1,299 research outputs found
GALEX UV Color-Magnitude Relations and Evidence for Recent Star Formation in Early-type Galaxies
We have used the GALEX UV photometric data to construct a first
near-ultraviolet (NUV) color-magnitude relation (CMR) for the galaxies
pre-classified as early-type by SDSS studies. The NUV CMR is a powerful tool
for tracking the recent star formation history in early-type galaxies, owing to
its high sensitivity to the presence of young stellar populations. Our NUV CMR
for UV-weak galaxies shows a well-defined slope and thus will be useful for
interpreting the restframe NUV data of distant galaxies and studying their star
formation history. Compared to optical CMRs, the NUV CMR shows a substantially
larger scatter, which we interpret as evidence of recent star formation
activities. Roughly 15% of the recent epoch (z < 0.13) bright (M[r] < -22)
early-type galaxies show a sign of recent (< 1Gyr) star formation at the 1-2%
level (lower limit) in mass compared to the total stellar mass. This implies
that low level residual star formation was common during the last few billion
years even in bright early-type galaxies.Comment: This paper will be published as part of the Galaxy Evolution Explorer
(GALEX) Astrophysical Journal Letters Special Issue. Links to the full set of
papers will be available at http://www.galex.caltech.edu/PUBLICATIONS/ after
November 22, 200
Predictions for ASKAP Neutral Hydrogen Surveys
The Australian Square Kilometer Array Pathfinder (ASKAP) will revolutionise
our knowledge of gas-rich galaxies in the Universe. Here we present predictions
for two proposed extragalactic ASKAP neutral hydrogen (HI) emission-line
surveys, based on semi-analytic models applied to cosmological N-body
simulations. The ASKAP HI All-Sky Survey, known as WALLABY, is a shallow 3 Pi
survey (z = 0 - 0.26) which will probe the mass and dynamics of over 600,000
galaxies. A much deeper small-area HI survey, called DINGO, aims to trace the
evolution of HI from z = 0 - 0.43, a cosmological volume of 40 million Mpc^3,
detecting potentially 100,000 galaxies. The high-sensitivity 30 antenna ASKAP
core (diameter ~2 km) will provide an angular resolution of 30 arcsec (at z=0).
Our simulations show that the majority of galaxies detected in WALLABY (87.5%)
will be resolved. About 5000 galaxies will be well resolved, i.e. more than
five beams (2.5 arcmin) across the major axis, enabling kinematic studies of
their gaseous disks. This number would rise to 160,000 galaxies if all 36 ASKAP
antennas could be used; the additional six antennas provide baselines up to 6
km, resulting in an angular resolution of 10 arcsec. For DINGO this increased
resolution is highly desirable to minimise source confusion; reducing confusion
rates from a maximum of 10% of sources at the survey edge to 3%. We estimate
that the sources detected by WALLABY and DINGO will span four orders of
magnitude in total halo mass (from 10^{11} to 10^{15} Msol) and nearly seven
orders of magnitude in stellar mass (from 10^{5} to 10^{12} Msol), allowing us
to investigate the process of galaxy formation across the last four billion
years.Comment: 21 pages, accepted for publication in MNRAS, minor updates to
published version and fixed links. Movies and images available at
http://ict.icrar.org/store/Movies/Duffy12c
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Metabolite Profiles During Oral Glucose Challenge
To identify distinct biological pathways of glucose metabolism, we conducted a systematic evaluation of biochemical changes after an oral glucose tolerance test (OGTT) in a community-based population. Metabolic profiling was performed on 377 nondiabetic Framingham Offspring cohort participants (mean age 57 years, 42% women, BMI 30 kg/m2) before and after OGTT. Changes in metabolite levels were evaluated with paired Student t tests, cluster-based analyses, and multivariable linear regression to examine differences associated with insulin resistance. Of 110 metabolites tested, 91 significantly changed with OGTT (P ≤ 0.0005 for all). Amino acids, β-hydroxybutyrate, and tricarboxylic acid cycle intermediates decreased after OGTT, and glycolysis products increased, consistent with physiological insulin actions. Other pathways affected by OGTT included decreases in serotonin derivatives, urea cycle metabolites, and B vitamins. We also observed an increase in conjugated, and a decrease in unconjugated, bile acids. Changes in β-hydroxybutyrate, isoleucine, lactate, and pyridoxate were blunted in those with insulin resistance. Our findings demonstrate changes in 91 metabolites representing distinct biological pathways that are perturbed in response to an OGTT. We also identify metabolite responses that distinguish individuals with and without insulin resistance. These findings suggest that unique metabolic phenotypes can be unmasked by OGTT in the prediabetic state
Efficacy and safety of emtricitabine/tenofovir alafenamide (FTC/TAF) vs. emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) as a backbone for treatment of HIV-1 infection in virologically suppressed adults: subgroup analysis by third agent of a randomized, double-blind, active-controlled phase 3 trial*
Background: FTC/TAF was shown to be noninferior to FTC/TDF with advantages in markers of renal and bone safety.Objective: To evaluate the efficacy and safety of switching to FTC/TAF from FTC/TDF by third agent (boosted protease inhibitor [PI] vs. unboosted third agent).Methods: We conducted a 48-week subgroup analysis based on third agent from a randomized, double blind study in virologically suppressed adults on a FTC/TDF-containing regimen who switched to FTC/TAF vs. continued FTC/TDF while remaining on the same third agent.Results: We randomized (1:1) 663 participants to either switch to FTC/TAF (N = 333) or continue FTC/TDF (N = 330), each with baseline third agent stratifying by class of third agent in the prior treatment regimen (boosted PI 46%, unboosted third agent 54%). At week 48, significant differences in renal biomarkers and bone mineral density were observed favoring FTC/TAF over FTC/TDF (p < 0.05 for all), with similar improvements in the FTC/TAF arm in those who received boosted PI vs. unb..
WALLABY Early Science - I. The NGC 7162 Galaxy Group
We present Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY) early
science results from the Australian Square Kilometre Array Pathfinder (ASKAP)
observations of the NGC 7162 galaxy group. We use archival HIPASS and Australia
Telescope Compact Array (ATCA) observations of this group to validate the new
ASKAP data and the data reduction pipeline ASKAPsoft. We detect six galaxies in
the neutral hydrogen (HI) 21-cm line, expanding the NGC 7162 group membership
from four to seven galaxies. Two of the new detections are also the first HI
detections of the dwarf galaxies, AM 2159-434 and GALEXASC J220338.65-431128.7,
for which we have measured velocities of and km s,
respectively. We confirm that there is extended HI emission around NGC 7162
possibly due to past interactions in the group as indicated by the
offset between the kinematic and morphological major axes for NGC 7162A, and
its HI richness. Taking advantage of the increased resolution (factor of
) of the ASKAP data over archival ATCA observations, we fit a tilted
ring model and use envelope tracing to determine the galaxies' rotation curves.
Using these we estimate the dynamical masses and find, as expected, high dark
matter fractions of for all group members. The
ASKAP data are publicly available.Comment: 20 pages, 11 figures, accepted for publication in MNRA
The Look-back Time Evolution of Far-Ultraviolet Flux from the Brightest Cluster Elliptical Galaxies at z < 0.2
We present the GALEX UV photometry of the elliptical galaxies in Abell
clusters at moderate redshifts (z < 0.2) for the study of the look-back time
evolution of the UV upturn phenomenon. The brightest elliptical galaxies (M_r <
-22) in 12 remote clusters are compared with the nearby giant elliptical
galaxies of comparable optical luminosity in the Fornax and Virgo clusters. The
sample galaxies presented here appear to be quiescent without signs of massive
star formation or strong nuclear activity, and show smooth, extended profiles
in their UV images indicating that the far-UV (FUV) light is mostly produced by
hot stars in the underlying old stellar population. Compared to their
counterparts in nearby clusters, the FUV flux of cluster giant elliptical
galaxies at moderate redshifts fades rapidly with ~ 2 Gyrs of look-back time,
and the observed pace in FUV - V color evolution agrees reasonably well with
the prediction from the population synthesis models where the dominant FUV
source is hot horizontal-branch stars and their progeny. A similar amount of
color spread (~ 1 mag) in FUV - V exists among the brightest cluster elliptical
galaxies at z ~ 0.1, as observed among the nearby giant elliptical galaxies of
comparable optical luminosity.Comment: Accepted for publication in the Special GALEX ApJ Supplement,
December 200
GALEX UV Color Relations for Nearby Early-Type Galaxies
We use GALEX/optical photometry to construct color-color relationships for
early-type galaxies sorted by morphological type. We have matched objects in
the GALEX GR1 public release and the first IR1.1 internal release, with the RC3
early-type galaxies having a morphological type -5.5<T<-1.5 with mean error in
T<1.5, and mean error on (B-V)T<0.05. After visual inspection of each match, we
are left with 130 galaxies with a reliable GALEX pipeline photometry in the
far-UV and near-UV bands. This sample is divided into Ellipticals (-5.5<T<-3.5)
and Lenticulars (-3.5<T<-1.5). After correction for the Galactic extinction,
the color-color diagrams FUV-NUV vs. (B-V)_{Tc} are plotted for the two
subsamples. We find a tight anti-correlation between the FUV-NUV and (B-V)_{Tc}
colors for Ellipticals, the UV color getting bluer when the (B-V)_{Tc} get
redder. This relationship very likely is an extension of the color-metallicity
relationship into the GALEX NUV band. We suspect that the main source of the
correlation is metal line blanketing in the NUV band. The FUV-NUV vs B-V
correlation has larger scatter for lenticular galaxies; we speculate this
reflects the presence of low level star formation. If the latter objects (i.e.
those that are blue both in FUV-NUV and B-V) are interpreted as harboring
recent star formation activity, this would be the case for a few percent (~4%)
of Ellipticals and ~15% of Lenticulars; this would make about 10% of early-type
galaxies with residual star formation in our full sample of 130 early-type
galaxies. We also plot FUV-NUV vs. the Mg_2 index and central velocity
dispersion. We find a tight anti-correlation between FUV-NUV and the Mg_2
index(...).Comment: 25 pages, 5 figures, accepted for publication in ApJS (abstract
abridged), typos corrected in section 2.
CATdb: a public access to Arabidopsis transcriptome data from the URGV-CATMA platform
CATdb is a free resource available at http://urgv.evry.inra.fr/CATdb that provides public access to a large collection of transcriptome data for Arabidopsis thaliana produced by a single Complete Arabidopsis Transcriptome Micro Array (CATMA) platform. CATMA probes consist of gene-specific sequence tags (GSTs) of 150–500 bp. The v2 version of CATMA contains 24 576 GST probes representing most of the predicted A. thaliana genes, and 615 probes tiling the chloroplastic and mitochondrial genomes. Data in CATdb are entirely processed with the same standardized protocol, from microarray printing to data analyses. CATdb contains the results of 53 projects including 1724 hybridized samples distributed between 13 different organs, 49 different developmental conditions, 45 mutants and 63 environmental conditions. All the data contained in CATdb can be downloaded from the web site and subsets of data can be sorted out and displayed either by keywords, by experiments, genes or lists of genes up to 100. CATdb gives an easy access to the complete description of experiments with a picture of the experiment design
Correlations in the orientations of galaxy clusters
The relative orientation of clusters' major elongation axes and clusters'
angular momentum is studied using a large N-body simulation in a box of 500
Mpc/h base length for a standard LambdaCDM model. Employing the technique of
mark correlation functions, we successfully separated the correlations in the
orientation from the well known clustering signal traced by the two-point
correlation function. The correlations in the orientation are highly
significant for our sample of 3000 clusters. We found an alignment of
neighboring clusters, i.e. an enhanced probability of the major elongation axes
of neighboring cluster pairs to be in parallel with each other. At 10 Mpc/h
separation the amplitude of this signal is ~10% above the value expected from
random orientations, and it vanishes on scales larger than 15 Mpc/h. The
``filamentary'' alignment between clusters' major elongation axes and the lines
pointing towards neighboring clusters shows even stronger deviations from
random orientation, which can be detected out to scales of 100 Mpc/h, both in
2D and 3D analyses. Similarly, strong correlations of the angular momentum were
seen. Also a clear signal in the scalar correlation of the absolute value of
the angular momentum, the spin parameter and the mass was found. They extend up
to 50 Mpc/h and have an amplitude of 40%, 15%, and 10% above a random
distribution at 10 Mpc/h separation, respectively.Comment: 10 pages, 10 figures, A&A, accepted 28/08/0
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