933 resultados para shape memory alloy,shape memory polymers,effetto memoria di forma


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El texto es un testimonio de dimensiones poco abordadas de Alfredo Pareja: el lado humano del diplomático, del docente en el extranjero, de integrante del Grupo de Guayaquil. Principalmente reseña el nacimiento de un espacio clave de recuperación de la memoria: el Archivo Histórico y la biblioteca especializada del Ministerio de Relaciones Exteriores del Ecuador. Durante tres años, desde 1981, se trabajó en una pequeña oficina, elaborando fichas a partir de manuscritos, pergaminos y demás documentos que allí reposaban, Pareja veía necesario este rescate para la construcción de la historia del país. A partir de ésta y de otras fuentes -coloniales y del siglo XIX, hasta entonces desconocidas o interpretadas de diferente modo por los territorialistas ecuatorianos-, Pareja planteó una nueva interpretación del conflicto limítrofe con Perú, y sostuvo la necesidad de un acuerdo de paz, ello implicaba la aceptación del Protocolo de Río de Janeiro, situación que despertó en su contra muchos comentarios enconados, pero que formó parte de la tesis que prevaleció. El Archivo Histórico «Alfredo Pareja Diezcanseco» se inauguró en julio de 1996.

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La autora lee la novela Hoy empiezo a acordarme, del ecuatoriano Miguel Donoso Pareja, desde la perspectiva de la ficción como un intento –vano–, por parte del narrador, de encontrarse a sí mismo, escritura-travesía hacia un yo que resulta ser siempre “otro”. El personaje pretendería transformar no exclusivamente su realidad, sino la ficción misma en un universo navegable para el lector, la escritura fragmentada en vehículo que no lo lleve a destino alguno, sino a su propio punto de partida. Más que construir una novela de perfección formal, el narrador pretendería involucrar al lector en su propio viaje-búsqueda. Donoso partiría de la escritura como presencia y ausencia, como verdad y mentira, para construir esta novela con historias fragmentadas que se alimentan tanto del recuerdo como del olvido, en un cabal ejercicio de hiperconciencia narrativa.

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Este artículo analiza las representaciones sociales y los marcos de memoria en el Parque Histórico Guayaquil. Los recorridos del parque temático son confrontados con registros provenientes de la investigación histórica y de la narrativa social, con el objeto de iluminar la manera en que se reproducen los imaginarios sociales y culturales sobre la modernización de la ciudad y el rol de las élites económicas y los sectores campesinos en dicho proceso.

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At its most fundamental, cognition as displayed by biological agents (such as humans) may be said to consist of the manipulation and utilisation of memory. Recent discussions in the field of cognitive robotics have emphasised the role of embodiment and the necessity of a value or motivation for autonomous behaviour. This work proposes a computational architecture – the Memory-Based Cognitive (MBC) architecture – based upon these considerations for the autonomous development of control of a simple mobile robot. This novel architecture will permit the exploration of theoretical issues in cognitive robotics and animal cognition. Furthermore, the biological inspiration of the architecture is anticipated to result in a mobile robot controller which displays adaptive behaviour in unknown environments.

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We use an empirical statistical model to demonstrate significant skill in making extended-range forecasts of the monthly-mean Arctic Oscillation (AO). Forecast skill derives from persistent circulation anomalies in the lowermost stratosphere and is greatest during boreal winter. A comparison to the Southern Hemisphere provides evidence that both the time scale and predictability of the AO depend on the presence of persistent circulation anomalies just above the tropopause. These circulation anomalies most likely affect the troposphere through changes to waves in the upper troposphere, which induce surface pressure changes that correspond to the AO.

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There are at least three distinct time scales that are relevant for the evolution of atmospheric convection. These are the time scale of the forcing mechanism, the time scale governing the response to a steady forcing, and the time scale of the response to variations in the forcing. The last of these, tmem, is associated with convective life cycles, which provide an element of memory in the system. A highly simplified model of convection is introduced, which allows for investigation of the character of convection as a function of the three time scales. For short tmem, the convective response is strongly tied to the forcing as in conventional equilibrium parameterization. For long tmem, the convection responds only to the slowly evolving component of forcing, and any fluctuations in the forcing are essentially suppressed. At intermediate tmem, convection becomes less predictable: conventional equilibrium closure breaks down and current levels of convection modify the subsequent response.

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This article explores conflicts over a series of ruins located within Zimbabwe's flagship National Park. The relics have long been regarded as sacred places by local African communities evicted from their vicinity, and have come to be seen as their ethnic heritage. Local intellectuals' promotion of this heritage was an important aspect of a defensive mobilization of cultural difference on the part of a marginalized minority group. I explore both indigenous and colonial ideas about the ruins, the different social movements with which they have been associated and the changing social life they have given the stone relics. Although African and European ideas sometimes came into violent confrontation - as in the context of colonial era evictions - there were also mutual influences in emergent ideas about tribe, heritage and history. The article engages with Pierre Nora's notion of 'sites of memory', which has usefully drawn attention to the way in which ideas of the past are rooted and reproduced in representations of particular places. But it criticizes Nora's tendency to romanticize pre-modern 'memory', suppress narrative and depoliticize traditional connections with the past. Thus, the article highlights the historicity of traditional means of relating to the past, highlighting the often bitter and divisive politics of traditional ritual, myth, kinship, descent and 'being first'. It also emphasizes the entanglement of modern and traditional ideas, inadequately captured by Nora's implied opposition between history and memory. (c) 2005 Elsevier Ltd. All rights reserved.

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For vegetated surfaces, calculation of soil heat flux, G, with the Exact or Analytical method requires a harmonic analysis of below-canopy soil surface temperature, to obtain the shape of the diurnal course of G. When determining G with remote sensing methods, only composite (vegetation plus soil) radiometric brightness temperature is available. This paper presents a simple equation that relates the sum of the harmonic terms derived for the composite radiometric surface temperature to that of belowcanopy soil surface temperature. The thermal inertia, Gamma(,) for which a simple equation has been presented in a companion paper, paper I, is used to set the magnitude of G. To assess the success of the method proposed in this paper for the estimation of the diurnal shape of G, a comparison was made between 'remote' and in situ calculated values from described field sites. This indicated that the proposed method was suitable for the estimation of the shape of G for a variety of vegetation types and densities. The approach outlined in paper I, to obtain Gamma, was then combined with the estimated harmonic terms to predict estimates of G, which were compared to values predicted by empirical remote methods found in the literature. This indicated that the method proposed in the combination of papers I and II gave reliable estimates of G, which, in comparison to the other methods, resulted in more realistic predictions for vegetated surfaces. This set of equations can also be used for bare and sparsely vegetated soils, making it a universally applicable method. (C) 2007 Elsevier B.V. All rights reserved.

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Three experiments investigated irrelevant sound interference of lip-read lists. In Experiment 1, an acoustically changing sequence of nine irrelevant utterances was more disruptive to spoken immediate identification of lists of nine lip-read digits than nine repetitions of the same utterances (the changing-state effect; Jones, Madden, & Miles, 1992). Experiment 2 replicated this finding when lip-read items were sampled with replacement from the nine digits to form the lip-read lists. In Experiment 3, when the irrelevant sound was confined to the retention interval of a delayed recall task, a changing-state pattern of disruption also occurred. Results confirm a changing-state effect in memory for lip-read items but also point to the possibility that, for lip-reading, changing-state effects may occur at an earlier, perceptual stage.

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Four experiments investigate the hypothesis that irrelevant sound interferes with serial recall of auditory items in the same fashion as with visually presented items. In Experiment 1 an acoustically changing sequence of 30 irrelevant utterances was more disruptive than 30 repetitions of the same utterance (the changing-state effect; Jones, Madden, & Miles, 1992) whether the to-be-remembered items were visually or auditorily presented. Experiment 2 showed that two different utterances spoken once (a heterogeneous compound suffix; LeCompte & Watkins, 1995) produced less disruption to serial recall than 15 repetitions of the same sequence. Disruption thus depends on the number of sounds in the irrelevant sequence. In Experiments 3a and 3b the number of different sounds, the "token-set" size (Tremblay & Jones, 1998), in an irrelevant sequence also influenced the magnitude of disruption in both irrelevant sound and compound suffix conditions. The results support the view that the disruption of memory for auditory items, like memory for visually presented items, is dependent on the number of different irrelevant sounds presented and the size of the set from which these sounds are taken. Theoretical implications are discussed.