5,075 research outputs found
The Mass distribution of the Cluster 0957+561 from Gravitational Lensing
Multiply gravitationally lensed objects with known time delays can lead to
direct determinations of H independent of the distance ladder if the mass
distribution of the lens is known. Currently, the double QSO 0957+561 is the
only lensed object with a precisely known time delay. The largest remaining
source of systematic error in the H determination results from uncertainty
in the mass distribution of the lens which is comprised of a massive galaxy
(G1) and the cluster in which it resides.
We have obtained V-band CCD images from CFHT in order to measure the mass
distribution in the cluster from its gravitional distorting effect on the
appearance of background galaxes. We use this data to constuct a
two-dimensional mass map of the field. A mass peak is detected at the
level, offset from, but consistent with, the position of G1. Simple
tests reveal no significant substructure and the mass distribution is
consistent with a spherical cluster. The peak in the number density map of
bright galaxies is offset from G1 similarly to the mass peak.
We constructed an azimuthally averaged mass profile centered on G1 out to 2
\arcmin ( kpc). It is consistent with an isothermal mass
distribution with a small core (r_c \approx 5 \arcsec = 17 h^{-1} kpc). The
inferred mass within 1 Mpc is consistent with the dynamical mass estimate but
higher than the upper limits from a ROSAT X-ray study.
We discuss implications for H in a future paper.Comment: LaTeX, aas version 4 macros. Calibration error in original led to
overestimate of cluster mass. Seven out of twelve figures included. Complete
paper is available at: http://www.astro.lsa.umich.edu:80/users/philf
The Mass distribution of the Most Luminous X-ray Cluster RXJ1347.5-1145 from Gravitational Lensing
Galaxy cluster mass distribution are potentially useful probes of
and the nature of the dark matter. Large clusters will distort the observed
shapes of background galaxies through gravitational lensing allowing the
measurement of the cluster mass distributions. In this paper we describe weak
statistical lensing measurements of the most luminous X-ray cluster known,
RXJ1347.5-1145 at z=0.45. We detect a shear signal in the background galaxies
at a signal-to-noise ratio of 7.5 in the radial range kpc. A mass map of the cluster reveals an 11 peak in the
cluster mass distribution consistent with the position of the central dominant
galaxy and 3 evidence for the presence of a subcluster at a projected
radius of 1.3 - 1.7 h^{-1} Mpc from the cluster center. In the range kpc mass traces light, and the azimuthally averaged cluster
mass and light profiles are consistent with singular isothermal spheres with
M(r<1 Mpc) = . Assuming an isotropic
velocity distribution function, the implied velocity dispersion is . The rest-frame mass-to-light ratio is . The lensing mass estimate is almost twice as high as
a previously determined X-ray mass estimate.Comment: 21 Pages LaTeX, AASTEX version 4 macros, Accepted for publication in
the AJ. 8 of 12 figures included, full paper at
http://www.astro.lsa.umich.edu:80/users/philf/www/papers/list.htm
Improved Parameters and New Lensed Features for Q0957+561 from WFPC2 Imaging
New HST WFPC2 observations of the lensed double QSO 0957+561 will allow
improved constraints on the lens mass distribution and hence will improve the
derived value of H. We first present improved optical positions and
photometry for the known components of this lens. The optical separation
between the A and B quasar images agrees with VLBI data at the 10 mas level,
and the optical center of the primary lensing galaxy G1 coincides with the VLBI
source G' to within 10 mas. The best previous model for this lens (Grogin and
Narayan 1996) is excluded by these data and must be reevaluated.
Several new resolved features are found within 10\arcsec of G1, including an
apparent fold arc with two bright knots. Several other small galaxies are
detected, including two which may be multiple images of each other. We present
positions and crude photometry of these objects.Comment: 7 pages including 2 postscript figures, LaTeX, emulateapj style. Also
available at
http://www.astro.lsa.umich.edu:80/users/philf/www/papers/list.htm
Detection of Lens Candidates for the Double QSO Q2345+007
Luminous objects associated with the 7.06\arcsec\ separation double quasar
Q2345+007 have, until now, escaped detection. In this letter we present the
results of the deepest known imaging of the region surrounding the quasar. The
total exposure times were 47600 seconds in B (101 frames) and 32160 seconds
in R (82 frames). The frames came from CFHT, CTIO, and KPNO. We detect a B
= 25.0 mag galaxy (B -- R = 0.5 mag) in close proximity to the fainter QSO
image, possibly at given by several absorption features in the QSO
spectra. Furthermore, there is a 2.9 enhancement in the number density
of faint galaxies ( B , B R ) near the
quasar and another 3.1 enhancement further away. These discoveries
support the hypothesis that Q2345+007 is being lensed by one or more distant
mass concentrations and may imply that compact ``clusters'' already exist at
early epochs. We discuss several lens models for the system and the
cosmological implications.Comment: (uuencoded compressed postscript
Polymorphisms in genes related to the hypothalamic-pituitary-adrenal axis and antidepressant response â Systematic review
Objective: Around 50% of depressed patients do not respond to antidepressants. Evidence from familial studies suggests a genetic component to this. This study investigated whether patients with polymorphisms in genes related to the hypothalamic-pituitary-adrenal (HPA) axis were less likely to respond to antidepressants.
Method: EMBASE, MEDLINE, PsycINFO, and the Cochrane Library were searched. Inclusionary criteria were: 1) patients with depression, 2) study of HPA axis-related candidate genes, 3) at least four weeks of antidepressants, and 4) assessment of depressive symptoms dividing patients into non-responders and responders.
Results: Nineteen studies were identified. Non-responders and responders did not differ in single nucleotide polymorphisms (SNPs) in genes encoding arginine vasopressin. Findings were equivocal regarding genes encoding the FK506 binding protein 5 and glucocorticoid and mineralocorticoid receptors. Specific SNPs and haplotypes within genes related to corticotropin-releasing hormone (CRHBP, CRHR1) and melanocortins (POMC) predicted non-responder status.
Conclusions: Replication studies and additional investigations exploring gene x environment and drug x environment interactions are necessary before pharmacological treatments may be adjusted based on a patientâs genetic profile
Consequences Of Fully Dressing Quark-Gluon Vertex Function With Two-Point Gluon Lines
We extend recent studies of the effects of quark-gluon vertex dressing upon
the solutions of the Dyson-Schwinger equation for the quark propagator. A
momentum delta function is used to represent the dominant infrared strength of
the effective gluon propagator so that the resulting integral equations become
algebraic. The quark-gluon vertex is constructed from the complete set of
diagrams involving only 2-point gluon lines. The additional diagrams, including
those with crossed gluon lines, are shown to make an important contribution to
the DSE solutions for the quark propagator, because of their large color
factors and the rapid growth in their number
Childhood trauma associated with increased post-awakening cortisol in major depressive disorder
Background: Enhanced post-awakening cortisol may serve as a biological marker for individuals with major depressive disorder. However, studies comparing post-awakening cortisol between patients with major depressive disorder (MDD) and healthy controls have produced conflicting findings. The aim of this study was to investigate whether this inconsistency could be due to the effects of childhood trauma.
Methods: A total of N = 112 patients with MDD and healthy controls were divided into four groups according to the presence of childhood trauma. Saliva samples were collected at awakening and 15, 30, 45, and 60 min later. The total cortisol output and the cortisol awakening response (CAR) were calculated.
Results: The total post-awakening cortisol output was significantly higher in patients with MDD as compared to healthy controls, but only in those individuals reporting childhood trauma. The four groups did not differ regarding the CAR.
Conclusions: Elevated post-awakening cortisol in MDD may be confined to those with a history of early life stress. Tailoring and/or augmenting of currently available treatments may be required to meet the specific needs of this population
Nonperturbative structure of the quark-gluon vertex
The complete tensor structure of the quark--gluon vertex in Landau gauge is
determined at two kinematical points (`asymmetric' and `symmetric') from
lattice QCD in the quenched approximation. The simulations are carried out at
beta=6.0, using a mean-field improved Sheikholeslami-Wohlert fermion action,
with two quark masses ~ 60 and 115 MeV. We find substantial deviations from the
abelian form at the asymmetric point. The mass dependence is found to be
negligible. At the symmetric point, the form factor related to the
chromomagnetic moment is determined and found to contribute significantly to
the infrared interaction strength.Comment: 16 pages, 11 figures, JHEP3.cl
OGFOD1 catalyzes prolyl hydroxylation of RPS23 and is involved in translation control and stress granule formation
2-Oxoglutarate (2OG) and Fe(II)-dependent oxygenase domain-containing protein 1 (OGFOD1) is predicted to be a conserved 2OG oxygenase, the catalytic domain of which is related to hypoxia-inducible factor prolyl hydroxylases. OGFOD1 homologs in yeast are implicated in diverse cellular functions ranging from oxygen-dependent regulation of sterol response genes (Ofd1, Schizosaccharomyces pombe) to translation termination/mRNA polyadenylation (Tpa1p, Saccharomyces cerevisiae). However, neither the biochemical activity of OGFOD1 nor the identity of its substrate has been defined. Here we show that OGFOD1 is a prolyl hydroxylase that catalyzes the posttranslational hydroxylation of a highly conserved residue (Pro-62) in the small ribosomal protein S23 (RPS23). Unusually OGFOD1 retained a high affinity for, and forms a stable complex with, the hydroxylated RPS23 substrate. Knockdown or inactivation of OGFOD1 caused a cell type-dependent induction of stress granules, translational arrest, and growth impairment in a manner complemented by wild-type but not inactive OGFOD1. The work identifies a human prolyl hydroxylase with a role in translational regulation
VLT multi-epoch radial velocity survey toward NGC 6253. Analysis of three transiting planetary candidates
We measured the radial velocity of 139 stars in the region of NGC 6253,
discussing cluster's membership and binarity in this sample, complementing our
analysis with photometric, proper motion, and radial velocity data available
from previous studies of this cluster, and analyzing three planetary transiting
candidates we found in the field of NGC 6253. Spectra were obtained with the
UVES and GIRAFFE spectrographs at the VLT, during three epochs in August 2008.
The mean radial velocity of the cluster is -29.11+/-0.85 km/s. Using both
radial velocities and proper motions we found 35 cluster's members, among which
12 are likely cluster's close binary systems. One star may have a sub-stellar
companion, requiring a more intensive follow-up. Our results are in good
agreement with past radial velocity and photometric measurements. Furthermore,
using our photometry, astrometry and spectroscopy we identified a new sub-giant
branch eclipsing binary system, member of the cluster. The cluster's close
binary frequency at 29% +/- 9% (34% +/-10% once including long period
binaries), appears higher than the field binary frequency equal to (22% +/- 5%,
though these estimates are still consistent within the uncertainties. Among the
three transiting planetary candidates the brightest one (V=15.26) is worth to
be more intensively investigated with higher percision spectroscopy. We
discussed the possibility to detect sub-stellar companions (brown dwarfs and
planets) with the radial velocity technique (both with UVES/GIRAFFE and HARPS)
around turn-off stars of old open clusters [abridged].Comment: 25 pages, 18 figures, 8 tables. Accepted for publication in A&
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