30,932 research outputs found

    Identifying pathways of exposure to highway pollutants in great crested newt (Triturus cristatus) road mitigation tunnels: Exposure pathways of highway pollutants to Triturus cristatus

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    Road mitigation tunnels are increasingly deployed for amphibians but very little is known about chemical pollution in such schemes. We assessed pollution pressures associated with road runoff at a major great crested newt mitigation scheme in England. Sediments and waters in the mitigation system were analysed for major physico-chemical parameters, trace metals and total petroleum hydrocarbons and compared to a nearby reference site. Seven out of eight tested metals including copper, zinc, lead and iron were in significantly greater concentrations in the tunnels than at a reference site and at environmentally significant concentrations. Water samples also exhibited elevated concentrations of aluminium and chromium and occasionally extreme alkaline pH associated with leaching of portlandite in tunnel cements. High conductivity values in waters and sediments corresponding with seasonal de-icing salt application were also apparent. The study highlights the potential pollutant pressures for amphibians associated with large-scale urban development and road mitigation schemes

    An experimental and theoretical evaluation of increased thermal diffusivity phase change devices

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    This study was to experimentally evaluate and mathematically model the performance of phase change thermal control devices containing high thermal conductivity metal matrices. Three aluminum honeycomb filters were evaluated at five different heat flux levels using n-oct-adecane as the test material. The system was mathematically modeled by approximating the partial differential equations with a three-dimensional implicit alternating direction technique. The mathematical model predicts the system quite well. All of the phase change times are predicted. The heating of solid phase is predicted exactly while there is some variation between theoretical and experimental results in the liquid phase. This variation in the liquid phase could be accounted for by the fact that there are some heat losses in the cell and there could be some convection in the experimental system

    Modelling Malaria Control

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    White discusses a new study that models the impact of deploying intermittent presumptive treatment of malaria upon the spread of drug resistance

    Convergence across Spanish Provinces:Cross-section and Pairwise Evidence

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    Distribution free statistics are employed to investigate biennial income per capita convergence across 52 Spanish provinces over the period 1955-1997. Based upon ideas of concordance and discordance that capture convergence and divergence properties, the paper presents results that suggest convergence is dominant for the full sample over the entire period, swings in this trend between convergence and divergence are present and switching in rank does take place. When provinces are analysed in pairs some show strong evidence of divergence.Convergence; Steady state; Average UK regional male wages

    Geothermal studies - Yellowstone National Park /test site 11/, Wyoming

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    Summary report of diamond drilling in thermal areas of Yellowstone National Park, and method for determining heat flow in thermal area

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    Real-time dynamics in spin-1/2 chains with adaptive time-dependent DMRG

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    We investigate the influence of different interaction strengths and dimerizations on the magnetization transport in antiferromagnetic spin-1/2 XXZ-chains. We focus on the real-time evolution of the inhomogeneous initial state with all spins pointing up along the z axis in the left half and down in the right half of the chain, using the adaptive time-dependent density-matrix renormalization group (adaptive t-DMRG). We find on time-scales accessible to us ballistic magnetization transport for small Sz-Sz-interaction and arbitrary dimerization, but almost no transport for stronger Sz-Sz-interaction, with a sharp crossover at Jz=1. At Jz=1 results indicate superdiffusive transport. Additionally, we perform a detailed analysis of the error made by the adaptive time-dependent DMRG using the fact that the evolution in the XX-model is known exactly. We find that the error at small times is dominated by the error made by the Trotter decomposition, whereas for longer times the DMRG truncation error becomes the most important, with a very sharp crossover at some "runaway" time.Comment: 13 pages, 20 figure
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