2,264 research outputs found
Edge channel mixing induced by potential steps in an integer quantum Hall system
We investigate the coherent mixing of co-propagating edge channels in a
quantum Hall bar produced by step potentials. In the case of two edge channels
it is found that, although a single step induces only a few percent mixing, a
series of steps could yield 50% mixing. In addition, a strong mixing is found
when the potential height of a single step allows a different number of edge
channels on the two sides of the step. Charge density probability has been also
calculated even for the case where the step is smoothened.Comment: final version: 7 pages, 6 figure
Subtleties on energy calculations in the image method
In this pedagogical work we point out a subtle mistake that can be done by
undergraduate or graduate students in the computation of the electrostatic
energy of a system containing charges and perfect conductors if they naively
use the image method. Specifically, we show that the naive expressions for the
electrostatic energy for these systems obtained directly from the image method
are wrong by a factor 1/2. We start our discussion with well known examples,
namely, point charge-perfectly conducting wall and point charge-perfectly
conducting sphere and then proceed to the demonstration of general results,
valid for conductors of arbitrary shapes.Comment: 9 pages, 2 figures; Major change in this version: subsection added to
Sect.4 (theorem generalization). Minor changes: title replaced; corrections
to the English; some explanatory comments adde
Entanglement detection for electrons via witness operators
We discuss an implementation of the entanglement witness, a method to detect
entanglement with few local measurements, in systems where entangled electrons
are generated both in the spin and orbital degrees of freedom.
We address the efficiency of this method in various setups, including two
different particle-hole entanglement structures, and we demonstrate that it can
also be used to infer information on the possible dephasing afflicting the
devices.Comment: 12 pages, 5 figures; published versio
Perceptions of an Electronic Medical Record (EMR): Lessons from a French Longitudinal Survey
AbstractThe goal of this longitudinal study is to examine the evolution of the perceptions, namely anxiety, ease of use, usefulness, misfit (not customization), trust and usefulness, related to an Electronic Medical Record (EMR) for the clinical staff in a French Teaching hospital. Two surveys were conducted first in September 2013 and second in December 2015, based on a questionnaire consisting of items on the Likert scale. As results, the correlation of all the variables between the two surveys is very significant (except for usefulness, for which the relationship is significant). This is not surprising, given previous studied focused on habits and learning related to technology adoption. Nevertheless, the increase is not spectacular and it makes necessary to evaluate EMR satisfaction and perceptions in order to elaborate a measure standard enabling comparisons and benchmarking among hospitals
Intercomparision of Monte Carlo radiation transport codes MCNPX, GEANT4, and FLUKA for simulating proton radiotherapy of the eye
Monte Carlo simulations of an ocular treatment beam- line consisting of a nozzle and a water phantom were carried out using MCNPX, GEANT4, and FLUKA to compare the dosimetric accuracy and the simulation efficiency of the codes. Simulated central axis percent depth- dose profiles and cross-field dose profiles were compared with experimentally measured data for the comparison. Simulation speed was evaluated by comparing the number of proton histories simulated per second using each code. The results indicate that all the Monte Carlo transport codes calculate sufficiently accurate proton dose distributions in the eye and that the FLUKA transport code has the highest simulation efficiency
A track-repeating algorithm for fast Monte Carlo dose calculations of proton radiotherapy
Monte Carlo codes are utilized for accurate dose calculations in proton radiation therapy research. While they are superior in accuracy to commonly used analytical dose calculations, they require significantly longer computation times. The aim of this work is to characterize a Monte Carlo track-repeating algorithm to increase computation speed without compromising dosimetric accuracy. The track-repeating approach reduced the CPU time required for a complete dose calculation in voxel- ized patient anatomy by more than two orders of magnitude, while on average reproducing the results from the traditional Monte Carlo approach within 4% dose difference and within 1-mm distance to agreement
Manipulating nonequilibrium magnetism through superconductors
Electrostatic control of the magnetization of a normal mesoscopic conductor
is analyzed in a hybrid superconductor-normal-superconductor system. This
effect stems from the interplay between the non-equilibrium condition in the
normal region and the Zeeman splitting of the quasiparticle density of states
of the superconductor subjected to a static in-plane magnetic field. Unexpected
spin-dependent effects such as magnetization suppression, diamagnetic-like
response of the susceptibility as well as spin-polarized current generation are
the most remarkable features presented. The impact of scattering events is
evaluated and let us show that this effect is compatible with realistic
material properties and fabrication techniques.Comment: 5 pages, 4 figure
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