991 resultados para Jacobi polynomials
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A Thesis submitted for the co-tutelle degree of Doctor in Physics at Universidade Nova de Lisboa and Université Pierre et Marie Curie
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In this work we perform a comparison of two different numerical schemes for the solution of the time-fractional diffusion equation with variable diffusion coefficient and a nonlinear source term. The two methods are the implicit numerical scheme presented in [M.L. Morgado, M. Rebelo, Numerical approximation of distributed order reaction- diffusion equations, Journal of Computational and Applied Mathematics 275 (2015) 216-227] that is adapted to our type of equation, and a colocation method where Chebyshev polynomials are used to reduce the fractional differential equation to a system of ordinary differential equations
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Conformally flat spacetimes with an elastic stress energy tensor having diagonal trace-free anisotropic pressure are investigated using 1+3 formalism. The 1+3 Bianchi and Jacobi identities and Einstein field equations are written for a particular case with a conformal factor dependent on only one spatial coordinate. Solutions with non null anisotropic pressure are obtained.
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The authors studied the rainfall in Pesqueira (Pernambuco, Brasil) in a period of 48 years (1910 through 1957) by the method of orthogonal polynomials, degrees up to the fourth having been tried. None of them was significant, so that it seems that no trend is present. The mean observed was 679.00 mm., with standard error of the mean 205.5 mm., and a 30.3% coefficient of variation. The 95% level of probability would include annual rainfall from 263.9 up to 1094.1mm.
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This paper deals with the study by orthogonal polynomials of trends in the mean annual and mean monthly temperatures (in degrees Centigrade) in Campinas (State of São Paulo, Brasil), from 1890 up to 1956. Only 4 months were studied (January, April, July and October) taken as typical of their respective season. For the annual averages both linear and quadratic components were significant, the regression equation being y = 19.95 - 0.0219 x + 0.00057 x², where y is the temperature (in degrees Centigrade) and x is the number of years after 1889. Thus 1890 corresponds to x = 1, 1891, to x = 2, etc. The equation shows a minimum for the year 1908, with a calculated mean y = 19.74. The expected means by the regression equation are given below. Anual temperature means for Campinas (SP, Brasil) calculated by the regression equation Year Annual mean (Degrees Centigrade) 1890 19.93 1900 10.78 1908 19.74 (minimum) 1010 19.75 1920 19.82 1930 20.01 1940 20.32 1950 20.74 1956 21.05 The mean for 67 years was 20.08°C with standard error of the mean 0.08°G. For January the regression equation was y = 23.08 - 0.0661 x + 0.00122 x², with a minimum of 22.19°C for 1916. The average for 67 years was 22.70°C, with standard error 0.12°C. For April no component of regression was significant. The average was 20.42°C, with standard error 0.13°C. For July the regression equation was of first degree, y = 16.01 + 0.0140X. The average for 67 years was 16.49°C, with standard error of the mean 0.14°C. Finally, for October the regression equation was y = 20.55 - 0.0362x + 0.00078x², with a minimum of 20.13°C for 1912. The average was 20.52°C, with standard error of the mean equal to 0.14°C.
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Coletas quinzenais de ácaros de ramos do Pinheiro-do-Paraná, Araucária angustifolia, em Lages, Santa Catarina, revelaram a presença, durante um ano (Setembro de 1983 a Agosto de 1984) das espécies fitófagas Oligonychus urunguis (Jacobi) e Tydeus formosus (Cooreman) e de ácaros predadores da família Phytoseiidae, dos gêneros Amblyseius e Proprioseiopsis. Também ácaros oribatídeos foram coletados durante todo o ano. De ocorrência mais restrita foram obtidos ácaros das famílias Ascidae, Bdellidae, Cheyletidae e Acaridae. O método de coleta batendo-se o material vegetal sobre tela e bandeja revelou-se pouco mais eficiente do que o emprego do funil de Tullgren.
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O gênero Nersia Stål, 1862 abriga 11 espécies, das quais Nersia haedina Stål, 1862 e Nersia sertata (Jacobi, 1904) são encontradas no Rio Grande do Sul. Ambas espécies são caracterizadas e ilustradas. Caracteres da genitália de machos e fêmeas são descritos pela primeira vez. Novos registros para a Região Neotropical são fornecidos.
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Eriphosoma Melzer, 1922 é redefinido incluindo cinco espécies: E. bipartitum (Buquet, 1844) (espécie-tipo), E. barbiellinii Melzer, 1922, E. jacobi Fuchs, 1961 e duas espécies novas descritas do Brasil: E. marcela sp. nov. (Espírito Santo) e E. mermudes sp. nov. (Bahia e Minas Gerais). Nova combinação proposta: Erytrochiton sellatum (Buquet, 1844). Chave para as espécies de Eriphosoma é fornecida.
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Consider a Riemannian manifold equipped with an infinitesimal isometry. For this setup, a unified treatment is provided, solely in the language of Riemannian geometry, of techniques in reduction, linearization, and stability of relative equilibria. In particular, for mechanical control systems, an explicit characterization is given for the manner in which reduction by an infinitesimal isometry, and linearization along a controlled trajectory "commute." As part of the development, relationships are derived between the Jacobi equation of geodesic variation and concepts from reduction theory, such as the curvature of the mechanical connection and the effective potential. As an application of our techniques, fiber and base stability of relative equilibria are studied. The paper also serves as a tutorial of Riemannian geometric methods applicable in the intersection of mechanics and control theory.
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Elevated high-sensitivity C-reactive protein (hs-CRP) concentration is associated with an increased risk of cardiovascular disease but this association seems to be largely mediated via conventional cardiovascular risk factors. In particular, the association between hs-CRP and obesity has been extensively demonstrated and correlations are stronger in women than men. We used fractional polynomials-a method that allows flexible modeling of non linear relations-to investigate the dose/response mathematical relationship between hs-CRP and several indicators of adiposity in Caucasians (Switzerland) and Africans (Seychelles) surveyed in two population-based studies. This relationship was non-linear exhibiting a steeper slope for low levels of hs-CRP and a higher level in women. The observed sex difference in the relationship between hs-CRP and adiposity almost disappeared upon adjustment for leptin, suggesting that these sex differences might be partially mediated, by leptin. All these relationship were similar in Caucasians and Africans. This is the first report on a non-linear relation, stratified by gender, between hs-CRP and adiposity.
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In this paper we unify, simplify, and extend previous work on the evolutionary dynamics of symmetric N-player matrix games with two pure strategies. In such games, gains from switching strategies depend, in general, on how many other individuals in the group play a given strategy. As a consequence, the gain function determining the gradient of selection can be a polynomial of degree N-1. In order to deal with the intricacy of the resulting evolutionary dynamics, we make use of the theory of polynomials in Bernstein form. This theory implies a tight link between the sign pattern of the gains from switching on the one hand and the number and stability of the rest points of the replicator dynamics on the other hand. While this relationship is a general one, it is most informative if gains from switching have at most two sign changes, as is the case for most multi-player matrix games considered in the literature. We demonstrate that previous results for public goods games are easily recovered and extended using this observation. Further examples illustrate how focusing on the sign pattern of the gains from switching obviates the need for a more involved analysis.
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La malaltia cerebrovascular és una de les patologies més prevalents a Catalunya, motivant un gran nombre de consultes a urgències i una de les primeres causes de mortalitat i discapacitat en adults. L’objectiu d’aquest estudi descriptiu fou explorar les característiques dels pacients amb patologia neurovascular atesos a urgències de l’Hospital Vall d’Hebron entre 2001 i 2008 a través de diverses variables. En vuit anys, s’ha produit un canvi en el perfil d’aquests pacients, amb l’augment de la complexitat diagnòstico-terapèutica de l’atenció de l’ictus a urgències. Amb tot, observem una disminució de la necessitat d’ingrés, la mortalitat i l’estada mitja hospitalària.