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1

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

2

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

3

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

4

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

5

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

6

Water-level fluctuations, emersion regimes, and variations of echinoid populations on a Caribbean reef flat  

Science.gov (United States)

This paper examines fluctuations in water level over a Caribbean reef flat at Punta Galeta, Panamá. In an analysis of approximately ten years of records, the mean diurnal range of the tides was 24·5 cm and varied <2 cm from year to year. Daily mean water levels varied erratically over a range of approximately 30 cm. Monthly mean water levels fluctuated seasonally over a range of about 10 cm and were consistently higher than those at the regional tidal reference station at Cristóbal. On days with more wave action, water levels at Galeta increased relative to those at Cristóbal, suggesting that waves were 'pumping' water onto the reef flat. The monthly mean water levels at the two sites were not correlated, indicating that tidal data from conventional stations in deeper water cannot be extrapolated to reef flats, except as estimates of minimum potential water levels. Most of the reef flat was within 6 cm vertical span just below mean lower low water. The highest elevations within this range were exposed above water level for an average of 918 hours per year, as compared with 144 hours per year at the lowest elevation. Most exposures lasted less than 10 hours, with a modal duration of 3-5 hours; however, exposures longer than 12 hours occurred at nearly all elevations in all years. Exposures of the reef flat were most frequent between February and June and between August and November, a pattern apparently caused by a combination of seasonal oscillations of regional sea levels, the annual pattern of the solstitial tides, and waves generated by seasonal trade winds. The fluctuations in water levels apparently affected the abundances of some species of sea urchins on the reef flat. Populations of Lytechinus variegatus and Diadema antillarum declined or disappeared from the reef flat during seasons of repeated subaerial exposures, but recolonized the habitat in periods of higher water levels. Although they are reported to suffer heavy mortality during emersion, Echinometra lucunter and E. viridis did not exhibit reductions in abundance that were synchronous with the seasonal exposures of the reef flat.

Cubit, John D.; Windsor, Donald M.; Thompson, Ricardo C.; Burgett, Jeff M.

1986-06-01

7

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

International Nuclear Information System (INIS)

[en] This report presents earthquake-induced water-level and fluid- pressure data for well USW H-5 during April 1992. Well USW H-5 is located in the Yucca Mountain area, Nevada. On April 22,1992 a 6.2-magnitude earthquake occurred in southern California which caused a maximum fluid-pressure change of approximately 50 centimeters in well USW H-5. Within 18 hours on April 25--26, 1992, three major earthquakes occurred in northern California. The water-level responses to these earthquakes were detected in well USW H-5. The maximum water-level fluctuation from the northern California earthquakes was in excess of 52.5 cm

1992-01-01

8

Identification of pumping influences in long-term water level fluctuations.  

UK PubMed Central (United Kingdom)

Identification of the pumping influences at monitoring wells caused by spatially and temporally variable water supply pumping can be a challenging, yet an important hydrogeological task. The information that can be obtained can be critical for conceptualization of the hydrogeological conditions and indications of the zone of influence of the individual pumping wells. However, the pumping influences are often intermittent and small in magnitude with variable production rates from multiple pumping wells. While these difficulties may support an inclination to abandon the existing dataset and conduct a dedicated cross-hole pumping test, that option can be challenging and expensive to coordinate and execute. This paper presents a method that utilizes a simple analytical modeling approach for analysis of a long-term water level record utilizing an inverse modeling approach. The methodology allows the identification of pumping wells influencing the water level fluctuations. Thus, the analysis provides an efficient and cost-effective alternative to designed and coordinated cross-hole pumping tests. We apply this method on a dataset from the Los Alamos National Laboratory site. Our analysis also provides (1) an evaluation of the information content of the transient water level data; (2) indications of potential structures of the aquifer heterogeneity inhibiting or promoting pressure propagation; and (3) guidance for the development of more complicated models requiring detailed specification of the aquifer heterogeneity.

Harp DR; Vesselinov VV

2011-05-01

9

Effects of fluctuations in river water level on virus removal by bank filtration and aquifer passage--a scenario analysis.  

UK PubMed Central (United Kingdom)

Riverbank filtration is an effective process for removing pathogenic viruses from river water. Despite indications that changing hydraulic conditions during floods can affect the efficacy of riverbank filtration to remove viruses, the impact on advection and dispersion of viruses in the riverbank is not well understood. We investigated the effects of fluctuations in river water level on virus transport during riverbank filtration, considering 3-D transient groundwater flow and virus transport. Using constant removal rates from published field experiments with bacteriophages, removal of viruses with distance from the riverbank was simulated for coarse gravel, fine gravel and fine sandy gravel. Our simulations showed that, in comparison with steady flow conditions, fluctuations in river water level cause viruses to be transported further at higher concentrations into the riverbank. A 1-5 m increase in river water levels led to a 2- to 4-log (log10 reduction in concentration relative to the initial concentration in the river) increase in virus concentration and to up to 30% shorter travel times. For particular cases during the receding flood, changing groundwater flow conditions caused that pristine groundwater was carried from further inland and that simulated virus concentrations were more diluted in groundwater. Our study suggests that the adverse effect of water level fluctuations on virus transport should be considered in the simulation of safe setback distances for drinking water supplies.

Derx J; Blaschke AP; Farnleitner AH; Pang L; Blöschl G; Schijven JF

2013-04-01

10

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

11

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

Science.gov (United States)

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.

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

2009-05-01

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

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; A. Chelani; R. K. Chadha; R. N. Singh

2009-01-01

13

Seepage Analysis of Rock-Fill Dam Subjected to Water Level Fluctuation: A case study on Gotvand-Olya Dam  

Directory of Open Access Journals (Sweden)

Full Text Available The Gotvand-Olya Dam is a rock-fill dam, located at Khuzestan province in southwest of Iran. Since the dam is subjected to the daily water level fluctuation, such as rapid drawdown and refill, thus induce a structural impact on the behavior of dam body, it draws many soil engineering concerns. In this paper, seepage analysis of the rock-fill dam was primarily conducted to evaluate the dam safety against the leakage through the dam body. Traditionally, steady-state analysis was employed to investigate the seepage in the dam body, summing that water level is fixed at two cases: high and low water levels. Consequently, it was not able to properly reflect the time-dependent characteristics of seepage phenomena. In this study, seepage analysis was numerically performed using 2-D FEM transient analysis. As a particular boundary condition for an analysis, the water level fluctuation was incorporated to simulate the daily changes. As a result, various seepage phenomena were quantified such as hydraulic gradient, seepage vector and pore water pressure distribution at the corresponding time of interest as the water level rises and recedes. At steady state analysis, the seepage flux at high water level in downstream area was predicted to be 78 l/s. In additions, the seepage flux measured and estimated were both acceptable considering design criteria. The result of this study proves that there is no sign of hazardous sources contributing to the possibility of piping, internal erosion and excess leakage through the dam body.

Ali Beheshti; Amirabbas Kamanbedast; Hossein Akbari

2013-01-01

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

Directory of Open Access Journals (Sweden)

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

FANG Lu-qiu

2010-01-01

15

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

UK PubMed Central (United Kingdom)

Floodplain lakes are especially dynamic due to the irregular flow regime of the Paraná River and its location along the geomorphologic gradient between the lakes and the river. The response of Eichhornia crassipes (Mart.) Solms (one of the most frequent aquatic plant) was studied in two floodplain lakes with different flooding regimes. Samples were taken between March 1997 and December 2001 on 13 different hydrologic conditions during prolonged hydrologic connection and prolonged hydrologic isolation. Leaf height, leaf density, biomass and nutrient content of the mature leaves of E. crassipes were measured and related to water level fluctuation and the hydrologic connectivity. The lake more connected with the main channel had a long lasting inundation phase. In this condition the surface area covered by water increased more than three times compared to prolonged hydrologic isolation condition. As river water entered the floodplain lakes, dissolved inorganic nitrogen increased to high values, especially NO3-, whereas the isolation condition was characterised by a decrease in NO3 concentrations to undetectable levels. Compared to plants growing in the more isolated lake, those growing in the more connected lake had a significantly lower leaf density, longer leaves, less root biomass and lower ratio between below-ground and above-ground biomasses. However, total and leaf biomasses were not significantly different between sites. In each lake, differences in leaf height, leaf biomass and root biomass between prolonged hydrologic connection and isolation, as well as the insignificant relationship between leaf size and leaf density, indicate that the morphological traits of E. crassipes respond to pluri-annual water level fluctuations. The highest nutrient concentration in mature leaves was registered at the end of the prolonged hydrologic connection in the more connected lake. During the prolonged isolation, leaves had more lignin and a higher L:N ratio than at high waters, at the same sites. The success of E. crassipes in occupying habitats subjected to wide and erratic fluctuations in water level, such as the Parana River floodplain, appears to be related to its ability to modify morphological traits according to water level.

Neiff JJ; Casco SL; Poi de Neiff A

2008-06-01

16

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)

2000-01-01

17

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.

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

2013-01-01

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Water-level fluctuations of Lake Tanganyika in phase with oceanic changes during the last glaciation and deglaciation  

Science.gov (United States)

THERE has been considerable controversy about the magnitude of fluctuations of the levels of Lake Tanganyika, the Earth's second deepest lake (1,470 m), following the discovery of submerged valleys extending down to 550 m below present lake levels1. These fluctuations register changes in the precipitation/(evaporation + evapotranspiration) ratio in a large equatorial-tropical area of catchment, south of the Equator. Here we report new palaeohydrological data, back to 40 kyr BP, from carbon dating of the total organic matter in two diatomaceous cores. The results constrain the vertical lake level fluctuations more than has hitherto been possible2-5 and show that the fluctuations from 26 kyr BP are correlated with changes in global sea level and ice volume. Surpris-ingly fluctuations seem to be in phase with those of the African lakes north of the Equator, which are clearly linked to the Milankovitch mechanisms.

Gasse, Franpoise; Lédée, Vincent; Massault, Marc; Fontes, Jean-Charles

1989-11-01

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

UK PubMed Central (United Kingdom)

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.

Nevado B; Mautner S; Sturmbauer C; Verheyen E

2013-08-01

20

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

2013-07-10

 
 
 
 
21

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.

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

2013-01-01

22

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

UK PubMed Central (United Kingdom)

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.

Koblmüller S; Salzburger W; Obermüller B; Eigner E; Sturmbauer C; Sefc KM

2011-06-01

23

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

2011-04-22

24

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

Directory of Open Access Journals (Sweden)

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

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

2008-01-01

25

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

26

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Establishment of Tabebuia cassinoides seedlings is related to water-level fluctuations in southeastern Brazil swamp forests. Nine years of annual monitoring of 48 individuals established during a drought in November 1997, when the swamp was unflooded, suggested that their establishment depends on th...

Mariana de Andrade Iguatemy; Pablo José Francisco Pena Rodrigues

27

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

UK PubMed Central (United Kingdom)

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

Ye C; Cheng X; Zhang Q

2013-09-01

28

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  

Energy Technology Data Exchange (ETDEWEB)

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

NONE

1995-08-01

29

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

30

Comparison between Neural Networks and Adaptive Neuro-fuzzy Inference System in Modeling Lake Kerkini Water Level Fluctuation Lake Management using Artificial Intelligence  

Directory of Open Access Journals (Sweden)

Full Text Available This study presents lake Kerkini water level simulation. Water level depends on a large number of parameters and procedures which are usually complex or non-linear. Water level was calculated, by using a model based on visual basic language. The model took account of all parameters that contribute to water level. Simulation was achieved when the model output approximated the available measured values. Afterwards, the same project was implemented by using artificial intelligence methods. These are, artificial neural networks and adaptive neuro fuzzy inference system. The basic advantage of this implementation is the fact that the output is obtained without having to use all the parameters that contribute to the final result. This means that they can be implemented for modeling systems where the procedures are not fully known or when there is a large parameter number affecting the result. Both models showed a great performance in simulating water level fluctuation and they are also suggested for prediction.

Leonidas Mpallas; Cristos Tzimopoulos; Christos Evangelides

2011-01-01

31

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

32

Density fluctuations in liquid water.  

UK PubMed Central (United Kingdom)

The density distributions and fluctuations in grids of varying size in liquid water at ambient pressure, both above the freezing point and in the supercooled state, are analyzed from the trajectories obtained from large-scale molecular dynamics simulations. It is found that the occurrence of low- and high-density regions (LDL and HDL) is transient and their respective residence times are dependent on the size of the simulated system. The spatial extent of density-density correlation is found to be within 7 Å or less. The temporal existence of LDL and HDL arises as a result of natural density fluctuations of an equilibrium system. The density of bulk water at ambient conditions is homogenous.

English NJ; Tse JS

2011-01-01

33

Changes in rotifer communities regarding to the water-level fluctuations in the floodplain Gemenc, Danube (Hungary)  

Directory of Open Access Journals (Sweden)

Full Text Available The planktonic rotifer communities in three hydrodynamicaly different river-arms at the floodplain of the Danube River at Gemenc have been studied. In the numerous arms the current has different speeds depending on the water level, therefore the physical and chemical parameters (temperature, conductivity, transparency, dissolved oxygen content) are different. We have found forty-six rotifer taxa in the area, but the species-composition changes seasonally. There are therefore big differences in the qualitative and quantitative data between the main arm and the other branches. At high water levels (flood), the rotifer communities of the area are uniformized but, at low water levels the area becomes divided into a series of different water bodies, some near to the lake-state. This phenomenon develops a few days after the flood. The species composition and the abundance relations of the planktonic rotifer communities reflect this effect.

Schöll, K.

2006-01-01

34

[Soil seed bank and its correlations with aboveground vegetation and environmental factors in water level fluctuating zone of Danjiangkou Reservoir, Central China].  

UK PubMed Central (United Kingdom)

Taking the water level fluctuating zone of the Danjiangkou Reservoir as a case, and by the method of hierarchical cluster analysis, the soil seed banks at 37 sampling plots within the areas of 140-145 m elevation were divided into 6 groups, and the species composition, density, and diversity of the soil seed banks among the groups were compared. The differences between the soil seed banks and the aboveground vegetations were analyzed by S0rensen similarity coefficient, and the correlations among the soil seed banks, aboveground vegetations, and environmental factors were explored by principal component analysis (PCA) and multivariable regression analysis. At the same altitudes of the water level fluctuating zone, the species composition of the soil seed banks had obvious heterogeneity, and the density and diversity indices of the soil seed banks among different groups were great. The similarity coefficient between the soil seed banks and aboveground vegetations was low, and the species number in the soil seed banks was obviously lesser than that in the aboveground vegetations. The density of the soil seed banks was highly positively correlated with the aboveground vegetations coverage and species number and the soil texture, but highly negatively correlated with the soil water-holding capacity and soil porosity.

Liu RX; Zhan J; Shi ZH; Chen LQ

2013-03-01

35

Level Dynamics and Universality of Spectral Fluctuations  

CERN Document Server

The spectral fluctuations of quantum (or wave) systems with a chaotic classical (or ray) limit are mostly universal and faithful to random-matrix theory. Taking up ideas of Pechukas and Yukawa we demonstrate that equilibrium statistical mechanics for the fictitious gas of interacting particles associated with the parametric motion of levels yields spectral fluctuations of the random-matrix type. Clues are the choice of an appropriate equilibrium ensemble, a certain ergodicity of level dynamics and estimates for the frequency of avoided crossings of neighboring levels. While equilibrium statistical mechanics only predicts the average behavior of a family of dynamical systems over a certain range of a control parameter we show that the family coalesces to a single system in the classical limit. Our arguments also reveal that integrable dynamics cannot produce universal spectral fluctuations since their parametric level dynamics correspond to near ideal-gas behavior of the Pechukas-Yukawa gas.

Braun, P A; Haake, F; Kus, M; Zyczkowski, K; Braun, Peter; Gnutzmann, Sven; Haake, Fritz; Kus, Marek; Zyczkowski, Karol

2000-01-01

36

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.

YUAN Xing-zhong; XIONG Sen; LIU Hong; LI Bo; WANG Qiang

2012-01-01

37

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

38

Global Warming and Caspian Sea Level Fluctuations  

CERN Document Server

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

Ardakanian, Reza

2013-01-01

39

Assessing heavy metal pollution in the water level fluctuation zone of China's Three Gorges Reservoir using geochemical and soil microbial approaches.  

UK PubMed Central (United Kingdom)

The water level fluctuation zone (WLFZ) in the Three Gorges Reservoir is located in the intersection of terrestrial and aquatic ecosystems, and assessing heavy metal pollution in the drown zone is critical for ecological remediation and water conservation. In this study, soils were collected in June and September 2009 in natural recovery area and revegetation area of the WLFZ, and geochemical approaches including geoaccumulation index (I (geo)) and factor analysis and soil microbial community structure were applied to assess the spatial variability and evaluate the influence of revegetation on metals in the WLFZ. Geochemical approaches demonstrated the moderate pollutant of Cd, the slight pollutant of Hg, and four types of pollutant sources including industrial and domestic wastewater, natural rock weathering, traffic exhaust, and crustal materials in the WLFZ. Our results also demonstrated significantly lower concentrations for elements of As, Cd, Pb, Zn, and Mn in the revegetation area. Moreover, soil microbial community structure failed to monitor the heavy metal pollution in such a relatively clean area. Our results suggest that revegetation plays an important role in controlling heavy metal pollution in the WLFZ of the Three Gorges Reservoir, China.

Ye C; Li S; Zhang Y; Tong X; Zhang Q

2013-01-01

40

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

Directory of Open Access Journals (Sweden)

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

Anderson Medeiros dos Santos; Francisco de Assis Esteves

2004-01-01

 
 
 
 
41

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

Science.gov (United States)

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

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

2010-12-01

42

Lowest Landau level diamagnetic fluctuations in niobium  

International Nuclear Information System (INIS)

[en] We have performed a magnetic study of a bulk metallic sample of Nb with critical temperature Tc = 8.5 K. Magnetization measurements taken for magnetic fields greater than 1 kOe show a superconducting transition that becomes broader as the field is increased. The data are well described by lowest Landau level (LLL) fluctuation theory. A scaling analysis yields values for the superconducting transition temperature under field Tc(H) which are consistent with Hc2(T)

2004-01-01

43

Plant community characteristics and their responses to environmental factors in the water level fluctuation zone of the three gorges reservoir in China.  

UK PubMed Central (United Kingdom)

The annual water level regulating of the Three Gorges Reservoir prolonged the submerged duration (from 2 to 8 months) and resulted in the reversal of natural flood rhythms (winter submerged). These changes might alter plant community characteristics in the water level fluctuation zone (WLFZ). The aim of this study was to determine the plant community characteristics in the WLFZ and their responses to the environmental factors (i.e., annual hydrological regulation, topographic characteristics, soil physical properties and soil nutrients). The height, coverage, frequency and biomass of each plant species and the soil properties at each elevation zone (150, 155, 160, 165 and 170 m) were measured from March to September in 2010. Univariate two-factor analysis and redundancy analysis (RDA) were used to analyze the spatial and temporal variations of the community characteristics and identify the key environmental factors influencing vegetation. We found that 93.2 % of the species analysed were terrestrial vascular plants. Annual herbs made up the highest percentage of life forms at each altitude. The differences in the species number per square metre, the Shannon-Wiener diversity index and the biomass of vegetation demonstrated statistical significance with respect to sampling time but not elevation. The most dominant species at altitudes of 150, 155, 160, 165 and 170 m were Cynodon dactylon, Cyperus rotundus, Digitaria sanguinalis, Setaria viridis and Daucus carota, respectively. The concentrations of soil nutrients appeared to be the lowest at an altitude of 150 m, although the differences with respect to elevation were not significant. The results of the RDA indicated that the key factors that influenced the species composition of vegetation were elevation, slope, pH and the concentration of soil available phosphorus.

Zhang Z; Wan C; Zheng Z; Hu L; Feng K; Chang J; Xie P

2013-10-01

44

Plant community characteristics and their responses to environmental factors in the water level fluctuation zone of the three gorges reservoir in China.  

UK PubMed Central (United Kingdom)

The annual water level regulating of the Three Gorges Reservoir prolonged the submerged duration (from 2 to 8 months) and resulted in the reversal of natural flood rhythms (winter submerged). These changes might alter plant community characteristics in the water level fluctuation zone (WLFZ). The aim of this study was to determine the plant community characteristics in the WLFZ and their responses to the environmental factors (i.e., annual hydrological regulation, topographic characteristics, soil physical properties and soil nutrients). The height, coverage, frequency and biomass of each plant species and the soil properties at each elevation zone (150, 155, 160, 165 and 170 m) were measured from March to September in 2010. Univariate two-factor analysis and redundancy analysis (RDA) were used to analyze the spatial and temporal variations of the community characteristics and identify the key environmental factors influencing vegetation. We found that 93.2 % of the species analysed were terrestrial vascular plants. Annual herbs made up the highest percentage of life forms at each altitude. The differences in the species number per square metre, the Shannon-Wiener diversity index and the biomass of vegetation demonstrated statistical significance with respect to sampling time but not elevation. The most dominant species at altitudes of 150, 155, 160, 165 and 170 m were Cynodon dactylon, Cyperus rotundus, Digitaria sanguinalis, Setaria viridis and Daucus carota, respectively. The concentrations of soil nutrients appeared to be the lowest at an altitude of 150 m, although the differences with respect to elevation were not significant. The results of the RDA indicated that the key factors that influenced the species composition of vegetation were elevation, slope, pH and the concentration of soil available phosphorus.

Zhang Z; Wan C; Zheng Z; Hu L; Feng K; Chang J; Xie P

2013-04-01

45

Plant community characteristics and their responses to environmental factors in the water level fluctuation zone of the three gorges reservoir in China.  

Science.gov (United States)

The annual water level regulating of the Three Gorges Reservoir prolonged the submerged duration (from 2 to 8 months) and resulted in the reversal of natural flood rhythms (winter submerged). These changes might alter plant community characteristics in the water level fluctuation zone (WLFZ). The aim of this study was to determine the plant community characteristics in the WLFZ and their responses to the environmental factors (i.e., annual hydrological regulation, topographic characteristics, soil physical properties and soil nutrients). The height, coverage, frequency and biomass of each plant species and the soil properties at each elevation zone (150, 155, 160, 165 and 170 m) were measured from March to September in 2010. Univariate two-factor analysis and redundancy analysis (RDA) were used to analyze the spatial and temporal variations of the community characteristics and identify the key environmental factors influencing vegetation. We found that 93.2 % of the species analysed were terrestrial vascular plants. Annual herbs made up the highest percentage of life forms at each altitude. The differences in the species number per square metre, the Shannon-Wiener diversity index and the biomass of vegetation demonstrated statistical significance with respect to sampling time but not elevation. The most dominant species at altitudes of 150, 155, 160, 165 and 170 m were Cynodon dactylon, Cyperus rotundus, Digitaria sanguinalis, Setaria viridis and Daucus carota, respectively. The concentrations of soil nutrients appeared to be the lowest at an altitude of 150 m, although the differences with respect to elevation were not significant. The results of the RDA indicated that the key factors that influenced the species composition of vegetation were elevation, slope, pH and the concentration of soil available phosphorus. PMID:23589274

Zhang, Zhiyong; Wan, Chengyan; Zheng, Zhiwei; Hu, Lian; Feng, Kun; Chang, Jianbo; Xie, Ping

2013-04-16

46

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

UK PubMed Central (United Kingdom)

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.

Ye C; Zhang K; Deng Q; Zhang Q

2013-03-01

47

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

UK PubMed Central (United Kingdom)

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

Sun WB; Du B; Zhao XL; He BH

2013-03-01

48

River and cooling water temperature fluctuations  

International Nuclear Information System (INIS)

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

1976-01-01

49

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 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 zooplanctófagas de Chirostoma en quince sitios del Lago de Chapala, México, reveló una influencia estadísticamente significativa en las condiciones contrastantes (P=0.0002). Esta (more) cionalmente, 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 Chapala, Mexico, revealed the significant influence of contrasting conditions (P=0.0002). Seasonally, segregation was more related to species dominance in the dry season and exclusiv (more) ely 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.

2011-01-01

50

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 Chapala, 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.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 zooplanctófagas 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.

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

2011-01-01

51

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

52

Effect of entrapped gas on peatland surface level fluctuations  

Science.gov (United States)

Peat is a highly compressible medium and changes in peat surface level in response to shifts in water storage and entrapped gas volume have been reported previously. Since both peat compressibility and capacity to entrap gas are related to peat structure, we hypothesize that the relationship between water table and surface level may vary across a peatland. The objective of this study is to investigate the relationships between peat surface level positions, water table positions and subsurface gas pools at local topographic low-lying areas within a poor fen, which differ in peat properties and vegetation cover. Three sites were investigated, two with highly movable surfaces (FA and FB) and one which was more stable (NF). Deviations from the water table position-surface level position relationship (residuals) appear to be related to changes in atmospheric pressure. However, this relationship varied between FA and NF. The differences in these relationships were supported by distinct patterns of gas dynamics between these sites. Ebullition tended to occur only during periods of falling atmospheric pressure at FA, whereas it occurred much more frequently at NF without atmospheric pressure being the primary control. Evidence of ebullition based on changes in volumetric water content below the water table were supported by ebullition measured by surface gas traps and by shifts in pore water pressure deviation. These different responses of surface level fluctuations to changes in atmospheric pressure between sampling locations are likely related to variations in peat properties between the sites. Copyright

Strack, M.; Kellner, E.; Waddington, J. M.

2006-11-01

53

Fluctuation and localization of acoustic waves in bubbly water  

CERN Document Server

Here the fluctuation properties of acoustic localization in bubbly water is explored. We show that the strong localization can occur in such a system for a certain frequency range and sufficient filling fractions of air-bubbles. Two fluctuating quantities are considered, that is, the fluctuation of transmission and the fluctuation of the phase of acoustic wave fields. When localization occurs, these fluctuations tend to vanish, a feature able to uniquely identify the phenomenon of wave localization.

Kuo, C H; Ye, Z; Kuo, Chao-Hsien; Wang, Ken Kang-Hsin; Ye, Zhen

2003-01-01

54

Seed submergence tolerance of four annual species growing in the water-level-fluctuation zone of Three Gorges Reservoir, China, and effects of long-term submergence on their seed germination  

Directory of Open Access Journals (Sweden)

Full Text Available Aims Our objective was to examine seeds of Echinochloa crusgalli, Xanthium sibiricum, Aeschynomene indica and Polygonum hydropiper, four common annual species growing in the water-level-fluctuation zone of Three Gorges Reservoir in China, in regard to tolerance of submergence and germination in the changing environment of the zone.Methods We divided the water-level-fluctuation zone into nine elevational zones according to the Wusong Elevation criterion. We then observed seed submergence tolerance and the effects of submergence on seed germination in a “water impoundment-water recession” cycle after seeds of the four species were sown in the nine elevational zones. Seed germination was divided into seeds with and without sand sediment on surface.Important findings Ripe seeds (or fruits) of the four species kept their vitality after submergence. The starting time for seed germination after the end of submergence and seed germination duration both gradually decreased with decreasing elevation (p < 0.01), and the starting time for seed germination was significantly reduced below 169 m (p < 0.01). Overall, within the same elevational zone, the starting time for seed germination after the end of submergence was longest for A. indica, followed by X. sibiricum, and shortest for P. hydropiper. For E. crusgalli, X. sibiricum and P. hydropiper, seed germination percentage first increased and then decreased with decreasing elevation, while it decreased for A. indica. Sand sedimentation had little effect on seed germination; the effect was positive for X. sibiricum and negative for A. indica. We concluded that seeds (or fruits) of the four annuals can tolerate submergence and germinate successfully in the changing environment of water-level-fluctuation zone. Therefore, these species are useful in the revegetation and restoration of this zone of the Three Gorges Reservoir.

SHEN Jian-Hong; ZENG Bo; LEI Shu-Tong; SU Xiao-Lei; HUANG Wen-Jun

2011-01-01

55

Hydrophobic nanoconfinement suppresses fluctuations in supercooled water.  

UK PubMed Central (United Kingdom)

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 EG; Mazza MG; Stanley HE; Franzese G

2012-02-01

56

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. PMID:22277682

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

2012-01-25

57

Spatial-temporal Dynamics of Vegetation in the Newly Created Water-level-fluctuation Zone of Three Gorges Reservoir:a Case Study in Baijia Stream, Kaixian County, China  

Directory of Open Access Journals (Sweden)

Full Text Available "After impoundent of the Three Gorges Reservoir, a large permanent sample plot was placed in its water-level-fluctuation zone beside Baijia Stream, Kaixian County, China. Vegetation in the plot was investigated in the summer of 2008,2009 and 2010. The result indicated that community' s component, biodiversity and aboveground biomass showed obvious spatial-temporal dynamics. Total spiecies number of vascular flora inside decreased yearly, from 52 species in 2008 to 41 species in 2009 and to 35 species in 2010. The area below 156 m in elevation was dominated by Paspalum paspaloides andXanthium sibiricum in 2008. However, Paspalum paspaloides was rapid replaced by Cynodon dactylo in 2009 and X. sibiricum expanded its distribution in upper area of the plot. In 2010, X. sibiricum depressed its population in lower areas of the plot as the Three Gorges Reservoir started to impound half month earlier in the winter of 2009 and decreased seed bank for its germination. Shannon-Wiener Index increased as elevation according to the data of 2009 and 2010, which reflected the influ-ence of submerged gradient. Aboveground biomass of vegetation in each elevation zone of the plot indicated great variation.Key words: Three Gorges Reservoir; water-level-fluctuation zone; vegetation; spatial-temporal dynamics; biodiversity"

WANG Qiang; LIU Hong; ZHANG Yue-wei; XIONG Sen; YUAN Xing-zhong

2012-01-01

58

Flux Lattice Melting and Lowest Landau Level Fluctuations  

CERN Multimedia

We discuss the influence of lowest Landau level (LLL) fluctuations near H_{c2}(T) on flux lattice melting in YBa$_2$Cu$_3$O$_{7-\\delta}$ (YBCO). We show that the specific heat step of the flux lattice melting transition in YBCO single crystals can be attributed largely to the degrees of freedom associated with LLL fluctuations. These degrees of freedom have already been shown to account for most of the latent heat. We also show that these results are a consequence of the correspondence between flux lattice melting and the onset of LLL fluctuations.

Pierson, S W; Pierson, Stephen W.; Valls, Oriol T.

1998-01-01

59

Air encapsulation. II. Profile water storage and shallow water table fluctuations  

International Nuclear Information System (INIS)

[en] In a wet soil, volumetric encapsulated air contents can easily approach 0.06 m3 m-3. The objective of this study was to determine, through simulation, the effect of air encapsulation on profile water storage and shallow water table fluctuations and whether air encapsulation should be considered in modeling field events. Using a two-dimensional soil moisture code that included a routine designed to model air encapsulation, the authors simulated profile water storage changes during hypothetical rainfall events and water table responses during actual rainfall events. The simulation results indicated that, following the infiltration of 10 mm of water, profile moisture content differences with and without air encapsulation would be 3 m-3 and thus may not be measurable in the field with a neutron probe. Water table levels, however, rose significantly higher in the profile when air was encapsulated. Depending on the initial depth of the water table and the moisture characteristic, the water table rises were two to five times those when air was not encapsulated. For water tables located within 1.3 m of the surface, application of the model to actual rainfall events improved the fit to the measured water table data. In those situations where water table level predictions are important (e.g., wetlands, stream banks), researchers should consider air encapsulation in their analysis of water table fluctuations

1986-12-05

60

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

 
 
 
 
61

A mathematical model for the transmission of Schistosoma japonicum in consideration of seasonal water level fluctuations of Poyang Lake in Jiangxi, China.  

UK PubMed Central (United Kingdom)

BACKGROUND: Poyang Lake, the largest fresh water lake in China, is the major transmission site of Schistosoma japonicum in China. Epidemics of schistosomiasis japonica have threatened the health of residents and stunted social-economic development there. OBJECTIVE: This article aims at evaluating the effect of various control measures against schistosomiasis: selective mass treatment (ST), targeted mass treatment (TT), mass treatment for animal reservoirs (MT), and health education (HE), on reduction of the prevalence through simulations based on a mathematical model. METHODS: We proposed a mathematical model, which is a system of ordinary differential equations for the transmission of S. japonicum among humans, bovines, and snails. The model takes into account the seasonal variation of the water level of Poyang Lake that is caused by the backflow of the Yangtze River and inflow from five small rivers, which influences the transmission of S. japonicum. For the purpose of dealing with the age-specific prevalence and intensity of infection, the human population was classified into four age categories in the model. We carried out several simulations resulting from the execution of ST and TT for elementary school children (E Sch), and combinations of ST, MT, and HE. RESULTS: The simulations indicated that all of the control measures only for humans had a trend of revival after interruption, and a combination of ST and MT has a significant effect on reducing human infection. Although TT and HE had a significant effect on the prevalence in the E Sch group, it had little effect on the overall human population. CONCLUSION: The simulations indicate that measures targeted to bovines such as chemotherapy besides humans will be vital to eliminate the transmission of S. japonicum in the Poyang Lake region. Moreover, it is desirable to improve health education for fishermen and herdsmen.

Xiang J; Chen H; Ishikawa H

2013-04-01

62

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; Nora Sihvola; Riitta Korpela

2012-01-01

63

Dietary factors and fluctuating levels of melatonin.  

UK PubMed Central (United Kingdom)

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.

Peuhkuri K; Sihvola N; Korpela R

2012-01-01

64

A Bayesian two-level model for fluctuation assay.  

UK PubMed Central (United Kingdom)

The fluctuation experiment is an essential tool for measuring microbial mutation rates in the laboratory. When inferring the mutation rate from an experiment, one assumes that the number of mutants in each test tube follows a common distribution. This assumption conceptually restricts the scope of applicability of fluctuation assay. We relax this assumption by proposing a Bayesian two-level model, under which an experiment-wide average mutation rate can be defined. The new model suggests a gamma mixture of the Luria-Delbrück distribution, which coincides with a recently discovered discrete distribution. While the mixture model is of considerable independent interest in fluctuation assay, it also offers a practical Markov chain Monte Carlo method for estimating mutation rates. We illustrate the Bayesian approach with a detailed analysis of an actual fluctuation experiment.

Zheng Q

2011-12-01

65

Capillary effect on water table fluctuations in unconfined aquifers  

Science.gov (United States)

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

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

2013-05-01

66

Lower limit for the velocity fluctuation level in wind tunnels  

Energy Technology Data Exchange (ETDEWEB)

The origins of the velocity fluctuations in the test section of a wind tunnel are discussed. Vorticity (turbulence convected from upstream) can be reduced by a careful design of the settling chamber to almost any desired level. The amplitudes of pressure waves propagating round the tunnel circuit can also be reduced considerably. The lowest level of the velocity fluctuations in wind tunnels are determined by those pressure fields that are created on the outer boundaries of the test section. These boundaries are the free shear layers in the case of free jet facilities and the turbulent boundary layers in the case of closed wall test sections. The lower limit for the rms velocity level is achieved in many open jet wind tunnels (typically 0.15%). The corresponding limit for low speed tunnels with closed test sections is smaller by a factor of at least twenty but not yet known.

Michel, U.; Froebel, E.

1988-01-01

67

[Effects of turbulent fluctuation intensity on the growth of algae and water environment].  

UK PubMed Central (United Kingdom)

Through a self-designed vertically oscillating grid experiment device, the experiment was carried out to research the effects of the turbulence fluctuation intensity on the growth of algae and water environment in the water with adequate nutrients by changing the vibration frequency under a certain light and temperature conditions. The results showed that: the turbulent fluctuation has significant effects on algae growing that weak turbulence fluctuation can promote the growth of algae and strong turbulence fluctuation will inhibit the growth of algae in the range of experimental level. With the increase of the turbulent fluctuation intensity, the peak of algal biomass gradually delayed. Changes of nitrogen and phosphorus in the experimental process have significant differences, when the vibration frequency was up to 2.0 Hz, the maximum reduction of TN and TP were 55.2% and 69.0% lower compared with 0.5 Hz, which was closely associated with the growth of algae. With the intensity of turbulent fluctuation increases, nitrogen-phosphorus ratio first increases and then decreases corresponding to the peak of the algal biomass. Turbulent fluctuation can promote the pH and, dissolved oxygen quickly adjusted to the level of algae growing required, and the most appropriate value remains unchanged.

Lei Y; Long TY; San L; An Q; Huang NQ

2013-05-01

68

GROUND WATER FLUCTUATIONS IN THE KANOLA WATERSHED BASIN OF KARMALA TAHSIL, SOLAPUR DISTRICT, MAHARASHTRA  

Directory of Open Access Journals (Sweden)

Full Text Available Water level fluctuations and depletion of the groundwater are the major problem in the drought prone area. Just deepening of well with heavy capital investment is not a proper solution. The problem is aggravated especially in the summer season. It has direct bearing on food security and poverty. The present study has attempted to understand fluctuations in the ground water levels in a Kanola watershed basin in the drought affected areas of Maharashtra state. The study concludes that it is necessary to undertake watershed development programmes in the basin taking into account specific site factors to ensure groundwater availability for longer period in a year.

PANDURANG Y. PATIL; PRAVEEN SAPTARSHI

2013-01-01

69

Ground Water Fluctuations In The Kanola Watershed Basin Of Karmala Tahsil, Solapur District, Maharashtra  

Directory of Open Access Journals (Sweden)

Full Text Available Water level fluctuations and depletion of the groundwater are the major problem in the drought prone area. Just deepening of well with heavy capital investment is not a proper solution. The problem is aggravated especially in the summer season. It has direct bearing on food security and poverty. The present study has attempted to understand fluctuations in the ground water levels in a Kanola watershed basin in the drought affected areas of Maharashtra state. The study concludes that it is necessary to undertake watershed development programmes in the basin taking into account specific site factors to ensure groundwater availability for longer period in a year.

Pandurang Y. Patil; Praveen Saptarshi

2013-01-01

70

Mass loss from LNAPL pools under fluctuating water table conditions  

Energy Technology Data Exchange (ETDEWEB)

Nonaqueous-phase liquids less dense than water (LNAPLs) form pools at the ground-water table, when leaked in sufficient quantities into the subsurface. Subsequent fluctuations of the ground-water table create a smear zone in the vicinity of the water table with the LNAPLs trapped in the pore spaces in the form of blobs. In addition to the pool, these blobs participate in dissolution and biodegradation processes in the saturated zone. A quantitative method is developed to evaluate mass loss of LNAPLs in the saturated zone under fluctuating water table conditions. A mathematical scheme is used to transform the moving domain to a stationary domain and the transformed advective-dispersive-reaction equation is solved numerically. The mass loss is computed in terms of two components: (1) Biodegradation within the domain; and (2) advective flux leaving the domain. The results indicate that the fluctuating water table conditions enhance the mass loss inasmuch as the entrapped blobs contribute to dissolution and biodegradation processes. Analysis of mass loss as a function of the Damkoehler number (Da) indicates that biodegradation increases the mass removal from the system only after Da exceeds 0.1. Furthermore, for Da > 0.1, the biodegradation of solute dissolved from the entrapped blobs enhances the mass loss from the pool to a much greater extent than when no entrapped blobs exist under static water table conditions.

Reddi, L.N.; Han, W. [Kansas State Univ., Manhattan, KS (United States). Dept. of Civil Engineering; Banks, M.K. [Purdue Univ., West Lafayette, IN (United States). School of Civil Engineering

1998-12-01

71

Dynamical Fluctuating Charge Force Fields Application to Liquid Water  

CERN Multimedia

A new molecular dynamics model in which the point charges on atomic sites are allowed to fluctuate in response to the environment is developed and applied to water. The idea for treating charges as variables is based on the concept of electronegativity equalization according to which: (a) The electronegativity of an atomic site is dependent on the atom's type and charge and is perturbed by the electrostatic potential it experiences from its neighbors and (b) Charge is transferred between atomic sites in such a way that electronegativities are equalized. The charges are treated as dynamical variables using an extended Lagrangian method in which the charges are given a fictitious mass, velocities and kinetic energy and then propagated according to Newtonian mechanics along with the atomic degrees of freedom. Models for water with fluctuating charges are developed using the geometries of two common fixed-charge water potentials: the simple point charge (SPC) and the 4-point transferable intermolecular potential ...

Rick, S W; Berne, B J; Rick, Steven W.; Stuart, Steven J.

1994-01-01

72

Different levels of cortical excitability reflect clinical fluctuations in migraine.  

UK PubMed Central (United Kingdom)

BACKGROUND: In a previous study we demonstrated that high-frequency oscillations (HFOs) elicited by median nerve stimulation are significantly correlated to clinical fluctuations of migraine. We aimed at verifying whether clinical fluctuations and HFO changes are correlated to N20 somatosensory evoked potential (SEP) recovery cycle, which is likely to reflect the functional refractoriness of primary somatosensory cortex neurons. METHODS: We analysed both HFOs and N20 SEP recovery cycle to paired stimulation in 21 migraine patients and 18 healthy volunteers. RESULTS: Shortened recovery cycle correlated with low-amplitude HFOs as well as with clinical worsening. By contrast, prolonged recovery cycle correlated with enhanced HFOs, as well as with spontaneous clinical improvement. CONCLUSIONS: In our migraine patients the strict relationship between presynaptic HFO amplitude and N20 recovery function suggests that changes of both parameters might be caused by modifications of the thalamo-cortical drive. Our findings suggest that the thalamo-cortical drive during interictal stages could fluctuate from abnormally high to abnormally low levels, depending on mechanisms which reduce cortical excitability in spontaneously improving patients, and increase cortical excitability in spontaneously worsening ones.

Restuccia D; Vollono C; del Piero I; Martucci L; Zanini S

2013-09-01

73

Mesoscale wind fluctuations over Danish waters  

DEFF Research Database (Denmark)

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

Vincent, Claire Louise

2010-01-01

74

Calibration of Atmospherically Induced Delay Fluctuations due to Water Vapor  

Science.gov (United States)

We have completed a new generation of water vapor radiometers (WVR) , the A- series, in order to support radio science experiments with the Cassini spacecraft. These new instruments sense three frequencies in the vicinity of the 22 GHz emission line of atmospheric water vapor within a 1 degree beamwidth from a clear aperture antenna that is co-pointed with the radio telescope down to 10 degree elevation. The radiometer electronics features almost an order of magnitude improvement in temperature stability compared with earlier WVR designs. For many radio science experiments, the error budget is likely to be dominated by path delay fluctuations due to variable atmospheric water vapor along the line-of-sight to the spacecraft. In order to demonstrate the performance of these new WVRs we are attempting to calibrate the delay fluctuations as seen by a radio interferometer operating over a 21 km baseline with a WVR near each antenna. The characteristics of these new WVRs will be described and the results of our preliminary analysis will be presented indicating an accuracy of 0.2 to 0.5 mm in tracking path delay fluctuations over time scales of 10 to 10,000 seconds.

Resch, George; Jacobs, Christopher; Keihm, Steve; Lanyi, Gabor; Naudet, Charles; Riley, Abraham; Rosenberger, Hans; Tanner, Alan

2000-05-01

75

Oxygenation of anoxic water in a fluctuating water table system: An experimental and numerical study.  

Energy Technology Data Exchange (ETDEWEB)

A side effect of in situ groundwater remediation techniques that operate by establishing reducing conditions within an aquifer is that anoxic water exits these zones, posing a potential risk to aquatic organisms inhabiting areas of groundwater discharge downgradient from the site. A number of processes have been identified that can attenuate an anoxic plume in an unconfined aquifer with a fluctuating water table. The hypothesis that water table fluctuations increase oxygen transfer from air to water, through enhanced exchange from entrapped air, is tested in an intermediate-scale, fluctuating water table experiment. A dual-energy gamma radiation system was used to measure water saturations while dissolved oxygen (DO) concentrations were measured with flow-through oxygen microelectrodes. A hysteretic multifluid simulator was used to test whether the experimentally obtained water and entrapped air saturations, as well as DO concentrations, could be predicted using the assumptions of two- phase flow and equilibrium partitioning between the gas and the aqueous phases. The experimental results show that zones with entrapped air, formed during the imbibition portions of the experiment, were instrumental in re-oxygenation of the water in the zone of fluctuation. The fluctuating water table system also caused significant amounts of dissolved oxygen to be transported deeper into the flow cell. The simulator was able to predict water saturations, entrapped air saturations, and dissolved oxygen concentrations reasonably well.

Williams, Mark D.(BATTELLE (PACIFIC NW LAB)); Oostrom, Martinus (BATTELLE (PACIFIC NW LAB))

1999-12-01

76

High levels of fluctuating asymmetry in isolated stickleback populations  

Directory of Open Access Journals (Sweden)

Full Text Available 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 predation risk) populations of nine-spined sticklebacks (Pungitius pungitius). Results Pond sticklebacks had on average three times higher levels of FA than marine fish and this difference was highly significant. Heterozygosity in microsatellite markers was on average two times lower in pond (HE ? 0.3) than in marine (HE ? 0.6) populations, and levels of FA and heterozygosity were negatively correlated across populations. However, after controlling for habitat effect on heterozygosity, levels of FA and heterozygosity were uncorrelated. Conclusions The fact that levels of FA in traits likely to be important in the context of predator evasion were elevated in ponds compared to marine populations suggests that relaxed selection for homeostasis in ponds lacking predatory fish may be responsible for the observed habitat difference in levels of FA. This inference also aligns with the observation that the levels of genetic variability across the populations did not explain population differences in levels of FA after correcting for habitat effect. Hence, while differences in strength of selection, rather than in the degree of genetic stress could be argued to explain habitat differences in levels of FA, the hypothesis that increased FA in ponds is caused by genetic stress cannot be rejected.

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

2012-01-01

77

Level density of a Fermion gas: average growth, fluctuations, universality  

CERN Multimedia

It has been shown by H. Bethe more than 70 years ago that the number of excited states of a Fermi gas grows, at high excitation energies $Q$, like the exponential of the square root of $Q$. This result takes into account only the average density of single particle (SP) levels near the Fermi energy. It ignores two important effects, namely the discreteness of the SP spectrum, and its fluctuations. We show that the discreteness of the SP spectrum gives rise to smooth finite--$Q$ corrections. Mathematically, these corrections are associated to the problem of partitions of an integer. On top of the smooth growth of the many--body density of states there are, generically, oscillations. An explicit expression of these oscillations is given. Their properties strongly depend on the regular or chaotic nature of the SP motion. In particular, we analyze their typical size, temperature dependence and probability distribution, with emphasis on their universal aspects.

Leboeuf, P

2005-01-01

78

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

79

Water Vapor Radiometer Measurements of the Tropospheric Delay Fluctuations at Goldstone Over a Full Year  

Science.gov (United States)

One year of near-continuous water vapor radiometer (WVR) measurements at DSS 13 has provided a database for characterizing the Goldstone tropospheric delay properties in a statistical sense. The results have been expressed in terms of the Allan standard deviation of delay and compared to a previous model for Goldstone fluctuations and the specifications of the Cassini Gravitational Wave Experiment (GWE). The new WVR data indicate that average fluctuation levels at hour time scales or less are ~30-percent lower than the earlier Goldstone model predictions. At >1-h time scales, the WVR indicated fluctuation levels are in closer agreement with the model, although noise floor limitations may be artificially raising the average WVR-derived atmospheric fluctuation levels at the longer time scales. When scaled to two-way Doppler tracking at 20-deg elevation, as will occur for the GWE, these results indicate that Goldstone winter tropospheric delay fluctuations will typically be a factor of 10 larger than the GWE requirements at 1000 s and a factor of 4 larger at 10,000 s.

Keihm, S. J.

1995-04-01

80

Implementation of geoarchaeological methods in historical sea level fluctuation research  

Energy Technology Data Exchange (ETDEWEB)

Israel, like most other Mediterranean countries, is very rich in archaeological sites located at the present shoreline or at shallow underwater depths. This special situation produces a unique opportunity to develop the study of ancient sea levels through marine and coastal installations and their relation to the present sea level. A recently developed method is based upon the study of ancient water wells along the present shoreline and in the near-by coastal regions. The determination of the ancient groundwater table in each of the wells studied permits a sea level reconstruction for the relevant time with high accuracy. The study of 12 water wells representing different ages, from the Pre-Pottery Neolithic period (well dug by Galili of ca. 7,900 BP), to Crusader times (ca. 800 BP), provides data on sea level changes which, in most cases, supports data obtained from other regions. 7 refs.

Nir, Y. [Geological Survey of Israel, Jerusalem (Israel)

1993-09-01

 
 
 
 
81

Predicting groundwater level fluctuations with meteorological effect implications—A comparative study among soft computing techniques  

Science.gov (United States)

The knowledge of groundwater table fluctuations is important in agricultural lands as well as in the studies related to groundwater utilization and management levels. This paper investigates the abilities of Gene Expression Programming (GEP), Adaptive Neuro-Fuzzy Inference System (ANFIS), Artificial Neural Networks (ANN) and Support Vector Machine (SVM) techniques for groundwater level forecasting in following day up to 7-day prediction intervals. Several input combinations comprising water table level, rainfall and evapotranspiration values from Hongcheon Well station (South Korea), covering a period of eight years (2001-2008) were used to develop and test the applied models. The data from the first six years were used for developing (training) the applied models and the last two years data were reserved for testing. A comparison was also made between the forecasts provided by these models and the Auto-Regressive Moving Average (ARMA) technique. Based on the comparisons, it was found that the GEP models could be employed successfully in forecasting water table level fluctuations up to 7 days beyond data records.

Shiri, Jalal; Kisi, Ozgur; Yoon, Heesung; Lee, Kang-Kun; Hossein Nazemi, Amir

2013-07-01

82

Large decrease of fluctuations for supercooled water in hydrophobic nanoconfinement.  

Science.gov (United States)

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

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

2011-04-07

83

Large decrease of fluctuations for supercooled water in hydrophobic nanoconfinement.  

UK PubMed Central (United Kingdom)

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

Strekalova EG; Mazza MG; Stanley HE; Franzese G

2011-04-01

84

Level density and level density parameter in medium heavy nuclei including thermal and quantal fluctuation effects  

CERN Document Server

In a realistic application of the SPA + RPA theory for calculation of the nuclear level densities we find that quantal fluctuation corrections (RPA) are important even up to temperature $T = 2.0$ $MeV$. This leads to a good agreement between calculated numbers and the available experimental data for $^{104}Pd$ and $^{114}Sn$, particularly the excitation energy ($E^*$) dependence. Furthermore, we also argue that $a=S^2/4E^*$ is the only correct definition of the level density parameter in the present context which is also consistent with the Bethe like level density formula.

Agrawal, B K

1998-01-01

85

Fluctuation characteristics of acting pressure of water jet  

Energy Technology Data Exchange (ETDEWEB)

Concerning the rock cutting mechanism by a water jet, if the nature of the pressure acting onto the rock surface due to the water jet can be understood, it is considered that the problem of the above mechanism is attributed to the problem of the rock destruction under certain stress condition. From the above viewpoint, this research tries to grasp quantitatively the acting pressure of a water jet, particularly the characteristics of its fluctuation components using the self-correlation function, the cross correlation function between the discharge pressure and the acting pressure and the frequency response function, etc.. For the experiment, a three-throw plunger pump was used. Its maximum discharge pressure was 500kgf/cm/sup 2/ and its maximum discharge flow was 181/min. By controlling the revolution of a pump driving motor using an inverter, the pressure and the flow were changed. In addition, 4 kinds of nozzles from 1.1mm to 2.5mm were used. (6 figs, 2 refs)

Kiyono, Fumio; Saito, Takayuki; Handa, Keiji

1988-04-01

86

Experimental and Modeling Investigation of Shallow Water Table Fluctuations in Relation to Reverse Wieringermeer Effect  

Directory of Open Access Journals (Sweden)

Full Text Available Soil column experiments and modeling investigations were performed to study the behavior of shallow water table in response to various recharge events. Hence, shallow water table fluctuations inside sandy (Toyoura sand) and clayey (Chiba light clay) soil columns in response to surface and sub-surface recharge events were investigated under laboratory conditions. Experimental results showed that small application of water could raise the shallow water table level more than 100 times in depth in the case of Toyoura sand and more than 50 times in the case of Chiba LiC, reflecting a reverse Wieringermeer effect (RWE) response type of groundwater. This rise was associated with a prompt change of pressure head values which exhibited instantaneous fluctuations of centimeters due to the addition of millimeters of water. The recharge volumes leading to such disproportionate water table rise were successfully estimated using a simple analytical model based on the moisture retention curve of the soil and considering the hysteresis effect on soil water dynamics within the capillary fringe zone.

Ibrahimi Mohamed Khaled; Miyazaki Tsuyoshi; Nishikawa Kohei; Nishimura Taku; Imoto Hiromi

2011-01-01

87

The effect of tropospheric fluctuations on the accuracy of water vapor radiometry  

Science.gov (United States)

Line-of-sight path delay calibration accuracies of 1 mm are needed to improve both angular and Doppler tracking capabilities. Fluctuations in the refractivity of tropospheric water vapor limit the present accuracies to about 1 nrad for the angular position and to a delay rate of 3x10(exp -13) sec/sec over a 100-sec time interval for Doppler tracking. This article describes progress in evaluating the limitations of the technique of water vapor radiometry at the 1-mm level. The two effects evaluated here are: (1) errors arising from tip-curve calibration of WVR's in the presence of tropospheric fluctuations and (2) errors due to the use of nonzero beamwidths for water vapor radiometer (WVR) horns. The error caused by tropospheric water vapor fluctuations during instrument calibration from a single tip curve is 0.26 percent in the estimated gain for a tip-curve duration of several minutes or less. This gain error causes a 3-mm bias and a 1-mm scale factor error in the estimated path delay at a 10-deg elevation per 1 g/cm(sup 2) of zenith water vapor column density present in the troposphere during the astrometric observation. The error caused by WVR beam averaging of tropospheric fluctuations is 3 mm at a 10-deg elevation per 1 g/cm(sup 2) of zenith water vapor (and is proportionally higher for higher water vapor content) for current WVR beamwidths (full width at half maximum of approximately 6 deg). This is a stochastic error (which cannot be calibrated) and which can be reduced to about half of its instantaneous value by time averaging the radio signal over several minutes. The results presented here suggest two improvements to WVR design: first, the gain of the instruments should be stabilized to 4 parts in 10(exp 4) over a calibration period lasting 5 hours, and second, the WVR antenna beamwidth should be reduced to about 0.2 deg. This will reduce the error induced by water vapor fluctuations in the estimated path delays to less than 1 mm for the elevation range from zenith to 6 deg for most observation weather conditions.

Wilcox, J. Z.

1992-08-01

88

Fluctuations in the level density of a Fermi gas  

CERN Document Server

We present a theory that accurately describes the counting of excited states of a noninteracting fermionic gas. At high excitation energies the results reproduce Bethe's theory. At low energies oscillatory corrections to the many--body density of states, related to shell effects, are obtained. The fluctuations depend non-trivially on energy and particle number. Universality and connections with Poisson statistics and random matrix theory are established for regular and chaotic single--particle motion.

Leboeuf, P; Relano, A

2004-01-01

89

Mineralization of sparsely water-soluble polycyclic aromatic hydrocarbons in a water table fluctuation zone  

Energy Technology Data Exchange (ETDEWEB)

The mineralization potential of sparsely water-soluble polycyclic aromatic hydrocarbons (PAHs) within a highly diesel-contaminated water table fluctuation zone (WTFZ) was investigated using core-scale column microcosms. Experimental conditions mimicked overall seasonal changes in water and oxygen content at the site. During the first aerobic winter, PAH mineralization rates in the freshly contaminated soil were fastest for contaminant [{sup 14}C]-naphthalene which was the least hydrophobic and most water-soluble. Lowering the water table nearly doubled the mineralization rates of all [{sup 14}C]PAHs studied. During the oxygen-poor summer, all mineralization rates were insignificant and failed to respond to water table changes. Neither a return to water-saturated aerobic (winter) conditions nor lowering the water table under aerobic conditions induced detectable mineralization of [{sup 14}C]-naphthalene, but lowering the water table did markedly hasten the still slow mineralization of [{sup 14}C]phenanthrene and [{sup 14}C]anthracene. The time-dependent mineralization behavior and its response to water table fluctuations were explicable in terms of microbial responses to the changing oxygen content and depleting mineral nutrients.

Holman, H.Y.N.; Tsang, Y.W.; Holman, W.R. [Lawrence Berkeley National Lab., CA (United States)

1999-06-01

90

Modeling belowground water table fluctuations in the Everglades  

Science.gov (United States)

Humid lands, such as riparian zones, peatlands, and unsubmerged wetlands, are considered among the most biologically diverse of all ecosystems, providing a bountiful habitat for a large number of plant and animal species. In such ecosystems, the water table dynamics play a key role in major ecohydrological processes. The aim of the present study is to test with field data a recent analytical model for the estimation of the long-term probability distribution of the belowground water table position in groundwater-dependent environments. This model accounts for stochastic rainfall and processes such as infiltration, root water uptake, water flow from/to an external water body, and capillary fluxes. The water table model is tested using field data of groundwater levels recorded in three different sites within the Everglades (Florida, USA). A sensitivity analysis of the model to the soil and vegetation parameters is also carried out. After performing a procedure to determinate appropriate model parameters for the three sites, the steady state probability distribution functions of water table levels predicted by the model are compared to the empirical ones at both the annual and the seasonal time scale. The model is shown capable to reproduce many features of the observed distributions although there exist model predictions which still show some discrepancies with respect to the empirical observations. The potential causes for these discrepancies are also investigated and discussed.

Pumo, Dario; Tamea, Stefania; Noto, Leonardo Valerio; Miralles-Wilhem, Fernando; Rodriguez-Iturbe, Ignacio

2010-11-01

91

Biodegradation of Toluene Under Seasonal and Diurnal Fluctuations of Soil-Water Temperature.  

UK PubMed Central (United Kingdom)

An increasing interest in bioremediation of hydrocarbon polluted sites raises the question of the influence of seasonal and diurnal changes on soil-water temperature on biodegradation of BTEX, a widespread group of (sub)-surface contaminants. Therefore, we investigated the impact of a wide range of varying soil-water temperature on biodegradation of toluene under aerobic conditions. To see the seasonal impact of temperature, three sets of batch experiments were conducted at three different constant temperatures: 10°C, 21°C, and 30°C. These conditions were considered to represent (1) winter, (2) spring and/or autumn, and (3) summer seasons, respectively, at many polluted sites. Three additional sets of batch experiments were performed under fluctuating soil-water temperature cases (21<>10°C, 30<>21°C, and 10<>30°C) to mimic the day-night temperature patterns expected during the year. The batches were put at two different temperatures alternatively to represent the day (high-temperature) and night (low-temperature) times. The results of constant- and fluctuating-temperature experiments show that toluene degradation is strongly dependent on soil-water temperature level. An almost two-fold increase in toluene degradation time was observed for every 10°C decrease in temperature for constant-temperature cases. Under fluctuating-temperature conditions, toluene degraders were able to overcome the temperature stress and continued thriving during all considered weather scenarios. However, a slightly longer time was taken compared to the corresponding time at daily mean temperature conditions. The findings of this study are directly useful for bioremediation of hydrocarbon-polluted sites having significant diurnal and seasonal variations of soil-water temperature.

Yadav BK; Shrestha SR; Hassanizadeh SM

2012-09-01

92

Sea level rise and water storage on land  

Science.gov (United States)

Climate data was used to model the relationship between sea level rise and the loss of water stored in soils and snowpack on land. It was found that water stored on land did not make any lasting contribution to sea level rise during the 50 year period, although strong variation in precipitation and subsequent runoff, particularly in the tropics, caused sea level to fluctuate every ten years or so.

Al., Duc E.; Agu

93

Reactor water level measuring device  

International Nuclear Information System (INIS)

[en] The device of the present invention contributes to an improvement of maintenance and economics by decreasing the number and the kinds of water level transmitters disposed in a plant site. That is, a plurality of reactor water level monitors disposed in the plant site and a reactor water level monitor disposed in a central operation chamber are connected by a light transmission line. A plant operation state is judged by the monitor in the central operation chamber, and appropriate measuring range switching signals are sent to the water level detectors in the plant site depending on the conditions. Further, water level signals sent from the water level detectors are received in the central operation chamber and a circuit corresponding to the measuring range switching signals is selected, and the reactor water level is displayed by a recorder. Further, if requirement for the measuring range and calibration data of the water level detectors is sent to the water level detectors in the plant site by a selection switch of the monitor in the central operation chamber, the range is recognized and the calibration data are checked, and the results are inputted to a recording circuit of the monitor. (I.S.)

1992-04-14

94

Structural fluctuation of protein in water around its native state: a new statistical mechanics formulation.  

UK PubMed Central (United Kingdom)

A new statistical mechanics formulation of characterizing the structural fluctuation of protein correlated with that of water is presented based on the generalized Langevin equation and the 3D-reference interaction site model (RISM)/RISM theory of molecular liquids. The displacement vector of atom positions, and their conjugated momentum, are chosen for the dynamic variables for protein, while the density fields of atoms and their momentum fields are chosen for water. Projection of other degrees of freedom onto those dynamic variables using the standard projection operator method produces essentially two equations, which describe the time evolution of fluctuation concerning the density field of solvent and the conformation of protein around an equilibrium state, which are coupled with each other. The equation concerning the protein dynamics is formally akin to that of the coupled Langevin oscillators, and is a generalization of the latter, to atomic level. The most intriguing feature of the new equation is that it contains the variance-covariance matrix as the "Hessian" term describing the "force" restoring an equilibrium conformation, which is the second moment of the fluctuation of atom positions. The "Hessian" matrix is naturally identified as the second derivative of the free energy surface around the equilibrium. A method to evaluate the Hessian matrix based on the 3D-RISM/RISM theory is proposed. Proposed also is an application of the present formulation to the molecular recognition, in which the conformational fluctuation of protein around its native state becomes an important factor as exemplified by so called "induced fitting."

Kim B; Hirata F

2013-02-01

95

Structural fluctuation of protein in water around its native state: a new statistical mechanics formulation.  

Science.gov (United States)

A new statistical mechanics formulation of characterizing the structural fluctuation of protein correlated with that of water is presented based on the generalized Langevin equation and the 3D-reference interaction site model (RISM)/RISM theory of molecular liquids. The displacement vector of atom positions, and their conjugated momentum, are chosen for the dynamic variables for protein, while the density fields of atoms and their momentum fields are chosen for water. Projection of other degrees of freedom onto those dynamic variables using the standard projection operator method produces essentially two equations, which describe the time evolution of fluctuation concerning the density field of solvent and the conformation of protein around an equilibrium state, which are coupled with each other. The equation concerning the protein dynamics is formally akin to that of the coupled Langevin oscillators, and is a generalization of the latter, to atomic level. The most intriguing feature of the new equation is that it contains the variance-covariance matrix as the "Hessian" term describing the "force" restoring an equilibrium conformation, which is the second moment of the fluctuation of atom positions. The "Hessian" matrix is naturally identified as the second derivative of the free energy surface around the equilibrium. A method to evaluate the Hessian matrix based on the 3D-RISM/RISM theory is proposed. Proposed also is an application of the present formulation to the molecular recognition, in which the conformational fluctuation of protein around its native state becomes an important factor as exemplified by so called "induced fitting." PMID:23406099

Kim, Bongsoo; Hirata, Fumio

2013-02-01

96

Structural fluctuation of protein in water around its native state: A new statistical mechanics formulation  

Science.gov (United States)

A new statistical mechanics formulation of characterizing the structural fluctuation of protein correlated with that of water is presented based on the generalized Langevin equation and the 3D-reference interaction site model (RISM)/RISM theory of molecular liquids. The displacement vector of atom positions, and their conjugated momentum, are chosen for the dynamic variables for protein, while the density fields of atoms and their momentum fields are chosen for water. Projection of other degrees of freedom onto those dynamic variables using the standard projection operator method produces essentially two equations, which describe the time evolution of fluctuation concerning the density field of solvent and the conformation of protein around an equilibrium state, which are coupled with each other. The equation concerning the protein dynamics is formally akin to that of the coupled Langevin oscillators, and is a generalization of the latter, to atomic level. The most intriguing feature of the new equation is that it contains the variance-covariance matrix as the ``Hessian'' term describing the ``force'' restoring an equilibrium conformation, which is the second moment of the fluctuation of atom positions. The ``Hessian'' matrix is naturally identified as the second derivative of the free energy surface around the equilibrium. A method to evaluate the Hessian matrix based on the 3D-RISM/RISM theory is proposed. Proposed also is an application of the present formulation to the molecular recognition, in which the conformational fluctuation of protein around its native state becomes an important factor as exemplified by so called ``induced fitting.''

Kim, Bongsoo; Hirata, Fumio

2013-02-01

97

Method of vegetation slope pavement of level fluctuation zone  

UK PubMed Central (United Kingdom)

A method for preparing plant slope protection on rising and falling limb of water surface applies scheme of sowing amphibious plant seeds as main then planting amphibious plant nursery stock as auxiliary on slope of rising and falling limb to form ecological protective plant group configured by musky and grass with water logging proof and draught enduring nature.

ZHANG YUCHANG ZHANG

98

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)

[en] 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.

2012-01-01

99

One-dimensional airflow in unsaturated zone induced by periodic water table fluctuation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper investigates the vertical airflow driven by fluctuating water table within the lower layer of a coastal two-layered system. The upper layer is unsaturated and semipermeable, while the lower is permeable. An analytical solution of the subsurface air pressure fluctuation is derived on the b...

Li, H; Jiao, JJ

100

A novel automated fluctuating water table column system to study redox oscillations in saturated and unsaturated media  

Science.gov (United States)

An automated, computer-controlled soil column experimental setup was developed to simulate in detail the effects of water table dynamics on the biogeochemical transformations of nutrients and other redox-sensitive chemical species at the interface between groundwater and surface waters. The experiments were conducted using two parallel soil columns, one under stable and the other under fluctuating water table conditions. The water table in the soil columns was controlled by an automated multi-channel pump connected to two equilibrium and storage columns. In the stable column, the water table was maintained at -20 cm below the soil surface while it fluctuated between the soil surface and -45 cm in the fluctuating column at a rate of 4.8 cm/d. Redox potential (Eh), pH profiles were measured continuously using high temporal resolution microsensors (10 ?m glass tip) installed into the columns at different depths. The results show striking geochemical contrasts between the fluctuating and the stable columns, demonstrating that the setup is able to impose redox potential oscillations ranging from oxidizing (~+700 mv) to reducing (~-200 mv) conditions. CO2 fluxes were monitored in the headspace above the soil surface using a LICOR LI-8100 automated soil CO2 flux system. The mean CO2 emission in the stable water table column was ~20 ppm/min. In the fluctuating soil column, the CO2 flux varied between 4 and 110 ppm/min and the lowest were measured at the highest water level. Water samples obtained from micro-Rhizon samplers installed into the columns at various depths. Additionally, the physical, chemical and microbial characteristics of the media were characterized by centimetre scale slicing of the soil columns at the end of the experiment. The impacting of these oscillations on the distribution of chemical species will be discussed in term of the interactions between soils, solutes, microbial activity, and hydrology.

Rezanezhad, F.; Couture, R.-M.; Kovac, R.; Van Cappellen, P.

2012-04-01

 
 
 
 
101

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

Science.gov (United States)

We conduct a drainage experiment to confirm the variable Sy.The height of capillary fringe plays a key role for the Sy variation.ETg estimation using diurnal water table fluctuations in a desert area.

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

2013-05-01

102

Level density of a Fermi gas: average growth and fluctuations  

CERN Document Server

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

Leboeuf, P; Leboeuf, Patricio

2006-01-01

103

Level Density of a Fermi Gas: Average Growth and Fluctuations  

International Nuclear Information System (INIS)

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

2006-07-07

104

Speech recognition in fluctuating and continuous maskers: effects of hearing loss and presentation level.  

UK PubMed Central (United Kingdom)

Listeners with normal-hearing sensitivity recognize speech more accurately in the presence of fluctuating background sounds, such as a single competing voice, than in unmodulated noise at the same overall level. These performance differences are greatly reduced in listeners with hearing impairment, who generally receive little benefit from fluctuations in masker envelopes. If this lack of benefit is entirely due to elevated quiet thresholds and the resulting inaudibility of low-amplitude portions of signal + masker, then listeners with hearing impairment should derive increasing benefit from masker fluctuations as presentation levels increase. Listeners with normal-hearing (NH) sensitivity and listeners with hearing impairment (HI) were tested for sentence recognition at moderate and high presentation levels in competing speech-shaped noise, in competing speech by a single talker, and in competing time-reversed speech by the same talker. NH listeners showed more accurate recognition at moderate than at high presentation levels and better performance in fluctuating maskers than in unmodulated noise. For these listeners, modulated versus unmodulated performance differences tended to decrease at high presentation levels. Listeners with HI, as a group, showed performance that was more similar across maskers and presentation levels. Considered individually, only 2 out of 6 listeners with HI showed better overall performance and increasing benefit from masker fluctuations as presentation level increased. These results suggest that audibility alone does not completely account for the group differences in performance with fluctuating maskers; suprathreshold processing differences between groups also appear to play an important role. Competing speech frequently provided more effective masking than time-reversed speech containing temporal fluctuations of equal magnitude. This finding is consistent with "informational" masking resulting from competitive processing of words and phrases within the speech masker that would notoccur for time-reversed sentences.

Summers V; Molis MR

2004-04-01

105

Fluctuating Mesozoic and Cenozoic sea levels and implications for stratigraphy  

Energy Technology Data Exchange (ETDEWEB)

Sequence stratigraphy encompasses depositional models of genetically related packages of sediments deposited during various phases of cycle of sea level change, i.e., from a lowstand to highstand to the subsequent lowstand. The application of these models to marine outcrops around the world and to subsurface data led to the construction of Mesozoic-Cenozoic sea level curves with greater event resolution than the earlier curves based on seismic data alone. Construction of these better resolution curves begins with an outline of the principles of sequence-stratigraphic analysis and the reconstruction of the history of sea level change from outcrop and subsurface data for the past 250 Ma. Examples of marine sections from North America, Europe, and Asia can be used to illustrate sequence analysis of outcrop data and the integration of chronostratigraphy with sea level history. Also important are the implications of sequence-stratigraphic methodology and the new cycle charts to various disciplines of stratigraphy, environmental reconstruction, and basin analysis. The relationship of unconformities along the continental margins to hiatuses and dissolution surfaces in the deep basins must also be explored, as well as the relevance of sequence-stratigraphic methodology to biofacies and source rock prediction.

Haq, B.U. (National Science Foundation, Washington, DC (USA))

1988-12-01

106

Band gaps and localization of surface water waves over large-scale sand waves with random fluctuations.  

UK PubMed Central (United Kingdom)

Band structure and wave localization are investigated for sea surface water waves over large-scale sand wave topography. Sand wave height, sand wave width, water depth, and water width between adjacent sand waves have significant impact on band gaps. Random fluctuations of sand wave height, sand wave width, and water depth induce water wave localization. However, random water width produces a perfect transmission tunnel of water waves at a certain frequency so that localization does not occur no matter how large a disorder level is applied. Together with theoretical results, the field experimental observations in the Taiwan Bank suggest band gap and wave localization as the physical mechanism of sea surface water wave propagating over natural large-scale sand waves.

Zhang Y; Li Y; Shao H; Zhong Y; Zhang S; Zhao Z

2012-06-01

107

Spectrum of two-level systems with discrete frequency fluctuations.  

Science.gov (United States)

We study, theoretically and experimentally, an ensemble of two-level systems coupled to an environment which induces random jumps in their resonant frequency. We present a closed-form formula for the spectrum in terms of the resonant frequency distribution and the Poisson rate constant. For a normal distribution the spectrum deviates from a generalized Gumbel function, a well-known result for continuous stochastic Gaussian processes. We perform experiments with optically trapped cold 87Rb atoms and show that the predictions of our theory for a 3D harmonic trap match the measured spectra without fitting parameters. PMID:20867373

Sagi, Yoav; Pugatch, Rami; Almog, Ido; Davidson, Nir

2010-06-25

108

Spectrum of two-level systems with discrete frequency fluctuations.  

UK PubMed Central (United Kingdom)

We study, theoretically and experimentally, an ensemble of two-level systems coupled to an environment which induces random jumps in their resonant frequency. We present a closed-form formula for the spectrum in terms of the resonant frequency distribution and the Poisson rate constant. For a normal distribution the spectrum deviates from a generalized Gumbel function, a well-known result for continuous stochastic Gaussian processes. We perform experiments with optically trapped cold 87Rb atoms and show that the predictions of our theory for a 3D harmonic trap match the measured spectra without fitting parameters.

Sagi Y; Pugatch R; Almog I; Davidson N

2010-06-01

109

Complexity of low-frequency blood oxygen level-dependent fluctuations covaries with local connectivity.  

UK PubMed Central (United Kingdom)

Very low-frequency blood oxygen level-dependent (BOLD) fluctuations have emerged as a valuable tool for describing brain anatomy, neuropathology, and development. Such fluctuations exhibit power law frequency dynamics, with largest amplitude at lowest frequencies. The biophysical mechanisms generating such fluctuations are poorly understood. Using publicly available data from 1,019 subjects of age 7-30, we show that BOLD fluctuations exhibit temporal complexity that is linearly related to local connectivity (regional homogeneity), consistently and significantly covarying across subjects and across gray matter regions. This relationship persisted independently of covariance with gray matter density or standard deviation of BOLD signal. During late neurodevelopment, BOLD fluctuations were unchanged with age in association cortex while becoming more random throughout the rest of the brain. These data suggest that local interconnectivity may play a key role in establishing the complexity of low-frequency BOLD fluctuations underlying functional magnetic resonance imaging connectivity. Stable low-frequency power dynamics may emerge through segmentation and integration of connectivity during development of distributed large-scale brain networks. Hum Brain Mapp, 2013. © 2013 Wiley Periodicals, Inc.

Anderson JS; Zielinski BA; Nielsen JA; Ferguson MA

2013-02-01

110

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 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 t (more) he 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.

2012-04-01

111

Experimental and Modeling Investigation of Shallow Water Table Fluctuations in Relation to Reverse Wieringermeer Effect  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Soil column experiments and modeling investigations were performed to study the behavior of shallow water table in response to various recharge events. Hence, shallow water table fluctuations inside sandy (Toyoura sand) and clayey (Chiba light clay) soil columns in response to surface and sub-surfac...

Ibrahimi Mohamed Khaled; Miyazaki Tsuyoshi; Nishikawa Kohei; Nishimura Taku; Imoto Hiromi

112

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

A study of the solute redistribution caused by water-table fluctuations in experimental packed columns of fine sand and a sandy clay loam soil using potassium chloride as a non-reactive tracer is modelled. With the water table initially at the soil surface, the redistribution of surface applied chlo...

Cesáreo Landeros-Sánchez; Ma. del Refugio Castañeda-Chávez; Fabiola Lango-Reynoso; Itzel Galaviz-Villa

113

Multifractal detrended fluctuation analysis in examining scaling properties of the spatial patterns of soil water storage  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Knowledge about the scaling properties of soil water storage is crucial in transferring locally measured fluctuations to larger scales and vice-versa. Studies based on remotely sensed data have shown that the variability in surface soil water has clear scaling properties (i.e., statistically self si...

A. Biswas; T. B. Zeleke; B. C. Si

114

Fluctuation of sea-level and decision of cycles in Yanzhou coalfield  

Energy Technology Data Exchange (ETDEWEB)

Based on the analyses of cyclicity and textual feature of the coal measure in Yanzhou coalfield, the paper discusses the characteristics of sea-level change and its controlling in the coal-forming process, elucidates the asymmetrical feature and superposition of cyclothems in various orders. The evidence shows that the sea-level changes are of high frequency and mutational change, and that the cyclical features are mainly controlled by sea-level fluctuation. 6 refs., 2 figs., 1 tab.

Dai, S.; Ren, D.; Liu, Y.; Yang, Q. [China University of Mining and Technology, Beijing (China). Beijing Graduate School

1997-03-01

115

Effects of water compressibility on the pressure fluctuation prediction in pump turbine  

Science.gov (United States)

The compressible effect of water is a key factor in transient flows. However, it is always neglected in the unsteady simulations for hydraulic machinery. In light of this, the governing equation of the flow is deduced to combine the compressibility of water, and then simulations with compressible and incompressible considerations to the typical unsteady flow phenomenon (Rotor stator interaction) in a pump turbine model are carried out and compared with each other. The results show that water compressibility has great effects on the magnitude and frequency of pressure fluctuation. As the operating condition concerned, the compressibility of water will induce larger pressure fluctuation, which agrees better with measured data. Moreover, the lower frequency component of the pressure signal can only be captured with the combination of water compressibility. It can be concluded that water compressibility is a fatal factor, which cannot be neglected in the unsteady simulations for pump turbines.

Yin, J. L.; Wang, D. Z.; Wang, L. Q.; Wu, Y. L.; Wei, X. Z.

2012-11-01

116

Effects of water compressibility on the pressure fluctuation prediction in pump turbine  

International Nuclear Information System (INIS)

The compressible effect of water is a key factor in transient flows. However, it is always neglected in the unsteady simulations for hydraulic machinery. In light of this, the governing equation of the flow is deduced to combine the compressibility of water, and then simulations with compressible and incompressible considerations to the typical unsteady flow phenomenon (Rotor stator interaction) in a pump turbine model are carried out and compared with each other. The results show that water compressibility has great effects on the magnitude and frequency of pressure fluctuation. As the operating condition concerned, the compressibility of water will induce larger pressure fluctuation, which agrees better with measured data. Moreover, the lower frequency component of the pressure signal can only be captured with the combination of water compressibility. It can be concluded that water compressibility is a fatal factor, which cannot be neglected in the unsteady simulations for pump turbines.

2012-11-26

117

Lectures on Molecular- and Nano-scale Fluctuations in Water  

CERN Multimedia

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

Chandler, David

2011-01-01

118

Ultrafast dynamics of liquid water: Frequency fluctuations of the OH stretch and the HOH bend  

Energy Technology Data Exchange (ETDEWEB)

Frequency fluctuations of the OH stretch and the HOH bend in liquid water are reported from the third-order response function evaluated using the TTM3-F potential for water. The simulated two-dimensional infrared (IR) spectra of the OH stretch are similar to previously reported theoretical results. The present study suggests that the frequency fluctuation of the HOH bend is faster than that of the OH stretch. The ultrafast loss of the frequency correlation of the HOH bend is due to the strong couplings with the OH stretch as well as the intermolecular hydrogen bond bend.

Imoto, Sho; Xantheas, Sotiris S.; Saito, Shinji

2013-07-28

119

Ultrafast dynamics of liquid water: frequency fluctuations of the OH stretch and the HOH bend.  

UK PubMed Central (United Kingdom)

Frequency fluctuations of the OH stretch and the HOH bend in liquid water are reported from the third-order response function evaluated using the TTM3-F potential for water. The simulated two-dimensional infrared spectra of the OH stretch are similar to previously reported theoretical results. The present study suggests that the frequency fluctuation of the HOH bend is faster than that of the OH stretch. The ultrafast loss of the frequency correlation of the HOH bend is due to the strong couplings with the OH stretch as well as the intermolecular hydrogen bond bend.

Imoto S; Xantheas SS; Saito S

2013-07-01

120

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

Directory of Open Access Journals (Sweden)

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

Momon Sodik Imanudin; Edi Armanto; Robiyanto Hendro Susanto; Siti Masreah Bernas

2010-01-01

 
 
 
 
121

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

International Nuclear Information System (INIS)

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

2001-05-03

122

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

Energy Technology Data Exchange (ETDEWEB)

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

Paces, James B.; Whelan, Joseph

2001-04-29

123

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

International Nuclear Information System (INIS)

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

2001-01-01

124

Water table fluctuation and its effects on vegetation in a semiarid environment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A good understanding of water table fluctuation effects on vegetation is crucial for sustaining fragile hydrology and ecology of semiarid areas such as the Horqin Sandy Land (HSL) in northern China, but such understanding is not well documented in literature. The objectives of this study were to exa...

L. Duan; T. Liu; X. Wang; Y. Luo; W. Wang; X. Liu

125

A field study of the vertical immiscible displacement of LNAPL associated with a fluctuating water table  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A variety of field techniques were utilized to study the immiscible displacement of LNAPL (gasoline) above a fluctuating shallow water table. Hydrophobic and hydrophillic tensiometer measurements were compared to a dual-well monitoring system that measured the potentiometric head of groundwater ...

Steffy, D. A.; Johnston, C.; Barry, D. A.

126

The line shape of a two-level system with a fluctuating frequency  

Science.gov (United States)

An expression is derived for describing the transformation of the line shape in a two-level system with a fluctuating resonance frequency ?. In contrast to the existing approaches, the obtained expression is not based on any assumption regarding the distribution of frequencies ?. It is shown that, under conditions of a dichotomous random process when the resonance frequency ? randomly assumes one of two values, as well as under conditions of the Gauss-Markov and Lorentz-Markov random processes describing the frequency fluctuations, the derived expression reduces to well-known results. The transformation of the line shape of a two-level system described by the plateau-shaped Abragam curve is considered as an example.

Olszewski, M.; Sergeev, N. A.

2008-10-01

127

Reproducibility of intraocular pressure peak and fluctuation of the water-drinking test.  

UK PubMed Central (United Kingdom)

BACKGROUND: The water-drinking test has been used as a stress test to evaluate the drainage system of the eye. However, in order to be clinically applicable,a test must provide reproducible results with consistent measurements. This study was performed to verify the reproducibility of intraocular pressure peaks and fluctuation detected during the water-drinking test in patients with ocular hypertension and open-angle glaucoma. DESIGN: A prospective analysis of patients in a tertiary care unit for glaucoma treatment. PARTICIPANTS: Twenty-four ocular hypertension and 64 open-angle glaucoma patients not under treatment. METHODS: The water-drinking test was performed in 2 consecutive days by the same examiners in patients not under treatment. Reproducibility was assessed using the intraclass correlation coefficient. MAIN OUTCOME MEASURES: Peak and fluctuation of intraocular pressure obtained with the water-drinking test were analysed for reproducibility. RESULTS: Eighty-eight eyes from 24 ocular hypertension and 64 open-angle glaucoma patients not under treatment were evaluated. Test and retest intraocular pressure peak values were 28.38 ± 4.64 and 28.38 ± 4.56 mmHg, respectively (P = 1.00). Test and retest intraocular pressure fluctuation values were 5.75 ± 3.9 and 4.99 ± 2.7 mmHg, respectively (P = 0.06). Based on intraclass coefficient, reproducibility was excellent for peak intraocular pressure (intraclass correlation coefficient = 0.79) and fair for intraocular pressure fluctuation (intraclass correlation coefficient = 0.37). CONCLUSION: Intraocular pressure peaks detected during the water-drinking test presented excellent reproducibility, whereas the reproducibility of fluctuation was considered fair.

Hatanaka M; Alencar LM; De Moraes CG; Susanna R Jr

2013-05-01

128

Level widths and level densities in 28Si, 46Ti, 52Cr, and 60Ni from Ericson fluctuations  

International Nuclear Information System (INIS)

Ericson fluctuations in the differential cross sections were investigated for the compound reactions 27Al(p,n0)27Si, 45Sc(p,n4)45Ti, 45Sc(p,n5)45Ti, 51V(p,n0)51Cr, and 59Co(p,n0)59Ni. Level widths in the compound nuclei 28Si, 46Ti, 52Cr, and 60Ni were extracted from the analysis of the differential cross sections by the Fourier method and a nonlinear fit to the lnk2+Bk2> distribution. The neutron spectra for each reaction were measured at least at three backward angles but the coherence width did not show a strong angular dependence. Nuclear level densities for the above nuclei were extracted by relating the average level spacing DJ? to the average level width ?J? using the fluctuation theory. Reasonable agreements were found with other level densities and level density compilations based in the Fermi gas formalism of Al-Quraishi and Huang for 28Si, 46Ti, and 52Cr but the comparison diverges for 60Ni for which additional measurements are required in order to clarify the observed discrepancies. The level density parameters that best describe the data are a=3.5 and ?=4.0, U28Si, a=4.8 and ?=-0.3, U46Ti, and a=4.8 and ?=0.3, U52Cr.

2004-01-01

129

Level widths and level densities in 28 Si , 46 Ti , 52 Cr , and 60 Ni from Ericson fluctuations  

Science.gov (United States)

Ericson fluctuations in the differential cross sections were investigated for the compound reactions 27 Al (p, n0 ) 27 Si , 45 Sc (p, n4 ) 45 Ti , 45 Sc (p, n5 ) 45 Ti , 51 V (p, n0 ) 51 Cr , and 59 Co (p, n0 ) 59 Ni . Level widths in the compound nuclei 28 Si , 46 Ti , 52 Cr , and 60 Ni were extracted from the analysis of the differential cross sections by the Fourier method and a nonlinear fit to the ln distribution. The neutron spectra for each reaction were measured at least at three backward angles but the coherence width did not show a strong angular dependence. Nuclear level densities for the above nuclei were extracted by relating the average level spacing DJ? to the average level width ?J? using the fluctuation theory. Reasonable agreements were found with other level densities and level density compilations based in the Fermi gas formalism of Al-Quraishi and Huang for 28 Si , 46 Ti , and 52 Cr but the comparison diverges for 60 Ni for which additional measurements are required in order to clarify the observed discrepancies. The level density parameters that best describe the data are a=3.5 and ?=4.0 , U<25 MeV , for 28 Si , a=4.8 and ?=-0.3 , U<20 MeV , for 46 Ti , and a=4.8 and ?=0.3 , U<20 MeV , for 52 Cr .

Salas-Bacci, Americo; Grimes, Steven M.; Massey, Thomas N.; Parpottas, Yannis; Wheeler, Raymond T.; Oldendick, James E.

2004-08-01

130

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.

1990-01-01

131

One-dimensional airflow in unsaturated zone induced by periodic water table fluctuation  

Science.gov (United States)

This paper investigates the vertical airflow driven by fluctuating water table within the lower layer of a coastal two-layered system. The upper layer is unsaturated and semipermeable, while the lower is permeable. An analytical solution of the subsurface air pressure fluctuation is derived on the basis of model simplification assumptions, the reasonability of which was examined by numerical solutions of the original nonlinear model. The airflow in the upper layer is controlled from the top by the constant atmospheric pressure and from the bottom by a temporally fluctuating air pressure P0(t), which is spatially constant in the unsaturated zone of the lower layer. For a sinusoidal head the amplitude of P0(t) increases with the frequency of the head fluctuation, the upper layer's thickness, and the unconfined aquifer's air-filled porosity and decreases with the upper layer's permeability. The phase shift of P0(t) ranges from 0 to ?/2, indicating a ``time advance.'' Particularly, P0(t) is approximately proportional to the temporal derivative of the head for sufficiently thin or permeable upper layer and to the head itself for sufficiently thick or less permeable one. The fluctuation amplitude of the water table is always less than that of the head and can be only one tenth of the latter if the upper layer is sufficiently thick or less permeable, which may slow significantly the landward attenuation speed of the tide-induced head fluctuation in a coastal ``air-confined'' aquifer. The analytical solution was used to estimate the value range of the air permeability of the marine sand fill at a coastal reclamation area of Hong Kong.

Li, Hailong; Jiao, Jiu Jimmy

2005-04-01

132

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

DEFF Research Database (Denmark)

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

Massman, W.J.; Ibrom, Andreas

2008-01-01

133

Dynamics of phreatophyte root growth relative to a seasonally fluctuating water table in a Mediterranean-type environment.  

UK PubMed Central (United Kingdom)

While seasonal redistribution of fine root biomass in response to fluctuations in groundwater level is often inferred in phreatophytic plants, few studies have observed the in situ growth dynamics of deep roots relative to those near the surface. We investigated the root growth dynamics of two Banksia species accessing a seasonally dynamic water table and hypothesized that root growth phenology varied with depth, i.e. root growth closest to the water table would be influenced by water table dynamics rather than surface micro-climate. Root in-growth bags were used to observe the dynamics of root growth at different soil depths and above-ground growth was also assessed to identify whole-plant growth phenology. Root growth at shallow depths was found to be in synchrony with above-ground growth phenophases, following increases in ambient temperature and soil water content. In contrast, root growth at depth was either constant or suppressed by saturation. Root growth above the water table and within the capillary fringe occurred in all seasons, corresponding with consistent water availability and aerobic conditions. However, at the water table, a seasonal cycle of root elongation with drawdown in summer followed by trimming in response to water table rise and saturation in winter, was observed. The ability to grow roots year-round at the capillary fringe and redistribute fine root biomass in response to groundwater drawdown is considered critical in allowing phreatophytes, in seasonally water-limited environments, to maintain access to groundwater throughout the year.

Canham CA; Froend RH; Stock WD; Davies M

2012-12-01

134

Dynamics of phreatophyte root growth relative to a seasonally fluctuating water table in a Mediterranean-type environment.  

Science.gov (United States)

While seasonal redistribution of fine root biomass in response to fluctuations in groundwater level is often inferred in phreatophytic plants, few studies have observed the in situ growth dynamics of deep roots relative to those near the surface. We investigated the root growth dynamics of two Banksia species accessing a seasonally dynamic water table and hypothesized that root growth phenology varied with depth, i.e. root growth closest to the water table would be influenced by water table dynamics rather than surface micro-climate. Root in-growth bags were used to observe the dynamics of root growth at different soil depths and above-ground growth was also assessed to identify whole-plant growth phenology. Root growth at shallow depths was found to be in synchrony with above-ground growth phenophases, following increases in ambient temperature and soil water content. In contrast, root growth at depth was either constant or suppressed by saturation. Root growth above the water table and within the capillary fringe occurred in all seasons, corresponding with consistent water availability and aerobic conditions. However, at the water table, a seasonal cycle of root elongation with drawdown in summer followed by trimming in response to water table rise and saturation in winter, was observed. The ability to grow roots year-round at the capillary fringe and redistribute fine root biomass in response to groundwater drawdown is considered critical in allowing phreatophytes, in seasonally water-limited environments, to maintain access to groundwater throughout the year. PMID:22692384

Canham, Caroline A; Froend, Raymond H; Stock, William D; Davies, Muriel

2012-06-13

135

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

DEFF Research Database (Denmark)

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

Catic, Jasmina; Santurette, Sébastien

2013-01-01

136

Analysis of water levels in the Frenchman Flat area, Nevada Test Site  

Science.gov (United States)

Analysis of water levels in 21 wells in the Frenchman Flat area, Nevada Test Site, provides information on the accuracy of hydraulic-head calculations, temporal water-level trends, and potential causes of water-level fluctuations. Accurate hydraulic heads are particularly important in Frenchman Flat where the hydraulic gradients are relatively flat (less than 1 foot per mile) in the alluvial aquifer. Temporal water-level trends with magnitudes near or exceeding the regional hydraulic gradient may have a substantial effect on ground-water flow directions. Water-level measurements can be adjusted for the effects of barometric pressure, formation water density (from water-temperature measurements), borehole deviation, and land-surface altitude in selected wells in the Frenchman Flat area. Water levels in one well were adjusted for the effect of density; this adjustment was significantly greater (about 17 feet) than the adjustment of water levels for barometric pressure, borehole deviation, or land-surface altitude (less than about 4 feet). Water-level measurements from five wells exhibited trends that were statistically and hydrologically significant. Statistically significant water-level trends were observed for three wells completed in the alluvial aquifer (WW-5a, UE-5n, and PW-3), for one well completed in the carbonate aquifer (SM-23), and for one well completed in the quartzite confining unit (Army-6a). Potential causes of water-level fluctuations in wells in the Frenchman Flat area include changes in atmospheric conditions (precipitation and barometric pressure), Earth tides, seismic activity, past underground nuclear testing, and nearby pumping. Periodic water-level measurements in some wells completed in the carbonate aquifer indicate cyclic-type water-level fluctuations that generally correlate with longer term changes (more than 5 years) in precipitation. Ground-water pumping fromthe alluvial aquifer at well WW-5c and pumping and discharge from well RNM-2s appear to cause water-level fluctuations in nearby observation wells. The remaining known sources of water-level fluctuations do not appear to substantially affect water-level changes (seismic activity and underground nuclear testing) or do not affect changes over a period of more than 1 year (barometric pressure and Earth tides) in wells in the Frenchman Flat area.

Bright, D. J.; Watkins, S. A.; Lisle, B. A.

2001-01-01

137

Higher order analytical solutions of water table fluctuations in coastal aquifers.  

UK PubMed Central (United Kingdom)

The groundwater response of coastal aquifers to tidal forcing is described by Laplace's equation coupled with the nonlinear phreatic-free surface boundary condition. Here we describe fluctuations in the water table using two small parameters, extending previous work by proposing an ansatz to compute higher order, semi-analytical solutions. The new solutions are compared with known lower order solutions. The relative difference between the linear solution and higher order solutions can reach up to 30% of the linear solution for shallow beaches. The new solutions exhibit a reduction in the over height of the groundwater fluctuations compared with the lower order solutions. In addition, the super elevation of the water table, both near shore and as the aquifer tends landward, is examined with the inclusion of higher order terms.

Stojsavljevic JD; Jeng DS; Seymour BR; Pokrajac D

2012-03-01

138

Comparison of Dual Water Vapor Radiometer Differenced Path Delay Fluctuations and Site Test Interferometer Phase Delay Fluctuations Over a Shared 250-Meter Baseline  

Science.gov (United States)

Site test interferometers (STIs) have been deployed at Goldstone, California, in order to (1) assess the suitability of Goldstone as an uplink array site, and (2) statistically characterize atmospheric-induced phase fluctuations over an approximately 250-m baseline for the Goldstone climate for use in future array link scenarios. Beginning in August 2008, dual water vapor radiometers (DWVRs) were deployed next to each antenna element of the STI residing at the Venus site at Goldstone forming a baseline of similar length. The differenced path delay between the two WVR units forms an additional data type that can be used to validate the STI phase fluctuations and confirm the atmospheric nature of these fluctuations. This study was motivated by several considerations. First, the use of a single WVR provides single-point path delay fluctuation measurements that could be used as an ancillary data type, to compare against the magnitude of STI path delay fluctuations. Second, the use of two WVRs allows estimation of their differenced path delay, which produces a data type that could be correlated directly against the STI phase difference fluctuations (filtered to remove long-period nontroposphere variations). This can allow one to assess whether STI fluctuations are due to troposphere or can be used to identify suspicious signatures to verify whether equipment problems or other anomalies exist. Such an experiment could also be used to explore the feasibility and limitations of using a DWVR in place of an STI to characterize atmospheric phase fluctuations for a generally dry climate when liquid content in the atmosphere is minimal (up to a certain limit occurring less than 1 percent of the time). This article reports on initial study results of a comparison of differenced path delay statistics derived from both the DWVR and the STI, as well as including discussion of prospects for future DWVR experiments using WVRs of improved design and optimal experimental procedures.

Morabito, D. D.; D'Addario, L. R.; Keihm, S.; Shambayati, S.

2012-02-01

139

Stratigraphic analysis of lake level fluctuations in Lake Ohrid: an integration of high resolution hydro-acoustic data and sediment cores  

Directory of Open Access Journals (Sweden)

Full Text Available Ancient Lake Ohrid is a steep-sided, oligotrophic, karst lake that was tectonically formed most likely within the Pliocene and often referred to as a hotspot of endemic biodiversity. This study aims on tracing significant lake level fluctuations at Lake Ohrid using high-resolution acoustic data in combination with lithological, geochemical, and chronological information from two sediment cores recovered from sub-aquatic terrace levels at ca. 32 and 60 m water depth. According to our data, significant lake level fluctuations with prominent lowstands of ca. 60 and 35 m below the present water level occurred during Marine Isotope Stage (MIS) 6 and MIS 5, respectively. The effect of these lowstands on biodiversity in most coastal parts of the lake is negligible, due to only small changes in lake surface area, coastline, and habitat. In contrast, biodiversity in shallower areas was more severely affected due to disconnection of today sub-lacustrine springs from the main water body. Multichannel seismic data from deeper parts of the lake clearly image several clinoform structures stacked on top of each other. These stacked clinoforms indicate significantly lower lake levels prior to MIS 6 and a stepwise rise of water level with intermittent stillstands since its existence as water-filled body, which might have caused enhanced expansion of endemic species within Lake Ohrid.

K. Lindhorst; H. Vogel; S. Krastel; B. Wagner; A. Hilgers; A. Zander; T. Schwenk; M. Wessels; G. Daut

2010-01-01

140

[Seasonal fluctuations in fluoride content in waters of the Warta oxbow lake in Lubon].  

UK PubMed Central (United Kingdom)

Studies were carried out in 2002-2003 at the Department of Inland Fishing and Aquaculture, Agricultural University of Pozna?, on seasonal fluctuations in fluoride content in waters of the Warta oxbow lake in Lubo? (52 degrees 19' N, 16 degrees 53' E). This reservoir has been loaded during several decades with fluorine compounds, originating from the deposits of post-crystallization lye of aluminum fluoride and fluorosilicic acid. The greatest amounts of fluorine compounds were deposited in the bottom sediments in the deepest part of the reservoir. On the basis of these two-year observations it was concluded that the concentration of fluoride in water is subject to significant variations (between 1.0 and 6.2 mg F(-)/L). The lowest fluoride concentration in water was recorded during vernal circulation. On the other hand, the highest values were found in the bottom water layer during the summer stagnation. Seasonal fluctuations in fluoride content in waters of the Warta oxbow lake were closely connected with mineralization in the bottom sediment as revealed by oxygen deficiencies in the bottom water layer.

Jezierska-Madziar M; Pi?skwar P; Golski J

2004-01-01

 
 
 
 
141

[Seasonal fluctuations in fluoride content in waters of the Warta oxbow lake in Lubo?].  

Science.gov (United States)

Studies were carried out in 2002-2003 at the Department of Inland Fishing and Aquaculture, Agricultural University of Pozna?, on seasonal fluctuations in fluoride content in waters of the Warta oxbow lake in Lubo? (52 degrees 19' N, 16 degrees 53' E). This reservoir has been loaded during several decades with fluorine compounds, originating from the deposits of post-crystallization lye of aluminum fluoride and fluorosilicic acid. The greatest amounts of fluorine compounds were deposited in the bottom sediments in the deepest part of the reservoir. On the basis of these two-year observations it was concluded that the concentration of fluoride in water is subject to significant variations (between 1.0 and 6.2 mg F(-)/L). The lowest fluoride concentration in water was recorded during vernal circulation. On the other hand, the highest values were found in the bottom water layer during the summer stagnation. Seasonal fluctuations in fluoride content in waters of the Warta oxbow lake were closely connected with mineralization in the bottom sediment as revealed by oxygen deficiencies in the bottom water layer. PMID:16892585

Jezierska-Madziar, Maria; Pi?skwar, Piotr; Golski, Janusz

2004-01-01

142

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

Science.gov (United States)

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

Niedzielski, Tomasz; Kosek, Wieslaw

2010-01-01

143

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

2012-01-01

144

Level Densities of ^28Si, ^46Ti, ^52Cr and ^60Ni from Ericson Fluctuations  

Science.gov (United States)

Level densities in the continuum region are deduced in the compound nuclei of ^28Si, ^46Ti, ^52Cr and ^60Ni using thick target measurements and an Ericson fluctuation analysis of the reactions ^27Al(p,n), ^45Sc(p,n), ^51V(p,n) and ^59Co(p,n) respectively. A high resolution neutron spectra were measured in the range of neutron energies from 0.8 to 2.0 MeV with a bar of pastic scintillator viewed at both ends and the back by photomultipliers. Both NIM and CAMAC electronics were used in the electronic system. Time of flight techniques were used for the neutron identification with a flight path of 20 meters. Comparison of the deduced level densities with the most recent level density compilations will be also presented. This work was supported under U.S. D.O.E grant No. DE-FG02-88ER40387.

Salas-Bacci, Americo; Grimes, Steven M.; Massey, Thomas N.; Parpottas, Yannis; Wheeler, Raymond T.; Oldendick, James E.

2003-04-01

145

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

UK PubMed Central (United Kingdom)

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 13C-derived intrinsic water use efficiency (WUEi) 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 ?18O 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.

Battipaglia G; DE Micco V; Brand WA; Saurer M; Aronne G; Linke P; Cherubini P

2013-07-01

146

Earthquake induced well level fluctuations in Koyna-Warna area of enhanced reservoir induced seismicity  

Science.gov (United States)

An Indo-German research program is investigating possible in-situ pore pressure fluctuations associated with earthquakes in the Koyna-Warna Region, Maharashtra, India. The area is ideal for such a study as induced seismicity has occurred here since the impounding of the Koyna Dam Reservoir in 1962 and is probably highest in the world. Beginning in 1995, we have drilled 21 bore wells, 90 to 250 m deep, in the Deccan trap basalts of the region. The wells are equipped with pressure transducers and recording systems apt for monitoring changes in well level heights. Tidal signals are clearly observed in most of the well level data, which suggests that the wells are sensitive to small strain changes in the connected rock formations. Till now, we have observed at least 6 local earthquakes which have induced co-seismic well level anomalies in two or more wells. The strongest event had M 5.2 (September 5, 2000) and has significantly affected the well level height in seven wells. Occasionally, some precursory anomaly appears to be present in the data, with lead times of several days up to a few weeks - which needs, however, further analysis. Remarkably, well level fluctuations in nearby wells do sometimes correlate during intervals where no earthquakes occurred. Given the high strain-sensitivity of the probed well-aquifer systems, this could be due to local-regional stress changes at rather shallow depths The data set which is being obtained in the Koyna-Warna area may be a valuable source of information about the effective rheology of stressed continental crust.

Chadha, R. K.; Kuempel, H.-J.

2003-04-01

147

Water Level Modeling around German Bight  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work investigates the water level data measured in 18 stations around the German Bight from 1953 to 2006. It is the most useful hydrometric data to measure a water body and to do a forecasting for specific extreme risks. Our water level data are both temporal and spatial. We apply first stoc...

Cao, Xiaofeng

148

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

149

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

International Nuclear Information System (INIS)

[en] 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

150

Water table fluctuation and its effects on vegetation in a semiarid environment  

Directory of Open Access Journals (Sweden)

Full Text Available A good understanding of water table fluctuation effects on vegetation is crucial for sustaining fragile hydrology and ecology of semiarid areas such as the Horqin Sandy Land (HSL) in northern China, but such understanding is not well documented in literature. The objectives of this study were to examine spatio-temporal variations of water table and their effects on vegetation in a semiarid environment. A 9.71 km2 area within the HSL was chosen and well-instrumented to continuously measure hydrometeorologic parameters (e.g., water table). The area comprises of meadow lands and sandy dunes as well as transitional zones in between. In addition to those measured data, this study also used Landsat TM and MODIS imageries and meteorological data at a station near the study area. The spatio-temporal variations were examined using visual plots and contour maps, while the effects on vegetation were determined by overlaying a water table depth map with a vegetation index map derived from the MODIS imageries. The results indicated that water table was mainly dependent on local topography, localized geological settings, and human activities (e.g., reclamation). At annual and monthly scales, water table was mainly a function of precipitation and potential evapotranspiration. A region within the study area where depth to water table was smaller tended to have better (i.e., more dense and productive) vegetation cover. Further, the results revealed that water table fluctuation was more sensitive for vegetations in the meadow lands than in the transitional zones, but it was least sensitive for vegetations in the sandy dunes.

L. Duan; T. Liu; X. Wang; Y. Luo; W. Wang; X. Liu

2011-01-01

151

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

152

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

153

Monitoring of ground water levels, Hadano Basin  

Energy Technology Data Exchange (ETDEWEB)

The ground water levels in the Hadano Basin have been monitored in 20 wells. This paper deals with the fractuation of water levels observed in nine years from 1975 and 1983. The drop rate of ground water level is 5.7 cm/year in the recharge area. In the central part of the basin at the west side of the Mizunashi river, the drop rate is 4.7 cm/year and at its east side the drop rate is 0.1 cm/year. No water level drop is recognized in the discharge area of the basin. 1 reference, 20 figures.

Nagase, K.; Koizumi, Y.; Furihara, S.

1984-01-01

154

Climate change and water level impacts on wetlands: A bibliography  

Energy Technology Data Exchange (ETDEWEB)

Climate change may significantly alter the water resources of North America, and an altered water regime in the Great Lakes basin would affect the presence and ecological viability of the coastal wetlands linked to the basin. As part of a study to determine the physical, biological and socioeconomic impacts of water level fluctuations on coastal wetlands, a literature review was conducted. Emphasis was placed on works detailing the effects of historical water level changes on Great Lakes coastal wetlands. More than 540 citations for the period of 1935-1991 are provided. The references are divided into four main subject areas: wetlands, climate and water levels; wetland functions and values; wetlands of Canada and North America; and climate change, water resources and the Great Lakes. Citations are further subdivided into more specific topics and are listed alphabetically by author and then by year. The references include published materials such as journals, workshop results, conference and symposium proceedings, technical manuals and government agency reports, and also unpublished work such as theses and government documents. 546 refs.

Koshida, G.; Mortsch, L.

1991-01-01

155

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

CERN Multimedia

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

156

A demonstration of precise calibration of tropospheric delay fluctuations with water vapor radiometers  

Science.gov (United States)

The ability of water vapor radiometers (WVRs) to calibrate changes in tropospheric delay was demonstrated during very long baseline radio interferometer (VLBI) observations at Goldstone, California. WVR measurements reduced the observed VLBI delay variations over a 13 hr period by a factor of ?2.5. When applied to shorter time scales, a ?50% reduction in 100-700 s delay variations was achieved during conditions of high tropospheric activity. Thermal WVR noise precluded calibration of short time scale delay fluctuations during quiet tropospheric conditions.

Teitelbaum, L. P.; Keihm, S. J.; Linfield, R. P.; Mahoney, M. J.; Resch, G. M.

157

Clastic sequences developed during glacio-eustatic sea level fluctuations on a sandy barrier coastline  

Energy Technology Data Exchange (ETDEWEB)

Seismic reflection (Geopulse) profiles from a 125 km{sup 2} grid on the New Jersey low-mesotidal sandy barrier coastline reveal a 30-m sediment thickness composed of three unconformity bounded parasequences. Vibracores from 12 sites reveal a variety of depositional environments that existed during the most recent glacio-eustatic sea level fluctuations on this stable passive margin. Environments include fluvial, during glacial lowstands; barrier islands with back-barrier lagoons and pro-barrier ebb tidal deltas and shore-attached ridges; and below storm-wave base shelves during interglacial highstands. Following the last major interglacial (Sangamon, {approx} 125KA), sea level fell and rivers eroded a planar seaward dipping surface by the early Wisconsinan time ({approx}70KA). As sea level rose during the mid-Wisconsinan ({approx} 50KA), a barrier island shoreline migrated to within 0.2-1.7 km of the modern shoreline. Maximum highstand of mid Wisconsinan sea level was 20 m below present. Sea level fell again during the late Wisconsinan ({approx}20KA). A barrier island/lagoonal system developed under rising sea level at least by the early middle Holocene based on peats (8,800 BP) in lagoonal muds cored from {minus}12 m. The root of the mid-Wisconsinan barrier system was preserved under early Holocene transgressive sediments. The modern coastal and inner continental shelf deposits are relatively thin (3-4 m) pebbly sands overlying a prominent ravinement surface unconformity formed during the Holocene sea level rise. Isopach maps constructed for this surface indicate up to 7 m of relief eroded into muds beneath the ebb tidal delta and the shore-attached ridges. The ridges and delta shielded the underlying fine sediments during sea level rise. Based on a reasonable Atlantic shoreline transgression rate of 2 m/yr, the modern Barnegat Inlet ebb tidal delta has existed in its general location for at least 800 years.

Ashley, G.M.; Sheridan, R.E.; Wellner, R.W. (Rutgers, The State Univ. of New Jersey, New Brunswick (USA))

1990-05-01

158

Recommendations for designing coastal-protection actions in conditions of the significant periodic fluctuations of the sea level / ???????????? ??? ?????????????? ?????????????? ??????????? ? ???????? ?????-??????? ????????????? ????????? ?????? ????  

Directory of Open Access Journals (Sweden)

Full Text Available In clause questions of designing coastalprotection actions in conditions of significant fluctuations of a level of reservoirs are considered. During catastrophic rise of a level of Caspian sea by the various organizations the extensive complex of scientifically-design works and projects of coastalprotection the Caspian coast of Russia has been executed. In clause the basic results of dissertational work of the author, devoted to the complex analysis of the executed works and development on this base of recommendations for designing coastalprotection actions in conditions of essential fluctuations of a level of reservoirs are resulted. / ??????????? ??????? ?????????????? ?????????????? ??????????? ? ???????? ???????????? ????????? ?????? ????????. ????????? ???????? ?????????? ??????????????? ?????? ??????, ??????????? ??????? ????????? ????????? ??????-????????? ????? ?? ???????????? ??????????? ????????? ?????? ? ?????????? ?? ???? ???? ???????????? ??? ?????????????? ?????????????? ??????????? ? ???????? ???????????? ????????? ?????? ????????.

Dashkevich A.V. / ???????? ?????? ??????????

2009-01-01

159

Fluctuations in human milk long-chain PUFA levels in relation to dietary fish intake  

DEFF Research Database (Denmark)

Within the Danish population, milk DHA (22:6n-3) levels vary by more than a factor of 10. This paper deals with fluctuations in the milk content of 22:6n-3 and other long-chain PUFA (LCPUFA) and the acute effects of fish meals and fish oil supplements on milk levels of LCPUFA. Twelve fish-eating mothers with 4-mon-old infants provided one blood and one adipose tissue sample, and seven consecutive morning hindmilk samples with dietary records from the previous days. Another 12 lactating women were given fish oil (2-8 g) for breakfast and delivered 6-12 milk samples during the following 24 h. The mean milk 22:6n-3 content of the fish-eating mothers was 0.57 ± 0.28 FA% (= percentage of total area of FAME peaks in GLC) and the day-to-day variation (SD/mean) within the individual was 35 ± 17%. Mean milk 22:6n-3 content on mornings with no fish the day before was 0.42 ± 0.15 FA%; this was increased by 82 ± 17% (n = 9, P = 0.05) if the mother had eaten fatty fish. Fish oil resulted in a twofold increase in milk 22:6n-3 levels, which peaked after 10 h and lasted for 24 h. The EPA content of milk was also increased by fish meals and fish oil supplements, but these had no effect on the level of arachidonic acid. The study showed that diurnal and day-to-day fluctuations in levels of milk n-3 LCPUFA are large, which makes it difficult to assess the 22:6n-3 intake of breast-fed infants from a single milk sample. In studies of the functional outcome of dietary 22:6n-3 in breast-fed infants it is suggested also to use a measure of maternal 22:6n-3 status.

Lauritzen, L.; Michaelsen, K.F.

2002-01-01

160

Development of Mechanical Water Level Controller  

Directory of Open Access Journals (Sweden)

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

Akonyi Nasiru Sule; Chinedu Cletus Obinwa; Christian Ebele Okekeze; Eyo Ifreke

2012-01-01

 
 
 
 
161

Water cooling tower and water level control system therefor  

Energy Technology Data Exchange (ETDEWEB)

This patent describes an improved water cooling tower system including a water cooling tower structure having a top portion, a bottom portion, an intermediate portion therebetween, a water-collecting basin operatively disposed in the bottom portion of the structure, a heat exchange means operatively disposed in the intermediate portion of the structure, means for recirculating the water from the water-collecting basin to the top portion of the structure and feeding the recirculated water into the top of the heat exchange means, means for moving air through the heat exchange means drawing heat from the water for evaporating a portion of the water while cooling the non-evaporated water, means for utilizing the cooled water for at least one of air-conditioning and water-cooling purposes, conduit means operatively coupling a source of fresh water to the water-collecting basin for restoring the water lost in the evaporation process, the conduit means including a signal-responsive hydraulic valve means operatively coupled therein, the hydraulic valve means including a water inlet, a water outlet, a control port, and means responsive to the control signals at the control port for opening and closing the hydraulic valve means, the hydraulic valve mans being responsive to an ADD WATER control signal for passing the fresh make-up water through the fresh water conduit to the water-collecting basin and being further responsive to a DON'T ADD control signal for preventing the passage of fresh make-up water through the conduit means, the water in the water-collecting basin having a predetermined desired water level.

Kinkead, C.W.

1989-06-06

162

Trend Estimation of Blood Glucose Level Fluctuations Based on Data Mining  

Directory of Open Access Journals (Sweden)

Full Text Available We have fabricated calorie-calculating software that calculates and records the total calorific food intake by choosing a meal menu selected using a computer mouse. The purpose of this software was to simplify data collection throughout a person's normal life, even if they were inexperienced computer operators. Three portable commercial devices have also been prepared a blood glucose monitor, a metabolic rate monitor and a mobile-computer, and linked into the calorie-calculating software. Time-course changes of the blood glucose level, metabolic rate and food intake were measured using these devices during a 3 month period. Based on the data collected in this study we could predict blood glucose levels of the next morning (FBG) by modeling using data mining. Although a large error rate was found for predicting the absolute value, conditions could be found that improved the accuracy of the predicting trends in blood glucose level fluctuations by up to 90 %. However, in order to further improve the accuracy of estimation it was necessary to obtain further details about the patients' life style or to optimise the input variables that were dependent on each patient rather than collecting data over longer periods.

Masaki Yamaguchi; Shigenori Kambe; Karin Wårdell; Katsuya Yamazaki; Masashi Kobayashi; Nobuaki Honda; Hiroaki Tsutsui; Chosei Kaseda

2003-01-01

163

Rotational fluctuations of water confined to layered oxide materials: nonmonotonous temperature dependence of relaxation times.  

Science.gov (United States)

The rotational molecular dynamics of water confined to layered oxide materials with brucite structure was studied by dielectric spectroscopy in the frequency range from 10(-2) to 10(7) Hz and in a broad temperature interval. The layered double hydroxide samples show one relaxation process, which was assigned to fluctuations of water molecules forming a layer, strongly adsorbed to the oxide surface. The temperature dependence of the relaxation rates has an unusual saddlelike shape characterized by a maximum. The model of Ryabov et al. (J. Phys. Chem. B 2001, 105, 1845) recently applied to describe the dynamics of water molecules in porous glasses is employed also for the layered materials. This model assumes two competing effects: rotational fluctuations of water molecules that take place simultaneously with defect formation, allowing the creation of free volume necessary for reorientation. The activation energy of rotational fluctuations, the energy of defect formation, a pre-exponential factor, and the defect concentration are obtained as main parameters from a fit of this model to the data. The values of these parameters were compared with those found for water confined to nanoporous molecular sieves, porous glasses, or bulk ice. Several correlations were discussed in detail, such as the lower the value of the energy of defect formation, the higher the number of defects. The pre-exponential factor increases with increasing activation energy, as an expression of the compensation law, and indicates the cooperative nature of the motional process. The involvement of the surface OH groups and of the oxygen atoms of the interlayer anions in the formation of hydrogen bonds was further discussed. For the birnessite sample, the relaxation processes are probably overlaid by a dominating conductivity contribution, which is analyzed in its frequency and temperature dependence. It is found that the conductivity of birnessite obeys the characteristics of semiconducting disordered materials. Especially the Barton/Nakajima/Namikawa relationship is fulfilled. Analyzing the temperature dependence of the direct current (dc) conductivity sigma0 in detail gives some hint that sigma0(T) has also an unusual saddlelike form. PMID:17536791

Frunza, Ligia; Schönhals, Andreas; Frunza, Stefan; Parvulescu, Vasile I; Cojocaru, Bogdan; Carriazo, Daniel; Martín, Cristina; Rives, Vicente

2007-05-31

164

Effects of high and fluctuating pressure on microbial abundance and activity in a water hydraulic system.  

Science.gov (United States)

The effects of high and fluctuating pressure up to 220 bar on microbial growth and activity were determined in a pilot-scale water hydraulic system. An increase in the pipeline pressure from 70 to 220 bar decreased the total and the viable cell number in the pressure medium from 2.2(+/-0.5)x10(5) to 4.9(+/-1.5)x10(4) cells/ml and from 5.7(+/-2.8)x10(4) to 1.3(+/-0.7)x10(4) cfu/ml, respectively. Microbial attachment in the non-pressurised tank of the hydraulic system increased with increasing pipeline pressure [from 1.0(+/-0.3) to 3.8(+/-2.7)x10(5) cells/cm(2) on stainless steel]. The phosphatase, aminopeptidase and beta-glucosidase activities in the pressurised medium were between 0.02 and 1.4 micromol/lh ( V(max)) and decreased in response to increasing pipeline pressure. The alpha-glucosidase activity was detected only at 70 bar and the glucuronidase activity only occasionally. Based on principal component and cluster analyses, both the pressure applied and the original filling water quality affected substrate utilisation patterns. This study demonstrated the capability of freshwater bacteria to tolerate high and fluctuating pressure in a technical water system. Microbial survival was due to attachment and growth on the surfaces of the non-pressurised components and the nutrient flux released by cell lysis in the pressurised components. In summary, high pressures in water hydraulic systems do not prevent potential microbiologically related operational problems. PMID:11956752

Soini, S M; Koskinen, K T; Vilenius, M J; Puhakka, J A

2002-02-08

165

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

166

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

Directory of Open Access Journals (Sweden)

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

Cesáreo Landeros-Sánchez; Ma. del Refugio Castañeda-Chávez; Fabiola Lango-Reynoso; Itzel Galaviz-Villa

2012-01-01

167

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

Directory of Open Access Journals (Sweden)

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; Okada Yosuke; Mori Hiroko; Tanaka Yoshiya

2013-01-01

168

Remote forcing of East African rainfall and relationships with fluctuations in levels of Lake Victoria  

Science.gov (United States)

This study investigates the climatological variables responsible for fluctuations in Lake Victoria levels, in particular the causal mechanism responsible for a major anomaly that occurred in 1961. A Lake Victoria rainfall series (LVRS) correlates significantly (5%) with Lake Victoria levels and is utilized for subsequent analysis of rainfall variability. Relationships between annual and seasonal (March-May and October-December (OND)) LVRS and a number of tropical and extra-tropical series were analyzed. The results illustrate the dominance of the El Niño-Southern Oscillation phenomenon in modulating LVRS. The greatest correlation is found between LVRSOND and the Southern Oscillation index (r = -0.39, significant at the 1% level), although the relationship is non-linear over the course of the century.Velocity potential is employed as the principal diagnostic variable. Seasonal composite maps and empirical orthogonal function (EOF) analysis of Indian Ocean region -fields are utilized to test the hypothesis that an Indian Ocean Walker cell is responsible for the anomalous 1961 rainfall episode. Subsequent analysis leads to the rejection of this hypothesis. EOF analysis of OND 200 hPa -fields reveals a number of modes of tropical variability. EOF analysis of the Indian Ocean basin illustrates the emergence of a meridional circulation directed over the Indian Ocean (EOF5). This time series correlates significantly with LVRSOND (r = -0.40, 1% level), although the spatial pattern only explains a small proportion (2.35%) of the total variance. analysis for OND over the broader tropical region reveals significant relationships (5%) between OND EOF3* and July-September Sahel rainfall for the preceding season and subsequent year. This relationship may assist future long-lead seasonal forecast schemes for the Sahel region.

Mistry, Vinay V.; Conway, Declan

2003-01-01

169

Manganese oxidation induced by water table fluctuations in a sand column.  

UK PubMed Central (United Kingdom)

On-off cycles of production wells, especially in bank filtration settings, cause oscillations in the local water table, which can deliver significant amounts of dissolved oxygen (DO) to the shallow groundwater. The potential for DO introduced in this manner to oxidize manganese(II) (Mn(II)), mediated by the obligate aerobe Pseudomonas putida GB-1, was tested in a column of quartz sand fed with anoxic influent solution and subject to 1.3 m water table changes every 30-50 h. After a period of filter ripening, 100 ?M Mn was rapidly removed during periods of low water table and high dissolved oxygen concentrations. The accumulation of Mn in the column was confirmed by XRF analysis of the sand at the conclusion of the study, and both measured net oxidation rates and XAS analysis suggest microbial oxidation as the dominant process. The addition of Zn, which inhibited GB-1 Mn oxidation but not its growth, interrupted the Mn removal process, but Mn oxidation recovered within one water table fluctuation. Thus transient DO conditions could support microbially mediated Mn oxidation, and this process could be more relevant in shallow groundwater than previously thought.

Farnsworth CE; Voegelin A; Hering JG

2012-01-01

170

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

International Nuclear Information System (INIS)

[en] 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)

2002-01-01

171

The effect of the last 4000 years` of climate fluctuations in Eretz Israel on the Dead Sea level and man  

Energy Technology Data Exchange (ETDEWEB)

The article discusses various landmarks revealed at different times in history by the dropping of the level of the Dead Sea. Records of rainfall during the last 4000 years are quoted. The fluctuations involved only the extent of winter rainfall. 2 refs.

Klein, C. [Ministry of Agriculture, Jerusalem (Israel). Israel Hydrological Service

1993-09-01

172

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; DARABOS, Enik?

2012-01-01

173

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; M.E. Varela; E. Benito

2013-01-01

174

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.

Kar, T.; Destain, J.; Thonart, P.; Delvigne, F.

2010-01-01

175

Soil migration and plant uptake of technetium from a fluctuating water table  

International Nuclear Information System (INIS)

[en] Soil columns (50 x 15 cm) were used to determine the potential for 95mTc (as a surrogate for 99Tc which is an important component of some radioactive waste) to migrate from a contaminated, fluctuating water table, through sandy loam soil and into perennial ryegrass. Upward migration was significantly retarded with, generally, only the bottom few centimetres of soil becoming contaminated over the 6 months of the experiment. This is thought to have been due to the presence of anoxic conditions within the water table leading to the reduction of pertechnetate to TcIV species which are relatively insoluble. However, some evidence of very slow upward migration over time was found. Only a small and inconsistent transfer of activity into the perennial ryegrass was observed. Whilst these observations would suggest that 99Tc is less important than radionuclides such as 129I and 36Cl in terms of the risk associated with radioactive waste disposal, the potential for a slow upward migration, and/or a pulse-release following the re-oxidation of reduced soil in which 99Tc has accumulated should not be overlooked

2005-01-01

176

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.

1061-01-00

177

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

178

Fluctuation of serum C3 levels reflects disease activity and metabolic background in patients with IgA nephropathy.  

UK PubMed Central (United Kingdom)

BACKGROUND: We focused on the fluctuations of serum C3 levels throughout the clinical course of patients and investigated the relationship between these fluctuations and clinical findings. METHODS: IgA nephropathy patients (n = 122) were enrolled in the present study. Serum C3 and other clinical markers were compared at the time of renal biopsy and at last follow-up (6.67 ± 2.07 years). Patients were divided into 3 groups based on serum C3 levels: Group I with first C3 levels below the mean -1 SD, which turned into an increase at last observation; group II with first C3 levels more than the mean +1 SD, which turned into a decrease at last observation; and group III, with first C3 levels more than the mean +1 SD, which turned into an increase at last observation. First and last levels of clinical markers were compared among the 3 groups. RESULTS: Serum C3 levels of the patients whose renal symptoms, including hematuria, proteinuria and estimated glomerular filtration rate (eGFR), were improved, were significantly increased at last observation (p<0.05, p<0.01, p<0.01, respectively). Age, total cholesterol and triglyceride levels in group III were significantly higher than those in group I. Group II showed a significant reduction of urinary protein. Groups I and II maintained renal function, but group III showed a significant deterioration of renal function. CONCLUSIONS: The levels and fluctuations of serum C3 might reflect the disease activity and metabolic alteration in patients with IgA nephropathy.

Suzuki H; Ohsawa I; Kodama F; Nakayama K; Ohtani A; Onda K; Nagamachi S; Kurusu A; Suzuki Y; Ohi H; Horikoshi S; Tomino Y

2013-07-01

179

Hydro static water level systems at Fermilab  

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-09-01

180

Hydro static water level systems at Fermilab  

International Nuclear Information System (INIS)

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

2006-01-01

 
 
 
 
181

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

182

Entanglement between a pair of spatially separated two-level atoms induced by zero-point field fluctuations  

CERN Document Server

We have considered the interaction of a pair of spatially separated two-level atoms with the electromagnetic field in its vacuum state and we have analyzed the amount of entanglement induced between the two atoms by the non local field fluctuations. This has allowed us to characterize the quantum nature of the non local correlations of the electromagnetic field vacuum state as well as to link the induced quantum entanglement with Casimir-Polder potentials.

Cirone, M A; Palma, G M; Passante, R; Persico, F S; Cirone, Markus.A.; Compagno, Giuseppe; Passante, Roberto; Persico, Francesco S.

2004-01-01

183

Coarse grained normal mode analysis vs. refined Gaussian Network Model for protein residue-level structural fluctuations.  

UK PubMed Central (United Kingdom)

We investigate several approaches to coarse grained normal mode analysis on protein residual-level structural fluctuations by choosing different ways of representing the residues and the forces among them. Single-atom representations using the backbone atoms C(?), C, N, and C(?) are considered. Combinations of some of these atoms are also tested. The force constants between the representative atoms are extracted from the Hessian matrix of the energy function and served as the force constants between the corresponding residues. The residue mean-square-fluctuations and their correlations with the experimental B-factors are calculated for a large set of proteins. The results are compared with all-atom normal mode analysis and the residue-level Gaussian Network Model. The coarse-grained methods perform more efficiently than all-atom normal mode analysis, while their B-factor correlations are also higher. Their B-factor correlations are comparable with those estimated by the Gaussian Network Model and in many cases better. The extracted force constants are surveyed for different pairs of residues with different numbers of separation residues in sequence. The statistical averages are used to build a refined Gaussian Network Model, which is able to predict residue-level structural fluctuations significantly better than the conventional Gaussian Network Model in many test cases.

Park JK; Jernigan R; Wu Z

2013-01-01

184

Modern Risks of Anthropogenic Influence on Living Species: Nano-Level Fluctuation  

Science.gov (United States)

Taking into consideration oncoming global change, basic researches, concerning prospects of the use the modern methods of modeling in such important aspect as reactions of living organism on miscellaneous level hierarchy on risks, appearing as a result these change become exceedingly actual. Using different methods of modeling, generalized experimental material, we managed consider in detail some changes of the biological processes on different hierarchy levels (cellular, organism and population) in response to risks, appearing in ecosystems. In particular, processes of the shaping new desert in context of global desertification were modeled; possible mechanisms of speciation of living organism in radiation—chemical stress and mutation are described. The enzymes degradation models were worked out. On base of these experimental results the phenomena of negative geotropism of root system at influence of specifically dangerous xenobiotics (in particular, chlororganic) and thick water insoluble polymeric covering is considered. Besides, attempt of modeling of complex interaction in ecosystems in condition ecological crisis is realized. In spite of different levels of models, they, on our point of view, can illustrate the interaction of nanoworld with sharply changing condition of the environment and give the approaches to creation new technology. Consideration of these models is important and with standpoint of the estimation of risk and that difficulties, which faces the mankind at period of the oncoming global change of ecosystems under influence of different “on its nature” calls.

Ruban, I.; Sharipov, M.; Voropaeva, N.; Magarshak, Yu.

185

Detecting drawdowns masked by environmental stresses with water-level models.  

UK PubMed Central (United Kingdom)

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 during the period of record. Pumping signals are generated with Theis models, where the pumping schedule is translated into water-level change with the Theis solution. This approach closely matched drawdowns simulated with a complex three-dimensional, hypothetical model and reasonably estimated drawdowns from an aquifer test conducted in a complex hydrogeologic system. Pumping-induced changes generated with a numerical model and analytical Theis model agreed (RMS as low as 0.007 m) in cases where pumping signals traveled more than 1 km across confining units and fault structures. Maximum drawdowns of about 0.05 m were analytically estimated from field investigations where environmental fluctuations approached 0.2 m during the analysis period.

Garcia CA; Halford KJ; Fenelon JM

2013-05-01

186

Sea-level and salinity fluctuations during the Paleocene-Eocene thermal maximum in Arctic Spitsbergen  

Science.gov (United States)

Palaeoenvironmental manifestations of the Paleocene-Eocene thermal maximum (PETM; ~ 56 Ma) are relatively well documented in low- to mid-latitude settings and at high southern latitudes, but no documented high northern latitude sites record the entire hyperthermal event. We present high-resolution multi-proxy records from a PETM succession on Spitsbergen in the high Arctic (palaeolatitude ~ 75 °N). By comparing our results with those from Integrated Ocean Drilling Program Site 302-4A, we document regional palaeoenvironmental variations in the expression of the PETM, with evidence for major differences in basin-margin vegetation and water column oxygen depletion. Sedimentological, palynological and geochemical data demonstrate a pre-PETM sea level rise in Spitsbergen before the - 4‰ ?13CTOC excursion, which culminated in maximum flooding during the peak of the event. The appearance of the dinoflagellate cyst Apectodinium before the onset of the carbon isotope excursion (CIE) corroborates that environmental change in the Arctic had begun prior to the CIE. Sedimentological and palynological evidence indicate that elevated terrestrial runoff resulted in water column stratification, providing further evidence for an intensification of the hydrological cycle during the PETM.

Harding, Ian C.; Charles, Adam J.; Marshall, John E. A.; Pälike, Heiko; Roberts, Andrew P.; Wilson, Paul A.; Jarvis, Edward; Thorne, Robert; Morris, Emily; Moremon, Rebecca; Pearce, Richard B.; Akbari, Shir

2011-02-01

187

Fluctuating lattice Boltzmann  

CERN Document Server

We introduce a fluctuating lattice Boltzmann equation in which the noise satisfies a fluctuation-dissipation theorem directly at lattice level. This ensures proper thermalization of the so-called `ghost' modes which otherwise constantly drain thermal energy out of the system. Our approach produces correct thermal fluctuations for the mass density, momentum density, and stress, thus recovering the equations of (isothermal) fluctuating nonlinear hydrodynamics at large wavelengths and long times. Our method promises efficient, accurate simulation of fluctuating mesoscopic fluids.

Adhikari, R; Stratford, K; Wagner, A

2004-01-01

188

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

UK PubMed Central (United Kingdom)

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

Shilo K; Appelbaum G; Noter Y

1979-09-01

189

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

Directory of Open Access Journals (Sweden)

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

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

2011-01-01

190

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in english 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 Cor (more) relation 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.

Furlanetto, Rafael Lacerda; Facio Jr, Antonio Carlos; Hatanaka, Marcelo; Susanna Junior, Remo

2010-01-01

191

Water levels in continuously monitored wells in the Yucca Mountain Area, Nevada, 1989  

International Nuclear Information System (INIS)

Water levels have been monitored hourly in 16 wells representing 24 intervals in the Yucca Mountain area, Nevada. Water levels were monitored using pressure transducers and were recorded by data loggers. The pressure transducers were periodically calibrated by raising and lowering them in the wells. The water levels were normally measured at approximately the same time that the transducers were calibrated. Where the transducer output appeared reasonable, it was converted to water levels using the calibrations and manual water-level measurements. The amount of transducer output that was converted to water levels ranged from zero for one interval to 100 percent for one interval. Fifteen of the wells were completed in Tertiary volcanic rocks and one well was completed in Paleozoic carbonate rocks. Each well monitored from one to four depth intervals. Water-level fluctuation caused by barometric pressure changes and earth tides were observed. Transducer output is presented in graphic form and, where appropriate, water-level altitude is presented in graphical and tabular form

1995-01-01

192

Unraveling the climatic causes of past lake level change using lake energy and water balance models  

Science.gov (United States)

Lake level records provide a rich resource of information about past variations in surface water, a resource likely to experience significant impacts under future climate change. The water balance of a lake is controlled by a variety of climate variables, including precipitation, radiation, humidity, and wind speed, and it can be difficult to pinpoint the exact climatic causes of past lake level fluctuations. This understanding is crucial, however, for predicting whether surface water resources will diminish in the future. In this research, we use output from a coupled atmosphere-ocean general circulation model to force lake energy and water balance models over East Asia and Arid Central Asia to test hypotheses about the causes of lake level variations during the Holocene and Last Glacial Maximum. We find that changes in evaporation tend to work in concert with precipitation changes to maximize lake level fluctuations. This occurs because high levels of precipitation are associated with increased cloudiness and humidity and decreased shortwave radiation, which all lead to decreased lake evaporation. There is also a significant effect of changes in winter insolation on the annual duration of lake ice cover and lake evaporation. These findings help to explain some of the differences in lake level observed between monsoonal Asia and Arid Central Asia and can be generalized to other parts of the globe.

Morrill, C.; Li, Y.

2009-12-01

193

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

DEFF Research Database (Denmark)

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

Nielsen, K.A.; Dahl, M.

2008-01-01

194

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

International Nuclear Information System (INIS)

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

1979-01-01

195

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

196

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

International Nuclear Information System (INIS)

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

1997-01-01

197

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

CERN Multimedia

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

Okumura, Y; Misaki, A

2010-01-01

198

?????????????????????? Necessity and Methods for Reservoir Seasonal Drought Control Water Level  

Directory of Open Access Journals (Sweden)

Full Text Available ???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? Similar to the reservoir flood control water level, the drought control water level, though a new concept, is very important for reservoir drought relief operation. The definition and the importance of the drought control water level has been introduced and discussed. Some theoretical methods on the drought control water level, including the necessity of the seasonal control and how to determinate the seasonal values, have been pointed out. The reservoir drought control water level can be a guide for the further improving the management of drought, which also plays an important role in water supply engineering programming and water resources optimal allocation.

??; ???; ???; ??

2012-01-01

199

The fluctuation of serum C-reaction protein level in patients with cerebral infarction  

UK PubMed Central (United Kingdom)

The serum CRP level was determined serially (on day 1,7 and 14 after onsets) by immune turbidity method in 66 patients with ACI and 45 normal controls. In ACI group, the serum CRP level increased on first day was sighnificantly (P<0.01) higher than that in the controls, showing a highest serum CRP level in severe patients. It reached the peak on seventh day and then tended to decrease gradually. This study suggests that high serum CRP level may play a role in the development of ACI, and serum CRP level is positively correlated with severity extent of ACI.

Huang Yonghua; Zhang Weiwei; Zhou Xiaoying; Bai Hengchu; Wei Yazhou; Li Juan

2004-01-01

200

Stratigraphic study of beach features on the southwestern shore of Lake Michigan: new evidence of Holocene lake-level fluctuations. Environmental geology notes  

International Nuclear Information System (INIS)

Research conducted in the Chicago area over the past decade has resulted in detailed interpretation of changes. Stratigraphic studies, coupled with radiocarbon dating, indicate that conspicuous fluctuations of Lake Michigan have occurred during the past 2,000 years - a period previously recognized as one of relatively stable levels. Results of this study indicate a pattern of lake level changes not discernible in the 125-year historically recorded and measured changes; the historically recorded changes in lake level represent only part of a long-term, naturally fluctuating trend that in some cases may have exceeded the maxima and minima of the historically-recorded lake levels

1985-01-01

 
 
 
 
201

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

CERN Document Server

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

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

2003-01-01

202

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

Energy Technology Data Exchange (ETDEWEB)

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

Casey, Daniel

1987-08-01

203

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

Science.gov (United States)

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

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

2009-11-01

204

The Midway Atoll coral cap: Meteoric diagenesis, amplitude of sea-level fluctuation and dolomitization  

Science.gov (United States)

A continuously cored borehole through the bank margin of the Midway Atoll coral cap provides a record of post-early Miocene eustasy. Subaerial exposure horizons are identified by light carbon isotope signatures and, in some instances, by lithologic criteria. Sea-level highstands are recorded by aggradational units of reef sediment that are bounded by these subaerial horizons. Sea-level lowstands are constrained to fall no farther than a meteoric-marine diagenetic boundary observed in the core. This diagenetic boundary is defined by an offset in both oxygen and carbon isotope data, light isotopic composition being indicative of intermittent meteoric diagenesis. Application of this analytic approach may provide amplitude constraints on eustasy elsewhere in the geologic record. Portions of the bank margin core are partially to completely dolomitized. Dolomites are isotopically enriched relative to stratigraphically adjacent calcite.

Major, R. P.

1984-01-01

205

Identification of flow regimes for steam-water two phase flow using differential pressure fluctuations  

International Nuclear Information System (INIS)

[en] Based on wavelet analysis, a novel method of steam-liquid two phase flow regimes on-line fuzzy identification is presented. The pipeline pressure drop is adopted for measurement signal along the heated test section, its fluctuation characteristic has been proceeded two-stage decompose based on third-stratum Daubechies wavelet, and a criterion of identifying the flow regimes is proposed in the term of root-mean-square deviation of two-stage fine coefficient obtained in the wavelet analysis. The research results show that the method is feasible for the flow regimes identification of typical bubble and slug flow. (authors)

2007-01-01

206

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

Science.gov (United States)

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

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

2008-07-15

207

Determination of the level density of 29Si from Ericson fluctuations  

Science.gov (United States)

Neutron total cross-section measurements for 28Si have been made with the white neutron source at Los Alamos Meson Physics Facility for neutron energies between 4 and 600 MeV. Very good resolution (~=0.2 ns/m) was obtained. The detailed structure at low energies is found to be different than obtained in previous measurements, although at energies 7Ericson analysis is performed to yield values for the level density of 29Si between 13 and 22 MeV.

Mishra, V.; Boukharouba, N.; Grimes, S. M.; Doctor, K.; Pedroni, R. S.; Haight, R. C.

1991-12-01

208

Elimination of two level fluctuators in superconducting quantum bits by an epitaxial tunnel barrier  

International Nuclear Information System (INIS)

Quantum computing based on Josephson junction technology is considered promising due to its scalable architecture. However, decoherence is a major obstacle. Here, we report evidence for improved Josephson quantum bits (qubits) using a single-crystal Al2O3 tunnel barrier. We have found an ?80% reduction in the density of the spectral splittings that indicate the existence of two-level fluctators (TLFs) in amorphous tunnel barriers. The residual ?20% TLFs can be attributed to interfacial effects that may be further reduced by different electrode materials. These results show that decoherence sources in the tunnel barrier of Josephson qubits can be identified and eliminated.

2006-09-01

209

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

Science.gov (United States)

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

John, Sajeev; Quang, Tran

1997-03-01

210

Determination of the level density of sup 29 Si from Ericson fluctuations  

Energy Technology Data Exchange (ETDEWEB)

Neutron total cross-section measurements for {sup 28}Si have been made with the white neutron source at Los Alamos Meson Physics Facility for neutron energies between 4 and 600 MeV. Very good resolution ({approx}0.2 ns/m) was obtained. The detailed structure at low energies is found to be different than obtained in previous measurements, although at energies 7{lt}{ital E}{sub {ital n}}{lt}15 MeV the agreement is quite good. The cross section becomes quite smooth above 15 MeV. An Ericson analysis is performed to yield values for the level density of {sup 29}Si between 13 and 22 MeV.

Mishra, V.; Boukharouba, N.; Grimes, S.M.; Doctor, K.; Pedroni, R.S. (Ohio University, Athens, Ohio 45701 (United States)); Haight, R.C. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

1991-12-01

211

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

212

Late quarternary glacioeustatic sea-level fluctuations: What are the sedimentologic processes and stratigraphic responses on continental margins  

Energy Technology Data Exchange (ETDEWEB)

Published stable isotope data from deep-sea sediments clearly show that the earth's climatic cycles have oscillated through at least 10 major glacial and interglacial episodes during the last million years. These high-frequency, orbitally-forced events should have resulted in major glacioeustatic sea-level fluctuations on the continental margins with dramatic sedimentologic effects and stratigraphic responses. However, such high-frequency events have proven difficult to resolve. Are they too short-lived to be recorded, to complex to decipher, or have traditional stratigraphic tools not been adequate to recognize them in continental margin sequences A detailed, multidisciplinary study of various continental margins is necessary to test the sensitivity of sedimentologic systems and response in stratigraphic records. This study must utilize (1) high-resolution event stratigraphy to define the depositional and erosional sediment sequences; (2) sediment analyses to delineate depositional environments and characterize lithofacies of specific system tracts; and (3) biostratigraphic and geochronologic analyses to place the depositional sequences in time. Integration of these data sets will (4) determine the resolving power of sequence stratigraphy; (5) develop working stratal models for recognizing short-pulsed, glacioeustatic sea-level events within the stratigraphic record; and (6) define a chronostratigraphy of changing paleoclimatic and paleoceanographic events operating on continental margin systems during the late Quaternary.

Riggs, S.R. (East Carolina Univ., Greenville, NC (United States)); Snyder, S.W. (North Carolina Univ., Raleigh (United States)); Hine, A.C. (Univ. of South Florida, St. Petersburg (United States))

1990-01-09

213

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(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

2004-01-01

214

Fluctuations and Relaxation Dynamics of Liquid Water Revealed by Linear and Nonlinear Spectroscopy  

Science.gov (United States)

Many efforts have been devoted to elucidating the intra- and intermolecular dynamics of liquid water because of their important roles in many fields of science and engineering. Nonlinear spectroscopy is a powerful tool to investigate the dynamics. Because nonlinear response functions are described by more than one time variable, it is possible to analyze static and dynamic mode couplings. Here we review the intra- and intermolecular dynamics of liquid water revealed by recent linear and nonlinear spectroscopic experiments and computer simulations. In particular, we discuss the population relaxation, anisotropy decay, and spectral diffusion of the intra- and intermolecular motions of water and their temperature dependence, which play important roles in ultrafast dynamics and relaxations in water.

Yagasaki, Takuma; Saito, Shinji

2013-04-01

215

Fluctuations and relaxation dynamics of liquid water revealed by linear and nonlinear spectroscopy.  

UK PubMed Central (United Kingdom)

Many efforts have been devoted to elucidating the intra- and intermolecular dynamics of liquid water because of their important roles in many fields of science and engineering. Nonlinear spectroscopy is a powerful tool to investigate the dynamics. Because nonlinear response functions are described by more than one time variable, it is possible to analyze static and dynamic mode couplings. Here we review the intra- and intermolecular dynamics of liquid water revealed by recent linear and nonlinear spectroscopic experiments and computer simulations. In particular, we discuss the population relaxation, anisotropy decay, and spectral diffusion of the intra- and intermolecular motions of water and their temperature dependence, which play important roles in ultrafast dynamics and relaxations in water.

Yagasaki T; Saito S

2013-01-01

216

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

217

Water-level measurement for pressurizer of HFETR test lop  

International Nuclear Information System (INIS)

When a differential pressure water-level gauge is used to measure the water-level in the vessel, large uncertainty can be induced because of the change of media density in the vessel. In order to raise the precision of water-level measurement for pressurizer of High-Flux Engineering Test Reactor (HFETR) Test loop, the auto-compensation of the density has been realized in the measurement of water-level through putting the functions that the density changes with the pressure into the measuring meter. Experiment and operation have confirmed that the system has the properties of the stability, high precision, large range of compensation, etc

2000-01-01

218

Solar effect on water level change of Hulun lake at northeast of China  

Science.gov (United States)

Water level measurements of Hulun lake, from 1961 to 2010, were taken to carry out correlation analysis with solar activity indices. It was found that 11 years smoothed sun spot number has a positive relationship with the water level of the lake. The relation coefficient reached its maximum, 0.75, when water level serial was shifted 8 years forward. According to literature records, the water level time serial was extended back to 1905. For the extended water level serial, a more remarkable solar effect was found with a relation coefficient up to 0.86. Also, other solar activity indices like F10.7, total solar insolation (TSI) and cosmic ray flux show similar correlation with the water level change, indicating that on decadal scale stronger solar activity leads to higher water level. Wavelet analysis shows both the solar activity and the water level change of Hulun lake have an apparent component with period of 80~90 years. Meteorologic data from the catchment indicates solar activity had affected local precipitation that subsequently determining the run off of the two inflow rivers of Hulun lake, eventually lead to fluctuation of water level. Meteorologic data also show that the regional precipitation in summer and that in winter changed in a negative relationship pattern. Southern oscillation index (SOI) and northern Atlantic oscillation index were taken to do relation analysis. A resulting plus relation coefficient for SOI and minus relation coefficient for NAOI unveiled the mechanism behind the relationship between solar activity and water level of Hulun lake. The lake, located at brim of domains of both westerly and east Asia monsoon, is very sensitive to multiple climate systems. In winter, westerly is dominant in Hulun lake region. While in summer, east Asia monsoon brings most precipitation to the region. Strong solar activity usually brings southern oscillation index (SOI) into positive phases. Subsequently more intense east Asia monsoon and more summer precipitation can been expected. On the other hand, strong solar activity brings northern Atlantic oscillation index into negative phases, that leads to weaker westerly and less winter precipitation in the region. Since summer precipitation is absolutely dominant within a year, stronger solar activity will lead to more precipitation, higher water level of Hulun lake.

Chen, ZhiQing

2013-04-01

219

Glassy Interfacial Dynamics of Ni Nanoparticles: Part II Discrete Breathers as an Explanation of Two-Level Energy Fluctuations.  

Science.gov (United States)

Recent studies of the dynamics of diverse condensed amorphous materials have indicated significant heterogeneity in the local mobility and a progressive increase in collective particle motion upon cooling that takes the form of string-like particle rearrangements. In a previous paper (Part I), we examined the possibility that fluctuations in potential energy E and particle mobility ? associated with this 'dynamic heterogeneity' might offer information about the scale of collective motion in glassy materials based on molecular dynamics simulations of the glassy interfacial region of Ni nanoparticles (NPs) at elevated temperatures. We found that the noise exponent associated with fluctuations in the Debye-Waller factor, a mobility related quantity, was directly proportional to the scale of collective motion L under a broad range of conditions, but the noise exponent associated with E(t) fluctuations was seemingly unrelated to L. In the present work, we focus on this unanticipated difference between potential energy and mobility fluctuations by examining these quantities at an atomic scale. We find that the string atoms exhibit a jump-like motion between two well-separated bands of energy states and the rate at which these jumps occur seems to be consistent with the phenomenology of the 'slow-beta' relaxation process of glass-forming liquids. Concurrently with these local E(t) jumps, we also find 'quake-like' particle displacements having a power-law distribution in magnitude so that particle displacement fluctuations within the strings are strikingly different from local E(t) fluctuations. An analysis of these E(t) fluctuations suggests that we are dealing with 'discrete breather' excitations in which large energy fluctuations develop in arrays of non-linear oscillators by virtue of large anharmonicity in the interparticle interactions and discreteness effects associated with particle packing. We quantify string collective motions on a fast caging times scale (picoseconds) and explore the significance of these collective motions for understanding the Boson peak of glass-forming materials. PMID:23585770

Zhang, Hao; Douglas, Jack F

2013-01-01

220

Glassy Interfacial Dynamics of Ni Nanoparticles: Part II Discrete Breathers as an Explanation of Two-Level Energy Fluctuations.  

UK PubMed Central (United Kingdom)

Recent studies of the dynamics of diverse condensed amorphous materials have indicated significant heterogeneity in the local mobility and a progressive increase in collective particle motion upon cooling that takes the form of string-like particle rearrangements. In a previous paper (Part I), we examined the possibility that fluctuations in potential energy E and particle mobility ? associated with this 'dynamic heterogeneity' might offer information about the scale of collective motion in glassy materials based on molecular dynamics simulations of the glassy interfacial region of Ni nanoparticles (NPs) at elevated temperatures. We found that the noise exponent associated with fluctuations in the Debye-Waller factor, a mobility related quantity, was directly proportional to the scale of collective motion L under a broad range of conditions, but the noise exponent associated with E(t) fluctuations was seemingly unrelated to L. In the present work, we focus on this unanticipated difference between potential energy and mobility fluctuations by examining these quantities at an atomic scale. We find that the string atoms exhibit a jump-like motion between two well-separated bands of energy states and the rate at which these jumps occur seems to be consistent with the phenomenology of the 'slow-beta' relaxation process of glass-forming liquids. Concurrently with these local E(t) jumps, we also find 'quake-like' particle displacements having a power-law distribution in magnitude so that particle displacement fluctuations within the strings are strikingly different from local E(t) fluctuations. An analysis of these E(t) fluctuations suggests that we are dealing with 'discrete breather' excitations in which large energy fluctuations develop in arrays of non-linear oscillators by virtue of large anharmonicity in the interparticle interactions and discreteness effects associated with particle packing. We quantify string collective motions on a fast caging times scale (picoseconds) and explore the significance of these collective motions for understanding the Boson peak of glass-forming materials.

Zhang H; Douglas JF

2013-01-01

 
 
 
 
221

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

222

Water Level Effects on Growth of Melaleuca Seedlings from Lake Okeechobee (Florida, USA) Littoral Zone.  

UK PubMed Central (United Kingdom)

/ The invasive exotic wetland tree, Melaleuca quinquenervia, is expanding rapidly throughout seasonally wet areas of southern Florida (USA), including the littoral zone of Lake Okeechobee. Natural resource managers are concerned that a lower lake level regulation schedule under consideration for Lake Okeechobee, while potentially beneficial to overall ecosystem health, might increase the rate of Melaleuca expansion. To investigate this possibility, Melaleuca saplings (harvested from the littoral zone) and 7-week-old seedlings (grown from harvested seeds) were subjected to various hydroperiod treatments in replicated mesocosms. Hydroperiod treatments were selected based on a simulation of historical water level variations. Saplings grew taller under longer hydroperiods with fluctuating water levels, including periods of submersion. Time since germination affected the response of seedlings to inundation. Submersed 7-week-old seedlings grew slower and had less biomass than submersed 12-week-old seedlings, yet mortality was low at both ages. Melaleuca's plasticity allows it to adapt to hypoxic, aquatic conditions by means of aquatic heterophylly and adventitious roots. Algae and drought also increased mortality. Based on faster growth of Melaleuca under longer hydroperiods and its adaptability to seasonal flooding, a lower lake regulation schedule may not stimulate its expansion. Therefore, water levels should not be manipulated only to control Melaleuca. Control of Melaleuca should continue using current practices such as manual removal or chemical treatment. KEY WORDS: Melaleuca; Lake Okeechobee; Littoral zone; Water level; Regulation schedule

LOCKHART C; AUSTIN DF; AUMEN NG

1999-05-01

223

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

Energy Technology Data Exchange (ETDEWEB)

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.). 2 refs.

Matal, O.; Klinga, J.; Simo, T. [Energovyzkum Ltd., Brno (Switzerland)

1995-12-31

224

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

UK PubMed Central (United Kingdom)

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.

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

2013-07-01

225

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

UK PubMed Central (United Kingdom)

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

Boccalandro HE; González CV; Wunderlin DA; Silva MF

2011-09-01

226

Anomalous water-level changes and possible relation with earthquakes  

Energy Technology Data Exchange (ETDEWEB)

Since late 1976 abandoned water wells have been monitored along the San Andreas and San Jacinto faults to detect water-level changes which may be premonitory to earthquakes. An M5.5 earthquake occurred 25 February 1980 within the San Jacinto fault zone near Anza. The water level in a continuously recorded well in Borrego Valley 35 km from the epicenter rose 0.5 m and returned to its prior level during a four-hour period beginning 88 hours before the earthquake. The water level in this well had been remarkably steady compared to other wells being monitored. Another well in Borrego Valley showed a much smaller rise and fall in water level at the same time. Because these changes are unique for the long-term records of these wells, they may represent precursors to the earthquake.

Merifield, P.M.; Lamar, D.L.

1981-05-01

227

First record of beachrock on Black Sea coast of Turkey: Implications for Late Holocene sea-level fluctuations  

Science.gov (United States)

We present new data on the diagenetic characteristics, subsurface nature and radiocarbon ages of beachrock from the Thracian Black Sea coast of Turkey, indicative of sea-level changes and climatic conditions favoring lithification of beach sands between 5.4 ka and 3.5 ka cal BP. Micrite coatings and succeeding meniscus cements typify diagenetic history and suggest a two-stage cementation over this timeframe. The early cements are typical of upper intertidal zone when the sea-level was likely similar to that of today. The ensuing intergranular bridges refer to an approximate 2 m decline in sea-level, favoring downward percolation of meteoric waters related to subaerial exposure, marked by a reduction in Mg concentration and dissolution pits on early cement coatings. Formation of beachrock during this bimillennial period could be associated with relatively drier conditions promoting the precipitation of connective cements.

Erginal, Ahmet Evren; Ekinci, Yunus Levent; Demirci, Alper; Bozcu, Mustafa; Ozturk, Muhammed Zeynel; Avcioglu, Mustafa; Oztura, Erdal

2013-08-01

228

Stability of a natural slope under combined effects of reservoir water level drawdown and rainfall infiltration  

Energy Technology Data Exchange (ETDEWEB)

Several large-scale soil slopes were immersed when China's Three-Gorge reservoir was filled. The stability of these slopes during subsequent water level fluctuations is a public concern. For that reason, a series of transient seepage and slope stability analyses were performed to analyze the changes in the groundwater table in a landslide under the combined effects of reservoir water level drawdown and rainfall infiltration. The effects of gravel content in the slope soil on the groundwater regimes and the slope stability were also studied. The pore water pressures from these analyses were used for the stability analyses of the slope. The stability of the slope was found to decrease significantly when the reservoir level was lowered quickly during a rainstorm. This study also revealed that the infiltration rate is larger and the ground water level is higher in soil slopes with less gravel content, because the hydraulic conductivity of a soil with less gravel content is larger than that with higher gravel content when the soils are desaturated. It was concluded that the calculated factor of safety of the soil slope with less gravel content is smaller during rainfall. 21 refs., 1 tab., 8 figs.

Chen, Q. [Sichuan Univ., Chengdu, Sichuan (China). School of Hydraulic and Hydroelectric Engineering; Zhang, L. [Hong Kong Univ. of Science and Technology, Hong Kong (China). Dept. of Civil Engineering

2005-07-01

229

Modelling Water Level Influence on Habitat Choice and Food Availability for Zostera Feeding Brent Geese Branta bernicla in Non-Tidal Areas  

DEFF Research Database (Denmark)

Brent geese Branta bernicla spring fattening around Agero, Denmark, alternate between feeding on saltmarshes and submerged Zostera beds in Limfjorden. It appeared from field observations that these alternations depended on the water level in Limfjorden. A model was developed to assess the impact of water level fluctuations on the habitat use. A second model was developed to estimate the impact of water level on Zostera availability. The first model was successful in demonstrating that fluctuations in water levels had considerable influence on habitat use by the brent geese, i.e. they fed on Zostera at low water levels and on saltmarshes during high water levels, particularly so in early spring, and that the switch between habitats occurred within a narrow water level span of ca 30 cm. The second model demonstrated that the switch between habitats could be explained by lowered availability of Zostera as water levels increased. By combining the output from the two models, differences between years could partly be explained by differences in Zostera availability in the early spring period (21 March - 25 April), whereas a more complicated situation was detected later in spring (26 April - 31 May). The models presented may be considered as tools in investigations of habitat use and carrying capacity of seagrass beds in non-tidal areas, where birds' access to feeding areas regularly may be hindered by high water levels.

Clausen, P.

2000-01-01

230

Synthesis water level control by fuzzy logic  

Directory of Open Access Journals (Sweden)

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

P. Berk; D. Stajnko; P. Vindis; B. Mursec; M. Lakota

2011-01-01

231

Assessment of radon levels in some water resources in Egypt  

International Nuclear Information System (INIS)

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

2003-01-01

232

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

233

Potential Effects of Climate Change on the Water Level, Flora and Macro-fauna of a Large Neotropical Wetland  

Science.gov (United States)

Possible consequences of climate change in one of the world’s largest wetlands (Ibera, Argentina) were analysed using a multi-scale approach. Climate projections coupled to hydrological models were used to analyse variability in wetland water level throughout the current century. Two potential scenarios of greenhouse gas emissions were explored, both resulting in an increase in the inter-annual fluctuations of the water level. In the scenario with higher emissions, projections also showed a long-term negative trend in water-level. To explore the possible response of biota to such water-level changes, species-area relationships of flora and aerial censuses of macro-fauna were analysed during an extraordinary dry period. Plant species richness at the basin scale was found to be highly resistant to hydrological changes, as the large dimension of the wetland acts to buffer against the water-level variations. However, local diversity decreased significantly with low water levels, leading to the loss of ecosystem resilience to additional stressors. The analysis of macro-fauna populations suggested that wetland provides refuge, in low water periods, for the animals with high dispersal ability (aquatic and migratory birds). On the contrary, the abundance of animals with low dispersal ability (mainly herbivorous species) was negatively impacted in low water periods, probably because they are required to search for alternative resources beyond the wetland borders. This period of resource scarcity was also related to increased mortality of large mammals (e.g. marsh deer) around water bodies with high anthropogenic enrichment and cyanobacteria dominance. The synergy between recurrent climatic fluctuations and additional stressors (i.e. biological invasions, eutrophication) presents an important challenge to the conservation of neotropical wetlands in the coming decades.

Ubeda, Barbara; Di Giacomo, Adrian S.; Neiff, Juan Jose; Loiselle, Steven A.; Guadalupe Poi, Alicia S.; Galvez, Jose Angel; Casco, Silvina; Cozar, Andres

2013-01-01

234

Potential effects of climate change on the water level, flora and macro-fauna of a large neotropical wetland.  

Science.gov (United States)

Possible consequences of climate change in one of the world's largest wetlands (Ibera, Argentina) were analysed using a multi-scale approach. Climate projections coupled to hydrological models were used to analyse variability in wetland water level throughout the current century. Two potential scenarios of greenhouse gas emissions were explored, both resulting in an increase in the inter-annual fluctuations of the water level. In the scenario with higher emissions, projections also showed a long-term negative trend in water-level. To explore the possible response of biota to such water-level changes, species-area relationships of flora and aerial censuses of macro-fauna were analysed during an extraordinary dry period. Plant species richness at the basin scale was found to be highly resistant to hydrological changes, as the large dimension of the wetland acts to buffer against the water-level variations. However, local diversity decreased significantly with low water levels, leading to the loss of ecosystem resilience to additional stressors. The analysis of macro-fauna populations suggested that wetland provides refuge, in low water periods, for the animals with high dispersal ability (aquatic and migratory birds). On the contrary, the abundance of animals with low dispersal ability (mainly herbivorous species) was negatively impacted in low water periods, probably because they are required to search for alternative resources beyond the wetland borders. This period of resource scarcity was also related to increased mortality of large mammals (e.g. marsh deer) around water bodies with high anthropogenic enrichment and cyanobacteria dominance. The synergy between recurrent climatic fluctuations and additional stressors (i.e. biological invasions, eutrophication) presents an important challenge to the conservation of neotropical wetlands in the coming decades. PMID:23874446

Úbeda, Bárbara; Di Giacomo, Adrian S; Neiff, Juan José; Loiselle, Steven A; Poi, Alicia S Guadalupe; Gálvez, José Ángel; Casco, Silvina; Cózar, Andrés

2013-07-09

235

Potential effects of climate change on the water level, flora and macro-fauna of a large neotropical wetland.  

UK PubMed Central (United Kingdom)

Possible consequences of climate change in one of the world's largest wetlands (Ibera, Argentina) were analysed using a multi-scale approach. Climate projections coupled to hydrological models were used to analyse variability in wetland water level throughout the current century. Two potential scenarios of greenhouse gas emissions were explored, both resulting in an increase in the inter-annual fluctuations of the water level. In the scenario with higher emissions, projections also showed a long-term negative trend in water-level. To explore the possible response of biota to such water-level changes, species-area relationships of flora and aerial censuses of macro-fauna were analysed during an extraordinary dry period. Plant species richness at the basin scale was found to be highly resistant to hydrological changes, as the large dimension of the wetland acts to buffer against the water-level variations. However, local diversity decreased significantly with low water levels, leading to the loss of ecosystem resilience to additional stressors. The analysis of macro-fauna populations suggested that wetland provides refuge, in low water periods, for the animals with high dispersal ability (aquatic and migratory birds). On the contrary, the abundance of animals with low dispersal ability (mainly herbivorous species) was negatively impacted in low water periods, probably because they are required to search for alternative resources beyond the wetland borders. This period of resource scarcity was also related to increased mortality of large mammals (e.g. marsh deer) around water bodies with high anthropogenic enrichment and cyanobacteria dominance. The synergy between recurrent climatic fluctuations and additional stressors (i.e. biological invasions, eutrophication) presents an important challenge to the conservation of neotropical wetlands in the coming decades.

Úbeda B; Di Giacomo AS; Neiff JJ; Loiselle SA; Poi AS; Gálvez JÁ; Casco S; Cózar A

2013-01-01

236

Reactor water level indicator for BWR type reactor  

International Nuclear Information System (INIS)

[en] The present invention provides a reactor water level indicator suppressing accumulation of incondensible gases and not causing degradation of materials. The degradation of the materials of a condensation vessel of the water level indicator is caused by accumulation of incondensible oxygen and hydrogen generated by radiolysis of reactor water in the condensation vessel. The molar ratio of hydrogen and oxygen in steams generated by radiolysis of reactor water during rated operation is about 2:1. The molar ratio of hydrogen and oxygen recombined by using a catalyst is also 2:1. Accordingly, incondensible oxygen and hydrogen are caused to recombine into water or stream by the function of a catalyst in a channel leading to the condensation vessel. With such procedures, the amount of the incondensible gases accumulated in the condensation vessel can be reduced. As a result, a water level indicator of a BWR type reactor causing no degradation of the materials can be obtained. (I.S.)

1994-08-24

237

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

238

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

UK PubMed Central (United Kingdom)

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.

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

2013-02-01

239

Implications for the water level change triggered moderate (M ? 4.0) earthquakes in Lake Van basin, Eastern Turkey  

Science.gov (United States)

The water level in Lake Van has shown alternating rises and decreases in history, causing economical, environmental and social problems over the littoral area. The water level changes were obtained to be in the order of 100 m between 18000 and 1000 B.C., in the order of 10 m between 1000 B.C. and 500 A.D. and relatively stable and fluctuating in the order of a few metres during the past 1500 years. The most recent change of the water level took place between 1987 and 1996, during which the water level increased episodically about 2 m and its altitude changed from approximately 1648.3 m to about 1650.2 m. All these changes were mainly related to climate changes. In this study, the water level changes in the lake after 1860 are compared with the seismic activity of faults lying close to the basin. Temporal correlations of seismicity with the water level changes are very persuasive and dramatic, indicating hydrogeological triggering of the earthquakes. This study shows that 14 M ? 5.0 earthquakes and increasing number of 4.0 ? M < 5.0 earthquakes accompanied or followed the dramatic (about 1 m or larger) changes of the annual mean of the water level in the lake and that there was a tendency of M ? 4 earthquakes to occur between November and February, during which the lake level is low within a year.

Utkucu, Murat

2006-01-01

240

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1986-06-01

 
 
 
 
241

Water Level Changes on the Central Amazon Floodplain Measured with Interferometric JERS-1 SAR Data  

Science.gov (United States)

The central Amazon floodplain is marked by non-channelized, diffusive flow conditions that prohibit the use of typical in-situ gauging methods for estimating discharge (e.g., rating-curves). In fact, gauging stations are located only on the mainstem and major tributaries, but not in the adjoining floodplains. Logistics and costs prohibit the installation of floodplain gauges, thus predictions of floodplain storage and subsequent discharge evolve from models, such as Muskingum methods, or from remote sensing. Interferometric processing of SIR-C SAR data has previously been used to demonstrate that water levels across the central Amazon floodplain are not horizontal, as assumed in a Muskingum model based approach. Yet, the interferometric SIR-C data exists only for a very brief, 24-hour period, and the method requires a "double-bounce" radar pulse travel path typical of flooded vegetation. Interferometric processing of JERS-1 SAR data over flooded forests of the floodplain provides net changes in water levels during the 44, 88, etc. day orbital repeat cycles. Interferometric coherence during these repeat-cycles is poor, but visible fringe patterns exist, even in unfiltered interferograms. Measured changes in water levels generally agree with channel gauges at Itapeau, Beruri, and Manacapuru, but within-floodplain fluctuations are not planar. Preliminary interpretation of the interferometric data suggests that during early rising water, inundation appears first as a patchwork bordered by small floodplain channels, whereas at mainstem peak stage, floodplain flow appears to sub-parallel the mainstem.

Alsdorf, D.

2003-12-01

242

Carboxyhaemoglobin levels in water-pipe and cigarette smokers  

Scientific Electronic Library Online (English)

Full Text Available 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 sm (more) oking 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.

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

2010-02-01

243

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

Energy Technology Data Exchange (ETDEWEB)

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.

Reiner,S.R.; Laczniak, R.J.; DeMeo, G.A.; Smith, J.LaRue; Elliott, P.E.; Nylund, W.E.; Fridrich, C.J.

2002-01-29

244

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

245

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

Energy Technology Data Exchange (ETDEWEB)

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

Ball, I. Joseph

1984-01-01

246

On the evaluation of environmental condition by the level of fluctuating asymmetry in anuran amphibian of lake frog (Rana ridibunda) as an example ?? ?????? ????????? ?????????? ????? ?? ?????? ????????????? ?????????? ? ?????????? ??????? ?? ??????? ??????? ??????? (Rana ridibunda)  

Directory of Open Access Journals (Sweden)

Full Text Available The possibility of the usage of environmental condition evaluation by the level of fluctuating asymmetry in anuram amphibians is discussed. On the basis of original results and literature cited the conclusion is made that similar studies must be provided with the thought-over choice of studied objects and used characteristics as well as by the objective search of the causes with the account of all the assemblage of ecological factors acting on the development of an organism.??????????? ??????????? ????????????? ?????? ????????? ?????????? ????? ?? ?????? ????????????? ?????????? ? ?????????? ???????????. ?? ????????? ??????????? ??????????? ? ?????????? ???????????? ?????????? ???????? ?????, ??? ???????? ?????? ?????? ?????????????? ??????????? ??????? ???????? ???????????? ? ???????????? ?????????, ? ????? ??????????? ??????? ?????? ? ?????? ???? ???????????? ????????????? ????????, ??????????? ?? ???????? ??????????.

Lada Georgiy Arcadyevich; Lyovin Aleksey Nikolaevich; Artyomova Lyudmila Viktorovna; Rybkina Natalia Serafimovna

2012-01-01

247

Radium-226 levels in Italian drinking waters and foods  

International Nuclear Information System (INIS)

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

1978-04-28

248

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

Scientific Electronic Library Online (English)

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

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

2013-09-01

249

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

Scientific Electronic Library Online (English)

Full Text Available 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 Brasil. A principal feição identificada foi um canal submerso, na plataforma interna, parcialmente preenchido, provavelmente relacionado com o sistema de vales inciso (more) s 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 i (more) n 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.

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

2010-01-01

250

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; Samia F.Lima Furtado; Moab Praxedes Gomes

2010-01-01

251

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

252

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

International Nuclear Information System (INIS)

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

2011-01-01

253

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 running. It is awkward for farmers to walk all the way to their fields at night just to switch the pump motor off. Besides, he may never get to identify the problem. This problem can be solved by using this GSM based system that will automatically make a call to the user mobile phone, when the water Level in the bore well drops threshold below or rises to the threshold level for pumping. The user can also remotely switch on or off the pump motor by sending a SMS from his mobile phone. The system is simple, reliable, portable and affordable. We proposed the work in which, Whenever water level in the tankdrops below the required level the system try to fill the tank by switching on the bore well motor to pump the water into the tank It is must to have enough water in the bore well to avoid the formation of air gap or empty running of bore well motor. High precision water level sensor is used to identify the reference water level to activate and deactivate the motor and system properly by interfacing the sensor devices into the well definedembedded system.

R.Ramani; S.Selvaraju; S.Valarmathy; R.Thangam; B.Rajasekaran

2012-01-01

254

Effect of changes in water level on sediment pore water redox geochemistry at a reservoir shoreline  

International Nuclear Information System (INIS)

Research highlights: ? Initially, reducing conditions existed in pore water of submerged shoreline sediment. ? Exposure of sediment to air by falling water level appears to have oxidized the sediment. ? Re-submergence of sediment led to reducing conditions in pore water after

2010-01-01

255

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.

Bukharitsin Peter Ivanovich; Karasaeva Al’finur Ravil’evna

2010-01-01

256

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

Energy Technology Data Exchange (ETDEWEB)

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

Casey, Daniel

1985-02-01

257

Fluctuation of densities of bacteriophages and Escherichia coli present in natural biofilms and water of a main channel and a small tributary.  

UK PubMed Central (United Kingdom)

Fluctuation of bacteriophage and Escherichia coli densities in naturally developed riverbed biofilms were investigated for a 1-year period. E. coli ranged from 1,500 to 15,500 most probable number (MPN)/100 mL and from 580 to 18,500 MPN/cm(2) in the main channel in the river water and biofilms, respectively. However, the fluctuations were much greater in the tributary, ranging from 0.8 to 100 MPN/100 mL and from 0.3 to 185 MPN/cm(2) in water and biofilms, respectively. The fluctuations of coliphages were also greater in the tributary than in the main channel. FRNA phage serotyping results indicated no significant differences in the source type of the fecal contamination in the main channel and tributary sampling stations. Significant correlations between phage groups in biofilms and water were found at both main channel and tributary. It was assumed that natural biofilms developed in the streambed captured and retained somatic phages in the biofilms for a certain period of time in the main channel site. At the location receiving constant and heavy contamination, the usage of phage indicators may provide additional information on the presence of viruses. In the small tributary it may be possible to estimate the virus concentration by monitoring the E. coli indicator.

Hirotani H; Yu M; Yamada T

2013-01-01

258

Analysis of water level reduction during ATWS/instability events  

International Nuclear Information System (INIS)

Density wave oscillations in a BWR can cause increased average core power and localized flow starvation. The postulated combination of anticipated transient without scram (ATWS) with oscillations can result in reactor transient conditions which have not been analyzed fully and might present safety concerns. Therefore, U.S. BWR utilities are currently considering possible operator actions to minimize the likelihood of large oscillations during an ATWS. This paper investigates the effectiveness of lowering reactor water level to reduce oscillations. Using the one-dimensional transient code, RETRAN-03, it is shown that decreasing water level reduces oscillations under conditions expected during an ATWS. Lowering level has a stabilizing effect because the power decreases as level drops. The dominant effect occurs, however, when the level drops below the feedwater spargers. This allows steam in the reactor to heat the feedwater as it sprays from the sparger. The result is a sharp reduction in core inlet subcooling, which stabilizes the reactor

1991-01-01

259

Monitoring Water Level in Agriculture Using Sensor Networks  

Directory of Open Access Journals (Sweden)

Full Text Available Recent advances in communications technology andwireless sensor networks made new trends to emerge inagriculture sector. One such new trend is Precision Agriculture.In this paper we are giving brief outline of using Wireless SensorNetworks (WSN) in Monitoring water level in the farm area forPrecision Agriculture. This algorithm offers a maximumopportunity of delivery of water level informationpackets/signals to base station as it also computes a threshold aswell as does calculates values based on transmission range. Thisover all computational mechanism helps us to build a robustmechanism for delivery of information to base station thus,reducing the packet loss. Our algorithm which picks up theinformation for water level can be further optimized by usingoptimization algorithms, which lead to smoothening of packetdelivery ratio, thereby increasing the packet delivery ratio bychoosing the right cost path with the help of optimizationtechniques like genetic algorithm, neural networks.

Iqbal Singh; Meenakshi Bansal

2011-01-01

260

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

 
 
 
 
261

Radon Levels in household waters in southern Poland  

International Nuclear Information System (INIS)

Determination of radon concentrations in household waters were performed in 1997 in three regions of south-western Poland which are considered to have an enhanced natural radioactivity level: in the Jelenia Gora and Walbrzych regions (both in South-western Sudety Mountains) and in the Upper Silesia Coal Basin. Water samples were collected from taps, wells and springs and were analysed in a liquid scintillation counter. In the upper Silesia coal Basin all values are below 50 Bq/dm3 with a maximum of 32 Bq/m3 and in the Sudety Mountains the radon concentration in water exceed this level in 68% of houses, reaching a maximum value ca. 1400 Bq/m3 in drilled well water in the Jelenia Gora region. The annual ingestion dose calculated for this value equals to ca. 0.5 mSv for infants, 0.4 mSv for children and 0.3 mSv for adults.The average annual effective whole body doses calculated for tap water samples for a representative population in the investigated regions range from about 0.02 mSv to 0.32 mSv and the maximum value reaches 1.39 mSv. The inhalation doses corresponding to the unit of water-borne radon concentration are about one order higher than in the ingestion ones for tap water supplies. (author)

2002-01-01

262

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.

Sophie C. Leterme; Robin D. Pingree; Morten D. Skogen; Laurent Seuront; Philip C. Reid; Martin J. Attrill

2008-01-01

263

Fluctuations in serum sodium level are associated with an increased risk of death in surgical ICU patients.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Dysnatremia may have an impact on outcomes in critically ill patients, but this has not been widely investigated in surgical ICU patients. We investigated the epidemiology of dysnatremia in a large cohort of surgical ICU patients and evaluated the possible influence of the time of acquisition of dysnatremia and fluctuations in serum sodium concentrations on hospital mortality in these patients. DESIGN: Retrospective analysis. SETTING: Fifty-bed surgical ICU. PATIENTS: All patients admitted to the ICU between January 2004 and January 2009. MEASUREMENTS AND MAIN RESULTS: Hyponatremia was defined as a serum sodium concentration <135 mmol/L and hypernatremia as a serum sodium concentration >145 mmol/L. Of the 10,923 surgical ICU patients included in the study, 1,215 (11.2%) had hyponatremia and 277 (2.5%) had hypernatremia at admission to the ICU. Among patients with normonatremia at admission to the ICU (n = 9431), the prevalence of ICU-acquired dysnatremia was 31.3%. Dysnatremia present at ICU admission (odds ratio 2.53; 95% confidence interval 2.06-3.12; p < .001) and ICU-acquired dysnatremia (odds ratio 2.06; 95% confidence interval 1.71-2.48; p < 0.001) were independently associated with an increased risk of in-hospital death compared to normonatremia. Dysnatremia at ICU admission (odds ratio 1.23; 95% confidence interval 1.01-1.50) was associated with a higher risk of in-hospital death, compared with ICU-acquired dysnatremia. Fluctuation in serum sodium concentration was also independently associated with an increased risk of in-hospital mortality, in patients who remained normonatremic (>6 mmol/L/ICU stay) and in those with dysnatremia (>12 mmol/L/24 hrs or >12 mmol/L/ICU stay). CONCLUSIONS: Dysnatremia was common in surgical ICU patients and was independently associated with an increased risk of in-hospital death in these patients. Dysnatremia at ICU admission was associated with a higher risk of death compared with ICU-acquired dysnatremia. Fluctuations in serum sodium concentrations were independently associated with an increased risk of in-hospital death, even in patients who remained normonatremic during the ICU stay.

Sakr Y; Rother S; Ferreira AM; Ewald C; Dünisch P; Riedemmann N; Reinhart K

2013-01-01

264

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

International Nuclear Information System (INIS)

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

1996-01-01

265

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...

266

Radioactive Levels in Taihu and Water Bodies of Suzhou.  

Science.gov (United States)

The radioactive levels in Taihu and water bodies of Suzhou, southern China, were investigated in 1983. The results of the investigation were compared with that of 1973. In addition, the authors investigated a suspected radioactive pollutant-ash of coal po...

Z. Zhang R. Fu N. Zhu H. Wang Q. Hu

1988-01-01

267

Radioactivity levels in waters and sediments from Van Lake / Turkey  

International Nuclear Information System (INIS)

[en] 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

2006-01-01

268

Intercomparison of low-level tritium in water  

International Nuclear Information System (INIS)

[en] 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)

1989-01-01

269

A new water level gauge for cold region application  

Energy Technology Data Exchange (ETDEWEB)

The traditional gas purging (bubbler) water level gauge has been widely sued because of its simplicity, ruggedness and ability to operate in areas of ice cover. However, its mechanically-based sensing and recording system and the need for density information to compute water level have caused inconveniences in field operations. This paper describes a new design that records and telemeters digital data and allows computation of water density directly from the pressure measurements. Major measurement error sources are also identified and quantified. The performance in water level measurement is comparable to the National Ocean Service`s standard air acoustic tide gauge. Deriving density from pressure measurements obviates the need for use of a separate conductivity/temperature/depth instrument, which can be prone to fouling. The uncertainty in density determination is less than 0.0005 g/cc in laboratory tests; in the field, it varies from 0.0015 g/cc under low wave conditions to 0.003 g/cc for high wave conditions. The instrument has been successfully deployed at several cold region sites including the Arctic and Antarctic regions.

Shih, H.H.; Moss, M.K.; Dixon, J.C. [National Ocean Service, Silver Spring, MD (United States)

1995-12-31

270

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

271

Early diagenesis of redox-sensitive trace metals in the Peru upwelling area - response to ENSO-related oxygen fluctuations in the water column  

Science.gov (United States)

Pore water and solid phase data for redox-sensitive metals (Mn, Fe, V, Mo and U) were collected on a transect across the Peru upwelling area (11°S) at water depths between 78 and 2025 m and bottom water oxygen concentrations ranging from ˜0 to 93 ?M. By comparing authigenic mass accumulation rates and diffusive benthic fluxes, we evaluate the respective mechanisms of trace metal accumulation, retention and remobilization across the oxygen minimum zone (OMZ) and with respect to oxygen fluctuations in the water column related to the El Niño Southern Oscillation (ENSO). Sediments within the permanent OMZ are characterized by diffusive uptake and authigenic fixation of U, V and Mo as well as diffusive loss of Mn and Fe across the benthic boundary. Some of the dissolved Mn and Fe in the water column re-precipitate at the oxycline and shuttle particle-reactive trace metals to the sediment surface at the lower and upper boundary of the OMZ. At the lower boundary, pore waters are not sufficiently sulfidic as to enable an efficient authigenic V and Mo fixation. As a consequence, sediments below the OMZ are preferentially enriched in U which is delivered via both in situ precipitation and lateral supply of U-rich phosphorites from further upslope. Trace metal cycling on the Peruvian shelf is strongly affected by ENSO-related oxygen fluctuations in bottom water. During periods of shelf oxygenation, surface sediments receive particulate V and Mo with metal (oxyhydr)oxides that derive from both terrigenous sources and precipitation at the retreating oxycline. After the recurrence of anoxic conditions, metal (oxyhydr)oxides are reductively dissolved and the hereby liberated V and Mo are authigenically removed. This alternation between supply of particle-reactive trace metals during oxic periods and fixation during anoxic periods leads to a preferential accumulation of V and Mo compared to U on the Peruvian shelf. The decoupling of V, Mo and U accumulation is further accentuated by the varying susceptibility to re-oxidation of the different authigenic metal phases. While authigenic U and V are readily re-oxidized and recycled during periods of shelf oxygenation, the sequestration of Mo by authigenic pyrite is favored by the transient occurrence of oxidizing conditions. Our findings reveal that redox-sensitive trace metals respond in specific manner to short-term oxygen fluctuations in the water column. The relative enrichment patterns identified might be useful for the reconstruction of past OMZ extension and large-scale redox oscillations in the geological record.

Scholz, Florian; Hensen, Christian; Noffke, Anna; Rohde, Anne; Liebetrau, Volker; Wallmann, Klaus

2011-11-01

272

Predicting the residual aluminum level in water treatment process  

Directory of Open Access Journals (Sweden)

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

J. Tomperi; M. Pelo; K. Leiviskä

2013-01-01

273

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; M. Pelo; K. Leiviskä

2012-01-01

274

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

Directory of Open Access Journals (Sweden)

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

A. Armstrong; S. Rose

1999-01-01

275

Study of TRAb, TGA and TMA level fluctuation in patients with Graves' disease before and after 131I therapy  

International Nuclear Information System (INIS)

[en] To determine the serum levels of TRAb, TGA and TMA in patients with Graves' disease before and after 131I therapy, serum levels of TRAb, TGA and TMA were measured by RIA in 132 patients before therapy and after therapy 3, 6,12,18 months respectively. The levels of TRAb, TGA and TMA in the patients were significantly higher than those in the controls. After treatment, TRAb increased (P

2003-01-01

276

Investigation of natural radioactivity levels in water around Kadugli, Sudan  

International Nuclear Information System (INIS)

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

2008-01-01

277

Analysis of water level reduction during ATWS/instability events  

International Nuclear Information System (INIS)

Density wave oscillations in a BWR can cause increased average core power and localized flow starvation. The postulated combination of anticipated transient without scram (ATWS) with oscillations can result in reactor transient conditions which have not been analyzed fully and might present safety concerns. Therefore, U.S. BWR utilities are currently considering possible operator actions to minimize the likelihood of large oscillations during an ATWS. This paper investigates the effectiveness of lowering reactor water level to reduce oscillations. Using the one-dimensional transient code, RETRAN-03, it is shown that decreasing water level reduces oscillations under conditions expected during an ATWS. Lowering level has a stabilizing effect because the power decreases as level drops. The dominant effect occurs, however, when the level drops below the feedwater spargers. This allows steam in the reactor to heat the feedwater as it sprays from the sparger. The result is a sharp reduction in core inlet subcooling, which stabilizes the reactor. In conclusion: During an ATWS event in which unstable system behavior is possible, the amount of core inlet subcooling plays a significant role in determining whether oscillations occur. For the system configuration investigated it was found that minimizing inlet subcooling has a pronounced stabilizing effect. A reduction of the vessel fluid level, in and of itself, has a relatively modest capacity to suppress oscillations. However, if the level reduction also induces a decrease in core inlet subcooling, then oscillation suppression can be dramatic. This reduction of subcooling is most pronounced when the level falls below the feedwater sparger and feedwater is allowed to mix with steam. For the system modeled herein, cycling of safety valves does not have a significant effect on the amplitude of oscillations. (authors)

1990-01-01

278

Sulfur Isotope Systematics and the Link Between Fluctuating Sulfate Levels and P Recycling in a Low Sulfate, Permanently Anoxic Lake (Lake McCarrons, MN): Implications for the Precambrian Rise of Oxygen  

Science.gov (United States)

Seawater sulfate concentrations have been used to track the rise of oxygen in the Precambrian ocean-atmosphere system because the primary mode of sulfate delivery to the ocean is the oxidative weathering of sulfides on land. Ancient seawater sulfate concentrations have been inferred from the extent of sulfur (S) isotope fractionation incurred during bacterial sulfate reduction (BSR) where organisms preferentially utilize 32S (over 34S) in the process of reducing of sulfate to sulfide. Within this context, increased variability in ?34Spyrite values in Proterozoic (~2.3 Ga) sediments—along with a corresponding increase in the isotopic difference between sulfate and pyrite (?34S)—has been attributed to an increase in seawater sulfate concentrations (from 1 mM) and inferentially Earth-surface oxygen levels. However, most S isotope studies have been calibrated using modern marine sediments that contain sulfate-reducing bacteria that are adapted to the high concentration of sulfate in the modern ocean (~28mM). In order to better understand S isotope systematics within a low sulfate system and to improve our interpretive construct for S isotope results generated from ancient strata, we explore the magnitude of S isotope fractionations associated with microbial activity in the water column and sediments of a low sulfate (<300 µM), permanently anoxic lake in Minnesota (Lake McCarrons). Furthermore, we explore the link between fluctuating sulfate levels and phosphorus (P) recycling in low sulfate systems by conducting lab incubation experiments under low and varying sulfate concentrations using sediment collected from Lake McCarrons. The results indicate: (1) surface water sulfate levels are ~275 µM and fall to ~130 µM at the sediment-water interface; (2) the S isotope difference between surface water sulfate and bottom water sulfide is ~5‰ (?34S) while in situ S isotope fractionations associated with BSR at the sediment-water interface approach 35‰; (3) sulfate reduction rates in the upper 3 cm of organic carbon rich sediment are ~0.1 µM cm-3 d-1, an order of magnitude lower than those recorded under higher (modern marine) sulfate concentrations; and (4) sulfate concentrations influence the efficiency of P recycling (as determined via bag incubation experiments). Here, we suggest that an increase in sulfate levels at ~2.3 Ga, as indicated by larger ?34S values recorded in strata of this age, facilitated higher rates of BSR, enhanced P recycling and thus higher primary production within marine surface waters and contributed to the magnitude of the “Great Oxidation Event.”

Gomes, M. L.; Hurtgen, M. T.

2009-12-01

279

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

Directory of Open Access Journals (Sweden)

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

Yusuke Yokoyama; Tezer M. Esat

2011-01-01

280

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

 
 
 
 
281

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.

2000-01-01

282

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

2000-01-01

283

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

284

Increased intestinal permeability as a cause of fluctuating postprandial blood glucose levels in Type 1 diabetic patients.  

UK PubMed Central (United Kingdom)

BACKGROUND: In diabetic patients, postprandial glucose levels, which have a major impact on metabolic control, are determined by the rate of nutrient delivery into the intestine, absorption of nutrients from the small intestine, and the metabolism of the absorbed nutrients by the liver. The present study addresses whether Type 1 diabetic patients have increased intestinal permeability and intestinal permeability predicts postprandial glucose variability. MATERIAL AND METHODS: Thirty Type 1 diabetic patients together with 15 sex- and age-matched healthy controls were enrolled in the study. After an overnight fasting all patients and controls received 100 micro Ci 51Cr of EDTA as a radioactive tracer and the percentage of the isotope excreted in a 24-h urinary specimen was the permeability measure. Instant blood glucose was measured just before the test, and the patients performed and recorded self-monitoring of fasting and 2nd-hour postprandial blood glucose levels during the following week. RESULTS: We found that intestinal permeability is increased in Type 1 diabetic patients compared with age- and sex-matched healthy controls. Increased intestinal permeability is related at least in part to the instant blood glucose level and the presence of diabetic autonomic neuropathy. CONCLUSION: Increased intestinal permeability leads to higher variation in postprandial blood glucose levels, thereby worsening metabolic control.

Damci T; Nuhoglu I; Devranoglu G; Osar Z; Demir M; Ilkova H

2003-05-01

285

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

286

Considering rating curve uncertainty in water level predictions  

Directory of Open Access Journals (Sweden)

Full Text Available Streamflow cannot be measured directly and is typically derived with a rating curve model. Unfortunately, this causes uncertainties in the streamflow data and also influences the calibration of rainfall-runoff models if they are conditioned on such data. However, it is currently unknown to what extent these uncertainties propagate to rainfall-runoff predictions. This study therefore presents a quantitative approach to rigorously consider the impact of the rating curve on the prediction uncertainty of water levels. The uncertainty analysis is performed within a formal Bayesian framework and the contributions of rating curve versus rainfall-runoff model parameters to the total predictive uncertainty are addressed. A major benefit of the approach is its independence from the applied rainfall-runoff model and rating curve. In addition, it only requires already existing hydrometric data. The approach was successfully tested on a small urbanized basin in Poland, where a dedicated monitoring campaign was performed in 2011. The results of our case study indicate that the uncertainty in calibration data derived by the rating curve method may be of the same relevance as rainfall-runoff model parameters themselves. A conceptual limitation of the approach presented is that it is limited to water level predictions. Nevertheless, regarding flood level predictions, the Bayesian framework seems very promising because it (i) enables the modeler to incorporate informal knowledge from easily accessible information and (ii) better assesses the individual error contributions. Especially the latter is important to improve the predictive capability of hydrological models.

A. E. Sikorska; A. Scheidegger; K. Banasik; J. Rieckermann

2013-01-01

287

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

Directory of Open Access Journals (Sweden)

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

Khaled Halbaoui; Touati Sai; Djamel Boukhetala; Feres Boudjema

2012-01-01

288

Glacial-eustatic sea-level fluctuation curve for Carboniferous-Permian boundary strata based on outcrops in the North American Midcontinent and North-Central Texas  

Energy Technology Data Exchange (ETDEWEB)

Based on lithologic and faunal analysis of uppermost Carboniferous through Lower Permian strata (Wabaunsee through lower Chase groups) exposed from southeastern Nebraska through north-central Oklahoma, a preliminary glacial-eustatic sea-level fluctuation curve is presented herein. In addition to the sea-level curve presented for the Midcontinent region, one for coeval outcropping strata (middle and upper Cisco Group) of the Eastern Shelf of the Midland Basin is also presented based on similar criteria. This sea-level curve is derived from new field studies as well as a refinement of earlier curves presented by Harrison (1973), and Boardman and Malinky (1985). The conclusion on the nature of the Carboniferous-Permian boundary strata cyclothems in the Midcontinent is mirrored by the results of that from North-Central Texas. Each of the primary biostratigraphically-based picks for the Carboniferous-Permian boundary coincide with either intermediate of major cycles in both study areas. Utilization of a glacial-eustatic maximum transgressive event for the Carboniferous-Permian boundary should result in a more correlatable level for intercontinental correlation.

Boardman, D.R. (Oklahoma State Univ., Stillwater, OK (United States). School of Geology)

1993-02-01

289

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; Abdolazim Behfar; Zahra Nazari; Mohammad Hassan Rabiee; Gholamreza Raeesi; Mohammad Reza Oveisi; Nafiseh Sadeghi

2013-01-01

290

Formal specification and animation of a water level monitoring system  

International Nuclear Information System (INIS)

This report describes the Vienna Development Method (VDM), which is a formal method for software specification and development. VDM evolved out of attempts to use mathematics in programming language specifications in order to avoid ambiguities in specifications written in natural language. This report also describes the use of VDM for a real-time application, where it is used to formally specify the requirements of a water level monitoring system. The procedures and techniques used to produce an executable form (animation) of the specification are covered. (Author).

1993-01-01

291

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

2006-01-01

292

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.

Shen Kang-Ning; Jamandre Brian; Hsu Chih-Chieh; Tzeng Wann-Nian; Durand Jean-Dominique

2011-01-01

293

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

UK PubMed Central (United Kingdom)

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.

Shen KN; Jamandre BW; Hsu CC; Tzeng WN; Durand JD

2011-01-01

294

Comparison of 1972 and 1996 Water Levels in the Goleta Central Ground-Water Subbasin, Santa Barbara County, California.  

Science.gov (United States)

Ground-water levels for 1996 were compared with 1972 water levels to determine if a 'drought buffer' currently exists. To make this determination, a network of 15 well sites was selected, water levels were measured monthly from April through December 1996...

C. A. Kaehler D. A. Pratt K. S. Paybins

1997-01-01

295

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

296

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

297

Ion Chromatographic Determination of low level Perchlorate in Natural Waters  

International Nuclear Information System (INIS)

Perchlorate (ClO4-) is a persistent contaminant of drinking-, surface-, and ground-water, and of soils. Possible contributions of ClO4- contamination are the military, the space program, and supporting industries and fertilizers. Perchlorate has long been known to have a negative effect on the thyroid gland. It has been added to the United States Environmental Protection Agency's (EPA) Contaminant candidate List (CCL) in 1998, so that ClO4 can be regulated at a concentration safe to humans. This paper describes the determination of trace level ClO4- in various matrices utilizing ion chromatographic method. The method utilizes a Dionex IonPac AS11 column with suppressed conductivity detection, 1500ul sample loop, and a 100 mN NaOH eluent at a flow rate of 1.0ml/min. These parameters allow a method detection limit (MDL) of 0.277ug/1 and a short retention time of 8 minutes. A quality control, proficiency testing samples from the EPA and a number of environmental samples from New York State (ground water) and California (ground and surface waters) were analyzed by this technique. Concentrations measured were in the range of 1.9-217 ug/1. No evidence of ClO4- was found in various commonly used fertilizers. (author)

2005-01-01

298

Investigation of natural radioactivity levels in water around Kadugli, Sudan  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-11-15

299

Evaluation of boiling water reactor water-level sensing line break and single failure: Generic Issue 101 boiling water reactor level redundancy - technical findings  

International Nuclear Information System (INIS)

[en] This report presents an evaluation of the potential safety concerns identified in Generic Issue 101, related to Boiling Water Reactor (BWR) level sensing line breaks. For this review, failure combinations and transients were evaluated to assure that existing BWR plants could be safely shut down under postulated conditions of a break or leak in the instrument line of the reactor vessel level instrumentation plus an independent single failure in any protection system. The review evaluated all the designs currently employed in boiling water reactor plants. Part I of this report describes the methodology used to evaluate the various designs and provides technical findings. Part II presents the value/impact analysis performed to evaluate the various alternatives that were considered to improve plant response to a postulated water-level sensing line break and single failure

1989-01-01

300

Fluctuation analysis  

International Nuclear Information System (INIS)

[en] This paper briefly reviews sources of noise in Josephson junctions, and the limits they impose on the sensitivity of dc and rf SQUIDS. The results are strictly valid only for a resistively shunted junction (RSJ) with zero capacitance, but should be applicable to point contact junctions and microbridges in so far as these devices can be approximated by the RSJ model. Fluctuations arising from Nyquist noise in the resistive shunt of a single junction are discussed in the limit eI/sub o/R/k/sub B/T

1980-05-09

 
 
 
 
301

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.; Trojanowski J.

2013-01-01

302

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

International Nuclear Information System (INIS)

This paper presents a preliminary study on lake-level fluctuations since the Last Glaciation in Selin Co (lake), Central Tibet, by dating four groups of beach ridges using optically stimulated luminescence (OSL). The highest/oldest beach ridge group (>100 m higher than the current lake level) is dated back to 67.9 ± 2.4 ka BP, corresponding to the early stage of the Last Glaciation (marine isotope stage (MIS) 4). This date further supports that no plateau-scale ice sheet covered the Tibetan Plateau during the Last Glaciation. The other three groups produce OSL ages of 30.4 ± 2.9 to 18.6 ± 1.7, 12.5 ± 1.6 to 9.2 ± 0.5, and 6.9 ± 0.2 ka BP respectively, most likely corresponding to cold or wet climate periods of the late stage of the Last Glaciation (MIS 2), deglaciation, and Holocene Hypsithermal. On the plateau scale, these four beach ridge groups are almost synchronous with advances or standstills of Himalayan glaciers, indicating similar climate controls across the central and southern Tibetan Plateau, and being consistent with the conclusion, obtained from nearby ice core records, that this area is affected by the South Asia monsoon. Furthermore, beach ridges are also synchronous with fluvial terraces in the northern Tibetan Plateau, implying common driving forces during their formation. Therefore, some terraces may be formed as a result of climate events rather than being of tectonic origin.

2009-01-01

303

Emergency action levels for light water reactors. Draft report  

International Nuclear Information System (INIS)

[en] 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

304

Radioactive levels in Taihu and water bodies of Suzhou  

International Nuclear Information System (INIS)

The radioactive levels in Taihu and water bidies of Suzhou, southern China, were investigated in 1983. The results of the investigation were compared with that of 1973. In addition, the authors investigated a suspectable radioactive pollutant-ash of coal powder from Wongting coal-fired power plant and its affect on the water in Taihu and Suzhou section of the Grand Canal. These results show: the average radioactive levels in Taihu are 41.4 mBq/L for total ?, 91.9 mBq/L for total ?, 3.4 x 10-7 g/L for uranium, 3.5 x 10-7 g/L for thorium; in Suzhou section of the Grand Canal 37.6 mBq/L for total ?, 101.9 mBq/L for total ?, 3.6 x 10-7 g/L for uranium, 4.9 x 10-7 g/L for thorium; in shallow well of Suzhou 61.4 mBq/L for total ?, 857.7 mBq/L for total ?, 1.6 x 10-7 g/L for uranium, 3.9 x 10-7 g/L for thorium. The radioactive levels in dry season are higher than that in rainy season, and each of them is lower than that in 1973. The average radioactive levels in Taihu and in Suzhou section of the Grand Canal caused by ash of coal powder from Wongting coal-fired power plant are: 87.3 and 140.6 mBq/L for total ? respectively; 146.3 and 162.8 mBq/L for total ?; 162.0 and 130.2 mBq/L for 40K; 6.7 x 10-7 and 5.3 x 10-7 g/L for uranium and 4.1 x 10-7 and 4.6 x 10-7 g/L for thorium

1988-01-01

305

Assessment of RELAP5/MOD1 code for the mixture water level tracking capability during blowdown  

International Nuclear Information System (INIS)

[en] The height of water level is one of the most important indicating parameters of Nuclear Power System either in normal operating or accidental conditions. It indicates not only the total amount of water inventory in system but also the effective cooling ability or status of the coolant. Generally, there are two kinds of water levels, namely, the collapsed water level and the mixture water level. After the void below the mixture level is removed, the mixture level turns out to be the collapsed water level. As far as the heat transfer is concerned, the mixture level is the one important and required to be precisely predicted. In this paper, analyses for GE Small Vessel Level Swell Tests and M.I.T. Steam Generator Blowdown Experiments are performed to verify the ability of RELAP5/MOD1 code in mixture water level tracking

1987-01-01

306

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; Nidhi Chandra; Shivraj Dagadi

2013-01-01

307

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

308

Flutuação populacional e intensidade de infestação da broca-dos-frutos em cupuaçu Population fluctuation and infestation levels of the cupuaçu fruit borer  

Directory of Open Access Journals (Sweden)

Full Text Available Dentre as pragas do cupuaçueiro Theobroma grandiflorum (Wild. ex Spreng.) Schum., a broca-dos-frutos, Conotrachelus humeropictus Fiedler (Coleoptera: Curculionidae), é a mais importante, devido aos danos causados e por estar disseminada em alguns Estados da região Norte do Brasil. Os objetivos deste trabalho foram avaliar a flutuação populacional de adultos de C. humeropictus, determinar a intensidade de infestação e caracterizar o ataque de larvas desta praga em frutos de cupuaçueiros, em sistemas agroflorestais no Estado de Rondônia. Para obter a flutuação populacional de adultos da broca, foram amostradas semanalmente, durante o período de março/98 a julho/00, 20 plantas de cupuaçu, pelo método do sacolejo, em duas áreas de agrossilvicultores. A avaliação da população de larvas foi realizada durante duas safras, onde foram coletados e abertos frutos atacados pela broca. A determinação da infestação da praga foi obtida através da porcentagem de frutos broqueados. Adultos de C. humeropictus ocorrem durante todo ano nas plantas de cupuaçu, na área estudada, mas predominam na floração, início da frutificação e durante o período de safra. Tanto os frutos verdes como os maduros são atacados, sendo que larvas de idades diferentes podem ocorrem em um mesmo fruto. Perdas superiores a 50% na produção de frutos, devido ao ataque da broca, ressaltam a importância desta praga na região.The most important pest of the cupuaçu crop is the fruit borer, Conotrachelus humeropictus Fiedler (Coleoptera: Curculionidae), wich severely damages fruits and is disseminated all over North Brazil. The objectives of this study were evaluating the population fluctuations of C. humeropictus adults, infestation levels and to characterize the pest larval attack in cupuaçu fruits of agroforestry systems of the Rondonia State, Brazil. Population fluctuations from C. humeropictus adults were evaluated weekly from March/98 to July/00 in twenty cupuaçu plants, by shaking the tree branches, of two producer areas. During two harvest periods, fruits attacked by the borer were collected and examined for evaluation of larvae population. Pest infestation was determined by the percentage of damaged fruits. C. humeropictus adults occur year around on cupuaçu plants, but predominate at the stages of flowering, fruit formation and during the harvest period. It was observed that mature and non-mature fruits are attacked by the pest; larvae of different ages can occur in a same fruit; the insect may cause losses greater than 50% of fruit yield.

Marcílio José Thomazini

2002-01-01

309

Flutuação populacional e intensidade de infestação da broca-dos-frutos em cupuaçu/ Population fluctuation and infestation levels of the cupuaçu fruit borer  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Dentre as pragas do cupuaçueiro Theobroma grandiflorum (Wild. ex Spreng.) Schum., a broca-dos-frutos, Conotrachelus humeropictus Fiedler (Coleoptera: Curculionidae), é a mais importante, devido aos danos causados e por estar disseminada em alguns Estados da região Norte do Brasil. Os objetivos deste trabalho foram avaliar a flutuação populacional de adultos de C. humeropictus, determinar a intensidade de infestação e caracterizar o ataque de larvas desta praga em f (more) rutos de cupuaçueiros, em sistemas agroflorestais no Estado de Rondônia. Para obter a flutuação populacional de adultos da broca, foram amostradas semanalmente, durante o período de março/98 a julho/00, 20 plantas de cupuaçu, pelo método do sacolejo, em duas áreas de agrossilvicultores. A avaliação da população de larvas foi realizada durante duas safras, onde foram coletados e abertos frutos atacados pela broca. A determinação da infestação da praga foi obtida através da porcentagem de frutos broqueados. Adultos de C. humeropictus ocorrem durante todo ano nas plantas de cupuaçu, na área estudada, mas predominam na floração, início da frutificação e durante o período de safra. Tanto os frutos verdes como os maduros são atacados, sendo que larvas de idades diferentes podem ocorrem em um mesmo fruto. Perdas superiores a 50% na produção de frutos, devido ao ataque da broca, ressaltam a importância desta praga na região. Abstract in english The most important pest of the cupuaçu crop is the fruit borer, Conotrachelus humeropictus Fiedler (Coleoptera: Curculionidae), wich severely damages fruits and is disseminated all over North Brazil. The objectives of this study were evaluating the population fluctuations of C. humeropictus adults, infestation levels and to characterize the pest larval attack in cupuaçu fruits of agroforestry systems of the Rondonia State, Brazil. Population fluctuations from C. humerop (more) ictus adults were evaluated weekly from March/98 to July/00 in twenty cupuaçu plants, by shaking the tree branches, of two producer areas. During two harvest periods, fruits attacked by the borer were collected and examined for evaluation of larvae population. Pest infestation was determined by the percentage of damaged fruits. C. humeropictus adults occur year around on cupuaçu plants, but predominate at the stages of flowering, fruit formation and during the harvest period. It was observed that mature and non-mature fruits are attacked by the pest; larvae of different ages can occur in a same fruit; the insect may cause losses greater than 50% of fruit yield.

Thomazini, Marcílio José

2002-09-01

310

An Extension of the Fluctuation Theorem  

CERN Document Server

Heat fluctuations are studied in a dissipative system with both mechanical and stochastic components for a simple model: a Brownian particle dragged through water by a moving potential. An extended stationary state fluctuation theorem is derived. For infinite time, this reduces to the conventional fluctuation theorem only for small fluctuations; for large fluctuations, it gives a much larger ratio of the probabilities of the particle to absorb rather than supply heat. This persists for finite times and should be observable in experiments similar to a recent one of Wang et al.

Van Zon, R

2003-01-01

311

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

312

Fluctuations analysis  

International Nuclear Information System (INIS)

[en] This paper briefly reviews sources of noise in Josephson junctions, and the limits they impose on the sensitivity of dc and rf SQUIDS. The results are strictly valid only for a resistively shunted junction (RSJ) with zero capacitance, but should be applicable to point contact junctions and microbridges in so far as these devices can be approximated by the RSJ model. We first discuss fluctuations arising from Nyquist noise in the resistive shunt of a single junction in the limit eI0R/ksub(B)T 0R/ksub(B)T >= 1 in which quantum effects become important. The Nyquist limit theory is used to calculate the noise in a dc SQUID, and the results are compared with a number of practical devices. The quantum limit is briefly considered. Results for the predicted sensitivity of rf SQUIDS are presented, and also compared with a number of practical devices. Finally, the importance of l/f noise (f is the frequency) in limiting the low frequency performance of SQUIDS is discussed. (orig.)

1980-05-09

313

Fluctuation analysis  

Energy Technology Data Exchange (ETDEWEB)

This paper briefly reviews sources of noise in Josephson junctions, and the limits they impose on the sensitivity of dc and rf SQUIDS. The results are strictly valid only for a resistively shunted junction (RSJ) with zero capacitance, but should be applicable to point contact junctions and microbridges in so far as these devices can be approximated by the RSJ model. Fluctuations arising from Nyquist noise in the resistive shunt of a single junction are discussed in the limit eI/sub o/R/k/sub B/T << 1 in which a classical treatment is appropriate, and then extend the treatment to the limit eI/sub o/R/k/sub B/T greater than or equal to 1 in which quantum effects become important. The Nyquist limit theory is used to calculate the noise in a dc SQUID, and the results are compared with a number of practical devices. The quantum limit is briefly considered. Results for the predicted sensitivity of rf SQUIDS are presented, and also compared with a number of practical devices. Finally, the importance of l/f noise (f is the frequency) in limiting the low frequency performance of SQUIDS is discussed.

Clarke, J.

1980-01-01

314

METHOD AND ENERGY-CARRIER PRODUCTION INSTALLATION FOR CARBON-DIOXIDE-NEUTRAL COMPENSATION FOR CURRENT LEVEL FLUCTUATIONS IN AN ELECTRICAL POWER SUPPLY SYSTEM AS A RESULT OF GENERATION PEAKS AND GENERATION TROUGHS IN THE GENERATION OF ELECTRICAL ENERG  

UK PubMed Central (United Kingdom)

A method is illustrated and described for carbon-dioxide-neutral compensation for current level fluctuations in an electrical power supply system as a result of generation peaks and generation troughs in the generation of electrical energy, in particular from regenerative energy sources using an energy-carrier production installation (1), wherein, when a generation peak occurs, electrical energy which is produced from a preferably regenerative energy source is used in an electrolysis unit (2) for hydrogen generation by electrolysis of an aqueous medium, in particular of water, wherein a hydrogen flow (6), which is generated in the electrolysis unit (2), is supplied to a reactor unit (3) designed for, in particular, catalytic generation of an energy-carrier flow (13), which contains hydrocarbon, using hydrogen and carbon dioxide and/or carbon monoxide, in particular designed for catalytic generation of methanol or methane, wherein, in a generation trough, the energy-carrier flow (13) which is produced and contains hydrocarbon is at least partially burned as required, in a combustion chamber (4), and the thermal energy of the flue-gas flow (15) formed from the combustion is used to generate electrical energy in a gas-turbine process and/or in a steam-turbine process, and the generated electrical energy is fed into the electrical power supply system, and wherein the flue-gas flow (15) is at least partially supplied to the reactor unit (3) as a carbon source for generation of the energy-carrier flow (13) which contains hydrocarbon.

KNOP KLAUS; ZOELLNER LARS

315

Does Exposure to Nitrate in Drinking Water Contribute Anything the Effect of Water Chlorination on Children Methemoglobin Levels?  

Directory of Open Access Journals (Sweden)

Full Text Available Previous studies showed contradictory findings regarding the relationship between nitrate in drinking well-water and abnormal methemoglobin (MetHb) level (>2%) among children. We studied the effect of water chlorination in this relationship in children aged up to 7. 240 subclinical children participated in this cross-sectional study. Water nitrate was analyzed for each participant, and so was blood MetHb. Analysis of two water nitrate exposure levels (50 mg/L as )-other extraneous factors (Breslow-Day-Test for interaction), bivariate and multivariate analyses were performed. Abnormal MetHb levels (up to 7.9%) were associated (p-value = 0.020) with exposure to drinking water nitrate. Only water chlorination was an effect modifier. Among those who do not disinfect water, the prevalence of ab- normal MetHb for those with nitrate level >50 mg/L was 4.95 (p-value = 0.001, 95% CI = [1.92 - 12.79]) times the prevalence for those with nitrate level <50 mg/L. Whereas, among those who do disinfect water, the prevalence for those with high nitrate levels was only 1.38 (p-value = 0.435, 95% CI = [0.62 - 3.07]) times the prevalence of those with low nitrate levels. The biological plausibility of a relationship between waterborne microorganisms, drinking water nitrate, drinking water chlorination, and development of an abnormal MetHb level needs to be further explored.

Mina Sadeq; Redouane Abouqal; Benaissa Attarassi; Mohammed Lakranbi; Rajae ElAouad; Larbi Idrissi

2012-01-01

316

The nuclear physical method for high pressure steam manifold water level gauging and its error  

International Nuclear Information System (INIS)

A new method, which is non-contact on measured water level, for measuring high pressure steam manifold water level with nuclear detection technique is introduced. This method overcomes the inherent drawback of previous water level gauges based on other principles. This method can realize full range real time monitoring on the continuous water level of high pressure steam manifold from the start to full load of boiler, and the actual value of water level can be obtained. The measuring errors were analysed on site. Errors from practical operation in Tianjin Junliangcheng Power Plant and in laboratory are also presented.

1993-01-01

317

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; Q. Zhang; T. Yang; C. Xu; X. Chen; T. Jiang

2007-01-01

318

The Fluctuation Niche in Plants  

International Nuclear Information System (INIS)

[en] Classical approaches to niche in coexisting plants have undervalued temporal fluctuations. We propose that fluctuation niche is an important dimension of the total niche and interacts with habitat and life-history niches to provide a better understanding of the multidimensional niche space where ecological interactions occur. To scale a fluctuation niche, it is necessary to relate environmental constrictions or species performance not only to the absolute values of the usual environmental and eco physiological variables but also to their variances or other measures of variability. We use Mediterranean plant communities as examples, because they present characteristic large seasonal and inter annual fluctuations in water and nutrient availabilities, along an episodic-constant gradient, and because the plant responses include a number of syndromes coupled to this gradient.

2009-01-01

319

The Fluctuation Niche in Plants  

Directory of Open Access Journals (Sweden)

Full Text Available Classical approaches to niche in coexisting plants have undervalued temporal fluctuations. We propose that fluctuation niche is an important dimension of the total niche and interacts with habitat and life-history niches to provide a better understanding of the multidimensional niche space where ecological interactions occur. To scale a fluctuation niche, it is necessary to relate environmental constrictions or species performance not only to the absolute values of the usual environmental and ecophysiological variables but also to their variances or other measures of variability. We use Mediterranean plant communities as examples, because they present characteristic large seasonal and interannual fluctuations in water and nutrient availabilities, along an episodic-constant gradient, and because the plant responses include a number of syndromes coupled to this gradient.

Jaume Terradas; Josep Peñuelas; Francisco Lloret

2009-01-01

320

Description of the US Geological Survey's water level monitoring program at the Hallam Nuclear Facility, September 1993--February 1994; Description of the collection of continuous water-level data; Description of the collection of monthly water-level data  

International Nuclear Information System (INIS)

The US Department of Energy and the US Department of the Interior agreed to monitor water-level data in 16 observation wells located at Hallam Facility, Hallam, Nebraska. The data collection period began in September 1993 and continued through August 1994. This report contains the interim summary representing six months of data collection. Specific sections include the following: description of the US Geological Survey's monitoring program at the Hallam Nuclear Facility (Sept. 1993 to Feb. 1994); description of the collection of continuous water-level data; description of the collection of monthly water-level data; table of observation well number, latitude, longitude, and depth; table of monthly ground-water levels data; table of recorder wells, rainfall, and barometric pressure unit values; and table of recorder well, rainfall, and barometric daily values; hydrographs of selected wells

1994-01-01

 
 
 
 
321

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.

2013-01-01

322

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)

[en] 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

323

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

324

Determining fluctuations of ground subsidence in areas affected by coal mining on the basis of levelling the points of observation lines  

Energy Technology Data Exchange (ETDEWEB)

This article analyzes fluctuations in ground subsidence along 11 observation lines in areas affected by underground black coal mining. Investigations show that ground subsidence does not have a fully continuous character in spite of the fact that the mined coal seams are located at a considerable depth. Irregularities in ground subsidence are not great, but in the case of thick coal seams, or in the case of mining a group of coal seams fluctuations reach 20 mm which can significantly affect some structures on the surface. On the basis of analysis of the results of observations along 11 lines a method of determining fluctuations in vertical dislocations is proposed. The dislocations are described as a function of distance to the boundary of mined coal field. A mathematical formula is also presented which permits the mean fluctuation treated as a function of the largest subsidence in full synclines to be calculated. Investigations indicate that fluctuations of ground subsidence are largest in the case of mining a group of coal seams, particularly when mining with caving is used. (9 refs.)

Szpetkowski, S.

1980-01-01

325

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; Bashar Abdallah Al-Saleem; Yousra Yousef AL-Ali

2012-01-01

326

Carboxyhaemoglobin levels in water-pipe and cigarette smokers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Water-pipe smoking is growing in popularity, especially among young people, because of the social nature of the smoking session and the assumption that the effects are less harmful than those of cigarette smoking. It has however been shown that a single water-pipe smoking session produces a 24-hour ...

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

327

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

UK PubMed Central (United Kingdom)

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.

Sundelöf A; Bartolino V; Ulmestrand M; Cardinale M

2013-01-01

328

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; Mahir Gulec; Omer Faruk Tekbas

2011-01-01

329

VANADIUM COMPLEXES FOR TESTING ARSENIC LEVELS IN DRINKING WATER  

UK PubMed Central (United Kingdom)

There is provided novel vanadium complexes useful as indicator molecules for detecting arsenate, and more specifically for quantitative measurements of arsenate in aqueous solutions. Such molecules may be used to measure arsenate concentrations in drinking water.

MCKENZIE CHRISTINE J; FRANCESCONI KEVIN; EGDAL RUNE KIRK; RABER GEORG

330

Predicted ground-water levels in the vicinity of S Area  

Energy Technology Data Exchange (ETDEWEB)

The historical minimum depths to the water table beneath the proposed sites for the DWPF and for the disposal of DWPF decontaminated salt have been estimated by reviewing water level records from several water table wells in the vicinity. The highest ground-water levels observed in the vicinity were in 1965 due to 73.5 inches of precipitation (approximately 50% above normal). The depth to the water table beneath the proposed DWPF canyon building for this period is estimated to have been approximately 23 feet. The depth to the water table beneath the proposed salt disposal site for this same high water level period is estimated to have been approximately 54 feet. Specifications for the proposed salt disposal site require 30 feet of backfill over the concrete monoliths and 10 feet of soil between the bottom of the monoliths and the historical high water table. The depth to the water table at the DWPF affects design considerations for liquefaction.

Root, R.W.

1980-01-11

331

Bath-tub vortex attenuation with the increase of in-vessel water level  

Science.gov (United States)

During the study of a bath-tub vortex formed in water flowing out through the hole in a vessel's bottom, a methodology was developed that enables controlling the change of in-vessel water level by continuous replenishment. The controlled rate of replenishment enables not only compensating for the loss of drained water and maintaining it at a constant level, but also increasing such a level. Enhancement of water level at different times after the formation of the bath-tub vortex leads to the gradual extinction of the vortex until its complete disappearance when a certain critical level of water in the vessel is achieved. A bath-tub vortex shape with a decrease of in-vessel water level and increase differs significantly.

Meshkov, E. E.; Sirotkin, A. A.

2013-07-01

332

Determination of Rn-222 in water using ultra-low level liquid scintillation counter  

International Nuclear Information System (INIS)

The technical advantages of the 1220 Quantulus liquid scintillation spectrometer allowed us to measure radon-222 in water by using alpha/ beta pulse-shape analyser(PSA) and the integral counting method are easy, convenient and rapid to analyse precisely. It is suitable for the field work and large samples size. The lower detection level of radon is 0.011 Bq liter-1. Radon is extracted from water in a toluene-base liquid scintillator. The radon analyses were done with ground water, tap water, surface water and reservoir water. Most of radon content in ground water were found to be in the range of 3 to 11 Bq liter-1. Very low radon activities found in surface water and tap water. The high level of radon activities found in reservoir water, up to 65 Bq liter-1.

1994-01-01

333

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 temperature was 30 to 40°C in the glasshouse during reproductive period and the inside air temperature was 3 to 4°C higher than outside of the glasshouse. Leaf temperature, stomatal conductance, leaf transpiration, photosynthesis and leaf water potential decreased with increase in water stress which influenced the production and abscission of flowers and pods. Water stresses reduced pod number due to both increased flower and pod abscission and fewer flowers per plant with low photosynthesis, decreased leaf water potential and high leaf temperature. In case of well watered soybean, pod number decreased in the glasshouse (T1) than the outside (T0) treatment due to a little increase in abscission of flowers and pods or low photosynthesis due to high air temperature inside the glasshouse. The flower production was significant between T0, T1 and T2 treatments, while pod number and seed number were found to decrease in T1 and T2 treatments due to increase in abscission percent of flowers and pods with the variation of photosynthesis and its parameters. The data indicated that environmentally induced variation in pod numbers in soybean was the result of both changes in flower and pod abscission and the number of reduced flower production. With the variation of high air temperature in the glasshouse, pod and seed number were reduced in T1 than in T0 treatment. Nitrogen accumulation of leaf declined drastically in T1 treatment at R6 stage which was limiting factor for photosynthesis and finally total dry matter as well as seed yield decreased in T1 compare to T0 treatment. The stress treatments reduced all growth parameters, dry matter production and nitrogen accumulation thus seed yield decreased in T2, T3 and T4 treatments, respectively. The differences in different soil water levels and temperature were reflected in lower production of total dry matter and seed yield.

Begum Samsun Nahar; Takeshi Ikeda

2001-01-01

334

Multiscale fluctuations in nuclear response  

Energy Technology Data Exchange (ETDEWEB)

The nuclear collective response is investigated in the framework of a doorway picture in which the spreading width of the collective emotion is described as a coupling to more and more complex configurations. It is shown that this coupling induces fluctuations of the observed strength. In the case of a hierarchy of overlapping decay channels, Ericson fluctuations are observed at different scales. Methods for extracting these scales and the related lifetimes are discussed. Finally, it is shown that the coupling of different states at one level of complexity to some common decay channels at the next level, may produce interference-like patterns in the nuclear response. This quantum effect leads to anew type of fluctuations with a typical width related to the level spacing. (author) 25 refs.

Lacroix, D.; Chomaz, Ph

1999-01-01

335

Multiscale fluctuations in nuclear response  

International Nuclear Information System (INIS)

The nuclear collective response is investigated in the framework of a doorway picture in which the spreading width of the collective emotion is described as a coupling to more and more complex configurations. It is shown that this coupling induces fluctuations of the observed strength. In the case of a hierarchy of overlapping decay channels, Ericson fluctuations are observed at different scales. Methods for extracting these scales and the related lifetimes are discussed. Finally, it is shown that the coupling of different states at one level of complexity to some common decay channels at the next level, may produce interference-like patterns in the nuclear response. This quantum effect leads to anew type of fluctuations with a typical width related to the level spacing. (author)

1999-01-01

336

Treatment of low level waste water by reverse osmosis  

International Nuclear Information System (INIS)

[en] A Study on the removal of certain radioactive elements Such as 141Ce, 51Cr 134Cu, 106Ru and 131I by Reverse Osmosis and the effect of surface activity agent on property of membrance are described in this paper. RO model is carried out to examine the treatment of actual reactor waste water and radioactive laundry waste water. The removal efficiency of total ? is 98%. Three preprocessing (cloth pocket filtrator, hivefiltrator and zone) and membrane cleaning methods (acid, ozone and spongeball) are also investigated

1987-01-01

337

Natural radiation level in drinking water in Homs city  

International Nuclear Information System (INIS)

In this study, radon concentrations were measured at the sources of drinking water and in some tap water in houses in Homs County. All measurements showed that concentrations are within the international allowed limits and there is no big difference in concentration between the sources and the houses. Also total alpha/beta and radium-226 content were measured in the samples of the sources and the houses using liquid scintillation counter. All measurements showed that concentrations are within the international allowed limits. (authors)

2008-01-01

338

Mechanism of water vapor gasification at high hydrogen levels  

Energy Technology Data Exchange (ETDEWEB)

The influence of hydrogen and carrier or diluent gases (He, Ar, Kr, N/sub 2/) on water vapor gasification was studied at total pressures between 0.15 and 2 MPa with chars prepared at 600 degrees C from brown coal, sugar, and polyvinyl chloride and with a glassy carbon (HTT 1100 degrees C). Hydrogen is a strong inhibitor at all pressures, but increasing pressure has an additional effect. The gasification kinetics follow a two-site surface reaction. Helium, as compared with the other inert gases, is a strong inhibitor of the water vapor gasification at elevated pressures but the inhibition is of a different nature than inhibition by hydrogen.

Huettinger, K.J.

1988-01-01

339

???????????????? Research on Changes of Peak Water Level in the Pearl River Estuary  

Digital Repository Infrastructure Vision for European Research (DRIVER)

???????????????????????????????????????????????????????????????????????1) 20??50???????????????????????????2) ???????????????20??90???????????????????????????????????????1981??1983??3) ??????????????????????????????????? Higher peak water level of the Pearl River Estuary gives a great t...

??; ???; ???; ???; ???; ???

340

Identification and simulation for steam generator water level based on Kalman Filter  

International Nuclear Information System (INIS)

[en] In order to effectively control the water level of the steam generator (SG), this paper has set about the state-observer theory in modern control and put forward a method to detect the 'false water level' based on Kalman Filter. Kalman Filter is a efficient tool to estimate state-variable by measured value including noise. For heavy measurement noise of steam flow, constructing a 'false water level' observer by Kalman Filter could availably obtain state variable of 'false water level'. The simulation computing for the dynamics characteristic of nuclear SG water level process under several typically running power was implemented by employing the simulation model. The result shows that the simulation model accurately identifies the 'false water level' produced in the reverse thermal-dynamic effects of nuclear SG water level process. The simulation model can realize the precise analysis of dynamics characteristic for the nuclear SG water level process. It can provide a kind of new ideas for the 'false water level' detecting of SG. (authors)

2008-01-01

 
 
 
 
341

Digitization and simulation realization of full range control system for steam generator water level  

International Nuclear Information System (INIS)

In this paper, a full range digital control system for the steam generator water level is designed by a control scheme of single element control and three-element cascade feed-forward control, and the method to use the software module configuration is proposed to realize the water level control strategy. This control strategy is then applied in the operation of the nuclear power simulation machine. The simulation result curves indicate that the steam generator water level maintains constant at the stable operation condition, and when the load changes, the water level changes but finally maintains the constant. (authors)

2010-01-01

342

Water mass change in the Amazon basin estimated by multi-temporal SAR data, GRACE gravimetry and water level observations  

Science.gov (United States)

The 2007 IPCC assessment report identified the land hydrology as one of the most uncertain components of the global water cycle. Variations of continental water masses occur in several compartments (e.g. surface and soil water, snow/ice, and groundwater). Mass variations and related changes of surface water exten-sions are being observed by contemporary space and in-situ observation systems such as GRACE gravim-etry, altimetry, optical/infrared sensors, SAR/InSAR, and in-situ river gauges. In this session we will present a regional multi-sensor study in the Amazon basin. The study focuses on the quantification of variations of water mass and water surface extent caused by extreme flood and drought situations that were frequent during the last decade. PALSAR data of two extreme events was selected; once when the Amazon River was flooded (March/April 2009) and once when the region suffered from a se-vere drought (October/November 2009). The advantage of using PALSAR is that it operates in L-Band and has the possibility to penetrate through the vegetation which is essential in the Amazon basin with its dense vegetation. Time series of water level variations were obtained from two in-situ gauges at Manacapuru and Obidos as well as from Envisat satellite altimetry. Total water storage change in the whole region was given by GRACE gravimetry. First, the variation of water mass is computed numerically using GRACE. Second the water level variations obtained from the two river gauges are analyzed with respect to observation of Envisat. Third the surface water extent is estimated by extracting water masks from PALSAR image data. The water mass change is obtained by intersecting the water masks with a medium resolution digital elevation model (SRTM). More specifically, water heights along the boundary of the river body were extracted from the DEM and processed for error reduction. Then, pixel heights within the river contour were interpolated with a Delaunay triangula-tion. Multiplying the differences in heights between high and low water periods by the area of the DEM reso-lution cell and summing them up over the river area provided an estimate of the total volume change. In the end, the presentation will give an assessment of the spatio-temporal consistency of the different ob-servation systems by comparing the spatial patterns of water variability in the data sets with respect to their temporal development and existing phase lags. Based on the level of consistency we will provide an outlook on the applicability of measurements of water levels and surface water extent for an independent assess-ment of water mass variations.

Spiridonova, S.; Seitz, F.; Hedman, K.; Meyer, F.

2012-04-01

343

Fluctuations of sea-water chemistry during Gargasian (Middle Aptian) time. Data from trace-element content (Mg, Sr, Mn, Fe) in hemipelagic carbonates from La Marcouline Quarry (Cassis, SE France)  

Directory of Open Access Journals (Sweden)

Full Text Available In the Lower Aptian historical stratotype area (Cassis-La Bédoule, SE France), a geochemical study of the Gargasian (Middle Aptian) marl-limestone alternations of the La Marcouline quarry complements data already obtained from Bedoulian (Early Aptian) sediments there. Nannoconids are the main carbonate producers in both limestones and marls. Although diagenetic minerals, such as ankerite (2.5%) are present in small amounts, the trace-element content of bulk carbonate is very close to that of Nannoconus spp. so geochemical sequences can be defined. The long-term evolution of trace-element content was not affected by diagenetic processes, variations in carbonate mineralogy, or a change of carbonate producers. An increase of around 500 ppm in the strontium content of bulk carbonate occurs between the base of the Cabri zone (late Bedoulian) and the Algerianus zone (late Gargasian). This evolution is linked to fluctuations in seawater Sr/Ca ratios caused by variability in the influx of hydrothermal and river waters, by changes in the ratio of aragonite/calcite production and by shifts in sea level. The eustatic sequence Aptian 4, its parasequences and its key surfaces (sequence boundaries, maximum flooding surface) are clearly reflected in the evolution of the bulk-carbonate contents of manganese.

RENARD Maurice; RAFELIS Marc de; EMMANUEL Laurent; BELTRAN Catherine; MOULLADE Michel; TRONCHETTI Guy

2007-01-01

344

Neural Network Model for Prediction of Ground Water Level in Metropolitan Considering Rainfall-Runoff as a Parameter  

Directory of Open Access Journals (Sweden)

Full Text Available In metropolitan area the ground water is the important resource of drinking water. To preserve the ground water level several rain water harvesting techniques are implemented now a days. A neural network model has been developed for ground water level prediction. Various models developed before for ground water level prediction with artificial neural network methodology. Most of these models these models consider rainfall and current ground water level as input parameter. This model considers rainfall-runoff as an important factor which represents the performance of rain water harvesting techniques in urban area. So this model predicts the ground water level with the effect of rain water harvesting techniques.

Sanjeev Kumar; Ajay Indian; Zubair Khan

2013-01-01

345

The level of environmental noise affects the physiological performance of Glycine max under water deficit  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english Plants in natural environments are subjected to a multitude of environmental cues. However, studies addressing physiological analyzes are usually focused on the isolation of a stress factor, making it difficult to understand plants behavior in their extremely complex natural environments. Herein, we analyzed how environmental variability (noise) may influence physiological processes of Glycine max under water deficit conditions. The plants were kept in a greenhouse (semi- (more) controlled environment - E SC) and in a growth chamber (controlled environment - E C) under two water regime conditions (100 and 30% of replacement of the water lost by evapotranspiration) for 30 days. The environmental variability was daily monitored with automatic sensors to record temperature, humidity, and irradiance. The physiological responses were analyzed by leaf gas exchanges, chlorophyll fluorescence, biomembrane integrity, and growth parameters. The results showed that water deficiency caused significant reductions in the physiological parameters evaluated. However, the environment with high variability (E SC) caused more extensive damages to biomembranes, regardless the water regime likely compromising physiological efficiency. The lower variability of E C promoted higher efficiency of total biomass production in both water regimes compared to the E SC. Therefore, our results support the hypothesis that more variable environmental conditions can limit the growth of Glycine max in response to the fluctuation of resources, therefore amplifying the effect of water deficit.

Bertolli, Suzana Chiari; Souza, Gustavo M.

2013-01-01

346

Elevated levels of radioactivity in water wells in Los Angeles and Orange Counties, California  

International Nuclear Information System (INIS)

Levels of gross alpha particle radioactivity nearly three times the maximum contamination levels (MCL) have been detected for several years in well waters and related surface waters in Los Angeles and Orange Counties, California. A few elevated levels of uranium have also been recorded. The affected wells and related surface waters represent only a minor fraction of the water sampled and tested in this area. None of the excessive radioactivity is believed to persist in the municipal waters sold to the public, due to the customary blending of waters from several wells or sources which water purveyors practice. This papers is a preliminary survey of the occurrence, possible sources, fate, and implications of these elevated radioactivity levels

1987-01-01

347

Fluorine level in some city water supplies of Bangladesh  

International Nuclear Information System (INIS)

[en] Nuclear reaction based Proton Induced Gamma Emission (PIGE) analytical method was employed for the quantitative measurement of fluorine in the city water supplies of the major cities of Bangladesh. 102 water samples collected from 14 city supplies were analyzed and these samples contain fluorine in the range of 0.03 to 1.10 mg/L with a mean of 0.33 ± 0.21 mg/L. It was also observed that except the samples of Barisal, Dinajpur and Rajshahi, all other water samples analyzed contain a much lower amount of fluorine than the maximum permissible value for Bangladesh in drinking water, which is 1 mg/L. The mean concentration of fluorine in the samples of Barisal, Dinajpur and Rajshahi are respectively 0.79±0.01, 0.71±0.13 and 0.92±0.18 mg/L. For the 55 samples of Dhaka city supply the mean fluorine concentration is 0.31±0.17 mg/L and that of 9 samples from Chittagong city supply is 0.19±0.10 mg/L, which is the lowest among the 14 city supply samples analyzed in this study

2003-01-01

348

Some methodical features of water ecosystem petroleum pollution level determination  

International Nuclear Information System (INIS)

A short review of analytical approaches to determine mineral oil products in the environment is given. Advantages and disadvantages of the used procedures are presented. The combined optical method of mineral oil products assessment is shown to be expedient ensuring complete extraction and determination of all kinds of mineral oil products in water and bottom sediments

2007-01-01

349

Determination of low levels of cationic polyelectrolytes in water  

Energy Technology Data Exchange (ETDEWEB)

Anionic dye complexation has been used to measure the concentrations of cationic polyelectrolytes in water. The colloidal form of the complex interferes with spectrophotometric measurements and must be removed. Advantage is taken of the hydrophobic character of the complex to facilitate its removal with Freon.

Parazak, D.P.; Burkhardt, C.W.; McCarthy, K.J.

1987-05-15

350

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 concentrations were 3.66±0.028 and 0.045±0.003 mg L-1 in the spring water and 3.52±0.011 and 0.025±0.001 mg L-1 in the mineral water, respectively. Finally; nitrate and nitrite levels in water samples were in accordance with the related national and international regulations and considered safe for consuming.

Nurhayat Atasoy; Suleyman Alemdar; Ufuk Mercan; Sema Agaoglu

2011-01-01

351

Design and Implementation of a Water Level Controller using Fuzzy Logic  

Directory of Open Access Journals (Sweden)

Full Text Available This paper analyzes the effectiveness of water level control using fuzzy logic. The water level in the tank is sensed using transistor switching principle. The level sensed is fed to the PIC16 microcontroller. The user provides the set point to the microcontroller through serial communication using the COM development port software, Terminal. It computes the error as the difference between the set point and the process variable. The fuzzy logic programmed in the microcontroller is applied which controls the water level in the tank using the drain and the feed pumps. Once the set point has been reached, the message along with the present level is sent back through serial communication to the user interface on a PC. Thus, the water level in the tank is controlled according to the set point given by the user. The implementation of a fuzzy level controller has many applications such as boiler drum level control, reverse osmosis plant, demineralisation plant etc.

Namrata Dey; Ria Mandal; M Monica Subashini

2013-01-01

352

???????????????? Research on Changes of Peak Water Level in the Pearl River Estuary  

Directory of Open Access Journals (Sweden)

Full Text Available ???????????????????????????????????????????????????????????????????????1) 20??50???????????????????????????2) ???????????????20??90???????????????????????????????????????1981??1983??3) ??????????????????????????????????? Higher peak water level of the Pearl River Estuary gives a great threat to life and construction losses in these developed areas. The peak water level series of the Denglongshan and Hengmen stations are analyzed by several methods. The results show that: 1) the peak water level has significant upward trend at representative station in the Pearl River Estuary since 1950s; 2) the increasing of the peak water level belongs to mutations phenomenon since early 1990s, the Denglongshan and Hengmen stations began to mutate re-spectively in 1981 and 1983; 3) the influence of sea level rise on change trend of the peak water level is greater than that of the maximum flow.  

??; ???; ???; ???; ???; ???

2012-01-01

353

A semi-classical approach of the relationship between simple cells' size and their living temperature limits based on number fluctuations of water coherence domains  

International Nuclear Information System (INIS)

Starting from the concepts of the quantum electrodynamics (QED) theory of coherence domains (CD) in water we propose a model aimed to evaluate the relationship between the size and the living temperature limits for simple, small cells. Cells are described as spherical potential wells with impenetrable walls, with CDs moving inside. The radius of the spherical potential well was estimated for physiological temperatures and the results match to bacteria and yeasts cells' size. As a CD in the spherical cell exerts a force upon the membrane, a 'gas' formed by CDs bears a pressure on the walls. A classical statistical stability condition relates this pressure to cell volum