On duality of the noncommutative extension of the Maxwell-Chern-Simons model

We study issues of duality in 3D field theory models over a canonical noncommutative spacetime and obtain the noncommutative extension of the Self-Dual model induced by the Seiberg-Witten map. We apply the dual projection technique to uncover some properties of the noncommutative Maxwell-Chern-Simons theory up to first-order in the noncommutative parameter. A duality between this theory and a model similar to the ordinary self-dual model is estabilished. The correspondence of the basic fields is obtained and the equivalence of algebras and equations of motion are directly verified. We also comment on previous results in this subject.Comment: Revtex, 9 pages, accepted for publication PL

The Quantum Algebraic Structure of the Twisted XXZ Chain

We consider the Quantum Inverse Scattering Method with a new R-matrix depending on two parameters $q$ and $t$. We find that the underlying algebraic structure is the two-parameter deformed algebra $SU_{q,t}(2)$ enlarged by introducing an element belonging to the centre. The corresponding Hamiltonian describes the spin-1/2 XXZ model with twisted periodic boundary conditions.Comment: LateX file, 9 pages, Minor changes (including authors` names in the hep-th heading

Environment, morphology and stellar populations of bulgeless low surface brightness galaxies

Based on the Sloan Digital Sky Survey DR 7, we investigate the environment, morphology and stellar population of bulgeless low surface brightness (LSB) galaxies in a volume-limited sample with redshift ranging from 0.024 to 0.04 and $M_r$ $\leq$ $-18.8$. The local density parameter $\Sigma_5$ is used to trace their environments. We find that, for bulgeless galaxies, the surface brightness does not depend on the environment. The stellar populations are compared for bulgeless LSB galaxies in different environments and for bulgeless LSB galaxies with different morphologies. The stellar populations of LSB galaxies in low density regions are similar to those of LSB galaxies in high density regions. Irregular LSB galaxies have more young stars and are more metal-poor than regular LSB galaxies. These results suggest that the evolution of LSB galaxies may be driven by their dynamics including mergers rather than by their large scale environment.Comment: 12 pages, 13 figures, Accepted by A&

Heterosis and its components in crosses among high quality protein maize populations.

The objetive of the present study was to investigate heterosis in high quality protein maize populations of distinct grain type groups. Agronomic traits and reaction to some leaf diseases of 19 yellow grain populations were assessed in a partial diallel grown in four environments. For grain yield trait, only variety effects and average heterosis were significant, indicating that the best intervarietal hybrids can be predicted using the means of the parental populations. The BR 473 and CMS 52 flint populations, the CMS 474 and ZQP 103 dent populations are recommended for an inter-group reciprocal recurrent selection program. In a decreasing order of preference, the dent type CMS 474, ZQP 103 and ZQP 101 populations and the flint type BR 473, CMS 455C, CMS 453, CMS 52, CMS 455 and CMS 458 are recommended to form composites

Anisotropic Cosmological Constant and the CMB Quadrupole Anomaly

There are evidences that the cosmic microwave background (CMB) large-angle anomalies imply a departure from statistical isotropy and hence from the standard cosmological model. We propose a LCDM model extension whose dark energy component preserves its nondynamical character but wield anisotropic vacuum pressure. Exact solutions for the cosmological scale factors are presented, upper bounds for the deformation parameter are evaluated and its value is estimated considering the elliptical universe proposal to solve the quadrupole anomaly. This model can be constructed from a Bianchi I cosmology with cosmological constant from two different ways: i) a straightforward anisotropic modification of the vacuum pressure consistently with energy-momentum conservation; ii) a Poisson structure deformation between canonical momenta such that the dynamics remain invariant under scale factors rescalings.Comment: 8 pages, 2 columns, 1 figure. v2: figure improved, added comments on higher eccentricity powers and references. v3: typos corrected, version to appear in PR

Avaliação dos impactos ambientais e socioeconômicos do sistema de produção de leite a pasto na Fazenda Escola de Cachoeiras de Macacu.

Resumo: A Fazenda Escola de Cachoeiras de Macacu da Universidade Federal Fluminense está implantando um sistema de produção de leite a pasto. Entretanto, qualquer sistema de produção animal é capaz de trazer impactos ambientais importantes. Assim, o objetivo deste trabalho foi avaliar os impactos ambientais e socioeconômicos da implantação dessa tecnologia, utilizando-se o Sistema Ambitec-Agro, desenvolvido pela Embrapa Meio Ambiente. O índice geral de impacto da atividade foi de 0,99 (em escala ±15), observando-se impactos socioeconômicos positivos, mas potencial para ocorrência de impactos ambientais negativos. Sugere-se a adoção de técnicas alternativas de manejo para a mitigação desses impactos

Quantum corrections to gravity and their implications for cosmology and astrophysics

The quantum contributions to the gravitational action are relatively easy to calculate in the higher derivative sector of the theory. However, the applications to the post-inflationary cosmology and astrophysics require the corrections to the Einstein-Hilbert action and to the cosmological constant, and those we can not derive yet in a consistent and safe way. At the same time, if we assume that these quantum terms are covariant and that they have relevant magnitude, their functional form can be defined up to a single free parameter, which can be defined on the phenomenological basis. It turns out that the quantum correction may lead, in principle, to surprisingly strong and interesting effects in astrophysics and cosmology.Comment: 15 pages, LaTeX, WS style, contribution to the Proceedings of the QFEXT-2011 conference in the Centro de Ciencias de Benasque Pedro Pasqual, Spai