5,865 research outputs found

    Decoupling Transition I. Flux Lattices in Pure Layered Superconductors

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    We study the decoupling transition of flux lattices in a layered superconductors at which the Josephson coupling J is renormalized to zero. We identify the order parameter and related correlations; the latter are shown to decay as a power law in the decoupled phase. Within 2nd order renormalization group we find that the transition is always continuous, in contrast with results of the self consistent harmonic approximation. The critical temperature for weak J is ~1/B, where B is the magnetic field, while for strong J it is~1/sqrt{B} and is strongly enhanced. We show that renormaliztion group can be used to evaluate the Josephson plasma frequency and find that for weak J it is~1/BT^2 in the decoupled phase.Comment: 14 pages, 5 figures. New sections III, V. Companion to following article on "Decoupling and Depinning II: Flux lattices in disordered layered superconductors

    Intentional Job Discrimination-New Tools for Our Oldest Problem

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    The roots of employment discrimination lie deep in our history. By the 18th century, race slavery was the underpinning of wealth in the southern colonies. Black slaves were considered property - subhumans who had no rights in themselves or their offspring. In 1765, the British imposed stamp taxes on the colonies; the colonies resisted. In 1766, Parliament claimed the power to govern the colonies in all matters, but by 1770 it had repealed almost all the taxes that offended the colonists. Business as usual returned to the relations between the colonies and Britain

    Crop Choice, Non-Target Pest Levels, Yield Loss and Their Effect on Insecticide Use in South Dakota

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    Agriculturally, South Dakota is a unique state possessing the highest rate of adoption for genetically modified crop varieties. In 2009 ninety-six percent of corn acres planted in South Dakota were genetically modified compared with eighty-five percent nationally (Economic Research Service). Additionally, South Dakota has seen a dramatic increase in the number of acres treated with insecticide over the past 20 years. These two situations taken together seem to be counterintuitive. Some genetically modified varieties, such as Bt corn, are equipped with genetic defenses so that they can protect the plant from target pests. Intuitively, one would expect to see a decrease in insecticide use as adoption of genetically modified varieties increase. Recent studies have found that there is a reduction in herbicides applied to herbicide tolerant varieties. Here in South Dakota, though, producers have expressed the opinion that the increase in insecticide use is the result of the emergence and spread of the soybean aphid in the state. This research seeks to address the underlying causes of the increase in insecticide use.Bt corn, GM crops, insecticide, Agricultural and Food Policy, Crop Production/Industries, Q1, Q2, Q5,

    Attitudes of Rural Middle-School Youth Toward Alcohol, Tobacco, Drugs, and Violence

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    Since 1996, our research team has conducted 15 focus groups with 169 middle-school youth in small communities as formative research for campaigns against alcohol, tobacco, drugs, and violence. Some key findings of a synthesis of focus-group results are that girls and boys perceive different risks to alcohol and tobacco use; peer relationships are important, but there is great potential for parents to increase influence; females and Hispanic youth are most concerned about serving as good role models; and youth prefer campaign materials that feature typical youth and activities

    Tachyonic perturbations in AdS5_5 orbifolds

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    We show that scalar as well as vector and tensor metric perturbations in the Randall-Sundrum II braneworld allow normalizable tachyonic modes, i.e., possible instabilities. These instabilities require nonvanishing initial anisotropic stresses on the brane. We show with a specific example that within the Randall-Sundrum II model, even though the tachyonic modes are excited, no instability develops. We argue, however, that in the cosmological context instabilities might in principle be present. We conjecture that the tachyonic modes are due to the singularity of the orbifold construction. We illustrate this with a simple but explicit toy model.Comment: 11 pages, matches published versio

    On graviton production in braneworld cosmology

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    We study braneworlds in a five dimensional bulk, where cosmological expansion is mimicked by motion through AdS5_5. We show that the five dimensional graviton reduces to the four dimensional one in the late time approximation of such braneworlds. Inserting a fixed regulator brane far from the physical brane, we investigate quantum graviton production due to the motion of the brane. We show that the massive Kaluza-Klein modes decouple completely from the massless mode and they are not generated at all in the limit where the regulator brane position goes to infinity. In the low energy limit, the massless four dimensional graviton obeys the usual 4d equation and is therefore also not generated in a radiation-dominated universe.Comment: 9 pages, minor changes, references correcte

    Area Regge Calculus and Discontinuous Metrics

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    Taking the triangle areas as independent variables in the theory of Regge calculus can lead to ambiguities in the edge lengths, which can be interpreted as discontinuities in the metric. We construct solutions to area Regge calculus using a triangulated lattice and find that on a spacelike hypersurface no such discontinuity can arise. On a null hypersurface however, we can have such a situation and the resulting metric can be interpreted as a so-called refractive wave.Comment: 18 pages, 1 figur

    Plasma processing of closed nuclear fuel cycle waste

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    В работе предложен плазменный метод переработки отходов замкнутого ядерного топливного цикла в виде водно-солеорганической композиции. Этот метод имеет несколько преимуществ и позволяет безопасно перерабатывать такой материал. Определен оптимальный состав для утилизации данного отхода в плазме. Равновесные составы показали, что в процессе плазменной обработки образуются N[2], CO[2], H[2]O, а также FeCl[3] и Fe[2]O[3 в конденсированной фазе. Отсутствие сажи является показателем того, что процесс переработки является экологически безопасным.The work proposed the plasma method of processing closed nuclear fuel cycle wastes in the form of a water-salt-organic composition. This method has several advantages and allows recycling such material safely. The optimal composition for recycling in plasma was determined. Equilibrium compositions showed that in the process of plasma processing N[2], CO[2], H[2]O and also FeCl[3] и Fe[2]O[3] in the condensed phase were formed. Lack of soot is an indicator that the recycling process is environmentally safe
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