977 resultados para STRATIFIED FLUIDS


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Objetivo: Descrever métodos e resultados iniciais do Sistema de Vigilância de Fatores de Risco e Proteção para Doenças Crônicas ão Transmissíveis por Inquérito Telefônico - VIGITEL implantado no Brasil em 2006. Métodos: O VIGITEL estudou amostras probabilísticas da população com 18 ou mais anos de idade residente em domicílios conectados à rede de telefonia fixa de cada uma das capitais dos 26 Estados brasileiros e do Distrito Federal (54.369 indivíduos no total, sendo pelo menos 2.000 por cidade). A amostragem foi realizada a partir de cadastros eletrônicos completos das linhas residenciais fixas de cada cidade, envolvendo sorteio de linhas (domicílios) e sorteio de um morador por linha para ser entrevistado. O questionário aplicado investigou características demográficas e socioeconômicas, padrão de alimentação e de atividade física, consumo de cigarros e de bebidas alcoólicas, e peso e altura recordados, entre outros quesitos. Estimativas sobre a freqüência de fatores de risco selecionados, estratificadas por sexo e acompanhadas de Intervalo de Confiança de 95%, foram calculadas para a população adulta de cada cidade empregando-se fatores de ponderação que igualam a composição sociodemográfica da amostra em cada cidade àquela observada no Censo Demográfico de 2000. Estimativas para o conjunto das cidades empregam fator de ponderação adicional que leva em conta a população de adultos de cada cidade. Resultados: Os cinco fatores de risco selecionados (tabagismo, consumo abusivo de bebidas alcoólicas, excesso de peso, consumo de carnes com excesso de gordura e sedentarismo) tenderam a ser mais freqüentes em homens do que em mulheres. Dentre os fatores de proteção, o consumo regular de frutas e hortaliças foi mais freqüente em mulheres do que em homens, observando-se situação inversa no caso da atividade física de lazer. ) Diferenças substanciais na freqüência dos fatores de risco e proteção foram observadas entre as cidades, com padrões de distribuição regional diferenciados por fator.Discussão: O desempenho do sistema, avaliado a partir da qualidade dos cadastros telefônicos e de taxas de resposta e de recusas, mostrou-se adequado e, de modo geral, superior ao encontrado em sistemas equivalentes existentes em países desenvolvidos. O custo do sistema de R$ 31,15 por entrevista realizada, foi a metade do custo observado no sistema americano de vigilância de fatores de risco para doenças crônicas por inquérito telefônico e um quinto do custo estimado em inquérito domiciliar tradicional realizado recentemente no Brasil

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Determinar el impacto de las enfermedades crónicas y el número de enfermedades en los diversos aspectos de la calidad de vida relacionada con la salud (HRQOL) en adultos mayores de São Paulo, Brasil. MÉTODOS: Se empleó la encuesta de salud SF-36® para evaluar el impacto de las enfermedades crónicas de mayor prevalencia sobre la HRQOL. Se realizó un estudio poblacional transversal con un muestreo por conglomerados estratificado en dos etapas. Se obtuvieron los datos de una encuesta multicéntrica sobre la salud aplicada mediante entrevistas en hogares de varios municipios del estado de São Paulo. Se evaluaron siete enfermedades -artritis, dolor de espalda, depresión/ansiedad, diabetes, hipertensión arterial, osteoporosis y accidentes cerebrovasculares- y sus efectos sobre la calidad de vida. RESULTADOS: De los 1 958 adultos mayores de 60 años o más, 13,6% informaron no padecer ninguna de las enfermedades, mientras 45,7% presentaron tres enfermedades crónicas o más. La presencia de cualquiera de las siete enfermedades crónicas estudiadas influyó significativamente en la puntuación de casi todas las escalas de la SF-36®. La HRQOL alcanzó valores inferiores cuando la persona tenía depresión/ansiedad, osteoporosis o había sufrido un accidente cerebrovascular. A mayor número de enfermedades, mayores eran los efectos negativos en las dimensiones de la SF-36®. La presencia de tres enfermedades o más afectó significativamente la HRQOL en todas las áreas. Las escalas más afectadas por las enfermedades fueron dolor físico, salud general y vitalidad. CONCLUSIONES: Se encontró una alta prevalencia de enfermedades crónicas en la población de adultos mayores; la magnitud del efecto sobre la HRQOL dependió del tipo de enfermedad. Estos resultados destacan la importancia de prevenir y controlar las enfermedades crónicas para reducir la comorbilidad y disminuir su impacto sobre la HRQOL en los adultos mayores

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OBJETIVO: Analisar prevalências de inatividade física e fatores associados, e exercícios e esportes praticados segundo escolaridade em 2.050 adultos de 18 a 59 anos de idade - Estado de São Paulo, Brasil. MÉTODOS: Estudo transversal de base populacional com amostra estratificada e em múltiplos estágios. A inatividade física global foi aferida pelo International Physical Activity questionary - IPAQ short version, e por questão sobre prática regular de atividade física no lazer. A análise dos dados levou em conta o desenho amostral. RESULTADOS: A prevalência de inatividade física no lazer foi maior entre as mulheres. Já a inatividade física pelo IPAQ foi maior entre os homens. Modelos de regressão múltipla de Poisson indicaram, nos homens, menor inatividade física pelo IPAQ nos solteiros e separados, estudantes e aqueles que não possuíam carro. A inatividade física no lazer foi maior nos homens acima de 40 anos e com menor escolaridade ou apenas estudantes. A inatividade física pelo IPAQ, nas mulheres, foi mais prevalente entre as com maior escolaridade, ocupações menos qualificadas e viúvas; a inatividade física no lazer diminuiu com o aumento da idade e da escolaridade. Entre as modalidades praticadas no lazer, a caminhada foi a mais prevalente nas mulheres e o futebol nos homens. A maioria das modalidades foi diretamente associada à escolaridade; aproximadamente 25% dos indivíduos com mais de 12 anos de estudo praticava caminhada. CONCLUSÕES: Estes resultados sugerem que intervenções e políticas públicas de promoção da atividade física devem considerar diferenças socioeconômicas, de gênero, bem como as modalidades e o contexto em que a atividade física é praticadA

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The exact time-dependent solution for the stochastic equations governing the behavior of a binary self-regulating gene is presented. Using the generating function technique to rephrase the master equations in terms of partial differential equations, we show that the model is totally integrable and the analytical solutions are the celebrated confluent Heun functions. Self-regulation plays a major role in the control of gene expression, and it is remarkable that such a microscopic model is completely integrable in terms of well-known complex functions.

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A system of nearest neighbors Kuramoto-like coupled oscillators placed in a ring is studied above the critical synchronization transition. We find a richness of solutions when the coupling increases, which exists only within a solvability region (SR). We also find that the solutions possess different characteristics, depending on the section of the boundary of the SR where they appear. We study the birth of these solutions and how they evolve when the coupling strength increases, and determine the diagram of solutions in phase space.

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A generalized version of the nonequilibrium linear Glauber model with q states in d dimensions is introduced and analyzed. The model is fully symmetric, its dynamics being invariant under all permutations of the q states. Exact expressions for the two-time autocorrelation and response functions on a d-dimensional lattice are obtained. In the stationary regime, the fluctuation-dissipation theorem holds, while in the transient the aging is observed with the fluctuation-dissipation ratio leading to the value predicted for the linear Glauber model.

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Understanding the emergence of extreme opinions and in what kind of environment they might become less extreme is a central theme in our modern globalized society. A model combining continuous opinions and observed discrete actions (CODA) capable of addressing the important issue of measuring how extreme opinions might be has been recently proposed. In this paper I show extreme opinions to arise in a ubiquitous manner in the CODA model for a multitude of social network structures. Depending on network details reducing extremism seems to be possible. However, a large number of agents with extreme opinions is always observed. A significant decrease in the number of extremists can be observed by allowing agents to change their positions in the network.

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Plasma edge turbulence in Tokamak Chauffage Alfven Bresilien (TCABR) [R. M. O. Galvao et al., Plasma Phys. Contr. Fusion 43, 1181 (2001)] is investigated for multifractal properties of the fluctuating floating electrostatic potential measured by Langmuir probes. The multifractality in this signal is characterized by the full multifractal spectra determined by applying the wavelet transform modulus maxima. In this work, the dependence of the multifractal spectrum with the radial position is presented. The multifractality degree inside the plasma increases with the radial position reaching a maximum near the plasma edge and becoming almost constant in the scrape-off layer. Comparisons between these results with those obtained for random test time series with the same Hurst exponents and data length statistically confirm the reported multifractal behavior. Moreover, the persistence of these signals, characterized by their Hurst exponent, present radial profile similar to the deterministic component estimated from analysis based on dynamical recurrences. (C) 2008 American Institute of Physics.

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The possible states in the flow around two identical circular cylinders in tandem arrangements are investigated for configurations in the vicinity of the drag inversion separation. By means of numerical simulations, the hysteresis in the transition between the shedding regimes is studied and the relationship between (three-dimensional) secondary instabilities and shedding regime determination is addressed. The differences observed in the behavior of two- and three-dimensional flows are analyzed, and the regions of bistable flow are delimited. Very good agreement is found between the proposed scenario and results available in the literature. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3420111]

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In this work, we investigate the interplay between surface anchoring and finite-size effects on the smectic-isotropic transition in free-standing smectic films. Using an extended McMillan model, we study how a homeotropic anchoring stabilizes the smectic order above the bulk transition temperature. In particular, we determine how the transition temperature depends on the surface ordering and film thickness. We identify a characteristic anchoring for which the transition temperature does not depend on the film thickness. For strong surface ordering, we found that the thickness dependence of the transition temperature can be well represented by a power-law relation. The power-law exponent exhibits a weak dependence on the range of film thicknesses, as well as on the molecular alkyl tail length. Our results reproduce the main experimental findings concerning the layer-thinning transitions in free-standing smectic films.

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We report numerically and analytically estimated values for the Hurst exponent for a recently proposed non-Markovian walk characterized by amnestically induced persistence. These results are consistent with earlier studies showing that log-periodic oscillations arise only for large memory losses of the recent past. We also report numerical estimates of the Hurst exponent for non-Markovian walks with diluted memory. Finally, we study walks with a fractal memory of the past for a Thue-Morse and Fibonacci memory patterns. These results are interpreted and discussed in the context of the necessary and sufficient conditions for the central limit theorem to hold.

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We investigate a recently proposed non-Markovian random walk model characterized by loss of memories of the recent past and amnestically induced persistence. We report numerical and analytical results showing the complete phase diagram, consisting of four phases, for this system: (i) classical nonpersistence, (ii) classical persistence, (iii) log-periodic nonpersistence, and (iv) log-periodic persistence driven by negative feedback. The first two phases possess continuous scale invariance symmetry, however, log-periodicity breaks this symmetry. Instead, log-periodic motion satisfies discrete scale invariance symmetry, with complex rather than real fractal dimensions. We find for log-periodic persistence evidence not only of statistical but also of geometric self-similarity.

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Background: An evaluation of patients' preferences is necessary to understand the demand for different insulin delivery systems. The aim of this study was to investigate the association between socioeconomic status (SES) and patients' preferences and willingness to pay (WTP) for various attributes of insulin administration for diabetes management. Methods: We conducted a discrete choice experiment (DCE) to determine patients' preferences and their WTP for hypothetical insulin treatments. Both self-reported annual household income and education completed were used to explore differences in treatment preferences and WTP for different attributes of treatment across different levels of SES. Results: The DCE questionnaire was successfully completed by 274 patients. Overall, glucose control was the most valued attribute by all socioeconomic groups, while route of insulin delivery was not as important. Patients with higher incomes were willing to pay significantly more for better glucose control and to avoid adverse events compared to lower income groups. In addition, they were willing to pay more for an oral short-acting insulin ($Can 71.65 [95% confidence interval, $40.68, $102.62]) compared to the low income group ($Can 9.85 [95% confidence interval, 14.86, 34.56; P < 0.01]). Conversely, there were no differences in preferences when the sample was stratified by level of education. Conclusions: This study revealed that preferences and WTP for insulin therapy are influenced by income but not by level of education. Specifically, the higher the income, the greater desire for an oral insulin delivery system, whereas an inhaled route becomes less important for patients.

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Consider N sites randomly and uniformly distributed in a d-dimensional hypercube. A walker explores this disordered medium going to the nearest site, which has not been visited in the last mu (memory) steps. The walker trajectory is composed of a transient part and a periodic part (cycle). For one-dimensional systems, travelers can or cannot explore all available space, giving rise to a crossover between localized and extended regimes at the critical memory mu(1) = log(2) N. The deterministic rule can be softened to consider more realistic situations with the inclusion of a stochastic parameter T (temperature). In this case, the walker movement is driven by a probability density function parameterized by T and a cost function. The cost function increases as the distance between two sites and favors hops to closer sites. As the temperature increases, the walker can escape from cycles that are reminiscent of the deterministic nature and extend the exploration. Here, we report an analytical model and numerical studies of the influence of the temperature and the critical memory in the exploration of one-dimensional disordered systems.

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Consider a random medium consisting of N points randomly distributed so that there is no correlation among the distances separating them. This is the random link model, which is the high dimensionality limit (mean-field approximation) for the Euclidean random point structure. In the random link model, at discrete time steps, a walker moves to the nearest point, which has not been visited in the last mu steps (memory), producing a deterministic partially self-avoiding walk (the tourist walk). We have analytically obtained the distribution of the number n of points explored by the walker with memory mu=2, as well as the transient and period joint distribution. This result enables us to explain the abrupt change in the exploratory behavior between the cases mu=1 (memoryless walker, driven by extreme value statistics) and mu=2 (walker with memory, driven by combinatorial statistics). In the mu=1 case, the mean newly visited points in the thermodynamic limit (N >> 1) is just < n >=e=2.72... while in the mu=2 case, the mean number < n > of visited points grows proportionally to N(1/2). Also, this result allows us to establish an equivalence between the random link model with mu=2 and random map (uncorrelated back and forth distances) with mu=0 and the abrupt change between the probabilities for null transient time and subsequent ones.