999 resultados para Duderstadt, James J., 1942-


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Fil: Marone, Gherardo.

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Fil: Peretó Rivas, Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas

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En Argentina, los primeros ensayos de voto directo en las elecciones internas de los partidos políticos tuvieron lugar en las décadas del treinta y el cuarenta del siglo XX. Con anterioridad, los candidatos eran elegidos por notables que imponían sus decisiones en las convenciones partidarias. En este artículo, se plantea analizar su implementación en Córdoba por la UCR y el Partido Demócrata, a partir de una coyuntura cuya relevancia trascendía los límites provinciales: las últimas elecciones parlamentarias nacionales antes del golpe militar de junio de 1943. La reconstrucción historiográfica muestra sus alcances así como las resistencias a la democratización en ambos partidos.

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Within the Scotia Sea, the axis of the Antarctic Circumpolar Current (ACC) is geographically confined, and sediments therefore contain a record of palaeo-flow speed uncomplicated by ACC axis migration. We outline Holocene and Last Glacial Maximum (LGM) current-controlled sedimentation using data from 3.5-kHz profiles, cores and current meter moorings. Geophysical surveys show areas of erosion and deposition controlled by Neogene basement topography. Deposition occurs in mounded sediment drifts or flatter areas, where 500-1000 m of sediment overlies acoustic basement. 3.5-kHz profiles show parallel, continuous sub-bottom reflectors with highest sedimentation rates in the centre of the drifts, and reflectors converging towards marginal zones of non-deposition. Locally, on the flanks of continental blocks (e.g. South Georgia), downslope processes are dominant. The absence of mudwaves on the sediment drifts may result from the unsteadiness of ACC flow. A core transect from the ACC axis south to the boundary with the Weddell Gyre shows a southward decrease in biogenic content, controlled by the Polar Front and the spring sea-ice edge. Both these features lay farther north at LGM. The cores have been dated by relative abundance of the radiolarian Cycladophora davisiana, and by changes in the biogenic Ba content, a palaeoproductivity indicator. Sedimentation rates range from 3 to 17 cm/ka. The grain size of Holocene sediments shows a coarsening trend from south to north, consistent with strongest bottom-current flow near the ACC axis, though interpretation is complicated by the presence of biogenic grains. Year-long current meter records indicate mean speeds from 7 cm/s in the south to 12 cm/s in the north, with benthic storm frequency increasing northwards. LGM sediments are predominantly terrigenous and show a clearer northward-coarsening trend, with well-sorted silts in the northern Scotia Sea. Assuming a constant terrigenous source, this implies stronger ACC flow at the LGM, contrasting with weaker Weddell Gyre flow deduced from earlier work.

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Fil: Amícola, José. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación. Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET); Argentina.