4,809 research outputs found

    Comment on: Reply to comment on `Perfect imaging without negative refraction'

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    Whether or not perfect imaging is obtained in the mirrored version of Maxwell's fisheye lens is debated in the comment/reply sequence [Blaikie-2010njp, Leonhardt-2010njp] discussing Leonhardt's original paper [Leonhardt-2009njp]. Here we show that causal solutions can be obtained without the need for an "active localized drain", contrary to the claims in [Leonhardt-2010njp].Comment: v2 (added MEEP ctl file), v3 (publisher statement

    Sistema coletor de frutos de macaúba.

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    Este trabalho teve como objetivo avaliar a qualidade do óleo na polpa de frutos de macaúba em função do tempo de permanência de frutos no campo mantido em sistema de coletores/contentores

    Características químicas e bioquímicas de frutos de macaúbas: maturação uniforme no cacho.

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    Para contribuir com conhecimento sobre a maturação de frutos de macauba, neste trabalho foram investigados aspectos de composição e atividade enzimática em frutos de macaúba dispostos nas porções apical, mediana e distal do cacho

    Four Poynting Theorems

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    The Poynting vector is an invaluable tool for analysing electromagnetic problems. However, even a rigorous stress-energy tensor approach can still leave us with the question: is it best defined as \Vec{E} \cross \Vec{H} or as \Vec{D} \cross \Vec{B}? Typical electromagnetic treatments provide yet another perspective: they regard \Vec{E} \cross \Vec{B} as the appropriate definition, because \Vec{E} and \Vec{B} are taken to be the fundamental electromagnetic fields. The astute reader will even notice the fourth possible combination of fields: i.e. \Vec{D} \cross \Vec{H}. Faced with this diverse selection, we have decided to treat each possible flux vector on its merits, deriving its associated energy continuity equation but applying minimal restrictions to the allowed host media. We then discuss each form, and how it represents the response of the medium. Finally, we derive a propagation equation for each flux vector using a directional fields approach; a useful result which enables further interpretation of each flux and its interaction with the medium.Comment: 8 pages. Updated slightly from EJP versio

    Uniformidade de maturação dos frutos no cacho de macaúbas nativas do pantanal e cerrado.

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    o presente trabalho teve como objetivo avaliar a uniformidade de maturação dos frutos no cacho em macaúbas de ocorrência natural nos biomas Pantanal e Cerrado
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