Mekong are linked to temporal and spatial trends in water infrastructure development from 1960 to 2010. We argue that variations in historical climatic factors are important, but they are not the main cause of observed changes in key hydrological indicators related to ecosystem productivity. Our analysis shows that the development of mainstream dams in the upper Mekong basin in the post-1991 period have resulted in a significant increase of 7 day minimum (+91.6%, fall rates (+42%, and the number of water level fluctuations (+75 observed in Chiang Sean. This effect diminishes downstream until it becomes negligible at Mukdahan (northeast Thailand, which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse (southern Laos, alterations to the number of fluctuations and rise rate became strongly significant after 1991. The observed alterations slowly decrease downstream, but modified rise rates, fall rates, and dry season water levels were still quantifiable and significant as far as Prek Kdam. This paper provides the first set of evidence of hydrological alterations in the Mekong beyond the Chinese dam cascade in the upper Mekong. Given the evident alterations with no precedence at Pakse and downstream, post-1991 changes can also be directly attributed to water infrastructure development in the Chi and Mun basins of Thailand. A reduction of 23 and 11% in the water raising and fall rates respectively at Prek Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan and Sekong subbasins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.

T. A. Cochrane

2014-04-01

215

Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap System  

Science.gov (United States)

The rapid rate of water infrastructure development in the Mekong basin is a cause for concern due to its potential impact on fisheries and downstream natural ecosystems. In this paper we analyse the historical water levels of the Mekong River and Tonle Sap system by comparing pre and post 1991 daily observations from six stations along the Mekong mainstream from Chiang Sean (northern Laos), to Stung Treng (Cambodia), and the Prek Kdam station on the Tonle Sap River. Observed alterations in water level patterns along the Mekong are linked to temporal and spatial trends in water infrastructure development from 1960 to 2010. We argue that variations in historical climatic factors are important, but they are not the main cause of observed changes in key hydrological indicators related to ecosystem productivity. Our analysis shows that the development of mainstream dams in the upper Mekong basin in the post-1991 period have resulted in a significant increase of 7 day minimum (+91.6%), fall rates (+42%), and the number of water level fluctuations (+75) observed in Chiang Sean. This effect diminishes downstream until it becomes negligible at Mukdahan (northeast Thailand), which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse (southern Laos), alterations to the number of fluctuations and rise rate became strongly significant after 1991. The observed alterations slowly decrease downstream, but modified rise rates, fall rates, and dry season water levels were still quantifiable and significant as far as Prek Kdam. This paper provides the first set of evidence of hydrological alterations in the Mekong beyond the Chinese dam cascade in the upper Mekong. Given the evident alterations with no precedence at Pakse and downstream, post-1991 changes can also be directly attributed to water infrastructure development in the Chi and Mun basins of Thailand. A reduction of 23 and 11% in the water raising and fall rates respectively at Prek Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan and Sekong subbasins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.

Cochrane, T. A.; Arias, M. E.; Piman, T.

2014-04-01

216

Fluctuations of Phytoplankton Community in the Coastal Waters of Caspian Sea in 2006  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Problem statement: The Caspian Sea ecosystem has been suffered with many problems since 1980s. Aanthropogenic pollution from heavy metals, hydrocarbons, pesticides, changes in the quantity of nutrient inputs by rivers, are significant threats to biodiversity and biological resources such as plankton structure in the Caspian Sea. According to the significant of phytoplankton community in marine system. The state of the fluctuations of phytoplankton communities of the southwestern Caspia...

Siamak Bagheri; Mashhor Mansor; Marzieh Makaremi; Jalil Sabkara; Maznah, W. O. W.; Alireza Mirzajani; Khodaparast, Seyed H.; Hossein Negarestan; Azemat Ghandi; Akbar Khalilpour

2011-01-01

217

Fluctuations in indoor radon levels in dwellings in a volcanic area of a temperate tropical region  

Energy Technology Data Exchange (ETDEWEB)

Mexico City is located in the central section of the Neo-Volcanic Mexican Belt at an altitude of 2240 m. Air pollution is currently a huge environmental problem in the city. With the aim of determining any anomalous behavior patterns in relation to indoor radon, which could possibly have had an effect on patients with lung diseases who are smokers, a study was performed in indoor atmospheres over a period of several months. Radon was measured using both passive and continuous radon monitoring devices. The results of our investigations indicate that the dwellings of patients with lung diseases show no special characteristics as compared to homes included in a control group. However, in both cases, an enhancement in the indoor radon concentration levels during the night and early morning periods was observed, the periods in which most people are at home resting. (orig.)

Segovia, N.; Ruiz, W.; Pena, P. [ININ, Mexico D.F. (Mexico); Ponciano, G.; Morales, V. [Dr. Manuel Gea Gonzalez General Hospital, Secretaria de Salud and Dept. of Pharmacology - UNAM (Mexico); Godinez, L. [IG-UNAM, Ciudad Univ., Mexico D.F. (Mexico)

2002-03-01

218

Fluctuations in indoor radon levels in dwellings in a volcanic area of a temperate tropical region  

International Nuclear Information System (INIS)

Mexico City is located in the central section of the Neo-Volcanic Mexican Belt at an altitude of 2240 m. Air pollution is currently a huge environmental problem in the city. With the aim of determining any anomalous behavior patterns in relation to indoor radon, which could possibly have had an effect on patients with lung diseases who are smokers, a study was performed in indoor atmospheres over a period of several months. Radon was measured using both passive and continuous radon monitoring devices. The results of our investigations indicate that the dwellings of patients with lung diseases show no special characteristics as compared to homes included in a control group. However, in both cases, an enhancement in the indoor radon concentration levels during the night and early morning periods was observed, the periods in which most people are at home resting. (orig.)

219

Dynamics of a Landau-Zener non-dissipative system with fluctuating energy levels  

Science.gov (United States)

This paper considers a Landau-Zener (two-level) system influenced by a three-dimensional Gaussian and non-Gaussian coloured noise and finds a general form of the time dependent diabatic quantum bit (qubit) flip transition probabilities in the fast, intermediate and slow noise limits. The qubit flip probability is observed to mimic (for low-frequencies noise) that of the standard LZ problem. The qubit flip probability is also observed to be the measure of quantum coherence of states. The transition probability is observed to be tailored by non-Gaussian low-frequency noise and otherwise by Gaussian low-frequency coloured noise. Intermediate and fast noise limits are observed to alter the memory of the system in time and found to improve and control quantum information processing.

Fai, L. C.; Diffo, J. T.; Ateuafack, M. E.; Tchoffo, M.; Fouokeng, G. C.

2014-12-01

220

Minimal global magnetic millihertz fluctuation level determined from mid-latitude underground observations  

Science.gov (United States)

Investigation of the ultra-low frequency (ULF) magnetic pulsations, detected at mid-latitude by the underground magnetometer system [SQUID]2, is carried out in order to establish a first baseline for the "global minimal magnetic level" in the site. This study analyzes 24 quiet days, identified by the Deutsches GeoForschungs Zentrum (GFZ) as magnetically quiet. The results show that the mean magnetic spectrum in the millihertz range (0.1-15 mHz), which corresponds to the global magnetic Earth-ionosphere system, is characterized by several pulsations of noticeable amplitude above the flicker noise. The noise trend clearly shows the difference below and above 3 mHz. We attempt to discern the origin of these pulsations present in the minimum magnetic background baseline, taking into account terrestrial and ionospheric sources. This study provides a complementary analysis of the Earth-ionosphere coupling in the magnetic domain.

Pozzo di Borgo, E.; Marfaing, J.; Waysand, G.

2012-02-01

 
 
 
 
221

Putting water on a lattice: the importance of long wavelength density fluctuations in theories of hydrophobic and interfacial phenomena.  

Science.gov (United States)

The physics of air-water interfaces plays a central role in modern theories of the hydrophobic effect. Implementing these theories, however, has been hampered by the difficulty of addressing fluctuations in the shape of such soft interfaces. We show that this challenge is a fundamental consequence of mapping long wavelength density variations onto discrete degrees of freedom. Drawing from studies of surface roughness in lattice models, we account for the resulting nonlinearities simply but accurately. Simulations show that this approach captures complex solvation behaviors quantitatively. PMID:24483999

Vaikuntanathan, Suriyanarayanan; Geissler, Phillip L

2014-01-17

222

Seasonal fluctuations in water repellency and infiltration in a sandy loam soil after a forest fire in Galicia (NW Spain)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this work was to analyze, after a wildfire of moderate severity, the temporal fluctuations in water repellency and infiltration in a sandy loam soil under a mixed plantation of pine and eucalyptus and the comparison with an adjacent area not affected by the fire. In the burnt area and in a neighboring area not affected by the fire were collected during one year (1, 4, 6, 8 and 12 months after the fire) 10 soil samples along a transect of 18 m at four depths: 0-2, 2-5, 5-10 and 10-2...

Rodri?guez-alleres, M.; Varela, M. E.; Benito, E.

2013-01-01

223

Supersonic water level measuring method and device therefor  

International Nuclear Information System (INIS)

In the present invention, water level can be measured stably irrespective of change of temperature distribution and flowing distribution of water in a pressure vessel or a tank of a nuclear reactor. Namely, sinusoidal supersonic waves are sent to a waveguide in contact with water to vibrate it. The water level is measured based on the change of the resonance state of the waveguide. Alternatively, sinusoidal supersonic waves are sent and received by a supersonic transducer. Resonance state of a waveguide in contact with water and connected to the supersonic transducer for propagating the supersonic waves is detected by way of the supersonic transducer. The water level is calculated based on the change of the resonance state. Since the resonance state of the waveguide member is free from the effects of temperature distribution and flowing distribution in water and gas, the water level can be measured at high accuracy irrespective of the temperature distribution and flowing distribution in water. (I.S.)

224

Water levels in the Yucca Mountain area, Nevada, 1993  

International Nuclear Information System (INIS)

Water levels were monitored in 28 wells in the Yucca Mountain area, Nevada, during 1993. Seventeen wells were monitored periodically, generally on a monthly basis, and 11 wells representing 18 intervals were monitored hourly. All wells monitor water levels in Tertiary volcanic rocks, except one that monitors water levels in Paleozoic carbonate rocks. Water levels were measured using calibrated steel tapes and pressure transducers; steel-tape measurements were corrected for mechanical stretch, thermal expansion, and borehole deviation to obtain precise water-level altitudes. Water-level altitudes in the Tertiary volcanic rocks ranged from about 728 meters above sea level east of Yucca Mountain to about 1,034 meters above sea level north of Yucca Mountain. Water-level altitudes in the well monitoring the Paleozoic carbonate rocks varied between 752 and 753 meters above sea level during 1993. Water levels were an average of about 0.04 meter lower than 1992 water levels. All data were acquired in accordance with a quality-assurance program to support the reliability of the data

225

Antioxidant status and dialysis: plasma and saliva antioxidant activity in patients with fluctuating urate levels.  

Science.gov (United States)

The present study is concerned with the influence of processes occurring during dialysis on the antioxidant capacity of plasma and saliva. The biological fluids were also tested for uric acid and total protein content. Before hemodialysis, plasma antioxidant status of hemodialyzed patients appears slightly higher than the corresponding status in normal subjects; after hemodialysis it is found unchanged. The result can be explained by a balance between a reduction in uric acid plasma content, due to the dialytic procedure, and an increase in protein content, possibly due to a dialysis-related hemoconcentration. Moreover, pre-dialysis total antioxidant capacity of whole saliva samples is higher than in healthy individuals and drastically decreases towards normal values following dialytic procedure. Our data indicate a certain concentration of the uric acid in the saliva of hemodialyzed patients and evidence that both total protein concentration and uric acid level show a good correlation with saliva total antioxidant capacity, suggesting that proteins are major antioxidants of this fluid. Further observations are needed to assess whether this improved saliva antioxidant ability has any consequence on the periodontal conditions of hemodialyzed subjects. PMID:9925029

Meucci, E; Littarru, C; Deli, G; Luciani, G; Tazza, L; Littarru, G P

1998-11-01

226

Suppression device for the reactor water level lowering  

International Nuclear Information System (INIS)

Purpose: To suppress the lowering in the reactor water level so as to avoid unnecessary actuation of ECCS upon generation of transient changes which forecasts the lowering of the reactor water level in a BWR type reactor. Constitution: There are provided a water level suppression signal generator for generating a water level suppression signal upon generation of a transient change signal which forecasts the water level lowering in a nuclear reactor and a recycling flow rate controller that applies a recycling flow rate control signal to a recycling pump drive motor by the water level lowering suppression signal. The velocity of the recycling pump is controlled by a reactor scram signal by way of the water level lowering suppresion signal generator and a recycling flow rate controller. Then, the recycling reactor core flow rate is decreased and the void amount in the reactor is transiently increased where the water level tends to increase. Accordingly, the water level lowering by the scram is moderated by the increasing tendency of the water level. (Ikeda, J.)

227

Response to an oral calcium load in nephrolithiasis patients with fluctuating parathyroid hormone and ionized calcium levels  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english the response to an oral calcium load test was assessed in 17 hypercalciuric nephrolithiasis patients who presented elevated parathyroid hormone (PTH) irrespective of the ionized calcium (sCa2+) levels. Blood samples were collected at baseline (0 min) and at 60 and 180 min after 1 g calcium load for [...] serum PTH, total calcium, sCa2+, and 1.25(OH)2D3 determinations. According to the sCa2+ level at baseline, patients were classified as normocalcemic (N = 9) or hypercalcemic (N = 8). Six healthy subjects were also evaluated as controls. Bone mineral density was reduced in 14/17 patients. In the normocalcemic group, mean PTH levels at 0, 60 and 180 min (95 ± 76, 56 ± 40, 57 ± 45 pg/ml, respectively) did not differ from the hypercalcemic group (130 ± 75, 68 ± 35, 80 ± 33 pg/ml) but were significantly higher compared to healthy subjects despite a similar elevation in sCa2+ after 60 and 180 min vs baseline in all 3 groups. Mean total calcium and 1.25(OH)2D3 were similar in the 3 groups. Additionally, we observed that 5 of 9 normocalcemic patients presented a significantly higher concentration-time curve for serum PTH (AUC0',60',180') than the other 4 patients and the healthy subjects, suggesting a primary parathyroid dysfunction. These data suggest that the individual response to an oral calcium load test may be a valuable dynamic tool to disclose a subtle primary hyperparathyroidism in patients with high PTH and fluctuating sCa2+ levels, avoiding repeated measurements of both parameters.

S.A., Gomes; A., Lage; M., Lazaretti-Castro; J.G.H., Vieira; I.P., Heilberg.

228

Field evaluation of the effects of water table fluctuations on soil radon gas emanations.  

Science.gov (United States)

Measurements of the depth of the water table and the concentration of soil gas radon at water wells in Virginia and Maryland show that at each well site, there is no correlation between the depths of the water table and the radon concentration. However, when comparing nearby water wells, there is a relationship between depth of the water table and the concentration of soil gas radon. Wells with a shallower water table tend to have less soil gas radon emanation. It may be that this relationship It may be that this relationship (higher water table with lower radon emanation) may explain seasonal changes in radon concentration, since changes in water table depth are caused by seasonal changes in precipitation. PMID:18569322

Mose, Douglas G; Merolla, Paul; Mushrush, George W

2008-07-15

229

Analysis of water-level management on the upper Mississippi River (1980-1990)  

Science.gov (United States)

Management at 27 low-head dams affects water surface elevations for a 1050km stretch of the Upper Mississippi River (UMR) between St Louis, Missouri and Minneapolis, Minnesota. A systemic overview is given of current operating plans at dams on the UMR and historical data are analysed to determine how well the operating plans are being met. Water level elevations at all 27 dams are regulated as a function of discharge, although plans are specific for each dam. The management objective is to maintain a target water level at specific locations (control point) in each impoundment over specific ranges of discharge. The target water level and control point may change as discharge changes in each impoundment. In some of the impoundments water regulation causes drawdowns below the elevation for which the dams were planned, and at other dams no drawdown occurs. During the navigation seasons of 1980 to 1990, water levels were within their target window for an average of 72–5% of the time for 25 dams analysed. Difficulties in meeting targets are caused by winds, local rainfall events, ice dams and rapidly fluctuating discharges from tributaries with upstream reservoirs used for peaking hydropower.

Wlosinski, Joseph H.; Hill, Lara

1995-01-01

230

Water levels in the Yucca Mountain Area, Nevada, 1996  

International Nuclear Information System (INIS)

Water levels were monitored in 24 wells in the Yucca Mountain area, Nevada, during 1996. Twenty-two wells representing 28 depth intervals were monitored periodically, generally on a monthly basis, and 2 wells representing 3 depth intervals were monitored both hourly and periodically. All wells monitor water levels in Tertiary volcanic rocks except one that monitors water levels in paleozoic carbonate rocks. Water levels were measured using either calibrated steel tapes or a pressure sensor. Mean water-level altitudes in the Tertiary volcanic rocks ranged from about 727.86 to about 1,034.58 meters above sea level during 1996. The mean water-level altitude in the well monitoring the Paleozoic carbonate rocks was about 752.57 meters above sea level during 1996. Mean water-level altitudes for 1996 were an average of about 0.06 meter lower than 1995 mean water-level altitudes and 0.03 meter lower than 1985--95 mean water-level altitudes. During 1996, water levels in the Yucca Mountain area could have been affected by long-term pumping at the C-hole complex that began on May 8, 1996. Through December 31, 1996, approximately 196 million liters were pumped from well UE-25 c number-sign 3 at the C-hole complex. Other ground-water pumpage in the Yucca Mountain area includes annual pumpage from water-supply wells UE-25 J-12 and UE-25 J-13 of approximately 163 and 105 million liters, respectively, and pumpage from well USW G-2 for hydraulic testing during February and April 1996 of approximately 6 million liters

231

Water levels in the Yucca Mountain area, Nevada, 1994  

International Nuclear Information System (INIS)

Water levels were monitored in 28 wells in the Yucca Mountain area, Nevada, during 1994. Twelve wells representing 13 intervals were monitored periodically, generally on a monthly basis, 6 wells representing 10 intervals were monitored hourly, and 10 wells representing 13 intervals were monitored both periodically and hourly. All wells monitor water levels in Tertiary volcanic rocks, except one, that monitors water levels in Paleozoic carbonate rocks. Water levels were measured using calibrated steel tapes, a multiconductor cable unit, and pressure transducers. Water-level altitudes in the Tertiary volcanic rocks ranged from about 728 to about 1,034 meters above sea level during 1994. The mean-annual water-level altitude in the well monitoring the Paleozoic carbonate rocks was about 753 meters above sea level during 1994. Water levels were only an average of about 0.01 meters lower than 1993 water levels. All data were acquired in accordance with a quality-assurance program to support the reliability of the data

232

High levels of fluctuating asymmetry in populations of Apodemus flavicollis from the most contaminated areas in Chernobyl  

International Nuclear Information System (INIS)

Random deviations from the perfect symmetry of normally bilaterally symmetrical characters for an individual with a given genotype occur during individual development due to the influence of multiple environmental factors. Fluctuating asymmetry (FA) is often used as a measure of developmental instability, and can be estimated as the variance of the distribution of differences between the left and right sides. We addressed the question of whether levels of FA were elevated in radioactively contaminated populations living around Chernobyl compared to those in reference populations of the yellow-necked mouse (Apodemus flavicollis). In addition, we studied amounts of directional asymmetry (DA) when one side is larger than the other on average. There was a significant difference among populations, including reference populations, in the amount of both FA and DA. A higher level of FA was documented for the contaminated populations in close proximity to the failed Chernobyl reactor for both the asymmetry of size and shape. The FAs of size and shape were highest in populations from the most contaminated locations in the Chernobyl exclusion zone. Although the directional asymmetry of shape was also highest in the contaminated populations, it was not significantly different from those in most of the reference populations. Populations from less contaminated areas inside the Chernobyl exclusion zone did not express FA values different from those of the reference populations outsim those of the reference populations outside the affected area. FA of skulls of A. flavicollis may indicate the degree to which the level of radioactive contamination affects the development of animals at Chernobyl. However, the mechanisms leading to these effects are not clear and probably vary from population to population. There were significant correlations between the overall right to left differences for the Procrustes aligned shape configurations, centroid sizes, and intramuscular 137Cs. Detectable effects of radiation on developmental stability probably start to occur between 0.132 and 0.297 ?Gy/h

233

Characteristic of water level changes in river-bed during the 2012 drought in context of ground water levels in a small catchment  

Science.gov (United States)

The objective of this paper is to characterize the water level changes in river bed during the 2012 drought, in the context of ground water levels in the catchment. During the growing season , and long- lasting lack of precipitation causes atmospheric drought. Prolonged lack of precipitation causes depletion of water resources in the saturated zone . Groundwater recharge of rivers decreases , and hence streamflow droughts (summer droughts) occur, which is identified as hydrological droughts. In the phase of hydrological drought a much stronger relationship between surface and ground waters is observed. The study area is the Zago?d?onka river. The Zago?dzonka catchment is situated in the strip of the Central Polish Lowlands, in the region where droughts are the most frequent. The basin is the research area of the Department of Hydraulic Engineering of WUoLS-SGGW in Warsaw. It is one of the few catchments in Poland, with long-term records of rainfall and runoff occurrences. Hydrometeorological measurements are carried out from July 1962. The catchment area is mainly covered by one Quaternary aquifer . Quaternary layer is composed mostly of Pleistocene sands and gravels, with thickness from 4 to 40 m. Aquifer is at a depth of 1 to 12 m below ground level and is unconfined and fed by direct infiltration of precipitation. The Zago?d?onka river is the main drainage in the local hydrologic cycle. There is a strong relationship between surface waters and occurring in the Quaternary sediments. In the hydrological year 2012 hydrological and atmospheric drought occurred. The duration and deficit of streamflow drought ( defined by with the Q90 % truncation level) in 2012 was three time greater than the average value from the multi-annual period, which influenced the groundwater level fluctuations. Acknowledgment The paper has been prepared with financial support by a grant from National Science Centre

Wasilewicz, Micha?; Kaznowska, Ewa; Hejduk, Leszek

2014-05-01

234

Short-time variations of the ground water level  

International Nuclear Information System (INIS)

Investigations have demonstrated that the ground water level of aquifers in the Swedish bedrock shows shorttime variations without changing their water content. The ground water level is among other things affected by regular tidal movements occuring in the ''solid'' crust of the earth variations in the atmospheric pressure strong earthquakes occuring in different parts of the world These effects proves that the system of fissures in the bedrock are not stable and that the ground water flow is influenced by both water- and airfilled fissures

235

Application of the water table fluctuation method for estimating evapotranspiration at two phreatophyte-dominated sites under hyper-arid environments  

Science.gov (United States)

Shallow groundwater is primarily discharged via evapotranspiration (ETg) in arid and semi-arid riparian systems; however, the quantification of ETg remains a challenge in regional water resource assessments of such systems. In this study, the diagnostic indicators of groundwater evapotranspiration processes and the principles of applying the water table fluctuation (WTF) method to estimate ETg based on seasonal groundwater level changes were presented. These techniques were then used to investigate groundwater evapotranspiration processes at two sites dominated by phreatophytes (Tamarix ramosissima and Populus euphratica) within hyper-arid desert environments in northwestern China for the period 2010-2012. The results indicate that steady declines in the water table, which are commonly attributed to groundwater evapotranspiration, occurred at both sites during the growing season. Based on the proposed WTF method, the estimated ETg was 0.63-0.73 mm/d at the Tamarix ramosissima site and 1.89-2.33 mm/d at the Populus euphratica site during the summer months (June-August). Numerical simulations using a one-dimensional root water uptake model indicate that the seasonal variations in ETg at both sites were primarily dependent on the potential evaporation rates. Comparisons with previous studies on plant transpiration at similar sites in this area show that these results are reasonable. It is apparent that the WTF method can provide a simple and relatively inexpensive method of estimating ETg on a large scale in arid/semi-arid regions. However, there are significant uncertainties associated with time-dependent lateral flow rates, which creates a challenge when applying this method. In addition, the selection of calculation periods that show steady declines in the groundwater level can be somewhat subjective. To enhance the performance of the WTF method based on seasonal water table declines, further research on the estimation of lateral flow rates should be performed using an effective network of groundwater monitoring.

Wang, Ping; Grinevsky, Sergey O.; Pozdniakov, Sergey P.; Yu, Jingjie; Dautova, Dina S.; Min, Leilei; Du, Chaoyang; Zhang, Yichi

2014-11-01

236

Evaluation of statistical properties of free-surface fluctuation on a high-speed water jet using laser refraction technique  

International Nuclear Information System (INIS)

Free-surface fluctuation on a high-speed water jet has been evaluated using a laser beam refraction technique. This technique employs two pulse laser diodes and one high-speed optic detector. By detecting the two dimensional (2D) trajectory of laser beams refracted at free surface, the local streamwise slope-angle fluctuation at two measuring locations 1.27 mm apart on a jet free surface can be evaluated. The experiments are conducted for several locations along the jet center axis within the range of average velocity up to 10 m/s. The wave speed is evaluated from dominant time lag of cross-correlation coefficient for individual wave period, which is divided from time-series slope-angle data according to the zero-up-crossing method. The shape of waves is also calculated by integrating the free-surface slope angle. The wavelength and wave height are evaluated from the individual waveform. The steepness of free surface wave takes a maximum at a certain distance from nozzle exit for U ? 8 m/s. This suggests that the initial amplification of wave results in a wave breaking on the jet free surface for these velocity conditions. (author)

237

Carboxyhaemoglobin levels in water-pipe and cigarette smokers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Water-pipe smoking is growing in popularity, especially among young people, because of the social nature of the smoking session and the assumption that the effects are less harmful than those of cigarette smoking. It has however been shown that a single water-pipe smoking session produces a 24-hour urinary cotinine level equivalent to smoking 10 cigarettes per day. AIM: We aimed to measure carboxyhaemoglobin (COHb) blood levels before and after water-pipe and cigarette smoking sessions. ...

Theron, Ansa; Schultz, Cedric; Ker, James A.; Falzone, Nadia

2010-01-01

238

Keeping fuel covered. ABB's new water level measurement system  

International Nuclear Information System (INIS)

As one of the basic principles of reactor safety is to ensure that the fuel is covered, knowing water levels is vital. Older designs of water measurement equipment can suffer errors caused by the presence of non-condensable gases in the water during a depressurization transient. ABB Atom's new level measuring system, which uses an advanced condensation pot, is virtually independent of any variation of gas content. (UK)

239

Synthesis water level control by fuzzy logic  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: This paper focuses on evolving of two types fuzzy and classical PID liquid level controller and examining whether they are better able to handle modelling uncertainties. A two stage strategy is employed to design the synthesis fuzzy and classical PID controller with the process of the first and second order and implements disorder (quadratic function.Design/methodology/approach: The synthesis of fuzzy and classical PID liquid level controller was realized with the HP laptop 6830s Compaq NA779ES, software Matlab/Simulink 2008b, FIS (Fuzzy Inference System soft logical tool, input-output unit 500 Dragon Rider and ultrasonic sensor. Using the simulation program Matlab/Simulink/FIS we simulate the operation of fuzzy and classical controller in the liquid level regulating cycle and made a comparison between fuzzy and classical controller functioning.Findings: From the responses to step fuzzy and classical controller for first-order process shows that the actual value of the controlled variable takes the value one. Fuzzy and classical PID controller does not allow control derogation, which is also inappropriate for fuzzy and classical control cycle with incorporating disturbance. Classical PID controller in the first-order process provides short-term regulation, such as fuzzy PID controller. In fuzzy control cycle with fuzzy PID controller and incorporating disturbance in the process of second-order the control cycle is stable and at certain predetermined parameters (integral gain a control does not allow deviations.Research limitations/implications: In future research, the robustness of the fuzzy logic controller will be investigated in more details.Practical implications: Using fuzzy liquid level controller can reduce power consumption by 25%. Originality/value: Fuzzy logic controller is useful in applications of nonlinear static characteristic, where classical methods with usually classical PID controllers cannot be a satisfactory outcome

P. Berk

2011-04-01

240

Study of the influence of temperature and precipitations on the levels of BTEX in natural waters.  

Science.gov (United States)

Assessment of seasonal changes in surface water quality is an important aspect for evaluating temporal variation of water due to natural or anthropogenic inputs of point and non-point sources. The objective of this paper was to investigate the influence of seasonal temperature fluctuations and precipitations on the levels of BTEX in natural waters. Principal component analysis (PCA) was used to evaluate the seasonal correlations of BTEX levels in water and to extract the parameters that are most important in assessing seasonal variations of water quality. This study was carried out as a part of VOCs monitoring program in natural water samples from Mediterranean coast. To carry out this project, a multiresidue analytical method was used. The method was based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography coupled to flame ionization detector (FID). The limits of detection LODs found for the tested analyte tested were in the 0.001-1 ?g/L range. These values were adequate for the analysis of these compounds in water samples according to the regulated values. Water samples from different points of the Mediterranean coast were analyzed during a period of three years, and were taken four times per year. Most of the compounds were below the limit established by the legislation. The results obtained by a chemometric study indicated that temperature and precipitations can be related on the BTEX levels found in water. A regression model between temperature or precipitations and BTEX concentration was obtained, thus these models can be used as predictive model for detection any non-normal concentration level. PMID:23978603

Moliner-Martínez, Y; Herraez-Hernandez, R; Verdú-Andres, J; Campíns-Falcó, P; Garrido-Palanca, C; Molins-Legua, C; Seco, A

2013-12-15

 
 
 
 
241

Water-Level Changes in Shallow Wells Before and After the 1999 Ýzmit and Düzce Earthquakes and Comparison with Long-Term Water-Level Observations (1999-2004), NW Turkey.  

Science.gov (United States)

It is well known that earthquakes cause hydrological changes, such as drying or flooding of water wells, fluctuations in ground-water levels in wells, changes in water quality, and formation of new springs. Significant drops in ground-water levels in wells were recorded during recent earthquakes in NW Turkey on August 17, 1999 in Ýzmit and on November 12, 1999 in Düzce. The Ýzmit earthquake (Ms 7.4) caused pre-seismic water-level changes in wells at Eskisehir, located 118-216 km away from the epicentre. Well-level changes in the Eskisehir, Sakarya, Bursa, Yalova, Yenisehir and Ýnegöl basins were recorded prior to and after the Düzce earthquake (Ms 7.2) as well. These changes are due to strain on the southern Marmara segments of the Thrace-Eskisehir Fault Zone (TEFZ), which is affected by deformation of the North Anatolian Fault Zone (NAFZ). Ground-water-level changes in wells prior to and after the earthquake away from the epicentre and the position of Eastern Marmara-Eskisehir region indicate a possible connection between well-level changes that respond to compressive and tensile stresses and shear strain away from active strike-slip faults. The wells, located in basins having an angular connection with the earthquake-producing main faults, completely activate only during major earthquakes. The wells showing anomalies prior to earthquakes are generally found near epicentres or in basins having an angular connection as stated above. The data collected after the 1999 anomalies up to September 2004 indicate that the 1999 anomalies are unique to that year. It was not difficult to separate the seasonal fluctuations of the water levels from the earthquake anomalies. In this context, it is concluded that the 1999 water level anomalies prior to the earthquake were the fast- and short-period signature of slow but long-term deformations that occurred over a large area.

Yaltirak, Cenk; Yalçin, Tolga; Yüce, Galiip; Bozkurto?lu, Erkan

2005-12-01

242

Melatonin levels, determined by LC-ESI-MS/MS, fluctuate during the day/night cycle in Vitis vinifera cv Malbec: evidence of its antioxidant role in fruits.  

Science.gov (United States)

The identification of melatonin in plants has inspired new investigations to understand its biological function and which endogenous and external factors control its levels in these organisms. Owing to the therapeutical and nutraceutical properties of melatonin, it should be important to develop reliable analytical methods for its quantification in vegetal matrices containing this indoleamine, such as grape and wine. The main objectives of the present study were to test whether melatonin levels fluctuate during the day in berry skins of Vitis vinifera L. cv Malbec, thereby possibly relating its abundance to its putative antioxidant function, to determine whether daylight reaching clusters negatively controls melatonin levels, and to evaluate whether total polyphenols and anthocyanins also change through a 24-hr period. Grapes were harvested throughout the day/night to determine the moment when high levels of these components are present in grapes. The presence of melatonin in grapes was evaluated by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry. It is shown for the first time that melatonin levels fluctuate during the day/night cycle in plants grown under field conditions in a fruit organ of the species Vitis vinifera. We also determined that the diurnal decay of melatonin in berry skins is induced by sunlight, because covered bunches retained higher melatonin levels than exposed ones, thus explaining at least part of the basis of its daily fluctuation. Evidence of melatonin's antioxidant role in grapes is also suggested by monitoring malondialdehyde levels during the day. PMID:21605162

Boccalandro, Hernán E; González, Carina V; Wunderlin, Daniel A; Silva, María F

2011-09-01

243

Ground-water levels in and pumpage from the alluvial aquifer at Louisville, Kentucky, May 1989-May 1991  

Science.gov (United States)

Water-level data have been collected in the alluvial aquifer at Louisville, Ky., by the U.S. Geological Survey since 1943. Interpretations of these data are published periodically to update the record and help local officials manage this ground-water supply. Maps and hydrographs are presented on two sheets to aid in the interpretation of water-level changes for the period May 1989-May 1991. The altitude of the water table in the alluvial aquifer has increased as much as 5 feet in some areas during the 2-year period of May 1989-May 1991. Hydrographs for obser- vation wells throughout the alluvial aquifer show that water levels fluctuate seasonally and in response to wet and dry periods; overall, the water- level trend has been upward in recent years. Water levels in the downtown area are affected by the pumping of ground water to heat and cool several buildings in the area. Ground-water contour maps show induced infiltration of water from the Ohio River to the alluvial aquifer in downtown Louisville as a result of the ground-water pumping.

Unthank, Michael D.

1995-01-01

244

Wave-induced mass transport affects daily Escherichia coli fluctuations in nearshore water  

Science.gov (United States)

Characterization of diel variability of fecal indicator bacteria concentration in nearshore waters is of particular importance for development of water sampling standards and protection of public health. Significant nighttime increase in Escherichia coli (E. coli) concentration in beach water, previously observed at marine sites, has also been identified in summer 2000 from fixed locations in waist- and knee-deep waters at Chicago 63rd Street Beach, an embayed, tideless, freshwater beach with low currents at night (approximately 0.015 m s–1). A theoretical model using wave-induced mass transport velocity for advection was developed to assess the contribution of surface waves to the observed nighttime E. coli replenishment in the nearshore water. Using average wave conditions for the summer season of year 2000, the model predicted an amount of E. coli transported from water of intermediate depth, where sediment resuspension occurred intermittently, that would be sufficient to have elevated E. coli concentration in the surf and swash zones as observed. The nighttime replenishment of E. coli in the surf and swash zones revealed here is an important phase in the cycle of diel variations of E. coli concentration in nearshore water. According to previous findings in Ge et al. (Environ. Sci. Technol. 2010, 44, 6731–6737), enhanced current circulation in the embayment during the day tends to displace and deposit material offshore, which partially sets up the system by the early evening for a new period of nighttime onshore movement. This wave-induced mass transport effect, although facilitating a significant base supply of material shoreward, can be perturbed or significantly influenced by high currents (orders of magnitude larger than a typical wave-induced mass transport velocity), current-induced turbulence, and tidal forcing.

Ge, Zhongfu; Whitman, Richard L.; Nevers, Meredith B.; Phanikumar, Mantha S.

2012-01-01

245

A multi-source satellite data approach for modelling Lake Turkana water level: Calibration and validation using satellite altimetry data  

Science.gov (United States)

Lake Turkana is one of the largest desert lakes in the world and is characterized by high degrees of interand intra-annual fluctuations. The hydrology and water balance of this lake have not been well understood due to its remote location and unavailability of reliable ground truth datasets. Managing surface water resources is a great challenge in areas where in-situ data are either limited or unavailable. In this study, multi-source satellite-driven data such as satellite-based rainfall estimates, modelled runoff, evapotranspiration, and a digital elevation dataset were used to model Lake Turkana water levels from 1998 to 2009. Due to the unavailability of reliable lake level data, an approach is presented to calibrate and validate the water balance model of Lake Turkana using a composite lake level product of TOPEX/Poseidon, Jason-1, and ENVISAT satellite altimetry data. Model validation results showed that the satellitedriven water balance model can satisfactorily capture the patterns and seasonal variations of the Lake Turkana water level fluctuations with a Pearson's correlation coefficient of 0.90 and a Nash-Sutcliffe Coefficient of Efficiency (NSCE) of 0.80 during the validation period (2004-2009). Model error estimates were within 10% of the natural variability of the lake. Our analysis indicated that fluctuations in Lake Turkana water levels are mainly driven by lake inflows and over-the-lake evaporation. Over-the-lake rainfall contributes only up to 30% of lake evaporative demand. During the modelling time period, Lake Turkana showed seasonal variations of 1-2m. The lake level fluctuated in the range up to 4m between the years 1998-2009. This study demonstrated the usefulness of satellite altimetry data to calibrate and validate the satellite-driven hydrological model for Lake Turkana without using any in-situ data. Furthermore, for Lake Turkana, we identified and outlined opportunities and challenges of using a calibrated satellite-driven water balance model for (i) quantitative assessment of the impact of basin developmental activities on lake levels and for (ii) forecasting lake level changes and their impact on fisheries. From this study, we suggest that globally available satellite altimetry data provide a unique opportunity for calibration and validation of hydrologic models in ungauged basins. ?? Author(s) 2012.

Velpuri, N.M.; Senay, G.B.; Asante, K.O.

2012-01-01

246

A multi-source satellite data approach for modelling Lake Turkana water level: calibration and validation using satellite altimetry data  

Directory of Open Access Journals (Sweden)

Full Text Available Lake Turkana is one of the largest desert lakes in the world and is characterized by high degrees of inter- and intra-annual fluctuations. The hydrology and water balance of this lake have not been well understood due to its remote location and unavailability of reliable ground truth datasets. Managing surface water resources is a great challenge in areas where in-situ data are either limited or unavailable. In this study, multi-source satellite-driven data such as satellite-based rainfall estimates, modelled runoff, evapotranspiration, and a digital elevation dataset were used to model Lake Turkana water levels from 1998 to 2009. Due to the unavailability of reliable lake level data, an approach is presented to calibrate and validate the water balance model of Lake Turkana using a composite lake level product of TOPEX/Poseidon, Jason-1, and ENVISAT satellite altimetry data. Model validation results showed that the satellite-driven water balance model can satisfactorily capture the patterns and seasonal variations of the Lake Turkana water level fluctuations with a Pearson's correlation coefficient of 0.90 and a Nash-Sutcliffe Coefficient of Efficiency (NSCE of 0.80 during the validation period (2004–2009. Model error estimates were within 10% of the natural variability of the lake. Our analysis indicated that fluctuations in Lake Turkana water levels are mainly driven by lake inflows and over-the-lake evaporation. Over-the-lake rainfall contributes only up to 30% of lake evaporative demand. During the modelling time period, Lake Turkana showed seasonal variations of 1–2 m. The lake level fluctuated in the range up to 4 m between the years 1998–2009. This study demonstrated the usefulness of satellite altimetry data to calibrate and validate the satellite-driven hydrological model for Lake Turkana without using any in-situ data. Furthermore, for Lake Turkana, we identified and outlined opportunities and challenges of using a calibrated satellite-driven water balance model for (i quantitative assessment of the impact of basin developmental activities on lake levels and for (ii forecasting lake level changes and their impact on fisheries. From this study, we suggest that globally available satellite altimetry data provide a unique opportunity for calibration and validation of hydrologic models in ungauged basins.

N. M. Velpuri

2012-01-01

247

Assessment of radon levels in some water resources in Egypt  

International Nuclear Information System (INIS)

Radon is a naturally occurring radioactive gas that is produced by the radioactive decay of radium. Breathing high concentrations of radon can cause lung cancer. When radon gas migrates through the atmosphere, the solid radon progeny are deposited on the soil and water below, entering into the food chain. Radon generated from rocks containing its parents may escape to the underground or surface running water, which ultimately used as drinking water or for irrigation. In this work radon level was determined in different water resources in Egypt. Water from spring, tap water Nile and some commercially available drinking water were subjected to radon measurements using CR-39 detectors. Radon concentration in different water resources was found the range from 8.94 to 10.00 Bq/m3 while in trapped air above water was 9.3 to 10.38 Bq/m3

248

Monitoring of water level changes In Anzali Mordab wetland, North Iran, Using SAR Interferometry  

Science.gov (United States)

Wetland ecosystems play a vital role in human life. The variable water level fluctuation sustained by wetlands during different seasons is one of the most important factors that affect the ecosystems surrounding them. Interferometric Synthetic Aperture Radar (InSAR) has proven to be an effective and powerful technique for detecting water level changes in wetlands covered with emergent woody or herbaceous vegetation. It provides dense spatial measurements of water level changes that cannot be obtained by any other terrestrial-based methods. In this study we used 20 Envisat images during 2003-2005 and 9 PALSAR images during 2007-2009 and compared the potential of C-band and L-band interferometry to monitor water levels changes in Anzali Mordab, North Iran. Our results show that L-band PALSAR images, which have a longer wavelength than C-band Envisat ASAR images, are more appropriate for this kind of application of InSAR over the marshy environment of Anzali Mordab. We also investigate the influence of different polarization of ALOS data on the quality of interferometric result and show that interferometric observations using HH polarization data result in a better coherence over marshes than HV polarization data.

Pesian, N.; Motagh, M.; Sharifi, M.; Alipour, S.

2010-12-01

249

Investigation of the Relationship between Groundwater Level Fluctuation and Vegetation Cover by using NDVI for Shaqlawa Basin, Kurdistan Region – Iraq  

Directory of Open Access Journals (Sweden)

Full Text Available Groundwater as an important component of the hydrological cycle and it is the main resource for irrigation and domestic water supply particularly in arid and semi-arid area, where groundwater is a key feature that controls the distribution of vegetation. Distribution of vegetation was compared in the Shaqlawa Basin located in Kurdistan Region, Northern Iraq with the depth to groundwater by using the normalize difference vegetation index (NDVI and the normalize different moisture index (NDMI. The NDVI and NDMI were derived from TM-5 images from 2006, 2007, 2009, 2010, and 2011. Depths to groundwater measurements were available from 11 monitoring wells. The results of statistical analysis show significant relationship between groundwater table and calculated vegetated areas at the 95% confidence levels with P-value less than 0.05 for all modeled years. The NDVI values at different depth to groundwater intervals indicate that higher vegetation coverage and more plant diversity exist in areas of shallow groundwater. Drought periods affected the groundwater table and less water infiltrating into soil, then the agricultural decreased. The scarcity of precipitation and other sources for fresh water increase the demand on groundwater water in agricultural activities in the region.

Shwan Seeyan

2014-06-01

250

Visualization of flow in pressurizer spray line piping and estimation of thermal stress fluctuation caused by swaying of water surface  

International Nuclear Information System (INIS)

The pressurizer spray line of PWR plants cools reactor coolant by injecting water into pressurizer. Since the continuous spray flow rate during commercial operation of the plant is considered insufficient to fill the pipe completely, there is a concern that a water surface exists in the pipe and may periodically sway. In order to identify the flow regimes in spray line piping and assess their impact on pipe structure, a flow visualization experiment was conducted. In the experiment, air was used substituted for steam to simulate the gas phase of the pressurizer, and the flow instability causing swaying without condensation was investigated. With a full-scale mock-up made of acrylic, flow under room temperature and atmospheric pressure conditions was visualized, and possible flow regimes were identified based on the results of the experiment. Three representative patterns of swaying of water surface were assumed, and the range of thermal stress fluctuation, when the surface swayed instantaneously, was calculated. With the three patterns of swaying assumed based on the visualization experiment, it was confirmed that the thermal stress amplitude would not exceed the fatigue endurance limit prescribed in the Japanese Design and Construction Code. (author)

251

Visualization of Flow in Pressurizer Spray Line Piping and Estimation of Thermal Stress Fluctuation Caused by Swaying of Water Surface  

Science.gov (United States)

The pressurizer spray line of PWR plants cools reactor coolant by injecting water into pressurizer. Since the continuous spray flow rate during commercial operation of the plant is considered insufficient to fill the pipe completely, there is a concern that a water surface exists in the pipe and may periodically sway. In order to identify the flow regimes in spray line piping and assess their impact on pipe structure, a flow visualization experiment was conducted. In the experiment, air was used substituted for steam to simulate the gas phase of the pressurizer, and the flow instability causing swaying without condensation was investigated. With a full-scale mock-up made of acrylic, flow under room temperature and atmospheric pressure conditions was visualized, and possible flow regimes were identified based on the results of the experiment. Three representative patterns of swaying of water surface were assumed, and the range of thermal stress fluctuation, when the surface swayed instantaneously, was calculated. With the three patterns of swaying assumed based on the visualization experiment, it was confirmed that the thermal stress amplitude would not exceed the fatigue endurance limit prescribed in the Japanese Design and Construction Code.

Oumaya, Toru; Nakamura, Akira; Onojima, Daisuke; Takenaka, Nobuyuki

252

Water level changes for Lake Turkana and climate variability during the African Humid Period  

Science.gov (United States)

The chronology of East African paleoclimate suggests the transition through the African Humid Period (AHP) at ca. 15 to 5 ka was a binary shift from wet conditions in the Late Pleistocene to current aridity. Previous studies indicate that water levels for Lake Turkana for the AHP were stable at ~88 to 98 m above current level with outflow into the White Nile Basin. This study of relict beaches around Lake Turkana indicates surprisingly >50 m variability in water level between 14 and 4 ka. The elevation of past water level is constrained by barometric and GPS-based altimetry of relict beaches and age control by 14C dating of associated mollusks and OSL dating of quartz grains from surrounding littoral and sublittoral deposits. We also include well provenanced lake level data from prior studies to constrain more fully the timing and height of water level fluctuations in the Late Quaternary. Additionally, previous studies indicate that peak water levels may be regionally amplified by increased precipitation causing overflow into the Lake Turkana Basin from the adjacent Suguta and Chew Bahir basins, particularly during high stands at ca. >8.5 ka and at 6.3 ka. Our analysis of the Lake Turkana strandplain reveals that water level may have varied by × 60 m, potentially reaching the outlet elevation at ca.11.3, 10.3, 9.0, 6.3 and 5.1 ka. There are other possible high stands at ca. 13.0, 8.4, 7.8 and 7.0 ka with limited elevational and age constraints; it is unknown if these lake stands reached the outlet elevation. Evidence from relict strand plains indicate that lake level was probably below 20 m since ca. 4.5 ka, though there were two noticeable high stands up to >12 to 18 m at ca. 830 years ago and AHP for Lake Turkana is characterized by extreme water level variability, rather than a sustained water level, with a final and rapid fall in lake level between 5.0 and 4.5 ka associated with increasing aridity.

Bloszies, C.; Forman, S. L.; Wright, D. K.

2013-12-01

253

Primary collector wall local temperature fluctuations in the area of water-steam phase boundary  

International Nuclear Information System (INIS)

A limited number of temperature sensors could be installed at the primary collector surface in the area of water - steam phase boundary. The surface temperatures as well WWER 440 steam generator process data were measured and stored for a long time and off-line evaluated. Selected results are presented in the paper. (orig.)

254

Lake deposits of moderate salinity as sensitive indicators of lake level fluctuations: Example from the Upper Rotliegend saline lake (Middle-Late Permian, Northeast Germany)  

Science.gov (United States)

The Rotliegend saline lake periodically covered wide areas of the Southern Permian Basin in Northwest Europe during the Permian. The sedimentology, mineralogy and geochemistry of lake deposits were studied to document very high frequency lake level fluctuations and to evaluate their triggers. Increased precipitation and marine ingressions into the basin resulted in lake extension. Increased run-off is documented by intercalated fluvial deposits in low-salinity deposits of the lake. Because lake deposits reflect mainly deposition in relatively wet climate phases, they are not correlatable to halite deposits in other basin areas. Decreased precipitation is followed by shrinkage of the lake, desiccation at its margins, and higher lake salinity due to concentration of the brine. Carbonate and anhydrite contents of lake deposits increased considerably before the areas fell dry, but halite is not preserved in the study area. Falling lake level is also reflected by the occurrence of wave ripples, reflecting decreased water depth and finally by desiccation and formation of evaporite crusts. Not only the mineralogical content, but also the colour of lake claystones changes with varying salinity. Anhydrite- and carbonate-free red claystones were replaced by violet to green and grey anhydritic and calcareous claystone or marls with increasing salinity. The amount of boron adsorbed on illite also corresponds to changes in salinity and can therefore be used as a palaeosalinity indicator. Rare earth element concentrations within lake deposits do not reflect variations in salinity but different palaeogeographical settings. Marine ingressions into the lake are neither reflected by the amount of boron adsorbed onto illite nor by rare earth element contents of the lake deposits. Highly saline deposits are partly characterised by intensive deformation, which can be interpreted as seismites or dissolution breccias.

Legler, B.; Schneider, J. W.; Gebhardt, U.; Merten, D.; Gaupp, R.

2011-03-01

255

Carboxyhaemoglobin levels in water-pipe and cigarette smokers  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Water-pipe smoking is growing in popularity, especially among young people, because of the social nature of the smoking session and the assumption that the effects are less harmful than those of cigarette smoking. It has however been shown that a single water-pipe smoking session produces a 24-hour [...] urinary cotinine level equivalent to smoking 10 cigarettes per day. AIM: We aimed to measure carboxyhaemoglobin (COHb) blood levels before and after water-pipe and cigarette smoking sessions. METHOD: Self-confessed smokers older than 18 years (N=30) volunteered to smoke a water-pipe or a cigarette and have their blood COHb levels measured under controlled conditions. RESULTS: Mean baseline COHb levels were 2.9% for the 15 cigarette smokers and 1.0% for the 15 water-pipe smokers. Levels increased by a mean of 481.7% in water-pipe smokers as opposed to 39.9% in cigarette smokers. CONCLUSION: The study demonstrated that water-pipe smokers had significantly higher increases in blood COHb levels thancigarette smokers during a single smoking session.

Ansa, Theron; Cedric, Schultz; James A, Ker; Nadia, Falzone.

2010-02-01

256

Falling Lake Victoria water levels: Is climate a contributing factor?  

Energy Technology Data Exchange (ETDEWEB)

Recently, and perhaps most threatening, Lake Victoria water level has been receding at an alarming rate. A recent study suggested the possibility of the expanded hydroelectric power station in Uganda. However, since the lake receives 80% of its refill through direct rainfall and only 20% from the basin discharge, climatic contributions cannot be ignored, since the 80% water is directly dependent on it. It is therefore necessary to investigate climatic contribution to the declining Lake Victoria water level observed over a long period, i.e., 30 years. This contribution uses 30 years period anomalies for rainfall, river discharge and lake level changes of stations within Lake Victoria basin to analyze linear and cyclic trends of climate indicators in relation ot lake levels. Linear trend analysis using the student's t test indicate a decreasing pattern in rainfall anomalies, with the slope being statistically similar to those of water levels at both Kisumu, Maziba and Jinja stations for the same period of time (1976-1999), thus showing a strong correlation. On the other hand, cyclic trend analysis using Discrete Fourier Transform (DFT) shows cyclic period of water level to coincide with those of droughts and rainfall. The strong relationship between climatic indicators of drought and rainfall on one-hand and lake levels on the other hand signifies the need to incorporate climate information in predicting, monitoring and managing lake level changes.

Awange, J.L. [Department of Spatial Sciences, Division of Science and Engineering, Curtin University of Technology, Perth, WA (Australia); Bae, K. [Department of Spatial Sciences, Division of Science and Engineering, Curtin University of Technology, Perth, WA (Australia); Ogalo, L. [IGAD Climate Prediction and Applications Centre (ICPAC) Nairobi (Kenya); Omondi, P. [IGAD Climate Prediction and Applications Centre (ICPAC) Nairobi (Kenya); Omullo, M. [Department of Environment Sciences, Maseno University, Maseno (Kenya); Omute, P. [Department of Spatial Sciences, Division of Science and Engineering, Curtin University of Technology, Perth, WA (Australia); Were, P. [Department of Environment Sciences, Maseno University, Maseno (Kenya)

2008-08-15

257

Experience of water chemistry and radiation levels in Swedish BWRs  

International Nuclear Information System (INIS)

From the BWR operational experience in Sweden it has been found that the occupational radiation exposures have been comparatively low in an international comparison. One main reason for the favourable conditions is the good water chemistry performance. This paper deals at first with the design considerations of water chemistry and materials selection. Next, the experience of water chemistry and radiation levels are provided. Finally, some methods to further reduce the radiation sources are discussed. (author)

258

Impacts of Water Level Fluctuations on Kokanee Reproduction in Flathead Lake, 1985 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

This study has investigated the effects of the operation of Kerr Dam on the reproductive success of kokanee that spawn along the shores of Flathead Lake. We have estimated the spawning escapement to the lakeshore, characterized spawning habitat, monitored egg and alevin survival in redds, and related survival to length of redd exposure due to lake drawdown. Groundwater discharge apparently attracts kokanee to spawning sites along the lakeshore and is responsible for prolonging egg survival in redds above minimum pool. We have quantified and described the effect of lake drawdown on groundwater flux in spawning areas. This report defines optimal lakeshore spawning habitat and discusses eqg and alevin survival both in and below the varial zone.

Beattie, Will; Fraley, John J.; Decker-Hess, Janet (Montana Department of Fish, Wildlife and Parks, Kalispell, MT)

1986-06-01

259

Radium-226 levels in Italian drinking waters and foods  

International Nuclear Information System (INIS)

Levels of 226Ra in Italian waters and foods were measured. Results were similar to those found in other countries, except for some mineral waters with 226Ra concentrations above 1 pCi/liter andup to 19 pCi/liter. No difinite correlation was found between the 226Ra concentrations measured and the high natural background radiation levels determined in central Italy in previous work

260

Typhoon and elevated radon level in a municipal water supply  

Energy Technology Data Exchange (ETDEWEB)

The Municipal Water Supply at Hsinchu City is a water treatment plant using poly- aluminum chloride (PAC) for coagulation and then followed by precipitation and filtration. Its capacity is 70,000 m{sup 3}/day. The raw water is drawn from the nearby river. Since the subject of interest is the radon level during typhoon season, the sampling period was from March to December 1999. Commercially available electret was used for water samples taken from the five ponds in the plant. This technique relies on the measurement of radon in air above a water sample enclosed in a sealed vessel. The concentration of airbone radon released from water was determined by means of the electret ion chamber. During the first sampling period there came two typhoons. One is called Magie during June 10-17, and the other called Sam during August 20-26. The first typhoon led to the radon level measured from the water samples as high as 705 Bq/m{sup 3}, while the second caused even higher radon level as high as 772 Bq/m{sup 3}. Similar results were obtained for the second sampling period after August till December 1999. For those measured without typhoon influence, the average radon was lower from the coagulation pond yet without coagulation process during March through August 1999. However, water samples taken from the pond after precipitation did not show similar results in radon level. (author)

Mao, Cheng-Hsin [Nuclear Science and Development Center, National Tsing Hua Univ., Taiwan (China); Weng, Pao-Shan [Radiation Protection Association ROC, Taiwan (China)

2000-05-01

 
 
 
 
261

Typhoon and elevated radon level in a municipal water supply  

International Nuclear Information System (INIS)

The Municipal Water Supply at Hsinchu City is a water treatment plant using poly- aluminum chloride (PAC) for coagulation and then followed by precipitation and filtration. Its capacity is 70,000 m3/day. The raw water is drawn from the nearby river. Since the subject of interest is the radon level during typhoon season, the sampling period was from March to December 1999. Commercially available electret was used for water samples taken from the five ponds in the plant. This technique relies on the measurement of radon in air above a water sample enclosed in a sealed vessel. The concentration of airbone radon released from water was determined by means of the electret ion chamber. During the first sampling period there came two typhoons. One is called Magie during June 10-17, and the other called Sam during August 20-26. The first typhoon led to the radon level measured from the water samples as high as 705 Bq/m3, while the second caused even higher radon level as high as 772 Bq/m3. Similar results were obtained for the second sampling period after August till December 1999. For those measured without typhoon influence, the average radon was lower from the coagulation pond yet without coagulation process during March through August 1999. However, water samples taken from the pond after precipitation did not show similar results in radon level. (author)

262

Fluctuations in the meiofauna of the Aufwuchs community in a brackish-water lagoon  

Science.gov (United States)

The organization of the Aufwuchs community in a brackish-water lagoon (Swanpool, Falmouth, U.K.) is described. Changes in the population densities of encrusting bryozoans and mobile meiofauna are described for a period of 3 years. Most meiofaunal species reached peak densities in the spring (January-March). These included tardigrades ( Macrobiotus sp.), oligochaetes ( Nais elinguis, Chaetogaster diaphanus), the harpacticoid copepod Schizopera clandestina, ostracods, the nematodes Dichromadora geophila and Theristus spp., and possibly the nematodes Chromadorina germanica and Atrochromadora microlaima. Other meiofaunal populations peaked in summer (July-September), and these included the chironomid Chironomus salinarius, the harpacticoid copepod Nitocra spinipes and the nematode Adoncholaimus thalassophygas. Two further species, the mite Halacarus balticus and the nematode Aphelencoides sp., showed irregular bursts in numbers. It is concluded that the spring-peaking species increased in numbers dependent upon the growth of the Aufwuchs, and particularly of the surface film of diatoms, while the summer-peaking species may have been controlled more by limiting values of salinity and temperature. These conclusions are contrasted with the general view of salinity as the over-riding factor in brackish-water ecosystems.

Little, Colin

1986-08-01

263

Water level regime in the Danube river and its river branches  

International Nuclear Information System (INIS)

In the major part of the left side river branch system, fed through the intake structure at Dobrohost, relatively high level conditions are kept during the whole vegetation period. The flow in the upstream part (upstream line D) is comparable with the pre-dam stages for 4000 m3 s-1 in Bratislava and between lines E to D with the pre dam 3000 m3 s-1. The very downstream part of the system is controlled by the water level fluctuation in the Danube. The water level in the old Danube could be increased substantially by constructing a series of submerged hydraulic structures. An increase in water level of more than 1.5 m was achieved by the discharge of 400 m3 s-1 in the old Danube using preliminary design of structures situated in the reach between rkm 1817-1825. The guaranteed width of 90 m and depth of 2 m in the old Danube could be achieved at discharge rates of 1500 m3 s-1 or higher. The flow velocity is about 0.5 m s-1 or higher. The flow velocity is about 0.5 m s-1 in the reaches between the structures at discharge 400 m3 s-1 and about 1 m s-1 at discharge of m3 s-1. (authors). 8 figs., 1 map, 12 refs

264

A Feasibility Study to Lower Steam Generator Low Water Level Trip Setpoint to Reduce Unnecessary Scram Frequency for KORI 3,4 Plant  

Energy Technology Data Exchange (ETDEWEB)

The steam generator low water level trip setpoint of KORI NPP units 3 and 4(KNU 3 and 4), three-loop Westinghouse pressurized water reactor, is higher than that of OPR1000. In addition, steam generator downcomer water level in KNU 3 and 4 could fluctuate easily during a transient because of smaller downcomer water inventory, compared to the total water inventory in the steam generator. Due to these reasons, there is a higher possibility of unnecessary reactor trips caused by the steam generator low-low water level in KNU 3 and 4. Its operating history shows that most of reactor trips were caused by steam generator low-low level reactor trip signal. Such reactor trips, especially unnecessary ones, result in time and economic losses. In this paper, a feasibility study was performed to reduce unnecessary reactor trip by changing steam generator low-low water level reactor trip setpoint(SGLLRTS) for KNU 3 and 4.

Jung, M. S.; Lee, C. S.; Lee, G. C.; Kim, E. K. [Korea Power Engineering Company, Daejeon (Korea, Republic of)

2008-10-15

265

A Feasibility Study to Lower Steam Generator Low Water Level Trip Setpoint to Reduce Unnecessary Scram Frequency for KORI 3,4 Plant  

International Nuclear Information System (INIS)

The steam generator low water level trip setpoint of KORI NPP units 3 and 4(KNU 3 and 4), three-loop Westinghouse pressurized water reactor, is higher than that of OPR1000. In addition, steam generator downcomer water level in KNU 3 and 4 could fluctuate easily during a transient because of smaller downcomer water inventory, compared to the total water inventory in the steam generator. Due to these reasons, there is a higher possibility of unnecessary reactor trips caused by the steam generator low-low water level in KNU 3 and 4. Its operating history shows that most of reactor trips were caused by steam generator low-low level reactor trip signal. Such reactor trips, especially unnecessary ones, result in time and economic losses. In this paper, a feasibility study was performed to reduce unnecessary reactor trip by changing steam generator low-low water level reactor trip setpoint(SGLLRTS) for KNU 3 and 4

266

[Sodium levels in the Dalmatian water resources in 2003].  

Science.gov (United States)

The objective of this paper was to analyse the sodium levels in the spring water, surface and groundwater in Dalmatia during 2003. The sodium concentrations were computed from the difference between coefficient K1 (the ratio between the chlorides and sulfates sum and the carbonate hardness) and K2 (the ratio between non-carbonate and carbonate hardness) and carbonate hardness. The average sodium concentrations have been expressed by a median and they ranged from 1.8 mg/L Na to 17.6 mg/L Na in the spring water, in the surface water they ranged from 1.0 to 502 mg/L Na and in the groundwater they ranged from 11.1 mg/L Na to 124.3 mg/L Na. In the spring water the sodium concentrations varied from 32% to 217%, in the surface water from 40% to 159% and in the groundwater from 77.3% to 180%. According to the corrosiveness coefficient K1, 83% of the spring waters are classified as non-corrosive and 17% as water with a low degree of corrosiveness; 84% of the surface waters are classified as non-corrosive water and 16% as very corrosive; all groundwater is classified as very corrosive water. Out of the total of 60 analyzed water resources 64% are classified as hypotensive, 20% as normotensive and 17% as hypertensive water. The drinking water has been defined as hypotensive (20 mg/L Na) by relating the sodium concentration projectively with the notion of arterial pressure knowing that an increased sodium concentration in blood increases the blood pressure. From the informatics standpoint the data related to health should be classified into data bases which can serve as a methodological starting point for studying the influence of sodium upon human health. Consequently, epidemiological studies should relate various sodium levels in drinking water to other factors which affect human health. PMID:16808101

Stambuk-Giljanovi?, Nives; Stambuk, Drago

2006-01-01

267

High-frequency propagating density fluctuations in deeply supercooled water: evidence of a single viscous relaxation.  

Science.gov (United States)

We performed a Brillouin scattering experiment on deeply supercooled water and compared the results with similar literature data obtained both at the same and at higher values of the exchanged wave vector. The whole set of available experimental data can be well reproduced with the use of the generalized hydrodynamic model where all the involved thermodynamic parameters are fixed to their literature values. On the contrary, the model based on the memory function approach generates the wrong estimates for measurables when the same values of the thermodynamic parameters are used. This result confirms our recent criticisms against the utilization of models originating from linear response theory [Phys. Rev. E 84, 051202 (2011)]. The inconsistency between models explains apparent discrepancies between the different conclusions on water acoustic behavior which may be found in the literature. We demonstrate that the observed behavior can be explained by assuming only a single relaxation process that is typical of any viscoelastic system. With all thermodynamics quantities fixed, the hydrodynamic description needs only two parameters to model the experimental data, namely, the relaxation time and the high-frequency limit of the sound velocity. The whole body of the experimental data can be well reproduced when the relaxation time behaves in an Arrhenian manner and the difference between the relaxed and not relaxed sound velocities is a constant. The high-frequency sound velocity is never higher than 2200 m/s. We conclude that, at least from experiments performed within the hydrodynamic regime, there is no indication for a fast sound close to the hypersonic velocity observed in ice. PMID:23496512

Aliotta, F; Gapi?ski, J; Pochylski, M; Ponterio, R C; Saija, F; Salvato, G; Vasi, C

2013-02-01

268

High-frequency propagating density fluctuations in deeply supercooled water: Evidence of a single viscous relaxation  

Science.gov (United States)

We performed a Brillouin scattering experiment on deeply supercooled water and compared the results with similar literature data obtained both at the same and at higher values of the exchanged wave vector. The whole set of available experimental data can be well reproduced with the use of the generalized hydrodynamic model where all the involved thermodynamic parameters are fixed to their literature values. On the contrary, the model based on the memory function approach generates the wrong estimates for measurables when the same values of the thermodynamic parameters are used. This result confirms our recent criticisms against the utilization of models originating from linear response theory [Phys. Rev. EPLEEE81063-651X10.1103/PhysRevE.84.051202 84, 051202 (2011)]. The inconsistency between models explains apparent discrepancies between the different conclusions on water acoustic behavior which may be found in the literature. We demonstrate that the observed behavior can be explained by assuming only a single relaxation process that is typical of any viscoelastic system. With all thermodynamics quantities fixed, the hydrodynamic description needs only two parameters to model the experimental data, namely, the relaxation time and the high-frequency limit of the sound velocity. The whole body of the experimental data can be well reproduced when the relaxation time behaves in an Arrhenian manner and the difference between the relaxed and not relaxed sound velocities is a constant. The high-frequency sound velocity is never higher than 2200 m/s. We conclude that, at least from experiments performed within the hydrodynamic regime, there is no indication for a fast sound close to the hypersonic velocity observed in ice.

Aliotta, F.; Gapi?ski, J.; Pochylski, M.; Ponterio, R. C.; Saija, F.; Salvato, G.; Vasi, C.

2013-02-01

269

Study on convective mixing phenomena in parallel triple-jet along wall. Comparison of temperature fluctuation characteristics between sodium and water  

International Nuclear Information System (INIS)

Full text of publication follows: When temperature fluctuation due to convective mixing between hot and cold fluids is transferred to structure, there is a possibility of high cycle thermal fatigue. In a fast reactor sodium is used as coolant. Many experiments and calculations using water as working fluid have been carried out for the temperature fluctuations. As regarding sodium there are few experimental data. Sodium has approximately a 100 times larger thermal conductivity than water though dynamic viscosity is the same order. So temperature fluctuation characteristics in sodium will be different from that in water. Especially, decay characteristics of temperature fluctuation near a wall surface are strongly influenced by thermal property of fluid in a boundary layer. This is of importance to evaluate transfer characteristics of temperature fluctuation from fluid to structure. Here, sodium and water experiments were performed using the same geometry of the test sections. These experimental apparatuses have parallel triple jets sandwiched with two partition plates. The triple jets flow vertically along a wall with convective mixing among the jets. The jet in the center is cold, and two jets in both sides are hot. The discharged velocities of the triple jets were 0.5 m/s in both experiments. The temperature data were obtained by movable thermocouple trees, which consisted of 25 to 40 thermocouples. The temperatures were measured at 0.5 mm from the wall surface to the center position between the two partition plates. In addition, a particle image velocimetry was applied to the water experiment. As for the time-averaged temperature field at the furthest position from the wall, the hot jets were inclined toward the cold jet in both experiments. Temperature fluctuation intensity was high in the region where the cold jet met the hot jets. A prominent frequency was observed in temperature fluctuation where the cold jet contacted the hot jets; it was resulted from oscillation of the jets. Both sodium and water experiments showed the same tendency of frequency characteristics at the furthest position from the wall surface, and the prominent frequency in sodium was the same as that in water. Temperature fluctuation intensity in sodium is small at the neighborhood of the wall surface in comparison with that at the furthest position from the wall. In water case, on the other hand, temperature fluctuation intensity near the wall was slightly larger than that at the furthest position from the wall. In sodium, the power spectrum density (PSD) near the wall was close to the PSD at the furthest position from the wall. In water, however, the prominent frequency diminished in the PSD near the wall. The vanished frequency component was shifted to the lower frequency components. The space distributions and frequency characteristics of temperature fluctuations were obtained and differences were discussed with fluid property in sodium and water experiments. (authors)

270

Measuring historic water levels of Lake Balaton and tributary wetlands using georeferenced maps  

Science.gov (United States)

Lake Balaton is a large and relatively shallow lake located in western Hungary. The lake is joined by small wetlands on the north shore and larger water-filled valleys on the south separated by and elevated sand bar. These wetlands are assumed to have been connected with Lake Balaton before the water level was artificially lowered in 1893. No regular measurements of the water level of the lake or these wetlands were carried out before the draining of the lake. Most of the wetlands were completely isolated from the water system of the lake after the water level change as roads, railway and holiday homes were built. The low valleys of the southern shore still hold many fishponds, swamps and wet meadows, which are important sanctuaries for rare wetland species, and are often less disturbed than the lake, which is a popular holiday resort. Hydrologic restoration of these wetlands is only possible if accurate information exists on the original, natural state. The 1776 Krieger-map and the first military survey (1782-1785) are the most accurate known maps of the original state of the Lake Balaton area. These maps were surveyed using triangulation and leveling, and are accurate enough to be compared with the present-day situation. Some of the depicted buildings and landmarks still survive and can be used as control points for georeferencing and correcting these maps. Since the bathymetry of the lake and the topography of the surrounding countryside have hardly changed, existing digital elevation models of the present-day relief could be compared to these georeferenced maps. The elevation profile of the lake shore and wetland borders can be calculated by tracing these lines on a Digital Elevation Model. The shore area of Lake Balaton has been filled in and changed, so present-day land topography can not be used to estimate the water level from the elevation profile of the shore line. However, the Krieger-map also shows bathymetric contours, and previous studies have shown that the topography of the lake floor has not changed measurably in the last hundred years. The bathymetric contours of Lake Balaton depicted on the georeferenced Krieger-map were digitized and overlain on the present-day DEM of the lake floor. The elevation profile of these lines was used to calculate the original elevation of the water level of the lake with the accuracy of one meter. The height of the water table around the lake depends closely on the water level of the lake, but wetlands can retain water and thus sustain a higher water table in the tributary valleys than in the lake itself. In order to measure the elevation of the water table around the lake, the borders of the water-logged areas on the southern shore of the lake were also digitized from the sheets of the First Military Survey and traced on a DEM of the hills on the southern side of the lake. The elevation of the water level in these wetlands was calculated based on these profiles. The water level in some valleys adjoining the lake is significantly higher than the water level of the lake itself, which shows that the water balance of these wetlands was mostly independent of the fluctuation of the lake. Some other large wetlands have borders that are in the same elevation as the shores of the lake itself, which shows that these wetlands are in close connection with the lake. The mapping of these historic wetland properties provides a valuable guide for future habitat restoration efforts.

Zlinszky, A.

2009-04-01

271

Differential equations governing slip-induced pore-pressure fluctuations in a water-saturated granular medium  

Science.gov (United States)

Macroscopic frictional slip in water-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic pore-pressure fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and pore-water pressures. Solid displacements and water pressures are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible pore deformation that occurs along the bumpy slip surface. Feedback between this deformation and the pore-pressure field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.

Iverson, R.M.

1993-01-01

272

Determination of Heavy Metal Levels in Various Industrial Waste Waters  

Directory of Open Access Journals (Sweden)

Full Text Available Important part of the environmetal pollution consists of waste water and water pollution. The water polluted by anthropogenical, industrial, and agricultural originated sources are defined as waste waters which are the main pollution sources for reservoirs, rivers, lakes, and seas. In this work, waste waters of leather, textile, automotive side, and metal plating industries were used to determine the levels of Cu, Zn, Cr, Pb and Ni by using Flame Atomic Absorption Spectrometer. As a result, highest mean levels of copper in supernatants of plating and textile industries were observed as 377,18 ng ml-1, respectively 103 ng ml-1 lead and 963,6 ng ml-1 nickel in plating industry, 1068,2 ng ml-1 zinc and 14557,1 ng ml-1 chromium in plating and leather industries were determined.

Mustafa ?ahin Dündar

2012-06-01

273

The Dead Sea: Impacts of the Rapidly Declining Water Level and the Expected "Anthropogenic" Meromixis Upon Water Level Stabilization  

Science.gov (United States)

The Dead Sea (DS) is a highly perturbed terminal lake experiencing major changes in its limnology. Exploitation of water resources in its drainage basin as well as salt extraction through brine evaporation by Israeli and Jordanian chemical industries have resulted in a decline of its water level by more than 25 meter over the past few decades. The DS current level, which is the lowest surface on Earth, is 418 meters below mean sea level, and the level continues to drop at a rate of about 1 m/yr. This represents annual water deficient of about 650 MCM/yr, which is equivalent to more than a third and a half of the water consumptions in Israel and Jordan, respectively. The declining water level is having negative environmental impacts on the lake's surroundings such as exposure of large mud flats and development of sinkholes in the vicinity of the lake. Yet, it is unlikely that in this water scarce region, stabilization of the DS level would be achieved through new freshwater allocation. Introduction of seawater, which is being considered today as a mean of stabilizing or raising lake level, will however have other environmental impacts, including changes in the DS chemical composition. We present a study providing forecast for the evolution of the DS under different operational scenarios, including conveyance of seawater from the Red Sea. The impact of increasing inflows (fresh or seawater) on the lake's dynamics is considered. All scenarios assumed continuation of operation of the chemical plants. Modeling was carried out using the modified 1-D POM-based code adopted for the DS chemistry. Long term dilution and the development of meromixis is expected to occur when lake level is raised. However, we show that meromixis would occur also when inflow volumes are smaller but enough to stabilize water level or decrease the current rate of water level decline. This seemingly unlikely behavior of a terminal lake experiencing a negative or a balanced water regime will be due to the continued operation of the chemical industries. Stratification develops because of excess inflow over evaporation, while water level decline occurs due to brine withdrawal from the hypolimnion by the industries. Anthropogenic impact would thus continue to control the DS evolution, even if lake level is stabilized. If the additional inflow is derived from seawater, the anthropogenic impact on the DS evolution would be even more pronounced.

Gavrieli, I.; Dvorkin, Y.; Lensky, N. G.; Lyakhovsky, V.

2006-12-01

274

Impacts of Water Levels on Breeding Canada Geese and the Methodology for Mitigation and Enhancement in the Flathead Drainage, 1983 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

The lower Flathead River Canada goose study was initiated to determine goose population trends and the effects of water level fluctuations on Canada goose nest and brood habitat, as a result of releases from Kerr Dam. This report presents data collected during the 1983 field season (15 February to 30 September, 1983) as part of an ongoing project. (DT)

Ball, I. Joseph

1984-01-01

275

Characterisation of Culex quinquefasciatus (Diptera: Culicidae) larval habitats at ground level and temporal fluctuations of larval abundance in Córdoba, Argentina  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The aims of this study were to characterise the ground-level larval habitats of the mosquito Culex quinquefasciatus, to determine the relationships between habitat characteristics and larval abundance and to examine seasonal larval-stage variations in Córdoba city. Every two weeks for two years, 15 [...] larval habitats (natural and artificial water bodies, including shallow wells, drains, retention ponds, canals and ditches) were visited and sampled for larval mosquitoes. Data regarding the water depth, temperature and pH, permanence, the presence of aquatic vegetation and the density of collected mosquito larvae were recorded. Data on the average air temperatures and accumulated precipitation during the 15 days prior to each sampling date were also obtained. Cx. quinquefasciatus larvae were collected throughout the study period and were generally most abundant in the summer season. Generalised linear mixed models indicated the average air temperature and presence of dicotyledonous aquatic vegetation as variables that served as important predictors of larval densities. Additionally, permanent breeding sites supported high larval densities. In Córdoba city and possibly in other highly populated cities at the same latitude with the same environmental conditions, control programs should focus on permanent larval habitats with aquatic vegetation during the early spring, when the Cx. quinquefasciatus population begins to increase.

Marta, Grech; Paolo, Sartor; Elizabet, Estallo; Francisco, Luduena-Almeida; Walter, Almiron.

2013-09-01

276

Cadmium level: a comparative study in district Abbottabad's drinking water  

International Nuclear Information System (INIS)

Abbottabad is a beautiful city of North West Frontier Province of Pakistan. A comparative study was conducted in order to see cadmium (Cd) level in drinking water of Abbottabad. 81 water samples were collected from wells, hand pumps, boring and municipal water distribution points. The samples were analyzed on atomic absorption spectrophotometer at Quaid-e-Azam University, Islamabad for the assessment of Cd level. The district Abbottabad was divided into five zones. Zone 1 consists of tehsil Havalian (16 samples), zone 2 consists of Qalanderabad to Mirpur area (16 samples), zone 3 consists of Nathiagali to Naryan area (21 samples), zone 4 consists of Sherwan to Shimla Hills area (13 samples), and zone 5 consists of Abbottabad City and Cantonment area (16 samples). The exact location of sampling points is shown in figure 1. Majority of the samples show Cd level within safe limits as described by World Health Organization (WHO) i.e. 3 micro g/l to 5 micro g/l. But in Zone 3 sample No.16,17, 18, 19 and zone 5 sample no 5 to 12 show high level of Cd. The results with respect to toxicity are dangerous to health. It is believed that this high level of Cd is due to underground mineral environment or due to seepage of domestic and Industrial waste water. Plumbing system of water supplies may also contribute to the increase of Cd level. According to municipal authorities in these areas the water supply (pipe line) has been laid before the creation of Pakistan (1947). Due to Poshe creation of Pakistan (1947). Due to Possible dangerous effect of Cd on health and environment, it is suggested that this higher level of Cd should be removed from water. We can use electrodialysis, revers osmosis or ion exchange processes consisting of resins (like Amberlite DP-1/ Amberlite IRC-718 for this purpose. (author)

277

Great Lakes Water Levels Bounce Back After Record Lows  

Science.gov (United States)

Water levels in the Great Lakes have rebounded dramatically from historic lows in December 2012 and January 2013, though the levels still remain lower than average in some of the lakes, scientists with the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Army Corps of Engineers said during a 20 November briefing. The low lake levels had hampered shipping and other commercial and recreational uses of the waterways.

Showstack, Randy

2013-12-01

278

Millennial-scale fluctuations in North Atlantic surface-water temperatures and salinities during MIS 100  

Science.gov (United States)

Given its proximity to the large dynamic ice-sheets of the northern hemisphere and the role in deep-water formation the North Atlantic represents on of the climatically sensitive regions on Earth. Hence, data sets in key areas like the North Atlantic are extremely useful in order to e.g. quantify and reconstruct the paleoceanographic dynamics of the Pliocene. The broad objective of this study is to quantify, at millennial time-scales, paleoclimatic and paleoceanographic changes during the Late Pliocene (MIS 99 to 101). These objectives will be met by the integration of the Mg/Ca paleotemperature method and its use to allow a differentiation between changes in global ice-volume and SST. The recently drilled Integrated Ocean Drilling Program Site 1313 from the central North Atlantic (50°N) provides an ideal opportunity to tackle these questions. A demonstrably complete Mid to Late Pliocene section for Site 1313 was recovered, consisting mainly out of nannofossil ooze and nannofossil silt. A very high sedimentation rate and the abundant and well-preserved microfossils provide the requirements for high-resolution studies on planktic foraminifera and optimal reconstruction of the phasing of SST records and their relationship to salinity and ice-sheet changes on a high temporal resolution. For this study 145 samples in 2-cm spacing (resulting in a ~400 years resolution) of isotope stages MIS 99 to 101 were prepared for parallel Mg/Ca and stable isotope analyses. Per sample 60 tests of G. ruber were picked from the 212 to 250 ?m size interval and subsequently split in half for Mg/Ca and stable isotope analyses. Mg/Ca ratios of the samples were measured by inductively coupled plasma-optical emission spectrometry.

Friedrich, O.; Bolton, C. T.; Wilson, P. A.; Schiebel, R.

2009-04-01

279

Relation of drainage problems to high ground-water levels, Coconut Grove area, Oahu, Hawaii  

Science.gov (United States)

Purpose and Scope In 1969, hydrologic data-collection sites were established in and around the Coconut Grove area for the purpose of measuring directly the relationship between rainfall, runoff, ground-water levels, the level of water in Kawainui Swamp and the canals, and tidal fluctuations. The primary objective was to identify the causes of the occurrence and persistence of flooding and to gain data on which to base recommendations for remedial action. The scope of the study included establishing and operating flow and stage-recording gages on the Swamp, Kawainui Canal, and the inner canal; periodic and repeated measurements of ground-water level in test borings throughout the residential area; collection and analysis of soil and construction borings made for engineering purposes; the assembly and analysis of all available data relating surface and subsurface flow conditions, and the development of conclusions as to the causes and means to alleviate the flooding. This report summarizes the information collected from October 1969 to June 1971, includes analysis of the data, and discusses the probable causes of flooding.

Swain, L.A.; Huxel, C.J., Jr.

1971-01-01

280

Stable carbon and oxygen isotopes reveal Sahel drought events and ground water fluctuations in sub-Saharan Africa  

Science.gov (United States)

Tree rings are important proxies for paleoclimate studies because they contain continuous historical records of inter-annual and intra-annual time resolutions, which range over hundreds of years. This study uses stable carbon and oxygen isotopes in tree rings to understand the drivers and impacts of climate change in sub-Saharan Africa and their ability to reconstruct past regional climate variability and climatic trends. Our approach considers large scale climate gradients and different temporal scales (inter-annual and intra-annual variations) and combines multi- parameter measurements (carbon and oxygen isotopes, whole wood and cellulose measurements). The study species are Faidherbia albida and Sclerocarya birrea from south and West Africa, respectively. Both are very important deciduous trees, and widely distributed in sub-Saharan Africa. Particularly, F. albida has a distinctive phenology; it bears leaves and flowers during the dry season and sheds its leaves during the rainy season. Stable carbon (?13C) and oxygen (?18O) mean values showed similar inter annual patterns. In general, both ?13C and ?18O show negative correlations with rainfall, humidity and PDSI. On the contrary, they are positively correlated with sunshine hours, maximum temperature and evaporation. The reverse phenology of Faidherbia and intra seasonal resolution measurements reveals seasonal ground water fluctuations. Both carbon and oxygen stable isotopes showed strong climatic signals including the long Sahel drought events and climatic recovery phases.

Gebrekirstos, Aster

2014-05-01

 
 
 
 
281

Perchlorate levels in soil and waters from the Atacama Desert.  

Science.gov (United States)

Perchlorate is an anion that originates as a contaminant in ground and surface waters. The presence of perchlorate in soil and water samples from northern Chile (Atacama Desert) was investigated by ion chromatography-electrospray mass spectrometry. Results indicated that perchlorate was found in five of seven soils (cultivated and uncultivated) ranging from 290 ± 1 to 2,565 ± 2 ?g/kg. The greatest concentration of perchlorate was detected in Humberstone soil (2,565 ± 2 ?g/kg) associated with nitrate deposits. Perchlorate levels in Chilean soils are greater than those reported for uncultivated soils in the United States. Perchlorate was also found in superficial running water ranging from 744 ± 0.01 to 1,480 ± 0.02 ?g/L. Perchlorate water concentration is 30-60 times greater than levels established by the United States Environmental Protection Agency (24.5 ?g/L) for drinking. PMID:24165784

Calderón, R; Palma, P; Parker, D; Molina, M; Godoy, F A; Escudey, M

2014-02-01

282

The low-frequency fluctuating pattern of monthly mean sea level in the tropical Pacific and the correlation between it and El Nino  

Science.gov (United States)

A long-term series analysis has been conducted of the SST in the Eastern Equatorial Pacific and the monthly MSL in the Tropical Pacific. Their quasiperiodic and low-frequency oscillation features are discovered as follows. The significant periods of low-frequency fluctuations for monthly MSL in the area of 20° N-20° S are between 43.5 months and 50.0 months, approximately 47.6 months which is the significant period of SST in the Eastern Equatorial Pacific. From the results of space-spectral analysis, the low-frequency fluctuations of monthly MSL in the Tropical Pacific Ocean appear to have an anticlockwise circularly-propagating pattern, i.e., the Eastern Pacific—the area of NEC—the Western Equatorial Pacific—the area of NECC—the Eastern Equatorial Pacific. The phases of the pattern correspond to those of El Nino cycle. In addition, some conclusions from our study indicate that the intensification of westward transport by NEC may be the initial cause of the accumulation of warm surface water in the Western Equatorial Pacific. It also shows that the low-frequency fluctuation of MSL in the Southern Pacific perhaps follows an anticlockwise propagating pattern, i.e., the Eastern Pacific—the area of SEC—the Western Equatorial Pacific—the area of SECC—the Eastern Pacific.

Yu, Jiye; Chen, Shangji; Fang, Xinhua

283

An Indirect Adaptive Controller to Regulate UTSG Water Level in Pressurized Water Nuclear Reactor  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Stabilizing water level of the Steam Generator (SG) in nuclear power plant is a very important problem since its parameters vary with operating conditions and dynamics of the system is very different according to the power levels and changes as time goes on. Therefore, it is an intractable as well as challenging task to improve the water level control system of the SG. In this study, a new framework for building an adaptive Minimum Variance controller for stabilizing water-level of SG is prop...

Djamel Boukhetala; Touati Sai; Khaled Halbaoui; Feres Boudjema

2012-01-01

284

Daily water level by ENVISAT altimetry of the Amazon River  

Science.gov (United States)

Radar Altimetry is a remote sensing technique applied in order to obtain the level of water of the hydrological processes, mostly in remote regions such as in the Amazon basin. However, the altimetry satellites have a limitation in their temporal resolution, which in the case of ENVISAT is 35 days, which prevents the study of short-term hydrological events alert of floods and droughts and etc. Thus, a method of obtaining altimetric daily time series water level, based on a linear model of interpolation by optimization with multi-objective criteria was applied, using data from in situ on pluvial stations, along the Amazon River. The altimetry data validation show accurate results with a RMS of 11 cm, while the estimates carried out by the model obtained 63% of altimetric daily time series water level data with RMS less than 40 cm, thus allowing the use of altimetry data daily at various hydrological studies, hydrodynamic modeling and monitoring of extreme events.

Sousa, A. C.; Pereira, P.; Silva, J. S.; Calmant, S.; Seyler, F.

2013-05-01

285

Experimental detection of radiative energy signal from a supercharged marine boiler and simulation on its application in control of drum water level  

International Nuclear Information System (INIS)

This paper describes a study on the application of a flame detecting system installed in a marine supercharged boiler. Flame images captured from experiments show that fluctuation of the flame in the supercharged boiler is intensive than that in stationary power plant boilers. Radiative Energy Signal (RES) is obtained from experiments by the flame detecting system, and it is shown that RES varies approximately linearly with the oil consumption rate and the heat absorption rate in the riser. Then, an instantaneous heat absorption rate is deduced from the real time RES by a linear equation, and a control strategy for the water level in drum by RES is proposed, in which the real time RES is used to control the flow rate of feed water in advance. Simulation results show that the fluctuating amplitude of the water level can be reduced significantly by introducing RES, and this control strategy has a great potential to improve the control quality of drum water level in the supercharged boiler. - Highlights: ? We install a flame detecting system on a marine boiler to monitor furnace combustion. ? We use flame image processing technology to analyze the boiler combustion behavior. ? A control strategy is proposed as introducing RES into the feed water control system. ? Simulation shows the drum water level overcome fluctuations by inducing RES. ? Experiments state this strategy and detecting method for improving combustion efficiency.

286

Estimation of the influence of level fluctuations of the Caspian Sea on navigation and development of activities on the improvement of the condition of the infrastructure of waterways in the delta of the Astrakhan region  

Directory of Open Access Journals (Sweden)

Full Text Available According experts’ forecasts, the fall of the level of the Caspian Sea, which has been recently stabilized on the mark – minus 26.5 m. on the coast of the Russian Federation, is expected. The modern condition of waterways of the Astrakhan region is considered due to the fact that navigation belongs to basic branches of the national economy, depending on fluctuations of the sea level. It is noticed that many objects of the infrastructure of the Astrakhan region, such as industrial enterprises, agricultural and fishing organizations, and ports, including the port Olya, are situated in so-called "coastal zone of risk". It is offered to apply bank protection of half-slope type as means to protect the given territo-ries from the influence of waters of the Caspian Sea. It is a levee, which frontal slope is strengthened by precast concrete slabs.

Karasaeva Al’finur Ravil’evna

2010-10-01

287

Fore reef upper slope mixed sedimentation response to penultimate glacial interglacial sea level fluctuations: IODP Hole 325-M0058A , Great Barrier Reef, Australia  

Science.gov (United States)

High resolution stratigraphy in IODP Expedition 325 Hole-M0058A(58A) shows that the mixed carbonate siliciclastic sedimentary section, cored on the upper slope of the Great Barrier Reef (GBR) SE of Cairns, corresponds to the last 200 ky or almost two full late Quaternary glacial-interglacial cycles. Contrary to what has been observed in similar settings, strontium (Sr) and silica (Si) X-ray Fluorescence counts-proxies for reef-derived carbonate and terrigenous exports to the upper slope, respectively-appear to be out of phase of well-established models such as highstand shedding for periplatform sediment and lowstand shedding for siliciclastics systems. Hole 58A, drilled at 167 mbsl, is the deepest site along a 7 site transect SE of Cairns offshore the GBR. The recovered 41.4 m-long sedimentary sequence is mainly composed of three unconsolidated green mud sections intercalated with two distinct sandy intervals. The close proximity to the modern GBR and shallow water depth of this hole allows for dramatic changes in sedimentation and energy as a result of the glacial-interglacial high amplitude sea level fluctuations. Planktic foraminifer tests of the species Globigerinoides ruber (white) were picked and analyzed every 10 cm to produce a high resolution oxygen isotope record at Hole 58A. This record clearly exhibits ?18O cyclic variations that are interpreted to correspond with Marine Isotope Stages (MIS) 1-7 or the last 200ky. The disappearance of G. ruber (pink) at 28.5 m, in addition to several uranium/thorium dates, confirm that the interval between 30 and 28 m characterized by a sharp ?18O decrease corresponds to Termination II; moreover three radiocarbon ages (6550 years BP or younger) within the top 6 m of Hole 58A confirm the Holocene. Throughout Hole 58A, Sr and Si count variations appear to be out of phase suggesting periods of alternating neritic and terrigenous input dominance to the upper slope. The pattern, however, does not follow the typical reciprocal mixed system model of highstand carbonates and lowstand siliciclastics. Interglacial MIS 7 corresponds with the highest high Sr values that unexpectedly remain high into the early stages of glacial MIS 6. During the early Termination II, Sr and Si counts increase as ?18O values decrease, then Sr counts decrease and remain low during late Termination II and MIS 5e interglacial peak, while Si counts continue to increase during late Termination II remaining high during MIS 5e. Sr counts rise during the MIS 5e interglacial to 5d glacial transition and remain high until Sr counts drop off before interglacial MIS 5a. This is uncharacteristic when compared to similar holes on the upper slopes of the GBR and Gulf of Papua, suggesting a local phenomenon. A possible explanation is that, during Termination II, terrigenous material was flushed off the previously exposed GBR continental shelf, causing the fledgling reef to be choked by turbid water, therefore reducing neritic export. Not until sea level began to fall during the MIS 5e-5d transition, did water become shallow enough to allow coralgal reef production to be turned on again. The unexpected result is that during the MIS 5e maximum high sea level, when the reef should have been exporting aragonite to the upper slopes, terrigenous sedimentation dominated.

Harper, B.; Bernabéu; Droxler, A. W.; Webster, J. M.; Thomas, A. L.; Tiwari, M.; Gischler, E.; Jovane, L.; Morgan, S.; Lado-Insua, T.

2012-12-01

288

Effects of Water Levels on Productivity of Canada Geese in the Northern Flathead Valley, 1984 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

Operation of Hungry Horse Dam on the South Fork Flathead River causes sporadic level fluctuations along the main stem Flathead River. Seasonal water level fluctuations and substantial habitat losses have occurred as a result of construction and operation of Kerr Dam, which regulates Flathead Lake. These fluctuations may impact goose populations through flooding or erosion of nesting and brood-rearing habitats, and increased susceptibility of nests and young to predation. The number, location, and success of goose nests were determined through pair surveys and nest searches. Counts of indicated pairs suggest there were 73-125 occupied nests in the study area; 44 were located in 1984. Twenty were island ground nests, 19 were tree nests, and 5 were on man-made structures. Hatching success was 76 percent. Sixty-one percent of all nests were in deciduous forest habitat; 87 percent were on riparian bench or island landforms. Seventy-four percent of all nests were within 5 m of the seasonal high water mark (HWM) and 85 percent of ground nests were 1 m or less above the HWM. Production, habitat use, and distribution of broods were documented through aerial, boat, ground, and observation tower surveys. 28 refs., 10 figs., 4 tabs.

Casey, Daniel

1985-02-01

289

Measurement of water potential in low-level waste management  

International Nuclear Information System (INIS)

The measurement of soil water is important to the shallow land burial of low-level waste. Soil water flow is the principle mechanism of radionuclide transport, allows the establishment of stabilizing vegetation and also governs the dissolution and release rates of the waste. This report focuses on the measurement of soil water potential and provides an evaluation of several field instruments that are available for use to monitor waste burial sites located in arid region soils. The theoretical concept of water potential is introduced and its relationship to water content and soil water flow is discussed. Next, four major areas of soils research are presented in terms of their dependence on the water potential concept. There are four basic types of sensors used to measure soil water potential. These are: (1) tensiometers; (2) soil psychrometers; (3) electrical resistance blocks; and (4) heat dissipation probes. Tensiometers are designed to measure the soil water potential directly by measuring the soil water pressure. Monitoring efforts at burial sites require measurements of soil water over long time periods. They also require measurements at key locations such as waste-soil interfaces and within any barrier system installed. Electrical resistance blocks are well suited for these types of measurements. The measurement of soil water potential can be a difficult task. There are several sensors commercially available; however, each has its own limitations. It is important to carefully select the appropriate sensor for the job. The accuracy, range, calibration, and stability of the sensor must be carefully considered. This study suggests that for waste management activities, the choice of sensor will be the tensiometer for precise soil characterization studies and the electrical resistance block for long term monitoring programs

290

Flashing characteristics in pipe downstream from a depressurizing tank and temperature fluctuation characteristics at a mixing tee junction with cold water injection  

International Nuclear Information System (INIS)

The flashing characteristics in a pipe downstream from a depressurizing tank were experimentally and analytically investigated on the basis of the transient test and two-phase flow analysis. The following three conclusions were obtained. (1) When the pressure margin of the pump inlet side and the distance to obtain an isothermal condition were sufficient, flashing phenomena did not occur in spite of the decreasing pressure. (2) When the ratio of the cold water injection flow rate to the hot water flow rate Mc/Mh increased, the peak distance of the water temperature fluctuation moved from L/D=1 to 0, and the maximum water temperature fluctuation ratio was about 40% of the temperature difference between hot and cold water near the mixing tee junction. But no problem occurred regarding the pipe material thermal fatigue, so reliability of the mixing tee junction was assured. (3) Due to suppression of flashing phenomena of the mixing pipe system, the decision diagram on the flashing occurrence was obtained from test and analytical results, taking into consideration three factors : the depressurizing ratio in the tank ; the cold water injection flow rate due to remaining sub-cooling ; and the delay time of thermal mixing. The simplified analytical equation was used to decrease the cold water injection flow rate by the optimized pipe length between the mixing tee junction and drain pump. The cold water injection flow rate was minimized when pipe length was about 15 to 20 times the pipe inner diameter. (author)

291

Flashing characteristics in pipe downstream from a depressurizing tank and temperature fluctuation characteristics at a mixing tee junction with cold water injection  

Energy Technology Data Exchange (ETDEWEB)

The flashing characteristics in a pipe downstream from a depressurizing tank were experimentally and analytically investigated on the basis of the transient test and two-phase flow analysis. The following three conclusions were obtained. (1) When the pressure margin of the pump inlet side and the distance to obtain an isothermal condition were sufficient, flashing phenomena did not occur in spite of the decreasing pressure. (2) When the ratio of the cold water injection flow rate to the hot water flow rate M{sub c}/M{sub h} increased, the peak distance of the water temperature fluctuation moved from L/D=1 to 0, and the maximum water temperature fluctuation ratio was about 40% of the temperature difference between hot and cold water near the mixing tee junction. But no problem occurred regarding the pipe material thermal fatigue, so reliability of the mixing tee junction was assured. (3) Due to suppression of flashing phenomena of the mixing pipe system, the decision diagram on the flashing occurrence was obtained from test and analytical results, taking into consideration three factors : the depressurizing ratio in the tank ; the cold water injection flow rate due to remaining sub-cooling ; and the delay time of thermal mixing. The simplified analytical equation was used to decrease the cold water injection flow rate by the optimized pipe length between the mixing tee junction and drain pump. The cold water injection flow rate was minimized when pipe length was about 15 to 20 times the pipe inner diameter. (author)

Shiina, Koji; Takahashi, Shirou [Hitachi Ltd., Power and Industrial Systems, Power and Industrial Systems R and D Laboratory, Hitachi, Ibaraki (Japan); Asada, Yukihiro [Hitachi Ltd., Ibaraki (Japan). Hitachi Works

2000-03-01

292

Condensation heat transfer of a co-current steam-water stratified flow in a rectangular channel and temperature fluctuations near the interface  

International Nuclear Information System (INIS)

Fundamental phenomena of condensation heat transfer at a steam-water interface have been studied related to the thermo-hydrodynamics of the emergency core cooling system for light water reactors. Temperature fluctuations in the liquid phase and near the interface were measured using the fine thermocouples and heat transfer coefficient was determined experimentally. The condensation heat transfer coefficient increased with the steam and water Reynolds numbers. Extraordinary temperature rise beyond the saturation temperature was observed in steam phase close to the interface. (author)

293

Development of an in-vessel water level gauge for light water power reactors  

International Nuclear Information System (INIS)

The in-vessel water level gauge, in principle, is based on the measurement of the temperature distribution on the surface of a long sheathed heater-pin which is partially immersed in water. Instead of adopting the measurement with many thermocouples, a binary-coded thermocouple array consisting of differential thermocouple array consisting of differential thermocouple trains (DTCTs) is settled on or in the sheath of a heater-pin to give a binary output related to the water level. Thus, this new-type of water level gauge was named BICOTH (Binary-Coded Thermocouple-array with Heater). After feasibility tests of the method with a prototype BICOTH, two types of in-vessel BICOTH were fabricated. The performance of each type was examined under the conditions of cold water and high-temperature, high-pressure water, and encouraging results were obtained. The principle and the test results are presented

294

AUTOMATED WATER LEVEL MEASUREMENTS IN SMALL-DIAMETER AQUIFER TUBES  

Energy Technology Data Exchange (ETDEWEB)

Groundwater contaminated with hexavalent chromium, strontium-90, and uranium discharges into the Columbia River along approximately 16 km (10 mi) of the shoreline. Various treatment systems have and will continue to be implemented to eliminate the impact of Hanford Site contamination to the river. To optimize the various remediation strategies, it is important to understand interactions between groundwater and the surface water of the Columbia River. An automated system to record water levels in aquifer sampling tubes installed in the hyporheic zone was designed and tested to (1) gain a more complete understanding of groundwater/river water interactions based on gaining and losing conditions ofthe Columbia River, (2) record and interpret data for consistent and defensible groundwater/surface water conceptual models that may be used to better predict subsurface contaminant fate and transport, and (3) evaluate the hydrodynamic influence of extraction wells in an expanded pump-and-treat system to optimize the treatment system. A system to measure water levels in small-diameter aquifer tubes was designed and tested in the laboratory and field. The system was configured to allow manual measurements to periodically calibrate the instrument and to permit aquifer tube sampling without removing the transducer tube. Manual measurements were collected with an e-tape designed and fabricated especially for this test. Results indicate that the transducer system accurately records groundwater levels in aquifer tubes. These data are being used to refine the conceptual and numeric models to better understand interactions in the hyporheic zone of the Columbia River and the adjacent river water and groundwater, and changes in hydrochemistry relative to groundwater flux as river water recharges the aquifer and then drains back out in response to changes in the river level.

PETERSEN SW; EDRINGTON RS; MAHOOD RO; VANMIDDLESWORTH PE

2011-01-14

295

Characteristics of fluid temperature fluctuation in a mixing tee pipe with hot and cold water flows; Koonsui to teionsui ga kongosuru T jigata goryu haikan no ryutai ondo hendo tokusei  

Energy Technology Data Exchange (ETDEWEB)

Plants have many tee pipes where a hot fluid and cold fluid flow into each other and mix. The mixing of hot and cold water can cause a fluid temperature fluctuation which leads to the temperature fluctuation of the inner pipe wall, so characteristics of this fluctuation in the mixing tee pipe were investigated through experiments. This paper shows the three mixing flow patterns in the tee pipe, i. e. stratified flow, turned jet and wall jet, the location of the maximum fluid temperature fluctuation and fluid temperature fluctuation characteristics downstream from the tee pipe. The experiments showed that characteristics of the fluid temperature fluctuation were largely related to the flow pattern in the tee pipe. The flow pattern of the turned flow in the tee pipe could suppress the fluid temperature fluctuation. (author)

Takahashi, S.; Shiina, K. [Hitachi, Ltd., Tokyo (Japan)

2000-11-25

296

CAN FLUORIDATION AFFECT WATER LEAD LEVELS AND LEAD NEUROTOXICITY?  

Science.gov (United States)

Recent reports have attempted to show that certain approaches to fluoridating potable water is linked to increased levels of lead(II) in the blood. We examine these claims in light of the established science and critically evaluate their significance. The completeness of nexafluo...

297

Effects of Water Levels on Productivity of Canada Geese in the Northern Flathead Valley, 1985 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

Operation of Hungry Horse Dam on the South Fork Flathead River causes sporadic water level fluctuations along the main stem Flathead River. Changes in chronology of seasonal water level fluctuations and substantial habitat losses have occurred as a result of construction and operation of Kerr Dam, which regulates Flathead Lake. These fluctuations may impact goose populations through flooding and erosion of nesting and brood-rearing habitats, and increased susceptibility of nests and young to predation. The number, location, and success of goose nests were determined through pair surveys and nest searches. Our 1985 pair count data indicated that 95 to 143 nests may have been present. Hatching success for 1985 nests (55%) was low compared to long-term averages for the region. Predation was the predominant cause of ground nest failure (25 nests); we documented 2 nest failures due to flooding. The maximum gosling count in the study area for 1985 was 197. Six key brood-rearing areas were identified. Most (80%) sites were located in the herbaceous or pasture cover type and the riparian bench landform. Analysis of aerial photographs taken prior to construction of Kerr Dam documented the loss of 1859 acres of habitat along the north shore of Flathead Lake. Losses were attributed to inundation and to continuing erosion due to operation of Kerr Dam. Lake and river water level regimes were compared with the chronology of important periods in the nesting cycle. Low lake levels in May and early June coincide with the breed-rearing period. Mudflats are heavily used by broods, but their effect on survival must still be documented. Preliminary recommendations to protect and enhance Canada goose habitat and production are being developed.

Casey, Daniel

1986-04-01

298

The structure of spatial fluctuation in terrestrial gamma-ray dose rate levels observed through one-dimensional surveys  

International Nuclear Information System (INIS)

Statistical analyses were performed for 50 sets of equal interval data of natural terrestrial gamma-ray dose rates observed for various distances. The multiple regression analysis shows that the variance of a set of data can be expressed as a function of the length and the mean value of the data with relatively high correlation coefficient. One-dimensional spectral analyses for the 50 sets of data suggest that the structures of fluctuation are similar to one another for various distances of observation starting from 0.1 km to about 7000 km. Each power spectral density can be approximated in the form of P(k)=0.780 x 10-3 m2.20 k-1.18, where k (cycle/km) and m (nGy/h) are the wave number and the mean, respectively. (author)

299

Radioactivity levels in waters and sediments from Van Lake / Turkey  

International Nuclear Information System (INIS)

It is well known that natural radionuclides can be effective as tracers for the different processes controlling the distribution of elements dissolved and particulate phases in aquatic systems. Significant radiation doses to man can potentially occur following radioactive contamination of water bodies such as rivers, lakes and reservoirs. In the long term, radioactivity in the water body can remain at significant levels as a result of secondary contamination processes. The Van Lake is located at Eastern part of Turkey and it is largest Lake of Turkey. The purpose of this study is to measure natural radioactivity in the waters and sediments taken from along to shore of Van Lake. Total of 19 surface coast lake waters and 18 sediments samples were collected from Van Lake in dry season in 2005, in the first part of this Project. In surface lake water samples, pH, mV and conductivity values were measured and alkalinity content was determined titrimetrically. The uranium concentrations in the lake water samples were measured using uranium analyzer. Radioactivities related to gross radium isotopes, gross-? and gross-? radioactivity levels in the surface water were determined. Gross radium isotopes were separated using the barium sulphate co-precipitation method and then the radioactivity of gross radium isotopes was measured by ZnS(Ag) alpha scintillation counter. The correlation among measured parameters for water samples and concentrations of uranium and gross radium isotopes are also discussed. Natural radioactivity in the sediments was also determined by gamma spectrometer. The field and laboratory studies on this project are carried out

300

High-level water purifying technology. Kodo josui shori gijutsu  

Energy Technology Data Exchange (ETDEWEB)

Research and development have been carried out on a high-level water purifying system using ozone and activated charcoals to supply drinking water free of carcinogenic matters and odors. This system comprises a system to utilize ozone by using silent discharge and oxygen enriching device, and a living organism/activated charcoal treatment system. The latter system utilizes living organisms deposited on activated charcoal surfaces to remove polluting substances including ammonia. The treatment experimenting equipment comprises an ozone generating system, an ozone treating column, an activated charcoal treating column, an ozone/activated charcoal control device, and a water amount and quality measuring system. An experiment was carried out using an experimental plant with a capacity of 20 m[sup 3]/day on water taken from the sedimentation process at an actual water purifying plant. As a result, trihalomethane formation potential was removed at about 40% in the ozone treatment, and at 70% in the whole treatment combining the ozone and living organism/activated charcoal treatments. For parameterization of palatability of water, a method is being studied that utilizes nuclear magnetic resonance to investigate degrees of water cluster. The method is regarded promising. 1 ref., 4 figs.

Tsugura, H.; Tsukiashi, K. (Meidensha Corp., Tokyo (Japan))

1993-07-01

 
 
 
 
301

Mountain Pine Beetle Impact on Stand-level Water Balance  

Science.gov (United States)

The recent mountain pine beetle (MPB) epidemic has disturbed millions of hectares throughout the Rocky Mountain West. The most persistent effects of MPB infestation on the stand-level water balance are likely concomitant with the grey stage of the disturbance cycle. The grey stage occurs within 3 to 5 years of the initial infestation after the needles of an infected tree have turned red and fallen off due to tree death. Large numbers of grey-stage trees in a stand may remain on the landscape for up to 20 years, until windthrow or another disturbance sends them to the forest floor. The greater temporal persistence of the grey stage over antecedent stages suggested that an examination of the grey stage would best capture long-term effects of MPB disturbance on the forest water balance. In this study we hypothesized that changes to the forest canopy associated with MPB disturbance may affect the stand-level water balance. The needle loss and windthrow that follows MPB disturbance is expected to increase the amount of precipitation reaching the forest floor. Additionally, overstory evapotranspiration (ET) demand is expected to decrease as MPB-induced tree mortality increases within disturbed stands. The expected cumulative effect of MPB disturbance on the stand-level water balance is an increase in soil moisture due to increased precipitation inputs and reduced overstory ET. This study was conducted in Lubrecht Experimental Forest and adjacent Bureau of Land Management areas near Missoula, Montana. Sub-canopy measurements of soil moisture, precipitation (rain and snow water equivalent), overstory transpiration and micro-meteorological data (net radiation, temperature, wind speed, etc.) were collected in three 50 x 50 meter plots. The plots consisted of a uniform stand of grey-stage lodgepole pine, a uniform stand of non-infested lodgepole pine, and a recent clear-cut stand, which served as a control unit. Water balances for each stand were constructed using a mass-balance approach and compared to investigate how MPB disturbance affects the stand-level water balance. Preliminary results from the first of two years of data collection suggests wetter soils in the grey-stage stand compared to the non-infested and clear cut stands. Continued data collection and analysis will provide further insight into the partitioning of the stand-level water balance in the grey stage of MPB disturbance.

Reilly, J. A.; Woods, S.

2012-12-01

302

An analysis of the water-level monitoring system for a boiling-water reactor  

International Nuclear Information System (INIS)

The water-level instrumentation system is very important to the overall safety of a BWR. This system is being monitored by the Safety Parameter Display System (SPDS) that is being installed in Georgia Power Company's Plant Hatch. One of the most significant functions of the SPDS is the comparison of redundant instrument readings and formation of the best estimate of each parameter from those readings which are consistent. When comparing water-level instrument readings, it is necessary to correct the individual readings for differences between current and calibration conditions as well as for differences between calibration conditions for the multiple instruments. This paper documents the examination of the water-level instrumentation system at Plant Hatch and presents the development of the equations that were used to determine the differences between indicated and actual water levels. (author)

303

Do Estimates of Water Productivity Enhance Understanding of Farm-Level Water Management?  

Directory of Open Access Journals (Sweden)

Full Text Available Estimates of water productivity are appearing with increasing frequency in the literature pertaining to agronomy, water management, and water policy. Some authors report such estimates as one of the outcome variables of experiment station studies, while others calculate water productivities when comparing regional crop production information. Many authors suggest or imply that higher values of water productivity are needed to ensure that future food production goals are achieved. Yet maximizing water productivity might not be consistent with farm-level goals or with societal objectives regarding water allocation and management. Farmers in both rainfed and irrigated settings must address a complex set of issues pertaining to risk, uncertainty, prices, and opportunity costs, when selecting activities and determining optimal strategies. It is not clear that farmers in either setting will or should choose to maximize water productivity. Upon examining water productivity, both conceptually and empirically, using published versions of crop production functions, I conclude that estimates of water productivity contain too little information to enhance understanding of farm-level water management.

Dennis Wichelns

2014-03-01

304

Seasonal and abrupt changes in the water level of closed lakes on the Tibetan Plateau and implications for climate impacts  

Science.gov (United States)

Using ICESat laser altimetry data, we examine seasonal and abrupt changes in the water level of 105 closed lakes on the Tibetan Plateau (TP) from 2003 to 2009. The cluster analysis method is applied to categorize different temporal evolution patterns of lake level, and the links between abrupt lake-level variations of the different clusters in specific seasons and key climatic variables during 2003-2009 based on 12 weather stations are further analyzed. The results show that seasonal lake-level variations were featured by strong spatio-temporal heterogeneity. Most lakes, especially in south Tibet, the central and northeastern Tibetan Plateau, showed large water-level increases (0.307 ± 0.301 m/year) in warm seasons (March-October), while showed declines or minor fluctuations (-0.091 ± 0.202 m/year) in cold seasons (November-February). Many small lakes in the Changtang Plateau and northern TP showed negative water budgets in warm seasons due to low precipitation and strong evaporation, but positive water budgets depending on seasonal snow meltwater supply in cold seasons. These lakes can be partitioned into eight clusters according to the common characteristics of seasonal and consistent abrupt lake-level variations. Lakes of Clusters 4 and 5 are not analyzed in detail because of their scattered distributions. The abrupt lake-level rises or declines for Clusters 1, 2, 3, 7 were inferred to be closely associated with dramatic changes in precipitation and evaporation. For example, most lakes in Cluster 1 experienced the substantial water-level rises (?0.99 m on average) in the warm season of 2005, which were largely attributable to the high precipitation and low evaporation in this season. The abrupt changes of water level for lakes in Clusters 6 and 8 (in the Changtang Plateau and northern TP) were probably associated with more snow meltwater supply. Time series of GRACE-observed terrestrial water storage changes confirm that the abrupt lake-level changes in specific seasons are associated with abnormal hydro-climatological conditions. Besides, the limitations of spatial pattern analysis of lake variations classification based on cluster analysis and the possible primary causes of lake level fluctuations are discussed.

Song, Chunqiao; Huang, Bo; Ke, Linghong; Richards, Keith S.

2014-06-01

305

Fuzzy Neural Networks for water level and discharge forecasting  

Science.gov (United States)

A new procedure for water level (or discharge) forecasting under uncertainty using artificial neural networks is proposed: uncertainty is expressed in the form of a fuzzy number. For this purpose, the parameters of the neural network, namely, the weights and biases, are represented by fuzzy numbers rather than crisp numbers. Through the application of the extension principle, the fuzzy number representative of the output variable (water level or discharge) is then calculated at each time step on the basis of a set of crisp inputs and fuzzy parameters of the neural network. The proposed neural network thus allows uncertainty to be taken into account at the forecasting stage not providing only deterministic or crisp predictions, but rather predictions in terms of 'the discharge (or level) will fall between two values, indicated according to the level of credibility considered, whereas it will take on a certain value when the level of credibility is maximum'. The fuzzy parameters of the neural network are estimated using a calibration procedure that imposes a constraint whereby for an assigned h-level the envelope of the corresponding intervals representing the outputs (forecasted levels or discharges, calculated at different points in time) must include a prefixed percentage of observed values. The proposed model is applied to two different case studies. Specifically, the data related to the first case study are used to develop and test a flood event-based water level forecasting model, whereas the data related to the latter are used for continuous discharge forecasting. The results obtained are compared with those provided by other data-driven models - Bayesian neural networks (Neal, R.M. 1992, Bayesian training of backpropagation networks by the hybrid Monte Carlo method. Tech. Rep. CRG-TR-92-1, Dep. of Comput. Sci., Univ. of Toronto, Toronto, Ont., Canada.) and the Local Uncertainty Estimation Model (Shrestha D.L. and Solomatine D.P. 2006, Machine learning approaches for estimation of prediction interval for the model output. Neural Networks, 19(2), 225-235.). The comparison shows the effectiveness of the fuzzy neural network forecasting model in estimating water levels or discharges under uncertainty. In particular, the fuzzy neural network enables us to define bands that describe, for an assigned h-level, the range of variability of the predicted variable. An analysis of the results obtained reveals that these bands generally have a slightly smaller width compared to the bands obtained using other data-driven models, the percentage of observed values contained within the bands being equal.

Alvisi, Stefano; Franchini, Marco

2010-05-01

306

Quadratic controller syntheses for the steam generator water level  

International Nuclear Information System (INIS)

The steam generator water level, (SGWL), control problem in the pressurized water reactor of a nuclear power plant is considered from robust control techniques point of view. The plant is a time-varying system with a non minimum phase behavior and an unstable open-loop response. The time-varying nature of the plant due to change in operating power is taken into account by including slowly time-varying uncertainty in the model. A linear Time-Invariant, (LTI) guaranteed cost quadratic stabilizing controller is designed in order to address some of the particular issues arising for such a control problem. (author)

307

Quality Level of Bottled Drinking Water Consumed in Saudi Arabia  

Directory of Open Access Journals (Sweden)

Full Text Available The quality of drinking water is a universal health concern and access to safe water is a fundamental human right. Many national and international organizations set certain parameters and levels for Bottled Drinking Water (BDW to ensure their quality. The present work aims to analyze the quality of various brands of BDW used in Saudi Arabia and to compare the quality levels to the BDW standards. One hundred and twenty six samples of 54 different BDW brands were collected from the Saudi market. The quality level parameters were analyzed using portable meters for pH, EC and TDS; spectrophotometer, HACH DR-2800 for F, SO4 and NO3; Inductively Coupled Plasma (ICP Mass Spectrometer (MS and atomic emission spectrometer (AES for elemental analysis. To evaluate the quality level parameters of BDW, the parameters were classified as following: (1 Parameters and substances affect the quality of BDW (pH, EC, TDS, HCO3, F, NO3 and SO4. (2 Macronutrients (Ca, K, Mg and Na. (3 Micronutrients-trace elements (Co, Cr, Cu, Fe, Mo, Se and Zn, (4 Potentially essential elements that have some beneficial health effects (B, Mn, Ni and V and (5 Toxic elements (Al, As, Cd, Hg, Pb, Th and U using Inductively coupled plasma-mass spectrometry, ICP-MS. The concentrations of the detected elements were compared with the Golf and international standard like World Health Organization.

Ashraf E.M. Khater

2014-01-01

308

Holocene palaeoclimate and sea level fluctuation recorded from the coastal Barker Swamp, Rottnest Island, south-western Western Australia  

Science.gov (United States)

The Holocene palaeoclimatic history of south-western Western Australia (SWWA) has received little attention compared to south-eastern Australia, and this has resulted in conflicting views over the impact of climate variability in the region. We present here a well-dated, high-resolution record from two overlapping sediment cores obtained from the centre of Barker Swamp, Rottnest Island, offshore Perth. The records span the last 8.7 ka, with the main lacustrine phase occurring after 7.4 ka. This site preserves both pollen and several ostracod taxa. The pollen record suggests a long-term shift from the early-mid Holocene to the late Holocene to drier conditions with less shrubland and more low-ground cover and less fire activity. A salinity transfer function was developed from ostracod faunal assemblage data and trace metal ratios (Mg/Ca, Sr/Ca and Na/Ca) and stable isotopes (?18O and ?13C) analysed on selected ostracod valves. These provide a detailed history of evaporation/precipitation (E/P) differences that clearly shows that the SWWA region was subjected to significant climatic shifts over the last 7.4 ka, with a broad shift towards increased aridity after 5 ka. The swamp ranged from fresh to saline as recorded in the ostracod valve chemistry and the independently-derived salinity transfer function. The ostracod record also indicates that a sea-level highstand occurred between ca. 4.5 and 4.3 ka, with probable step-wise increases at 6.75, 6.2, and 5.6 ka, with the last vestiges of salt water intrusion at ca. 1 ka. After about 2.3 ka, the fresh, groundwater lens that underlies the western portion of the island intersected the swamp depression, influencing the hydrology of the swamp. The broad climatic changes recorded in Barker Swamp are also compared with data from southern South Africa, and it is suggested that the Southern Annular Mode appears to have been the dominant driver in the climate of these regions and that the Indian Ocean Dipole is of little importance in the southern regions of the south-western Cape of Africa and south-western Western Australia.

Gouramanis, C.; Dodson, J.; Wilkins, D.; De Deckker, P.; Chase, B. M.

2012-10-01

309

Decadal fluctuations in North Atlantic water inflow in the North Sea between 1958-2003: impacts on temperature and phytoplankton populations  

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Full Text Available The circulation of Atlantic water along the European continental slope, in particular the inflow into the North Sea, influences North Sea water characteristics with consequent changes in the environment affecting plankton community dynamics. The long-term effect of fluctuating oceanographic conditions on the North Sea pelagic ecosystem is assessed. It is shown that (i there are similar regime shifts in the inflow through the northern North Sea and in Sea Surface Temperature, (ii long-term phytoplankton trends are influenced by the inflow only in some North Sea regions, and (iii the spatial variability in chemicophysical and biological parameters highlight the influence of smaller scale processes.

Martin J. Attrill

2008-03-01

310

Dendrochronological evaluation of historic changes in Lake Stirniai (Lithuania) water level  

International Nuclear Information System (INIS)

Full text: Dendrochronological research was carried out on Pinus sylvestris L. timber extracted from Lake Stirniai (55o15'04'' latitude (N) and 25o38'49'' longitude (E)). As a result, the tree ring width floating chronology spanning 213 years was compiled. Radiocarbon dating of the samples indicated that pines grew from 1103 ± 80 AD to 1315 ± 80 AD. Fragments of stems and roots of pines were found waterlogged in 1 m water layer. It means that in the Medieval Warm Period, the ground water level in the habitat of archaeological pines was below the nowadays lake level for at least by 1 m. The growth conditions became unfavourable in ? 1270 ± 80 AD. At the end of the 13th century the climate became damper, lake transgression started, the trees of Scots pine became dry. The basic cause of transgression seems to be the bogged bed of the rivulet Stirna flowing out of the lake. This phenomenon was caused by the changed climate conditions. The formant analysis of the radial increase of the stems of archaeological Scots pine in Lake Stirniai revealed 52.9; 30.3; 21.1; 17.5; 15.0; 11.2 year long-term fluctuation cycles. Comparison of the obtained data with the present cycles is foreseen. (author)

311

Predicting the residual aluminum level in water treatment process  

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Full Text Available In water treatment processes, aluminum salts are widely used as coagulation chemical. High dose of aluminum has been proved to be at least a minor health risk and some evidence points out that aluminum could increase the risk of Alzheimer's disease thus it is important to minimize the amount of residual aluminum in drinking water and water used at food industry. In this study, the data of a water treatment plant (WTP was analyzed and the residual aluminum in drinking water was predicted using Multiple Linear Regression (MLR and Artificial Neural Network (ANN models. The purpose was to find out which variables affect the amount of residual aluminum and create simple and reliable prediction models which can be used in an early warning system (EWS. Accuracy of ANN and MLR models were compared. The new nonlinear scaling method based on generalized norms and skewness was used to scale all measurement variables to range [?2...+2] before data-analysis and modeling. The effect of data pre-processing was studied by comparing prediction results to ones achieved in an earlier study. Results showed that it is possible to predict the baseline level of residual aluminum in drinking water with a simple model. Variables that affected the most the amount of residual aluminum were among others: raw water temperature, raw water KMnO4 and PAC / KMnO4-ratio. The accuracies of MLR and ANN models were found to be almost equal. Study also showed that data pre-processing affects to the final prediction result.

J. Tomperi

2012-06-01

312

Predicting the residual aluminum level in water treatment process  

Directory of Open Access Journals (Sweden)

Full Text Available In water treatment processes, aluminum salts are widely used as coagulation chemical. High dose of aluminum has been proved to be at least a minor health risk and some evidence points out that aluminum could increase the risk of Alzheimer's disease. Thus it is important to minimize the amount of residual aluminum in drinking water and water used at food industry. In this study, the data of a water treatment plant (WTP was analyzed and the residual aluminum in drinking water was predicted using Multiple Linear Regression (MLR and Artificial Neural Network (ANN models. The purpose was to find out which variables affect the amount of residual aluminum and create simple and reliable prediction models which can be used in an early warning system (EWS. Accuracy of ANN and MLR models were compared. The new nonlinear scaling method based on generalized norms and skewness was used to scale all measurement variables to range [?2...+2] before data-analysis and modeling. The effect of data pre-processing was studied by comparing prediction results to ones achieved in an earlier study. Results showed that it is possible to predict the baseline level of residual aluminum in drinking water with a simple model. Variables that affected the most the amount of residual aluminum were among others: raw water temperature, raw water KMnO4 and PAC/KMnO4 (Poly-Aluminum Chloride/Potassium permanganate-ratio. The accuracies of MLR and ANN models were found to be almost the same. Study also showed that data pre-processing affects to the final prediction result.

J. Tomperi

2013-06-01

313

The Water Level Fall of Lake Megali Prespa (N Greece): an Indicator of Regional Water Stress Driven by Climate Change and Amplified by Water Extraction?  

Science.gov (United States)

The Mediterranean stands out globally due to its sensitivity to (future) climate change, with future projections predicting an increase in excessive drought events and declining rainfall. Regional freshwater ecosystems are particularly threatened: precipitation decreases, while extreme droughts increase and human impacts intensify (e.g. water extraction, drainage, pollution and dam-building). Many Mediterranean lake-wetland systems have shrunk or disappeared over the past two decades. Protecting the remaining systems is extremely important for supporting global biodiversity and for ensuring sustainable water availability. This protection should be based on a clear understanding of lake-wetland hydrological responses to natural and human-induced changes, which is currently lacking in many parts of the Mediterranean. The interconnected Prespa-Ohrid Lake system is a global hotspot of biodiversity and endemism. The unprecedented fall in water level (~8m) of Lake Megali Prespa threatens this system, but causes remain debated. Modelling suggests that the S Balkan will experience rainfall and runoff decreases of ~30% by 2050. However, projections revealing the potential impact of these changes on future lake level are unavailable as lake regime is not understood. A further drop in lake level may have serious consequences. The Prespa Lakes contribute ~25% of the total inflow into Lake Ohrid through underground karst channels; falling lake levels decrease this discharge. Lake Ohrid, in turn, feeds the Drim River. This entire catchment may therefore be affected by falling lake levels; its water resources are of great importance for Greece, Albania, FYROM and Montenegro (e.g. tourism, agriculture, hydro-energy, urban & industrial use). This new work proves that annual water level fluctuations of Lake Megali Prespa are predominantly related to precipitation during the first 7 months (Oct-Apr) of the hydrological year (Oct-Sep). Lake level is very sensitive to regional and Mediterranean wet-dry events during this period. There are robust indications for a link between lake level and the North Atlantic Oscillation, which is known to strongly influence Mediterranean winter precipitation. Hydro-climatic records show a complicated picture, but tentatively support the conclusion that the unprecedented lake level fall is principally related to climate change. The available fluvial discharge record and most existing snowfall records show statistically significant decreases in annual averages. Annual rainfall only shows a statistically significant decrease of the 25th percentile; 7-month rainfall (Oct-Apr) additionally shows a statistically significant but non-robust decrease of the mean. The modest amount of water extraction (annually: ~14*103m3, ~0.004% of total lake volume) exerts a progressive and significant impact on lake level over the longer term, accounting for ~25% of the observed fall. Lake level lowering ends when lake-surface area shrinkage has led to a decrease in lake-surface evaporation that is equivalent to the amount of water extracted. The adjustment of lake level to stable extraction rates requires two to three decades. This work aims to steer adaptation and mitigation strategies by informing on lake response under different climate change and extraction scenarios. Lake protection is a cost effective solution for supporting global biodiversity and for providing sustainable water resources.

van der Schriek, Tim; Giannakopoulos, Christos

2014-05-01

314

Measurements of wall pressure fluctuations on a cylinder in annular water flow with upstream disturbance. Part II. Flow spoilers  

International Nuclear Information System (INIS)

The second part of an experimental study of wall-pressure fluctuations on a circular rod concentrically located in circular channels of three different hydraulic diameters is reported. Part I presented results with no upstream disturbances; this report is concerned with the effects of upstream flow spoilers. Experimental results from the measurement of fluctuating wall pressures are presented in various statistical forms, including power spectral density representations and mean-square values, as the basis for studying the effects of upstream disturbances and hydraulic diameter. The upstream disturbance generated by a grid-type spoiler is shown to have a more dominant effect on wall-pressure fluctuations than the other types of spoilers tested

315

Investigation of natural radioactivity levels in water around Kadugli, Sudan  

International Nuclear Information System (INIS)

Surface water from Miri Lake and groundwater from around Kadugli (West-Central Sudan) obtained by means of hand-pumps was analysed for 238U, 226Ra, 222Rn, and 232Th activity concentrations. The surface water showed very low levels of radionuclide concentrations: -1 for 238U, 226Ra, 222Rn, and 232Th, respectively. Groundwater revealed a significant amount of natural radioactivity (16.1-1720, 7.7-14.3, 3000-139,000, -1) respectively. The overall annual effective dose was below the WHO reference dose level of 0.1 mSv yr-1 except in one groundwater sample with an associated dose of 0.7 mSv yr-1

316

Water level and pressure control device upon isolation of reactors  

International Nuclear Information System (INIS)

Purpose: To enable automatic control for the pressure and reactor water level upon isolation of nuclear reactor and significantly decrease the thermal stresses on the reactor materials due to the supply of low temperature water. Constitution: In a case where a main steam isolation valve of BWR type reactor is colsed to isolate the reactor, a flow control valve is controlled by a flow detector that detects the steam flow rate in a main steam relief pipe to thereby release a portion of the main steams to a pressure suppression chamber thereby maintain the reactor pressure to a predetermined value. While on the other hand, feedwater corresponding to the released amount of steams is injected into the reactor core by a pump driven from an auxiliary turbine depending on the detection signal from the flow rate detector and the level detector to thereby attain the intended purpose. (Nakamoto, H.)

317

Lead levels in fresh water mollusk shells. [Corbicula manillensis  

Energy Technology Data Exchange (ETDEWEB)

The possibility of using the shells of various fresh water mollusks as indicators of lead levels has been investigated. Shells of Corbicula manillensis (Asiatic clam) were found to be reliable and readily available indicators of lead levels. Samples collected at a relatively clean site were found to yield a mean lead concentration of 0.6 ppM with a range of .1 to 1.3 ppM. The sample means from other sites were increased by factors between 2 and 3.

Clarke, J.H.; Clarke, A.N.; Wilson, D.J.; Friauf, J.J.

1976-01-01

318

Analytical approach for predicting fresh water discharge in an estuary based on tidal water level observations  

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Full Text Available As the tidal wave propagates into an estuary, the tidally averaged water level tends to rise in landward direction due to the density difference between saline and fresh water and the asymmetry of the friction. The effect of friction on the residual slope is even more remarkable when accounting for fresh water discharge. In this study, we investigate the influence of river discharge on tidal wave propagation in the Yangtze estuary with specific attention to residual water level slope. This is done by using a one-dimensional analytical model for tidal hydrodynamics accounting for the residual water level. We demonstrate the importance of the residual slope on tidal dynamics and use it to improve the prediction of the tidal propagation in estuaries (i.e., tidal damping, velocity amplitude, wave celerity and phase lag, especially when the influence of river discharge is significant. Finally, we develop a new inverse analytical approach for estimating fresh water discharge on the basis of tidal water level observations along the estuary, which can be used as a tool to obtain information on the river discharge that is otherwise difficult to measure in the tidal region.

H. Cai

2014-06-01

319

Steam Pressurizer test and water level measurement performance test  

International Nuclear Information System (INIS)

The reports discuss steam high pressure chamber test and water level measurement system performance test. In the report, the necessity and the methodology of test is described. The test loop and small scale steam chamber are designed. The validation for the design is conducted. Muliti-channel(200 or more) high-speed data acquisition system is required and chosen. The achievement of 1st year and 2nd year plan are presented

320

Ditch water levels manages for environmental aims: effects on field soil water regimes  

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Full Text Available The effects of ditch water management regimes on water tables are examined for two test sites in England, Halvergate in the Broads and Southlake Moor in the Somerset Levels and Moors Environmentally Sensitive Areas. It is observed that in some fields the effects of water management are only poorly transferred from the ditch to the field centre, especially where the hydraulic conductivity of the subsoil is small. Where there are large variations in the ditch water levels, reflecting the influence of major ditches subject to pump drainage, field soil water regimes differ significantly. Nevertheless, the effects of even quite small changes in the ditch regime cam be noticeable. Simple modelling studies show that much greater effects can be achieved by increasing the frequency of ditches within wetlands.

A. Armstrong

1999-01-01

 
 
 
 
321

Dynamical fluctuation of the mesoscopic structure in ternary C12E5-water-n- octane amphiphilic system  

Science.gov (United States)

Dynamical fluctuations of the bicontinuous microemulsion and lamellar structures in ternary C12E5-water-n-octane amphiphilic system are studied by means of neutron spin echo (NSE) spectrometry. The decay rates of the time correlation of the concentration were analyzed in terms of three theories: (1) A. G. Zilman and R. Granek, Phys. Rev. Lett. 77, 4788 (1996), (2) M. Nonomura and T. Ohta, J. Chem. Phys. 110, 7516 (1999), and (3) R. Granek and M. E. Cates, Phys. Rev. A 46, 3319 (1992), in the first of which a Langevin equation for membrane plaquettes and in the latter two of which time-dependent Ginzburg-Landau equations for the order parameters are considered. The result shows that the intermediate correlation functions I(q,t) for the ranges of 0

Komura, Shigehiro; Takeda, Takayoshi; Kawabata, Youhei; Ghosh, Swapan K.; Seto, Hideki; Nagao, Michihiro

2001-04-01

322

Reservoir Computing approach to Great Lakes water level forecasting  

Science.gov (United States)

SummaryThe use of echo state network (ESN) for dynamical system modeling is known as Reservoir Computing and has been shown to be effective for a number of applications, including signal processing, learning grammatical structure, time series prediction and motor/system control. However, the performance of Reservoir Computing approach on hydrological time series remains largely unexplored. This study investigates the potential of ESN or Reservoir Computing for long-term prediction of lake water levels. Great Lakes water levels from 1918 to 2005 are used to develop and evaluate the ESN models. The forecast performance of the ESN-based models is compared with the results obtained from two benchmark models, the conventional recurrent neural network (RNN) and the Bayesian neural network (BNN). The test results indicate a strong ability of ESN models to provide improved lake level forecasts up to 10-month ahead - suggesting that the inherent structure and innovative learning approach of the ESN is suitable for hydrological time series modeling. Another particular advantage of ESN learning approach is that it simplifies the network training complexity and avoids the limitations inherent to the gradient descent optimization method. Overall, it is shown that the ESN can be a good alternative method for improved lake level forecasting, performing better than both the RNN and the BNN on the four selected Great Lakes time series, namely, the Lakes Erie, Huron-Michigan, Ontario, and Superior.

Coulibaly, Paulin

2010-02-01

323

Global Climate and Sea Level ENDURING VARIABILITY AND RAPID FLUCTUATIONS OVER THE PAST 150,000 YEARS  

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Full Text Available Although climate variations and sea level changes are often discussed interchangeably, climate change need not always result in sea level change. Perturbations in Earth’s orbit cause major climate changes, and the resulting variations in the amount and distribution of solar radiation at ground level follow cycles lasting for thousands of years. Research done in the last decade shows that climate can change on centennial or shorter time scales. These more rapid changes appear to be related to modifications in ocean circulation initiated during the last glacial period either by injections of fresh meltwater or huge ice discharges into the North Atlantic. When first detected, these rapid climate changes were characterized as episodes decoupled from any significant change in sea level. New data clearly show a direct connection between climate and sea level, and even more surprising, this link may extend to times of glacial-interglacial transitions and possibly also to interglacials. The full extent of this sea level/climate coupling is unknown and is the subject of current research.

Yusuke Yokoyama

2011-06-01

324

Interannual variability and predictability of water table levels at Santa Fe Province (Argentina) within the climatic change context  

Science.gov (United States)

SummaryIn recent times, significant areas of the Northeastern Argentine (NEA) have been affected by climatic fluctuations which have caused serious damages in ecosystems and people's livehoods, both by floods and droughts. This has mainly occurred in the Santa Fe Province, having a great impact on the underlying unconfined aquifer. This paper analyzes the relationships between meteorological variability and water table levels in the context of climate variability and climatic change in the lower Carcarañá river experimental basin (about 4700 km 2), located in the Santa Fe Province. The goal of the study is to obtain long-term (interannual) predictions of water table levels in the region. The methodology used responds to a hypothetical conception of the temporal series having a signal formed by random components with characteristics of white noise. Singular Spectral Analysis ( SSA), among other non-parametric techniques were used to identify fluctuations and trend changes in climatic time-series. These characteristics provide valuable information for the evaluation of climatic evolution and for the detection of variations in this evolution, suggesting a climatic change either by natural mechanisms or by anthropogenic impacts. A positive trend in precipitation is found throughout the studied region with water table levels showing a similar spatial-temporal behavior. The SSA gives significant periodicities between 3 and 8 years showing a possible link between El Niño-Southern Oscillation (ENSO) phenomenon and precipitation and water table levels. The periodicities linked with ENSO are always present and the structures of the series are similar for the different studied periods. The results obtained, even if they are experimental constitute a first approximation. In general, they are promising, since the generated basis will enable to face further and more complex stages.

Venencio, María del Valle; García, Norberto O.

2011-10-01

325

Mesoscopic fluctuations, two-parameter scaling and concommitant unusual level spacing distributions in finite 1D disordered systems  

International Nuclear Information System (INIS)

We study level spacing distributions of finite-sized one-dimensional disordered systems. As the system evolves from a quasi-ballistic to a strongly localized regime, the system crosses over from a strongly non-Wigner-Dyson type level spacing distribution to a universal Poisson distribution in the thermodynamic (L??) limit. In between it goes through regimes where the distribution seems to be a mixture of Wigner-Dyson type and Poisson type distributions, thus indicating existence of pre-localized states before the thermodynamic limit sets in. (author)

326

The Organochlorine Pesticides Residue Levels in Karun River Water  

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Full Text Available Background: The organochlorine pesticides (OCPs are among the most commonly used in water streams around the world. Most of these contaminants are highly hydrophobic and persist in sediments of rivers and lakes. Studies have suggested that OCPs may affect the normal function of the human and wildlife endocrine systems.Objectives: The aim of this study is to determine the concentrations of selected organochlorine pesticides residues [OP'DDT, PP'DDT, alderin, dieldrin, heptachlor, (?,ß,?,? HCH, (?, ß endosulfan and metoxychlor] in samples from Karun River water at Khuzestan province in Iran , by GC-µ-ECD.Materials and Methods: Water was extracted with n-hexane and then purified by passing through a glass column packed with Florisil and Na2SO4, which was then eluted with ether: hexane solution v/v.Results: In general, all of 12 investigated organochlorine pesticides (OCPs were detected. Regardless of the kind of OCPs, the highest OCP pollution level in Karun River were seen from August to November 2009 ranging 71.43 – 89.34 µg/L, and the lowest were seen from Dec 2010 to March 2011 at levels of 22.25 - 22.64 µg/L. The highest and lowest mean concentrations of 12 investigated pesticides were ß-Endosulfan and pp' DDT with 28.51and 0.01 µg/L respectively.Conclusions: Comparison of total organochlorine pesticides residues concentration with WHO guidelines revealed that the Karun River had total OCPs residues above the probable effect level (0.2-20 µg/L, P < 0.05, which could pose a risk to aquatic life.

Behrooz Jannat

2013-01-01

327

Fluctuations in relative sea-level during the past 3000 yr in the Onnetoh estuary, Hokkaido, northern Japan  

Science.gov (United States)

This paper presents the results of a litho-, bio- and chronostratigraphical study of the evidence for late Holocene sea-level change, palaeoseismicity and coastal evolution at the Onnetoh estuary, northwest Japan. Alternating peat and mud couplets record evidence for four falls in relative sea-level since ca. 2500 cal. yr BP. In the latest instance, intertidal mud with a salt-tolerant diatom and plant macrofossil flora is abruptly overlain by a freshwater peat containing abundant macrofossil remains of the conifer Picea glehnii. These stratigraphical changes record an abrupt change from tidal flat to upland, with no intermediate transition through saltmarsh. In the other three instances, the stratigraphy records a more gradual fall in relative sea-level, as shown by gradational stratigraphical contacts and transitional diatom and plant macrofossil assemblages. Once established, these freshwater peat communities are gradually submerged and become overlain by saltmarsh and then intertidal muds. Radiocarbon ages and tephra date the emergence events to 2700-1750 (gradual), 1350-950 (gradual), 650-300 (gradual) and ca. 400 cal. yr BP (abrupt). These ages are similar to a sequence of emergence events recorded at the Akkeshi estuary, 70 km to the west of the present study site. The three falls in relative sea-level may record coseismic, or swift post-seismic, uplift caused by plate boundary subduction earthquakes on the Kurile subduction zone. The oldest relative sea-level fall is correlated with the so-called Yayoi regression, dated to 1500-3000 cal yr BP in other parts of Japan.

Sawai, Yuki; Nasu, Hiroo; Yasuda, Yoshinori

2002-05-01

328

Analysis of water-level data in the Yucca Mountain area, Nevada, 1985--95  

International Nuclear Information System (INIS)

vel in seven wells. Periods of rising and declining water levels were observed in most wells. However, 11 years of record were not sufficient to determine if these periods were cyclic. Because a goal of monitoring water levels at Yucca Mountain is to determine if there are water-level trends that could affect the potential repository, observed water-level changes over the period of this report may not be representative of the overall long-term trends in water levels

329

An Indirect Adaptive Controller to Regulate UTSG Water Level in Pressurized Water Nuclear Reactor  

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Full Text Available Stabilizing water level of the Steam Generator (SG in nuclear power plant is a very important problem since its parameters vary with operating conditions and dynamics of the system is very different according to the power levels and changes as time goes on. Therefore, it is an intractable as well as challenging task to improve the water level control system of the SG. In this study, a new framework for building an adaptive Minimum Variance controller for stabilizing water-level of SG is proposed. We use the recursive least squares algorithm to identify the Input/Output models. Minimum Variance Control (MVC law is also used to develop the adaptation controller. Emphasis is put on the evaluation of the parameter identification in order to avoid instabilities because of disturbances or insufficient excitations. This is especially of importance when the adaptive control is carried out in closed loop systems and without additional test signals. The algorithm so proposed is simulated and applied to the water level control in the U-Tube Steam Generating unit (UTSG used for electricity generation. It is shown through application to a nonlinear model of steam generators that the proposed controller has good performance.

Djamel Boukhetala

2012-01-01

330

Records of ground-water levels and effects of pumping in the Ardmore well-field area, Carter County, Oklahoma  

Science.gov (United States)

The purpose of this report is to outline the results of work done by the U.S. Geological Survey in the Ardmore well-field area, near Newport, Carter County. The work, completed in two periods between April 1964 and June 1965, was done as part of the ground-water program carried out by the Geological Survey in cooperation with the Oklahoma Water Resources Board. The study in the report area included: (1) a physical inventory of wells in the vicinity of the Ardmore well field (fig. 1); (2) information on depths, perforated intervals, ground-water levels, and water use (table 1); (3) records of water-level fluctuations in deep and shallow wells (table 2) to determine if there is a hydraulic connection between the deep zones tapped by Ardmore's wells and the shallow and intermediate zones tapped by domestic and stock wells in the surrounding area; and (4) general information on the geologic and hydrologic features that may be of use in evaluating the ground-water potential of the Wichita Formation, the principal aquifer in the area. (available as photostat copy only)

Wood, P.R.

1965-01-01

331

Nanosecond fluctuation kinetics of luminescence hopping quenching originated from the 5d1 level in the Ce3+:YPO4·0.8H2O nanocrystals  

International Nuclear Information System (INIS)

We study the nanosecond energy transfer kinetics detected at dipole allowed 5d1–4f1 transition and originated from the lowest 2?1 level of the Ce3+ ions doped into the rhabdophane-type YPO4·0.8H2O nanocrystals synthesized by microwave hydrothermal treatment. We show that the luminescence quenching in the nanocrystals is determined by two processes depending on Ce3+ (energy donor) concentration at constant OH? (energy acceptors) concentration. At 0.2 mol% Ce3+ the luminescence quenching is mainly determined by direct (static) quenching caused by vibrations of OH? groups. At 2.0 mol% Ce3+ the quenching accelerates due to energy migration from the Ce3+ ions with poor acceptor surrounding to the Ce3+ ions with the nearby OH? acceptors. In the latter case we observe fluctuation kinetics of the luminescence impurity hopping quenching starting immediately after static ordered stage of the decay kinetics. We obtain that for dipole allowed the 5d–4f transition in the Ce3+ donor the CDD microparameter of the Ce3+–Ce3+ energy migration and CDA microparameter of Ce3+–OH? energy transfer are in strong correlation with the higher spontaneous emission rate for dipole allowed transition in Ce3+ comparing to dipole forbidden transition in Nd3+. -- Highlights: • We prepare the Ce3+:YPO4·0.8H2O nanocrystals of mean D=42 nm by microwave–hydrothermal synthesis. • We detect luminescence quenching of Ce3+ the 5d1(2?1) level caused by OH? vibrations. • We find that the static quenching caused by vibrations of OH? molecular groups dominates at 0.2% of Ce3+. • We find that Ce3+–Ce3+ energy migration accelerates the Ce3+–OH? quenching at 2% of Ce3+. • We detect nanosecond fluctuation kinetics of hopping quenching immediately after an ordered static stage

332

Response of deep-water fore-arc systems to sea-level changes, tectonic activity and volcaniclastic input in Central America  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The incipient island-arc system of southern Central America (Cretaceous - early Oligocene) is characterized by thick turbidite systems, which mainly filled inner fore-arc troughs. Outcrop data show four second-order depositional sequences in the deep-water sediments. The formation of these depositional sequences is strongly related to the morphotectonic evolution of the island-arc system. Each depositional sequence reflects the complex interaction between global sea-level fluctuations, sedime...

Winsemann, Jutta; Seyfried, Hartmut

1991-01-01

333

Establishing solar water disinfection as a water treatment method at household level  

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Full Text Available 1.1 billion People worldwide do not have access to safe drinking water and therefore are exposed to a high risk for diarrhoeal diseases. As a consequence, about 6,000 children die each day of dehydration due to diarrhoea. Adequate water treatment methods and safe storage of drinking water, combined with hygiene promotion, are required to prevent the population without access to safe drinking water from illness and death. Solar water disinfection (SODIS is a new water treatment to be applied at household level with a great potential to reduce diarrhoea incidence of users. The method is very simple and the only resources required for its application are transparent PET plastic bottles (or glass bottles and sufficient sunlight: microbiologically contaminated water is filled into the bottles and exposed to the full sunlight for 6 hours. During solar exposure, the diarrhoea causing pathogens are killed by the UV-A radiation of the sunlight. At present, SODIS is used by about 2 Million users in more than 20 countries of the South. Diarrhoea incidence of users significantly has been reduced by 30 to 70 %. A careful and long-term community education process that involves creating awareness on the importance of treating drinking water and initiates behaviour change is required to establish the sustainable practice of SODIS at community level. In Madagascar, more than 160 children younger than 5 years die each day from malaria, diarrhoea and acute respiratory illnesses. The application of household water treatment methods such as SODIS significantly could contribute to improve their health.

Regula Meierhofer

2006-12-01

334

CFNN based water level control for nuclear steam generator  

International Nuclear Information System (INIS)

Because normal PID controller can't change its parameters according to the change of control object parameters. In this paper, the compensatory fuzzy neural network (CFNN) was used with a simplified model of nuclear steam generator (NSG) to design a NSG water level controller. Compensatory neurons which were introduced in the CFNN will make the control system improve the quality of fault tolerant and more stable. Meanwhile compensative fuzzy computation is optimized dynamically in the study algorithm of neural network, therefore the network is much more adaptive and the training speed is much faster. The results of simulation show that under this control method the system has smaller maximum overshoot and faster convergence speed than that of under normal PID control method. The CFNN can not only adjust parameters properly on line, but also can optimized relevant fuzzy reasoning in dynamic way, so it suit to be used on ling learning and control. The control method used in this paper is meaningful to the research of NSG water level intelligent control. (authors)

335

Investigation of natural radioactivity levels in water around Kadugli, Sudan  

Energy Technology Data Exchange (ETDEWEB)

Surface water from Miri Lake and groundwater from around Kadugli (West-Central Sudan) obtained by means of hand-pumps was analysed for {sup 238}U, {sup 226}Ra, {sup 222}Rn, and {sup 232}Th activity concentrations. The surface water showed very low levels of radionuclide concentrations: <1.0-7.5, 8.5-16.5, <1.6, and <0.1-0.39 mBq L{sup -1} for {sup 238}U, {sup 226}Ra, {sup 222}Rn, and {sup 232}Th, respectively. Groundwater revealed a significant amount of natural radioactivity (16.1-1720, 7.7-14.3, 3000-139,000, <0.1-39 mBq L{sup -1}) respectively. The overall annual effective dose was below the WHO reference dose level of 0.1 mSv yr{sup -1} except in one groundwater sample with an associated dose of 0.7 mSv yr{sup -1}.

Osman, Alfatih A.A. [Sudan Atomic Energy Commission, P.O. Box 3001, Khartoum (Sudan)], E-mail: alfatih_123@yahoo.com; Salih, Isam; Shaddad, Ibrahim A.; El Din, Saif; Siddeeg, M.B.; Eltayeb, Hatem; Idriss, Hajo; Hamza, Walid; Yousif, E.H. [Sudan Atomic Energy Commission, P.O. Box 3001, Khartoum (Sudan)

2008-11-15

336

Plio-Pleistocene sea level and temperature fluctuations in the northwestern Pacific promoted speciation in the globally-distributed flathead mullet Mugil cephalus  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The study of speciation in the marine realm is challenging because of the apparent absence of physical barriers to dispersal, which are one of the main drivers of genetic diversity. Although phylogeographic studies using mitochondrial DNA (mtDNA information often reveal significant genetic heterogeneity within marine species, the evolutionary significance of such diversity is difficult to interpret with these markers. In the northwestern (NW Pacific, several studies have emphasised the potential importance of sea-level regression during the most recent glaciations as a driver of genetic diversity in marine species. These studies have failed, however, to determine whether the period of isolation was long enough for divergence to attain speciation. Among these marine species, the cosmopolitan estuarine-dependent fish Mugil cephalus represents an interesting case study. Several divergent allopatric mtDNA lineages have been described in this species worldwide, and three occur in sympatry in the NW Pacific. Results Ten nuclear microsatellites were surveyed to estimate the level of genetic isolation of these lineages and determine the role of sea-level fluctuation in the evolution of NW Pacific M. cephalus. Three cryptic species of M. cephalus were identified within this region (NWP1, 2 and 3 using an assignment test on the microsatellite data. Each species corresponds with one of the three mtDNA lineages in the COI phylogenetic tree. NWP3 is the most divergent species, with a distribution range that suggests tropical affinities, while NWP1, with a northward distribution from Taiwan to Russia, is a temperate species. NWP2 is distributed along the warm Kuroshio Current. The divergence of NWP1 from NWP2 dates back to the Pleistocene epoch and probably corresponds to the separation of the Japan and China Seas when sea levels dropped. Despite their subsequent range expansion since this period of glaciation, no gene flow was observed among these three lineages, indicating that speciation has been achieved. Conclusions This study successfully identified three cryptic species in M. cephalus inhabiting the NW Pacific, using a combination of microsatellites and mitochondrial genetic markers. The current genetic architecture of the M. cephalus species complex in the NW Pacific is the result of a complex interaction of contemporary processes and historical events. Sea level and temperature fluctuations during Plio-Pleistocene epochs probably played a major role in creating the marine species diversity of the NW Pacific that is found today.

Durand Jean-Dominique

2011-03-01

337

Comparative Analysis of Seepage Losses From Nighttime Water Level Changes and Water Balance Methods  

Science.gov (United States)

Several techniques including Darcy's theory of one and two dimensional groundwater flow, seepage meters, and water balance have been used in the past to estimate seepage from impoundments such as reservoirs, ponds, and constructed wetlands. These methods result in varying level of errors in seepage estimates depending on method and biogeophysical setting to which they are applied. In this study, we explore a simple yet effective method of estimating groundwater fluxes for two stormwater impoundments (SIs) and a partially drained wetland located in agricultural areas using diurnal changes in surface water levels inside these systems. Days with no inflow, outflow, and rainfall were selected to minimize the effect of the error associated water balance components on seepage estimation. Difference in water levels between 20:00 hrs and 5:00 hrs was calculated for the selected days. Only nighttime change was considered keeping in mind the fact that evapotranspiration is negligible during night and hence, the change in water levels can be attributed to seepage alone. Seepage from the analysis of night-time change in the water levels was compared to the estimates from the water balance method with seepage being the residual component of the balance. Results show that seepage constitutes a large part of total outflow from the impoundments (29% and 17% for SI1 during 2008-2009 and 2009-2010 respectively, 30% for SI2 during 2009-2010 and seepage was greater than the total surface water outflow from SI2 during 2010-2011). Accuracy of this method varied from 5% to 41% for first and 4% to 29% for the second SI. Considering that errors as high as 100% have been reported with the use of Darcy's approach, the errors from our method are lower. The lower errors combined with ease of application without using the hydraulic conductivity values makes our approach feasible for other similar systems. Improved seepage estimate from the proposed method will result in quantification of nutrient fluxes from SI through subsurface pathways, which is likely to result in a more realistic representation of treatment efficiency of these impoundments. For instance, phosphorus treatment efficiency of SI1 for 2008-2009 was estimated to be -17% and -60% with and without seepage consideration, respectively. Key words: Groundwater flux, impoundment, wetland, water balance, Phosphorus, treatment efficiency.

Shukla, A.; Shukla, S.; Wu, C.

2013-12-01

338

RELATIONSHIPS BETWEEN LEVELS OF HETEROTROPHIC BACTERIA AND WATER QUALITY PARAMETERS IN A DRINKING WATER DISTRIBUTION SYSTEM  

Science.gov (United States)

Conventional plating methods were used to quantify heterotrophic bacteria from a drinking water distribution system. Three media, plate count agar (PCA), R2A agar and sheep blood agar (TSA-SB) were used to determine heterotrophic plate count (HPC) levels. Grab samples were collec...

339

Estimating groundwater recharge on a temperate humid to semiarid volcanic island (Jeju, Korea) from water table fluctuations, Cl mass balance, apparent CFC-12 ages and 3H renewal  

Science.gov (United States)

Groundwater table fluctuations, Chloride mass balance, apparent groundwater Chlorofluorocarbon (CFC-12) ages and tritium (3H) renewal rates were used to assess recharge on Jeju Island (Korea), where groundwater is the main source of potable water. Given the limitations of various techniques and the respective data, the methods yield highly variable results of 10 to 1,991 mm/yr, with an average of 780 mm/yr that represents about 40% of the average annual rainfall over the island. The magnitude of recharge has not changed significantly over the past 50 years as indicated by an overall agreement of estimates for recent inter-seasonal recharge from the water table fluctuation method, and the long term average values from the geochemical techniques and the detailed water budget. Heterogeneity of recharge at the catchment scale is caused by spatially and temporally variable rainfall and evapotranspiration as well as the wide range in effective porosity and specific yield values of the aquifer lithologies. A Piston Flow model with negligible dispersion and diffusion fits 3H values for most groundwater samples. This implies that the mafic to intermediate volcanics exhibit fracture-hosted groundwater flow and that rapid recharge may be occurring in zones of interconnected porosity that represent a fraction of the total porosity. Calculated recharge rates that are generally highest (>1,000 mm/yr) in southern and eastern catchments and decrease with altitude indicate a strong control of topography and rainfall. However, since high recharge may occur across broad areas, attempts to protect groundwater from surface contamination require management of the landscape as a whole, not just the uplands. Increased recharge in western catchments (i.e., Hallim and Hangyeong) has not lowered groundwater nitrate contents due to the low effective porosities of the aquifers, where older nitrate-rich water is trapped in massive lava blocks within the unsaturated zone and is slowly mixed with groundwater as the water table rises.

Hagedorn, K. B.; El-Kadi, A. I.; Mair, A.; Whittier, R.

2010-12-01

340

Type 1 and Type 2 unconformity development in response to differential subsidence rates and eustatic sea level fluctuations, Pletmos basin, offshore South Africa  

Energy Technology Data Exchange (ETDEWEB)

The Pletmos basin, offshore South Africa, has had variable subsidence rates from mid-Valanginian to mid-Campanian times. During this period, third-, fourth-, and fifth-order sea level fluctuations occurred. The interplay of eustasy and differential subsidence rates caused 67 unconformities. Seventeen are major type 1 unconformities, 44 are minor type 1 unconformities, and 3 are type 2 unconformities. A further three exhibit type 2 characteristics and grade laterally into equivalent type 1 unconformities. Slow subsidence rates permitted fourth- and fifth-order eustatic variations to move sea level below the shelf edge and to erode minor type 1 unconformities. Periodically, when higher order cycles coincided with the trough of a third-order cycle, major type 1 unconformities occurred. Later periods of rapid subsidence precluded fourth- and fifth-order cycles being recorded in the stratigraphic section, and only third-order cycles were interpreted. When the rate of third-order eustatic falls were of the same order of magnitude as subsidence rates, relative sea level did not shift beyond the shelf edge, resulting in type 2 erosion. Deep-seated growth faulting established differential subsidence rates in the central Pletmos basin. In areas of slow subsidence the effects of eustatic variations were amplified relative to areas of rapid subsidence. This resulted in enhanced erosion associated with the former where major and minor type 1 unconformities coalesce and type 2 unconformities grade laterally into equivalent type 1 unconformities.

Jollands, A. (Soekor Ltd., Parow (South Africa))

1989-03-01

 
 
 
 
341

Level of Water Awareness at Some Jordanian Universities Studentâ??s  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Problem statement: Jordan has been facing shortage in water sector during the last three decades due to natural and society factors, weakness of water awareness is one of these Society factors, so this study focused on the level of water awareness in fields of; water significant in life, water problem in Jordan, water conservation at part of Jordanian society. Approach: The study aimed to Investigate how some Jordanian Universities students behave to identify the level of water ...

Mohamad Said Damanhouri; Bashar Abdallah Al-Saleem; Yousra Yousef AL-Ali

2012-01-01

342

NOAA tsunami water level archive - scientific perspectives and discoveries  

Science.gov (United States)

The National Oceanic and Atmospheric Administration (NOAA) National Geophysical Data Center (NGDC) and co-located World Data Service for Geophysics (WDS) provides long-term archive, data management, and access to national and global tsunami data. Currently, NGDC archives and processes high-resolution data recorded by the Deep-ocean Assessment and Reporting of Tsunami (DART) network, the coastal-tide-gauge network from the National Ocean Service (NOS) as well as tide-gauge data recorded by all gauges in the two National Weather Service (NWS) Tsunami Warning Centers' (TWCs) regional networks. The challenge in processing these data is that the observations from the deep-ocean, Pacific Islands, Alaska region, and United States West and East Coasts display commonalities, but, at the same time, differ significantly, especially when extreme events are considered. The focus of this work is on how time integration of raw observations (10-seconds to 1-minute) could mask extreme water levels. Analysis of the statistical and spectral characteristics obtained from records with different time step of integration will be presented. Results show the need to precisely calibrate the despiking procedure against raw data due to the significant differences in the variability of deep-ocean and coastal tide-gauge observations. It is shown that special attention should be drawn to the very strong water level declines associated with the passage of the North Atlantic cyclones. Strong changes for the deep ocean and for the West Coast have implications for data quality but these same features are typical for the East Coast regime.

Mungov, G.; Eble, M. C.; McLean, S. J.

2013-12-01

343

Emergency action levels for light water reactors. Draft report  

International Nuclear Information System (INIS)

United States nuclear power plants are currently preparing revised radiological emergency response plans. As part of these plans, each licensee is establishing plant-specific instrumentation readings, called emergency action levels (EALs), that indicate the presence of a problem and the need to declare one of four classes of emergency as designated by the U.S. Nuclear Regulatory Commission. In this report, the EALs prepared for a pressurized water reactor and a boiling water reactor are assessed to determine whether they meet the requirements of NUREG-0654, Rev. 1 Appendix 1. In addition, five recent nuclear incidents are studied to determine how their outcomes might have been affected by the new emergency response plans. Most of the EALs reviewed were judged adequate. In some cases, alternate EALs or sets of generic EALs are proposed to meet the intent of NUREG-0654 Rev 1 Appendix 1, and the wording of some of the initiating conditions for the four emergency classes is clarified. For three of the five incidents reviewed, the new emergency response plans probably would not have affected the outcome; in one case, the plans would probably have prevented core damage; and any effect on the outcome of the last incident is uncertain

344

Natural radioactivity levels in different mineral waters from Bulgaria  

International Nuclear Information System (INIS)

The total radioactivity content of 76 mineral waters from different districts in Bulgaria was determined. Natural radioactivity levels resulting from uranium, radium-226, gross alpha and gross beta activity were measured. The results show that the specific activity range from < 0.02 Bq/l to 1.34 (12) Bq/l and from 0.068 (23) Bq/l to 2.60 (50) Bq/l for gross alpha and gross beta activity respectively. For natural Uranium the results vary between 0.020 (5) ?g/l and 180(50) ?g/l. Radium-226 content is between < 0.03 Bq/l to 0.296 (75) Bq/l. Due to differences in the geological structure of the aquifer, a large difference in values of the radioactive content was mSv/year. Excluding one value, TID do not exceed the permissible limit of 0.10 mSv/year. The correlations between investigated isotopes and Total Dissolved observed. The estimated Total Indicative Dose (TID) ranged from 0.0113 (57) mSv/year to 0.1713 (481) Solvents (TDS) in water were carried out. The results do not show a strong correlation between TDS values and dissolved radionuclides. (author)

345

Lake-level fluctuations since the Last Glaciation in Selin Co (lake), Central Tibet, investigated using optically stimulated luminescence dating of beach ridges  

International Nuclear Information System (INIS)

This paper presents a preliminary study on lake-level fluctuations since the Last Glaciation in Selin Co (lake), Central Tibet, by dating four groups of beach ridges using optically stimulated luminescence (OSL). The highest/oldest beach ridge group (>100 m higher than the current lake level) is dated back to 67.9 ± 2.4 ka BP, corresponding to the early stage of the Last Glaciation (marine isotope stage (MIS) 4). This date further supports that no plateau-scale ice sheet covered the Tibeta