Composition and origin of sediments at DSDP Site 54-424

The sediments recovered on Deep Sea Drilling Project Leg 54 appear to be mixtures of the normal pelagic sediments of the area and hydrothermally produced manganese and iron phases. The latter are mineralogically and chemically very similar to phases recovered from surficial sampling of the mounds. The hydrothermal nontronite which is approximately 15 meters thick in the three holes is essentially free of carbonate or detrital contaminants. The basal sediments are similar to the carbonate oozes presently being deposited in the region, but are enriched in Mn and Fe. This enrichment appears to be the result of hydrothermal deposition that took place at or near the spreading center and may not be associated with the mounds formation. Three different hypotheses for the formation of the nontronite layer and the mounds deposits are considered. An initial deposition of a widespread nontronite layer and subsequent diapiric-like movement of the layer into carbonates could account for the observed stratigraphy; however, if this be correct, analogous deposits should be present in other DSDP sites. The second hypothesis - replacement of the normal sediments by nontronite - may be feasible, but the high purity of the nontronite requires dissolution and removal of refractory elements. The third hypothesis, metal deposition in an advancing oxidation gradient, is compatible with submersible observations of the mounds; however, it can account only for the high purity of the nontronite by very rapid deposition of the hydrothermal phases.

Clinamen : Entre libertad y determinismo en De Rerum Natura de Lucrecio

En el presente trabajo se trabaja principalmente en la noción de clinamen, el cual debe entenderse como una desviación azarosa que ocurre en el átomo. Lucrecio argumenta, siguiendo la tradición atomista que lo precede, que el fundamento ontológico de la realidad, es que toda la naturaleza está compuesta de átomos y vacío. El filósofo adhiere a una concepción esencialmente mecanicista del cosmos: el hecho de que el mundo no es una creación de los dioses, hace que la naturaleza sea una constante repetición de los hechos. El concepto de clinamen lleva a Lucrecio plantear, además, el problema del determinismo y la libertad: si todo movimiento es siempre una relación causal con un antes, ¿de dónde viene este poder independiente del destino, a través del cual nos movemos hacia donde la voluntad de cada uno conduce? En segundo lugar, si todos los movimientos de los átomos son inflexiblemente determinados, la capacidad humana para decidir y asumir la responsabilidad de su accionar no podrían explicarse

Análisis y comentarios de fuentes para el estudio de la tierra en los partidos de Chascomús, Ranchos y Monte 1779-1850

El objetivo de esta comunicación es revisar las fuentes utilizadas por los historiadores y relacionarlas mediante series completas de datos en un período más amplio de tiempo, con el fin de abarcar todas las alternativas legales para la adquisición de la tierra. Para fijar espacialmente la cuestión y determinar la ubicación de las parcelas se reconstruye el Registro Gráfico de 1830, complementando las deficiencias de información con expedientes de Escribanía Mayor de Gobierno, libros de Mensuras Antiguas y Duplicados de Mensura. Se pondera el grado de exactitud de la información que contiene la fuente, se completan las áreas vacías y, por último, se utiliza el resultado final para producir dos registros gráficos que reflejen la ocupación y propiedad legal de la tierra para 1822 y 1850, con el fin de verificar el grado de subdivisión parcelaria. El espacio trabajado se circunscribe a los actuales partidos de Chascomús, General Paz y Monte al noreste del río Salado

Modelo para la toma de decisiones sobre los contenidos curriculares de la Organización del Conocimiento en programas académicos de Bibliotecología, Documentación o Ciencia de la Información

Se presenta un modelo para decidir los contenidos curriculares de la Organización del Conocimiento en carreras de Bibliotecología, Documentación y Ciencia de la Información, orientado principalmente al Mercosur. Para el diseño del modelo se tuvieron en cuenta los contenidos mínimos recomendados por los encuentros de directores y docentes de escuelas de Bibliotecología del Mercosur, la llamada corriente de ISKO y los aportes de distintos autores relacionados con ambas fuentes. El modelo consta de tres categorías primarias: fundamentos, aplicaciones y ética de la Organización del Conocimiento. Los fundamentos se consideran desde un abordaje multidimensional. Las aplicaciones se dividen en tres categorías primarias: a) construcción de sistemas de organización del conocimiento, b) descripción de contenido y c) gestión de calidad de la Organización del Conocimiento. La ética también se divide en tres categorías secundarias: compromiso ético, valores éticos y problemas éticos. El modelo debe entenderse como un molde vacío que necesita llenarse con los contenidos que decida cada carrera o cada espacio curricular y se espera que facilite la evaluación, actualización y comparación de esos contenidos. Tiene la limitación de basarse en las recomendaciones del Mercosur y la corriente de ISKO, que no son aceptadas por todos los especialistas

Teoría política posfundacional en La guerra del fin del mundo de Mario Vargas Llosa : ¿Canudos postestructuralista?

La relación entre teoría política y literatura quizás no pueda contarse entre las más fecundas si se la compara con el vínculo que han establecido disciplinas como la filosofía, la historia y la psicología. Si bien la política ha ocupado un lugar central en la literatura es difícil sostener que la teoría política haya obtenido un sitio destacado. Una notable excepción encontramos en la novela La guerra del fin del mundo de Mario Vargas Llosa, no porque el autor se dedique a la teoría política, sino por la complicidad de la trama de la novela con ciertas perspectivas teóricas contemporáneas. En este horizonte, el artículo tiene como objetivo realizar una lectura de La guerra del fin del mundo y sugerir su relación con categorías centrales de la teoría política de inspiración posfundacional como Heterogeneidad, Antagonismo, exterior constitutivo, significante vacío, discurso y hegemonía. El trabajo que presentamos, de este modo, pretende aportar a la discusión de ciertas categorías teórico políticas que muchas veces por su grado de abstracción han suscitado dificultades pero también ofrecer claves de lectura de esta novela desde la teoría política actual

Ezequiel: Relato de vida

El abordaje del presente relato despliega la situación de vida de un sujeto adolescente que desde temprana edad se relaciona con un docente de Educación Física. Interactuando por los distintos niveles educativos, y casi por azar, la vida de los dos se entrelazará y se relacionará en diferentes contextos de pobreza, indigencia y sometimiento. La narración pretende así recrear con crudeza las sensaciones que acompañan a la orfandad y la vulnerabilidad producto de la marginalidad, así como las consecuencias de teorizaciones pedagógicas vacías y de una escuela sin sentido, donde el devenir del maestro concurrirá para persuadir a su alumno de realizar una mejor vida. El objetivo final de este relato es intentar, humildemente, reflejar algo de la subsistencia de incontables niños y adolescentes de nuestro sistema educativo.

Magnetic properties of basalts at DSDP Hole 83-504B

We have studied the magnetic properties of 22 samples from DSDP Leg 83 to determine the origin of remanence and its relationship to such problems as the tectonic and chemical evolution of the section, the depth of the magnetized layer, and the applicability of magnetic properties of ophiolites to the marine crust. The magnitude of natural remanence has fairly typical values in the uppermost part of the section, falls two to three orders of magnitude in the transition zone, and returns to values slightly less than the upper part in the dike complex. This behavior reflects, for the most part, variations in the amount of magnetic minerals present. Directional behavior is highly variable throughout the section and often shows complexity even on the level of a single sample. Curie temperature measurements and preliminary opaque petrography indicate that the remanence is chemical in origin and probably involves a resetting of the original thermal remanent magnetization (TRM) direction. Selective destructive demagnetization of four breccia samples shows that the remanence of the clasts was acquired prior to consolidation and did not change significantly thereafter. There are also indications that some of the remanence may be carried by secondary magnetic phases. A comparison of these samples with comparable ophiolite rocks is equivocal, with similarities in remanence characteristics but differences in magnetic mineralogy. As for magnetic anomalies, the transition zone is too weakly magnetized to contribute significantly. The available data on the dike complex are inconclusive and their contribution is still open to debate.

Clinamen : Entre libertad y determinismo en De Rerum Natura de Lucrecio

En el presente trabajo se trabaja principalmente en la noción de clinamen, el cual debe entenderse como una desviación azarosa que ocurre en el átomo. Lucrecio argumenta, siguiendo la tradición atomista que lo precede, que el fundamento ontológico de la realidad, es que toda la naturaleza está compuesta de átomos y vacío. El filósofo adhiere a una concepción esencialmente mecanicista del cosmos: el hecho de que el mundo no es una creación de los dioses, hace que la naturaleza sea una constante repetición de los hechos. El concepto de clinamen lleva a Lucrecio plantear, además, el problema del determinismo y la libertad: si todo movimiento es siempre una relación causal con un antes, ¿de dónde viene este poder independiente del destino, a través del cual nos movemos hacia donde la voluntad de cada uno conduce? En segundo lugar, si todos los movimientos de los átomos son inflexiblemente determinados, la capacidad humana para decidir y asumir la responsabilidad de su accionar no podrían explicarse

Organic matter, isotopic composition of calcite veins in basement basalt and pore water at DSDP Leg 78A Holes

Sediments of the Barbados Ridge complex, cored on DSDP Leg 78A, contain low concentrations of acid-insoluble carbon (0.05-0.25%) and nitrogen (C/N 1.5-5) and dispersed C1-C6 hydrocarbons (100-800 ppb). The concentrations of organic carbon and 13C in organic carbon decrease with depth, whereas the concentration of dispersed hydrocarbons increases slightly with depth. These trends may reflect the slow oxidation of organic matter, with selective removal of 13C and slow conversion of the residual organic matter to hydrocarbons. Very minor indications of nitrogen gas were observed at about 250 meters sub-bottom at two of the drilling sites. Basement basalts have calcite veins with d13C values in the range of 2.0 to 3.2 per mil and d18O-SMOW values ranging from 28.5 to +30.6 per mil. Interstitial waters have d18O-SMOW of 0.2 to -3.5 per mil and dD-SMOW of -2 to -15 per mil. The oxygen isotopic composition of the calcite veins in the basement basalts gives estimated equilibrium fractionation temperatures in the range of 11 to 24°C, assuming precipitation from water with d18O-SMOW in the range of +0.1 to -1.0 per mil. This suggests that basalt alteration and precipitation of vein calcite occurred in contact either with warmer Campanian seawater or, later, with pore water, after burial to depths of 200- 300 meters. Pore waters from all three sites are depleted in deuterium and 18O, and dissolved sulfate is enriched in 34S at Sites 541 and 542, but not at Site 543.

Displaced diatom, discoasters and benthic foraminifers at DSDP Hole 72-515A

Late Pliocene to Recent sediments from the southern Brazil Basin (DSDP Hole 515A, hydraulic piston core) were analyzed for evidence of episodic flow of Antarctic Bottom Water (AABW) through the Vema Channel. Carbonate-enriched layers punctuate the post-Pliocene section, otherwise composed predominantly of terrigenous silt and clay. Carbonate enrichment is thought to result from rapid deposition of fine-grained calcareous turbidites, originating in canyons incised on the northern margin of the Rio Grande Rise. The composition of benthic foraminiferal assemblages and the presence of stratigraphically displaced discoasters is consistent with a turbidite origin. Based on the presence of displaced Antarctic diatoms, AABW flow through the Vema Channel apparently has had a major influence on this site for only four periods during the last 2.7 Ma (about 45 to 250; 375 to 430; 700 to 780; 1320 to 1345 thousand yr. ago).

Mineralogy and geochemistry of weathered serpentinites in DSDP Leg 84 sediments

At Sites 566, 567, and 570 of Leg 84, ophiolitic serpentinite basement was covered by a sequence of serpentinitic mud that was formed by weathering of the serpentinites under sea- or pore-water conditions. Several mineralogical processes were observed: (1) The serpentinitic mud that consists mainly of chrysotile was formed from the lizardite component of the serpentinites by alteration. (2) Slightly trioctahedral smectites containing nonexpandable mica layers, trioctahedral smectites containing nonexpandable chlorite layers, and swelling chlorites were presumably formed from detrital chlorite and/or serpentine. (3) The occurrence of tremolite, chlorite, analcime, and talc can be attributed to reworking of gabbroic ophiolite rocks. (4) Dolomite, aragonite, and Mg-calcite, all authigenic, occur in the serpentinitic mud.

Organic geochemistry of sediment samples from Prydz Bay

High molecular weight aliphatic hydrocarbons were extracted from sediments at two sites (741 and 742) drilled during Ocean Drilling Program Leg 119 in Prydz Bay, a major embayment on the continental shelf of East Antarctica. The distributions of n-alkanes and triterpenoid and steroid hydrocarbons suggest that the n-alkanes and steranes are mainly of terrestrial origin and that the hydrocarbons are immature to slightly mature in the Lower Cretaceous sediments and immature to mature in the Tertiary sediments. At Site 741, the Lower Cretaceous depositional sequence, which is generally characterized by immature hydrocarbons, is interrupted by sediment having more mature components, suggesting a change of source during part of Early Cretaceous time. At Site 742, the mature geochemical parameters of a Pliocene sample correlate with results reported elsewhere for Site 739. In all but one of the other Tertiary samples, the geochemical parameters indicate intermediate maturity. The Lower Cretaceous and Pliocene sediments average about 1.9% organic carbon, a value of interest from the point of view of potential sources of petroleum offshore from Antarctica.

Biological traits, and egg and fecal pellet production of Calanus finmarchicus and Calanus glacialis in situ and during experiments

The effects of temperature and food was examined for Calanus finmarchicus and C. glacialis during 3 phases of the phytoplankton spring bloom in Disko Bay, western Greenland. The 2 species were collected during pre-bloom, bloom, and post-bloom and exposed to temperatures from 0 to 10°C, combined with deficient or excess food. Fecal pellet and egg production were measured as indices for grazing and secondary production, respectively. Furthermore, changes in body carbon, nitrogen, and lipid content were measured. C. glacialis sampled before the bloom and incubated with excess food exhibited high specific egg production at temperatures between 0 and 2.5°C. Higher temperatures did not increase egg production considerably, whereas egg production for C. finmarchicus more than tripled between 2.5 and 5°C. Starved C. glacialis produced eggs at all temperatures stimulated by increasing temperatures, whereas starved C. finmarchicus needed temperatures above 5°C to produce eggs fueled by their lipid stores. Few C. finmarchicus had mature gonads at the initiation of the pre-bloom and bloom experiment, and egg production of C. finmarchicus therefore only increased as the ratio of individuals with mature gonads increased. During the bloom, both C. glacialis and C. finmarchicus used the high food availability for egg production, while refueling or exhausting their lipid stores, respectively. Finally, during the post-bloom experiment, production was low by C. finmarchicus, whereas C. glacialis had terminated production. Our results suggest that a future warmer ocean will reduce the advantage of early spawning by C. glacialis and that C. finmarchicus will become increasingly prevalent.

Benthic foraminiferal assemblages in surface sediments of the Elbe estuary

Two foraminiferal assemblages are observed in surface sediments of the Elbe estuarv. an Elphidium excavatum assemblaae and an Ahmonia/Protelphidium assemblage. They are the result of test-size sorting in accordance to the grain size of the sediments. These assemblages of mainly empty tests differ basically from the living population, which is dominated exclusively by E. excavatum. The average test size is decreasing when advancing from the Open sea into the estuary and the living fauna disappears near the entrance of the Kiel Canal. In the dead assemblage the diversity is distinctively higher and the average test size varies with the grain size of the sediment. The assemblages found in plankton tows are nearly identical with those in corresponding bottom samples. This indicates the distribution pattern to be caused by transport in currents (mainly in suspension). This type of foraminiferal assemblages characterize macro- and mesotidal estuaries and might indicate a high tidal range when observed in sediments of fossil estuaries.

Survey of living conditions of Arctic indigenous peoples

Major findings of the Survey of Living Conditions in the Arctic (SLiCA) are: (1) A combination of traditional activities and cash employment is the prevailing lifestyle of Arctic indigenous peoples; (2) family ties, social support of each other, and traditional activities have a lot to do with why indigenous people choose to remain in Arctic communities; (3) well-being is closely related to job opportunities, locally available fish and game, and a sense of local control. Well-being and depression (and related problems like suicide) are flip sides of the same coin. Improving well-being may reduce social problems; and, (4) health conditions vary widely in the Arctic: three-in-four Greenlandic Inuit self-rate their health as at least very good compared with one-in-two Canadian and Alaska Inuit and one-in-five Chukotka indigenous people. Findings are based on 7,200 interviews in a probability sample of Inupiat settlement regions of Alaska, the four Inuit settlement regions of Canada, all of Greenland, and the Anadyrskij, Anadyr, Shmidtovs, Beringovskij, Chukotskij, Iujl'tinskij, Bilibinskij, Chaunskij, Providenskij, Uel'Kal' districts of Chukotka. Indigenous people and researchers from Greenland, Russia, Canada, the United States, Denmark, Norway, Sweden, and Finland collaborated on all phases of the study.