380 research outputs found

    Natural intensions

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    There is an attractive way to explain representation in terms of adaptivity: roughly, an item R represents a state of affairs S if it has the proper function of co-occurring with S (that is, if the ancestors of R co-occurred with S and this co-occurrence explains why R was selected for, and thus why R exists now). Although this may be an adequate account of the extension or reference of R, what such explanations often neglect is an account of the intension or sense of R: how S is represented by R. No doubt such an account, if correct, would be complex, involving such things as the proper functions of the mechanisms that use R, the mechanisms by which R fulfills its function, and more. But it seems likely that an important step toward such an account would be the identification of the norms that govern this process. The norms of validity and Bayes' Theorem can guide investigations into the actual inferences and probabilistic reasoning that organisms perform. Is there a norm that can do the same for intension-fixing? I argue that before this can be resolved, some problems with the biosemantic account of extension must be resolved. I attempt to do so by offering a complexity-based account of the natural extension of a representation R: for a given set of ancestral co-occurrences Z, the natural extension is the extension of the least complex intension that best covers Z. Minimal description length is considered as a means for measuring complexity. Some advantages of and problems with the account are identified

    Resistance of Rice Varieties to \u3ci\u3eSitophilus oryzae\u3c/i\u3e (Coleoptera: Curculionidae)

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    Abstract Rice, Oryza sativa L. (Poaceae), is one of the world’s most important food crops. Among the insects that damage rice grains, the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), is the most important species. The objective of this study was to identify rice varieties with resistance to S. oryzae as measured by grain feeding damage and S. oryzae reproduction. The rice varieties evaluated were obtained from the germplasm bank of the National Center of Research Rice and Beans, Embrapa, Brazil. The experimental design was completely randomized with 3 replications and 22 treatments (varieties). The varieties Bonança, Esmeralda, and Rio Verde had the antibiosis and/or antixenosis type of resistance, providing high rates of mortality, low rates of adult emergence, and low rates of grain consumption by S. oryzae. The varieties Pepita and Progresso were susceptible, with a high rate of S. oryzae adult emergence and grain consumption. The presence or absence of a fissure in the grain was a major morphological characteristic determining susceptibility or resistance to S. oryzae in rice varieties. Resumo O arroz (Oryza sativa L.; Poaceae) é uma das culturas alimentares mais importantes do mundo. Entre os insetos que danificam os grãos de arroz, o gorgulho do arroz Sitophylus oryzae L. (Coleoptera: Curculionidae) é a espécia mais importante. O objetivo deste trabalho foi identificar variedades de arroz com resistência a S. oryzae. As variedades de arroz avaliadas foram obtidas do banco de germoplasma do Centro Nacional de Pesquisas em Arroz e Feijão, EMBRAPA, Brasil. O delineamento experimental foi inteiramente casualizado com 3 repetições e 22 tratamentos (variedades). As variedades Bonança, Esmeralda e Rio Verde apresentaram resistência do tipo antibiose e/ou antixenose, tendo altas taxas de mortalidade, baixas taxas de emergência de adultos e baixo consumo de grãos por S. oryzae. As variedades Pepita e Progresso são suscetíveis com alta emergência de adultos e consumo de grãos por S. oryzae. A presença ou ausência de fissuras no grão é uma importante característica morfológica para determinar a susceptibilidade ou resistência a S. oryzae em variedades de arroz

    COLEÓPTEROS COLETADOS COM ARMADILHAS LUMINOSAS EM PLANTIO DE Eucalyptus urophylla NA REGIÃO AMAZÔNICA BRASILEIRA

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    RESUMO Este trabalho teve como objetivo estudar a flutuação populacional de espécies da ordem Coleoptera em plantio de Eucalyptus urophylla no município de Almerin, estado do Pará. Esses insetos foram coletados com armadilhas luminosas durante uma noite, a cada quinze dias, de setembro de 1995 a agosto de 1996 com os exemplares identificados de acordo com coleções entomológicas e com a literatura especializada, e divididos em grupos identificados em nível de espécie (INE) ou de família (INF). Foram coletados 132 espécies da ordem Coleoptera, sendo 23 identificadas por espécie e 109 por família, com 2972 e 7187 indivíduos respectivamente. As espécies mais abundantes foram Anomala sp.1, Leucothireus sp. (Scarabaeidae) e Ciclocephala lamminata (Dynastidae) com 93,4% dos indivíduos do primeiro grupo. Carabidae apresentou o maior número de indivíduos (6411) e de espécies (31) dos insetos identificados por família. Todas as coletas apresentaram indivíduos da ordem Coleoptera, com maior número de exemplares dessa ordem em janeiro de 1996

    Geology and hydrogeology of the George Air Force Base vicinity, California

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    Computation in Physical Systems: A Normative Mapping Account

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    The relationship between abstract formal procedures and the activities of actual physical systems has proved to be surprisingly subtle and controversial, and there are a number of competing accounts of when a physical system can be properly said to implement a mathematical formalism and hence perform a computation. I defend an account wherein computational descriptions of physical systems are high-level normative interpretations motivated by our pragmatic concerns. Furthermore, the criteria of utility and success vary according to our diverse purposes and pragmatic goals. Hence there is no independent or uniform fact to the matter, and I advance the ‘anti-realist’ conclusion that computational descriptions of physical systems are not founded upon deep ontological distinctions, but rather upon interest-relative human conventions. Hence physical computation is a ‘conventional’ rather than a ‘natural’ kind
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