984 resultados para wavelet transformation


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Es una de las cuatro unidades del curso de preparación para los exámenes del General Certificate Secondary Education (GCSE). Esta unidad 3 es diferente de las dos unidades anteriores pues sus temas se basan en comprender la importancia de las fuentes en el estudio de la historia y como pueden ser interpretadas de varias maneras, lo que lleva a los historiadores a emitir juicios sobre la utilidad y fiabilidad de la información que proporcionan. Asimismo, se explica que en esta parte del examen del GCSE se conjugan los conocimientos y la información sobre los hechos con los juicios sobre las fuentes históricas.

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Es una de las cuatro unidades del curso de preparación para los exámenes del General Certificate Secondary Education (GCSE). Esta unidad 3 es diferente de las dos unidades anteriores pues sus temas se basan en comprender la importancia de las fuentes en el estudio de la historia y como pueden ser interpretadas de varias maneras, lo que lleva a los historiadores a emitir juicios sobre la utilidad y fiabilidad de la información que proporcionan. Asimismo, se explica que en esta parte del examen del GCSE se conjugan los conocimientos y la información sobre los hechos con los juicios sobre las fuentes históricas.

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Es un análisis exhaustivo de las dimensiones sociales del cambio climático, pues se considera una prioridad para el desarrollo humano aprender a vivir con sus efectos. Se presentan una serie de opciones que puede afrontar la humanidad en esta tarea estrictamente defensiva de adaptación a los riesgos del calentamiento global de la Tierra. Es una obra de referencia para los estudiantes de pregrado y postgrado interesados en los estudios sobre cambio climático, geografía y desarrollo.

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Monográfico con el título: 'Aprendizaje y construcción del conocimiento en la red'. Resumen basado en el de la publicación

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The main premise of Vygotsky’s cultural-historical theory is that to promote learning, and thus development, educators must intervene in, and change, the students’ socio-cultural context. Vygotsky’s theory, however, has been misinterpreted and the opposite approach has been accepted: the teaching is adapted, according to the context. The result is widespread failure in schools. This article reclaims the true transformative meaning of Vygotskian theory and shows how successful schools in several countries implement various actions to transform their social and cultural environment. Data is presented from six case studies of successful schools conducted in five European countries. The analysis shows that these actions improve instrumental learning and, consequently, cognitive development. All these efforts focus on teaching methods that aim to increase the amount that students learn

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A Fluxometria por Laser Doppler (LDF) é uma técnica não invasiva usada para medir o fluxo microvascular da pele humana. No fluxo é possível isolar componentes oscilatórias em gamas de frequências características que se encontram relacionadas com as actividades cardíaca, respiratória, miogénica, simpática e metabólica. A LDF permite assim estudar a fisiologia do fluxo sanguíneo. Neste trabalho foram realizadas medições de LDF nos tornozelos de 9 mulheres saudáveis numa situação de restrição à perfusão, usando uma braçadeira nos tornozelos. Os dados foram analisados com Transformada de Wavelet e Detrended Fluctuation Analysis (DFA) de modo a estudar os rácios das amplitudes das componentes de Wavelet e os respectivos expoentes . Estes parâmetros foram comparados nas situações de repouso, de restrição à perfusão e de recuperação após remoção da braçadeira. Observou-se que durante a restrição à perfusão houve um aumento significativo dos rácios de amplitude e dos expoentes a para as componentes cardíaca, respiratória e miogénica, o que pode reflectir vasoconstrição. Os parâmetros da componente metabólica apresentaram uma diminuição que se pode relacionar com variações na libertação de NO por parte do endotélio. Após a libertação da braçadeira, os parâmetros das componentes respiratória, miogénica e metabólica retornaram aos valores iniciais. Aanálise combinada de Wavelet com DFAoferece uma nova visão sobre a regulação do fluxo microvascular.

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The ITCT-Lagrangian-2K4 (Intercontinental Transport and Chemical Transformation) experiment was conceived with an aim to quantify the effects of photochemistry and mixing on the transformation of air masses in the free troposphere away from emissions. To this end, attempts were made to intercept and sample air masses several times during their journey across the North Atlantic using four aircraft based in New Hampshire (USA), Faial (Azores) and Creil (France). This article begins by describing forecasts from two Lagrangian models that were used to direct the aircraft into target air masses. A novel technique then identifies Lagrangian matches between flight segments. Two independent searches are conducted: for Lagrangian model matches and for pairs of whole air samples with matching hydrocarbon fingerprints. The information is filtered further by searching for matching hydrocarbon samples that are linked by matching trajectories. The quality of these "coincident matches'' is assessed using temperature, humidity and tracer observations. The technique pulls out five clear Lagrangian cases covering a variety of situations and these are examined in detail. The matching trajectories and hydrocarbon fingerprints are shown, and the downwind minus upwind differences in tracers are discussed.

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The soil microflora is very heterogeneous in its spatial distribution. The origins of this heterogeneity and its significance for soil function are not well understood. A problem for understanding spatial variation better is the assumption of statistical stationarity that is made in most of the statistical methods used to assess it. These assumptions are made explicit in geostatistical methods that have been increasingly used by soil biologists in recent years. Geostatistical methods are powerful, particularly for local prediction, but they require the assumption that the variability of a property of interest is spatially uniform, which is not always plausible given what is known about the complexity of the soil microflora and the soil environment. We have used the wavelet transform, a relatively new innovation in mathematical analysis, to investigate the spatial variation of abundance of Azotobacter in the soil of a typical agricultural landscape. The wavelet transform entails no assumptions of stationarity and is well suited to the analysis of variables that show intermittent or transient features at different spatial scales. In this study, we computed cross-variograms of Azotobacter abundance with the pH, water content and loss on ignition of the soil. These revealed scale-dependent covariation in all cases. The wavelet transform also showed that the correlation of Azotobacter abundance with all three soil properties depended on spatial scale, the correlation generally increased with spatial scale and was only significantly different from zero at some scales. However, the wavelet analysis also allowed us to show how the correlation changed across the landscape. For example, at one scale Azotobacter abundance was strongly correlated with pH in part of the transect, and not with soil water content, but this was reversed elsewhere on the transect. The results show how scale-dependent variation of potentially limiting environmental factors can induce a complex spatial pattern of abundance in a soil organism. The geostatistical methods that we used here make assumptions that are not consistent with the spatial changes in the covariation of these properties that our wavelet analysis has shown. This suggests that the wavelet transform is a powerful tool for future investigation of the spatial structure and function of soil biota. (c) 2006 Elsevier Ltd. All rights reserved.

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How do organizations previously dominated by the state develop dynamic capabilities that would support their growth in a competitive market economy? We develop a theoretical framework of organizational transformation that explains the processes by which organizations learn and develop dynamic capabilities in transition economies. Specifically, the framework theorizes about the importance of, and inter-relationships between, leadership, organizational learning, dynamic capabilities, and performance over three stages of transformation. Propositions derived from this framework explain the pre-conditions enabling organizational learning, the linkages between types of learning and functions of dynamic capabilities, and the feedback from dynamic capabilities to organizational learning that allows firms in transition economies to regain their footing and build long-term competitive advantage. We focus on transition contexts, where these processes have been magnified and thus offer new insights into strategizing in radically altered environments.