111 research outputs found
Self-consistent analysis of carrier-transport and carrier-capture dynamics in quantum cascade intersubband semiconductor lasers
A methodology for the self-consistent analysis of carrier transport and carrier capture aspects of the dynamics of quantum cascade intersubband semiconductor lasers is described in this paper. The approach is used to analyze two prototype quantum cascade lasers. The self-consistent analysis incorporates the calculation of the electron densities and temperatures in each subband, together with the intersubband relaxation time. In the calculation of the relaxation time, we take into account the electron interaction with polar optical and acoustic phonons, as well as electron degeneracy. In addition, we also calculate the capture time, considering backward processes that play a role in the electron transition from an injection into an active region. The calculations indicate intersubband relaxation times of order 1 ps and capture times of order 100 f
Parameter mismatches,variable delay times and synchronization in time-delayed systems
We investigate synchronization between two unidirectionally linearly coupled
chaotic non-identical time-delayed systems and show that parameter mismatches
are of crucial importance to achieve synchronization. We establish that
independent of the relation between the delay time in the coupled systems and
the coupling delay time, only retarded synchronization with the coupling delay
time is obtained. We show that with parameter mismatch or without it neither
complete nor anticipating synchronization occurs. We derive existence and
stability conditions for the retarded synchronization manifold. We demonstrate
our approach using examples of the Ikeda and Mackey-Glass models. Also for the
first time we investigate chaos synchronization in time-delayed systems with
variable delay time and find both existence and sufficient stability conditions
for the retarded synchronization manifold with the coupling delay lag time.
Also for the first time we consider synchronization between two
unidirectionally coupled chaotic multi-feedback Ikeda systems and derive
existence and stability conditions for the different anticipating, lag, and
complete synchronization regimes.Comment: 12 page
Neutrino Propagation in a Strongly Magnetized Medium
We derive general expressions at the one-loop level for the coefficients of
the covariant structure of the neutrino self-energy in the presence of a
constant magnetic field. The neutrino energy spectrum and index of refraction
are obtained for neutral and charged media in the strong-field limit () using the lowest Landau level
approximation. The results found within the lowest Landau level approximation
are numerically validated, summing in all Landau levels, for strong and weakly-strong fields. The neutrino energy in
leading order of the Fermi coupling constant is expressed as the sum of three
terms: a kinetic-energy term, a term of interaction between the magnetic field
and an induced neutrino magnetic moment, and a rest-energy term. The leading
radiative correction to the kinetic-energy term depends linearly on the
magnetic field strength and is independent of the chemical potential. The other
two terms are only present in a charged medium. For strong and weakly-strong
fields, it is found that the field-dependent correction to the neutrino energy
in a neutral medium is much larger than the thermal one. Possible applications
to cosmology and astrophysics are considered.Comment: 23 pages, 4 figures. Corrected misprints in reference
Role of genetic testing for inherited prostate cancer risk: Philadelphia prostate cancer consensus conference 2017
Purpose: Guidelines are limited for genetic testing for prostate cancer (PCA). The goal of this conference was to develop an expert consensus-dri
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