1,669 research outputs found

    An Overview of the Groundwater Use and Capacity Use Program

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    2010 S.C. Water Resources Conference - Science and Policy Challenges for a Sustainable Futur

    Flow heterogeneity in the fractured Chalk aquifer of southern England

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    The aim of the current work is to investigate the heterogeneity of flow in the Chalk aquifer of southern England. The rock mass properties and hydraulic characteristics of the aquifer have been characterised using a suite of geological and geophysical surveys and hydraulic tests. Fracture logs have been produced based on core logging and using optical images of boreholes. Flow has been characterised using borehole flow logs and dilution tests and hydraulic conductivity measured using packer tests. Fractures have been recorded with apertures in the range <1mm to about 30cm (sub-karstic enlargement) in diameter, however, hydrogeologically significant flow is not restricted to the enlarged fractures and is affected by the local groundwater head distribution. The work is being undertaken as part of the LOCAR Programme. LOCAR is a multi-project programme with the aim of measuring and modelling processes controlling water and material fluxes within lowland permeable catchments in the UK

    A variational approach to the QCD wave functional:Dynamical mass generation and confinement

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    We perform a variational calculation in the SU(N) Yang Mills theory in 3+1 dimensions. Our trial variational states are explicitly gauge invariant, and reduce to simple Gaussian states in the zero coupling limit. Our main result is that the energy is minimized for the value of the variational parameter away form the perturbative value. The best variational state is therefore characterized by a dynamically generated mass scale MM. This scale is related to the perturbative scale ΛQCD\Lambda_{QCD} by the following relation: αQCD(M)=π41N\alpha_{QCD}(M)={\pi\over 4}{1\over N}. Taking the one loop QCD β\beta- function and ΛQCD=150Mev\Lambda_{QCD}=150 Mev we find (for N=3) the vacuum condensate απ=0.008Gev4{\alpha\over \pi}= 0.008 Gev^4.Comment: 37 pages, (1 Figure available upon request), preprint LA-UR-94-2727, PUPT-149

    Impact of Sleep and Circadian Disruption on Energy Balance and Diabetes: A Summary of Workshop Discussions

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    A workshop was held at the National Institute for Diabetes and Digestive and Kidney Diseases with a focus on the impact of sleep and circadian disruption on energy balance and diabetes. The workshop identified a number of key principles for research in this area and a number of specific opportunities. Studies in this area would be facilitated by active collaboration between investigators in sleep/circadian research and investigators in metabolism/diabetes. There is a need to translate the elegant findings from basic research into improving the metabolic health of the American public. There is also a need for investigators studying the impact of sleep/circadian disruption in humans to move beyond measurements of insulin and glucose and conduct more in-depth phenotyping. There is also a need for the assessments of sleep and circadian rhythms as well as assessments for sleep-disordered breathing to be incorporated into all ongoing cohort studies related to diabetes risk. Studies in humans need to complement the elegant short-term laboratory-based human studies of simulated short sleep and shift work etc. with studies in subjects in the general population with these disorders. It is conceivable that chronic adaptations occur, and if so, the mechanisms by which they occur needs to be identified and understood. Particular areas of opportunity that are ready for translation are studies to address whether CPAP treatment of patients with pre-diabetes and obstructive sleep apnea (OSA) prevents or delays the onset of diabetes and whether temporal restricted feeding has the same impact on obesity rates in humans as it does in mice

    Quantum-statistical transport phenomena in memristive computing architectures

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    The advent of reliable, nanoscale memristive components is promising for next generation compute-in-memory paradigms, however, the intrinsic variability in these devices has prevented widespread adoption. Here we show coherent electron wave functions play a pivotal role in the nanoscale transport properties of these emerging, non-volatile memories. By characterizing both filamentary and non-filamentary memristive devices as disordered Anderson systems, the switching characteristics and intrinsic variability arise directly from the universality of electron transport in disordered media. Our framework suggests localization phenomena in nanoscale, solid-state memristive systems are directly linked to circuit level performance. We discuss how quantum conductance fluctuations in the active layer set a lower bound on device variability. This finding implies there is a fundamental quantum limit on the reliability of memristive devices, and electron coherence will play a decisive role in surpassing or maintaining Moore's Law with these systems.Comment: 13 pages, 6 figure

    Identification of urgent gaps in public and policymaker knowledge of heart failure: results of a global survey

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    Background: Despite advances in the treatment of heart failure (HF) with reduced ejection fraction, people with HF continue to have a high risk of mortality and hospitalisation. Patients also suffer from poor quality of life, with reduced societal and economic participation. The burden of HF on patients and healthcare systems is extraordinary, yet awareness remains low. This survey was conducted to identify gaps in general public and policymaker knowledge around HF. Methods: A closed-question web-based survey of the general public and policymakers was conducted between February and October 2020. Study outcomes assessed the participants’ awareness and understanding of HF symptoms, risk factors and mortality, and views around hospital admissions in their country. Responses were collected using multiple-choice questions. Results: The survey was completed by 26,272 general public respondents in 13 countries and 281 government and public sector policymakers in nine countries. While 99% of general public respondents had heard of HF, their understanding of the condition and its symptoms was poor, and only 6% identified that shortness of breath, fatigue, and leg swelling were the main symptoms of HF. Of policymaker respondents, 14% identified HF as the leading cause of avoidable hospitalisations, and only 4% recognised that ~ 87% of government spending on HF is related to hospitalisations. Conclusions: Major gaps were identified in the understanding of HF and the burden it places on patients and their caregivers, healthcare systems and society. This study confirms an ongoing need for national policy strategies and investment to raise awareness of the importance of HF prevention, early diagnosis, and implementation of effective treatments to reduce hospitalisations and death

    Homozygosity for a missense mutation in the 67 kDa isoform of glutamate decarboxylase in a family with autosomal recessive spastic cerebral palsy: parallels with Stiff-Person Syndrome and other movement disorders

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    Background Cerebral palsy (CP) is an heterogeneous group of neurological disorders of movement and/or posture, with an estimated incidence of 1 in 1000 live births. Non-progressive forms of symmetrical, spastic CP have been identified, which show a Mendelian autosomal recessive pattern of inheritance. We recently described the mapping of a recessive spastic CP locus to a 5 cM chromosomal region located at 2q24-31.1, in rare consanguineous families. Methods Here we present data that refine this locus to a 0.5 cM region, flanked by the microsatellite markers D2S2345 and D2S326. The minimal region contains the candidate gene GAD1, which encodes a glutamate decarboxylase isoform (GAD67), involved in conversion of the amino acid and excitatory neurotransmitter glutamate to the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Results A novel amino acid mis-sense mutation in GAD67 was detected, which segregated with CP in affected individuals. Conclusions This result is interesting because auto-antibodies to GAD67 and the more widely studied GAD65 homologue encoded by the GAD2 gene, are described in patients with Stiff-Person Syndrome (SPS), epilepsy, cerebellar ataxia and Batten disease. Further investigation seems merited of the possibility that variation in the GAD1 sequence, potentially affecting glutamate/GABA ratios, may underlie this form of spastic CP, given the presence of anti-GAD antibodies in SPS and the recognised excitotoxicity of glutamate in various contexts

    Can a “state of the art” chemistry transport model simulate Amazonian tropospheric chemistry?

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    We present an evaluation of a nested high-resolution Goddard Earth Observing System (GEOS)-Chem chemistry transport model simulation of tropospheric chemistry over tropical South America. The model has been constrained with two isoprene emission inventories: (1) the canopy-scale Model of Emissions of Gases and Aerosols from Nature (MEGAN) and (2) a leaf-scale algorithm coupled to the Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS) dynamic vegetation model, and the model has been run using two different chemical mechanisms that contain alternative treatments of isoprene photo-oxidation. Large differences of up to 100 Tg C yr^(−1) exist between the isoprene emissions predicted by each inventory, with MEGAN emissions generally higher. Based on our simulations we estimate that tropical South America (30–85°W, 14°N–25°S) contributes about 15–35% of total global isoprene emissions. We have quantified the model sensitivity to changes in isoprene emissions, chemistry, boundary layer mixing, and soil NO_x emissions using ground-based and airborne observations. We find GEOS-Chem has difficulty reproducing several observed chemical species; typically hydroxyl concentrations are underestimated, whilst mixing ratios of isoprene and its oxidation products are overestimated. The magnitude of model formaldehyde (HCHO) columns are most sensitive to the choice of chemical mechanism and isoprene emission inventory. We find GEOS-Chem exhibits a significant positive bias (10–100%) when compared with HCHO columns from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and Ozone Monitoring Instrument (OMI) for the study year 2006. Simulations that use the more detailed chemical mechanism and/or lowest isoprene emissions provide the best agreement to the satellite data, since they result in lower-HCHO columns

    The Hybrid Legal Geographies of a War Crimes Court

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    This paper explores the implications of understanding war crime trials as hybrid legal spaces. Drawing on twelve months of residential fieldwork in the Court of Bosnia and Herzegovina, Sarajevo, it examines the circulation of evidence, the choreography of the court room and the nature and possibilities for legal observation. Analyzing hybrid legal geographies foregrounds the material and embodied nature of trials, illuminating the forms of comportment, categorization and exclusion through which law establishes its legitimacy. Rather than emphasizing separation and distance, the lens of hybridity illuminates the multiple ways in which war crimes trials are grounded in the social and political context of present day Bosnia and Herzegovina. Consequently this analysis traces the disjuncture between the imagined geographies of legal jurisdiction and the material and embodied spaces of trial practices. In conclusion we argue that the establishment of the Court of Bosnia and Herzegovina illustrates the tensions that emerge when an institution of trial justice is used to strengthen the coherence of a post-conflict state.This paper is based on research funded by the Economic and Social Research Council (RES-061-25-0479).This is the accepted manuscript. The final version is available from http://www.tandfonline.com/doi/abs/10.1080/00045608.2014.892365

    ‘Re-reading Raphael Samuel: Politics, Personality and Performance’

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    For British historian Raphael Samuel, history and politics were inextricable. Best known as the founder of the history workshop movement, the controversial historian took his stance on the democratisation of history-making, becoming an outspoken advocate for public history. Despite making a significant contribution to contemporary historiography, he remains a neglected, even disparaged, figure. This paper contends that the most significant aspect of Samuel’s historical work was not one or other theory of history or argument about the past but his entire way of being an historian. Samuel embodied as much as expressed his ideas, consciously using his personality as a powerful political tool. It is further argued that conventional approaches to intellectual history, focusing on textual outputs, do not fully recognise the significance of performative modes of thinking. Theoretical approaches to performance as identity offer important insight here but can be too schematic in their view of applied and enacted thought. A biographical approach, by contrast, provides the intimate perspective necessary to fully appreciate the fluidity and complexity of such a personality. The paper first situates Samuel in the context of his earlier life, focusing on how and why he created such a public persona and how he adapted it in response to changing circumstances. It then considers the implications and effectiveness of this persona by assessing how it was perceived and narrated by others, acknowledging, in the process, why different groups engaged with and interpreted it differently
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