233 research outputs found
Utilization and Impact of Peer-Support Programs on Police Officersâ Mental Health
Police officer suicides rates hit an all-time high in the province of Ontario, Canada, in 2018. Sadly, this statistic is somewhat unsurprising, as research has shown that police officers suffer from higher rates of mental health disorder diagnoses compared the general public. One key reason for the elevated levels of suicide and other mental health issues among police officers is the stigma associated with seeking help. In an attempt to address these serious issues, Ontarioâs police services have begun to create internal peer-support programs as a way of supporting their members. The present research explores the experiences of police officers serving as peer-support team members, particularly with regards to the impacts of peer support. In addition, this research also examines the importance of discussing shared experiences regarding a lack of provincial standards with credible peers. The Policy Feedback Theory posits that, when a policy becomes established and resources are devoted to programs, it helps structure current activity and provides advantages for some groups. This study utilizes a phenomenological, qualitative approach, with data collection consisting of face-to-face interviews with nine police officers serving on the York Regional Policeâs peer-support team. The qualitative findings revealed that peer support is more than just a âconversationâ; rather, it is instrumental in enhancing mental health literacy among police officers, and it significantly contributes to stigma reduction. The findings also revealed that internal policy demonstrates an organizational commitment to mental health and peer-support programs, and that a provincial standard is necessary to ensure best practices and risk management in the creation and maintenance of peer-support programs
An Ultraviolet-Selected Galaxy Redshift Survey - II: The Physical Nature of Star Formation in an Enlarged Sample
We present further spectroscopic observations for a sample of galaxies
selected in the vacuum ultraviolet (UV) at 2000 \AA from the FOCA balloon-borne
imaging camera of Milliard et al. (1992). This work represents an extension of
the initial study of Treyer et al. (1998). Our enlarged catalogue contains 433
sources; 273 of these are galaxies, nearly all with redshifts z=0-0.4. Nebular
emission line measurements are available for 216 galaxies, allowing us to
address issues of reddening and metallicity. The UV and Halpha luminosity
functions strengthen our earlier assertions that the local volume-averaged star
formation rate is higher than indicated from earlier surveys. Moreover,
internally within our sample, we do not find a steep rise in the UV luminosity
density with redshift over 0<z<0.4. Our data is more consistent with a modest
evolutionary trend as suggested by recent redshift survey results. We find no
evidence for a significant number of AGN in our sample. We find the UV flux
indicates a consistently higher mean star formation rate than that implied by
the Halpha luminosity for typical constant or declining star formation
histories. Following Glazebrook et al. (1999), we interpret this discrepancy in
terms of a starburst model for our UV-luminous sources. Whilst we can explain
most of our observations in this way, there remains a small population with
extreme UV-optical colours which cannot be understood.Comment: 27 pages, 19 figures, accepted for publication in MNRA
Dependence of Dust Obscuration on Star Formation Rates in Galaxies
Many investigations of star formation rates (SFRs) in galaxies have explored
details of dust obscuration, with a number of recent analyses suggesting that
obscuration appears to increase in systems with high rates of star formation.
To date these analyses have been primarily based on nearby (z < 0.03) or UV
selected samples. Using 1.4 GHz imaging and optical spectroscopic data from the
Phoenix Deep Survey, the SFR-dependent obscuration is explored. The use of a
radio selected sample shows that previous studies exploring SFR-dependent
obscurations have been biased against obscured galaxies. The observed relation
between obscuration and SFR is found to be unsuitable to be used as an
obscuration measure for individual galaxies. Nevertheless, it is shown to be
successful as a first order correction for large samples of galaxies where no
other measure of obscuration is available, out to intermediate redshifts (z ~
0.8).Comment: 9 pages (including 5 encapsulated postscript figures), aastex, uses
emulateapj5.sty. Accepted for publication in Ap
UV and FIR selected samples of galaxies in the local Universe. Dust extinction and star formation rates
We have built two samples of galaxies selected at 0.2micron (hereafter UV)
and 60micron (hereafter FIR) covering a sky area of 35.36 deg^2. The UV
selected sample contains 25 galaxies brighter than AB_0.2=17mag. All of them,
but one elliptical, are detected at 60micron with a flux density larger or
equal to 0.2Jy. The UV counts are significantly lower than the euclidean
extrapolation towards brighter fluxes of previous determinations. The FIR
selected sample contains 42 galaxies brighter than f_60=0.6Jy. Excepting four
galaxies, all of them have a UV counterpart at the limiting magnitude
AB_0.2=20.3mag. The mean extinction derived from the analysis of the FIR to UV
flux ratio is ~1mag for the UV selected sample and ~2mag for the FIR selected
one. For each sample we compare several indicators of the recent star formation
rate (SFR) based on the FIR and/or the UV emissions and we find linear
relationships with slopes close to unity, meaning that no trend with the SFR
exists when converting between each other. Various absolute calibrations for
both samples are discussed in this paper. A positive correlation between
extinction and SFR is found when both samples are considered together although
with a considerable scatter. A similar result is obtained when using the SFR
normalized to the optical surface of the galaxies.Comment: 34 pages, 17 figures. Accepted for publication in A&
The ESO UVES Advanced Data Products Quasar Sample - VI. Sub-Damped Lyman- Metallicity Measurements and the Circum-Galactic Medium
The Circum-Galactic Medium (CGM) can be probed through the analysis of
absorbing systems in the line-of-sight to bright background quasars. We present
measurements of the metallicity of a new sample of 15 sub-damped Lyman-
absorbers (sub-DLAs, defined as absorbers with 19.0 < log N(H I) < 20.3) with
redshift 0.584 < < 3.104 from the ESO Ultra-Violet Echelle
Spectrograph (UVES) Advanced Data Products Quasar Sample (EUADP). We combine
these results with other measurements from the literature to produce a
compilation of metallicity measurements for 92 sub-DLAs as well as a sample of
362 DLAs. We apply a multi-element analysis to quantify the amount of dust in
these two classes of systems. We find that either the element depletion
patterns in these systems differ from the Galactic depletion patterns or they
have a different nucleosynthetic history than our own Galaxy. We propose a new
method to derive the velocity width of absorption profiles, using the modeled
Voigt profile features. The correlation between the velocity width delta_V90 of
the absorption profile and the metallicity is found to be tighter for DLAs than
for sub-DLAs. We report hints of a bimodal distribution in the [Fe/H]
metallicity of low redshift (z < 1.25) sub-DLAs, which is unseen at higher
redshifts. This feature can be interpreted as a signature from the metal-poor,
accreting gas and the metal-rich, outflowing gas, both being traced by sub-DLAs
at low redshifts.Comment: 64 pages, 31 figures, 27 tables. Submitted to MNRA
The UV luminosity function of nearby clusters of galaxies
We present the UV composite luminosity function for galaxies in the Virgo,
Coma and Abell 1367 clusters. The luminosity function (LF) is well fitted by a
Schechter function with M*(UV} - 5*log h(75) = -20.75 +/- 0.40 and alpha =
-1.50 +/- 0.10 and does not differ significantly from the local UV luminosity
function of the field. This result is in agreement with recent studies carried
out in the Halpha and B-bands which find no difference between the LFs of star
forming galaxies in clusters and in the field. This indicates that, whatever
mechanisms are responsible for quenching the star formation in clusters, they
influence similarly the giant and the dwarf populations, leaving the shape of
the LF unchanged and only modifying its normalization.Comment: 5 pages, 4 figures, 2 tables.Accepted for publication on A&A. Data
avaliable at http://goldmine.mib.infn.it/papers/LF_UV.htm
UV excess galaxies: Wolf-Rayet galaxies
We discuss V and R band photometry for 67% of the Sullivan et al. 2000 SA57
ultraviolet-selected galaxy sample. In a sample of 176 UV-selected galaxies,
Sullivan et al. 2000 find that 24% have (UV-B) colors too blue for consistency
with starburst spectral synthesis models. We propose that these extreme blue,
UV excess galaxies are Wolf-Rayet (WR) galaxies, starburst galaxies with strong
UV emission from WR stars. We measure a median (V-R)=0.38+-0.06 for the
UV-selected sample, bluer than a sample optically selected at R but consistent
with starburst and WR galaxy colors. We demonstrate that redshifted WR emission
lines can double or triple the flux through the UV bandpass at high redshifts.
Thus the (UV-B) color of a WR galaxy can be up to 1.3 mag bluer at high
redshift, and the expected selection function is skewed to larger redshifts.
The redshift distribution of the extreme blue, UV excess galaxies matches the
selection function we predict from the properties of WR galaxies.Comment: 4 pages, including 4 figures. Uses AASTeX and emulateapj5.sty.
Includes referee change
Photometry in UV astronomical images of extended sources in crowded field using deblended images in optical visible bands as Bayesian priors
Photometry of astrophysical sources, galaxies and stars, in crowded field images, if an old problem, is still a challenging goal, as new space survey missions are launched, releasing new data with increased sensibility, resolution and field of view. The GALEX mission, observes in two UV bands and produces deep sky images of millions of galaxies or stars mixed together. These UV observations are of lower resolution than same field observed in visible bands, and with a very faint signal, at the level of the photon noise for a substantial fraction of objects. Our purpose is to use the better known optical counterparts as prior information in a Bayesian approach to deduce the UV flux. Photometry of extended sources has been addressed several times using various techniques: background determination via sigma clipping, adaptative-aperture, point-spread-function photometry, isophotal photometry, to lists some. The Bayesian approach of using optical priors for solving the UV photometry has already been applied by our team in a previous work. Here we describe the improvement of using the extended shape inferred by deblending the high resolution optical images and not only the position of the optical sources. The resulting photometric accuracy has been tested with simulation of crowded UV fields added on top of real UV images. Finally, this helps to converge to smaller and flat residual and increase the faint source detection threshold. It thus gives the opportunity to work on 2nd order effects, like improving the knowledge of the background or point-spread function by iterating on them
Clustering Properties of restframe UV selected galaxies II: Migration of Star Formation sites with cosmic time from GALEX and CFHTLS
We analyze the clustering properties of ultraviolet selected galaxies by
using GALEX-SDSS data at z<0.6 and CFHTLS deep u' imaging at z=1. These
datasets provide a unique basis at z< 1 which can be directly compared with
high redshift samples built with similar selection criteria. We discuss the
dependence of the correlation function parameters (r0, delta) on the
ultraviolet luminosity as well as the linear bias evolution. We find that the
bias parameter shows a gradual decline from high (b > 2) to low redshift (b ~
0.79^{+0.1}_{-0.08}). When accounting for the fraction of the star formation
activity enclosed in the different samples, our results suggest that the bulk
of star formation migrated from high mass dark matter halos at z>2 (10^12 <
M_min < 10^13 M_sun, located in high density regions), to less massive halos at
low redshift (M_min < 10^12 M_sun, located in low density regions). This result
extends the ``downsizing'' picture (shift of the star formation activity from
high stellar mass systems at high z to low stellar mass at low z) to the dark
matter distribution.Comment: Accepted for Publication in the Special GALEX Ap. J. Supplement,
December 2007 Version with full resolution fig1 available at
http://taltos.pha.jhu.edu/~sebastien/papers/Galex_p2.ps.g
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