16,360 research outputs found
Hall effect in quasi one-dimensional organic conductors
We study the Hall effect in a system of weakly coupled Luttinger Liquid
chains, using a Memory function approach to compute the Hall constant in the
presence of umklapp scattering along the chains. In this approximation, the
Hall constant decomposes into two terms: a high-frequency term and a Memory
function term. For the case of zero umklapp scattering, where the Memory
function vanishes, the Hall constant is simply the band value, in agreement
with former results in a similar model with no dissipation along the chains.
With umklapp scattering along the chains, we find a power-law temperature
dependance of the Hall constant. We discuss the applications to quasi 1D
organic conductors at high temperatures.Comment: Proceedings of the ISCOM conference "Sixth International Symposium on
Crystalline Organic Metals, Superconductors, and Ferromagnets", Key West,
Florida, USA (Sept. 2005), to be plublished in the Journal of Low Temperature
Physic
Discrete Gravitational Dimensions
We study the physics of a single discrete gravitational extra dimension using
the effective field theory for massive gravitons. We first consider a minimal
discretization with 4D gravitons on the sites and nearest neighbor hopping
terms. At the linear level, 5D continuum physics is recovered correctly, but at
the non-linear level the theory becomes highly non-local in the discrete
dimension. There is a peculiar UV/IR connection, where the scale of strong
interactions at high energies is related to the radius of the dimension. These
new effects formally vanish in the limit of zero lattice spacing, but do not do
so quickly enough to reproduce the continuum physics consistently in an
effective field theory up to the 5D Planck scale. Nevertheless, this model does
make sense as an effective theory up to energies parametrically higher than the
compactification scale. In order to have a discrete theory that appears local
in the continuum limit, the lattice action must have interactions between
distant sites. We speculate on the relevance of these observations to the
construction of finite discrete theories of gravity in four dimensions.Comment: 5 pages, 4 diagrams. Important typos in some equations corrected;
conclusion s unchange
Crossover from Quarter-Filling to Half-Filling in a One-Dimensional Electron System with a Dimerized and Quarter-Filled Band
The interplay between quarter-filled and half-filled umklapp scattering has
been examined by applying the renormalization group method to a one-dimensional
quarter-filled electron system with dimerization, on-site (U) and
nearest-neighbor (V) repulsive interactions. The phase diagram on the U-V plane
is obtained at absolute zero temperature where the Mott insulator (the charge
ordered insulator) is found for smaller (larger) V. By choosing the moderate
parameter in the region of Mott insulator, it is shown that the resistivity
exhibits a crossover from behavior of quarter-filling to that of half-filling
with decreasing temperature.Comment: 4 pages, 4 figures, submitted to J. Phys. Soc. Jp
Open ventral hernia repair with a composite ventral patch : final results of a multicenter prospective study
Background: This study assessed clinical outcomes, including safety and recurrence, from the two-year follow-up of patients who underwent open ventral primary hernia repair with the use of the Parietex (TM) Composite Ventral Patch (PCO-VP).
Methods: A prospective single-arm, multicenter study of 126 patients undergoing open ventral hernia repair for umbilical and epigastric hernias with the PCO-VP was performed.
Results: One hundred twenty-six subjects (110 with umbilical hernia and 16 with epigastric hernia) with a mean hernia diameter of 1.8cm (0.4-4.0) were treated with PCO-VP. One hundred subjects completed the two-year study. Cumulative hernia recurrence was 3.0% (3/101; 95%CI: 0.0-6.3%) within 24months. Median Numeric Rating Scale pain scores improved from 2 [0-10] at baseline to 0 [0-3] at 1 month (P<0.001) and remained low at 24months 0 [0-6] (P<0.001). 99% (102/103) of the patients were satisfied with their repair at 24months postoperative.
Conclusions: The use of PCO-VP to repair primary umbilical and epigastric defects yielded a low recurrence rate, low postoperative and chronic pain, and high satisfaction ratings, confirming that PCO-VP is effective for small ventral hernia repair in the two-year term after implantation.
Trial registration: The study was registered publically at clinicaltrials.gov (NCT01848184 registered May 7, 2013)
Generalized Supersymmetric Perturbation Theory
Using the basic ingredient of supersymmetry, we develop a simple alternative
approach to perturbation theory in one-dimensional non-relativistic quantum
mechanics. The formulae for the energy shifts and wave functions do not involve
tedious calculations which appear in the available perturbation theories. The
model applicable in the same form to both the ground state and excited bound
states, unlike the recently introduced supersymmetric perturbation technique
which, together with other approaches based on logarithmic perturbation theory,
are involved within the more general framework of the present formalism.Comment: 13 pages article in LaTEX (uses standard article.sty). No Figures.
Sent to Ann. Physics (2004
Confinement-deconfinement transition in two-coupled chains with umklapp scattering
A role of umklapp scattering has been examined for two-coupled chains with
both forward and backward scatterings by applying renormalization group method
to bosonized Hamiltonian. It has been found that a state with relevant
interchain hopping changes into a state with irrelevant (confined) one when the
magnitude of umklapp scattering becomes larger than that of interchain hopping.
Critical value of umklapp scattering for such a confinement-deconfinement
transition is calculated as the function of interchain hopping and intrachain
interactions. A crossover from one-dimensional regime into that of coupled
chains is also shown with decreasing temperature.Comment: 13 pages, 7 figures, to be published in Phys. Rev.
The spectral action for Moyal planes
Extending a result of D.V. Vassilevich, we obtain the asymptotic expansion
for the trace of a "spatially" regularized heat operator associated with a
generalized Laplacian defined with integral Moyal products. The Moyal
hyperplanes corresponding to any skewsymmetric matrix being spectral
triples, the spectral action introduced in noncommutative geometry by A.
Chamseddine and A. Connes is computed. This result generalizes the Connes-Lott
action previously computed by Gayral for symplectic .Comment: 20 pages, no figure, few improvment
Analyzing Powers and Spin Correlation Coefficients for p+d Elastic Scattering at 135 and 200 MeV
The proton and deuteron analyzing powers and 10 of the possible 12 spin
correlation coefficients have been measured for p+d elastic scattering at
proton bombarding energies of 135 and 200 MeV. The results are compared with
Faddeev calculations using two different NN potentials. The qualitative
features of the extensive data set on the spin dependence in p+d elastic
scattering over a wide range of angles presented here are remarkably well
explained by two-nucleon force predictions without inclusion of a three-nucleon
force. The remaining discrepancies are, in general, not alleviated when
theoretical three-nucleon forces are included in the calculations.Comment: 43 pages, 12 figures, accepted for publication by Phys. Rev.
Measurement of Partial-Wave Contributions in pp --> pp pi^0
We report a measurement of the spin-dependent total cross section ratios
delta_sigma_T/sigma_tot and delta_sigma_L/sigma_tot of the pp --> pp pi^0
reaction between 325 MeV and 400 MeV. The experiment was carried out with a
polarized internal target in a storage ring. Non-vertical beam polarization was
obtained by the use of solenoidal spin rotators. Near threshold, the knowledge
of both spin-dependent total cross sections is sufficient to deduce the
strength of certain participating partial waves, free of any model.Comment: 6 pages, 4 figure
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