Revista de Filosofía. México, Universidad Iberoamericana, año XVI, Nº 47-48, mayo-diciembre de 1983.

Fil: Yerga de Ysaguirre, M. C.. Universidad Nacional de Cuyo. Facultad de Filosofía y Letras

Sea surface temperatures during Marine Isotope Stage (MIS) 11

The Marine Isotope Stage (MIS) 11 (424-374 ka) was characterized by a protracted deglaciation and an unusually long climatic optimum. It remains unclear to what degree the climate development during this interglacial reflects the unusually weak orbital forcing or greenhouse gas trends. Previously, arguments about the duration and timing of the MIS11 climatic optimum and about the pace of the deglacial warming were based on a small number of key records, which appear to show regional differences. In order to obtain a global signal of climate evolution during MIS11, we compiled a database of 78 sea surface temperature (SST) records from 57 sites spanning MIS11, aligned these individually on the basis of benthic (N = 28) or planktonic (N = 31) stable oxygen isotope curves to a common time frame and subjected 48 of them to an empirical orthogonal function (EOF) analysis. The analysis revealed a high commonality among all records, with the principal SST trend explaining almost 49% of the variability. This trend indicates that on the global scale, the surface ocean underwent rapid deglacial warming during Termination V, in pace with carbon dioxide rise, followed by a broad SST optimum centered at ~410 kyr. The second EOF, which explained ~18% of the variability, revealed the existence of a different SST trend, characterized by a delayed onset of the temperature optimum during MIS11 at ~398 kyr, followed by a prolonged warm period lasting beyond 380 kyr. This trend is most consistently manifested in the mid-latitude North Atlantic and Mediterranean Sea and is here attributed to the strength of the Atlantic meridional overturning circulation. A sensitivity analysis indicates that these results are robust to record selection and to age-model uncertainties of up to 3-6 kyr, but more sensitive to SST seasonal attribution and SST uncertainties >1 °C. In order to validate the CCSM3 (Community Climate System Model, version 3) predictive potential, the annual and seasonal SST anomalies recorded in a total of 74 proxy records were compared with runs for three time slices representing orbital configuration extremes during the peak interglacial of MIS11. The modeled SST anomalies are characterized by a significantly lower variance compared to the reconstructions. Nevertheless, significant correlations between proxy and model data are found in comparisons on the seasonal basis, indicating that the model captures part of the long-term variability induced by astronomical forcing, which appears to have left a detectable signature in SST trends.

A time-slice study in Heinrich Stadial 1 and Mid Holocene sediment cores off northern Senegal

Sediment dynamics in limnic, fluvial and marine environments can be assessed by granulometric and rock-magnetic methodologies. While classical grain-size analysis by sieving or settling mainly bears information on composition and transport, the magnetic mineral assemblages reflect to a larger extent the petrology and weathering conditions in the sediment source areas. Here, we combine both methods to investigate Late Quaternary marine sediments from five cores along a transect across the continental slope off Senegal. This region near the modern summer Intertropical Convergence Zone is particularly sensitive to climate change and receives sediments from several aeolian, fluvial and marine sources. From each of the investigated five GeoB sediment cores (494-2956 m water depth) two time slices were processed which represent contrasting climatic conditions: the arid Heinrich Stadial 1 (~ 15 kyr BP) and the humid Mid Holocene (~ 6 kyr BP). Each sediment sample was split into 16 grain-size fractions ranging from 1.6 to 500 µm. Concentration and grain-size indicative magnetic parameters (susceptibility, SIRM, HIRM, ARM and ARM/IRM) were determined at room temperature for each of these fractions. The joint consideration of whole sediment and magnetic mineral grain-size distributions allows to address several important issues: (i) distinction of two aeolian sediment fractions, one carried by the north-easterly trade winds (40-63 µm) and the other by the overlying easterly Harmattan wind (10-20 µm) as well as a fluvial fraction assigned to the Senegal River (< 10 µm); (ii) identification of three terrigenous sediment source areas: southern Sahara and Sahel dust (low fine-grained magnetite amounts and a comparatively high haematite content), dust from Senegalese coastal dunes (intermediate fine-grained magnetite and haematite contents) and soils from the upper reaches of the Senegal River (high fine-grained magnetite content); (iii) detection of partial diagenetic dissolution of fine magnetite particles as a function of organic input and shore distance; (iv) analysis of magnetic properties of marine carbonates dominating the grain-size fractions 63-500 µm.

Fragmentos aturdidos. La hibridación genérico-discursiva en 4.48 Psychosis de Sarah Kane

El presente trabajo se propone reflexionar sobre las principales problemáticas en torno a la representación de la subjetividad desplegadas en la obra de la dramaturga británica Sarah Kane a partir del análisis de su último drama, 4.48 Psychosis (1999). Con esta obra Kane lleva al extremo la búsqueda de colapsar ciertos límites para hacer de la forma y del contenido una misma cosa. La naturaleza fragmentaria del texto, la ausencia de trama o anécdota y la imposibilidad de identificar la presencia de uno o más personajes en escena, colaboran en la creación de esa atmósfera densa y ambigua que se correlaciona con el cuadro patológico del yo anticipado en el título de la pieza. Asimismo, la puesta en funcionamiento de estrategias de hibridación genérica, de apropiación, parodia y reescritura de diferentes modalidades discursivas (monólogos líricos, conversaciones entre doctor y paciente, el discurso de los cuestionarios médicos, de la psiquiatría y de las historias clínicas, citas extraídas de literatura de autoayuda o del libro bíblico del Apocalipsis, etc.) se constituye como práctica privilegiada para reflejar el descentramiento y la dispersión del sujeto y el borramiento de los límites entre realidad- ficción, sueño-vigilia, yo-otro

María Inés Saravia de Grossi. Sófocles. Una interpretación de sus tragedias, EDULP (Editorial de la Universidad de La Plata), La Plata, 2007, 406 pp.

Fil: Nelli, María Florencia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.