281 research outputs found
Hot Gaseous Coronae around Spiral Galaxies: Probing the Illustris Simulation
The presence of hot gaseous coronae around present-day massive spiral
galaxies is a fundamental prediction of galaxy formation models. However, our
observational knowledge remains scarce, since to date only four gaseous coronae
were detected around spirals with massive stellar bodies
(). To explore the hot coronae around
lower mass spiral galaxies, we utilized Chandra X-ray observations of a sample
of eight normal spiral galaxies with stellar masses of . Although statistically significant diffuse X-ray emission is
not detected beyond the optical radii ( kpc) of the galaxies, we derive
limits on the characteristics of the coronae. These limits,
complemented with previous detections of NGC 1961 and NGC 6753, are used to
probe the Illustris Simulation. The observed upper limits on the
X-ray luminosities and gas masses exceed or are at the upper end of the model
predictions. For NGC 1961 and NGC 6753 the observed gas temperatures, metal
abundances, and electron density profiles broadly agree with those predicted by
Illustris. These results hint that the physics modules of Illustris are broadly
consistent with the observed properties of hot coronae around spiral galaxies.
However, a shortcoming of Illustris is that massive black holes, mostly
residing in giant ellipticals, give rise to powerful radio-mode AGN feedback,
which results in under luminous coronae for ellipticals.Comment: 12 pages, 6 figures, accepted for publication in Ap
Prognostic significance of nonfatal reinfarction during 3-year follow-up: Results of the thrombolysis in myocardial infarction (TIMI) phase II clinical trial
Objectives.This study sought to assess the independent contribution of nonfatal reinfarction to the risk of subsequent death in patients with acute myocardial infarction undergoing thrombolytic therapy.Background.A composite of âunsatisfactory outcomesâ as an end point has increased statistical power and facilitated evaluation of evolving treatment regimens in acute myocardial infarction. The significance of nonfatal reinfarction as a component of a composite end point has not been evaluated in the thrombolytic era.Methods.Event rate of nonfatal reinfarction over 3-year follow-up was evaluated in patients with acute myocardial infarction entered into the Thrombolysis in Myocardial Infarction Phase II trial. The independent risk of nonfatal reinfarction for subsequent death within various time intervals of follow-up was determined. The mortality rate after nonfatal reinfarction was compared with that of a matched control group.Results.During 3-year follow-up, 349 of 3,339 patients had a nonfatal reinfarction. Univariate predictors were history (antedating the index event) of angina (p = 0.01), hypertension (p = 0.01), multivessel disease (p = 0.007) and not a current smoker (p = 0.003); the latter was an independent predictor (relative risk [RR] 1.3, 99% confidence interval [CI]1.0 to 1.8). Forty-three of the 349 patients with a nonfatal reinfarction died: RR for death (vs. patients without a nonfatal reinfarction) was 1.9 (99% CI 1.1 to 3.2) if reinfarction occurred within 42 days of study entry, 6.2 (99% CI 3.0 to 12.9) if reinfarction occurred between 43 and 365 days and 2.9 (99% CI 0.6 to 13.4) if reinfarction occurred between 366 days and 3 years. The cumulative 3-year death rate was 14.1% in patients with a nonfatal reinfarction compared with 7.9% (p < 0.01) in a matched control group. Univariate predictors of death after nonfatal reinfarction were age â„65 years (p < 0.001), not low risk category (p = 0.015) and history of heart failure before the index event (p < 0.001). Age â„65 years was the only independent predictor (RR 5.4, 99% CI 2.3 to 12.4).Conclusions.Nonfatal reinfarction is a strong and independent predictor for subsequent death. It represents a powerful component for a composite end point in patients who received thrombolytic therapy after acute myocardial infarction
Gastric cancer and Helicobacter pylori: a combined analysis of 12 case control studies nested within prospective cohorts
BACKGROUND: The magnitude of the association
between Helicobacter pylori and
incidence of gastric cancer is unclear. H
pylori infection and the circulating antibody
response can be lost with development
of cancer; thus retrospective studies
are subject to bias resulting from classifi-
cation of cases as H pylori negative when
they were infected in the past.
AIMS: To combine data from all case control
studies nested within prospective
cohorts to assess more reliably the relative
risk of gastric cancer associated with H
pylori infection.To investigate variation in
relative risk by age, sex, cancer type and
subsite, and interval between blood sampling
and cancer diagnosis.
METHODS: Studies were eligible if blood
samples for H pylori serology were collected
before diagnosis of gastric cancer in
cases. Identified published studies and two
unpublished studies were included. Individual
subject data were obtained for
each. Matched odds ratios (ORs) and 95%
confidence intervals (95% CI) were calculated
for the association between H pylori
and gastric cancer.
RESULTS: Twelve studies with 1228 gastric
cancer cases were considered. The association
with H pylori was restricted to noncardia
cancers (OR 3.0; 95% CI 2.3â3.8)
and was stronger when blood samples for
H pylori serology were collected 10+ years
before cancer diagnosis (5.9; 3.4â10.3). H
pylori infection was not associated with an
altered overall risk of cardia cancer (1.0;
0.7â1.4).
CONCLUSIONS: These results suggest that
5.9 is the best estimate of the relative risk
of non-cardia cancer associated with H
pylori infection and that H pylori does not
increase the risk of cardia cancer. They
also support the idea that when H pylori
status is assessed close to cancer diagnosis,
the magnitude of the non-cardia
association may be underestimated
A Transient Sub-Eddington Black Hole X-ray Binary Candidate in the Dust Lanes of Centaurus A
We report the discovery of a bright X-ray transient, CXOU J132527.6-430023,
in the nearby early-type galaxy NGC 5128. The source was first detected over
the course of five Chandra observations in 2007, reaching an unabsorbed
outburst luminosity of 1-2*10^38 erg/s in the 0.5-7.0 keV band before returning
to quiescence. Such luminosities are possible for both stellar-mass black hole
and neutron star X-ray binary transients. Here, we attempt to characterize the
nature of the compact object. No counterpart has been detected in the optical
or radio sky, but the proximity of the source to the dust lanes allows for the
possibility of an obscured companion. The brightness of the source after a >100
fold increase in X-ray flux makes it either the first confirmed transient
non-ULX black hole system in outburst to be subject to detailed spectral
modeling outside the Local Group, or a bright (>10^38 erg/s) transient neutron
star X-ray binary, which are very rare. Such a large increase in flux would
appear to lend weight to the view that this is a black hole transient. X-ray
spectral fitting of an absorbed power law yielded unphysical photon indices,
while the parameters of the best-fit absorbed disc blackbody model are typical
of an accreting ~10 Msol black hole in the thermally dominant state.Comment: 8 pages, 6 figures, accepted for publication in Ap
The Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of acute leukemia.
Acute leukemia is a constellation of rapidly progressing diseases that affect a wide range of patients regardless of age or gender. Traditional treatment options for patients with acute leukemia include chemotherapy and hematopoietic cell transplantation. The advent of cancer immunotherapy has had a significant impact on acute leukemia treatment. Novel immunotherapeutic agents including antibody-drug conjugates, bispecific T cell engagers, and chimeric antigen receptor T cell therapies have efficacy and have recently been approved by the US Food and Drug Administration (FDA) for the treatment of patients with acute leukemia. The Society for Immunotherapy of Cancer (SITC) convened a panel of experts to develop a clinical practice guideline composed of consensus recommendations on immunotherapy for the treatment of acute lymphoblastic leukemia and acute myeloid leukemia
The X-ray and mid-infrared luminosities in luminous type 1 quasars
Several recent studies have reported different intrinsic correlations between the active galactic nucleus (AGN) mid-IR luminosity () and the rest-frame 2â10 keV luminosity (L X) for luminous quasars. To understand the origin of the difference in the observed {L}_{{\rm{X}}}\mbox{--}{L}_{\mathrm{MIR}} relations, we study a sample of 3247 spectroscopically confirmed type 1 AGNs collected from Boötes, XMM-COSMOS, XMM-XXL-North, and the Sloan Digital Sky Survey quasars in the Swift/XRT footprint spanning over four orders of magnitude in luminosity. We carefully examine how different observational constraints impact the observed {L}_{{\rm{X}}}\mbox{--}{L}_{\mathrm{MIR}} relations, including the inclusion of X-ray-nondetected objects, possible X-ray absorption in type 1 AGNs, X-ray flux limits, and star formation contamination. We find that the primary factor driving the different {L}_{{\rm{X}}}\mbox{--}{L}_{\mathrm{MIR}} relations reported in the literature is the X-ray flux limits for different studies. When taking these effects into account, we find that the X-ray luminosity and mid-IR luminosity (measured at rest-frame , or ) of our sample of type 1 AGNs follow a bilinear relation in the logâlog plane: erg sâ1 + (44.60 ± 0.01) for erg sâ1, and erg sâ1 + (44.51 ± 0.01) for erg sâ1. This suggests that the luminous type 1 quasars have a shallower {L}_{{\rm{X}}}\mbox{--}{L}_{6\mu {\rm{m}}} correlation than the approximately linear relations found in local Seyfert galaxies. This result is consistent with previous studies reporting a luminosity-dependent {L}_{{\rm{X}}}\mbox{--}{L}_{\mathrm{MIR}} relation and implies that assuming a linear {L}_{{\rm{X}}}\mbox{--}{L}_{6\mu {\rm{m}}} relation to infer the neutral gas column density for X-ray absorption might overestimate the column densities in luminous quasars
Low-Mass X-ray Binaries and Globular Clusters in Centaurus A
We present results of Hubble Space Telescope and Chandra X-ray Observatory
observations of globular clusters (GCs) and low-mass X-ray binaries (LMXBs) in
the central regions of Centaurus A. Out of 440 GC candidates we find that 41
host X-ray point sources that are most likely LMXBs. We fit King models to our
GC candidates in order to measure their structural parameters. We find that GCs
that host LMXBs are denser and more compact, and have higher encounter rates
and concentrations than the GC population as a whole. We show that the higher
concentrations and masses are a consequence of the dependence of LMXB incidence
on central density and size plus the general trend for denser GCs to have
higher masses and concentrations. We conclude that neither concentration nor
mass are fundamental variables in determining the presence of LMXBs in GCs, and
that the more fundamental parameters relate to central density and size.Comment: 4 pages, 2 figures. Accepted for publication in ApJ Letter
Multilevel latent class casemix modelling: a novel approach to accommodate patient casemix
<p>Abstract</p> <p>Background</p> <p>Using routinely collected patient data we explore the utility of multilevel latent class (MLLC) models to adjust for patient casemix and rank Trust performance. We contrast this with ranks derived from Trust standardised mortality ratios (SMRs).</p> <p>Methods</p> <p>Patients with colorectal cancer diagnosed between 1998 and 2004 and resident in Northern and Yorkshire regions were identified from the cancer registry database (n = 24,640). Patient age, sex, stage-at-diagnosis (Dukes), and Trust of diagnosis/treatment were extracted. Socioeconomic background was derived using the Townsend Index. Outcome was survival at 3 years after diagnosis. MLLC-modelled and SMR-generated Trust ranks were compared.</p> <p>Results</p> <p>Patients were assigned to two classes of similar size: one with reasonable prognosis (63.0% died within 3 years), and one with better prognosis (39.3% died within 3 years). In patient class one, all patients diagnosed at stage B or C died within 3 years; in patient class two, all patients diagnosed at stage A, B or C survived. Trusts were assigned two classes with 51.3% and 53.2% of patients respectively dying within 3 years. Differences in the ranked Trust performance between the MLLC model and SMRs were all within estimated 95% CIs.</p> <p>Conclusions</p> <p>A novel approach to casemix adjustment is illustrated, ranking Trust performance whilst facilitating the evaluation of factors associated with the patient journey (e.g. treatments) and factors associated with the processes of healthcare delivery (e.g. delays). Further research can demonstrate the value of modelling patient pathways and evaluating healthcare processes across provider institutions.</p
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