91 research outputs found
The Timing of Nine Globular Cluster Pulsars
We have used the Robert C. Byrd Green Bank Telescope to time nine previously
known pulsars without published timing solutions in the globular clusters M62,
NGC 6544, and NGC 6624. We have full timing solutions that measure the spin,
astrometric, and (where applicable) binary parameters for six of these pulsars.
The remaining three pulsars (reported here for the first time) were not
detected enough to establish solutions. We also report our timing solutions for
five pulsars with previously published solutions, and find good agreement with
past authors, except for PSR J1701-3006B in M62. Gas in this system is probably
responsible for the discrepancy in orbital parameters, and we have been able to
measure a change in the orbital period over the course of our observations.
Among the pulsars with new solutions we find several binary pulsars with very
low mass companions (members of the so-called "black widow" class) and we are
able to place constraints on the mass-to-light ratio in two clusters. We
confirm that one of the pulsars in NGC 6624 is indeed a member of the rare
class of non-recycled pulsars found in globular clusters. We also have measured
the orbital precession and Shapiro delay for a relativistic binary in NGC 6544.
If we assume that the orbital precession can be described entirely by general
relativity, which is likely, we are able to measure the total system mass
(2.57190(73) M_sun) and companion mass (1.2064(20) M_sun), from which we derive
the orbital inclination [sin(i) = 0.9956(14)] and the pulsar mass (1.3655(21)
M_sun), the most precise such measurement ever obtained for a millisecond
pulsar. The companion is the most massive known around a fully recycled pulsar.Comment: Published in ApJ; 33 pages, 5 figures, 7 table
Do incoming residents vary in measures of emotional status even prior to residency training?
Objectives: To determine whether Empathy, Emotional Intelligence, and Burnout scores differ by specialty in incoming residents.
Methods: This is a single-site, prospective, cross-sectional study. Three validated survey instruments, the Jefferson Scale of Physician Empathy, Maslach Burnout Inventory, and Emotional and Social Competency Inventory, were written into a survey platform as a single 125-question Qualtrics survey. Over three academic years, 2015-2017, 229 incoming residents across all specialties were emailed the survey link during orientation. Residents were grouped by incoming specialty with anonymity assured. A total of 229 responses were included, with 121 (52.8%) identifying as female. Statistical analysis was performed using the Analysis of Variance or Kruskal-Wallis test, Chi-Square or Fisher\u27s Exact test, and Independent Samples t-test or Mann Whitney U test. A Bonferroni correction was applied for pairwise comparisons.
Results: Family Medicine had a higher median Jefferson Scale of Physician Empathy score (127) compared to Emergency Medicine (115), (U=767.7, p=0.0330). Maslach Burnout Inventory depersonalization and personal accomplishment subcategory scores showed a significant difference between specialties when omnibus tests were performed, but pairwise comparisons with emergency medicine residents showed no differences. Differences were found in the Maslach Burnout Inventory categories of Depersonalization (χ
Conclusions: Differences in measures of well-being exist across specialties, even prior to the start of residency training. The implication for educators of residency training is that some incoming residents, regardless of specialty, already exhibit troublesome features of burnout, and resources to effectively deal with these residents should be developed and utilized
Burnout, Empathy and Emotional Intelligence Amongst Incoming Residents of Various Specialties: Are the Differences Born or Made?
Measures of Resident Burnout, Empathy and Emotional Intelligence as a Function of Years in Post-Graduate Training
Do Female Residents Actually Demonstrate Better Levels of Empathy, Emotional Intelligence and Burnout than their Male Counterparts?
Has the COVID-19 Pandemic Adversely Affected Measure of Burnout and Empathy in Emergency Medicine Residents?
The relativistic pulsar-white dwarf binary PSR J1738+0333 II. The most stringent test of scalar-tensor gravity
(abridged) We report the results of a 10-year timing campaign on PSR
J1738+0333, a 5.85-ms pulsar in a low-eccentricity 8.5-hour orbit with a
low-mass white dwarf companion (...) The measurements of proper motion and
parallax allow for a precise subtraction of the kinematic contribution to the
observed orbital decay; this results in a significant measurement of the
intrinsic orbital decay: (-25.9 +/- 3.2) \times 10^{-15} s/s. This is
consistent with the orbital decay from the emission of gravitational waves
predicted by general relativity, (-27.7 +1.5/-1.9) \times 10^{-15} s/s (...).
This agreement introduces a tight upper limit on dipolar gravitational wave
emission, a prediction of most alternative theories of gravity for asymmetric
binary systems such as this. We use this limit to derive the most stringent
constraints ever on a wide class of gravity theories, where gravity involves a
scalar field contribution. When considering general scalar-tensor theories of
gravity, our new bounds are more stringent than the best current solar-system
limits over most of the parameter space, and constrain the matter-scalar
coupling constant {\alpha}_0^2 to be below the 10^{-5} level. For the special
case of the Jordan-Fierz-Brans-Dicke, we obtain the one-sigma bound
{\alpha}_0^2 < 2 \times 10^{-5}, which is within a factor two of the Cassini
limit. We also use our limit on dipolar gravitational wave emission to
constrain a wide class of theories of gravity which are based on a
generalization of Bekenstein's Tensor-Vector-Scalar gravity (TeVeS), a
relativistic formulation of Modified Newtonian Dynamics (MOND).Comment: Accepted for publication in MNRAS. 18 pages in emulate MNRAS format,
9 figures and 1 tabl
Is Intracranial Atherosclerosis an Independent Risk Factor for Cerebral Atrophy? A Retrospective Evaluation
<p>Abstract</p> <p>Background</p> <p>Our purpose was to study the association between the intracranial atherosclerosis as measured by cavernous carotid artery calcification (ICAC) observed on head CT and atrophic changes of supra-tentorial brain demonstrated by MRI.</p> <p>Methods</p> <p>Institutional review board approval was obtained for this retrospective study incorporating 65 consecutive patients presenting acutely who had both head CT and MRI. Arterial calcifications of the intracranial cavernous carotids (ICAC) were assigned a number (1 to 4) in the bone window images from CT scans. These 4 groups were then combined into high (grades 3 and 4) and low calcium (grades 1 and 2) subgroups. Brain MRI was independently evaluated to identify cortical and central atrophy. Demographics and cardiovascular risk factors were evaluated in subjects with high and low ICAC. Relationship between CT demonstrated ICAC and brain atrophy patterns were evaluated both without and with adjustment for cerebral ischemic scores and cardiovascular risk factors.</p> <p>Results</p> <p>Forty-six of the 65 (71%) patients had high ICAC on head CT. Subjects with high ICAC were older, and had higher prevalence of hypertension, diabetes, coronary artery disease (CAD), atrial fibrillation and history of previous stroke (CVA) compared to those with low ICAC. Age demonstrated strong correlation with both supratentorial atrophy patterns. There was no correlation between ICAC and cortical atrophy. There was correlation however between central atrophy and ICAC. This persisted even after adjustment for age.</p> <p>Conclusion</p> <p>Age is the most important determinant of atrophic cerebral changes. However, high ICAC demonstrated age independent association with central atrophy.</p
Diving into the vertical dimension of elasmobranch movement ecology
Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements
- …