14,535 research outputs found
Gravitational waves in the generalized Chaplygin gas model
The consequences of taking the generalized Chaplygin gas as the dark energy
constituent of the Universe on the gravitational waves are studied and the
spectrum obtained from this model, for the flat case, is analyzed. Besides its
importance for the study of the primordial Universe, the gravitational waves
represent an additional perspective (besides the CMB temperature and
polarization anisotropies) to evaluate the consistence of the different dark
energy models and establish better constraints to their parameters. The
analysis presented here takes this fact into consideration to open one more
perspective of verification of the generalized Chapligin gas model
applicability. Nine particular cases are compared: one where no dark energy is
present; two that simulate the -CDM model; two where the gas acts like
the traditional Chaplygin gas; and four where the dark energy is the
generalized Chaplygin gas. The different spectra permit to distinguish the
-CDM and the Chaplygin gas scenarios.Comment: Latex file, 9 pages, 11 figures eps forma
Efeitos de Caracteres Físicos e Químicos Sobre o Teor de Óleo de Frutos de Pupunha.
O objetivo deste estudo foi avaliar a relação entre variáveis físicas e químicas de frutos de pupunha, apontando os efeitos diretos e indiretos de variáveis explicativas sobre a variável principal, teor de óleo
Relações Causa-Efeito entre Caracteres Físicos e Químicos sobre Teor de Fibras em Frutos de Pupunha.
O objetivo deste trabalho foi quantificar e caracterizar a relação entre caracteres explicativos físicos e químicos de frutos de pupunha sobre o caráter tido como principal, percentual de fibra. Desejou-se, também, compreender a inter-relação entre dois complexos de variáveis, químicas e físicas, associadas ao fruto
Localized states at zigzag edges of bilayer graphene
We report the existence of zero energy surface states localized at zigzag
edges of bilayer graphene. Working within the tight-binding approximation we
derive the analytic solution for the wavefunctions of these peculiar surface
states. It is shown that zero energy edge states in bilayer graphene can be
divided into two families: (i) states living only on a single plane, equivalent
to surface states in monolayer graphene; (ii) states with finite amplitude over
the two layers, with an enhanced penetration into the bulk. The bulk and
surface (edge) electronic structure of bilayer graphene nanoribbons is also
studied, both in the absence and in the presence of a bias voltage between
planes.Comment: 4 pages, 5 figure
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