Determination of the scattering length for Rb-Cs X1Σ+^{1}\Sigma ^{+} ground electronic state using a variational method

We performed the calculation of the scattering length for the elastic collision between the rubidium and cesium atoms. For this we applied a variational procedure based on the R-matrix theory for unbound states employing the finite element method (FEM) for expansion of the wave-function in terms of a finite set of local basis functions. The FEM presents as advantages the possibility of the development of a efficient matrix inversion algorithm which significantly reduces the computation time to calculate the R matrix. We also tested a potential energy curve with spectroscopic accuracy obtained before from a direct adjustment procedure of experimental data of the $X^{1}\Sigma^{+}$ state based on genetic algorithm. The quality of our result was evaluated by comparing them with several ones previously published at literature.Comment: 15 pages, 6 tables and 2 figure

Cosmic String in Scalar-Tensor Gravity

The gravitational properties of a local cosmic string in the framework of scalar-tensor gravity are examined. We find the metric in the weak-field approximation and we show that, contrary to the General Relativity case, the cosmic string in scalar-tensor gravitation exerces a force on non-relativistic, neutral test particle. This force is proportional to the derivative of the conformal factor $A^{2}(\phi)$ and it is always attractive. Moreover, this force could have played an important role at the Early Universe, although nowadays it can be neglegible. It is also shown that the angular separation $\delta\varphi$ remains unaltered for scalar-tensor cosmic strings.Comment: 15 pages, LATEX, no figure

Sistema de produção agrossilvipastorial para a região de caatinga - SAF: avaliação dos impactos econômicos, sociais e ambientais.

bitstream/CNPC-2010/23041/1/cot110.pd

Relativistic Green functions in a plane wave gravitational background

We consider a massive relativistic particle in the background of a gravitational plane wave. The corresponding Green functions for both spinless and spin 1/2 cases, previously computed by A. Barducci and R. Giachetti \cite{Barducci3}, are reobtained here by alternative methods, as for example, the Fock-Schwinger proper-time method and the algebraic method. In analogy to the electromagnetic case, we show that for a gravitational plane wave background a semiclassical approach is also sufficient to provide the exact result, though the lagrangian involved is far from being a quadratic one.Comment: Last paper by Professor Arvind Narayan Vaidya, 18 pages, no figure

Massive scalar field near a cosmic string

The $\zeta$ function of a massive scalar field near a cosmic string is computed and then employed to find the vacuum fluctuation of the field. The vacuum expectation value of the energy-momentum tensor is also computed using a point-splitting approach. The obtained results could be useful also for the case of self-interacting scalar fields and for the finite-temperature Rindler space theory.Comment: 15 pages, standard LaTeX, no figures. Reference [14] correcte

Effect of the begomovirus transmission efficiency for the predominance of tomato severe rugose virus (TOSRV) in tomatos crops.

Tomato severe rugose virus (ToSRV) and Tomato golden vein virus (TGVV) are bipartite begomoviruses, transmitted by whiteflies (Bemisia tabaci biotypeB), frequently found infecting tomato (Solanum lycopersicum) crops in Brazil. To more fully understand the interaction begomovirus/whitefly, as well as how occurrence of mixed infection may influence virus emergence and dominance in an infected plant, a study on begomovirus transmission was carried out focusing on the determination of transmission efficiency of two begomoviruses, ToSRV and TGVV, in single and double infection.Resumo 066

Sistema de produção agrossilvipastoril para a região da Caatinga - SAF: uma avaliação dos impactos econômicos, sociais e ambientais.

A região semiárida brasileira configura-se como um ambiente extremamente frágil onde a agricultura é desenvolvida às custas de desmatamento indiscriminado, queimadas e períodos de pousio inadequados. O sistema agroflorestal pecuário é considerado como uma alternativa viável de uso dos recursos naturais que, normalmente, causa pouca ou nenhuma degradação ao meio ambiente. Diversos estudos tratam da produtividade dos sistemas agroflorestais pecuários em relação aos sistemas tradicionais, porém pouco se conhece sobre seu retorno financeiro, fato que dificulta os produtores em suas tomadas de decisão no gerenciamento ou investimento nas atividades agropecuárias. Diante deste cenário este estudo objetiva fazer uma avaliação e análise dos impactos econômicos, sociais e ambientais do Sistema Agrossilvipastoril ? SAF. Para tanto, utilizam-se as metodologias do AMBITEC-Social e AMBITEC-Produção Animal, desenvolvidas pela Empresa Brasileira de Pesquisa Agropecuária (Embrapa). O principal impacto econômico oriundo da adoção do Sistema Agrossilvipastoril é o incremento de produtividade. Ainda, a adoção da tecnologia em análise gerou impactos sociais positivos com relação a todos os aspectos (assim como também em todos os indicadores) analisados. Os principais impactos desejáveis sobre o meio ambiente são a redução da área necessária para pastagens, menores perdas de biodiversidade e de corredores de fauna, recuperação de solos e ecossistemas degradados, redução de resíduos químicos no produto final e diminuição da necessidade de ração, volumoso e suplementos

Comparison of 120Sn(6He,6He)120Sn and 120Sn(alpha,alpha)120Sn elastic scattering and signatures of the 6He neutron halo in the optical potential

Cross sections of $^{120}$Sn($\alpha$,$\alpha$)$^{120}$Sn elastic scattering have been extracted from the $\alpha$ particle beam contamination of a recent $^{120}$Sn($^6$He,$^6$He)$^{120}$Sn experiment. Both reactions are analyzed using systematic double folding potentials in the real part and smoothly varying Woods-Saxon potentials in the imaginary part. The potential extracted from the $^{120}$Sn($^6$He,$^6$He)$^{120}$Sn data may be used as the basis for the construction of a simple global $^6$He optical potential. The comparison of the $^6$He and $\alpha$ data shows that the halo nature of the $^6$He nucleus leads to a clear signature in the reflexion coefficients $\eta_L$: the relevant angular momenta $L$ with $\eta_L \gg 0$ and $\eta_L \ll 1$ are shifted to larger $L$ with a broader distribution. This signature is not present in the $\alpha$ scattering data and can thus be used as a new criterion for the definition of a halo nucleus.Comment: 13 pages, 7 figures, accepted for publication in Phys. Rev.

Viveiro internacional de observação de arroz de sequeiro para América Latina - VIOAL-S/79.

bitstream/item/26073/1/pesqandamento20.pd