6,628 research outputs found
Spin polarizations and spin Hall currents in a two-dimensional electron gas with magnetic impurities
We consider a two-dimensional electron gas in the presence of Rashba
spin-orbit coupling, and study the effects of magnetic s-wave impurities and
long-range non-magnetic disorder on the spin-charge dynamics of the system. We
focus on voltage induced spin polarizations and their relation to spin Hall
currents. Our results are obtained using the quasiclassical Green function
technique, and hold in the full range of the disorder parameter .Comment: 5 pages, 2 figures. References added, minor stylistic modification
ATLAS RPC offline monitoring and data quality assessment
In this work several aspects of ATLAS RPC offline monitoring and data quality
assessment are illustrated with cosmics data selected by RPC trigger. These
correspond to trigger selection, front-end mapping, detection efficiency and
occupancy, which are studied in terms of low level quantities such as: RPC
off-line hits and standalone tracks. The tools and techniques presented are
also extended to the forthcoming LHC p-p beam collisions.Comment: Poster section at ICHEP08, Philadelphia, USA, July 2008. 3 pages,
LaTeX, 3 eps figure
Determination of the noise parameters in a one-dimensional open quantum system
We consider an electron magnetically interacting with a spin-1/2 impurity,
embedded in an external environment whose noisy term acts only on the
impurity's spin, and we find expressions for the electron transmission and
reflection probabilities in terms of the phenomenological noise parameters.
Moreover, we give a simple example of the necessity of complete positivity for
physical consistency, showing that a positive but not completely positive
dissipative map can lead to negative transmission probabilities
KLOE results at the Frascati -factory DANE
The KLOE experiment at the Frascati -factory DANE has collected
about 0.5 fb of data till the end of the year 2002. These data allow to
perform a wide physics program, ranging from the physics of charged and neutral
kaons to radiative -decays. Results are presented for the lifetime
and the semileptonic processes . From the light meson
spectroscopy program, results on the decays as well as are presented.Comment: 5 pages, 3 figures, Proceedings contribution to the 10th Int.
Symposium on "Meson-Nucleon Physics and the Structure of the Nucleon"
(MENU04), Beijing, China, Aug. 30 - Sept. 4, 200
Analogue Gravity and ultrashort laser pulse filamentation
Ultrashort laser pulse filaments in dispersive nonlinear Kerr media induce a
moving refractive index perturbation which modifies the space-time geometry as
seen by co-propagating light rays. We study the analogue geometry induced by
the filament and show that one of the most evident features of filamentation,
namely conical emission, may be precisely reconstructed from the geodesics. We
highlight the existence of favorable conditions for the study of analogue black
hole kinematics and Hawking type radiation.Comment: 4 pages, revised versio
A ribonucleoprotein precursor of both the 30S and 50S ribosomal sunbunits of Escherichia coli.
Quasiclassical approach to the spin-Hall effect in the two-dimensional electron gas
We study the spin-charge coupled transport in a two-dimensional electron
system using the method of quasiclassical (-integrated) Green's functions.
In particular we derive the Eilenberger equation in the presence of a generic
spin-orbit field. The method allows us to study spin and charge transport from
ballistic to diffusive regimes and continuity equations for spin and charge are
automatically incorporated. In the clean limit we establish the connection
between the spin-Hall conductivity and the Berry phase in momentum space. For
finite systems we solve the Eilenberger equation numerically for the special
case of the Rashba spin-orbit coupling and a two-terminal geometry. In
particular, we calculate explicitly the spin-Hall induced spin polarization in
the corners, predicted by Mishchenko et al. [13]. Furthermore we find universal
spin currents in the short-time dynamics after switching on the voltage across
the sample, and calculate the corresponding spin-Hall polarization at the
edges. Where available, we find perfect agreement with analytical results.Comment: 9 pages, 6 figure
Positively Correlated miRNA-miRNA Regulatory Networks in Mouse Frontal Cortex During Early Stages of Alcohol Dependence
Although the study of gene regulation via the action of specific microRNAs (miRNAs) has experienced a boom in recent years, the analysis of genome-wide interaction networks among miRNAs and respective targeted mRNAs has lagged behind. MicroRNAs simultaneously target many transcripts and fine-tune the expression of genes through cooperative/combinatorial targeting. Therefore, they have a large regulatory potential that could widely impact development and progression of diseases, as well as contribute unpredicted collateral effects due to their natural, pathophysiological, or treatment-induced modulation. We support the viewpoint that whole mirnome-transcriptome interaction analysis is required to better understand the mechanisms and potential consequences of miRNA regulation and/or deregulation in relevant biological models. In this study, we tested the hypotheses that ethanol consumption induces changes in miRNA-mRNA interaction networks in the mouse frontal cortex and that some of the changes observed in the mouse are equivalent to changes in similar brain regions from human alcoholics. Results: miRNA-mRNA interaction networks responding to ethanol insult were identified by differential expression analysis and weighted gene coexpression network analysis (WGCNA). Important pathways (coexpressed modular networks detected by WGCNA) and hub genes central to the neuronal response to ethanol are highlighted, as well as key miRNAs that regulate these processes and therefore represent potential therapeutic targets for treating alcohol addiction. Importantly, we discovered a conserved signature of changing miRNAs between ethanol-treated mice and human alcoholics, which provides a valuable tool for future biomarker/diagnostic studies in humans. We report positively correlated miRNA-mRNA expression networks that suggest an adaptive, targeted miRNA response due to binge ethanol drinking. Conclusions: This study provides new evidence for the role of miRNA regulation in brain homeostasis and sheds new light on current understanding of the development of alcohol dependence. To our knowledge this is the first report that activated expression of miRNAs correlates with activated expression of mRNAs rather than with mRNA downregulation in an in vivo model. We speculate that early activation of miRNAs designed to limit the effects of alcohol-induced genes may be an essential adaptive response during disease progression.NIAAA 5R01AA012404, 5P20AA017838, 5U01AA013520, P01AA020683, 5T32AA007471-24/25Waggoner Center for Alcohol and Addiction Researc
Inverse Spin Hall Effect and Anomalous Hall Effect in a Two-Dimensional Electron Gas
We study the coupled dynamics of spin and charge currents in a
two-dimensional electron gas in the transport diffusive regime. For systems
with inversion symmetry there are established relations between the spin Hall
effect, the anomalous Hall effect and the inverse spin Hall effect. However, in
two-dimensional electron gases of semiconductors like GaAs, inversion symmetry
is broken so that the standard arguments do not apply. We demonstrate that in
the presence of a Rashba type of spin-orbit coupling (broken structural
inversion symmetry) the anomalous Hall effect, the spin Hall and inverse spin
Hall effect are substantially different effects. Furthermore we discuss the
inverse spin Hall effect for a two-dimensional electron gas with Rashba and
Dresselhaus spin-orbit coupling; our results agree with a recent experiment.Comment: 5 page
Quantum theory as a relevant framework for the statement of probabilistic and many-valued logic
Based on ideas of quantum theory of open systems we propose the consistent
approach to the formulation of logic of plausible propositions. To this end we
associate with every plausible proposition diagonal matrix of its likelihood
and examine it as density matrix of relevant quantum system. We are showing
that all logical connectives between plausible propositions can be represented
as special positive valued transformations of these matrices. We demonstrate
also the above transformations can be realized in relevant composite quantum
systems by quantum engineering methods. The approach proposed allows one not
only to reproduce and generalize results of well-known logical systems
(Boolean, Lukasiewicz and so on) but also to classify and analyze from unified
point of view various actual problems in psychophysics and social sciences.Comment: 7 page
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