Inorganic carbon and geochemistry measurements from landfast sea ice in Resolute Passage, Nunavut, Canada, as part of the Arctic-ICE project, May - June 2010

We conducted a six-week investigation of the sea ice inorganic carbon system during the winter-spring transition in the Canadian Arctic Archipelago. Samples for the determination of sea ice geochemistry were collected in conjunction with physical and biological parameters as part of the 2010 Arctic-ICE (Arctic - Ice-Covered Ecosystem in a Rapidly Changing Environment) program, a sea ice-based process study in Resolute Passage, Nunavut. The goal of Arctic-ICE was to determine the physical-biological processes controlling the timing of primary production in Arctic landfast sea ice and to better understand the influence of these processes on the drawdown and release of climatically active gases. The field study was conducted from 1 May to 21 June, 2010.

Late Pliocene stratigraphic distribution of Globoconella taxa in the North Atlantic

Quantitative records of Globorotalia puncticulata and Globorotalia inflata, the last two members of the Globorotalia (Globoconella) lineage, obtained from North Atlantic sediments collected at DSDP Site 552, ODP Site 659 and ODP Site 665, are used to examine fluctuations in the biogeographic distribution of these species in the Late Pliocene between 3 and 2 Ma. Abundance data indicate that prior to the expansion of Northern Hemisphere glaciation at about 2.5 Ma, Gr. puncticulata was an important component of the planktonic foraminiferal fauna and had a geographic distribution ranging from 2°N to at least 56°N in the North Atlantic. A previously undescribed 6 chambered variant of Gr. puncticulata is found at both Sites 659 and 665. The stratigraphic distribution of this morphotype is restricted, first occurring at 2.9 Ma and then disappearing when glacial intensity increased at 2.75 Ma (isotope stage 110). Similar declines in Gr. puncticulata abundances occurred during glacial isotope stages 102, 100, and 98 immediately prior to the extinction of Gr. puncticulata during glacial isotope stage 96. It appears that this extinction event was latitudinally diachronous within the North Atlantic, occurring earliest in the north at Site 552 (2.453 Ma), then at Site 659 (2.443 Ma) and later still in the Site 665 equatorial record (2.438 Ma). At Site 665 the first record of Gr. inflata occurs during glacial isotope stage 94 (2.416 Ma), shortly after the extinction of Gr. puncticulata. In the mid latitude North Atlantic there was a 340,000 year period following the disappearance of Gr. puncticulata when the Globoconella lineage was absent (the Gr. inflata gap). The Gr. inflata population found in the equatorial Atlantic must therefore have been introduced from the South Atlantic, probably by the South Equatorial Current. Faunal records from Sites 552 and 659 show that it was not until glacial isotope stage 78 (2.10 Ma) that Gr. inflata became widely established in the North Atlantic. Prior to this large-scale migration event, there were two limited colonisation events during glacial isotope stages 86 and 82 when Gr. inflata populations reached as far as Site 659 in the eastern North Atlantic. These incursions are believed to be reflect the entrainment of Gr. inflata within South Atlantic Central Water and the northward subsurface transport of individuals to the coastal upwelling zone off northwest Africa. It seems likely that the same mechanism was responsible for the re-establishment of the Globoconella lineage in the North Atlantic at 2.10 Ma, but in this instance additional factors, such as enhanced glacial circulation patterns and ecological changes within planktonic foraminiferal faunas, resulted in the successful expansion of Gr. inflata across the North Atlantic and the Mediterranean.

Pensar con el cuerpo : ¿Una política? 'No se puede pensar sin un cierto estado de enardecimiento sexual'

"No se puede pensar sin un cierto estado de enardecimiento sexual" Impulsadas por la fecundidad de esta idea de Nietszche venimos recorriendo un trayecto como grupo de pensamiento filosófico desde hace cuatro años. En nuestra producción colectiva nos hacemos eco de aquellos pensadores -Spinoza, Nietszche, Foucault, Deleuze, Agamben y Badiou- que proponen una inversión de la tradición filosófica que excluye al cuerpo del pensamiento. Desde este marco teórico nos proponemos desplegar en estas jornadas interrogantes acerca de la manera en que el cuerpo -objeto eminente de la biología- deviene factor político, dando surgimiento a la biopolítica. Junto a esta cuestión incluimos paralelamente el problema de las relaciones de poder y el modo de afección sobre los cuerpos y sus potencias colectivas.

Una aproximación al proceso de configuración de la identidad política y social de la central de trabajadores argentinos

Fil: Gusmerotti, Lucrecia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

(Table 1) Bioclimatic subzones and soil characteristics along the Yamal Arctic Transect, northwestern Siberia

Sustainability of tundra vegetation under changing climate on the Yamal Peninsula, northwestern Siberia, home to the world's largest area of reindeer husbandry, is of crucial importance to the local native community. An integrated investigation is needed for better understanding of the effects of soils, climate change and grazing on tundra vegetation in the Yamal region. In this study we applied a nutrient-based plant community model - ArcVeg - to evaluate how two factors (soil organic nitrogen (SON) levels and grazing) interact to affect tundra responses to climate warming across a latitudinal climatic gradient on the Yamal Peninsula. Model simulations were driven by field-collected soil data and expected grazing patterns along the Yamal Arctic Transect (YAT), within bioclimate subzones C (high arctic), D (northern low arctic) and E (southern low arctic). Plant biomass and NPP (net primary productivity) were significantly increased with warmer bioclimate subzones, greater soil nutrient levels and temporal climate warming, while they declined with higher grazing frequency. Temporal climate warming of 2 °C caused an increase of 665 g/m**2 in total biomass at the high SON site in subzone E, but only 298 g/m**2 at the low SON site. When grazing frequency was also increased, total biomass increased by only 369 g/m**2 at the high SON site in contrast to 184 g/m**2 at the low SON site in subzone E. Our results suggest that high SON can support greater plant biomass and plant responses to climate warming, while low SON and grazing may limit plant response to climate change. In addition to the first order factors (SON, bioclimate subzones, grazing and temporal climate warming), interactions among these significantly affect plant biomass and productivity in the arctic tundra and should not be ignored in regional scale studies.

"Palo a Pique": Anales de la Sociedad Rural

La presente comunicación analiza la posición de la Sociedad Rural de Gualeguaychú ante diversas políticas públicas destinadas al agro entre 1979 y 1982 a través de la publicación vocera de la entidad, la revista Palo a Pique , nacida en 1979 con el subtítulo de Anales de la Sociedad Rural. La revista que trata diversas cuestiones vinculadas al sector agrícola, tiene la función de informar y educar al productor, al tiempo que pretende reflejar sus demandas frente al Estado nacional y provincial, cuando éstos aplican medidas de carácter tributario que atentan -según la publicación- contra el normal desarrollo de las actividades rurales.

Products of chlorophyll diagenesis from DSDP Leg 57 Holes

Tetrapyrrole pigments isolated from sediments retrieved during Leg 57 include pheophytin-a, a myriad of chlorins, free-base deoxophylloerythroetioporphyrin (DPEP), as well as copper and nickel porphyrins. Their richness, both qualitatively and quantitatively, in chlorin tetrapyrroles affords a relatively complete study on the early diagenesis of chlorophyll. Our studies, coupled with those in the preceding chapter by Louda et al., point out the influence of pre- and postdepositional environments upon the mode of chlorophyll diagenesis. Formation of tetrapyrroles, collectively called "petroporphyrins," is seen to occur in only a limited set of environmental conditions (see Baker and Palmer, 1978). The more generalized route of chlorophyll diagenesis, at least in the ocean, results in removal of tetrapyrrole pigment, from the fossil record. Late diagenetic products, metalloporphyrins, are found to represent an extremely minor component of the tetrapyrrole assemblage in sediments studied from the Japan Trench. The products of chlorophyll diagenesis isolated from Japan Trench sediments allow expansion of previous diagenetic schemes (Baker and Palmer, 1978; Triebs, 1936) and indicate directions for future studies.

Una aproximación al proceso de configuración de la identidad política y social de la central de trabajadores argentinos

Fil: Gusmerotti, Lucrecia. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

"Palo a Pique": Anales de la Sociedad Rural

La presente comunicación analiza la posición de la Sociedad Rural de Gualeguaychú ante diversas políticas públicas destinadas al agro entre 1979 y 1982 a través de la publicación vocera de la entidad, la revista Palo a Pique , nacida en 1979 con el subtítulo de Anales de la Sociedad Rural. La revista que trata diversas cuestiones vinculadas al sector agrícola, tiene la función de informar y educar al productor, al tiempo que pretende reflejar sus demandas frente al Estado nacional y provincial, cuando éstos aplican medidas de carácter tributario que atentan -según la publicación- contra el normal desarrollo de las actividades rurales.