Addendum: Behavior of a bipartite system in a cavity

This note is an Addendum to our previous article [Phys. Rev. A \textbf{81}, 053820 (2010)]. We show that under the assumption of a Bose-Einstein distribution for the thermal reservoir, zero-temperature properties of the entangled states considered there are not changed by heating, for temperatures up to the order of room temperatures. In this case, the system is dissipative in free space and presents stability for a small cavity, both for T=0 and for finite temperature.Comment: Revtex, 04 pages no figures, Version as accepted for publication in Phys. Rev.

Behavior of a bipartite system in a cavity

We study the time evolution of a superposition of product states of two dressed atoms in a spherical cavity in the situations of an arbitrarily large cavity (free space) and of a small one. In the large-cavity case, the system dissipates, whereas, for the small cavity, the system evolves in an oscillating way and never completely decays. We verify that the von Neumann entropy for such a system does not depend on time, nor on the size of the cavityComment: 9 pages 2 figures, Revtex, Version accepted to be published in Physical Review

Magnetic effects on spontaneous symmetry breaking/restoration in a toroidal topology

We study temperature and finite-size effects on the spontaneous symmetry breaking/restoration for a scalar field model under the influence of an external magnetic field, at finite chemical potential. We use the 2PI formalism and consider the large-$N$ limit. We find that there is a minimal size of the system to sustain the broken phase, which diminishes as the applied field increases but is independent of the chemical potential. We analyze the critical curves and show that the magnetic field enhances the broken-phase regions, while increasing the chemical potential leads to a diminishement of the critical temperature.Comment: Five pages, five figures, version as accepted for publication in Phys. Rev.

Asymptotic Expansions of Feynman Amplitudes in a Generic Covariant Gauge

We show in this paper how to construct Symanzik polynomials and the Schwinger parametric representation of Feynman amplitudes for gauge theories in an unspecified covariant gauge. The complete Mellin representation of such amplitudes is then established in terms of invariants (squared sums of external momenta and squared masses). From the scaling of the invariants by a parameter we extend for the present situation a theorem on asymptotic expansions, previously proven for the case of scalar field theories, valid for both ultraviolet and infrared behaviors of Feynman amplitudes.Comment: 10 pages, revtex, no figure

Vanishing value chains, industrial districts and HRM in the Brazilian automotive industry

Industrial districts in the Brazilian automotive industry have facilitated just-in-time production, functional flexibility, and compatibility of HR practices since the 1980s. However, this model has been threatened by global over-capacity and the rise of low cost suppliers in South Korea and China. This paper develops literature on proximity dynamics though exploring the influence of global supply chains on HRM in industrial districts. The more specific research questions are: How viable are industrial districts in the context of global crises? And how is this viability bound up with the awareness of HR practices down the supply chain? The findings indicate that the industrial districts model is under threat. In the context of global supply chains, automotive majors have shifted costs onto their suppliers, disrupting established relationships, and moreover, they often lack knowledge of the employment practices of distant suppliers. Yet, in times of political and economic uncertainty, worker rights might be best served by geographical and cognitive proximity

Fifth disease in children living in Belém, Brazil

Amostras de soro colhidas na fase aguda de doença exantemática, acomentendo duas crianças, revelaram-se positivas quanto à presença de IgM específica para o vírus B 19, através do método de rádio-imuno-ensaio por mecanismo de captura. O primeiro paciente, um menino de dois anos, apresentou erupção cutânea com seis dias de duração; o segundo foi uma menina de quatro anos de idade, irmã do primeiro paciente e que foi submetida a exame à mesma época em que se procedeu à avaliação clínica do irmão, e que exibia "rash" cutâneo que evoluía há três dias.Acute sera from two children suffering from an illness with an erythematous rash were positive for B 19 virus specific IgM antibody, as tested by a capture radioimmunoassay. The first patient, a two year old boy, presented with a cutaneous rash of six days duration, the second was a four year old girl, sister of the first patient, who was examined at the same time and had a three day history of cutaneous rash