Crescimento de Curatella americana e Mouriri elliptica no Pantanal Sul-mato-grossense.

Resumo

Crescimento de Licania minutiflora no Pantanal Sul-Matogrossense.

Resumo

On Exact Symmetries and Massless Vectors in Holographic Flows and other Flux Vacua

We analyze the isometries of Type IIB flux vacua based on the Papadopolous-Tseytlin ansatz and identify the related massless bulk vector fields. To this end we devise a general ansatz, valid in any flux compactification, for the fluctuations of the metric and p-forms that diagonalizes the coupled equations. We then illustrate the procedure in the simple case of holographic flows driven by the RR 3-form flux only. Specifically we study the fate of the isometries of the Maldacena-Nunez solution associated to wrapped D5-branes.Comment: 23 page

Grinding of AISI 4340 steel whith interrupted cutting by aluminum oxide grinding wheel

There has been a great advance in the grinding process by the development of dressing, lubri-refrigeration and other methods. Nevertheless, all of these advances were gained only for continuous cutting; in other words, the ground workpiece profile remains unchanged. Hence, it becomes necessary to study grinding process using intermittent cutting (grooved workpiece – discontinuous cutting), as little or no knowledge and studies have been developed for this purpose, since there is nothing found in formal literature, except for grooved grinding wheels. In this paper, grinding trials were performed using a conventional aluminum oxide grinding wheel, testing samples made of AISI 4340 steel quenched and tempered with 2, 6, and 12 grooves. The cylindrical plunge grinding was performed by rotating the workpiece on the grinding wheel. This plunge movement was made at three different speeds. From the obtained results, it can be observed that roughness tended to increase for testing the sample with the same number of grooves, as rotation speed increased. Roundness error also tended to increase as the speed rotation process got higher for testing sample with the same number of grooves. Grinding wheel wear enhanced as rotation speed and number of grooves increased. Power consumed by the grinding machine was inversely proportional to the number of grooves

Determination of selenium in bovine semen by ICP-MS using formic acid for sample preparation.

Determination of Se by inductively coupled plasma mass spectrometry (ICP-MS) can be difficult due to spectral interferences; however, these interferences can be eliminated by using collision-reaction interface (CRI) technology. A simple and fast procedure for determination of total Se concentration in bovine semen by ICP-MS after sample solubilization with diluted formic acid is here proposed. Formic acid caused an increase of up to 50% in selenium net signals and the maximum gain was obtained at 10% v v-1 formic acid solution. The optimized nebulizer gas flow rates were 1.05 and 0.95 L min-1, and radio frequency applied power were 1.3 and 1.4 kW without and with CRI, respectively. Microwave-assisted acid digestion was also implemented in the preparation of semen sample for comparison of results. No statistical differences between these sample preparation strategies at 95% confidence level (t-test) were observed for 76Se+ , 77Se+ , 78Se+ and 82Se+ without using CRI and 82Se+ with CRI

Determinação de minerais em amostras de músculo bovino e castanhas empregando ácido diluído e sistemas de alta pressão (HPA).

Em uma análise química, a amostra deve ser submetida a um tratamento adequado visando a sua preparação para a determinação dos analitos. Essa etapa de preparo de amostras é fundamental para que a quantificação seja precisa. No caso de amostras orgânicas ou biológicas é necessário transformar os elementos de interesse em formas inorgânicas simples. Comumente são utilizadas digestões empregando ácidos concentrados, seja em chapas de aquecimento, em blocos digestores, com radiação microondas, ou em sistemas de alta pressão. Araújo et al.1 propuseram o preparo de amostras com a decomposição de plantas empregando ácido diluído e radiação microondas. Nesse trabalho foi avaliada a possibilidade da utilização de ácidos diluídos na digestão de amostras complexas (músculo bovino e castanhas) empregando sistemas de alta pressão (HPA)

Detection strategies for scalar gravitational waves with interferometers and resonant spheres

We compute the response and the angular pattern function of an interferometer for a scalar component of gravitational radiation in Brans-Dicke theory. We examine the problem of detecting a stochastic background of scalar GWs and compute the scalar overlap reduction function in the correlation between an interferometer and the monopole mode of a resonant sphere. While the correlation between two interferometers is maximized taking them as close as possible, the interferometer-sphere correlation is maximized at a finite value of f*d, where `f' is the resonance frequency of the sphere and `d' the distance between the detectors. This defines an optimal resonance frequency of the sphere as a function of the distance. For the correlation between the Virgo interferometer located near Pisa and a sphere located in Frascati, near Rome, we find an optimal resonance frequency f=590 Hz. We also briefly discuss the difficulties in applying this analysis to the dilaton and moduli fields predicted by string theory.Comment: 26 pages, Latex, 4 Postscript figures. Various minor improvements, misprint in eqs. 42, 127, 138 corrected, references adde