Search

We synthesize the quasi-likelihood, maximum-likelihood, and quasioptimal algorithms for estimating the arrival time and duration of a radio signal with unknown amplitude and initial phase. The discrepancies between the hardware and software realizations of the estimation algorithm are shown. The characteristics of the synthesized-algorithm operation efficiency are obtained. Asymptotic expressions for the biases, variances, and the correlation coefficient of the arrival-time and duration estimates, which hold true for large signal-to-noise ratios, are derived. The accuracy losses of the estimates of the radio-signal arrival time and duration because of the a priori ignorance of the amplitude and initial phase are determined.

We synthesize the quasilikelihood, maximum-likelihood, and quasioptimal algorithms for estimating the moments of appearance and disappearance of a radio signal with an arbitrary shape of the envelope function and unknown amplitude and initial phase. Asymptotic characteristics of the operation efficiency of the synthesized algorithm are found.

We study the solutions of the stationary Schrodinger equation in unbounded domains on Riemannian manifolds with noncompact boundary. Our approach to the statement of boundary value problems is based on the notion of a class of equivalent functions. We obtain sufficient conditions for the solvability of boundary value problems and prove the solvability of the Dirichlet problem on the cone of a model manifold with continuous boundary data on the boundary.

We study the problem of solvability of some boundary value problems on noncompact Riemannian manifolds with ends. We obtain the conditions for existence and uniqueness of solutions to the problems as well as the conditions for the fulfillment of Liouville-type theorems for harmonic functions on the manifolds.

The advantages and conditions to observe the phase conjugation in photorefractive crystals by degenerate stimulated backscattering via diffusion gratings are discussed. Different version of discrimination physics for self conjugation in selfstarting backscattering are demonstrated. Several possibilities to obtain self- and double-conjugation by means of four-wave mixing on reflecting gratings in photorefractive crystals as well as some related problems are pointed out.

We have investigated backward stimulated diffusive scattering of light with a time-varying speckle structure by photorefractive crystals in which the nonlinearity mechanism is diffusion-driven. We show that the efficiency and conjugated fraction for this process depend on the ratio of the coherence time to the dielectric relaxation time of the medium.

It was demonstrated that holographic gratings could be formed by temporally nonoverlapping optical beams. Effects involving coherent erasure by an individual pulse must be small to achieve efficient grating formation.

A possibility of a formation of holographic gratings with non-overlapping electromagnetic pulses is demonstrated. The coherent erosion by a single pulse should be relatively low to permit an efficient hologram formation.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Experimental study of stimulated diffusion backscattering in photorefractive crystals demonstrates that the phase conjugate component grows faster than other components of the scattered field in the case of pump radiation with a moving speckle structure.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present detailed experimental investigation of scattered radiation spatial structure in the geometry of a transmission grating photorefractive passive ring mirror (Fig. 1) and compare our results with the predictions of Ref.[1]. According to the theory, behaviour of a ring mirror in the limit of large Fresnel numbers is determined by two scale variation coefficients: α// and α⊥. Scale variation coefficient α// is the ratio of the width of the pumping beam 4 in the plane of intersection to that of the pumping beam 2 (see Fig. 1). For | α// | α// | >1 wider, than beam 2. The same with the scale variation coefficient α⊥, but for the direction, perpendicular to the intersection plane.

A reflection-grating self-pumped passive ring mirror is experimentally fabricated in a photorefractive KNbO(3) crystal. The observed values of nonlinear reflectivity are as much as 50%, and the response time of the mirror is several milliseconds.

Interaction of alpha-tocopherol with free fatty acids in bovine retinal photoreceptor membranes was studied using ESR spin-probe technique and measurements of rhodopsin thermal denaturation rates. Exogenous alpha-tocopherol incorporated into photoreceptor membranes prevented thermal destabilization of rhodopsin caused by free fatty acids. The efficiency of the stabilizing action of alpha-tocopherol directly depended both on the chain length and the degree of fatty acid unsaturation.

The alpha-tocopherol content and fatty acid composition of lipids in various types of nervous tissue membranes were studied. The transbilayer distribution of alpha-tocopherol and polyunsaturated fatty acids in liposomes and plasma membranes of synaptosomes was examined. It was shown that both phosphatidylethanolamine and phosphatidylserine are localized predominantly in the inner monolayer and they contain the bulk of polyenoic fatty acid residues. alpha-Tocopherol incorporated into liposomes from synaptosome plasma membrane lipids and present in synaptosome plasma membranes is also predominantly localized in the inner monolayers. No asymmetrical distribution of incorporated alpha-tocopherol was observed in liposomes prepared from a single phospholipid, e.g., dioleoylphosphatidylcholine.

Interaction of alpha-tocopherol with free fatty acids in bovine retinal photoreceptor membranes was studied using ESR spin-probe technique and measurements of rhodopsin thermal denaturation rates. Exogenous alpha-tocopherol incorporated into photoreceptor membranes prevented thermal destabilization of rhodopsin caused by free fatty acids. The efficiency of the stabilizing action of alpha-tocopherol directly depended both on the chain length and the degree of fatty acid unsaturation.