Exactly Solvable Model of Superconducting Magnetic Alloys

A model describing the Anderson impurity in the Bardeen-Cooper-Schriffer superconductor is proven to exhibit hidden integrability and is diagonalized exactly by the Bethe ansatz.Comment: 10 pages, RevTEX, Phys. Lett. A. (in press

An X-ray and Radio Study of the Varying Expansion Velocities in Tycho's Supernova Remnant

We present newly obtained X-ray and radio observations of Tycho's supernova remnant using {\it Chandra} and the Karl G. Jansky Very Large Array in 2015 and 2013/14, respectively. When combined with earlier epoch observations by these instruments, we now have time baselines for expansion measurements of the remnant of 12-15 year in the X-rays and 30 year in the radio. The remnant's large angular size allows for proper motion measurements at many locations around the periphery of the blast wave. We find, consistent with earlier measurements, a clear gradient in the expansion velocity of the remnant, despite its round shape. The proper motions on the western and southwestern sides of the remnant are about a factor of two higher than those in the east and northeast. We showed in an earlier work that this is related to an offset of the explosion site from the geometric center of the remnant due to a density gradient in the ISM, and using our refined measurements reported here, we find that this offset is $\sim 23"$ towards the northeast. An explosion center offset in such a circular remnant has implications for searches for progenitor companions in other remnants.Comment: Accepted for publication in ApJ Letter

Oxylipins in triglyceride-rich lipoproteins of dyslipidemic subjects promote endothelial inflammation following a high fat meal.

Elevated triglyceride-rich lipoproteins (TGRL) in circulation is a risk factor for atherosclerosis. TGRL from subjects consuming a high saturated fat test meal elicited a variable inflammatory response in TNFα-stimulated endothelial cells (EC) that correlated strongly with the polyunsaturated fatty acid (PUFA) content. This study investigates how the relative abundance of oxygenated metabolites of PUFA, oxylipins, is altered in TGRL postprandially, and how these changes promote endothelial inflammation. Human aortic EC were stimulated with TNFα and treated with TGRL, isolated from subjects' plasma at fasting and 3.5 hrs postprandial to a test meal high in saturated fat. Endothelial VCAM-1 surface expression stimulated by TNFα provided a readout for atherogenic inflammation. Concentrations of esterified and non-esterified fatty acids and oxylipins in TGRL were quantified by mass spectrometry. Dyslipidemic subjects produced TGRL that increased endothelial VCAM-1 expression by ≥35%, and exhibited impaired fasting lipogenesis activity and a shift in soluble epoxide hydrolase and lipoxygenase activity. Pro-atherogenic TGRL were enriched in eicosapentaenoic acid metabolites and depleted in esterified C18-PUFA-derived diols. Abundance of these metabolites was strongly predictive of VCAM-1 expression. We conclude the altered metabolism in dyslipidemic subjects produces TGRL with a unique oxylipin signature that promotes a pro-atherogenic endothelial phenotype

RCW 86: A Type Ia Supernova in a Wind-Blown Bubble

We report results from a multi-wavelength analysis of the Galactic SNR RCW 86, the proposed remnant of the supernova of 185 A.D. We report new infrared observations from {\it Spitzer} and {\it WISE}, where the entire shell is detected at 24 and 22 $\mu$m. We fit the infrared flux ratios with models of collisionally heated ambient dust, finding post-shock gas densities in the non-radiative shocks of 2.4 and 2.0 cm$^{-3}$ in the SW and NW portions of the remnant, respectively. The Balmer-dominated shocks around the periphery of the shell, large amount of iron in the X-ray emitting ejecta, and lack of a compact remnant support a Type Ia origin for this remnant. From hydrodynamic simulations, the observed characteristics of RCW 86 are successfully reproduced by an off-center explosion in a low-density cavity carved by the progenitor system. This would make RCW 86 the first known case of a Type Ia supernova in a wind-blown bubble. The fast shocks ($> 3000$ km s$^{-1}$) observed in the NE are propagating in the low-density bubble, where the shock is just beginning to encounter the shell, while the slower shocks elsewhere have already encountered the bubble wall. The diffuse nature of the synchrotron emission in the SW and NW is due to electrons that were accelerated early in the lifetime of the remnant, when the shock was still in the bubble. Electrons in a bubble could produce gamma-rays by inverse-Compton scattering. The wind-blown bubble scenario requires a single-degenerate progenitor, which should leave behind a companion star.Comment: Accepted for publication in ApJ. 50 pages, 9 figure

Effect of Manufacturing Tolerances on the Number of Load Carrying Fasteners in a Joint Subjected to a Shear Load: A Statistical Approach

Within the elastic range, the number of load-carrying fasteners in an interchangeable manufactured joint subjected to a shear load is dependent upon the following characteristics: 1. Material properties of the constituent parts in the shear joint. 2. Geometry of the shear joint. 3. Manufacturing tolerances of the constituent parts in the shear joint. 4. Number of fasteners in the shear joint. 5. Preload on the fasteners in the joint. 6. Static coefficient of friction between the joint surfaces. Neglecting the effects of preload and friction, the number of load-carrying fasteners is determined for a theoretical bolted joint design as a function of the remaining four (above) parameters. The analysis is accomplished by assuming all deformation in the constituent parts of the joint remain within the elastic range and then examining the stress-strain relationship existent in the shear joint. Based on simplifying assumptions, the total deflection is calculated and then, statistics are applied to the manufacturing tolerances of the constituent parts of the shear joint. The results suggest that plastic deformation occurs in all classically designed shear joints and the predicted number of load carrying fasteners using this analysis approach is in error. Suggestions for future research are presented

The Three-Dimensional Expansion of the Ejecta from Tycho's Supernova Remnant

We present the first three-dimensional measurements of the velocity of various ejecta knots in Tycho's supernova remnant, known to result from a Type Ia explosion. Chandra X-ray observations over a 12-year baseline from 2003 to 2015 allow us to measure the proper motion of nearly 60 "tufts" of Si-rich ejecta, giving us the velocity in the plane of the sky. For the line of sight velocity, we use two different methods: a non-equilibrium ionization model fit to the strong Si and S lines in the 1.2-2.8 keV regime, and a fit consisting of a series of Gaussian lines. These methods give consistent results, allowing us to determine the red or blue shift of each of the knots. Assuming a distance of 3.5 kpc, we find total velocities that range from 2400 to 6600 km s$^{-1}$, with a mean of 4430 km s$^{-1}$. We find several regions where the ejecta knots have overtaken the forward shock. These regions have proper motions in excess of 6000 km s$^{-1}$. Some Type Ia supernova explosion models predict a velocity asymmetry in the ejecta. We find no such velocity asymmetries in Tycho, and discuss our findings in light of various explosion models, favoring those delayed detonation models with relatively vigorous and symmetrical deflagrations. Finally, we compare measurements with models of the remnant's evolution that include both smooth and clumpy ejecta profiles, finding that both ejecta profiles can be accommodated by the observations.Comment: Accepted for publication in ApJ. Some figures slightly degraded to reduce file siz

Observations of X-rays and Thermal Dust Emission from the Supernova Remnant Kes 75

We present Spitzer Space Telescope and Chandra X-ray Observatory observations of the composite Galactic supernova remnant Kes 75 (G29.7-0.3). We use the detected flux at 24 microns and hot gas parameters from fitting spectra from new, deep X-ray observations to constrain models of dust emission, obtaining a dust-to-gas mass ratio M_dust/M_gas ~0.001. We find that a two-component thermal model, nominally representing shocked swept-up interstellar or circumstellar material and reverse-shocked ejecta, adequately fits the X-ray spectrum, albeit with somewhat high implied densities for both components. We surmise that this model implies a Wolf-Rayet progenitor for the remnant. We also present infrared flux upper limits for the central pulsar wind nebula.Comment: 7 pages, 2 tables, 4 figures, uses emulateapj. Accepted for publication in Ap