Near-Infrared Counterparts to Chandra X-ray Sources toward the Galactic Center. I. Statistics and a Catalog of Candidates

We present a catalog of 5184 candidate infrared counterparts to X-ray sources detected towards the Galactic center. The X-ray sample contains 9017 point sources detected in this region by the Chandra X-ray Observatory, including data from a recent deep survey of the central 2 x 0.8 deg of the Galactic plane. A total of 6760 of these sources have hard X-ray colors, and the majority of them lie near the Galactic center, while most of the remaining 2257 soft X-ray sources lie in the foreground. We cross-correlated the X-ray source positions with the 2MASS and SIRIUS near-infrared catalogs, which collectively contain stars with a 10-sigma limiting flux of K_s<=15.6 mag. In order to distinguish absorbed infrared sources near the Galactic center from those in the foreground, we defined red and blue sources as those which have H-K_s>=0.9 and <=0.9 mag, respectively. We find that 5.8(1.5)% of the hard X-ray sources have real infrared counterparts, of which 228(99) are red and 166(27) are blue. The red counterparts are probably comprised of WR/O stars, HMXBs, and symbiotics near the Galactic center. We also find that 39.4(1.0)% of the soft X-ray sources have blue infrared counterparts; most of these are probably coronally active dwarfs in the foreground. There is a noteworthy collection of ~20 red counterparts to hard X-ray sources near the Sagittarius-B H II region, which are probably massive binaries that have formed within the last several Myr. For each of the infrared matches to X-ray sources in our catalog we derived the probability that the association is real, based on the results of the cross-correlation analysis. The catalog will serve spectroscopic surveys to identify infrared counterparts to X-ray sources near the Galactic center.Comment: Submitted to ApJ January 16, 2009; accepted July 21, 2009; 30 pages, 6 figure

Massive Stellar X-ray Sources in the Galactic Center

We present results of a spectroscopic survey of bright near-infrared counterparts to X-ray point sources from a deep Chandra survey of the Galactic nuclear bulge. K-band spectroscopy has revealed 13 new Wolf-Rayet and O-supergiant counterparts to Chandra sources in the Galactic center (GC). Although they are systematically softer in X-rays than the general GC source population of accretion powered cataclysmic variables (CVs), their X-ray colors indicate a hard component consistent with emission from plasmas with E > 2 keV. Such hard X-ray emission is not ubiquitous among single Wolf-Rayet and O stars, but is common among Wolf-Rayet+OB binaries with colliding supersonic winds. Although we regard colliding-wind binary hypothesis as the most likely scenario, it remains possible that several of these objects are wind-accreting neutron stars or black holes in supergiant high-mass X-ray binaries, or extraordinary single stars emitting hard X-rays

Enhanced Nonperturbative Effects in Z Decays to Hadrons

We use soft collinear effective field theory (SCET) to study nonperturbative strong interaction effects in Z decays to hadronic final states that are enhanced in corners of phase space. These occur, for example, in the jet energy distribution for two jet events near E_J=M_Z/2, the thrust distribution near unity and the jet invariant mass distribution near zero. The extent to which such nonperturbative effects for different observables are related is discussed.Comment: 17 pages. Paper reorganized, and more discussion and results include

Healthy universities: an example of a whole-system health-promoting setting

The health-promoting settings approach is well established in health promotion, with organisational settings being understood as complex systems able to support human wellbeing and flourishing. Despite the reach and evident importance of higher education as a sector, ‘healthy universities’ has not received high-level international leadership comparable to many other settings programmes. This study explores how the concept of a healthy university is operationalised in two case study universities. Data collection methods included documentary analysis, observation field notes and semi-structured interviews with staff and students. Staff and students understood the characteristics of a healthy university to pertain to management processes relating to communication and to a respectful organisational ethos. Enhancers of health and wellbeing were feeling valued, being listened to, having skilled and supportive line managers and having a positive physical environment. Inhibitors of health and wellbeing were having a sense of powerlessness and a lack of care and concern. The concept of the healthy university has been slow to be adopted in contrast to initiatives such as healthy schools. In addition to challenges relating to lack of theorisation, paucity of evidence and difficulties in capturing the added value of whole-system working, this study suggests that this may be due to both their complex organisational structure and the diverse goals of higher education, which do not automatically privilege health and wellbeing. It also points to the need for a wholeuniversity approach that pays attention to the complex interactions and interconnections between component parts and highlights how the organisation can function effectively as a social system

Oral fumaric acid esters for psoriasis: abridged Cochrane systematic review including GRADE assessments

Fumaric acid esters (FAE) are licensed for the treatment of moderate to severe psoriasis in Germany but are also used off-label in many other countries. We conducted this systematic review to synthesize the highest quality evidence for the benefits and risks of FAE for psoriasis. Our primary outcomes were change in PASI score and drop-out rates due to adverse effects. Randomised controlled trials (RCTs) of FAE or dimethyl fumarate were included, with no restriction on age or psoriasis subtype. We searched The Cochrane Skin Group Specialised Register, CENTRAL in the Cochrane Library, MEDLINE, EMBASE, LILACS, five trials registers and handsearched six conference proceedings. Six RCTs with 544 participants were included, four of which were published only as abstracts or brief reports, limiting study reporting. Five RCTs compared FAE with placebo and all demonstrated benefit in favour of FAE but meta-analysis was only possible for PASI 50 after 12-16 weeks, which was achieved by 64% of participants on FAE compared to 14% on placebo (risk ratio (RR) 4.55; 95% CI 2.80 to 7.40; 2 studies; 247 participants; low quality evidence). There was no difference in drop-out rates due to adverse effects (RR 5.36, 95% CI 0.28 to 102.12; 1 study; 27 participants; very low-quality evidence and wide confidence interval). More participants experienced nuisance adverse effects with FAE (76%) compared to placebo (16%) (RR 4.72, 95% CI 2.45 to 9.08; 1 study; 99 participants; moderate-quality evidence), mainly abdominal pain, diarrhoea and flushing. One head-to-head study of very low quality evidence comparing FAE with methotrexate reported comparable efficacy and drop-out rates, although FAE caused more flushing. The evidence in this review was limited and must be interpreted with caution; better designed and reported studies are needed

Massive stellar X-ray sources in the galactic center

We present results of a spectroscopic survey of bright near-infrared counterparts to X-ray point sources from a deep Chandra survey of the Galactic nuclear bulge. K-band spectroscopy has revealed 13 new Wolf-Rayet and O-supergiant counterparts to Chandra soucres. Although they are systematically softer in X-rays than the general Galactic center source population of accretion powered CVs, their X-ray colors indicate a hard component consistent with emission from thermal plasma with kT>2 keV. Such hard X-ray emission is not ubiquitous among single Wolf-Rayet and O stars but is common among Wolf-Rayet+OB binaries with colliding supersonic winds. Although we regard colliding-wind binary hypothesis as the most likely scenario, it remains possible that several of these objects are wind-accreting neutron stars or black holes in supergiant high-mass X-ray binaries, or extraordinary single stars emitting hard X-rays