478 research outputs found
Deep Spectroscopy of the Host Galaxy of a Tidal Disruption Flare in A1795
A likely tidal disruption of a star by the intermediate-mass black hole
(IMBH) of a dwarf galaxy was recently identified in association with Abell
1795. Without deep spectroscopy for this very faint object, however, the
possibility of a more massive background galaxy or even a disk-instability
flare from a weak AGN could not be dismissed. We have now obtained 8 hours of
Gemini spectroscopy which unambiguously demonstrate that the host galaxy is
indeed an extremely low-mass
galaxy in Abell 1795, comparable to the least-massive galaxies determined to
host IMBHs via other studies. We find that the spectrum is consistent with the
X-ray flare being due to a tidal disruption event rather than an AGN flare. We
also set improved limits on the black hole mass and infer a 15-year X-ray variability of a factor
of . The confirmation of this galaxy-black hole system provides a
glimpse into a population of galaxies that is otherwise difficult to study, due
to the galaxies' low masses and intrinsic faintness, but which may be important
contributors to the tidal disruption rate.Comment: 9 pages, 4 figures. Accepted by MNRA
Breast Cancer in Young Women - a Clinical Challenge to Be Addressed in a Multidisciplinary Setting
Galaxy Orbits for Galaxy Clusters in Sloan Digital Sky Survey and 2dF Galaxy Redshift Survey
We present the results of a study for galaxy orbits in galaxy clusters using
a spectroscopic sample of galaxies in Sloan Digital Sky Survey (SDSS) and 2dF
Galaxy Redshift Survey (2dFGRS). We have determined the member galaxies of
Abell clusters covered by these surveys using the galaxies' redshift and
positional data. We have selected 10 clusters using three criteria: the number
of member galaxies is greater than or equal to 40, the spatial coverage is
complete, and X-ray mass profile is available in the literature. We derive the
radial profile of the galaxy number density and velocity dispersion using all,
early-type, and late-type galaxies for each cluster. We have investigated the
galaxy orbits for our sample clusters with constant and variable velocity
anisotropies over the clustercentric distance using Jeans equation. Using all
member galaxies, the galaxy orbits are found to be isotropic within the
uncertainty for most of sample clusters, although it is difficult to conclude
strongly for some clusters due the large errors and the variation as a function
of the clustercentric distance in the calculated velocity anisotropies. We
investigated the orbital difference between early-type and late-type galaxies
for four sample clusters, and found no significant difference between them.Comment: 59 pages, 21 figures. To appear in ApJ. Paper with high resolution
figures are available at http://astro.kias.re.kr/~hshwang/papers/orbit.pd
Cholecystectomy and the risk of colorectal cancer in Italy
In two case-control studies from Italy covering 3533 cases of colorectal cancer and 7062 hospital controls, the odds ratios were 1.04 after cholecystectomy for colorectal, 1.08 for colon and 1.03 for rectal cancers. The results did not differ significantly by gender, colon subsite or time since diagnosis
Use of postmenopausal hormone replacement therapy and risk of non-Hodgkin's lymphoma: a Danish Population-based Cohort Study
Use of postmenopausal hormone replacement therapy (HRT) has been hypothesised to be associated with a reduced risk of non-Hodgkin's lymphoma (NHL), but the epidemiologic evidence is conflicting. To examine the risk of NHL in HRT users aged 40 and older, we conducted a cohort study in the County of North Jutland, Denmark (population 0.5 million) using data from population-based health registries for the period 1989–2002. We computed age-standardised NHL incidence rates and used Cox regression analysis to compute the relative risk (RR) and corresponding 95% confidence intervals (CI) of NHL among HRT users compared with non-users, adjusting for age and calendar period. The number of prescriptions redeemed (1, 2–4, 5–9, 10–19, or 20 or more prescriptions) was used as a proxy for duration of HRT. We identified 40 NHL cases among HRT users during 179 838 person-years of follow-up and 310 NHL cases among non-users during 1 247 302 person-years of follow-up. The age-standardised incidence rates of NHL were 25.7 per 100 000 among HRT users and 24.2 per 100 000 among non-users, yielding an adjusted RR of 0.99 (95% CI: 0.71–1.39). Our data did not support an association between HRT use and risk of NHL
Diabetes status and post-load plasma glucose concentration in relation to site-specific cancer mortality: findings from the original Whitehall study
ObjectiveWhile several studies have reported on the relation of diabetes status with pancreatic cancer risk, the predictive value of this disorder for other malignancies is unclear. Methods: The Whitehall study, a 25year follow-up for mortality experience of 18,006 men with data on post-challenge blood glucose and self-reported diabetes, allowed us to address these issues. Results: There were 2158 cancer deaths at follow-up. Of the 15 cancer outcomes, diabetes status was positively associated with mortality from carcinoma of the pancreas and liver, while the relationship with lung cancer was inverse, after controlling for a range of potential covariates and mediators which included obesity and socioeconomic position. After excluding deaths occurring in the first 10years of follow-up to examine the effect of reverse causality, the magnitude of the relationships for carcinoma of the pancreas and lung was little altered, while for liver cancer it was markedly attenuated. Conclusions: In the present study, diabetes status was related to pancreatic, liver, and lung cancer risk. Cohorts with serially collected data on blood glucose and covariates are required to further examine this area
A record-linkage study of the development of hepatocellular carcinoma in persons with hepatitis C infection in Scotland
We investigated trends in first time hospital admissions and deaths attributable to hepatocellular carcinoma (HCC) in a large population based cohort of 22 073 individuals diagnosed with hepatitis C viral (HCV) infection through laboratory testing in Scotland in 1991 2006. We identified new cases of HCC through record linkage to the national inpatient hospital discharge database and deaths registry. A total of 172 persons diagnosed with HCV were admitted to hospital or died with first time mention of HCC. Hepatocellular carcinoma incidence increased between 1996 and 2006 (average annual change of 6.1, 95% confidence interval (CI):0.9 11.6%, P¼0.021). The adjusted relative risk of HCC was greater for males (hazard ratio¼2.7, 95% CI: 1.7 4.2), for those aged 60 years or older (hazard ratio ¼2.7, 95% CI: 1.9 4.1) compared with 50 59 years, and for those with a previous alcohol related hospital admission (hazard ratio¼2.5, 95% CI: 1.7 3.7). The risk of individuals diagnosed with HCV developing HCC was greatlyincreased compared with the general Scottish population (standardised incidence ratio¼127, 95% CI: 102 156). Owing to the advancing age of the Scottish HCV diagnosed population, the annual number of HCC cases is projected to increase, with a consequent increasing burden on the public healthcare system
Direct measurement of dark matter halo ellipticity from two-dimensional lensing shear maps of 25 massive clusters
We present new measurements of dark matter distributions in 25 X-ray luminous
clusters by making a full use of the two-dimensional (2D) weak lensing signals
obtained from high-quality Subaru/Suprime-Cam imaging data. Our approach to
directly compare the measured lensing shear pattern with elliptical model
predictions allows us to extract new information on the mass distributions of
individual clusters, such as the halo ellipticity and mass centroid. We find
that these parameters on the cluster shape are little degenerate with cluster
mass and concentration parameters. By combining the 2D fitting results for a
subsample of 18 clusters, the elliptical shape of dark matter haloes is
detected at 7\sigma significance level. The mean ellipticity is found to be e =
0.46 \pm 0.04 (1\sigma), which is in excellent agreement with the standard
collisionless CDM model prediction. The mass centroid can be constrained with a
typical accuracy of ~20" (~50 kpc/h) in radius for each cluster with some
significant outliers, enabling to assess one of the most important systematic
errors inherent in the stacked cluster weak lensing technique, the mass
centroid uncertainty. In addition, the shape of the dark mass distribution is
found to be only weakly correlated with that of the member galaxy distribution.
We carefully examine possible sources of systematic errors in our measurements,
finding none of them to be significant. Our results demonstrate the power of
high-quality imaging data for exploring the detailed spatial distribution of
dark matter (Abridged).Comment: 17 pages, 10 figures, MNRAS in pres
Estimating relative survival among people registered with cancer in England and Wales
Because routinely collected survival data for cancer patients in England and Wales do not typically specify cause of death, conventional estimates of survival in cancer patients based on such data are a measure of their mortality from all causes rather than their mortality due to cancer. As a result, trends in survival over time are difficult to interpret because changes in overall survival may well reflect changes in the risk of death from other causes, rather than from the cancer of interest. One way of overcoming this problem is to use some form of ‘relative survival’ defined as a measure of survival corrected for the effect of other independent causes of death. Since this concept was first introduced, various methods for calculating relative survival have been proposed and this had led to some confusion as to the most appropriate choice of estimate. This paper aims to provide an introduction to the concept of relative survival and reviews some of the suggested methods of estimation. In addition, a particularly simple, but robust approach, is highlighted based on expected and observed mortality. This method is illustrated using preliminary data from the Office for National Statistics on cancer survival in patients born after 1939 and diagnosed with cancer during 1972–84. The examples presented, although limited to analyses on a small number of selected sites, highlight some encouraging trends in survival in people aged under 35 diagnosed with leukaemia, Hodgkin's disease and testicular cancer during this period. © 1999 Cancer Research Campaig
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