15,584 research outputs found
Top quark forward-backward asymmetry and charge asymmetry in left-right twin Higgs model
In order to explain the Tevatron anomaly of the top quark forward-backward
asymmetry in the left-right twin Higgs model, we choose to give up
the lightest neutral particle of field as a stable dark matter
candidate. Then a new Yukawa interaction for is allowed, which can be
free from the constraint of same-sign top pair production and contribute
sizably to . Considering the constraints from the production rates of
the top pair (), the top decay rates and invariant mass
distribution, we find that this model with such new Yukawa interaction can
explain measured at the Tevatron while satisfying the charge
asymmetry measured at the LHC.Moreover, this model predicts a
strongly correlation between at the LHC and at the
Tevatron, i.e., increases as increases.Comment: 17 pages, 9 figures; matches the published versio
Spectral Representation Theory for Dielectric Behavior of Nonspherical Cell Suspensions
Recent experiments revealed that the dielectric dispersion spectrum of
fission yeast cells in a suspension was mainly composed of two sub-dispersions.
The low-frequency sub-dispersion depended on the cell length, while the
high-frequency one was independent of it. The cell shape effect was simulated
by an ellipsoidal cell model but the comparison between theory and experiment
was far from being satisfactory. Prompted by the discrepancy, we proposed the
use of spectral representation to analyze more realistic cell models. We
adopted a shell-spheroidal model to analyze the effects of the cell membrane.
It is found that the dielectric property of the cell membrane has only a minor
effect on the dispersion magnitude ratio and the characteristic frequency
ratio. We further included the effect of rotation of dipole induced by an
external electric field, and solved the dipole-rotation spheroidal model in the
spectral representation. Good agreement between theory and experiment has been
obtained.Comment: 19 pages, 5 eps figure
Glassy Dynamics in a Frustrated Spin System: Role of Defects
In an effort to understand the glass transition, the kinetics of a spin model
with frustration but no quenched randomness has been analyzed. The
phenomenology of the spin model is remarkably similiar to that of structural
glasses. Analysis of the model suggests that defects play a major role in
dictating the dynamics as the glass transition is approached.Comment: 9 pages, 5 figures, accepted in J. Phys.: Condensed Matter,
proceedings of the Trieste workshop on "Unifying Concepts in Glass Physics
Zero-temperature criticality in the two-dimensional gauge glass model
The zero-temperature critical state of the two-dimensional gauge glass model
is investigated. It is found that low-energy vortex configurations afford a
simple description in terms of gapless, weakly interacting vortex-antivortex
pair excitations. A linear dielectric screening calculation is presented in a
renormalization group setting that yields a power-law decay of spin-wave
stiffness with distance. These properties are in agreement with low-temperature
specific heat and spin-glass susceptibility data obtained in large-scale
multi-canonical Monte Carlo simulations.Comment: 4 pages, 4 figure
Development of hot drawing process for nitinol tube
In recent years, Nitinol, near-equiatomic nickel-titanium alloys, have found growing applications in medical technology and joining technology, due to their special characteristics such as shape memory, superplasticity and biocompatibility. The production of Nitinol tube cost-effectively remains a technical challenge. In this paper, we describe a hot drawing process for Nitinol tube production. A Nitinol tube blank and a metal core are assembled together. The assembly is hot drawn for several passes to a final diameter. The metal core is then plastically stretched to reduce its diameter and removed from the tube. Hot drawing process has been applied to Ni50.7Ti and Ni47Ti44Nb9 alloys. Nitinol tubes of 13.6 mm outer diameter and 1 mm wall thickness have been successfully produced from a tube blank of 20 mm outer diameter and 3.5 mm thickness
-meson in nuclear matter
The -nucleon (N) interactions are deduced from the heavy baryon
chiral perturbation theory up to the next-to-leading-order terms. Combining the
relativistic mean-field theory for nucleon system, we have studied the
in-medium properties of -meson. We find that all the elastic scattering
N interactions come from the next-to-leading-order terms. The N
sigma term is found to be about 280130 MeV. The off-shell terms are also
important to the in-medium properties of -meson. On application of the
latest determination of the N scattering length, the ratio of
-meson effective mass to its vacuum value is near , while
the optical potential is about MeV, at the normal nuclear density.Comment: 8 pages, 3 figures, to appear in PRC, many modification
Healthcare data mining: predicting inpatient length of stay
Data mining approaches have been widely applied in the field of healthcare. At the same time it is recognized that most healthcare datasets are full of missing values. In this paper we apply decision trees, Naive Bayesian classifiers and feature selection methods to a geriatric hospital dataset in order to predict inpatient length of stay, especially for the long stay patients
Dielectric Behavior of Nonspherical Cell Suspensions
Recent experiments revealed that the dielectric dispersion spectrum of
fission yeast cells in a suspension was mainly composed of two sub-dispersions.
The low-frequency sub-dispersion depended on the cell length, whereas the
high-frequency one was independent of it. The cell shape effect was
qualitatively simulated by an ellipsoidal cell model. However, the comparison
between theory and experiment was far from being satisfactory. In an attempt to
close up the gap between theory and experiment, we considered the more
realistic cells of spherocylinders, i.e., circular cylinders with two
hemispherical caps at both ends. We have formulated a Green function formalism
for calculating the spectral representation of cells of finite length. The
Green function can be reduced because of the azimuthal symmetry of the cell.
This simplification enables us to calculate the dispersion spectrum and hence
access the effect of cell structure on the dielectric behavior of cell
suspensions.Comment: Preliminary results have been reported in the 2001 March Meeting of
the American Physical Society. Accepted for publications in J. Phys.:
Condens. Matte
Multiband effects on beta-FeSe single crystals
We present the upper critical fields Hc2(T) and Hall effect in beta-FeSe
single crystals. The Hc2(T) increases as the temperature is lowered for field
applied parallel and perpendicular to (101), the natural growth facet of the
crystal. The Hc2(T) for both field directions and the anisotropy at low
temperature increase under pressure. Hole carriers are dominant at high
magnetic fields. However, the contribution of electron-type carriers is
significant at low fields and low temperature. Our results show that multiband
effects dominate Hc2(T) and electronic transport in the normal state
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