4,192 research outputs found

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

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    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 X1Σ+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

    ^1S_0 pairing correlations in relativistic nuclear matter and the two-nucleon virtual state

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    We use the Gorkov formulation of the Dirac-Hartree-Fock-Bogoliubov approximation to nuclear pairing to study the ^1S_0 nucleon-nucleon correlations in nuclear matter. We find the short-range correlations of the ^1S_0 pairing fields to be almost identical to those of the two-nucleon virtual state. We obtain mutually consistent results for the pairing fields, using several different sets of effective interaction parameters, when we demand that each of these sets places the virtual-state pole at its physical location.Comment: 11 pages, 9 PostScript figures, RevTex, submitted to Phys. Rev.

    Measuring The Co2 Flux At The Air/water Interface In Lakes Using Flow Injection Analysis.

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    The carbon dioxide flux at the air/water interface in lakes was calculated after the determination of H2CO3* (free CO2) and atmospheric CO2 using flow injection analysis (FIA) coupled to a conductometric detector. The method is based on the diffusion of CO2 through a hydrophobic membrane into a flow of deionized water, generating a gradient of conductivity proportional to the concentration of CO2 in the sample. Using one experimental set-up, the speciation of the inorganic carbon (H2CO3* and dissolved inorganic carbon) was accomplished by simply adjusting the sample pH. The determination of CO2 in the atmosphere was carried out by direct injection of the gaseous samples. The FIA apparatus was taken into the field and CO2 fluxes were evaluated in several Brazilian lakes. In these lakes, representing different eutrophic stages, the CO2 flux varied from -242 (invasive) up to 3227 (evasive) mumol CO2 m-2 h-1.3317-2

    Caprinocultura e ovinocultura: crescimento promissor x desorganização preocupante.

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    Nematodes in horticulture: an overview.

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    Herein, we integrated information about the damage and losses caused by these pathogens in horticulture. Resistant genotypes seem to be the best alternative and, due to wide horticulture aspect, the focus is especially for life sustaining horticultural, such as banana, cassava, potato, and sugar beet. In addition, it was also provided evidence regarding how studies have been conducted on new strategies for resistance and control, such as the elucidation of effector?s functions. Nematode effectors studies, focus on the development of new resistant plant genotypes, is an auspicious strategy against this parasites
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