Direct constraints on the dark matter self-interaction cross-section from the merging galaxy cluster 1E0657-56

We compare new maps of the hot gas, dark matter, and galaxies for 1E0657-56, a cluster with a rare, high-velocity merger occurring nearly in the plane of the sky. The X-ray observations reveal a bullet-like gas subcluster just exiting the collision site. A prominent bow shock gives an estimate of the subcluster velocity, 4500 km/s, which lies mostly in the plane of the sky. The optical image shows that the gas lags behind the subcluster galaxies. The weak-lensing mass map reveals a dark matter clump lying ahead of the collisional gas bullet, but coincident with the effectively collisionless galaxies. From these observations, one can directly estimate the cross-section of the dark matter self-interaction. That the dark matter is not fluid-like is seen directly in the X-ray -- lensing mass overlay; more quantitative limits can be derived from three simple independent arguments. The most sensitive constraint, sigma/m<1 cm^2/g, comes from the consistency of the subcluster mass-to-light ratio with the main cluster (and universal) value, which rules out a significant mass loss due to dark matter particle collisions. This limit excludes most of the 0.5-5 cm^2/g interval proposed to explain the flat mass profiles in galaxies. Our result is only an order-of-magnitude estimate which involves a number of simplifying, but always conservative, assumptions; stronger constraints may be derived using hydrodynamic simulations of this cluster.Comment: Text clarified; some numbers changed slightly for consistency with final version of the accompanying lensing paper. 6 pages, uses emulateapj. ApJ in pres

A Room For "Adam And Steve" at Mrs. Murphy's Bed and Breakfast: Avoiding the Sin of Inhospitality in Places of Public Accommodation

This article aims to encourage a vital and evolutionary step forward in understanding how multifaceted legal processes shape, and should shape, thinking about gay and lesbian couples within religious communities and the body politic. The article begins by providing context that illustrates the place-based and diffuse nature of an ongoing culture war between civil rights and religious freedom, further exposing the painful irony inherent in using misinterpretations of the Sodom and Gomorrah parable to reinforce inhospitality. The article describes a state-by-state patchwork of nondiscrimination laws governing places of public accommodation and explores the Jim Crow origins of the "Mrs. Murphy" exception that has been incorporated into a handful of state nondiscrimination laws. The article then examines how existing legal frameworks address claims of sexual orientation discrimination alongside defenses based upon religious freedom. Finally, this article seeks to accelerate an emerging trend toward including sexual orientation as a protected category in our nation’s nondiscrimination laws, by highlighting an opportunity to counter religious misinterpretations currently reflected in the prevailing cultural narrative

A Review of Clinical Informatics Competencies in Nursing to Inform Best Practices in Education and Nurse Faculty Development

AIM The aim of this literature review was to determine the state of the science related to clinical informatics competencies of registered nurses and to determine best practices in educational strategies for both nursing students and faculty. BACKGROUND Continued emphasis on the provision of evidence-based patient care has implications for requisite informatics-focused competencies to be threaded throughout all levels of nursing educational programs. METHOD Whittemore and Knalf’s five-step integrative review process guided this research. An extensive search yielded 69 publications for critical appraisal. RESULTS Results suggest nursing educational programs do not adhere to standardized criteria for teaching nursing informatics competencies. Another identified literature gap was the scarcity of research related to informatics training requirements for nurse educators. CONCLUSION Findings support the need for continued research to provide clear direction about the expected clinical informatics competencies of graduate nurses and what training faculty need to facilitate student learning

Luminosity function of faint Galactic sources in the Chandra bulge field

We study the statistical properties of faint X-ray sources detected in the Chandra Bulge Field. The unprecedented sensitivity of the Chandra observations allows us to probe the population of faint Galactic X-ray sources down to luminosities L(2-10 keV)~1e30 erg/sec at the Galactic Center distance. We show that the luminosity function of these CBF sources agrees well with the luminosity function of sources in the Solar vicinity (Sazonov et al. 2006). The cumulative luminosity density of sources detected in the CBF in the luminosity range 1e30-1e32 erg/sec per unit stellar mass is L(2-10 keV)/M*=(1.7+/-0.3)e27 erg/sec/Msun. Taking into account sources in the luminosity range 1e32-1e34 erg/sec from Sazonov et al. (2006), the cumulative luminosity density in the broad luminosity range 1e30-1e34 erg/sec becomes L(2-10 keV)/M*=(2.4+/-0.4)e27 erg/sec/Msun. The majority of sources with the faintest luminosities should be active binary stars with hot coronae based on the available luminosity function of X-ray sources in the Solar environment.Comment: 5 pages, 4 figures, Accepted for publication in MNRA

Chandra X-ray Observations of the Hydra A Cluster: An Interaction Between the Radio Source and the X-Ray-Emitting Gas

We present Chandra X-ray Observations of the Hydra A cluster of galaxies, and we report the discovery of structure in the central 80 kpc of the cluster's X-ray-emitting gas. The most remarkable structures are depressions in the X-ray surface brightness, $\sim 25-35$ kpc diameter, that are coincident with Hydra A's radio lobes. The depressions are nearly devoid of X-ray-emitting gas, and there is no evidence for shock-heated gas surrounding the radio lobes. We suggest the gas within the surface brightness depressions was displaced as the radio lobes expanded subsonically, leaving cavities in the hot atmosphere. The gas temperature declines from 4 keV at 70 kpc to 3 keV in the inner 20 kpc of the brightest cluster galaxy (BCG), and the cooling time of the gas is $\sim 600$ Myr in the inner 10 kpc. These properties are consistent with the presence of a \sim 34 \msunyr cooling flow within a 70 kpc radius. Bright X-ray emission is present in the BCG surrounding a recently-accreted disk of nebular emission and young stars. The star formation rate is commensurate with the cooling rate of the hot gas within the volume of the disk, although the sink for the material cooling at larger radii remains elusive.Comment: 4 pages, 3 figures; submitted to ApJ Letter