3,018 research outputs found

    Dinâmica recente no espaço rural do município de Nossa Senhora da Glória/SE.

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    O objetivo desse artigo é analisar a dinâmica recente no espaço rural de um município do semi-árido sergipano, reconhecido pelo dinamismo da sua economia que gira em torno da produção e processamento do leite por agricultores familiares, a despeito da inexistência de políticas específicas e continuadas para esse fim. A área de pesquisa é o município de Nossa Senhora da Glória localizado no Alto Sertão sergipano. A metodologia privilegiou o contato com atores-chave através de entrevistas, observações de campo, caminhadas transversais para observação da paisagem, participação em reuniões e levantamento de dados secundários. Os principais resultados demonstram que o município de Glória contem na sua totalidade três unidades de desenvolvimento com dinâmicas particulares a depender das estratégias dos agricultores, acesso e qualidade dos recursos naturais e vinculação com os mercados (trabalho, produto e financeiro

    Evolution from BCS to BKT superfluidity in one-dimensional optical lattices

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    We analyze the finite temperature phase diagram of fermion mixtures in one-dimensional optical lattices as a function of interaction strength. At low temperatures, the system evolves from an anisotropic three-dimensional Bardeen-Cooper-Schrieffer (BCS) superfluid to an effectively two-dimensional Berezinskii-Kosterlitz-Thouless (BKT) superfluid as the interaction strength increases. We calculate the critical temperature as a function of interaction strength, and identify the region where the dimensional crossover occurs for a specified optical lattice potential. Finally, we show that the dominant vortex excitations near the critical temperature evolve from multiplane elliptical vortex loops in the three-dimensional regime to planar vortex-antivortex pairs in the two-dimensional regime, and we propose a detection scheme for these excitations.Comment: 4 pages with 2 figure

    Phase Fluctuations and Vortex Lattice Melting in Triplet Quasi-One-Dimensional Superconductors at High Magnetic Fields

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    Assuming that the order parameter corresponds to an equal spin triplet pairing symmetry state, we calculate the effect of phase fluctuations in quasi-one-dimensional superconductors at high magnetic fields applied along the y (b') axis. We show that phase fluctuations can destroy the theoretically predicted triplet reentrant superconducting state, and that they are responsible for melting the magnetic field induced Josephson vortex lattice above a magnetic field dependent melting temperature Tm.Comment: 4 pages (double column), 1 eps figur

    Counting States: A Combinatorial Analysis of SQM Fragmentation

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    The Strange Quark matter (SQM) hypothesis states that at extreme pressure and density conditions a new ground state of matter would arise, in which half of the \textit{down} quarks become strange quarks. If true, it would mean that at least the core of neutron stars is made of SQM. In this hypothesis, SQM would be released in the inter-stellar medium when two of these objects merge. It is estimated that 102M10^{-2} M\odot of SQM would be released this way. This matter will undergo a sequence of processes that should result in a fraction of the released SQM becoming heavy nuclei through \textit{r-process}. In this work we are interested in characterizing the fragmentation of SQM, with the novelty of keeping track of the \textit{quark configuration} of the fragmented matter. This is accomplished by developing a methodology to estimate the energy of each fragment as the sum of its \textit{constituent quarks}, the Coulomb interaction among the quarks and fragments' momenta. The determination of the fragmentation output is crucial to fully characterize the subsequent nucleosynthesis.Comment: 4 pages, 2 figures, 2 table

    Método para classificar bovinos resistentes à infecção por Babesia bovis.

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    Descreve a metodologia de desafio para a identificação de bovinos resistentes ou suscetíveis à primo-infecção por B. bovis para fins experimentais.bitstream/item/55805/1/CO65.pdfDsiponível no formato online

    Thermodynamically stable noncomposite vortices in mesoscopic two-gap superconductors

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    In mesoscopic two-gap superconductors with sizes of the order of the coherence length noncomposite vortices are found to be thermodynamically stable in a large domain of the THT - H phase diagram. In these phases the vortex cores of one condensate are spatially separated from the other condensate ones, and their respective distributions can adopt distinct symmetries. The appearance of these vortex phases is caused by a non-negligible effect of the boundary of the sample on the superconducting order parameter and represents therefore a genuine mesoscopic effect. For low values of interband Josephson coupling vortex patterns with L1L2L_1 \neq L_2 can arise in addition to the phases with L1=L2L_1 =L_2, where L1L_1 and L2L_2 are total vorticities in the two condensates. The calculations show that noncomposite vortices could be observed in thin mesoscopic samples of MgB2_{2}.Comment: 5 pages, 3 figures, to be published in Europhysics Letter

    A micromechanical constitutive model for ductile fracture: numerical treatment and calibration strategy

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    This contribution describes the numerical treatment and calibration strategy for a new micromechanical damage model, which employs two internal damage variables. The new micromechanical model is based on Gurson's theory incorporating the void volume fraction as one damage parameter and a shear mechanism, which was formulated considering geometrical and phenomenological aspects, as the second internal damage variable. The first and the second damage variables are coupled in the constitutive formulation in order to affect the hydrostatic stress and deviatoric stress contributions, respectively. Both internal damage variables are independent and, as a consequence, they also require independent nucleation mechanisms for each one in order to trigger the growth contribution. These mechanisms require the determination of material parameters that are obtained through two calibration points: one for high and the other for low stress triaxiality. This is in contrast to other damage models that typically require one calibration point. In the first part of this paper, theoretical aspects of the constitutive formulation are presented and discussed. Then, an implicit numerical integration algorithm is derived, based on the operator split methodology, together with a methodology to perform the calibration of all material parameters. In order to assess the performance of the new model, the “butterfly” specimen was used and the 1045 steel was employed under a wide range of stress triaxiality. The results obtained from the numerical simulations are presented such as: the evolution of both damage parameters, the evolution of the equivalent plastic strain, the reaction versus displacement curve and the contour of the effective damage parameter. From the comparison of the numerical results with experimental evidence, it will be highlighted that the present formulation is able to predict accurately the location of fracture onset and the level of the associated equivalent plastic strain at fracture
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