990 resultados para 172-1062
Resumo:
Reflectance spectra collected during ODP Leg 172 were used in concert with solid phase iron chemistry, carbonate content, and organic carbon content measurements to evaluate the agents responsible for setting the color in sediments. Factor analysis has proved a valuable and rapid technique to detect the local and regional primary factors that influence sediment color. On the western North Atlantic drifts, sediment color is the result of primary mineralogy as well as diagenetic changes. Sediment lightness is controlled by the carbonate content while the hue is primarily due to the presence of hematite and Fe2+/Fe3+ changes in clay minerals. Hematite, most likely derived from the Permo-Carboniferous red beds of the Canadian Maritimes, is differentially preserved at various sites due to differences in reductive diagenesis and dilution by other sedimentary components. Various intensities for diagenesis result from changes in organic carbon content, sedimentation rates, and H2S production via anaerobic methane oxidation. Iron monosulfides occur extensively at all high sedimentation sites especially in glacial periods suggesting increased high terrigenous flux and/or increased reactive iron flux in glacials.
Resumo:
Geomagnetic excursions are recognized as intrinsic features of the Earth's magnetic field. High-resolution records of field behaviour, captured in marine sedimentary cores, present an opportunity to determine the temporal and geometric character of the field during geomagnetic excursions and provide constraints on the mechanisms producing field variability. We present here the highest resolution record yet published of the Blake geomagnetic excursion (~125 ka) measured in three cores from Ocean Drilling Program (ODP) Site 1062 on the Blake-Bahama Outer Ridge. The Blake excursion has a controversial structure and timing but these cores have a sufficiently high sedimentation rate (~10cm/ka) to allow detailed reconstruction of the field behaviour at this site during the excursion. Palaeomagnetic measurements of the cores reveal rapid transitions (<500 yr) between the contemporary stable normal polarity and a completely reversed state of long duration which spans a stratigraphic interval of 0.7 m. We determine the duration of the reversed state during the Blake excursion using oxygen isotope stratigraphy, combined with 230Th excess measurements to assess variations in the sedimentation rates through the sections of interest. This provides an age and duration for the Blake excursion with greater accuracy and with constrained uncertainty. We date the directional excursion as falling between 129 and 122 ka with a duration for the deviation of 6.5±1.3 kyr. The long duration of this interval and the fully reversed field suggest the existence of a pseudo-stable, reversed dipole field component during the excursion and challenge the idea that excursions are always of short duration.
Resumo:
Abyssal mud waves (or fine-grained sediment waves) are often cited as evidence for deep current activity because subbottom profiles show that the wave form has migrated with time. The migration history of a fine-grained sediment wave on the Blake-Bahama Outer Ridge (ODP Site 1062) has been studied through the analysis of multiple ODP holes spaced across the wave. Additional information about wave migration patterns comes from 3.5-kHz records and watergun seismic profiles. These data suggest that wave migration has varied during the last not, vert, similar ~10 Myr, although the only sediments sampled are younger than 4.8 Ma. Seismic profiles suggest wave migration was initiated about 8-10 Ma, and wave migration was pronounced from about 5 Ma to about 1 Ma (with an episode of wave reorganization about 4.5 Ma). Analysis of ODP cores suggests that migration rates have been somewhat lower and more variable during the last 1 Myr. Intervals of no wave migration are observed for several time intervals and appear to characterize deglaciations, especially during the last 500 kyr. Comparisons between seismic profiles and the core record show that most of the seismic horizons correlate closely with time horizons, and thus that the seismic profiles give a reasonable representation of sediment wave migration. Models suggest that wave migration is more pronounced during periods of higher bottom current flow and less pronounced during periods of lower current flow. Thus the migration record is consistent with generally higher bottom flow speeds at this site prior to 1 Ma and lower bottom flow speeds after 1 Ma. The Mid-Pleistocene Transition from a dominant climatic periodicity of 40 kyr to a dominant climatic periodicity of 100 kyr starts at about this time, suggesting an overall reduction in bottom flow speed at this site coincident with changing climate patterns. These changes in flow speed could be related to changes in the depth of the Western Boundary Undercurrent as well as to changes in the speed of thermohaline circulation.
Resumo:
Ten ODP sites drilled in a depth transect (2164-4775 m water depth) during Leg 172 recovered high-deposition rate (>20 cm/kyr) sedimentary sections from sediment drifts in the western North Atlantic. For each site an age model covering the past 0.8-0.9 Ma has been developed. The time scales have a resolution of 10-20 kyr and are derived by tuning variations of estimated carbonate content to the orbital parameters precession and obliquity. Based on the similarity in the signature of proxy records and the spectral character of the time series, the sites are divided into two groups: precession cycles are better developed in carbonate records from a group of shallow sites (2164-2975 m water depth, Sites 1055-1058) while the deeper sites (2995-4775 m water depth, Sites 1060-1063) are characterized by higher spectral density in the obliquity band. The resulting time scales show excellent coherence with other dated carbonate and isotope records from low latitudes. Besides the typical Milankovitch cyclicity significant variance of the resulting carbonate time series is concentrated at millennial-scale changes with periods of about 12, 6, 4, 2.5, and 1.5 kyr. Comparisons of carbonate records from the Blake Bahama Outer Ridge and the Bermuda Rise reveal a remarkable similarity in the time and frequency domain indicating a basin-wide uniform sedimentation pattern during the last 0.9 Ma.
Resumo:
Background: This open-label, randomised phase III study was designed to further investigate the clinical activity and safety of SRL172 (killed Mycobacterium vaccae suspension) with chemotherapy in the treatment of non-small-cell lung cancer (NSCLC). Patients and methods: Patients were randomised to receive platinum-based chemotherapy, consisting of up to six cycles of MVP (mitomycin, vinblastine and cisplatin or carboplatin) with (210 patients) or without (209 patients) monthly SRL172. Results: There was no statistical difference between the two groups in overall survival (primary efficacy end point) over the course of the study (median overall survival of 223 days versus 225 days; P = 0.65). However, a higher proportion of patients were alive at the end of the 15-week treatment phase in the chemotherapy plus SRL172 group (90%), than in the chemotherapy alone group (83%) (P = 0.061). At the end of the treatment phase, the response rate was 37% in the combined group and 33% in the chemotherapy alone group. Patients in the chemotherapy alone group had greater deterioration in their Global Health Status score (-14.3) than patients in the chemotherapy plus SRL172 group (-6.6) (P = 0.02). Conclusion: In this non-placebo controlled trial, SRL172 when added to standard cancer chemotherapy significantly improved patient quality of life without affecting overall survival times. © 2004 European Society for Medical Oncology.
Resumo:
Contenido: Naturaleza del conocimiento humano : el significado de la abstracción en Santo Tomás (II) / Octavio Nicolás Derisi – Nacimiento, vida y transfiguración del filósofo griego / Cesáreo López Salgado – La transformación ockhamista de la teoría de la suposición / Ignacio Miralbell – La noción de lugar en Guillermo de Ockham / Olga L. Larre ; J. E. Bolzán – Notas y comentarios -- Bibliografía
Resumo:
O chamado Grupo dos Trinta e Dois Constituintes revisou o projeto de Constituição, do Relator Bernardo Cabral (PMDB-AM), e reduziu o texto para duzentos e cinquenta artigos. O Deputado Israel Pinheiro (PMDB-MG) declara que o texto constitucional ficou mais organizado, mais articulado, após a revisão. Não houve preocupação em tocar nos pontos polêmicos do projeto, mas apenas de enxugar o texto original, deixando para a lei ordinária o que não é constitucional. O Senador Virgílio Távora (PDS-CE) considera que foi uma tentativa válida de auxílio. O Deputado Ulysses Guimarães (PMDB-SP), a quem foi entregue a nova versão, considerou que é uma contribuição importante, assim como outras tantas que chegarão. Balanço da primeira semana de entrega das emendas populares a Assembleia Nacional Constituinte (ANC). Representantes de empregados em empresas de telecomunicações de todo o país entregam emenda na qual pedem a manutenção do monopólio estatal nos serviços de telecomunicação e a criação do Conselho Nacional de Comunicação, que garanta a cada brasileiro o direito à informação livre e sem censura. Representantes das cooperativas entregam emenda na qual pedem a auto-gestão dos seus negócios, o ensino do cooperativismo e a isenção de impostos. Roberto Rodrigues, representante das cooperados, diz que quando a cooperativa vende algum insumo para o cooperado, cobrando dele um diferencial referente ao custo operacional da cooperativa, não pode haver incidência de imposto. O Deputado Ivo Vanderlinde (PMDB-SC) considera positivo o fortalecimento do cooperativismo. O Deputado Bernardo Cabral (PMDB-AM) mostra entusiasmo ao receber as emendas populares. Fernando Gabeira, jornalista e escritor, convoca o povo a participar.
Resumo:
Parlamentares de todos os partidos procuram o consenso em torno do projeto de Constituição. O Deputado Israel Pinheiro Filho (PMDB-MG) esclarece que a preocupação é encontrar um texto constitucional que seja mais reduzido, mais enxuto, mas que represente a vontade da sociedade brasileira. Pacifistas denunciam a fabricação indiscriminada de armas nucleares, quarenta e dois anos após a Bomba de Hiroshima. O atual projeto de Constituição admite o uso da energia nuclear somente para fins pacíficos. O Deputado Fabio Feldmann (PMDB-SP) esclarece que muitas pessoas defendem a bomba atômica como um instrumento da paz, o que é um claro absurdo. Ele apoia a emenda popular proposta pela Sociedade Brasileira para o Progresso da Ciência (SBPC) que proíbe a bomba atômica brasileira. Sessão Extraordinária da Assembleia Nacional Constituinte (ANC) debateu a Reforma Agrária. O Deputado Roberto Jefferson (PTB-RJ) criticou a esquerda e considera que a distinção entre terras improdutivas e terras inexploradas deve ser feita pela justiça, pois a violência inviabilizará a Reforma Agrária. O Deputado Aldo Arantes (PC do B-GO) afirma que o atual projeto é a expressão da vontade dos latifundiários e propõe limite ao tamanho das propriedades rurais.