14,659 research outputs found

    Qualitative and quantitative features of orbits of massive particles and photons moving in Wyman geometry

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    The Wyman's solution depends on two parameters, the mass MM and the scalar charge σ\sigma. If one fixes MM to a positive value, say M0M_0, and let σ2\sigma^2 take values along the real line it describes three different types of spacetimes. For σ2>0\sigma^2 >0 the spacetimes are naked singularities, for σ2=0\sigma^2 = 0 one has the Schwarzschild black hole of mass M0M_0 and finally for M02σ2<0-M_0^2 \leq \sigma^2 < 0 one has wormhole spacetimes. In the present work, we shall study qualitative and quantitative features of orbits of massive particles and photons moving in the naked singularity and wormhole spacetimes of the Wyman solution. These orbits are the timelike geodesics for massive particles and null geodesics for photons. Combining the four geodesic equations with an additional equation derived from the line element, we obtain an effective potential for the massive particles and a different effective potential for the photons. We investigate all possible types of orbits, for massive particles and photons, by studying the appropriate effective potential. We notice that for certain values of σ2>0\sigma^2 >0, there is an infinity potential wall that prevents both massive particles and photons ever to reach the naked singularity. We notice, also, that for certain values of M02σ2<0-M_0^2 \leq \sigma^2 < 0, the potential is finite everywhere, which allows massive particles and photons moving from one wormhole asymptotically flat region to the other. We also compute the radial timelike and null geodesics for massive particles and photons, respectively, moving in the naked singularities and wormholes spacetimes.Comment: 20 pages, 8 ps figures, IOPLaTe

    Alterações nas características químicas de um latossolo amarelo sob sistemas agroflorestais com cupuaçuzeiro no município de Presidente Figueiredo, AM.

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    Avaliação de algumas características químicas de um latossolo amarelo distrófico, sob dois sistemas agroflorestais com três tipos de manejo de adubação, durante oito anos

    Exportação de nutrientes de sistemas agroflorestais através das colheitas - o valor dos resíduos dos frutos amazônicos.

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    O objetivo desse trabalho foi quantificar a biomassa da colheita de dois modelos de sistemas agroflorestais, implantados em áreas de pastagens degradadas, e suas respectivas exportações de nutrientes através das colheitas

    Desenvolvimento da técnica TRAP (Target region amplification polymorphism) para caracterização genética de guaranazeiro.

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    O objetivo desse trabalho foi desenhar e otimizar a técnica de TRAP (Target Region Amplification Polymorphism) para as aplicações diversas das análises de diversidade genética em guaranazeiro

    Polimorfismo de (GA)n intra e inter SSR em germoplasma mandioca.

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    O objetivo do trabalho foi comparar o polimorfismo de (GA)n Inter e Intra SSR na análise preliminar de acessos de germoplasma mantidos no Campo Experimental do Caldeirão, município de Iranduba
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