489 research outputs found
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Suicidal Plans and Attempts Among Adolescents in Mongolia: Urban Versus Rural Differences
Background: Although 75% of suicides occur in low- and middle-income countries, few studies have examined suicidal behaviors among young people in these countries. Aims: This study aimed to examine what individual characteristics were associated with suicidal plans and attempts among Mongolian youth and whether suicidal risks and behaviors varied by urban and rural locations. Method: Logistic regression analyses were utilized to investigate suicidal plans and attempts among 5,393 adolescents using the Global Student Health Survey – 2013. Results: Adolescents who lived in urban areas were at higher risk for suicidal plans and behaviors than those who lived in rural areas; however, the patterns of suicidal risks were similar. Specifically, individual characteristics, such as being female, feeling lonely and worried, smoking cigarettes, drinking alcohol, and having fights at school, were associated with suicidal plans and behaviors regardless of the residential places. Limitations: A number of important variables have not been included in the questionnaire such as depression, family and parental support, household income, family constructs etc. Conclusion: Given the comparable patterns of risk between urban and rural adolescents and the relatively high rates of suicidal plans and attempts, similar mental health services and interventions are necessitated for both urban and rural areas
A Catalog of Spectroscopically Confirmed White Dwarfs from the Sloan Digital Sky Survey Data Release 4
We present a catalog of 9316 spectroscopically confirmed white dwarfs from
the Sloan Digital Sky Survey Data Release 4. We have selected the stars through
photometric cuts and spectroscopic modeling, backed up by a set of visual
inspections. Roughly 6000 of the stars are new discoveries, roughly doubling
the number of spectroscopically confirmed white dwarfs. We analyze the stars by
performing temperature and surface gravity fits to grids of pure hydrogen and
helium atmospheres. Among the rare outliers are a set of presumed helium-core
DA white dwarfs with estimated masses below 0.3 Msun, including two candidates
that may be the lowest masses yet found. We also present a list of 928 hot
subdwarfs.Comment: Accepted by the Astrophysical Journal Supplements, 25 pages, 24
figures, LaTeX. The electronic catalog, as well as diagnostic figures and
links to the spectra, is available at http://das.sdss.org/wdcat/dr4
Discovery of New Ultracool White Dwarfs in the Sloan Digital Sky Survey
We report the discovery of five very cool white dwarfs in the Sloan Digital
Sky Survey (SDSS). Four are ultracool, exhibiting strong collision induced
absorption (CIA) from molecular hydrogen and are similar in color to the three
previously known coolest white dwarfs, SDSS J1337+00, LHS 3250 and LHS 1402.
The fifth, an ultracool white dwarf candidate, shows milder CIA flux
suppression and has a color and spectral shape similar to WD 0346+246. All five
new white dwarfs are faint (g > 18.9) and have significant proper motions. One
of the new ultracool white dwarfs, SDSS J0947, appears to be in a binary system
with a slightly warmer (T_{eff} ~ 5000K) white dwarf companion.Comment: 15 pages, 3 figures, submitted to ApJL. Higher resolution versions of
finding charts are available at
http://astro.uchicago.edu/~gates/findingchart
An Improved Photometric Calibration of the Sloan Digital Sky Survey Imaging Data
We present an algorithm to photometrically calibrate wide field optical
imaging surveys, that simultaneously solves for the calibration parameters and
relative stellar fluxes using overlapping observations. The algorithm decouples
the problem of "relative" calibrations, from that of "absolute" calibrations;
the absolute calibration is reduced to determining a few numbers for the entire
survey. We pay special attention to the spatial structure of the calibration
errors, allowing one to isolate particular error modes in downstream analyses.
Applying this to the Sloan Digital Sky Survey imaging data, we achieve ~1%
relative calibration errors across 8500 sq.deg. in griz; the errors are ~2% for
the u band. These errors are dominated by unmodelled atmospheric variations at
Apache Point Observatory. These calibrations, dubbed "ubercalibration", are now
public with SDSS Data Release 6, and will be a part of subsequent SDSS data
releases.Comment: 16 pages, 17 figures, matches version accepted in ApJ. These
calibrations are available at http://www.sdss.org/dr
Automated Detection of Infectious Disease Outbreaks in Hospitals: A Retrospective Cohort Study
Susan Huang and colleagues describe an automated statistical software, WHONET-SaTScan, its application in a hospital, and the potential it has to identify hospital infection clusters that had escaped routine detection
Hdelta-Selected Galaxies in the Sloan Digital Sky Survey I: The Catalog
[Abridged] We present here a new and homogeneous sample of 3340 galaxies
selected from the Sloan Digital Sky Survey (SDSS) based solely on the observed
strength of their Hdelta absorption line. These galaxies are commonly known as
``post-starburst'' or ``E+A'' galaxies, and the study of these galaxies has
been severely hampered by the lack of a large, statistical sample of such
galaxies. In this paper, we rectify this problem by selecting a sample of
galaxies which possess an absorption Hdelta equivalent width of EW(Hdelta_max)
- Delta EW(Hdelta_max) > 4A from 106682 galaxies in the SDSS. We have performed
extensive tests on our catalog including comparing different methodologies of
measuring the Hdelta absorption and studying the effects of stellar absorption,
dust extinction, emission-filling and measurement error. The measured abundance
of our Hdelta-selected (HDS) galaxies is 2.6 +/- 0.1% of all galaxies within a
volume-limited sample of 0.05<z<0.1 and M(r*)<-20.5, which is consistent with
previous studies of such galaxies in the literature. We find that only 25 of
our HDS galaxies in this volume-limited sample (3.5+/-0.7%) show no evidence
for OII and Halpha emission, thus indicating that true E+A (or k+a) galaxies
are extremely rare objects at low redshift, i.e., only 0.09+/-0.02% of all
galaxies in this volume-limited sample are true E+A galaxies. In contrast,
89+/-5% of our HDS galaxies in the volume-limited sample have significant
detections of the OII and Halpha emission lines. We find 27 galaxies in our
volume-limited HDS sample that possess no detectable OII emission, but do
however possess detectable Halpha emission. These galaxies may be dusty
star-forming galaxies. We provide the community with this new catalog of
Hdelta-selected galaxies to aid in the understanding of these galaxies.Comment: Submitted to PASJ. Catalog of galaxies available at
http://astrophysics.phys.cmu.edu/~tomo/ea
A Lyman-alpha-only AGN from the Sloan Digital Sky Survey
The Sloan Digital Sky Survey has discovered a z=2.4917 radio-loud active
galactic nucleus (AGN) with a luminous, variable, low-polarization UV
continuum, H I two-photon emission, and a moderately broad Lyman-alpha line
(FWHM = 1430 km/s) but without obvious metal-line emission. SDSS
J113658.36+024220.1 does have associated metal-line absorption in three
distinct, narrow systems spanning a velocity range of 2710 km/s. Despite
certain spectral similarities, SDSS J1136+0242 is not a Lyman-break galaxy.
Instead, the Ly-alpha and two-photon emission can be attributed to an extended,
low-metallicity narrow-line region. The unpolarized continuum argues that we
see SDSS J1136+0242 very close to the axis of any ionization cone present. We
can conceive of two plausible explanations for why we see a strong UV continuum
but no broad-line emission in this `face-on radio galaxy' model for SDSS
J1136+0242: the continuum could be relativistically beamed synchrotron emission
which swamps the broad-line emission; or, more likely, SDSS J1136+0242 could be
similar to PG 1407+265, a quasar in which for some unknown reason the
high-ionization emission lines are very broad, very weak, and highly
blueshifted.Comment: AJ, in press, 10 pages emulateapj forma
A New Giant Stellar Structure in the Outer Halo of M31
The Sloan Digital Sky Survey has revealed an overdensity of luminous red
giant stars ~ 3 degrees (40 projected kpc) to the northeast of M31, which we
have called Andromeda NE. The line-of-sight distance to Andromeda NE is within
approximately 50 kpc of M31; Andromeda NE is not a physically unrelated
projection. Andromeda NE has a g-band absolute magnitude of ~ -11.6 and central
surface brightness of ~ 29 mag/sq.arcsec, making it nearly two orders of
magnitude more diffuse than any known Local Group dwarf galaxy at that
luminosity. Based on its distance and morphology, Andromeda NE is likely
undergoing tidal disruption. Andromeda NE's red giant branch color is unlike
that of M31's present-day outer disk or the stellar stream reported by Ibata et
al. (2001), arguing against a direct link between Andromeda NE and these
structures. However, Andromeda NE has a red giant branch color similar to that
of the G1 clump; it is possible that these structures are both material torn
off of M31's disk in the distant past, or that these are both part of one
ancient stellar stream.Comment: 11 pages, 3 figures; ApJ Letters accepted versio
False positive HIV diagnoses in resource limited settings: operational lessons learned for HIV programmes
Access to HIV diagnosis is life-saving; however the use of rapid diagnostic tests in combination is vulnerable to wrongly diagnosing HIV infection when both screening tests give a false positive result. Misclassification of HIV patients can also occur due to poor quality control, administrative errors and lack of supervision and training of staff. Médecins Sans Frontières discovered in 2004 that HIV negative individuals were enrolled in some HIV programmes. This paper describes the result of an audit of three sites to review testing practices, implement improved testing algorithms and offer re-testing to clients enrolled in the HIV clinic
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Using Automated Health Plan Data to Assess Infection Risk from Coronary Artery Bypass Surgery
We determined if infection indicators were sufficiently consistent across health plans to allow comparison of hospitals’ risks of infection after coronary artery bypass surgery. Three managed care organizations accounted for 90% of managed care in eastern Massachusetts, from October 1996 through March 1999. We searched automated inpatient and outpatient claims and outpatient pharmacy dispensing files for indicator codes suggestive of postoperative surgical site infection. We reviewed full text medical records of patients with indicator codes to confirm infection status. We compared the hospital-specific proportions of cases with an indicator code, adjusting for health plan, age, sex, and chronic disease score. A total of 536 (27%) of 1,953 patients had infection indicators. Infection was confirmed in 79 (53%) of 149 reviewed records with adequate documentation. The proportion of patients with an indicator of infection varied significantly (p<0.001) between hospitals (19% to 36%) and health plans (22% to 33%). The difference between hospitals persisted after adjustment for health plan and patients’ age and sex. Similar relationships were observed when postoperative antibiotic information was ignored. Automated claims and pharmacy data from different health plans can be used together to allow inexpensive, routine monitoring of indicators of postoperative infection, with the goal of identifying institutions that can be further evaluated to determine if risks for infection can be reduced
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