2,328 research outputs found
Lived experience of mental distress and sense-making in black ethnic groups according to cultural heritage
Objective: Previous research has highlighted men and women from black ethnic groups are more likely to be diagnosed with poor mental health and may have difficulty recognising experiences as such, due to perceptions of stigma and culturally defined attributions of distress. The aim of this research was to explore how black ethnic groups experience mental distress and find meaning in their experiences according to cultural heritage.
Method: Semi-structured interviews with four participants and an Interpretative Phenomenological Analysis were conducted.
Results: Findings describe an awareness of cultural stigma relating to mental health, emotional distance impacting disclosure within the family, mental health as a misunderstood concept and feelings of empowerment through acceptance and supported disclosure. Whilst cultural heritage was important for developing awareness and understanding of stigma, attributed meanings of mental distress were individualistic.
Discussion: Awareness of how stigmatic cultural conceptualisations are generationally represented and systemically maintained is vital to understanding how people from black ethnic groups experience mental distress. Clinical implications are discussed to explore how the socio-cultural and mental health needs of this population can be met
From observer-dependent facts to frame-dependent measurement records in Wigner friend scenarios
The description of Wigner-friend scenarios -- in which external agents
describe a closed laboratory containing a friend making a measurement --
remains problematic due to the ambiguous nature of quantum measurements. One
option is to endorse assumptions leading to observer-dependent facts, given
that the friend's measurement outcome is not defined from the point of view of
the external observers. We introduce in this work a model showing that these
assumptions can also lead to measurement records that depend on the inertial
reference frame in which the agents make their observations. Our model is based
on an entangled pair shared by the friend and a distant agent performing
space-like separated measurements. An external observer at rest relative to the
closed laboratory and observers in a moving frame do not agree on the observed
records, which are not Lorentz transforms of one another
Making sense of relativistic Wigner friend scenarios
Wigner-friend scenarios -- in which external agents describe a closed
laboratory containing a friend making a measurement -- highlight the
difficulties inherent to quantum theory when accounting for measurements.
Recently, several works have investigated Wigner-friend scenarios with
relativistic constraints, systematically resulting in a contradiction between
observations made in different inertial reference frames. We examine in this
paper the reasons for and the implications of these contradictions. Having in
mind the well-known tensions between quantum theory and relativity, we will put
a particular emphasis on the role of the relativistic constraints in these
scenarios
Effect of a moving mirror on the free fall of a quantum particle in a homogeneous gravitational field
We investigate the effect of time-dependent boundary conditions on the
dynamics of a quantum bouncer -- a particle falling in a homogeneous
gravitational field on a moving mirror. We examine more particularly the way a
moving mirror modifies the properties of the entire wavefunction of a falling
particle. We find that some effects, such as the fact that a quantum particle
hitting a moving mirror may bounce significantly higher than when the mirror is
fixed, are in line with classical intuition. Other effects, such as the change
in relative phases or in the current density in spatial regions arbitrarily far
from the mirror are specifically quantum. We further discuss how the effects
produced by a moving mirror could be observed in link with current experiments,
in particular with cold neutrons
Local u'g'r'i'z' Standard Stars in the Chandra Deep Field-South
Because several observing programs are underway in various spectral regimes
to explore the Chandra Deep Field South (CDF-S), the value of local photometric
standards is obvious. As part of an NOAO Surveys Program to establish
u'g'r'i'z' standard stars in the southern hemisphere, we have observed the
central region of the CDF-S to create local standards for use by other
investigators using these filters. As a courtesy, we present the CDF-S
standards to the public now, although the main program will not finish until
mid-2005.Comment: Accepted by AJ (scheduled for October 2003 issue). 26 pages, 5
tables, 5 figures. High resolution version of Figure 7 available at
http://home.fnal.gov/~dtucker/Southern_ugriz/index.htm
The Sloan Bright Arcs Survey : Six Strongly Lensed Galaxies at z=0.4-1.4
We present new results of our program to systematically search for strongly
lensed galaxies in the Sloan Digital Sky Survey (SDSS) imaging data. In this
study six strong lens systems are presented which we have confirmed with
follow-up spectroscopy and imaging using the 3.5m telescope at the Apache Point
Observatory. Preliminary mass models indicate that the lenses are group-scale
systems with velocity dispersions ranging from 466-878 km s^{-1} at z=0.17-0.45
which are strongly lensing source galaxies at z=0.4-1.4. Galaxy groups are a
relatively new mass scale just beginning to be probed with strong lensing. Our
sample of lenses roughly doubles the confirmed number of group-scale lenses in
the SDSS and complements ongoing strong lens searches in other imaging surveys
such as the CFHTLS (Cabanac et al 2007). As our arcs were discovered in the
SDSS imaging data they are all bright (), making them ideally
suited for detailed follow-up studies.Comment: 13 pages, 3 figures, submitted to ApJL, the Sloan Bright Arcs page is
located here: http://home.fnal.gov/~kubo/brightarcs.htm
The Sloan Bright Arcs Survey: Four Strongly Lensed Galaxies with Redshift >2
We report the discovery of four very bright, strongly-lensed galaxies found
via systematic searches for arcs in Sloan Digital Sky Survey Data Release 5 and
6. These were followed-up with spectroscopy and imaging data from the
Astrophysical Research Consortium 3.5m telescope at Apache Point Observatory
and found to have redshift . With isophotal magnitudes
and 3\arcsec-diameter magnitudes , these systems are some of
the brightest and highest surface brightness lensed galaxies known in this
redshift range. In addition to the magnitudes and redshifts, we present
estimates of the Einstein radii, which range from 5.0 \arcsec to 12.7
\arcsec, and use those to derive the enclosed masses of the lensing galaxies
The 8 o'clock Arc: A Serendipitous Discovery of a Strongly Lensed Lyman Break Galaxy in the SDSS DR4 Imaging Data
We report on the serendipitous discovery of the brightest Lyman Break Galaxy
(LBG) currently known, a galaxy at z=2.73 that is being strongly lensed by the
z=0.38 Luminous Red Galaxy (LRG) SDSS J002240.91+143110.4. The arc of this
gravitational lens system, which we have dubbed the "8 o'clock arc" due to its
time of discovery, was initially identified in the imaging data of the Sloan
Digital Sky Survey Data Release 4 (SDSS DR4); followup observations on the
Astrophysical Research Consortium (ARC) 3.5m telescope at Apache Point
Observatory confirmed the lensing nature of this system and led to the
identification of the arc's spectrum as that of an LBG. The arc has a spectrum
and a redshift remarkably similar to those of the previous record-holder for
brightest LBG (MS 1512-cB58, a.k.a "cB58"), but, with an estimated total
magnitude of (g,r,i) = (20.0,19.2,19.0) and surface brightness of
(mu_g,mu_r,mu_i) = (23.3, 22.5, 22.3) mag/arcsec^2, the 8 o'clock arc is thrice
as bright. The 8 o'clock arc, which consists of three lensed images of the LBG,
is 162deg (9.6arcsec) long and has a length-to-width ratio of 6:1. A fourth
image of the LBG -- a counter-image -- can also be identified in the ARC 3.5m
g-band images. A simple lens model for the system assuming a singular
isothermal ellipsoid potential yields an Einstein radius of 2.91+/-0.14 arcsec,
a total mass for the lensing LRG (within the (10.6+/-0.5)/h kpc enclosed by the
lensed images) of 1.04x10^12/h Msun, and a magnification factor for the LBG of
12.3(+15/-3.6). The LBG itself is intrinsically quite luminous (approximately
6L*) and shows indications of massive recent star formation, perhaps as high as
160/h Msun/year.Comment: 4 pages 5 figures, submitted to ApJ Letter
A Systematic Search for High Surface Brightness Giant Arcs in a Sloan Digital Sky Survey Cluster Sample
We present the results of a search for gravitationally-lensed giant arcs
conducted on a sample of 825 SDSS galaxy clusters. Both a visual inspection of
the images and an automated search were performed and no arcs were found. This
result is used to set an upper limit on the arc probability per cluster. We
present selection functions for our survey, in the form of arc detection
efficiency curves plotted as functions of arc parameters, both for the visual
inspection and the automated search. The selection function is such that we are
sensitive only to long, high surface brightness arcs with g-band surface
brightness mu_g 10. Our upper limits on
the arc probability are compatible with previous arc searches. Lastly, we
report on a serendipitous discovery of a giant arc in the SDSS data, known
inside the SDSS Collaboration as Hall's arc.Comment: 34 pages,8 Fig. Accepted ApJ:Jan-200
Large Scale Structure in the SDSS Galaxy Survey
The Large Scale Structure (LSS) in the galaxy distribution is investigated
using the Sloan Digital Sky Survey Early Data Release (SDSS EDR). Using the
Minimal Spanning Tree technique we have extracted sets of filaments, of
wall-like structures, of galaxy groups, and of rich clusters from this unique
sample. The physical properties of these structures were then measured and
compared with the expectations from Zel'dovich' theory.
The measured characteristics of galaxy walls were found to be consistent with
those for a spatially flat CDM cosmological model with
0.3 and 0.7, and for Gaussian
initial perturbations with a Harrison -- Zel'dovich power spectrum.
Furthermore, we found that the mass functions of groups and of unrelaxed
structure elements generally fit well with the expectations from Zel'dovich'
theory, although there was some discrepancy for lower mass groups which may be
due to incompleteness in the selected sample of groups. We also note that both
groups and rich clusters tend to prefer the environments of walls, which tend
to be of higher density, rather than the environments of filaments, which tend
to be of lower density.
Finally, we note evidence of systematic differences in the properties of the
LSS between the Northern Galactic Cap stripe and the Southern Galactic Cap
stripe -- in particular, in the physical properties of the walls, their spatial
distribution, and the relative numbers of clusters embedded in walls. Because
the mean separation of walls is 60 -- 70 Mpc, each stripe
only intersects a few tens of walls. Thus, small number statistics and cosmic
variance are the likely drivers of these systematic differences.Comment: 13 pages, 11 figures, MNRAS submitte
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