Los juegos deportivos en la educación general básica

Fil: Manazza, Carlos Alberto. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Mercado de trabajo y paro forzoso : Desde los comienzos de la Argentina moderna hasta la crisis de los años '30

Tabla de contenidos: Desocupación, subocupación, trabajo estacional, trabajo intermitente : De la crisis del '90 a la Primera Guerra Mundial / José Panettieri. Trabajo y salud [1880-1914] / Patricia G. Flier. Mercado de trabajo agrícola y el paro estacional en el agro pampeano [1890-1920] / Mariela Sansoni. Los tipógrafos en Buenos Aires : La sociedad tipográfica bonaerense [1855-1880] / María Silvia Badoza. Mercado de trabajo y reclutamiento de fuerza de trabajo en los ingenios azucareros de Salta y Jujuy [1880-1940] / María Cecilia Zuleta.

Mercado de trabajo y consumo alimenticio en la Argentina agroexportadora : Estudio de casos

Tabla de contenidos: Abastecimiento, comercialización, mercado de consumo y carestía en la ciudad de Buenos Aires desde fines del siglo pasado hasta 1920 / Patricia Graciela Flier. Formación del mercado de trabajo ferroviario en la Argentina agroexportadora / Mariela Sansoni. La organización de los procesos de trabajo en la industria textil, 1930-1945 : Una aproximación a través del análisis del periódico sindical El obrero textil / Andrea Del Bono.

Los juegos deportivos en la educación general básica

Fil: Manazza, Carlos Alberto. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Rare earth elements of modern seeps from the Gulf of Mexico, the Black Sea, and the Congo Fan

At marine seeps, methane is microbially oxidized resulting in the precipitation of carbonates close to the seafloor. Methane oxidation leads to sulfate depletion in sediment pore water, which induces a change in redox conditions. Rare earth element (REE) patterns of authigenic carbonate phases collected from modern seeps of the Gulf of Mexico, the Black Sea, and the Congo Fan were analyzed. Different carbonate minerals including aragonite and calcite with different crystal habits have been selected for analysis. Total REE content (SumREE) of seep carbonates varies widely, from 0.1 ppm to 42.5 ppm, but a common trend is that the SumREE in microcrystalline phases is higher than that of the associated later phases including micospar, sparite and blocky cement, suggesting that SumREE may be a function of diagenesis. The shale-normalized REE patterns of the seep carbonates often show different Ce anomalies even in samples from a specific site, suggesting that the formation conditions of seep carbonates are variable and complex. Overall, our results show that apart from anoxic, oxic conditions are at least temporarily common in seep environments.

Geochemistry of ODP Hole 135-839B basalts

Experimental phase relations were used to assess the role of volatiles and crustal level fractional crystallization in the petrogenesis of lavas from Hole 839B in the central Lau Basin. Melting experiments were performed on Sample 135-839B-15R-2, 63-67 cm, at 1 atm, anhydrous, and 2 kbar, H2O-saturated (~6 wt% H2O in the melt) to determine the influence of variable pressure and H2O content on phase appearances, mineral chemistry, and liquid line of descent followed during crystallization. The effects of H2O are to depress the liquidus by ~100°C, and to suppress crystallization of plagioclase and orthopyroxene relative to olivine and high-Ca clinopyroxene. At 1 atm, anhydrous, olivine and plagioclase coexist near the liquidus, whereas orthopyroxene and then clinopyroxene appear with decreasing temperature. Crystallization of 50 wt% produces a residual liquid that is rich in FeO* (10.8 wt%) and poor in Al2O3 (13.6 wt%). At 2 kbar, H2O-saturated, the liquidus phases are olivine and chromian spinel, with high-Ca clinopyroxene appearing after ~10% crystallization. Plagioclase saturation is suppressed until ~20% crystallization has occurred. The residual liquid from 35 wt% crystallization is rich in AI2O3 (17.4 wt%), and poor in MgO (4.82 wt%); it contains moderate FeO* (8.2 wt%), and resembles the low-MgO andesites recovered from Hole 839B. On the basis of these experiments we conclude that the primitive lavas recovered from Hole 839B have experienced crystallization along the Ol + Cpx saturation boundary, under hydrous conditions (an ankaramitic liquid line of descent), and variable amounts of olivine and chromian spinel accumulation. The low-MgO andesites from Hole 839B are the products of hydrous fractional crystallization, at crustal pressures, of a parent magma similar to basaltic andesite Sample 135-839B-15R-2, 63-67 cm.

Accumulation of glucose and protein hydrolysate by natural populations of microorganisms in the Black Sea and Atlantic Ocean

Accumulation rate of dissolved organic matter (DOM) by natural populations varies over a wide range. In the surface layer of the Black Sea accumulation rate of glucose is 0.6-4.82 mg C/m**3 per day, and in the Atlantic Ocean 1.15-12.38 mg C/m**3 per day. This rate is 2-17 times higher when hydrolysate is added to the medium. Accumulation rate of glucose and hydrolysate in the aphotic layer of the Black Sea and the Atlantic Ocean is 1.5-6 times lower than at the surface. The organotrophic coefficient also varied within wide range. Relative amount of DOM used by microorganisms for growth in total production is much less (0.6-39.9%) in areas of intensive photosynthesis than in waters poor in DOM (83.7-99.2%).