939 resultados para Lightcone fluctuation
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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O objetivo deste trabalho foi determinar a taxa de fecundação de dendezeiros, após introdução de Elaeidobius kamerunicus, no Sul da Bahia, e a flutuação populacional, distribuição espacial e a influência de fatores meteorológicos sobre E. kamerunicus e E. subvittatus. Análises físicas de 12 mil espiguetas de dendezeiros foram realizadas em 2004-2006. Na avaliação da relação entre a temperatura média mensal e o total mensal de indivíduos de E. kamerunicus e E. subvittatus, utilizou-se a correlação de Pearson. A taxa de fecundação foi de 79,4%, um incremento de 19% quando comparado aos dendezeiros polinizados apenas por E. subvittatus. Plantios comerciais de dendezeiros em Ituberá e Nazaré, BA, apresentaram taxas médias de fecundações de 76%. E. kamerunicus foi dominante nos plantios de dendezeiro de Una, BA. Populações de E. kamerunicus sobrepujaram as de E. subvittatus, em todos os municípios onde existem grandes maciços de dendezeiros subespontâneos. No entanto, em Itapebi, BA, as populações de E. subvittatus superaram as de E. kamerunicus. A temperatura e a precipitação pluvial afetam a atividade de vôo e densidade populacional de E. subvittatus.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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O tapir ou anta, descrito como o maior mamífero terrestre brasileiro, pertence à ordem Perissodactila, subordem Hippomorfa, superfamília Tapiroidea e família Tapiridae. Na floresta úmida está envolvido com a dispersão de sementes em função das características do tubo digestivo. O acompanhamento do ciclo estral permite avaliar e compreender a atividade reprodutiva nas espécies animais. Nos animais silvestres, o estresse da contenção pode interferir na própria ciclicidade gonadal, uma das alternativas é o acompanhamento dos hormônios gonadais nas excretas. Buscamos neste trabalho o acompanhamento periódico da atividade gonadal através da quantificação de progesterona no leite. Utilizamos uma fêmea recém-parida no Zoológico de Araçatuba, da qual colhemos leite, esfregaço vaginal e temperatura retal. A progesterona foi quantificada por radioimunoensaio de fase sólida (Coat-a-Count, DPC®) com curva padrão fornecida pela F.A.O. O ensaio mostrou sensibilidade de 1,25 nmol/l com coeficiente de variação intra-ensaio de 15,36%. Durante a fase de lactação, a fêmea não apresentou níveis detectáveis de progesterona por 158 dias (de novembro a abril). O primeiro pico de produção foi de 2,3 nmol/l e apresentou duração de 5 dias. O segundo pico de 3,54 nmol/l teve uma duração de 23 dias. Setenta e quatro dias após o aparecimento da progesterona no leite a lactação cessou. Podemos concluir que a fêmea de tapir apresentou um período de anestro lactacional de aproximadamente 5 meses e voltou a ciclar no outono (abril) sugerindo pouca influência do fotoperíodo. A quantificação da progesterona no leite mostrou-se útil para o acompanhamento do ciclo estral na espécie, porém a variação da citologia vaginal e temperatura retal não apresentaram correlação com os níveis hormonais.
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A região do litoral norte do Estado de São Paulo registrou 14, 30 e 104 casos de leishmaniose tegumentar americana nos anos de 1993, 1994 e 1995 respectivamente. Com objetivo de caracterizar a fauna e a distribuição sazonal e horária das espécies de flebotomíneos foram realizadas coletas quinzenais de formas adultas durante o período de dezembro de 1995 a novembro de 1996, utilizando-se armadilhas luminosas do tipo CDC, no interior da residência, no peridomicílio e na mata durante 12 horas a partir do crepúsculo vespertino. No peridomicílio foi utilizada, durante 6 horas também a partir do crepúsculo vespertino, armadilha de Shannon instalada a 100 metros da casa. A cada 3 meses esta armadilha foi utilizada durante 12 horas. Foram observadas flutuações das densidades populacionais, bem como as ocorrências intra e extradomiciliar das espécies predominantes. Lutzomyia intermedia foi a espécie mais abundante nas diferentes armadilhas utilizadas e nos ambientes investigados.
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The primary role of the respiratory system is to ensure adequate tissue oxygenation, eliminate carbon dioxide and help to regulate acid-base status. To maintain this homeostasis, amphibians possess an array of receptors located at peripheral and central chemoreceptive sites that sense respiration-related variables in both internal and external environments. As in mammals, input from these receptors is integrated at central rhythmogenic and pattern-forming elements in the medulla in a manner that meets the demands determined by the environment within the constraints of the behavior and breathing pattern of the animal. Also as in mammals, while outputs from areas in the midbrain may modulate respiration directly, they do not play a significant role in the production of the normal respiratory rhythm. However, despite these similarities, the breathing patterns of the two classes are different: mammals maintain homeostasis of arterial blood gases through rhythmic and continuous breathing, whereas amphibians display an intermittent pattern of aerial respiration. While the latter is also often rhythmic, it allows a degree of fluctuation in key respiratory variables that has led some to suggest that control is not as tight in these animals. In this review we will focus specifically on recent advances in studies of the control of ventilation in anuran amphibians. This is the group of amphibians that has attracted the most recent attention from respiratory physiologists. (c) 2006 Elsevier B.V. All rights reserved.
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A number of amphibians and reptiles have cyclic behavior, becoming inactive with the coming of the dry season. In South America this pattern of activity is common, particularly in savannah-like vegetation. During the dry season amphibians burrow into the mud or soil, and either form a cocoon or increase the osmotic concentration of body fluids to reduce evaporative water loss. Some phyllomedusid tree frogs coat their body surface with skin secretion and excrete uric acid to minimize water loss. Reptiles also retreat into shelter deep enough to avoid temperature fluctuation during estivation or reduce metabolic response to temperature. Reduction of temperature sensitivity of the metabolism seems to be a strategy common to estivating amphibians and reptiles. Despite seasonal change of the environment, some species of reptiles are active all year round.
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The temperature dependence has been investigated for the photoinduced birefringence in Langmuir-Blodgett (LB) films from the azocopolymer 4-[N- ethyl -N-(2-hydroxyethyl)] amino-2'-chloro-4'-nitroazobenzene (MMA-DR13) mixed with cadmium stearate. The buildup and relaxation of the birefringence in the range from 20 to 296 K were fitted with a Kohlrausch-Williams-Watts (KWW) function, with a beta-value of 0.78-0.98 for the build-up and 0.18-0.27 for the decay. This is consistent with a distribution of time constants for the kinetics of the birefringence processes. The maximum birefringence increased with increasing temperature up to 120 K because the free volume fluctuation also increased with temperature. Above 120 K, the birefringence decreased with temperature as thermal diffusion dominates. In the latter range of temperature, an Arrhenius behavior is inferred for both build-up and decay of birefringence. In each case two activation energies were obtained: 0.8 and 5 kJ/mol for the build-up and 10 and 30 kJ/mol for the decay. The energies for the build-up are much lower than those associated with motion of the polymer chain, which means that the dynamics is governed by the orientation of the chromophores. For the decay, local motion of lateral groups of the polymer chains becomes important as the activation energies are within the range of gamma-relaxation energies. (C) 2003 Elsevier B.V. B.V. All rights reserved.
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The effect of lead excess on the pyrochlore-type formation in Pb(Mg1/3Nb2/3)O-3 (PMN) powders has been investigated. The polymeric precursor method was used in the synthesis of the columbite in association to the partial oxalate method to synthesize the PMN powder samples. Structure refinement of the columbite precursor and PMN powders was carried out using the Rietveld method. The quantitative phase analysis showed that the amount of perovskite phase is not affected by PbO excess, but a great excess drives the pyrochlore-type formation so that 3 wt.% of PbO causes the predominance of Mg-containing pyrochlore phase. Using the refined data obtained from the Rietveld refinement, the compositional fluctuation in the perovskite phase was calculated from Nb/Mg ratio values and Pb occupation factor. Mg inclusion occurs concomitant with Ph one into PMN perovskite phase and this effect is directed by PbO excess during powder synthesis. (C) 2003 Elsevier B.V. All rights reserved.
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We study the statistical distribution of quantum energy splittings due to a dynamical tunneling. The system. The annular billiard, has whispering quasimodes due to a discrete symmetry that exists even when chaos is present in the underlying classical dynamics. Symmetric and antisymmetric combinations of these quasimodes correspond to quantum doublet states whose degeneracies decrease as the circles become more eccentric. We construct numerical ensembles composed of splittings for two distinct regimes, one which we call semiclassical for high quantum numbers and high energies where the whispering regions are connected by chaos, and other which we call quantal for low quantum numbers, low energies, and near integrable where dynamical tunneling is not a dominant mechanism. In both cases we observe a variation on the fluctuation amplitudes, but their mean behaviors follow the formula of Leyvraz and Ullmo [J. Phys. A 29, 2529 (1996)]. A description of a three-level collision involving a doublet and a singlet is also provided through a numerical example.
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One of the major problems facing Blast Furnaces is the occurrence of cracks in taphole mud, as the underlying causes are not easily identifiable. The absence of this knowledge makes it difficult the use of conventional techniques for predictability and mitigation. This paper will address the application of Probabilistic Neural Network using the Matlab software as a means to detect and control such cracks. The most relevant BF operational variables were picked through the statistic tool "Principal Component Analysis - PCA." Based upon the selection of these variables a probabilistic neural network was built. A set of BF operational data, consisting of 30 controlling variables, was divided into 2 groups, one of which for network training, and the other one to validate the neural network. The neural network got 98% of the cases right. The results show the effectiveness of this tool for crack prediction in relation to clay intrinsic properties and as a result of the fluctuation in operational variables.
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The spittlebugs are considered the most important pests in tropical pastures. The damages caused by these insects decrease the production of pastures. The objective this work was to study the population dynamics of Notozulia entreriana, from June 2007 to June 2008, and the correlation with meteorological and environmental factors (rainfall, temperature, daily solar radiation and pasture height). Therefore, sampled were made in three areas of grassland in the municipality of Marechal Candido Rondon-PR. Sampling of adults and nymphs was made. Also we determined which species of spittlebugs (Hemiptera: Cercopidae) occur in the western region of Parana State. The population fluctuation of N. entreriana showed four peaks during the period of favorable development - spring / summer. The daily solar radiation had a higher correlation with the population. Rainfall, temperature and pasture height had little correlation with the population dynamics. The species that occurred with greater abundance was N. entreriana, representing 88.4% of the total insects collected in western of Parana State.