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1

Water-level fluctuations affect macrophyte richness in floodplain lakes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The characteristic ecology of floodplain lakes is in part due to their relatively strong water-level fluctuations. We analyzed the factors determining water-level fluctuations in 100 floodplain lakes (during non-flooded conditions) in the active floodplains of the Lower Rhine in the Netherlands. Furthermore, we explored the relationship between water-level fluctuations and macrophyte species richness, and analyzed the suitability of artificially created lakes for macrophyte vegetation. During...

Geest, G. J.; Wolters, H.; Roozen, F. C. J. M.; Coops, H.; Roijackers, R. M. M.; Buijse, A. D.; Scheffer, M.

2005-01-01

2

Seasonal water level fluctuations: Implications for reservoir limnology and management  

Digital Repository Infrastructure Vision for European Research (DRIVER)

With the purpose of finding out whether seasonal water level fluctuations could affect water quality in a reservoir subjected to those changes, trends in environmental variables and in phytoplankton and zooplankton assemblages were analysed. The reservoir’s hydrological cycle was characterized by three regimes. The maximum level phase lasted from January to the beginning of June, the emptying phase existed between mid-June to the beginning of September and the minimum level phas...

Geraldes, Ana Maria; Boavida, Maria Jose?

2005-01-01

3

Reverse water-level fluctuations associated with fracture connectivity.  

Science.gov (United States)

Reverse water-level fluctuations (RWFs), a phenomenon in which water levels rise briefly in response to pumping, were detected in monitoring wells in a fractured siliciclastic aquifer system near a deep public supply well. The magnitude and timing of RWFs provide important information that can help interpret aquifer hydraulics near pumping wells. A RWF in a well is normally attributed to poroelastic coupling between the solid and fluid components in an aquifer system. In addition to revealing classical pumping-induced poroelastic RWFs, data from pressure transducers located at varying depths and distances from the public supply well suggest that the RWFs propagate rapidly through fractures to influence wells hundreds of meters from the pumping well. The rate and cycling frequency of pumping is an important factor in the magnitude of RWFs. The pattern of RWF propagation can be used to better define fracture connectivity in an aquifer system. Rapid, cyclic head changes due to RWFs may also serve as a mechanism for contaminant transport. PMID:23473020

Gellasch, Christopher A; Wang, Herbert F; Bradbury, Kenneth R; Bahr, Jean M; Lande, Lauren L

2014-01-01

4

Temporal scales of water-level fluctuations in lakes and their ecological implications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Water-level fluctuations (WLF) of lakes have temporal scales ranging from seconds to hundreds of years. Fluctuations in the lake level generated by an unbalanced water budget resulting from meteorological and hydrological processes, such as precipitation, evaporation and inflow and outflow conditions usually have long temporal scales (days to years) and are here classified as long-term WLF. In contrast, WLF generated by hydrodynamic processes, e.g. basin-scale oscillations and travel...

Hofmann, Hilmar; Lorke, Andreas; Peeters, Frank

2008-01-01

5

Vegetational and landscape level responses to water level fluctuations in Finnish, mid-boreal aapa mire - aro wetland environments  

Energy Technology Data Exchange (ETDEWEB)

Abstract Gradient, which is largely considered to be related to water level in mires, is referred to as a microtopographic mud bottom to carpet to lawn to hummock level gradient or the hummock level to intermediate level (lawn) to flark level gradient. The relationship of this vegetation gradient to various physical water level characteristics was studied. The general classification used in the present summary paper divides the aro vegetation of the inland of Northern Ostrobothnia into two main groups: (a) treeless fen aro vegetation (Juncus supinus, Carex lasiocarpa, Rhynchospora fusca, Molinia caerulea) and (b) heath aro vegetation (Polytrichum commune). The first group (a) was divided into fen aro wetlands with an approximately10 cm peaty layer at most and into aro fens with a peat layer thicker than 10 cm. The treatment of the water level gradient was divided into three main groups. (1) The mean water level correlated with mire surface levels (microtopographic gradient) within mires with slight water level fluctuations and partly within mires with considerable water level fluctuations. (2) Three habitat groups could be distinguished on the basis of the range of water level fluctuation i.e. mires with slight water level fluctuations, mires with considerable water level fluctuations and the aro vegetation with extreme water level fluctuations. (3) The timing of water level fluctuations indicated that there are different types of patterns within aro wetlands, the seasonal pattern being mainly a response to yearly snow melt and the several-year-fluctuation pattern being related to the regional groundwater table fluctuation in mineral soils (heath forests). A link was suggested between the stability of the water regime and peat production in local aapa mire - aro wetland environments. From the point of view of peatland plants the direction of variation from a stable to an unstable water regime in aapa mire - aro wetland environments represents a transition towards more and more harsh ecological conditions, partly forming a gradient through natural disturbance. A qualitative functional model was provided for the mire - aro wetland systems of Northern Ostrobothnia. The model supposes differences in the characteristics of peat between two functional complexes within a mire system. Finally, the model for local mire - aro wetland systems was converted to a general from: diplotelmic (acrotelm) mires were divided into two subtypes (diplotelmic water stabilization mires, diplotelmic water fluctuation mires) and the relationship of those subtypes to percolation mires and seasonal wetlands was considered. (orig.)

Laitinen, J.

2008-07-01

6

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

7

Spectral analysis of observed aquifer water level fluctuations  

Science.gov (United States)

A mathematical model is presented that describes small, periodic, water level perturbations in a fully screened observation well penetrating a homogeneous, isotropic, confined aquifer system. The analytical solution is formulated in terms of frequency and phase response functions that are controlled by aquifer transmissivity (T) and storage coefficient (S). Well casing storage effects are considered; however, well screen entrance losses associated with turbulence are neglected because piezometric head differences inside and outside the well are small. As the ratio of well casing radius to well screen radius (rc/rw) changes, these theoretical response functions are systematically altered. When rc/rwnoise without the improved Levenberg-Marquardt (LM) optimization scheme developed here. Initially, a sigmoidal curve fitting algorithm and observed frequency and phase response functions are used to identify a starting estimate for T. This value is then used in the LM procedure and facilitates convergence to optimal system parameters while minimizing uncertainty. Without this approach, however, the LM scheme will not yield unique estimates. This methodology yields smaller aquifer parameters than traditional specific capacity tests, suggesting either a well bore skin effect or a scaling phenomenon similar to that reported in the literature for slug and aquifer test comparisons. Hence, this technique is probably best suited for monitoring wells where conventional aquifer test methods are impractical. This approach is documented in several MATLAB m-files and illustrated by several examples using observed data.

McLin, Stephen

2012-09-01

8

Preliminary assessment of the impact of fluctuating water levels on northern pike in Reindeer Lake  

International Nuclear Information System (INIS)

Reindeer Lake in north eastern Saskatchewan regulates water levels for the Island Falls hydroelectric power plant. Since inception of the Whitesand Dam on the lake, there have been concerns that fluctuating water levels could be adversely impacting the habitat and population of northern pike in the lake. The extent of water level fluctuations during the pike spawning period of Reindeer Lake and its effect on spawning success was investigated. Since construction of the Whitesand Dam in 1942 Reindeer Lake water levels have averaged ca 1.71 m higher than had the dam not existed, creating ca 430 km"2 of new surface area. Much of this area is shallow water and prone to growth of aquatic vegetation, which is suitable spawning and nursery habitat for northern pike. Annual and periodic water level fluctuations of Reindeer Lake have been higher than under natural conditions. During northern pike spawning and nursing periods, water levels in the lake have generally increased, in 60 out of 64 y. It is concluded that operation of the dam has not caused any direct negative impacts on the northern pike habitat in the lake. 2 refs., 4 figs., 4 tabs

1993-01-01

9

Fuzzy logic model of lake water level fluctuations in Lake Van, Turkey  

Science.gov (United States)

Lake Van is one of the largest terminal lakes in the world. In recent years, significant lake level fluctuations have occurred and can be related to global climatic change. This fluctuation sometimes exhibits abrupt shifts. Floods originating from the lake can cause considerable damage and loss in agriculture and urban areas. Therefore, water level forecasting plays a significant role in planning and design. This study is aimed at predicting future lake levels from past rainfall amounts and water level records. A dynamical change of the lake level is evaluated by the fuzzy approach. The fuzzy inference system has the ability to use fuzzy membership functions that include the uncertainties of the concerned event. This method is applied for Lake Van, in east Turkey. Furthermore, model capabilities are compared with ARMAX model. It is shown that lower absolute errors are obtained with the Takagi-Sugeno fuzzy approach than with the ARMAX model.

Altunkaynak, A.; ?en, Z.

2007-11-01

10

Earthquake-induced water-level fluctuations at Yucca Mountain, Nevada, June 1992  

International Nuclear Information System (INIS)

This report presents earthquake-induced water-level and fluid-pressure data for wells in the Yucca Mountain area, Nevada, during June 1992. Three earthquakes occurred which caused significant water-level and fluid-pressure responses in wells. Wells USW H-5 and USW H-6 are continuously monitored to detect short-term responses caused by earthquakes. Two wells, monitored hourly, had significant, longer-term responses in water level following the earthquakes. On June 28, 1992, a 7.5-magnitude earthquake occurred near Landers, California causing an estimated maximum water-level change of 90 centimeters in well USW H-5. Three hours later a 6.6-magnitude earthquake occurred near Big Bear Lake, California; the maximum water-level fluctuation was 20 centimeters in well USW H-5. A 5.6-magnitude earthquake occurred at Little Skull Mountain, Nevada, on June 29, approximately 23 kilometers from Yucca Mountain. The maximum estimated short-term water-level fluctuation from the Little Skull Mountain earthquake was 40 centimeters in well USW H-5. The water level in well UE-25p number-sign 1, monitored hourly, decreased approximately 50 centimeters over 3 days following the Little Skull Mountain earthquake. The water level in UE-25p number-sign 1 returned to pre-earthquake levels in approximately 6 months. The water level in the lower interval of well USW H-3 increased 28 centimeters following the Little Skull Mountain earthquake. The Landers and Little Skull Mountain earthquakes caused responses in 17 intervals of 14 hourly monitored wells, however, most responses were small and of short duration. For several days following the major earthquakes, many smaller magnitude aftershocks occurred causing measurable responses in the continuously monitored wells

1993-01-01

11

Earthquake-induced water-level fluctuations at Yucca Mountain, Nevada, June 1992  

Energy Technology Data Exchange (ETDEWEB)

This report presents earthquake-induced water-level and fluid-pressure data for wells in the Yucca Mountain area, Nevada, during June 1992. Three earthquakes occurred which caused significant water-level and fluid-pressure responses in wells. Wells USW H-5 and USW H-6 are continuously monitored to detect short-term responses caused by earthquakes. Two wells, monitored hourly, had significant, longer-term responses in water level following the earthquakes. On June 28, 1992, a 7.5-magnitude earthquake occurred near Landers, California causing an estimated maximum water-level change of 90 centimeters in well USW H-5. Three hours later a 6.6-magnitude earthquake occurred near Big Bear Lake, California; the maximum water-level fluctuation was 20 centimeters in well USW H-5. A 5.6-magnitude earthquake occurred at Little Skull Mountain, Nevada, on June 29, approximately 23 kilometers from Yucca Mountain. The maximum estimated short-term water-level fluctuation from the Little Skull Mountain earthquake was 40 centimeters in well USW H-5. The water level in well UE-25p {number_sign}1, monitored hourly, decreased approximately 50 centimeters over 3 days following the Little Skull Mountain earthquake. The water level in UE-25p {number_sign}1 returned to pre-earthquake levels in approximately 6 months. The water level in the lower interval of well USW H-3 increased 28 centimeters following the Little Skull Mountain earthquake. The Landers and Little Skull Mountain earthquakes caused responses in 17 intervals of 14 hourly monitored wells, however, most responses were small and of short duration. For several days following the major earthquakes, many smaller magnitude aftershocks occurred causing measurable responses in the continuously monitored wells.

O`Brien, G.M.

1993-07-01

12

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

13

Effects of water level fluctuations on the early life stages of fish in the littoral zone of lakes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Studies on the reactions of organisms to their abiotic environment are indispensable to understand their aut- and synecology and to predict effects of changes in ecosystems on their inhabitants. This thesis aims to contribute to a mechanistic understanding of how water level fluctuations affect early life stages of littoral fish. Water level fluctuations can have different periods, ranging from less than a second to more than a year. Short-term fluctuations with a period of few seconds, i.e. ...

Stoll, Stefan

2009-01-01

14

Effects of Barometric Fluctuations on Well Water-Level Measurements and Aquifer Test Data  

Energy Technology Data Exchange (ETDEWEB)

The Pacific Northwest National Laboratory, as part of the Hanford Groundwater Monitoring Project, examines the potential for offsite migration of contamination within underlying aquifer systems. Well water-level elevation measurements from selected wells within these aquifer systems commonly form the basis for delineating groundwater-flow patterns (i.e., flow direction and hydraulic gradient). In addition, the analysis of water-level responses obtained in wells during hydrologic tests provides estimates of hydraulic properties that are important for evaluating groundwater-flow velocity and transport characteristics. Barometric pressure fluctuations, however, can have a discernible impact on well water-level measurements. These barometric effects may lead to erroneous indications of hydraulic head within the aquifer. Total hydraulic head (i.e., sum of the water-table elevation and the atmospheric pressure at the water-table surface) within the aquifer, not well water-level elevation, is the hydrologic parameter for determining groundwater-flow direction and hydraulic gradient conditions. Temporal variations in barometric pressure may also adversely affect well water-level responses obtained during hydrologic tests. If significant, adjustments or removal of these barometric effects from the test-response record may be required for quantitative hydraulic property determination. This report examines the effects of barometric fluctuations on well water-level measurements and evaluates adjustment and removal methods for determining areal aquifer head conditions and aquifer test analysis. Two examples of Hanford Site unconfined aquifer tests are examined that demonstrate barometric response analysis and illustrate the predictive/removal capabilities of various methods for well water-level and aquifer total head values. Good predictive/removal characteristics were demonstrated with best corrective results provided by multiple-regression deconvolution methods.

FA Spane, Jr.

1999-12-16

15

??BP??????????????? Prediction of the Water Level Fluctuation of Dongting Lake Based on BP Neural Network  

Directory of Open Access Journals (Sweden)

Full Text Available ????????????????????????????????????????????????????????????????????Levenberg-Marquardt?????????????????BP????????????2010?10?????????????????????????????????????????????3.89%??????0.91%???????BP????????????????????????????????It is of vital significance to study the water level fluctuation of DongtingLakeespecially after the operation of the Three Gorges Reservoir (TGR, which may provide useful data and necessary information for the repairing works of the wetland. In this study, the historical time series of outflow discharge of the TGR and water level of Chenglingji were taken as training samples. Based on Levenberg-Marquardt (LM algorithm, a BP neural network with four layers was established, which well-expressed the unknown but literally existed relationship between outflow discharge of the TGR and the water level of Chenglingji. Then it was applied to the water level prediction in October 2010 of Chenglingji. It is indicated that the trend of actual value and forecast value are in substantial agreement and the maximum and average errors are 3.89% and 0.91%, respectively. It is shown that BP neural network has fairly good simulation accuracy and can be satisfactorily utilized to predict the water level fluctuation of theDongtingLake.

???

2012-08-01

16

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 t...

Mare?chal, Jean-christophe; Sarma, Mp; Ahmed, Shakeel; Lachassagne, Patrick

2002-01-01

17

Water-level fluctuation and its implication on the hydrologic cycle in the Gwangneung Supersite, Korea  

Science.gov (United States)

For effective assessment and management of water resources, it is important to understand and quantify each component of the hydrologic cycle. A careful and detailed analysis of spatio-temporal variations in water levels in aquifers could reveal useful information on the groundwater system. This study is objected to understand the reasons and mechanisms of fluctuations. As a part of an interdisciplinary research project, HydroKorea, to ascertain the water cycle quantitatively, water levels have been monitored from shallow monitoring wells(G1, G4) with less than 1-m in depths and a deep well enclosing three monitoring wells (ft1, ft2 and ft3 screened at depths of 102m, 45m and 6m below ground surface, respectively). Monitoring wells are located in the Gwangneung Supersite, Korea. Water levels used in this study were monitored by 10-min interval from February to May in 2007. Water levels compensated for air pressure were analyzed using a Fast Fourier Transform(FFT) technique for power spectral analysis. Results show periodic variations in 11.38, 12.19, 21.33, 24.38, and 28.44 hours, indicating strong influence of diurnal and semidiurnal tidal components. The diurnal components of the water levels from G1 and G4 in summer had greater power than those in winter, implying that the water table is affected by not only earth tides but evapotranspiration. However, those of the water levels from ft1, ft2 and ft3 do not show seasonal characteristics indicating that evapotranspiration has no influence in water levels of deep monitoring wells.

Kim, Y.; Woo, N.; Hong, T.; Kim, J.

2007-12-01

18

Ecological effects of water-level fluctuations in lakes : an urgent issue  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Water-level fluctuations (WLF) affect the ecological processes and patterns of lakes in several ways. Aquatic habitats and feeding or breeding grounds are gained or lost, as light, climate and wave impacts change to mention only a few phenomena. While the phenomenon of WLF has been studied in many rivers (better known as flood pulse, Junk & Wantzen, 2004) and environmental flows (Bunn et al., 2006), so far it has not received due attention in lakes (Coops et al., 2003). A potential reason for...

2008-01-01

19

Response of littoral macrophytes to water level fluctuations in a storage reservoir Réponse des macrophytes littoraux aux fluctuations du niveau d’eau dans un réservoir  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 be...

Krolová M.; ?ížková H.; Hejzlar J.; Poláková S.

2013-01-01

20

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

CERN Multimedia

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

 
 
 
 
21

Combining the soilwater balance and water-level fluctuation methods to estimate natural groundwater recharge: Practical aspects  

Science.gov (United States)

A relatively simple and practical approach for calculating groundwater recharge in semiarid plain environments with a relatively shallow water table, such as the Kansas Prairies, is outlined. Major uncertainties in the Darcian, water balance, and groundwater fluctuation analysis approaches are outlined, and a combination methodology for reducing some of the uncertainties is proposed. By combining a storm-based soilwater balance (lasting several days) with the resulting water table rise, effective storativity values of the region near the water table are obtained. This combination method is termed the 'hybrid water-fluctuation method'. Using a simple average of several such estimates results in a site-calibrated effective storativity value that can be used to translate each major water-table rise tied to a specific storm period into a corresponding amount of groundwater recharge. Examples of soilwater balance and water-level fluctuation analyses based on field-measured data from Kansas show that the proposed methodology gives better and more reliable results than either of the two well-established approaches used singly. ?? 1991.

Sophocleous, M. A.

1991-01-01

22

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

Directory of Open Access Journals (Sweden)

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

23

Late Holocene water level fluctuations of Lake Afourgagh (Middle-Atlas Mountains, Morocco) inferred from charophyte remains  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Water level fluctuations of Lake Afourgagh (Middle-Atlas Mountains, Morocco) over the last 2500 years (Late Holocene) have been reconstructed using charophyte remains in the lake sediment archives. The study involved 22 pits (1-3 m deep) dug along a transect across the lake shore terrace. Biogenic activity appears to be a dominant contributor to the accumulation of the lake sediments, as the thickest deposits are tufas composed of charophyte-encrusted stems with numerous gyrogonites (termed "...

De?triche?, Se?bastien; Bre?heret, Jean-gabriel; Soulie?-ma?rsche, I.; Karrat, L.; Macaire, Jean-jacques

2009-01-01

24

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)

2000-07-25

25

Relationship between mercury accumulation in young-of-the-year yellow perch and water-level fluctuations  

Science.gov (United States)

A three-year (2001 -2003) monitoring effort of 14 northeastern Minnesota lakes was conducted to document relationships between water-level fluctuations and mercury bioaccumulation in young-of-the-year (YOY) yellow perch (Perca flavescens) collected in the fall of each year at fixed locations. Six of those lakes are located within or adjacent to Voyageurs National Park and are influenced by dams on the outlets of Rainy and Namakan lakes. One site on Sand Point Lake coincides with a location that has nine years of previous monitoring suitable for addressing the same issue over a longer time frame. Mean mercury concentrations in YOY yellow perch at each sampling location varied significantly from year to year. For the 12-year monitoring site on Sand Point Lake, values ranged from 38 ng gww-1 in 1998 to 200 ng gww -1 in 2001. For the 14-lake study, annual mean concentrations ranged by nearly a factor of 2, on average, for each lake over the three years of record. One likely factor responsible for these wide variations is that annual water-level fluctuations are strongly correlated with mercury levels in YOY perch for both data sets. ?? 2005 American Chemical Society.

Sorensen, J. A.; Kallemeyn, L. W.; Sydor, M.

2005-01-01

26

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 wit...

Anderson Medeiros dos Santos; Francisco de Assis Esteves

2004-01-01

27

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 wat...

Ramana, D. V.; Chelani, A.; Chadha, R. K.; Singh, R. N.

2009-01-01

28

Observations of Water-Level Fluctuations Induced by Local and Distant Earthquakes at Two Wells in Hualien, Eastern Taiwan  

Science.gov (United States)

Sustained water level fluctuations may occur in response to local changes of volumetric strain associated with passage of seismic waves or ground deformation. Two wells, namely HLC-05 and HLC-03, with high sampling rates (1 and 6 second) have been deployed for the purpose of monitoring the dynamic response of water level and static steps induced by earthquakes in Hualien area, eastern Taiwan since 2002. Through our observations, we have found the following results. (1) The water level changes may occur with earthquakes of magnitude M>=0.43+2.39log10(D), where D is the distance from the well; (2) the peak water level fluctuations (PWL) are apparently proportional to the peak ground velocity (PGV) and peak ground displacement (PGD) on logarithmic scales, but no clear trend with the peak ground acceleration (PGA). We performed regression to obtain the relationships between PWL and PGV, and PWL and PGD, respectively, as follows: For the HLC-05 well: ln(PWL)=0.83ln(PGVH)-3.22, ln(PWL)=0.97ln(PGVV)-2.27, ln(PWL)=0.80ln(PGDH)-1.70, ln(PWL)=0.91ln(PGDV)-0.83 For the HLC-03 well: ln(PWL)=0.73ln(PGVH)-3.29, ln(PWL)=0.73ln(PGVV)-2.65, ln(PWL)=0.53ln(PGDH)-2.44, ln(PWL)=0.57ln(PGDV)-1.93 where the subscripts H and V represent the horizontal and the vertical component, of ground motion respectively.

Liu, C.; Huang, M.; Tsai, Y.; Lee, C.

2005-12-01

29

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

30

Response of littoral macrophytes to water level fluctuations in a storage reservoir Réponse des macrophytes littoraux aux fluctuations du niveau d’eau dans un réservoir  

Directory of Open Access Journals (Sweden)

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. Les lacs et réservoirs qui sont utilisés pour l’approvisionnement en eau et/ou les régulations d’écoulement ont généralement des communautés littorales de macrophytes peu développées, ce qui altère le potentiel écologique selon la directive européenne cadre sur l’eau. Le but de notre étude était de révéler les facteurs de contrôle de la croissance des macrophytes littoraux dans un réservoir avec un niveau d’eau fluctuant (Lipno, République tchèque. Les macrophytes ne sont présents dans ce réservoir que dans la zone eulittorale i.e., la région du littoral entre les plus hauts et les plus bas niveaux d’eau saisonniers. Trois sous-zones eulittorales peuvent être distinguées : la eulittorale supérieure avec une communauté stable d’espèces pérennes avec un fort recouvrement, la eulittorale médiane avec une richesse relativement élevée d’espèces émergées et amphibies présentant des valeurs de couverture faible, et la eulittorale inférieure de végétation permanente. Couverture et composition des espèces, dans chaque sous-zone, sont principalement influencées par la durée et le moment des inondations, suivis par la limitation en nutriments et des conditions fortement réductrices dans les sédiments organiques inondés. Nos résultats soulignent l’importance écologique de la zone eulittorale dans des réservoirs à niveaux d’eau fluctuants, où la croissance des macrophytes peut être prise en compte par une gestion ciblée du niveau d’eau, ce qui aide les gestionnaires du réservoir à améliorer le potentiel écologique de ce type de plans d’eau.

Hejzlar J.

2013-05-01

31

Water-level fluctuations and metapopulation dynamics as drivers of genetic diversity in populations of three Tanganyikan cichlid fish species.  

Science.gov (United States)

Understanding how genetic variation is generated and maintained in natural populations, and how this process unfolds in a changing environment, remains a central issue in biological research. In this work, we analysed patterns of genetic diversity from several populations of three cichlid species from Lake Tanganyika in parallel, using the mitochondrial DNA control region. We sampled populations inhabiting the littoral rocky habitats in both very deep and very shallow areas of the lake. We hypothesized that the former would constitute relatively older, more stable and genetically more diverse populations, because they should have been less severely affected by the well-documented episodes of dramatic water-level fluctuations. In agreement with our predictions, populations of all three species sampled in very shallow shorelines showed traces of stronger population growth than populations of the same species inhabiting deep shorelines. However, contrary to our working hypothesis, we found a significant trend towards increased genetic diversity in the younger, demographically less stable populations inhabiting shallow areas, in comparison with the older and more stable populations inhabiting the deep shorelines. We interpret this finding as the result of the establishment of metapopulation dynamics in the former shorelines, by the frequent perturbation and reshuffling of individuals between populations due to the lake-level fluctuations. The repeated succession of periods of allopatric separation and secondary contact is likely to have further increased the rapid pace of speciation in lacustrine cichlids. PMID:23837841

Nevado, B; Mautner, S; Sturmbauer, C; Verheyen, E

2013-08-01

32

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

Science.gov (United States)

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

33

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Costa Rica | Language: English Abstract in spanish 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. Abstract in english 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 l [...] akes 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.

Juan José, Neiff; Sylvina Lorena, Casco; Alicia, Poi de Neiff.

34

Water-level fluctuations in the Black Sea since the Last Glacial Maximum  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two IFREMER oceanographic surveys carried out in the northwestern Black Sea in 1998 and 2002 complement previous seabed mapping and subsurface sampling by various international expeditions. They show that the lake level rose on the continental shelf to at least the -40 to -30 m isobath based on the landward limit of a Dreissena layer representative of very low salinity conditions (<50/00). The Black Sea then shows clear evidence for an onset of marine conditions at 7150 BP. From these observa...

Lericolais, Gilles; Popescu, I.; Guichard, F.; Popescu, S. M.

2007-01-01

35

Impacts of Water Level Fluctuations on Kokanee Reproduction in Flathead Lake, 1984 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

This study was initiated in the fall of 1981 to delineate the extent of successful shoreline spawning of kokanee salmon in Flathead Lake and determine the impacts of the historic and present operations of Kerr and Hungry Horse dams. An investigation of the quantity and quality of groundwater and other factors affecting kokanee reproductive success in Flathead Lake began in the spring of 1982. A total of 719 redds were counted in 17 shoreline areas of Flathead Lake in1983 compared to 592 in 1981 and 1,029 in 1982. Shoreline spawning contributed three percent to the total kokanee spawning in the Flathead drainage in 1983. Fifty-nine percent of the redds were located above 2883 ft, the operational minimum pool. The majority of those redds were constructed between 2885 and 2889 ft. In areas above minimum pool, intergravel dissolved oxygen concentrations were adequate for embryo survival and exhibited a decrease with depth. Limited data indicated apparent velocity may be the key in determining redd distribution. Seventy-five percent of the redds located below minimum pool were constructed in a zone between 2869 and 2883 ft. In individual areas, apparent velocity measurements and intergravel dissolved oxygen concentrations were related to redd density. The variation in intergravel dissolved oxygen concentrations in the Yellow Bay spawning area was partially explained by lake stage fluctuation. As lake stage declined, groundwater apparent velocity increased which increased intergravel dissolved oxygen concentrations. Mean survival to the eyed stage in the three areas below minimum pool was 43 percent. Prior to exposure by lake drawdown, mean survival to the eyed stage in spawning areas above minimum pool was 87 percent. This indicated habitat most conducive to successful embryo survival was in gravels above 2883 ft. prior to significant exposure. Survival in redds exposed to either extended periods of drawdown or to temperatures less than -10% was significantly reduced to a mean of 20-30 percent. Survival in individual spawning areas exposed by lake drawdown varied from 0 to 65 percent. Groundwater reaction to lake stage explained some of the variation in individual spawning area survival. Three types of groundwater reaction to lake stage were identified. Increased survival in exposed redds resulted from two of the three types. A significant statistical relationship was determined between embryo survival and the number of days exposed by lake drawdown. The operation of Kerr Dam in 1983-84 was characterized by an early decline in lake stage, a longer period near minimum pool and a later and more rapid filling compared to the operation seen in 1981-82 and 1982-83. Based on the survival relationship observed in natural redds exposed by drawdown in 1983-84, complete mortality from exposure would have occurred to all redds constructed above 2884.7 ftor 90 percent of all redds constructed above minimum pool. Emergence traps placed over redds below minimum pool in Gravel, Blue, and Yellow bays captured fry in Gravel and Blue bays only. Duration of fry emergence in1984 was three weeks longer than in 1982 or 1983, but was not related to the date of initial redd construction. Survival to fry emergence in Gravel Bay was calculated to be 28.9 percent of egg deposition or 57,484 fry. Survival to fry emergence above and below the zone of greatest redd density was 33.6 and 245 percent, respectively, indicating a relationship between survival and spawner site selection. After analysis of the historic operation of Kerr Dam, it is believed that the dam has, and is continuing to have, a significant impact on successful shoreline spawning of kokanee salmon in Flathead Lake. Based on the evidence that prolonged exposure of salmonid embryo by dewatering causes significant mortality, the number of days the lake was held below various foot increments (2884 ft to 2888 ft) during the incubation period was investigated. The annual change in the number of days the lake was held below 2885 ft was further investigated because 80-90 percent of the redds cons

Decker-Hess, Janet; Clancey, Patrick (Montana Department of Fish, Wildlife and Parks, Kalispell, MT)

1984-03-01

36

Earth-Fissure Movements Associated with Fluctuations in Ground-Water Levels Near the Picacho Mountains, South-Central Arizona, 1980-84.  

Science.gov (United States)

The purposes of the study were to test the hypothesis that the opening, closing, and vertical offset of a major earth fissure can be correlated with water-level fluctuations in nearby piezometers and to use dislocation modeling of land-surface deformation...

M. C. Carpenter

1993-01-01

37

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  

International Nuclear Information System (INIS)

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)

1995-01-01

38

Study on planting technology for the slope of water level fluctuation part of water reservoir; Chosuichi suii hendobu norimen no ryokuka gijutsu ni kansuru kenkyu  

Energy Technology Data Exchange (ETDEWEB)

It has become a problem from the viewpoint of aspect and slope protection that plants can not grow on the slope of water reservoir of hydro-power plants due to the repetition of raise and down of water level for a long term, which makes the slope a barren zone. In order to improve the barren slope, the Kansai Electric Power Co., Inc. has studied on the planting technology for the slope of water level fluctuation since 1993. This paper describes the interim results of planting tests conducted at the pumped storage power plant. Among the plants tested in this time, seedlings of sweet flags and willow, and seeds of reed canary grass were found to be useful. From the growth of plants, there was not any difference due to the slope. When planting is conducted by seeds, especially the initial germination and rooting were problems. It was required to seed down at least one year before to root firmly without effects of covering with water immediately after germination. Even if rooting only within the planting base spray, the encroachment prevention effect of soil can be recognized. The soil was stable through the encroachment prevention method, and exotic species could be found where soil has deposited. 5 refs., 6 figs., 5 tabs.

Kiyohara, M.; Onishi, M.; Doi, S. [Kansai Electric Power Co. Inc., Osaka (Japan)

1996-05-05

39

Climatic fluctuations and water management  

Energy Technology Data Exchange (ETDEWEB)

The conference was held to emphasise the importance of climatic fluctuations in water management. The papers are divided into five categories: monitoring, forecasting and analysis procedures; impact of climatic changes; planning and management; case studies and reports which look at the Nile delta, Lahnstein-on-Rhine in Germany, and the effect of El Nino on the Indian climate, and finally the keynote lectures and recommendations. Five papers are abstracted.

Abuzeid, M.A.; Biswas, A.K. (eds.)

1992-01-01

40

[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

 
 
 
 
41

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 < 0.001 and biomass (ANOVA; p < 0.001 in each sampling period, ranging from 143.9 cm and 338.8 g dry wt.m-2, before the sandbar opening, to 16.3 cm and 20.2 g dry wt.m-2 respectively after the sandbar breaching. The drastic variation of the water level, leading mass mortality of the stems, together with the lowest mean biomass/stem (0.057 g dry wt.individual-1, recorded after the sandbar breaching, did not represent a strong disturbance for E. interstincta, since the resilience time estimated for this population was about 30 days.

Santos Anderson Medeiros dos

2004-01-01

42

Analysis of water-level fluctuations of Lakes Winona and Winnemissett-- two landlocked lakes in a karst terrane in Volusia County, Florida  

Science.gov (United States)

The water levels of Lakes Winona and Winnemissett in Volusia County, Fla., correlate reasonably well during dry spells but only poorly during wet spells. Disparities develop mostly at times when the lake levels rise abruptly owing to rainstorms passing over the lake basins. The lack of correlation is attributed to the uneven distribution of the storm rainfall, even though the average annual rainfall at National Weather Service gages in the general area of the lakes is about the same. Analyses of the monthly rainfall data show that the rainfall variability between gages is sufficient to account for most of the disparity between monthly changes in the levels of the two lakes. The total annual rainfall at times may differ between rainfall gages by as much as 15 to 20 inches. Such differences tend to balance over the long term but may persist in the same direction for two or more years, causing apparent anomalies in lake-level fluctuations. (Woodard-USGS)

Hughes, G. H.

1979-01-01

43

Long transients near the ghost of a stable state in eutrophic shallow lakes with fluctuating water levels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Alternative stable states in shallow lakes have received much attention over the past decades, but less is known about transient dynamics of such lakes in the face of stochastic perturbations such as incidental extremes in water levels driven by climatic variability. Here, we report on the ecosystem dynamics of 70 lakes in the floodplains of the Lower Rhine in The Netherlands from 1999 to 2004. In any particular year, most lakes were either in a macrophyte-dominated clear state or in a contra...

Geest, G. J.; Coops, H.; Scheffer, M.; Nes, E. H.

2007-01-01

44

Common cyclicities in the seismicity and water level fluctuations at the charlevoix seismic zone on the St Lawrence River, Quebec, Canada  

Science.gov (United States)

Intraplate seismicity has no widely accepted explanation for its origin. The hydroseismicity hypothesis suggests that natural increases in hydraulic head, caused by transient increases in water table elevation, can be transmitted to hypocentral depths (10-25 km) in a fractured, prestressed, near-failure crust, and, along with long term hydrolytic weakening of rocks, contribute to the triggering of earthquakes. In this study, the temporal characteristics of seismicity and water level fluctuations at the Charlevoix seismic zone on the Saint Lawrence River in Quebec, Canada, are determined using Fourier spectral analysis and are investigated for possible temporal relationships, as predicted by hydroseismicity, using group delay analysis. Fourier spectral analysis of the temporal release of seismic energy indicates the presence of short term cyclicities of periods of 13-14 yr, along with longer term periods of approx. 55-70 yr. Spectral analysis of the water level data indicates cyclicities with periods of 1, 23, 14 and 8 years. Group delay analysis of the 14 yr periodicities in the water level and seismicity time series yields a time lag of 2.3-2.6 yr, with the water levels leading the seismicity time series. Crustal diffusivity values estimated from the group delay analysis range between 0.3 and 2.7 m 2/s, for a depth interval from 7 to 20 km, which is within the range of published values of diffusivities for the crust (0.1-100 m 2/sec). The present study suggests that common cyclicities are present in both the water levels and seismicity in the Charlevoix region. Such cyclicities are an essential element of the hydroseismicity hypothesis for the diffusion of surficial fluid pressure variations to hypocentral depths. Furthermore, the temporal relationship between the cyclicities observed allows for a possible causal relationship between repetitive mechanical effects of pore pressure transients and seismicity in the Charlevoix region.

Tsoflias, George P.; Bollinger, G. A.; Costain, John K.

1995-03-01

45

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

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

46

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

47

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 regulation has caused marked ecological changes in the littoral zone of TGR. The littoral zone formed after impounded by TGR not only is the crucible to us, but also the ecological opportunity. The vegetation of large-scale hydro-fluctuation belt is a very valuable resource, if properly used, can turn harm into advantage. In view of the current status and existing problems of the littoral wetland in TGR, we should focus on utilizing resources of the littoral wetland eco-friendly. Based on the needs for the littoral wetland transform into the multifunctional ecological economic benefit such as increasing carbon sources, biological production, and environmental purification, we must develop the ecological engineering model of sustainable utilizing the wetland resources of the littoral zone. In view of the environment problems of TGR and its characteristics of water level fluctuation, the ecological engineering focusing on restoration of littoral wetlands have been carried out since 2008. The eco-logical engineering was mainly conducted at littoral wetlands in Baijia stream of Pengxi River of TGR, including dike-pond system, submergence tolerance wetland-woods and waterfowl habitats recreate projects. The design principle and process for the ecological engineering of littoral wetlands restoration under the condition of the periodic water level change was described in details in this paper. Effects of the ecological engineering and the benefits to the environments were assessed. In the end of the article we proposed that the ecological engineering focus on the restoration of littoral wetlands, also should consider uti.

WANG Qiang

2012-05-01

48

Laboratory tests to assess water-level fluctuations at Vernita Bar, Washington, USA. [Effects on chinook salmon redd  

Energy Technology Data Exchange (ETDEWEB)

Vernita Bar chinook salmon redd dewatering was simulated in gravel-filled aquaria. Dewatering before hatching did not affect survival; after hatching a few hours of dewatering was fatal. Weather conditions at Vernita Bar was not a factor in assessing dewatering effects. Above-ground watering of dewatered redds may protect alevins and eleutheroembryos.

Neitzel, D.A.; Becker, C.D.; Abernethy, C.S.

1985-02-01

49

Plant communities in relation to flooding and soil characteristics in the water level fluctuation zone of the Three Gorges Reservoir, China.  

Science.gov (United States)

With the filling of the Three Gorges Reservoir, original vegetation in the water level fluctuation zone (WLFZ) between the elevations of 145 and 175 m disappeared due to the reversal of submergence time (winter flooding) and prolonged inundation duration (nearly half a year). To better understand the relationships between the environmental factors and recovered plant communities for reconstructing floristically diverse riparian zone, we conducted a field survey in 11 sites in the WLFZ in June 2010, and vegetation composition, flooding characteristics, heavy metals, and soil major nutrients were determined. Consequently, the canonical correspondence analysis was used to investigate the relationships between plant species composition and flooding characteristics, heavy metal contamination, and soil nutrients. Results demonstrated that vegetation in the WLFZ was dominated by annuals, i.e., Echinochloa crusgalli and Bidens tripartita, and perennials including Cynodon dactylon, and plant species richness and diversity were negatively associated with flooding duration, heavy metal contamination, and nutrients including total phosphorus, available phosphorus, available potassium, and nitrate. Our results suggest that plant species, recovering mainly through soil seed bank and regeneration of remnant individuals, have been influenced by the combined effects of environmental factors. PMID:22968672

Ye, Chen; Zhang, Kerong; Deng, Qi; Zhang, Quanfa

2013-03-01

50

Spatial patterns of zooplanktivore Chirostoma species (Atherinopsidae) during water-level fluctuation in the shallow tropical Lake Chapala, Mexico: seasonal and interannual analysis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in spanish El presente estudio describe la influencia que tiene la fluctuación del nivel del agua en la distribución de los peces a dos diferentes escalas: estacional (estiaje y lluvias) e interanual (condiciones de bajo y alto volumen). El análisis de las relaciones de abundancia entre tres especies zooplanct [...] ófagas de Chirostoma en quince sitios del Lago de Chapala, México, reveló una influencia estadísticamente significativa en las condiciones contrastantes (P=0.0002). Estacionalmente, la segregación estuvo más relacionada a la dominancia de las especies en la época de estiaje y exclusivamente relacionada a las características ambientales en la época de lluvias. Interanualmente, la influencia biótica se presenta en los episodios más someros y más profundos del lago. Las características ambientales influenciaron la distribución de las especies cuando el lago alcanzó el 25% de su volumen. El sitio geográfico, profundidad, temperatura y salinidad fueron los principales factores que influenciaron la distribución de los peces. Estos resultados enfatizan la necesidad de implementar diferentes estrategias de manejo de acuerdo al volumen del lago, particularmente cuando se alcanza un umbral crítico. Abstract in english This study addresses the influence of water-level fluctuations on fish distribution at two temporal scales: seasonal (dry and rainy) and interannual (low and high volume conditions). The analysis of abundance relationships among three zooplanktivore Chirostoma species at fifteen sites in Lake Chapal [...] a, Mexico, revealed the significant influence of contrasting conditions (P=0.0002). Seasonally, segregation was more related to species dominance in the dry season and exclusively related to environmental characteristics in the rainy season. Interanually, biotic influence occurred in the shallowest and the deepest episodes of the lake. Environmental characteristics influenced species distribution when the lake reached 25% of its volume. Site, depth, temperature, and salinity were the leading factors influencing fish distribution. These results emphasize the necessity to implement different management strategies according to lake volume, particularly when a critical threshold is reached.

Moncayo-Estrada, Rodrigo; Escalera-Gallardo, Carlos; Lind, Owen T..

51

Periodic behavior of groundwater level fluctuations in residential areas  

Science.gov (United States)

SummaryFor residential cities and their suburbs the continuous increase in groundwater level constitutes a common problem that can threaten the buried pipeline systems and structures, as well as road pavements. In this paper, the periodic pattern of groundwater level fluctuations is investigated for six monitoring wells located in residential areas in Kuwait. Monthly water level measurements obtained from the monitoring wells for periods varying from 8 to 10 years are employed to examine the relationship with monthly-averaged temperature and -totaled rainfall. The periodograms of the water level, rainfall, and temperature data are also determined. The results reveal that the annual periodicity typically observed in the last two climatological data sets can significantly be identified in all the series of subsurface water level examined here. Other periodicities of 27 and 18 months existing in the periodogram of rainfall are identified in two and four water level series, respectively. It is advocated here that the 27-month period present in the rainfall data of Kuwait is attributed to the well-known Quasi-Biennial Oscillation in zonal wind, which has been reported by many researchers for areas near the equator such as India and Indonesia. A time series model that triggers the influence of the detected periodicities is developed for the water level data to show an example of exploiting the fluctuation pattern for providing forecasts of groundwater table changes. The model can possibly be used to set a time plan for starting a continuous dewatering process to avoid problems related to groundwater level rise in residential areas.

Almedeij, Jaber; Al-Ruwaih, Fawzia

2006-09-01

52

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

53

Hydrophobic nanoconfinement suppresses fluctuations in supercooled water  

Science.gov (United States)

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 interfaces among domains with different local order, promoted by the hydrophobic effect of the water-hydrophobic-nanoparticle interfaces.

Strekalova, E. G.; Mazza, M. G.; Stanley, H. E.; Franzese, G.

2012-02-01

54

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

55

Fluctuations in number of water molecules confined between nanoparticles.  

Science.gov (United States)

We used molecular dynamics computer simulations to study the character of interactions between two nanoscale graphene plates in water and also between plates made of "carbon" atoms that have different interaction strength with water. Fluctuations in the number of water molecules in the confined space between plates are qualitatively similar when the plates are made of graphene or when the plates contain "carbon" atoms with weaker "carbon"-water interaction strength. We also observed that these fluctuations are strongly enhanced compared to the fluctuations observed next to a single plate. If the character of water fluctuations in the confined space determines the character of interactions, then it is possible to conclude that the interaction between graphene plates in water is hydrophobic. PMID:20925366

Eun, Changsun; Berkowitz, Max L

2010-10-28

56

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

57

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

58

Quantal Fluctuations in Fluorescence Lifetimes of Individual Rovibronic Levels.  

Science.gov (United States)

Measured fluorescence lifetimes of individual rovibronic levels in SiH2 (A(1)B(1), OnO), n =1,2,3 vary irregularly from one level to the next. The distribution of these fluctuations is well fitted by the procedure of maximal entropy. This suggests that th...

Y. M. Engel R. D. Levine J. W. Thoman J. I. Steinfeld R. I. McKay

1987-01-01

59

Effects of fluctuating glucose levels on neuronal cells in vitro.  

Science.gov (United States)

There is increasing evidence for glucose fluctuation playing a role in the damaging effects of diabetes on various organs, including the brain. We aimed to study the effects of glycaemic variation (GV) upon mitochondrial activity using an in vitro human neuronal model. The metabolic disturbance of GV in neuronal cells, was mimicked via exposure of neuroblastoma cells SH-SY5Y to constant glucose or fluctuating (i.e. 6 h cycles) for 24 and 48 h. Mitochondrial dehydrogenase activity was determined via MTT assay. Cell mitochondrial activity (MTT) was moderately decreased in constant high glucose, but markedly decreased following 24 and 48 h of cyclical glucose fluctuations. Glucose transport determined via 2-deoxy-D-[1-(14)C] glucose uptake was regulated in an exaggerated manner in response to glucose variance, accompanied by modest changes in GLUT 1 mRNA abundance. Osmotic components of these glucose effects were investigated in the presence of the osmotic-mimics mannitol and L: -glucose. Both treatments showed that fluctuating osmolality did not result in a significant change in mitochondrial activity and had no effects on (14)Cglucose uptake, suggesting that adverse effects on mitochondrial function were specifically related to metabolically active glucose fluctuations. Apoptosis gene expression showed that both intrinsic and extrinsic apoptotic pathways were modulated by glucose variance, with two major response clusters corresponding to (i) glucose stress-modulated genes, (ii) glucose mediated osmotic stress-modulated genes. Gene clustering analysis by STRING showed that most of the glucose stress-modulated genes were components of the intrinsic/mitochondrial apoptotic pathway including Bcl-2, Caspases and apoptosis executors. On the other hand the glucose mediated osmotic stress-modulated genes were mostly within the extrinsic apoptotic pathway, including TNF receptor and their ligands and adaptors/activators/initiators of apoptosis. Fluctuating glucose levels have a greater adverse effect on neuronal cell energy regulation mechanisms than either sustained high or low glucose levels. PMID:22565596

Russo, Vincenzo C; Higgins, Sandra; Werther, George A; Cameron, Fergus J

2012-08-01

60

Influence of two-level fluctuators on adiabatic passage techniques  

CERN Document Server

We study the effect of two-level fluctuators (TLFs), as they are frequently present in solid-state devices, on the process of Stimulated Raman Adiabatic Passage (STIRAP) performed with a quan- tum three-level system. When the amplitudes of the driving-pulses used in the STIRAP are in resonance with the level spacing of the fluctuators the quality of the protocol, i.e., the transferred population decreases sharply. In general the effect can not be reduced by speeding up the STIRAP process. We also discuss the effect of a structured noise environment on the process of Coherent Tunneling by Adiabatic Passage (CTAP). The effect of a weakly structured environment or TLFs with short coherence times on STIRAP and CTAP can be described by the Bloch-Redfield theory. For a strongly structured environment a higher-dimensional approach has to be used where the TLFs are treated as part of the system.

Vogt, Nicolas; Marthaler, Michael; Schön, Gerd

2012-01-01

 
 
 
 
61

Water-level variations in the sea of marmara  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Characteristics of water level variations in the Sea of Marmara have been investigated. Long-period oscillations of non-tidal origin have been identified in the analysis. These oscillations are due to regular fluctuations of water level throughout the year caused by meteorological and oceanographic influences. Greater fluctuations are produced by local winds, river runoff and inflow from the Black Sea. These fluctuations increase rapidly in spring and early August, the latter due to Black Sea...

Yuce, Hy

1993-01-01

62

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

63

High levels of fluctuating asymmetry in isolated stickleback populations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Fluctuating asymmetry (FA), defined as small random deviations from the ideal bilateral symmetry, has been hypothesized to increase in response to both genetic and environmental stress experienced by a population. We compared levels of FA in 12 bilateral meristic traits (viz. lateral-line system neuromasts and lateral plates), and heterozygosity in 23 microsatellite loci, among four marine (high piscine predation risk) and four pond (zero piscine ...

Trokovic Nina; Herczeg Gábor; Ghani Nurul Izza; Shikano Takahito; Merilä Juha

2012-01-01

64

Water level instrumentation simulation  

Energy Technology Data Exchange (ETDEWEB)

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 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)

Berger, W.E.; Raines, J.C.; Hammersley, R.J.; Henry, R.E. [Fauske and Associates, Inc., Burr Ridge, IL (United States)

1996-07-01

65

Free product recovery at spill sites with fluctuating water tables  

International Nuclear Information System (INIS)

Spills and leaks of hydrocarbons from underground storage tanks, pipelines and other facilities pose a serious potential for groundwater contamination which can be very costly to remediate. The severity of the impacts and the cost of remediation can be reduced by various means. Lateral spreading of free phase hydrocarbons on the groundwater table can be prevented by pumping water to control the hydraulic gradient. Recovery of floating product may be performed by skimming hydrocarbons from wells, usually in combination with water pumping to increase the gradient. The environmental variables (water table gradient, water table fluctuations due to regional recovery wells, rates of water pumping)

1991-05-13

66

Coupling water table fluctuation to mercury speciation and transport in wetland ecosystems  

Science.gov (United States)

Hydrological processes exert a first-order control over both the conditions required for mercury methylation to occur, and the transport of methylmercury from sites of production. In the recent literature, evidence has been presented that a relationship exists between water level fluctuation and mercury levels in aquatic organisms. These observations have led to the conclusion that this fluctuation is stimulating mercury methylation in littoral sediments and wetland ecosystems through the creation of favourable biogeochemical conditions. Using data from a range of wetland ecosystems, and several experiments that subjected wetland soils to fluctuating water levels, a relationship between water table fluctuation frequency and methylmercury production will be presented. Experimental data show that longer frequency wetting and drying periods result in greater methylmercury production relative to a static or high frequency fluctuation. It was also found that mercury methylation processes in wetland soils are able to sustain elevated pore water concentrations over repeated wetting and draining events. These data suggest that methylmercury export from wetlands is likely limited by the degree of hydrological connectivity rather than biogeochemical processes, highlighting the need to better understand the nature of hydrological linkages among wetlands and adjacent ecosystems.

Branfireun, B. A.; Mitchell, C. P.

2008-12-01

67

Quantum projection noise: Population fluctuations in two-level systems  

Science.gov (United States)

Measurements of internal energy states of atomic ions confined in traps can be used to illustrate fundamental properties of quantum systems, because long relaxation times and observation times are available. In the experiments described here, a single ion or a few identical ions were prepared in well-defined superpositions of two internal energy eigenstates. The populations of the energy levels were then measured. For an individual ion, the outcome of the measurement is uncertain, unless the amplitude for one of the two eigenstates is zero, and is completely uncertain when the magnitudes of the two amplitudes are equal. In one experiment, a single 199Hg+ ion, confined in a linear rf trap, was prepared in various superpositions of two hyperfine states. In another experiment, groups of 9Be+ ions, ranging in size from about 5 to about 400 ions, were confined in a Penning trap and prepared in various superposition states. The measured population fluctuations were greater when the state amplitudes were equal than when one of the amplitudes was nearly zero, in agreement with the predictions of quantum mechanics. These fluctuations, which we call quantum projection noise, are the fundamental source of noise for population measurements with a fixed number of atoms. These fluctuations are of practical importance, since they contribute to the errors of atomic frequency standards.

Itano, W. M.; Bergquist, J. C.; Bollinger, J. J.; Gilligan, J. M.; Heinzen, D. J.; Moore, F. L.; Raizen, M. G.; Wineland, D. J.

1993-05-01

68

Holocene Lake-Level Fluctuations of Lake Aricota, Southern Peru  

Science.gov (United States)

Lacustrine deposits exposed around Lake Aricota, Peru (17° 22'S), a 7.5-km 2 lake dammed by debris flows, provide a middle to late Holocene record of lake-level fluctuations. Chronological context for shoreline deposits was obtained from radiocarbon dating of vascular plant remains and other datable material with minimal 14C reservoir effects (Lake Titicaca (16°S), which is only 130 km to the northeast and shares a similar climatology. Comparisons with other marine and terrestrial records highlight emerging contradictions over the nature of mid-Holocene climate in the central Andes.

Placzek, Christa; Quade, Jay; Betancourt, Julio L.

2001-09-01

69

Partial width fluctuation method of determining nuclear level density  

Energy Technology Data Exchange (ETDEWEB)

A new method of determining the nuclear level density is presented. This method is based on the statistical analysis of the partial width fluctuations appearing in an excitation function of the radiative proton capture. The method was applied in the case of the /sup 88/Sr(p,..gamma..sub(..omega..))/sup 89/Y and /sup 89/Y(p,..gamma..sub(..omega..))/sup 90/Zr reactions. The density of levels with spin I/sup -/ in /sup 90/Zr and the densities of levels with spins 1/2/sup +/ and 3/2/sup +/ in /sup 89/Y at excitation energies from 10.9 to 11.6 MeV and from 9.3 to 10.8 MeV respectively, were determined with an uncertainty of about 35%.

Dygo, A.; Szeflinska, G.; Szeflinski, Z.; Wilhelmi, Z. (Warsaw Univ. (Poland). Inst. Fizyki Doswiadczalnej)

1982-04-12

70

Partial width fluctuation method of determining nuclear level density  

International Nuclear Information System (INIS)

A new method of determining the nuclear level density is presented. This method is based on the statistical analysis of the partial width fluctuations appearing in an excitation function of the radiative proton capture. The method was applied in the case of the "8"8Sr(p,?sub(?))"8"9Y and "8"9Y(p,?sub(?))"9"0Zr reactions. The density of levels with spin I"- in "9"0Zr and the densities of levels with spins 1/2"+ and 3/2"+ in "8"9Y at excitation energies from 10.9 to 11.6 MeV and from 9.3 to 10.8 MeV respectively, were determined with an uncertainty of about 35%. (orig.)

1982-04-12

71

Estimation of groundwater evaportranspiration using diurnal water table fluctuations in the Mu Us Desert, northern China  

Science.gov (United States)

Groundwater evapotranspiration (ETg) is a significant component of water balance analysis in desert areas. Estimation of ETg using diurnal water table fluctuations, i.e. the White method, is considered simple and straightforward, but it was seldom applied in desert areas. In this study, long-term and high-resolution groundwater level data were used to estimate ETg rate at two sites covered by typical desert plants Salix psammophila and Artemisia ordosica, respectively, in the Mu Us Desert in northern China. The specific yield (Sy) was derived from a drainage experiment in laboratory. The results showed that the water demand of S. psammophila could result in a weak but identifiable diurnal fluctuation of water table that was 2.35 m below the land surface, reasonable estimates of ETg could be derived from the White method, and the level of the ETg corresponded with the plant growth stages. However, the water table data from the area covered by A. ordosica did not show diurnal fluctuation during the growing season. The White method is good for the desert areas where groundwater use by other processes is negligible, and evapotranspiration is the main process for groundwater consumption. In addition, the information about diurnal water table fluctuations is useful for identification of groundwater-dependence of vegetation. A. ordosica is groundwater-independent, whereas S. psammophila is groundwater-dependent.

Cheng, Dong-hui; Li, Ying; Chen, Xunhong; Wang, Wen-ke; Hou, Guang-cai; Wang, Cun-liang

2013-05-01

72

A statistical approach to estimating evapotranspiration from diurnal groundwater level fluctuations  

Science.gov (United States)

the last few decades, automatic sensors that record groundwater levels at high-frequency intervals have become widely used in groundwater monitoring practice. These sensors provide large amounts of data regarding diurnal groundwater fluctuations, which can be treated as stochastic periodic time series. In this study, a simple relationship between the average standard deviation of diurnal groundwater level fluctuations and the daily evapotranspiration over relatively short periods (days or weeks) was developed for estimating groundwater consumption by phreatophytes in arid/semiarid areas. Our approach allows estimating groundwater evapotranspiration (ETg) using stable statistical characteristics of diurnal groundwater fluctuations, and it is useful for analyzing large amounts of data obtained from digital groundwater level monitoring sensors. A comparison of the ETg results from a synthetic set of groundwater level fluctuations with predefined values shows that this technique behaves consistently and is robust. A numerical analysis of one-dimensional saturated-unsaturated water flow to a root system using Richards' equation indicates that this method provides a reliable estimate of ETg when the basic assumptions of the White method are met. The method was also applied to two phreatophyte-dominated riparian sites in New Mexico to demonstrate its usefulness, which provides better results than the commonly used White method.

Wang, Ping; Pozdniakov, Sergey P.

2014-03-01

73

Fluctuation spectrum and size scaling of river flow and level  

CERN Multimedia

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

74

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.)

1997-01-14

75

Nuclear quantum effects and hydrogen bond fluctuations in water.  

Science.gov (United States)

The hydrogen bond (HB) is central to our understanding of the properties of water. However, despite intense theoretical and experimental study, it continues to hold some surprises. Here, we show from an analysis of ab initio simulations that take proper account of nuclear quantum effects that the hydrogen-bonded protons in liquid water experience significant excursions in the direction of the acceptor oxygen atoms. This generates a small but nonnegligible fraction of transient autoprotolysis events that are not seen in simulations with classical nuclei. These events are associated with major rearrangements of the electronic density, as revealed by an analysis of the computed Wannier centers and (1)H chemical shifts. We also show that the quantum fluctuations exhibit significant correlations across neighboring HBs, consistent with an ephemeral shuttling of protons along water wires. We end by suggesting possible implications for our understanding of how perturbations (solvated ions, interfaces, and confinement) might affect the HB network in water. PMID:24014589

Ceriotti, Michele; Cuny, Jérôme; Parrinello, Michele; Manolopoulos, David E

2013-09-24

76

Predicting climate fluctuations for water management by applying neural network  

Energy Technology Data Exchange (ETDEWEB)

The ability to forecast climate fluctuations would be a valuable asset to regional water management authorities such as the South Florida Water Management District. These forecasts may provide advanced warnings of possible extended periods of deficits or surpluses of water availability allowing better regional water management for flood protection, water supply, and environmental enhancement. In order to achieve this goal, it is necessary to have a global perspective of the oceanic and atmospheric phenomena which may affect regional water resources. However, the complexity involved may hinder traditional analytical approaches in forecasting because such approaches are based on many simplified assumptions about the natural phenomena. This paper investigates the applicability of neural networks in climate forecasting for regional water resources management. This paper applies the most widely used Back Propagation model to the climate forecasting. In this study, issues such as selecting a best fit neural network configuration, deploying a proper training algorithm, and preprocessing input data are addressed. The effects of various global oceanic and atmospheric variables to the regional water resources are also discussed. The study is focused on the prediction of water storage for Lake Okeechobee, the liquid heart for south Florida. Several global weather parameters over the past several decades are used as input data for training and testing. Different combinations of the variables are explored. Preliminary results show that the neural networks are promising tools in this type of forecasting.

Zhang, E.Y. [South Florida Water Management District, West Palm Beach, FL (United States)

1996-12-31

77

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

78

Effects of Salty Water and Temperature on Shape Fluctuations of a Few Correlated Phospholipids  

Science.gov (United States)

We evaluate effects of salty water and temperature on shape fluctuations of a few correlated phospholipids by calculating four parameters of aperture, symmetry, isotropy, and compactness. We perform molecular dynamics simulations of few POPC lipids for 8 ns in four different conditions: 300 K of water, 340 K of water, 300 K of salty water, and 340 K of salty water, respectively. From the results, adding salt and increasing temperature generally change each parameter. Because each parameter concerns shape fluctuations, the adding salt and the increasing temperature consequently contribute to shape fluctuations as well. Furthermore, we discuss roles of sodium as glue effect in connection with either the parameters or temperature, and investigate effects of the number of lipids on each parameter leading to the saturation effect of isotropy. From a geometrical consequence of isotropy-symmetry in both the salty and the pure water, we find shape fluctuation regions such as cone- like, rod-like, and sphere-like regions. Nevertheless, each parameter in the salty water shows more Gaussian distribution than in the pure water. Therefore, we then investigate the certain shape fluctuations in different conditions dealing with the distributions. Interestingly, the regions of shape fluctuations in the salty water are slightly different from those in the pure water. It apparently shows that they follow a fluctuation line. The fluctuation line likely contributes to occurring non-Gaussian distributions for the pure water.

Purqon, A.; Yamamoto, T.; Nishikawa, K.; Nagao, H.; Nishikawa, K.

79

Hall voltage fluctuations as a diagnostic of internal magnetic field fluctuations in high temperature superconductors and the half-filled Landau level  

CERN Document Server

Fluctuations of the Hall voltage reveal information about long wavelength magnetic field fluctuations. If gauge theories of strongly correlated electrons are correct, such fluctuations are particularly large in the half-filled Landau level and in high T_c superconductors. We present estimates for the magnitude, system size and frequency dependence of these fluctuations. The frequency dependence contains information about instantons in the gauge field.

Ioffe, L B; Millis, A J

1996-01-01

80

Why is the CMB fluctuation level 10^{-5}?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We explore the qualitative changes that would occur if the amplitude Q ~ 10^{-5} of cosmological density fluctuations were different. If is less than about 10^{-6}, the cosmological objects that form would have so low virial temperatures that they may be unable to cool and form stars, and would be so loosely bound that even if they could produce a supernova explosion, they might be unable to retain the heavy elements necessary for planetary life. If Q is greater than about 1...

Tegmark, Max; Rees, Martin

1997-01-01

 
 
 
 
81

Memorization of short-range potential fluctuations in Landau levels  

International Nuclear Information System (INIS)

We calculate energy spectra of a two-dimensional electron system in a perpendicular magnetic field and periodic potentials of short periods. The Coulomb interaction is included within a screened Hartree-Fock approximation. The electrostatic screening is poor and the exchange interaction amplifies the energy dispersion. We obtain, by numerical iterations, self-consistent solutions that have a hysteresis-like property. With increasing amplitude of the external potential the energy dispersion and the electron density become periodic, and they remain stable when the external potential is reduced to zero. We explain this property in physical terms and speculate that a real system could memorize short-range potential fluctuations after the potential has been turned off. (author)

1998-01-01

82

Fluctuations in sedation levels may contribute to delirium in ICU patients  

DEFF Research Database (Denmark)

Delirium in patients admitted to the intensive care unit (ICU) is a serious complication potentially increasing morbidity and mortality. The aim of this study was to investigate the impact of fluctuating sedation levels on the incidence of delirium in ICU.

Svenningsen, H; Egerod, Ingrid Eugenie

2013-01-01

83

Investigation of free level fluctuations in a simulated model of a sodium cooled Fast Breeder Reactor using pulsating conductance monitoring device  

International Nuclear Information System (INIS)

Highlights: ? An innovative approach for measurement of water level fluctuation is presented. ? Measurement was conducted with a PC based pulsating type level sensor. ? Deployed the technique in monitoring level fluctuation in PFBR simulated facility. ? The technique helped in validation of hot pool design of PFBR, India. - Abstract: A high resolution measurement technique for rapid and accurate monitoring of water level using an in-house built pulsating conductance monitoring device is presented. The technique has the capability of online monitoring of any sudden shift in water level in a reservoir which is subjected to rapid fluctuations due to any external factor. We have deployed this novel technique for real time monitoring of water level fluctuations in a specially designed ¼ scale model of the Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, India. The water level measurements in various locations of the simulated test facility were carried out in different experimental campaigns with and without inclusion of thermal baffles to it in specific operating conditions as required by the reactor designers. The amplitudes and the frequencies of fluctuations with required statistical parameters in hot water pool of the simulated model were evaluated from the online time versus water level plot in more convenient way using system software package. From experimental results it is computed that the maximum free level fluctuation in the hot pool of PFBR with baffle plates provided on the inner vessel is 30 mm which is considerably less than the value (?82 mm) obtained without having any baffle plates. The present work provided useful information for assessment of appropriate design which would be adopted in the PFBR for safe operation of the reactor.

2012-03-01

84

Cluster regression model and level fluctuation features of Van Lake, Turkey  

Directory of Open Access Journals (Sweden)

Full Text Available Lake water levels change under the influences of natural and/or anthropogenic environmental conditions. Among these influences are the climate change, greenhouse effects and ozone layer depletions which are reflected in the hydrological cycle features over the lake drainage basins. Lake levels are among the most significant hydrological variables that are influenced by different atmospheric and environmental conditions. Consequently, lake level time series in many parts of the world include nonstationarity components such as shifts in the mean value, apparent or hidden periodicities. On the other hand, many lake level modeling techniques have a stationarity assumption. The main purpose of this work is to develop a cluster regression model for dealing with nonstationarity especially in the form of shifting means. The basis of this model is the combination of transition probability and classical regression technique. Both parts of the model are applied to monthly level fluctuations of Lake Van in eastern Turkey. It is observed that the cluster regression procedure does preserve the statistical properties and the transitional probabilities that are indistinguishable from the original data.

Key words. Hydrology (hydrologic budget; stochastic processes · Meteorology and atmospheric dynamics (ocean-atmosphere interactions

Z. ?en

85

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

86

Detecting Drawdowns Masked by Environmental Stresses with Water-Level Models  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Detecting and quantifying small drawdown at observation wells distant from the pumping well greatly expands the characterized aquifer volume. However, this detection is often obscured by water level fluctuations such as barometric and tidal effects. A reliable analytical approach for distinguishing drawdown from nonpumping water-level fluctuations is presented and tested here. Drawdown is distinguished by analytically simulating all pumping and nonpumping water-level stresses simultaneously d...

Garcia, Ca; Halford, Kj; Fenelon, Jm

2013-01-01

87

Low level activity determination by means of gamma spectrometry with respect to the natural background fluctuation.  

Science.gov (United States)

The determination of low level activities of natural radionuclides from the uranium and thorium series by gamma-spectrometry faces the problem of proper natural background subtraction. Background fluctuation can cause differences in activity determination. Also the minimum detectable activity (MDA) of natural and artificial radionuclides can be influenced by background fluctuation. In this paper, results of the background fluctuation of shielded HPGe detectors with relative efficiency of 50-150% are presented together with the assessment of its influence on the determination of natural and artificial radionuclides. PMID:23562437

Dragounová, Lenka; Rulík, Petr

2013-11-01

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

Effects of sound level fluctuations on annoyance caused by aircraft-flyover noise  

Science.gov (United States)

A laboratory experiment was conducted to determine the effects of variations in the rate and magnitude of sound level fluctuations on the annoyance caused by aircraft-flyover noise. The effects of tonal content, noise duration, and sound pressure level on annoyance were also studied. An aircraft-noise synthesis system was used to synthesize 32 aircraft-flyover noise stimuli representing the factorial combinations of 2 tone conditions, 2 noise durations, 2 sound pressure levels, 2 level fluctuation rates, and 2 level fluctuation magnitudes. Thirty-two test subjects made annoyance judgements on a total of 64 stimuli in a subjective listening test facility simulating an outdoor acoustic environment. Variations in the rate and magnitude of level fluctuations were found to have little, if any, effect on annoyance. Tonal content, noise duration, sound pressure level, and the interaction of tonal content with sound pressure level were found to affect the judged annoyance significantly. The addition of tone corrections and/or duration corrections significantly improved the annoyance prediction ability of noise rating scales.

Mccurdy, D. A.

1979-01-01

90

The fluctuations of Lago Maggiore levels in a regulated regime consideration on low water events (Le fluttuazioni di livello del Lago Maggiore in regime regolato: considerazioni sugli eventi di magra)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Lago Maggiore, due to the elevation and morphological nature of its drainage basin and to its location in a high precipitation climatic zone with a great inter-annual variability, is a water body with a high hydrogeological risk in that it is subject to floods and low water episodes that can be long-lasting. This last aspect, rather neglected in the previous studies, poses a serious risk for the communities on the shoreline and also for the use of the water resources for the irrigation of a w...

Barbanti, Luigi; Ambrosetti, Walter; Rolla, Angelo

2007-01-01

91

1/f fluctuations of amino acids regulate water transportation in aquaporin 1  

Science.gov (United States)

Aquaporins (AQPs), which transport water molecules across cell membranes, are involved in many physiological processes. Recently, it is reported that the water-water interactions within the channel are broken at the aromatic/arginine selectivity filter (ar/R region), which prevents proton transportation [U. K. Eriksson et al., Science 340, 1346 (2013), 10.1126/science.1234306]. However, the effects of the conformational fluctuations of amino acids on water transportation remain unclear. Using all-atom molecular dynamics simulations, we analyze water transportation and fluctuations of amino acids within AQP1. The amino acids exhibit 1/f fluctuations, indicating possession of long-term memory. Moreover, we find that water molecules crossing the ar/R region obey a non-Poisson process. To investigate the effect of 1/f fluctuations on water transportation, we perform restrained molecular dynamics simulations of AQP1 and simple Langevin stochastic simulations. As a result, we confirm that 1/f fluctuations of amino acids contribute to water transportation in AQP1. These findings appreciably enhance our understanding of AQPs and suggest possibilities for developing biomimetic nanopores.

Yamamoto, Eiji; Akimoto, Takuma; Hirano, Yoshinori; Yasui, Masato; Yasuoka, Kenji

2014-02-01

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.

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

93

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.I. Gonzu00E1lez-Trejo

2012-01-01

94

Diurnal temperature fluctuations in an artificial small shallow water body  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For aquatic biological processes, diurnal and annual cycles of water temperature are very important to plants as well as to animals and microbes living in the water. An existing one-dimensional model has been extended to simulate the temperature profile within a small water body. A year-round outdoor experiment has been conducted to estimate the model input parameters and to verify the model. Both model simulations and measurements show a strong temperature stratification in the water during ...

Jacobs, A. F. G.; Heusinkveld, B. G.; Kraai, S.; Paaijmans, K. P.

2008-01-01

95

Relationship between fluctuations in glucose levels measured by continuous glucose monitoring and vascular endothelial dysfunction in type 2 diabetes mellitus  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Fluctuations in blood glucose level cause endothelial dysfunction and play a critical role in onset and/or progression of atherosclerosis. We hypothesized that fluctuation in blood glucose levels correlate with vascular endothelial dysfunction and that this relationship can be assessed using common bedside medical devices. Methods Fluctuations in blood glucose levels were measured over 24?hours by continuous glucose monitoring (CGM) on admi...

Torimoto Keiichi; Okada Yosuke; Mori Hiroko; Tanaka Yoshiya

2013-01-01

96

Model of m-level low-frequency current fluctuations in metal thermionic cathodes  

International Nuclear Information System (INIS)

A new model of low-frequency fluctuations, based on the thermionic current model [Mathematical Handbook for Scientists and Engineers, New York, 1961; Introduction to Statistical Radio-Physic. Part 1: Random Processes, Moscow, 1976 (in Russian)], has been designed. The proposed model provides calculation of realization, auto-correlation function (ACF) and power spectral density (PSD) of an m-level quantum signal. This model has allowed to explain the reason of very small magnitude of low-frequency (LF) boundary (10-4 to 10-2 Hz) on experimental spectra of LF current fluctuations in a metal thermionic cathodes

2003-06-15

97

Diagenesis and porosity development associated with major sea level fluctuations, Upper Permian, Jameson land, east Greenland  

Energy Technology Data Exchange (ETDEWEB)

The Upper Permian of Jameson Land includes two major carbonate sequences, represented by the Karstryggen and Wegener Halvoe formations. The initial Karstryggen transgression led to the development of a shallow marine platform with structurally controlled evaporite basins (salinas) separated by stromatolitic, peloidal, or micritic carbonate depositional areas. The Wegener Havloe sequence reflects more rapid and extensive transgression with the deposition of three subcycles of fully marine, platform, or biohermal carbonates containing minor evaporites near the basin margins. Bioherms (bryozoan-brachiopod-marine cement mounds) show > 100 m of relief, indicating that large relative sea level changes were involved. Both the Karstryggen and Wgener Havloe cycles were terminated by major regressions, which led to karstic and/or fluvial incision of the underlying sequences. Not surprisingly, carbonate and evaporite diagenesis was greatly affected by these regional or eustatic sea level fluctuations. Evaporites dissolved or were replaced by calcite and celestite under the influence of meteoric waters. Limestones show collapse brecciation, grain leaching, soil development, and characteristic vadose and phreatic cements. Most significantly meteoric flushing led to massive dissolution of botryoidal marine cements (aragonite and probable high-Mg calcite) within biohermal facies on the Wegener Peninsula. This early porosity resurrection led to the preservation of porous bioherm core zones until hydrocarbon migration. Only late (posthydrocarbon), probably hydrothermal fluid flow led to cementation of the bioherm cores while expelling most of the reservoired hydrocarbons. If the sea level changes affecting the Greenlandic Permian are eustatic, then this study may provide significant clues to porosity development throughout the largely unexplored northern Zechstein basin.

Scholle, P.A.; Ulmer, D.S. (Southern Methodist Univ., Dallas, TX (USA)); Stemmerik, L. (Greenland Geological Survey, Copenhagen (Denmark))

1990-05-01

98

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.)

1984-01-01

99

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

Directory of Open Access Journals (Sweden)

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

100

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

 
 
 
 
101

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 c...

Kasimov, N. S.; Gennadiev, A. N.; Kasatenkova, M. S.; Lychagin, M. Y.; Kroonenberg, S. B.; Koltermann, P.

2012-01-01

102

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 c...

Kasimov, Nicolay S.; Gennadiev, Alexandre N.; Kasatenkova, Maria S.; Lychagin, Michail Y.; Kroonenberg, Salomon B.; Peter Koltermann

2012-01-01

103

Fluctuating energy level Landau-Teller theory: application to the vibrational energy relaxation of liquid methanol.  

Science.gov (United States)

State-to-state vibrational energy relaxation (VER) rates of the OH-stretch fundamental to select vibrational modes of liquid methanol are presented. The rates are calculated via a modified, fluctuating Landau-Teller (FLT) theory approach, which allow for dynamical vibrational energy level shifts. These rates are then compared to previously published results from Gulmen and Sibert [J. Phys. Chem. A 2004, 108, 2389] for the traditional Landau-Teller (LT) method as well as results calculated through time-dependent perturbation theory (TD), which naturally allow for the fluctuation. For the first time, this method is applied to a polyatomic molecular system, and the FLT theory greatly reduces the discrepancy between the LT and TD results or, at a minimum, is comparable to the LT approach with very little additional computational cost. PMID:16833910

Gulmen, Tolga S; Sibert, Edwin L

2005-07-01

104

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

1990-10-18

105

Fluctuations in Species-Level Protein Expression Occur during Element and Nutrient Cycling in the Subsurface  

Energy Technology Data Exchange (ETDEWEB)

While microbial activities in environmental systems play a key role in the utilization and cycling of essential elements and compounds, microbial activity and growth frequently fluctuates in response to environmental stimuli and perturbations. To investigate these fluctuations within a saturated aquifer system, we monitored a carbon-stimulated in situ Geobacter population while iron reduction was occurring, using 16S rRNA abundances and high-resolution tandem mass spectrometry proteome measurements. Following carbon amendment, 16S rRNA analysis of temporally separated samples revealed the rapid enrichment of Geobacter-like environmental strains with strong similarity to G. bemidjiensis. Tandem mass spectrometry proteomics measurements suggest high carbon flux through Geobacter respiratory pathways, and the synthesis of anapleurotic four carbon compounds from acetyl-CoA via pyruvate ferredoxin oxidoreductase activity. Across a 40-day period where Fe(III) reduction was occurring, fluctuations in protein expression reflected changes in anabolic versus catabolic reactions, with increased levels of biosynthesis occurring soon after acetate arrival in the aquifer. In addition, localized shifts in nutrient limitation were inferred based on expression of nitrogenase enzymes and phosphate uptake proteins. These temporal data offer the first example of differing microbial protein expression associated with changing geochemical conditions in a subsurface environment.

Wilkins, Michael J.; Wrighton, Kelly C.; Nicora, Carrie D.; Williams, Kenneth H.; McCue, Lee Ann; Handley, Kim M.; Miller, C. S.; Giloteaux, L.; Montgomery, A. P.; Lovley, Derek R.; Banfield, Jillian F.; Long, Philip E.; Lipton, Mary S.

2013-03-05

106

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

Science.gov (United States)

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. PMID:23927121

Catic, Jasmina; Santurette, Sébastien; Buchholz, Jörg M; Gran, Fredrik; Dau, Torsten

2013-08-01

107

Nonlinear bound on unstable fluctuation level in low-density non-neutral plasma  

International Nuclear Information System (INIS)

A cold-fluid model is used to describe the nonlinear evolutions of low-density non-neutral plasma immersed in a strong axial magnetic field. It is assumed that there is no axial dependence, and that the electron fluid moves with the usual E x B drift velocity. Use is made of global (spatially averaged) conservation constraints satisfied by the continuity and Poisson equations to obtain a non-linear bound on the unstable fluctuation level for a general initial density profile. (author)

1986-01-01

108

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

109

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

110

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

111

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

112

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 180"0 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

1980-10-12

113

Arrival-time fluctuations of coherent reflections from surface gravity water waves.  

Science.gov (United States)

Arrival time fluctuations of coherent reflections from surface gravity waves are examined. A two-dimensional ray model with an evolving rough sea surface is used to explain the mechanism and formation of the deterministic striation patterns due to the surface reflection. Arrival time predictions from the ray model match qualitatively well with the measurements from bidirectional acoustic transmissions in a water depth of 100?m. PMID:24815293

Badiey, Mohsen; Eickmeier, Justin; Song, Aijun

2014-05-01

114

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

115

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

116

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 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.)

2000-11-01

117

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

118

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

119

Random fluctuations of snow accumulation over antarctica and their relation to sea level change  

Energy Technology Data Exchange (ETDEWEB)

Short-term changes in the volume of ice sheets as analyzed by radar altimetry may not be related to long-term climatic change. Indeed, the large relaxation time of an ice sheet induces a low-frequency response to random fluctuations of snow accumulation. However, the time scale of the response is big compared to the average human lifetime and the effect of these random fluctuations on sea level change may be important even if they are not linked to climatic change. In this study, the relaxation time of an ice sheet is expressed with respect to the ice thickness, surface slope and ice velocity. These parameters are deduced from the precise topography derived from the geodetic cycle of the ERS1 radar altimeter. The variance of the induced effect on ice elevation is found to be around 3 m over a 30-year scale and with a maximum of 10 m in Wilkes Land and in the western part of the West Antarctic ice sheet. Near the coast, this effect can mask a climatic signal and thus be critical for altimetric mass balance surveys. The estimated changes in Antarctica's elevation between the Seasat (1978) and ERS (1993) epochs could be explained at least partially by such processes. In terms of sea level change over the 30-year scale, the standard deviation of the induced effect is 8 {+-} 2.8 cm. Finally, we show that the probability of a present-day, induced sea level rise of between 0.5 and 1 mm/year over a 30-year time scale is estimated at 10% {+-} 10%, with coastal areas accounting for half of this signal. (orig.)

Remy, F.; Testut, L.; Legresy, B. [LEGOS (CNRS-CNES-UPS), Toulouse (France)

2002-07-01

120

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

 
 
 
 
121

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

122

Methods of measuring water levels in deep wells  

Science.gov (United States)

Accurate measurement of water levels deeper than 1,000 feet in wells requires specialized equipment. Corrections for stretch and thermal expansion of measuring tapes must be considered, and other measuring devices must be calibrated periodically. Bore-hole deviation corrections also must be made. Devices for recording fluctuation of fluid level usually require mechanical modification for use at these depths. A multichannel recording device utilizing pressure transducers has been constructed. This device was originally designed to record aquifer response to nearby underground nuclear explosions but can also be used for recording data from multi-well pumping tests. Bottom-hole recording devices designed for oil-field use have been utilized in a limited manner. These devices were generally found to lack the precision required, in ground-water investigations at the Nevada Test Site but may be applicable in other areas. A newly developed bottom-hole recording pressure gauge of improved accuracy has been used with satisfactory results.

Garber, M. S.; Koopman, F. C.

1968-01-01

123

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

1993-04-02

124

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

Energy Technology Data Exchange (ETDEWEB)

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.

White, M.D.; Lenhard, R.J.

1993-03-01

125

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

126

Control of mould level fluctuation through the modification of steel composition  

Science.gov (United States)

Periodic mould level fluctuation (MLF) during slab casting is a bottleneck for upgrading the surface quality and casting speed especially for hypoperitectic (HP) or ultralow carbon steels. The uneven growth of the initially solidified shell is verified to be one of the important inducements to MLF due to related unsteady bulging in the secondary cooling zone. It is shown that the solidification mode of steels and the contraction behavior can be modified through chemical composition optimization within given composition limits. For high strength low alloy (HSLA) steels, the actual peritectic points calculated by Thermo-Calc software may change remarkably with the slight variations of alloying element contents. Accordingly, the narrow limit of chemical composition of HP steels through optimization is proven to be one of the effective factors to control the popular MLF phenomenon during slab casting.

Li, Yang; Zhang, Xiao-huan; Lan, Peng; Zhang, Jia-quan

2013-02-01

127

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

128

Electrical Resistivity Imaging of Tidal Fluctuations in the Water Table at Inwood Hill Park, Manhattan  

Science.gov (United States)

Inwood Hill Park is located on the northern tip of Manhattan and has been extensively modified over the years by human activities. In its current form, it has a backbone of exposed or lightly covered bedrock along the Hudson River, adjacent to a flat area with two tidal inlets along the northern shore of Manhattan. The tidal motions in the inlets are expected to drive corresponding fluctuations in the water table along the borders of the inlets. In the Fall of 2002, a group of students from the Department of Earth and Atmospheric Sciences at the City College of New York studied these fluctuations. Electrical resistivity cross sections were obtained with a Syscal Kid Switch 24 resistivity meter during the course of a tidal cycle at three locations surrounding the westernmost inlet in the park. No change was seen over a tidal cycle at Site 1, possibly due to the effect of concrete erosion barriers which were located between the land and the water surrounding this site. Measurements at Site 2 revealed a small, regular change in the water table elevation of approximately 5 cm over the course of a tidal cycle. This site is inferred to rest on alluvial sediments deposited by a small creek. The cross sections taken at different times during a tidal cycle at Site 3 were the most interesting. They show a very heterogeneous subsurface, with water spurting between blocks of high resistivity materials during the rising portion of the cycle. A small sinkhole was observed on the surface of the ground directly above an obvious plume of water in the cross section. Park personnel confirmed that this sinkhole, like others scattered around this site, is natural and not due to recent construction activity. They also indicated that debris from the construction of the New York City subways may have been dumped in the area in the past. Our conclusion is that the tidal fluctuations at Site 3 are being channeled by solid blocks in the construction debris, and that the sinkholes currently present result from removal of sediments from below, as a result of the tidal fluctuations.

Kenyon, P. M.; Kassem, D.; Olin, A.; Nunez, J.; Smalling, A.

2005-05-01

129

A heuristic approach to predicting water beetle diversity in temporary and fluctuating waters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An understanding of the causal mechanisms and processes that shape macroinvertebrate communities at a local scale has important implications for the management and conservation of freshwater biodiversity. Here we compare the performance of linear and non-linear statistics to explore diversity–environment relationships using data from 76 temporary and fluctuating ponds in two regions of southern England.We focus on aquatic beetle assemblages, which have been shown to be excellent...

Gutie?rrez Estrada, Juan Carlos; Bilton, David T.

2010-01-01

130

Pleistocene sea-level fluctuations and human evolution on the southern coastal plain of South Africa  

Science.gov (United States)

Humans evolved in Africa, but where and how remain unclear. Here it is proposed that the southern coastal plain (SCP) of South Africa may have served as a geographical point of origin through periodic expansion and contraction (isolation) in response to glacial/interglacial changes in sea level and climate. During Pleistocene interglacial highstands when sea level was above -75 m human populations were isolated for periods of 360-3400 25-yr generations on the SCP by the rugged mountains of the Cape Fold Belt, climate and vegetation barriers. The SCP expands five-fold as sea level falls from -75 to -120 m during glacial maxima to form a continuous, unobstructed coastal plain accessible to the interior. An expanded and wet glacial SCP may have served as a refuge to humans and large migratory herds and resulted in the mixing of previously isolated groups. The expansive glacial SCP habitat abruptly contracts, by as much as one-third in 300 yr, during the rapid rise in sea level associated with glacial terminations. Rapid flooding may have increased population density and competition on the SCP to select for humans who expanded their diet to include marine resources or hunted large animals. Successful adaptations developed on an isolated SCP are predicted to widely disperse during glacial terminations when the SCP rapidly contracts or during the initial opening of the SCP in the transition to glacial maxima. The hypothesis that periodic expansion and contraction of the SCP, as well as the coastal plain of North Africa, contributed to the stepwise origin of our species over the last 800 thousand years (kyr) is evaluated by comparing the archeological, DNA and sea-level records. These records generally support the hypothesis, but more complete and well dated records are required to resolve the extent to which sea-level fluctuations influenced the complex history of human evolution.

Compton, John S.

2011-03-01

131

Response of New zealand mudsnails Potamopyrgus antipodarum to freezing and near freezing fluctuating water temperatures  

Science.gov (United States)

We explored the resilience of the invasive New Zealand mudsnail Potamopyrgus antipodarum to fluctuating winter freezing and near-freezing temperature cycles in laboratory tests. Our goal was to provide data to confirm field observations of mortality and presumed mortality in stream habitats with fluctuating freezing to near-freezing temperatures. We tested individuals from 2 locations with distinctly different thermal regimes and population densities. One location had low snail densities and water temperatures with strong diel and seasonal water variation. The other location had high snail densities and nearly constant water temperatures. Groups of individuals from both locations were tested in each of 3 laboratory-created diel thermal cycles around nominal temperatures of 0, 2, or 4°C. Mortality occurred in cycles around 0°C in both populations, and little to no mortality occurred at temperatures >0°C. Individuals from both sources held in diel 0°C cycles for 72 h showed 100% mortality. Our findings support observations from published field studies that survival was limited in infested habitats subject to freezing temperatures.

Moffitt, Christine M.; James, Christopher A.

2012-01-01

132

Thermocouple-type water level monitoring device  

International Nuclear Information System (INIS)

A water level monitoring device for monitoring a water level in an upper plenum above a reactor core of a PWR type reactor container comprises an elongate cylindrical containing tube, and having a bubble separation portion disposed at the lower end thereof. A plurality of water level detector guide tubes are supported vertically by a dripping preventing plate in the containing tube. Water level detectors are inserted into the guide tubes such that each of vertical positions thereof is made different. A heat generation wire connected in a U-like shape to a lead wire and a chromel wire connected in a U-like shape by way of the alumel wire covered by an insulation material are disposed in the covering tube of the water level detector. The heat generation wire is not wound into a coil but extends in an axial direction while reciprocating at least once in the vicinity of a hot contact point. With such a constitution, responsibility is not worsened and erroneous observation of water level due to scattering of water droplets is not caused. (I.N.)

1995-02-09

133

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

134

Relationship between fluctuations in glucose levels measured by continuous glucose monitoring and vascular endothelial dysfunction in type 2 diabetes mellitus  

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Full Text Available Abstract Background Fluctuations in blood glucose level cause endothelial dysfunction and play a critical role in onset and/or progression of atherosclerosis. We hypothesized that fluctuation in blood glucose levels correlate with vascular endothelial dysfunction and that this relationship can be assessed using common bedside medical devices. Methods Fluctuations in blood glucose levels were measured over 24?hours by continuous glucose monitoring (CGM on admission day 2 in 57 patients with type 2 diabetes mellitus. The reactive hyperemia index (RHI, an index of vascular endothelial function, was measured using peripheral arterial tonometry (EndoPAT on admission day 3. Results The natural logarithmic-scaled RHI (L_RHI correlated with SD (r=?0.504; PPP=0.001 and percentage of time ?200?mg/dl (r=?0.292; P=0.028. In 12 patients with hypoglycemia, L_RHI also correlated with the percentage of time at hypoglycemia (r=?0.589; P=0.044. L_RHI did not correlate with HbA1c or fasting plasma glucose levels. Furthermore, L_RHI did not correlate with LDL cholesterol, HDL cholesterol, and triglyceride levels or with systolic and diastolic blood pressures. Finally, multivariate analysis identified MAGE as the only significant determinant of L_RHI. Conclusions Fluctuations in blood glucose levels play a significant role in vascular endothelial dysfunction in type 2 diabetes. Trial registration UMIN000007581

Torimoto Keiichi

2013-01-01

135

A point-wise least squares spectral analysis (LSSA) of the Caspian Sea level fluctuations, using TOPEX/Poseidon and Jason-1 observations  

Science.gov (United States)

The Caspian Sea has displayed considerable fluctuations in its water level during the past century. Knowledge of such fluctuation is vital for understanding the local hydrological cycles, climate of the region, and construction activities within the sea and along its shorelines. This study established a point-wise satellite altimetry approach to monitor the fluctuations of the Caspian Sea using a complete dataset of TOPEX/Poseidon for the period 1993 to the middle of 2002, and its follow-on Jason-1 for the period 2002 to August 2009. Therefore, 280 virtual time-series were constructed to monitor the fluctuations. The least squares spectral analysis (LSSA) method is, then employed to find the most significant frequencies of the time-series, while the statistical method of principle component analysis (PCA) is applied to extract the dominant variability of level variations. The study also used the observations of TOPEX/Poseidon and Jason-1 over the Volga River along with 5 years of Volga's water discharge to study its influence on the Caspian Sea level changes. The LSSA results indicate that the lunar semidiurnal (M2) and the Sun semidiurnal (S2) frequencies are the main tidal frequencies of the Caspian Sea with the mean amplitude of 4.2 and 2.8 cm, respectively. A statistically significant long-term frequency (12.5-years period) is also found from altimetry and tide gauge observations. A phase lag, related to the inter-annual frequencies of the Volga River was detected from the point-wise time-series showing level propagation from the northwest to the southeast of the sea. The cross-correlation between the power spectrum of Volga and that of the northern-most, middle, and southern-most points within the Caspian Sea were respectively 0.63, 0.51 and 0.4 of zero-lag correlation, corroborating the influence of the Volga River. The result of PCA also shows that different parts of the Caspian Sea exhibit different amplitudes of level variations, indicating that the point-wise approach, when employing all available satellite measurements could be a suitable method for a preliminary monitoring of this inland water resource as it gives accurate local fluctuations.

Sharifi, M. A.; Forootan, E.; Nikkhoo, M.; Awange, J. L.; Najafi-Alamdari, M.

2013-03-01

136

Thermal fluctuation levels of magnetic and electric fields in unmagnetized plasma: The rigorous relativistic kinetic theory  

International Nuclear Information System (INIS)

Any fully ionized collisionless plasma with finite random particle velocities contains electric and magnetic field fluctuations. The fluctuations can be of three different types: weakly damped, weakly propagating, or aperiodic. The kinetics of these fluctuations in general unmagnetized plasmas, governed by the competition of spontaneous emission, absorption, and stimulated emission processes, is investigated, extending the well-known results for weakly damped fluctuations. The generalized Kirchhoff radiation law for both collective and noncollective fluctuations is derived, which in stationary plasmas provides the equilibrium energy densities of electromagnetic fluctuations by the ratio of the respective spontaneous emission coefficient and the true absorption coefficient. As an illustrative example, the equilibrium energy densities of aperiodic transverse collective electric and magnetic fluctuations in an isotropic thermal electron-proton plasmas of density ne are calculated as |?B|=?((?B)2)=2.8(nemec2)1/2g1/2?e7/4 and |?E|=?((?E)2)=3.2(nemec2)1/2g1/3?e2, where g and ?e denote the plasma parameter and the thermal electron velocity in units of the speed of light, respectively. For densities and temperatures of the reionized early intergalactic medium, |?B|=6·10?18G and |?E|=2·10?16G result

2014-03-01

137

Magnetization reversal and two-level fluctuations by spin injection in a ferromagnetic metallic layer  

Science.gov (United States)

Slow magnetic relaxation and two-level fluctuations measurements under high current injection are performed in single-contacted ferromagnetic nanostructures. The magnetic configurations of the samples are described by two metastable states of the uniform magnetization. The current-dependent effective energy barrier due to spin transfer from the current to the magnetic layer is measured. The comparison between the results obtained with Ni nanowires of 6 ?m length and 60 nm diameter, and Co (10 nm)/Cu (10 nm)/ Co(30 nm) nanometric pillars of about 40 nm in diameter refined the characterization of this effect. It is shown that all observed features cannot be reduced to the action of a current dependent effective field. Instead, all measurements can be described in terms of an effective temperature, which depends on the current amplitude and direction. The system is then analogous to an unstable open system. The effect of current-induced magnetization reversal is interpreted as the balance of spin injection between both interfaces of the ferromagnetic layer.

Wegrowe, J.-E.

2003-12-01

138

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

139

Fluctuations in Species-Level Protein Expression Occur during Element and Nutrient Cycling in the Subsurface  

Digital Repository Infrastructure Vision for European Research (DRIVER)

While microbial activities in environmental systems play a key role in the utilization and cycling of essential elements and compounds, microbial activity and growth frequently fluctuates in response to environmental stimuli and perturbations. To investigate these fluctuations within a saturated aquifer system, we monitored a carbon-stimulated in situ Geobacter population while iron reduction was occurring, using 16S rRNA abundances and high-resolution tandem mass spectrometry proteome measur...

Wilkins, Michael J.; Wrighton, Kelly C.; Nicora, Carrie D.; Williams, Kenneth H.; Mccue, Lee Ann; Handley, Kim M.; Miller, Chris S.; Giloteaux, Ludovic; Montgomery, Alison P.; Lovley, Derek R.; Banfield, Jillian F.; Long, Philip E.; Lipton, Mary S.

2013-01-01

140

Water level regulation and control of schistosomiasis transmission: a case study in Oyan Reservoir, Ogun State, Nigeria.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effect of different water discharge patterns from the artificial Oyan Reservoir in Ogun State, Nigeria, on water level fluctuations and on schistosomiasis transmission was investigated between August 1990 and March 1993 to determine the impact of water level regulation on schistosomiasis transmission and control. The results show that transmission was greatly influenced by the pattern of water discharge during the hot dry season (January-April). A high discharge during this period of no r...

Ofoezie, I. E.; Asaolu, S. O.

1997-01-01

 
 
 
 
141

Millennial/submillennial-scale sea-level fluctuations in western Mediterranean during the second highstand of MIS 5e  

Science.gov (United States)

This paper investigates a series of small-scale, short-lived fluctuations of sea level registered in a prograding barrier spit that grew during the MIS 5e. This interglacial includes three highstands ( Zazo et al., 2003) and we focus on the second highstand, of assumed duration ˜10 ± 2 ka, given that U-Th ages do not provide more accurate data. Geometry and 3D architecture of beach facies, and thin-section petrography were used to investigate eight exposed offlapping subunits separated by seven conspicuous erosion surfaces, all interpreted as the result of repeated small-scale fluctuations of sea level. Each subunit records a relatively rapid rise of sea level that generated a gravelly shoreface with algal bioherms and a sandy uppermost shoreface and foreshore where most sand accumulated. A second range of still smaller-scaled oscillations of sea level has been deduced in this phase of sea-level fluctuation from lateral and vertical shifts of the foreshore-plunge-step-uppermost shoreface facies. Eventually, progradation with gently falling sea level took place and foreshore deposits underwent successive vadose cementation and subaerial dissolution, owing to relatively prolonged exposure. Later recovery of sea level re-established the highstand with sea level at approximately the same elevation, and there began deposition of a new subunit. The minimum sea-level variation (fall and subsequent rise) required to generate the observed features is 4 m. The time span available for the whole succession of events, and comparison with the Holocene prograding beach ridge complex in the nearby Roquetas (Almería) were used to calculate the periodicity of events. A millennial-suborbital time scale is suggested for fluctuations separating subunits and a decadal scale for the minor oscillations inside each subunit.

Dabrio, C. J.; Zazo, C.; Cabero, A.; Goy, J. L.; Bardají, T.; Hillaire-Marcel, C.; González-Delgado, J. A.; Lario, J.; Silva, P. G.; Borja, F.; García-Blázquez, A. M.

2011-02-01

142

A simple model for predicting water table fluctuations in a tidal marsh  

Science.gov (United States)

Wetland restoration efforts are ongoing in many urban estuaries. In this context the hydrologic characteristics of restored wetlands are of paramount importance since the spatially and temporally variable position of the water table and of soil saturation establishes the oxidation state of the substrate, which, in turn, affects the wetland's biogeochemical composition and the biological communities it is capable of supporting. A relatively simple analytical model developed here describes tidal marsh hydrology from creek bank to interior, considering transient drainage, net meteorological inputs, and tidal effects. Given a series of physical and time-dependent inputs, the analytical solution derived predicts the position of the water table at points along a transect perpendicular to a tidal creek. Validation of the model using water table time series data collected along three transects at Piermont Marsh, a tidal wetland on the Hudson River in the New York/New Jersey Estuary, indicates good general agreement between observations and predictions, although it may not be precise enough for some kinds of ecological applications. A sensitivity analysis on the model indicates that a range of pairs of transmissivity and specific yield values that increase with distance from the creek results in the same spatial and temporal fluctuations in the water table. This equifinality result is discussed as it relates to the predictive capacity of the model presented.

Montalto, Franco A.; Parlange, Jean-Yves; Steenhuis, Tammo S.

2007-03-01

143

Population fluctuations in a two-level atom excited by a field with amplitude and phase noise  

International Nuclear Information System (INIS)

Population fluctuations of a two-level atom excited by a quasi-resonance field with amplitude and phase (frequency) noise are studied. Analytic solutions are obtained relating spectral density of the population fluctuations to the radio-field noise, under the assumption of arbitrary radio-field power and small noise. The range of convergence of the analytic solutions obtained is examined using the computer simulation technique. Solution of the inverse problem - reconstruction of the field noise spectral densities from the measured population fluctuations - is discussed. The proposed formulation of the problem is related to studying the noise spectra of microwave sources and signals in radio-optic EPR spectroscopy and frequency stabilization. 8 refs., 3 figs

1994-11-01

144

Population fluctuations in a two-level atom excited by a field with amplitude and phase noise  

Energy Technology Data Exchange (ETDEWEB)

Population fluctuations of a two-level atom excited by a quasi-resonance field with amplitude and phase (frequency) noise are studied. Analytic solutions are obtained relating spectral density of the population fluctuations to the radio-field noise, under the assumption of arbitrary radio-field power and small noise. The range of convergence of the analytic solutions obtained is examined using the computer simulation technique. Solution of the inverse problem - reconstruction of the field noise spectral densities from the measured population fluctuations - is discussed. The proposed formulation of the problem is related to studying the noise spectra of microwave sources and signals in radio-optic EPR spectroscopy and frequency stabilization. 8 refs., 3 figs.

Pazgalev, A.S.; Yakobson, N.N. [Vavilov State Optical Institute, St. Petersburg (Russian Federation)

1994-11-01

145

Analysis of the cross-correlation between seismicity and water level in the Aswan area (Egypt) from 1982 to 2010  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study the correlation between the monthly fluctuations of the water level of the Aswan High Dam and monthly number of earthquakes from 1982 to 2010, which occurred in the surrounding area, was investigated. Our findings reveal that significant correlation is present during the period 1982–1993 between water level and shallow seismicity (depth less than 15 km). The deep seismicity (depth larger than 15 km) is significantly correlated with the water level between January and April 198...

2012-01-01

146

Thermal fatigue crack initiation and arrest behavior in labyrinth structure subjected to temperature fluctuation in pure water  

International Nuclear Information System (INIS)

At a tee junction point of piping system or labyrinth structure of pump seal, hot and cold water are mixed with each other in whirl. The vibrating mixing boundary between the hot and cold water induces a temperature fluctuation on a inside surface of the pipe just after the connection point or labyrinth land and bottom surface. The temperature fluctuation causes thermal fatigue. In this study the thermal stress distributions in the labyrinth structure were analyzed using FEM for various frequencies under the temperature fluctuation of turbulent water flow. The fracture mechanics analysis indicated that the thermal fatigue crack with relatively high frequency of 0.1 Hz to 25 Hz were arrested at a depth nearly proportional to square root of reciprocal of the frequency and it was about 3.8 mm for 1 Hz. (author)

2002-06-01

147

Water Level Detection Using Synthetic Aperture Radar Imagery  

International Nuclear Information System (INIS)

Reservoir water levels are of interest for international safeguards and domestic monitoring because they can be used as indicators of processing activity, uranium mine tailings protection status, or power generation for clandestine operation. Monitoring of water levels using satellite technology, especially civilian synthetic aperture radar (SAR) for remote or restricted-access sites worldwide has the potential to be a valuable tool for national/international safeguards as well as environmental monitoring applications. Unlike optical sensors, SAR is capable of reliable repeat monitoring regardless of cloud cover or solar illumination, i.e. it can image the target through clouds and darkness. Because of this ability, quick turn around for a SAR image is almost always guaranteed. SAR is very sensitive to the land/water interface and can be used to extract detailed elevation models. SAR is also sensitive to metallic structures or objects and can thus be useful in detection of heavy equipment or undeclared construction at decommissioned facilities. Although spaceborne SAR cannot match the resolution of optical satellites, future SAR satellites will offer much better resolution (e.g., approximately 3 metres for RADARSAT-2). Furthermore, future SAR satellites will offer different polarization and frequency channels to provide terrain and vegetation classification. The objective is to investigate the use of SAR for water level detection 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

2003-05-01

148

Effect of water-table fluctuations on the degradation of Sphagnum phenols in surficial peats  

Science.gov (United States)

A much improved understanding of how water-table fluctuations near the surface affect decomposition and preservation of peat-forming plant litter and surficial peats is needed in order to predict possible feedbacks between the peatland carbon cycle and the global climate system. In this study peatland plants (bryophytes and vascular plants), their litter and peat cores were collected from the Ryggmossen peatland in the boreonemoral zone of central Sweden. The extracted insoluble residues from whole plant tissues were depolymerized using thermally assisted hydrolysis and methylation (THM) in the presence of both unlabelled and 13C-labelled tetramethylammonium hydroxide (TMAH) which yielded both vascular plant- and Sphagnum-derived phenols. Methylated 4-isopropenylphenol (IUPAC: 1-methoxy-4-(prop-1-en-2-yl)benzene), methylated cis- and trans-3-(4'-hydroxyphen-1-yl)but-2-enoic acid (IUPAC: (E/Z)-methyl 3-(4-methoxyphenyl)but-2-enoate), and methylated 3-(4'-hydroxyphen-1-yl)but-3-enoic acid (IUPAC: methyl 3-(4-methoxyphenyl)but-3-enoate) (van der Heijden et al., 1997) are confirmed as TMAH thermochemolysis products of "bound" sphagnum acid and also as being specific to Sphagnum mosses. These putative biomarkers were also significant components in the unlabelled TMAH thermochemolysis products from the depolymerization of ultrasonically extracted samples from eight peat cores, one from a hummock and one from a hollow at each of the four stages along the bog plateau-to-swamp forest gradient. We have proposed and measured two parameters namely (i) ? which is defined as the total amount of these four molecules normalised to 100 mg of OC; and (ii) an index (SR%) which is the ratio of ? to the ? parameter giving a measure of the relative amounts of "bound" sphagnum acid to the "bound" vascular plant phenols in peat moss and the surficial peat layers. Changes in ? and SR% down the bog plateau (BP), bog margin (BM) and fen lagg (FL) cores in the Ryggmossen mire indicates that the sphagnum acid bound into the peat is being degraded in the unsaturated and seasonally-saturated layers. There is then a stabilisation of Sphagnum-derived phenols in the deepest horizons of the seasonally-saturated layer and into the permanently-saturated layer. These results suggest that "bound" sphagnum acid will be stabilised in peatlands shifting to a wetter and more variable precipitation regime whereas it will be gradually stripped away (e.g. by hydrolysis/enzymatic activity) in surficial peats shifting to a drier climate, such that any subsequent rewetting of the peat could lead to anaerobic hydrolysis and fermentation of the newly exposed carbohydrates. This highlights the sensitivity of Sphagnum surficial peats to climate-induced changes in water levels albeit there may be differences in the extent of degradation along the bog-fen gradient.

Abbott, Geoffrey D.; Swain, Eleanor Y.; Muhammad, Aminu B.; Allton, Kathryn; Belyea, Lisa R.; Laing, Christopher G.; Cowie, Greg L.

2013-04-01

149

Daily fluctuation of plasma levels with conventional and controlled-release carbamazepine: correlation with adverse effects.  

Science.gov (United States)

The pharmacokinetics, tolerability, and efficacy of carbamazepine (CBZ) and the pharmacokinetics of carbamazepine-10, 11-epoxide (CBZE) were studied after chronic administration of a conventional tablet formation or of the controlled-release (CR) formulation of CBZ 400 mg (Tegretol 400) to 20 patients with epilepsy treated with carbamazepine and complaining of intermittent adverse effects. To compare the two formulations at the same doses and dose schedules, the study design had to be open, within-patient, with an initial 4 week period to individually adjust the dosage schedule with conventional CBZ followed by a 4 week period in which the CR formulation was substituted for conventional CBZ at the same daily dose and given by the same schedule. A further 4 week period was also studied to evaluate the same dosage of the CR formulation but given b.i.d. In this latter period six patients required an increase in dosage (200 mg/day). Before the beginning of the study and at the end of each period seizure frequency and tolerability were assessed. Tolerability was estimated with a specifically prepared scale that assesses the main items and with an overall rating scale. At the end of each treatment period, serum levels of CBZ and CBZE were determined at various times over a 10 h period. Peak plasma concentrations (Cmax) of CBZ and the fluctuation index (FI) were significantly lower for the CR CBZ, although minimal and mean plasma concentrations were the same in the three periods of the study.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8195585

Bareggi, S R; Tata, M R; Guizzaro, A; Pirola, R; Parisi, A; Monza, C G

1994-01-01

150

Paleoclimatic significance of lake level fluctuations in the Lahontan Basin. [Pyramid Lake, Nevada  

Energy Technology Data Exchange (ETDEWEB)

An energy flux balance model has been developed which treats evaporation as a function of air temperature, surface water temperature, precipitable water aloft, the amount, height, and type of sky cover, and the optical air mass. The model has been used to estimate the mean historical evaporation rate for Pyramid Lake, Nevada, using as input climatic data from the Reno area averaged over the period 1950 to 1975. Estimated and measured values of the mean annual evaporation rate were found to be in good agreement. The model was used to simulate changes in the level, the surface area and the volume of paleo Lake Lahontan. In particular, possible climatic states responsible for past high stands (1270 and 1330 m) were investigated. A conservative range of discharge values was used in the calculations. Results of the simulations indicate the fundamental importance of sky cover in the creation and destruction of large lake systems.

Benson, L.V.

1980-08-01

151

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

152

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

153

Mitigation of radon levels in water  

Energy Technology Data Exchange (ETDEWEB)

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 [sup 222]Rn 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 [sup 222]Rn in potable water should not exceed 300 pCi/l. According to the EPA, well waters found to have concentration of [sup 222]Rn 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 [sup 222]Rn concentration have been investigated in the laboratory to determine their effectiveness for removing [sup 222]Rn from well waters.

Abulfaraj, W.; Mamoon, A.M.; Sahsah, M. (King Abdulaziz Univ., Jeddah (Saudi Arabia))

1993-01-01

154

Effects of basin type on coastal plain-shelf-slope systems during base-level fluctuations: An experimental approach  

Energy Technology Data Exchange (ETDEWEB)

Sequence stratigraphic models emphasize the importance of basin type on the reactions of coastal plain-shelf-slope systems to base-level changes. A series of experiments were performed in a 4.5 m by 7 m flume to examine the effects of a passive margin basin with a shelf/slope break versus a ramp margin basin on coastal plain-shelf-slope deposits that result from base-level fluctuations. Results indicate that basin type has a strong influence on the erosional features and deposits that develop in response to base-level fluctuations. Fluctuations that occur along a shelf/slope break margin result in well-defined, deeply incised valleys, which develop early in lowstand time and have low width:depth ratios. Rivers may incise into and deposit over outer-middle shelf deposits of the previous highstand. Late lowstand deposits are coarser grained than early lowstand deposits and include fine- and coarse-grained slope and basin floor fans. During subsequent base-level rise early transgressive deposits are confined to incised valleys. Fluctuations along a ramp margin result in shallow, wide incised valleys with high width:depth ratios, which develop late in lowstand time. Incision occurs into shelf deltaic deposits and these are overlain by valley fill deposits. Deposits of the lowstand systems tract do not coarsen upward significantly and contain only sand-rich, small, thin delta front fan deposits. During subsequent base-level rise transgressive deposits are not confined to incised valleys. Transgressive deposition within the valleys occurs over a short time interval and is followed closely by flooding of the adjacent shelf.

Wood, L.J. (Colorado State Univ., Fort Collins (United States))

1991-03-01

155

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

156

Observing plants dealing with soil water stress: Daily soil moisture fluctuations derived from polymer tensiometers  

Science.gov (United States)

Periods of soil water deficit often occur within a plant's life cycle, even in temperate deciduous and rain forests (Wilson et al. 2001, Grace 1999). Various experiments have shown that roots are able to sense the distribution of water in the soil, and produce signals that trigger changes in leaf expansion rate and stomatal conductance (Blackman and Davies 1985, Gollan et al. 1986, Gowing et al. 1990 Davies and Zhang 1991, Mansfield and De Silva 1994, Sadras and Milroy 1996). Partitioning of water and air in the soil, solute distribution in soil water, water flow through the soil, and water availability for plants can be determined according to the distribution of the soil water potential (e.g. Schröder et al. 2013, Kool et al. 2014). Understanding plant water uptake under dry conditions has been compromised by hydrological instrumentation with low accuracy in dry soils due to signal attenuation, or a compromised measurement range (Whalley et al. 2013). Development of polymer tensiometers makes it possible to study the soil water potential over a range meaningful for studying plant responses to water stress (Bakker et al. 2007, Van der Ploeg et al. 2008, 2010). Polymer tensiometer data obtained from a lysimeter experiment (Van der Ploeg et al. 2008) were used to analyse day-night fluctuations of soil moisture in the vicinity of maize roots. To do so, three polymer tensiometers placed in the middle of the lysimeter from a control, dry and very dry treatment (one lysimeter per treatment) were used to calculate water content changes over 12 hours. These 12 hours corresponded with the operation of the growing light. Soil water potential measurements in the hour before the growing light was turned on or off were averaged. The averaged value was used as input for the van Genuchten (1980) model. Parameters for the model were obtained from laboratory determination of water retention, with a separate model parameterization for each lysimeter setup. Results show daily fluctuations in water content changes, with both root water uptake and root water excretion. The magnitude of the water content change was in the same order for all treatments, thus suggesting compensatory uptake. References Bakker G, Van der Ploeg MJ, de Rooij GH, Hoogendam CW, Gooren HPA, Huiskes C, Koopal LK and Kruidhof H. New polymer tensiometers: Measuring matric pressures down to the wilting point. Vadose Zone J. 6: 196-202, 2007. Blackman PG and Davies WJ. Root to shoot communication in maize plants of the effects of soil drying. J. Exp. Bot. 36: 39-48, 1985. Davies WJ and Zhang J. Root signals and the regulation of growth and development of plants in drying soil. Annu. Rev. Plant Physiol. Plant Mol. Biol. 42: 55-76, 1991. Gollan T, Passioura JB and Munns R. Soil water status affects the stomatal conductance of fully turgid wheat and sunflower leafs. Aust. J. Plant Physiol. 13: 459-464, 1986. Gowing DJG, Davies WJ and Jones HG. A Positive Root-sourced Signal as an Indicator of Soil Drying in Apple, Malus x domestica Borkh. J. Exp. Bot. 41: 1535-1540, 1990. Grace J. Environmental controls of gas exchange in tropical rain forests. In: Press, M.C, J.D. Scholes and M.G. Barker (ed.). Physiological plant ecology: the 39th Symposium of the British Ecological Society. Blackwell Science, United Kingdom, 1999. Kool D, Agam N, Lazarovitch N, Heitman JL, Sauer TJ, Ben-Gal A. A review of approaches for evapotranspiration partitioning. Agricultural and Forest Meteorology 184: 56- 70, 2014. Mansfield TA and De Silva DLR. Sensory systems in the roots of plants and their role in controlling stomatal function in the leaves. Physiol. Chem. Phys. & Med. 26: 89-99, 1994. Sadras VO and Milroy SP. Soil-water thresholds for the responses of leaf expansion and gas exchange: a review. Field Crops Res. 47: 253-266, 1996. Schröder N, Lazarovitch N, Vanderborcht J, Vereecken H, Javaux M. Linking transpiration reduction to rhizosphere salinity using a 3D coupled soil-plant model. Plant Soil 2013, doi: 10.1007/s11104-013-1990-8 Van der Ploeg MJ, Gooren HPA, Bakker G and de Rooij GH.

van der Ploeg, Martine; de Rooij, Gerrit

2014-05-01

157

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.

2010-05-01

158

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

159

On the applicability of available methods for estimating daily evapotranspiration by using diurnal water table fluctuations  

Science.gov (United States)

Shallow groundwater is mainly discharged by phreatophytes in many riparian ecosystems of arid and semiarid environment, while estimation of groundwater evapotranspiration (ETG) in these regions still remains a challenge for regional water resources assessment. Since White (1932) provided a method for estimating ETG based on diurnal groundwater dynamics, a number of modifications of White method were developed for calculating ETG; however, a major source of uncertainty in all these methods is associated with estimates groundwater recovery rate. In this study, we developed a criterion of quasi-steady conditions of groundwater evapotranspiration processes, which based on a coupled consideration of the water and energy balance. This criterion was tested by using the one dimensional saturated-unsaturated flow model, and use of these guidelines with the White method approaches could enable minimize uncertainty in estimating ETG. The developed methodology is illustrated by estimation of ETG rate using high-accuracy monitoring data of groundwater fluctuations for Goby environments in a typical arid region of northwest China.

Wang, P.; Pozdniakov, S. P.; Lekhov, M.; Yu, J.

2012-12-01

160

Contribution of climate-driven change in continental water storage to recent sea-level rise  

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Using a global model of continental water balance, forced by interannual variations in precipitation and near-surface atmospheric temperature for the period 1981–1998, we estimate the sea-level changes associated with climate-driven changes in storage of water as snowpack, soil water, and ground water; storage in ice sheets and large lakes is not considered. The 1981–1998 trend is estimated to be 0.12 mm/yr, and substantial interannual fluctuations are inferred; for 1993–1998, the trend...

Milly, P. C. D.; Cazenave, A.; Gennero, C.

2003-01-01

 
 
 
 
161

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 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. PMID:24852545

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

2014-05-21

162

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 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.

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

2014-05-01

163

Fluctuations of the Caspian Sea level in the quasi-two-year and 11-year cycles of solar activity  

Energy Technology Data Exchange (ETDEWEB)

Fluctuations of the Caspian Sea level due to dynamics of solar activity in its quasi-two-year and 11-year cycles, as well as to the influence of the 22-to 23-year magnetic cycle are analyzed. Perturbation of the geomagnetic field and the atmospheric circulation are regarded as a transmitting mechanism of the Sun`s influence on the Earth`s hydrosphere.

Nuzhdina, M.A. [Astronomical Observatory, Kiev (Ukraine)

1995-07-01

164

Hydraulic interactions between fractures and bedding planes in a carbonate aquifer studied by means of experimentally induced water-table fluctuations (Coaraze experimental site, southeastern France)  

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In aquifers with variable permeability, the water exchanges between high and low permeability regions are controlled by the hydraulic head gradient. Past studies have addressed this problem mainly considering steadystate hydraulic conditions. To study such exchanges during water-table fluctuations, a spring was equipped with a water-gate that creates 10-meter artificial fluctuations of the water table. The water exchanges are discussed with respect to hydrochemical and pressure measurements i...

2009-01-01

165

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

2004-03-01

166

The effect of wind speed fluctuations on the performance of a wind-powered membrane system for brackish water desalination  

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A wind-powered reverse osmosis membrane (wind-membrane) system without energy storage was tested using synthetic brackish water (2750 and 5500 mg/L NaCl) over a range of simulated wind speeds under both steady-state and fluctuating conditions. The parameters varied were: i) average wind speed from 3.7 (system start-up) to 8.7 m/s; ii) wind turbulence intensity from 0.0 (steady-state conditions) to 0.6 (extreme fluctuations); and iii) period of oscillation from 15 to 90 s. With ...

Park, Gavin L.; Scha?fer, Andrea; Richards, Bryce S.

2011-01-01

167

Soil- and plant- water uptake in saline environments and their consequences to plant adaptation in fluctuating climates  

Science.gov (United States)

Ecological processes determining plant colonization are quite peculiar and competition among different species is governed by a set of unique adaptations to stress conditions caused by drought, hypoxic or hyper-saline conditions. These adaptations and possible positive feedbacks often lead to the formation of patterns of vegetation colonization and spatial heterogeneity (zonation), and play a primary role in the stabilization of sediments. It is these issues that frame the scope of this study. The main objective of this work is to track one of the fundamental pathways between plant adaptation (quantified in terms of physiological and ecological attributes such as leaf area or root density profile) and feedbacks (quantified by plant-mediated alterations to water availability and salinity levels): root water uptake. Because root-water uptake is the main conduit connecting transpiring leaves to reservoirs of soil water, the means by which salinity modifies the processes governing its two end-points and any two-way interactions between them serves as a logical starting point. Salinity effects on leaf transpiration and photosynthesis are first explored via stomatal optimization principles that maximize carbon gain at a given water loss for autonomous leaves. Salinity directly affects leaf physiological attributes such as mesophyll conductance and photosynthetic parameters and hence over-all conductance to transpiration as well as different strategies to cope with the high salinity (e.g. through salt seclusion, compartmentation and osmotic adjustments). A coupled model of subsurface flow based on a modified Richards’ equation that accounts for the effects of increasing salinity, anaerobic conditions, water stress and compensation factors is developed. Plant water uptake is considered as a soil moisture sink term with a potential rate dictated by the carbon demands of the leaves, and an actual rate that accounts for both - hydraulic and salinity limitations. Using this model, the root distribution shape function (e.g. constant, linear, exponential, or power-law) that optimally satisfies these carbon demands and simultaneous hydraulic and salinity constraints of the soil-root system is then determined for a set of forcing variables and boundary conditions. Adaptation speeds and feedback strengths to future climatic fluctuations are explored as ‘departures’ from this equilibrium profile state.

Volpe, V.; Albertson, J. D.; Katul, G. G.; Marani, M.

2010-12-01

168

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

169

Fluctuating modal interference characteristics in shallow water with a seasonal thermocline  

Science.gov (United States)

In temporal and spatial array signal processing, especially for a large-aperture horizontal line arrays (HLA), degradation of the horizontal longitudinal correlation of signals among different hydrophones due to multipath dispersion commonly limits the array gain. It is therefore important to reduce or cancel the dispersion effects between hydrophone signals. Modal filtering is one of the available approaches to utilize the interference structure of sound fields and to improve the signal processing performance. In this paper, modal filtering based on a warping transform from a nonlinear time-frequency signal to a linear one is used to separate modes from a broadband signal. Then, the contributions of modes to interference striation are determined in order to explain the difference of the waveguide invariant between modes. The variability of waveguide invariants in fluctuating shallow water with a strong seasonal thermocline and internal waves is examined experimentally. The experiment was performed with a sea-floor located HLA and a fixed sound source transmitting 160-250 Hz linear frequency modulated (LFM) signals, which were observed over a long period of time. The contribution of low-and high-order modes to interference patterns explains the variability of waveguide invariants in the measured data.

Zhou, Shihong; Niu, Haiqiang; Ren, Yun; He, Li

2012-11-01

170

The stratigraphic record of the quaternary sea level fluctuations and the impact of the post-glacial sea level rise (Termination I) in the Adriatic basin (Mediterranean sea)  

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The modern stratigraphy of clastic continental margins is the result of the interaction between several geological processes acting on different time scales, among which sea level oscillations, sediment supply fluctuations and local tectonics are the main mechanisms. During the past three years my PhD was focused on understanding the impact of each of these process in the deposition of the central and northern Adriatic sedimentary successions, with the aim of reconstructing and quantifying th...

Maselli, Vittorio

2011-01-01

171

A Control Method of Charging Level for Battery Energy Storage System for Smoothing Output Fluctuation of Wind Power Generation  

Science.gov (United States)

This paper proposes a new control method for maintaining a charging level for a battery energy storage system (BESS) coupled with a wind farm (WF) to stabilize WF output. Since output of wind power varies with wind speed, operation of a power system will be influenced if a large number of WFs are interconnected to the power system. The authors have made a research project to conduct demonstration tests of a BESS coupled with a WF to smooth out short-term fluctuations in WF output. In operating the BESS, it is essential to maintain a charging level of a battery within a proper range. This paper thus proposes a new control method called “State-Of-Charge Feedback Control (SOC-FB control)” to stabilize the charging level. In this paper, characteristics of the SOC-FB control are discussed through theoretical analyses with its transfer functions as well as through simulation studies. Analyses on the transfer functions show that the SOC-FB control is effective to stabilize the charging level of the battery. Sensitivity of the control parameters of the SOC-FB control is examined from the viewpoints of the performance of smoothing the output fluctuations and stabilizing the charging level. The performance of the BESS is also examined through simulations using actual WF output data. The results show that charging level is kept within its proper range without deteriorating the smoothing performance by adopting the SOC-FB control, while the charging level goes beyond its proper range without the SOC-FB control. These results clarified the effectiveness of the SOC-FB control to maintain the charging level of the battery. Results of the sensitivity of the control parameters are considered useful to select proper parameters for the control.

Yoshimoto, Katsuhisa; Nanahara, Toshiya; Koshimizu, Gentaro

172

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

Science.gov (United States)

On 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.

2014-01-01

173

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

174

Millennial/submillennial-scale sea-level fluctuations in western Mediterranean during the second highstand of MIS 5e  

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This paper investigates a series of small-scale, short-lived fluctuations of sea level registered in a prograding barrier spit that grew during theMIS 5e. This interglacial includes three highstands (Zazo et al., 2003) and we focus on the second highstand, of assumed duration ?10 2 ka, given that UeTh ages do not provide more accurate data. Geometry and 3D architecture of beach facies, and thin-section petrography were used to investigate eight exposed offlapping subunits separ...

Dabrio, Cristino J.; Zazo Carden?a, Caridad; Cabero Del Ri?o, Ana; Goy Goy, Jose? Luis; Bardaji? Azca?rate, Teresa; Hillaire-marcel, Claude; Gonza?lez Delgado, Jose? A?ngel; Lario Go?mez, Javier; Silva Barroso, Pablo Gabriel; Borja, Francisco; Garci?a Bla?zquez, Ana Mari?a

2011-01-01

175

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

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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

176

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.

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

2014-01-01

177

Effect of Different Soil Water Levels on Production and Abscission of Reproductive Organs of Soybean under High Temperature  

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An experiment was conducted during summer 1999 in and out sides of a glasshouse to evaluate the effect of different soil water levels on growth, physiological aspects and, production and abscission of flowers and pods of soybean. Three stress treatments were imposed by 40, 60 and 80% reduced water from flower initiation to maturity in the glasshouse. Two well-watered unstressed controls were also included for comparison of performances in and out sides of the glasshouse. Fluctuation in air te...

Begum Samsun Nahar; Takeshi Ikeda

2001-01-01

178

Correlation between central corneal thickness and intraocular pressure peak and fluctuation during the water drinking test in glaucoma patients  

Directory of Open Access Journals (Sweden)

Full Text Available OBJECTIVE: To investigate the correlation between central corneal thickness and outflow facility assessed by intraocular pressure peak and fluctuation during the water drinking test. METHODS: Fifty-five newly diagnosed primary open-angle glaucoma patients submitted to central corneal thickness measurements and water drinking test were enrolled in this retrospective study.;. Patients were divided into three groups according to their central corneal thickness. Pearson's Correlation test was performed in the groups with lower and higher pachymetric values. RESULTS: The mean age was 65,65 ± 28,28 years; 63,63% were female and 52,72% were caucasian. The mean central corneal thickness was 544,32 ± 36,86 µm, and the mean baseline intraocular pressure was 23,36 ± 6,26 mmHg. During the water drinking test, the mean intraocular pressure peak and mean intraocular pressure fluctuation were 30,43 ± 8,13 mmHg and 31,46 ± 18,46%, respectively. No relevant correlation was detected between the central corneal thickness and the intraocular pressure peak (r² = 0,021 or between the central corneal thickness and the intraocular pressure fluctuation (r² = 0,011. Group 1 presented a mean central corneal thickness of 505,81 ± 13,86 µm, and Group 3 was 583,55 ± 27,87 µm (p = 0,001. The mean intraocular pressure peak was 31,05 ± 9,05 mmHg and 27,83 ± 4,92 mmHg in Group 1 and in Group 3, respectively (p = 0,193. The difference of intraocular pressure fluctuation was not statistically significant between Group 1 (mean 28,47±16,25% and Group3 (mean 33,27 ± 21,27% (p = 0,43. CONCLUSION: In our case series, no correlation was found between central corneal thickness and water drinkingtest results.

Rafael Lacerda Furlanetto

2010-01-01

179

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

International Nuclear Information System (INIS)

From 1985 through 1995, a water-level network that consists of 28 wells for monitoring 36 depth intervals has been maintained in the Yucca Mountain area. The network includes wells that were measured manually, approximately monthly, and/or measured hourly with a transducer/data logger system. Manual water-level measurements were made with either calibrated steel tapes or single or multiconductor-cable units. All wells monitor water levels in Tertiary volcanic rocks, except one that monitors water levels in Paleozoic carbonate rocks. Annual mean water-level altitudes for all wells for the period 1985-95 ranged from 727.93 to 1,034.60 meters. The maximum range in water-level change between monthly measurements and/or monthly mean values was 12.22 meters in well USW H-3 lower interval, and the minimum range was 0.31 meter in wells UE-25 b-1 upper interval, and J-11. In 31 of the 36 depth intervals monitored, the range of water-level change was less than 1 meter. The range of standard deviation of all depth interval measurements for all wells that were monitored was 0.053 to 3.098 meters. No seasonal water-level trends were detected in any of the wells, and regional ground-water withdrawals did not appear to cause water-level changes. Most annual water-level fluctuations can be attributed to barometric and Earth-tide changes. Regional earthquakes, which occurred on June 28--29, 1992, might have simultaneously affected the water level 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

180

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

 
 
 
 
181

a Coupled Soil-Plant Approach to Modeling Convective Rainfall Initiation Induced by Water Table Fluctuation  

Science.gov (United States)

To investigate the feedback mechanisms between soil moisture dynamics and predisposition to convective rainfall, a soil-plant-atmosphere model is developed that couples the three-dimensional soil-vegetation water dynamics with an atmospheric boundary layer (ABL) slab model. The predisposition state is surrogated to the crossing of the modeled lifting condensation level and boundary layer heights. Such a predisposition is interpreted as a necessary but not sufficient condition for the initiation of convective rainfall. The model is applied to a loblolly pine plantation in the Southeastern US and used to investigate the role of vegetation on boundary layer-cloud formation. Numerical simulations highlight the feedback mechanisms occurring in the soil-plant-atmosphere continuum demonstrating that changes in the soil and plant compartments (e.g. water table drawdown, LAI decrease) impact the probability of convective rainfall occurrences.

Bonetti, S.; Manoli, G.; domec, J.; Putti, M.; Marani, M.; Katul, G. G.

2013-12-01

182

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

Energy Technology Data Exchange (ETDEWEB)

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.

Whelan, J.F.; Moscati, R.J.; Marshall, B.D [Geological Survey, Denver, CO (United States). Yucca Mountain Project Branch; Roedder, E. [Harvard Univ., Cambridge, MA (United States)

1997-12-01

183

IVF Performance of Women Who Have Fluctuating Early Follicular FSH Levels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objectives: The aim was to evaluate whether women who have early follicular follicle-stimulating hormone (FSH) levels >12 mIU/ml have reduced response to follicular stimulation for in vitro fertilization (IVF) in a following month, in spite of normal FSH levels.

Lass, A.; Gerrard, A.; Abusheikha, N.; Akagbosu, F.; Brinsden, P.

2000-01-01

184

Water balance of Lake Tana and its sensitivity to fluctuations in rainfall, Blue Nile basin, Ethiopia  

Science.gov (United States)

The annual water budget of Lake Tana is determined from estimates of runoff, rainfall on the lake, measured outflow and empirically determined evaporation. Simulation of lake level variation (1960-1992) has been conducted through modeling at a monthly time step. Despite the ±20% rainfall variations in the Blue Nile basin in the last 50 years, the lake level remained regular. A preliminary analysis of the sensitivity of level and outflow of the lake suggests that they are controlled more by variation in rainfall than by basin-scale forcing induced by human activities. The analysis shows that a drastic (40-45%) and sustained (7-8 years) rainfall reduction is required to change the lake from out flowing to terminal (cessation of outflow). However, the outflow from the lake shows significant variation responding to the rainfall variations. Unlike the terminal lakes in the Ethiopian rift valley or the other large lakes of Tropical Africa, at its present hydrologic condition, the Lake Tana level is less sensitive to rainfall variation and changes in catchment characteristics.

Kebede, S.; Travi, Y.; Alemayehu, T.; Marc, V.

2006-01-01

185

Variance and spectra of fluorescence-intensity fluctuations from two-level atoms in a phase-diffusing field  

International Nuclear Information System (INIS)

We have measured the variance in fluorescence intensity and the spectrum of those fluctuations for two-level atoms in a phase-diffusing laser field. We compare our results with recent theoretical predictions that have been extended to include the effects of Doppler broadening and spatial variation of the laser intensity. Our study includes the effects of laser power, bandwidth, and shape (Lorentzian and non-Lorentzian) of the laser spectrum. At lower laser intensities, our measured variances versus detuning are in quantitative agreement with the theoretical predictions. At intensities above saturation, the variance is sensitive to inhomogeneities in the distribution of laser intensity in the interaction region, and only qualitative agreement is achieved. Asymmetries in the variance versus detuning resulting from correlated amplitude and phase noise have been observed. Spectra of the phase-noise-induced fluorescence-intensity fluctuations are shown to contain contributions from transients excited by the phase noise and are more sensitive to artifacts in the noise modulation process than the intensity spectrum of the laser field itself

1990-12-01

186

Variance and spectra of fluorescence-intensity fluctuations from two-level atoms in a phase-diffusing field  

Energy Technology Data Exchange (ETDEWEB)

We have measured the variance in fluorescence intensity and the spectrum of those fluctuations for two-level atoms in a phase-diffusing laser field. We compare our results with recent theoretical predictions that have been extended to include the effects of Doppler broadening and spatial variation of the laser intensity. Our study includes the effects of laser power, bandwidth, and shape (Lorentzian and non-Lorentzian) of the laser spectrum. At lower laser intensities, our measured variances versus detuning are in quantitative agreement with the theoretical predictions. At intensities above saturation, the variance is sensitive to inhomogeneities in the distribution of laser intensity in the interaction region, and only qualitative agreement is achieved. Asymmetries in the variance versus detuning resulting from correlated amplitude and phase noise have been observed. Spectra of the phase-noise-induced fluorescence-intensity fluctuations are shown to contain contributions from transients excited by the phase noise and are more sensitive to artifacts in the noise modulation process than the intensity spectrum of the laser field itself.

Anderson, M.H.; Jones, R.D.; Cooper, J.; Smith, S.J. (Joint Institute for Laboratory Astrophysics, University of Colorado, Boulder, CO (USA) National Institute of Standards and Technology, Boulder, CO (USA)); Elliott, D.S. (School of Electrical Engineering, Purdue University, West Lafayette, IN (USA)); Ritsch, H.; Zoller, P. (Institute for Theoretical Physics, University of Innsbruck, Innsbruck (Austria))

1990-12-01

187

Quantitative assessment of glacial fluctuations in the level of Lake Lisan, Dead Sea rift  

Science.gov (United States)

A quantitative understanding of climatic variations in the Levant during the last glacial cycle is needed to support archaeologists in assessing the drivers behind hominin migrations and cultural developments in this key region at the intersection between Africa and Europe. It will also foster a better understanding of the region's natural variability as context to projections of modern climate change. Detailed documentation of variations in the level of Lake Lisan - the lake that occupied the Dead Sea rift during the last glacial cycle - provides crucial climatic information for this region. Existing reconstructions suggest that Lake Lisan highstands during cold intervals of the last glacial cycle represent relatively humid conditions in the region, but these interpretations have remained predominantly qualitative. Here, I evaluate realistic ranges of the key climatological parameters that controlled lake level, based on the observed timing and amplitudes of lake-level variability. I infer that a mean precipitation rate over the wider catchment area of about 500 mm y-1, as proposed in the literature, would be consistent with observed lake levels if there was a concomitant 15-50% increase in wind speed during cold glacial stadials. This lends quantitative support to previous inferences of a notable increase in the intensity of Mediterranean (winter) storms during glacial periods, which tracked eastward into the Levant. In contrast to highstands during 'regular' stadials, lake level dropped during Heinrich Events. I demonstrate that this likely indicates a further intensification of the winds during those times.

Rohling, Eelco J.

2013-06-01

188

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.

189

Real Time Imaging of Quantum and Thermal Fluctuations: The Case of a Two-Level System  

Science.gov (United States)

A quantum system in contact with a heat bath undergoes quantum transitions between energy levels upon absorption or emission of energy quanta by the bath. These transitions remain virtual unless the energy of the system is measured repeatedly, even continuously in time. Isolating the two indispensable mechanisms in competition, we describe in a synthetic way the main physical features of thermally activated quantum jumps. Using classical tools of stochastic analysis, we compute in the case of a two-level system the complete statistics of jumps and transition times in the limit when the typical measurement time is small compared to the thermal relaxation time. The emerging picture is that quantum trajectories are similar to those of a classical particle in a noisy environment, subject to transitions à la Kramer in a multi-well landscape, but with a large multiplicative noise.

Bauer, Michel; Bernard, Denis

2014-03-01

190

Real Time Imaging of Quantum and Thermal Fluctuations: The Case of a Two-Level System  

Science.gov (United States)

A quantum system in contact with a heat bath undergoes quantum transitions between energy levels upon absorption or emission of energy quanta by the bath. These transitions remain virtual unless the energy of the system is measured repeatedly, even continuously in time. Isolating the two indispensable mechanisms in competition, we describe in a synthetic way the main physical features of thermally activated quantum jumps. Using classical tools of stochastic analysis, we compute in the case of a two-level system the complete statistics of jumps and transition times in the limit when the typical measurement time is small compared to the thermal relaxation time. The emerging picture is that quantum trajectories are similar to those of a classical particle in a noisy environment, subject to transitions à la Kramer in a multi-well landscape, but with a large multiplicative noise.

Bauer, Michel; Bernard, Denis

2014-06-01

191

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

192

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

193

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

194

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

195

Groundwater Evapotranspiration from Diurnal Water Table Fluctuation: a Modified White Based Method Using Drainable and Fillable Porosity  

Science.gov (United States)

In shallow unconfined aquifers, the water table usually shows a distinct diurnal fluctuation pattern corresponding to the twenty-four hour solar radiation cycle. This diurnal water table fluctuation (DWTF) signal can be used to estimate the groundwater evapotranspiration (ETg) by vegetation, a method known as the White [1932] method. Water table fluctuations in shallow phreatic aquifers is controlled by two distinct storage parameters, drainable porosity (or specific yield) and the fillable porosity. Yet, it is implicitly assumed in most studies that these two parameters are equal, unless hysteresis effect is considered. The White based method available in the literature is also based on a single drainable porosity parameter to estimate the ETg. In this study, we present a modification of the White based method to estimate ETg from DWTF using separate drainable (?d) and fillable porosity (?f) parameters. Separate analytical expressions based on successive steady state moisture profiles are used to estimate ?d and ?f, instead of the commonly employed hydrostatic moisture profile approach. The modified method is then applied to estimate ETg using the DWTF data observed in a field in northeast Florida and the results are compared with ET estimations from the standard Penman-Monteith equation. It is found that the modified method resulted in significantly better estimates of ETg than the previously available method that used only a single, hydrostatic-moisture-profile based ?d. Furthermore, the modified method is also used to estimate ETg even during rainfall events which produced significantly better estimates of ETg as compared to the single ?d parameter method.

Acharya, S.; Mylavarapu, R.; Jawitz, J. W.

2012-12-01

196

Effects of water level regulation on littoral zone of lakes Konnivesi and Ruotsalainen  

International Nuclear Information System (INIS)

Measures to develop an ecologically based regulation practice for the lakes Ruotsalainen and Konnivesi which belong to the Kymijoki watercourse, were undertaken in 1995, when the intermunicipal board for the Heinola health care centre and Myllykoski Oy proposed that the regulation licence should re-evaluated. The purpose of this study, which is part of the overall development project, was to assess the ecological impacts of regulation on the littoral zones of these lakes. More specifically, the study focussed on the changes in the ecology of the littoral zone due to the water level fluctuation. The littoral vegetation of lake Konnivesi reflects the improvement of water quality over the past fifteen years. The species indicative of eutrophication have mostly disappeared. The vegetation of the uppermost littoral zone has stabilised, and the effect of wave erosion is small Ice pressure on the bottom has hardly any impact on the plants sensitive to the ice scouring effect, because the ice-covered zone has actually been reduced in size consequent to the regulation. Owing to the small range of water level fluctuation during the open water period, the uppermost littoral zone remains very narrow, which restricts the spreading of especially helophytic vegetation. The narrow littoral zone impairs the development of the normal zonal biotope in many places and simultaneously prevents diverse increase of littoral biota. The aim of the ecological regulation practice proposed for Konnivesi is to ensure a water level favourable for pike spawning It is further proposed that the water level should decline by 25 cm during the open water period following the flood peak. This would help to widen the littoral zone suited to helophytic vegetation and to increase the vegetational diversity of especially gently sloping shores. (orig.) 12 refs

1997-01-01

197

Rate of bentazone transformation in four layers of a humic sandy soil profile with fluctuating water table  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The rate of transformation of a pesticide as a function of the depth in the soil is needed as an input into computations on the risk of residues leaching to groundwater. The herbicide bentazone was incubated at 15 °C in soil materials derived from four layers at depths of up to 2.5 m in a humic sandy soil profile with a fluctuating water table (0.8 to 1.4 m), while simulating the redox conditions existing in the field. Gamma-irradiation experiments indicated that bentazone is mainly transfor...

Leistra, M.; Smelt, J. H.; Matser, A. M.; Bogte, J. J.; Pas, L. J. T.

2001-01-01

198

Late holocene fluctuations in the rate of sea-level rise in the Delaware Bay  

Energy Technology Data Exchange (ETDEWEB)

Over 40 cores have been obtained along the tidal Leipsic River, a tributary of Delaware Bay. In addition to the expected general pattern of Holocene transgressive submergence, the cores also reveal two abrupt transgressive facies transitions where subtidal muds overlie tidal wetland deposits. These abrupt facies transitions have been dated by radiocarbon analyses at approximately 3,000 and 1,800 years BP. 13 cores obtained by Fletcher et al. (in press) from Wolfe Glade, a tidal wetland on the southeastern coast of Delaware Bay, reveal at least 5 transgressive episodes. The younger 2 episodes have been dated at approximately 3,250 and 1,800 years BP. The youngest transgressive episode inferred from Wolfe Glade and the Leipsic River correlate with a major transgression of the sea recognized by Meyerson (1972) in wetland deposits of the New Jersey shore of Delaware Bay. This widely separated but temporally correlative transgressive facies transition suggests the occurrence of a major regional event. Because other mechanisms (autocompaction, rapid subsidence, lateral erosion by migration of tidal streams, and reduced sediment supply) are less likely, the authors propose that the local rate of sea-level rise abruptly increased approximately 1,800 years ago in Delaware Bay. Transgressive facies transitions observed at the Leipsic River and at Wolfe Glade also suggest the possibility that an additional acceleration in the rate of sea-level rise occurred approximately 3,000 years ago.

John, S.; Pizzuto, J.S. (Univ. of Delaware, Newark, DE (United States). Dept. of Geology); Fletcher, C.H. III (Univ. of Hawaii, Honolulu, HI (United States). Dept. of Geology)

1993-03-01

199

Analyzing sound speed fluctuations in shallow water from group-velocity versus phase-velocity data representation.  

Science.gov (United States)

Data collected over more than eight consecutive hours between two source-receiver arrays in a shallow water environment are analyzed through the physics of the waveguide invariant. In particular, the use of vertical arrays on both the source and receiver sides provides source and receiver angles in addition to travel-times associated with a set of eigenray paths in the waveguide. From the travel-times and the source-receiver angles, the eigenrays are projected into a group-velocity versus phase-velocity (Vg-Vp) plot for each acquisition. The time evolution of the Vg-Vp representation over the 8.5-h long experiment is discussed. Group speed fluctuations observed for a set of eigenrays with turning points at different depths in the water column are compared to the Brunt-Va?isa?la? frequency. PMID:23556564

Roux, Philippe; Kuperman, W A; Cornuelle, Bruce D; Aulanier, Florian; Hodgkiss, W S; Song, Hee Chun

2013-04-01

200

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.

 
 
 
 
201

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

Directory of Open Access Journals (Sweden)

Full Text Available 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(OH2D3 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(OH2D3 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.

Gomes S.A.

2004-01-01

202

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

Directory of Open Access Journals (Sweden)

Full Text Available 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(OH2D3 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(OH2D3 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

2004-09-01

203

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

1998-01-01

204

Scaling properties of pH fluctuations in coastal waters of the English Channel: pH as a turbulent active scalar  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We consider here pH and temperature fluctuations in marine waters, recorded at fixed points using high resolution automatic devices. We analyze time series coming from 4 monitoring stations located along French coast: one station is situated in the coastal area off Boulogne-sur-mer (Eastern English Channel) and 3 stations in the Bay of Seine. All these pH time series reveal large fluctuations at all scales similar to turbulent temperature fluctuations. We compare the pH and temperature time s...

Zongo, S. B.; Schmitt, F. G.

2011-01-01

205

Inter-annual precipitation fluctuations alter the responses of above- and belowground biomass to water and N enrichment  

Science.gov (United States)

Water availability has profound effects on plant growth and productivity in temperate and semi-arid grasslands. However, it remains unclear how variation of inter-annual precipitation by extreme rainfall events will alter the aboveground and belowground responses of plants, and how these responses may be contingent on N availability. In this study, we examined the interactive effects of inter-annual precipitation variation and N addition on aboveground and live fine root biomass of a semi-arid grassland in northern China for two consecutive years (2007 and 2008). Inter-annual variation in precipitation resulting mainly from the occurrence of extreme rainfall events in 2008 significantly affected above- and belowground plant biomass responses to water addition. In addition, variation of inter-annual precipitation by this extreme rainfall event suppressed plant responses to nitrogen addition and reduced the interaction effects between water and nitrogen addition. These effects of inter-annual precipitation fluctuation could be attributed to the negative influence of the extreme rainfall event on soil N and water availability, ultimately reducing plant rainfall use efficiency and nitrogen use efficiency. In conclusion, our results suggest ecosystem responses to water and N enrichment could be altered by inter-annual variation of precipitation regime caused by the naturally occurring extreme rainfall events.

Kong, D. L.; Lü, X. T.; Jiang, L. L.; Wu, H. F.; Miao, Y.; Kardol, P.

2013-08-01

206

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

207

Analysis of ground-water levels and associated trends in Yucca Flat, Nevada Test Site, Nye County, Nevada, 1951-2003  

Science.gov (United States)

Almost 4,000 water-level measurements in 216 wells in the Yucca Flat area from 1951 to 2003 were quality assured and analyzed. An interpretative database was developed that describes water-level conditions for each water level measured in Yucca Flat. Multiple attributes were assigned to each water-level measurement in the database to describe the hydrologic conditions at the time of measurement. General quality, temporal variability, regional significance, and hydrologic conditions are attributed for each water-level measurement. The database also includes narratives that discuss the water-level history of each well. Water levels in 34 wells were analyzed for variability and for statistically significant trends. An attempt was made to identify the cause of many of the water-level fluctuations or trends. Potential causes include equilibration following well construction or development, pumping in the monitoring well, withdrawals from a nearby supply well, recharge from precipitation, earthquakes, underground nuclear tests, land subsidence, barometric pressure, and Earth tides. Some of the naturally occurring fluctuations in water levels may result from variations in recharge. The magnitude of the overall water-level change for these fluctuations generally is less than 2 feet. Long-term steady-state hydrographs for most of the wells open to carbonate rock have a very similar pattern. Carbonate-rock wells without the characteristic pattern are directly west of the Yucca and Topgallant faults in the southwestern part of Yucca Flat. Long-term steady-state hydrographs from wells open to volcanic tuffs or the Eleana confining unit have a distinctly different pattern from the general water-level pattern of the carbonate-rock aquifers. Anthropogenic water-level fluctuations were caused primarily by water withdrawals and nuclear testing. Nuclear tests affected water levels in many wells. Trends in these wells are attributed to test-cavity infilling or the effects of depressurization following nuclear testing. The magnitude of the overall water-level change for wells with anthropogenic trends can be large, ranging from several feet to hundreds of feet. Vertical water-level differences at 27 sites in Yucca Flat with multiple open intervals were compared. Large vertical differences were noted in volcanic rocks and in boreholes where water levels were affected by nuclear tests. Small vertical differences were noted within the carbonate-rock and valley-fill aquifers. Vertical hydraulic gradients generally are downward in volcanic rocks and from pre-Tertiary clastic rocks toward volcanic- or carbonate-rock units.

Fenelon, Joseph M.

2005-01-01

208

Analysis of Ground-Water Levels and Associated Trends in Yucca Flat, Nevada Test Site, Nye County, Nevada, 1951-2003  

Energy Technology Data Exchange (ETDEWEB)

Almost 4,000 water-level measurements in 216 wells in the Yucca Flat area from 1951 to 2003 were quality assured and analyzed. An interpretative database was developed that describes water-level conditions for each water level measured in Yucca Flat. Multiple attributes were assigned to each water-level measurement in the database to describe the hydrologic conditions at the time of measurement. General quality, temporal variability, regional significance, and hydrologic conditions are attributed for each water-level measurement. The database also includes narratives that discuss the water-level history of each well. Water levels in 34 wells were analyzed for variability and for statistically significant trends. An attempt was made to identify the cause of many of the water-level fluctuations or trends. Potential causes include equilibration following well construction or development, pumping in the monitoring well, withdrawals from a nearby supply well, recharge from precipitation, earthquakes, underground nuclear tests, land subsidence, barometric pressure, and Earth tides. Some of the naturally occurring fluctuations in water levels may result from variations in recharge. The magnitude of the overall water-level change for these fluctuations generally is less than 2 feet. Long-term steady-state hydrographs for most of the wells open to carbonate rock have a very similar pattern. Carbonate-rock wells without the characteristic pattern are directly west of the Yucca and Topgallant faults in the southwestern part of Yucca Flat. Long-term steady-state hydrographs from wells open to volcanic tuffs or the Eleana confining unit have a distinctly different pattern from the general water-level pattern of the carbonate-rock aquifers. Anthropogenic water-level fluctuations were caused primarily by water withdrawals and nuclear testing. Nuclear tests affected water levels in many wells. Trends in these wells are attributed to test-cavity infilling or the effects of depressurization following nuclear testing. The magnitude of the overall water-level change for wells with anthropogenic trends can be large, ranging from several feet to hundreds of feet. Vertical water-level differences at 27 sites in Yucca Flat with multiple open intervals were compared. Large vertical differences were noted in volcanic rocks and in boreholes where water levels were affected by nuclear tests. Small vertical differences were noted within the carbonate-rock and valley-fill aquifers. Vertical hydraulic gradients generally are downward in volcanic rocks and from pre-Tertiary clastic rocks toward volcanic- or carbonate-rock units.

J.M. Fenelon

2005-10-05

209

Controlling taste and odour levels in water  

Energy Technology Data Exchange (ETDEWEB)

Taste and odor of drinking water supplies act as indicator mechanisms, indicating increased degrees of biological activity, possible contamination of the supply, treatment inadequacies, or contamination of the distribution systems. Disinfection and coagulation are effective preventive measures. Taste and odor problems may arise even with the application of preventive measures, so protective and treatment techniques must be implemented. These include chlorination and activated carbon absorption. (1 photo, 3 references, 1 table)

Bowers, A.J.

1980-12-01

210

Fluctuations of the Caspian Sea level as an indicator of global climatic changes - using data from radiocarbon dating of sediments  

International Nuclear Information System (INIS)

Because of the large area of the basin water, the level of the Caspian Sea reflects the global change of climate of the Northern hemisphere. In order to reconstruct the paleoclimatic situation, samples were taken from ancient salt marshes, depressions and bars which form when the sea level has fallen significantly. Mollusc shells, peat, carbonates and organic matter were used for 14C dating. The data obtained demonstrate the relationship between the sea level and climatic changes. During cooling the sea level rises and vice versa. This relates to the long-period (13,000 y) as well as to the short-period (2,000-2,500 y) and to secular changes of the climate. (author)

1990-01-01

211

A siphon gage for monitoring surface-water levels  

Science.gov (United States)

A device that uses a siphon tube to establish a hydraulic connection between the bottom of an onshore standpipe and a point at the bottom of a water body was designed and tested for monitoring surface-water levels. Water is added to the standpipe to a level sufficient to drive a complete slug of water through the siphoning tube and to flush all air out of the system. The water levels in the standpipe and the water body equilibrate and provide a measurable static water surface in the standpipe. The siphon gage was designed to allow quick and accurate year-round measurements with minimal maintenance. Currently available devices for monitoring surface-water levels commonly involve time-consuming and costly installation and surveying, and the movement of reference points and the presence of ice cover in cold regions cause discontinuity and inaccuracy in the data collected. Installation and field testing of a siphon gage using 0.75-in-diameter polyethylene tubing at Ashumet Pond in Falmouth, Massachusetts, demonstrated that the siphon gage can provide long-term data with a field effort and accuracy equivalent to measurement of ground-water levels at an observation well.A device that uses a siphon tube to establish a hydraulic connection between the bottom of an onshore standpipe and a point at the bottom of a water body was designed and tested for monitoring surface-water levels. Water is added to the standpipe to a level sufficient to drive a complete slug of water through the siphoning tube and to flush all air out of the system. The water levels in the standpipe and the water body equilibrate and provide a measurable static water surface in the standpipe. The siphon gage was designed to allow quick and accurate year-round measurements with minimal maintenance. Currently available devices for monitoring surface-water levels commonly involve time-consuming and costly installation and surveying, and the movement of reference points and the presence of ice cover in cold regions cause discontinuity and inaccuracy in the data collected. Installation and field testing of a siphon gage using 0.75-in-diameter polyethylene tubing at Ashumet Pond in Falmouth, Massachusetts, demonstrated that the siphon gage can provide long-term data with a field effort and accuracy equivalent to measurement of ground-water levels at an observation well.

McCobb, T. D.; LeBlanc, D. R.; Socolow, R. S.

1999-01-01

212

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

213

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 h...

2010-01-01

214

Two-level system with a thermally fluctuating transfer matrix element: Application to the problem of DNA charge transfer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Charge transfer along the base-pair stack in DNA is modeled in terms of thermally-assisted tunneling between adjacent base pairs. Central to our approach is the notion that tunneling between fluctuating pairs is rate-limited by the requirement of their optimal alignment. We focus on this aspect of the process by modeling two adjacent base pairs in terms of a classical damped oscillator subject to thermal fluctuations as described by a Fokker-Planck equation. We find that the...

D Orsogna, Maria R.; Rudnick, Joseph

2002-01-01

215

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

216

Impact of groundwater levels on evaporation and water-vapor fluxes in highly saline soils  

Science.gov (United States)

In aquifers of arid and hyper-arid zones, such as those occurring in the Chilean Andes high plateau, it is important to determine both the quantity and location of water discharges at the temporal scales of interest to close the basin's water budget and thus, to manage the water resource properly. In zones where shallow aquifers are the main source of water, overexploitation of the water resource changes the dynamics of water, heat and solute transport in the vadose zone. As aquifers are exploited, fluctuations in depth to groundwater are exacerbated. These fluctuations modify both soil structure and evaporation from the ground, which is typically the most important discharge from the water budget and is very difficult to estimate. Therefore, a correct quantification of evaporation from these soils is essential to improve the accuracy of the water balance estimation. The objective of this study was to investigate the evaporation processes and water-vapor fluxes in a soil column filled with a saline soil from the Salar del Huasco basin, Chile. Water content, electrical conductivity and temperature at different depths in the soil profile were monitored to determine the liquid and vapor fluxes within the soil column. The results showed that evaporation is negligible when the groundwater table is deeper than 1 m. For shallower groundwater levels, evaporation increases in an exponential fashion reaching a value of 3 mm/day when the groundwater table is near the surface of the ground. These evaporation rates are on the same order of magnitude than the field measurements, but slightly lower due to the controlled conditions maintained in the laboratory. Isothermal fluid fluxes were predominant over the non-isothermal fluid and water vapor fluxes. The net flux for all the phreatic levels tested in the laboratory showed different behaviors, with ascending or descending flows as a consequence of changes in water content and temperature distribution within the soil. It was found that evaporation from bare soils occurs as a consequence of vapor transport due to the thermal gradients. This vapor transport was also influences by the salinity of the soil.

Munoz, J. F.; Hernández, M. F.; Braud, I.; Gironas, J. A.; Suarez, F. I.

2012-12-01

217

Magnetic fluctuations on TFTR  

International Nuclear Information System (INIS)

Data from magnetic pick-up loops (Mirnov coils), located on the wall inside the vacuum vessel of TFTR, are used for studying the edge magnetic fluctuations. Experiments, such as impurity injection, gas puffing, and plasma motion, dramatically affect the fluctuations measured by the coils. A quantitative study of the fluctuation levels during these experiments has been made. Results show that there are simple relations between the amount of impurities or gas injected and changes in the fluctuation levels. Spatial locations of the fluctuation modes have also been tentatively identified. Finally, different models were studied in order to explain the behavior and dependence of the fluctuations on the relevant parameters of the plasma. 7 refs., 12 figs

1988-01-01

218

WATER-LEVEL MONITOR FOR BOREWELL AND WATER TANK BASED ON GSM  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Now a days, home automation & remote control and monitoring systems have seen a rapid growth in terms of technology. Apparently there is no early warning system to monitor the tank water level and bore well water level when it has reached the critical level. In this paper we have provided water level monitoring in the tank as well as in the bore well. If the water level in a bore well drops below the threshold level for pumping its pump motor may get air locked or more burn out due to dry run...

2012-01-01

219

Regional and State Level Water Scarcity Report: Northeast United States  

Science.gov (United States)

There are an abundance of large-scale, coarse resolution global water scarcity studies, but the existing literature fails to address regional and state specific scarcity measures. Moreover, while environmental water requirements are an integral factor in the development and implementation of sustainable water management practices, only recently has this notion been introduced to water scarcity research. In this paper, we argue that developing a preliminary measure of water scarcity, at the regional and state levels, will allow for more informed policy development. The goal of this study is to generate a more comprehensive understanding of water scarcity in the Northeast, by gathering fine scale data, applying a consistent methodology to the calculation of a scarcity index, and analyzing the results to see relative trends in spatio-temporal water scarcity. Public supply, irrigation, rural, industrial and thermo-power withdrawals have been compiled from USGS state water use publications from 1950 to 1985. Using the WBMplus water model runoff data, state specific in-stream environmental water requirements were calculated using the accepted hydro-ecological methodology. Water scarcity was then calculated as a ratio of water withdrawals to total available water minus environmental flow requirements for the system. In so doing, this study generates a spatially explicit and temporally varying water scarcity indicator (WSI) for the Northeastern United States between 1950 and 2000 at the regional and state levels at a five-year time interval. Calculation of a spatial and temporal water scarcity indicator enabled us to identify regions and specific states that were: slightly exploited (WSI 1.0). The minimum environmental water requirements to maintain in-stream aquatic and riparian ecosystems for the Northeastern states ranged between 27.5 to 36.3 percent of the mean annual runoff within Vermont and Maryland, respectively. The regional WSI values ranged between 0.199 in 1950 and 0.512 in 1995, indicating increasing water scarcity over time as population and employment growth has placed greater demands on water resources. Additionally, our study revealed that in 1980, Massachusetts, Pennsylvania and New Jersey scarcity levels were 0.733, 0.790 and 0.857, respectively. Although the Northeastern United States is commonly perceived as a water rich region, moderate to heavily exploited levels of water stress were observed over the time period when a finer spatial scale is utilized. Water scarcity indicator values were disaggregated by state for each time period and illustrated using a series of maps. Additional descriptive statistics were used to elucidate the differences in water scarcity between states over time.

Nicoletti, C. K.; Lopez-Morales, C. A.; Hoover, J. H.; Voigt, B. G.; Vorosmarty, C. J.; Mohammed, I. N.

2010-12-01

220

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.)

1994-10-18

 
 
 
 
221

Levels of toxaphene congeners in fish from Danish waters  

DEFF Research Database (Denmark)

The levels of toxaphene congeners, in addition to PCB congeners and organochlorine pesticides, were determined in various fish samples from different Danish waters. While PCB-153 and p,p'-DDE show different levels depending on the fishing area, with highest levels in fish from the Western Baltic Sea, toxaphene was detected in all the samples investigated at a more constant level. The distribution of the three toxaphene congeners Parlar #26, #50 and #62 depends on the fishing area, with the Western Baltic Sea being different from the other waters by having almost equal levels of toxaphene congeners #26 and #50.

Fromberg, Arvid; Cederberg, Tommy Licht

2000-01-01

222

Holocene lake level fluctuations of a small alpine lake in the Qilian Mountains, NW China: a comparison of chironomid, ostracod, pollen and geochemistry data.  

Science.gov (United States)

A core of 14 m length was drilled in a small alpine lake in the Qilian Mountains, NW China. The lake Luanhaizi has a drainage area of about 30 km2 and is situated at an altitude of 3200 m which represents the altitude of the present regional upper timberline. Due to the small size of the open-basin lake (surface area about 1 km2) and the sharply outlined catchment area the lake is regarded as a very sensitively and rapidly responding ecosystem. Analyses of ostracod shells, head capsules of larval chironomids and pollen and spores were conducted and the organic and carbonate content (LOI), element concentrations and magnetic susceptibility of core samples determined. Ostracod taxa mainly comprise Candona candida, C. neglecta, C. rawsoni, Cyclocypris ovum, Cypridopsis vidua, Fabaeformiscandona caudata, F. danielopoli, F. hyalina, Herpetocypris chevreuxi, Heterocypris salina, Ilyocypris cf. bradyi, I. echinata, I. lacustris and Limnocythere inopinata. They may be used to distinguish periods of low lake levels corresponding to a dense cover of aquatic plants at the lake bottom from stages of higher lake levels and a corresponding decrease in macrophytes at the core site. Chironomid taxa belonging to Chironomus, Cladopelma, Glyptotendipes, Micropsectra, Paratanytarsus, Polypedilum, Psectrocladius and Tanytarsus further provide information on variations in benthic oxygen availability and lake level fluctuations. Several units of the core show high abundances of pollen and spores of higher aquatic and wetland plants and fungi (Cyperaceae, Hippuris, Myriophyllum and Glomus) indicating low lake levels. In contrast, algae such as Botryococcus, Pediastrum and Tetraedron were regarded to reflect higher water levels. Typha angustifolia-type, Typha latifolia, Alisma and Potamogeton were recorded in low abundances as well. The organic content of core samples averages 6 % displaying four alternating stages of distinct minima and maxima. Lowest values of about 1 % occur at the core base whereas the organic content rises to 16 % at maximum near the top. The carbonate content displays a similar pattern with strong shifts ranging from 3 to 31%. The results of the investigation of the sediment core from the alpine lake in the Qilian Mountains were presented and the validity of single proxies with respect to lake level changes discussed.

Mischke, S.; Herzschuh, U.

2003-04-01

223

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 an...

2012-01-01

224

Response of the Apodi-Mossoró estuary-incised valley system (NE Brazil) to sea-level fluctuations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study focuses on the Quaternary sea level changes in the Apodi-Mossoró Estuary and adjacent shelf, Northeastern Brazil, based on the analysis of high-resolution seismic profiles, integrated with echosounder, SRTM and satellite image data. We use these data to develop a relative stratigraphy. An incised-valley extending from the Apodi-Mossoró Estuary onto the shelf dominates the investigated area. In very shallow waters (down to 10 m depth) the channel lies mainly in a NW-SE direction, ...

Helenice Vital; Lima Furtado, Samia F.; Moab Praxedes Gomes

2010-01-01

225

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.

226

Two-level system with a thermally fluctuating transfer matrix element: Application to the problem of DNA charge transfer  

International Nuclear Information System (INIS)

Charge transfer along the base-pair stack in DNA is modeled in terms of thermally assisted tunneling between adjacent base pairs. The key element of the approach in this paper is the notion that this tunneling between base pairs that fluctuate significantly from their nominal orientation is rate limited by the requirement of optimal alignment. We focus on this aspect of the process by modeling two adjacent base pairs in terms of a classical damped oscillator subject to thermal fluctuations as described by a Fokker-Planck equation. We find that the process is characterized by two time scales, a result that is in accord with the experimental findings

2002-10-01

227

Water level monitoring and controlling system in reactor pressure vessel  

International Nuclear Information System (INIS)

Upon controlling of a water level conducted before an operation of removing a head of a reactor pressure vessel performed upon periodical inspection of a power plant, a supersonic displacement sensor capable of conducting measurement on the basis of cm unit is used as a water level indicator. The water level in the reactor pressure vessel can be controlled to a position above a steam dryer accurately by a remote operation while measuring the water level in the pressure vessel at a high accuracy. In addition, a dose equivalent gauge for evaluating the dose equivalent rate of the operation circumstance is previously disposed before the removal of the head of the reactor pressure vessel to reduce the amount of operation and exposure dose of a radiation operation manager. These supersonic displacement sensor and dose equivalent gauge are made detachable so that they can be disposed only when they are required thereby enabling to minimize the deterioration of the device. (N.H.)

1996-11-29

228

Hampshire, West Sussex and Isle of Wight water levels  

Our hydrometric stations collect data on river levels and flows, rainfall and groundwater. This data helps us manage water resources for people and wildlife, and provide flood warnings. Related Searches: ladies mile vernham dean preston candover

229

Trace-level mercury removal from surface water  

International Nuclear Information System (INIS)

Many sorbents have been developed for the removal of mercury and heavy metals from waters; however, most of the data published thus far do not address the removal of mercury to the target levels represented in this project. The application to which these sorbents are targeted for use is the removal of mercury from microgram-per-liter levels to low nanogram-per-liter levels. Sorbents with thiouronium, thiol, amine, sulfur, and proprietary functional groups were selected for these studies. Mercury was successfully removed from surface water via adsorption onto Ionac SR-4 and Mersorb resins to levels below the target goal of 12 ng/L in batch studies. A thiol-based resin performed the best, indicating that over 200,000 volumes of water could be treated with one volume of resin. The cost of the resin is approximately $0.24 per 1,000 gal of water

1998-09-13

230

Trace-level mercury removal from surface water  

Energy Technology Data Exchange (ETDEWEB)

Many sorbents have been developed for the removal of mercury and heavy metals from waters; however, most of the data published thus far do not address the removal of mercury to the target levels represented in this project. The application to which these sorbents are targeted for use is the removal of mercury from microgram-per-liter levels to low nanogram-per-liter levels. Sorbents with thiouronium, thiol, amine, sulfur, and proprietary functional groups were selected for these studies. Mercury was successfully removed from surface water via adsorption onto Ionac SR-4 and Mersorb resins to levels below the target goal of 12 ng/L in batch studies. A thiol-based resin performed the best, indicating that over 200,000 volumes of water could be treated with one volume of resin. The cost of the resin is approximately $0.24 per 1,000 gal of water.

Klasson, K.T.; Bostick, D.T.

1998-06-01

231

Water level monitoring and controlling system in reactor pressure vessel  

Energy Technology Data Exchange (ETDEWEB)

Upon controlling of a water level conducted before an operation of removing a head of a reactor pressure vessel performed upon periodical inspection of a power plant, a supersonic displacement sensor capable of conducting measurement on the basis of cm unit is used as a water level indicator. The water level in the reactor pressure vessel can be controlled to a position above a steam dryer accurately by a remote operation while measuring the water level in the pressure vessel at a high accuracy. In addition, a dose equivalent gauge for evaluating the dose equivalent rate of the operation circumstance is previously disposed before the removal of the head of the reactor pressure vessel to reduce the amount of operation and exposure dose of a radiation operation manager. These supersonic displacement sensor and dose equivalent gauge are made detachable so that they can be disposed only when they are required thereby enabling to minimize the deterioration of the device. (N.H.)

Nishida, Chikara; Matsuhashi, Yoshinori; Mikura, Michitaka

1998-06-19

232

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

233

Predicting effects of climate fluctuations for water management by applying neural network  

Energy Technology Data Exchange (ETDEWEB)

This paper investigates the applicability of neural networks in climate based forecasting for regional water resources management. A neural network is a computational method inspired by studies of the brain and nerve systems in biological organisms. Neural networks represent highly idealized mathematical models of the authors present understanding of such complex systems. Typically, a neural network consists of a set of layered processing units and weighted interconnections between the units. There exists a variety of neural network models and learning procedures. This paper applies the most widely used Back Propagation model to the climate forecasting. While the architecture of the Back Propagation network is fairly established, the process of determining the best suitable network configuration and the best parameters for a given application is trial-and-error, especially when the relationships between the variables are not well understood. On the other hand, this trial-and-error process can be used to help reveal the underlining relationships between variables. In this study, issues such as selecting a best fit neural network configuration, deploying a proper training algorithm, and preprocessing input data are addressed. The effects of various global oceanic and atmospheric variables to the regional water resources are also discussed. The study is focused on the prediction of inflow to Lake Okeechobee, the liquid heart for south Florida. Several global weather parameters over the past several decades are used as input data for training and testing. Different combinations of the variables are explored.

Zhang, E.; Trimble, P. [South Florida Water Management District, West Palm Beach, FL (United States)

1996-09-01

234

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)

1980-10-17

235

Subtidal water level variation controlled by river flow and tides  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Subtidal water level dynamics in the Berau river, East Kalimantan, Indonesia, feature a pronounced fortnightly variation. The daily mean water levels at a station about 60 km from the sea are 0.2–0.6 m higher during spring tide than during neap tide. To explain the underlying mechanisms, a local subtidal momentum balance is set up from field data, using continuous discharge estimates inferred from measurements taken with a horizontal acoustic Doppler current profiler. It is demonstrated tha...

Buschman, F. A.; Hoitink, A. J. F.; Vegt, M.; Hoekstra, P.

2009-01-01

236

Radium-226 levels in Italian drinking waters and foods  

International Nuclear Information System (INIS)

Levels of "2"2"6Ra in Italian waters and foods were measured. Results were similar to those found in other countries, except for some mineral waters with "2"2"6Ra concentrations above 1 pCi/liter andup to 19 pCi/liter. No difinite correlation was found between the "2"2"6Ra concentrations measured and the high natural background radiation levels determined in central Italy in previous work

1978-04-28

237

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 influe...

Armstrong, A.; Rose, S.

1999-01-01

238

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ur...

Monia Renzi; Andrea Giovani; Focardi, Silvano E.

2012-01-01

239

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

240

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)

2005-10-02

 
 
 
 
241

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

242

A comparative study of ejaculate traits in three endangered ungulates with different levels of inbreeding: fluctuating asymmetry as an indicator of reproductive and genetic stress.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We studied three closely related species of endangered gazelles (Gazella dorcas, Gazella dama and Gazella cuvieri) with different levels of inbreeding in order to determine at which intensities inbreeding influences ejaculate traits. We also examined whether fluctuating asymmetry (FA) is a reliable indicator of genetic as well as reproductive stress. Our results show that, within each population, the individual coefficient of inbreeding is inversely related to ejaculate quality only in the sp...

Gomendio, M.; Cassinello, J.; Roldan, E. R.

2000-01-01

243

Ground-water discharge determined from measurements of evapotranspiration, other available hydrologic components, and shallow water-level changes, Oasis Valley, Nye County, Nevada  

International Nuclear Information System (INIS)

Oasis Valley is an area of natural ground-water discharge within the Death Valley regional ground-water flow system of southern Nevada and adjacent California. Ground water discharging at Oasis Valley is replenished from inflow derived from an extensive recharge area that includes the northwestern part of the Nevada Test Site (NTS). Because nuclear testing has introduced radionuclides into the subsurface of the NTS, the U.S. Department of Energy currently is investigating the potential transport of these radionuclides by ground water flow. To better evaluate any potential risk associated with these test-generated contaminants, a number of studies were undertaken to accurately quantify discharge from areas downgradient in the regional ground-water flow system from the NTS. This report refines the estimate of ground-water discharge from Oasis Valley. Ground-water discharge from Oasis Valley was estimated by quantifying evapotranspiration (ET), estimating subsurface outflow, and compiling ground-water withdrawal data. ET was quantified by identifying areas of ongoing ground-water ET, delineating areas of ET defined on the basis of similarities in vegetation and soil-moisture conditions and computing ET rates for each of the delineated areas. A classification technique using spectral-reflectance characteristics determined from satellite imagery acquired in 1992 identified eight unique areas of ground-water ET. These areas encompass about 3,426 acres of sparsely to densely vegetated grassland, shrubland, wetland, and open water. Annual ET rates in Oasis Valley were computed with energy-budget methods using micrometeorological data collected at five sites. ET rates range from 0.6 foot per year in a sparse, dry saltgrass environment to 3.1 feet per year in dense meadow vegetation. Mean annual ET from Oasis Valley is estimated to be about 7,800 acre-feet. Mean annual ground-water discharge by ET from Oasis Valley, determined by removing the annual local precipitation component of 0.5 foot, is estimated to be about 6,000 acre-feet. Annual subsurface outflow from Oasis Valley into the Amargosa Desert is estimated to be between 30 and 130 acre-feet. Estimates of total annual ground-water withdrawal from Oasis Valley by municipal and non-municipal users in 1996 and 1999 are 440 acre-feet and 210 acre-feet, respectively. Based on these values, natural annual ground-water discharge from Oasis Valley is about 6,100 acre-feet. Total annual discharge was 6,500 acre-feet in 1996 and 6,300 acre-feet in 1999. This quantity of natural ground-water discharge from Oasis Valley exceeds the previous estimate made in 1962 by a factor of about 2.5. Water levels were measured in Oasis Valley to gain additional insight into the ET process. In shallow wells, water levels showed annual fluctuations as large as 7 feet and daily fluctuations as large as 0.2 foot. These fluctuations may be attributed to water loss associated with evapotranspiration. In shallow wells affected by E T, annual minimum depths to water generally occurred in winter or early spring shortly after daily ET reached minimum rates. Annual maximum depths to water generally occurred in late summer or fall shortly after daily ET reached maximum rates. The magnitude of daily water-level fluctuations generally increased as ET increased and decreased as depth to water increased

2002-01-01

244

Response of the Apodi-Mossoró estuary-incised valley system (NE Brazil to sea-level fluctuations  

Directory of Open Access Journals (Sweden)

Full Text Available This study focuses on the Quaternary sea level changes in the Apodi-Mossoró Estuary and adjacent shelf, Northeastern Brazil, based on the analysis of high-resolution seismic profiles, integrated with echosounder, SRTM and satellite image data. We use these data to develop a relative stratigraphy. An incised-valley extending from the Apodi-Mossoró Estuary onto the shelf dominates the investigated area. In very shallow waters (down to 10 m depth the channel lies mainly in a NW-SE direction, changing to NE-SW in waters below10 m, in the form of a J-shaped valley. The southern flank of the shallow channel presents an abrupt morphology, probably determined by a residual scarp due to neotectonic reactivation of a pre-existing fault. This incised-valley can be correlated with a former river valley formed during the late Pleistocene fall in sea-level. The base-level change related to this drop in sea level can be regionally expressed on seismic lines as a laterally-continuous stratigraphic surface named Horizon I, interpreted as representing the sub-aerial exposure of the continental shelf. Many incised valleys were excavated on this exposed shelf, including that of the Apodi-Mossoró Estuary and its incised valley system. This incised valley has lain buried since the Holocene transgression. The Holocene sediments present sub-horizontal layers, or they have filled the incised valley with oblique features.Este estudo utiliza a integração de dados sísmicos de alta resolução, batimétricos, SRTM e imagens de satélite para desenvolvimento da estratigrafia relativa visando entender as variações do nível do mar durante o Quaternário no estuário do rio Apodi-Mossoró e plataforma adjacente, nordeste do Brasil. A principal feição identificada foi um canal submerso, na plataforma interna, parcialmente preenchido, provavelmente relacionado com o sistema de vales incisos formado durante o rebaixamento do nível do mar no Pleistoceno. O canal apresenta duas direções principais (NW-SE e NE-SW, em forma da letra J, aparentemente controladas pelas estruturas tectônicas da Bacia Potiguar. A margem oeste do canal é relativamente soerguida em relação à margem leste. Com base nos dados sísmicos foi possível identificar uma descontinuidade presente em toda a área, interpretada como o limite Pleistoceno/Holoceno, bem como sismofácies referentes a padrões de preenchimento e sedimentação do canal submerso e da plataforma durante a subida do nível do mar no Holoceno.

Helenice Vital

2010-01-01

245

Response of the Apodi-Mossoró estuary-incised valley system (NE Brazil) to sea-level fluctuations  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este estudo utiliza a integração de dados sísmicos de alta resolução, batimétricos, SRTM e imagens de satélite para desenvolvimento da estratigrafia relativa visando entender as variações do nível do mar durante o Quaternário no estuário do rio Apodi-Mossoró e plataforma adjacente, nordeste do Brasi [...] l. A principal feição identificada foi um canal submerso, na plataforma interna, parcialmente preenchido, provavelmente relacionado com o sistema de vales incisos formado durante o rebaixamento do nível do mar no Pleistoceno. O canal apresenta duas direções principais (NW-SE e NE-SW), em forma da letra J, aparentemente controladas pelas estruturas tectônicas da Bacia Potiguar. A margem oeste do canal é relativamente soerguida em relação à margem leste. Com base nos dados sísmicos foi possível identificar uma descontinuidade presente em toda a área, interpretada como o limite Pleistoceno/Holoceno, bem como sismofácies referentes a padrões de preenchimento e sedimentação do canal submerso e da plataforma durante a subida do nível do mar no Holoceno. Abstract in english This study focuses on the Quaternary sea level changes in the Apodi-Mossoró Estuary and adjacent shelf, Northeastern Brazil, based on the analysis of high-resolution seismic profiles, integrated with echosounder, SRTM and satellite image data. We use these data to develop a relative stratigraphy. An [...] incised-valley extending from the Apodi-Mossoró Estuary onto the shelf dominates the investigated area. In very shallow waters (down to 10 m depth) the channel lies mainly in a NW-SE direction, changing to NE-SW in waters below10 m, in the form of a J-shaped valley. The southern flank of the shallow channel presents an abrupt morphology, probably determined by a residual scarp due to neotectonic reactivation of a pre-existing fault. This incised-valley can be correlated with a former river valley formed during the late Pleistocene fall in sea-level. The base-level change related to this drop in sea level can be regionally expressed on seismic lines as a laterally-continuous stratigraphic surface named Horizon I, interpreted as representing the sub-aerial exposure of the continental shelf. Many incised valleys were excavated on this exposed shelf, including that of the Apodi-Mossoró Estuary and its incised valley system. This incised valley has lain buried since the Holocene transgression. The Holocene sediments present sub-horizontal layers, or they have filled the incised valley with oblique features.

Helenice, Vital; Samia F.Lima, Furtado; Moab Praxedes, Gomes.

246

Monitoring of water level inside reactor pressure vessel  

International Nuclear Information System (INIS)

Up to the TMI accident the water level inside the pressurizer was used to monitor the water inventory inside the primary cooling system of pressurized water reactors. The TMI accident showed that this was not a reliable measurement for the reactor coolant inventory inside the reactor pressure vessel. For this reason there was a demand for a measurement of the water level inside the RVP, independent from the existing one inside the pressurizer and with a diverse measuring method. For WWER reactors a new level measurement system was developed to monitor the water level inside the reactor pressure vessel by means of the KNITU, resp. KITU level probe which meet all the mentioned engineered safeguards and geometric and constructive requirements. First backfitting s of the new level measurement system in the WWER s 440 in Bohunice V1 (Slovakia), unit 1 (1998) and unit 2 (2000), Novovoronezh (Russia), unit 4 (1999) and Kola (Russia), unit 1 and unit 2 (1999) show very good operational results. (Authors)

2001-09-01

247

Water uptake strategies of maize under varying levels of water stress  

Science.gov (United States)

More frequent and intense droughts due to global climate change, together with an increasing agricultural water use emphasize the importance of understanding root water uptake under water-stressed conditions. While root water uptake is driven by potential gradients, measurement of soil water potentials was limited by the measurement range of water-filled tensiometers (-0.085 MPa). A recently developed polymer tensiometer (POT) can measure soil water potentials down to -1.6 MPa. Monitoring low soil water potentials in the presence of root water uptake may help gain knowledge of a plant's strategy to cope with water stress, and allows improved determination of local water stress levels in experiments. To investigate plant strategies that cope with water stress, soil water potentials were measured in the vicinity of maize roots in three lysimeters. The lysimeters received different irrigation amounts: an optimal irrigation gift (-0.05 < p < -0.02 MPa) and minimized irrigation to create moderate (minimum p = -0.45 MPa) and severe (minimum p = -0.80 MPa) water stress. Measured soil water potentials showed that the water stressed plants started to take up water from deeper soil layers, and continued to take up water under very dry conditions. This research was funded by the Dutch Technology Foundation (STW).

van der Ploeg, M.; Gooren, H. P. A.; Bakker, G.; de Rooij, G. H.

2009-04-01

248

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

249

Calving Glacier Dynamics Controlled by Small Fluctuations in Subglacial Water Pressure Revealed by Hot Water Drilling in Glaciar Perito Moreno, Patagonia  

Science.gov (United States)

Most glaciers in Patagonia terminate in lakes and the ocean. Despite the importance of these calving glaciers for the recent mass loss of the Patagonia Icefields, studies on glacier dynamics are scarce in the region. To investigate the role of subglacial water pressure in the dynamics of calving glaciers, we drilled through Glaciar Perito Moreno, a fast flowing (400-800 m a-1) fresh water calving glacier draining eastward in the Southern Patagonia Icefield. This was the first attempt of hot water drilling and subglacial observations in Patagonia. The drilling was performed from February to March 2010 at about 5 km from the terminus, where the glacier is 510 m thick and the bed is 330 m below the proglacial lake level (Fig. 1). We drilled two boreholes to the bed and installed pressure sensors to measure borehole water levels. Ice surface speed was measured every hour with GPS receivers. The water levels and flow speed were measured from 5 to 14 March and from 25 February to 2 April 2010, respectively. The water levels in the boreholes were about 440 m above the bed, oscillating in a diurnal manner within a range of ±15 m. This observation indicated that the subglacial water pressure was 92-98% of the ice overburden pressure. Ice flow speed showed clear diurnal variations correlated with air temperature during the 5-week measurement period (r=0.77). The data revealed that up to 40% of change in flow speed was driven by only 6% subglacial water pressure variations. The speed was very sensitive to the water pressure, probably because the pressure was consistently close to the ice overburden. Fig. 1. (a) Satellite image of Glaciar Perito Moreno showing locations of drilling (+), GPS (?) and temperature (?) measurement sites with summer mean flow vectors (image courtesy of NASA Johnson Space Center). (b) Longitudinal cross section along the central flowline. The bed profile is based on the observational data (?) by Stuefer et al. (2007).

Sugiyama, S.; Skvarca, P.; Naito, N.; Enomoto, H.; Tsutaki, S.; Tone, K.; Marinsek, S.; Aniya, M.

2010-12-01

250

Jack-up leveling barge for shallow water rigs  

Energy Technology Data Exchange (ETDEWEB)

Generally, the only alternative to a shell pad is a shallow water jack-up or a submersible rig. And in some instances, it is impractical to tow these mobile rigs to the location because of the necessary dredging. A possible solution to this problem, devised by Chain Jacks, Inc., is a jack-up leveling barge that extends its legs and pads to the bottom in waters ranging to 35 ft deep, then ballasts down to a depth of 10 ft or so below the surface. The barge-mounted rigs move over the leveling barges, ballast down and start rigging up. At this point, the leveling barge de-ballasts to minimize the load on the legs and mats. Chain Jack says the concept will enable barge mounted rigs to drill in waters ranging from 25 to 35 ft, and the cost will be considerably less than that of jack-ups or submersibles.

1982-07-01

251

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

252

Optimal level controller for steam generators in pressurized water reactors  

International Nuclear Information System (INIS)

The paper presents a different approach via optimal control theory to the design of water level controller for steam generators in large pressurized water reactors. The problem is cast into an optimal linear regulator control problem and a linearized state space model in standard form is developed from the nonlinear descriptor representation of the system. The proposed controller is a linear, constant, state feedback law which has the following desirable features: the controller is independent of the disturbance, the water level returns to its prespecified level value following a disturbance, the controlled system is asymptotically stable, and the transients are optimized. A numerical example is given to illustrate the effectiveness of the proposed controller

1987-01-01

253

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

254

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)

2000-03-01

255

Multiplicity fluctuations and temperature fluctuations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We argue that specific fluctuations observed in high-energy nuclear collisions can be attributed to intrinsic fluctuations of temperature of the hadronizing system formed in such processes and therefore can be described by the same nonextensivity parameter $q$ characterizing Tsallis statistics describing such systems (for $q \\to 1$ one recovers the usual Boltzmann-Gibbs approach). It means that $|q-1|$, which is a direct measure of temperature fluctuations, can also be expre...

Wilk, Grzegorz; Wlodarczyk, Zbigniew

2009-01-01

256

Water Quality and pH Levels in Aquatic Ecosystems  

Science.gov (United States)

In this fun and in depth hands-on experiment, learners test various liquid samples (distilled water, lemon juice, vinegar, and baking soda mixed with water) to determine their pH levels and identify each sample as either acid, base or neutral chemical. Then, over the course of several weeks, learners perform a number of tests and observe the affects of pH level on plants. The wrap up section of this activity discusses acid rain and its dramatic impact on aquatic animals, and tips for going further.

Jersey, New; Center, Liberty S.; Coalition, New J.

2006-01-01

257

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

1982-01-01

258

Using silicates to lower lead levels in drinking water  

Energy Technology Data Exchange (ETDEWEB)

York is a small resort town on the coast of Maine, near the New Hampshire border. The town's population of 5,000 usually doubles during the summer tourist season. Like many small water systems in New England, its soft, moderately alkaline water corrodes its unlined, cast-iron pipe distribution system, picking up significant quantities of iron along the way. Customers served by these lines have complained about the red water. York Water District officials hoped that a new 4-mgd treatment facility brought into service in spring 1990 would alleviate the red water problems, but they were also considering ways to address the requirements of the Lead and Copper Rule from the EPA promulgated in 1991. With the assistance of their consulting engineering firm, York Water District officials evaluated treatment strategies and decided against using polyphosphates to control lead and copper because of their ability to complex with the metals, possibly causing an increase in concentration. The officials eventually chose sodium silicates to lower the iron, lead, and copper levels in the system. Several utilities in Maine had reported using sodium silicate as a common strategy for red water problems. In addition, sodium silicate was favored because it reacts with metal for form a barrier to corrosion. York Water District, with assistance from its consultant, designed an 18-month program to add sodium silicates to its system, track metal concentrations, and monitor red water complaints. The district prepared a report for the EPA, covering data collected over the first 12 months of the program -- essentially calendar year 1991. According to Michael R. Schock, research chemist with the EPA's Drinking Water Research Division in Cincinnati, the agency is anxious to obtain as much quantitative information as possible on using sodium silicate for pH and/or corrosion control. This article describes the monitoring system, water treatment and study results.

1994-09-01

259

Fluvial-estuarine reinterpretation of large, isolated sandstone bodies in epicontinental cyclothems, Upper Pennsylvanian, northern Midcontinent, USA, and their significance for understanding late Paleozoic sea-level fluctuations  

Science.gov (United States)

The Upper Pennsylvanian Indian Cave Sandstone (ICS) in southeastern Nebraska is herein reinterpreted as three multistory incised valley fills and one single-storey channel fill, altogether representing at least two different intervals of time. ICS lithosomes are linear bodies, as much as 2000 m wide and 30 m thick, incised into pre-existing cyclothems, and have relatively steep sides and flat bases. They include crudely fining-upwards successions of trough cross-bedded sandstones, interpreted as tidally-influenced fluvial deposits, overlain by upper estuarine heterolithic facies, with local coals, and a restricted trace fossil assemblage. The vertical facies succession suggests sediment accumulation in a regime of gradually increasing accommodation, i.e., during rising relative sea level. The basal erosion surfaces of ICS bodies can be traced out onto the adjacent interfluves where they correspond to well-developed paleosols, indicating sequence boundaries. Furthermore, the sequences defined herein can be correlated closely with recently published sequence stratigraphic frameworks from the region, suggesting that the ICS bodies record repeated, fifth-order (Milankovitch band), relative sea-level fluctuations of a minimum of 30 m during latest Pennsylvanian time Significantly, this estimate is half or less of those made by many other studies. Such a local quantification of relative sea-level change provides a critical constraint on eustatic sea-level fluctuation during the late Paleozoic Gondwanan Ice Age.

Fischbein, S. A.; Joeckel, R. M.; Fielding, C. R.

2009-04-01

260

Low-level measurements of tritium in water  

International Nuclear Information System (INIS)

Using a liquid scintillation counter, an experimental procedure for measuring low-level activity concentrations of tritium in environmental water has been developed by our laboratory, using the electrolytic tritium enrichment. Additionally, some quality tests were applied in order to assure the goodness of the method. Well-known water samples collected in the Tagus River (West of Spain) and the Danube River (Bulgaria), both affected by nuclear plant releases, were analysed and results were compared to previous data. The analytical procedure was applied to drinking water samples from the public water supply of Seville and mineral waters from different springs in Spain in order to characterize its origin. Due to the very low levels of tritium in the analysed samples, some results were reported as lower than the minimum detectable activity concentration (MDA). However, the count rate of these measurements was over the background count rate of LS counter in all the cases. For that reason, an exhaustive discussion about the meaning of the MDA, using an experimental essay, was made in order to establish a rigorous criterion that leads to a reliable value in the case of low-level measurements

2003-10-10

 
 
 
 
261

Low-level measurements of tritium in water.  

Science.gov (United States)

Using a liquid scintillation counter, an experimental procedure for measuring low-level activity concentrations of tritium in environmental water has been developed by our laboratory, using the electrolytic tritium enrichment. Additionally, some quality tests were applied in order to assure the goodness of the method. Well-known water samples collected in the Tagus River (West of Spain) and the Danube River (Bulgaria), both affected by nuclear plant releases, were analysed and results were compared to previous data. The analytical procedure was applied to drinking water samples from the public water supply of Seville and mineral waters from different springs in Spain in order to characterize its origin. Due to the very low levels of tritium in the analysed samples, some results were reported as lower than the minimum detectable activity concentration (MDA). However, the count rate of these measurements was over the background count rate of LS counter in all the cases. For that reason, an exhaustive discussion about the meaning of the MDA, using an experimental essay, was made in order to establish a rigorous criterion that leads to a reliable value in the case of low-level measurements. PMID:15177365

Villa, M; Manjón, G

2004-01-01

262

Low-level measurements of tritium in water  

Energy Technology Data Exchange (ETDEWEB)

Using a liquid scintillation counter, an experimental procedure for measuring low-level activity concentrations of tritium in environmental water has been developed by our laboratory, using the electrolytic tritium enrichment. Additionally, some quality tests were applied in order to assure the goodness of the method. Well-known water samples collected in the Tagus River (West of Spain) and the Danube River (Bulgaria), both affected by nuclear plant releases, were analysed and results were compared to previous data. The analytical procedure was applied to drinking water samples from the public water supply of Seville and mineral waters from different springs in Spain in order to characterize its origin. Due to the very low levels of tritium in the analysed samples, some results were reported as lower than the minimum detectable activity concentration (MDA). However, the count rate of these measurements was over the background count rate of LS counter in all the cases. For that reason, an exhaustive discussion about the meaning of the MDA, using an experimental essay, was made in order to establish a rigorous criterion that leads to a reliable value in the case of low-level measurements.

Villa, M. E-mail: mvilla@us.es; Manjon, G

2004-09-01

263

Wireless Automatic Water Level Control using Radio Frequency Communication  

Directory of Open Access Journals (Sweden)

Full Text Available Water scarcity is the serious issue in major cities. It is a common problem which is faced by every house owner, that when his tank is empty he has to switch on the motor and switch the motor off when it is full. Due to the busy life it is common that the tank usually overflows without notice. One has to keep on observing his tank water level to switch off the motor once it is switched on. And sometimes this also can happen that the motor coil burns because of absence of water in the sump. So these are the everyday problem that motivated us in coming up with an affordable, wireless automatic water level control system that doesn’t need any attention once it is installed.In this paper we have discussed about design and implementation of water level control system which is wireless, automatic, cost effective and reliable. It uses two Radio Frequency transceivers along with a controller each installed at the tank and sump. Radio Frequency transceivers are used for wireless communication. It is completely automated with the help of a micro controller. The system doesn’t need any attention of the user unless the sump is empty. Installation cost is reduced since the system is wireless. It is reliable because it has no problems arising after installation such as breakage of wire

MUKTHA SHANKARI K

2013-04-01

264

TRIHALOMETHANE LEVELS IN HOME TAP WATER AND SEMEN QUALITY  

Science.gov (United States)

Trihalomethane Levels in Home Tap Water and Semen Quality Laura Fenster, 1 Kirsten Waller, 2 Gayle Windham, 1 Tanya Henneman, 2 Meredith Anderson, 2 Pauline Mendola, 3 James W. Overstreet, 4 Shanna H. Swan5 1California Department of Health Services, Division of Environm...

265

Measurement of low-level activity in water  

Energy Technology Data Exchange (ETDEWEB)

The practice describes the process necessary to obtain meaningful data from water samples that contain low levels (<10 pCi) of radioactivity. The practice includes a discussion of instrumentation, measurement of alpha emitters, measurement of beta activity, measurement of gamma activity, general counting procedure, calculation, and reporting. (JMT)

1981-01-01

266

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

267

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

2006-09-06

268

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

269

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

270

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

271

Quantifying Water Level Change Through Time in the North American Great Lakes  

Science.gov (United States)

Anthropogenic and natural fluctuations including precipitation, runoff, snowmelt, water retention time, evaporation, and outflow all contribute to changes in water levels recorded in the North American Great Lakes. Changes in water levels and tides have been used as an index for physical parameters such as temperature, density, and circulation (Keeling and Whorf, 1997; Denny and Paine, 1998). In this study, NOAA verified hourly water level data ranging from 20 to 30 years in duration for five stations in Lake Michigan and four stations in Lake Superior were analyzed. Power Spectral Density calculated from a Fourier transform of the time series were found to exhibit power law scaling. The power-scaling exponent (?) was determined by fitting a power function to a log-log plot of frequency (f) or period (1/f) versus power in the frequency domain. Four distinct regions of scaling are observed with inflection points at approximately 1 day, 5 days, and 30 - 60 days. For time scales of less than one day, the power-scaling exponent (?) ranges from 0.1 to 0.5, indicating a white noise. From 1 day to 5 - 7 days, ? ranges from 1.5 to 2.6, indicating moderate to strong persistence which we propose is due to frontal movements of weather systems. On timescales between 5 days and 30 - 60 days, ? ranges from 0.1 to 0.4, again indicating a white noise which we propose is due to monthly and seasonal weather variations within the Great Lakes System. Beyond 30 - 60 days, all stations exhibit persistence, with ?-values between 1.6 and 2.7.

Tebbens, S. F.; Smigelski, J. R.; Barton, C. C.

2011-12-01

272

Intercomparison of low-level tritium in water  

International Nuclear Information System (INIS)

In 1985 the Section of Isotope Hydrology of the IAEA organized the fourth intercomparison for low-level tritium counting in waters. Four water samples with different 3H concentration were sent to 85 laboratories willing to participate. The results from the different laboratories were presented in the unified questionnaires and coded. The participation in the intercomparisons for every laboratory doing low-level 3H measurements in the waters is very important and useful. This is a best way to check the entire procedure and methods of the measurements and the reliability of the standards used. Since our laboratories are doing the natural 3H concentration measurement in the waters for the environmental control and hydrology reasons it was necessary to take part in this intercomparison. Our standard procedure was applied. The 3H activity in the samples was measured by liquid scintillation counting after an electrolytic enrichment. The results of our measurements of the four water samples, received from the organizers, are presented on the figures and tables presenting summary of the intercomparison. It is clear that our measurement (procedure and standards) have given satisfactory results (author)

1989-10-02

273

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

274

One high voltage direct current HVAC power station Malaysia planning produce intelligent power controller artificial neural networks ANN techniques. controller action Touchet down main power switch current levels goes up down fluctuation  

Science.gov (United States)

Did you mean: One high voltage direct current HVAC power station Malaysia planning produce intelligent power controller artificial neural networks ANN techniques. controller action Touchet down main power switch current levels goes up down fluctuation ?

275

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

Directory of Open Access Journals (Sweden)

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

276

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)

1998-01-01

277

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

278

Wide Fluctuations in Fluorescence Lifetimes of Individual Rovibronic Levels in SiH2 (A1B sub 1).  

Science.gov (United States)

We have measured fluorescence lifetimes of individual rovibronic levels in SiH2. The lifetimes vary widely from one level to the next, ranging from 1 micro. Similar behavior is seen in the (000), (010), and (030) levels. This behavior is inte...

J. W. Thoman J. I. Steinfeld R. I. McKay A. E. Knight

1987-01-01

279

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

280

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)

2005-07-17

 
 
 
 
281

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-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

282

Steam Pressurizer test and water level measurement performance test  

Energy Technology Data Exchange (ETDEWEB)

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

Park, M. R.; Hwang, S. C.; Han, S. J. [KIMM, Daejeon (Korea, Republic of)

2010-01-15

283

Response of bacterial community structure to seasonal fluctuation and anthropogenic pollution on coastal water of Alang-Sosiya ship breaking yard, Bhavnagar, India.  

Science.gov (United States)

Bacterial community structure was analyzed from coastal water of Alang-Sosiya ship breaking yard (ASSBY), world's largest ship breaking yard, near Bhavnagar, using 16S rRNA gene sequencing (cultured dependent and culture independent). In clone libraries, total 2324 clones were retrieved from seven samples (coastal water of ASSBY for three seasons along with one pristine coastal water) which were grouped in 525 operational taxonomic units. Proteobacteria was found to be dominant in all samples. In pristine samples, Gammaproteobacteria was found to be dominant, whereas in polluted samples dominancy of Gammaproteobacteria has shifted to Betaproteobacteria and Epsilonproteobacteria. Richness and diversity indices also indicated that bacterial community in pristine sample was the most diverse followed by summer, monsoon and winter samples. To the best of knowledge, this is the first study describing bacterial community structure from coastal water of ASSBY, and it suggests that seasonal fluctuation and anthropogenic pollutions alters the bacterial community structure. PMID:24727696

Patel, Vilas; Munot, Hitendra; Shouche, Yogesh S; Madamwar, Datta

2014-06-01

284

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

285

Concentrating Low-Level Tritiated Water Through Isotope Exchange  

International Nuclear Information System (INIS)

Trapping of tritium on polymers with specific functional groups was investigated as a means of treating waste streams containing low levels of tritium. Chemical exchange of tritium with hydrogen on the functional group was used as the mechanism for trapping. The polymers tested include Aurorez polybenzimidazole resin beads, Chelex 100 resin beads, Duolite GT-73, microcrystalline cellulose, and polyethylenimine. The tests were performed under simulated operating conditions on water obtained from the Radioactive Liquid Waste Treatment Facility at Los Alamos National Laboratory. Tritiated water from the Tritium Systems Test Assembly is discharged to this plant. Polyethylenimine is a water-soluble polymer that was tested using a stirred membrane cell with an ultrafiltration membrane. All of the polymers except polyethylenimine took up tritium from the water. Polybenzimidazole demonstrated the highest tritium uptake. The results are explained on the basis of the type of functional group, hydrogen bonding, and rigidity of the molecular structure of the polymer. The theoretical calculations indicate that significant isotope discrimination requires high-frequency modes with hydrogen bonding contribution and support the experimental findings. Modeling suggested trends that may lead to structures that are more efficient in trapping tritium

2000-03-01

286

Concentrating low-level tritiated water through isotope exchange  

Energy Technology Data Exchange (ETDEWEB)

Trapping of tritium on polymers with specific functional groups was investigated as a means of treating waste streams containing low levels of tritium. Chemical exchange of tritium with hydrogen on the functional group was used as the mechanism for trapping. The polymers tested include Aurorez polybenzimidazole resin beads, Chelex 100 resin beads, Duolite GT-73, microcrystalline cellulose, and polyethylenimine. The tests were performed under simulated operating conditions on water obtained from the Radioactive Liquid Waste Treatment Facility at Los Alamos National Laboratory, Tritiated water from the Tritium Systems Test Assembly is discharged to this plant. Polyethylenimine is a water-soluble polymer that was tested using a stirred membrane cell with an ultrafiltration membrane. All of the polymers except polyethylenimine took up tritium from the water. Polybenzimidazole demonstrated the highest tritium uptake. The results are explained on the basis of the type of functional group, hydrogen bonding, and rigidity of the molecular structure of the polymer. The theoretical calculations indicate that significant isotope discrimination requires high-frequency modes with hydrogen bonding contribution and support the experimental findings. Modeling suggested trends that may lead to structures that are more efficient in trapping tritium.

Jorgensen, B.S.; Dye, R.C.; Pratt, L.R.; Gomez, M.A.; Meadows, J.E.

2000-03-01

287

Concentrating low-level tritiated water through isotope exchange  

International Nuclear Information System (INIS)

Trapping of tritium on polymers with specific functional groups was investigated as a means of treating waste streams containing low levels of tritium. Chemical exchange of tritium with hydrogen on the functional group was used as the mechanism for trapping. The polymers tested include Aurorez polybenzimidazole resin beads, Chelex 100 resin beads, Duolite GT-73, microcrystalline cellulose, and polyethylenimine. The tests were performed under simulated operating conditions on water obtained from the Radioactive Liquid Waste Treatment Facility at Los Alamos National Laboratory, Tritiated water from the Tritium Systems Test Assembly is discharged to this plant. Polyethylenimine is a water-soluble polymer that was tested using a stirred membrane cell with an ultrafiltration membrane. All of the polymers except polyethylenimine took up tritium from the water. Polybenzimidazole demonstrated the highest tritium uptake. The results are explained on the basis of the type of functional group, hydrogen bonding, and rigidity of the molecular structure of the polymer. The theoretical calculations indicate that significant isotope discrimination requires high-frequency modes with hydrogen bonding contribution and support the experimental findings. Modeling suggested trends that may lead to structures that are more efficient in trapping tritium

2000-03-01

288

Screening Experiments for Removal of Low-Level Tritiated Water  

International Nuclear Information System (INIS)

Screening experiments for low levels of tritiated water (HTO) remediation based upon selective adsorption/desorption mechanisms utilizing equilibrium isotope effects have been carried out. Several organic and inorganic high surface area materials were investigated to assess their ability to selectively adsorb low concentrations of HTO. Ion-exchange resins with cation functionalities, chitosan, sodium alginate, and several inorganic media modified with metal cations exhibited promising results. Biomaterials, for example, chitosan and modified alginate, demonstrated positive results. Based on the literature and our preliminary testing, we postulate four possible mechanisms for selected tritium adsorption: hydrogen ion exchange, HTO coordination with surface cation sites, hydrogen bonding to surface basic sites, and secondary hydrogen bonding (structural water) in fine pores

2005-03-01

289

Removal of trace-level mercury from surface water  

Energy Technology Data Exchange (ETDEWEB)

The removal of mercury from slipstreams of water from a creek and from a wastewater treatment plant has been studied in the field. Two types of column studies were performed with different mercury sorbents. A short-term study that yielded information about the kinetic behavior of different sorbents in a column configuration and a long-term study that is under they way were used to obtain information about long-term performance and treatment capacity. The results indicate that sorbents containing thiol functional groups gave the best performance in both the short- and long-term studies. The results also indicate that water pretreatment may be an effective option to ensure that the mercury is free and oxidized. This approach may be a necessity when target levels of ng/L are desired.

Klasson, K.T.; Bostick, D.T.; Taylor, P.A.; Farr, L.L.

1999-07-01

290

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 su...

2004-01-01

291

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)

1998-01-01

292

Cross correlations between charge noise and critical-current fluctuations in a four-level tunable Josephson system  

Science.gov (United States)

A protocol to test cross correlations between charge and critical-current noise in the small superconducting contacts of an asymmetric Cooper-pair transistor coupled to a phase qubit is presented. The superconducting circuit behaves as a tunable four-level quantum system that can be prepared in two different configurations where cross-correlation terms are, respectively, absent or present and therefore, in principle, detectable. The measurements of the cross correlations are performed either through the escape probability of the dc superconducting quantum interference device or a quantum-state tomography of a few elements of the reduced density matrix of the four-level quantum system.

Faoro, Lara; Hekking, Frank W. J.

2010-02-01

293

The Organochlorine Pesticides Residue Levels in Karun River Water  

Directory of Open Access Journals (Sweden)

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

294

Projected climate change effects on water level of an oxbow  

Science.gov (United States)

One of the most vulnerable regions in the Carpathian Basin is the Great Hungarian Plain, where small and shallow oxbows are endangered along river Tisza. The purpose of this paper is to determine how the global warming affects a typical oxbow, located on the floodplain of river Tisza, in Hungary. A coupled meteorological-hydraulic model is developed and applied for this oxbow. Results suggest that the monthly minimum water levels are expected to decrease, moreover, extreme drought events sometimes result temporary drying-up of the oxbow.

Hunyady, Adrienn

295

Bode Analysis and Modeling of Water Level Change in the Great Lakes  

Science.gov (United States)

Power Spectral Density calculated from a fast Fourier transform expresses a time series in terms of power in the corresponding frequency domain. The power-scaling exponent ( ? ) is determined by fitting a power function to a log-log plot of frequency ( f ) or period ( 1/f ) versus power in the frequency domain. Anthropogenic and natural fluctuations including precipitation, runoff, snowmelt, water retention time, evaporation, and outflow all contribute to changes in water levels recorded in the Great Lakes. In this study, NOAA verified hourly water level data ranging from 20 to 30 years in duration for five stations in Lake Michigan and four stations in Lake Superior were analyzed. Water level time series in the Great Lakes are found to exhibit power law scaling and are thus self-affine over four distinct period ranges, each with a different beta value. With this information, a model of the original time series may be generated using an approach which draws from concepts in control theory and feedback systems. Bode Analysis can be applied in the frequency domain to explain variations in the scaling behavior ( ? ) of water level data by examining the patterns of change in amplitude and phase across frequencies. A Bode magnitude plot of the system is created from the data of power versus frequency converting the amplitude to 20log dB magnitude. A transfer function representing the output of the system divided by the input is then derived based on the data using Laplace transforms and solved for magnitude and phase. Bode analysis results in a series of two transfer function equations, one for magnitude and one for phase, for each distinct beta value over the specified period range. The type of differential equation controls the slope ( ? ) while the constant (k) in the differential equation controls the position (period) of transitions in scaling behavior (i.e., corner frequencies or inflection points) and are characteristics of the system. Combining the transfer functions for all frequencies yields a Frequency Response Model of the underlying internal dynamics of the system and provides a basis to determine how a system will respond to any given input. For water level change in the Great Lakes, the complex pattern of scaling versus period can be well approximated by a combination of linear differential equations or transfer functions representing magnitude and phase at each frequency within each period range. The linear differential equation Frequency Response Model describes water levels of the Great Lakes system as two spring inertial systems coupled together and provides a quantitative measure of variations observed in the Power Spectral Density plots. The Frequency Response Model is also used to generate a synthetic time series which is statistically identical to the original Great Lakes water level time series. This method introduces a novel way to generate a quantitative, equation-based model of self-affine time series data.

Tebbens, S. F.; Smigelski, J. R.; Barton, C. C.

2009-12-01

296

Universal mesoscopic conductance fluctuations  

International Nuclear Information System (INIS)

The theory of conductance fluctuations in disordered metallic systems with size large compared to the mean free path of the electron but small compared to localization length is considered. It is demonstrates that fluctuations have an universal character and are due to repulsion between levels and spectral rigidity. The basic fluctuation measures for the energy spectrum in the mesoscopic regime of disordered systems are consistent with the Gaussian random matrix ensemble predictions. Although our disordered electron random matrix ensemble does not belong to the Gaussian ensemble the two ensembles turn out to be essentially similar. The level repulsion and the spectral rigidity found in nuclear spectra should also be observed in the metallic regime of Anderson localization. 7 refs. (orig.)

1992-01-01

297

Fluctuations in total antioxidant capacity, catalase activity, and hydrogen peroxide levels of follicular fluid during bovine folliculogenesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Follicular fluid is an important environment for oocyte development, yet current knowledge regarding its in vivo oxidant and antioxidant levels remains limited. Examining follicular fluid oxidants and antioxidants will improve understanding of their changes in vivo and contribute to optimization of in vitro maturation conditions. The aim of our study was to consider select markers, namely catalase (CAT) enzyme activity, total antioxidant capacity (TAC), and hydrogen peroxide (H2O2) in follicu...

Gupta, Sajal; Choi, Audrey; Yu, Hope Y.; Czerniak, Suzanne M.; Holick, Emily A.; Paolella, Louis J.; Agarwal, Ashok; Combelles, Catherine M. H.

2011-01-01

298

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

2014-01-01

299

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

Directory of Open Access Journals (Sweden)

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

300

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)

2008-06-01

 
 
 
 
301

The west African mangrove: an indicator of sea-level fluctuations and regional climate changes during the last deglaciation  

International Nuclear Information System (INIS)

The review of modern and late Quaternary pollen data recording the mangrove evolution in West Africa shows that littoral and deep-sea sediments have registered different signals. The first one gives evidence for past sea-level variations from ca. 12,000 B.P. to ca. 5,000 B.P. The second one records the first widespread response of tropical forest ecosystems to the last deglaciation step and enhanced monsoonal rains at ca. 9,500 B.P. (authors)

1996-01-01

302

Relative significance of tectonics, sea level fluctuations, and paleoclimate to Cretaceous coal distribution in North America. Cooperative thesis  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this research has been to address the quantitative and qualitative parameters of coal distribution which are considered to be responsive to the dynamic controls of tectonics, climate, and sea level change. These dynamic controls all operate through time and space with varying degrees of influence on coal accumulation and preservation. As a result, a geologic, climatic, oceanographic, and biologic overview which considers coal distribution for all of North America over the span of Cretaceous time is believed important for developing a holistic model to explain the principal controls on such distribution.

Beeson, D.C.

1984-01-01

303

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

304

Experimental poromechanics of trabecular bone strength: role of Terzaghi's effective stress and of tissue level stress fluctuations.  

Science.gov (United States)

In the 1920s and 1930s, Terzaghi and coworkers realized that the failure of various porous geomaterials under internal pore pressure is given through evaluating the failure function for the same materials at zero pressure, with 'total stress plus pore pressure' instead of 'total stress alone' as argument. As to check, probably for the first time, the relevance of this ('Terzaghi's') failure criterion for trabecular bone, a series of poromechanical and ultrasonic tests was conducted on bovine and human trabecular bone samples. Evaluation of respective experimental results within the theoretical framework of microporomechanics showed that (i) Terzaghi's effective stress indeed governs trabecular bone failure, (ii) deviatoric stress states at the level of the solid bone matrix (also called tissue level) are primary candidates for initiating bone failure, and (iii) the high heterogeneity of these deviatoric tissue stresses, which increases with increasing intertrabecular porosity, governs the overall failure of trabecular bone. Result (i) lets us use the widely documented experimental results for strength values of bone samples without pore pressure, as to predict failure of the same bone samples under internal pore pressure. Result (ii) suggests a favorable mode for strength modeling of solid bone matrix. Finally, result (iii) underlines the suitability of microfinite element simulations for trabecular bone microstructures. PMID:20883995

Brynk, Tomasz; Hellmich, Christian; Fritsch, Andreas; Zysset, Philippe; Eberhardsteiner, Josef

2011-02-01

305

Design of double-fuzzy-integral intelligent water level controller for steam generator  

International Nuclear Information System (INIS)

In order to effectively control the water level of steam generator, a double-fuzzy-integral water level controller is designed in this paper. A 'false water level' distinguishing fuzzy controller is added before normal fuzzy controller, to control the water level effectively when SG is in 'false water level' phase. In order to have an optimal water level control, this paper gives the result of fuzzy controller and integral controller export in phase. By the analyzing of control curve, it has validated that the designed double-fuzzy-integral water level controller may overcome the disadvantageous influence given by 'false water level' phenomena to the water level control, and that the control excess adjustment quantity is small and the steady time is short. (authors)

2007-04-01

306

Multi-Annual Fluctuations in Reconstructed Historical Time-Series of a European Lobster (Homarus gammarus) Population Disappear at Increased Exploitation Levels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Through the history of ecology, fluctuations of populations have been a dominating topic, and endogenous causes of fluctuations and oscillations have been recognized and studied for more than 80 years. Here we analyzed an historical dataset, covering more than 130 years, of European lobster (Homarus gammarus) catches. The data shows periodic fluctuations, which are first dampened and then disappear over time. The disappearance of the periodicity coincided with a substantial increase in fishin...

2013-01-01

307

Assessing coupling between lakes and layered aquifers in a complex Pleistocene landscape based on water level dynamics  

Science.gov (United States)

The biosphere reserve Schorfheide-Chorin is a scenic region with many lakes. Hydraulic coupling between lakes and groundwater is difficult to assess due to the very heterogeneous Pleistocene deposits with a complex layering of different aquifers, part of them being confined. Thus, a principal component analysis of time series of groundwater and lake water levels was performed. The first two principal components provided a quantitative measure of damping of the input signal, i.e., the extent to which time series of groundwater pressure heads or lake water levels are smoothed and delayed with respect to the input signal, i.e., groundwater recharge or precipitation minus evapotranspiration, respectively. The lakes differed substantially with respect to damping behaviour, indicating different impacts of deep groundwater contribution. For most of the groundwater wells, damping increased linearly with mean depth to water table. In contrast, some wells exhibited nearly identical behaviour independent of depth. High-pass filtered data of water table level from these wells were strongly and inversely correlated with those of barometric pressure fluctuations, pointing to a confined aquifer which was evidently not connected to the adjacent lake.

Lischeid, Gunnar; Natkhin, Marco; Steidl, Jörg; Dietrich, Ottfried; Dannowski, Ralf; Merz, Christoph

2010-11-01

308

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

1981-01-01

309

The effects of disturbance and severe seasonal fluctuations in environmental conditions on north temperate shallow-water fish assemblages  

Science.gov (United States)

The shallow-water fish populations at one disturbed and one undisturbed site in the Oslofjord, Norway were sampled with a beach seine from September 1981 to September 1982. The inner site (inner fjord; Hvervenbukta) is in the most polluted part of the fjord and has a heavy recreational usage during the summer months, the outer site (Ellingstad) is in a least polluted part of the fjord and has only sporadic recreational usage. Physical conditions at the two sites differ primarily in seasonal changes of dissolved oxygen levels (Hvervenbukta 3·3-11·1 ml O 2 1 -1 and Ellingstad 5·3-7·1 ml O 2 1 -1). Thirty-three fish species were caught at Ellingstad compared with only 23 at Hvervenbukta, with 0·61 similarity in species lists. Both sites had approximately equal numbers of resident and non-resident species. The mean density of individuals was much greater at Hvervenbukta (0·36 m -2) than at Ellingstad (0·04 m -2). Both sites showed a high dominance factor with a few species comprising the majority of the abundance. Overall species diversity ( H'), evenness ( F') and species richness ( D) were greater at Ellingstad, consistent with the reduced disturbance. The overall range in seasonal similarity was relatively high for both sites as a function of the severe seasonal cycle in temperature (ice cover to approximately 20 °C). These relatively high variations are to be expected for north temperate fish assemblages. The range in the seasonal similarity index was greater at Hvervenbukta reflecting increased disturbance. There were dissimilar patterns in the seasonal cycles of community parameters at the two sites. Changes in population structure were largest during the period of recruitment of new year classes.

Nash, Richard D. M.

1988-02-01

310

GPS water level measurements for Indonesia's Tsunami Early Warning System  

Directory of Open Access Journals (Sweden)

Full Text Available On Boxing Day 2004, a severe tsunami was generated by a strong earthquake in Northern Sumatra causing a large number of casualties. At this time, neither an offshore buoy network was in place to measure tsunami waves, nor a system to disseminate tsunami warnings to local governmental entities. Since then, buoys have been developed by Indonesia and Germany, complemented by NOAA's Deep-ocean Assessment and Reporting of Tsunamis (DART buoys, and have been moored offshore Sumatra and Java. The suite of sensors for offshore tsunami detection in Indonesia has been advanced by adding GPS technology for water level measurements.

The usage of GPS buoys in tsunami warning systems is a relatively new approach. The concept of the German Indonesian Tsunami Early Warning System (GITEWS (Rudloff et al., 2009 combines GPS technology and ocean bottom pressure (OBP measurements. Especially for near-field installations where the seismic noise may deteriorate the OBP data, GPS-derived sea level heights provide additional information.

The GPS buoy technology is precise enough to detect medium to large tsunamis of amplitudes larger than 10 cm. The analysis presented here suggests that for about 68% of the time, tsunamis larger than 5 cm may be detectable.

T. Schöne

2011-03-01

311

Trend Analysis of Ground-Water Levels and Spring Discharge in the Yucca Mountain Region, Nevada and California, 1960-2000  

International Nuclear Information System (INIS)

Ground-water level and discharge data from 1960 to 2000 were analyzed for the Yucca Mountain region of southern Nevada and eastern California. Included were water-level data from 37 wells and a fissure (Devils Hole) and discharge data from five springs and from a flowing well. Data were evaluated for variability and for upward, downward, or cyclic trends with an emphasis on the period 1992-2000. Potential factors causing trends in water levels and discharge include ground-water withdrawal, infiltration of precipitation, earthquakes, evapotranspiration, barometric pressure, and earth tides. Statistically significant trends in ground water levels or spring discharge from 1992 to 2000 were upward at 12 water-level sites and downward at 14 water-level sites and 1 spring-discharge site. In general, the magnitude of the change in water level from 1992 to 2000 was small (less than 2 feet), except where influenced by pumping or local effects such as possible equilibration from well construction or diversion of nearby surface water. Seasonal trends are superimposed on some of the long-term (1992-2000) trends in water levels and discharge. Factors causing seasonal trends include barometric pressure, evapotranspiration, and pumping. The magnitude of seasonal change in water level can vary from as little as 0.05 foot in regional aquifers to greater than 5 feet in monitoring wells near large supply wells in the Amargosa Farms area. Three major episodes of earthquake activity affected water levels in wells in the Yucca Mountain region between 1992 and 2000: the Landers/Little Skull Mountain, Northridge, and Hector Mine earthquakes. The Landers/Little Skull Mountain earthquakes, in June 1992, had the largest observed effect on water levels and on discharge during the study period. Monthly measurements of wells in the study network show that earthquakes affected water levels from a few tenths of a foot to 3.5 feet. In the Ash Meadows area, water levels remained relatively stable from 1992 to 2000, with some water levels showing small rising trends and some declining slightly. Possible reasons for water-level fluctuations at sites AD-6 (Tracer Well 3), AM-5 (Devils Hole Well), and AM-4 (Devils Hole) from 1960 to 2000 include climate change, local and regional ground-water withdrawals, and tectonic activity. In Jackass Flats, water levels from 1992 to 2000 in six wells adjacent to Fortymile Wash displayed either small upward trends or no upward or downward trend. Comparison of trends in water levels from 1983 to 2000 for these six wells shows good correlations between all wells and suggests a common mechanism controlling water levels in the area. Of the likely controls on the system-precipitation or pumping in Jackass Flats-precipitation appears to be the predominant factor controlling water levels near Fortymile Wash. Water levels in the heavily pumped Amargosa Farms area declined from about 10 to 30 feet from 1964 to 2000. Water-level declines accelerated beginning in the early 1990's as pumping rates increased substantially. Pumping in the Amargosa Farms area may affect water levels in some wells as far away as 5-14 miles. The water level at site DV-3 (Travertine Point 1 Well) and discharge at site DV-2 (Navel Spring), both in the Death Valley hydrographic area, had downward trends from 1992 to 2000. The cause of these downward trends may be linked to earthquakes, pumping in the Amargosa Farms area, or both

312

Seasonal Fluctuations In Co, Ni, Cu, Zn, Cd, Pb Concentrations In Surface Microlayers And Subsurface Water Of Two City Ponds  

Directory of Open Access Journals (Sweden)

Full Text Available We owe the knowledge concerning the surface water microlayer to the wide research into marine environment and relatively scarce research done into inland city ponds ecosystems. The surface microlayer is a very thin, several hundred micrometers thick layer at the contact of water and atmosphere. This important form of air-water exchange ecotone, which constitutes the surface microlayer of water, is a specific environment as to its chemical and physical characteristics and is different from subsurface waters. It can absorb chemical substances like heavy metals, phytoneuston and bacteria in larger quantities in comparison to lower parts of the water. This characteristic feature results, among others, from the processes of transport at the contact of hydrosphere-atmosphere and also transport within the very area of surface water microlayer. The paper describes transport processes of six heavy metals: Co, Ni, Cu, Zn, Cd, Pb from subsurface water to surface water microlayer and vice versa, analyzed in a one year cycle. The transport of chemical substances under consideration was described on a basis of experiments made during the period of one year at five city pounds in S?upsk (Polish Pomerania. During the research, samples of the surface water microlayer were collected by means of application of the Garrett mesh technique. At the same time, samples of subsurface water were collected and tested as to the content of the same parameters as the surface microlayer. Samples were sampled in month intervals. The concentration of aforementioned heavy metals was measured by mass spectrometry method and used Perkin Elmer Elan DRC aparature.

Antonowicz J. P.

2013-04-01

313

Behaviors of extreme water level in the Pearl River Delta and possible impacts from human activities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Trends and variations of the extreme water levels defined as exceeding/falling below certain thresholds (mean ± std) across the Pearl River Delta (PRD) are systematically explored using the linear regression method. Research results indicate that: 1) The upper PRD is dominated by the significant decreasing low water level, and significant increasing low water level can be identified in the lower PRD. The variations of the relative frequency of the high water level are characterized by the de...

Chen, Y. D.; Zhang, Q.; Yang, T.; Xu, C.; Chen, X.; Jiang, T.

2007-01-01

314

Characterisation of hydrogeological connections in a lowland karst network using time series analysis of water levels in ephemeral groundwater-fed lakes (turloughs)  

Science.gov (United States)

This research has used continuous water level measurements five groundwater-fed lakes (or turloughs) in a linked lowland karst network of south Galway in Ireland over a 3 year period in order to elucidate the hydrogeological controls and conduit configurations forming the flooded karstic hydraulic system beneath the ground. The main spring outflow from this network discharges below mean sea level making it difficult to determine the hydraulic nature of the network using traditional rainfall-spring flow cross analysis, as has been done in many other studies on karst systems. However, the localised groundwater-surface water interactions (the turloughs) in this flooded lowland karst system can yield information about the nature of the hydraulic connections beneath the ground. Various different analytical techniques have been applied to the fluctuating turlough water level time series data in order to determine the nature of the linkage between them as well as hydraulic pipe configurations at key points in order to improve the conceptual model of the overall karst network. Initially, simple cross correlations between the different turlough water levels were carried out applying different time lags. Frequency analysis of the signals was then carried out using Fast Fourier transform analysis and then both discrete and continuous wavelet analyses have been applied to the data sets to characterise these inherently non-stationary time-series of fluctuating water levels. The analysis has indicated which turloughs are on the main line conduit system and which are somewhat off-line, the relative size of the main conduit in the network including evidence of localised constrictions, as well as clearly showing the tidal influence on the water levels in the three lower turloughs at shallow depths ˜8 km from the main spring outfall at the sea. It has also indicated that the timing of high rainfall events coincident with maximum spring tide levels may promote more consistent, long duration flooding of the turloughs throughout the winter.

Gill, L. W.; Naughton, O.; Johnston, P. M.; Basu, B.; Ghosh, B.

2013-08-01

315

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

CERN Multimedia

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 $x_{\\text{TBA}} \\approx 0.03 - 0.07$. 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 $x_{\\text{TBA}} \\approx 0.05$. 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 non-linearity. Interestingly, water mol...

Banerjee, Saikat; Bagchi, Biman

2014-01-01

316

ERPWS: An Energy Efficient Routing Protocol for Conductive Sensor based Water Level Monitoring and Control System using Zigbee and 74HC14 Inverter  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we have shown how to use conductive sensor, Zigbee and 74HC14 Inverter to monitor the water level and to control the working of pump. This project is designed to automatically fill the over head tank when it gets empty and monitor the water level in it. The motor is switched ON when the water level in the overhead tank drops below a pre fixed low level (on point and puts off the motor when water level rises up to pre fixed high level (off point.The motor is also switched off during the following conditions: when the sump water is exhausted before filling overhead tank, pump running dry, mains voltage fluctuations. We also introduce an energy efficient routing protocol for Wireless Sensor Networks (ERPWS for Conductive Sensor based Water Level Monitoring and Control System using Zigbee (XBEE 802.15.4 in terms of energy consumptions, the packet loss ratio, network lifetime and the average delivery delay. The XBEE used here is XBEE Pro Series 1(XBP24-AWI-001 and IC used is 74HC14 Hex Inverting Schmitt trigger. Simulation results have been obtained by using NS2 simulator. The evaluation results show that the energy consumption of routing using ERPWS is significantly lower than LEACH and traditional routing protocols.

Saima Maqbool

2013-07-01

317

Lithostratigraphy of the Middle Eocene Dammam Formation in Qatar, Arabian Gulf: effects of sea-level fluctuations along a tidal environment  

Science.gov (United States)

The Middle Eocene Dammam Formation dominates the surface exposure of Qatar. It consists of shales followed by limestone and is topped by dolomitic limestone. It is subdivided, from oldest to youngest, into the Midra Shale, Dukhan, Umm Bab and Abaruq members. Three patterns of facies dominate the formation. Shale-marl facies in the lower part, mudstone/wackestone/packstone facies in the middle part and argillaceous dolomitic wackestone/packstone facies in the upper part. The main fauna of the Dammam Formation include Nummulites, Alveolines, Linderines, shark teeth, molluscs and echinoderms. The Nummulites species are common, particularly within the middle members (Dukhan and Umm Bab members). Coarsening-upward parasequences reflect the cyclicity of the Eocene Dammam Formation in Qatar. At least three short-lived transgressive/regressive cyclothems can be recognized in sediments of the formation. These small-scale cycles resulted from fluctuations in sea level. A local hiatus is believed to separate these cycles in northeastern Qatar. A warm shallow marine environment was predominant as indicated by extensive dolomitization and the presence of Alveolines, Linderines and Nummulites with globular tests.

Al-Saad, Hamad

2005-08-01

318

Water Hardness Level and ItAND#8217;s Health Effects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Water hardness is a term used to define the number of ions contained in the water, especially quantity sulphate, carbonate salts of calcium and magnesium. This characteristis of water is a important quality in it’s use as drinking water, industrial water and service water. The temporary hardness level of water cames from bicarbonate salts of calcium and magnesium whereas chloride, sulphate, nitrate, phosphate, silicate salts of calcium and magnesium. In order to indicate the hardness le...

2011-01-01

319

To save water or not? : A study of water scarcity at multiple levels, and people's attitudestowards it in Bangalore, India  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In a situation where population growth and development is to be sustained throughnaturally limited water resources, something needs to be done to either render waterusage more effective or make more water available. This is the situation in Bangalore Urban District (BUD), an ever growing city lying far from perennial water sources. This thesis presents the water situation in BUD, and aims to analyze the current status of water resources on multiple levels in BUD. Further the aim is to look at...

Bogna?s, De?sire?e

2011-01-01

320

COMPARISON OF VENTED AND ABSOLUTE PRESSURE TRANSDUCERS FOR WATER-LEVEL MONITORING IN HANFORD SITE CENTRAL PLATEAU WELLS  

Energy Technology Data Exchange (ETDEWEB)

Automated water-level data collected using vented pressure transducers deployed in Hanford Site Central Plateau wells commonly display more variability than manual tape measurements in response to barometric pressure fluctuations. To explain this difference, it was hypothesized that vented pressure transducers installed in some wells are subject to barometric pressure effects that reduce water-level measurement accuracy. Vented pressure transducers use a vent tube, which is open to the atmosphere at land surface, to supply air pressure to the transducer housing for barometric compensation so the transducer measurements will represent only the water pressure. When using vented transducers, the assumption is made that the air pressure between land surface and the well bore is in equilibrium. By comparison, absolute pressure transducers directly measure the air pressure within the wellbore. Barometric compensation is achieved by subtracting the well bore air pressure measurement from the total pressure measured by a second transducer submerged in the water. Thus, no assumption of air pressure equilibrium is needed. In this study, water-level measurements were collected from the same Central Plateau wells using both vented and absolute pressure transducers to evaluate the different methods of barometric compensation. Manual tape measurements were also collected to evaluate the transducers. Measurements collected during this study demonstrated that the vented pressure transducers over-responded to barometric pressure fluctuations due to a pressure disequilibrium between the air within the wellbores and the atmosphere at land surface. The disequilibrium is thought to be caused by the relatively long time required for barometric pressure changes to equilibrate between land surface and the deep vadose zone and may be exacerbated by the restriction of air flow between the well bore and the atmosphere due to the presence of sample pump landing plates and well caps. The disequilibrium is likely limited to wells screened across the water table (i.e., open to the deep vadose zone) where the depth to water is large or a low-permeability layer occurs in the vadose zone. Such wells are a pathway for air movement between the deep vadose zone and land surface and this sustains the pressure disequilibrium between the well bore and the atmosphere for longer time periods. Barometric over-response was not observed with the absolute pressure transducers because barometric compensation was achieved by directly measuring the air pressure within the well. Users of vented pressure transducers should be aware of the over-response issue in certain Hanford Site wells and ascertain if it will affect the use of the data. Pressure disequilibrium between the well and the atmosphere can be identified by substantial air movement through the wellbore. In wells exhibiting pressure disequilibrium, it is recommended that absolute pressure transducers be used rather than vented transducers for applications that require precise automated determinations of well water-level changes in response to barometric pressure fluctuations.

MCDONALD JP

2011-09-08

 
 
 
 
321

A 3500 14C yr High-Resolution Record of Water-Level Changes in Lake Titicaca, Bolivia/Peru  

Science.gov (United States)

Sediment cores collected from the southern basin of Lake Titicaca (Bolivia/Peru) on a transect from 4.6 m above overflow level to 15.1 m below overflow level are used to identify a new century-scale chronology of Holocene lake-level variations. The results indicate that lithologic and geochemical analyses on a transect of cores can be used to identify and date century-scale lake-level changes. Detailed sedimentary analyses of subfacies and radiocarbon dating were conducted on four representative cores. A chronology based on 60 accelerator mass spectrometer radiocarbon measurements constrains the timing of water-level fluctuations. Two methods were used to estimate the 14C reservoir age. Both indicate that it has remained nearly constant at ˜250 14C yr during the late Holocene. Core studies based on lithology and geochemistry establish the timing and magnitude of five periods of low lake level, implying negative moisture balance for the northern Andean altiplano over the last 3500 cal yr. Between 3500 and 3350 cal yr B.P., a transition from massive, inorganic-clay facies to laminated organic-matter-rich silts in each of the four cores signals a water-level rise after a prolonged mid-Holocene dry phase. Evidence of other significant low lake levels occurs 2900-2800, 2400-2200, 2000-1700, and 900-500 cal yr B.P. Several of the low lake levels coincided with cultural changes in the region, including the collapse of the Tiwanaku civilization.

Abbott, Mark B.; Binford, Michael W.; Brenner, Mark; Kelts, Kerry R.

1997-03-01

322

Fuzzy logic control of steam generator water level in pressurized water reactors  

International Nuclear Information System (INIS)

In this paper a fuzzy logic controller is applied to control the steam generator water level in a pressurized water reactor. The method does not require a detailed mathematical mode of the object to be controlled. The design is based on a set of linguistic rules that were adopted from the human operator's experience. After off-line fuzzy computation, the controller is a lookup table, and thus, real-time control is achieved. Shrink-and-swell phenomena are considered in the linguistic rules, and the simulation results show that their effect is dramatically reduced. The performance of the control system can also be improved by changing the input and output scaling factors, which is convenient for on-line tuning

1992-10-01

323

Behaviors of extreme water level in the Pearl River Delta and possible impacts from human activities  

Directory of Open Access Journals (Sweden)

Full Text Available Trends and variations of the extreme water levels defined as exceeding/falling below certain thresholds (mean ± std across the Pearl River Delta (PRD are systematically explored using the linear regression method. Research results indicate that: 1 The upper PRD is dominated by the significant decreasing low water level, and significant increasing low water level can be identified in the lower PRD. The variations of the relative frequency of the high water level are characterized by the decreasing variability in the middle PRD. However more stations show significant changes of the relative frequency of the low water level across the PRD. No confirmative changing patterns of the relative frequency of the low water level can be detected in the middle PRD; 2 When it comes to the seasonal variations of the high/low water level in JJA (high flow periods in the PRD, stations located closer to the estuary tend to exhibit increasing high/low water level. However stations located closer to the upper PRD tend to show decreasing high/low water level. Similar patterns can be identified in the high/low water level in DJF (low flow periods in the PRD; 3 The changes of the water level in the PRD are heavily affected by human interferences, e.g. in-channel dredging, sand mining and the construction of levees. The stations dominated by decreasing water level are mostly located along the river channels featured by highly-intensive dredging. The stations along the coastal regions show significant increasing extreme high/low water level. The coastal regions are not influenced by in-channel dredging, and furthermore, sediment loads from upper and middle PRD are deposited in the river mouths and which will tend to raise the water level in the estuary of the PRD. The findings of this paper may be helpful for local water resource management.

Y. D. Chen

2007-12-01

324

Nitrate and Nitrite Levels of Natural Spring and Mineral Water in Van, Turkey  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study was performed to determine nitrate and nitrite levels of packaged natural spring and mineral water consumed in Van city of Turkey. A total of 200 water samples, belonging to 10 different companies, each of 100 pet spring water and 100 bottled mineral water samples were used as material. Nitrate and nitrite levels were measured by the spectrophotometric method. According to the results both nitrate and nitrite were found to be present in all water samples. Mean nitrate and nitrite c...

Nurhayat Atasoy; Suleyman Alemdar; Ufuk Mercan; Sema Agaoglu

2011-01-01

325

Water Level Evaluation at Southern Malaysia Reservoir using Fuzzy Composite Programming  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ranking and evaluation of properreservoir water level outflowing into downstream river system under multi-criterion environment was presented using multi-criteria decision approach specifically Fuzzy Composite Programming (FCP). The optimum water level evaluation is vital to take into consideration the various environmental, water quantity and economical aspects of the overall systems. This multicriteria analysis will optimize water release, ensuring water quality, providing economical benefi...

2013-01-01

326

Effect of water level drawdown on decomposition in boreal peatlands  

Science.gov (United States)

Plant litter production and decomposition are key processes in element cycling in most ecosystems. In peatlands, there has been a long-term imbalance between litter production and decay caused by high water levels (WL) and consequent anoxia. This has resulted in peatlands being a significant sink of carbon (C) from the atmosphere. However, peatlands are experiencing both "natural" (global climate change) and anthropogenic (ditching) changes that threaten their ability to retain this ecosystem identity and function. Many of these alterations can be traced back to WL drawdown, which can cause increased aeration, higher acidity, falling temperatures, and a greater probability of drought. Such changes are also associated with an increasing decomposition rate, and therefore a greater amount of C released back to the atmosphere. Yet studies about how the overall C balance of peatlands will be affected have come up with conflicting conclusions, demonstrating that the C store could increase, decrease, or remain static. A factor that has been largely overlooked is the change in litter type composition following persistent WL drawdown. It is the aim of our study, then, to help to resolve this issue. We studied the effects of short-term (ca. 4 years) and long-term (ca. 40 years) persistent WL drawdown on the decomposition of numerous types of above-ground and below-ground plant litters at three boreal peatland sites: bog, oligotrophic fen and mesotrophic fen. We thus believe that enough permutations have been created to obtain a good assessment of how each factor, site nutrient level, WL regime, and litter type composition, influences decomposition. We used the litter bag method to measure the decomposition rates: placed measured amounts of plant litter, or cellulose strips as a control, into closed mesh bags, and installed the bags in the natural environment for decomposition for each litter type for varying amounts of time. Following litter bag recovery, the litter was cleaned of excess debris and analyzed for changes in mass, enzyme activity, mesofauna presence, and microbial community composition, among other things. The experiment has a run-time of ten years, the results from the first two years are presented in the poster.

Straková, Petra; Penttilä, Timo; Laiho, Raija

2010-05-01

327

Tritium activity levels in environmental water samples from different origins  

International Nuclear Information System (INIS)

Tritium activity was determined in environmental waters from different areas of Catalonia, using a distillation procedure before liquid scintillation counting. The developed method was validated by analysing two samples from proficiency tests. In most of water samples (from rivers, rain, mineral bottled waters and tap waters) analysed, the activity values were lower or close to the minimum detectable activity (MDA) for our method which has a value of 0.6 Bq/l. However, the Ebro river samples had a mean activity around 3.6±0.6Bq/l. The nuclear power station of Asco, which is located on the banks of this river, can be a source of tritium production and introduction into the environment, so a more exhaustive study of these waters was carried out. Tritium activities in this river were a long way above the normative limit in Spain for waters intended for human consumption, which is 100 Bq/l

2007-09-01

328

Tritium activity levels in environmental water samples from different origins  

Energy Technology Data Exchange (ETDEWEB)

Tritium activity was determined in environmental waters from different areas of Catalonia, using a distillation procedure before liquid scintillation counting. The developed method was validated by analysing two samples from proficiency tests. In most of water samples (from rivers, rain, mineral bottled waters and tap waters) analysed, the activity values were lower or close to the minimum detectable activity (MDA) for our method which has a value of 0.6 Bq/l. However, the Ebro river samples had a mean activity around 3.6{+-}0.6Bq/l. The nuclear power station of Asco, which is located on the banks of this river, can be a source of tritium production and introduction into the environment, so a more exhaustive study of these waters was carried out. Tritium activities in this river were a long way above the normative limit in Spain for waters intended for human consumption, which is 100 Bq/l.

Palomo, M.; Penalver, A.; Aguilar, C. [Unitat de Radioquimica Ambiental i Sanitaria, Universitat Rovira i Virgili, Edifici CTT-FURV, Av. Paisos Catalans 18, 43007 Tarragona (Spain); Borrull, F. [Unitat de Radioquimica Ambiental i Sanitaria, Universitat Rovira i Virgili, Edifici CTT-FURV, Av. Paisos Catalans 18, 43007 Tarragona (Spain)], E-mail: francesc.borrull@urv.cat

2007-09-15

329

Lake Storage Measurements For Water Resources Management: Combining Remotely Sensed Water Levels and Surface Areas  

Science.gov (United States)

Presently operating satellite-based radar altimeters have the ability to monitor variations in surface water height for large lakes and reservoirs, and future sensors will expand observational capabilities to many smaller water bodies. Such remote sensing provides objective, independent information where in situ data are lacking or access is restricted. A USDA/NASA (http://www.pecad.fas.usda.gov/cropexplorer/global_reservoir/) program is performing operational altimetric monitoring of the largest lakes and reservoirs around the world using data from the NASA/CNES, NRL, and ESA missions. Public lake-level products from the Global Reservoir and Lake Monitor (GRLM) are a combination of archived and near real time information. The USDA/FAS utilizes the products for assessing international irrigation potential and for crop production estimates; other end-users study climate trends, observe anthropogenic effects, and/or are are involved in other water resources management and regional water security issues. At the same time, the Dartmouth Flood Observatory (http://floodobservatory.colorado.edu/), its NASA GSFC partners (http://oas.gsfc.nasa.gov/floodmap/home.html), and associated MODIS data and automated processing algorithms are providing public access to a growing GIS record of the Earth's changing surface water extent, including changes related to floods and droughts. The Observatory's web site also provide both archival and near real time information, and is based mainly on the highest spatial resolution (250 m) MODIS bands. Therefore, it is now possible to provide on an international basis reservoir and lake storage change measurements entirely from remote sensing, on a frequently updating basis. The volume change values are based on standard numerical procedures used for many decades for analysis of coeval lake area and height data. We provide first results of this combination, including prototype displays for public access and data retrieval of water storage volume changes. Ground-based data can, in some cases, test the remote sensing accuracy and precision. Data accuracy requirements vary for different applications: reservoir management for flood control, agriculture, or power generation may need more accurate and timely information than (for example) regional assessments of water and food security issues. Thus, the long-term goal for the hydrological sciences community should be to efficiently mesh both types of information and with as extensive geographic coverage as possible.

Brakenridge, G. R.; Birkett, C. M.

2013-12-01

330

Fluctuations, exchange processes, and water diffusion in aqueous protein systems: A study of bovine serum albumin by diverse NMR techniques  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Experimental frequency, concentration, and temperature dependences of the deuteron relaxation times T1 and T2 of D2O solutions of bovine serum albumin are reported and theoretically described in a closed form without formal parameters. Crucial processes of the theoretical concept are material exchange, translational diffusion of water molecules on the rugged surfaces of proteins, and tumbling of the macromolecules. It is also concluded that, apart from averaging of the relaxation rates in the...

1990-01-01

331

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 awareness in sectors of water, giving students positive attitudes towards water resources and conservation, uses and reduce consumption. Encourage students for voluntary collective actions as A hope to raising water awareness. The society sample study were represented by (320 Jordanian Universities students, take in consideration the following variables: Academic specialists, sex, University status and average monthly income per family. Data base for previous variables obtained by special questioner prepared for this study. Data run to statistical analysis through some simple Descriptive statistical approaches as (ANOVA. Results: The study showed that the level of water awareness towards water significant at a weak level, it reached to (57% of sample study towards water conservation. Students of scientific specializes have water awareness more than humanitarian specializes. There isnâ??t impact of University status and average monthly income on the level of water awareness. Conclusion/Recommendations: Most of study sample recognized with significant of water at life, they admit that Jordan faced water problem, but female were more than male at the level of water awarenes, also scientific specialists more than humanitarian specialties. Study recommends to enrich the curriculum of humanitarian sciences, with more topics looking for water and encourage personal activities and volunteers work to conserve water and rationalized it, also activation laws and legislation related with water.

Mohamad Said Damanhouri

2012-01-01

332

Lowered tritium levels in river water indicate significant storage of water in a large catchment  

International Nuclear Information System (INIS)

Tritium in the runoff of the Tugela river, in Kwazulu-Natal province on the east coast of South Africa, was monitored for a three year period from 1970 to 1972. The catchment above the runoff sampling site (Mandini) is 29089 km2 in extent; the altitude ranges from sea level to 3000 masl, the mean annual rainfall ranges from 700 to 1500 mm and the mean annual runoff ranges between 6 to 49% of the rainfall (that is 46 to 724 mm). Rainfall was monitored at three sites representing a range of altitudes and distance from the coast. Tritium in the river water was considerably lower than that of rainfall of the inland stations. A model for tritium in rainfall was used describing the increasing tritium content inland. Using the data of a rainfall-runoff model that describes 74 sub-catchments (200 to 1200 km2 in size) by their characteristic rainfall and runoff, it is possible to calculate the contribution of each sub-catchment to the total runoff at the sampling station. Labelling the runoff of each sub-catchment with the tritium level of its rainfall, enables the calculation of a weighted mean tritium content of annual input for the entire catchment. For the hydrological years (Oct-Sept) 1971/2 and 1972/3 these are 38 and 30 TU respectively. The weighted (by monthly flow) mean tritium level of the river is 26.6 and 26.3 TU for the same years. This suggest a large source of low-tritium water contributing to the Tugela runoff for both these seasons. This is all the more remarkable since the sampling period was six years after the bomb peak of tritium in the southern hemisphere (e.g. Pretoria station 6826200). Any carry-over water in the river from a previous year should actually increase the tritium content in the river. The sparseness of available data (two seasons) does not allow a detailed analysis of the residence times of water in the system and more recent measurements are just not available. Interpretation models that can be used are: a binary model indicating 74% of present year rainfall and 26% of pre-1960 (3.5 TU) water; a simple exponential (mixed box) model where the mean residence time will have to be as large as 7 to 9 years in order to introduce sufficient pre-bomb water. The rapid flow response to rainfall in the catchment and the low base flow in the river suggests that there is little storage available. Nevertheless, both the simplistic models require storage of water of a magnitude of at least the mean annual rainfall in the catchment. This discrepancy needs resolution

2003-05-19

333

Stochastic modeling of Lake Van water level time series with jumps and multiple trends  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In 1990s, water level in the closed-basin Lake Van located in the Eastern Anatolia, Turkey has risen up about 2 m. Analysis of the hydrometeorological shows that change in the water level is related to the water budget of the lake. In this study, a stochastic model is generated using the measured monthly water level data of the lake. The model is derived after removal of trend and periodicity in the data set. Trend observed in the lake water level time series is fitted by mono- and mul...

Aksoy, H.; Unal, N. E.; Eris, E.; Yuce, M. I.

2013-01-01

334

Sources of Elevated Sodium Levels in Drinking Water...and Recommendations for Reduction.  

Science.gov (United States)

Sodium enters drinking water by a variety of human activities and by natural means. Evidence suggests elevated levels of sodium in drinking water may adversely affect health. Action should be taken to reduce the level of human exposure to sodium in drinking water. (RE)

Calabrese, Edward J.; Tuthill, Robert W.

1978-01-01

335

Investigation of spatio-temporal water level and mass oscillations by using satellite gravimetry, altimetry and thermal data in Caspian Sea  

Science.gov (United States)

As Caspian Sea does not communicate with the world oceans, its dynamics are very different from the global water. Although -as for the world ocean- its level presents regular annual oscillations, estimations from last century and new more precise measurements shows large interannual fluctuations. Changes in the Caspian Sea water volume are investigated using space altimetry, whereas the GRACE satellite gravimetry mission allows monitoring the change of the surface mass distribution. Under the hypothesis that the change in water mass is the only cause of gravity change, it is possible to convert the mass distribution change into volume change, using a steric equation for the sea water. Combinations of multi-mission gridded altimetry data from AVISO with mono mission time series were used in order to analyze the local fluctuations of the lake, revealing a significant tilt between north and south. Large differences in the surface mass distribution rate of change in the basin and in the lake are evidenced in the GRACE data, as well as small differences in phase, which are due to delayed snow melting. Ignoring the short-term changes in water level due to winds, the main reason to cause periodic spatial water level disuniformity is spatial disuniformity in water density. Steric effect was calculated by interfering 2 factors of temperature and salinity. Steric anomaly maps show that it is able to change water level up to 17 cm. As the northern part of the lake has the least salinity in summers the largest effect would be expected to occur in the northern part, but the opposite is observed, probably due to the fact that this part is the shallowest. For the steric anomaly the lake presents spatially variations of 3 cm in winter but 7 cm in the summers. Generally, the largest steric induced fluctuations are observed in the middle of the lake, mostly in the north and east parts of the lake center. We used altimetry and space gravity data jointly, in order to build an improved and more coherent picture of the time space variation of the lake level and mass distribution. ;

Moradi, A.; de Viron, O.; Metivier, L.

2012-12-01

336

A new water level monitor system for nuclear reactor vessel during and after LOCAs  

International Nuclear Information System (INIS)

The water level in nuclear reactor vessel is an important parameter during and after LOCAs. It can not meet the nuclear safety specification to use the water level measured in the pressurizer to show the level in the vessel. It is difficult to monitor the water level in the vessel of NHR-200 nuclear heating reactor with present differential pressure transducers. A new level detector based on the heat transfer difference between water (or liquid) and steam (or gas) is developed and proven for use by experiments under the pressure 0.15-3.0 MPa. A new water level monitor system including a detector assembly that contains several detectors, a signal encoder and an intellectual processor, is designed. The analysis and experiments show that the new system is correct in principle, reliable in working properties and feasible in structure for monitoring the water level in the NHR-200 reactor

1997-04-14

337

A novel encoding water level monitor system during and after LOCAs in a nuclear heating reactor  

International Nuclear Information System (INIS)

The water level in a nuclear reactor vessel is an important parameter during and after LOCAs. Nuclear safety specifications can not be carried out when the water level is measured using a pressurizer which does show the level in the vessel. It is difficult to monitor the water level in the vessel of a Daqing 200MW nuclear heating reactor (NHR-200) using the present differential pressure transducers. Based on the heat transfer differences between water (or liquid) and steam (or gas), a novel level detector, which includes encoding heating shell thermocouples, has been developed and verified for use experimentally under pressures of 0.15-3.0 MPa. A novel encoding water level monitoring system was designed, made up of an assembly that contains several detectors, a signal encoder and an intelligent processor. Analysis and experiments have shown that the new system is correct in principle, reliable and feasible in structure for monitoring the water level in the NHR-200 reactor. (orig.)

1998-02-15

338

Water-level changes and directions of ground-water flow in the shallow aquifer, Fallon area, Churchill County, Nevada  

Science.gov (United States)

The Truckee-Carson-Pyramid Lake Water Rights Settlement Act of 1990 directed the U.S. Fish and Wildlife Service to acquire water rights for wetland areas in the Carson Desert, Nevada. The public is concerned that htis acquisition of water rights and delivery of the water directly to wildlife areas would result in less recharge to the shallow ground water in the Fallon area and cause domestic wells to go dry. In January 1992, the U.S. Geological Survey, in cooperation with U.S. Fish and Wildlife Service, began a study of the shallow ground-water system in the Fallon area in Churchill County, Nevada. A network of 126 wells in the study area was monitored. Between January and November 1992, water levels in most wells declined, usually less than 2 feet. The maximum measured decline over this period was 2.68 feet in a well near Stillwater Marsh. Between April and July, however, water levels rose in irrigated areas, typically 1 to 2 feet. Newlands Project water deliveries to the study area began soon after the turn of the century. Since then, water levels have risen more than 15 feet across much of the study area. Water lost from unlined irrigtiaon canals caused the stage in Big Soda Lake to rise nearly 60 feet; ground-water levels near the lake have risen 30 to 40 feet. The depth to water in most irrigated areas is now less than 10 feet. The altitude of the water table ranges from 4.025 feet above sea level 11 miles west of Fallon to 3,865 feet in the Stillwater Marsh area. Ground water flows eastward and divides; some flow goes to the northeast toward the Carson Sink and Stillwater areas, and some goes southeastward to Carson Lake.

Seiler, R. L.; Allander, K. K.

1993-01-01

339

Antioxidant response and oxidative stress levels in Macrobrachium borellii (Crustacea: Palaemonidae) exposed to the water-soluble fraction of petroleum.  

Science.gov (United States)

The aim of the present work was to evaluate the effect of the water soluble fraction of hydrocarbons (WSF) on the antioxidant status of the freshwater prawn Macrobrachium borellii. First, seasonal variations were studied in a non-polluted area. Hepatopancreas and gills showed season-related fluctuations in catalase (CAT), glutathione-S-transferase (GST) activities and in lipid peroxidation levels (LPO), but not in superoxide dismutase (SOD). Then, adults were exposed semi-statically to sublethal doses for 7days. CAT, SOD, GST, and glutathione peroxidase (GPx) activities and LPO, reduced glutathione (GSH) and protein oxidation (PO) levels were determined. Exposed individuals showed significant increases in CAT, SOD, and GST activities in hepatopancreas and CAT activity in gills. GPx activity did not vary in either tissues. While LPO levels increased, GSH levels decreased significantly in hepatopancreas of exposed animals, but PO levels showed no variation. Induction of SOD was also assessed by Real-time PCR mRNA expression in hepatopancreas. The non-enzymatic antioxidant activity was also tested; ABTS 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) was higher in hemolymph of treated-prawns compared to controls, but ferric reducing activity of plasma assay (FRAP) values did not change. Taken together, the present results indicated that the antioxidant defenses of M. borellii, mainly in hepatopancreas, were significantly affected by aquatic hydrocarbon contamination, regardless of the season. PMID:21320634

Lavarías, S; Heras, H; Pedrini, N; Tournier, H; Ansaldo, M

2011-05-01

340

Fluctuation contents of phosphorus and natural radionuclide in the water column of the Mersing river, Johor, Malaysia  

International Nuclear Information System (INIS)

Studies on natural radionuclides such as 210Po and 210Pb with the concentration of phosphorus in water column related to suspended particulate matter (SPM) were carried out at the Mersing River, Johor, Malaysia. Sixteen water samples were collected from nine stations on the 4th July 2010. 210Po and 210Pb activities varied between 0.76 to 2.24 mBq/L and 0.16 to 1.60 mBq/L respectively. The phosphorus concentrations, comprising total dissolved phosphorus (TDP), soluble reactive phosphorus (SRP) and dissolved organic phosphorus (DOP), were within the ranges of 6.06 to 23.31 ?g/L, 2.24 to 13.42 ?g/L and 0.47 to 16.10 ?/L, respectively. The concentration of TDP and salinity shows weak positive correlation (r = 0.39), perhaps due to the shallow depth of the Mersing River. There is a high positive correlation (r = 0.85) of 210Po activity with SPM concentration and a moderately positive correlation (r =0.59) of 210Po and TDP in water. The Kd values in suspended particulate matter are much higher compare to that in dissolved phase, proving that the adsorption of radionuclides to particles is more dominant. This implies that SPM significantly influences the variation of the P compound and both radionuclides in the Mersing River. This corresponds with agricultural activities from palm oil estates; erosion of the river bank due to river runoff; advection of suspended particulates from surface sediment due to boat and ferry traffic at the jetties; sedimentation; domestic sewage from nearby terrestrial areas; and natural processes; all of which might have resulted in their introduction to the Mersing River. (author)

2013-01-01

 
 
 
 
341

Analyzing sound speed fluctuations in shallow water from group-velocity versus phase-velocity data representation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Data collected over more than eight consecutive hours between two source-receiver arrays in a shallow water environment are analyzed through the physics of the waveguide invariant. In particular, the use of vertical arrays on both the source and receiver sides provides source and receiver angles in addition to travel-times associated with a set of eigenray paths in the waveguide. From the travel-times and the source-receiver angles, the eigenrays are projected into a group-velocity versus pha...

2013-01-01

342

Water Hardness Level and ItAND#8217;s Health Effects  

Directory of Open Access Journals (Sweden)

Full Text Available Water hardness is a term used to define the number of ions contained in the water, especially quantity sulphate, carbonate salts of calcium and magnesium. This characteristis of water is a important quality in it’s use as drinking water, industrial water and service water. The temporary hardness level of water cames from bicarbonate salts of calcium and magnesium whereas chloride, sulphate, nitrate, phosphate, silicate salts of calcium and magnesium. In order to indicate the hardness level of water samples French Hardness Level is used in our country. There is a larger amounth of calcium and magnesium salts in hard water samples. These minerals have very important functions in the human body. In this study, the importance of hard water in terms of human health has been assessed under light of current information. The studies about the preventive role of hard water in cardiovascular diseases, cerebrovascular diseases, stroke and many types of cancer areviewed. These studies Express that higher levels of calcium and magnesium hard water provide a higher reduction in these disease. Water, which must be consumed as 2 liters per dayis very important for human life. Hard water contains a lot of the minerals that must be taker daily, especially calcium and magnesium. It’s advised that water for consumption to have medium hardness. The hardness level of water is an aesthetic quality. Thus, in populations having a taste for soft water, the effort of individuals to softer the network water provided by municipalities using different equipments, in addition to their preference of soft water in plastic or glass bottles for consumption could imply lack of benefit of hard water for population health and also bring out some risks in terms of water hygiene. [TAF Prev Med Bull 2011; 10(2.000: 187-192

Necmettin Kocak

2011-04-01

343

Continuous determination of low-level tritium activity in water  

International Nuclear Information System (INIS)

The measurement of sub-nanocurie amounts of tritium in water is of considerable interest to scientists working in environmental, hydrological, and nuclear energy research. Heretofore, the universally accepted method of sampling and batch counting the water in conventional liquid scintillation counters has been considered the only viable method, due to the very long counting time required to obtain statistically significant data. The objective of this paper is to describe research focused on developing a method and instrumentation to monitor very low specific activity tritiated water in a flowing mode

1985-11-01

344

Paleohydrology of the southern Great Basin, with special reference to water table fluctuations beneath the Nevada Test Site during the Late Pleistocene  

Energy Technology Data Exchange (ETDEWEB)

The magnitude of water table rise during Pleistocene pluvial climates, and of the resultant shortening of ground-water flow path and reduction in unsaturated zone thickness, is investigated. The distribution of calcitic veins in alluvium and lakebeds, and of tufa deposits, between the Ash Meadows spring discharge area and the Nevada Test Site suggests that discharge from the regional Paleozoic carbonate aquifer during the Late Pleistocene occurred at distances as much as 14 kilometers northeast of Ash Meadows and at altitudes up to 50 meters higher than at present. Use of the underflow equation (relating discharge to transmissivity, aquifer width, and hydraulic gradient), and various assumptions regarding pluvial recharge, transmissivity, and altitude of ground-water base level, suggest possible rises in potentiometric level in the carbonate aquifer of 6 to 90 meters beneath central Frenchman Flat, 58 kilometers northeast of Ash Meadows. During Wisconsin time the rise probably did not exceed 30 meters. Water-level rises beneath Frenchman Flat during future pluvials are unlikely to exceed 30 meters, and future levels might even be 10 meters lower than the modern one, 210 meters beneath the center of the valley. Neither the cited rise in potentiometric level in the regional carbonate aquifer, nor the shortened flow path during the Late Pleistocene precludes utilization of the NTS as a repository for high-level or transuranic-element radioactive wastes provided other requisite conditions are met at this site. Deep water tables, attendant thick (up to several hundred meter) unsaturated zones, and ground-water flow paths tens of kilometers in length characterized the region during Wisconsin time and possibly throughout the Pleistocene, and are likely to so characterize it during future pluvial climates.

Winograd, I.J.; Doty, G.C.

1980-12-31

345

Paleohydrology of the southern Great Basin, with special reference to water table fluctuations beneath the Nevada Test Site during the Late Pleistocene  

International Nuclear Information System (INIS)

The magnitude of water table rise during Pleistocene pluvial climates, and of the resultant shortening of ground-water flow path and reduction in unsaturated zone thickness, is investigated. The distribution of calcitic veins in alluvium and lakebeds, and of tufa deposits, between the Ash Meadows spring discharge area and the Nevada Test Site suggests that discharge from the regional Paleozoic carbonate aquifer during the Late Pleistocene occurred at distances as much as 14 kilometers northeast of Ash Meadows and at altitudes up to 50 meters higher than at present. Use of the underflow equation (relating discharge to transmissivity, aquifer width, and hydraulic gradient), and various assumptions regarding pluvial recharge, transmissivity, and altitude of ground-water base level, suggest possible rises in potentiometric level in the carbonate aquifer of 6 to 90 meters beneath central Frenchman Flat, 58 kilometers northeast of Ash Meadows. During Wisconsin time the rise probably did not exceed 30 meters. Water-level rises beneath Frenchman Flat during future pluvials are unlikely to exceed 30 meters, and future levels might even be 10 meters lower than the modern one, 210 meters beneath the center of the valley. Neither the cited rise in potentiometric level in the regional carbonate aquifer, nor the shortened flow path during the Late Pleistocene precludes utilization of the NTS as a repository for high-level or transuranic-element radioactive wastes provided other requisite conditions are met at this site. Deep water tables, attendant thick (up to several hundred meter) unsaturated zones, and ground-water flow paths tens of kilometers in length characterized the region during Wisconsin time and possibly throughout the Pleistocene, and are likely to so characterize it during future pluvial climates

1980-01-01

346

Multi-annual fluctuations in reconstructed historical time-series of a European lobster (Homarus gammarus) population disappear at increased exploitation levels.  

Science.gov (United States)

Through the history of ecology, fluctuations of populations have been a dominating topic, and endogenous causes of fluctuations and oscillations have been recognized and studied for more than 80 years. Here we analyzed an historical dataset, covering more than 130 years, of European lobster (Homarus gammarus) catches. The data shows periodic fluctuations, which are first dampened and then disappear over time. The disappearance of the periodicity coincided with a substantial increase in fishing effort and the oscillations have not reappeared in the time series. The shifting baseline syndrome has changed our perception of not only the status of the stock, but also the regulating pressures. We describe the transition of a naturally regulated lobster population into a heavily exploited fisheries controlled stock. This is shown by the incorporation of environmental and endogenous processes in generalized additive models, autocorrelation functions and periodicity analyses of time-series. PMID:23573187

Sundelöf, Andreas; Bartolino, Valerio; Ulmestrand, Mats; Cardinale, Massimiliano

2013-01-01

347

Stochastic modeling of Lake Van water level time series with jumps and multiple trends  

Directory of Open Access Journals (Sweden)

Full Text Available In the 1990s, water level in the closed-basin Lake Van located in the Eastern Anatolia, Turkey, has risen up about 2 m. Analysis of the hydrometeorological data shows that change in the water level is related to the water budget of the lake. In this study, stochastic models are proposed for simulating monthly water level data. Two models considering mono- and multiple-trend time series are developed. The models are derived after removal of trend and periodicity in the dataset. Trend observed in the lake water level time series is fitted by mono- and multiple-trend lines. In the so-called mono-trend model, the time series is treated as a whole under the hypothesis that the lake water level has an increasing trend. In the second model (so-called multiple-trend, the time series is divided into a number of segments to each a linear trend can be fitted separately. Application on the lake water level data shows that four segments, each fitted with a trend line, are meaningful. Both the mono- and multiple-trend models are used for simulation of synthetic lake water level time series under the hypothesis that the observed mono- and multiple-trend structure of the lake water level persist during the simulation period. The multiple-trend model is found better for planning the future infrastructural projects in surrounding areas of the lake as it generates higher maxima for the simulated lake water level.

H. Aksoy

2013-06-01

348

Valence fluctuation phenomena  

International Nuclear Information System (INIS)

Valence fluctuation phenomena occur in rare-earth compounds in which the proximity of the 4f level to the Fermi energy leads to instabilities of the charge configuration (valence) and/or of the magnetic moment. The experimental results observed in the subset of such systems for which the 4f ions form a lattice with identical valence on each site are reviewed. The discussion includes key thermodynamic experiments, such as susceptibility and lattice constant, and spectroscopic experiments such as XPS and neutron scattering. This is followed by a review of existing theoretical work concerning both the ground states and the isomorphic phase transitions which occur in such compounds; the emphasis is on those aspects which make valence fluctuation phenomena such a challenging many-body problem. 391 references. (author)

1981-01-01

349

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Juan José Neiff; Sylvina Lorena Casco; Alicia Poi de Neiff

2008-01-01

350

Rapid fluctuations in flow and water-column properties in Asan Bay, Guam: implications for selective resilience of coral reefs in warming seas  

Science.gov (United States)

Hydrodynamics and water-column properties were investigated off west-central Guam from July 2007 through January 2008. Rapid fluctuations, on time scales of 10s of min, in currents, temperature, salinity, and acoustic backscatter were observed to occur on sub-diurnal frequencies along more than 2 km of the fore reef but not at the reef crest. During periods characterized by higher sea-surface temperatures (SSTs), weaker wind forcing, smaller ocean surface waves, and greater thermal stratification, rapid decreases in temperature and concurrent rapid increases in salinity and acoustic backscatter coincided with onshore-directed near-bed currents and offshore-directed near-surface currents. During the study, these cool-water events, on average, lasted 2.3 h and decreased the water temperature 0.57 °C, increased the salinity 0.25 PSU, and were two orders of magnitude more prevalent during the summer season than the winter. During the summer season when the average satellite-derived SST anomaly was +0.63 °C, these cooling events, on average, lowered the temperature 1.14 °C along the fore reef but only 0.11 °C along the reef crest. The rapid shifts appear to be the result of internal tidal bores pumping cooler, more saline, higher-backscatter oceanic water from depths >50 m over cross-shore distances of 100 s of m into the warmer, less saline waters at depths of 20 m and shallower. Such internal bores appear to have the potential to buffer shallow coral reefs from predicted increases in SSTs by bringing cool, offshore water to shallow coral environments. These cooling internal bores may also provide additional benefits to offset stress such as supplying food to thermally stressed corals, reducing stress due to ultraviolet radiation and/or low salinity, and delivering coral larvae from deeper reefs not impacted by surface thermal stress. Thus, the presence of internal bores might be an important factor locally in the resilience of select coral reefs facing increased thermal stress.

Storlazzi, C. D.; Field, M. E.; Cheriton, O. M.; Presto, M. K.; Logan, J. B.

2013-12-01

351

New Methods to Estimate 2D Water Level Distributions of Dynamic Rivers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

River restoration measures are becoming increasingly popular and are leading to dynamic river bed morphologies that in turn result in complex water level distributions in a river. Disconnected river branches, nonlinear longitudinal water level profiles and morphologically induced lateral water level gradients can evolve rapidly. The modeling of such river-groundwater systems is of high practical relevance in order to assess the impact of restoration measures on the exchange flux between a riv...

Diem, Samuel; Renard, Philippe; Schirmer, Mario

2014-01-01

352