55 research outputs found

    Order parameter of MgB_2: a fully gapped superconductor

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    We have measured the low-temperature specific heat C(T) for polycrystalline MgB_2 prepared by high pressure synthesis. C(T) below 10 K vanishes exponentially, which unambiguously indicates a fully opened superconducting energy gap. However, this gap is found to be too small to account for Tc of MgB_2. Together with the small specific heat jump DeltaC/gamma_nTc=1.13, scenarios like anisotropic s-wave or multi-component order parameter are called for. The magnetic field dependence of gamma(H) is neither linear for a fully gapped s-wave superconductor nor H^1/2 for nodal order parameter. It seems that this intriguing behavior of gamma(H) is associated with the intrinsic electronic properties other than flux pinning.Comment: 7 pages, 5 figures; revised text and figures; references updated, Phys. Rev. Lett., in pres

    Happiness, Ideology and Crime in Argentine Cities

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    This paper uses self-reported data on victimization, subjective well being and ideology for a panel of individuals living in six Argentine cities. While no relationship is found between happiness and victimization experiences, a correlation is documented, however, between victimization experience and changes in ideological positions. Specifically, individuals who are the victims of crime are subsequently more likely than non-victims to state that inequality is high in Argentina and that the appropriate measure to reduce crime is to become less punitive (demanding lower penalties for the same crime)

    Medulloblastoma in childhood: revisiting intrathecal therapy in infants and children

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