998 resultados para 201-1230B


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A method for quantifying in situ dissolved methane concentrations in sediment cores that have gas voids is described. The method relies on normalizing methane (CH4) in the gas voids to nitrogen (N2) and/or argon (Ar). The principles of the method are presented. The method was tested during Ocean Drilling Program Leg 201, and preliminary results indicate that it can be used to generate reproducible and accurate dissolved methane values if argon and nitrogen are both measured or if one is measured along with pressure of the gas void.

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Marine sediments harbor an enormous quantity of microorganisms, including a multitude of novel species. The habitable zone of the marine sediment column begins at the sediment-water interface and probably extends to depths of several thousands of meters. Studies of the microbial diversity in this ecosystem have mostly relied on molecular biological techniques. We used a complementary method - analysis of intact polar membrane lipids - to characterize the in-situ microbial community in sediments covering a wide range of environmental conditions from Peru Margin, Equatorial Pacific, Hydrate Ridge, and Juan de Fuca Ridge. Bacterial and eukaryotic phospholipids were only detected in surface sediments from the Peru Margin. In contrast, deeply buried sediments, independent of their geographic location, were dominated by archaeal diether and tetraether lipids with various polar head groups and core lipids. We compared ring distributions of archaeal tetraether lipids derived from polar glycosidic precursors with those that are present as core lipids. The distributions of these related compound pools were distinct, suggestive of different archaeal sources, i.e., the polar compounds derive from sedimentary communities and the core lipids are fossil remnants from planktonic communities with possible admixtures of decayed sedimentary archaea. This in-situ production of distinct archaeal lipid populations potentially affects applications of the TEX86 paleotemperature proxy as demonstrated by offsets in reconstructed temperatures between both pools. We evaluated how varying cell and lipid stabilities will influence the sedimentary pool by using a box-model. The results are consistent with (i) a requirement of continuous inputs of freshly synthesized lipids in subsurface sediments for explaining the observed distribution of intact polar lipids, and (ii) decreasing lipid inputs with increasing burial depth.

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Early diagenetic dolomite beds were sampled during the Ocean Drilling Programme (ODP) Leg 201 at four reoccupied ODP Leg 112 sites on the Peru continental margin (Sites 1227/684, 1228/680, 1229/681 and 1230/685) and analysed for petrography, mineralogy, d13C, d18O and 87Sr/86Sr values. The results are compared with the chemistry, and d13C and 87Sr/86Sr values of the associated porewater. Petrographic relationships indicate that dolomite forms as a primary precipitate in porous diatom ooze and siliciclastic sediment and is not replacing the small amounts of precursor carbonate. Dolomite precipitation often pre-dates the formation of framboidal pyrite. Most dolomite layers show 87Sr/86Sr-ratios similar to the composition of Quaternary seawater and do not indicate a contribution from the hypersaline brine, which is present at a greater burial depth. Also, the d13C values of the dolomite are not in equilibrium with the d13C values of the dissolved inorganic carbon in the associated modern porewater. Both petrography and 87Sr/86Sr ratios suggest a shallow depth of dolomite formation in the uppermost sediment (<30 m below the seafloor). A significant depletion in the dissolved Mg and Ca in the porewater constrains the present site of dolomite precipitation, which co-occurs with a sharp increase in alkalinity and microbial cell concentration at the sulphate-methane interface. It has been hypothesized that microbial 'hot-spots', such as the sulphate-methane interface, may act as focused sites of dolomite precipitation. Varying d13C values from -15 per mil to +15 per mil for the dolomite are consistent with precipitation at a dynamic sulphate-methane interface, where d13C of the dissolved inorganic carbon would likewise be variable. A dynamic deep biosphere with upward and downward migration of the sulphate-methane interface can be simulated using a simple numerical diffusion model for sulphate concentration in a sedimentary sequence with variable input of organic matter. Thus, the study of dolomite layers in ancient organic carbon-rich sedimentary sequences can provide a useful window into the palaeo-dynamics of the deep biosphere.

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Contenido: El aristotelismo y el tomismo frente al egoísmo psicológico / María L. Lukac de Stier – El deseo natural de ver a Dios en la Summa contra Gentiles / Guillermo Jorge Cambiasso – La creación como encuentro del ser y de la nada en la teología del maestro Eckhart de Hochheim O.P. (1260-1327) / Brian J. Farrelly – Malebranche y el libertinage érudit / Francisco Leocata – The problem of person and Jean Mouroux / John M. McDermott ; Glenn J. Comandini – Los fundamentos de la Bioética de H. Tristram Engelhardt / Jorge Martínez Barrera – Cuando las contradictorias son verdaderas / Marisa Villalba de Tablón – Examen del escepticismo moral y del relativismo moral / Camilo Tale – Saint Thomas et le mystère de la création : une réponse aux interrogations de l’homme d’aujourd’hui / Marie-Dominique Philippe – La finalidad de la naturaleza humana : alcance y actualidad de la cuestión / Beatriz Eugenia Reyes Oribe – La providencia y el gobierno del mundo / Alberto Caturelli – Saint Thomas et le problème de la possibilité d’un univers créé éternel / Alain-Marie de Lassus – La causalidad material de los elementos en la generación de los cuerpos mixtos / Mario Enrique Sacchi -- Bibliografía

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Consultoria Legislativa - Área I - Direito Constitucional, Eleitoral, Municipal, Direito Administrativo, Processo Legislativo e Poder Judiciário.

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No Plenário da Assembleia Nacional Constituinte (ANC), discussão de emendas populares que tratam dos direitos e da aposentadoria dos trabalhadores e da reforma urbana. O representante da Arquidiocese do Rio de Janeiro, Carlos Roberto Castro, defende uma emenda em favor do usucapião nas favelas cariocas, após cinco anos, e em terrenos urbanos abandonados, após dois anos. Adib Jorge, representante sindical, defende emenda popular que prevê aposentadoria mais justa aos trabalhadores. O Deputado Farabulini Júnior (PTB-SP) defende a paridade dos salários entre os trabalhadores da ativa e os aposentados e pensionistas. Em nome da CUT (Central Única dos Trabalhadores), o Deputado Paulo Paim (PT-RS) fala em defesa da emenda popular dos direitos dos trabalhadores e declara que o eixo dessa emenda é a estabilidade no emprego, as quarenta horas semanais e o direito de greve. Na próxima Sessão Extraordinária serão discutidas emendas populares que tratam da estabilidade no emprego, participação nos lucros e democratização da administração das empresas, reforma urbana, transporte coletivo e moradia popular. O projeto de Constituição do Relator Bernardo Cabral permite o pluralismo sindical. O Deputado Juarez Antunes (PDT-RJ) considera que o pluralismo sindical só favorece a classe empresarial. Marival Campos, Presidente do Sindicato dos Petroleiros-BA, informa que é uma tentativa do patronato de dividir os trabalhadores cada vez mais. Luiz Machado, Presidente do Sindicato dos Urbanitários-RJ, afirma que será desenvolvido um trabalho junto aos parlamentares para que esse dispositivo não seja aprovado. O Deputado Mario Lima (PMDB-BA) informa que só deve haver um sindicato de cada categoria em cada base territorial. O Deputado Afif Domingos (PL-SP) considera que nada impede a coexistência de mais de um sindicato dentro da mesma base, contanto que apenas um seja o representante nos dissídios da categoria perante a lei. O Deputado Paes Landim (PFL-PI) afirma que tanto faz a unicidade ou pluralismo, desde que os sindicatos tenham liberdade e possam atuar livres da interferência do Estado. O Deputado Augusto Carvalho (PCB-DF) declara que só se os trabalhadores se unirem em um único sindicato terão força suficiente para poder enfrentar o patronato.