5,387 research outputs found
Solutions of the Yang-Baxter equation: descendants of the six-vertex model from the Drinfeld doubles of dihedral group algebras
The representation theory of the Drinfeld doubles of dihedral groups is used
to solve the Yang-Baxter equation. Use of the 2-dimensional representations
recovers the six-vertex model solution. Solutions in arbitrary dimensions,
which are viewed as descendants of the six-vertex model case, are then obtained
using tensor product graph methods which were originally formulated for quantum
algebras. Connections with the Fateev-Zamolodchikov model are discussed.Comment: 34 pages, 2 figure
Landau Collision Integral Solver with Adaptive Mesh Refinement on Emerging Architectures
The Landau collision integral is an accurate model for the small-angle
dominated Coulomb collisions in fusion plasmas. We investigate a high order
accurate, fully conservative, finite element discretization of the nonlinear
multi-species Landau integral with adaptive mesh refinement using the PETSc
library (www.mcs.anl.gov/petsc). We develop algorithms and techniques to
efficiently utilize emerging architectures with an approach that minimizes
memory usage and movement and is suitable for vector processing. The Landau
collision integral is vectorized with Intel AVX-512 intrinsics and the solver
sustains as much as 22% of the theoretical peak flop rate of the Second
Generation Intel Xeon Phi, Knights Landing, processor
Exploring Health and Health Education Participation of African American Fathers
In recent years, there has been increased attention to the importance of a healthy lifestyle. However, health indicators continue to support a decline in the overall health status of African American men. Studies have adequately explained adults‘ education participation motivations; few have explored African American men‘s motivations to participate in health educational programs. The purpose of this study was to explore African American men‘s motivations for participating in health education. Using focus group interviews, we identified themes which explain their motivations for participation. We discuss three primary health education motivations of African American men. The findings can assist program planners and health educators in developing recruiting strategies and attracting African American men to participate in health education programs thereby enhancing their overall health. Key Words: African American fathers, Health Education, Motivation, Participation
Stable isotope evidence of meat eating and hunting specialization in adult male chimpanzees
Observations of hunting and meat eating in our closest living relatives, chimpanzees (Pan troglodytes), suggest that among primates, regular inclusion of meat in the diet is not a characteristic unique to Homo. Wild chimpanzees are known to consume vertebrate meat, but its actual dietary contribution is, depending on the study population, often either unknown or minimal. Constraints on continual direct observation throughout the entire hunting season mean that behavioral observations are limited in their ability to accurately quantify meat consumption. Here we present direct stable isotope evidence supporting behavioral observations of frequent meat eating among wild adult male chimpanzees (Pan troglodytes verus) in Taï National Park, Côte d’Ivoire. Meat eating among some of the male chimpanzees is significant enough to result in a marked isotope signal detectable on a short-term basis in their hair keratin and long-term in their bone collagen. Although both adult males and females and juveniles derive their dietary protein largely from daily fruit and seasonal nut consumption, our data indicate that some adult males also derive a large amount of dietary protein from hunted meat. Our results reinforce behavioral observations of male-dominated hunting and meat eating in adult Taï chimpanzees, suggesting that sex differences in food acquisition and consumption may have persisted throughout hominin evolution, rather than being a recent development in the human lineage
Structure Formation Inside Triaxial Dark Matter Halos: Galactic Disks, Bulges and Bars
We investigate the formation and evolution of galactic disks immersed in
assembling live DM halos. Disk/halo components have been evolved from the
cosmological initial conditions and represent the collapse of an isolated
density perturbation. The baryons include gas (which participates in star
formation [SF]) and stars. The feedback from the stellar energy release onto
the ISM has been implemented. We find that (1) The growing triaxial halo figure
tumbling is insignificant and the angular momentum (J) is channeled into the
internal circulation; (2) Density response of the disk is out of phase with the
DM, thus diluting the inner halo flatness and washing out its prolateness; (3)
The total J is neathly conserved, even in models accounting for feedback; (4)
The specific J for the DM is nearly constant, while that for baryons is
decreasing; (5) Early stage of disk formation resembles the cat's cradle -- a
small amorphous disk fueled via radial string patterns; (6) The initially
puffed up gas component in the disk thins when the SF rate drops below ~5
Mo/yr; (7) About 40%-60% of the baryons remain outside the SF region; (8)
Rotation curves appear to be flat and account for the observed disk/halo
contributions; (9) A range of bulge-dominated to bulgeless disks was obtained;
Lower density threshold for SF leads to a smaller, thicker disk; Gravitational
softening in the gas has a substantial effect on various aspects of galaxy
evolution and mimics a number of intrinsic processes within the ISM; (10) The
models are characterized by an extensive bar-forming activity; (11) Nuclear
bars, dynamically coupled and decoupled form in response to the gas inflow
along the primary bars.Comment: 18 pages, 16 figures, accepted by the Astrophysical Journal. Minor
revisions. The high-resolution figures can be found at
http://www.pa.uky.edu/~shlosman/research/galdyn/figs07a
Universal Baxterization for -graded Hopf algebras
We present a method for Baxterizing solutions of the constant Yang-Baxter
equation associated with -graded Hopf algebras. To demonstrate the
approach, we provide examples for the Taft algebras and the quantum group
.Comment: 8 page
Thermionic Emission, Multielectron Bubbles, and A Novel Electron Collector in a Liquid Helium Environment
We study two techniques to create electrons in a liquid helium environment.
One is thermionic emission of tungsten filaments in a low temperature cell in
the vapor phase with a superfluid helium film covering all surfaces; the other
is operating a glowing filament immersed in bulk liquid helium. We present both
the steady state and rapid sweep I-V curves and the electron current yield.
These curves, having a negative dynamic resistance region, differ remarkably
from those of a vacuum tube filament. A novel low temperature vapor-phase
electron collector for which the insulating helium film on the collector
surface can be removed is used to measure emission current. We also discuss our
achievement of producing multi-electron bubbles (MEBs) in liquid helium by a
new method.Comment: 28 pages, 7 figure
Optical control over transmission of terahertz radiation through arrays of subwavelength holes of varying size
Thomas Henry Isaac, J. Gómez Rivas, and Euan Hendry, Physical Review B, Vol. 80, article 193412 (2009). "Copyright © 2009 by the American Physical Society."We modulate the transmission of terahertz (THz) radiation through periodic arrays of subwavelength holes in a metallic film by using pulses of visible-wavelength light to photoexcite the semiconducting substrate of the hole arrays. By varying the photodoping level of the semiconductor we are able to switch off the resonant transmission of THz radiation through the array. By varying the size of the holes, we demonstrate the crucial role that surface modes play in the resonant transmission and ultimately in the photomodulation behavior of these structures. We demonstrate that the surface-wave transmission mechanism can allow for very efficient optical modulation of radiation transmission
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