985 research outputs found

    Propriedades quĆ­micas e farmacolĆ³gicas de mangiferina: um composto bioativo de manga (Mangifera indica L.)

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    IntroduĆ§Ć£o; Estrutura e propriedades quĆ­micas; Teores de mangiferina; Atividades farmacolĆ³gicas; Produtos baseados em mangiferina.bitstream/CPATSA-2009-09/40766/1/SDC218.pd

    Multilevel Preconditioning of Discontinuous-Galerkin Spectral Element Methods, Part I: Geometrically Conforming Meshes

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    This paper is concerned with the design, analysis and implementation of preconditioning concepts for spectral Discontinuous Galerkin discretizations of elliptic boundary value problems. While presently known techniques realize a growth of the condition numbers that is logarithmic in the polynomial degrees when all degrees are equal and quadratic otherwise, our main objective is to realize full robustness with respect to arbitrarily large locally varying polynomial degrees degrees, i.e., under mild grading constraints condition numbers stay uniformly bounded with respect to the mesh size and variable degrees. The conceptual foundation of the envisaged preconditioners is the auxiliary space method. The main conceptual ingredients that will be shown in this framework to yield "optimal" preconditioners in the above sense are Legendre-Gauss-Lobatto grids in connection with certain associated anisotropic nested dyadic grids as well as specially adapted wavelet preconditioners for the resulting low order auxiliary problems. Moreover, the preconditioners have a modular form that facilitates somewhat simplified partial realizations. One of the components can, for instance, be conveniently combined with domain decomposition, at the expense though of a logarithmic growth of condition numbers. Our analysis is complemented by quantitative experimental studies of the main components.Comment: 41 pages, 11 figures; Major revision: rearrangement of the contents for better readability, part on wavelet preconditioner adde

    A Polynomial Spectral Calculus for Analysis of DG Spectral Element Methods

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    We introduce a polynomial spectral calculus that follows from the summation by parts property of the Legendre-Gauss-Lobatto quadrature. We use the calculus to simplify the analysis of two multidimensional discontinuous Galerkin spectral element approximations

    Uncertainties of Synthetic Integrated Colors as Age Indicators

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    We investigate the uncertainties in the synthetic integrated colors of simple stellar populations. Three types of uncertainties are from the stellar models, the population synthesis techniques, and from the spectral libraries. Despite some skepticism, synthetic colors appear to be reliable age indicators when used for select age ranges. Rest-frame optical colors are good age indicators at ages 2 -- 7Gyr. At ages sufficiently large to produce hot HB stars, the UV-to-optical colors provide an alternative means for measuring ages. This UV technique may break the age-metallicity degeneracy because it separates old populations from young ones even in the lack of metallicity information. One can use such techniques on extragalactic globular clusters and perhaps even for high redshift galaxies that are passively evolving to study galaxy evolution history.Comment: 38 pages, 21 figures, LaTex, 2003, ApJ, 582 (Jan 1), in pres

    Damping of Electron Density Structures and Implications for Interstellar Scintillation

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    The forms of electron density structures in kinetic Alfven wave turbulence are studied in connection with scintillation. The focus is on small scales Lāˆ¼108āˆ’1010L \sim 10^8-10^{10} cm where the Kinetic Alfv\'en wave (KAW) regime is active in the interstellar medium. MHD turbulence converts to a KAW cascade, starting at 10 times the ion gyroradius and continuing to smaller scales. These scales are inferred to dominate scintillation in the theory of Boldyrev et al. From numerical solutions of a decaying kinetic Alfv\'en wave turbulence model, structure morphology reveals two types of localized structures, filaments and sheets, and shows that they arise in different regimes of resistive and diffusive damping. Minimal resistive damping yields localized current filaments that form out of Gaussian-distributed initial conditions. When resistive damping is large relative to diffusive damping, sheet-like structures form. In the filamentary regime, each filament is associated with a non-localized magnetic and density structure, circularly symmetric in cross section. Density and magnetic fields have Gaussian statistics (as inferred from Gaussian-valued kurtosis) while density gradients are strongly non-Gaussian, more so than current. This enhancement of non-Gaussian statistics in a derivative field is expected since gradient operations enhance small-scale fluctuations. The enhancement of density gradient kurtosis over current kurtosis is not obvious, yet it suggests that modest fluctuation levels in electron density may yield large scintillation events during pulsar signal propagation in the interstellar medium. In the sheet regime the same statistical observations hold, despite the absence of localized filamentary structures. Probability density functions are constructed from statistical ensembles in both regimes, showing clear formation of long, highly non-Gaussian tails

    Low magnetic Prandtl number dynamos with helical forcing

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    We present direct numerical simulations of dynamo action in a forced Roberts flow. The behavior of the dynamo is followed as the mechanical Reynolds number is increased, starting from the laminar case until a turbulent regime is reached. The critical magnetic Reynolds for dynamo action is found, and in the turbulent flow it is observed to be nearly independent on the magnetic Prandtl number in the range from 0.3 to 0.1. Also the dependence of this threshold with the amount of mechanical helicity in the flow is studied. For the different regimes found, the configuration of the magnetic and velocity fields in the saturated steady state are discussed.Comment: 9 pages, 14 figure

    A spectral method for elliptic equations: the Dirichlet problem

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    An elliptic partial differential equation Lu=f with a zero Dirichlet boundary condition is converted to an equivalent elliptic equation on the unit ball. A spectral Galerkin method is applied to the reformulated problem, using multivariate polynomials as the approximants. For a smooth boundary and smooth problem parameter functions, the method is proven to converge faster than any power of 1/n with n the degree of the approximate Galerkin solution. Examples in two and three variables are given as numerical illustrations. Empirically, the condition number of the associated linear system increases like O(N), with N the order of the linear system.Comment: This is latex with the standard article style, produced using Scientific Workplace in a portable format. The paper is 22 pages in length with 8 figure

    Aboriginal and Torres Strait Islander men and parenting: a scoping review

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    Aboriginal and Torres Strait Islander men rarely rate a mention within discussions of parenting unless framed in the negative, or as the cause of dysfunctional family life. Consequently, the roles and responsibilities of Aboriginal and Torres Strait Islander men within parenting have largely been neglected or ignored. This scoping review aimed to identify and describe Aboriginal and Torres Strait Islander parenting programs that focused on male parents. A comprehensive search was conducted of databases, PubMed and Informit ATSI health, to identify peer-review publications, while relevant websites were also searched for grey literature. The review identified eight programs that met the inclusion criteria. The review highlights the lack of rigorously researched and published literature on parenting programs that focus on Aboriginal and Torres Strait Islander male parents. The programs all reported positive outcomes and demonstrate that given the opportunity, Aboriginal and Torres Strait Islander male parents are ready and determined to fulfil their roles and responsibilities as parents to the best of their ability for the benefit of their families and communities. The provision of inclusive parenting programs and services will equip Aboriginal and Torres Strait Islander male parents to better support their families during these important times.Kootsy Canuto, Stephen G. Harfield, Karla J. Canuto A and Alex Brow

    Compostos clorados: aspectos gerais e sua utilizaĆ§Ć£o como agente sanitizante na agricultura, micropropagaĆ§Ć£o e pecuĆ”ria.

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    Compostos clorados; Modo de aĆ§Ć£o dos compostos clorados; Fatores que Influenciam no processo de desinfecĆ§Ć£o; Utilizando compostos clorados; Tipos de compostos clorados e sua utilizaĆ§Ć£o; Compostos clorados de origemHipoclorito de sĆ³dio; Aspectos negativos mais comuns da utilizaĆ§Ć£o de compostos clorados como agentes sanitizantes e como contornĆ”-los; UtilizaĆ§Ć£o de compostos clorados como agentes sanitizantes na agricultura; UtilizaĆ§Ć£o de compostos clorados como agentes sanitizantes na pecuĆ”ria; UtilizaĆ§Ć£o de compostos clorados como agentes sanitizantes na micropropagaĆ§Ć£o.bitstream/CPATSA/37828/1/SDC207.pd
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