975 resultados para LEVEL VARIATIONS


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Hulun Lake, China’s fifth-largest inland lake, experienced severe declines in water level in the period of 2000-2010. This has prompted concerns whether the lake is drying up gradually. A multi-million US dollar engineering project to construct a water channel to transfer part of the river flow from a nearby river to maintain the water level was completed in August 2010. This study aimed to advance the understanding of the key processes controlling the lake water level variation over the last five decades, as well as investigate the impact of the river transfer engineering project on the water level. A water balance model was developed to investigate the lake water level variations over the last five decades, using hydrological and climatic data as well as satellite-based measurements and results from land surface modelling. The investigation reveals that the severe reduction of river discharge (- 364±64 mm/yr, ~70% of the five-decade average) into the lake was the key factor behind the decline of the lake water level between 2000 and 2010. The decline of river discharge was due to the reduction of total runoff from the lake watershed. This was a result of the reduction of soil moisture due to the decrease of precipitation (-49±45 mm/yr) over this period. The water budget calculation suggests that the groundwater component from the surrounding lake area as well as surface run off from the un-gauged area surrounding the lake contributed ~ net 210 Mm3/yr (equivalent to ~ 100 mm/yr) water inflows into the lake. The results also show that the water diversion project did prevent a further water level decline of over 0.5 m by the end of 2012. Overall, the monthly water balance model gave an excellent prediction of the lake water level fluctuation over the last five decades and can be a useful tool to manage lake water resources in the future.

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Introduction: This chapter describes the characteristics of
adult patients on renal replacement therapy (RRT) in the
UK in 2009. The prevalence rates per million population
(pmp) were calculated for Primary Care Trusts in England,
Health and Social Care Areas in Northern Ireland, Local
Health Boards in Wales and Health Boards in Scotland.
These areas will be referred to in this report as ‘PCT/HBs’.
Methods: Data were electronically collected from all 72
renal centres within the UK. A series of cross-sectional and
longitudinal analyses were performed to describe the
demographics of prevalent RRT patients in 2009 at centre
and national level. Age and gender standardised ratios for
prevalence rates in PCT/HBs were calculated. Results:
There were 49,080 adult patients receiving RRT in the UK
on 31st December 2009, equating to a UK prevalence of
794 pmp. This represented an annual increase in prevalent
numbers of approximately 3.2% although there was significant
variation between centres and PCT/HB areas. The
growth rate from 2008 to 2009 for prevalent patients by
treatment modality in the UK was 4.2% for haemodialysis
(HD), a fall of 7.2% for peritoneal dialysis (PD) and a
growth of 4.4% with a functioning transplant. There has
been a slow but steady decline in the proportion of PD
patients from 2000 onwards. Median RRT vintage was 5.4
years. The median age of prevalent patients was 57.7
years (HD 65.9 years, PD 61.2 years and transplant 50.8
years). For all ages, prevalence rates in males exceeded
those in females: peaks for males were in the 75–79 years
age group at 2,632 pmp and for females in the 70–74
years age group at 1,445 pmp. The most common identifiable
renal diagnosis was biopsy-proven glomerulonephritis
(16.0%), followed by diabetes (14.7%). Transplantation was
the most common treatment modality (48%), HD in 44%
and PD 8%. However, HD was increasingly common with
increasing age and transplantation less common. Conclusions:
The HD and transplant population continued to
expand whilst the PD population contracted. There were
national, regional and dialysis centre level variations in
prevalence rates. This has implications for service planning
and ensuring equity of care for RRT patients.

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Hulun Lake, China's fifth-largest inland lake, experienced severe declines in water level in the period of 2000-2010. This has prompted concerns whether the lake is drying up gradually. A multi-million US dollar engineering project to construct a water channel to transfer part of the river flow from a nearby river to maintain the water level was completed in August 2010. This study aimed to advance the understanding of the key processes controlling the lake water level variation over the last five decades, as well as investigate the impact of the river transfer engineering project on the water level. A water balance model was developed to investigate the lake water level variations over the last five decades, using hydrological and climatic data as well as satellite-based measurements and results from land surface modelling. The investigation reveals that the severe reduction of river discharge (-364±64 mm/yr, ∼70% of the five-decade average) into the lake was the key factor behind the decline of the lake water level between 2000 and 2010. The decline of river discharge was due to the reduction of total runoff from the lake watershed. This was a result of the reduction of soil moisture due to the decrease of precipitation (-49±45 mm/yr) over this period. The water budget calculation suggests that the groundwater component from the surrounding lake area as well as surface run off from the un-gauged area surrounding the lake contributed ∼ net 210 Mm3/yr (equivalent to ∼ 100 mm/yr) water inflows into the lake. The results also show that the water diversion project did prevent a further water level decline of over 0.5 m by the end of 2012. Overall, the monthly water balance model gave an excellent prediction of the lake water level fluctuation over the last five decades and can be a useful tool to manage lake water resources in the future.

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De nombreux problèmes pratiques qui se posent dans dans le domaine de la logistique, peuvent être modélisés comme des problèmes de tournées de véhicules. De façon générale, cette famille de problèmes implique la conception de routes, débutant et se terminant à un dépôt, qui sont utilisées pour distribuer des biens à un nombre de clients géographiquement dispersé dans un contexte où les coûts associés aux routes sont minimisés. Selon le type de problème, un ou plusieurs dépôts peuvent-être présents. Les problèmes de tournées de véhicules sont parmi les problèmes combinatoires les plus difficiles à résoudre. Dans cette thèse, nous étudions un problème d’optimisation combinatoire, appartenant aux classes des problèmes de tournées de véhicules, qui est liée au contexte des réseaux de transport. Nous introduisons un nouveau problème qui est principalement inspiré des activités de collecte de lait des fermes de production, et de la redistribution du produit collecté aux usines de transformation, pour la province de Québec. Deux variantes de ce problème sont considérées. La première, vise la conception d’un plan tactique de routage pour le problème de la collecte-redistribution de lait sur un horizon donné, en supposant que le niveau de la production au cours de l’horizon est fixé. La deuxième variante, vise à fournir un plan plus précis en tenant compte de la variation potentielle de niveau de production pouvant survenir au cours de l’horizon considéré. Dans la première partie de cette thèse, nous décrivons un algorithme exact pour la première variante du problème qui se caractérise par la présence de fenêtres de temps, plusieurs dépôts, et une flotte hétérogène de véhicules, et dont l’objectif est de minimiser le coût de routage. À cette fin, le problème est modélisé comme un problème multi-attributs de tournées de véhicules. L’algorithme exact est basé sur la génération de colonnes impliquant un algorithme de plus court chemin élémentaire avec contraintes de ressources. Dans la deuxième partie, nous concevons un algorithme exact pour résoudre la deuxième variante du problème. À cette fin, le problème est modélisé comme un problème de tournées de véhicules multi-périodes prenant en compte explicitement les variations potentielles du niveau de production sur un horizon donné. De nouvelles stratégies sont proposées pour résoudre le problème de plus court chemin élémentaire avec contraintes de ressources, impliquant dans ce cas une structure particulière étant donné la caractéristique multi-périodes du problème général. Pour résoudre des instances de taille réaliste dans des temps de calcul raisonnables, une approche de résolution de nature heuristique est requise. La troisième partie propose un algorithme de recherche adaptative à grands voisinages où de nombreuses nouvelles stratégies d’exploration et d’exploitation sont proposées pour améliorer la performances de l’algorithme proposé en termes de la qualité de la solution obtenue et du temps de calcul nécessaire.

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Of the several physical processes occurring in the sea, vertical motions have special significance because of their marked effects on the oceanic environment. upwelling is the process in the sea whereby subsurface layers move up towards the surface. The reverse process of surface water sinking to subsurface depths is called sinking. Upwelling is a very conspicuous feature along the west coasts of continents and equatorial regions, though upwelling also occurs along certain east coasts of continents and other regions, The Thesis is an outcome of some investigations carried out by the author on upwelling and sinking off the west and east coasts of India. The aim of the study is to find out the actual period and duration of upwelling and sinking, their driving mechanism, various associated features and the factors that affect these processes. It is achieved by analysing the temperature and density fields off the west and east coasts of India, and further conclusions are drawn from the divergence field of surface currents, wind stress and sea level variations.

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The present success in the manufacture of multi-layer interconnects in ultra-large-scale integration is largely due to the acceptable planarization capabilities of the chemical-mechanical polishing (CMP) process. In the past decade, copper has emerged as the preferred interconnect material. The greatest challenge in Cu CMP at present is the control of wafer surface non-uniformity at various scales. As the size of a wafer has increased to 300 mm, the wafer-level non-uniformity has assumed critical importance. Moreover, the pattern geometry in each die has become quite complex due to a wide range of feature sizes and multi-level structures. Therefore, it is important to develop a non-uniformity model that integrates wafer-, die- and feature-level variations into a unified, multi-scale dielectric erosion and Cu dishing model. In this paper, a systematic way of characterizing and modeling dishing in the single-step Cu CMP process is presented. The possible causes of dishing at each scale are identified in terms of several geometric and process parameters. The feature-scale pressure calculation based on the step-height at each polishing stage is introduced. The dishing model is based on pad elastic deformation and the evolving pattern geometry, and is integrated with the wafer- and die-level variations. Experimental and analytical means of determining the model parameters are outlined and the model is validated by polishing experiments on patterned wafers. Finally, practical approaches for minimizing Cu dishing are suggested.

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The present success in the manufacture of multi-layer interconnects in ultra-large-scale integration is largely due to the acceptable planarization capabilities of the chemical-mechanical polishing (CMP) process. In the past decade, copper has emerged as the preferred interconnect material. The greatest challenge in Cu CMP at present is the control of wafer surface non-uniformity at various scales. As the size of a wafer has increased to 300 mm, the wafer-level non-uniformity has assumed critical importance. Moreover, the pattern geometry in each die has become quite complex due to a wide range of feature sizes and multi-level structures. Therefore, it is important to develop a non-uniformity model that integrates wafer-, die- and feature-level variations into a unified, multi-scale dielectric erosion and Cu dishing model. In this paper, a systematic way of characterizing and modeling dishing in the single-step Cu CMP process is presented. The possible causes of dishing at each scale are identified in terms of several geometric and process parameters. The feature-scale pressure calculation based on the step-height at each polishing stage is introduced. The dishing model is based on pad elastic deformation and the evolving pattern geometry, and is integrated with the wafer- and die-level variations. Experimental and analytical means of determining the model parameters are outlined and the model is validated by polishing experiments on patterned wafers. Finally, practical approaches for minimizing Cu dishing are suggested.

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Understanding the factors involved in the development of postpartum depressive disorders has important implications for the detection of women at risk, and the development of theory‐driven preventative treatments. In the current study, recent innovations in the assessment of idiographic cognitive functioning among adult, non‐pregnant samples were administered to a sample of healthy primiparous women to investigate their predictive utility in the onset of low mood following childbirth. Cognitive biases using autobiographical material, and the degree of self‐devaluation during brief episodes of naturally occurring low mood were assessed in 94 concurrently well women in the third trimester of their first pregnancy. The degree of depressive symptomatology at 2 and 8 weeks postpartum was assessed subsequently. Antenatal self‐devaluative tendencies and a lack of specificity in autobiographical retrieval were not associated with low mood in the initial weeks following delivery, when biological factors are believed to play an important role, but did predict depressive symptoms more distally at 8 weeks after childbirth. This relationship was demonstrated after controlling for educational level, variations in antenatal dysphoria, previous emotional difficulties, neuroticism and the woman's own experience of mothering. The theoretical and clinical implications of the findings are discussed.

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Issue addressed: Despite recognition that urban infrastructure influences physical activity, there have been no comparisons between Australian city-level patterns of physical activity. This study ranked Australian cities in terms of adults? participation in leisure-time physical activity and examined city-level variations in activity trends between 2001 and 2009. Methods: Data on participation in leisure-time physical activity in adults (=15 years) between 2001 and 2009 were obtained from the Exercise Recreation and Sport Survey (ERASS), a computer-assisted telephone interview conducted to collect population-level sport participation information by the Australian Sports Commission. Data were analysed for respondents residing in the eight capital cities of Australia. The prevalence of meeting recommended ?health-enhancing physical activity? (HEPA) and levels of walking were calculated by age, gender and survey year. Multiple linear logistic regression analyses were used to compare cities. Results: Pooled data from 174,323 adults across years showed that Melbourne, Brisbane, Perth and Canberra residents were significantly more active than Sydney, Adelaide and Hobart residents in terms of HEPA. Hobart, Perth and Melbourne residents were significantly more likely to walk =5 sessions a week compared with their counterparts in other cities. HEPA and walking increased across most cities between 2001 and 2009. Conclusion: There are significant differences between Australian cities in physical activity and walking levels, over and above differences attributable to age, gender or educational levels. While this may be due to infrastructure differences, comparative information on indicators of the built environment and transport infrastructure are not available.

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Objective: To investigate: (i) how lunch frequency of adolescents varies between schools and between classes within schools; (ii) the associations between frequency of lunch and individual sociodemographic factors and school characteristics; and (iii) if any observed associations between lunch frequency and school characteristics vary by gender and age groups. Design: Cross-sectional study in which students and school headmasters completed self-administered questionnaires. Associations were estimated by multilevel multivariate logistic regression. Setting: The Danish arm of the Health Behaviour in School-Aged Children study 2010. Subjects: Students (n 4922) aged 11, 13 and 15 years attending a random sample of seventy-three schools. Results: The school-level and class-level variations in low lunch frequency were small (intraclass correlation coefficient <2·1 %). At the individual level, low lunch frequency was most common among students who were boys, 13- and 15-year-olds, from medium and low family social class, descendants of immigrants, living in a single-parent family and in a reconstructed family. School-level analyses suggested that having access to a canteen at school was associated with low lunch frequency (OR=1·47; 95% CI 1·14, 1·89). Likewise not having an adult present during lunch breaks was associated with low lunch frequency (OR=1·44; 95% CI 1·18, 1·75). Cross-level interactions suggested that these associations differed by age group. Conclusions: Lunch frequency among Danish students appears to be largely influenced by sociodemographic factors. Additionally, the presence of an adult during lunch breaks promotes frequent lunch consumption while availability of a canteen may discourage frequent lunch consumption. These findings vary between older and younger students.

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A descriptive analysis of the responses of plankton from lakes lateral to a river in its mouth zone into a tropical reservoir to water level variations is presented. Three situations were reported: 1) a comparison of species richness and diversity and of algae population abundance in prolonged drought and in periods of connection of lakes to the river, 2) the spatial distribution of abundance and richness of Rotifera species in four isolated water bodies formed by fragmentation of a lateral lake during a period of prolonged drought and in the same areas during a period of integrity as an ecosystem, 3) the variability of total zooplankton and Cladocera densities at the end of the isolation period of a lateral lake and after the recovery of connection with the river and in a year of continuous connection with the lotic ecosystem. Various idiosyncrasies were observed in connected lateral lakes, like the surface hydrologic connectivity, a primary factor in species richness modifcations and a secondary controlling factor of plankton abundance. Underground hydrologic connectivity, through the river[forward arrow] lake water fux during the high-water period and lake [forward arrow] river during drought period, appears to have an important role in richness and abundance variations of planktonic populations in the lake isolated from the river.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Geociências e Meio Ambiente - IGCE

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O presente estudo teve como objetivo investigar a propagação da maré no sistema fluvial Guamá-Capim, na região amazônica, considerando aspectos hidrológicos e geomorfológicos. Os métodos empregados incluem dados históricos de vazões fluviais e níveis d'água, além de medições próprias de maré em diferentes locais e períodos ao longo do sistema. Os principais pontos defendidos no presente trabalho incluem a vazão fluvial como principal fator para a distorção da maré e consequente formação de pororoca no sistema, assim como o baixo relevo da área seria responsável por incremento na incursão da maré para o continente. Os resultados revelam uma penetração da maré de mais de 200 km, ocorrendo também uma forte deformação da maré, se intensificando gradualmente a montante, resultando em uma vazante até 5 horas mais longa que a enchente 161 km a montante, apresentando também velocidades de enchente levemente superiores, incluindo o decaimento contínuo da altura da maré, intensificado a partir desse ponto. Sazonalmente, a vazão fluvial aumenta 10 vezes no rio Guamá e 4 vezes no rio Capim. Durante períodos de alta descarga, combinados com marés equinociais (e.g. março-abril), o fenômeno da pororoca ocorre no sistema, em associação ao baixo relevo da área. Desta forma as principais conclusões são de que a forte deformação da maré relacionada a altas descargas fluviais e o baixo relevo da área são os fatores preponderantes na propagação da maré no sistema e formação de pororoca. Mais além, o sistema foi classificado como tidal river, onde a enorme descarga de água doce na região costeira amazônica resulta na prática ausência de salinidade no sistema estudado. Assim, seu estudo vem contribuir na definição e classificação de sistemas estuarinos.