7,674 research outputs found

    Existence of positive solutions of a superlinear boundary value problem with indefinite weight

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    We deal with the existence of positive solutions for a two-point boundary value problem associated with the nonlinear second order equation u+a(x)g(u)=0u''+a(x)g(u)=0. The weight a(x)a(x) is allowed to change its sign. We assume that the function g ⁣:[0,+[Rg\colon\mathopen{[}0,+\infty\mathclose{[}\to\mathbb{R} is continuous, g(0)=0g(0)=0 and satisfies suitable growth conditions, so as the case g(s)=spg(s)=s^{p}, with p>1p>1, is covered. In particular we suppose that g(s)/sg(s)/s is large near infinity, but we do not require that g(s)g(s) is non-negative in a neighborhood of zero. Using a topological approach based on the Leray-Schauder degree we obtain a result of existence of at least a positive solution that improves previous existence theorems.Comment: 12 pages, 4 PNG figure

    On "Ergodicity and Central Limit Theorem in Systems with Long-Range Interactions" by Figueiredo et al

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    In the present paper we refute the criticism advanced in a recent preprint by Figueiredo et al [1] about the possible application of the qq-generalized Central Limit Theorem (CLT) to a paradigmatic long-range-interacting many-body classical Hamiltonian system, the so-called Hamiltonian Mean Field (HMF) model. We exhibit that, contrary to what is claimed by these authors and in accordance with our previous results, qq-Gaussian-like curves are possible and real attractors for a certain class of initial conditions, namely the one which produces nontrivial longstanding quasi-stationary states before the arrival, only for finite size, to the thermal equilibrium.Comment: 2 pages, 2 figures. Short version of the paper, accepted for publication in Europhysics Letters, (2009) in pres

    Brazilian embryo industry in context: pitfalls, lessons, and expectations for the future.

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    Proceedings of the 31st Annual Meeting of the Brazilian Embryo Technology Society (SBTE); Cabo de Santo Agostinho, PE, Brazil, August 17th to 19th, 2017. Abstract

    Aspectos biológicos do parasitóide Campolus flavicincta (Ashmead) criados em lagartas de Spodoptera frugiperda (Smith).

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    Estudou-se em laboratorio, aspectos biologicos do parasitoide Campoletis flavicincta (Ashmead) utilizando como hospedeiro larvas de Spodoptera frugiperda (Smith). Dez casais recem-nascidos de C. flavicincta foram individualizados no interior de vidros transparentes, (9,5 cm de diametro x 22 cm de altura) cobertos com um tecido fino, com solucao acucarada enriquecida com acido ascorbico. Sob condicoes de temperatura de 25 +/_ 2oC, umidade relativa de 70 +/- 10% e fotofase de 12 horas, cada casal recebeu diariamente cerca de 50 lagartas de tres dias de idade da especie S. frugiperda. Apos cada periodo de parasitismo as larvas foram individualizadas em copos plasticos contendo dieta artificial. O ciclo biologico total do parasitoide foi de 19,3 dias, sendo de 12,1 dias o periodo de ovo-larva e 7,2 dias o periodo de pupa. O peso medio da pupas foi de 8,3mg. A longevidade dos adultos foi em media 29,3 dias para os machos e 23,3 para as femeas. O periodo de parasitismo foi de 25 dias, com uma media de 18 lagartas parasitadas por dia. Houve predominancia de machos, com uma razao sexual de 0,15
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