CO2 perturbation experiments: similarities and differences between dissolved inorganic carbon and total alkalinity manipulations

Increasing atmospheric carbon dioxide (CO2) through human activities and invasion of anthropogenic CO2 into the surface ocean alters the seawater carbonate chemistry, increasing CO2 and bicarbonate (HCO3−) at the expense of carbonate ion (CO32−) concentrations. This redistribution in the dissolved inorganic carbon (DIC) pool decreases pH and carbonate saturation state (Ω). Several components of the carbonate system are considered potential key variables influencing for instance calcium carbonate precipitation in marine calcifiers such as coccolithophores, foraminifera, corals, mollusks and echinoderms. Unravelling the sensitivities of marine organisms and ecosystems to CO2 induced ocean acidification (OA) requires well-controlled experimental setups and accurate carbonate system manipulations. Here we describe and analyse the chemical changes involved in the two basic approaches for carbonate chemistry manipulation, i.e. changing DIC at constant total alkalinity (TA) and changing TA at constant DIC. Furthermore, we briefly introduce several methods to experimentally manipulate DIC and TA. Finally, we examine responses obtained with both approaches using published results for the coccolithophore Emiliania huxleyi. We conclude that under most experimental conditions in the context of ocean acidification DIC and TA manipulations yield similar changes in all parameters of the carbonate system, which implies direct comparability of data obtained with the two basic approaches for CO2 perturbation

Statistical transmutation of quantum bosonic strings coupled to general four-dimensional Chern-Simons theory

A bosonic string coupled to the generalized Chern-Simons theory in 3+1D acquires a magnetic field along itself, when it is closed, and a topological charge at its extremity, when it is open. We construct the creation operators for the full quantum field states associated to these strings and determine the dual algebra satisfied by them. We show that the creation operator fo the composite state of a quantum closed bosonic string, bearing a magnetic flux, and a topologically charged open bosonic string, possesses generalized statistics. The relation of our results with previous approaches to the problem is also established.Comment: 4 pages, Revtex

Short-term response of the coccolithophore Emiliania huxleyi to an abrupt change in seawater carbon dioxide concentrations

The response of the coccolithophore Emiliania huxleyi to rising CO2 concentrations is well documented for acclimated cultures where cells are exposed to the CO2 treatments for several generations prior to the experiment. The exact number of generations required for acclimation to CO2-induced changes in seawater carbonate chemistry, however, is unknown. Here we show that Emiliania huxleyi's short-term response (26 h) after cultures (grown at 500 μatm) were abruptly exposed to changed CO2 concentrations (~190, 410, 800 and 1500 μatm) is similar to that obtained with acclimated cultures under comparable conditions in earlier studies. Most importantly, from the lower CO2 levels (190 and 410 μatm) to 750 and 1500 μatm calcification decreased and organic carbon fixation increased within the first 8 to 14 h after exposing the cultures to changes in carbonate chemistry. This suggests that Emiliania huxleyi rapidly alters the rates of essential metabolical processes in response to changes in seawater carbonate chemistry, establishing a new physiological "state" (acclimation) within a matter of hours. If this relatively rapid response applies to other phytoplankton species, it may simplify interpretation of studies with natural communities (e.g. mesocosm studies and ship-board incubations), where often it is not feasible to allow for a pre-conditioning phase before starting experimental incubations

Dendê: futuro do Amazonas.

Ecologia. Mercado. Estimativas. Potencial do Amazonas.bitstream/item/198356/1/Dende-futuro-do-Amazonas.pd

O ENGAJAMENTO POLÍTICO CULTURAL DE NIETZSCHE EM SUAS REFLEXÕES SOBRE A ARTE

A presente pesquisa pretende abordar como Nietzsche foi um pensador extremamente engajado com as questões culturais de sua época em suas reflexões sobre a arte. Tomando como pano de fundo, a ideia de um Nietzsche que através da filosofia e pela arte, faz uma crítica à cultura, em última instância, o que defenderemos nessa pesquisa é um conceito de engajamento que está ancorado nas reflexões de Nietzsche sobre a arte, mas que, no entanto, indicam que ele não tinha apenas uma preocupação puramente estética, mas, sim político cultural. Esta hipótese de engajamento político cultural será demonstrada através dos conceitos de Bildung e de música popular nos escritos do primeiro Nietzsche. Findando nosso trabalho o texto O Caso Wagner será analisado político culturalmente como crítica ao projeto da modernidade, trabalhando conceitos como décadence, niilismo, arte decadente, indústria cultural e grande política; sedimentando a ideia geral de um Nietzsche engajado político culturalmente. Palavras chaves: Engajamento político-cultural. Arte. Extemporaneidade. Crítica. Modernidade. Niilismo. Décadence. Grande política

Geometric Quantization of Topological Gauge Theories

We study the symplectic quantization of Abelian gauge theories in $2+1$ space-time dimensions with the introduction of a topological Chern-Simons term.Comment: 13 pages, plain TEX, IF/UFRJ/9