3,521 research outputs found

    Finite-Size Scaling in Two-dimensional Continuum Percolation Models

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    We test the universal finite-size scaling of the cluster mass order parameter in two-dimensional (2D) isotropic and directed continuum percolation models below the percolation threshold by computer simulations. We found that the simulation data in the 2D continuum models obey the same scaling expression of mass M to sample size L as generally accepted for isotropic lattice problems, but with a positive sign of the slope in the ln-ln plot of M versus L. Another interesting aspect of the finite-size 2D models is also suggested by plotting the normalized mass in 2D continuum and lattice bond percolation models, versus an effective percolation parameter, independently of the system structure (i.e. lattice or continuum) and of the possible directions allowed for percolation (i.e. isotropic or directed) in regions close to the percolation thresholds. Our study is the first attempt to map the scaling behaviour of the mass for both lattice and continuum model systems into one curve.Comment: 9 pages, Revtex, 2 PostScript figure

    The empirical evaluation of thermal conduction coefficient of some liquid composite heat insulating materials

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    We experimentally determined the coefficients of thermal conductivity of some ultra thin liquid composite heat insulating coatings, for sample 1 [lambda]=0.086 W/(m [x] C), for sample 2 [lambda]= 0.091 W/(m [x] C). We performed the measurement error calculation. The actual thermal conduction coefficient of the studied samples was higher than the declared one. The manufactures of liquid coatings might have used some "ideal" conditions when defining heat conductivity in the laboratory or the coefficient was obtained by means of theoretical solution of heat conduction problem in liquid composite insulating media. However, liquid insulating coatings are of great interest to builders, because they allow to warm objects of complex geometric shapes (valve chambers, complex assemblies, etc.), which makes them virtually irreplaceable. The proper accounting of heating qualities of paints will allow to avoid heat loss increase above the specified limits in insulated pipes with heat transfer materials or building structures, as well as protect them from possible thawing in the period of subzero weather

    The empirical definition of total emissivity of modern super-thin liquid composite thermal insulators

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    Modern world trends in the field of energy and mineral resources preservation policy involves the need for a more cost-efficient use of the Earth's natural resources, including in the field of construction industry. Using insulation modern materials would largely solve this problem. The acceptability appraisal of various advanced heat-insulating blankets is a crucial task, which requires experimental verification of total emissivity empirical definition of modern super-thin liquid composite thermal insulators and their real value definition. Method of investigation is as follows: an empirical definition of blankets emissivity using the proposed laboratory equipment, which comprises a system of "gray" bodies, thermocouple probe and a source of continuous heat flux. Total emissivity of modern super-thin liquid composite thermal insulators is experimentally determined. It amounted e = 0.89 for sample # 1, and e = 0.87 for sample # 2 at a temperature of 35-65 °C. It was found that the actual emissivity of the samples was higher than it had been declared

    Mammalian Lipopolysaccharide Receptors Incorporated into the Retroviral Envelope Augment Virus Transmission

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    SummaryThe orally transmitted retrovirus mouse mammary tumor virus (MMTV) requires the intestinal microbiota for persistence. Virion-associated lipopolysaccharide (LPS) activates Toll-like receptor 4 (TLR4), stimulating production of the immunosuppressive cytokine IL-10 and MMTV evasion of host immunity. However, the mechanisms by which MMTV associates with LPS remain unknown. We find that the viral envelope contains the mammalian LPS-binding factors CD14, TLR4, and MD-2, which, in conjunction with LPS-binding protein (LBP), bind LPS to the virus and augment transmission. MMTV isolated from infected mice lacking these LBPs cannot engage LPS or stimulate TLR4 and have a transmission defect. Furthermore, MMTV incorporation of a weak agonist LPS from Bacteroides, a prevalent LPS source in the gut, significantly enhances the ability of this LPS to stimulate TLR4, suggesting that MMTV intensifies these immunostimulatory properties. Thus, an orally transmitted retrovirus can capture, modify, and exploit mammalian receptors for bacterial ligands to ensure successful transmission

    Penetration of hot electrons through a cold disordered wire

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    We study a penetration of an electron with high energy E<<T through strongly disordered wire of length L<<a (a being the localization length). Such an electron can loose, but not gain the energy, when hopping from one localized state to another. We have found a distribution function for the transmission coefficient t. The typical t remains exponentially small in L/a, but with the decrement, reduced compared to the case of direct elastic tunnelling. The distribution function has a relatively strong tail in the domain of anomalously high t; the average ~(a/L)^2 is controlled by rare configurations of disorder, corresponding to this tail.Comment: 4 pages, 5 figure

    Universal Crossover between Efros-Shklovskii and Mott Variable-Range-Hopping Regimes

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    A universal scaling function, describing the crossover between the Mott and the Efros-Shklovskii hopping regimes, is derived, using the percolation picture of transport in strongly localized systems. This function is agrees very well with experimental data. Quantitative comparison with experiment allows for the possible determination of the role played by polarons in the transport.Comment: 7 pages + 1 figure, Revte

    The Current State of Climate Change Perceptions and Policies in Vietnam: 2014 Report

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    This report was constructed to assess the current perceptions and policies regarding climate change in Vietnam. The report comprises a country report, outlining current policies relating to climate change, stakeholder mapping regarding climate change locally and nationally, and results from two stakeholder perception surveys conducted locally and nationally in Vietnam. A total of 50 stakeholders were interviewed, 25 locally and 25 nationally. The stakeholders in the survey represented government offices, universities, research institutions, NGOs, and farmers’ groups. Concerns about climate change impacts included drought, flooding, rainfall variation, and salinity intrusion. These concerns, as well as the methods in which stakeholders would like to receive climate information, varied between local and national stakeholders as well as by the type of institution that the stakeholder represented. This emphasizes a need for location- and user-specific responses to climate change
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