Nonadiabatic charged spherical evolution in the postquasistatic approximation

We apply the postquasistatic approximation, an iterative method for the evolution of self-gravitating spheres of matter, to study the evolution of dissipative and electrically charged distributions in General Relativity. We evolve nonadiabatic distributions assuming an equation of state that accounts for the anisotropy induced by the electric charge. Dissipation is described by streaming out or diffusion approximations. We match the interior solution, in noncomoving coordinates, with the Vaidya-Reissner-Nordstr\"om exterior solution. Two models are considered: i) a Schwarzschild-like shell in the diffusion limit; ii) a Schwarzschild-like interior in the free streaming limit. These toy models tell us something about the nature of the dissipative and electrically charged collapse. Diffusion stabilizes the gravitational collapse producing a spherical shell whose contraction is halted in a short characteristic hydrodynamic time. The streaming out radiation provides a more efficient mechanism for emission of energy, redistributing the electric charge on the whole sphere, while the distribution collapses indefinitely with a longer hydrodynamic time scale.Comment: 11 pages, 16 Figures. Accepted for publication in Phys Rev

Equation of state and transport processes in self--similar spheres

We study the effect of transport processes (diffusion and free--streaming) on a collapsing spherically symmetric distribution of matter in a self--similar space--time. A very simple solution shows interesting features when it is matched with the Vaidya exterior solution. In the mixed case (diffusion and free--streaming), we find a barotropic equation of state in the stationary regime. In the diffusion approximation the gravitational potential at the surface is always constant; if we perturb the stationary state, the system is very stable, recovering the barotropic equation of state as time progresses. In the free--streaming case the self--similar evolution is stationary but with a non--barotropic equation of state.Comment: 9 pages, 2 figure

Activation-Induced Cytidine Deaminase Does Not Impact Murine Meiotic Recombination

Activation-Induced Cytidine Deaminase (AID) was first described as the triggering enzyme of the B-cell-specific reactions that edit the immunoglobulin genes, namely somatic hypermutation, gene conversion and class switch recombination. Over the years, AID was also detected in cells other than lymphocytes, and it has been assigned additional roles in the innate defense against transforming retroviruses, in retrotransposition restriction and in DNA demethylation. Notably, AID expression was found in germline tissues, and in heterologous systems it can induce the double-strand breaks required for the initiation of meiotic recombination and proper gamete formation. However, since AID deficient mice are fully fertile, the molecule is not essential for meiosis. Thus, the remaining question that we addressed here is whether AID influences the frequency of meiotic recombination in mice. We measured the recombination events in the meiosis of male and female mice F1 hybrids of C57BL/6J and BALB/c, in Aicda(+/+) and Aicda(-/-) background using a panel of SNPs that distinguishes C57BL/6J from BALB/c genome across the 19 autosomes. In agreement with the literature, we found that the frequency of recombination in the female germline was higher than in male germline, both in the Aicda(+/+) and the Aicda(-/-) backgrounds. No statistical difference was found in the average recombination events between Aicda(+/+) and Aicda(-/-) animals, either in females or males. In addition, the recombination frequency between SNPs flanking the IgH and Igκ loci was also not different. We conclude that AID has a minor impact, if any, on the overall frequency of meiotic recombination.Marie Curie Reintegration grant: (PIRG03-GA-2008230967), FCT fellowship: (SFRH/BPD/66824/2009)

Controlling Physical Systems with Symmetries

Symmetry properties of the evolution equation and the state to be controlled are shown to determine the basic features of the linear control of unstable orbits. In particular, the selection of control parameters and their minimal number are determined by the irreducible representations of the symmetry group of the linearization about the orbit to be controlled. We use the general results to demonstrate the effect of symmetry on the control of two sample physical systems: a coupled map lattice and a particle in a symmetric potential.Comment: 6 page

Self-similar and charged spheres in the diffusion approximation

We study spherical, charged and self--similar distributions of matter in the diffusion approximation. We propose a simple, dynamic but physically meaningful solution. For such a solution we obtain a model in which the distribution becomes static and changes to dust. The collapse is halted with damped mass oscillations about the absolute value of the total charge.Comment: 15 pages, 7 figure

Scedosporium and Pseudallescheria low molecular weight metabolites revealed by database search

The potential of mMass software search tool with new compound libraries was demonstrated on metabolomics of Scedosporium prolificans, S. apiospermum and Pseudallescheria boydii sensu stricto. Cyclic peptides pseudacyclins, small molecular weight tyroscherin analogues and various lipids were annotated by open source mass spectometry tool utilising accurate matrix-assisted laser desorption/ionisation mass spectral data of intact fungal spores. Electrospray ionisation combined with tandem mass spectrometry was used for monohexosylceramide characterisation in fungal extracts

Bibliotecas públicas, exclusão social e o fim da esfera pública

Esta comunicação apresenta e discute os fundamentos teóricos essenciais das bibliotecas públicas no que diz respeito à definição e real prossecução dos seus papéis sociais, explorando a utilização do conceito de capital social. Analisa igualmente de um modo crítico a sua real - ou desejada - intervenção enquanto instrumento de inclusão social e na luta ativa contra a exclusão social, bem como a conceção de biblioteca pública enquanto elemento constitutivo da esfera pública, detetando uma tendência ou um perigo do enfraquecimento progressivo desta. Esta discussão é feita com base numa revisão da literatura com origem nos países do eixo latino-americano (incluindo Portugal, Espanha, França e a América Latina em geral), anglo-saxónico e escandinavo, depois de uma secção que faz a apresentação de uma série de dados com o propósito de traçar uma caracterização de Portugal em termos socioeconómicos, concluindo pela existência e mesmo o agravamento de diversos fatores de exclusão e desigualdade social, logo de grandes assimetrias no acesso, não só aos bens materiais como à cultura e à educação. Conclui-se que a biblioteca pública pode desempenhar e tem efetivamente desempenhado, nos últimos anos, em diversas partes do mundo, importantes papéis sociais, contribuindo para aumentar o capital social das comunidades, para a inclusão e na luta contra a exclusão social. As bibliotecas são um elemento importante da esfera pública, mas todas estas funções ou atributos são muitas vezes resultado de iniciativas locais e/ou de profissionais individualmente, faltando geralmente políticas, orientações nacionais, e muitas vezes recursos para o cumprimento destes papéis. A tudo isto acresce a crescente perda de importância da esfera pública, com um grande desinvestimento nas funções sociais do Estado. É neste contexto que os profissionais podem ser decisivos na defesa e reafirmação dos valores e do impacto social das bibliotecas públicas