1,000 research outputs found
The X-Ray Properties of the Optically Brightest Mini-BAL Quasars from the Sloan Digital Sky Survey
We have compiled a sample of 14 of the optically brightest radio-quiet
quasars (~~17.5 and ~~1.9) in the Sloan Digital Sky Survey
Data Release 5 quasar catalog that have C IV mini-BALs present in their
spectra. X-ray data for 12 of the objects were obtained via a Chandra snapshot
survey using ACIS-S, while data for the other two quasars were obtained from
archival XMM-Newton observations. Joint X-ray spectral analysis shows the
mini-BAL quasars have a similar average power-law photon index
() and level of intrinsic absorption () as non-BMB (neither BAL nor mini-BAL) quasars.
Mini-BAL quasars are more similar to non-BMB quasars than to BAL quasars in
their distribution of relative X-ray brightness (assessed with
). Relative colors indicate mild dust reddening in the
optical spectra of mini-BAL quasars. Significant correlations between
and UV absorption properties are confirmed for a sample
of 56 sources combining mini-BAL and BAL quasars with high signal-to-noise
ratio rest-frame UV spectra, which generally supports models in which X-ray
absorption is important in enabling driving of the UV absorption-line wind. We
also propose alternative parametrizations of the UV absorption properties of
mini-BAL and BAL quasars, which may better describe the broad absorption
troughs in some respects.Comment: ApJ accepted; 21 pages, 11 figures, and 9 table
A Population of X-ray Weak Quasars: PHL 1811 Analogs at High Redshift
We report the results from Chandra and XMM-Newton observations of a sample of
10 type 1 quasars selected to have unusual UV emission-line properties (weak
and blueshifted high-ionization lines; strong UV Fe emission) similar to those
of PHL 1811, a confirmed intrinsically X-ray weak quasar. These quasars were
identified by the Sloan Digital Sky Survey at high redshift (z~2.2); eight are
radio quiet while two are radio intermediate. All of the radio-quiet PHL 1811
analogs are notably X-ray weak by a mean factor of ~13. These sources lack
broad absorption lines and have blue UV/optical continua, suggesting they are
intrinsically X-ray weak. However, their average X-ray spectrum appears to be
harder than those of typical quasars, which may indicate the presence of heavy
intrinsic X-ray absorption. Our radio-quiet PHL 1811 analogs support a
connection between an X-ray weak spectral energy distribution and PHL 1811-like
UV emission lines; this connection provides an economical way to identify X-ray
weak type 1 quasars. The fraction of radio-quiet PHL 1811 analogs in the
radio-quiet quasar population is estimated to be < 1.2%. We have investigated
correlations between relative X-ray brightness and UV emission-line properties
for a sample combining radio-quiet PHL 1811 analogs, PHL 1811, and typical type
1 quasars. These correlation analyses suggest that PHL 1811 analogs may have
extreme wind-dominated broad emission-line regions. Observationally,
radio-quiet PHL 1811 analogs appear to be a subset (~30%) of radio-quiet
weak-line quasars. The existence of a subset of quasars in which
high-ionization "shielding gas" covers most of the BELR, but little more than
the BELR, could potentially unify the PHL 1811 analogs and WLQs. The two
radio-intermediate PHL 1811 analogs are X-ray bright. One of them appears to
have jet-dominated X-ray emission, while the nature of the other remains
unclear.Comment: ApJ accepted; 25 pages, 11 figures and 8 table
Norspermidine is not a self-produced trigger for biofilm disassembly
SummaryFormation of Bacillus subtilis biofilms, consisting of cells encapsulated within an extracellular matrix of exopolysaccharide and protein, requires the polyamine spermidine. A recent study reported that (1) related polyamine norspermidine is synthesized by B. subtilis using the equivalent of the Vibrio cholerae biosynthetic pathway, (2) exogenous norspermidine at 25 μM prevents B. subtilis biofilm formation, (3) endogenous norspermidine is present in biofilms at 50–80 μM, and (4) norspermidine prevents biofilm formation by condensing biofilm exopolysaccharide. In contrast, we find that, at concentrations up to 200 μM, exogenous norspermidine promotes biofilm formation. We find that norspermidine is absent in wild-type B. subtilis biofilms at all stages, and higher concentrations of exogenous norspermidine eventually inhibit planktonic growth and biofilm formation in an exopolysaccharide-independent manner. Moreover, orthologs of the V. cholerae norspermidine biosynthetic pathway are absent from B. subtilis, confirming that norspermidine is not physiologically relevant to biofilm function in this species
Exploring the galaxy cluster-group transition regime at high redshifts: Physical properties of two newly detected z > 1 systems
Context: Multi-wavelength surveys for clusters of galaxies are opening a
window on the elusive high-redshift (z>1) cluster population. Well controlled
statistical samples of distant clusters will enable us to answer questions
about their cosmological context, early assembly phases and the thermodynamical
evolution of the intracluster medium. Aims: We report on the detection of two
z>1 systems, XMMU J0302.2-0001 and XMMU J1532.2-0836, as part of the XMM-Newton
Distant Cluster Project (XDCP) sample. We investigate the nature of the
sources, measure their spectroscopic redshift and determine their basic
physical parameters. Methods: The results of the present paper are based on the
analysis of XMM-Newton archival data, optical/near-infrared imaging and deep
optical follow-up spectroscopy of the clusters. Results: We confirm the X-ray
source XMMU J0302.2-0001 as a gravitationally bound, bona fide cluster of
galaxies at spectroscopic redshift z=1.185. We estimate its M500 mass to
(1.6+/-0.3) times 10^{14} Msun from its measured X-ray luminosity. This ranks
the cluster among intermediate mass system. In the case of XMMU J1532.2-0836 we
find the X-ray detection to be coincident with a dynamically bound system of
galaxies at z=1.358. Optical spectroscopy reveals the presence of a central
active galactic nucleus, which can be a dominant source of the detected X-ray
emission from this system. We provide upper limits of X-ray parameters for the
system and discuss cluster identification challenges in the high-redshift
low-mass cluster regime. A third, intermediate redshift (z=0.647) cluster, XMMU
J0302.1-0000, is serendipitously detected in the same field as XMMU
J0302.2-0001. We provide its analysis as well.Comment: Accepted to A&A, 13/04/2011. 15 pages, 18 figures, 5 tables, 2
appendice
The XMM Cluster Survey: X-ray analysis methodology
The XMM Cluster Survey (XCS) is a serendipitous search for galaxy clusters
using all publicly available data in the XMM-Newton Science Archive. Its main
aims are to measure cosmological parameters and trace the evolution of X-ray
scaling relations. In this paper we describe the data processing methodology
applied to the 5,776 XMM observations used to construct the current XCS source
catalogue. A total of 3,675 > 4-sigma cluster candidates with > 50
background-subtracted X-ray counts are extracted from a total non-overlapping
area suitable for cluster searching of 410 deg^2. Of these, 993 candidates are
detected with > 300 background-subtracted X-ray photon counts, and we
demonstrate that robust temperature measurements can be obtained down to this
count limit. We describe in detail the automated pipelines used to perform the
spectral and surface brightness fitting for these candidates, as well as to
estimate redshifts from the X-ray data alone. A total of 587 (122) X-ray
temperatures to a typical accuracy of < 40 (< 10) per cent have been measured
to date. We also present the methodology adopted for determining the selection
function of the survey, and show that the extended source detection algorithm
is robust to a range of cluster morphologies by inserting mock clusters derived
from hydrodynamical simulations into real XMM images. These tests show that the
simple isothermal beta-profiles is sufficient to capture the essential details
of the cluster population detected in the archival XMM observations. The
redshift follow-up of the XCS cluster sample is presented in a companion paper,
together with a first data release of 503 optically-confirmed clusters.Comment: MNRAS accepted, 45 pages, 38 figures. Our companion paper describing
our optical analysis methodology and presenting a first set of confirmed
clusters has now been submitted to MNRA
Relapsing polychondritis: state of the art on clinical practice guidelines
Due to the rarity of relapsing polychondritis (RP), many unmet needs remain in the management of RP. Here, we present a systematic review of clinical practice guidelines (CPGs) published for RP, as well as a list of the most striking unmet needs for this rare disease. We carried out a systematic search in PubMed and Embase based on controlled terms (medical subject headings and Emtree) and keywords of the disease and publication type (CPGs). The systematic literature review identified 20 citations, among which no CPGs could be identified. We identified 11 main areas with unmet needs in the field of RP: the diagnosis strategy for RP; the therapeutic management of RP; the management of pregnancy in RP; the management of the disease in specific age groups (for instance in paediatric-onset RP); the evaluation of adherence to treatment; the follow-up of patients with RP, including the frequency of screening for the potential complications and the optimal imaging tools for each involved region; perioperative and anaesthetic management (due to tracheal involvement); risk of neoplasms in RP, including haematological malignancies; the prevention and management of infections; tools for assessment of disease activity and damage; and patient-reported outcomes and quality of life indicators. Patients and physicians should work together within the frame of the ReCONNET network to derive valuable evidence for obtaining literature-informed CPGs
Endogenous Morphine Levels Are Increased in Sepsis: A Partial Implication of Neutrophils
BACKGROUND: Mammalian cells synthesize morphine and the respective biosynthetic pathway has been elucidated. Human neutrophils release this alkaloid into the media after exposure to morphine precursors. However, the exact role of endogenous morphine in inflammatory processes remains unclear. We postulate that morphine is released during infection and can be determined in the serum of patients with severe infection such as sepsis. METHODOLOGY: The presence and subcellular immunolocalization of endogenous morphine was investigated by ELISA, mass spectrometry analysis and laser confocal microscopy. Neutrophils were activated with Interleukin-8 (IL-8) or lipopolysaccharide (LPS). Morphine secretion was determined by a morphine-specific ELISA. mu opioid receptor expression was assessed with flow cytometry. Serum morphine concentrations of septic patients were determined with a morphine-specific ELISA and morphine identity was confirmed in human neutrophils and serum of septic patients by mass spectrometry analysis. The effects of the concentration of morphine found in serum of septic patients on LPS-induced release of IL-8 by human neutrophils were tested. PRINCIPAL FINDINGS: We confirmed the presence of morphine in human neutrophil extracts and showed its colocalisation with lactoferrin within the secondary granules of neutrophils. Morphine secretion was quantified in the supernatant of activated human polymorphonuclear neutrophils in the presence and absence of Ca(2+). LPS and IL-8 were able to induce a significant release of morphine only in presence of Ca(2+). LPS treatment increased mu opioid receptor expression on neutrophils. Low concentration of morphine (8 nM) significantly inhibited the release of IL-8 from neutrophils when coincubated with LPS. This effect was reversed by naloxone. Patients with sepsis, severe sepsis and septic shock had significant higher circulating morphine levels compared to patients with systemic inflammatory response syndrome and healthy controls. Mass spectrometry analysis showed that endogenous morphine from serum of patient with sepsis was identical to poppy-derived morphine. CONCLUSIONS: Our results indicate that morphine concentrations are increased significantly in the serum of patients with systemic infection and that morphine is, at least in part, secreted from neutrophils during sepsis. Morphine concentrations equivalent to those found in the serum of septic patients significantly inhibited LPS-induced IL-8 secretion in neutrophils
The X-ray luminous cluster underlying the bright radio-quiet quasar H1821+643
We present a Chandra observation of the only low redshift, z=0.299, galaxy
cluster to contain a highly luminous radio-quiet quasar, H1821+643. By
simulating the quasar PSF, we subtract the quasar contribution from the cluster
core and determine the physical properties of the cluster gas down to 3 arcsec
(15 kpc) from the point source. The temperature of the cluster gas decreases
from 9.0\pm0.5 keV down to 1.3\pm0.2 keV in the centre, with a short central
radiative cooling time of 1.0\pm0.1 Gyr, typical of a strong cool-core cluster.
The X-ray morphology in the central 100 kpc shows extended spurs of emission
from the core, a small radio cavity and a weak shock or cold front forming a
semi-circular edge at 15 arcsec radius. The quasar bolometric luminosity was
estimated to be 2 x 10^{47} erg per sec, requiring a mass accretion rate of 40
Msolar per yr, which corresponds to half the Eddington accretion rate. We
explore possible accretion mechanisms for this object and determine that Bondi
accretion, when boosted by Compton cooling of the accretion material, could
provide a significant source of the fuel for this outburst. We consider
H1821+643 in the context of a unified AGN accretion model and, by comparing
H1821+643 with a sample of galaxy clusters, we show that the quasar has not
significantly affected the large-scale cluster gas properties.Comment: 20 pages, 19 figures, accepted by MNRA
Estimation of genetic diversity and relationship in sugar beet pollinators based on SSR markers
Background: Genetic diversity studies are important for the selection of parents with a greater combination capacity that, when crossed, increase the chances of obtaining superior genotypes. Thus, 26 polymorphic simple sequence repeat (SSR) primers were used to assess the genetic diversity of 140 individual samples from 12 diploid sugar beet pollinators (pollen parents) and two cytoplasmic male sterile (cms) lines (seed parents). Eight pollinators originated from three research centers in the United States Department of Agriculture, while four pollinators and cms lines were from the Institute of Field and Vegetable Crops, Novi Sad, Serbia. Results: In total, 129 alleleswere obtained, with a mean of 3.2 alleles per SSR marker. The observed heterozygosity ranged from 0.00 to 0.87 (mean = 0.30). Expected heterozygosity and Shannon's information index were the lowest for marker BQ590934 and the highest for markers SB15s and FDSB502s; the same markers were the most informative, with PIC values of 0.70 and 0.69, respectively. Three private alleles were found in pollinator EL0204; two in pollinator C51; and one in pollinators NS1, FC221, and C93035. Molecular variance showed that 77.34% of the total genetic variation was attributed to intrapopulation variability. Cluster and correspondence analysis grouped sugar beet pollinators according to the breeding centers, with few exceptions, which indicate that certain amount of germplasm was shared, although centers had their own breeding programs. Conclusions: The results indicate that this approach can improve the selection of pollinators as suitable parental components and could further be applied in sugar beet breeding programs
First Observation of CP Violation in B0->D(*)CP h0 Decays by a Combined Time-Dependent Analysis of BaBar and Belle Data
We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0
decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the
neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S
omega. The measurement is performed combining the final data samples collected
at the Y(4S) resonance by the BaBar and Belle experiments at the
asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The
data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar
detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We
measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06
(syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results
correspond to the first observation of CP violation in B0->D(*)CP h0 decays.
The hypothesis of no mixing-induced CP violation is excluded in these decays at
the level of 5.4 standard deviations.Comment: 9 pages, 2 figures, submitted to Physical Review Letter
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