Navegando por Autor "Silva, R."
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Artigo Generalized quantum entropies(Elsevier, 2011-07-08) Anselmo, Dory Hélio Aires de Lima; Santos, A. P.; Silva, R.; Alcaniz, J. S.A deduction of generalized quantum entropies within the Tsallis and Kaniadakis frameworks is derived using a generalization of the ordinary multinomial coefficient. This generalization is based on the respective deformed multiplication and division. We show that the two above entropies are consistent with ones arbitrarily assumed at other contextsArtigo Non-gaussian statistics and stellar rotational velocities of main-sequence field stars(American Astronomical Society, 2009) Carvalho, J. C.; Nascimento Jr., J. D. do; Silva, R.; Medeiros, José Renan deIn this Letter, we study the observed distributions of rotational velocity in a sample of more than 16,000 nearby F and G dwarf stars, magnitude complete, and presenting high-precision V sin i measurements. We show that the velocity distributions cannot be fitted by a Maxwellian. In addition, an analysis based on both Tsallis and Kaniadakis power-law statistics is by far the most appropriate statistics and gives a very good fit. It is also shown that single and binary stars have similar rotational distributions. This is the first time, to our knowledge, that these two new statistics have been tested for the rotation of such a large sample of stars, pointing solidly to a solution of the puzzling problem of the function governing the distribution of stellar rotational velocity.Artigo Nonextensive quantum H-theorem(IOP Publishing, 2010-01-18) Anselmo, Dory Hélio Aires de Lima; Silva, R.; Alcaniz, J. S.A proof of the quantum H-theorem taking into account nonextensive effects on the quantum entropy SqQ is shown. The positiveness of the time variation of SqQ combined with a duality transformation implies that the nonextensive parameter q lies in the interval [0,2]. It is also shown that the stationary states are described by quantum q-power law extensions of the Fermi-Dirac and Bose-Einstein distributions. Such results reduce to the standard ones in the extensive limit, thereby showing that the nonextensive entropic framework can be harmonized with the quantum distributions contained in the quantum statistics theory