16,240 research outputs found
Ab initio calculation of the dynamical properties of PPP and PPV
In this work, we have calculated the vibrational modes and frequencies of the
crystalline PPP (in both the Pbam and Pnnm symmetries) and PPV (in the P21/c
symmetry). Our results are in good agreement with the available experimental
data. Also, we have calculated the temperature dependence of their specific
heats at constant volume, and of their vibrational entropies. Based on our
results, at high temperatures, the PPP is more stable in the Pnnm structure
than in the Pbam one.Comment: 5 pages, 7 figures, accepted for publication in Braz. J. Phys.,
special number, Proceedings of BWSP-12, 12th Brazilian Workshop on
Semiconductor Physic
Relatório do cruzeiro realizado no Banco de Sofala pelo navio "Pantikapey" de 7-23/Junho/1981: peixes demersais e fauna acompanhante de camarāo
Catch composition and bathymetric distribution of demersal fish caught along the coast of Mozambique between parallels 16 degree 20' and 19 degree 30' S at depths of 11 to 180 metres are given. The shrimp by-catch was also studied
Restoration of U(1) symmetry and meson spectrum in hot or dense matter
We explore the effects of breaking and restoration of chiral and axial
symmetries using an extended three-flavor Nambu-Jona-Lasinio model that
incorporates explicitly the axial anomaly through the 't Hooft interaction. We
implement a temperature (density) dependence of the anomaly coefficient
motivated by lattice results for the topological susceptibility. The spectrum
of scalar and pseudoscalar mesons is analyzed bearing in mind the
identification of chiral partners and the study of its convergence. We also
concentrate on the behavior of the mixing angles that give us relevant
information on the issue under discussion. The results suggest that the axial
part of the symmetry is restored before the possible restoration of the full
U(3)U(3) chiral symmetry might occur.Comment: 9 pages, 5 figures. Talk given at Joint Meeting
Heidelberg-Liege-Paris-Rostock (HLPR 2004), Spa, Belgium, 16-18 Dec 200
The biology and availability of the spiny lobster Palinurus delagoae Barnard, off the coast of Mozambique
Catch and effort data and some biological characteristics of the deep water spiny lobster P. delagoae collected between August 1980 and December 1981, are presented. The work was conducted on board a commercial vessel off the coast of Mozambique
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