12,646 research outputs found

    Functional kernel estimators of conditional extreme quantiles

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    We address the estimation of "extreme" conditional quantiles i.e. when their order converges to one as the sample size increases. Conditions on the rate of convergence of their order to one are provided to obtain asymptotically Gaussian distributed kernel estimators. A Weissman-type estimator and kernel estimators of the conditional tail-index are derived, permitting to estimate extreme conditional quantiles of arbitrary order.Comment: arXiv admin note: text overlap with arXiv:1107.226

    Defects in the supersymmetric mKdV hierarchy via Backlund transformations

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    The integrability of the N=1{\cal N}=1 supersymmetric modified Korteweg de-Vries (smKdV) hierarchy in the presence of defects is investigated through the construction of its super B\"acklund transformation. The construction of such transformation is performed by using essentially two methods: the B\"acklund-defect matrix approach and the superfield approach. Firstly, we employ the defect matrix associated to the hierarchy which turns out to be the same for the supersymmetric sinh-Gordon (sshG) model. The method is general for all flows and as an example we derive explicitly the B\"acklund equations in components for the first few flows of the hierarchy, namely t3t_3 and t5t_5. Secondly, the supersymmetric extension of the B\"acklund transformation in the superspace formalism is constructed for those flows. Finally, this super B\"acklund transformation is employed to introduce type I defects for the supersymmetric mKdV hierarchy. Further integrability aspects by considering modified conserved quantities are derived from the defect matrix.Comment: 40 pages. Some comments and references added. Version accepted for publication in JHE

    Structural properties of crumpled cream layers

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    The cream layer is a complex heterogeneous material of biological origin which forms spontaneously at the air-milk interface. Here, it is studied the crumpling of a single cream layer packing under its own weight at room temperature in three-dimensional space. The structure obtained in these circumstances has low volume fraction and anomalous fractal dimensions. Direct means and noninvasive NMR imaging technique are used to investigate the internal and external structure of these systems.Comment: 9 pages, 4 figures, accepted in J. Phys. D: Appl. Phy

    Vertex Operators and Soliton Solutions of Affine Toda Model with U(2) Symmetry

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    The symmetry structure of non-abelian affine Toda model based on the coset SL(3)/SL(2)U(1)SL(3)/SL(2)\otimes U(1) is studied. It is shown that the model possess non-abelian Noether symmetry closing into a q-deformed SL(2)U(1)SL(2)\otimes U(1) algebra. Specific two vertex soliton solutions are constructed.Comment: 17 pages, latex, misprints corrected, version to appear in J.Phys

    Metodologias de índices para análise da sustentabilidade em bacias hidrográficas.

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    A manutenção da quantidade e qualidade dos recursos hídricos é um desafio a ser equacionado na atualidade, tendo em vista que este recurso é indispensável para diversas formas de vida na terra. Os Índices e os indicadores de sustentabilidade tem sido utilizados como importantes ferramentas no processo de planejamento e gestão dos recursos hídricos. Os índices/indicadores podem expressar a situação atual de uma bacia hidrográfica, em dados quantitativos, tornando a análise de uma situação, mensurável. Este trabalho teve como o objetivo analisar seis publicações científicas disponíveis em periódicos na web que utilizaram índices de sustentabilidade em bacias hidrográficas. O procedimento metodológico consiste em uma revisão bibliográfica, que analisa algumas metodologias com propostas de fornecer informações de modo a subsidiar a gestão dos recursos hídricos
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