Description of atmospheric conditions at the Pierre Auger Observatory using the Global Data Assimilation System (GDAS)

Atmospheric conditions at the site of a cosmic ray observatory must be known for reconstructing observed extensive air showers. The Global Data Assimilation System (GDAS) is a global atmospheric model predicated on meteorological measurements and numerical weather predictions. GDAS provides altitude-dependent profiles of the main state variables of the atmosphere like temperature, pressure, and humidity. The original data and their application to the air shower reconstruction of the Pierre Auger Observatory are described. By comparisons with radiosonde and weather station measurements obtained on-site in Malargue and averaged monthly models, the utility of the GDAS data is shown. (C) 2012 Elsevier B.V. All rights reserved.

Em busca de uma nova inserção da América Latina na economia global

O objetivo deste artigo é discutir, de forma interdisciplinar, as condições necessárias e os caminhos para concretizar um modelo econômico e político de maior autonomia no cenário mundial para os países da América do Sul. O enfoque parte das condições políticas e sociais configuradas pela região ao fim da primeira década do presente século, enfatizando o papel do Brasil e considerando as relações econômicas e políticas do contexto internacional, a estabilidade política e o crescente protagonismo da China nos países da região. Analisa ainda aspectos referentes à importância da política social e da política de defesa comum sob a União das Nações Sul-Americanas (Unasul).

Enhancement of Nematic Order and Global Phase Diagram of a Lattice Model for Coupled Nematic Systems

We use an infinite-range Maier-Saupe model, with two sets of local quadrupolar variables and restricted orientations, to investigate the global phase diagram of a coupled system of two nematic subsystems. The free energy and the equations of state are exactly calculated by standard techniques of statistical mechanics. The nematic-isotropic transition temperature of system A increases with both the interaction energy among mesogens of system B, and the two-subsystem coupling J. This enhancement of the nematic phase is manifested in a global phase diagram in terms of the interaction parameters and the temperature T. We make some comments on the connections of these results with experimental findings for a system of diluted ferroelectric nanoparticles embedded in a nematic liquid-crystalline environment.