7,855 research outputs found
Project OASIS: The Design of a Signal Detector for the Search for Extraterrestrial Intelligence
An 8 million channel spectrum analyzer (MCSA) was designed the meet to meet the needs of a SETI program. The MCSA puts out a very large data base at very high rates. The development of a device which follows the MCSA, is presented
Morphosemantic Categories in Chinese: An Interim Report
This paper applies the notion of the homonerae - a sub-morphemic semantic unit - to the morphosemantic analysis of Cantonese. A number of major morphosemantic categories and subcategories in Chinese are identified through analysis of monomorphemic lexical items. The morphosemantic approach adopted is related to the 'shengxun' branch of traditional Chinese linguistics
The Role of Subsurface Flows in Solar Surface Convection: Modeling the Spectrum of Supergranular and Larger Scale Flows
We model the solar horizontal velocity power spectrum at scales larger than
granulation using a two-component approximation to the mass continuity
equation. The model takes four times the density scale height as the integral
(driving) scale of the vertical motions at each depth. Scales larger than this
decay with height from the deeper layers. Those smaller are assumed to follow a
Kolomogorov turbulent cascade, with the total power in the vertical convective
motions matching that required to transport the solar luminosity in a mixing
length formulation. These model components are validated using large scale
radiative hydrodynamic simulations. We reach two primary conclusions: 1. The
model predicts significantly more power at low wavenumbers than is observed in
the solar photospheric horizontal velocity spectrum. 2. Ionization plays a
minor role in shaping the observed solar velocity spectrum by reducing
convective amplitudes in the regions of partial helium ionization. The excess
low wavenumber power is also seen in the fully nonlinear three-dimensional
radiative hydrodynamic simulations employing a realistic equation of state.
This adds to other recent evidence suggesting that the amplitudes of large
scale convective motions in the Sun are significantly lower than expected.
Employing the same feature tracking algorithm used with observational data on
the simulation output, we show that the observed low wavenumber power can be
reproduced in hydrodynamic models if the amplitudes of large scale modes in the
deep layers are artificially reduced. Since the large scale modes have reduced
amplitudes, modes on the scale of supergranulation and smaller remain important
to convective heat flux even in the deep layers, suggesting that small scale
convective correlations are maintained through the bulk of the solar convection
zone.Comment: 36 pages, 6 figure
Does responsibility affect the public valuation of health care interventions? A relative valuation approach to health care safety
This article is available open access through the publisherâs website at the link below. Copyright © 2012, International Society for Pharmacoeconomics and
Outcomes Research (ISPOR).Objective - Health services often spend more on safety interventions than seems cost-effective. This study investigates whether the public value safety-related health care improvements more highly than the same improvements in contexts where the health care system is not responsible.
Method - An online survey was conducted to elicit the relative importance placed on preventing harms caused by 1) health care (hospital-acquired infections, drug administration errors, injuries to health care staff), 2) individuals (personal lifestyle choices, sports-related injuries), and 3) nature (genetic disorders). Direct valuations were obtained from members of the public by using a person trade-off or âmatchingâ method. Participants were asked to choose between two preventative interventions of equal cost and equal health benefit per person for the same number of people, but differing in causation. If participants indicated a preference, their strength of preference was measured by using person trade-off.
Results - Responses were obtained from 1030 people, reflecting the sociodemographic mix of the UK population. Participants valued interventions preventing hospital-acquired infections (1.31) more highly than genetic disorders (1.0), although drug errors were valued similarly to genetic disorders (1.07), and interventions to prevent injury to health care staff were given less weight than genetic disorders (0.71). Less weight was also given to interventions related to lifestyle (0.65) and sports injuries (0.41).
Conclusion - Our results suggest that people do not attach a simple fixed premium to âsafety-relatedâ interventions but that preferences depend more subtly on context. The use of the results of such public preference surveys to directly inform policy would therefore be premature.Brunel University
Nitrogen hydrides in interstellar gas: Herschel/HIFI observations towards G10.6-0.4 (W31C)
The HIFI instrument on board the Herschel Space Observatory has been used to observe interstellar nitrogen hydrides along the sight-line towards
G10.6â0.4 in order to improve our understanding of the interstellar chemistry of nitrogen. We report observations of absorption in NH N = 1 â 0,
J = 2 â 1 and ortho-NH_2 1_(1,1) â 0_(0,0). We also observed ortho-NH_3 1_0 â 0_0, and 2_0 â 1_0, para-NH_3 2_1 â 1_1, and searched unsuccessfully for
NH^+. All detections show emission and absorption associated directly with the hot-core source itself as well as absorption by foreground material
over a wide range of velocities. All spectra show similar, non-saturated, absorption features, which we attribute to diffuse molecular gas. Total
column densities over the velocity range 11â54 km s^(â1) are estimated. The similar profiles suggest fairly uniform abundances relative to hydrogen,
approximately 6 Ă 10^(â9), 3 Ă 10^(â9), and 3 Ă 10^(â9) for NH, NH_2, and NH_3, respectively. These abundances are discussed with reference to models of
gas-phase and surface chemistry
Ultrasonic Wave Propagation in a Tooth Phantom
Although ultrasonic energy has been used widely for general medical diagnostic purposes and as a tool for the nondestructive inspection of engineering components, a lack of understanding of the fundamental wave propagation phenomena in teeth has largely precluded its application to dentistry. This paper studies the physics of ultrasound/teeth interactions. Based on the authorsâ experience with the detection of defec engineering materials using ultrasound and the development of finite element computer code to study the wave propagation, initial studies have already been made on a tooth phantom. Results indicate that this numerical model can indeed be used to study the complex ultrasound interactions with dental anomalies, such as pulpitis and abscesses, and that such results could be used to optimize the design of appropriate transducers and equipment for dentistry applications. The primary reason why this technique is important and should take place is that ultrasonography has a great advantage over the presently available X-ray technology in that it does put any strain on the patient nor does it cause any pain. Most importantly, ultrasonic waves are nonionizing which, when used at low sound intensity levels, do not cause any health risks to the patient nor to the operator
Shaft mount for data coupler system
A device for mounting a data transmission apparatus to a rotating, tapered, and instrumented shaft is provided. This device permits attachment without interfering with shaft rotation or the accuracy of data output, and prevents both radial and axial slippage of the data transmission apparatus. The mounting device consists of a sleeve assembly which is attached to the shaft by means of clamps that are situated at some distance removed from the instrumented area of the shaft. The data transmission device is secured to the sleeve such that the entire assembly rotates with the shaft. Shim adjustments between sleeve sections assure that a minimum compressive load is transferred to the instrumented area of the shaft and a rubber lining is affixed to a large portion of the interior surface of the sleeve to absorb vibration
The role of concern about falling on stepping performance during complex activities
Background There is limited understanding of the underlying mechanisms explaining the role of concern about falling on fall risk in older people. Anxiety is known to interact with cognitive resources and, as people get older, they require more cognitive resources to maintain balance. This might affect an individual's ability to perform cognitive-motor tasks concurrently. The aim of this study was to investigate the effect of a visuospatial dual-task on stepping performance in older people with and without concern about falling and the impact of repeating this task in those with high concern about falling. Methods Three-hundred-eight community-dwelling older people, aged 70 to 90 years old, participated in the study. Participants were asked to perform a Choice Stepping Reaction Time (CSRT) task in two conditions; once without any other tasks (single task condition), and once while simultaneously performing a visuospatial task (dual-task condition). Participants were asked to rate their levels of concern and confidence specifically related to each of the 25 stepping trials (before/after). We also measured general concern about falling, affect, and sensorimotor and cognitive functioning. Results Total stepping reaction times increased when participants also performed the visuospatial task. The relation between general concern about falling and stepping reaction time, was affected by sensorimotor and executive functioning. Generalised linear mixed models showed that the group with moderate to high levels of general concern about falling had slower total stepping reaction times than those with lower levels of concern about falling, especially during the dual-task condition. Individuals with greater general concern about falling showed reduced confidence levels about whether they could do the stepping tasks under both conditions. Repeatedly performing the stepping task reduced the immediate task-specific concern about falling levels and increased confidence in all participants. Conclusions These findings reveal that people with higher general concern about falling experienced more difficulties during a dual-task condition than people with lower levels of concern. Of further interest, better sensorimotor and cognitive functioning reduced this effect. Graded exposure has potential to reduce concern about falling during fear-evoking activities, especially in conjunction with therapies that improve balance, mood and cognitive function
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