330 resultados para Pollard


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The volatile constituents obtained from the pentane extract, using simultaneous distillation-extraction of the flowers of Encyclia vespa and E. fragrans were analysed by GC/ MS. The main volatile components identified in the flowers of E. vespa were terpinen-4-ol (20.3%), verbenone (14.8%), trans-verbenol (13.6%) and x-pinene (11.8%). The major volatiles of the flowers of E. fragrans were terpinen-4-ol (18.3%), (2Z,6E)-farnesol (15.4%) and trans-verbenol (10.2%).

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"Vegeu el resum a l'inici del document del fitxer adjunt."

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El agoritmo Rho de Pollard es uno de los mejores conocidos para resolver el problema del logaritmo discreto. Se trata de una implementación de una paralelización utilizando MPI sobre un clúster. El lector encontrará en este proyecto el algoritmo de paralelización utilizado, así como, un conjunto de pruebas y resultados de la ejecución debidamente analizados.

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Aquest treball final de carrera té com a objectiu l'estudi del problema del logaritme discret i les variants d'un dels possibles i millors atacs que existeixen fins ara: la Rho de Pollard. La implementació d'aquest algorisme s'ha paral·lelitzat sobre un sistema de computació distribuïda peer-to-peer anomenat CoDiP2P. Centrant l'atenció en la seva aplicació sobre el grup multiplicatiu F*p.

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Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly reflect population sizes and trends. This study compares capture-mark-recapture (absolute abundance) and count-index (relative abundance) monitoring methods in three species (Maculinea nausithous and Iolana iolas: Lycaenidae; Minois dryas: Satyridae) in contrasted habitat types. We demonstrate that intraspecific variability in individual detectability under standard monitoring conditions is probably the rule rather than the exception, which questions the reliability of count-based indices to estimate and compare specific population abundance. Our results suggest that the accuracy of count-based methods depends heavily on the ecology and behavior of the target species, as well as on the type of habitat in which surveys take place. Monitoring programs designed to assess the abundance and trends in butterfly populations should incorporate a measure of detectability. We discuss the relative advantages and inconveniences of current monitoring methods and analytical approaches with respect to the characteristics of the species under scrutiny and resources availability.

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Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly reflect population sizes and trends. This study compares capture-mark-recapture (absolute abundance) and count-index (relative abundance) monitoring methods in three species (Maculinea nausithous and Iolana iolas: Lycaenidae; Minois dryas: Satyridae) in contrasted habitat types. We demonstrate that intraspecific variability in individual detectability under standard monitoring conditions is probably the rule rather than the exception, which questions the reliability of count-based indices to estimate and compare specific population abundance. Our results suggest that the accuracy of count-based methods depends heavily on the ecology and behavior of the target species, as well as on the type of habitat in which surveys take place. Monitoring programs designed to assess the abundance and trends in butterfly populations should incorporate a measure of detectability. We discuss the relative advantages and inconveniences of current monitoring methods and analytical approaches with respect to the characteristics of the species under scrutiny and resources availability.

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Trial of William Campbell Preston who was being sued by Miss Madeline Pollard for $50,000 in a breach of promise suit. Accused of promising to marry Miss Pollard and fathering a child and then failing to fulfill his promise. He was found guilty.

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Mode of access: Internet.

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