19,264 research outputs found
On the Spatial Distribution of Hard X-Rays from Solar Flare Loops
The aim of this paper is to investigate the spatial structure of the
impulsive phase hard X-ray emission from solar flares. This work is motivated
by the YOHKOH and the forthcoming HESSI observations. Summarizing past results,
it is shown that the transport effects can account for the observations by
inhomogeneous loops where there is a strong field convergence and/or density
enhancement at the top of the flaring loop. Scattering by plasma turbulence at
the acceleration site or pancake type pitch angle distribution of the
accelerated electrons can also give rise to enhanced emission at the loop tops.
These could be a natural consequence of acceleration by plasma waves. This
paper considers a general case of stochastic scattering and acceleration that
leads to an isotropic pitch angle distribution and an enhanced emission from
the loop tops or the acceleration site.
Following the formalism developed in earlier papers the strength and the
spectrum of the radiation expected from the acceleration site and the foot
points are evaluated and their dependence on the parameters describing the
acceleration process and the flare plasma are determined. The theoretical ratio
of these two intensities and relative values of their spectral indices are
compared with the YOHKOH observations, demonstrating that the above mentioned
parameters can be constrained with such observations. It is shown that future
high spatial and spectral resolution observations, for example those expected
from HESSI, can begin to distinguish between different models and constrain
their parameters.Comment: 37 pages with 20 figures. Accepted for publication in ApJ
http://www.astronomy.stanford.ed
The prevalence of Type 2 diabetes and its associated health problems in a community-dwelling elderly population.
AIMS: Prevalence estimates of Type 2 diabetes and its associated health problems in elderly populations are rare, especially in the very elderly. METHODS: A sample of 15 095 community-dwelling older people aged > or = 75 years were assessed. Type 2 diabetes and associated health problems were identified using self-reporting, general practitioner records, drug histories, and blood and urine measurements. RESULTS: There were 1177 people identified as having Type 2 diabetes mellitus, giving an overall prevalence of 7.8% (95% confidence interval 7.1, 8.5), 9.4% (8.4, 10.5) for men and 6.8% (6.1, 7.6) for women. The age, sex and smoking adjusted odds ratios for various health problems, comparing people with and without diabetes were: low vision 1.6 (1.3, 1.9), proteinuria 1.7 (1.4, 2.1), chronic kidney disease stage 4 or 5 1.5 (1.0, 2.1), angina 1.3 (1.1, 1.6), myocardial infarction 1.5 (1.2, 1.8), cerebrovascular event 2.0 (1.8, 2.1) and foot ulceration 1.7 (1.2, 2.4). CONCLUSIONS: The prevalence of Type 2 diabetes is not high in community-dwelling older people, but diabetes was a contributory factor to a number of health problems
Annoyance resulting from intrusion of aircraft sounds upon various activities
An experiment was conducted in which subjects were engaged in TV viewing, telephone listening, or reverie (no activity) for a 1/2-hour session. During the session, they were exposed to a series of recorded aircraft sounds at the rate of one flight every 2 minutes. Within each session, four levels of flyover noise, separated by dB increments, were presented several times in a Latin Square balanced sequence. The peak level of the noisiest flyover in any session was fixed at 95, 90, 85, 75, or 70 dBA. At the end of the test session, subjects recorded their responses to the aircraft sounds, using a bipolar scale which covered the range from very pleasant to extremely annoying. Responses to aircraft noises were found to be significantly affected by the particular activity in which the subjects were engaged. Not all subjects found the aircraft sounds to be annoying
Effects of three activities on annoyance responses to recorded flyovers
Human subjects participated in an experiment in which they were engaged in TV viewing, telephone listening, or reverie (no activity) for a 1/2-hour session. During the session, they were exposed to a series of recorded aircraft sounds at the rate of one flight every 2 minutes. At each session, four levels of flyover noise, separated by 5 db increments were presented several times in a Latin Square balanced sequence. The peak levels of the noisiest flyover in any session was fixed at 95, 90, 85, 75, or 70 db. At the end of the test session, subjects recorded their responses to the aircraft sounds, using a bipolar scale which covered the range from very pleasant to extremely annoying. Responses to aircraft noises are found to be significantly affected by the particular activity in which the subjects are engaged
Question design in nurse-led and GP-led telephone triage for same-day appointment requests: a comparative investigation
Objective: To compare doctorsâ and nursesâ communication with patients in primary care telephone triage consultations. Design: Qualitative comparative study of content and form of questions in 51 telephone triage encounters between practitioners (general practitioners (GPs)=29; nurses=22) and patients requesting a same-day appointment in primary care. Audio-recordings of nurse-led calls were synchronised with video recordings of nurse's use of computer decision support software (CDSS) during triage. Setting: 2 GP practices in Devon and Warwickshire, UK. Participants: 4 GPs and 29 patients; and 4 nurses and 22 patients requesting a same-day face-to-face appointment with a GP. Main outcome measure: Form and content of practitioner-initiated questions and patient responses during clinical assessment. Results: A total of 484 questionâresponse sequences were coded (160 GP; 324 N). Despite average call lengths being similar (GP=4â
min, 37â
s, (SD=1â
min, 26â
s); N=4â
min, 39â
s, (SD=2â
min, 22â
s)), GPs and nurses differed in the average number (GP=5.51, (SD=4.66); N=14.72, (SD=6.42)), content and form of questions asked. A higher frequency of questioning in nurse-led triage was found to be due to nursesâ use of CDSS to guide telephone triage. 89% of nurse questions were oriented to asking patients about their reported symptoms or to wider-information gathering, compared to 54% of GP questions. 43% of GP questions involved eliciting patient concerns or expectations, and obtaining details of medical history, compared to 11% of nurse questions. Nurses using CDSS frequently delivered questions designed as declarative statements requesting confirmation and which typically preferred a âno problemâ response. In contrast, GPs asked a higher proportion of interrogative questions designed to request information. Conclusions: Nurses and GPs emphasise different aspects of the clinical assessment process during telephone triage. These different styles of triage have implications for the type of information available following nurse-led or doctor-led triage, and for how patients experience triage
Weld procedure produces quality welds for thick sections of Hastelloy-X
Welding program produces premium quality, multipass welds in heavy tube sections of Hastelloy-X. It develops semiautomatic tungsten/inert gas procedures, weld wire procurement specifications material weld properties, welder-operator training, and nondestructive testing inspection techniques and procedures
Omega time transmissions and receiving requirements
A short history is given of the development of dual VLF time transmission techniques. The theory of time recovery from the relative phase of the dual frequency transmission is presented. The transmission and receiving requirements for cycle identification and cycle ambiguity resolution are described. Finally, an experiment to test the capability of time transmission of the OMEGA system is propose
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