13,766 research outputs found

    Gravitational waves in the generalized Chaplygin gas model

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    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 Λ\Lambda-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 Λ\Lambda-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.

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    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.

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    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

    Selection of Stylosanthes Guianensis for the Cerrados of Brazil

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    Progenies of intervarietal hybrid stylos (Stylosanthes guianensis var.vulgaris x S.guianensis var.pauciflora) with mid-season maturity date (early-and mid-June), high dry matter and seed yields have been identified at the National Beef Cattle Research Center (CNPGC), Campo Grande, MS, Brazil. Dry matter yields of the best selections were comparable to those of the late-flowering control, cv. Mineirão. Several mid-season hybrids produced 150 to 200 kg/ha of seed-inpod and a single plant selection yielded in excess of 300 kg/ha. The high degree of resistance to anthracnose observed in the advanced generations is attributed to the immense genetic diversity of these heterogeneous populations which restricted the development of this highly variable pathogen. Stability of disease resistance of superior mid-season maturity types and their adaptation to a wider range of ecological situations have yet to be assessed in multilocational trials. Grazing productivity experiments are required to determine animal production and persistency of the selected materials

    Development of a Multicross Cultivars of Stylosanthes spp.

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    A synthetic population, referred to as multicross, has been developed from an interspecific mixture of Stylosanthes capitata and S.macrocephala germplasm. This basic population evolved in a farming situation subject to uncontrolled, continuous, heavy grazing. Natural selection and systematically programmed intercrossing among anthracnose-resistant Venezuelan and Brazilian genotypes of S.capitata have played major roles in the subsequent development of this heterogeneous population. Eight anthracnose-resistant Venezuelan and two Brazilian accessions of S.capitata were introgressed into the basic population. Genetic diversity was further increased by adding seed of four selected accessions of S. macrocephala to the synthetic which had already included three accessions from the basic population. The composite was advanced through five generations of bulk seed production to improve its stability, synchronise harvest maturity, and primarily to facilitate natural intercrossing among S.capitata genotypes. The multicross population displayed anthracnose-resistance in the presence of susceptible, infected accessions in field trials conducted over the years since its initial synthesis in 1990
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