1,150 research outputs found

    Argumentation of the River Derwent using Thirlmere

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    This is the Argumentation of the River Derwent using Thirlmere produced by the Cumberland River Authority in 1972. This report focuses on the augmentation of the River Derwent by a limited discharge from the Thirlmere Reservoir in short terms. A Working Party of officers from both the Authority and the Corporation was established and experimental releases of water from Thirlmere were made in dry periods in order to assess more clearly their effect upon river flows, and on the level of Bassenthwaite Lake. This report contains the Working Party's evaluations, conclusions and recommendations

    Helicopter tail rotor orthogonal blade vortex interaction

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    The aerodynamic operating environment of the helicopter is particularly complex and, to some extent, dominated by the vortices trailed from the main and tail rotors. These vortices not only determine the form of the induced flow field but also interact with each other and with elements of the physical structure of the flight vehicle. Such interactions can have implications in terms of structural vibration, noise generation and flight performance. In this paper, the interaction of main rotor vortices with the helicopter tail rotor is considered and, in particular, the limiting case of the orthogonal interaction. The significance of the topic is introduced by highlighting the operational issues for helicopters arising from tail rotor interactions. The basic phenomenon is then described before experimental studies of the interaction are presented. Progress in numerical modelling is then considered and, finally, the prospects for future research in the area are discussed

    Improvements in Circumpolar Southern Hemisphere Extratropical Atmospheric Circulation in CMIP6 Compared to CMIP5

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    One of the major globally relevant systematic biases in previous generations of climate models has been an equatorward bias in the latitude of the Southern Hemisphere (SH) mid‐latitude tropospheric eddy driven westerly jet. The far reaching implications of this for Southern Ocean heat and carbon uptake and Antarctic land and sea ice are key reasons why addressing this bias is a high priority. It is therefore of primary importance to evaluate the representation of the SH westerly jet in the latest generation of global climate and earth‐system models that comprise the Coupled Model Intercomparison Project Phase 6 (CMIP6). In this paper we assess the representation of major indices of SH extratropical atmospheric circulation in CMIP6 by comparison against both observations and the previous generation of CMIP5 models. Indices assessed are the latitude and speed of the westerly jet, variability of the Southern Annular Mode (SAM) and representation of the Amundsen Sea Low (ASL). These are calculated from the historical forcing simulations of both CMIP5 and CMIP6 for time periods matching available observational and reanalysis datasets. From the 39 CMIP6 models available at the time of writing there is an overall reduction in the equatorward bias of the annual mean westerly jet from 1.9° in CMIP5 to 0.4° in CMIP6 and from a seasonal perspective the reduction is clearest in austral spring and summer. This is accompanied by a halving of the bias of SAM decorrelation timescales compared to CMIP5. However, no such overall improvements are evident for the ASL

    THE AMUNDSEN SEA LOW Variability, Change, and Impact on Antarctic Climate

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    The Amundsen Sea low (ASL) is a climatological low pressure center that exerts considerable influence on the climate of West Antarctica. Its potential to explain important recent changes in Antarctic climate, for example, in temperature and sea ice extent, means that it has become the focus of an increasing number of studies. Here, the authors summarize the current understanding of the ASL, using reanalysis datasets to analyze recent variability and trends, as well as ice-core chemistry and climate model projections, to examine past and future changes in the ASL, respectively. The ASL has deepened in recent decades, affecting the climate through its influence on the regional meridional wind field, which controls the advection of moisture and heat into the continent. Deepening of the ASL in spring is consistent with observed West Antarctic warming and greater sea ice extent in the Ross Sea. Climate model simulations for recent decades indicate that this deepening is mediated by tropical variability while climate model projections through the twenty-first century suggest that the ASL will deepen in some seasons in response to greenhouse gas concentration increases

    The prisoner's right to vote and civic responsibility: Reaffirming the social contract?

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    Copyright © 2009 NAPOThis article considers the issue of the prisoner’s right to vote in the light of recent developments in law and policy. It critically reviews the purported justifications for disenfranchisement and argues that re-enfranchisement should be pursued on the grounds of both principle and policy

    Come back Marshall, all is forgiven? : Complexity, evolution, mathematics and Marshallian exceptionalism

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    Marshall was the great synthesiser of neoclassical economics. Yet with his qualified assumption of self-interest, his emphasis on variation in economic evolution and his cautious attitude to the use of mathematics, Marshall differs fundamentally from other leading neoclassical contemporaries. Metaphors inspire more specific analogies and ontological assumptions, and Marshall used the guiding metaphor of Spencerian evolution. But unfortunately, the further development of a Marshallian evolutionary approach was undermined in part by theoretical problems within Spencer's theory. Yet some things can be salvaged from the Marshallian evolutionary vision. They may even be placed in a more viable Darwinian framework.Peer reviewedFinal Accepted Versio

    The hodograph method applicability in the problem of long-scale nonlinear dynamics of a thin vortex filament near a flat boundary

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    Hamiltonian dynamics of a thin vortex filament in ideal incompressible fluid near a flat fixed boundary is considered at the conditions that at any point of the curve determining shape of the filament the angle between tangent vector and the boundary plane is small, also the distance from a point on the curve to the plane is small in comparison with the curvature radius. The dynamics is shown to be effectively described by a nonlinear system of two (1+1)-dimensional partial differential equations. The hodograph transformation reduces that system to a single linear differential equation of the second order with separable variables. Simple solutions of the linear equation are investigated at real values of spectral parameter λ\lambda when the filament projection on the boundary plane has shape of a two-branch spiral or a smoothed angle, depending on the sign of λ\lambda.Comment: 9 pages, revtex4, 6 eps-figure

    Functional morphology of the forelimb of Early Miocene caviomorph rodents from Patagonia

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    Caviomorph rodents (New World Hystricognathi) are represented in the Santa Cruz Formation of Patagonia (Early Miocene, Santacrucian) by four superfamilies. From this unit, excellent cranial and associated postcranial remains of Neoreomys, Eocardia, Schistomys (Cavioidea), Perimys (Chinchilloidea) and Steiromys (Erethizontoidea) are known. To interpret their use of substrate, a comparative description of limb bones (scapula, humerus, radius and ulna) of the five genera was performed within a taxonomic and ecologically diverse sample of extant rodents. Using palaeobiological inferences based on the habits and functional morphology of members of the extant sample, hypotheses were generated for the use of substrate by the Santacrucian taxa. Neoreomys would have had a marked flexo-extension capacity of the humerus and a moderate flexion of the manus. This genus and Eocardia would have had a complete and stabilized forearm extension, with wide stride and moderate extension of the forearm for the latter. Schistomys presents features similar to Eocardia. Perimys would have had strong external rotation of the humerus, moderate flexion of the manus and moderate, complete and stabilized extension of the forearm. Steiromys would have had good pronation/supination capacity, strong internal rotation of the humerus and flexion of the forearm and manus. Neoreomys would have been ambulatory and an occasional runner. Eocardia and Schistomys would have been good runners. Perimys would have been a digger and Steiromys a climber. This morphological disparity reflects a high ecological diversity, compatible with differential use of space during the Santacrucian.Fil: Muñoz, Nahuel Antu. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Toledo, Néstor. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Candela, Adriana Magdalena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Vizcaíno, Sergio Fabiån. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

    X-Ray Scattering Measurements of the Transient Structure of a Driven Charge-Density-Wave

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    We report time-resolved x-ray scattering measurements of the transient structural response of the sliding {\bf Q}1_{1} charge-density-wave (CDW) in NbSe3_{3} to a reversal of the driving electric field. The observed time scale characterizing this response at 70K varies from ∌\sim 15 msec for driving fields near threshold to ∌\sim 2 msec for fields well above threshold. The position and time-dependent strain of the CDW is analyzed in terms of a phenomenological equation of motion for the phase of the CDW order parameter. The value of the damping constant, Îł=(3.2±0.7)×10−19\gamma = (3.2 \pm 0.7) \times 10^{-19} eV ⋅\cdot seconds ⋅\cdot \AA−3^{-3}, is in excellent agreement with the value determined from transport measurements. As the driving field approaches threshold from above, the line shape becomes bimodal, suggesting that the CDW does not depin throughout the entire sample at one well-defined voltage.Comment: revtex 3.0, 7 figure
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