6,005 research outputs found

    Asymptotic behavior in time periodic parabolic problems with unbounded coefficients

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    We study asymptotic behavior in a class of non-autonomous second order parabolic equations with time periodic unbounded coefficients in R×Rd\mathbb R\times \mathbb R^d. Our results generalize and improve asymptotic behavior results for Markov semigroups having an invariant measure. We also study spectral properties of the realization of the parabolic operator u↦A(t)u−utu\mapsto {\cal A}(t) u - u_t in suitable LpL^p spaces

    Hypercontractivity and asymptotic behaviour in nonautonomous Kolmogorov equations

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    We consider a class of nonautonomous second order parabolic equations with unbounded coefficients defined in I×RdI\times\R^d, where II is a right-halfline. We prove logarithmic Sobolev and Poincar\'e inequalities with respect to an associated evolution system of measures {μt:t∈I}\{\mu_t: t \in I\}, and we deduce hypercontractivity and asymptotic behaviour results for the evolution operator G(t,s)G(t,s)

    Kernel estimates for nonautonomous Kolmogorov equations

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    Using time dependent Lyapunov functions, we prove pointwise upper bounds for the heat kernels of some nonautonomous Kolmogorov operators with possibly unbounded drift and diffusion coefficients

    Cultivo da mandioca na Região Centro-Sul do Brasil.

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    Cultivo da mandioca na região Centro-Sul do Brasil; Cenário Mundial; Clima; Solos; Cultivares; Plantio; Tratos culturais; Doenças e métodos de controle; Pragas e métodos de controle; Normas gerais sobre o uso de agrotóxicos; Colheita; Custo de produção e preços.bitstream/item/65791/1/SP20046.pd

    First-Order Regular and Degenerate Identification Differential Problems

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    We are concerned with both regular and degenerate first-order identification problems related to systems of differential equations of weakly parabolic type in Banach spaces. Several applications to partial differential equations and systems will be given in a subsequent paper to show the fullness of our abstract results

    Accretion disk in the eclipsing binary AU Mon

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    We analyze the CoRoT and V-passband ground-based light curves of the interacting close binary AU Mon, assuming that there is a geometrically and optically thick accretion disk around the hotter and more massive star, as inferred from photometric and spectroscopic characteristics of the binary. Our model fits the observations very well and provides estimates for the orbital elements and physical parameters of the components and of the accretion disk.Comment: Accepted for publication in MNRA
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