997 resultados para 193-1190C
Resumo:
A geochemical, mineralogical, and isotopic database comprising 75 analyses of Ocean Drilling Program (ODP) Leg 193 samples has been prepared, representing the variable dacitic volcanic facies and alteration types observed in drill core from the subsurface of the PACMANUS hydrothermal system (Table T1. The data set comprises major elements, trace and rare earth elements (REE), various volatiles (S, F, Cl, S, SO4, CO2, and H2O), and analyses of 18O and 86Sr/87Sr for bulk rock and mineral separates (anhydrite). Furthermore, normative mineral proportions have been calculated based on the results of X-ray diffraction (XRD) analysis (Table T2) using the SOLVER function of the Microsoft Excel program. Several of the samples analyzed consist of mesoscopically distinctive domains, and separate powders were generated to investigate these hand specimen-scale heterogeneities. Images of all the samples are collated in Figure F1, illustrating the location of each powder analyzed and documenting which measurements were performed.
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Leg 193 was the fourth Ocean Drilling Program expedition focusing on understanding subseafloor hydrothermal systems. This program was the first to combine studies of the volcanology, structure, hydrology, mineralization, and microbiology of a subseafloor hydrothermal system hosted by felsic rocks by coring at the PACMANUS hydrothermal field in the Manus Basin, Papua New Guinea. The study examines only the petrology and bulk rock and mineral chemistry of the freshest and most morphologically youthful lava flows recovered from the shallowest drill cores at the four sites occupied during Leg 193. There are subtle but distinct petrographic and geochemical variations between the closely spaced sites.
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This study presents a systematic analysis and interpretation of autonomous underwater vehicle-based microbathymetry combined with remotely operated vehicle (ROV) video recordings, rock analyses and temperaturemeasurements within the PACManus hydrothermal area located on Pual Ridge in the Bismarck Sea of eastern Manus Basin. The data obtained during research cruise Magellan-06 and So-216 provides a framework for understanding the relationship between the volcanism, tectonismand hydrothermal activity. PACManus is a submarine felsic vocanically-hosted hydrothermal area that hosts multiple vent fields locatedwithin several hundredmeters of one another but with different fluid chemistries, vent temperatures and morphologies. The total area of hydrothermal activity is estimated to be 20,279m**2. Themicrobathymetrymaps combinedwith the ROV video observations allow for precise high-resolution mapping estimates of the areal extents of hydrothermal activity.We find the distribution of hydrothermal fields in the PACManus area is primarily controlled by volcanic features that include lava domes, thick andmassive blocky lava flows, breccias and feeder dykes. Spatial variation in the permeability of local volcanic facies appears to control the distribution of venting within a field.We define a three-stage chronological sequence for the volcanic evolution of the PACManus based on lava flow morphology, sediment cover and lava SiO2 concentration. In Stage-1, sparsely to moderately porphyritic dacite lavas (68-69.8 wt.% SiO2) erupted to form domes or cryptodomes. In Stage-2, aphyric lava with slightly lower SiO2 concentrations (67.2-67.9 wt.% SiO2) formed jumbled and pillowed lava flows. In the most recent phase Stage-3, massive blocky lavaswith 69 to 72.5wt.% SiO2were erupted throughmultiple vents constructing a volcanic ridge identified as the PACManus neovolcanic zone. The transition between these stages may be gradual and related to progressive heating of a silicic magma following a recharge event of hot, mantle-derived melts.
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Mycobacterium leprae recA harbors an in-frame insertion sequence that encodes an intein homing endonuclease (PI-MleI). Most inteins (intein endonucleases) possess two conserved LAGLIDADG (DOD) motifs at their ctive center. A common feature of LAGLIDADG-type homing endonucleases is that they recognize and cleave the same or very similar DNA sequences. However, PI-MleI is distinctive from other members of the family of LAGLIDADG-type HEases for its modular structure with functionally separable domains for DNA-binding and cleavage, each with distinct sequence preferences. Sequence alignment analyses of PI-MleI revealed three putative LAGLIDADG motifs; however, there is conflicting bioinformatics data in regard to their identity and specific location within the intein polypeptide. To resolve this conflict and to determine the active-site residues essential for DNA target site recognition and double-stranded DNA cleavage, we performed site-directed mutagenesis of presumptive catalytic residues in the LAGLIDADG motifs. Analysis of target DNA recognition and kinetic parameters of the wild-type PI-MleI and its variants disclosed that the two amino acid residues, Asp(122) (in Block C) and Asp(193) (in functional Block E), are crucial to the double-stranded DNA endonuclease activity, whereas Asp(218) (in pseudo-Block E) is not. However, despite the reduced catalytic activity, the PI-MleI variants, like the wild-type PI-MleI, generated a footprint of the same length around the insertion site. The D122T variant showed significantly reduced catalytic activity, and D122A and D193A mutations although failed to affect their DNA-binding affinities, but abolished the double-stranded DNA cleavage activity. On the other hand, D122C variant showed approximately twofold higher double-stranded DNA cleavage activity, compared with the wild-type PI-MleI. These results provide compelling evidence that Asp(122) and Asp(193) in DOD motif I and II, respectively, are bona fide active-site residues essential for DNA cleavage activity. The implications of these results are discussed in this report.
Resumo:
O Relator da Comissão de Sistematização da Assembleia Nacional Constituinte, Bernardo Cabral (PMDB-AM), reunido com os relatores adjuntos, tratou de alguns pontos polêmicos ainda não definidos tais como imissão de posse de terras, anistia e a educação. Os pontos já definidos do projeto de Constituição são: sistema de governo com parlamentarismo brando; distinção entre empresa 100% nacional e empresa brasileira com capital estrangeiro; estabilidade no emprego substituída por proibição de demissões arbitrárias; jornada de 40 horas saiu do projeto e ficou para lei ordinária; criado o Serviço Nacional de Saúde com participação da iniciativa privada; reserva de mercado temporária em áreas estratégicas; concessões de rádio e TV poderão ser cassadas pelo Congresso Nacional. Encontro do Deputado Bernardo Cabral (PMDB-AM) com os líderes partidários não consegue consenso. A maioria dos líderes não concorda com o projeto de Constituição tal como está. O Deputado Brandão Monteiro (PDT-RJ) afirma que este projeto de Constituição representa um grande acordo entre as elites e que haverá reação a isso. O Deputado José Genoino (PT-SP) considera que estão cortando os avanços conseguidos na fase das comissões temáticas da Assembleia Nacional Constituinte. O Deputado Haroldo de Lima (PC do B-BA) declara que é muito importante que o movimento popular se manifeste contra o projeto. O Deputado Euclides Scalco (PMDB-PR) declara que houve articulação multipartidária e que não há razão para críticas ao projeto. O Deputado Stélio Dias (PFL-ES) propõe o retorno do projeto para nova discussão nas comissões temáticas. O Deputado Naphytali Alves (PMDB-GO) declara que 35 anos de trabalho para todas as categorias de trabalhadores é um retrocesso. O Deputado Fábio Feldmann (PMDB-SP) afirma que estão querendo tirar do texto as conquistas obtidas no que diz respeito ao meio ambiente. O Relator Adjunto Senador Fernando Henrique Cardoso (PMDB-SP) considera que, antes de opinar, as pessoas devem ler os projetos.