980 resultados para PARAXIAL APPROXIMATION
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Dissertação de mestrado em Administração Pública (área de especialização em Gestão Pública)
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Dissertação de mestrado em Economia Industrial e da Empresa
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Tese de Doutoramento (Programa Doutoral em Engenharia Biomédica)
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The Symbolic Aggregate Approximation (iSAX) is widely used in time series data mining. Its popularity arises from the fact that it largely reduces time series size, it is symbolic, allows lower bounding and is space efficient. However, it requires setting two parameters: the symbolic length and alphabet size, which limits the applicability of the technique. The optimal parameter values are highly application dependent. Typically, they are either set to a fixed value or experimentally probed for the best configuration. In this work we propose an approach to automatically estimate iSAX’s parameters. The approach – AutoiSAX – not only discovers the best parameter setting for each time series in the database, but also finds the alphabet size for each iSAX symbol within the same word. It is based on simple and intuitive ideas from time series complexity and statistics. The technique can be smoothly embedded in existing data mining tasks as an efficient sub-routine. We analyze its impact in visualization interpretability, classification accuracy and motif mining. Our contribution aims to make iSAX a more general approach as it evolves towards a parameter-free method.
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Objetivo Identificar a preocupação com a forma do corpo de estudantes de Farmácia-Bioquímica e sua relação com variáveis sociais e laborais e com o estado nutricional. Métodos Participaram 346 discentes com média de idade de 20,2 (DP = 2,4) anos, sendo 278 (80,3%) do sexo feminino. Utilizou-se o Body Shape Questionnaire (BSQ). As validades fatorial e convergente e a consistência interna (α) do BSQ foram estimadas. Utilizaram-se como índices de ajustamento o qui-quadrado pelos graus de liberdade (χ2/gl), o Comparative Fit Index (CFI), o Normed Fit Index (NFI) e o Root Mean Square Error of Approximation (RMSEA). O escore médio de preocupação com a forma do corpo foi obtido por meio de algoritmo gerado na análise fatorial confirmatória. Para comparar os escores médios segundo as variáveis de interesse, utilizou-se Análise de Variância (ANOVA). Resultados O BSQ apresentou, para a amostra de estudo, adequada validade (χ2/gl = 3,29; CFI = 0,87, NFI = 0,82, RMSEA = 0,08) e confiabilidade (α = 0,97) após ajustamento. Verificou-se que as mulheres (p < 0,001) apresentaram maior preocupação com a forma do corpo que os homens. Além disso, os estudantes que avaliaram o curso como pior que as expectativas iniciais (p = 0,048), que consomem medicamentos por causa dos estudos (p < 0,001), que já pensaram em desistir do curso (p = 0,002) e foram classificados com sobrepeso/obesidade (p < 0,001) também apresentaram alta preocupação com a forma do corpo. Conclusão As varáveis sexo, avaliação em relação ao curso, ingestão de medicamentos por causa dos estudos, pensamento em desistir do curso e o estado nutricional apresentaram relação significativa com a preocupação com a forma do corpo entre os estudantes.
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The use of genome-scale metabolic models has been rapidly increasing in fields such as metabolic engineering. An important part of a metabolic model is the biomass equation since this reaction will ultimately determine the predictive capacity of the model in terms of essentiality and flux distributions. Thus, in order to obtain a reliable metabolic model the biomass precursors and their coefficients must be as precise as possible. Ideally, determination of the biomass composition would be performed experimentally, but when no experimental data are available this is established by approximation to closely related organisms. Computational methods however, can extract some information from the genome such as amino acid and nucleotide compositions. The main objectives of this study were to compare the biomass composition of several organisms and to evaluate how biomass precursor coefficients affected the predictability of several genome-scale metabolic models by comparing predictions with experimental data in literature. For that, the biomass macromolecular composition was experimentally determined and the amino acid composition was both experimentally and computationally estimated for several organisms. Sensitivity analysis studies were also performed with the Escherichia coli iAF1260 metabolic model concerning specific growth rates and flux distributions. The results obtained suggest that the macromolecular composition is conserved among related organisms. Contrasting, experimental data for amino acid composition seem to have no similarities for related organisms. It was also observed that the impact of macromolecular composition on specific growth rates and flux distributions is larger than the impact of amino acid composition, even when data from closely related organisms are used.
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Dissertação de mestrado em Direito Administrativo (área de especialização em Emprego Público)
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Dissertação de mestrado em Geologia (área de especialização em Valorização de Recursos Geológicos)
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The necessary information to distinguish a local inhomogeneous mass density field from its spatial average on a compact domain of the universe can be measured by relative information entropy. The Kullback-Leibler (KL) formula arises very naturally in this context, however, it provides a very complicated way to compute the mutual information between spatially separated but causally connected regions of the universe in a realistic, inhomogeneous model. To circumvent this issue, by considering a parametric extension of the KL measure, we develop a simple model to describe the mutual information which is entangled via the gravitational field equations. We show that the Tsallis relative entropy can be a good approximation in the case of small inhomogeneities, and for measuring the independent relative information inside the domain, we propose the R\'enyi relative entropy formula.
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Dissertação de mestrado integrado em Engenharia e Gestão Industrial
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La contaminación ambiental por metales pesados como el cromo y por compuestos orgánicos como los fenoles es un grave problema a nivel mundial debido a su toxicidad y a sus efectos adversos sobre los seres humanos, la flora y la fauna, tanto por su acumulación en la cadena alimentaria como por su continua persistencia en el medio ambiente. En un estudio preliminar, efectuado por nuestro laboratorio, se han detectado elevados niveles de estos contaminantes en sedimentos y efluentes en zonas industriales del sur de la provincia de Córdoba, lo cual plantea la necesidad de removerlos. Entre las tecnologías disponibles, la biorremediación, que se basa en el uso de sistemas biológicos, como los microorganismos, para la detoxificación y la degradación de contaminantes, se presenta como una alternativa probablemente más efectiva y de menor costo que las técnicas convencionales. Sin embargo, la aplicación de esta tecnología depende en gran parte de la influencia de las características particulares y específicas de la zona a remediar. En consecuencia, en primer lugar se caracterizará la zona de muestreo y se aislarán e identificarán microorganismos nativos de la región, tolerantes a cromo y fenol, a partir de muestras de suelo, agua y sedimentos, ya que podrían constituir una adecuada herramienta biotecnológica, mejor adaptada al sitio a tratar. Posteriormente se estudiará la biorremediación de Cr y fenol utilizando dichos microorganismos, analizando su capacidad para biotransformar, bioacumular o bioadsorber a estos contaminantes, y se determinarán las condiciones óptimas para el tratamiento. Se analizarán los posibles mecanismos fisiológicos, bioquímicos y moleculares involucrados en la remediación, que constituye una etapa crucial para el diseño de una estrategia adecuada y eficiente. Finalmente, se aplicará esta tecnología a escala reactor, como una primera aproximación al tratamiento a mayor escala. De esta manera se espera reducir los niveles de estos contaminantes y así minimizar el impacto ambiental que ellos producen en suelos y acuíferos. A futuro, la utilización de los microorganismos seleccionados, de manera individual o formando consorcios, para el tratamiento de efluentes industriales previa liberación al medio ambiente, o su uso en bioaumento, constituirían posibles alternativas de aplicación. Los principales impactos científico-tecnológicos del proyecto serán: (a) la generación de una nueva tecnología biológica de decontaminación de cromo y fenol, intentando presentar soluciones frente a una problemática ambiental que afecta a nuestra región, pero que además es común a la mayoría de los países, (b) la formación de nuevos recursos humanos en el área y (c) el trabajo en colaboración con otros grupos de investigación que se destacan en el área de biotecnología ambiental. Environmental pollution produced by heavy metals, such as chromium and organic compounds like phenolics is a serious global problem due to their toxicity, their adverse effects on human life, plants and animals, their accumulation in the food chains and also by their persistance in the environment. In a previous study performed in our laboratory, high levels of these pollutants were detected in sediments and effluents from industrial zones of the south of Cordoba Province, which determine the need to remove them. Among various technologies, bioremediation which is based on the use of biological systems, such as microorganisms, to detoxify and to degrade contaminants, is probably the most effective alternative, and it is less expensive than other conventional technologies. However, the application of this technology depends on the influence of the particular and specific characteristics of the zone to be remediate. As a consecuence, at the first time, the zone of sampling will be characterized and then, native microorganisms, tolerant to chromium and phenol, will be isolated from soils, water and sediments and identificated. These microorganisms would be an adequate biotechnological tool, more adapted to the conditions of the site to be remediate than other ones. Then, the ability of these selected microorganisms to biotransform, bioaccumulate or biosorbe chromium and phenol will be studied and the optimal conditions for the treatment will be determined. The possible physiological, biochemical and molecular mechanisms involved in bioremediation will be also analized, because this is a crucial step in the design of an adequate and efficient remediation strategy. Finally, this technology will be applied in a reactor, as an approximation to the treatment at a major scale. A reduction in the levels of these pollutants will be expected, to minimize their environmental impact on soils and aquifers.
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Magdeburg, Univ., Fak. für Mathematik, Diss., 2012
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Material law, crystal plasticity, cubic bodycentered crystals, bcc crystals, steel, pencil glide, texture, texture approximation, texture development, deep drawing, springback, simulation
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Spiral wave,feedback mechanism, photosensitive BZ reaction, excitable media, drift vetor field plot, planewave approximation, BZ, nonlinear
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Ziel der vorliegenden Arbeit war es, Möglichkeiten zur Approximation des Vermögensendwerts von Fonds-Sparplänen, wie sie typischerweise von Banken und Versicherungen angeboten werden, aufzuspüren und zu untersuchen. Von Interesse sind hierbei Approximationen für die Verteilungsfunktion, Quantile, gestutzte Erwartungswerte und Tail-Values-at-Risk. Die Modellierung der zu Grunde liegenden Wertpapierpreisprozesse erfolgt, wie üblich, als geometrische Brownsche Bewegung, wodurch der Vermögensendwert eines Wertpapiersparplans strukturell eine Summe lognormalverteilter Zufallsvariablen ist. Die Verteilung einer solchen Summe ist jedoch bekanntlich nicht explizit anzugeben; deren Simulation ist natürlich möglich, jedoch ob der Vielzahl von bei einer Bank oder Versicherung zu verwaltender Sparpläne unpraktikabel. Immer wieder stößt man auf Arbeiten, in denen darauf hingewiesen wird, dass die Summe von lognormalverteilten Zufallsvariablen gut durch eine eindimensional lognormalverteilte Zufallsvariable, in der Regel durch eine mit demselben Erwartungswert und derselben Varianz, approximiert würde. Dies konnte meist einzig und allein durch Simulationen und numerische Berechnungen gestützt werden. Wir präsentieren hier ein Resultat, welches eine Rechtfertigung für die genannte Approximation liefert: die Verteilungskonvergenz gegen eine Lognormalverteilung bei verschwindenden Varianzen/ Kovarianzen der Summanden ...