39,309 research outputs found

    Transmission coefficient and two-fold degenerate discrete spectrum of spin-1 bosons in a double-step potential

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    The scattering of spin-1 bosons in a nonminimal vector double-step potential is described in terms of eigenstates of the helicity operator and it is shown that the transmission coefficient is insensitive to the choice of the polarization of the incident beam. Poles of the transmission amplitude reveal the existence of a two-fold degenerate spectrum. The results are interpreted in terms of solutions of two coupled effective Schr\"{o}dinger equations for a finite square well with additional δ\delta -functions situated at the borders.Comment: arXiv admin note: substantial text overlap with arXiv:1203.119

    An alternative theoretical approach to describe planetary systems through a Schrodinger-type diffusion equation

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    In the present work we show that planetary mean distances can be calculated with the help of a Schrodinger-type diffusion equation. The obtained results are shown to agree with the observed orbits of all the planets and of the asteroid belt in the solar system, with only three empty states. Furthermore, the equation solutions predict a fundamental orbit at 0.05 AU from solar-type stars, a result confirmed by recent discoveries. In contrast to other similar approaches previously presented in the literature, we take into account the flatness of the solar system, by considering the flat solutions of the Schrodinger-type equation. The model has just one input parameter, given by the mean distance of Mercury.Comment: 6 pages. Version accepted for publication in Chaos, Solitons & Fractal

    Automatic allocation of safety requirements to components of a software product line

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    Safety critical systems developed as part of a product line must still comply with safety standards. Standards use the concept of Safety Integrity Levels (SILs) to drive the assignment of system safety requirements to components of a system under design. However, for a Software Product Line (SPL), the safety requirements that need to be allocated to a component may vary in different products. Variation in design can indeed change the possible hazards incurred in each product, their causes, and can alter the safety requirements placed on individual components in different SPL products. Establishing common SILs for components of a large scale SPL by considering all possible usage scenarios, is desirable for economies of scale, but it also poses challenges to the safety engineering process. In this paper, we propose a method for automatic allocation of SILs to components of a product line. The approach is applied to a Hybrid Braking System SPL design

    Caracterizacao fisico-quimica dos frutos de tres variedades de tamereiras (Phoenix dactylifera L.) introduzidas no BAG da Embrapa Semi-Arido.

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    O Objetivo do presente trabalho foi estudar alguns parâmetros físico-químicos de tâmaras em estádio tamar, para caracterização de três variedades de tamareiras introduzidas no Banco Ativo de Germoplasma da Embrapa Semi-Árido

    Non-Gaussian two-mode squeezing and continuous variable entanglement of linearly and circularly polarized light beams interacting with cold atoms

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    We investigate how entangled coherent states and superpositions of low intensity coherent states of non-Gaussian nature can be generated via non-resonant interaction between either two linearly or circularly polarized field modes and an ensemble of X-like four-level atoms placed in an optical cavity. We compare our results to recent experimental observations and argue that the non-Gaussian structure of the field states may be present in those systems.Comment: 10 pages, 7 figures, replaced with final published versio
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