Relativistic many-body calculations of electric-dipole matrix elements, lifetimes and polarizabilities in rubidium

Electric-dipole matrix elements for ns-n'p, nd-n'p, and 6d-4f transitions in Rb are calculated using a relativistic all-order method. A third-order calculation is also carried out for these matrix elements to evaluate the importance of the high-order many-body perturbation theory contributions. The all-order matrix elements are used to evaluate lifetimes of ns and np levels with n=6, 7, 8 and nd levels with n=4, 5, 6 for comparison with experiment and to provide benchmark values for these lifetimes. The dynamic polarizabilities are calculated for ns states of rubidium. The resulting lifetime and polarizability values are compared with available theory and experiment.Comment: 8 pages, 2 figure

Photolysis of Nitrous Oxide Isotopomers studied by Time-dependent Hermite Propagation

Nitrous oxide (

Louse (Insecta : Phthiraptera) mitochondrial 12S rRNA secondary structure is highly variable

Lice are ectoparasitic insects hosted by birds and mammals. Mitochondrial 12S rRNA sequences obtained from lice show considerable length variation and are very difficult to align. We show that the louse 12S rRNA domain III secondary structure displays considerable variation compared to other insects, in both the shape and number of stems and loops. Phylogenetic trees constructed from tree edit distances between louse 12S rRNA structures do not closely resemble trees constructed from sequence data, suggesting that at least some of this structural variation has arisen independently in different louse lineages. Taken together with previous work on mitochondrial gene order and elevated rates of substitution in louse mitochondrial sequences, the structural variation in louse 12S rRNA confirms the highly distinctive nature of molecular evolution in these insects

5\u27-Nucleotidase and Thrombin-Like Activities of Selected Crotalid Venoms

Thrombin-like activities were not observed inCrotalus basiliscus, C. molossus and C. scutulatus scutulatus crude venoms. 5\u27-Nucleotidase specific activities of 0.863, 0.273 and 5.520 units/mg of crude venom protein were observed inC. basiliscus, C. molossus and C. s. scutulatus venoms, respectively. Concanavalin ASepharose 4 B (Con A)affinitychromatography yielded two fractions from each of the crude venoms. Ineach instance, both fractions exhibited 5\u27-nucleotidase activities and the Con A-binding proteins had higher activities than the Con A-nonbinding proteins. 5\u27-Nucleotidase activities inthe DEAESephadex A-50 chromatographic fractions were localized in the first elution fraction and the last fraction(s) to elute. EDTAhad no effect on the 5\u27-nucleotidase activities ofthe crude venoms

5\u27-Nucleotidase and Thrombin-Like Activities of Selected Crotalid Venoms

Thrombin-like activities were not observed inCrotalus basiliscus, C. molossus and C. scutulatus scutulatus crude venoms. 5\u27-Nucleotidase specific activities of 0.863, 0.273 and 5.520 units/mg of crude venom protein were observed inC. basiliscus, C. molossus and C. s. scutulatus venoms, respectively. Concanavalin ASepharose 4 B (Con A)affinitychromatography yielded two fractions from each of the crude venoms. Ineach instance, both fractions exhibited 5\u27-nucleotidase activities and the Con A-binding proteins had higher activities than the Con A-nonbinding proteins. 5\u27-Nucleotidase activities inthe DEAESephadex A-50 chromatographic fractions were localized in the first elution fraction and the last fraction(s) to elute. EDTAhad no effect on the 5\u27-nucleotidase activities ofthe crude venoms

Approximately Vanishing of Topological Cohomology Groups

In this paper, we establish the Pexiderized stability of coboundaries and cocycles and use them to investigate the Hyers--Ulam stability of some functional equations. We prove that for each Banach algebra $A$, Banach $A$-bimodule $X$ and positive integer $n, H^n(A,X)=0$ if and only if the $n$-th cohomology group approximately vanishes.Comment: 18 pages, minor correction

Electric-dipole, electric-quadrupole, magnetic-dipole, and magnetic-quadrupole transitions in the neon isoelectronic sequence

Excitation energies for 2l-3l′ hole-particle states of Ne-like ions are determined to second order in relativistic many-body perturbation theory (MBPT). Reduced matrix elements, line strengths, and transition rates are calculated for electric-dipole (E1), magnetic-quadrupole (E2), magnetic-dipole (M1), and magnetic-quadrupole (M2) transitions in Ne-like ions with nuclear charges ranging from Z=11 to 100. The calculations start from a 1s22s22p6 closed-shell Dirac-Fock potential and include second-order Coulomb and Breit-Coulomb interactions. First-order many-body perturbation theory (MBPT) is used to obtain intermediate-coupling coefficients, and second-order MBPT is used to determine the matrix elements. Contributions from negative-energy states are included in the second-order E1, M1, E2, and M2 matrix elements. The resulting transition energies are compared with experimental values and with results from other recent calculations. Trends of E1, E2, M1, and M2 transition rates as functions of nuclear charge Z are shown graphically for all transitions to the ground state

Relativistic many-body calculations of energies of n=3 states in aluminumlike ions

Energies of 3l3l′3l″ states of aluminumlike ions with Z=14?100 are evaluated to second order in relativistic many-body perturbation theory starting from a 1s22s22p6 Dirac-Fock potential. Intrinsic three-particle contributions to the energy are included in the present calculation and found to contribute about 10?20 % of the total second-order energy. Corrections for the frequency-dependent Breit interaction and the Lamb shift are included in lowest order. A detailed discussion of contributions to the energy levels is given for aluminumlike germanium (Z=32). Comparisons are made with available experimental data. We obtain excellent agreement for term splitting, even for low-Z ions. These calculations are presented as a theoretical benchmark for comparison with experiment and theory

Scattering of elastic waves by periodic arrays of spherical bodies

We develop a formalism for the calculation of the frequency band structure of a phononic crystal consisting of non-overlapping elastic spheres, characterized by Lam\'e coefficients which may be complex and frequency dependent, arranged periodically in a host medium with different mass density and Lam\'e coefficients. We view the crystal as a sequence of planes of spheres, parallel to and having the two dimensional periodicity of a given crystallographic plane, and obtain the complex band structure of the infinite crystal associated with this plane. The method allows one to calculate, also, the transmission, reflection, and absorption coefficients for an elastic wave (longitudinal or transverse) incident, at any angle, on a slab of the crystal of finite thickness. We demonstrate the efficiency of the method by applying it to a specific example.Comment: 19 pages, 5 figures, Phys. Rev. B (in press