Geo-referenced photo-mosaics of the Menez Gwen Hydrothermal Vent (Mid-Atlantic Ridge)

The Menez Gwen hydrothermal vents, located on the flanks of a small young volcanic structure in the axial valley of the Menez Gwen seamount, are the shallowest known vent systems on the Mid-Atlantic Ridge that host chemosynthetic communities. Although visited several times by research cruises, very few images have been published of the active sites, and their spatial dimensions and morphologies remain difficult to comprehend. We visited the vents on the eastern flank of the small Menez Gwen volcano during cruises with RV Poseidon (POS402, 2010) and RV Meteor (M82/3, 2010), and used new bathymetry and imagery data to provide first detailed information on the extents, surface morphologies, spatial patterns of the hydrothermal discharge and the distribution of dominant megafauna of five active sites. The investigated sites were mostly covered by soft sediments and abundant white precipitates, and bordered by basaltic pillows. The hydrothermally-influenced areas of the sites ranged from 59 to 200 m**2. Geo-referenced photomosaics and video data revealed that the symbiotic mussel Bathymodiolus azoricus was the dominant species and present at all sites. Using literature data on average body sizes and biomasses of Menez Gwen B. azoricus, we estimated that the B. azoricus populations inhabiting the eastern flank sites of the small volcano range between 28,640 and 50,120 individuals with a total biomass of 50 to 380 kg wet weight. Based on modeled rates of chemical consumption by the symbionts, the annual methane and sulfide consumption by B. azoricus could reach 1760 mol CH4 yr**-1 and 11,060 mol H2S yr**-1. We propose that the chemical consumption by B. azoricus over at the Menez Gwen sites is low compared to the natural release of methane and sulfide via venting fluids.

Enseñar a enseñar Economía: la cuestión de la formación docente y la formación disciplinar en el Profesorado de Ciencias Económicas (PCE). 16H274

Con esta investigación se propuso indagar y reflexionar acerca de la tensión existente entre la formación disciplinar específica que se pretende alcanzar en el graduado del Profesorado en Ciencias Económicas y su capacidad para generar la construcción de conocimientos significativos en su práctica profesional. El proyecto se ejecutó en dos etapas: la primera abarcó el año 2009 y una segunda, el año 2010. La primera etapa estuvo centrada en la realización de actividades de tipo exploratoria y descriptiva de materiales curriculares tanto para la enseñanza media y la formación del profesorado en Ciencias Económicas, como también se cotejaron directrices de la formación docente en otras universidades del país; se analizaron materiales bibliográficos a fin de efectuar un acercamiento al estado de la cuestión. Los resultados de las actividades, las reflexiones y análisis, condujeron a la producción de documentos de base, trabajos e informes finales. En la segunda etapa, el trabajo se abocó a la toma de decisiones respecto de: los marcos teóricos metodológicos que orientó el trabajo de campo, y la determinación de las muestras. Seguidamente se procedió a la revisión y el testeo de los instrumentos de recolección de la información, elaborados en la primera etapa, para luego realizar el trabajo de campo. Luego de la sistematización de los datos obtenidos se realzaron talleres de reflexión y análisis al interior del equipo a fin de elaborar un documento final que en el que se integraron las informaciones obtenidas del análisis curricular, las entrevistas y las encuestas, logrando delimitar los puntos críticos en el marco de la problemática estudiada.

Comunicación y ciudad. La producción social de la seguridad en Posadas, Misiones. 16H303

Actividades desarrolladas durante el período: Se definieron, en función de los objetivos propuestos; tres ejes –con sus especificidades aunque articulados entre sí- para el abordaje de la producción pública de la (in) seguridad: massmediático; político-institucional; cotidiano; Se compartió, en reuniones quincenales de todo del equipo la lectura comprensiva y analítica de bibliografía vinculada con el proyecto; Se comenzó con la observación y registro fotográfico de controversiales prácticas, de presencias y usos del espacio público que aportan al debate público sobre la seguridad; Se inició el relevamiento y recopilación de discursos alusivos que circulan en medios, en la web; también de documentación oficial sobre la cuestión; Se empezó a organizar un archivo periodístico del tema; a partir de producciones de los diarios locales: Primera Edición, Noticias de la calle y El Territorio; Se confeccionó el cuestionario para una encuesta sobre percepción de seguridad, diseño de instructivo, plan de campo. Se seccionaron las zonas para la toma de la encuesta: micro centro, costanera; barrios: A4, Villa Cabello y San Lorenzo de Posadas; Se conformó el Grupo de estudio sobre la Ciudad y el Territorio (GECYT) a partir del contacto y confluencia con otros proyectos de investigación de la Facultad; Se continuó con las actividades de Promoción del Derecho a la Ciudad, iniciadas en el proyecto anterior (Espacio, comunicación y cultura III. 16H238)

"Contemporary Art and Anthropology". De Arnd Schneider y Christopher Wright (Editores). En: Avá, nº 9

Entre Arte e Antropologia: diálogos e apropriações A relação entre Arte e Ciência é um dos temas dos mais complexos e evolutivos, sempre dependendo do contexto histórico e do objetivo desta "relação". Por isto, resolvi começar esta resenha do livro ContemporaryArt and Anthropology com uma visão ampla e clássica deste problema epistemológico .

Revista de Estudios Clásicos

La Revista de Estudios Clásicos publica trabajos y colaboraciones originales que versan sobre los ámbitos comprendidos bajo los conceptos de filología, filosofía y literatura griega y latina, y su recepción en autores posteriores.

Age and chemical composition of apatites from five DSDP and ODP Sites in the Pacific, Atlantic and Indian Oceans

Since studies on deep-sea cores were carried out in the early 1990s it has been known that ambient temperature may have a marked affect on apatite fission track annealing. Due to sluggish annealing kinetics, this effect cannot be quantified by laboratory annealing experiments. The unknown amount of low-temperature annealing remains one of the main uncertainties for extracting thermal histories from fission track data, particularly for samples which experienced slow cooling in shallow crustal levels. To further elucidate these uncertainties, we studied volcanogenic sediments from five deep-sea drill cores, that were exposed to maximum temperatures between ~10° and 70°C over geological time scales of ~15-120 Ma. Mean track lengths (MTL) and etch pit diameters (Dpar) of all samples were measured, and the chemical composition of each grain analyzed for age and track length measurements was determined by electron microprobe analysis. Thermal histories of the sampled sites were independently reconstructed, based on vitrinite reflectance measurements and/or 1D numerical modelling. These reconstructions were used to test the most widely used annealing models for their ability to predict low-temperature annealing. Our results show that long-term exposure to temperatures below the temperature range of the nominal apatite fission track partial annealing zone results in track shortening ranging between 4 and 11%. Both chlorine content and Dpar values explain the downhole annealing patterns equally well. Low chlorine apatite from one drill core revealed a systematic relation between Si-content and Dpar value. The question whether Si-substitution in apatite has direct and systematic effects on annealing properties however, cannot be addressed by our data. For samples, which remained at temperatures <30°C, and which are low in chlorine, the Laslett et al. [Laslett G., Green P., Duddy I. and Gleadow A. (1987) Thermal annealing of fission tracks in apatite. Chem. Geol. 65, 1-13] annealing model predicts MTL up to 0.6 µm longer than those actually measured, whereas for apatites with intermediate to high chlorine content, which experienced temperatures >30°C, the predictions of the Laslett et al. (1987) model agree with the measured MTL data within error levels. With few exceptions, predictions by the Ketcham et al. [Ketcham R., Donelick R. and Carlson W. (1999) Variability of apatite fission-track annealing kinetics. III: Extrapolation to geological time scales. Am. Mineral. 84/9, 1235-1255] annealing model are consistent with the measured data for samples which remained at temperatures below ~30°C. For samples which experienced maximum temperatures between ~30 and 70°C, and which are rich in chlorine, the Ketcham et al. (1999) model overestimates track annealing.

Halocarbons in surface water from SWEDARP97/98

A number of parameters of biogeochemical interest were monitored along a north-southerly transect (S 43-S 63°) in the Atlantic Sector of the Southern Ocean from the 8th to the 20th of December 1997. Changes in total dissolved inorganic carbon (CT) and total alkalinity (AT) were mostly dependent on temperature and salinity until the ice edge was reached. After this point only a weak correlation was seen between these. Highest mean values of CT and AT were observed in the Winter Ice Edge (WIE) (2195 and 2319 µmol/kg, respectively). Lowest mean AT (2277 µmol/kg) was observed in the Sub-Antarctic Front (SAF), whereas lowest mean CT concentration (2068 µmol/kg) was associated with the Sub-Tropical Front (STF). The pH in situ varied between 8.060 and 8.156 where the highest values were observed in the southern part of the Antarctic Polar Front (APF) and in the Summer Ice Edge (SIE) Region . These peaks were associated with areas of high chlorophyll a (chl a) and tribromomethane values. In the other areas the pH in situ was mainly dependent on hydrography. Bacterial abundance decreased more than one order of magnitude when going from north to south. The decrease appeared to be strongly related to water temperature and there were no elevated abundances at frontal zones. Microphytoplankton dominated in the SAF and APF, whereas the nano- and picoplankton dominated outside these regions. Volatile halogenated compounds were found to vary both with regions, and with daylight. For the iodinated compounds, the highest concentrations were found north of the STF. Brominated hydrocarbons had high concentrations in the STF, but elevated concentrations were also found in the APF and SIE regions. No obvious correlation could be found between the occurrence of individual halocarbons and chl a. On some occasions trichloroethene and tribromomethane related to the presence of nano- and microplankton, respectively.

Holocene sedimentation in the Strait of Otranto, Mediterranean Sea

An extensive radiograph study of 24 undisturbed, up to 206-cm long box and gravity cores from the western part of the Strait of Otranto revealed a great variety of primary bedding structures and secondary burrowing features. The regional distribution of the sediments according to their structural, textural, and compositional properties reflects the major morphologic subdivisions of the strait into shelf, slope, and trough bottom (e.g., the bottom of the northern end of the Corfu-Kephallinia Trough, which extends from the northeastern Ionian Sea into the Strait of Otranto): (1) The Apulian shelf (0 to -170m) is only partly covered by very poorly sorted, muddy sands without layering. These relict(?) sands are rich in organic carbonate debris and contain glauconite and reworked (?Pleistocene) ooids. (2) The slope sediments (-170 to -1,000 m) are poorly sorted, sandy muds with a high degree of burrowing. One core (OT 5) is laminated and shows slump structures. An origin of these slumped sediment masses from older deposits higher on the slope was inferred from their abnormal compaction, color, texture, organic content, and mineral composition. (3) Cores from the northern end of the Corfu-Kephallinia Trough (-980 to -1,060 m) display a few graded sand layers, 2-5 cm (maximum 30 cm) thick with parallel and ripple-cross-laminations, deposited by oceanic bottom or small-scale turbidity currents. They are intercalated with homogeneous lutite. (4) Hemipelagic sediments prevail in the more southerly part of the Corfu-Kephallinia Trough and on the "Apulian-Ionian Ridge", the southern submarine extension of the Apulian Peninsula. Below a core depth of 160 cm, these cores have a laminated ("varved") zone, representing an Early Holocene (Boreal-Atlanticum) "stagnation layer" (14C age approximately 9,000 years). The terrigenous components of the surface sediments as well as those of the deeper sand layers can be derived from the Apulian shelf and the Italian mainland (Cretaceous Apulian Plateau and Gargano Mountains, southern Apennines, volcanic province of the Monte Vulture). Indicated by the heavy mineral glaucophane, a minor proportion of the sedimentary material is probably of Alpine origin. If this portion is considered to be first-cycle clastic material it reaches the Strait of Otranto after a longitudinal transport of 700 km via the Adriatic Sea. The lack of phyllosilicates in the coarse- to medium-grained shelf samples might be explained by the activity of the "Apulian Current" (surface velocities up to 4 knots) which in the past possibly has affected the bottom almost down to depths of the shelf edge. The percentage of planktonic organisms, and also the plankton: benthos ratio in the sediments is a useful indicator for bathymetry (depth zonation).