1,398 research outputs found
Low temperature dephasing saturation from elastic magnetic spin disorder and interactions
We treat the question of the low temperature behavior of the dephasing rate
of the electrons in the presence of elastic spin disorder scattering and
interactions. In the frame of a self-consistent diagrammatic treatment, we
obtain saturation of the dephasing rate in the limit of low temperature for
magnetic scattering, in agreement with the non-interacting case. The magnitude
of the dephasing rate is set by the strength of the magnetic scattering rate.
We discuss the agreement of our results with relevant experiments.Comment: This paper supersedes cond-mat/021022
The dynamical balance, transport and circulation of the Antarctic Circumpolar Current
The physical ingredients of the ACC circulation are reviewed. A picture of thecirculation is sketched by means of recent observations of the WOCE decade. Wepresent and discuss the role of forcing functions (wind stress, surfacebuoyancy flux) in the balance of the (quasi)-zonal flow, the meridionalcirculation and their relation to the ACC transport. Emphasis will be on theinterrelation of the zonal momentum balance and the meridional circulation, theimportance of diapycnal mixing and eddy processes. Finally, new model conceptsare described: a model of the ACC transport dependence on wind stress andbuoyancy flux, based on linear wave theory; and a model of the meridionaloverturning of the Southern Ocean, based on zonally averaged dynamics with eddyparameterization
Fast transverse phase space measurement system for GUNLAB a compact test facility for SRF photoinjectors
Superconducting radiofrequency photo electron injectors SRF guns are promising electron sources for the next generation of electron linear accelerators. The energy recovery linac ERL bERLinPro will employ a 1.5 cell 1.3 GHz SRF gun cavity with normal conducting high quantum efficiency photocathode to produce a 100mA CW electron beam with high brightness. We are currently working on a compact test beamline GunLab to investigate the phase space of the extracted electron beam and to optimize the drive laser as well RF parameters. The motivation for GunLab is to decouple the SRF gun development from the ERL development. The goal is to measure not only the complete 6 dimensional phase space of the extracted and accelerated bunches but also to investigate dark current and beam halo. In this paper we will discuss unique features of GunLab for the phase space measurements
Dissipate locally, couple globally: a sharp transition from decoupling to infinite range coupling in Josephson arrays with on-site dissipation
We study the T=0 normal to superconducting transition of Josephson arrays
with {\it on-site} dissipation. A perturbative renormalization group solution
is given. Like the previously studied case of {\it bond} dissipation (BD), this
is a "floating" to coupled (FC) phase transition. {\it Unlike} the BD
transition, at which {\it only} nearest-neighbor couplings become relevant,
here {\it all} inter-grain couplings, out to {\it infinitely} large distances,
do so simultaneously. We predict, for the first time in an FC transition, a
diverging spatial correlation length. Our results show the robustness of
floating phases in dissipative quantum systems.Comment: 7+ pages, 3 eps figures, Europhysics Letters preprint format, as
publishe
A large-scale evaluation framework for EEG deep learning architectures
EEG is the most common signal source for noninvasive BCI applications. For
such applications, the EEG signal needs to be decoded and translated into
appropriate actions. A recently emerging EEG decoding approach is deep learning
with Convolutional or Recurrent Neural Networks (CNNs, RNNs) with many
different architectures already published. Here we present a novel framework
for the large-scale evaluation of different deep-learning architectures on
different EEG datasets. This framework comprises (i) a collection of EEG
datasets currently including 100 examples (recording sessions) from six
different classification problems, (ii) a collection of different EEG decoding
algorithms, and (iii) a wrapper linking the decoders to the data as well as
handling structured documentation of all settings and (hyper-) parameters and
statistics, designed to ensure transparency and reproducibility. As an
applications example we used our framework by comparing three publicly
available CNN architectures: the Braindecode Deep4 ConvNet, Braindecode Shallow
ConvNet, and two versions of EEGNet. We also show how our framework can be used
to study similarities and differences in the performance of different decoding
methods across tasks. We argue that the deep learning EEG framework as
described here could help to tap the full potential of deep learning for BCI
applications.Comment: 7 pages, 3 figures, final version accepted for presentation at IEEE
SMC 2018 conferenc
The Pulsed Power Converter and Septum Magnet System for Injection into the Electron Storage Ring at ESRF
At ESRF, the European Synchrotron Radiation Facility in Grenoble, electrons are accelerated, via a 200Â MeV Linac and a 6Â GeV synchrotron booster, and injected into the storage ring at 10Â Hz rate. Two thin septum blade magnets and an eddy current sheet type septum magnet provide the final deflection of the injected beam. The operational requirements of the e- injection scheme and the resulting demanding hardware specifications are recalled. The pulsed septum magnets are briefly described. The design, circuit layout and construction of the power converters are related with emphasis on innovative aspects of general interest. Results of tests during commissioning are reported
Different activation energies in glucose uptake in Saccharomyces cerevisiae DFY1 suggest two transport systems
AbstractThe analysis of initial glucose uptake in Saccharomyces cerevisiae at 25°, 20°, 15° and 10°C by computer-assisted nonlinear regression analysis predicts two transport systems. The first demonstrates Michaelis–Menten kinetics and the second shows first order behaviour. The activation energies of these two systems were calculated by the Arrhenius equation at four different growth phases, namely early exponential (EE), middle exponential (ME2), late exponential (LE) and early stationary (ES) with 2% glucose in the batch medium. The activation energies calculated from the Vm values in EE, ME, LE and ES growth phases were 15.8±1.7, 13.5±1.0, 15.1±0.8 and 13.5±0.7 kcal/mol. These values are in agreement with activation energies calculated for the first mechanism, facilitated diffusion, which is the mechanism deduced from countertransport experiments. The activation energies derived for the second transport system from the first order rate constants in cells grown to EE, ME2, LE and ES were 8.0±2.1, 8.1±1.3, 9.6±3.0 and 7.5±2.6 kcal/mol. These values are still significantly higher than for free diffusion of glucose in water and lower as predicted for passage of glucose through the lipid phase. Therefore, we assume in addition to carrier-mediated facilitated diffusion the entrance of glucose into the cell through a pore
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