Functional Bosonization of Non-Relativistic Fermions in (2+1)(2+1) Dimensions

We analyze the universality of the bosonization rules in non-relativistic fermionic systems in $(2+1)d$. We show that, in the case of linear fermionic dispersion relations, a general fermionic theory can be mapped into a gauge theory in such a way that the fermionic density maps into a magnetic flux and the fermionic current maps into a transverse electric field. These are universal rules in the sense that they remain valid whatever the interaction considered. We also show that these rules are universal in the case of non-linear dispersion relations provided we consider only density-density interactions. We apply the functional bosonization formalism to a non-relativistic and non-local massive Thirring-like model and evaluate the spectrum of collective excitations in several limits. In the large mass limit, we are able to exactly calculate this spectrum for arbitrary density-density and current-current interactions. We also analyze the massless case and show that it has no collective excitations for any density-density potential in the Gaussian approximation. Moreover, the presence of current interactions may induce a gapless mode with a linear dispersion relation.Comment: 26 Pages, LaTeX, Final version to appear in International Journal of Modern Physics

On the chromospheric activity of stars with planets

Context. Signatures of chromospheric activity enhancement have been found for a dozen stars, pointing to a possible star-planet interaction. Nevertheless in the coronal activity regime, there is no conclusive observational evidence for such an interaction. Does star-planet interaction manifest itself only for a few particular cases, without having a major effect on stars with planets in general? Aims. We aim to add additional observational constraints to support or reject the major effects of star-planet interactions in stellar activity, based on CaII chromospheric emission flux. Methods. We performed a statistical analysis of CaII emission flux of stars with planets, as well as a comparison between CaII and X-ray emission fluxes, searching for dependencies on planetary parameters. Results. In the present sample of stars with planets, there are no significant correlations between chromospheric activity indicator log(R'HK) and planetary parameters. Further, the distribution of the chromospheric activity indicator for stars without planets is not distinguishable from the one with planets.Comment: 6 pages, 5 figures, submitted to A&

Visao retrospectiva do melhoramento genetico do algodoeiro moco (Gossypium hirsutum r. marie galante Hutch) no nordeste do Brasil.

bitstream/item/33387/1/VISAO-RETROSPECTIVA.pd

Zoneamento para a cultura do algodão no Nordeste. II. Algodão herbaceo.

bitstream/item/33388/1/ZONEMAMENTO-PARA.pd

Dimensão ambiental do Projeto de Assentamento Agrícola Nilson Campos - Porto Velho - Rondônia.

No presente documento são apresentados os resultados quanto à dimensão ambiental obtidos no levantamento realizado no projeto de assentamento estudado no período de dezembro 2001/março 2002 bem como, informações bibliográficas quanto à dimensão ambiental do mesmo e propostas de projetos para conservação e melhor utilização dos recursos naturais do assentamento agrícola estudado.bitstream/item/54345/1/Doc92-assentamentoagricola.pd

Avaliação agroeconômica de sistemas consorciados de cenoura e rúcula.

Um dos sistemas de cultivo que pode contribuir para a realização de uma agricultura sustentável economicamente é a consorciação de culturas. Estudos coprovam que rendimentos advindos de sistemas consorciados de hortaliças, apresentam-se vantajosos em relação aos obtidos nas culturas soslteiras