29,365 research outputs found
Electrical conductivity and thermal dilepton rate from quenched lattice QCD
We report on a continuum extrapolation of the vector current correlation
function for light valence quarks in the deconfined phase of quenched QCD. This
is achieved by performing a systematic analysis of the influence of cut-off
effects on light quark meson correlators at using clover
improved Wilson fermions. We discuss resulting constraints on the electrical
conductivity and the thermal dilepton rate in a quark gluon plasma. In addition
new results at 1.2 and 3.0 will be presented.Comment: 4 pages, 6 eps figures, to appear in the proceedings of Quark Matter
2011, 23-28 May 2011, Annecy, Franc
Electron transfer through a multiterminal quantum ring: magnetic forces and elastic scattering effects
We study electron transport through a semiconductor quantum ring with one
input and two output terminals for an elastic scatterer present within one of
the arms of the ring. We demonstrate that the scatterer not only introduces
asymmetry in the transport probability to the two output leads but also reduces
the visibility of the Aharonov-Bohm conductance oscillations. This reduction
occurs in spite of the phase coherence of the elastic scattering and is due to
interruption of the electron circulation around the ring by the potential
defect. The results are in a qualitative agreement with a recent experiment by
Strambini et al. [Phys. Rev. B {\bf 79}, 195443 (2009)]. We also indicate that
the magnetic symmetry of the sum of conductance of both the output leads as
obtained in the experiment can be understood as resulting from the invariance
of backscattering to the input lead with respect to the magnetic field
orientation.Comment: submitted to PR
The weld-brazing metal joining process
Superior mechanical properties were obtained in metal joints weld-brazed between faying surfaces. Weld-braze applications and advantages are listed
Hodograph solutions of the dispersionless coupled KdV hierarchies, critical points and the Euler-Poisson-Darboux equation
It is shown that the hodograph solutions of the dispersionless coupled KdV
(dcKdV) hierarchies describe critical and degenerate critical points of a
scalar function which obeys the Euler-Poisson-Darboux equation. Singular
sectors of each dcKdV hierarchy are found to be described by solutions of
higher genus dcKdV hierarchies. Concrete solutions exhibiting shock type
singularities are presented.Comment: 19 page
Development of aircraft lavatory compartments with improved fire resistance characteristics, phase 1: Fire containment test of a wide body aircraft lavatory module
A test was conducted to evaluate the fire containment characteristics of a Boeing 747 lavatory module. Results showed that the fire was contained within the lavatory during the 30-minute test period with the door closed. The resistance of the lavatory wall and ceiling panels and general lavatory construction to burn-through under the test conditions was demonstrated
Comment on "c-axis Josephson tunneling in -wave superconductors''
This comment points out that the recent paper by Maki and Haas [Phys. Rev. B
{\bf 67}, 020510 (2003)] is completely wrong.Comment: 1 page, submittted to Phys. Rev.
Josephson (001) tilt grain boundary junctions of high temperature superconductors
We calculate the critical current across in-plane (001) tilt grain
boundary junctions of high temperature superconductors. We solve for the
electronic states corresponding to the electron-doped cuprates, two slightly
different hole-doped cuprates, and an extremely underdoped hole-doped cuprate
in each half-space, and weakly connect the two half-spaces by either specular
or random quasiparticle tunneling. We treat symmetric, straight, and fully
asymmetric junctions with s-, extended-s-, or d-wave order
parameters. For symmetric junctions with random grain boundary tunneling, our
results are generally in agreement with the Sigrist-Rice form for ideal
junctions that has been used to interpret ``phase-sensitive'' experiments
consisting of such in-plane grain boundary junctions. For specular grain
boundary tunneling across symmetric juncitons, our results depend upon the
Fermi surface topology, but are usually rather consistent with the random facet
model of Tsuei {\it et al.} [Phys. Rev. Lett. {\bf 73}, 593 (1994)]. Our
results for asymmetric junctions of electron-doped cuparates are in agreement
with the Sigrist-Rice form. However, ou resutls for asymmetric junctions of
hole-doped cuprates show that the details of the Fermi surface topology and of
the tunneling processes are both very important, so that the
``phase-sensitive'' experiments based upon the in-plane Josephson junctions are
less definitive than has generally been thought.Comment: 13 pages, 10 figures, resubmitted to PR
Time scale of entropic segregation of flexible polymers in confinement: Implications for chromosome segregation in filamentous bacteria
We report molecular dynamics simulations of the segregation of two
overlapping chains in cylindrical confinement. We find that the entropic
repulsion between the chains can be sufficiently strong to cause segregation on
a time scale that is short compared to the one for diffusion. This result
implies that entropic driving forces are sufficiently strong to cause rapid
bacterial chromosome segregation.Comment: Minor changes. Added some references, corrected the labels in figure
6 and reformatted in two columns. Also added reference to published version
in PR
The phase-dependent linear conductance of a superconducting quantum point contact
The exact expression for the phase-dependent linear conductance of a weakly
damped superconducting quantum point contact is obtained. The calculation is
performed by summing up the complete perturbative series in the coupling
between the electrodes. The failure of any finite order perturbative expansion
in the limit of small voltage and small quasi-particle damping is analyzed in
detail. In the low transmission regime this nonperturbative calculation yields
a result which is at variance with standard tunnel theory. Our result predicts
the correct sign of the quasi-particle pair interference term and exhibits an
unusual phase-dependence at low temperatures in qualitative agreement with the
available experimental data.Comment: 12 pages (revtex) + 1 postscript figure. Submitted to Phys. Rev. Let
- …