28,125 research outputs found
Self-Diffusion in 2D Dusty Plasma Liquids: Numerical Simulation Results
We perform Brownian dynamics simulations for studying the self-diffusion in
two-dimensional (2D) dusty plasma liquids, in terms of both mean-square
displacement and velocity autocorrelation function (VAF). Super-diffusion of
charged dust particles has been observed to be most significant at infinitely
small damping rate for intermediate coupling strength, where the
long-time asymptotic behavior of VAF is found to be the product of and
. The former represents the prediction of early theories in
2D simple liquids and the latter the VAF of a free Brownian particle. This
leads to a smooth transition from super-diffusion to normal diffusion, and then
to sub-diffusion with an increase of the damping rate. These results well
explain the seemingly contradictory scattered in recent classical molecular
dynamics simulations and experiments of dusty plasmas.Comment: 10 pages 5 figures, accepted by PR
Eigenvalues of Ruijsenaars-Schneider models associated with root system in Bethe ansatz formalism
Ruijsenaars-Schneider models associated with root system with a
discrete coupling constant are studied. The eigenvalues of the Hamiltonian are
givein in terms of the Bethe ansatz formulas. Taking the "non-relativistic"
limit, we obtain the spectrum of the corresponding Calogero-Moser systems in
the third formulas of Felder et al [20].Comment: Latex file, 25 page
Swift, XMM-Newton, and NuSTAR observations of PSR J2032+4127/MT91 213
We report our recent Swift, NuSTAR, and XMM-Newton X-ray and Lijiang optical
observations on PSR J2032+4127/MT91 213, the gamma-ray binary candidate with a
period of 45-50 years. The coming periastron of the system was predicted to be
in November 2017, around which high-energy flares from keV to TeV are expected.
Recent studies with Chandra and Swift X-ray observations taken in 2015/16
showed that its X-ray emission has been brighter by a factors of ~10 than that
before 2013, probably revealing some on-going activities between the pulsar
wind and the stellar wind. Our new Swift/XRT lightcurve shows no strong
evidence of a single vigorous brightening trend, but rather several strong
X-ray flares on weekly to monthly timescales with a slowly brightening
baseline, namely the low state. The NuSTAR and XMM-Newton observations taken
during the flaring and the low states, respectively, show a denser environment
and a softer power-law index during the flaring state, implying that the pulsar
wind interacted with stronger stellar winds of the companion to produce the
flares. These precursors would be crucial in studying the predicted giant
outburst from this extreme gamma-ray binary during the periastron passage in
late 2017.Comment: 6 pages, including 3 figures and 2 tables. Accepted for publication
in Ap
Masses and Majorana fermions in graphene
We review the classification of all the 36 possible gap-opening instabilities
in graphene, i.e., the 36 relativistic masses of the two-dimensional Dirac
Hamiltonian when the spin, valley, and superconducting channels are included.
We then show that in graphene it is possible to realize an odd number of
Majorana fermions attached to vortices in superconducting order parameters if a
proper hierarchy of mass scales is in place.Comment: Contribution to the Proceedings of the Nobel symposium on graphene
and quantum matte
Wave spectra of 2D dusty plasma solids and liquids
Brownian dynamics simulations were carried out to study wave spectra of
two-dimensional dusty plasma liquids and solids for a wide range of
wavelengths. The existence of a longitudinal dust thermal mode was confirmed in
simulations, and a cutoff wavenumber in the transverse mode was measured.
Dispersion relations, resulting from simulations, were compared with those from
analytical theories, such as the random-phase approximation (RPA),
quasi-localized charged approximation (QLCA), and harmonic approximation (HA).
An overall good agreement between the QLCA and simulations was found for wide
ranges of states and wavelengths after taking into account the direct thermal
effect in the QLCA, while for the RPA and HA good agreement with simulations
were found in the high and low temperature limits, respectively.Comment: 26 pages, 9 figure
Gauge Field Fluctuations and First-Order Phase Transition in Color Superconductivity
We study the gauge field fluctuations in dense quark matter and determine the
temperature of the induced first-order phase transition to the
color-superconducting phase in weak coupling. We find that the local
approximation of the coupling between the gauge potential and the order
parameter, employed in the Ginzburg-Landau theory, has to be modified by
restoring the full momentum dependence of the polarization function of gluons
in the superconducting phase.Comment: 5 pages, 1 figure, Revtex, we have modified our conclusions for the
metallic superconducto
Constructing power system restoration strategies
System restoration is an integral part of the overall defense system against catastrophic outages. The nature of system restoration problem involves status assessment, optimization of generation capability and load pickup. The optimization problem needs to take into numerous practical considerations and, therefore, it cannot be formulated as one single optimization problem. The other critical consideration for the development of decision support tools is its generality, i.e., the tools should be portable from a system to another with minimal customization. This presentation will provide a comprehensive methodology for construction of system restoration strategies. The strategy adopted by each power system differs, depending on the system characteristics and policies. A new method based on the concept of "generic restoration milestones" and "generic restoration actions" has been developed. A specific restoration strategy can be synthesized by a combination of the milestones and actions based on the actual system conditions. The decision support tool is expected to reduce the restoration time, thereby improving the system reliability.published_or_final_versionThe 6th International Conference on Electrical and Electroincs Engineering (ELECO 2009), Bursa, Turkey, 5-8 November 2009. In Proceedings of the International Conference on Electrical and Electronics Engineering, 2009, p. I8-I1
Ettingshausen effect due to Majorana modes
The presence of Majorana zero-energy modes at vortex cores in a topological
superconductor implies that each vortex carries an extra entropy , given
by , that is independent of temperature. By utilizing this
special property of Majorana modes, the edges of a topological superconductor
can be cooled (or heated) by the motion of the vortices across the edges. As
vortices flow in the transverse direction with respect to an external imposed
supercurrent, due to the Lorentz force, a thermoelectric effect analogous to
the Ettingshausen effect is expected to occur between opposing edges. We
propose an experiment to observe this thermoelectric effect, which could
directly probe the intrinsic entropy of Majorana zero-energy modes.Comment: 16 pages, 3 figure
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