1,049 research outputs found
Relationship between X-ray and ultraviolet emission in 3C 273
In 3C 273, ultraviolet flux and X-ray flux measured by BATSE are not well
correlated, contrarily to predictions of several models, unless the X-ray flux
lags the UV emission by 1.75 yr. The absence of observed correlation at small
lag cannot be due to spectral variability. A Comptonizing corona model is
however compatible with all UV and X-ray observations covering the BATSE
period.Comment: LaTeX, 4 pages, 6 figures. espcrc2.sty style file included. Poster
contribution to the symposium "The Active X-ray Sky: Results from BepppoSAX
and Rossi-XTE", Rome, October 199
2003--2005 INTEGRAL and XMM-Newton observations of 3C 273
The aim of this paper is to study the evolution of the broadband spectrum of
one of the brightest and nearest quasars 3C 273.
We analyze the data obtained during quasi-simultaneous INTEGRAL and XMM
monitoring of the blazar 3C 273 in 2003--2005 in the UV, X-ray and soft
gamma-ray bands and study the results in the context of the long-term evolution
of the source.
The 0.2-100 keV spectrum of the source is well fitted by a combination of a
soft cut-off power law and a hard power law. No improvement of the fit is
achieved if one replaces the soft cut-off power law by either a blackbody, or a
disk reflection model. During the observation period the source has reached the
historically softest state in the hard X-ray domain with a photon index
. Comparing our data with available archived X-ray data
from previous years, we find a secular evolution of the source toward softer
X-ray emission (the photon index has increased by
over the last thirty years). We argue that existing theoretical models have to
be significantly modified to account for the observed spectral evolution of the
source.Comment: 11 pages, accepted to A&
Exploration of health dimensions to be included in multi-attribute health-utility assessment
Objective Measurement of health utility is important for quality improvement, but instruments vary in their content. Multi-attribute health utility measures typically assess a small number of health problems, e.g. the EuroQoL EQ-5D questionnaire explores five dimensions of health. We aimed to examine whether a small number of dimensions explains a sufficient amount of variance in self-perceived health, and what can be gained from adding additional dimensions. Design Cross-sectional mail survey that explored health utility and self-perceived health. Setting General resident population of French-speaking Switzerland. Participants Non-institutionalized adults. Main outcome measures EQ-5D (which measures mobility, self-care, usual activities, pain/discomfort, anxiety/depression and a visual analogue health scale between 0 and 100 (VAS)). A subsample rated five additional health dimensions (sleep, memory/concentration, energy/fatigue, sight/hearing, contacts with others). Results In total, 349 adults returned the extended 10-item questionnaire. All added items were strongly and significantly associated with the VAS for perceived health. The proportion of variance explained (R2) in the VAS was 0.47 for the original EQ-5D items (adjusted for attenuation: 0.65), 0.47 for the new items (adjusted for attenuation: 0.65) and 0.56 for the 10 items together (adjusted for attenuation: 0.78). Forty-four percent of the respondents who had a perfect health utility on the EQ-5D reported at least one problem in the new health dimensions. Conclusion Self-perceived health among the general public is influenced by more health dimensions than are typically measured in a multi-attribute health-utility instrumen
Social Support, Social and Temporal Comparisons Protect Well-Being and Health between 45 and 70 Years Old in Four Urban Communities
This study examined the impact of social support and of temporal and social comparisons on well-being and selfreported health in four capital cities: Paris, Berlin, Moscow and Beijing. Based on the lifespan control theory, an
integrative model investigating the influence of these coping strategies, especially on the psychological regulation of
health losses, was tested on 1141 respondents aged 45 to 70 years by using structural equation modelling with
multigroup comparisons. Results indicated a good fit of the model to participants' responses. In all contexts, physical
weaknesses favoured the use of social and temporal comparison strategies rather than social support. Moreover,
across the cities, coping strategies were oriented more toward protecting self-evaluation of health than toward
enhancement of well-being. Social comparison decreased the impact of physical weaknesses on health evaluation
and on well-being in the four cities, but to a lesser extent in China. Results are discussed regarding the normative
cross-cultural aspects that intervene during ageing in the four urban contexts
Clinical factors associated with the non-utilization of an anaesthesia incident reporting system
Background Incident reporting is a widely recommended method to measure undesirable events in anaesthesia. Under-utilization is a major weakness of voluntary incident reporting systems. Little is known about factors influencing reporting practices, particularly the clinical environment, anaesthesia team composition, severity of the incident, and perceived risk of litigation. The purpose of this study was to assess each of these, using an existing anaesthesia database. Methods We performed a retrospective cohort study and analysed 46 207 surgical patients. We used multivariate analysis to identify factors associated with the non-utilization of the reporting system. Results We found that in 7022 (15.1%) of the procedures performed, the incident reporting system was not used. Factors associated with the non-use of the system were regional anaesthesia/local anaesthesia, odds ratio (OR) 1.64 [95% confidence interval (CI) 1.03-2.62], emergency procedures OR 1.15 (95% CI: 1.05-1.27), and a consultant anaesthetist working without a trainee, OR 1.71 (95% CI: 1.03-2.82). In contrast, factors such as longer duration of surgery, OR 0.85 (95% CI: 0.76-0.94), the presence of a senior anaesthesia trainee, OR 0.86 (95% CI: 0.81-0.92), and the occurrence of severe complications with a high risk of litigation (i.e. death, nerve injuries) were less associated with a non-use of the reporting system, OR 0.65 (95% CI: 0.44-0.97). Team composition and time of day had no measurable impact on reporting practices. Conclusions Clinical factors play a significant role in the utilization of an anaesthesia incident reporting system and more particularly, severity of complications and higher liability risks which appear more as incentives than barriers to incident reportin
INTEGRAL discovery of non-thermal hard X-ray emission from the Ophiuchus cluster
We present the results of deep observations of the Ophiuchus cluster of
galaxies with INTEGRAL in the 3-80 keV band. We analyse 3 Ms of INTEGRAL data
on the Ophiuchus cluster with the IBIS/ISGRI hard X-ray imager and the JEM-X
X-ray monitor. In the X-ray band using JEM-X, we show that the source is
extended, and that the morphology is compatible with the results found by
previous missions. Above 20 keV, we show that the size of the source is
slightly larger than the PSF of the instrument, and is consistent with the soft
X-ray morphology found with JEM-X and ASCA. Thanks to the constraints on the
temperature provided by JEM-X, we show that the spectrum of the cluster is not
well fitted by a single-temperature thermal Bremsstrahlung model, and that
another spectral component is needed to explain the high energy data. We detect
the high energy tail with a higher detection significance (6.4 sigma) than the
BeppoSAX claim (2 sigma). Because of the imaging capabilities of JEM-X and
ISGRI, we are able to exclude the possibility that the excess emission comes
from very hot regions or absorbed AGN, which proves that the excess emission is
indeed of non-thermal origin. Using the available radio data together with the
non-thermal hard X-ray flux, we estimate a magnetic field B ~ 0.1-0.2 mu G.Comment: 8 pages, 9 figures, accepted by A&
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