Las paradojas de nadie : Una genealogía del no-sujeto

Cada época histórica construye, a través de discursos y prácticas específicas, sus formas legitimadas de subjetividad. Sin embargo, por debajo de estas identidades institucionalizadas, se ha ido gestando a lo largo de la historia una forma paradójica de subjetividad cuyo nombre, desde Homero en adelante, es Nadie. Esta figura excéntrica hace posible, cada vez que reaparece en la trama de los discursos y las prácticas, la subversión de las categorías fundamentales de la ontología y la política que han definido al hombre históricamente. Este trabajo pretende reconstruir la genealogía de esta particular figura con el fin de mostrar la posibilidad de una lectura diferente (y paradójica) de algunos de los conceptos centrales de la metafísica de Occidente

Magnetic properties of ODP Hole 109-670A

Magnetic fabrics of serpentinized peridotites are related to anisomorphic magnetite formed during serpentinization. In the less serpentinized facies they are, however, mainly mimetic of the high temperature deformation prior to serpentinization. In more serpentinized peridotites, the magnetic fabrics, related to magnetite veins which are more developed in this case, are superimposed on mimetic fabrics. Remanent properties, hysteresis loop parameters, and Curie temperatures were measured. Natural remanent magnetizations (NRM) have crystallization remanent magnetic (CRM) origin. Measured magnetic parameters suggest that pseudo-single domain (PSD) grains of magnetite are present in samples with low degree of serpentinization. The samples with high degree of serpentinization contain mainly multi-domain (MD) magnetite grains.

Sobre la homogeinización de la presión fiscal en la agricultura pampeana tras la devaluación

La década del '90 marcó una fuerte aceleración del proceso de concentración económica de la producción agrícola pampeana, evolución que continuaría tras la devaluación de 2002. En la determinación del mismo convergen distintos factores: las economías de escala, el manejo cambiario, la evolución tecnológica (entre otros). En este trabajo se estudia uno de estos condicionantes: la política impositiva del Estado Nacional. Se analizan los tributos que gravan al agro y sus alícuotas, diferenciando según la escala y perfil tecnológico del productor, calculando un indicador de la presión fiscal (peso de los tributos sobre el ingreso bruto de la explotación). Se concluye que en el nuevo siglo se produjo una nivelación importante en cuanto a los montos impositivos requeridos por el Estado a los distintos tipos de agentes, lo que minimizó la posibilidad que tiene éste a partir de aquella herramienta de modelar una trama social más desconcentrada

Escuela, migrantes internos y comunidad barrial en Rosario. Cultura y socialización en la segunda mitad del siglo XX

Esta es una tesis situada en el campo de estudios interdisciplinario de las Ciencias de la Educación, la Historia y la Psicología Social, por lo que es denominada como un estudio acerca de la educación, y su historia psicosocial. La identidad es un concepto sumamente prolífico a la hora de pensar las problemáticas educativas en claves históricas y psicosociales. Si a esto se le agrega la interacción con los cánones escolares, se alcanza un campo rico y fértil para ser investigado. A partir de ahí, la investigación se propone por objetivo general, producir un conocimiento explicativo en torno a la configuración de identidad y el impacto producido por los cánones culturales de la escuela en la herencia cultural de las poblaciones migratorias. A los fines de situar empíricamente el objeto, la dimensión espacial elegida, ha sido una comunidad de la ciudad de Rosario, Santa Fe. El barrio Belgrano y, en particular, la escuela No 91 República Federativa de Brasil, que es la oferta educativa estatal de nivel primario vinculada al mismo. Se desarrollan elementos analíticos que hacen a la configuración socio-histórica (segunda mitad del siglo XX) y educativa del barrio Belgrano. Se trabajan categorías que involucran a la identidad barrial, su historia, la transmisión del legado cultural y el sentido de pertenencia de los sujetos que viven e interactúan en él. Se parte de las siguientes hipótesis: los migrantes internos se incorporan a la comunidad local escapando de las necesidades económicas de su lugar de origen No obstante, una vez asentados los migrantes toman como propias las representaciones adquiridas confluyendo con las referidas a la pertenencia barrial. Si la escuela pretende que la identidad de los migrantes sea absorbida como una adaptación pasiva al canon cultural, esta fracasa en aquellos aspectos que hacen al legado cultural, aunque continúe con la reproducción de ciertos aspectos de la homogeneización y de las diferencias sociales. La metodología cualitativa se ajusta a las pretensiones establecidas. El análisis de entrevistas, documentos, y datos censales es utilizado siendo triangulados los datos para una mejor precisión de la información referida. Consecuentemente, se efectúa el examen del impacto de los movimientos migratorios interprovinciales e internos de la ciudad que conllevan a poblar y a extender el tejido social del barrio y sus alcances en la transmisión del legado cultural en la escuela. Los resultados ponen en evidencia que el arbitrario cultural dominante, a través de sus propios cánones, no que lineal ni se apoderó totalmente de toda la escuela No. 91. Al tener un sentido de pertenencia e identificación suprema con el barrio, no habría reproducido totalmente y sin cuestionamientos el canon cultural dominante. Implícitamente y quizá espontáneamente, las prácticas reprodujeron el mandato del discurso del conjunto social, amalgamado con los aprendizajes socialmente significativos del legado de la comunidad. Por último, hacia fines de los noventa, la vida cotidiana barrial se torna altamente fragmentada e individualizada sin expectativas de configurar un proyecto común. Estas características también se observaron en la práctica docente: la pérdida en el tiempo, del sentido histórico, que ocasiona un resquebrajamiento en los vínculos sociales.

The 'Philosophical paintings' of the Republic

En el presente artículo examino la apropiación platónica del lenguaje poético en República y sostengo que, a pesar de sus críticas a la poesía en los libros 3 y 10, el lenguaje poético está correctamente entrelazado dentro del tejido filosófico para pintar lo corrupto, lo feo y lo inmoral. En términos específicos, la adaptación platónica de diversos motivos poéticos e imágenes en República se vuelve más significativa si prestamos atención a Sócrates como un quasi-pintor en el diálogo e interpretamos sus imágenes filosóficas como una respuesta de la filosofía a las engañosas representaciones dramáticas de la poesía. De este modo, el arte de la pintura que, incluso es criticado en el libro 10 de República, en manos de Platón resulta una herramienta filosófica que le permite investigar la relación de nuestro mundo senso-perceptivo ordinario con el campo metafísico de las Ideas y el lugar de lo humano en él

Geochemical analysis of minerals from sediment core CRP-2 in the Ross Sea, Antarctica

Distribution patterns, petrography, whole-rock and mineral chemistry, and shape and fabric data are described for the most representative basement lithologies occurring as clasts (granule to bolder grain-size class) from the 625 m deep CRP-2/2A drillcore. A major change in the distribution pattern of the clast types occurs at c. 310 mbsf., with granitoid-dominated clasts above and mainly dolerite clasts below; moreover, compositional and modal data suggest a further division into seven main detrital assemblages or petrofacies. In spite of this variability, most granitoid pebbles consist of either pink or grey biotite±hornblende monzogranites. Other less common and ubiquitous lithologies include biotite syenogranite, biotite-hornblende granodiorite, tonalite, monzogranitic porphyries (very common below 310 mbsf), microgranite, and subordinately, monzogabbro, Ca-silicate rocks, biotite-clinozoisite schist and biotite orthogneiss (restricted to the pre-Pliocene strata). The ubiquitous occurrence of biotite±hornblende monzogranite pebbles in both the Quaternary-Pliocene and Miocene-Oligocene sections, apparently reflects the dominance of these lithologies in the onshore basement, and particularly in the Cambro-Ordovician Granite Harbour Igneous Complex which forms the most extensive outcrop in southern Victoria Land. The petrographical features of the other CRP-2/2A pebble lithologies are consistent with a supply dominantly from areas of the Transantarctic Mountains facing the CRP-2/2A site, and they thus provide further evidence of a local provenance for the supply of basement clasts to the CRP-2/2A sedimentary strata.

Representative analyses of pre-tectonic metabasic rocks and metapelitic gneiss from Sverdrupfjella, East Antarctica

Extensive high-grade polydeformed metamorphic provinces surrounding Archaean cratonic nuclei in the East Antarctic Shield record two tectono-thermal episodes in late Mesoproterozoic and late Neoproterozoic-Cambrian times. In Western Dronning Maud Land, the high-grade Mesoproterozoic Maud Belt is juxtaposed against the Archaean Grunehogna Province and has traditionally been interpreted as a Grenvillian mobile belt that was thermally overprinted during the Early Palaeozoic. Integration of new U-Pb sensitive high-resolution ion microprobe and conventional single zircon and monazite age data, and Ar-Ar data on hornblende and biotite, with thermobarometric calculations on rocks from the H.U. Sverdrupfjella, northern Maud Belt, resulted in a more complex P-T-t evolution than previously assumed. A c. 540?Ma monazite, hosted by an upper ampibolite-facies mineral assemblage defining a regionally dominant top-to-NW shear fabric, provides strong evidence for the penetrative deformation in the area being of Pan-African age and not of Grenvillian age as previously reported. Relics of an eclogite-facies garnet-omphacite assemblage within strain-protected mafic boudins indicate that the peak metamorphic conditions recorded by most rocks in the area (T = 687-758°C, P = 9·4-11·3?kbar) were attained subsequent to decompression from P > 12·9?kbar. By analogy with limited U-Pb single zircon age data and on circumstantial textural grounds, this earlier eclogite-facies metamorphism is ascribed to subduction and accretion around 565?Ma. Post-peak metamorphic K-metasomatism under amphibolite-facies conditions is ascribed to the intrusion of post-orogenic granite at c. 480?Ma. The recognition of extensive Pan-African tectonism in the Maud Belt casts doubts on previous Rodinia reconstructions, in which this belt takes a pivotal position between East Antarctica, the Kalahari Craton and Laurentia. Evidence of late Mesoproterozoic high-grade metamorphism during the formation of the Maud Belt exists in the form of c. 1035?Ma zircon overgrowths that are probably related to relics of granulite-facies metamorphism recorded from other parts of the Maud Belt. The polymetamorphic rocks are largely derived from a c. 1140?Ma volcanic arc and 1072 ± 10?Ma granite.

Laboratory shearing experiments at low sliding velocities of IODP Hole 343-C0019E

The 2011 Tohoku-Oki earthquake demonstrated that the shallowest reaches of plate boundary subduction megathrusts can host substantial coseismic slip that generates large and destructive tsunamis, contrary to the common assumption that the frictional properties of unconsolidated clay-rich sediments at depths less than View the MathML source should inhibit rupture. We report on laboratory shearing experiments at low sliding velocities (View the MathML source) using borehole samples recovered during IODP Expedition 343 (JFAST), spanning the plate-boundary décollement within the region of large coseismic slip during the Tohoku earthquake. We show that at sub-seismic slip rates the fault is weak (sliding friction µs=0.2-0.26), in contrast to the much stronger wall rocks (µs>~0.5). The fault is weak due to elevated smectite clay content and is frictionally similar to a pelagic clay layer of similar composition. The higher cohesion of intact wall rock samples coupled with their higher amorphous silica content suggests that the wall rock is stronger due to diagenetic cementation and low clay content. Our measurements also show that the strongly developed in-situ fabric in the fault zone does not contribute to its frictional weakness, but does lead to a near-cohesionless fault zone, which may facilitate rupture propagation by reducing shear strength and surface energy at the tip of the rupture front. We suggest that the shallow rupture and large coseismic slip during the 2011 Tohoku earthquake was facilitated by a weak and cohesionless fault combined with strong wall rocks that drive localized deformation within a narrow zone.

Sedimentology of ODP Leg 126 deep-water volcaniclastics

Three sites were drilled in the Izu-Bonin forearc basin during Ocean Drilling Program (ODP) Leg 126. High-quality formation microscanner (FMS) data from two of the sites provide images of part of a thick, volcaniclastic, middle to upper Oligocene, basin-plain turbidite succession. The FMS images were used to construct bed-by-bed sedimentary sections for the depth intervals 2232-2441 m below rig floor (mbrf) in Hole 792E, and 4023-4330 mbrf in Hole 793B. Beds vary in thickness from those that are near or below the resolution of the FMS tool (2.5 cm) to those that are 10-15 m thick. The bed thicknesses are distributed according to a power law with an exponent of about 1.0. There are no obvious upward thickening or thinning sequences in the bed-by-bed sections. Spaced packets of thick and very thick beds may be a response to (1) low stands of global sea level, particularly at 30 Ma, (2) periods of increased tectonic uplift, or (3) periods of more intense volcanism. Graded sandstones, most pebbly sandstones, and graded to graded-stratified conglomerates were deposited by turbidity currents. The very thick, mainly structureless beds of sandstone, pebbly sandstone, and pebble conglomerate are interpreted as sandy debris-flow deposits. Many of the sediment gravity flows may have been triggered by earthquakes. Long recurrence intervals of 0.3-1 m.y. for the very thickest beds are consistent with triggering by large-magnitude earthquakes (M = 9) with epicenters approximately 10-50 km away from large, unstable accumulations of volcaniclastic sand and ash on the flanks of arc volcanoes. Paleocurrents were obtained from the grain fabric of six thicker sandstone beds, and ripple migration directions in about 40 thinner beds; orientations were constrained by the FMS images. The data from ripples are very scattered and cannot be used to specify source positions. They do, however, indicate that the paleoenvironment was a basin plain where weaker currents were free to follow a broad range of flow paths. The data from sandstone fabric are more reliable and indicate that turbidity currents flowed toward 150? during the time period from 28.9 to 27.3 Ma. This direction is essentially along the axis of the forearc basin, from north to south, with a small component of flow away from the western margin of the basin.

Texture analyses of ODP Site 131-808 sediments

The microfabric of 11 mudrock specimens from ODP Site 808 (Nankai accretionary prism) was quantitatively analyzed using X-ray texture goniometry and optical petrography. The objectives of the study were to learn about rock strain and to detect a component of bulk lateral shortening in the deformation of the mudstones. Strain evaluation is based on the predictions of March theory, and on distortions of initially homogeneous marker particle distributions (the Fry technique). The main results are as follows. The specimens underwent a strain path of progressive flattening, which is closely related to loss of pore space by vertical loading. A component of bulk lateral shortening is detectable in the top 550 mbsf at Site 808, but compared with the amount of uniaxial vertical shortening, its relative magnitude is probably small. Moreover, it cannot be said with confidence whether this is caused by toe contraction of the accretionary wedge or by gravitationally induced downslope movement of the sediment pile. The mudstones examined were deposited in a marine environment with an oxic bottom water column. Micropore collapse is an important fabric building mechanism, but below 400 mbsf its effects are at least partly overridden by recrystallization of smectite. We conclude that mud microfabrics are not very precise deformation gauges, but can be used for rough estimations of strain.

Magnetic measurements on ODP holes 178-1095A, 178-1095B and 178-1101A

We have determined the azimuth of bottom-current flow in drift deposit sediments recovered at ODP Sites 1095 and 1101, Antarctic Peninsula, using paleomagnetic reorientation of anisotropy of magnetic susceptibility (AMS) ellipsoids. A total of 38 cores from the two ODP sites have been measured, providing spatial and directional information on the physical record of the ACC (Antarctic Circumpolar Current) in the Plio-Pleistocene. Declination and inclination of the paleomagnetic vector of each core segment were used to reorient the AMS principal axes to the geographic coordinates. The cores were reoriented using the measured direction of the characteristic remanent magnetization (ChRM) with respect to a common reference line for the core, from which we are able to determine the orientation of the paleocurrent flow for Sites 1095 (Drift 7) and 1101 (Drift 4) relative to the geographic coordinates. Both sites have paleocurrent directions trending ~NW-SE, which in the former locality are parallel to a sediment wave field. Our study shows that a combination of magnetic fabric analysis and paleomagnetism allows deep-sea sedimentary fabric to be used as a long-term proxy of bottom-current flow history.