On the composition of oceanic and littoral manganese nodules (published online 2015)

The following analyses were made some years ago, principally with the object of ascertaining the state of oxidation of the manganese in the nodules. The nodules examined came from three different localities, two of them oceanic and the third littoral. Samples marked I., II., and III. are from nodules brought up in the trawl on board the "Challenger," on 13th March 1874, in lat. 42° 42' S., long. 134° 10' E. The depth of the water was 2600 fathoms, and the temperature of the bottom water 0·2° C. The density of the bottom water was 1·02570 at 15·56° C. Being from a high southern latitude, and therefore near the source of surface aeration, the water is highly charged with atmospheric gases, especially oxygen. It contained, per litre, 18·4 c.c. of mixed nitrogen and oxygen, of which 31·81 per cent, was oxygen, and 27·33 c.c, or 53·7 milligrammes, loosely-bound carbonic acid. The position of the station is about 400 miles south-west of the nearest part of the Australian coast, and about 500 miles west of Tasmania. It was the deepest water observed in the Antarctic voyage between the Cape of Good Hope and Melbourne. The haul was a very abundant one, and a few notes which I made at the time may be interesting: -"The water was found unexpectedly deep, the bottom being red clay, with some Foraminifera.

Determination of sulfite and manganese in sediments from the K/T boundary

The solid-state-physics technique of electron spin resonance (ESR) has been employed in an exploratory study of marine limestones and impact-related deposits from Cretaceous-Tertiary (KT) boundary sites including Spain (Sopelana and Caravaca), New Jersey (Bass River), the U.S. Atlantic continental margin (Blake Nose, ODP Leg 171B/1049/A), and several locations in Belize and southern Mexico within -600 km of the Chicxulub crater. The ESR spectra of SO3(1-) (a radiation-induced point defect involving a sulfite ion substitutional for CO3(2-) which has trapped a positive charge) and Mn(2+) in calcite were singled out for analysis because they are unambiguously interpretable and relatively easy to record. ESR signal strengths of calcite-related SO3(1-) and Mn(2+) have been studied as functions of stratigraphic position in whole-rock samples across the KT boundary at Sopelana, Caravaca, and Blake Nose. At all three of these sites, anomalies in SO3(1-) and/or Mn(2+) intensities are noted at the KT boundary relative to the corresponding background levels in the rocks above and below. At Caravaca, the SO3(1-) background itself is found to be lower by a factor of 2.7 in the first 30,000 years of the Tertiary relative to its steady-state value in the last 15,000 years of the Cretaceous, indicating either an abrupt and quasi-permanent change in ocean chemistry (or temperature) or extinction of the marine biota primarily responsible for fixing sulfite in the late Cretaceous limestones. An exponential decrease in the Mn(2+) concentration per unit mass calcite, [Mn(2+)], as the KT boundary at Caravaca is approached from below (1/e characteristic length =1.4 cm) is interpreted as a result of post-impact leaching of the seafloor. Absolute ESR quantitative analyses of proximal impact deposits from Belize and southern Mexico group naturally into three distinct fields in a twodimensional [SO3(1-)]-versus-[Mn(2+)] scatter plot. These fields contain (I) limestone ejecta clasts, (II) accretionary lapilli, and (III) a variety of SO3(1-) -depleted/Mn(2+) enriched impact deposits. Data for the investigated non-impact-related Cretaceous and Tertiary marine limestones (Spain and Blake Nose) fall outside of these three fields. With reference to thes enon-impact deposits, fields I, II, and III can be respectively characterized as Mn(2+) -depleted, SO3(1-) -enhanced, and SO3(1-) -depleted. It is proposed that (1) field I represents calcites from the Yucatin Platform, and that the Mn(2+) -depleted signature can be used as an indicator of primary Chicxulub ejecta in deep marine environments and (2) field II represents calcites that include a component formed in the vapor plume, either from condensation in the presence of CO2/SO3(1-) -rich vapors, or reactions between CaO and CO2/SO3 rich vapors, and that this SO3(1-) -enhanced signature can be used as an indicator of impact vapor plume deposits. Given these two propositions, the ESR data for the Blake Nose deposits are ascribed to the presence of basal coarse calcitic Chicxulub ejecta clasts, while the finer components that are increasingly represented toward the top are interpreted to contain high- SO3(1-) calcite from the vapor plume. The apparently-undisturbed Bass River deposit may contain even higher concentrations of vapor-plume calcite. None of the three components included in field III appear to be represented at distal, deep marine KT-boundary sites; this field may include several types of impact-related deposits of diverse origins and diagenetic histories.

El juego en los procesos de intervención escolar. 16H264

1) Indagación bibliográfica y reseñas críticas. Ampliación de la consulta bibliográfica y reelaboración de tramas conceptuales y analíticas destinadas a la observación y el análisis. 2) Fichaje de bibliografía seleccionada. Profundización, análisis y continuación de los fichajes de autores: De Certau, Michel, Peirce, Charles: (1908) Un argumento olvidado a favor de la realidad de Dios, en The Hibbert Journal., Vigotsky L.: (1991, 2000, 1996,1997, 2001) Obras Escogidas I, II, III, IV, V. Ed. Aprendizaje Visor, Bruner, J.: (1995)Acción, pensamiento y lenguaje .Ed. Alianza. Madrid. 3)Hemos incluido en los análisis aportes de la producción de la tesis doctoral de la Dra. Raquel Alarcón, Título: "Alfabetización semiótica en los umbrales. Cita en sitios de borde" (Tesis doctoral. Inédita), CEA, UNC, Sept, 2010. 4) Revisión de los cronogramas previstos acordes con las posibilidades y disponibilidades que requirieron las instancias de indagaciones propuestas. Sistematizaciones de los informes parciales. Análisis de las propuestas de planificación de los IFD y producciones curriculares oficiales vigentes. 4) Producción del informe final

Thomas Cahill. Navegando por el mar de vino. Por qué los griegos son importantes. Bogotá, Norma, 2005, 325 pp.

Fil: Poquet, Adriana.

Persona y naturaleza : de Pedro Lombardo a Martin Heidegger

Pese a los indicios que podrían encontrarse en la filosofía griega, la noción de persona es de origen netamente cristiano y no pudo haber sido formulada sino dentro de ese horizonte de pensamiento. El hombre ha sido creado a imagen de Dios y es persona porque, en primer término, Dios lo es. Aquí se enlazan, durante el medioevo, las cuestiones antropológicas y teológicas (trinitarias y cristológicas). Un ejemplo paradigmático se encuentra en las Sentencias de Pedro Lombardo y sus comentadores, entre los que hemos reparado especialmente en Tomás de Aquino. En este contexto, “naturaleza" (divina o humana) y “persona" son nociones íntimamente vinculadas, pues es propio de tales naturalezas el existir y manifestarse como seres personales. Esa relación, sin embargo, se pierde durante la modernidad, época en que persona y naturaleza se vuelven términos antagónicos. Martin Heidegger, agudo crítico de esa transformación en la historia del pensar, propone una concepción de lo humano que, no obstante su “ateísmo metodológico", finalmente parece aproximarse a la noción cristiana de persona.