1,580 research outputs found

    Seasonal forecasting of groundwater levels in principal aquifers of the United Kingdom

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    To date, the majority of hydrological forecasting studies have focussed on using medium-range (3–15 days) weather forecasts to drive hydrological models and make predictions of future river flows. With recent developments in seasonal (1–3 months) weather forecast skill, such as those from the latest version of the UK Met Office global seasonal forecast system (GloSea5), there is now an opportunity to use similar methodologies to forecast groundwater levels in more slowly responding aquifers on seasonal timescales. This study uses seasonal rainfall forecasts and a lumped groundwater model to simulate groundwater levels at 21 locations in the United Kingdom up to three months into the future. The results indicate that the forecasts have skill; outperforming a persistence forecast and demonstrating reliability, resolution and discrimination. However, there is currently little to gain from using seasonal rainfall forecasts over using site climatology for this type of application. Furthermore, the forecasts are not able to capture extreme groundwater levels, primarily because of inadequacies in the driving rainfall forecasts. The findings also show that the origin of forecast skill, be it from the meteorological input, groundwater model or initial condition, is site specific and related to the groundwater response characteristics to rainfall and antecedent hydro-meteorological conditions

    EmoçÔes, “stress”, ansiedade e “coping": estudo qualitativo com treinadores de nĂ­vel internacional

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    A influĂȘncia dos fatores e processos psicolĂłgicos no desempenho desportivo dos atletas estĂĄ, de uma forma geral, amplamente demonstrada; todavia, poucas investigaçÔes procuraram estudar esta relação nos treinadores. Neste sentido, empregando uma entrevista semi-estruturada, a presente investigação procurou, junto de seis treinadores de elite com idades compreendidas entre os 55 e os 63 anos (M = 59 ± 3,03) de diversas modalidades, identificar as caracterĂ­sticas/competĂȘncias psicolĂłgicas mais importantes para o sucesso desportivo, as principais fontes de “stress” e ansiedade experienciadas e as estratĂ©gias de “coping” a que recorriam em situaçÔes estressantes e/ou problemĂĄticas, adicionalmente, pretendeu explorar o papel de outras emoçÔes no seu desempenho. Os resultados revelaram que: 1) a motivação era uma das competĂȘncias/caracterĂ­sticas psicolĂłgicas percepcionadas pelos treinadores como mais importantes para o sucesso; 2) as principais fontes de “stress” estavam relacionadas com preocupaçÔes com o desempenho dos atletas, sendo comuns a diferentes modalidades; 3) os treinadores recorriam a diversas estratĂ©gias de “coping” em simultĂąneo, geralmente adaptativas; e 4) para alĂ©m da ansiedade, outras emoçÔes, positivas e negativas, pareciam influenciar o desempenho dos treinadores.Fundação para a CiĂȘncia e Tecnologia (FCT

    Minimal model for aeolian sand dunes

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    We present a minimal model for the formation and migration of aeolian sand dunes. It combines a perturbative description of the turbulent wind velocity field above the dune with a continuum saltation model that allows for saturation transients in the sand flux. The latter are shown to provide the characteristic length scale. The model can explain the origin of important features of dunes, such as the formation of a slip face, the broken scale invariance, and the existence of a minimum dune size. It also predicts the longitudinal shape and aspect ratio of dunes and heaps, their migration velocity and shape relaxation dynamics. Although the minimal model employs non-local expressions for the wind shear stress as well as for the sand flux, it is simple enough to serve as a very efficient tool for analytical and numerical investigations and to open up the way to simulations of large scale desert topographies.Comment: 19 pages, 22 figure

    CARACTERIZAÇÃO DOS RESÍDUOS DAS INDÚSTRIAS CERÂMICAS ESTRUTURAIS DA REGIÃO DO CARIRI – CE

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    Existe uma grande preocupação por parte das indĂșstrias com a disposição dos resĂ­duos gerados ao longo do processo produtivo, e no setor de cerĂąmica estrutural nĂŁo Ă© diferente. O descarte desses resĂ­duos, de um modo geral, ocasiona um impacto ambiental negativo. Assim, o presente trabalho tem por objetivo analisar os resĂ­duos produzidos pelas indĂșstrias cerĂąmicas estruturais da regiĂŁo do Cariri – CE, para fins de reutilização. A caracterização dos resĂ­duos foi realizada antes e apĂłs queima para trĂȘs produtos distintos: lajota, tijolo de 8 furos e telha romana, por meio das tĂ©cnicas de difração de raios–X (DRX), Espectroscopia vibracional na regiĂŁo do infravermelho (IV), anĂĄlise tĂ©rmica diferencial (ATD), anĂĄlise tĂ©rmica gravimĂ©trica (ATG) e fluorescĂȘncia de raios-X. Com base nos resultados de DRX (apĂłs queima) pode-se concluir que as amostras sĂŁo resĂ­duos principalmente constituĂ­dos de quartzo (SiO2) em maior quantidade e feldspato e rutilo em menor quantidade, confirmados atravĂ©s dos espectros de infravermelho, assim como, Ă© possĂ­vel observar na fluorescĂȘncia de raios-X concentraçÔes mais altas de SiO2, a presença de Fe2O3 que caracteriza a cor avermelha nos resĂ­duos, alĂ©m de outros Ăłxidos como Al2O3, CaO, Na2O, K2Oe TiO2. Os resultados preliminaresmostram que os resĂ­duos estudados podem ser incorporados a uma matriz cerĂąmica

    Haloperidol and Ziprasidone for Treatment of Delirium in Critical Illness

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    BACKGROUND: There are conflicting data on the effects of antipsychotic medications on delirium in patients in the intensive care unit (ICU). METHODS: In a randomized, double-blind, placebo-controlled trial, we assigned patients with acute respiratory failure or shock and hypoactive or hyperactive delirium to receive intravenous boluses of haloperidol (maximum dose, 20 mg daily), ziprasidone (maximum dose, 40 mg daily), or placebo. The volume and dose of a trial drug or placebo was halved or doubled at 12-hour intervals on the basis of the presence or absence of delirium, as detected with the use of the Confusion Assessment Method for the ICU, and of side effects of the intervention. The primary end point was the number of days alive without delirium or coma during the 14-day intervention period. Secondary end points included 30-day and 90-day survival, time to freedom from mechanical ventilation, and time to ICU and hospital discharge. Safety end points included extrapyramidal symptoms and excessive sedation. RESULTS: Written informed consent was obtained from 1183 patients or their authorized representatives. Delirium developed in 566 patients (48%), of whom 89% had hypoactive delirium and 11% had hyperactive delirium. Of the 566 patients, 184 were randomly assigned to receive placebo, 192 to receive haloperidol, and 190 to receive ziprasidone. The median duration of exposure to a trial drug or placebo was 4 days (interquartile range, 3 to 7). The median number of days alive without delirium or coma was 8.5 (95% confidence interval [CI], 5.6 to 9.9) in the placebo group, 7.9 (95% CI, 4.4 to 9.6) in the haloperidol group, and 8.7 (95% CI, 5.9 to 10.0) in the ziprasidone group (P=0.26 for overall effect across trial groups). The use of haloperidol or ziprasidone, as compared with placebo, had no significant effect on the primary end point (odds ratios, 0.88 [95% CI, 0.64 to 1.21] and 1.04 [95% CI, 0.73 to 1.48], respectively). There were no significant between-group differences with respect to the secondary end points or the frequency of extrapyramidal symptoms. CONCLUSIONS: The use of haloperidol or ziprasidone, as compared with placebo, in patients with acute respiratory failure or shock and hypoactive or hyperactive delirium in the ICU did not significantly alter the duration of delirium. (Funded by the National Institutes of Health and the VA Geriatric Research Education and Clinical Center; MIND-USA ClinicalTrials.gov number, NCT01211522 .)

    Organic film thickness influence on the bias stress instability in Sexithiophene Field Effect Transistors

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    In this paper, the dynamics of bias stress phenomenon in Sexithiophene (T6) Field Effect Transistors (FETs) has been investigated. T6 FETs have been fabricated by vacuum depositing films with thickness from 10 nm to 130 nm on Si/SiO2 substrates. After the T6 film structural analysis by X-Ray diffraction and the FET electrical investigation focused on carrier mobility evaluation, bias stress instability parameters have been estimated and discussed in the context of existing models. By increasing the film thickness, a clear correlation between the stress parameters and the structural properties of the organic layer has been highlighted. Conversely, the mobility values result almost thickness independent

    Cold Plasma Dispersion Relations in the Vicinity of a Schwarzschild Black Hole Horizon

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    We apply the ADM 3+1 formalism to derive the general relativistic magnetohydrodynamic equations for cold plasma in spatially flat Schwarzschild metric. Respective perturbed equations are linearized for non-magnetized and magnetized plasmas both in non-rotating and rotating backgrounds. These are then Fourier analyzed and the corresponding dispersion relations are obtained. These relations are discussed for the existence of waves with positive angular frequency in the region near the horizon. Our results support the fact that no information can be extracted from the Schwarzschild black hole. It is concluded that negative phase velocity propagates in the rotating background whether the black hole is rotating or non-rotating.Comment: 27 pages, 11 figures accepted for publication in Gen. Relat. & Gravi

    What do young athletes implicitly understand about psychological skills?

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    One reason sport psychologists teach psychological skills is to enhance performance in sport; but the value of psychological skills for young athletes is questionable because of the qualitative and quantitative differences between children and adults in their understanding of abstract concepts such as mental skills. To teach these skills effectively to young athletes, sport psychologists need to appreciate what young athletes implicitly understand about such skills because maturational (e.g., cognitive, social) and environmental (e.g., coaches) factors can influence the progressive development of children and youth. In the present qualitative study, we explored young athletes’ (aged 10–15 years) understanding of four basic psychological skills: goal setting, mental imagery, self-talk, and relaxation. Young athletes (n = 118: 75 males and 43 females) completed an open-ended questionnaire to report their understanding of these four basic psychological skills. Compared with the older youth athletes, the younger youth athletes were less able to explain the meaning of each psychological skill. Goal setting and mental imagery were better understood than self-talk and relaxation. Based on these findings, sport psychologists should consider adapting interventions and psychoeducational programs to match young athletes’ age and developmental level

    The Hahn Quantum Variational Calculus

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    We introduce the Hahn quantum variational calculus. Necessary and sufficient optimality conditions for the basic, isoperimetric, and Hahn quantum Lagrange problems, are studied. We also show the validity of Leitmann's direct method for the Hahn quantum variational calculus, and give explicit solutions to some concrete problems. To illustrate the results, we provide several examples and discuss a quantum version of the well known Ramsey model of economics.Comment: Submitted: 3/March/2010; 4th revision: 9/June/2010; accepted: 18/June/2010; for publication in Journal of Optimization Theory and Application
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