513 research outputs found
The Extrasolar Planet epsilon Eridani b - Orbit and Mass
Hubble Space Telescope observations of the nearby (3.22 pc), K2 V star
epsilon Eridani have been combined with ground-based astrometric and radial
velocity data to determine the mass of its known companion. We model the
astrometric and radial velocity measurements simultaneously to obtain the
parallax, proper motion, perturbation period, perturbation inclination, and
perturbation size. Because of the long period of the companion, \eps b, we
extend our astrometric coverage to a total of 14.94 years (including the three
year span of the \HST data) by including lower-precision ground-based
astrometry from the Allegheny Multichannel Astrometric Photometer. Radial
velocities now span 1980.8 -- 2006.3. We obtain a perturbation period, P = 6.85
+/- 0.03 yr, semi-major axis, alpha =1.88 +/- 0.20 mas, and inclination i =
30.1 +/- 3.8 degrees. This inclination is consistent with a previously measured
dust disk inclination, suggesting coplanarity. Assuming a primary mass M_* =
0.83 M_{\sun}, we obtain a companion mass M = 1.55 +/- 0.24 M_{Jup}. Given the
relatively young age of epsilon Eri (~800 Myr), this accurate exoplanet mass
and orbit can usefully inform future direct imaging attempts. We predict the
next periastron at 2007.3 with a total separation, rho = 0.3 arcsec at position
angle, p.a. = -27 degrees. Orbit orientation and geometry dictate that epsilon
Eri b will appear brightest in reflected light very nearly at periastron.
Radial velocities spanning over 25 years indicate an acceleration consistent
with a Jupiter-mass object with a period in excess of 50 years, possibly
responsible for one feature of the dust morphology, the inner cavity
Possible Observational Criteria for Distinguishing Brown Dwarfs from Planets
The difference in formation process between binary stars and planetary
systems is reflected in their composition as well as their orbital
architecture, particularly orbital eccentricity as a function of orbital
period. It is suggested here that this difference can be used as an
observational criterion to distinguish between brown dwarfs and planets.
Application of the orbital criterion suggests that with three possible
exceptions, all of the recently-discovered substellar companions discovered to
date may be brown dwarfs and not planets. These criterion may be used as a
guide for interpretation of the nature of sub-stellar mass companions to stars
in the future.Comment: LaTeX, 11 pages including 2 figures, accepted for publication in the
Astrophysical Journal Letter
Social cognition and African American men: The roles of perceived discrimination and experimenter race on task performance
The Social Cognition Psychometric Evaluation (SCOPE) study consists of a battery of eight tasks selected to measure social-cognitive deficits in individuals with schizophrenia. The battery is currently in a multisite validation process. While the SCOPE study collects basic demographic data, more nuanced race-related factors might artificially inflate cross-cultural differences in social cognition. As an initial step, we investigated whether race, independent of mental illness status, affects performance on the SCOPE battery. Thus, we examined the effects of perceived discrimination and experimenter race on the performance of 51 non-clinical African American men on the SCOPE battery. Results revealed that these factors impacted social cognitive task performance. Specifically, participants performed better on a skills-based task factor in the presence of Black experimenters, and frequency of perceived racism predicted increased perception of hostility in negative interpersonal situations with accidental causes. Thus, race-related factors are important to identify and explore in the measurement of social cognition in African Americans
Innovative Interprofessional Collaboration: Addressing the Need for Education for Health Center Workers around Patients\u27 Sexual Orientation and Gender Identity (SOGI)
BACKGROUND: University of Rhode Island (URI) students in a graduate-level course, Interdisciplinary Teamwork in Health and Human Services, collaborated with a local health provider, Wood River Health Services (WRHS), to create training materials for its staff on the topic of sexual orientation/gender identity (SOGI). WRHS is a federally-funded, comprehensive community health center located in a rural area of Rhode Island. It provides medical, dental, and mental health services. WRHS had been advised to enhance its attention to issues related to SOGI.
OBJECTIVES The aims for this project were: 1. Assess needs and priorities of WRHS staff around knowledge and attitudes about SOGI and health care; 2. Create a training tool for staf fto enable them to facilitate patient comfort in disclosing SOGI-related information that would assist them in addressing individual needs of patients; 3. Provide students an opportunity to effectively learn and practice interprofessionally.
METHODS The students--representing three different health fields (Occupational Therapy, Human Development and Family Studies, and Pharmacy)--researched SOGI issues related to their fields. Students met with WRHS staff to develop a clear understanding of the center’s barriers to adequately provide care to LGBTQ+ patients. They conducted a survey to assess staff attitudes and knowledge about SOGI terminology, health disparities, and the importance of a welcoming environment that informed the development of a training presentation. Staf can complete it at their convenience, and it can be used as part of onboarding new staff. Retrospective pre/post-tests were administered to students and WRHS staff.
CONCLUSION Informational presentations are a useful tool for agencies looking to build capacity and comfort among staff around SOGI. Additionally, providing students with opportunities to learn with, from, and about each other is a critical component of health professions education.https://jdc.jefferson.edu/sexandgenderhealth/1020/thumbnail.jp
Astrometric Methods and Instrumentation to Identify and Characterize Extrasolar Planets: A Review
I present a review of astrometric techniques and instrumentation utilized to
search for, detect, and characterize extra-solar planets. First, I briefly
summarize the properties of the present-day sample of extrasolar planets, in
connection with predictions from theoretical models of planet formation and
evolution. Next, the generic approach to planet detection with astrometry is
described, with significant discussion of a variety of technical, statistical,
and astrophysical issues to be faced by future ground-based as well as
space-borne efforts in order to achieve the required degree of measurement
precision. After a brief summary of past and present efforts to detect planets
via milli-arcsecond astrometry, I then discuss the planet-finding capabilities
of future astrometric observatories aiming at micro-arcsecond precision.
Lastly, I outline a number experiments that can be conducted by means of
high-precision astrometry during the next decade, to illustrate its potential
for important contributions to planetary science, in comparison with other
indirect and direct methods for the detection and characterization of planetary
systems.Comment: 61 pages, 8 figures, PASP, accepted (October 2005 issue
Characteristics of US public schools with reported cases of novel influenza A (H1N1)
Objective
The 2009 pandemic of influenza A (H1N1) has disproportionately affected children and young adults, resulting in attention by public health officials and the news media on schools as important settings for disease transmission and spread. We aimed to characterize US schools affected by novel influenza A (H1N1) relative to other schools in the same communities.
Methods
A database of US school-related cases was obtained by electronic news media monitoring for early reports of novel H1N1 influenza between April 23 and June 8, 2009. We performed a matched case–control study of 32 public primary and secondary schools that had one or more confirmed cases of H1N1 influenza and 6815 control schools located in the same 23 counties as case schools.
Results
Compared with controls from the same county, schools with reports of confirmed cases of H1N1 influenza were less likely to have a high proportion of economically disadvantaged students (adjusted odds ratio (aOR) 0.385; 95% confidence interval (CI) 0.166–0.894) and less likely to have older students (aOR 0.792; 95% CI 0.670–0.938).
Conclusions
We conclude that public schools with younger, more affluent students may be considered sentinels of the epidemic and may have played a role in its initial spread.National Institute of Allergy and Infectious Diseases (U.S.) (R21AI073591-01)National Institutes of Health (U.S.)Canadian Institutes of Health Research (PAN-83152)Canadian Institutes of Health Research (CAT-86857)Google (Firm) (Research Grant
The Torino Observatory Parallax Program: White Dwarf Candidates
We present parallax determinations for six white dwarf candidates in the
Torino Observatory Parallax Program. The absolute parallaxes are found with
precisions at the 2-3 milliarcsecond level. For WD 1126+185 we find a distance
incompatible with being a white dwarf, implying an incorrect classification.
For WD 2216+484 we find our distance is consistent with a simple DA white dwarf
rather than a composite system as previously proposed in the literature. In
general it is found that the published photometric distance is an overestimate
of the distance found here.Comment: AA paper, 7 pages, 4 figure
1951: Abilene Christian College Bible Lectures - Full Text
Delivered in the Auditorium of Abilene Christian College
Abilene, Texas
February 18-22, 1951
Price, $3.00
FIRM FOUNDATION PUBLISHING HOUSE
Austin, Texa
Three-dimensional interferometric, spectrometric, and planetary views of Procyon
We used a new realistic 3D radiative-hydrodynamical model atmosphere of
Procyon generated with the Stagger Code and synthetic spectra computed with the
radiative transfer code Optim3D to re-analyze interferometric and spectroscopic
data from the optical to the infrared of Procyon. We compute intensity maps in
two optical filters centered at 500 and 800 nm (MARK III) and one infrared
filter centered at 2200 nm (VINCI). We constructed stellar disk images
accounting for the center-to-limb variations and used them to derive visibility
amplitudes and closure phases. We provide 3D limb-darkening coefficients in the
optical as well as in the infrared. We show that visibility curves and closure
phases show clear deviations from circular symmetry from the 3rd lobe on. These
deviations are detectable with current interferometers using closure phases. We
derive new angular diameters at different wavelengths with two independent
methods based on 3D simulations. We find a diameter_Vinci = 5.390 \pm 0.03 mas
that this is confirmed by an independent asteroseismic estimation. The
resulting Teff is 6591 K, which is consistent with the infrared flux method
determinations. We find also a value of the surface gravity log g = 4.01 \pm
0.03 that is larger by 0.05 dex from literature values. Spectrophotometric
comparisons with observations provide very good agreement with the spectral
energy distribution and photometric colors, allowing us to conclude that the
thermal gradient of the simulation matches fairly well Procyon. Finally, we
show that the granulation pattern of a planet hosting Procyon-like star has a
non-negligible impact on the detection of hot Jupiters in the infrared using
interferometry closure phases. It is then crucial to have a comprehensive
knowledge of the host star to directly detect and characterize hot Jupiters. In
this respect, RHD simulations are very important to reach this aim.Comment: Accepted for publication on Astronomy and Astrophysics, 14 pages, 12
figure
The Discovery of a Planetary Companion to 16 Cygni B
High precision radial velocity observations of the solar-type star 16 Cygni B
taken at McDonald Observatory and at Lick Observatory, have each independently
discovered periodic radial-velocity variations indicating the presence of a
Jovian-mass companion to this star. The orbital fit to the combined data gives
a period of 800.8 days, a velocity amplitude of 43.9 m/s, and an eccentricity
of 0.63. This is the largest eccentricity of any planetary system discovered so
far. Assuming that 16 Cygni B has a mass of 1.0 Msun, this implies a mass for
the companion of 1.5 sin i Jupiter masses. While the mass of this object is
well within the range expected for planets, the large orbital eccentricity
cannot be explained simply by the standard model of growth of planets in a
protostellar disk. It is possible that this object was formed in the normal
manner with a low eccentricity orbit, and has undergone post-formational
orbital evolution, either through the same process which formed the ``massive
eccentric'' planets around 70 Virginis and HD114762, or by gravitational
interactions with the companion star 16 Cygni A. It is also possible that the
object is an extremely low mass brown dwarf, formed through fragmentation of
the collapsing protostar. We explore a possible connection between stellar
photospheric Li depletion, pre-main sequence stellar rotation, the presence of
a massive proto-planetary disk, and the formation of a planetary companion.Comment: 18 pages, 3 PostScript figures, Latex, uses aaspp4 macros, submitted
to Astrophysical Journa
- …