Semiclassical Gravity in the Far Field Limit of Stars, Black Holes, and Wormholes

Semiclassical gravity is investigated in a large class of asymptotically flat, static, spherically symmetric spacetimes including those containing static stars, black holes, and wormholes. Specifically the stress-energy tensors of massless free spin 0 and spin 1/2 fields are computed to leading order in the asymptotic regions of these spacetimes. This is done for spin 0 fields in Schwarzschild spacetime using a WKB approximation. It is done numerically for the spin 1/2 field in Schwarzschild, extreme Reissner-Nordstrom, and various wormhole spacetimes. And it is done by finding analytic solutions to the leading order mode equations in a large class of asymptotically flat static spherically symmetric spacetimes. Agreement is shown between these various computational methods. It is found that for all of the spacetimes considered, the energy density and pressure in the asymptotic region are proportional to 1/r^5 to leading order. Furthermore, for the spin 1/2 field and the conformally coupled scalar field, the stress-energy tensor depends only on the leading order geometry in the far field limit. This is also true for the minimally coupled scalar field for spacetimes containing either a static star or a black hole, but not for spacetimes containing a wormhole.Comment: 43 pages, 2 figures. Reference added, minor changes, PRD versio

Balloon Atrial Septostomy as Initial Therapy in Pediatric Pulmonary Hypertension

Balloon atrial septostomy is a palliative procedure currently used to bridge medically refractory pulmonary hypertension patients to lung transplantation. In the current report, we present balloon atrial septostomy as an initial therapy for high-risk pediatric pulmonary hypertension patients at our institution. Nineteen patients with median age of 4.3 years (range 0.1-14.3 years) underwent balloon atrial septostomy during initial admission for pulmonary hypertension. There were no procedural complications or deaths within 24 h of balloon atrial septostomy. Patients were followed for a median of 2.6 years (interquartile range 1.0-4.8 years). Three (16%) patients died, 3 (16%) underwent lung transplantation, and 1 (5%) underwent reverse Potts shunt. Transplant-free survival at 30 days, 1 year, and 3 years was 84%, 76%, and 67% respectively. This single-center experience suggests early-BAS in addition to pharmacotherapy is safe and warrants consideration in high-risk pediatric pulmonary hypertension patients

Stress-Energy Tensor for the Massless Spin 1/2 Field in Static Black Hole Spacetimes

The stress-energy tensor for the massless spin 1/2 field is numerically computed outside and on the event horizons of both charged and uncharged static non-rotating black holes, corresponding to the Schwarzschild, Reissner-Nordstrom and extreme Reissner-Nordstr\"om solutions of Einstein's equations. The field is assumed to be in a thermal state at the black hole temperature. Comparison is made between the numerical results and previous analytic approximations for the stress-energy tensor in these spacetimes. For the Schwarzschild (charge zero) solution, it is shown that the stress-energy differs even in sign from the analytic approximation. For the Reissner-Nordstrom and extreme Reissner-Nordstrom solutions, divergences predicted by the analytic approximations are shown not to exist.Comment: 5 pages, 4 figures, additional discussio

Surface potential at a ferroelectric grain due to asymmetric screening of depolarization fields

Nonlinear screening of electric depolarization fields, generated by a stripe domain structure in a ferroelectric grain of a polycrystalline material, is studied within a semiconductor model of ferroelectrics. It is shown that the maximum strength of local depolarization fields is rather determined by the electronic band gap than by the spontaneous polarization magnitude. Furthermore, field screening due to electronic band bending and due to presence of intrinsic defects leads to asymmetric space charge regions near the grain boundary, which produce an effective dipole layer at the surface of the grain. This results in the formation of a potential difference between the grain surface and its interior of the order of 1 V, which can be of either sign depending on defect transition levels and concentrations. Exemplary acceptor doping of BaTiO3 is shown to allow tuning of the said surface potential in the region between 0.1 and 1.3 V.Comment: 14 pages, 11 figures, submitted to J. Appl. Phy

The Interrelations Between Spiritual Well-Being, Pain Interference and Depressive Symptoms in Patients with Multiple Sclerosis

Depressive symptoms are common in individuals with multiple sclerosis (MS), and are frequently exacerbated by pain; however, spiritual well-being may allow persons with MS to more effectively cope with pain-related deficits in physical and role functioning. We explored the associations between spiritual well-being, pain interference and depressive symptoms, assessing each as a potential mediator, in eighty-one patients being treated for MS, who completed self-report measures: Functional Assessment of Chronic Illness Therapy-Spiritual Well-Being Scale, Pain Effects Scale, and Center for Epidemiologic Studies Depression Scale Revised. At the bivariate level, spiritual well-being and its subscale of meaning and peace were negatively associated with depression and pain interference. In mediation models, depression was not related to pain interference via spiritual well-being, or to spiritual well-being via pain interference. Pain interference was related to depression via spiritual well-being and meaning/peace, and to spiritual well-being and meaning/peace via depressive symptoms. Finally, spiritual well-being and meaning/peace were related to depression via pain interference, and to pain interference via depressive symptoms. For patients with MS, a multi-faceted approach to treatment that includes pain reduction and promotion of spiritual well-being may be beneficial, although amelioration of depression remains a critical task

Detection of Planetary and Stellar Companions to Neighboring Stars via a Combination of Radial Velocity and Direct Imaging Techniques

13 pages, 6 figures, 4 tables, accepted for publication in the Astronomical Journal (submitted 25 Feb 2019; accepted 28 April 2019). Machine readable tables and Posteriors from the RadVel fits are available here: http://stephenkane.net/rvfits.tarThe sensitivities of radial velocity (RV) surveys for exoplanet detection are extending to increasingly longer orbital periods, where companions with periods of several years are now being regularly discovered. Companions with orbital periods that exceed the duration of the survey manifest in the data as an incomplete orbit or linear trend, a feature that can either present as the sole detectable companion to the host star, or as an additional signal overlain on the signatures of previously discovered companion(s). A diagnostic that can confirm or constrain scenarios in which the trend is caused by an unseen stellar rather than planetary companion is the use of high-contrast imaging observations. Here, we present RV data from the Anglo-Australian Planet Search (AAPS) for 20 stars that show evidence of orbiting companions. Of these, six companions have resolved orbits, with three that lie in the planetary regime. Two of these (HD 92987b and HD 221420b) are new discoveries. Follow-up observations using the Differential Speckle Survey Instrument (DSSI) on the Gemini South telescope revealed that 5 of the 20 monitored companions are likely stellar in nature. We use the sensitivity of the AAPS and DSSI data to place constraints on the mass of the companions for the remaining systems. Our analysis shows that a planetary-mass companion provides the most likely self-consistent explanation of the data for many of the remaining systems.Peer reviewedFinal Accepted Versio

Spatially resolved acoustic spectroscopy for texture imaging in powder bed fusion nickel superalloys

© 2019 Author(s). There is a clear industrial pull to fabricate high value components using premium high temperature aerospace materials by additive manufacturing. Inconveniently, the same material properties which allow them to perform well in service render them difficult to process via powder bed fusion. Current build systems are charac-terised by high defect rates and erratic microstructure, leading to components with inferior mechanical properties. The work presents microstructural texture imaging of powder-bed fusion components by a non-contact laser ultrasonic method, Spatially Resolved Acoustic Spectroscopy (SRAS). In short, this work demonstrates the ability to SRAS to detect and characterise meso-scale crystalline texture features. Probing samples manufactured by powder bed fusion, in the common nickel based aerospace superalloy Inconel 718, it has been shown the the primary crystalline orientation of can be inferred from the measured velocity, with good agreement with Electron Backscatter Diffraction. The studied sample was found to have a microstructure formation that bore a heavy resemblance to the chosen scanning pattern, with clear influence from the geometry through varying scan vector length and island-boundary scan strategy. This work forms part of a progression towards deployment of a SRAS system as an in-situ inspection solution for PBF

Fruit and Vegetable Intake and Food Store Access: A Cross-Sectional Survey Study in Ypsilanti, Michigan

Given declines in supermarkets in Washtenaw County, Michigan (MI), we aim to characterize the relationship between food store access and fruit and vegetable intake in Ypsilanti, MI. A cross-sectional, convenience sample survey was conducted in March 2011 at the Ypsilanti District Library (n=83). Self-reported food store access, perceived food environment, and fruit and vegetable intake were assessed. Linear and logistic regressions were performed between store access, fruit and vegetable intake, and meeting dietary recommendations. Perception was evaluated for effect modification. Adjusting for demographics, each food store within one mile of participants’ homes increased odds of meeting recommended intake by 105% (OR 2.05, 95% CI: 1.02, 4.10). However, contrary to previous literature, each additional minute to the food store was associated with consumption of 0.37 (95% confidence interval [CI]: 0.10, 0.64) more servings of fruits and vegetables per day. Perception was not a statistically significant effect modifier, but data suggest differences for those with divergent perceptions. Food environment is associated with fruit and vegetable intake in Ypsilanti, MI. Inconsistent findings suggest that programs should focus on enhancing the food environment within the context of perceptions and preferences

Air mass factor formulation for spectroscopic measurements from satellites: Application to formaldehyde retrievals from the Global Ozone Monitoring Experiment

Abstract. We present a new formulation for the air mass factor (AMF) to convert slant column measurements of optically thin atmospheric species from space into total vertical columns. Because of atmospheric scattering, the AMF depends on the vertical distribution of the species. We formulate the AMF as the integral of the relative vertical distribution (shape factor) of the species over the depth of the atmosphere, weighted by altitudedependent coefficients (scattering weights) computed independently from a radiative transfer model. The scattering weights are readily tabulated, and one can then obtain the AMF for any observation scene by using shape factors from a three dimensional (3-D) atmospheric chemistry model for the period of observation. This approach subsequently allows objective evaluation of the 3-D model with the observed vertical columns, since the shape factor and the vertical column in the model represent two independent pieces of information. We demonstrate the AMF method by using slant column measurements of formaldehyde at 346 nm from the Global Ozone Monitoring Experiment satellite instrument over North America during July 1996. Shape factors are computed with the Global Earth Observing System CHEMistry (GEOS-CHEM) global 3-D model and are checked for consistency with the few available aircraft measurements. Scattering weights increase by an order of magnitude from the surface to the upper troposphere. The AMFs are typically 20-40 % less over continents than over the oceans and are approximately half the values calculated in the absence of scattering. Model-induced errors in the AMF are estimated to be • 10%. The GEOS-CHEM model captures 50 % and 60 % of the variances in the observed slant and vertical columns, respectively. Comparison of the simulated and observed vertical columns allows assessment of model bias. 1