Localization of inhomogeneities in diffuse optical tomography based on late arriving photons

An algorithm for localizing inhomogeneities in pulsed diffuse optical tomography is proposed and implemented. A distinctive feature of this technique is the formation of an initial approximation to the spatial distributions of the absorption and scattering coefficients in a biomedical object under study based on the angle-dependent homogeneity index, HI(a). The method allows one to determine the approximate optical structure of the object using late arriving photons and thus solve more rapidly the inverse problem. The suggestion that all absorbing and scattering inhomogeneities in an object under study are spherical also simplifies and enhances image reconstruction.     

On the distribution of the zeros of the cubic <Emphasis Type="Italic">L</Emphasis>-function

The distribution of the real parts of the zeros of the cubic L-function is considered. Some observations based on numerical results are presented. Bibliography: 4 titles.     

Computation of the zeros of the <Emphasis Type="Italic">L</Emphasis>-function associated with the cubic theta function

The paper considers the L-function associated with the Kubota-Patterson cubic theta function. A method for computing values of the L-function is developed, and some conjectures on the distribution of its zeros are advanced and supported by numerical results. Bibliography: 12 titles. Translated from Zapiski Nauchnykh. Seminarov POMI, Vol. 357, 2008, pp. 180–194.     

Deformations of CCR,their *-representations,and enveloping C*-algebras

In this paper we provide a review of recent results related to the representation theory and properties of enveloping C* -algebras of Wick deformations for canonical commutative and anticommutative relations of quantum mechanics.     

Stability of the flow of weakly electro-conductive fluid in the presence of a spiral magnetic field

The stability to small disturbances of the flow in a pipe of annular cross section is considered in the presence of a spiral magnetic field. The investigated duct configuration consists of two infinite coaxial cylinders between which a weakly electroconductive viscous incompressible fluid is placed, which moves under the axial pressure gradient. The azimuthal magnetic field is created by a current flowing through the central cylinder, and the longitudinal magnetic field is created by an external solenoid. The magnetohydrodynamic approximation is used. It is found that the introduction of the azimuthal magnetic field may lead to a flow destabilization as compared to the case of only the longitudinal magnetic field.     

On studying energy dependences of π− p elastic scattering cross sections in the 33–55 GeV/c range

The π^? p differential elastic scattering cross sections have been measured for eight momenta in the 33–55 GeV/c range. The energy dependence of the slope and of the total elastic scattering cross sections has been determined experimentally. The results are compared with the known data. The experimental data are compared both with the Regge pole model and with the quasi-potential one.     

Determination of flow velocity vector based on Doppler shift and spectrum broadening with optical coherence tomography

We describe a technique that uses Doppler optical coherence tomography to estimate accurately the scattering fluid-flow velocity without a priori knowledge of the Doppler angle. Our technique is based on the combined use of the Doppler shift on the interference signal and the Doppler spectrum broadening caused by the particles moving across the probe beam. It is shown that the estimated values of the Doppler angle and average fluid velocity from the experiments agree well with the preset values.     

Physical Coordinates as Dynamic Variables in Relativistic Theories

We show that relativistic theories of strings and of gravity that are invariant with respect to general covariance transformations can be formulated in terms of physical coordinates with nonzero evolution Hamiltonians by identifying these coordinates with some dynamic variables.     

Field-Like spin-transfer torque in a chiral helimagnet

Based on the microscopic model of sd coupling between free electrons and local moments, we present a quantum calculation of a nonadiabatic spin-transfer torque in a chiral helimagnet.