A canonical transformation and the tunneling probability for the birth of an asymptotically DeSitter universe with dust

In the present work, we study the quantum cosmology description of closed Friedmann-Robertson-Walker models in the presence of a positive cosmological constant and a generic perfect fluid. We work in the Schutz's variational formalism. If one uses the scale factor and its canonically conjugated momentum as the phase space variables that describe the geometrical sector of these models, one obtains Wheeler-DeWitt equations with operator ordering ambiguities. In order to avoid those ambiguities and simplify the quantum treatment of the models, we introduce new phase space variables. We explicitly demonstrate that the transformation leading from the old set of variables to the new one is canonical. In order to show that the above canonical transformations simplify the quantum treatment of those models, we consider a particular model where the perfect fluid is dust. We solve the Wheeler-DeWitt equation numerically using the Crank-Nicholson scheme and determine the time evolution of the initial wave function. Finally, we compare the results for the present model with the ones for another model where the only difference is the presence of a radiative perfect fluid, instead of dust.Comment: Revtex4, 18 pages, 2 EPS figure

Revisão da metodologia analítica de determinação do extrato seco de vinho.

bitstream/item/40094/1/bop002.pd

ERIC-PCR diferencia guaranazeiro cultivado de espécies afins (Paullinia spp).

O objetivo deste trabalho foi analisar o potencial dos primers ERIC-PCR para identificação da variação intra e interespecífica

Mais de 170 cultivares transgênicas são disponibilizadas no mercado de sementes do Brasil para a safra 2011/12.

bitstream/item/39191/1/mais-170.pd

A LOCAL DIFFERENTIAL QUADRATURE METHOD WITH VARIABLE SHAPE MULTIQUADRICS: TESTS ON POISSON EQUATION AND FLUID DYNAMICS USING CONSISTENT CLOUD REFINEMENTS

A meshless Local Differential Quadrature Method for solving partial differential equations is presented in this paper. It is based in a point cloud discretization and local supports. A basis set of Multiquadric functions is employed for determining the weight coefficients in derivative approximations. Tests with the Poisson equation are presented for verifying the converge behavior of the method in Clouds with Unstructured Generation (CUG’s). A consistent refinement procedure for varying the multiquadric shape parameter between local supports is proposed. The method is finally applied for solving the classical benchmark problem of natural convection in a square cavity. Satisfactory results were obtained in comparison with the reference literature

Thermodynamical properties of an ideal gas in a traversable wormhole

In this work, we analyze the thermodynamic properties of non--interacting particles under influence of the gravitational field of a traversable wormhole. In particular, we investigate how the thermodynamic quantities are affected by the Ellis wormhole geometry, considering three different regions to our study: asymptotically far, close to the throat, and at the throat. The thermodynamic quantities turn out to depend strongly on parameter that controls the wormhole throat radius. By varying it, there exist an expressive modification in the thermodynamic state quantities, exhibiting both usual matter and dark energy--like behaviors. Finally, the interactions are regarded to the energy density and it seems to indicate that it "cures" the dark energy--like features.Comment: 29 pages and 18 figure

Análise da acurácia das simulações do modelo BRAMS na Amazônia Ocidental.

O objetivo deste estudo é avaliar o modelo de previsão numérica do tempo BRAMS (Brazilian Regional Atmospheric Modelling System), a partir da comparação entre os valores preditos e os observados (dados do NCEP (National Center Environmental Prediction). Foram realizadas comparações entre os valores preditos e os observados através da raiz do erro quadrático médio (RMSE) para os prognósticos de precipitação de 24, 48, 72 e 96 hs, no período de novembro de 2008 a março de 2009. Os resultados mostraram que o modelo BRAMS teve uma performance melhor quando assimilado com dados do modelo global do NCEP

Avaliação de unidades de reciclagem e compostagem de resíduos sólidos urbanos do Estado de São Paulo.

Diante do exposto, o presente trabalho vem subsidiar a avaliação IQC aplicada nas URC's visando estabelecer um índice mais confiável e completo. O trabalho determina uma nova classificação das unidades pelo cruzamento de informações sobre a avaliação do IQC com as dos parâmetros analisados (valores fora do limite estabelecido).Edited by Claudio da Rocha Brito; Melany M. Ciampi. EHWC 2006