3,773 research outputs found
Spin-memory loss at Co/Ru interfaces
We have determined the spin-memory-loss parameter, , 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 . From the CPP-MR, we
obtain that is in good agreement with
obtained from spin-triplet transmission. For
spin-singlet transmission, we have 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
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 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
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
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
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,
Representative Farm Analysis of the S. 1731 Farm Bill Proposal
Agribusiness, Agricultural and Food Policy,
Strong gametocytocidal effect of methylene blue-based combination therapy against falciparum malaria
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
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
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
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