2,093 research outputs found

    An integrated approach for evaluating the effectiveness of landslide risk reduction in unplanned communities in the Caribbean

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    Despite the recognition of the need for mitigation approaches to landslide risk in developing countries, the delivery of ‘on-the-ground’ measures is rarely undertaken. With respect to other ‘natural’ hazards it is widely reported that mitigation can pay. However, the lack of such an evidence-base in relation to landslides in developing countries hinders advocacy amongst decision makers for expenditure on ex-ante measures. This research addresses these limitations directly by developing and applying an integrated risk assessment and cost-benefit analysis of physical landslide mitigation measures implemented in an unplanned community in the Eastern Caribbean. In order to quantify the level of landslide risk reduction achieved, landslide hazard and vulnerability were modelled (before and after the intervention) and project costs, direct and indirect benefits were monetised. It is shown that the probability of landslide occurrence has been substantially reduced by implementing surface-water drainage measures, and that the benefits of the project outweigh the costs by a ratio of 2.7 to 1. This paper adds to the evidence base that ‘mitigation pays’ with respect to landslide risk in the most vulnerable communities – thus strengthening the argument for ex-ante measures. This integrated project evaluation methodology should be suitable for adoption as part of the community-based landslide mitigation project cycle, and it is hoped that this resource, and the results of this study, will stimulate further such programmes.Landslide modelling, Risk assessment, Cost Benefit Analysis, Developing countries, Community

    Quantifying loss aversion:Evidence from a UK population survey

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    TARIFA (Cádiz). Estrategia militar. 1840 (1811-1812)

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    Orientado con lis en rosa de 8 vientosRelieve representado por sombreadoRelación de los principales conventos, baterias, torres y casamatas indicada por clave alfabéticaNota relativa a que "El Sitio comenzó el 11 de diciembre de 1811 y terminó el 4 de enero de 1812

    Analysis of unsteady gas flow in a plain pipe exhaust system of a firing engine and its side effect upon the performance of a naturally aspirated two-stroke oil engine

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    The present investigation is part of a long term research programme dealing with the wave action in the exhaust and induction pipes of a two-stroke oil engine and their effect upon the cylinder scavenge process. As a development of fundamental researches carried out at the University Laboratories using simulated cylinder release pressures in a motored engine, the present investigation seeks to extend the established data to the practical problem of the engine under firing conditions. In this report, the theoretical analysis of unsteady one-dimensional gas flow, all owing for the effects of wall friction, heat exchange with the surroundings, and temperature discontinuities is developed, and the Method of Characteristics is applied to effect a solution. Theoretical exhaust pipe and cylinder indicator diagrams are evaluated using this theory, and compared with the experimental diagrams from the firing engine. From performance trials, the measured air consumption using a constant air/fuel ratio, but different exhaust pipe lengths and engine speeds, is evaluated and plotted on a dimensionless basis for comparison with the previous simulated work

    Adaptive radiation along a deeply conserved genetic line of least resistance in \u3cem\u3eAnolis\u3c/em\u3e lizards

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    On microevolutionary timescales, adaptive evolution depends upon both natural selection and the underlying genetic architecture of traits under selection, which may constrain evolutionary outcomes. Whether such genetic constraints shape phenotypic diversity over macroevolutionary timescales is more controversial, however. One key prediction is that genetic constraints should bias the early stages of species divergence along “genetic lines of least resistance” defined by the genetic (co)variance matrix, G. This bias is expected to erode over time as species means and G matrices diverge, allowing phenotypes to evolve away from the major axis of variation. We tested for evidence of this signal in West Indian Anolis lizards, an iconic example of adaptive radiation. We found that the major axis of morphological evolution was well aligned with a major axis of genetic variance shared by all species despite separation times of 20–40 million years, suggesting that divergence occurred along a conserved genetic line of least resistance. Further, this signal persisted even as G itself evolved, apparently because the largest evolutionary changes in G were themselves aligned with the line of genetic least resistance. Our results demonstrate that the signature of genetic constraint may persist over much longer timescales than previously appreciated, even in the presence of evolving genetic architecture. This pattern may have arisen either because pervasive constraints have biased the course of adaptive evolution or because the G matrix itself has been shaped by selection to conform to the adaptive landscape

    Rat cities and beehive worlds: density and design in the modern city

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    Nestled among E. M. Forster's careful studies of Edwardian social mores is a short story called "The Machine Stops." Set many years in the future, it is a work of science fiction that imagines all humanity housed in giant high-density cities buried deep below a lifeless surface. With each citizen cocooned in an identical private chamber, all interaction is mediated through the workings of "the Machine," a totalizing social system that controls every aspect of human life. Cultural variety has ceded to rigorous organization: everywhere is the same, everyone lives the same life. So hopelessly reliant is humanity upon the efficient operation of the Machine, that when the system begins to fail there is little the people can do, and so tightly ordered is the system that the failure spreads. At the story's conclusion, the collapse is total, and Forster's closing image offers a condemnation of the world they had built, and a hopeful glimpse of the world that might, in their absence, return: "The whole city was broken like a honeycomb. [⋯] For a moment they saw the nations of the dead, and, before they joined them, scraps of the untainted sky" (2001: 123). In physically breaking apart the city, there is an extent to which Forster is literalizing the device of the broken society, but it is also the case that the infrastructure of the Machine is so inseparable from its social structure that the failure of one causes the failure of the other. The city has-in the vocabulary of present-day engineers-"failed badly.
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