Asymptotic and boundary integral formulae for the computational reconstruction of small conductivity imperfections

In this paper we investigate the electrostatic problem of determining conductivity profiles from the knowledge of boundary currents and voltages. We obtain an improved estimate for the voltage potential of a two-dimensional conductor having finitely many circular inclusions and piecewise constant conductivity profile. We derive an asymptotic expansion for the voltage potential in terms of the reference voltage potential and the location, size, and conductivity of the inhomogeneities. This representation is used to formulate the nonlinear least squares problem for estimating the location and size of the inhomogeneities. Required boundary data for the voltage potential are generated numerically by solving a system of integral equations. Computational experiments are presented to demonstrate the effectiveness of our identification procedure.     

Passage of ion beams through parallel grids

Analytical expressions for the mathematical expectation and dispersion of the time of flight of a nonrelativistic charged particle through a multielectrode system consisting of parallel grids are derived. These expressions can be useful in design optimization, for example, of plasma-confining grid systems and time-of-flight mass spectrometers.     

Investigation of the structural elements of a fullerene within the static-fluctuation approximation of the Hubbard model

The anticommutator Green’s functions, correlation functions, and ground-state energies for closed atomic structures that consist of five or six atoms and are structural elements of a fullerene are calculated within the static-fluctuation approximation of the Hubbard model. The results of the calculations are analyzed and compared with the data available in the literature.     

Ultrashort pulse laser osteotomy

Laser treatment of bone tissue has already been the subject of many studies to find substitutes for mechanical instruments that are nowadays used in implantology and orthopaedics. Mainly lasers with pulse durations in the μs region have been tested leaving surface features that are not always satisfactory. Therefore, in the present study laser osteotomy has been performed with a 330 fs Yb:glass laser, λ = 1040 nm, at a pulse repetition rate of 1 kHz. For bovine spongiosa, compacta, and cartilage, the ablation thresholds as well as the ablation rates for various pulse energies have been determined. Additionally, quadratic areas have been ablated in bone tissue. The remaining morphology has been analyzed via scanning electron microscopy. Laser ablation has also been performed with an Er, Cr:YSGG laser, λ = 2780 nm, PRR = 20 Hz, τ ～ 50 μs. The results of USPL and Erbium laser ablation are compared.     

Discovery of a new long-lived isomeric state in 125Ce

A new long-lived isomeric state in the near proton dripline nucleus ¹²⁵Ce has been identified with Schottky mass spectrometry at GSI. The excitation energy E ^* = 103(12)keV and the decay time of 193(1)s have been obtained from a single stored fully ionized ^125m Ce⁵⁸⁺ ion. The data implies an E3 transition and a 1/2⁺ assignment for the spin of the isomer.     

Diffusion,solubility, and electrical properties of scandium and praseodymium in silicon

An integrated study of diffusion, solubility, and electrical properties of scandium and praseodymium in silicon annealed in various media and temperature ranges (1100–1280 °C) was performed for the first time. The tracer technique, autoradiography, measurements of isothermic capacity and current relaxation, conductivity, and the Hall effect were used for the investigations. The diffusion parameters, solubility, and an acceptor character of scandium and praseodymium impurities in silicon were determined. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 75–77, January, 2007.     

Neutron reflection from a helical system

Analytical expressions for neutron reflection and transmission by magnetic mirrors with helical magnetization are derived. Reflectance curves with and without neutron spin flip are presented. Resonant properties of helical systems are studied.     

Sound propagation in an unstable atmospheric layer

The equation of sound propagation in an unstable medium produced by the presence of supersaturated water vapor in it, which can appear in a hurricane area, is derived. This equation takes into account the effects of sound velocity dispersion, amplification, damping, and nonlinear effects. Some solutions to this equation are presented, illustrating the specific features of sound propagation in an unstable medium. Published in Akusticheskiĭ Zhurnal, 2007, Vol. 53, No. 3, pp. 477–480.     

Analysis of (π K<Superscript>+</Superscript>) and (K<Superscript>-</Superscript>, K<Superscript>+</Superscript>) hypernuclear production spectra in distorted-wave impulse approximation

We study the hyperon-nucleus potential with distorted-wave impulse wave approximation (DWIA) using the Green's function method. In order to include the nucleon and hyperon potential effects in Fermi averaging, we introduce the local optimal momentum approximation of target nucleons. We can describe the quasi-free Λ , Σ and Ξ production spectra in a better way than in the standard Fermi-averaged t -matrix treatments.