3,252 research outputs found
H2 Formation on Interstellar Grains in Different Physical Regimes
An analysis of the kinetics of H2 formation on interstellar dust grains is
presented using rate equations. It is shown that semi-empirical expressions
that appeared in the literature represent two different physical regimes. In
particular, it is shown that the expression given by Hollenbach, Werner and
Salpeter [ApJ, 163, 165 (1971)] applies when high flux, or high mobility, of H
atoms on the surface of a grain, makes it very unlikely that H atoms evaporate
before they meet each other and recombine. The expression of Pirronello et al.\
[ApJ, 483, L131 (1997)] -- deduced on the basis of accurate measurements on
realistic dust analogue -- applies to the opposite regime (low coverage and low
mobility). The implications of this analysis for the understanding of the
processes dominating in the Interstellar Medium are discussed.Comment: 4 pages, MN styl
Design of a low cost earth resources system
The author has identified the following significant results. Survey results indicated that users of remote sensing data in the Southeastern U.S. were increasingly turning to digital processing techniques. All the states surveyed have had some involvement in projects using digitally processed data. Even those states which do not yet have in-house capabilities for digital processing were extremely interested in and were planning to develop such capabilities
Computer processing of peach tree decline data
There are no author-identified significant results in this report
Application of DWF to heavy-light mesons
We consider application of domain wall fermions to quarks with relatively
heavy masses, aiming at precision calculations of charmed meson properties.
Preliminary results for a few basic quantities are presented.Comment: Lattice2003(heavy), 3 pages, 3 figure
Orbit equivalence rigidity for ergodic actions of the mapping class group
We establish orbit equivalence rigidity for any ergodic, essentially free and
measure-preserving action on a standard Borel space with a finite positive
measure of the mapping class group for a compact orientable surface with higher
complexity. We prove similar rigidity results for a finite direct product of
mapping class groups as well.Comment: 11 pages, title changed, a part of contents remove
A new look at C*-simplicity and the unique trace property of a group
We characterize when the reduced C*-algebra of a group has unique tracial
state, respectively, is simple, in terms of Dixmier-type properties of the
group C*-algebra. We also give a simple proof of the recent result by
Breuillard, Kalantar, Kennedy and Ozawa that the reduced C*-algebra of a group
has unique tracial state if and only if the amenable radical of the group is
trivial.Comment: 8 page
Critical research and advanced technology (CRT) support project
A critical technology base for utility and industrial gas turbines by planning the use of coal-derived fuels was studied. Development tasks were included in the following areas: (1) Combustion - investigate the combustion of coal-derived fuels and methods to minimize the conversion of fuel-bound nitrogen to NOx; (2) materials - understand and minimize hot corrosion; (3) system studies - integrate and focus the technological efforts. A literature survey of coal-derived fuels was completed and a NOx emissions model was developed. Flametube tests of a two-stage (rich-lean) combustor defined optimum equivalence ratios for minimizing NOx emissions. Sector combustor tests demonstrated variable air control to optimize equivalence ratios over a wide load range and steam cooling of the primary zone liner. The catalytic combustion of coal-derived fuels was demonstrated. The combustion of coal-derived gases is very promising. A hot-corrosion life prediction model was formulated and verified with laboratory testing of doped fuels. Fuel additives to control sulfur corrosion were studied. The intermittent application of barium proved effective. Advanced thermal barrier coatings were developed and tested. Coating failure modes were identified and new material formulations and fabrication parameters were specified. System studies in support of the thermal barrier coating development were accomplished
Childhood environmental health concerns in Russia
Environmental Health Centre (EHC) is one of the few
Russian organisations responsible for the development of
environmental epidemiology and health risk assessment
methodologies in Russia. Being a WELL resource centre
network partner we considered the possibilities for environmental
interventions to address major causes of child
mortality and morbidity and environmental health concerns
in Russia. It was based on the results of the preliminary
scoping studies carried out by our Centre during May
– October 2002. The scoping studies themselves were
based on published and unpublished literature and on
consultations with key stakeholders
Quenched QCD with domain wall fermions
We report on simulations of quenched QCD using domain wall fermions, where we
focus on basic questions about the formalism and its ability to produce
expected low energy hadronic physics for light quarks. The work reported here
is on quenched lattices at and 5.85, using values
for the length of the fifth dimension between 10 and 48. We report results for
parameter choices which lead to the desired number of flavors, a study of
undamped modes in the extra dimension and hadron masses.Comment: Contribution to Lattice '98. Presented by R. Mawhinney. 3 pages, 3
figure
Dynamical QCD thermodynamics with domain wall fermions
We present results from numerical simulations of full, two flavor QCD
thermodynamics at N_t=4 with domain wall fermions. For the first time a
numerical simulation of the full QCD phase transition displays a low
temperature phase with spontaneous chiral symmetry breaking but intact flavor
symmetry and a high temperature phase with the full SU(2) x SU(2) chiral flavor
symmetry.Comment: LATTICE98(hightemp
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