9,669 research outputs found
Statistical study of the conductance and shot noise in open quantum-chaotic cavities: Contribution from whispering gallery modes
In the past, a maximum-entropy model was introduced and applied to the study
of statistical scattering by chaotic cavities, when short paths may play an
important role in the scattering process. In particular, the validity of the
model was investigated in relation with the statistical properties of the
conductance in open chaotic cavities. In this article we investigate further
the validity of the maximum-entropy model, by comparing the theoretical
predictions with the results of computer simulations, in which the Schroedinger
equation is solved numerically inside the cavity for one and two open channels
in the leads; we analyze, in addition to the conductance, the zero-frequency
limit of the shot-noise power spectrum. We also obtain theoretical results for
the ensemble average of this last quantity, for the orthogonal and unitary
cases of the circular ensemble and an arbitrary number of channels. Generally
speaking, the agreement between theory and numerics is good. In some of the
cavities that we study, short paths consist of whispering gallery modes, which
were excluded in previous studies. These cavities turn out to be all the more
interesting, as it is in relation with them that we found certain systematic
discrepancies in the comparison with theory. We give evidence that it is the
lack of stationarity inside the energy interval that is analyzed, and hence the
lack of ergodicity that gives rise to the discrepancies. Indeed, the agreement
between theory and numerical simulations is improved when the energy interval
is reduced to a point and the statistics is then collected over an ensemble. It
thus appears that the maximum-entropy model is valid beyond the domain where it
was originally derived. An understanding of this situation is still lacking at
the present moment.Comment: Revised version, minor modifications, 28 pages, 7 figure
Extrasolar Planets in Mean-Motion Resonance: Apses Alignment and Asymmetric Stationary Solutions
In recent years several pairs of extrasolar planets have been discovered in
the vicinity of mean-motion commensurabilities. In some cases, such as the
Gliese 876 system, the planets seem to be trapped in a stationary solution, the
system exhibiting a simultaneous libration of the resonant angle theta_1 = 2
lambda_2 - lambda_1 - varpi_1 and of the relative position of the pericenters.
In this paper we analyze the existence and location of these stable
solutions, for the 2/1 and 3/1 resonances, as function of the masses and
orbital elements of both planets. This is undertaken via an analytical model
for the resonant Hamiltonian function. The results are compared with those of
numerical simulations of the exact equations.
In the 2/1 commensurability, we show the existence of three principal
families of stationary solutions: (i) aligned orbits, in which theta_1 and
varpi_1 - varpi_2 both librate around zero, (ii) anti-aligned orbits, in which
theta_1=0 and the difference in pericenter is 180 degrees, and (iii) asymmetric
stationary solutions, where both the resonant angle and varpi_1 - varpi_2 are
constants with values different of 0 or 180 degrees. Each family exists in a
different domain of values of the mass ratio and eccentricities of both
planets. Similar results are also found in the 3/1 resonance.
We discuss the application of these results to the extrasolar planetary
systems and develop a chart of possible planetary orbits with apsidal
corotation. We estimate, also, the maximum planetary masses in order that the
stationary solutions are dynamically stable.Comment: 25 pages, 10 figures. Submitted to Ap
Intensity correlations in electronic wave propagation in a disordered medium: the influence of spin-orbit scattering
We obtain explicit expressions for the correlation functions of transmission
and reflection coefficients of coherent electronic waves propagating through a
disordered quasi-one-dimensional medium with purely elastic diffusive
scattering in the presence of spin-orbit interactions. We find in the metallic
regime both large local intensity fluctuations and long-range correlations
which ultimately lead to universal conductance fluctuations. We show that the
main effect of spin-orbit scattering is to suppress both local and long-range
intensity fluctuations by a universal symmetry factor 4. We use a scattering
approach based on random transfer matrices.Comment: 15 pages, written in plain TeX, Preprint OUTP-93-42S (University of
Oxford), to appear in Phys. Rev.
Marine recreational fisheries statistics survey for northern and central California, Quarterly Report no. 1, July to September 1979
Field intercept Marine Recreational Fisheries Statistics Survey (MRFSS) data for central and northern California, collected in July to September 1979, is presented in a data report format. Data in this quarterly report are subdivided into three categories: primarily by five geographical areas;
secondarily by fishing modes and gear types within each area; and finally by catch definition for each area, mode, and gear type. Tables are presented for these categories, each with three sections: sampled effort, ranked catch, and catch-per-unit-effort (CPUE). Also, within each area,
length-frequency histograms and tables are presented for select species. (168pp.
Range and structure of ambient density from 30 to 120 km altitude
Range and structure of atmospheric density from 30 to 120 km - analysis of statistical models and deviations from U.S. standard and Patrick reference atmosphere
Marine recreational fisheries statistics survey for northern and central California, Quarterly Report no. 2, October to December, 1979
Field intercept Marine Recreational Fisheries Statistics Survey (MRFSS) data for central and northern California, collected in October to December 1979, is presented in a data report format. Data in this quarterly report are subdivided into three categories: primarily by five geographical areas; secondarily by fishing modes and gear types within each area; and finally by catch definition for each area, mode, d gear type. Tables are presented for these categories, each with three sections: sampled effort, ranked
catch, and catch-per-unit-effort (CPUE). Also, within each area, length-frequency histograms and tables are presented for select species. (139pp.
Marine recreational fisheries statistics survey for northern and central California, Quarterly Report no. 6, October to December, 1980
Field intercept Marine Recreational Fisheries Statistics Survey (MRFSS) data for central and northern California, collected in October to December. 1980, is presented in a data report format. Data in this quarterly report are subdivided into three categories: primarily by five geographical areas; secondarily by fishing modes and gear types within each area; and finally by catch definition for each area, mode, and gear type. Tables are presented for these categories, each with three sections: sampled effort, ranked catch, and catch-per-unit effort (CPUE). Also, within each area, length-frequency histograms and tables are presented for select species. (143pp.
- …