17,585 research outputs found
Beam spin asymmetry in deeply virtual production
An interpretation of the beam spin azimuthal asymmetries measured at JLAB in
deep exclusive electroproduction of charged and neutral pions is presented. The
model combines a Regge pole approach with the effect of nucleon resonances. The
- and -channel contributions are described using a dual Bloom-Gilman
connection between the exclusive form factors and inclusive deep inelastic
structure functions. The results are in agreement with data provided the
excitations of nucleon resonances are taken into account.Comment: 5 pages, 3 figures. Talk at the 19th International Spin Physics
Symposium (SPIN2010), Sept.27-Oct.2, 2010, Juelich, German
Kinetic Accessibility of Buried DNA Sites in Nucleosomes
Using a theoretical model for spontaneous partial DNA unwrapping from
histones, we study the transient exposure of protein-binding DNA sites within
nucleosomes. We focus on the functional dependence of the rates for site
exposure and reburial on the site position, which is measurable experimentally
and pertinent to gene regulation. We find the dependence to be roughly
described by a random walker model. Close inspection reveals a surprising
physical effect of flexibility-assisted barrier crossing, which we characterize
within a toy model, the "semiflexible Brownian rotor."Comment: final version as published in Phys. Rev. Let
AN EVALUATION OF CONSUMER PESTICIDE RESIDUE CONCERNS AND RISK INFORMATION SOURCES
Marginal probability effects of demographic variables on consumer concerns about pesticide residues were assessed as well as the likelihood of consumer beliefs given different channels of information on produce safety and risks. This was done using maximum likelihood estimation (MLE) of ordered logit models. The empirical results showed that pesticide residue concern levels appeared to be lower for more highly educated and high income households. Safety information from the academic community was found to have the highest likelihood of acceptance by consumers.Risk and Uncertainty,
Phonon-dressed Mollow triplet in the regime of cavity-QED
We study the resonance fluorescence spectra of a driven quantum dot placed
inside a high semiconductor cavity and interacting with an acoustic phonon
bath. The dynamics is calculated using a time-convolutionless master equation
obtained in the polaron frame. We demonstrate pronounced spectral broadening of
the Mollow sidebands through cavity-emission which, for small cavity-coupling
rates, increases quadratically with the Rabi frequency. However, for larger
cavity coupling rates, this broadening dependence is found to be more complex.
This field-dependent Mollow triplet broadening is primarily a consequence of
the triplet peaks sampling different parts of the asymmetric phonon bath, and
agrees directly with recent experiments with semiconductor micropillars. The
influence from the detuned cavity photon bath and multi-photon effects is shown
to play a qualitatively important role on the fluorescence spectra.Comment: 4 pages, 4 figure
Triple Compton effect: A photon splitting into three upon collision with a free electron
The process in which a photon splits into three after the collision with a
free electron (triple Compton effect) is the most basic process for the
generation of a high-energy multi-particle entangled state composed out of
elementary quanta. The cross section of the process is evaluated in two
experimentally realizable situations, one employing gamma photons and
stationary electrons, and the other using keV photons and GeV electrons of an
x-ray free electron laser. For the first case, our calculation is in agreement
with the only available measurement of the differential cross section for the
process under study. Our estimates indicate that the process should be readily
measurable also in the second case. We quantify the polarization entanglement
in the final state by a recently proposed multi-particle entanglement measure.Comment: 5 pages; RevTeX; to be published in Phys.Rev.Let
THE SINGLE INDEX MARKET MODEL IN AGRICULTURE
This study illustrates the differences in empirical results due to data measurements and estimating procedures when applying the single index market model in agriculture. Gross and net return betas along with systematic and unsystematic risk proportions are estimated and found to be different. The stochastic coefficients model is used to show the difference in beta-risk estimates compared with the traditional fixed coefficients OLS procedure. A third estimating technique, weighted least squares/Prais Winsten method, is also proposed.Research Methods/ Statistical Methods,
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