879 resultados para Response time (computer systems)
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INTRODUÇÃO:O exercício prévio tem importantes implicações na preparação de atletas antes de competições.OBJETIVO:Analisar o efeito de um exercício prévio realizado no domínio pesado no pico de torque (PTORQUE) medido após exercício severo.MÉTODOS:Participaram deste estudo 14 homens ativos (idade: 26 ± 4 anos, VO2max: 44 ± 6 mLO2.min-1.kg-1) que realizaram sete testes em dias diferentes: a) teste progressivo de rampa para determinação do VO2max e da potência pico; b) quatro testes de carga constante para determinação da potência crítica, capacidade de trabalho anaeróbio e potência correspondente ao tempo de exaustão de 3 min (PTLim3min) e; c) dois testes de carga constante de 2 min na PTLim3min seguidos por um sprint all out de 10 s, a fim de medir o PTORQUE. Este último protocolo foi realizado com (EP) e sem (CON) a realização de um exercício prévio pesado.RESULTADOS:O PTORQUE foi significantemente maior após o EP (101 ± 30 Nm) em relação à condição CON (95 ± 23 Nm). O tempo da resposta médio (TRM) do VO2 foi significantemente menor após o EP (24 ± 7 s) em relação à condição CON (32 ± 10 s). A amplitude primária do VO2 aumentou significantemente após o EP (2598 ± 421 mLO2.min-1) em relação à condição CON (2184 ± 246 mLO2.min-1). O déficit de O2 foi significantemente menor após o exercício prévio (980 ± 432 mLO2) em relação à condição CON (1273 ± 398 mLO2). Houve correlação significante entre a variação do déficit de O2 com a do PTORQUE (r = 0,53) e da variação do TRM com a do PTORQUE (r = 0,53).CONCLUSÃO:Pode-se concluir que o PTORQUE é maior após exercício aeróbio de curta duração precedido do EP. Deste modo, esta estratégia pode ser interessante como preparação para algumas competições esportivas.
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Pós-graduação em Ciência da Computação - IBILCE
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Far from the continental margin, drainage basins in Central Amazonia should be in topographic steady state; but they are not. Abandoned remnant fluvial valleys up to hundreds of square kilometers in size are observed throughout Amazonia, and are evidence of significant landscape reorganization. While major Late Miocene drainage shifts occurred due to initiation of the transcontinental Amazon River, local landscape change has remained active until today. Driven either by dynamic topography, tectonism, and/or climatic fluctuations, drainage captures in Amazonia provide a natural experiment for assessing the geomorphic response of low-slope basins to sudden, capture related base-level falls. This paper evaluates the timing of geomorphic change by examining a drainage capture event across the Baependi fault scarp involving the Cuieiras and TarumA-Mirim River basins northwest of the city of Manaus in Brazil. A system of capture-related knickpoints was generated by base-level fall following drainage capture; through numerical modeling of their initiation and propagation, the capture event is inferred to have occurred between the middle and late Pleistocene, consistent with other studies of landscape change in surrounding areas. In low-slope settings like the Amazon River basin, base-level fall can increase erosion rates by more than an order of magnitude, and moderate to large river basins can respond to episodes of base-level fall over timescales of tens to hundreds of thousands of years. Copyright (c) 2013 John Wiley & Sons, Ltd.
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Introduction: In the Web environment, there is a need for greater care with regard to the processing of descriptive and thematic information. The concern with the recovery of information in computer systems precedes the development of the first personal computers. Models of information retrieval have been and are today widely used in databases specific to a field whose scope is known. Objectives: Verify how the issue of relevance is treated in the main computer models of information retrieval and, especially, as the issue is addressed in the future of the Web, the called Semantic Web. Methodology: Bibliographical research. Results: In the classical models studied here, it was realized that the main concern is retrieving documents whose description is closest to the search expression used by the user, which does not necessarily imply that this really needs. In semantic retrieval is the use of ontologies, feature that extends the user's search for a wider range of possible relevant options. Conclusions: The relevance is a subjective judgment and inherent to the user, it will depend on the interaction with the system and especially the fact that he expects to recover in your search. Systems that are based on a model of relevance are not popular, because it requires greater interaction and depend on the user's disposal. The Semantic Web is so far the initiative more efficient in the case of information retrieval in the digital environment.
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Pós-graduação em Engenharia Mecânica - FEB
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Huge image collections are becoming available lately. In this scenario, the use of Content-Based Image Retrieval (CBIR) systems has emerged as a promising approach to support image searches. The objective of CBIR systems is to retrieve the most similar images in a collection, given a query image, by taking into account image visual properties such as texture, color, and shape. In these systems, the effectiveness of the retrieval process depends heavily on the accuracy of ranking approaches. Recently, re-ranking approaches have been proposed to improve the effectiveness of CBIR systems by taking into account the relationships among images. The re-ranking approaches consider the relationships among all images in a given dataset. These approaches typically demands a huge amount of computational power, which hampers its use in practical situations. On the other hand, these methods can be massively parallelized. In this paper, we propose to speedup the computation of the RL-Sim algorithm, a recently proposed image re-ranking approach, by using the computational power of Graphics Processing Units (GPU). GPUs are emerging as relatively inexpensive parallel processors that are becoming available on a wide range of computer systems. We address the image re-ranking performance challenges by proposing a parallel solution designed to fit the computational model of GPUs. We conducted an experimental evaluation considering different implementations and devices. Experimental results demonstrate that significant performance gains can be obtained. Our approach achieves speedups of 7x from serial implementation considering the overall algorithm and up to 36x on its core steps.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Synchronization in nonlinear dynamical systems, especially in chaotic systems, is field of research in several areas of knowledge, such as Mechanical Engineering and Electrical Engineering, Biology, Physics, among others. In simple terms, two systems are synchronized if after a certain time, they have similar behavior or occurring at the same time. The sound and image in a film is an example of this phenomenon in our daily lives. The studies of synchronization include studies of continuous dynamic systems, governed by differential equations or studies of discrete time dynamical systems, also called maps. Maps correspond, in general, discretizations of differential equations and are widely used to model physical systems, mainly due to its ease of computational. It is enough to make iterations from given initial conditions for knowing the trajectories of system. This completion of course work based on the study of the map called ”Zaslavksy Web Map”. The Zaslavksy Web Map is a result of the combination of the movements of a particle in a constant magnetic field and a wave electrostatic propagating perpendicular to the magnetic field. Apart from interest in the particularities of this map, there was objective the deepening of concepts of nonlinear dynamics, as equilibrium points, linear stability, stability non-linear, bifurcation and chaos
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Pós-graduação em Ciência da Computação - IBILCE
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Engenharia Elétrica - FEIS
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Pós-graduação em Ciência da Computação - IBILCE
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)