Isotopic composition of water in fog, rain, throughfall and stemflow in the Monte Verde, Costa Rica

Fog deposition, precipitation, throughfall and stemflow were measured in a windward tropical montane cloud forest near Monteverde, Costa Rica, for a 65-day period during the dry season of 2003. Net fog deposition was measured directly using the eddy covariance (EC) method and it amounted to 1.2 ± 0.1 mm/day (mean ± standard error). Fog water deposition was 5-9% of incident rainfall for the entire period, which is at the low end of previously reported values. Stable isotope concentrations (d18O and d2H) were determined in a large number of samples of each water component. Mass balance-based estimates of fog deposition were 1.0 ± 0.3 and 5.0 ± 2.7 mm/day (mean ± SE) when d18O and d2H were used as tracer, respectively. Comparisons between direct fog deposition measurements and the results of the mass balance model using d18O as a tracer indicated that the latter might be a good tool to estimate fog deposition in the absence of direct measurement under many (but not all) conditions. At 506 mm, measured water inputs over the 65 days (fog plus rain) fell short by 46 mm compared to the canopy output of 552 mm (throughfall, stemflow and interception evaporation). This discrepancy is attributed to the underestimation of rainfall during conditions of high wind.

Minerals of bulk and fine-grained (2 µm) samples from DSDP Leg 60

A bulk-sediment and clay-fraction X-ray diffraction study of samples from Deep Sea Drilling Project Leg 60 shows an abundance of the following minerals: plagioclase feldspar, zeolite, smectite, Fe-Mg chlorite, attapulgite, and serpentine. Amorphous compounds are also abundant. The variations in abundance of the different components correspond to episodes of volcanic activity through time. Deposits from periods of great activity are composed of sediments very rich in amorphous matter and in "primary" minerals (e.g., plagioclase feldspars). During relatively quiet periods, clay minerals and zeolites predominate.

Immobilisation data of juvenile and adult male and female Weddell seals at Drescher Inlet from expeditions DRE1990 and DRE1992

Fourten Weddell seals (Leptonychotes weddellii) and two crabeater seals (Lobodon carcinophaga) were immobilised at Drescher Inlet (Riiser Larsen Ice Shelf), eastern Weddell Sea coast, between January and February 1990 using a combination of ketamine, xylazine, and diazepam. Eleven Weddell seals were drugged once, and two and one were drugged two and three times each, coming to a total of 18 immobilisation procedures. Another 16 seals were immobilised between January and February 1992. Ten seals were drugged once, and three and two were drugged two and three times each, coming to a total of 25 immobilisation procedures. Narcoses were terminated with yohimbine. Data as given by doi:10.1594/PANGAEA.438920 were selected for publication. Data sets doi:10.1594/PANGAEA.438921 and doi:10.1594/PANGAEA.438926 followed the same methods and dose regimes.

Radicalización política y sectores populares en la Argentina de los '70 : La juventud peronista [JP] y su articulación con Montoneros en los barrios periféricos de la ciudad de La Plata

La Tesis, a través de un estudio de caso, se propone aportar una descripción empírica sobre los nexos que las organizaciones armadas establecieron con los sectores populares durante los '70 en la Argentina. Con ese propósito, reconstruye el sistema de unidades básicas organizado por la Juventud Peronista platense articulada con Montoneros en los barrios de la periferia platense entre 1972/74. Para el abordaje y comprensión de este conjunto, la investigación se ocupa previamente de la reconstrucción de aspectos de la larga trayectoria de la JP platense, previa a su articulación con Montoneros, durante los años '60, cuando delineo una estrategia de expansión política centrada en los ámbitos barriales, asimilando también una serie de influencias y prácticas producto de los procesos de radicalización en curso. Luego la tesis analiza el universo de las unidades básicas montoneras atendiendo a tres grandes componentes. Primero, los actores barriales más representativos: los militantes y las unidades básicas. Segundo, las prácticas sobre las que se sostuvo toda la experiencia: las de tipo reivindicativas y las más propiamente políticas. Por ultimo, el conjunto de representaciones que guiaron el debate y circulación de ideas: la recepción que tuvieron en el seno de las unidades básicas las concepciones criticas de los jóvenes montoneros en tomo a Perón y al peronismo y las nociones de socialismo y la lucha armada. La tesis permite apreciar la complejidad y variedad de lazos e intercambios que tuvieron lugar en el ámbito barrial montonero de la ciudad de La Plata y, a la vez, Ios límites y la dinámica que llevó a su disolución

Isotopic composition of the fine fraction of ODP Site 114-704

Ocean Drilling Program Site 704 in the subantarctic South Atlantic was drilled to investigate the response of the Southern Ocean to climatic and Oceanographic developments during the late Neogene. Stable oxygen and carbon isotopes of fine-fraction (<63 µm) carbonate were analyzed to supplement similar analyses of benthic and planktonic foraminifers. The fine fraction is generally composed primarily of coccoliths, and isotopic analyses of the fine fraction were made to complement the foraminiferal analyses. The isotopic curves thus generated suggest paleoceanographic changes not recognizable by the use of benthic and planktonic foraminifers alone. The global Chron 6 carbon isotope shift, found at 253-244 mbsf (6.39-6.0 Ma) at Site 704 in the planktonic and benthic record, is seen in the fine-fraction d13C record as a gradual decrease from 255 mbsf (6.44 Ma) to 210 mbsf (4.24 Ma). At 170 mbsf, mean d18O values of Neogloboquadrina pachyderma increase by 0.6 per mil-0.7 per mil (Hodell and Ciesielski, 1991, doi:10.2973/odp.proc.sr.114.150.1991), reflecting decreased temperature and increased continental ice volume. Accumulation rates increase by 3.3 times above this depth (which corresponds to an age of 2.5 Ma), suggesting increased upwelling and biologic productivity. Carbon isotopic values of fine-fraction carbonate decrease by about 1.5 per mil at 2.6 Ma; however, no change is recorded in the d13C of N. pachyderma. The fine-fraction d13C shift slightly precedes an average l per mil decrease in d13C in benthic foraminifers. The cause of the benthic d13C shift (most likely due to a change in deep water circulation; Hodell and Ciesielski, 1991) is probably not directly related to the fine-fraction shift. The fine-fraction shift is most likely caused by (1) a change in the upwelling to productivity ratio at this site, with increased upwelling bringing lighter carbon to surface waters, more productivity, and higher sedimentation rates and (2) a change in the particle composition of the fine fraction. The increased upwelling is probably due to a northward migration of the Antarctic Polar Front to a position nearer Site 704.

Facundo Tomás, Escrito, pintado (Dialéctica entre escritura e imágenes en la conformación del pensamiento europeo)

Fil: Hafter, Lea Evelyn. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.