5,868 research outputs found
Prevalence and clinical characteristics of left ventricular dysfunction among elderly patients in general practice setting: cross sectional survey
Objective: To assess the prevalence and clinical characteristics of left ventricular dysfunction among elderly patients in the general practice setting by echocardiographic assessment of ventricular function.
Design: Cross sectional survey.
Setting: Four centre general practice in Poole, Dorset.
Subjects: 817 elderly patients aged 70-84 years.
Main outcomes: Echocardiographic assessment of left ventricular systolic function including measurement of ejection fraction by biplane summation method where possible, clinical symptoms, and signs of left ventricular dysfunction.
Results: The overall prevalence of left ventricular systolic dysfunction was 7.5% (95% confidence interval 5.8% to 9.5%); mild dysfunction (5.0%) was considerably more prevalent than moderate (1.6%) or severe dysfunction (0.7%). Measurement of ejection fraction was possible in 82% of patients (n=667): in patients categorised as having mild, moderate, or severe dysfunction, the mean ejection fraction was 48% (SD 12.0), 38% (8.1), and 26% (7.9) respectively. At all ages the prevalence was much higher in men than in women (odds ratio 5.1, 95% confidence interval 2.6 to 10.1). No clinical symptom or sign was both sensitive and specific. In around half the patients with ventricular dysfunction (52%, 32/61) heart failure had not been previously diagnosed.
Conclusions: Unrecognised left ventricular dysfunction is a common problem in elderly patients in the general practice setting. Appropriate treatment with angiotensin converting enzyme inhibitors has the potential to reduce hospitalisation and mortality in these patients, but diagnosis should not be based on clinical history and examination alone. Screening is feasible in general practice, but it should not be implemented until the optimum method of identifying left ventricular dysfunction is clarified, and the cost effectiveness of screening has been shown
Irregular Satellites of the Planets: Products of Capture in the Early Solar System
All four giant planets in the Solar system possess irregular satellites,
characterized by large, highly eccentric and/or inclined orbits that are
distinct from the nearly circular, uninclined orbits of the regular satellites.
This difference can be traced directly to different modes of formation. Whereas
the regular satellites grew by accretion within circumplanetary disks the
irregular satellites were captured from initially heliocentric orbits at an
early epoch. Recently, powerful survey observations have greatly increased the
number of known irregular satellites, permitting a fresh look at the group
properties of these objects and motivating a re-examination of the mechanisms
of capture. None of the suggested mechanisms, including gas-drag, pull-down,
and three-body capture, convincingly fit the group characteristics of the
irregular satellites. The sources of the satellites also remain unidentified.Comment: 51 pages, 17 figures, 5 tables, to appear in ARAA 200
Divergence in Dialogue
Copyright: 2014 Healey et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.This work was supported by the Economic and Social Research Council (ESRC; http://www.esrc.ac.uk/) through the DynDial project (Dynamics of Conversational Dialogue, RES-062-23-0962) and the Engineering and Physical Sciences Research Council (EPSRC; http://www.epsrc.ac.uk/) through the RISER
project (Robust Incremental Semantic Resources for Dialogue, EP/J010383/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Measurement of nuclear effects in neutrino interactions with minimal dependence on neutrino energy
We present a phenomenological study of nuclear effects in neutrino
charged-current interactions, using transverse kinematic imbalances in
exclusive measurements. Novel observables with minimal dependence on neutrino
energy are proposed to study quasielastic scattering, and especially resonance
production. They should be able to provide direct constraints on nuclear
effects in neutrino- and antineutrino-nucleus interactions.Comment: 7 pages, 9 figures, accepted version by PR
Energy Flow in Acoustic Black Holes
We present the results of an analysis of superradiant energy flow due to
scalar fields incident on an acoustic black hole. In addition to providing
independent confirmation of the recent results in [5], we determine in detail
the profile of energy flow everywhere outside the horizon. We confirm
explicitly that in a suitable frame the energy flow is inward at the horizon
and outward at infinity, as expected on physical grounds.Comment: 8 pages, 9 figures, Comments added to discussion of energy flow and
introductory section abbreviate
Silicon on Ceramic Process: Silicon Sheet Growth and Device Development for the Large-area Silicon Sheet and Cell Development Tasks of the Low-cost Solar Array Project
The technical and economic feasibility of producing solar cell quality sheet silicon was investigated. It was hoped this could be done by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. Work was directed towards the solution of unique cell processing/design problems encountered with the silicon-ceramic (SOC) material due to its intimate contact with the ceramic substrate. Significant progress was demonstrated in the following areas; (1) the continuous coater succeeded in producing small-area coatings exhibiting unidirectional solidification and substatial grain size; (2) dip coater succeeded in producing thick (more than 500 micron) dendritic layers at coating speeds of 0.2-0.3 cm/sec; and (3) a standard for producing total area SOC solar cells using slotted ceramic substrates was developed
Machine-learning-based investigation of the variables affecting summertime lightning occurrence over the Southern Great Plains
Lightning is affected by many factors, many of which are not routinely measured, well understood, or accounted for in physical models. Several commonly used machine learning (ML) models have been applied to analyze the relationship between Atmospheric Radiation Measurement (ARM) data and lightning data from the Earth Networks Total Lightning Network (ENTLN) in order to identify important variables affecting lightning occurrence in the vicinity of the Southern Great Plains (SGP) ARM site during the summer months (June, July, August and September) of 2012 to 2020. Testing various ML models, we found that the random forest model is the best predictor among common classifiers. When convective clouds were detected, it predicts lightning occurrence with an accuracy of 76.9 % and an area under the curve (AUC) of 0.850. Using this model, we further ranked the variables in terms of their effectiveness in nowcasting lightning and identified geometric cloud thickness, rain rate and convective available potential energy (CAPE) as the most effective predictors. The contrast in meteorological variables between no-lightning and frequent-lightning periods was examined for hours with CAPE values conducive to thunderstorm formation. Besides the variables considered for the ML models, surface variables and mid-altitude variables (e.g., equivalent potential temperature and minimum equivalent potential temperature, respectively) have statistically significant contrasts between no-lightning and frequent-lightning hours. For example, the minimum equivalent potential temperature from 700 to 500 hPa is significantly lower during frequent-lightning hours compared with no-lightning hours. Finally, a notable positive relationship between the intracloud (IC) flash fraction and the square root of CAPE (CAPE) was found, suggesting that stronger updrafts increase the height of the electrification zone, resulting in fewer flashes reaching the surface and consequently a greater IC flash fraction.</p
Spontaneous Symmetry Breaking for Scalar QED with Non-minimal Chern-Simons Coupling
We investigate the two-loop effective potential for both minimally and
non-minimally coupled Maxwell-Chern-Simons theories. The non-minimal gauge
interaction represents the magnetic moment interaction between a charged scalar
and the electromagnetic field. In a previous paper we have shown that the two
loop effective potential for this model is renormalizable with an appropriate
choice of the non-minimal coupling constant. We carry out a detailed analysis
of the spontaneous symmetry breaking induced by radiative corrections. As long
as the renormalization point for all couplings is chosen to be the true minimum
of the effective potential, both models predict the presence of spontaneous
symmetry breaking. Two loop corrections are small compared to the one loop
result, and thus the symmetry breaking is perturbatively stable.Comment: Revtex 25 pages, 9 figure
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