Using Entropy-Based Methods to Study General Constrained Parameter Optimization Problems

In this letter we propose the use of physics techniques for entropy determination on constrained parameter optimization problems. The main feature of such techniques, the construction of an unbiased walk on energy space, suggests their use on the quest for optimal solutions of an optimization problem. Moreover, the entropy, and its associated density of states, give us information concerning the feasibility of solutions.Comment: 10 pages, 3 figures, references correcte

Fatores que influenciam características de produtividade de vacas da raça Nelore.

Avaliação dos efeitos de alguns fatores sobre as relações dos pesos dos bezerros ao nascimento e a desmama com o peso e a idade da vaca ao parto e sobre a habilidade materna mais provável para os pesos ao nascimento e a desmama e ganho de peso do nascimento a desmama da raça Nelore pertencentes a um rebanho comercial do estado de São Paulo

Causas de variação não genética sobre características de peso de animais de um rebanho Nelore.

Estudaram-se os efeitos dos fatores não genético sobre 6581, 5418 e 1800 observações de pesos ao nascimento, a desmama e sobreano respectivamente, de animais de um rebanho Nelore comercial, criado em regime de pastagens na região Oeste do Estado de São Paulo.Resumo

A semiquantitative approach to the impurity-band-related transport properties of GaMnAs nanolayers

We investigate the spin-polarized transport of GaMnAs nanolayers in which a ferromagnetic order exists below a certain transition temperature. Our calculation for the self-averaged resistivity takes into account the existence of an impurity band determining the extended ("metallic" transport) or localized (hopping by thermal excitation) nature of the states at and near the Fermi level. Magnetic order and resistivity are inter-related due to the influence of the spin polarization of the impurity band and the effect of the Zeeman splitting on the mobility edge. We obtain, for a given range of Mn concentration and carrier density, a "metallic" behavior in which the transport by extended carriers dominates at low temperature, and is dominated by the thermally excited localized carriers near and above the transition temperature. This gives rise to a conspicuous hump of the resistivity which has been experimentally observed and brings light onto the relationship between transport and magnetic properties of this material