998 resultados para V-T EQUATION


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The new hexanuclear mixed-valence vanadium complex [V3O3(OEt)(ashz)(2)(mu-OEt)](2) (1) with an N,O-donor ligand is reported. It acts as a highly efficient catalyst toward alkane oxidations by aqueous H2O2. Remarkably, high turnover numbers up to 25000 with product yields of up to 27% (based on alkane) stand for one of the most active systems for such reactions.

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Retomo o tema do último artigo dedicado ao trabalho desenvolvido por Miguel Gouveia, formador em calcetaria portuguesa e artística. (...) Na Fajã dos Vimes, podemos apreciar outros pormenores interessantes em calçada, desde logo um bule de café, com cinco grãos 3D (figura 3). Miguel colocou em prática a sua veia criativa: "Este é o único sítio da Europa onde se produz café, divinal por sinal, muito melhor do que o normal. Por isso, o local merecia como homenagem um desenho único e original!" (...) Miguel é de opinião que "o cristianismo primitivo também se encontra representado nas festas açorianas em honra ao Divino Espírito Santo. Estas festividades estão relacionadas com o culto da rainha Santa Isabel e com o conhecido milagre das rosas, num apelo ao renascimento de uma época em que a vontade popular era determinante sobre a vontade da nobreza governante. Na Idade Média, a nobreza era representada pela coroa, o clero pela cruz e o povo pelo Espírito Santo; quando se coloca a pomba do Espírito Santo no topo da coroa significa precisamente que se reconhece a soberania da vontade popular relativamente à tomada de decisões sobre os destinos do território governado (figura 6)". (...)

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: In this work we derive an analytical solution given by Bessel series to the transient and one-dimensional (1D) bioheat transfer equation in a multi-layer region with spatially dependent heat sources. Each region represents an independent biological tissue characterized by temperature-invariant physiological parameters and a linearly temperature dependent metabolic heat generation. Moreover, 1D Cartesian, cylindrical or spherical coordinates are used to define the geometry and temperature boundary conditions of first, second and third kinds are assumed at the inner and outer surfaces. We present two examples of clinical applications for the developed solution. In the first one, we investigate two different heat source terms to simulate the heating in a tumor and its surrounding tissue, induced during a magnetic fluid hyperthermia technique used for cancer treatment. To obtain an accurate analytical solution, we determine the error associated with the truncated Bessel series that defines the transient solution. In the second application, we explore the potential of this model to study the effect of different environmental conditions in a multi-layered human head model (brain, bone and scalp). The convective heat transfer effect of a large blood vessel located inside the brain is also investigated. The results are further compared with a numerical solution obtained by the Finite Element Method and computed with COMSOL Multi-physics v4.1 (c). (c) 2013 Elsevier Ltd. All rights reserved.

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The aim of the present study was to test a hypothetical model to examine if dispositional optimism exerts a moderating or a mediating effect between personality traits and quality of life, in Portuguese patients with chronic diseases. A sample of 540 patients was recruited from central hospitals in various districts of Portugal. All patients completed self-reported questionnaires assessing socio-demographic and clinical variables, personality, dispositional optimism, and quality of life. Structural equation modeling (SEM) was used to analyze the moderating and mediating effects. Results suggest that dispositional optimism exerts a mediator rather than a moderator role between personality traits and quality of life, suggesting that “the expectation that good things will happen” contributes to a better general well-being and better mental functioning.

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Na qualidade de Diretora Regional das Comunidades, fomos responsável pela redação dos artigos e coordenação da página "Comunidades Açorianas no Mundo", integrada no jornal Mundo Português, servindo a mesma para a divulgação das atividades realizadas pela Direção Regional Das Comunidades do Governo dos Açores.

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Solution enthalpies of 1,4-dioxane have been obtained in 15 protic and aprotic solvents at 298.15 K. Breaking the overall process through the use of Solomonov's methodology the cavity term was calculated and interaction enthalpies (Delta H-int) were determined. Main factors involved in the interaction enthalpy have been identified and quantified using a QSPR approach based on the TAKA model equation. The relevant descriptors were found to be pi* and beta, which showed, respectively, exothermic and endothermic contributions. The magnitude of pi* coefficient points toward non-specific solute-solvent interactions playing a major role in the solution process. The positive value of the beta coefficient reflects the endothermic character of the solvents' hydrogen bond acceptor (HBA) basicity contribution, indicating that solvent molecules engaged in hydrogen bonding preferentially interact with each other rather than with 1,4-dioxane. (C) 2013 Elsevier B.V. All rights reserved.

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Contrastando com o importante legado dos mestres organistas portugueses dos séculos XVI e XVII, a música portuguesa para órgão pós-1700 parece quase inexistente (excluindo raros exemplos, como as quatro sonatas para órgão de Carlos Seixas). Seja devido à destruição causada pelo grande terramoto de Lisboa em 1755, ou a outras causas, a ausência de fontes é surpreendente, considerando os testemunhos de actividade musical durante aquele período. Este artigo lida com uma fonte até hoje relativamente ignorada: o manuscrito CLI/1-4 nº 7 da Biblioteca do Palácio Ducal de Vila Viçosa (Versos / Sobre o Canto Chão / Para Orgão / De Fr. Jeronimo da M.dre de DS.). Esta colecção de vinte versos para órgão de Jerónimo da Madre de Deus é, de longe, a maior obra portuguesa para órgão da primeira metade do século XVIII até hoje conhecida. Claramente pensadas para o órgão, estas curtas peças testemunham a transformação da escrita para tecla em Portugal durante o reinado de D. João V (nomeadamente através da absorção de influências italianas) e fornecem informações preciosas sobre o tipo de instrumento em que eram tocadas.

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We perform a comparison between the fractional iteration and decomposition methods applied to the wave equation on Cantor set. The operators are taken in the local sense. The results illustrate the significant features of the two methods which are both very effective and straightforward for solving the differential equations with local fractional derivative.

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This article addresses the problem of obtaining reduced complexity models of multi-reach water delivery canals that are suitable for robust and linear parameter varying (LPV) control design. In the first stage, by applying a method known from the literature, a finite dimensional rational transfer function of a priori defined order is obtained for each canal reach by linearizing the Saint-Venant equations. Then, by using block diagrams algebra, these different models are combined with linearized gate models in order to obtain the overall canal model. In what concerns the control design objectives, this approach has the advantages of providing a model with prescribed order and to quantify the high frequency uncertainty due to model approximation. A case study with a 3-reach canal is presented, and the resulting model is compared with experimental data. © 2014 IEEE.

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We prove existence, uniqueness, and stability of solutions of the prescribed curvature problem (u'/root 1 + u'(2))' = au - b/root 1 + u'(2) in [0, 1], u'(0) = u(1) = 0, for any given a > 0 and b > 0. We also develop a linear monotone iterative scheme for approximating the solution. This equation has been proposed as a model of the corneal shape in the recent paper (Okrasinski and Plociniczak in Nonlinear Anal., Real World Appl. 13:1498-1505, 2012), where a simplified version obtained by partial linearization has been investigated.

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The lignite-clays of Póvoa de Santarém dated as Upper «Vindobonian» (mammalian zone MN6), fielded abundant remains of animals and plants (spores, pollens, seeds, etc.). The forms identified are indicative of several environments. Plants, either aquatic or belonging to swampy areas are predominant (Nuphar sp., Sparganium sp., Stratiotes kaltennordheimensis, cf. Ranunculus sp.). There are also remains of plants characteristiques of a humid rather than a swampy soil such as Polypodiaceae, Myrica ceriferiformis, Toddalia maii, Spirematospermum wetzeleri. The genera Vitis and Ephedra, although rare, point fowards the existence of drier regions in the neighbourhood. The presence of polens such as Picea indicate the presence at some distance less warm upland forest areas.

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Teeth and astragali were used for a biometrical study concerning suids from V-a (upper Burdigalian) and V-b (Langhian) divisions from Lisbon's Miocene series. The Hyotherium (V-b) are identical to those from french localities, hence they all belong in the same species H. soemmeringi. Bunolistriodon populations from V-a and V-b are homogenous; no significant difference between them has been found, inspite of different geological age. Both may be ascribed to B. lockharti. No evolutive trend was detected. The presence of another form close to the north african B. massai could not be confirmed either. French localities' Bunolistriodon populations also seem homogenous and conspecific with those from Lisbon. Notwithstanding its essentially homogenous character, there can be distinguished two sets in both V-a and V-b populations according to M3 size; this remains to be explained, since the last molars are the most likely to show a broad range of variation and are not unequivocally related to sexual dimorphism. Classification of the rare Tayassuidae has been confirmed. All known taxa are shown (see tableau I).

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This article addresses the problem of obtaining reduced complexity models of multi-reach water delivery canals that are suitable for robust and linear parameter varying (LPV) control design. In the first stage, by applying a method known from the literature, a finite dimensional rational transfer function of a priori defined order is obtained for each canal reach by linearizing the Saint-Venant equations. Then, by using block diagrams algebra, these different models are combined with linearized gate models in order to obtain the overall canal model. In what concerns the control design objectives, this approach has the advantages of providing a model with prescribed order and to quantify the high frequency uncertainty due to model approximation. A case study with a 3-reach canal is presented, and the resulting model is compared with experimental data. © 2014 IEEE.

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Dissertação para obtenção do grau de Mestre em Música - Interpretação Artística