419 research outputs found
The first endovascular repair of an acute type A dissection using an endograft designed for the ascending aorta
Endovascular repair has emerged as a potential alternative to emergency open surgical repair for type A dissection in selected patients, with isolated reports describing the results obtained with a range of devices designed originally for the descending aorta. We believe that we present the first reported repair of an acute ascending aortic dissection using an endovascular stent graft manufactured specifically for the ascending aorta
Psychosocial assessment of self-harm patients and risk of repeat presentation:An instrumental variable analysis using time of hospital presentation
BACKGROUND:Clinical guidelines have recommended psychosocial assessment of self-harm patients for years, yet estimates of its impact on the risk of repeat self-harm vary. Assessing the association of psychosocial assessment with risk of repeat self-harm is challenging due to the effects of confounding by indication. METHODS:We analysed data from a cohort study of 15,113 patients presenting to the emergency departments of three UK hospitals to investigate the association of psychosocial assessment with risk of repeat hospital presentation for self-harm. Time of day of hospital presentation was used as an instrument for psychosocial assessment, attempting to control for confounding by indication. RESULTS:Conventional regression analysis suggested psychosocial assessment was not associated with risk of repeat self-harm within 12 months (Risk Difference (RD) 0.00 95% confidence interval (95%CI) -0.01 to 0.02). In contrast, IV analysis suggested risk of repeat self-harm was reduced by 18% (RD -0.18, 95%CI -0.32 to -0.03) in those patients receiving a psychosocial assessment. However, the instrument of time of day did not remove all potential effects of confounding by indication, suggesting the IV effect estimate may be biased. CONCLUSIONS:We found that psychosocial assessments reduce risk of repeat self-harm. This is in-line with other non-randomised studies based on populations in which allocation to assessment was less subject to confounding by indication. However, as our instrument did not fully balance important confounders across time of day, the IV effect estimate should be interpreted with caution
Dust Temperatures in the Infrared Space Observatory Atlas of Bright Spiral Galaxies
We examine far-infrared and submillimeter spectral energy distributions for
galaxies in the Infrared Space Observatory Atlas of Bright Spiral Galaxies. For
the 71 galaxies where we had complete 60-180 micron data, we fit blackbodies
with lambda^-1 emissivities and average temperatures of 31 K or lambda^-2
emissivities and average temperatures of 22 K. Except for high temperatures
determined in some early-type galaxies, the temperatures show no dependence on
any galaxy characteristic. For the 60-850 micron range in eight galaxies, we
fit blackbodies with lambda^-1, lambda-2, and lambda^-beta (with beta variable)
emissivities to the data. The best results were with the lambda^-beta
emissivities, where the temperatures were ~30 K and the emissivity coefficient
beta ranged from 0.9 to 1.9. These results produced gas to dust ratios that
ranged from 150 to 580, which were consistent with the ratio for the Milky Way
and which exhibited relatively little dispersion compared to fits with fixed
emissivities.Comment: AJ, 2003, in pres
Developing an intervention to facilitate family communication about inherited genetic conditions, and training genetic counsellors in its delivery.
Many families experience difficulty in talking about an inherited genetic condition that affects one or more of them. There have now been a number of studies identifying the issues in detail, however few have developed interventions to assist families. The SPRinG collaborative have used the UK Medical Research Council's guidance on Developing and Evaluating Complex Interventions, to work with families and genetic counsellors (GCs) to co-design a psycho-educational intervention to facilitate family communication and promote better coping and adaptation to living with an inherited genetic condition for parents and their children (<18 years). The intervention is modelled on multi-family discussion groups (MFDGs) used in psychiatric settings. The MFDG was developed and tested over three phases. First focus groups with parents, young people, children and health professionals discussed whether MFDG was acceptable and proposed a suitable design. Using evidence and focus group data, the intervention and a training manual were developed and three GCs were trained in its delivery. Finally, a prototype MFDG was led by a family therapist and co-facilitated by the three GCs. Data analysis showed that families attending the focus groups and intervention thought MFDG highly beneficial, and the pilot sessions had a significant impact on their family' functioning. We also demonstrated that it is possible to train GCs to deliver the MFDG intervention. Further studies are now required to test the feasibility of undertaking a definitive randomised controlled trial to evaluate its effectiveness in improving family outcomes before implementing into genetic counselling practice.The National Institute of Health Research funded the study but any views expressed do not necessarily reflect those of the Authority. Funded by NIHR reference number: RP-DG-1211-10015
A Bayesian approach to the modelling of alpha Cen A
Determining the physical characteristics of a star is an inverse problem
consisting in estimating the parameters of models for the stellar structure and
evolution, knowing certain observable quantities. We use a Bayesian approach to
solve this problem for alpha Cen A, which allows us to incorporate prior
information on the parameters to be estimated, in order to better constrain the
problem. Our strategy is based on the use of a Markov Chain Monte Carlo (MCMC)
algorithm to estimate the posterior probability densities of the stellar
parameters: mass, age, initial chemical composition,... We use the stellar
evolutionary code ASTEC to model the star. To constrain this model both seismic
and non-seismic observations were considered. Several different strategies were
tested to fit these values, either using two or five free parameters in ASTEC.
We are thus able to show evidence that MCMC methods become efficient with
respect to more classical grid-based strategies when the number of parameters
increases. The results of our MCMC algorithm allow us to derive estimates for
the stellar parameters and robust uncertainties thanks to the statistical
analysis of the posterior probability densities. We are also able to compute
odds for the presence of a convective core in alpha Cen A. When using
core-sensitive seismic observational constraints, these can raise above ~40%.
The comparison of results to previous studies also indicates that these seismic
constraints are of critical importance for our knowledge of the structure of
this star.Comment: 21 pages, 6 figures, to be published in MNRA
Conservation physiology of animal migration
Migration is a widespread phenomenon among many taxa. This complex behaviour enables animals to exploit many temporally productive and spatially discrete habitats to accrue various fitness benefits (e.g. growth, reproduction, predator avoidance). Human activities and global environmental change represent potential threats to migrating animals (from individuals to species), and research is underway to understand mechanisms that control migration and how migration responds to modern challenges. Focusing on behavioural and physiological aspects of migration can help to provide better understanding, management and conservation of migratory populations. Here, we highlight different physiological, behavioural and biomechanical aspects of animal migration that will help us to understand how migratory animals interact with current and future anthropogenic threats. We are in the early stages of a changing planet, and our und
Optical Counterparts for 70,000 Radio Sources: APM Identifications for the FIRST Radio Survey
We describe a program to identify optical counterparts to radio sources from
the VLA FIRST survey using the Cambridge APM scans of the POSS-I plates. We use
radio observations covering 4150 square degrees of the north Galactic cap to a
20 cm flux density threshold of 1.0 mJy; the 382,892 sources detected all have
positional uncertainties of <1" (radius of 90% confidence). Our description of
the APM catalog, derived from the 148 POSS-I O and E plates covering this
region, includes an assessment of its astrometric and photometric accuracy, a
photometric recalibration using the Minnesota APS catalog, a discussion of the
classification algorithm, and quantitative tests of the catalog's reliability
and completeness. We go on to show how the use of FIRST sources as astrometric
standards allows us to improve the absolute astrometry of the POSS plates by
nearly an order of magnitude to ~0.15" rms. Matching the radio and optical
catalogs yields counterparts for over 70,000 radio sources; we include detailed
discussions of the reliability and completeness of these identifications as a
function of optical and radio morphology, optical magnitude and color, and
radio flux density. An analysis of the problem of radio sources with complex
morphologies (e.g., double-lobed radio galaxies) is included. We conclude with
a brief discussion of the source classes represented among the radio sources
with identified counterparts.Comment: Accepted for publication in ApJ; 28 pages, 23 figure
Photometric Classification of 2315 Pan-STARRS1 Supernovae with Superphot
The classification of supernovae (SNe) and its impact on our understanding of explosion physics and progenitors have traditionally been based on the presence or absence of certain spectral features. However, current and upcoming wide-field time-domain surveys have increased the transient discovery rate far beyond our capacity to obtain even a single spectrum of each new event. We must therefore rely heavily on photometric classification— connecting SN light curves back to their spectroscopically defined classes. Here, we present Superphot, an opensource Python implementation of the machine-learning classification algorithm of Villar et al., and apply it to 2315 previously unclassified transients from the Pan-STARRS1 Medium Deep Survey for which we obtained spectroscopic host-galaxy redshifts. Our classifier achieves an overall accuracy of 82%, with completenesses and purities of >80% for the best classes (SNe Ia and superluminous SNe). For the worst performing SN class (SNe Ibc), the completeness and purity fall to 37% and 21%, respectively. Our classifier provides 1257 newly classified SNe Ia, 521 SNe II, 298 SNe Ibc, 181 SNe IIn, and 58 SLSNe. These are among the largest uniformly observed samples of SNe available in the literature and will enable a wide range of statistical studies of each class
Roadmap on inorganic perovskites for energy applications
Authors thank EPSRC (EP/P007821/1) and Low Emissions Resources Global for support.Inorganic perovskites exhibit many important physical properties such as ferroelectricity, magnetoresistance and superconductivity as well their importance as Energy Materials. Many of the most important energy materials are inorganic perovskites and find application in batteries, fuel cells, photocatalysts, catalysis, thermoelectrics and solar thermal. In all these applications, perovskite oxides, or their derivatives offer highly competitive performance, often state of the art and so tend to dominate research into energy material. In the following sections, we review these functionalities in turn seeking to facilitate the interchange of ideas between domains. The potential for improvement is explored and we highlight the importance of both detailed modelling and in situ and operando studies in taking these materials forward.Publisher PDFPeer reviewe
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