2,839 research outputs found
WHERE YOU LIVE DOES MATTER: THE IMPACT OF RACIAL RESIDENTIAL SEGREGATION ON RACIAL DISPARITIES IN CANCER INCIDENCE AND MORTALITY IN NORTHEASTERN AND SOUTHERN U.S. COUNTIES, 2005-2009
This study merges the frameworks of social epidemiology, human ecology, and Critical Race Theory to examine the impact of racial residential segregation on racial disparities in cancer incidence/mortality and characteristics of the social and physical environment. County-level data on cancer incidence, cancer mortality, racial residential segregation, and other characteristics of the social and physical environment are collected from nine publically-available sources.
Regression models identify predictors of the racial disparity in cancer incidence and cancer mortality. Racial residential segregation is not a significant predictor of the racial gap in cancer incidence or the racial gap in cancer mortality after controlling for the racial gap in median household income. Racial disparity in median household income is the most significant predictor of both the racial gap in cancer incidence and the racial gap in cancer mortality. Although there is no significant relationship between racial residential segregation and the racial gap in cancer incidence and cancer mortality was not found, highly segregated areas do face certain forms of disadvantage in several health-protecting resources—housing, exposure to environmental pollutants, educational attainment, and economic opportunities.
In order for interventions and policies to be effective in reducing racial disparities in health outcomes, the structural (i.e., foundational and fundamental) causes of these inequalities—institutional racism, racial residential segregation, economic/educational inequalities—must be addressed. In addition, the methods used to "protect confidentiality" and "maintain data reliability" of publically available data sources need to be examined through the lens of Critical Race Theory to determine whether these methods are simply supporting the racialized structure and protecting the status quo
Time Delay Measurements for the Cluster-lensed Sextuple Quasar SDSS J2222+2745
We report first results from an ongoing monitoring campaign to measure time
delays between the six images of the quasar SDSS\,J22222745, gravitationally
lensed by a galaxy cluster. The time delay between A and B, the two most highly
magnified images, is measured to be days (95\%
confidence interval), consistent with previous model predictions for this lens
system. The strong intrinsic variability of the quasar also allows us to derive
a time delay value of days between image C and A,
in spite of modest overlap between their light curves in the current data set.
Image C, which is predicted to lead all the other lensed quasar images, has
undergone a sharp, monotonic flux increase of 60-75\% during 2014. A
corresponding brightening is firmly predicted to occur in images A and B during
2016. The amplitude of this rise indicates that time delays involving all six
known images in this system, including those of the demagnified central images
D-F, will be obtainable from further ground-based monitoring of this system
during the next few years.Comment: 9 pages, 9 figures, Version accepted for publication in Ap
On the lack of correlation between Mg II 2796, 2803 Angstrom and Lyman alpha emission in lensed star-forming galaxies
We examine the Mg II 2796, 2803 Angstrom, Lyman alpha, and nebular line
emission in five bright star-forming galaxies at 1.66<z<1.91 that have been
gravitationally lensed by foreground galaxy clusters. All five galaxies show
prominent Mg II emission and absorption in a P Cygni profile. We find no
correlation between the equivalent widths of Mg II and Lyman alpha emission.
The Mg II emission has a broader range of velocities than do the nebular
emission line profiles; the Mg II emission is redshifted with respect to
systemic by 100 to 200 km/s. When present, Lyman alpha is even more redshifted.
The reddest components of Mg II and Lyman alpha emission have tails to 500-600
km/s, implying a strong outflow. The lack of correlation in the Mg II and Lyman
alpha equivalent widths, the differing velocity profiles, and the high ratios
of Mg II to nebular line fluxes together suggest that the bulk of Mg II
emission does not ultimately arise as nebular line emission, but may instead be
reprocessed stellar continuum emission.Comment: The Astrophysical Journal, in press. 6 pages, 2 figure
Thermal tolerance and potential distribution of Carvalhotingis visenda (Hemiptera: Tingidae), a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae)
The specialist tingid, Carvalhotingis visenda, is a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae). Cat's claw creeper is an invasive liana with a wide climatic tolerance, and for biological control to be effective the tingid must survive and develop over a range of temperatures. We evaluated the effect of constant temperatures (0-45°C) on the survival and development of C. visenda. Adults showed tolerance for wider temperature ranges (0-45°C), but oviposition, egg hatching and nymphal development were all affected by both high (>30°C) and low (<20°C) temperatures. Temperatures between 20°C and 30°C are the most favourable for adult survival, oviposition, egg hatching and nymphal development. The ability of adults and nymphs to survive for a few days at high (40°C and 45°C) and low (0°C and 5°C) temperatures suggest that extreme temperature events, which usually occur for short durations (hours) in cat's claw creeper infested regions in Queensland and New South Wales states are not likely to affect the tingid population. The potential number of generations (egg to adult) the tingid can complete in a year in Australia ranged from three to eight, with more generations in Queensland than in New South Wales
A Mesolithic settlement site at Howick, Northumberland: a preliminary report
Excavations at a coastal site at Howick during 2000 and 2002 have revealed evidence for a substantial Mesolithic settlement and a Bronze Age cist cemetery. Twenty one radiocarbon determinations of the earlier eighth millennium BP (Cal.) indicate that the Mesolithic site is one of the earliest known in northern Britain. An 8m core of sediment was recovered from stream deposits adjacent to the archaeological site which provides information on local environmental conditions. Howick offers a unique opportunity to understand aspects of hunter-gatherer colonisation and settlement during a period of rapid palaeogeographical change around the margins of the North Sea basin, at a time when it was being progressively inundated by the final stages of the postglacial marine transgression. The cist cemetery will add to the picture of Bronze Age occupation of the coastal strip and again reveals a correlation between the location of Bronze Age and Mesolithic sites which has been observed elsewhere in the region
[OII] emitters in the GOODS field at z~1.85: a homogeneous measure of evolving star formation
We present the results of a deep, near-infrared, narrow band imaging survey
at a central wavelength of 1.062 microns (FWHM=0.01 microns) in the GOODS-South
field using the ESO VLT instrument, HAWK-I. The data are used to carry out the
highest redshift search for [OII]3727 emission line galaxies to date. The
images reach an emission line flux limit (5 sigma) of 1.5 x 10^-17 erg cm^-2
s^-1, additionally making the survey the deepest of its kind at high redshift.
In this paper we identify a sample of [OII]3727 emission line objects at
redshift z~1.85 in a co-moving volume of ~4100 Mpc^3. Objects are selected
using an observed equivalent width (EW_obs) threshold of EW_obs = 50 angstroms.
The sample is used to derive the space density and constrain the luminosity
function of [OII] emitters at z=1.85. We find that the space density of objects
with observed [OII] luminosities in the range log(L_[OII]) > 41.74 erg s^-1 is
log(rho)=-2.45+/-0.14 Mpc^-3, a factor of 2 greater than the observed space
density of [OII] emitters reported at z~1.4. After accounting for completeness
and assuming an internal extinction correction of A_Halpha=1 mag (equivalent to
A_[OII]=1.87), we report a star formation rate density of rho* ~0.38+/-0.06
Msun yr^-1 Mpc^-3. We independently derive the dust extinction of the sample
using 24 micron fluxes and find a mean extinction of A_[OII]=0.98+/-0.11
magnitudes (A_Halpha=0.52). This is significantly lower than the A_Halpha=1
(A[OII]=1.86) mag value widely used in the literature. Finally we incorporate
this improved extinction correction into the star formation rate density
measurement and report rho*~0.24+/-0.06 Msun yr^-1 Mpc^-3.Comment: 11 pages, 10 figures, accepted for publication in MNRA
Searching for Cooling Signatures in Strong Lensing Galaxy Clusters: Evidence Against Baryons Shaping the Matter Distribution in Cluster Cores
The process by which the mass density profile of certain galaxy clusters
becomes centrally concentrated enough to produce high strong lensing (SL)
cross-sections is not well understood. It has been suggested that the baryonic
condensation of the intra-cluster medium (ICM) due to cooling may drag dark
matter to the cores and thus steepen the profile. In this work, we search for
evidence of ongoing ICM cooling in the first large, well-defined sample of
strong lensing selected galaxy clusters in the range 0.1 < z < 0.6. Based on
known correlations between the ICM cooling rate and both optical emission line
luminosity and star formation, we measure, for a sample of 89 strong lensing
clusters, the fraction of clusters that have [OII]3727 emission in their
brightest cluster galaxy (BCG). We find that the fraction of line-emitting BCGs
is constant as a function of redshift for z > 0.2 and shows no statistically
significant deviation from the total cluster population. Specific star
formation rates, as traced by the strength of the 4000 angstrom break, D_4000,
are also consistent with the general cluster population. Finally, we use
optical imaging of the SL clusters to measure the angular separation, R_arc,
between the arc and the center of mass of each lensing cluster in our sample
and test for evidence of changing [OII] emission and D_4000 as a function of
R_arc, a proxy observable for SL cross-sections. D_4000 is constant with all
values of R_arc, and the [OII] emission fractions show no dependence on R_arc
for R_arc > 10" and only very marginal evidence of increased weak [OII]
emission for systems with R_arc < 10". These results argue against the ability
of baryonic cooling associated with cool core activity in the cores of galaxy
clusters to strongly modify the underlying dark matter potential, leading to an
increase in strong lensing cross-sections.Comment: 9 Pages, 5 Figures, 1 Tabl
Constraining the metallicities, ages, star formation histories, and ionizing continua of extragalactic massive star populations
We infer the properties of massive star populations using the far-ultraviolet
stellar continua of 61 star-forming galaxies: 42 at low-z observed with HST and
19 at z~2 from the Megasaura sample. We fit each stellar continuum with a
linear combination of up to 50 single age and single metallicity Starburst99
models. From these fits, we derive light-weighted ages and metallicities, which
agree with stellar wind and photospheric spectral features, and infer the
spectral shapes and strengths of the ionizing continua. Inferred light-weighted
stellar metallicities span 0.05-1.5 Z and are similar to the measured
nebular metallicities. We quantify the ionizing continua using the ratio of the
ionizing flux at 900\AA\ to the non-ionizing flux at 1500\AA\ and demonstrate
the evolution of this ratio with stellar age and metallicity using theoretical
single burst models. These single burst models only match the inferred ionizing
continua of half of the sample, while the other half are described by a mixture
of stellar ages. Mixed age populations produce stronger and harder ionizing
spectra than continuous star formation histories, but, contrary to previous
studies that assume constant star formation, have similar stellar and nebular
metallicities. Stellar population age and metallicity affect the far-UV
continua in different and distinguishable ways; assuming a constant star
formation history diminishes the diagnostic power. Finally, we provide simple
prescriptions to determine the ionizing photon production efficiency
() from the stellar population properties. has a range
of log( Hz erg that depends on stellar age,
metallicity, star formation history, and contributions from binary star
evolution. These stellar population properties must be observationally
determined to determine the number of ionizing photons generated by massive
stars.Comment: 31 pages, 23 figures, resubmitted to ApJ after incorporating the
referee's comments. Comments encourage
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