2,508 research outputs found
Ray model and ray-wave correspondence in coupled optical microdisks
We introduce a ray model for coupled optical microdisks, in which we select
coupling-efficient rays among the splitting rays. We investigate the resulting
phase-space structure and report island structures arising from the
ray-coupling between the two microdisks. We find the microdisks's refractive
index to influence the phase-space structure and calculate the stability and
decay rates of the islands. Turning to ray-wave correspondence, we find many
resonances to be directly related to the presence of these islands. We study
the relation between the (ray-picture originating) island structures and the
(wave-picture originating) spectral properties of resonances, especially the
leakiness of the resonances which is represented as the imaginary part of the
complex wave vector.Comment: 9 pages, 8 figure
Harmonic Generation from Laser-Irradiated Clusters
The harmonic emission from cluster nanoplasmas subject to short, intense
infrared laser pulses is analyzed by means of particle-in-cell simulations. A
pronounced resonant enhancement of the low-order harmonic yields is found when
the Mie plasma frequency of the ionizing and expanding cluster resonates with
the respective harmonic frequency. We show that a strong, nonlinear resonant
coupling of the cluster electrons with the laser field inhibits coherent
electron motion, suppressing the emitted radiation and restricting the spectrum
to only low-order harmonics. A pump-probe scheme is suggested to monitor the
ionization dynamics of the expanding clusters.Comment: 4 pages, ReVTeX
Crystal structure of LaTiO_3.41 under pressure
The crystal structure of the layered, perovskite-related LaTiO_3.41
(La_5Ti_5O_{17+\delta}) has been studied by synchrotron powder x-ray
diffraction under hydrostatic pressure up to 27 GPa (T = 295 K). The
ambient-pressure phase was found to remain stable up to 18 GPa. A sluggish, but
reversible phase transition occurs in the range 18--24 GPa. The structural
changes of the low-pressure phase are characterized by a pronounced anisotropy
in the axis compressibilities, which are at a ratio of approximately 1:2:3 for
the a, b, and c axes. Possible effects of pressure on the electronic properties
of LaTiO_3.41 are discussed.Comment: 5 pages, 6 figure
Tpr1, a Schizosaccharomyces pombe protein involved in potassium transport
AbstractThe Schizosaccharomyces pombe Tpr1 was isolated as suppressor of the Saccharomyces cerevisiae Î trk1,2 potassium uptake deficient phenotype. Tpr1, for tetratrico peptide repeat, encodes a 1039 amino acid residues protein with several reiterated TPR units displaying significant homology to p150TSP, a recently identified phosphoprotein of mouse, to S. cerevisiae CTR9 and to related sequences of human, Caenorhabditis elegans, Methanoccocus jannaschii and Arabidopsis thaliana. Expression of Tpr1 restored growth on 0.2 mM K+ media, induced K+ transport with a KT of 4.6 mM and resumed inward currents of â90 pĂ
at â250 mV (pH 7.2) conducting K+ and other alkali-metal ions. The tetratrico peptide repeat is a degenerate motif of 34 amino acids that is repeated several times within TPR-containing proteins and has been suggested to mediate protein-protein interactions. The sequence and putative binding properties of Tpr1 suggest the protein unlikely as transporter but involved in the enhancement of K+ uptake via conventional carriers
Norm Optimal Iterative Learning Control with Application to Problems in Accelerator based Free Electron Lasers and Rehabilitation Robotics
This paper gives an overview of the theoretical basis of the norm optimal approach to iterative learning control followed by results that describe more recent work which has experimentally benchmarking the performance that can be achieved. The remainder of then paper then describes its actual application to a physical process and a very novel application in stroke rehabilitation
Trapping mechanism in overdamped ratchets with quenched noise
A trapping mechanism is observed and proposed as the origin of the anomalous
behavior recently discovered in transport properties of overdamped ratchets
subject to external oscillatory drive in the presence of quenched noise. In
particular, this mechanism is shown to appear whenever the quenched disorder
strength is greater than a threshold value. The minimum disorder strength
required for the existence of traps is determined by studying the trap
structure in a disorder configuration space. An approximation to the trapping
probability density function in a disordered region of finite length included
in an otherwise perfect ratchet lattice is obtained. The mean velocity of the
particles and the diffusion coefficient are found to have a non-monotonic
dependence on the quenched noise strength due to the presence of the traps.Comment: 21 pages, 6 figures, to appear in PR
Superconvergent Perturbation Method in Quantum Mechanics
An analogue of Kolmogorov's superconvergent perturbation theory in classical
mechanics is constructed for self adjoint operators. It is different from the
usual Rayleigh--Schr\"odinger perturbation theory and yields expansions for
eigenvalues and eigenvectors in terms of functions of the perturbation
parameter.Comment: 11 pages, LaTe
Extremely Small Energy Gap in the Quasi-One-Dimensional Conducting Chain Compound SrNbO
Resistivity, optical, and angle-resolved photoemission experiments reveal
unusual one-dimensional electronic properties of highly anisotropic
SrNbO. Along the conducting chain direction we find an extremely small
energy gap of only a few meV at the Fermi level. A discussion in terms of
typical 1D instabilities (Peierls, Mott-Hubbard) shows that neither seems to
provide a satisfactory explanation for the unique properties of SrNbO.Comment: 4 pages, 3 figure
Ny Udskiftning, Hoveriets OphĂŠvelse m. m., under Stamhuset Bidstrup.
Ny Udskiftning, Hoveriets OphĂŠvelse m. m., under Stamhuset Bidstrup
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