Observation of a subgap density of states in superconductor-normal metal bilayers in the Cooper limit

We present transport and tunneling measurements of Pb-Ag bilayers with thicknesses, $d_{Pb}$ and $d_{Ag}$, that are much less than the superconducting coherence length. The transition temperature, $T_c$, and energy gap, $\Delta$, in the tunneling Density of States (DOS) decrease exponentially with $d_{Ag}$ at fixed $d_{Pb}$. Simultaneously, a DOS that increases linearly from the Fermi energy grows and fills nearly 40% of the gap as $T_c$ is 1/10 of $T_c$ of bulk Pb. This behavior suggests that a growing fraction of quasiparticles decouple from the superconductor as $T_c$ goes to 0. The linear dependence is consistent with the quasiparticles becoming trapped on integrable trajectories in the metal layer.Comment: 5 pages and 4 figures. This version is just the same as the old version except that we try to cut the unnecessary white space in the figures and make the whole paper look more compac

A dearth of OH/IR stars in the Small Magellanic Cloud

We present the results of targeted observations and a survey of 1612-, 1665-, and 1667-MHz circumstellar OH maser emission from asymptotic giant branch (AGB) stars and red supergiants (RSGs) in the Small Magellanic Cloud (SMC), using the Parkes and Australia Telescope Compact Array radio telescopes. No clear OH maser emission has been detected in any of our observations targeting luminous, long-period, large-amplitude variable stars, which have been confirmed spectroscopically and photometrically to be mid- to late-M spectral type. These observations have probed 3 - 4 times deeper than any OH maser survey in the SMC. Using a bootstrapping method with LMC and Galactic OH/IR star samples and our SMC observation upper limits, we have calculated the likelihood of not detecting maser emission in any of the two sources considered to be the top maser candidates to be less than 0.05%, assuming a similar pumping mechanism as the LMC and Galactic OH/IR sources. We have performed a population comparison of the Magellanic Clouds and used Spitzer IRAC and MIPS photometry to confirm that we have observed all high luminosity SMC sources that are expected to exhibit maser emission. We suspect that, compared to the OH/IR stars in the Galaxy and LMC, the reduction in metallicity may curtail the dusty wind phase at the end of the evolution of the most massive cool stars. We also suspect that the conditions in the circumstellar envelope change beyond a simple scaling of abundances and wind speed with metallicity

Correlated transport of FQHE quasiparticles in a double-antidot system

We have calculated the linear conductance associated with tunneling of individual quasiparticles of primary quantum Hall liquids with filling factors $\nu =1/(2m+1)$ through a system of two antidots in series. On-site Coulomb interaction simulates the Fermi exclusion and makes the quasiparticle dynamics similar to that of tunneling electrons. The liquid edges serve as the quasiparticle reservoirs, and also create the dissipation mechanism for tunneling between the antidots. In the regime of strong dissipation, the conductance should exhibit resonant peaks of unusual form and a width proportional to the quasiparticle interaction energy $U$. In the weakly-damped regime, the shape of the resonant conductance peaks reflects coherent tunnel coupling of the antidots. The Luttinger-liquid singularity in the rates of quasiparticle tunneling to/from the liquid edges manifests itself as an additional weak resonant structure in the conductance curves.Comment: 9 pages including 5 figure

Some Radiative Corrections to Neutrino Scattering: I Neutral Currents

With the advent of high precision neutrino scattering experiments comes the need for improved radiative corrections. We present a phenomenological analysis of some contributions to the production of photons in neutrino neutral current scattering that are relevant to experiments subsuming the 1% level.Comment: 17 Pages, 7 .pdf Figure

Substellar Companions to Main Sequence Stars: No Brown Dwarf Desert at Wide Separations

We use three field L and T dwarfs which were discovered to be wide companions to known stars by the Two Micron All-Sky Survey (2MASS) to derive a preliminary brown dwarf companion frequency. Observed L and T dwarfs indicate that brown dwarfs are not unusually rare as wide (Delta >1000 A.U.) systems to F-M0 main-sequence stars (M>0.5M_sun, M_V<9.5), even though they are rare at close separation (Delta <3 A.U.), the ``brown dwarf desert.'' Stellar companions in these separation ranges are equally frequent, but brown dwarfs are >~ 10 times as frequent for wide than close separations. A brown dwarf wide-companion frequency as low as the 0.5% seen in the brown dwarf desert is ruled out by currently-available observations.Comment: ApJL, in pres

Structure and Stability of the Twofold Surface of Icosahedral Al-Pd-Mn by Low-Energy Electron Diffraction and X-Ray Photoemission Spectroscopy

We have used low-energy electron diffraction and x-ray photoemission spectroscopy to investigate the structure of the twofold surface of icosahedral Al-Pd-Mn. The regrowth of the surface by annealing after sputtering took place in two distinct stages. The first stage was the appearance of a fine-grained surface phase with icosahedral, or near-icosahedral, symmetry. For higher annealing temperatures (above 800 K) a bulk terminated face-centered icosahedral surface was observed

Post-Mortem Cardiac Device Retrieval for Re-Use in Third World Nations: Views of the General Public & Patient Population

http://deepblue.lib.umich.edu/bitstream/2027.42/109410/1/postmortemgeneral.pdf61Description of postmortemgeneral.pdf : Presentatio

Bioactivation of Trimethoprim to Protein-Reactive Metabolites in Human Liver Microsomes

The formation of drug-protein adducts via metabolic activation and covalent binding may stimulate an immune response or may result in direct cell toxicity. Protein covalent binding is a potentially pivotal step in the development of idiosyncratic adverse drug reactions (IADRs). Trimethoprim (TMP)-sulfamethoxazole (SMX) is a combination antibiotic that commonly causes IADRs. Recent data suggest that the contribution of the TMP component of TMP-SMX to IADRs may be underappreciated. We previously demonstrated that TMP is bioactivated to chemically reactive intermediates that can be trapped in vitro by N-acetyl cysteine (NAC), and we have detected TMP-NAC adducts (i.e., mercapturic acids) in the urine of patients taking TMP-SMX. However, the occurrence and extent of TMP covalent binding to proteins was unknown. To determine the ability of TMP to form protein adducts, we incubated [14C]TMP with human liver microsomes in the presence and absence of NADPH. We observed protein covalent binding that was NADPH dependent and increased with incubation time and concentration of both protein and TMP. The estimated covalent binding was 0.8 nmol Eq TMP/mg protein, which is comparable to the level of covalent binding for several other drugs that have been associated with covalent binding–induced toxicity and/or IADRs. NAC and selective inhibitors of CYP2B6 and CYP3A4 significantly reduced TMP covalent binding. These results demonstrate for the first time that TMP bioactivation can lead directly to protein adduct formation, suggesting that TMP has been overlooked as a potential contributor of TMP-SMX IADRs