14,673 research outputs found

    Entanglement Swapping: Entangling Atoms That Never Interacted

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    In this paper we discuss four different proposals of entangling atomic states of particles which have never interacted. The experimental realization proposed makes use of the interaction of Rydberg atoms with a micromaser cavity prepared in either a coherent state or in a superposition of the zero and one field Fock states. We consider atoms in either a three-level cascade or lambda configurationComment: 17 pages and 2 figure

    Linear scaling computation of the Fock matrix. IX. Parallel computation of the Coulomb matrix

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    We present parallelization of a quantum-chemical tree-code [J. Chem. Phys. {\bf 106}, 5526 (1997)] for linear scaling computation of the Coulomb matrix. Equal time partition [J. Chem. Phys. {\bf 118}, 9128 (2003)] is used to load balance computation of the Coulomb matrix. Equal time partition is a measurement based algorithm for domain decomposition that exploits small variation of the density between self-consistent-field cycles to achieve load balance. Efficiency of the equal time partition is illustrated by several tests involving both finite and periodic systems. It is found that equal time partition is able to deliver 91 -- 98 % efficiency with 128 processors in the most time consuming part of the Coulomb matrix calculation. The current parallel quantum chemical tree code is able to deliver 63 -- 81% overall efficiency on 128 processors with fine grained parallelism (less than two heavy atoms per processor).Comment: 7 pages, 6 figure

    About the ergodic regime in the analogical Hopfield neural networks. Moments of the partition function

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    In this paper we introduce and exploit the real replica approach for a minimal generalization of the Hopfield model, by assuming the learned patterns to be distributed accordingly to a standard unit Gaussian. We consider the high storage case, when the number of patterns is linearly diverging with the number of neurons. We study the infinite volume behavior of the normalized momenta of the partition function. We find a region in the parameter space where the free energy density in the infinite volume limit is self-averaging around its annealed approximation, as well as the entropy and the internal energy density. Moreover, we evaluate the corrections to their extensive counterparts with respect to their annealed expressions. The fluctuations of properly introduced overlaps, which act as order parameters, are also discussed.Comment: 15 page

    O que é vinho de qualidade?

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    bitstream/item/123314/1/bonvivant-v14-n155-p42-dez-2013.pdfPublicado também no informativo A Vindima, v. 6, n. 57, p. 4, nov. 2013

    Towards the Genealogy of Borderline Personality Disorder

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    Introdução: A perturbação borderline da personalidade surge na ausência de uma categoria para classificar pessoas que se encontravam entre o diagnóstico de neurose e psicose e tem, desde o seu nascimento, sofrido modificações na sua definição e aplicação clínica. Objectivos: Este artigo tem por objectivo traçar a genealogia da perturbação borderline da personalidade de modo a ensaiar hipóteses para o surgimento desta categoria diagnóstica. Métodos: Com base numa revisão da literatura, foi efectuada uma leitura crítica da evolução da categoria borderline na psiquiatria. Resultados: A evolução do conceito pode ser definida ao longo de três fases: desde o final do XIX ao início do século XX são usadas múltiplas terminologias e o diagnóstico é heterogéneo; de 1960 a 1980 surge o conceito de organização borderline da personalidade e a sua sistematização segundo a teoria psicanalítica; desde 1980 até à actualidade ocorre a entrada na DSM III e a homogeneização do diagnóstico sob a égide da biopsiquiatria. Os limites entre as diferentes fases do conceito são fluídos e dependem das condições socio-políticas associadas. Para o nascimento da doença em análise são ensaiadas várias hipóteses: criação de novos sujeitos-psíquicos, melhor acesso à saúde mental e identificação da doença, governamentalidade biopolítica, identificação de comportamentos anteriormente não considerados patológicos, descontinuidade social, nova expressão de sofrimento e contágio social. Conclusão: A perturbação borderline da personalidade resulta de práticas, representações, interacções sociais e modos de subjectificação, onde ocorre uma nova relação entre as ideias de corpo e identidade.info:eu-repo/semantics/publishedVersio

    Comparison of Four Space Propulsion Methods for Reducing Transfer Times of Manned Mars Mission

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    We assess the possibility of reducing the travel time of a manned mission to Mars by examining four different propulsion methods, and keeping the mass at departure under 2,500 tonnes, for a fixed architecture. We evaluated representative systems of three different state of the art technologies (chemical, nuclear thermal, and electric), and one advance technology, the "Pure Electro-Magnetic Thrust" (PEMT) concept (proposed by Rubbia). A mission architecture mostly based on the Design Reference Architecture 5.0 is assumed in order to estimate the mass budget, that influences the performance of the propulsion system. Pareto curves of the duration of the mission and time of flight versus mass of mission are drawn. We conclude that the ion engine technology, combined with the classical chemical engine, yields the shortest mission times for this architecture with the lowest mass, and that chemical propulsion alone is the best to minimise travel time. The results obtained using the PEMT suggest that it could be a more suitable solution for farther destinations than Mars.Comment: Change in title, abstract and presentation so to clarify the main results. 14 pages, 7 figures and 2 table
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