Evolving wormhole geometries within nonlinear electrodynamics

In this work, we explore the possibility of evolving (2+1) and (3+1)-dimensional wormhole spacetimes, conformally related to the respective static geometries, within the context of nonlinear electrodynamics. For the (3+1)-dimensional spacetime, it is found that the Einstein field equation imposes a contracting wormhole solution and the obedience of the weak energy condition. Nevertheless, in the presence of an electric field, the latter presents a singularity at the throat, however, for a pure magnetic field the solution is regular. For the (2+1)-dimensional case, it is also found that the physical fields are singular at the throat. Thus, taking into account the principle of finiteness, which states that a satisfactory theory should avoid physical quantities becoming infinite, one may rule out evolving (3+1)-dimensional wormhole solutions, in the presence of an electric field, and the (2+1)-dimensional case coupled to nonlinear electrodynamics.Comment: 17 pages, 1 figure; to appear in Classical and Quantum Gravity. V2: minor corrections, including a referenc

An anti-Schwarzshild solution: wormholes and scalar-tensor solutions

We investigate a static solution with an hyperbolic nature, characterised by a pseudo-spherical foliation of space. This space-time metric can be perceived as an anti-Schwarzschild solution, and exhibits repulsive features. It belongs to the class of static vacuum solutions termed "a degenerate static solution of class A". In the present work we review its fundamental features, discuss the existence of generalised wormholes, and derive its extension to scalar-tensor gravity theories in general.Comment: 3 pages, contribution to the proceedings of the Spanish Relativity Meeting-ERE200

A new special class of Petrov type D vacuum space-times in dimension five

Using extensions of the Newman-Penrose and Geroch-Held-Penrose formalisms to five dimensions, we invariantly classify all Petrov type $D$ vacuum solutions for which the Riemann tensor is isotropic in a plane orthogonal to a pair of Weyl alligned null directionsComment: 4 pages, 1 table, no figures. Contribution to the proceedings of the Spanish Relativity Meeting 2010 held in Granada (Spain

Tsallis holographic dark energy in the Brans-Dicke cosmology

Using the Tsallis generalized entropy, holographic hypothesis and also considering the Hubble horizon as the IR cutoff, we build a holographic model for dark energy and study its cosmological consequences in the Brans-Dicke framework. At first, we focus on a non-interacting universe, and thereinafter, we study the results of considering a sign-changeable interaction between the dark sectors of the cosmos. Our investigations show that, compared with the flat case, the power and freedom of the model in describing the cosmic evolution is significantly increased in the presence of the curvature. The stability analysis also indicates that, independent of the universe curvature, both the interacting and non-interacting cases are classically unstable. In fact, both the classical stability criterion and an acceptable behavior for the cosmos quantities, including the deceleration and density parameters as well as the equation of state, are not simultaneously obtainable.Comment: Accepted version, Eur. Phys. J. C (2018

Efeitos de variantes do gene da aromatase sobre caracteristicas de crescimento, reprotutivas e de habilidade materna em ovinos de uma população multirracial.

Resumo: Foi verificado o efeito das variantes do gene da aromatase sobre características produtivas e reprodutivas de ovinos de uma população multirracial. Para isto, fêmeas de diferentes grupos genéticos foram genotipadas e a influência do genótipo do animal sobre seu desempenho ou sobre o desempenho de suas crias foi analisada pelo método dos quadrados mínimos. Fêmeas BB apresentaram menor idade ao primeiro parto para o grupo genético ½ Dorper e menor intervalo de partos para a raça Santa Inês. Nestes mesmos grupos genéticos, as fêmeas AB apresentaram maiores pesos totais de crias desmamadas por matriz e por parto. Existem evidências que fêmeas BB apresentam melhores desempenhos reprodutivos, contrariamente às fêmeas AB que apresentam melhores habilidades maternas. Entretanto, maiores investigações são necessárias para comprovar estas evidências; [Allelic Frequency from Aromatase Gene in Meat Sheep]. Abstract: The effect of variants for aromatase gene on productive and reproductive traits in sheep from a multiracial population was verified. Females of different genetic groups were genotyped and the influence of the genotype of the animal on your performance or on the performance of yours lambs was analyzed by the least square method. BB females presented lower age at first lambing for ½ Dorper and lower lambing interval for Santa Inês breed. In these same genetic groups, AB females presented larger total weight of weaned lambs per female and per lambing. There are evidences that BB females presented better reproductive performance, contrarily to AB females that presented better maternal ability. However, more investigations are necessary to prove these evidences

Caracterização da expressão de inibidores de poligalacturonases (pgips) em resposta aos estresses biótico e abiótico em plantas de feijão comum (Phaseolus vulgaris L.).

O presente trabalho teve como objetivo, avaliar a expressão de genes inibidores de poligalacturonases (PvPgip) em plantas de feijão comum (Phaseolus vulgaris L.) em resposta aos estresses biótico e abiótico.CONAFE