2,682 research outputs found

    Design considerations for lunar base photovoltaic power systems

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    A survey was made of factors that may affect the design of photovoltaic arrays for a lunar base. These factors, which include the lunar environment and system design criteria, are examined. A photovoltaic power system design with a triangular array geometry is discussed and compared to a nuclear reactor power systems and a power system utilizing both nuclear and solar power sources

    The limitations of whiteness and the boundaries of Englishness: second-generation Irish identifications and positionings in multiethnic Britain

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    The focus of this article is the second-generation Irish in England. It is based on data collected as part of the Irish 2 project, which examined processes of identity formation amongst the second-generation Irish population in England and Scotland. The article examines and maps identifications and positionings of second-generation Irish people and discusses how two hegemonic domains - Ireland and England - intersect in the lives of the children of Irish-born parents, with material and psychological consequences. Their positionings in multiethnic Britain are compared with those of ‘visible’ minority ethnic groups, and their narratives of belonging and non-belonging are analysed in terms of the limitations of whiteness and the boundaries of Englishness

    Scientific basis for safely shutting in the Macondo Well after the April 20, 2010 Deepwater Horizon blowout

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    As part of the government response to the Deepwater Horizon blowout, a Well Integrity Team evaluated the geologic hazards of shutting in the Macondo Well at the seafloor and determined the conditions under which it could safely be undertaken. Of particular concern was the possibility that, under the anticipated high shut-in pressures, oil could leak out of the well casing below the seafloor. Such a leak could lead to new geologic pathways for hydrocarbon release to the Gulf of Mexico. Evaluating this hazard required analyses of 2D and 3D seismic surveys, seafloor bathymetry, sediment properties, geophysical well logs, and drilling data to assess the geological, hydrological, and geomechanical conditions around the Macondo Well. After the well was successfully capped and shut in on July 15, 2010, a variety of monitoring activities were used to assess subsurface well integrity. These activities included acquisition of wellhead pressure data, marine multichannel seismic pro- files, seafloor and water-column sonar surveys, and wellhead visual/acoustic monitoring. These data showed that the Macondo Well was not leaking after shut in, and therefore, it could remain safely shut until reservoir pressures were suppressed (killed) with heavy drilling mud and the well was sealed with cement

    Family stories, public silence: Irish identity construction amongst the second-generation Irish in England

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    Formal narratives of history, especially that of colonial oppression, have been central to the construction of national identities in Ireland. But the Irish diasporic community in Britain has been cut off from the reproduction of these narratives, most notably by their absence from the curriculum of Catholic schools, as result of the unofficial 'denationalisation' pact agreed by the Church in the 19th century (Hickman, 1995). The reproduction of Irish identities is largely a private matter, carried out within the home through family accounts of local connections, often reinforced by extended visits to parent/s 'home' areas. Recapturing a public dimension has often become a personal quest in adulthood, 'filling in the gaps'. This paper explores constructions of narratives of nation by a key diasporic population, those with one or two Irish-born parents. It places particular emphasis on varying regional/national contexts within which such constructions take place, drawing on focus group discussions and interviews for the ESRC-funded Irish 2 Project in five locations — London, Glasgow, Manchester, Coventry and Banbury

    Hypotonicity-induced changes in anion permeability of cultured rat brain endothelial cells

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    AbstractIodide efflux, an index of anion permeability, has been monitored in cultured rat brain endothelial cells. Following hypotonicity-induced swelling, large, rapid increases in permeability occur, the extent of these increases depending on the degree of hypotonicity. Such large responses are not observed with rat aortic endothelial cells. Results of anion substitution experiments suggest that iodide efflux is via a chloride channel rather than an exchanger. The efflux increase is blocked by NPPB (100 μM) but not by DIDS or DPC at 100 μM. It is dependent on intracellular ATP but unaffected by removal of external calcium. Increasing internal calcium using A23187 does not produce a change in efflux, but depletion of calcium reduces or eliminates the response to hypotonicity. The response is reduced by pimozide (2–50 μM) that inhibits the actions of calmodulin and by pBPB (10 μM) that affects phospholipase A2 activity. It is eliminated by 5-lipoxygenase inhibitors (L-656,224 and ETH615, 10 μM) but is unaffected by cyclo-oxygenase inhibitors (indomethacin and piroxicam, 1–100 μM). It is blocked by some modulators of P-glycoprotein activity, e.g., verapamil (100 μM), tamoxifen (50 μM), and progesterone (100 μM) but not by others, e,g., forskolin (40 μM), dideoxyforskolin (40 μM), quinidine (100 μM) and cyclosporin A (10 μM)

    A new method for ranking academic journals in accounting and finance

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    Given the many and varied uses to which journal rankings are put, interest in ranking journal 'quality' is likely to persist. Unfortunately, existing methods of constructing such rankings all have inherent limitations. This paper proposes a new (complementary) approach, based on submissions to RAE 2001, which is not restricted to a pre-defined journal set and, importantly, is based on quality choice decisions driven by economic incentives. For three metrics, submissions to RAE 2001 are compared with the available set of publications to provide evidence on the perception of journal quality, a fourth metric is based on the overall RAE grades, and an overall ranking is produced

    Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model

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    We present a numerical model of the ocean that couples a three-stream radiative transfer component with a marine biogeochemical–ecosystem component in a dynamic three-dimensional physical framework. The radiative transfer component resolves the penetration of spectral irradiance as it is absorbed and scattered within the water column. We explicitly include the effect of several optically important water constituents (different phytoplankton functional types; detrital particles; and coloured dissolved organic matter, CDOM). The model is evaluated against in situ-observed and satellite-derived products. In particular we compare to concurrently measured biogeochemical, ecosystem, and optical data along a meridional transect of the Atlantic Ocean. The simulation captures the patterns and magnitudes of these data, and estimates surface upwelling irradiance analogous to that observed by ocean colour satellite instruments. We find that incorporating the different optically important constituents explicitly and including spectral irradiance was crucial to capture the variability in the depth of the subsurface chlorophyll a (Chl a) maximum. We conduct a series of sensitivity experiments to demonstrate, globally, the relative importance of each of the water constituents, as well as the crucial feedbacks between the light field, the relative fitness of phytoplankton types, and the biogeochemistry of the ocean. CDOM has proportionally more importance at attenuating light at short wavelengths and in more productive waters, phytoplankton absorption is relatively more important at the subsurface Chl a maximum, and water molecules have the greatest contribution when concentrations of other constituents are low, such as in the oligotrophic gyres. Scattering had less effect on attenuation, but since it is important for the amount and type of upwelling irradiance, it is crucial for setting sea surface reflectance. Strikingly, sensitivity experiments in which absorption by any of the optical constituents was increased led to a decrease in the size of the oligotrophic regions of the subtropical gyres: lateral nutrient supplies were enhanced as a result of decreasing high-latitude productivity. This new model that captures bio-optical feedbacks will be important for improving our understanding of the role of light and optical constituents on ocean biogeochemistry, especially in a changing environment. Further, resolving surface upwelling irradiance will make it easier to connect to satellite-derived products in the future
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