55 research outputs found
A Merger Scenario for the Dynamics of Abell 665
We present new redshift measurements for 55 galaxies in the vicinity of the
rich galaxy cluster Abell 665. When combined with results from the literature,
we have good velocity measurements for a sample of 77 confirmed cluster members
from which we derive the cluster's redshift z=0.1829 +/- 0.0005 and
line-of-sight velocity dispersion of 1390 +/- 120 km/s. Our analysis of the
kinematical and spatial data for the subset of galaxies located within the
central 750 kpc reveals only subtle evidence for substructure and
non-Gaussianity in the velocity distribution. We find that the brightest
cluster member is not moving significantly relative to the other galaxies near
the center of the cluster. On the other hand, our deep ROSAT high resolution
image of A665 shows strong evidence for isophotal twisting and centroid
variation, thereby confirming previous suggestions of significant substructure
in the hot X-ray--emitting intracluster gas. In light of this evident
substructure, we have compared the optical velocity data with N-body
simulations of head-on cluster mergers. We find that a merger of two similar
mass subclusters (mass ratios of 1:1 or 1:2) seen close to the time of
core-crossing produces velocity distributions that are consistent with that
observed.Comment: 30 pages and 7 figures. Accepted by the Astrophysical Journal Full
resoultion figures 1 and 3 available in postscript at
http://www.physics.rutgers.edu/~percy/A665paper.htm
Inflammasome activation during spontaneous preterm labor with intraĂą amniotic infection or sterile intraĂą amniotic inflammation
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146295/1/aji13049.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146295/2/aji13049_am.pd
The amniotic fluid cell-free transcriptome in spontaneous preterm labor
The amniotic fluid (AF) cell-free RNA was shown to reflect physiological and pathological processes in pregnancy, but its value in the prediction of spontaneous preterm delivery is unknown. Herein we profiled cell-free RNA in AF samples collected from women who underwent transabdominal amniocentesis after an episode of spontaneous preterm labor and subsequently delivered within 24 h (n = 10) or later (n = 28) in gestation. Expression of known placental single-cell RNA-Seq signatures was quantified in AF cell-free RNA and compared between the groups. Random forest models were applied to predict time-to-delivery after amniocentesis. There were 2385 genes differentially expressed in AF samples of women who delivered within 24 h of amniocentesis compared to gestational age-matched samples from women who delivered after 24 h of amniocentesis. Genes with cell-free RNA changes were associated with immune and inflammatory processes related to the onset of labor, and the expression of placental single-cell RNA-Seq signatures of immune cells was increased with imminent delivery. AF transcriptomic prediction models captured these effects and predicted delivery within 24 h of amniocentesis (AUROC = 0.81). These results may inform the development of biomarkers for spontaneous preterm birth
Composite Luminosity Functions Based on the Sloan Digital Sky Survey "Cut & Enhance" Galaxy Cluster Catalog
We present here results on the composite luminosity functions of galaxies in
the clusters of galaxies selected from the SDSS Cut and Enhance cluster catalog
(CE; Goto et al. 2001). We construct the composite luminosity function in the
five SDSS bands, u,g,r,i and z, using 204 CE clusters ranging from z=0.02 to
z=0.25. We use photometric redshifts to construct composite luminosity
functions. The robustness of the weighting scheme was tested using Monte Carlo
simulation. We find the slope of composite LFs become flatter toward redder
color band. Comparing with field LFs of SDSS (Blanton et al. 2001), cluster LFs
have brighter characteristic magnitude and flatter slopes in g, r, i and z
bands. These results are consistent with the hypothesis that the cluster LF has
two distinct underlying populations i.e. the bright end of the LF is dominated
by bright early types that follow a gaussian--like luminosity distribution,
while the faint--end of the cluster LF is a steep power--law like function
dominated by star--forming (bluer) galaxies. We also study the composite
luminosity functions for early--type and late--type galaxies using profile
fits, a concentration parameter and u-r color to classify galaxy morphology.
The strong dependence of LF on galaxy morphology is found.The faint end slope
of the LF is always flatter for early--type galaxies than late--type regardless
of passband and methodology. These results are consistent with the hypothesis
that the cluster region are dominated by bright elliptical galaxies.Comment: 21 pages, 5 figures, PASJ, 54, 515, miner typos fixe
The cytokine network in women with an asymptomatic short cervix and the risk of preterm delivery
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138402/1/aji12686_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138402/2/aji12686.pd
Disorders of placental villous maturation are present in one-third of cases with spontaneous preterm labor
Spontaneous preterm labor is an obstetrical syndrome accounting for approximately 65-70% of preterm births, the latter being the most frequent cause of neonatal death and the second most frequent cause of death in children less than five years of age worldwide. The purpose of this study was to determine and compare to uncomplicated pregnancies (1) the frequency of placental disorders of villous maturation in spontaneous preterm labor; (2) the frequency of other placental morphologic characteristics associated with the preterm labor syndrome; and (3) the distribution of these lesions according to gestational age at delivery and their severity. A case-control study of singleton pregnant women was conducted that included (1) uncomplicated pregnancies (controls, n=944) and (2) pregnancies with spontaneous preterm labor (cases, n=438). All placentas underwent histopathologic examination. Patients with chronic maternal diseases (e.g., chronic hypertension, diabetes mellitus, renal disease, thyroid disease, asthma, autoimmune disease, and coagulopathies), fetal malformations, chromosomal abnormalities, multifetal gestation, preeclampsia, eclampsia, preterm prelabor rupture of the fetal membranes, gestational hypertension, gestational diabetes mellitus, and HELLP (hemolysis, elevated liver enzymes and low platelet count) syndrome were excluded from the study. Compared to the controls, the most prevalent placental lesions among the cases were the disorders of villous maturation (31.8% [106/333] including delayed villous maturation 18.6% [62/333] vs. 1.4% [6/442], q\u3c0.0001, prevalence ratio 13.7; and accelerated villous maturation 13.2% [44/333] vs. 0% [0/442], q\u3c0.001). Other lesions in decreasing order of prevalence included hypercapillarized villi (15.6% [68/435] vs. 3.5% [33/938], q\u3c0.001, prevalence ratio 4.4); nucleated red blood cells (1.1% [5/437] vs. 0% [0/938], q\u3c0.01); chronic inflammatory lesions (47.9% [210/438] vs. 29.9% [282/944], q\u3c0.0001, prevalence ratio 1.6); fetal inflammatory response (30.1% [132/438] vs. 23.2% [219/944], q\u3c0.05, prevalence ratio 1.3); maternal inflammatory response (45.5% [195/438] vs. 36.1% [341/944], q\u3c0.01, prevalence ratio 1.2); and maternal vascular malperfusion (44.5% [195/438] vs. 35.7% [337/944], q\u3c0.01, prevalence ratio 1.2). Accelerated villous maturation did not show gestational age-dependent association with any other placental lesion while delayed villous maturation showed a gestational age-dependent association with acute placental inflammation (q-value=0.005). Disorders of villous maturation are present in nearly one-third of the cases of spontaneous preterm labor
The Environment of Passive Spiral Galaxies in the SDSS
In previous work on galaxy clusters, several authors reported a discovery of
an unusual population of galaxies, which have spiral morphologies, but do not
show any star formation activity. These galaxies are called ``passive
spirals'', and have been interesting since it has been difficult to understand
the existence of such galaxies. Using a volume limited sample (0.05<z<0.1 and
Mr<-20.5; 25813 galaxies) of the Sloan Digital Sky Survey data, we have found
73 (0.280.03%) passive spiral galaxies and studied their environments. It
is found that passive spiral galaxies live in local galaxy density 1-2
Mpc and 1-10 cluster-centric virial radius. Thus the origins of passive
spiral galaxies are likely to be cluster related. These characteristic
environments coincide with the previously reported environment where galaxy
star formation rate suddenly declines and the so-called morphology-density
relation turns. It is likely that the same physical mechanism is responsible
for all of these observational results. The existence of passive spiral
galaxies suggests that a physical mechanism that works calmly is preferred to
dynamical origins such as major merger/interaction since such a mechanism can
destroy spiral arm structures. Compared with observed cluster galaxy evolution
such as the Butcher-Oemler effect and the morphological Butcher-Oemler effect,
passive spiral galaxies are likely to be a galaxy population in transition
between red, elliptical/S0 galaxies in low redshift clusters and blue, spiral
galaxies more numerous in higher redshift clusters.Comment: 31 pages, 13 figures, PASJ in pres
Catalog of Galactic Beta Cephei Stars
We present an extensive and up-to-date catalog of Galactic Beta Cephei stars.
This catalog is intended to give a comprehensive overview of observational
characteristics of all known Beta Cephei stars. 93 stars could be confirmed to
be Beta Cephei stars. For some stars we re-analyzed published data or conducted
our own analyses. 61 stars were rejected from the final Beta Cephei list, and
77 stars are suspected to be Beta Cephei stars. A list of critically selected
pulsation frequencies for confirmed Beta Cephei stars is also presented. We
analyze the Beta Cephei stars as a group, such as the distributions of their
spectral types, projected rotational velocities, radial velocities, pulsation
periods, and Galactic coordinates. We confirm that the majority of these stars
are multiperiodic pulsators. We show that, besides two exceptions, the Beta
Cephei stars with high pulsation amplitudes are slow rotators. We construct a
theoretical HR diagram that suggests that almost all 93 Beta Cephei stars are
MS objects. We discuss the observational boundaries of Beta Cephei pulsation
and their physical parameters. We corroborate that the excited pulsation modes
are near to the radial fundamental mode in frequency and we show that the mass
distribution of the stars peaks at 12 solar masses. We point out that the
theoretical instability strip of the Beta Cephei stars is filled neither at the
cool nor at the hot end and attempt to explain this observation
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