2,867 research outputs found
Stationary phase slip state in quasi-one-dimensional rings
The nonuniform superconducting state in a ring in which the order parameter
vanishing at one point is studied. This state is characterized by a jump of the
phase by at the point where the order parameter becomes zero. In uniform
rings such a state is a saddle-point state and consequently unstable. However,
for non-uniform rings with e.g. variations of geometrical or physical
parameters or with attached wires this state can be stabilized and may be
realized experimentally.Comment: 6 pages, 7 figures, RevTex 4.0 styl
Microcomputer-based artificial vision support system for real-time image processing for camera-driven visual prostheses
It is difficult to predict exactly what blind subjects with
camera-driven visual prostheses (e.g., retinal implants) can perceive.
Thus, it is prudent to offer them a wide variety of image processing
filters and the capability to engage these filters repeatedly in any userdefined
order to enhance their visual perception. To attain true portability,
we employ a commercial off-the-shelf battery-powered general
purpose Linux microprocessor platform to create the
microcomputer-based artificial vision support system (µAVS^2) for
real-time image processing. Truly standalone, µAVS^2 is smaller than a
deck of playing cards, lightweight, fast, and equipped with USB, RS-
232 and Ethernet interfaces. Image processing filters on µAVS^2 operate
in a user-defined linear sequential-loop fashion, resulting in vastly
reduced memory and CPU requirements during execution. µAVS^2
imports raw video frames from a USB or IP camera, performs image
processing, and issues the processed data over an outbound Internet
TCP/IP or RS-232 connection to the visual prosthesis system. Hence,
µAVS^2 affords users of current and future visual prostheses independent
mobility and the capability to customize the visual perception
generated. Additionally, µAVS^2 can easily be reconfigured for other
prosthetic systems. Testing of µAVS^2 with actual retinal implant carriers
is envisioned in the near future
Carbon incorporation effects and reaction mechanism of FeOCl cathode materials for chloride ion batteries
Metal oxychlorides are proved to be new cathode materials for chloride ion batteries. However, this kind of cathode materials is still in a very early stage of research and development. The obtained reversible capacity is low and the electrochemical reaction mechanism concerning chloride ion transfer is not clear. Herein, we report FeOCl/carbon composites prepared by mechanical milling of the as-prepared FeOCl with carbon nanotube, carbon black or graphene nanoplatelets as cathode materials for chloride ion batteries. The electrochemical performance of the FeOCl electrode is evidently improved by the incorporation of graphene into the cathode. FeOCl/graphene cathode shows a high reversible capacity of 184 mAh g−1 based on the phase transformation between FeOCl and FeO. Two stages of this phase transformation are observed for the FeOCl cathode. New insight into the reaction mechanism of chloride ion dissociation of FeOCl is investigated by DFT + U + D2 calculations
A qubit strongly-coupled to a resonant cavity: asymmetry of the spontaneous emission spectrum beyond the rotating wave approximation
We investigate the spontaneous emission spectrum of a qubit in a lossy
resonant cavity. We use neither the rotating-wave approximation nor the Markov
approximation. The qubit-cavity coupling strength is varied from weak, to
strong, even to lower bound of the ultra-strong. For the weak-coupling case,
the spontaneous emission spectrum of the qubit is a single peak, with its
location depending on the spectral density of the qubit environment. Increasing
the qubit-cavity coupling increases the asymmetry (the positions about the
qubit energy spacing and heights of the two peaks) of the two spontaneous
emission peaks (which are related to the vacuum Rabi splitting) more.
Explicitly, for a qubit in a low-frequency intrinsic bath, the height asymmetry
of the splitting peaks becomes larger, when the qubit-cavity coupling strength
is increased. However, for a qubit in an Ohmic bath, the height asymmetry of
the spectral peaks is inverted from the same case of the low-frequency bath,
when the qubit is strongly coupled to the cavity. Increasing the qubit-cavity
coupling to the lower bound of the ultra-strong regime, the height asymmetry of
the left and right peak heights are inverted, which is consistent with the same
case of low-frequency bath, only relatively weak. Therefore, our results
explicitly show how the height asymmetry in the spontaneous emission spectrum
peaks depends not only on the qubit-cavity coupling, but also on the type of
intrinsic noise experienced by the qubit.Comment: 10pages, 5 figure
Manifestation of the magnetic resonance mode in the nodal quasiparticle lifetime in superconducting cuprates
Studying the nodal quasiparticles in superconducting cuprates by
photoemission with highly improved momentum resolution, we show that a new
"kink" feature in the scattering rate is a key to uncover the nature of
electron correlations in these compounds. Our data provide evidence that the
main doping independent contribution to the scattering can be well understood
in terms of the conventional Fermi liquid model, while the additional doping
dependent contribution has a magnetic origin. This sheds doubt on applicability
of a phonon-mediated pairing mechanism to high temperature superconductors.Comment: rextex, 4 pages, 4 figure
Frenkel and charge transfer excitons in C60
We have studied the low energy electronic excitations of C60 using momentum
dependent electron energy-loss spectroscopy in transmission. The momentum
dependent intensity of the gap excitation allows the first direct experimental
determination of the energy of the 1Hg excitation and thus also of the total
width of the multiplet resulting from the gap transition. In addition, we could
elucidate the nature of the following excitations - as either Frenkel or charge
transfer excitons.Comment: RevTEX, 3 Figures, to appear in Phys. Rev.
Microcomputer-based artificial vision support system for real-time image processing for camera-driven visual prostheses
Numerical simulation of drop impact and rebound phenomena on smooth and micro-structured hydrophobic surfaces
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