On subgroups and factor groups of GL(n, q) acting on spreads with the same characteristic

Let π^l_∞ be an affine translation plane of order q^r with GF(q) in its kern. Suppose G is a subgroup of the translation complement of π^l_∞ which leaves invariant a set Δ of q + 1 slopes and acts transitively on l_∞?Δ. We study the situation when G≌SL(n, q) or PSL(n, q).We show that if G|Δ = identity, then π^l_∞ is a Hall plane, a Lorimer-Rahilly plane (LR-16) or a Johnson-Walker plane (JW-16). Moreover, if n?3, then G fixes Δ elementwise and π^l_∞ is LR-16 or JW-16.     

Single and double ionization of gallium by electron impact

Electron impact single and double ionization cross sections of gallium have been calculated in the binary encounter approximation using accurate expression for σ_Δ;E including exchange and interference as given by Vriens and Hartree-Fock velocity distributions for the target electrons throughout the calculations. It is concluded that the ionization of 3d shell contributes partly to single ionization and partly to double ionization. The results so obtained show reasonably good agreement with the experimental data.     

Free-convection between vertical walls partially filled with porous medium

This paper presents an analytical study of laminar fully developed free-convection flow between two vertical walls partially filled with porous matrix and partially with a clear fluid having interface vertically. The momentum transfer in porous medium is described by the Brinkman-extended Darcy model and the two regions are coupled by equating the velocity and shear stress at the interface. The governing equations having non-linear nature have been solved by using perturbation method. It has been found that effect of Brinkman term is in entire porous domain for large values of Darcy number while its effect is confined nearer to interface and wall for small values of Darcy number. Received on 19 March 1997     

Diffraction of sound pulses by a rigid cylinder in an inhomogeneous medium

We consider the problem of scattering of two-dimensional sound pulses by a rigid circular cylinder embedded in a cylindrically stratified inhomogeneous medium. The line source is parallel to the axis of the cylinder. It is assumed that the velocity of soundc is given byc ^?1=pr ^q, wherep andq are real constants andp>0. The method of dual integral transformation developed by Friedlander is used. The solution in terms of pulse propagation modes gives the diffracted pulse and the method of steepest descents yields the geometrical acoustic field.     

Effect of supersaturation on the viscosity of solutions

Ohne Zusammenfassung     

Microscopic optical fields and mixing coefficients of x-ray and optical frequencies in solids

Simple approximation schemes are developed to calculate induced optical fields and local field corrections to the linear optical dielectric function in metals like aluminium and in insulators like germanium. In these calculations, the unperturbed electronic states in Ge are described within the framework of the bonding orbital approach, whereas the nearly-free-electron approximation is used for Al. As expected, explicit numerical calculations show that the contribution to secondary longitudinal induced fields is more appreciable in Ge. The second order susceptibility describing the non-linear mixing of an optical frequency with an x-ray frequency, which depends upon the magnitude of the microscopic induced optical charge density, is also calculated for these solids. For most relevant wavevectors of secondary optical fields, it is found to be of the order of 10^?12 esu in Ge and 10^?14 esu in Al.     

Force field validation for nucleic acid simulations: comparing energies and dynamics of a DNA dodecamer

Important questions exist regarding the quality of force fields used in molecular dynamics (MD) simulations and their interoperable use with other available MD implementations. NAMD is one of the most efficient and scalable parallel molecular dynamics codes for large-scale biomolecular simulations in the open source domain. It is the aim of this article to analyze and compare the dynamics of a benchmark DNA dodecamer d(CTTTTGCAAAAG)2 system, including its binding to a specific drug molecule arising from the use of various simulation protocols in NAMD using Amber98, with the dynamics arising from simulations of the same dodecamer using Amber98 in the AMBER package, one of the most well-established simulation codes for nucleic acids. Based upon a set of validation benchmarks, the details of which are discussed, we find that nucleic acid simulations using NAMD give meaningful results and that the essential features of the resulting dynamics are similar to those arising from the AMBER package. This sets the stage for reliable large-scale simulations of nucleic acids using NAMD.     

Polarographic study of mixed ligand complex stability constants and kinetic parameters of reduction of zinc(II)-tartrate—Thiocyanate system

The Zn-tartrate-thiocyanate system has been investigated polarographically and the composition and stability constants of mixed complexes formed have been determined.