9,040 research outputs found

    The Paradox of Disconnected Coalitions

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    COALITION FORMATION; DYNAMIC ANALYSIS; SINGLE-PEAKEDNESS; LEGISLATURES; MILITARY ALLIANCES.

    Groundwater resource modelling for public water supply management in London

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    In London, groundwater abstractions for public supply are predominantly from the Chalk aquifer. However, water resource pressures put existing abstractions at risk and often require complex analysis to support new source development. Thames Water develops and uses regional groundwater models for such analysis to support communication with stakeholders such as the Environment Agency, the environmental regulator of England and Wales. Using two case studies, the importance of regional models as Thames Water assets is demonstrated. While Thames Water has developed regional models as a context for sub-catchment scale analysis of groundwater source development, they are subsequently used to address other issues. As a result, the models are updated regularly, enhancing both conceptual understanding and calibration. These models cost less than 1% of the capital cost of new water source schemes. However, as they are enhanced and applied more widely, the models accrue further value as active decision support tools. Regional model usage to investigate a range of local systems and interactions is of particular value to Thames Water. In this regard, it is important to appreciate and promote the clarity and consistency generated when stakeholder-specific issues can be analysed within an agreed regional model framework

    Evaluation of four global reanalysis products using in-situ observations in the Amundsen Sea Embayment, Antarctica

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    The glaciers within the Amundsen Sea Embayment (ASE), West Antarctica, are amongst the most rapidly retreating in Antarctica. Meteorological reanalysis products are widely used to help understand and simulate the processes causing this retreat. Here we provide an evaluation against observations of four of the latest global reanalysis products within the ASE region—the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-I), Japanese 55-year Reanalysis (JRA-55), Climate Forecast System Reanalysis (CFSR), and Modern Era Retrospective-Analysis for Research and Applications (MERRA). The observations comprise data from four automatic weather stations (AWSs), three research vessel cruises, and a new set of 38 radiosondes all within the period 2009–2014. All four reanalyses produce 2 m temperature fields that are colder than AWS observations, with the biases varying from approximately −1.8°C (ERA-I) to −6.8°C (MERRA). Over the Amundsen Sea, spatially averaged summertime biases are between −0.4°C (JRA-55) and −2.1°C (MERRA) with notably larger cold biases close to the continent (up to −6°C) in all reanalyses. All four reanalyses underestimate near-surface wind speed at high wind speeds (>15 m s−1) and exhibit dry biases and relatively large root-mean-square errors (RMSE) in specific humidity. A comparison to the radiosonde soundings shows that the cold, dry bias at the surface extends into the lower troposphere; here ERA-I and CFSR reanalyses provide the most accurate profiles. The reanalyses generally contain larger temperature and humidity biases, (and RMSE) when a temperature inversion is observed, and contain larger wind speed biases (~2 to 3 m s−1), when a low-level jet is observed

    Superfluid Spin-down, with Random Unpinning of the Vortices

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    The so-called ``creeping'' motion of the pinned vortices in a rotating superfluid involves ``random unpinning'' and ``vortex motion'' as two physically separate processes. We argue that such a creeping motion of the vortices need not be (biased) in the direction of an existing radial Magnus force, nor should a constant microscopic radial velocity be assigned to the vortex motion, in contradiction with the basic assumptions of the ``vortex creep'' model. We point out internal inconsistencies in the predictions of this model which arise due to this unjustified foundation that ignores the role of the actual torque on the superfluid. The proper spin-down rate of a pinned superfluid is then calculated and turns out to be much less than that suggested in the vortex creep model, hence being of even less observational significance for its possible application in explaining the post-glitch relaxations of the radio pulsars.Comment: To be published in J. Low Temp. Phys., Vol. 139, May 2005 [Eqs 11, 15-17 here, have been revised and, may be substituted for the corresponding ones in that paper

    The semileptonic decays of the B_c meson

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    We study the semileptonic transitions B_c to \eta_c, J/\psi, D, D^*, B, B^*, B_s, B_s^* in the framework of a relativistic constituent quark model. We use experimental data on leptonic J/\psi decay, lattice and QCD sum rule results on leptonic B_c decay, and on radiative \eta_c transitions to adjust the quark model parameters. We compute all form factors of the above semileptonic B_c-transitions and give predictions for various semileptonic B_c decay modes including their \tau-modes when they are kinematically accessible. The implications of heavy quark symmetry for the semileptonic decays are discussed and are shown to be manifest in our explicit relativistic quark model calculation. A comparison of our results with the results of other calculations is performed.Comment: 31 pages Latex (uses epsf, revtex). Section II expanded, typos corrected. This version will appear in Phys. Rev.

    Withdrawal from treatment as an outcome in the Isolde study of COPD

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    Objectives: To investigate the determinants of patient withdrawal from our study, and the effect of these withdrawals on the outcome of treatment with inhaled corticosteroids in patients with COPD. Design: A double-blind, placebo-controlled, randomized trial. Setting: Eighteen outpatient centers in the United Kingdom. Participants: Seven hundred fifty-one patients with stable COPD defined clinically as baseline postbronchodilator FEV1 > 0.8 L and < 85% predicted, FEV1/FVC ratio < 70%, and FEV1 change after albuterol < 10% of predicted. Intervention: Random assignment of either 500 micrograms bid of inhaled fluticasone propionate (FP)using a spacer device or an identical placebo inhaler. Treatment was continued for 3 years or until patients withdrew from follow-up. Measurements and results: Postbronchodilator FEV1 was measured on three occasions before randomization and every 3 months thereafter. Health status was assessed by the disease-specific St. George Respiratory Questionnaire (SGRQ) and the modified short-form 36 questionnaire (SF-36) at baseline and every 6 months. Three hundred thirty-nine patients withdrew, of whom 156 patients received FP. Prescription of frequent courses of oral prednisolone was the most common reason for withdrawing as specified in the protocol (69 patients in the FP group withdrew due to respiratory symptoms, compared with 93 patients in the placebo group). This explained the significantly greater dropout of placebo-treated patients that was most evident when FEV1 was < 50% predicted. Patients withdrawing had a significantly more rapid decline in health status, measured by both the SGRQ and the SF-36 (p < 0.001). Those withdrawing from the placebo group had a more rapid decline in FEV1 and more exacerbations than the FP-treated groups. Baseline FEV1 was lower in dropouts than in patients completing the study receiving placebo, but there was no difference between the respective groups receiving FP. Conclusions: Patients who withdrew from follow-up were those with the most rapidly deteriorating health status and lung function. Losing these patients from the final analysis can reduce the power of a study to achieve its primary end point

    Asymptotic Pad\'e Approximants and the SQCD β\beta-function

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    We present a prediction for the four loop β\beta-function for SQCD based on the method of Asymptotic Pad\'e Approximants.Comment: 8 pages, including 2 figures. Plain TeX. Uses Harvmac and eps

    Randomised controlled trial of homoeopathy versus placebo in perennial allergic rhinitis with overview of four trial series

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    OBJECTIVE: To test the hypothesis that homoeopathy is a placebo by examining its effect in patients with allergic rhinitis and so contest the evidence from three previous trials in this series. Design: Randomised, double blind, placebo controlled, parallel group, multicentre study. SETTING: Four general practices and a hospital ear, nose, and throat outpatient department. PARTICIPANTS: 51 patients with perennial allergic rhinitis. Intervention: Random assignment to an oral 30c homoeopathic preparation of principal inhalant allergen or to placebo. MAIN OUTCOME MEASURES: Changes from baseline in nasal inspiratory peak flow and symptom visual analogue scale score over third and fourth weeks after randomisation. RESULTS: Fifty patients completed the study. The homoeopathy group had a significant objective improvement in nasal airflow compared with the placebo group (mean difference 19.8 l/min, 95% confidence interval 10.4 to 29.1, P=0.0001). Both groups reported improvement in symptoms, with patients taking homoeopathy reporting more improvement in all but one of the centres, which had more patients with aggravations. On average no significant difference between the groups was seen on visual analogue scale scores. Initial aggravations of rhinitis symptoms were more common with homoeopathy than placebo (7 (30%) v 2 (7%), P=0.04). Addition of these results to those of three previous trials (n=253) showed a mean symptom reduction on visual analogue scores of 28% (10.9 mm) for homoeopathy compared with 3% (1.1 mm) for placebo (95% confidence interval 4.2 to 15.4, P=0.0007). CONCLUSION: The objective results reinforce earlier evidence that homoeopathic dilutions differ from placebo

    Psychological and emotional needs, assessment and support post-stroke: a multi-perspective qualitative study

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    Background: International stroke care guidelines recommend the routine assessment and management of psychological and emotional problems post-stroke. Understanding the experiences of those delivering and receiving these services is vital to improving the provision of psychological support post-stroke. Objectives: To explore patients’, carers’ and health professionals’ experiences of psychological need, assessment and support post-stroke whilst in hospital and immediately post-discharge. Methods: Participants were recruited from seven specialist stroke services in the North of England. Qualitative semi-structured interviews and focus groups were conducted with 31 stroke patients, 28 carers and 66 health professionals. The interviews were recorded and transcribed verbatim, and analysed using thematic analysis. Results: Two central themes emerged Minding the gap: psychological expertise, and Protective factors perceived to reduce the need for formal psychological support. The lack of psychological expertise amongst healthcare professionals working on stroke units was a source of frustration and resulted in other disciplines assuming the role of a psychologist without the required skills and training. Multiple stakeholders discussed the importance of protective factors, including downward social comparison, social support, peer support, communication and information provision, that were perceived to reduce the need for formal psychological support. Discussion: Stroke patients need better access to psychological support, including information, advice and peer or social support. More research is required to establish the effectiveness of alternative options to formal psychological suppor
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