Canonical transformation for stiff matter models in quantum cosmology

In the present work we consider Friedmann-Robertson-Walker models in the presence of a stiff matter perfect fluid and a cosmological constant. We write the superhamiltonian of these models using the Schutz's variational formalism. We notice that the resulting superhamiltonians have terms that will lead to factor ordering ambiguities when they are written as operators. In order to remove these ambiguities, we introduce appropriate coordinate transformations and prove that these transformations are canonical using the symplectic method.Comment: Revtex4 Class, 3 pages, No Figure

Equivalence between different classical treatments of the O(N) nonlinear sigma model and their functional Schrodinger equations

In this work we derive the Hamiltonian formalism of the O(N) non-linear sigma model in its original version as a second-class constrained field theory and then as a first-class constrained field theory. We treat the model as a second-class constrained field theory by two different methods: the unconstrained and the Dirac second-class formalisms. We show that the Hamiltonians for all these versions of the model are equivalent. Then, for a particular factor-ordering choice, we write the functional Schrodinger equation for each derived Hamiltonian. We show that they are all identical which justifies our factor-ordering choice and opens the way for a future quantization of the model via the functional Schrodinger representation.Comment: Revtex version, 17 pages, substantial change

Gestão da biodiversidade e produção agrícola: o Cerrado goiano.

Este trabalho procura realizar uma reflexão sobre os processos e políticas ambientais e de gestão da biodiversidade relacionados com o ecossistema do Cerrado. Para tanto, realiza uma síntese do significado desse ecossistema, procura resgatar alguns conteúdos históricos relacionados à ocupação desse território e busca identificar os principais atores e tensões sociais envolvidos no processo que define o atual padrão ambiental do mesmo. Para que, em uma visão sistêmica, o processo de ocupação do Cerrado de Goiás possa ser melhor compreendido, foi feito um esforço para demonstrar o arcabouço institucional e legal, no âmbito federal e estadual, e as possíveis formas de gestão relacionadas com o manejo da biodiversidade local