Alternate islands of multiple isochronous chains in wave-particle interactions

We analyze the dynamics of a relativistic particle moving in a uniform magnetic field and perturbed by a standing electrostatic wave. We show that a pulsed wave produces an infinite number of perturbative terms with the same winding number, which may generate islands in the same region of phase space. As a consequence, the number of isochronous island chains varies as a function of the wave parameters. We observe that in all the resonances, the number of chains is related to the amplitude of the various resonant terms. We determine analytically the position of the periodic points and the number of island chains as a function of the wave number and wave period. Such information is very important when one is concerned with regular particle acceleration, since it is necessary to adjust the initial conditions of the particle to obtain the maximum acceleration.Comment: Submitte

Proposta metodológica para avaliação da efetividade das políticas sociais para agricultores familiares do Estado de Goiás.

O objetivo principal desse artigo é realizar uma revisão bibliográfica e uma proposta metodológica para avaliar as efetividades sociais das políticas públicas para os agricultores familiares do estado de Goiás. Os programas escolhidos pelas suas representatividades sociais e econômicas para o campo e especificamente para a agricultura familiar, sujeito deste trabalho, são o Programa Nacional da Alimentação Escolar (PNAE), o Programas de Aquisição de Alimentos (PAA) da Agricultura Familiar. Também será abordado o Programa Bolsa Família, que não se trata da temática da segurança alimentar, mas que é um programa social de grande inserção no meio rural, especificamente para os agricultores familiares, e com a hipótese que tem efeitos significativos em elementos de segurança alimentar dos agricultores familiares do território em questão

Spin-glass behaviour on random lattices

The ground-state phase diagram of an Ising spin-glass model on a random graph with an arbitrary fraction $w$ of ferromagnetic interactions is analysed in the presence of an external field. Using the replica method, and performing an analysis of stability of the replica-symmetric solution, it is shown that $w=1/2$, correponding to an unbiased spin glass, is a singular point in the phase diagram, separating a region with a spin-glass phase ($w<1/2$) from a region with spin-glass, ferromagnetic, mixed, and paramagnetic phases ($w>1/2$)

Teleportation of entangled states without Bell-state measurement

In a recent paper [Phys. Rev. A 70, 025803 (2004)] we presented a scheme to teleport an entanglement of zero- and one-photon states from a bimodal cavity to another one, with 100% success probability. Here, inspired on recent results in the literature, we have modified our previous proposal to teleport the same entangled state without using Bell-state measurements. For comparison, the time spent, the fidelity, and the success probability for this teleportation are considered.Comment: 4 pages, 1 figure, published in Phys. Rev. A 72, 045802 (2005