23,219 research outputs found

    Tunable conductance of magnetic nanowires with structured domain walls

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    We show that in a magnetic nanowire with double magnetic domain walls, quantum interference results in spin-split quasistationary states localized mainly between the domain walls. Spin-flip-assisted transmission through the domain structure increases strongly when these size-quantized states are tuned on resonance with the Fermi energy, e.g. upon varying the distance between the domain walls which results in resonance-type peaks of the wire conductance. This novel phenomena is shown to be utilizable to manipulate the spin density in the domain vicinity. The domain walls parameters are readily controllable and the predicted effect is hence exploitable in spintronic devices.Comment: 4 pages with 4 figure

    Competing risks, left truncation and late entry effect in A-bomb survivors cohort

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    The cohort under study comprises A-bomb survivors residing in Hiroshima Prefecture since 1968. After this year, thousands of survivors were newly recognized every year. The aim of this study is to determine whether the survival experience of the late entrants to the cohort is significantly different from the registered population in 1968. Parametric models that account for left truncation and competing risks were developed by using sub-hazard functions. A Weibull distribution was used to determine the possible existence of a late entry effect in Hiroshima A-bomb survivors. The competing risks framework shows that there might be a late entry effect in the male and female groups. Our findings are congruent with previous studies analysing similar populations

    Phi meson mass and decay width in nuclear matter

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    The ϕ\phi meson spectrum, which in vacuum is dominated by its coupling to the KˉK\bar{K} K system, is modified in nuclear matter. Following a model based on chiral SU(3) dynamics we calculate the ϕ\phi meson selfenergy in nuclear matter considering the KK and Kˉ\bar{K} in-medium properties. For the latter we use the results of previous calculations which account for SS- and PP-wave kaon-nucleon interactions based on the lowest order meson-baryon chiral effective Lagrangian, and this leads to a dressing of the kaon propagators in the medium. In addition, a set of vertex corrections is evaluated to fulfill gauge invariance, which involves contact couplings of the ϕ\phi meson to SS-wave and PP-wave kaon-baryon vertices. Within this scheme the mass shift and decay width of the ϕ\phi meson in nuclear matter are studied.Comment: 19 pages, 10 figures in EPS format, revtex4; One section modified, some references update