3,741 research outputs found

    Spin-memory loss at Co/Ru interfaces

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    We have determined the spin-memory-loss parameter, δCo/Ru\delta_{Co/Ru}, by measuring the transmission of spin-triplet and spin-singlet Cooper pairs across Co/Ru interfaces in Josephson junctions and by Current-Perpendicular-to-Plane Giant Magnetoresistance (CPP-GMR) techniques. The probability of spin-memory loss at the Co/Ru interface is (1−exp(−δCo/Ru))(1-exp(-\delta_{Co/Ru})). From the CPP-MR, we obtain δCo/Ru=0.34−0.02+0.04\delta_{Co/Ru} = 0.34^{+0.04}_{-0.02} that is in good agreement with δCo/Ru=0.35±0.08\delta_{Co/Ru} = 0.35 \pm 0.08 obtained from spin-triplet transmission. For spin-singlet transmission, we have δCo/Ru=0.64±0.05\delta_{Co/Ru} = 0.64 \pm 0.05 that is different from that obtained from CPP-GMR and spin-triplet transmission. The source of this difference is not understood.Comment: 9 pages, 9 figure

    Gravitational wave background from vacuum and thermal fluctuations during axion-like inflation

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    We revisit the framework of axion-like inflation in view of the possibility that the coupling of the inflaton to a non-Abelian topological charge density could lead to the generation of a rapidly thermalizing heat bath. Both dispersive (mass) and absorptive (friction) effects are included. For phenomenologically viable parameters, the system remains in a weak regime of warm inflation (thermal friction ≪\ll Hubble rate). For tensor perturbations we derive an interpolating formula that incorporates both vacuum and thermal production. The latter yields a model-independent frequency shape ∼f03\sim f_0^3 in the LISA window, whose coefficient allows to measure the maximal shear viscosity of the thermal epoch. It is a challenge, however, to find models where the coefficient is large enough to be observable.Comment: 32 pages. v2: clarifications adde

    GRB afterglow light curves in the pre-Swift era - a statistical study

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    We present the results of a systematic analysis of the world sample of optical/near-infrared afterglow light curves observed in the pre-Swift era by the end of 2004. After selecting the best observed 16 afterglows with well-sampled light curves that can be described by a Beuermann equation, we explore the parameter space of the light curve parameters and physical quantities related to them. In addition, we search for correlations between these parameters and the corresponding gamma-ray data, and we use our data set to look for a fine structure in the light curves.Comment: accepted for publication in ApJ; Version 2: minor changes, one figure adde

    Analysis of H.R. 2646 on Land Tenure Arrangements on U.S. Representative and Texas FARM Assistance Farms

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    This report analyzes whether H.R. 2646 may provide economic incentives for landlords to end current land tenure arrangements with tenants and take over management (and government payments) associated with their land. This work is a followup to Briefing Paper 01-9, Representative Farm Analysis of the H.R. 2646 Farm Bill Proposal that analyzes the impacts of H.R. 2646 on the representative crop farms maintained by the Agricultural and Food Policy Center (AFPC).Agribusiness, Agricultural and Food Policy, Land Economics/Use,

    Strong gametocytocidal effect of methylene blue-based combination therapy against falciparum malaria

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    With the availability of new preventive and curative interventions, global malaria control has been strengthened significantly in recent years. Drugs effective in reducing malaria gametocytaemia might contribute to local elimination and possible long-term eradication. We here report on the effects of methylene blue (MB)-based malaria combination therapy on gametocytaemia during a randomised-controlled trial in Burkina Faso. An open-label randomised controlled phase II study in 180 children aged 6-10 years with uncomplicated falciparum malaria was conducted in Nouna, north-western Burkina Faso. Children were randomised to MB-artesunate (AS), MB-amodiaquine (AQ), and AS-AQ (local standard of care). Overall follow-up was for 28 days, follow-up for gametocytaemia was for 14 days. The treatment groups were similar in baseline characteristics and there was only one loss to follow-up. Compared to AS-AQ, both MB-containing regimens were associated with significantly reduced gametocyte carrier rates during follow-up days 3, 7, and 14. This effect was seen both in patients with and without P. falciparum gametocytaemia at baseline. MB reveals pronounced gametocytocidal activity which appears to act against both existing and developing P. falciparum gametocytes. MB-based combination therapy thus has the potential to reduce transmission of P. falciparum malaria in endemic regions, which has important implications for future elimination and eradication strategies

    Analysis of the Effects of Proposed House and Senate Farm Bills on Rice Returns

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    This report reflects analysis of projected gross returns under the proposed farm programs – H.R. 2646 the House Bill that passed the House floor on October 5th, the Senate Bill that passed the Senate Agriculture Committee on November 15th and the Cochran/Roberts Bill that was defeated previously in committee.Agricultural and Food Policy,

    The Perfect Atom: Bound States of Supersymmetric Quantum Electrodynamics

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    We study hydrogen-like atoms in N=1 supersymmetric quantum electrodynamics with an electronic and a muonic family. These atoms are bound states of an anti-muon and an electron or their superpartners. The exchange of a photino converts different bound states into each other. We determine the energy eigenstates and calculate the spectrum to fourth order in the fine structure constant. A difference between these perfect atoms and non-supersymmetric ones is the absence of hyperfine structure. We organize the eigenstates into super multiplets of the underlying symmetry algebra.Comment: 30 pages, 2 figures. v2: mistake associated with gauge choice fixed, references added. v3: comment about super-positronium added, published versio
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