244 research outputs found
Food Stamp Participation and Reasons for Nonparticipation: 1986
The decision of eligible households to participate in the food stamp program is analyzed utilizing the 1986 Panel Study of Income Dynamics. Less than one-half of the sample of eligible households receive food stamps in 1986. The results of a multinomial logit model suggest that participation is related negatively to the age and educational level of the household head and positively to the benefit level. Participation is lower for single men and households residing in the West and higher for people with disabilities and households receiving some form of public transfer income. Problems regarding information about food stamps and personal attitudes toward food stamp use have the greatest impact on the decision to participate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44658/1/10834_2004_Article_418066.pd
The Changing Nature of Poverty
Since the beginning of the War on Poverty, the poverty rate has fluctuated widely, and at the same time the poverty population has undergone many changes, some mirroring the changing stereotypes of the poor and others less pronounced than the changing stereotypes would lead us to believe. A feminization of poverty has occurred, with many more of the poor now in households headed by women. Interestingly, aging of the poverty population has not occurred despite growth in the elderly segment of the overall population. Concerning turnover in the poverty population, we find that despite poverty theories emphasizing persistence, recurrent poverty is relatively rare and poverty is not generally passed from one generation to the next. Poverty prevention has come from both economic growth and government transfers; however, inequality in economic growth has contributed to poverty. With the proportion of elderly and female- headed households likely to continue at a high level into the future, poverty rates are also likely to remain high unless government transfers are increased.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66979/2/10.1177_000271628547900103.pd
Economic crisis and the construction of a neo-liberal regulatory regime in Korea
A consistent theme of the literature on the ontology of the 1997 South Korean crisis is the key role played by regulatory failures and the growing weakness of the state. This paper seeks to briefly highlight both the insights and the limitations of this approach to understanding the crisis. Having done so, we shall set out the argument that the crisis created an opportunity for reformist Korean Ă©lites to advance their longstanding, but previously frustrated, project to create a comprehensive unambiguously neo-liberal regulatory regime. This paper will also seek to highlight the implications of our reading of the development of the Korean political economy for broader debates on economic liberalisation, crisis and the future of the developmental state
XMM-Newton observations of the Galactic Supernova Remnant CTB 109 (G109.1-1.0)
We present the analysis of the X-ray Multi-Mirror Mission (XMM-Newton)
European Photon Imaging Camera (EPIC) data of the Galactic supernova remnant
(SNR) CTB 109 (G109.1-1.0). CTB 109 is associated with the anomalous X-ray
pulsar (AXP) 1E 2259+586 and has an unusual semi-circular morphology in both
the X-ray and the radio, and an extended X-ray bright interior region known as
the `Lobe'. The deep EPIC mosaic image of the remnant shows no emission towards
the west where a giant molecular cloud complex is located. No morphological
connection between the Lobe and the AXP is found. We find remarkably little
spectral variation across the remnant given the large intensity variations. All
spectra of the shell and the Lobe are well fitted by a single-temperature
non-equilibrium ionization model for a collisional plasma with solar abundances
(kT = 0.5 - 0.7 keV, tau = n_e t = 1 - 4 x 10^11 s cm^-3, N_H = 5 - 7 x 10^21
cm^-2). There is no indication of nonthermal emission in the Lobe or the shell.
We conclude that the Lobe originated from an interaction of the SNR shock wave
with an interstellar cloud. Applying the Sedov solution for the undisturbed
eastern part of the SNR, and assuming full equilibration between the electrons
and ions behind the shock front, the SNR shock velocity is derived as v_s = 720
+/- 60 km s^-1, the remnant age as t = (8.8 +/- 0.9) x 10^3 d_3 yr, the initial
energy as E_0 = (7.4 +/- 2.9) x 10^50 d_3^2.5 ergs, and the pre-shock density
of the nuclei in the ambient medium as n_0 = (0.16 +/- 0.02) d_3^-0.5 cm^-3, at
an assumed distance of D = 3.0 d_3 kpc. Assuming CTB 109 and 1E 2259+586 are
associated, these values constrain the age and the environment of the
progenitor of the SNR and the pulsar.Comment: Accepted for publication in ApJ. 9 figures. Figs. 1 + 2 are in color
(fig1.jpg, fig2.jpg
Physical activity, fatigue, and sleep in people with Parkinsonâs disease: A secondary per protocol analysis from an intervention trial
Symptoms of Parkinsonâs can result in low physical activity and poor sleep patterns which can have a detrimental effect on a personâs quality of life. To date, studies looking into exercise interventions for people with Parkinsonâs (PwP) for symptom management are promising but inconclusive. The aim of this study is to estimate the effect of a clearly defined exercise prescription on general physical activity levels, fatigue, sleep, and quality of life in PwP. Method. PwP randomised into either an exercise group (29; 16 males, 13 females; mean age 67 years (7.12)) or a control handwriting group (36; 19 males; 17 females; mean age 67 years (5.88)) as part of a larger trial were included in this substudy if they had completed a 6-month weekly exercise programme (intervention group) and had complete objective physical activity data (intervention and control group). Sleep and fatigue were recorded from self-reported measures, and physical activity levels measured through the use of accelerometers worn 24 hours/day over a seven-day testing period at baseline and following the 24-week intervention. A Wilcoxonâs test followed by a MannâWhitney post hoc analysis was used, and effect sizes were calculated. Results. Participants showed a significant increase in time spent in sedentary and light activities during the overnight period postintervention in both exercise and handwriting groups (p < 0.05) with a moderate effect found for the change in sedentary and light activities in the overnight hours for both groups, over time (0.32 and 0.37-0.38, resp.). There was no impact on self-reported fatigue or sleep. Conclusion. The observed moderate effect on sedentary and light activities overnight could suggest an objective improvement in sleep patterns for individuals participating in both exercise and handwriting interventions. This supports the need for further studies to investigate the role of behavioural interventions for nonmotor symptoms
Periodicities in the high-mass X-ray binary system RXJ0146.9+6121/LSI+61 235
The high-mass X-ray binary RX J0146.9+6121, with optical counterpart LS I+61°235 (V831 Cas), is an intriguing system on the outskirts of the open cluster NGC 663. It contains the slowest Be type X-ray pulsar known with a pulse period of around 1400 s and, primarily from the study of variation in the emission line profile of Hα, it is known to have a Be decretion disc with a one-armed density wave period of approximately 1240 d. Here we present the results of an extensive photometric campaign, supplemented with optical spectroscopy, aimed at measuring short time-scale periodicities. We find three significant periodicities in the photometric data at, in order of statistical significance, 0.34, 0.67 and 0.10 d. We give arguments to support the interpretation that the 0.34 and 0.10 d periods could be due to stellar oscillations of the B-type primary star and that the 0.67 d period is the spin period of the Be star with a spin axis inclination of 23+10â8 degrees. We measured a systemic velocity of â37.0 ± 4.3 km sâ1 confirming that LS I+61°235 has a high probability of membership in the young cluster NGC 663 from which the system's age can be estimated as 20â25 Myr. From archival RXTE All Sky Monitor (ASM) data we further find âsuperâ X-ray outbursts roughly every 450 d. If these super outbursts are caused by the alignment of the compact star with the one-armed decretion disc enhancement, then the orbital period is approximately 330 d
z~7 galaxy candidates from NICMOS observations over the HDF South and the CDF-S and HDF-N GOODS fields
We use ~88 arcmin**2 of deep (>~26.5 mag at 5 sigma) NICMOS data over the two
GOODS fields and the HDF South to conduct a search for bright z>~7 galaxy
candidates. This search takes advantage of an efficient preselection over 58
arcmin**2 of NICMOS H-band data where only plausible z>~7 candidates are
followed up with NICMOS J-band observations. ~248 arcmin**2 of deep
ground-based near-infrared data (>~25.5 mag, 5 sigma) is also considered in the
search. In total, we report 15 z-dropout candidates over this area -- 7 of
which are new to these search fields. Two possible z~9 J-dropout candidates are
also found, but seem unlikely to correspond to z~9 galaxies. The present z~9
search is used to set upper limits on the prevalence of such sources. Rigorous
testing is undertaken to establish the level of contamination of our selections
by photometric scatter, low mass stars, supernovae (SNe), and spurious sources.
The estimated contamination rate of our z~7 selection is ~24%. Through careful
simulations, the effective volume available to our z>~7 selections is estimated
and used to establish constraints on the volume density of luminous (L*(z=3),
or -21 mag) galaxies from these searches. We find that the volume density of
luminous star-forming galaxies at z~7 is 13_{-5}^{+8}x lower than at z~4 and
>25x lower (1 sigma) at z~9 than at z~4. This is the most stringent constraint
yet available on the volume density of >~L* galaxies at z~9. The present
wide-area, multi-field search limits cosmic variance to <20%. The evolution we
find at the bright end of the UV LF is similar to that found from recent Subaru
Suprime-Cam, HAWK-I or ERS WFC3/IR searches. The present paper also includes a
complete summary of our final z~7 z-dropout sample (18 candidates) identified
from all NICMOS observations to date (over the two GOODS fields, the HUDF,
galaxy clusters).Comment: 13 pages, 6 figures, 6 tables, accepted for publication in the
Astrophysical Journal, replaced to match accepted version, see
http://firstgalaxies.org/astronomers-area/ for a link to a complete reduction
of the NICMOS observations over the two GOODS field
Combined strong and weak lensing analysis of 28 clusters from the Sloan Giant Arcs Survey
We study the mass distribution of a sample of 28 galaxy clusters using strong
and weak lensing observations. The clusters are selected via their strong
lensing properties as part of the Sloan Giant Arcs Survey (SGAS) from the Sloan
Digital Sky Survey (SDSS). Mass modelling of the strong lensing information
from the giant arcs is combined with weak lensing measurements from deep
Subaru/Suprime-cam images to primarily obtain robust constraints on the
concentration parameter and the shape of the mass distribution. We find that
the concentration c_vir is a steep function of the mass, c_vir \propto
M_vir^-0.59\pm0.12, with the value roughly consistent with the
lensing-bias-corrected theoretical expectation for high mass (10^15 h^-1 M_sun)
clusters. However, the observationally inferred concentration parameters appear
to be much higher at lower masses (10^14 h^-1 M_sun), possibly a consequence of
the modification to the inner density profiles provided by baryon cooling. The
steep mass-concentration relation is also supported from direct stacking
analysis of the tangential shear profiles. In addition, we explore the
two-dimensional shape of the projected mass distribution by stacking weak
lensing shear maps of individual clusters with prior information on the
position angle from strong lens modelling, and find significant evidence for a
large mean ellipticity with the best-fit value of e = 0.47 \pm 0.06 for the
mass distribution of the stacked sample. We find that the luminous cluster
member galaxy distribution traces the overall mass distribution very well,
although the distribution of fainter cluster galaxies appears to be more
extended than the total mass.Comment: 29 pages, 15+9 figures, 7 tables, accepted for publication in MNRA
Cluster Lenses
Clusters of galaxies are the most recently assembled, massive, bound
structures in the Universe. As predicted by General Relativity, given their
masses, clusters strongly deform space-time in their vicinity. Clusters act as
some of the most powerful gravitational lenses in the Universe. Light rays
traversing through clusters from distant sources are hence deflected, and the
resulting images of these distant objects therefore appear distorted and
magnified. Lensing by clusters occurs in two regimes, each with unique
observational signatures. The strong lensing regime is characterized by effects
readily seen by eye, namely, the production of giant arcs, multiple-images, and
arclets. The weak lensing regime is characterized by small deformations in the
shapes of background galaxies only detectable statistically. Cluster lenses
have been exploited successfully to address several important current questions
in cosmology: (i) the study of the lens(es) - understanding cluster mass
distributions and issues pertaining to cluster formation and evolution, as well
as constraining the nature of dark matter; (ii) the study of the lensed objects
- probing the properties of the background lensed galaxy population - which is
statistically at higher redshifts and of lower intrinsic luminosity thus
enabling the probing of galaxy formation at the earliest times right up to the
Dark Ages; and (iii) the study of the geometry of the Universe - as the
strength of lensing depends on the ratios of angular diameter distances between
the lens, source and observer, lens deflections are sensitive to the value of
cosmological parameters and offer a powerful geometric tool to probe Dark
Energy. In this review, we present the basics of cluster lensing and provide a
current status report of the field.Comment: About 120 pages - Published in Open Access at:
http://www.springerlink.com/content/j183018170485723/ . arXiv admin note:
text overlap with arXiv:astro-ph/0504478 and arXiv:1003.3674 by other author
A highly magnified candidate for a young galaxy seen when the Universe was 500 Myrs old
The early Universe at redshift z\sim6-11 marks the reionization of the
intergalactic medium, following the formation of the first generation of stars.
However, those young galaxies at a cosmic age of \lesssim 500 million years
(Myr, at z \gtrsim 10) remain largely unexplored as they are at or beyond the
sensitivity limits of current large telescopes. Gravitational lensing by galaxy
clusters enables the detection of high-redshift galaxies that are fainter than
what otherwise could be found in the deepest images of the sky. We report the
discovery of an object found in the multi-band observations of the cluster
MACS1149+22 that has a high probability of being a gravitationally magnified
object from the early universe. The object is firmly detected (12 sigma) in the
two reddest bands of HST/WFC3, and not detected below 1.2 {\mu}m, matching the
characteristics of z\sim9 objects. We derive a robust photometric redshift of z
= 9.6 \pm 0.2, corresponding to a cosmic age of 490 \pm 15Myr (i.e., 3.6% of
the age of the Universe). The large number of bands used to derive the redshift
estimate make it one of the most accurate estimates ever obtained for such a
distant object. The significant magnification by cluster lensing (a factor of
\sim15) allows us to analyze the object's ultra-violet and optical luminosity
in its rest-frame, thus enabling us to constrain on its stellar mass,
star-formation rate and age. If the galaxy is indeed at such a large redshift,
then its age is less than 200 Myr (at the 95% confidence level), implying a
formation redshift of zf \lesssim 14. The object is the first z>9 candidate
that is bright enough for detailed spectroscopic studies with JWST,
demonstrating the unique potential of galaxy cluster fields for finding highly
magnified, intrinsically faint galaxies at the highest redshifts.Comment: Submitted to the Nature Journal. 39 Pages, 13 figure
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