8,142 research outputs found

    Localizing gravity on thick branes: a solution for massive KK modes of the Schroedinger equation

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    We generate scalar thick brane configurations in a 5D Riemannian space time which describes gravity coupled to a self-interacting scalar field. We also show that 4D gravity can be localized on a thick brane which does not necessarily respect Z_2-symmetry, generalizing several previous models based on the Randall-Sundrum system and avoiding the restriction to orbifold geometries as well as the introduction of the branes in the action by hand. We begin by obtaining a smooth brane configuration that preserves 4D Poincar'e invariance and violates reflection symmetry along the fifth dimension. The extra dimension can have either compact or extended topology, depending on the values of the parameters of the solution. In the non-compact case, our field configuration represents a thick brane with positive energy density centered at y=c_2, whereas in the compact case we get pairs of thick branes. We recast as well the wave equations of the transverse traceless modes of the linear fluctuations of the classical solution into a Schroedinger's equation form with a volcano potential of finite bottom. We solve Schroedinger equation for the massless zero mode m^2=0 and obtain a single bound wave function which represents a stable 4D graviton and is free of tachyonic modes with m^2<0. We also get a continuum spectrum of Kaluza-Klein (KK) states with m^2>0 that are suppressed at y=c_2 and turn asymptotically into plane waves. We found a particular case in which the Schroedinger equation can be solved for all m^2>0, giving us the opportunity of studying analytically the massive modes of the spectrum of KK excitations, a rare fact when considering thick brane configurations.Comment: 8 pages in latex. We corrected signs in the field equations, the expressions for the scalar field and the self-interacting potential. Due to the fact that no changes are introduced in the warp factor, the physics of the system remains the sam

    Optimization of supply diversity for the self-assembly of simple objects in two and three dimensions

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    The field of algorithmic self-assembly is concerned with the design and analysis of self-assembly systems from a computational perspective, that is, from the perspective of mathematical problems whose study may give insight into the natural processes through which elementary objects self-assemble into more complex ones. One of the main problems of algorithmic self-assembly is the minimum tile set problem (MTSP), which asks for a collection of types of elementary objects (called tiles) to be found for the self-assembly of an object having a pre-established shape. Such a collection is to be as concise as possible, thus minimizing supply diversity, while satisfying a set of stringent constraints having to do with the termination and other properties of the self-assembly process from its tile types. We present a study of what we think is the first practical approach to MTSP. Our study starts with the introduction of an evolutionary heuristic to tackle MTSP and includes results from extensive experimentation with the heuristic on the self-assembly of simple objects in two and three dimensions. The heuristic we introduce combines classic elements from the field of evolutionary computation with a problem-specific variant of Pareto dominance into a multi-objective approach to MTSP.Comment: Minor typos correcte

    Analytical results for a Bessel function times Legendre polynomials class integrals

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    When treating problems of vector diffraction in electromagnetic theory, the evaluation of the integral involving Bessel and associated Legendre functions is necessary. Here we present the analytical result for this integral that will make unnecessary numerical quadrature techniques or localized approximations. The solution is presented using the properties of the Bessel and associated Legendre functions.Comment: 4 page

    Coexistence Curve Singularities at Critical End Points

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    We report an extensive Monte Carlo study of critical end point behaviour in a symmetrical binary fluid mixture. On the basis of general scaling arguments, singular behaviour is predicted in the diameter of the liquid-gas coexistence curve as the critical end point is approached. The simulation results show clear evidence for this singularity, as well as confirming a previously predicted singularity in the coexistence chemical potential. Both singularities should be detectable experimentally.Comment: 9 pages Revtex, 3 figures. To appear in Phys. Rev. Let

    Pragas quarentenárias A1 e A2 da citricultura baiana.

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    As barreiras fitossanitárias impactam o setor produtivo e comercial de diversos países que pretendem exportar seus produtos agrícolas, em face das exigências que impõem a trânsito internacional de vegetais. Entretanto, essas normativas visam a proteger os importadores do ingresso e disseminação de pragas em seu território. A certificação fitossanitária de origem (CFO) e a permissão de trânsito de vegetais (PTV), documentos que atestam a sanidade e garantem a rastreabilidade das partidas, são exemplos das exigências fitossanitárias interestaduais. A Bahia, segundo lugar no ranking nacional de produção de citros, foi reconhecida pelo Ministério da Agricultura, Pecuária e Abastecimento (MAPA) como área de não ocorrência de várias pragas da citricultura, das quais muitas já foram introduzidas no Estado e estão restritas a microrregiões produtoras. Faz-se necessário avaliar o risco de disseminação e estabelecimento dessas pragas na Bahia, bem como estratégia de prevenção do ingresso daquelas que ainda não ocorrem no Estado.bitstream/item/103892/1/ComunicadoTecnico-156-cristiane-definitivo.pd

    Como a planta de arroz se desenvolve.

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    Planta. Raízes. Caule. Perfilhamento. Folha. Panícula. Espigueta. Flor. Grão. Germinação. Plântula. Fases de crescimento da planta de arroz. Produção de matéria seca. Produção. Características da planta relacionadas com a capacidade de produção. Exigências de radiação solar pela cultura do arroz.bitstream/item/100485/1/Encarte.pdfEncarte

    Private Outsourcing of Polynomial Evaluation and Matrix Multiplication using Multilinear Maps

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    {\em Verifiable computation} (VC) allows a computationally weak client to outsource the evaluation of a function on many inputs to a powerful but untrusted server. The client invests a large amount of off-line computation and gives an encoding of its function to the server. The server returns both an evaluation of the function on the client's input and a proof such that the client can verify the evaluation using substantially less effort than doing the evaluation on its own. We consider how to privately outsource computations using {\em privacy preserving} VC schemes whose executions reveal no information on the client's input or function to the server. We construct VC schemes with {\em input privacy} for univariate polynomial evaluation and matrix multiplication and then extend them such that the {\em function privacy} is also achieved. Our tool is the recently developed {mutilinear maps}. The proposed VC schemes can be used in outsourcing {private information retrieval (PIR)}.Comment: 23 pages, A preliminary version appears in the 12th International Conference on Cryptology and Network Security (CANS 2013
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