2,038 research outputs found
Turbulence in nonabelian gauge theory
Kolmogorov wave turbulence plays an important role for the thermalization
process following plasma instabilities in nonabelian gauge theories. We show
that classical-statistical simulations in SU(2) gauge theory indicate a
Kolmogorov scaling exponent known from scalar models. In the range of validity
of resummed perturbation theory this result is shown to agree with analytical
estimates. We study the effect of classical-statistical versus quantum
corrections and demonstrate that the latter lead to the absence of turbulence
in the far ultraviolet.Comment: 13 pages, 4 figures. PLB version, improved statistics indicates
Kolmogorov exponent 4/
Insightful classification of crystal structures using deep learning
Computational methods that automatically extract knowledge from data are
critical for enabling data-driven materials science. A reliable identification
of lattice symmetry is a crucial first step for materials characterization and
analytics. Current methods require a user-specified threshold, and are unable
to detect average symmetries for defective structures. Here, we propose a
machine-learning-based approach to automatically classify structures by crystal
symmetry. First, we represent crystals by calculating a diffraction image, then
construct a deep-learning neural-network model for classification. Our approach
is able to correctly classify a dataset comprising more than 100 000 simulated
crystal structures, including heavily defective ones. The internal operations
of the neural network are unraveled through attentive response maps,
demonstrating that it uses the same landmarks a materials scientist would use,
although never explicitly instructed to do so. Our study paves the way for
crystal-structure recognition of - possibly noisy and incomplete -
three-dimensional structural data in big-data materials science.Comment: Nature Communications, in press (2018
Republican States Bolstered Their Health Insurance Rate Review Programs Using Incentives From the Affordable Care Act.
The Affordable Care Act (ACA) included financial and regulatory incentives and goals for states to bolster their health insurance rate review programs, increase their anticipated loss ratio requirements, expand Medicaid, and establish state-based exchanges. We grouped states by political party control and compared their reactions across these policy goals. To identify changes in states rate review programs and anticipated loss ratio requirements in the individual and small group markets since the ACAs enactment, we conducted legal research and contacted each states insurance regulator. We linked rate review program changes to the Centers for Medicare and Medicaid Services (CMS) criteria for an effective rate review program. We found, of states that did not meet CMSs criteria when the ACA was enacted, most made changes to meet those criteria, including Republican-controlled states, which generally oppose the ACA. This finding is likely the result of the relatively low administrative burden associated with reviewing health insurance rates and the fact that doing so prevents federal intervention in rate review. However, Republican-controlled states were less likely than non-Republican-controlled states to increase their anticipated loss ratio requirements to align with the federal retrospective medical loss ratio requirement, expand Medicaid, and establish state-based exchanges, because of their general opposition to the ACA. We conclude that federal incentives for states to strengthen their health insurance rate review programs were more effective than the incentives for states to adopt other insurance-related policy goals of the ACA
Quantum size effect in Pb(100) films: the role of symmetry and implication for film growth
We show from density-functional calculations that Pb(100) thin films exhibit
quantum size effect with a bilayer periodicity in film energies, film
relaxations, and work functions, which originate from different symmetry of the
stacking geometry of odd and even layer films. The bilayer periodicity of the
film energy is argued to survive on a semiconductor substrate, which should
allow the growth of ``magically'' thick even-layer Pb(100) films. Furthermore,
it is found that the quantum well states in a simple metal film can be
classified into -bonded and -bonded states, which quantize
independently
Accountable Care Organizations in California: Promise and Performance
California has more accountable care organizations (ACOs) than any other state in the country, with particularly rapid growth over the past two years. This report introduces new evidence that ACOs improve the quality of care, increase patient satisfaction, and may reduce costs
The steady-state of heterogeneous catalysis, studied by first-principles statistical mechanics
The turn-over frequency of the catalytic oxidation of CO at RuO2(110) was
calculated as function of temperature and partial pressures using ab initio
statistical mechanics. The underlying energetics of the gas-phase molecules,
dissociation, adsorption, surface diffusion, surface chemical reactions, and
desorption were obtained by all-electron density-functional theory. The
resulting CO2 formation rate [in the full (T, p_CO, p_O2)-space], the movies
displaying the atomic motion and reactions over times scales from picoseconds
to seconds, and the statistical analyses provide insights into the concerted
actions ruling heterogeneous catalysis and open thermodynamic systems in
general.Comment: 4 pages including 3 figures, Related publications can be found at
http://www.fhi-berlin.mpg.de/th/paper.htm
The stability of vicinal surfaces and the equilibrium crystal shape of Pb by first principles theory
The orientation-dependent surface energies of fcc Pb for more than 30 vicinal orientations, distributed over the [110] and [001] zones of the stereographic triangle, have been studied by density-functional theory. For bulk-truncated structures almost all vicinal surfaces are found to be unstable and would facet into (111) and (100) orientations. However, after surface relaxation, all vicinal surfaces are stable relative to faceting into (111) and (100) orientations. There are also regions of relaxed vicinal surfaces which will facet into nearby stable vicinal surfaces. Overall, surface relaxation significantly affects the equilibrium crystal shape (ECS) of Pb. In both the [110] and [001] crystallographic zones the (110), (112), (221), and (023) facets are found on the ECS only after relaxation, in addition to (111) and (100). This result is in agreement with the experimental ECS of Pb at 353 K. Step formation energies for various vicinal orientations are estimated from facet diameters of the theoretical ECS and compared with experimental data
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