3,242 research outputs found
The LCO/Palomar 10,000 km/sec Cluster Survey. II. Constraints on Large-Scale Streaming
The LCO/Palomar 10,000 km/sec (LP10K) Tully-Fisher (TF) data set is used to
test for bulk streaming motions on a ~150 Mpc scale. The sample consists of 172
cluster galaxies in the original target range of the survey, 9000-13,000
km/sec, plus an additional 72 galaxies with cz < 30,000 km/sec. A
maximum-likelihood analysis that is insensitive to Malmquist and selection bias
effects is used to constrain the bulk velocity parameters, and realistic
Monte-Carlo simulations are carried out to correct residual biases and
determine statistical errors. When the analysis is restricted to the original
target range, the bias-corrected bulk flow is v_B=720 +/- 280 km/sec toward
l=266, b=19. When all objects out to z=0.1 are included the result is virtually
unchanged, v_B=700 +/- 250 km/sec toward l=272, b=10. The hypothesis that the
Hubble flow has converged to the CMB frame at distances less than ~ 100 Mpc is
ruled out at the 97% confidence level. The data are inconsistent with the flow
vector found by Lauer & Postman. However, the LP10K bulk flow is consistent
with that obtained from the SMAC survey of elliptical galaxies recently
described by Hudson et al. If correct, the LP10K results indicate that the
convergence depth for the Hubble flow is >~ 150 Mpc.Comment: 14 pages, 7 figures, uses emulateapj, submitted to the Astrophysical
Journal. Also available at http://astro.stanford.edu/jeff
Association Between Empathy and Burnout Among Emergency Medicine Physicians
Background:
The association between physician self-reported empathy and burnout has been studied in the past with diverse findings. We aimed to determine the association between empathy and burnout among United States emergency medicine (EM) physicians using a novel combination of tools for validation.
Methods:
This was a prospective single-center observational study. Data were collected from EM physicians. From December 1, 2018 to January 31, 2019, we used the Jefferson scale of empathy (JSE) to assess physician empathy and the Copenhagen burnout inventory (CBI) to assess burnout. We divided EM physicians into different groups (residents in each year of training, junior/senior attendings). Empathy, burnout scores and their association were analyzed and compared among these groups.
Results:
A total of 33 attending physicians and 35 EM residents participated in this study. Median self-reported empathy scores were 113 (interquartile range (IQR): 105 - 117) in post-graduate year (PGY)-1, 112 (90 - 115) in PGY-2, 106 (93 - 118) in PGY-3 EM residents, 112 (105 - 116) in junior and 114 (101 - 125) in senior attending physicians. Overall burnout scores were 43 (33 - 50) in PGY-1, 51 (29 - 56) in PGY-2, 43 (42 - 53) in PGY-3 EM residents, 33 (24 - 47) in junior attending and 25 (22 - 53) in senior attending physicians separately. The Spearman correlation (ρ) was -0.11 and β-weight was -0.23 between empathy and patient-related burnout scores.
Conclusion:
Self-reported empathy declines over the course of EM residency training and improves after graduation. Overall high burnout occurs among EM residents and improves after graduation. Our analysis showed a weak negative correlation between self-reported empathy and patient-related burnout among EM physicians
Anomaly mediated neutrino-photon interactions at finite baryon density
We propose new physical processes based on the axial vector anomaly and
described by the Wess-Zumino-Witten term that couples the photon, Z-boson, and
the omega-meson. The interaction takes the form of a pseudo-Chern-Simons term,
. This term
induces neutrino-photon interactions at finite baryon density via the coupling
of the Z-boson to neutrinos. These interactions may be detectable in various
laboratory and astrophysical arenas. The new interactions may account for the
MiniBooNE excess. They also produce a competitive contribution to neutron star
cooling at temperatures >10^9 K. These processes and related axion--photon
interactions at finite baryon density appear to be relevant in many
astrophysical regimes.Comment: 4 pages, 2 figures; references adde
Remote sensing and geologic studies of the orientale basin region
Both visual and near-infrared spectral observations are combined with multispectral imaging to study the Orientale interior and exterior, the Cruger region, Grimaldi Region, the Schiller-Schickard Region, and the Humorum Region of the Moon. It was concluded that anorthosites occur in the Inner Rook Mountains of Orientale, the inner ring of Grimaldi, and the main ring of Humorum. Imaging spectroscopy shows that the entire eastern Inner Rook Mountains are composed of anorthosites. Orientale ejecta are strikingly like the surface materials in the region where Apollo 16 landed. This similarity indicates similar mineralogy, i.e., noritic anorthosite. Thus, Orientile ejecta is more mafic than the Inner Rook Mountains. This situation is also true for the Nectaris, Humorum, and Gramaldi basins. Isolated areas of the Orientale region show the presence of gabbroic rocks, but, in general, Orientale ejecta are noritic anorthosites, which contain much more low-Ca pyroxene than high-Ca pyroxene. Ancient (pre-Orientale) mare volcanism apparently occurred in several areas of the western limb
The conference effect: National surgery meetings are associated with increased mortality at trauma centers without American College of Surgeons verification
BACKGROUND:
Thousands of physicians attend scientific conferences each year. While recent data indicate that variation in staffing during such meetings impacts survival of non-surgical patients, the association between treatment during conferences and outcomes of a surgical population remain unknown. The purpose of this study was to examine mortality resulting from traumatic injuries and the influence of hospital admission during national surgery meetings.
STUDY DESIGN:
Retrospective analysis of in-hospital mortality using data from the Trauma Quality Improvement Program (2010-2011). Identified patients admitted during four annual meetings and compared their mortality with that of patients admitted during non-conference periods. Analysis included 155 hospitals with 12,256 patients admitted on 42 conference days and 82,399 patients admitted on 270 non-conference days. Multivariate analysis performed separately for hospitals with different levels of trauma center verification by state and American College of Surgeons (ACS) criteria.
RESULTS:
Patient characteristics were similar between meeting and non-meeting dates. At ACS level I and level II trauma centers during conference versus non-conference dates, adjusted mortality was not significantly different. However, adjusted mortality increased significantly for patients admitted to trauma centers that lacked ACS trauma verification during conferences versus non-conference days (OR 1.2, p = 0.008), particularly for patients with penetrating injuries, whose mortality rose from 11.6% to 15.9% (p = 0.006).
CONCLUSIONS:
Trauma mortality increased during surgery conferences compared to non-conference dates for patients admitted to hospitals that lacked ACS trauma level verification. The mortality difference at those hospitals was greatest for patients who presented with penetrating injuries
Remote sensing and geologic studies of the terrain northwest of Humorum basin
A portion of the highlands terrain northwest of the Humorum basin, a large multiringed impact structure on the southwestern portion of the lunar nearside, exhibits anomalous characteristics in several remote sensing data sets. A variety of remote sensing studies of the terrain northwest of Humorum basin were performed in order to determine the composition and origin of the anomalous unit as well as the composition of the highland material exposed by the Humorum impact event. It was found that at least a portion of the mare-bounding ring of Humorum is composed of pure anorthosite. Other details of the study are reported
The Far-Ultraviolet Spectra of TW Hya. II. Models of H2 Fluorescence in a Disk
We measure the temperature of warm gas at planet-forming radii in the disk
around the classical T Tauri star (CTTS) TW Hya by modelling the H2
fluorescence observed in HST/STIS and FUSE spectra. Strong Ly-alpha emission
irradiates a warm disk surface within 2 AU of the central star and pumps
certain excited levels of H2. We simulate a 1D plane-parallel atmosphere to
estimate fluxes for the 140 observed H2 emission lines and to reconstruct the
Ly-alpha emission profile incident upon the warm H2. The excitation of H2 can
be determined from relative line strengths by measuring self-absorption in
lines with low-energy lower levels, or by reconstructing the Ly-alpha profile
incident upon the warm H2 using the total flux from a single upper level and
the opacity in the pumping transition. Based on those diagnostics, we estimate
that the warm disk surface has a column density of log
N(H2)=18.5^{+1.2}_{-0.8}, a temperature T=2500^{+700}_{-500} K, and a filling
factor of H2, as seen by the source of Ly-alpha emission, of 0.25\pm0.08 (all
2-sigma error bars). TW Hya produces approximately 10^{-3} L_\odot in the FUV,
about 85% of which is in the Ly-alpha emission line. From the H I absorption
observed in the Ly-alpha emission, we infer that dust extinction in our line of
sight to TW Hya is negligible.Comment: Accepted by ApJ. 26 pages, 17 figures, 6 table
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data IV: Luminosity Function from the Fall Equatorial Stripe Sampl
This is the fourth paper in a series aimed at finding high-redshift quasars
from five-color imaging data taken along the Celestial Equator by the SDSS.
during its commissioning phase. In this paper, we use the color-selected sample
of 39 luminous high-redshift quasars presented in Paper III to derive the
evolution of the quasar luminosity function over the range of 3.6<z<5.0, and
-27.5<M_1450<-25.5 (Omega=1, H_0=50 km s^-1 Mpc^-1). We use the selection
function derived in Paper III to correct for sample incompleteness. The
luminosity function is estimated using three different methods: (1) the 1/V_a
estimator; (2) a maximum likelihood solution, assuming that the density of
quasars depends exponentially on redshift and as a power law in luminosity and
(3) Lynden-Bell's non-parametric C^- estimator. All three methods give
consistent results. The luminous quasar density decreases by a factor of ~ 6
from z=3.5 to z=5.0, consistent with the decline seen from several previous
optical surveys at z<4.5. The luminosity function follows psi(L) ~ L^{-2.5} for
z~4 at the bright end, significantly flatter than the bright end luminosity
function psi(L) \propto L^{-3.5} found in previous studies for z<3, suggesting
that the shape of the quasar luminosity function evolves with redshift as well,
and that the quasar evolution from z=2 to 5 cannot be described as pure
luminosity evolution. Possible selection biases and the effect of dust
extinction on the redshift evolution of the quasar density are also discussed.Comment: AJ accepted, with minor change
Halo Star Streams in the Solar Neighborhood
We have assembled a sample of halo stars in the solar neighborhood to look
for halo substructure in velocity and angular momentum space. Our sample
includes red giants, RR Lyrae, and red horizontal branch stars within 2.5 kpc
of the Sun with [Fe/H] less than -1.0. It was chosen to include stars with
accurate distances, space velocities, and metallicities as well as
well-quantified errors. We confirm the existence of the streams found by Helmi
and coworkers, which we refer to as the H99 streams. These streams have a
double-peaked velocity distribution in the z direction. We use the results of
modeling of the H99 streams by Helmi and collaborators to test how one might
use v_z velocity information and radial velocity information to detect
kinematic substructure in the halo. We find that detecting the H99 streams with
radial velocities alone would require a large sample. We use the velocity
distribution of the H99 streams to estimate their age. From our model of the
progenitor of the H99 streams, we determine that it was accreted between 6 and
9 Gyr ago. The H99 streams have [alpha/Fe] abundances similar to other halo
stars in the solar neighborhood, suggesting that the gas that formed these
stars were enriched mostly by Type II SNe. We have also discovered in angular
momentum space two other possible substructures, which we refer to as the
retrograde and prograde outliers. The retrograde outliers are likely to be halo
substructure, but the prograde outliers are most likely part of the smooth
halo. The retrograde outliers have significant structure in the v_phi direction
and show a range of [alpha/Fe]. The methods presented in this paper can be used
to exploit the kinematic information present in future large databases like
RAVE, SDSSII/SEGUE, and Gaia.Comment: 46 pages, 13 figures, and 9 tables. Minor changes to text to match
proofed version of the paper. Low resolution figures. High resolution version
at http://www.astro.wisc.edu/~kepley/solar_streams.p
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