Avaliação do impacto ambiental de sistemas intensivos de produção de carne bovina conduzidos em pastagens.

bitstream/CPPSE/17576/1/Boletim14.pdfISSN 1981-207

Field-theoretical renormalization group for a flat two-dimensional Fermi surface

We implement an explicit two-loop calculation of the coupling functions and the self-energy of interacting fermions with a two-dimensional flat Fermi surface in the framework of the field theoretical renormalization group (RG) approach. Throughout the calculation both the Fermi surface and the Fermi velocity are assumed to be fixed and unaffected by interactions. We show that in two dimensions, in a weak coupling regime, there is no significant change in the RG flow compared to the well-known one-loop results available in the literature. However, if we extrapolate the flow to a moderate coupling regime there are interesting new features associated with an anisotropic suppression of the quasiparticle weight Z along the Fermi surface, and the vanishing of the renormalized coupling functions for several choices of the external momenta.Comment: 16 pages and 22 figure

Condutividade hidráulica saturada de campo em pastagens tropicais submetidas a exploração intensiva da pastagem.

Foram realizadas medições de CHSC, utilizando permeâmetro de Guelph, em Latossolo Vermelho-Amarelo Distrófico típico (26% argila), Latossolo Vermelho Distrófico típico (29% argila), Latossolo Vermelho Distroférrico (antigo Latossolo Roxo; 40% argila) e Nitossolo Vermelho Eutroférrico (antiga Terra Roxa Estruturada; 45% argila), nas profundidades de 10, 20 e 60 cm. O objetivo foi verificar se os manejos das pastagens são adequados para manter as propriedades físicas favoráveis do solo. Os resultados mostraram que tanto na exploração extensiva como intensiva da pastagem, evitando-se superpastejo, houve manutenção ou mesmo aumento da CHSC na camada de 0 a 10 cm, e que variou de 0,8 a 4,1 m/h, dependendo do tipo de solo

Final-state, Open-loop Control of the Heat equation in Tensorial Domains (full version)

In this paper, a quadratic optimal control problem will be considered for the heat equation in tensorial domains with homogeneous Dirichlet boundary conditions, in which the control function (depending only on time) constitutes a source term. These problems involve choosing a control function (with or without "peak-value" constraints) to approximately steer the solution of the heat equation to a desired function at the end of a prescribed (finite) time-interval. To compute approximations to the desired optimal control functions, semi-discrete, spectral (with eigenfunctions) Galerkin approximations to the corresponding heat equation and the corresponding (approximating) control problems are tackled. Two simple, illustrative examples are presented in the final section.Comment: 32 pages, 11 figures, submitte