970 resultados para Davies, William, d. 1776.
Resumo:
From 1950 through 1900 studies on the glacial geology of northern Greenland have been made in cooperation with the U.S. Air Force Cambridge Research Laboratories. As a result of these studies four distinct phases of the latest glaciation have been recognized. The last glaciation extended over most of the land and removed traces of previous anes. Retreat of the ice mass began some time previous to 6000 years ago. This was followed by a rtse in sea level which deposited clay-silt succeeded by karne gravels around stagnant ice lobes in the large valleys. Marine terraces, up to 129 meters above present sea level, developed as readjustment occurred in the land free of ice. About 3700 years ago an advance of glaciers down major fjords took place followed by retreat to approximately the present position of the ice. Till in Peary Land, north of Frederick E. Hyde Fjord, contains only locally derived matertals indicating that the central Greenland ice cap did not cover the area.
Resumo:
Two medium-depth ice cores were retrieved from Berkner Island by a joint project between the Alfred-Wegener-Institut and the British Antarctic Survey in the 1994/95 field season. A 151m deep core from the northern dome (Reinwarthhöhe) of Berkner Island spans 700 years, while a 181m deep core from the southern dome (Thyssenhöhe) spans approximately 1200 years. Both cores display clear seasonal cycles in electrical conductivity measurements, allowing dating by annual-layer counting and the calculation of accumulation profiles. Stable-isotope measurements (both d18O and dD), together with the accumulation data, allow us to estimate changes in climate for most of the past millennium: the data show multi-decadal variability around a generally stable long-term mean. In addition, a full suite of major chemistry measurements is available to define the history of aerosol deposition at these sites: again, there is little evidence that the chemistry of the sites has changed over the past six centuries. Finally, we suggest that the southern dome, with an ice thickness of 950 m, is an ideal site from which to gain a climate history of the late stages of the last glacial and the deglaciation for comparison with the records from the deep Antarctic ice cores, and with other intermediate-depth cores such asTaylor Dome and Siple Dome.
Resumo:
Background. Ocean acidification as a result of increased anthropogenic CO2 emissions is occurring in marine and estuarine environments worldwide. The coastal ocean experiences additional daily and seasonal fluctuations in pH that can be lower than projected end of century open ocean pH reductions. Projected and current ocean acidification have wide-ranging effects on many aquatic organisms, however the exact mechanisms of the impacts of ocean acidification on many of these animals remains to be characterized. Methods. In order to assess the impact of ocean acidification on marine invertebrates, Pacific oysters (Crassostrea gigas) were exposed to one of four different pCO2 levels for four weeks: 400 µatm (pH 8.0), 800 µatm (pH 7.7), 1000 µatm (pH 7.6), or 2800 µatm (pH 7.3). At the end of 4 weeks a variety of physiological parameters were measured to assess the impacts of ocean acidification: tissue glycogen content and fatty acid profile, shell micromechanical properties, and response to acute heat shock. To determine the effects of ocean acidification on the underlying molecular physiology of oysters and their stress response, some of the oysters from 400 µatm and 2800 µatm were exposed to an additional mechanical stress and shotgun proteomics were done on oysters from high and low pCO2 and from with and without mechanical stress. Results. At the end of the four week exposure period, oysters in all four pCO2 environments deposited new shell, but growth rate was not different among the treatments. However, micromechanical properties of the new shell were compromised by elevated pCO2. Elevated pCO2 affected neither whole body fatty acid composition, nor glycogen content, nor mortality rate associated with acute heat shock. Shotgun proteomics revealed that several physiological pathways were significantly affected by ocean acidification, including antioxidant response, carbohydrate metabolism, and transcription and translation. Additionally, the proteomic response to a second stress differed with pCO2, with numerous processes significantly affected by mechanical stimulation at high versus low pCO2 (all proteomics data are available in the ProteomeXchange under the identifier PXD000835). Discussion. Oyster physiology is significantly altered by exposure to elevated pCO2, indicating changes in energy resource use. This is especially apparent in the assessment of the effects of pCO2 on the proteomic response to a second stress. The altered stress response illustrates that ocean acidification may impact how oysters respond to other changes in their environment. These data contribute to an integrative view of the effects of ocean acidification on oysters as well as physiological trade-offs during environmental stress.
Resumo:
O objetivo dessa tese é aprofundar, a partir do discurso pós-colonial, uma crise na perspectiva teológica da libertação. Esta promoveu, na dcada de 1970, uma reviravolta nos estudos teológicos no terceiro mundo. Para tanto, leremos um conto de Gabriel García Márquez chamado “El ahogado más hermosodel mundo” (1968) analizando e avaliando as estratégias políticas e culturais ali inscritas. Para levar a frente tal avaliação é preciso ampliar o escopo de uma visão que divide o mundo em secular/religioso, ou em ideias/práticas religiosas e não religiosas, para dar passo a uma visão unificada que compreende a mundanalidade, tanto do que é catalogado como ‘religioso’ quanto do que se pretende ‘não religioso’. A teologia/ciências da religião, como discurso científico sobre a economia das trocas que lidam com visões, compreensões e práticas de mundo marcadas pelo reconhecimento do mistério que lhes é inerente, possuem um papel fundamental na compreensão, explicitação, articulação e disponibilização de tais forças culturais. A percepção de existirem elementos no conto que se relacionam com os símbolos sobre Jesus/Cristo nos ofereceu um vetor de análise; entretanto, não nos deixamos limitar pelos grilhões disciplinares que essa simbologia implica. Ao mesmo tempo, esse vínculo, compreendido desde a relação imperial/colonial inerente aos discursos e imagens sobre Jesus-Cristo, embora sem centralizar a análise, não poderia ficar intocado. Partimos para a construção de uma estrutura teórica que explicitasse os valores, gestos, e horizontes mundanos do conto, cristológicos e não-cristológicos, contribuindo assim para uma desestabilização dos quadros tradicionais a partir dos quais se concebem a teologia e as ciências da religião, a obra de García Márquez como literatura, e a geografia imperial/colonial que postula o realismo ficcional de territórios como “América Latina”. Abrimos, assim, um espaço de significação que lê o conto como uma “não-cristologia”, deslocando o aprisionamento disciplinar e classificatório dos elementos envolvidos na análise. O discurso crítico de Edward Said, Homi Bhabha e GayatriSpivak soma-se à prática teórica de teólogas críticas feministas da Ásia, da África e da América Latina para formular o cenário político emancipatório que denominaremos teologia crítica secular.
Resumo:
Peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear hormone receptor that plays a key role in the differentiation of adipocytes. Activation of this receptor in liposarcomas and breast and colon cancer cells also induces cell growth inhibition and differentiation. In the present study, we show that PPARγ is expressed in human prostate adenocarcinomas and cell lines derived from these tumors. Activation of this receptor with specific ligands exerts an inhibitory effect on the growth of prostate cancer cell lines. Further, we show that prostate cancer and cell lines do not have intragenic mutations in the PPARγ gene, although 40% of the informative tumors have hemizygous deletions of this gene. Based on our preclinical data, we conducted a phase II clinical study in patients with advanced prostate cancer using troglitazone, a PPARγ ligand used for the treatment of type 2 diabetes. Forty-one men with histologically confirmed prostate cancer and no symptomatic metastatic disease were treated orally with troglitazone. An unexpectedly high incidence of prolonged stabilization of prostate-specific antigen was seen in patients treated with troglitazone. In addition, one patient had a dramatic decrease in serum prostate-specific antigen to nearly undetectable levels. These data suggest that PPARγ may serve as a biological modifier in human prostate cancer and its therapeutic potential in this disease should be further investigated.