980 resultados para Nonstationary variance
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Dissertação apresentada ao Instituto Politécnico do Porto para obtenção do Grau de Mestre em Logística Orientada por: Prof. Dr. Pedro Godinho
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A biosensor for urea has been developed based on the observation that urea is a powerful active-site inhibitor of amidase, which catalyzes the hydrolysis of amides such as acetamide to produce ammonia and the corresponding organic acid. Cell-free extract from Pseudomonas aeruginosa was the source of amidase (acylamide hydrolase, EC 3.5.1.4) which was immobilized on a polyethersulfone membrane in the presence of glutaraldehyde; anion-selective electrode for ammonium ions was used for biosensor development. Analysis of variance was used for optimization of the biosensorresponse and showed that 30 mu L of cell-free extract containing 7.47 mg protein mL(-1), 2 mu L of glutaraldehyde (5%, v/v) and 10 mu L of gelatin (15%, w/v) exhibited the highest response. Optimization of other parameters showed that pH 7.2 and 30 min incubation time were optimum for incubation ofmembranes in urea. The biosensor exhibited a linear response in the range of 4.0-10.0 mu M urea, a detection limit of 2.0 mu M for urea, a response timeof 20 s, a sensitivity of 58.245 % per mu M urea and a storage stability of over 4 months. It was successfully used for quantification of urea in samples such as wine and milk; recovery experiments were carried out which revealed an average substrate recovery of 94.9%. The urea analogs hydroxyurea, methylurea and thiourea inhibited amidase activity by about 90%, 10% and 0%, respectively, compared with urea inhibition.
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DESIGN: A randomized controlled trial.OB JECTIVE: To investigate the immediate effects on pressure pain thresholds over latent trigger points (TrPs) in the masseter and temporalis muscles and active mouth opening following atlanto-occipital joint thrust manipulation or a soft tissue manual intervention targeted to the suboccipital muscles. BACKGROUND : Previous studies have described hypoalgesic effects of neck manipulative interventions over TrPs in the cervical musculature. There is a lack of studies analyzing these mechanisms over TrPs of muscles innervated by the trigeminal nerve. METHODS: One hundred twenty-two volunteers, 31 men and 91 women, between the ages of 18 and 30 years, with latent TrPs in the masseter muscle, were randomly divided into 3 groups: a manipulative group who received an atlanto-occipital joint thrust, a soft tissue group who received an inhibition technique over the suboccipital muscles, and a control group who did not receive an intervention. Pressure pain thresholds over latent TrPs in the masseter and temporalis muscles, and active mouth opening were assessed pretreatment and 2 minutes posttreatment by a blinded assessor. Mixed-model analyses of variance (ANOVA) were used to examine the effects of interventions on each outcome, with group as the between-subjects variable and time as the within-subjects variable. The primary analysis was the group-by-time interaction. RESULTS: The 2-by-3 mixed-model ANOVA revealed a significant group-by-time interaction for changes in pressure pain thresholds over masseter (P<.01) and temporalis (P =.003) muscle latent TrPs and also for active mouth opening (P<.001) in favor of the manipulative and soft tissue groups. Between-group effect sizes were small. CONCLUSIONS: The application of an atlanto-occipital thrust manipulation or soft tissue technique targeted to the suboccipital muscles led to an immediate increase in pressure pain thresholds over latent TrPs in the masseter and temporalis muscles and an increase in maximum active mouth opening. Nevertheless, the effects of both interventions were small and future studies are required to elucidate the clinical relevance of these changes. LEVEL OF EVIDENCE : Therapy, level 1b. J Orthop Sports Phys Ther 2010;40(5):310-317. doi:10.2519/jospt.2010.3257. KEYWORDSDS: cervical manipulation, muscle trigger points, neck, TMJ, upper cervical.
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This paper proposes a particle swarm optimization (PSO) approach to support electricity producers for multiperiod optimal contract allocation. The producer risk preference is stated by a utility function (U) expressing the tradeoff between the expectation and variance of the return. Variance estimation and expected return are based on a forecasted scenario interval determined by a price range forecasting model developed by the authors. A certain confidence level is associated to each forecasted scenario interval. The proposed model makes use of contracts with physical (spot and forward) and financial (options) settlement. PSO performance was evaluated by comparing it with a genetic algorithm-based approach. This model can be used by producers in deregulated electricity markets but can easily be adapted to load serving entities and retailers. Moreover, it can easily be adapted to the use of other type of contracts.
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O objectivo deste estudo é determinar as propriedades psicométricas da versão portuguesa do Stroke Aphasic Depression Questionnaire-21 (SADQ-21). Envolveu 120 sujeitos, 33 dos quais com afasia. Os resultados demonstraram que o SADQ-21 revela uma consistência interna muito elevada (α=0,87). A validade de construção identificou cinco domínios. A variância total explicada pelos factores foi elevada (65,85%). A correlação entre a medida de ouro e o SADQ-21 é estatisticamente significativa (p<0,05). Os indivíduos com afasia estão significativamente mais deprimidos que os sem afasia (p=0,0001). Conclui-se que o SADQ-21 é um instrumento adequado para a avaliação da sintomatologia depressiva em pessoas com afasia.
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This paper proposes a swarm intelligence long-term hedging tool to support electricity producers in competitive electricity markets. This tool investigates the long-term hedging opportunities available to electric power producers through the use of contracts with physical (spot and forward) and financial (options) settlement. To find the optimal portfolio the producer risk preference is stated by a utility function (U) expressing the trade-off between the expectation and the variance of the return. Variance estimation and the expected return are based on a forecasted scenario interval determined by a long-term price range forecast model, developed by the authors, whose explanation is outside the scope of this paper. The proposed tool makes use of Particle Swarm Optimization (PSO) and its performance has been evaluated by comparing it with a Genetic Algorithm (GA) based approach. To validate the risk management tool a case study, using real price historical data for mainland Spanish market, is presented to demonstrate the effectiveness of the proposed methodology.
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This paper addresses the optimal involvement in derivatives electricity markets of a power producer to hedge against the pool price volatility. To achieve this aim, a swarm intelligence meta-heuristic optimization technique for long-term risk management tool is proposed. This tool investigates the long-term opportunities for risk hedging available for electric power producers through the use of contracts with physical (spot and forward contracts) and financial (options contracts) settlement. The producer risk preference is formulated as a utility function (U) expressing the trade-off between the expectation and the variance of the return. Variance of return and the expectation are based on a forecasted scenario interval determined by a long-term price range forecasting model. This model also makes use of particle swarm optimization (PSO) to find the best parameters allow to achieve better forecasting results. On the other hand, the price estimation depends on load forecasting. This work also presents a regressive long-term load forecast model that make use of PSO to find the best parameters as well as in price estimation. The PSO technique performance has been evaluated by comparison with a Genetic Algorithm (GA) based approach. A case study is presented and the results are discussed taking into account the real price and load historical data from mainland Spanish electricity market demonstrating the effectiveness of the methodology handling this type of problems. Finally, conclusions are dully drawn.
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Mestrado em Contabilidade e Gestão das Instituições Financeiras
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A Insuficiência Cardíaca (IC), como uma doença crónica, tem vindo a ser alvo de análise devido ao seu impacto, não só a nível económico, mas também a nível da qualidade de vida (QV). Vários estudos demonstram que os doentes com IC apresentam um comprometimento da QV, em várias dimensões. OBJETIVO: Descrever a QV dos doentes com IC do Centro Hospitalar Tâmega e Sousa (CHTS). METODOLOGIA: O estudo é quantitativo, transversal, prospetivo e descritivo. Foi aplicado, entre janeiro a junho de 2012, o Euro Quality of Life Instrument-5D (EQ-5D) para avaliar o estado de saúde (ES) e o Kansas City Cardiomyopathy Questionnaire (KCCQ) para avaliar a QV de 326 doentes com IC, dos quais 226 seguidos na Consulta Externa (77,9% masculinos, idade média 67,5 ±11,6 anos, desvio padrão) e 100 na Clínica de IC (CIC) (73,0% masculinos, idade média 59,0 anos, desvio padrão ±12,7). Foi usada a estatística descritiva, teste t, qui quadrado e a análise da variância. RESULTADOS: Os doentes do género feminino, do grupo etário 75-100 anos, solteiros, divorciados, separados ou viúvos, que não sabem ler nem escrever, sem apoio dos amigos e sem condições económicas mínimas para o tratamento da IC apresentaram pior ES e QV. Os doentes submetidos à terapia de ressincronização cardíaca e às cirurgias valvular e de revascularização tiveram melhor QV. Os doentes com IC de etiologia isquémica e em classe III-IV da New York Heart Association apresentaram pior ES. Nestas classes e com fração de ejeção ≤35% os doentes tiveram pior QV. Os doentes da CIC evidenciaram melhor ES e QV. CONCLUSÕES: A QV dos doentes com IC do CHTS é influenciada pelos fatores pessoais, clínicos e pelo local de intervenção. É fundamental mensurar a QV, na prática clínica, para evidenciar a perceção do ES dos doentes e o impacto da IC na QV.
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Tese de Doutoramento, Matemática (Investigação Operacional), 23 de Setembro de 2006, Universidade dos Açores.
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Mestrado em Engenharia Química
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Dissertação de Mestrado, Gestão de Empresa (MBA), 16 de Julho de 2013, Universidade dos Açores.
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Dissertação de Mestrado, Gestão e Conservação da Natureza, 11 de Junho de 2014, Universidade dos Açores.
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Copyright: © 2014 Aranda et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)