247 research outputs found
Maternal and neonatal outcomes by labor onset type and gestational age.
OBJECTIVE: We sought to determine maternal and neonatal outcomes by labor onset type and gestational age.
STUDY DESIGN: We used electronic medical records data from 10 US institutions in the Consortium on Safe Labor on 115,528 deliveries from 2002 through 2008. Deliveries were divided by labor onset type (spontaneous, elective induction, indicated induction, unlabored cesarean). Neonatal and maternal outcomes were calculated by labor onset type and gestational age.
RESULTS: Neonatal intensive care unit admissions and sepsis improved with each week of gestational age until 39 weeks (P \u3c .001). After adjusting for complications, elective induction of labor was associated with a lower risk of ventilator use (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.28-0.53), sepsis (OR, 0.36; 95% CI, 0.26-0.49), and neonatal intensive care unit admissions (OR, 0.52; 95% CI, 0.48-0.57) compared to spontaneous labor. The relative risk of hysterectomy at term was 3.21 (95% CI, 1.08-9.54) with elective induction, 1.16 (95% CI, 0.24-5.58) with indicated induction, and 6.57 (95% CI, 1.78-24.30) with cesarean without labor compared to spontaneous labor.
CONCLUSION: Some neonatal outcomes improved until 39 weeks. Babies born with elective induction are associated with better neonatal outcomes compared to spontaneous labor. Elective induction may be associated with an increased hysterectomy risk
Measuring our universe from galaxy redshift surveys
Galaxy redshift surveys have achieved significant progress over the last
couple of decades. Those surveys tell us in the most straightforward way what
our local universe looks like. While the galaxy distribution traces the bright
side of the universe, detailed quantitative analyses of the data have even
revealed the dark side of the universe dominated by non-baryonic dark matter as
well as more mysterious dark energy (or Einstein's cosmological constant). We
describe several methodologies of using galaxy redshift surveys as cosmological
probes, and then summarize the recent results from the existing surveys.
Finally we present our views on the future of redshift surveys in the era of
Precision Cosmology.Comment: 82 pages, 31 figures, invited review article published in Living
Reviews in Relativity, http://www.livingreviews.org/lrr-2004-
The VIMOS-VLT Deep Survey. The dependence of clustering on galaxy stellar mass at z~1
Aims: We use the VVDS-Deep first-epoch data to measure the dependence of
galaxy clustering on galaxy stellar mass, at z~0.85.
Methods: We measure the projected correlation function wp(rp) for sub-samples
with 0.5<z<1.2 covering different mass ranges between 10^9 and 10^11 Msun. We
quantify in detail the observational selection biases using 40 mock catalogues
built from the Millennium run and semi-analytic models.
Results: Our simulations indicate that serious incompleteness in mass is
present only for log(M/Msun)<9.5. In the mass range log(M/Msun)=[9.0-9.5], the
photometric selection function of the VVDS misses 2/3rd of the galaxies. The
sample is virtually 100% complete above 10^10 Msun. We present the first direct
evidence for a clear dependence of clustering on the galaxy stellar mass at
z~0.85. The clustering length increases from r0 ~ 2.76 h^-1 Mpc for galaxies
with mass M>10^9 Msun to r0 ~ 4.28 h^-1 Mpc for galaxies more massive than
10^10.5 Msun. At the same time, the slope increases from ~ 1.67 to ~ 2.28.
A comparison of the observed wp(rp) to local measurements by the SDSS shows
that the evolution is faster for objects less massive than ~10^10.5 Msun. This
is interpreted as a higher dependence on redshift of the linear bias b_L for
the more massive objects. While for the most massive galaxies b_L decreases
from 1.5+/-0.2 at z~0.85 to 1.33+/-0.03 at z~0.15, the less massive population
maintains a virtually constant value b_L~1.3. This result is in agreement with
a scenario in which more massive galaxies formed at high redshift in the
highest peaks of the density field, while less massive objects form at later
epochs from the more general population of dark-matter halos.Comment: 13 pages, 10 figures, accepted in A&
The VIMOS-VLT Deep Survey: Evolution in the Halo Occupation Number since z 1
We model the evolution of the mean galaxy occupation of dark-matter halos
over the range , using the data from the VIMOS-VLT Deep Survey
(VVDS). The galaxy projected correlation function was computed for a
set of luminosity-limited subsamples and fits to its shape were obtained using
two variants of Halo Occupation Distribution models. These provide us with a
set of best-fitting parameters, from which we obtain the average mass of a halo
and average number of galaxies per halo. We find that after accounting for the
evolution in luminosity and assuming that we are largely following the same
population, the underlying dark matter halo shows a growth in mass with
decreasing redshift as expected in a hierarchical structure formation scenario.
Using two different HOD models, we see that the halo mass grows by 90% over the
redshift interval z=[0.5,1.0]. This is the first time the evolution in halo
mass at high redshifts has been obtained from a single data survey and it
follows the simple form seen in N-body simulations with , and . This provides evidence for a rapid accretion
phase of massive halos having a present-day mass , with a merger event occuring between redshifts of 0.5
and 1.0. Futhermore, we find that more luminous galaxies are found to occupy
more massive halos irrespectively of the redshift. Finally, the average number
of galaxies per halo shows little increase from redshift z 1.0 to z
0.5, with a sharp increase by a factor 3 from z 0.5 to z 0.1,
likely due to the dynamical friction of subhalos within their host halos.Comment: 14 pages, 6 figures, 5 tables. MNRAS accepted
Comparison of the VIMOS-VLT Deep Survey with the Munich semi-analytical model - I. Magnitude counts, redshift distribution, colour bimodality, and galaxy clustering
This paper presents a detailed comparison between high-redshift observations
from the VIMOS-VLT Deep Survey (VVDS) and predictions from the Munich
semi-analytical model of galaxy formation. In particular, we focus this
analysis on the magnitude, redshift, and colour distributions of galaxies, as
well as their clustering properties. We constructed 100 quasi-independent mock
catalogues, using the output of the semi-analytical model presented in De Lucia
& Blaizot (2007).We then applied the same observational selection function of
the VVDS-Deep survey, so as to carry out a fair comparison between models and
observations. We find that the semi-analytical model reproduces well the
magnitude counts in the optical bands. It tends, however, to overpredict the
abundance of faint red galaxies, in particular in the i' and z' bands. Model
galaxies exhibit a colour bimodality that is only in qualitative agreement with
the data. In particular, we find that the model tends to overpredict the number
of red galaxies at low redshift and of blue galaxies at all redshifts probed by
VVDS-Deep observations, although a large fraction of the bluest observed
galaxies is absent from the model. In addition, the model overpredicts by about
14 per cent the number of galaxies observed at 0.2<z<1 with I_AB<24. When
comparing the galaxy clustering properties, we find that model galaxies are
more strongly clustered than observed ones at all redshift from z=0.2 to z=2,
with the difference being less significant above z~1. When splitting the
samples into red and blue galaxies, we find that the observed clustering of
blue galaxies is well reproduced by the model, while red model galaxies are
much more clustered than observed ones, being principally responsible for the
strong global clustering found in the model. [abridged]Comment: 15 pages, 14 figures, accepted for publication in A&
A Carpet Cloak Device for Visible Light
We report an invisibility carpet cloak device, which is capable of making an
object undetectable by visible light. The cloak is designed using quasi
conformal mapping and is fabricated in a silicon nitride waveguide on a
specially developed nano-porous silicon oxide substrate with a very low
refractive index. The spatial index variation is realized by etching holes of
various sizes in the nitride layer at deep subwavelength scale creating a local
effective medium index. The fabricated device demonstrates wideband
invisibility throughout the visible spectrum with low loss. This silicon
nitride on low index substrate can also be a general scheme for implementation
of transformation optical devices at visible frequency
Large Scale Structure of the Universe
Galaxies are not uniformly distributed in space. On large scales the Universe
displays coherent structure, with galaxies residing in groups and clusters on
scales of ~1-3 Mpc/h, which lie at the intersections of long filaments of
galaxies that are >10 Mpc/h in length. Vast regions of relatively empty space,
known as voids, contain very few galaxies and span the volume in between these
structures. This observed large scale structure depends both on cosmological
parameters and on the formation and evolution of galaxies. Using the two-point
correlation function, one can trace the dependence of large scale structure on
galaxy properties such as luminosity, color, stellar mass, and track its
evolution with redshift. Comparison of the observed galaxy clustering
signatures with dark matter simulations allows one to model and understand the
clustering of galaxies and their formation and evolution within their parent
dark matter halos. Clustering measurements can determine the parent dark matter
halo mass of a given galaxy population, connect observed galaxy populations at
different epochs, and constrain cosmological parameters and galaxy evolution
models. This chapter describes the methods used to measure the two-point
correlation function in both redshift and real space, presents the current
results of how the clustering amplitude depends on various galaxy properties,
and discusses quantitative measurements of the structures of voids and
filaments. The interpretation of these results with current theoretical models
is also presented.Comment: Invited contribution to be published in Vol. 8 of book "Planets,
Stars, and Stellar Systems", Springer, series editor T. D. Oswalt, volume
editor W. C. Keel, v2 includes additional references, updated to match
published versio
The zCOSMOS Survey. The dependence of clustering on luminosity and stellar mass at z=0.2-1
We study the dependence of galaxy clustering on luminosity and stellar mass
at redshifts z ~ [0.2-1] using the first zCOSMOS 10K sample.
We measure the redshift-space correlation functions xi(rp,pi) and its
projection wp(rp) for sub-samples covering different luminosity, mass and
redshift ranges. We quantify in detail the observational selection biases and
we check our covariance and error estimate techniques using ensembles of
semi-analytic mock catalogues. We finally compare our measurements to the
cosmological model predictions from the mock surveys.
At odds with other measurements, we find a weak dependence of galaxy
clustering on luminosity in all redshift bins explored. A mild dependence on
stellar mass is instead observed. At z~0.7, wp(rp) shows strong excess power on
large scales. We interpret this as produced by large-scale structure dominating
the survey volume and extending preferentially in direction perpendicular to
the line-of-sight. We do not see any significant evolution with redshift of the
amplitude of clustering for bright and/or massive galaxies.
The clustering measured in the zCOSMOS data at 0.5<z<1 for galaxies with
log(M/M_\odot)>=10 is only marginally consistent with predictions from the mock
surveys. On scales larger than ~2 h^-1 Mpc, the observed clustering amplitude
is compatible only with ~1% of the mocks. Thus, if the power spectrum of matter
is LCDM with standard normalization and the bias has no unnatural
scale-dependence, this result indicates that COSMOS has picked up a
particularly rare, ~2-3 sigma positive fluctuation in a volume of ~10^6 h^-1
Mpc^3. These findings underline the need for larger surveys of the z~1 Universe
to appropriately characterize the level of structure at this epoch.Comment: 18 pages, 21 figures, accepted for publication in Astronomy and
Astrophysic
Confirmation of general relativity on large scales from weak lensing and galaxy velocities
Although general relativity underlies modern cosmology, its applicability on
cosmological length scales has yet to be stringently tested. Such a test has
recently been proposed, using a quantity, EG, that combines measures of
large-scale gravitational lensing, galaxy clustering and structure growth rate.
The combination is insensitive to 'galaxy bias' (the difference between the
clustering of visible galaxies and invisible dark matter) and is thus robust to
the uncertainty in this parameter. Modified theories of gravity generally
predict values of EG different from the general relativistic prediction
because, in these theories, the 'gravitational slip' (the difference between
the two potentials that describe perturbations in the gravitational metric) is
non-zero, which leads to changes in the growth of structure and the strength of
the gravitational lensing effect3. Here we report that EG = 0.39 +/- 0.06 on
length scales of tens of megaparsecs, in agreement with the general
relativistic prediction of EG 0.4. The measured value excludes a
model within the tensor-vector-scalar gravity theory, which modifies both
Newtonian and Einstein gravity. However, the relatively large uncertainty still
permits models within f(R) theory, which is an extension of general relativity.
A fivefold decrease in uncertainty is needed to rule out these models.Comment: Submitted version; 13 pages, 2 figures. Accepted version and
supplementary material are available at:
http://www.nature.com/nature/journal/v464/n7286/full/nature08857.html
Chemokine (C-C Motif) Receptor 2 Mediates Dendritic Cell Recruitment to the Human Colon but Is Not Responsible for Differences Observed in Dendritic Cell Subsets, Phenotype, and Function Between the Proximal and Distal Colon.
BACKGROUND & AIMS: Most knowledge about gastrointestinal (GI)-tract dendritic cells (DC) relies on murine studies where CD103+ DC specialize in generating immune tolerance with the functionality of CD11b+/- subsets being unclear. Information about human GI-DC is scarce, especially regarding regional specifications. Here, we characterized human DC properties throughout the human colon. METHODS: Paired proximal (right/ascending) and distal (left/descending) human colonic biopsies from 95 healthy subjects were taken; DC were assessed by flow cytometry and microbiota composition assessed by 16S rRNA gene sequencing. RESULTS: Colonic DC identified were myeloid (mDC, CD11c+CD123-) and further divided based on CD103 and SIRPα (human analog of murine CD11b) expression. CD103-SIRPα+ DC were the major population and with CD103+SIRPα+ DC were CD1c+ILT3+CCR2+ (although CCR2 was not expressed on all CD103+SIRPα+ DC). CD103+SIRPα- DC constituted a minor subset that were CD141+ILT3-CCR2-. Proximal colon samples had higher total DC counts and fewer CD103+SIRPα+ cells. Proximal colon DC were more mature than distal DC with higher stimulatory capacity for CD4+CD45RA+ T-cells. However, DC and DC-invoked T-cell expression of mucosal homing markers (ÎČ7, CCR9) was lower for proximal DC. CCR2 was expressed on circulating CD1c+, but not CD141+ mDC, and mediated DC recruitment by colonic culture supernatants in transwell assays. Proximal colon DC produced higher levels of cytokines. Mucosal microbiota profiling showed a lower microbiota load in the proximal colon, but with no differences in microbiota composition between compartments. CONCLUSIONS: Proximal colonic DC subsets differ from those in distal colon and are more mature. Targeted immunotherapy using DC in T-cell mediated GI tract inflammation may therefore need to reflect this immune compartmentalization
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