1,038 research outputs found
Theory of Spin polarized Tunneling in Superconducting Sr2RuO4
A theory of tunneling conductance in ferromagnetic metal/insulator/triplet -
supercondcutor junctions is presented for unitary and non-unitary spin triplet
pairing states which are promising candidates for the superconducting paring
symmetry of Sr2RuO4. As the magnitude of the exchange interaction in the
ferromagnetic metal is increased, the conductance for the unitary pairing state
below the energy gap is reduced in contrast to the case for the non-unitary
pairing state
Strong coupling of the cyclotron motion of surface electrons on liquid helium to a microwave cavity
The strong coupling regime is observed in a system of two-dimensional electrons whose cyclotron motion is coupled to an electro-magnetic mode in a Fabry-Perot cavity resonator. The Rabi splitting of eigenfrequencies of coupled motion is observed both in the cavity reflection spectrum and ac current of electrons, the latter probed by measuring their bolometric photoresponse. Despite the fact that similar observations of the Rabi splitting in many-particle systems have been described as a quantum-mechanical effect, we show that the observed splitting can be explained completely by a model based on the classical electrodynamics
A mechanism with severing near barbed ends and annealing explains structure and dynamics of dendritic actin networks
Single molecule imaging has shown that part of actin disassembles within a few seconds after incorporation into the dendritic filament network in lamellipodia, suggestive of frequent destabilization near barbed ends. To investigate the mechanisms behind network remodeling, we created a stochastic model with polymerization, depolymerization, branching, capping, uncapping, severing, oligomer diffusion, annealing, and debranching. We find that filament severing, enhanced near barbed ends, can explain the single molecule actin lifetime distribution, if oligomer fragments reanneal to free ends with rate constants comparable to in vitro measurements. The same mechanism leads to actin networks consistent with measured filament, end, and branch concentrations. These networks undergo structural remodeling, leading to longer filaments away from the leading edge, at the +/- 35𝑜 orientation pattern. Imaging of actin speckle lifetimes at sub-second resolution verifies frequent disassembly of newly-assembled actin. We thus propose a unified mechanism that fits a diverse set of basic lamellipodia phenomenology
Assessment of hygienic conditions of ground pepper (Piper nigrum L.) on the market in São Paulo city, by means of two methodologies for detecting the light filth
Pepper should to be collected, processed, and packed under optimum conditions to avoid the presence of foreign matter. The hygienic conditions of ground pepper marketted in São Paulo city were assessed in determining the presence of foreign matter by means of two extraction methodologies. This study was carried out during a six-month time period from May to September 2006. The occurrence of light impurities was determined either by the flotation technique following the methodology recommended by AOAC or by enzyme – linked immunosorbent assay (ELISA). It was observed that 100% of the examined samples contained insect fragments, and many samples were housing more than one type of foreign matter. Twentytwo percent of samples were unqualified for consumption owing to the occurrence of rodent hairs. For the calibration of ELISA test for quantification of insect contamination level in pepper samples, a range of standard-infested samples was prepared in adding 1, 2, 4, 8 and 10 insects in a control sample to estimate the number of insects in the analyzed samples by measuring optical densities (OD) values with a spectrophotometer. Among the 22 samples, 36.4% of samples presented OD values close to that corresponding to the standard infested with eight insects, 40.9% of samples were comparable to OD of the standard infested with four insects, 18.2% comparable to standard with 10 insects, and 4.5% to the standard with two insects. According to the results observed in the present study, the technique described in AOAC official methods manual was found more suitable for detecting not only the insects but also the additional impurities in analyzed samples, while ELISA is specific to detect myosin from the insect muscle, which undergoes serious degradation with time. Keywords: Pepper, ELISA test , Light filth, AOAC official method
Theory of magnetotunneling spectroscopy in spin triplet p-wave superconductors
We study the influence of a magnetic field on the zero-bias conductance
peak (ZBCP) due to zero-energy Andreev bound state (ZES) in normal metal /
unconventional superconductor. For p-wave junctions, ZBCP does not split into
two by even for sufficiently low transparent junctions, where ZBCP clearly
splits for d-wave. This unique property originates from the fact that for
p-wave superconductors, perpendicularly injected quasiparticle form ZES, which
contribute most dominantly on the tunneling conductance. In addition, we show
that for +i-wave superconductor junctions, the height of ZBCP is
sensitive to due to the formation of broken time reversal symmetry state.
We propose that tunneling spectroscopy in the presence of magnetic field,
, , is an promising method to determine the pairing
symmetry of unconventional superconductors.Comment: 4 pages, 6 figures, using jpsj2.cl
Edge states and determination of pairing symmetry in superconducting Sr2RuO4
We calculate the energy dispersion of the surface Andreev states and their
contribution to tunneling conductance for the order parameters with horizontal
and vertical lines of nodes proposed for superconducting Sr2RuO4. For vertical
lines, we find double peaks in tunneling spectra reflecting the van Hove
singularities in the density of surface states originating from the turning
points in their energy dispersion. For horizontal lines, we find a single
cusp-like peak at zero bias, which agrees very well with the experimental data
on tunneling in Sr2RuO4.Comment: 6 pages, 6 figures. V.2: comparison with experiment added and
discussion of horizontal nodes expanded. v.3: significant expansion: 1 figure
and 2 pages added. v.4: acknowledgements added. Additional viewgraphs with
experimental and theoretical curves superimposed are available at
http://www2.physics.umd.edu/~yakovenk/talks/Sr2RuO4
Theory of tunneling spectroscopy in superconducting Sr2RuO4
A theory for tunneling spectroscopy in normal metal /insulator/triplet
superconductor junction is presented. We assume two kinds of non-unitary
triplet superconducting states which are the most promising states for
SrRuO. The calculated conductance spectra showzero-bias peaks as
well as gap structures. The existences of residual components in the spectra
reflect the non-unitary properties of superconducting states.Comment: 5pages, 4figures(included), to be published in Phys.Rev.B 56, (1997
Josephson effect test for triplet pairing symmetry
The critical current modulation and the spontaneous flux of the vortex states
in corner Josephson junctions between SrRuO and a conventional s-wave
superconductor are calculated as a function of the crystal orientation, and the
magnetic field. For SrRuO we assume two nodeless p-wave pairing states.
Also we use the nodal -wave states and , and one special p-wave state having line nodes. It is seen that the
critical current depends solely on the topology of the gap.Comment: 22 pages, 12 figure
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