12,859 research outputs found

    Constraining the evolution of the CMB temperature with SZ measurements from Planck data

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    The CMB temperature-redshift relation, T_CMB(z)=T_0(1+z), is a key prediction of the standard cosmology, but is violated in many non standard models. Constraining possible deviations to this law is an effective way to test the LambdaCDM paradigm and to search for hints of new physics. We have determined T_CMB(z), with a precision up to 3%, for a subsample (104 clusters) of the Planck SZ cluster catalog, at redshift in the range 0.01-- 0.94, using measurements of the spectrum of the Sunyaev Zel'dovich effect obtained from Planck temperature maps at frequencies from 70 to 353 GHz. The method adopted to provide individual determinations of T_CMB(z) at cluster redshift relies on the use of SZ intensity change, Delta I_SZ(nu), at different frequencies, and on a Monte-Carlo Markov Chain approach. By applying this method to the sample of 104 clusters, we limit possible deviations of the form T_CMB(z)=T_0(1+z)^(1-beta) to be beta= 0.022 +/- 0.018, at 1 sigma uncertainty, consistent with the prediction of the standard model. Combining these measurements with previously published results we get beta=0.016+/-0.012.Comment: submitted to JCAP, 21 pages, 8 figure

    Vorton Formation

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    In this paper we present the first analytic model for vorton formation. We start by deriving the microscopic string equations of motion in Witten's superconducting model, and show that in the relevant chiral limit these coincide with the ones obtained from the supersonic elastic models of Carter and Peter. We then numerically study a number of solutions of these equations of motion and thereby suggest criteria for deciding whether a given superconducting loop configuration can form a vorton. Finally, using a recently developed model for the evolution of currents in superconducting strings we conjecture, by comparison with these criteria, that string networks formed at the GUT phase transition should produce no vortons. On the other hand, a network formed at the electroweak scale can produce vortons accounting for up to 6% of the critical density. Some consequences of our results are discussed.Comment: 41 pages; color figures 3-6 not included, but available from authors. To appear in Phys. Rev.

    IAC 576 - cultivar de mandioca de mesa recomendada para Mato Grosso do Sul.

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    bitstream/item/24714/1/COT200380.pdfDocumento on-line

    Caracterização morfológica de híbridos interespecíficos de maracujazeiro (Passiflora spp.).

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    O presente trabalho teve como objetivo utilizar descritores morfológicos de 17 híbridos interespecíficos provenientes do cruzamento entre Passiflora edulis Sims e Passiflora cincinnatta Mast. Os parentais P. edulis (BGM330) e P. cincinnatta (BGM077), bem como os 21 híbridos resultantes deste cruzamento foram caracterizados com uso de 27 descritores qualitativos incluindo atributos relacionados à folha e flor, no período de abril a julho de 2011. As flores foram coletadas obedecendo-se o horário de abertura para cada acesso e, as medições foram obtidas com o auxílio de paquímetro.PDF. 083_11

    Análise econômica das propriedades de produção de leite.

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    O objetivo do estudo seria conhecer, em nlvel local, o polinhnio, principalmente suas limitações, e ajudar os produtores, que concordarem de participar do projeto, a superarem suas dificuldades

    Caracterização de híbridos interespecíficos de maracujazeiro por descritores morfológicos.

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    Espécies silvestres do gênero Passiflora têm apresentado ampla variabilidade morfológica e são fontes valiosas de genes para resistência às principais doenças do maracujazeiro. Tais características podem contribuir para o desenvolvimento de novos híbridos de maracujazeiro com atributos agronômicos desejáveis
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