Random walk in dynamically disordered chains: Poisson white noise disorder

Exact solutions are given for a variety of models of random walks in a chain with time-dependent disorder. Dynamic disorder is modeled by white Poisson noise. Models with site-independent (global) and site-dependent (local) disorder are considered. Results are described in terms of an affective random walk in a nondisordered medium. In the cases of global disorder the effective random walk contains multistep transitions, so that the continuous limit is not a diffusion process. In the cases of local disorder the effective process is equivalent to usual random walk in the absence of disorder but with slower diffusion. Difficulties associated with the continuous-limit representation of random walk in a disordered chain are discussed. In particular, we consider explicit cases in which taking the continuous limit and averaging over disorder sources do not commute.     

Filter design of composite trade-off filter with support regions to obtain invariant pattern recognition with defocused images

The discrimination capacity (DC) measures the ability of the filter in a pattern recognition problem to discriminate the target against other objects in the input scene. If the input scene is degraded by a defect of focus, then the DC is degraded and the pattern recognition process is worse. In this paper, we present a methodology based in the selection of ring frequency bands and in the design of the trade-off filters taking into account these frequencies to obtain several information channels. The information of all the channels is fused by means of the addition of all the channels and the geometric mean of them. Also individual channel analysis is shown. The influence on the DC and SNR of the added white noise in the input image is presented.     

Some geometric spectral properties of N-body Schrödinger operators

Communicated by J. B. McLeod     

On the measurement of stress in solid propellant

The problems related to the direct measurement of stresses in solid propellant are identified and reviewed. The piezoresistance phenomenon is discussed and it is shown how this phenomenon can be utilized to measure stresses in elastomers and solid propellant. One version of a piezoresistive stress transducer is used to measure radial stresses in an uncontained thick-walled elastic cylinder which is internally pressurized. A smaller similar version of the piezoresistive stress transducer is employed in a rosette configuration to measure the stress state at five critical locations in a quarter-scale Surveyor solid-propellant motor three times during a four-year storage period. The instrumentation and calibration of these piezoresistive stress transducers are briefly described.     

Post-Newtonian equations for the metric perturbation generated by a rotating elastic earth

By using Synge's approximation method to describe the unperturbed problem, we obtain the equations for the gravitational field perturbation and the Lagrangian displacement that occur when an isolated and initially self-gravitating spherical and static elastic earth gets into steady rotation. These equations are explicitly derived in an order of approximation for the initial problem where both rotation and elastic structure manifest themselves in the perturbed state.     

A novel hybrid inorganic-metalorganic compound based on a polymeric polyoxometalate and a copper complex: synthesis, crystal structure and topological studies

Reaction of monosubstituted Keggin polyoxometalates (POMs) and [Cu(ac)(pmdien)]+ generated in situ led to the formation of the hybrid metal organic-inorganic compound K5[Cu(ac)(pmdien)][SiW11CuO39].12H2O; its crystal structure and magnetic properties have also been determined. The packing of this compound can be viewed as a stacking of hydrogen-bonded chiral double chains, with the cationic complexes located between the two-dimensional arrangement of POM double chains. DFT calculations performed on [Cu(ac)(pmdien)]+ suggest that the distortion presented in this cationic copper complex is due to electronic effects. An AIM stability study of the cationic copper complex, in order to determine the relationship between the bond angle Cu-O-C and the denticity of the acetate ligand, has been carried out. Topological analyses over the polyhedral distortion, both of the monosubstituted polyanion and copper complexes, have been performed by means of continuous shape measures (CSM).     

Dynamic aspect of bacteriorhodopsin as a typical membrane protein as revealed by site-directed solid-state 13C NMR

We demonstrate here a general feature of dynamic aspect of membrane proteins as revealed by site-directed 13C NMR studies on bacteriorhodopsin (bR) as a typical membrane protein and a variety of mutants at ambient temperature. 13C NMR signals of [3-13C]Ala- or [1-13C]Val-labeled proteins were assigned regio-specifically with reference to the data of the conformation-dependent 13C chemical shifts from model polypeptides, followed by site-specific assignment based on site-directed mutants. Revealed picture of membrane protein at ambient temperature is not static in contrast to anticipation from crystalline structures but flexible enough to undergo a variety of local fluctuations with frequencies from 10(2) to 10(8)Hz, as pointed out already. This picture was further refined by taking into account of residue-specific dynamics of interfacial domains between the surface and inner part of the transmembrane helices and conformational fluctuation induced by the presence of a kinked structure. The residue-specific dynamics of the former was revealed by observation of broadened or suppressed peaks from the interfacial domains caused by acquisition of internal fluctuation motions interfered with frequencies of proton decoupling or magic angle spinning. The presence of such suppressed peaks due to molecular fluctuations in the interfacial domains was further confirmed by insensitivity of the peak-intensities from the interfacial domains in spite of the presence of accelerated relaxation rate to nearby residues from surface bound Mn2+ ion. Further, conformational change of the transmembrane alpha-helix F due to a plausible kinked structure at Pro 186 was confirmed in view of specific displacements of Ala 184 and Val 187 13C NMR peaks from chemically synthesized [3-13C]Ala(184)-, [1-13C]Val(187)-labeled wild type and P186L mutant of transmembrane fragment F(164-194) incorporated into lipid bilayer. It is emphasized that the observed displacement of [3-13C]-labeled Ala 184 peak at 17.4 ppm in the presence of kinked structure in this model peptide is consistent with that of intact protein at 17.27 ppm.     

All-optical image processing with cavity type II second-harmonic generation

The possibilities offered by type II intracavity second-harmonic generation for all-optical parallel processing of images are investigated. By injecting an image in a linearly polarized pump beam and a homogeneous field with orthogonal polarization, we obtain, according to the value of the latter, either frequency and polarization transfer or contrast enhancement and contour recognition. Noise-filtering effects are also predicted.     

Deformable Asymmetric Tops under Similarity Transformations

In this paper the configurations of relative equilibrium are determined for a deformable heavy top with a fixed point constrained to deform only by similarity transformations. We analyze the nonlinear orbital stability using the reduced energy–momentum method for configurations such that the center of the mass vector is parallel to the axis of gravity and coincides with an eigenvector of the Euler tensor. In addition, we study these conditions of stability for a specific deformable top given by a hyperelastic material of the Saint Venant–Kirchhoff type, and describe how these conditions are particularized in the special case of almost rigid tops.     

Two-photon cavity solitons in active optical media

We show that broad-area cascade lasers with no absorbing intracavity elements support the spontaneous formation of two-dimensional bright localized structures in a dark background. These cavity solitons consist of islands of two-photon emission embedded in a background of single-photon emission. We discuss the mechanisms through which these structures are formed and interact, along with their properties and stability.