We develop low-dimensional models for the evolution of a free shear layer in a periodic domain. The goal is to obtain models simple enough to be analyzed using standard tools from dynamical systems theory, yet including enough of the physics to model nonlinear saturation and energy transfer between modes (e.g., pairing). Recently, experiments have suggested that high-frequency forcing of shear ...

In past years we have witnessed remarkable progress in the study of exclusive charmless B decays. Experimentally, CLEO [1] has discovered many new two-body decay modes B ! K ; K; K; K ; K ; 0 ; !K and found a possible evidence for B ! K . Moreover, CLEO has provided new improved upper limits for many other decay modes. While all the measured channels are penguin dominated, the most recently obs...

In clustering algorithms, choosing a subset of representative examples is very important in data set. Such ''exemplars " can be found by randomly choosing an initial subset of data objects and then iteratively refining it, but this works well only if that initial choice is close to a good solution. In this paper, based on the frequency of attribute values, the average density of an object is de...

The square and kagome lattices with nearest-neighbor springs of spring constant k are isostatic with a number of zero-frequency modes that scale with their perimeter. We analytically study the approach to this isostatic limit as the spring constant k' for next-nearest-neighbor bonds vanishes. We identify a characteristic frequency omega* approximately square root of k' and length l* approximate...

We present a complete study of R-parity violating supersymmetric effects in eleven exclusive semi-leptonic b → (s, d)ν ¯ ν decays, including B + u → K (*)+ ν ¯ ν, B 0 d → K (*)0 ν ¯ ν, B 0 s → φν ¯ ν, B 0 d → π 0 (ρ 0)ν ¯ ν, B + u → π + (ρ +)ν ¯ ν and B 0 s → K (*)0 ν ¯ ν decay modes, and we find those eleven modes are very sensitive to the constrained R-parity violating couplings. We derive st...

Raman-scattering measurements on single crystals of K2SO4, Rb2SO4, and Cs2SO4 have been made at both room and liquid-nitrogen temperatures. Lattice-dynamical calculations, based on a rigid-ion model using the Gordon-Kim method to calculate the short-range potentials, were performed. The influence of the alkali-metal ions on the lattice-dynamical properties of the crystals is discussed. ©1991 Th...

in this paper, we investigate variation of the wavelength, intensity and polarization of the self-assembled inas/gaas quantum dots emission by microphotoluminescence spectroscopy at the liquid helium temperature. the microcavity wafer sample is grown by molecular beam epitaxy (mbe) and chemically etched into the micropillar structure (with elliptical cross section - long and short axis 2µm×1.5µ...

The density fluctuation spectrum N(k, ω) is calculated for the t-J model in the low-doping regime using a slave-fermion method for the constrained fermions. The obtained results for N(k, ω) are in good agreement with diagonalization results. The density response is characterized by incoherent, momentum dependent spectral functions reaching up to energies ∼ 8t and a low-energy structure at energ...

The platinum anti-cancer agents cisplatin and carboplatin bind to the histidine 15 residue in the model protein hen egg white lysozyme. By using temperatures either side of the protein glass transition state (∼180 K), several platinum binding modes are seen and show that not all these platinum modes are stable. In particular, the mean square displacement vibration amplitudes of the cisplatin an...

Context. Stellar oscillations are an important tool to probe the interior of a star. Subdwarf B stars are core helium burning objects, but their formation is poorly understood as neither single star nor binary evolution can fully explain their observed properties. Since 1997 an increasing number of sdB stars has been found to pulsate forming two classes of stars (the V361 Hya and V1093 Her star...