315 research outputs found
Glucocorticoids are lower at delivery in maternal, but not cord blood of obese pregnancies
Abstract Glucocorticoids are vital for lung maturation. We previously showed that cortisol is lower in obese pregnancy. Whether this is maintained at delivery is unknown but is clinically relevant as maternal and cord blood cortisol levels are correlated and offspring of obese are more likely to need neonatal respiratory support. We hypothesized that glucocorticoids are lower in maternal and cord blood at delivery in obese pregnancies. Glucocorticoids (cortisol and corticosterone) and their inactive versions (cortisone and 11-dehydrocorticosterone) were measured by LC-MS/MS in maternal and cord plasma from 259 Caucasian women at delivery (BMI 18–55 kg/m2). Analyses adjusted for labour status, delivery mode, offspring gender, birthweight and gestational age. Cortisol and corticosterone were significantly higher in maternal than cord blood. Inactive versions were significantly higher in cord than maternal blood. Increased maternal BMI associated with lower maternal cortisol, corticosterone and 11-dehydrocorticosterone. Despite significant positive correlations between maternal and cord blood glucocorticoid levels, increased maternal BMI was not associated with lower cord blood glucocorticoid levels. Conditions at delivery may overcome any potential negative effects of low maternal glucocorticoids on the fetus in the short-term. This may not preclude the longer-term effects of fetal exposure to lower glucocorticoid levels during obese pregnancy
Precision Mass Measurements of 129-131Cd and Their Impact on Stellar Nucleosynthesis via the Rapid Neutron Capture Process
Masses adjacent to the classical waiting-point nuclide 130Cd have been
measured by using the Penning- trap spectrometer ISOLTRAP at ISOLDE/CERN. We
find a significant deviation of over 400 keV from earlier values evaluated by
using nuclear beta-decay data. The new measurements show the reduction of the N
= 82 shell gap below the doubly magic 132Sn. The nucleosynthesis associated
with the ejected wind from type-II supernovae as well as from compact object
binary mergers is studied, by using state-of-the-art hydrodynamic simulations.
We find a consistent and direct impact of the newly measured masses on the
calculated abundances in the A = 128 - 132 region and a reduction of the
uncertainties from the precision mass input data
The XMM-Newton Wide Angle Survey (XWAS): the X-ray spectrum of type-1 AGN
We discuss the broad band X-ray properties of one of the largest samples of
X-ray selected type-1 AGN to date (487 objects in total), drawn from the
XMM-Newton Wide Angle Survey. The objects cover 2-10 keV luminosities from
~10^{42}-10^{45} erg s^{-1} and are detected up to redshift ~4. We constrain
the overall properties of the broad band continuum, soft excess and X-ray
absorption, along with their dependence on the X-ray luminosity and redshift
and we discuss the implications for models of AGN emission. We constrained the
mean spectral index of the broad band X-ray continuum to =1.96+-0.02
with intrinsic dispersion sigma=0.27_{-0.02}^{+0.01}. The continuum becomes
harder at faint fluxes and at higher redshifts and luminosities. The dependence
of Gamma with flux is likely due to undetected absorption rather than to
spectral variation. We found a strong dependence of the detection efficiency of
objects on the spectral shape which can have a strong impact on the measured
mean continuum shapes of sources at different redshifts and luminosities. We
detected excess absorption in ~3% of our objects, with column densities ~a few
x10^{22} cm^{-2}. The apparent mismatch between the optical classification and
X-ray properties of these objects is a challenge for the standard AGN
unification model. We found that the fraction of objects with detected soft
excess is ~36%. Using a thermal model, we constrained the soft excess mean
temperature and intrinsic dispersion to ~100 eV and sigma~34 eV. The origin
of the soft excess as thermal emission from the accretion disk or Compton
scattered disk emission is ruled out on the basis of the temperatures detected
and the lack of correlation of the measured temperature with the X-ray
luminosity (abridged).Comment: 13 pages, 24 figures, Accepted for publication in Astronomy and
Astrophysic
CAIXA: a Catalogue of AGN In the XMM-Newton Archive II. Multiwavelength correlations
We presented CAIXA, a Catalogue of AGN in the XMM-Newton Archive, in a
companion paper. Here, a systematic search for correlations between the X-ray
spectral properties and the multiwavelength data was performed for the sources
in CAIXA. All the significant (>99.9% confidence level) correlations are
discussed along with their physical implications on current models of AGN. Two
main correlations are discussed in this paper: a) a very strong
anti-correlation between the FWHM of the H optical line and the ratio
between the soft and the hard X-ray luminosity. Although similar
anti-correlations between optical line width and X-ray spectral steepness have
already been discussed in the literature (see e.g., Laor et al. 1994, Boller et
al. 1996, Brandt et al. 1997), we consider the formulation we present in this
paper is more fundamental, as it links model-independent quantities. Coupled
with a strong anti-correlation between the V to hard X-ray flux ratio and the
H FHWM, it supports scenarios for the origin of the soft excess in AGN,
which require strong suppression of the hard X-ray emission; b) a strong (and
expected) correlation between the X-ray luminosity and the black hole mass. Its
slope, flatter than 1, is consistent with Eddington ratio-dependent bolometric
corrections, such as that recently proposed by Vasudevan & Fabian (2009).
Moreover, we critically review through various statistical tests the role that
distance biases play in the strong radio to X-ray luminosity correlation found
in CAIXA and elsewhere; we conclude that only complete, unbiased samples (such
as that recently published by Behar & Laor, 2008) should be used to draw
observational constraints on the origin of radio emission in radio-quiet AGN.Comment: 12 pages, 11 figures, accepted for publication in Astronomy and
Astrophysics; two figures erroneously attached by astroph to the paper were
remove
Investigating the complex X-ray spectrum of a broad-line 2MASS red quasar: XMM-Newton observation of FTM 0830+3759
We report results from a 50 ks XMM-Newton observation of the dust-reddened
broad-line quasar FTM 0830+3759 (z=0.413) selected from the FIRST/2MASS Red
Quasar survey. For this AGN, a very short 9 ks Chandra exposure had suggested a
feature-rich X-ray spectrum and HST images revealed a very disturbed host
galaxy morphology. Contrary to classical, optically-selected quasars, the X-ray
properties of red (i.e. with J-Ks> 1.7 and R-Ks> 4) broad line quasars are
still quite unexplored, although there is a growing consensus that, due to
moderate obscuration, these objects can offer a unique view of spectral
components typically swamped by the AGN light in normal, blue quasars. The
XMM-Newton observation discussed here has definitely confirmed the complexity
of the X-ray spectrum revealing the presence of a cold (or mildly-ionized)
absorber with Nh ~10^{22} cm^-2 along the line of sight to the nucleus and a
Compton reflection component accompanied by an intense Fe K emission line in
this quasar with a Lum(2-10) ~5 x 10^{44} erg/s. A soft-excess component is
also required by the data. The match between the column density derived by our
spectral analysis and that expected on the basis of reddening due to the dust
suggests the possibility that both absorptions occur in the same medium. FTM
0830+3759 is characterized by an extinction/absorption-corrected
X-ray-to-optical flux ratio alphaox = -2.3, that is steeper than expected on
the basis of its UV luminosity. These findings indicate that the X-ray
properties of FTM 0830+3759 differs from those typically observed for
optically-selected broad line quasars with comparable hard X-ray luminosity.Comment: Accepted for publication in Ap
Antenatal dexamethasone treatment transiently alters diastolic function in the mouse fetal heart
Multi-epoch X-ray observations of the Seyfert 1.2 galaxy Mrk 79: bulk motion of the illuminating X-ray source
Multi-epoch X-ray spectroscopy (0.3-25 keV) of the Seyfert 1.2 galaxy Mrk 79
(UGC 3973) spanning nearly eight years and a factor of three in broadband flux
are analysed. The data are obtained at seven epochs with either XMM-Newton or
Suzaku. Comparison with contemporaneous RXTE monitoring indicate that all flux
states of Mrk 79 are represented by the data. The spectra are fitted in a
self-consistent manner adopting a power law and ionised reflection to describe
the broadband continuum. Modification of the spectra by a distant photoionised
medium, seen predominantly in emission, are also included. Under the assumption
that the inner disk is at the innermost stable circular orbit, our blurred
reflection models give a spin of a = 0.7+/-0.1. The reflection component in
each spectrum is weaker than predicted by simple reflection models. If the
illuminating X-ray emission is produced by flares above the disk that move at
mildly relativistic velocities, however, diminished reflection is expected.
Light bending due to strong gravity near black holes can influence how the
illuminating and reflected flux are observed; variations in Mrk 79 do not
suggest that light bending is important in this source.Comment: 13 pages. Accepted for publication in MNRA
Quantitative analysis of 11-dehydrocorticosterone and corticosterone for preclinical studies by liquid chromatography triple quadrupole mass spectrometry
A Quasar Catalog with Simultaneous UV, Optical and X-ray Observations by Swift
We have compiled a catalog of optically-selected quasars with simultaneous
observations in UV/optical and X-ray bands by the Swift Gamma Ray Burst
Explorer. Objects in this catalog are identified by matching the Swift
pointings with the Sloan Digital Sky Survey Data Release 5 quasar catalog. The
final catalog contains 843 objects, among which 637 have both UVOT and XRT
observations and 354 of which are detected by both instruments. The overall
X-ray detection rate is ~60% which rises to ~85% among sources with at least 10
ks of XRT exposure time. We construct the time-averaged spectral energy
distribution for each of the 354 quasars using UVOT photometric measurements
and XRT spectra. From model fits to these SEDs, we find that the big blue bump
contributes about 0.3 dex to the quasar luminosity. We re-visit the
alpha_ox-L_uv relation by selecting a clean sample with only type 1 radio-quiet
quasars; the dispersion of this relation is reduced by at least 15% compared to
studies that use non-simultaneous UV/optical and X-ray data. We only found a
weak correlation between L/L_Edd and alpha_uv. We do not find significant
correlations between alpha_x and alpha_ox, alpha_ox and alpha_uv, and alpha_x
and Log L(0.3-10 keV). The correlations between alpha_uv and alpha_x, alpha_ox
and alpha_x, alpha_ox and alpha_uv, L/L_Edd and alpha_x, and L/L_Edd and
alpha_ox are stronger amongst low-redshift quasars, indicating that these
correlations are likely driven by the changes of SED shape with accretion
state.Comment: 63 pages, 22 figures, accepted by ApJ
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