Symmetries and Ambiguities in the linear sigma model with light quarks

We investigate the role of undetermined finite contributions generated by radiative corrections in a $SU(2)\times SU(2)$ linear sigma model with quarks. Although some of such terms can be absorbed in the renormalization procedure, one such contribution is left in the expression for the pion decay constant. This arbitrariness is eliminated by chiral symmetry.Comment: 9 pages. Added references through the text; an author was added due to an important contribution; corrected typos; the title also was changed. Submitted to Modern Physics Letter

Ultraviolet and Infrared Divergences in Implicit Regularization: a Consistent Approach

Implicit Regularization is a 4-dimensional regularization initially conceived to treat ultraviolet divergences. It has been successfully tested in several instances in the literature, more specifically in those where Dimensional Regularization does not apply. In the present contribution we extend the method to handle infrared divergences as well. We show that the essential steps which rendered Implicit Regularization adequate in the case of ultraviolet divergences have their counterpart for infrared ones. Moreover we show that a new scale appears, typically an infrared scale which is completely independent of the ultraviolet one. Examples are given.Comment: 9 pages, version to appear in Mod. Phys. Lett.

The effects caused by the replacement of native riparian forest with Eucalyptus sp. on the benthic macro-invertebrate community.

The replacement of native riparian forests with exotic plants, especially Eucalyptus sp. can cause changes in ecological processes of small orders rivers. The leaves of Eucalyptus sp. have lower nutrients concentration, higher hardness and secondary metabolites which inhibit the decomposing micro-organisms and benthic macro-invertebrate colonization, which are the connection between the dead organic matter and the rest of the food chain. Thus the aim of the study was to test the following hypothesis: leaf decomposition rate will be lower in the substrate composed of Eucalyptus sp. leaves, when compared to the substrate composed of native tree species leaves; the benthic macro-invertebrates diversity will be lower in the substrate composed of Eucalyptus sp. leaves than the one composed of native tree species leaves. Sixty litter bags were used in the experiment, 30 of them were filled with 5 g of Eucalyptus sp leaves and the other 30 with a mixture of native trees leaves. From the results it was concluded that leaf decomposition rates were similar for both substrates, substrate composed of native trees leaves and substrate composed of Eucalyptus sp. leaves; the benthic macroinvertebrates diversity was lower in the substrate composed of Eucalyptus sp. leaves when compared to the substrate composed of native tree species leaves

Estaquia de castanheira-do-Brasil: influência de substratos, suplementação mineral e ácido bórico no enraizamento adventício.

Este trabalho teve como objetivo avaliar a influência de substratos, adubação e ácido bórico no enraizamento adventício de estacas de B. excelsa, espécie de importância ecologia e econômica para a Região Amazônica

Caracterização biofísica e aptidão agrícola das terras em áreas de projeto de assentamento oficial: PA São Francisco.

Caracterização da área; Clima; Vegetação; Geologia e geomorfologia; Mapeamento das unidades de solo; Argissolos vermelho-amarelos; Cambissolos háplicos; Plintossolos argilúvicos; Gleissolos háplicos; Neossolos flúvicos; Avaliação da aptidão agrícola das terras; Classes de aptidão agrícola das terras.bitstream/item/63435/1/Oriental-Doc136.pd

Diversidade florística e fitossociológica do tapete herbáceo da caatinga na reserva legal do Salitre, Juazeiro-BA.

Para amostragem das herbáceas foi adotado o método das parcelas, com 50m2 de área amostral em cada microhabitate