2,776 research outputs found
The Rashba Hamiltonian and electron transport
The Rashba Hamiltonian describes the splitting of the conduction band as a
result of spin-orbit coupling in the presence of an external field and is
commonly used to model the electronic structure of confined narrow-gap
semiconductors. Due to the mixing of spin states some care has to be exercised
in the calculation of transport properties. We derive the velocity operator for
the Rashba-split conduction band and demonstrate that the transmission of an
interface between a ferromagnet and a Rashba-split semiconductor does not
depend on the magnetization direction, in contrast with previous assertions in
the literature.Comment: one tex file, two figures; paper to appear in this form in PRB (RC
Comparisons of commercial frozen yogurt with ksu formulation
Ten samples of vanilla frozen yogurt were
purchased in Kansas and compared to a highprotein,
KSU formulation. The KSU
formulation had similar solids, fat, and sugar
contents as the commercial samples. All
commercial samples had lower protein (almost
less than half) content and more lactose, and
almost all samples had fewer lactic acid
bacteria than the KSU formulation. All but one
commercial sample had lower b-galactosidase
activity than the KSU formulation. This may
reflect the differing lactic acid bacterial
populations in the frozen yogurts
Density of States Extracted from Modified Recursion Relations
We evaluate the density of states (DOS) associated with tridiagonal symmetric
Hamiltonian matrices and study the effect of perturbation on one of its
entries. Analysis is carried out by studying the resulting three-term recursion
relation and the corresponding orthogonal polynomials of the first and second
kind. We found closed form expressions for the new DOS in terms of the original
one when perturbation affects a single diagonal or off-diagonal site or a
combination of both. The projected DOS is also calculated numerically and its
relation to the average DOS is explored both analytically and numerically.Comment: 15 pages including 8 figures (one in color
PDB72 Health economic evaluation of canagliflozin in the treatment of type 2 diabetes mellitus in Sweden
Density functional theory and demixing of binary hard rod-polymer mixtures
A density functional theory for a mixture of hard rods and polymers modeled
as chains built of hard tangent spheres is proposed by combining the functional
due to Yu and Wu for the polymer mixtures [J. Chem. Phys. {\bf 117}, 2368
(2002)] with the Schmidt's functional [Phys. Rev. E {\bf 63}, 50201 (2001)] for
rod-sphere mixtures. As a simple application of the functional, the demixing
transition into polymer-rich and rod-rich phases is examined. When the chain
length increases, the phase boundary broadens and the critical packing fraction
decreases. The shift of the critical point of a demixing transition is most
noticeable for short chains.Comment: 4 pages,2 figures, in press, PR
Multiphonon and ``hot''-phonon Isovector Electric-Dipole Excitations
We argue that a substantial increase in the cross section for Coulomb
excitation in the region of the Double Giant Dipole Resonance should be
expected from Coulomb excitation of excited states involved in the spreading of
the one-phonon resonance, in a manifestation of the Brink-Axel phenomenon. This
generates an additional fluctuating amplitude and a corresponding new term to
be added incoherently to the usual cross-section. The appropriate extension of
an applicable reaction calculation is considered in order to estimate this
effect.Comment: 6 pages, Latex, 1 figure available on reques
SU(2,1) Dynamics of Multiple Giant Dipole Resonance Coulomb Excitation
We construct a three-dimensional analytically soluble model of the nonlinear
effects in Coulomb excitation of multiphonon Giant Dipole Resonances (GDR)
based on the SU(2,1) algebra. The full 3-dimensional model predicts further
enhancement of the Double GDR (DGDR) cross sections at high bombarding
energies. Enhancement factors for DGDR measured in thirteen different processes
with various projectiles and targets at different bombarding energies are well
reproduced with the same value of the nonlinearity parameter with the exception
of the anomalous case of Xe which requires a larger value.Comment: 10 pages, 3 Postscript figures, late
Generation of entangled coherent states via cross phase modulation in a double electromagnetically induced transparency regime
The generation of an entangled coherent state is one of the most important
ingredients of quantum information processing using coherent states. Recently,
numerous schemes to achieve this task have been proposed. In order to generate
travelling-wave entangled coherent states, cross phase modulation, optimized by
optical Kerr effect enhancement in a dense medium in an electromagnetically
induced transparency (EIT) regime, seems to be very promising. In this
scenario, we propose a fully quantized model of a double-EIT scheme recently
proposed [D. Petrosyan and G. Kurizki, {\sl Phys. Rev. A} {\bf 65}, 33833
(2002)]: the quantization step is performed adopting a fully Hamiltonian
approach. This allows us to write effective equations of motion for two
interacting quantum fields of light that show how the dynamics of one field
depends on the photon-number operator of the other. The preparation of a
Schr\"odinger cat state, which is a superposition of two distinct coherent
states, is briefly exposed. This is based on non-linear interaction via
double-EIT of two light fields (initially prepared in coherent states) and on a
detection step performed using a beam splitter and two photodetectors.
In order to show the entanglement of a generated entangled coherent state, we
suggest to measure the joint quadrature variance of the field. We show that the
entangled coherent states satisfy the sufficient condition for entanglement
based on quadrature variance measurement. We also show how robust our scheme is
against a low detection efficiency of homodyne detectors.Comment: 15 pages, 9 figures; extensively revised version; added Section
BioConcens: Biomass and bioenergy production agriculture – consequences for soil fertility, environment, spread of animal parasites and socio-economy
The research programme called “international research cooperation and organic integrity” was commenced for a period 2006-2010. It is coordinated by DARCOF (The Danish Research Centre for Organic Farming). The whole programme, with acronym DARCOF III, consists of 15 projects (http://www.darcof.dk/research/darcofiii/index.html). One of them is BIOCONCENS - Biomass and bioenergy production in organic farming – consequences for soil fertility, environment, spread of animal parasites and socio-economy (http://www.bioconcens.elr.dk/uk/). The production of bioenergy in organic agriculture (OA) can reduce its dependency of fossil fuels and decrease green house gasses emission; consequently it will increase sustainability of organic farms. Biorefinery concept based on co-production of biogas, bioethanol and protein fodder in organic farming will be developed within the BIOCONCENS project and the background for the project and the different work packages will be presented in this paper
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