Quantifying the drivers of ocean-atmosphere CO2 fluxes

A mechanistic framework for quantitatively mapping the regional drivers of air-sea CO2 fluxes at a global scale is developed. The framework evaluates the interplay between (1) surface heat and freshwater fluxes that influence the potential saturated carbon concentration, which depends on changes in sea surface temperature, salinity and alkalinity, (2) a residual, disequilibrium flux influenced by upwelling and entrainment of remineralized carbon- and nutrient-rich waters from the ocean interior, as well as rapid subduction of surface waters, (3) carbon uptake and export by biological activity as both soft tissue and carbonate, and (4) the effect on surface carbon concentrations due to freshwater precipitation or evaporation. In a steady state simulation of a coarse-resolution ocean circulation and biogeochemistry model, the sum of the individually determined components is close to the known total flux of the simulation. The leading order balance, identified in different dynamical regimes, is between the CO2 fluxes driven by surface heat fluxes and a combination of biologically driven carbon uptake and disequilibrium-driven carbon outgassing. The framework is still able to reconstruct simulated fluxes when evaluated using monthly averaged data and takes a form that can be applied consistently in models of different complexity and observations of the ocean. In this way, the framework may reveal differences in the balance of drivers acting across an ensemble of climate model simulations or be applied to an analysis and interpretation of the observed, real-world air-sea flux of CO2

Periodismo, nuevos medios y poder comunicacional

[es] El fenómeno de las redes sociales y su acelerado uso por audiencias y políticos, abre no pocas incógnitas en la ya compleja actividad periodística. La cada vez más acentuada interdependencia en red -de agendas globales- encuentra en el microblogging una fuente informativa de novedades locales que emergen de las redes sociales. Su atractivo: el suspenso de un “continuará…” que pone a sus protagonistas en un momento triunfal del relato, asociado a la espectacularidad de la polémica y a la continua sorpresa, que privilegia el melodrama en 140 caracteres al chequeo de fuentes. Los protagonistas de las noticias (sujetos del enunciado) encarnados en los llamados políticos 2.0 pasan a ser actores principales en la producción y circulación de la información (sujeto de la enunciación). Esta novedad subvierte el orden interpelante–interpelado entre medios y audiencias, escapa al simple análisis de contenidos y obliga a revisar cómo se establecen los “contratos de lectura” (Veron, 1985) que, a diferencia de aquellos estudios centrados sobre el soporte papel, hoy deben anexar los cláusulas preexistentes surgidas de las redes sociales, que no negocian e ingresan de manera indirecta y naturalizada en el newsmaking la agenda noticiosa. [en] The social networking phenomenon and its widespread use audiences and political, opens a few unknowns in the complex journalistic activity. The ever increasing interdependence network -global issues- located in the microblogging a source of local news information emerging from social networks. Its appeal: the suspense of a “continued ...” that puts its players in a triumphant moment in the story, coupled with the spectacular of the controversy and the continuing surprise, which favors the melodrama in 140 characters to check sources.The protagonists of news (subject of the statement) embodied in the so-called political 2.0 become major players in the production and circulation of information (the subject of enunciation). This development subverts the interpellation order between media and audiences, beyond the simple content analysis and requires review how to establish “contracts of reading” (Veron, 1985) which, unlike those studies focused on the paper, today must append the existing clauses arising from social networks that do not negotiate and enter indirectly and naturalized in the news making the news agend

Cytotoxic Activity of Paris quadrifolia Extract and Isolated Saponin Fractions Against Human Tumor Cell Lines

Steroidal saponins isolated from many plant species belonging to Monocotyledones display potent cytotoxic activity towards many human tumor cells. We examined the cytotoxic effects of crude Paris quadrifolia extract for the first time, testing isolated saponin-rich fractions against four different human cell lines using the [(3-(4,5- dimethylthiazol-2-yl)]-2,5-diphenyltetrazolium bromide (MTT) assay. Cytotoxic activity was tested against human promyelocytic leukemia (HL-60) cells, human cervical adenocarcinoma (HeLa) cells and human breast cancer (MDA-MB-468) cells. Human skin fibroblasts were used as non-neoplastic control cells. Our results show significant activity of the weakly water-soluble solid residue and butanolic fraction against HL-60 and HeLa cells. The solid residue exerted cytotoxicity against all tested cell lines