34,457 research outputs found

    Forrageiras de verão.

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    Nitrogen use of a mixed tree crop plantation with a leguminous cover crop.

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    Study on two associated frut tree crops take up their N in comparison to a leguminous cover crop in an agroforestry system. Preliminar results showed the pueraria had the highest foliar N content followed by pupunha; cupuacu having less than the other two. One year after application, cupuacu took up more of the applied N in comparison to the total N uptake than pueraria and pupunha as seen from the high &15N values. The amount of 15N taken up in relation to dry matter equaled between the three species, since pueraria had a lot higher N contents. The other sampling dates showed the same tendency.bitstream/item/181065/1/ID-2600-2-45-52.pd

    Lorentz-violating effects in the Bose-Einstein condensation of an ideal bosonic gas

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    We have studied the effects of Lorentz-violation in the Bose-Einstein condensation (BEC) of an ideal boson gas, by assessing both the nonrelativistic and ultrarelativistic limits. Our model describes a massive complex scalar field coupled to a CPT-even and Lorentz-violating background. We irst analyze the nonrelativistic case, at this level by using experimental data, we obtain upper-bounds for some LIV parameters. In the sequel, we have constructed the partition function for the relativistic ideal boson gas which to be able of a consistent description requires the imposition of severe restrictions on some LIV coefficients. In both cases, we have demonstrated that the LIV contributions are contained in an overall factor, which multiplies almost all thermodynamical properties. An exception is the fraction of the condensed particles.Comment: 7 pages Latex2e. To be published in Modern Physics Letters

    An investigation relating to the design parameters of diaphragm mandrels

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    The aim of the present investigation was to establish the equations relating the deformations and the gripping pressure of diaphragm mandrels, as well as to simplify them, enabling their utilization by a designer. Diaphragm mandrels, to be used in lathe or finishing machining work, can be seen as revolution pieces constituted of an assemblage of elastic elements disposed around their revolution axis. The centering and gripping operations rely only on the elastic forces generated when those elements are elasticly deformed. The non-existence of metalic sliding parts distinguishes this type of mandrels from the usual types and assures an high degree of repeatability and accuracy during the machining operations. Four fundamental stages constitute the present work. Firstly, the preliminary design of the geometrical shape for the diaphragm mandrels has been developed in chapter 2. The second and third fundamental stages have been undertaken simultaneously. They are constituted of an theoretical and experimental analysis in view to obtain the equations earlier refered. This analysis has been undertaken firstly on two different types of Specimen, simulating the constituting elements of a diaphragm mandrel and finally on a third Specimen simulating an actual section of the mandrel. The first Specimen simulated the tapered parts of the mandrel, and the second type simulated the assemblage of those tapered parts and the holding part in between them. On pages 42, 71 and 126 are represented the first, the second and the third type of those Specimen, respectively. In chapter 3 is elaborated the theoretical analysis of the first type, in chapter 7 the second type and in chapter 11 the third type. Their experimental analysis is presented on chapter 4, 5 and 6 for the first type, on chapters 8, 9 and 10 for the second one and on the chapter 12, 13 and 14 for the third type. The theoretical analysis, based upon the energy method enabled the calculations of deformations, load forces and gripping pressure relationships, and from the experimental work the experimental values have been obtained and used to verify the accuracy of the theoretical analysis. Mechanical and electronic techniques have been used during the experiments and close correlation between the predicted results and the experimental ones have been obtained, this being stated in chapter 6, chapter 10 and chapter 14. Finally the third stage of this investigation has been related with the simplification of the theoretical expressions and their presentation in a tabled way providing their use by a designer to characterize the behaviour of a mandrel as well as to define its geometrical dimensions under a specific work situation, chapter 17 and 18

    Caracterização agronômica de novos genótipos de mamoeiro na Chapada do Apodi.

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    O mamoeiro (Carica papaya L.) possui expressiva importância econômica para o Brasil, destacando-se como segundo maior produtor mundial. Em 2012 o país produziu 1.517.696 toneladas de mamão (FAO, 2012). No Brasil o mamoeiro é cultivado na quase totalidade do seu território, merecendo destaque os estados da Bahia, Espirito Santo, Ceará e Rio Grande do Norte, que são responsáveis por 87,35% da produção nacional (IBGE, 2013)

    Constraining Elko Dark Matter at the LHC with Monophoton Events

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    A mass dimension one fermion, also known as Elko, constitutes a dark matter candidate which might interact with photons at the tree level in a specific fashion. In this work, we investigate the constraints imposed by unitarity and LHC data on this type of interactions using the search for new physics in monophoton events. We found that Elkos which can explain the dark matter relic abundance mainly through electromagnetic interactions are excluded at the 95\%CL by the 8 TeV LHC data for masses up to 1 TeV.Comment: 6 pages, 4 figure
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