12,396 research outputs found

    Oil Prices and the Impact of Rising Economies

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    •The first commercial oil well was drilled in Romania in 1857, since then oil has been playing a crucial role in the global economy. •High oil prices can slow economic growth, cause inflationary pressures and create global imbalances. •High oil prices and tight market conditions have also raised fears about oil scarcity and concerns about energy security in many oil- importing countries. •The supply-demand factor seems to be popular among the factors that outweigh the impact of Organization of Petroleum Exporting Countries (OPEC)

    EXPANDING WIC FARMER'S MARKETS

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    Food Security and Poverty,

    Current-induced reversal in magnetic nanopillars passivated by silicon

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    We demonstrate that magnetic multilayer nanopillars can be efficiently protected from oxidation by coating with silicon. Both the protected and the oxidized nanopillars exhibit an increase of reversal current at cryogenic temperatures. However the magnetic excitation onset current increases only in the oxidized samples. We show that oxidized nanopillars exhibit anomalous switching statistics at low temperature, providing a simple test for the quality of magnetic nanodevices.Comment: 3 pages, 4 figure

    On blowup for Yang-Mills fields

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    We study development of singularities for the spherically symmetric Yang-Mills equations in d+1d+1 dimensional Minkowski spacetime for d=4d=4 (the critical dimension) and d=5d=5 (the lowest supercritical dimension). Using combined numerical and analytical methods we show in both cases that generic solutions starting with sufficiently large initial data blow up in finite time. The mechanism of singularity formation depends on the dimension: in d=5d=5 the blowup is exactly self-similar while in d=4d=4 the blowup is only approximately self-similar and can be viewed as the adiabatic shrinking of the marginally stable static solution. The threshold for blowup and the connection with critical phenomena in the gravitational collapse (which motivated this research) are also briefly discussed.Comment: 4 pages, 3 figures, submitted to Physical Review Letter

    Integrals of motion and the shape of the attractor for the Lorenz model

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    In this paper, we consider three-dimensional dynamical systems, as for example the Lorenz model. For these systems, we introduce a method for obtaining families of two-dimensional surfaces such that trajectories cross each surface of the family in the same direction. For obtaining these surfaces, we are guided by the integrals of motion that exist for particular values of the parameters of the system. Nonetheless families of surfaces are obtained for arbitrary values of these parameters. Only a bounded region of the phase space is not filled by these surfaces. The global attractor of the system must be contained in this region. In this way, we obtain information on the shape and location of the global attractor. These results are more restrictive than similar bounds that have been recently found by the method of Lyapunov functions.Comment: 17 pages,12 figures. PACS numbers : 05.45.+b / 02.30.Hq Accepted for publication in Physics Letters A. e-mails : [email protected] & [email protected]
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