25,270 research outputs found

    On Galois-Division Multiple Access Systems: Figures of Merit and Performance Evaluation

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    A new approach to multiple access based on finite field transforms is investigated. These schemes, termed Galois-Division Multiple Access (GDMA), offer compact bandwidth requirements. A new digital transform, the Finite Field Hartley Transform (FFHT) requires to deal with fields of characteristic p, p \neq 2. A binary-to-p-ary (p \neq 2) mapping based on the opportunistic secondary channel is introduced. This allows the use of GDMA in conjunction with available digital systems. The performance of GDMA is also evaluated.Comment: 6 pages, 4 figures. In: XIX Simposio Brasileiro de Telecomunicacoes, 2001, Fortaleza, CE, Brazi

    Deriva genética nos acessos de arroz do banco de germoplasma da Embrapa Arroz e Feijão.

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    O objetivo do trabalho foi verificar a porcentagem de germinação das sementes dos acessos de arroz monitorando a sua viabilidade ao longo do armazenamento para indicação de multiplicação e renovação evitando assim a ocorrência de erosão genética

    Multimode Hong-Ou-Mandel interference

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    We consider multimode two-photon interference at a beam splitter by photons created by spontaneous parametric down-conversion. The resulting interference pattern is shown to depend upon the transverse spatial symmetry of the pump beam. In an experiment, we employ the first-order Hermite-Gaussian modes in order to show that, by manipulating the pump beam, one can control the resulting two-photon interference behavior. We expect these results to play an important role in the engineering of quantum states of light for use in quantum information processing and quantum imaging.Comment: 4 pages, 6 figures, submitted to PR
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