2,387 research outputs found

    Universal Aspects of U(1)U(1) Gauge Field Localization on Branes in DD-dimensions

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    In this work, we study the general properties of the DD-vector field localization on (Dd1)(D-d-1)-brane with co-dimension dd. We consider a conformally flat metric with the warp factor depending only on the transverse extra dimensions. We employ the geometrical coupling mechanism and find an analytical solution for the U(1)U(1) gauge field valid for any warp factor. Using this solution we find that the only condition necessary for localization is that the bulk geometry is asymptotically AdS. Therefore, our solution has an universal validity for any warp factor and is independent of the particular model considered. We also show that the model has no tachyonic modes. Finally, we study the scalar components of the DD-vector field. As a general result, we show that if we consider the coupling with the tensor and the Ricci scalar in higher co-dimensions, there is an indication that both sectors will be localized. As a concrete example, the above techniques are applied for the intersecting brane model. We obtain that the branes introduce boundary conditions that fix all parameters of the model in such a way that both sectors, gauge and scalar fields, are confined.Comment: 26 pages, 5 figures, Accepted version for publication in JHE

    Relações de gênero e produção científica de pensadoras da Embrapa.

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    Analisar o perfil das pensadoras da Embrapa de modo a descrever em estudo exploratório as relações de gênero e a produção científica indexada de pensadoras (Pesquisadoras I, II, III) em agropecuária na Embrapa desde a sua criação (1973). Os objetivos específicos são: mapear os padrões de distribuição espacial das pensadoras na Embrapa em termos de profissões e regiões onde estão lotadas; verificar a concentração em campos de atuação das pensadoras da Embrapa e distribuição espacial entre as unidades da Embrapa; levantar a produção científica indexada das pensadoras da Embrapa; analisar a produção científica através de estudos de freqüência e fator de impacto; coletar depoimentos de pensadoras da Embrapa sobre aspectos principais de suas carreiras científicas; comparar os resultados obtidos com resultados de estudos exploratórios semelhantes

    Dynamical star-disk interaction in the young stellar system V354 Mon

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    The main goal of this work is to characterize the mass accretion and ejection processes of the classical T Tauri star V354 Mon, a member of the young stellar cluster NGC 2264. In March 2008, photometric and spectroscopic observations of V354 Mon were obtained simultaneously with the CoRoT satellite, the 60 cm telescope at the Observat\'orio Pico dos Dias (LNA - Brazil) equipped with a CCD camera and Johnson/Cousins BVRI filters, and the SOPHIE \'echelle spectrograph at the Observatoire de Haute-Provence (CNRS - France). The light curve of V354 Mon shows periodical minima (P = 5.26 +/- 0.50 days) that vary in depth and width at each rotational cycle. From the analysis of the photometric and spectroscopic data, it is possible to identify correlations between the emission line variability and the light-curve modulation of the young system, such as the occurrence of pronounced redshifted absorption in the H_alpha line at the epoch of minimum flux. This is evidence that during photometric minima we see the accretion funnel projected onto the stellar photosphere in our line of sight, implying that the hot spot coincides with the light-curve minima. We applied models of cold and hot spots and a model of occultation by circumstellar material to investigate the source of the observed photometric variations. We conclude that nonuniformly distributed material in the inner part of the circumstellar disk is the main cause of the photometric modulation, which does not exclude the presence of hot and cold spots at the stellar surface. It is believed that the distortion in the inner part of the disk is created by the dynamical interaction between the stellar magnetosphere, inclined with respect to the rotation axis, and the circumstellar disk, as also observed in the classical T Tauri star AA Tau and predicted by magnetohydrodynamical numerical simulations.Comment: Accepted by Astronomy and Astrophysic

    Causas de variação do peso de vacas da raça Canchim criadas em regime de pastagens.

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    O objetivo do trabalho foi estimar os efeitos de fatores genético e ambientais no peso de vacas da raça Canchim, criadas em regime de pastagens na EMBRAPA-UEPAE, São Carlos, SP

    Fatores que influenciam os pesos de bezerros Canchim ao nascimento e a desmama.

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    Foram analisados os pesos ao nascimento a desmama de 1.404 bezerros Canchim, filhos de touros e nascidos durante o período de 1971 a 1979. Os pesos a desmama foram ajustados para 270 dias pelo ganho médio diário do nascimento e pela regressão do peso observado em função da idade da desmama
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