7,169 research outputs found
Assessing alcohol intake & its dose-dependent effects on liver enzymes by 24-h recall and questionnaire using NHANES 2001-2010 data
Electron surface layer at the interface of a plasma and a dielectric wall
We study the potential and the charge distribution across the interface of a
plasma and a dielectric wall. For this purpose, the charge bound to the wall is
modelled as a quasi-stationary electron surface layer which satisfies Poisson's
equation and minimizes the grand canonical potential of the wall-thermalized
excess electrons constituting the wall charge. Based on an effective model for
a graded interface taking into account the image potential and the offset of
the conduction band to the potential just outside the dielectric, we
specifically calculate the potential and the electron distribution for
magnesium oxide, silicon dioxide and sapphire surfaces in contact with a helium
discharge. Depending on the electron affinity of the surface, we find two
vastly different behaviors. For negative electron affinity, electrons do not
penetrate into the wall and an external surface charge is formed in the image
potential, while for positive electron affinity, electrons penetrate into the
wall and a space charge layer develops in the interior of the dielectric. We
also investigate how the electron surface layer merges with the bulk of the
dielectric.Comment: 15 pages, 9 figures, accepted versio
Rotational symmetry of self-similar solutions to the Ricci flow
Let (M,g) be a three-dimensional steady gradient Ricci soliton which is
non-flat and \kappa-noncollapsed. We prove that (M,g) is isometric to the
Bryant soliton up to scaling. This solves a problem mentioned in Perelman's
first paper.Comment: Final version, to appear in Invent. Mat
The area of horizons and the trapped region
This paper considers some fundamental questions concerning marginally trapped
surfaces, or apparent horizons, in Cauchy data sets for the Einstein equation.
An area estimate for outermost marginally trapped surfaces is proved. The proof
makes use of an existence result for marginal surfaces, in the presence of
barriers, curvature estimates, together with a novel surgery construction for
marginal surfaces. These results are applied to characterize the boundary of
the trapped region.Comment: 44 pages, v3: small changes in presentatio
Observations of the quasi 2âday wave from the High Resolution Doppler Imager on Uars
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95387/1/grl7238.pd
Upending the Social Ecological Model to Guide Health Promotion Efforts Toward Policy and Environmental Change
Efforts to change policies and the environments in which people live, work, and play have gained increasing attention over the past several decades. Yet health promotion frameworks that illustrate the complex processes that produce health-enhancing structural changes are limited. Building on the experiences of health educators, community activists, and community-based researchers described in this supplement and elsewhere, as well as several political, social, and behavioral science theories, we propose a new framework to organize our thinking about producing policy, environmental, and other structural changes. We build on the social ecological model, a framework widely employed in public health research and practice, by turning it inside out, placing health-related and other social policies and environments at the center, and conceptualizing the ways in which individuals, their social networks, and organized groups produce a community context that fosters healthy policy and environmental development. We conclude by describing how health promotion practitioners and researchers can foster structural change by (1) conveying the health and social relevance of policy and environmental change initiatives, (2) building partnerships to support them, and (3) promoting more equitable distributions of the resources necessary for people to meet their daily needs, control their lives, and freely participate in the public sphere
Numerical simulation on detonation initiation and propagation in supersonic combustible mixtures with nonuniform species
Linear modeling of possible mechanisms for parkinson tremor generation
The power of Parkinson tremor is expressed in terms of possibly changed frequency response functions between relevant variables in the neuromuscular system. The derivation starts out from a linear loopless equivalent model of mechanisms for general tremor generation. Hypothetical changes in this model from the substrate of the disease are indicated, and possible ones are inferred from literature about experiments on patients. The result indicates that in these patients tremor appears to have been generated in loops, which did not include the brain area which in surgery usually is inactivated. For some patients in the literature, these loops could involve muscle length receptors, the static sensitivity of which may have been enlarged by pathological brain activity
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