3,692 research outputs found

    Subsídio metodológico à integração da gestão de recursos hídricos com a gestão territorial, considerando as políticas florestal, agrícola e municipal urbana

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    Na tentativa de apoiar a efetivação da gestão de recursos hídricos no Brasil, segundo a Lei 9433/1997, pesquisas vêm sendo desenvolvidas em contribuição à integração da gestão de recursos hídricos com a gestão municipal/territorial. Neste contexto, o presente estudo, dando continuidade a trabalho com metodologia desenvolvida para integração ente a política de recursos hídricos com a política urbana, buscou expandir a integração de instrumentos da gestão de recursos hídricos com outras políticas setoriais, fortemente incidentes em regiões rurais, através da adaptação de modelo conceitual. Tomando-se as políticas agrícola e florestal como exemplo daquelas fortemente atuantes em regiões rurais, e como referência procedimentos metodológicos de análise e agrupamento de, e avaliação de interface entre, instrumentos de gestão de políticas, as principais etapas que compreenderam o desenvolvimento do trabalho foram: 1- identificação, análise e agrupamento de instrumentos de gestão das políticas agrícola e florestal; e 2- avaliação das inter-relações entre grupos de instrumentos de gestão de recursos hídricos com grupos de instrumentos de gestão agrícola, florestal e urbana. O desenvolvimento de extensiva pesquisa bibliográfica e documental foi de grande relevância em suporte à realização de todas as fases da pesquisa. Entre as principais conclusões do trabalho destaca-se: a adaptação do Modelo Conceitual para a integração entre a política de recursos hídricos e a política urbana mostrou-se promissor no que se refere à identificação de possibilidades de integração de grupos de instrumentos de gestão de recursos hídricos com grupos de instrumentos de gestão de outras políticas setoriais (uma ou mais) incidentes em regiões urbana e/ou rurais), avaliadas individualmente ou em conjunto, com base na afinidade entre as finalidades de tais grupos. Por fim, são feitas algumas recomendações para o desenvolvimento de futuros estudos

    Chirikov Diffusion in the Asteroidal Three-Body Resonance (5,-2,-2)

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    The theory of diffusion in many-dimensional Hamiltonian system is applied to asteroidal dynamics. The general formulations developed by Chirikov is applied to the Nesvorn\'{y}-Morbidelli analytic model of three-body (three-orbit) mean-motion resonances (Jupiter-Saturn-asteroid system). In particular, we investigate the diffusion \emph{along} and \emph{across} the separatrices of the (5,-2,-2) resonance of the (490) Veritas asteroidal family and their relationship to diffusion in semi-major axis and eccentricity. The estimations of diffusion were obtained using the Melnikov integral, a Hadjidemetriou-type sympletic map and numerical integrations for times up to 10810^{8} years.Comment: 27 pages, 6 figure

    A new analysis of the GJ581 extrasolar planetary system

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    We have done a new analysis of the available observations for the GJ581 exoplanetary system. Today this system is controversial due to choices that can be done in the orbital determination. The main ones are the ocurrence of aliases and the additional bodies - the planets f and g - announced in Vogt et al. 2010. Any dynamical study of exoplanets requires the good knowledge of the orbital elements and the investigations involving the planet g are particularly interesting, since this body would lie in the Habitable Zone (HZ) of the star GJ581. This region,for this system, is very attractive of the dynamical point of view due to several resonances of two and three bodies present there. In this work, we investigate the conditions under which the planet g may exist. We stress the fact that the planet g is intimately related with the orbital elements of the planet d; more precisely, we conclude that it is not possible to disconnect its existence from the determination of the eccentricity of the planet d. Concerning the planet f, we have found one solution with period 450\approx 450 days, but we are judicious about any affirmation concernig this body because its signal is in the threshold of detection and the high period is in a spectral region where the ocorruence of aliases is very common. Besides, we outline some dynamical features of the habitable zone with the dynamical map and point out the role played by some resonances laying there.Comment: 12 pages, 9 figure

    On the dynamics of Extrasolar Planetary Systems under dissipation. Migration of planets

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    We study the dynamics of planetary systems with two planets moving in the same plane, when frictional forces act on the two planets, in addition to the gravitational forces. The model of the general three-body problem is used. Different laws of friction are considered. The topology of the phase space is essential in understanding the evolution of the system. The topology is determined by the families of stable and unstable periodic orbits, both symmetric and non symmetric. It is along the stable families, or close to them, that the planets migrate when dissipative forces act. At the critical points where the stability along the family changes, there is a bifurcation of a new family of stable periodic orbits and the migration process changes route and follows the new stable family up to large eccentricities or to a chaotic region. We consider both resonant and non resonant planetary systems. The 2/1, 3/1 and 3/2 resonances are studied. The migration to larger or smaller eccentricities depends on the particular law of friction. Also, in some cases the semimajor axes increase and in other cases they are stabilized. For particular laws of friction and for special values of the parameters of the frictional forces, it is possible to have partially stationary solutions, where the eccentricities and the semimajor axes are fixed.Comment: Accepted in Celestial Mechanics and Dynamical Astronom

    On the connection between the Nekhoroshev theorem and Arnold Diffusion

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    The analytical techniques of the Nekhoroshev theorem are used to provide estimates on the coefficient of Arnold diffusion along a particular resonance in the Hamiltonian model of Froeschl\'{e} et al. (2000). A resonant normal form is constructed by a computer program and the size of its remainder Ropt||R_{opt}|| at the optimal order of normalization is calculated as a function of the small parameter ϵ\epsilon. We find that the diffusion coefficient scales as DRopt3D\propto||R_{opt}||^3, while the size of the optimal remainder scales as Roptexp(1/ϵ0.21)||R_{opt}|| \propto\exp(1/\epsilon^{0.21}) in the range 104ϵ10210^{-4}\leq\epsilon \leq 10^{-2}. A comparison is made with the numerical results of Lega et al. (2003) in the same model.Comment: Accepted in Celestial Mechanics and Dynamical Astronom

    Dynamic scaling in the vicinity of the Luttinger liquid fixed point

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    We calculate the single-particle spectral function A (k, omega) of a one-dimensional Luttinger liquid by means of a functional renormalization group (RG) approach. Given an infrared energy cutoff Lambda = Lambda_0 e^{- l}, our approach yields the spectral function in the scaling form, A_{\Lambda} (k_F + p, omega) = tau Z_l tilde{A}_l (p xi, omega tau), where k_F is the Fermi momentum, Z_l is the wave-function renormalization factor, tau = 1 / \Lambda is the time scale and xi = v_F / \Lambda is the length scale associated with Lambda. At the Luttinger liquid fixed point (l rightarrow infty) our RG result for A (k, omega) exhibits the correct anomalous scaling properties, and for k = \pm k_F agrees exactly with the well-known bosonization result at weak coupling. Our calculation demonstrates that the field rescaling is essential for obtaining the crossover from Fermi liquid behavior to Luttinger liquid behavior from a truncation of the hierarchy of exact RG flow equations as the infrared cutoff is reduced.Comment: 15 pages, 5 figure

    Exact integral equation for the renormalized Fermi surface

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    The true Fermi surface of a fermionic many-body system can be viewed as a fixed point manifold of the renormalization group (RG). Within the framework of the exact functional RG we show that the fixed point condition implies an exact integral equation for the counterterm which is needed for a self-consistent calculation of the Fermi surface. In the simplest approximation, our integral equation reduces to the self-consistent Hartree-Fock equation for the counterterm.Comment: 5 pages, 1 figur

    Resonances of low orders in the planetary system of HD37124

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    The full set of published radial velocity data (52 measurements from Keck + 58 ones from ELODIE + 17 ones from CORALIE) for the star HD37124 is analysed. Two families of dynamically stable high-eccentricity orbital solutions for the planetary system are found. In the first one, the outer planets c and d are trapped in the 2/1 mean-motion resonance. The second family of solutions corresponds to the 5/2 mean-motion resonance between these planets. In both families, the planets are locked in (or close to) an apsidal corotation resonance. In the case of the 2/1 MMR, it is an asymmetric apsidal corotation (with the difference between the longitudes of periastra Δω60\Delta\omega\sim 60^\circ), whereas in the case of the 5/2 MMR it is a symmetric antialigned one (Δω=180\Delta\omega = 180^\circ). It remains also possible that the two outer planets are not trapped in an orbital resonance. Then their orbital eccentricities should be relatively small (less than, say, 0.15) and the ratio of their orbital periods is unlikely to exceed 2.32.52.3-2.5.Comment: 28 pages, 10 figures, 3 tables; Accepted to Celestial Mechanics and Dynamical Astronom

    Tendência genética do peso ao desmame de bezerros da raça Nelore.

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    Estudou-se a tendência genética do peso ao desmame de 94.052 animais da raça Nelore de seis regiões do Brasil, através da metodologia de SMITH (1962), com dois modelos estatísticos, um contendo os efeitos fixos de sexo, mes e ano de nascimento do bezerro, fazenda e idade da vaca ao parto e o efeito aleatório de touro, o outro, semelhante, porem, sem o efeito de touro. Os valores obtidos foram 994;-188;902;692;868;1115 g/ano, para as diferentes regiões estudadas. Os ganhos genético obtidos no período, em geral, foram altos, a exceção da região dois que apresentaram valor negativo, revelando, talvez, a inexistência de um programa de seleção.Resumo expandid
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