Forbidden M1 and E2 transitions in monovalent atoms and ions

We carried out a systematic high-precision relativistic study of the forbidden magnetic-dipole and electric-quadrupole transitions in Ca+, Rb, Sr+, Cs, Ba+, Fr, Ra+, Ac2+, and Th3+. This work is motivated by the importance of these transitions for tests of fundamental physics and precision measurements. The relative importance of the relativistic, correlation, Breit correction, and contributions of negative-energy states is investigated. Recommended values of reduced matrix elements are presented together with their uncertainties. The matrix elements and resulting lifetimes are compared with other theoretical values and with experiment where available.Comment: 9 pages, 6 table

Biological patterns: Novel indicators for pharmacological assays

Variable gravity testing using the KC-135 demonstrated clearly that biological pattern formation was definitely shown to result from gravity alone, and not from oxygen gradients in solution. Motile pattern formation of spermatozoa are driven by alternate mechanisms, and apparently not affected by short-term changes in gravity. The chemical effects found appear to be secondary to the primary effect of gravity. Cryopreservation may be the remedy to the problem of 'spare' or 'standing order' biological samples for testing of space lab investigations, but further studies are necessary

Small-angle x-ray-scattering study of phase separation and crystallization in the bulk amorphous Mg62Cu25Y10Li3 alloy

We report on a small-angle x-ray-scattering (SAXS) and differential scanning calorimetry study of phase separation and crystallization in rapidly quenched amorphous Mg62Cu25Y10Li3 alloy samples. Differential scanning calorimetry demonstrates the occurrence of crystallization and grain growth upon isothermal annealing of these samples at 135 °C. The SAXS studies show the presence of large inhomogeneities even in the rapidly quenched as-prepared Mg62Cu25Y10Li3 alloy that is attributed to phase separation in the undercooled liquid during the cooling process. After isothermal annealing at 135 °C for longer than 30 min the samples exhibit a strong SAXS intensity that monotonically increases with increasing annealing time. During heat treatment, crystallization and growth of a nanocrystalline bcc-Mg7Li3 phase occurs in the Y-poor and MgLi-rich domains. The initially rough boundaries of the nanocrystals become sharper with increasing annealing time. Anomalous small-angle x-ray-scattering investigations near the Cu K edge indicate that while Cu is distributed homogeneously in the as-prepared sample, a Cu composition gradient develops between the matrix and the bcc-Mg7Li3 nanocrystals in the annealed sample

Excitation energies, polarizabilities, multipole transition rates, and lifetimes in Th IV

Excitation energies of the ns_{1/2} (n=7-10), np_j (n=7-9), nd_j (n=6-8), nf_{j} (n=5-7), and ng_{j} (n=5-6) states in Th IV are evaluated. First-, second-, third-, and all-order Coulomb energies and first- and second-order Coulomb-Breit energies are calculated. Reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for the 96 possible nl_j-n'l'_j' electric-dipole transitions. Multipole matrix elements (7s_{1/2}-6d_j, 7s_{1/2}-5f_j, and 5f_{5/2}-5f_{7/2}) are evaluated to obtain the lifetimes of the $5f_{7/2}$ and 7s_{1/2}$ states. Matrix elements are calculated using both relativistic many-body perturbation theory, complete through third order, and a relativistic all-order method restricted to single and double (SD) excitations. Scalar and tensor polarizabilities for the 5f_{5/2} ground state in Th3+ are calculated using relativistic third-order and all-order methods. These calculations provide a theoretical benchmark for comparison with experiment and theory.Comment: 9 pages, 9 figure

Factors Limiting Cell Penetration in Manufacturing Plants

Despite the potential advantages of cellular manufacturing, most plants with cells have only partially converted their systems. This study examines factors that limit cell penetration within plants using a mail survey of cell users. The existence of service processes, lack of a strong champion who would push the design and implementation of more cells, and low cost of tracking non-cell parts/ products on the plant floor were found to be significant predictors of cell penetration for plants with cells and no plans for further cells. Factors limiting penetration in plants planning to implement further cells could not be determined

Excitation energies, polarizabilities, multipole transition rates, and lifetimes of ions along the francium isoelectronic sequence

Relativistic many-body perturbation theory is applied to study properties of ions of the francium isoelectronic sequence. Specifically, energies of the 7s, 7p, 6d, and 5f states of Fr-like ions with nuclear charges Z = 87 - 100 are calculated through third order; reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for 7s - 7p, 7p - 6d, and 6d - 5f electric-dipole transitions; and 7s - 6d, 7s - 5f, and 5f_5/2 - 5f_7/2 multipole matrix elements are evaluated to obtain the lifetimes of low-lying excited states. Moreover, for the ions Z = 87 - 92 calculations are also carried out using the relativistic all-order single-double method, in which single and double excitations of Dirac-Fock wave functions are included to all orders in perturbation theory. With the aid of the SD wave functions, we obtain accurate values of energies, transition rates, oscillator strengths, and the lifetimes of these six ions. Ground state scalar polarizabilities in Fr I, Ra II, Ac III, and Th IV are calculated using relativistic third-order and all-order methods. Ground state scalar polarizabilities for other Fr-like ions are calculated using a relativistic second-order method. These calculations provide a theoretical benchmark for comparison with experiment and theory.Comment: 13 figures, 11 table

Excitation energies, hyperfine constants, E1, E2, M1 transition rates, and lifetimes of (6s2)nl states in Tl I and Pb II

Energies of np (n=6-9), ns (n=7-9), nd (n=6-8), and nf (n=5-6) states in Tl I and Pb II are obtained using relativistic many-body perturbation theory. Reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for the 72 possible electric-dipole transitions. Electric-quadrupole and magnetic-dipole matrix elements are evaluated to obtain np(3/2) - mp(1/2) (n,m=6,7) transition rates. Hyperfine constants A are evaluated for a number of states in 205Tl. First-, second-, third-, and all-order corrections to the energies and matrix elements and first- and second-order Breit corrections to energies are calculated. In our implementation of the all-order method, single and double excitations of Dirac-Fock wave functions are included to all orders in perturbation theory. These calculations provide a theoretical benchmark for comparison with experiment and theory.Comment: twelve tables, no figure

Relativistic many-body calculation of energies, lifetimes, polarizabilities, blackbody radiative shift and hyperfine constants in Lu2+

Energy levels of 30 low-lying states of Lu2+ and allowed electric-dipole matrix elements between these states are evaluated using a relativistic all-order method in which all single, double and partial triple excitations of Dirac-Fock wave functions are included to all orders of perturbation theory. Matrix elements are critically evaluated for their accuracy and recommended values of the matrix elements are given together with uncertainty estimates. Line strengths, transition rates and lifetimes of the metastable 5d(3/2) and 5d(5/2) states are calculated. Recommended values are given for static polarizabilities of the 6s, 5d and 6p states and tensor polarizabilities of the 5d and 6p(3/2) states. Uncertainties of the polarizability values are estimated in all cases. The blackbody radiation shift of the 6s(1/2)-5d(5/2) transition frequency of the Lu2+ ion is calculated with the aid of the recommended scalar polarizabilities of the 6s(1/2) and 5d(5/2) states. Finally, A and B hyperfine constants are determined for states of 175Lu2+ with n <= 9. This work provides recommended values of transition matrix elements, polarizabilities and hyperfine constants of Lu2+, critically evaluated for accuracy, for benchmark tests of high-precision theoretical methodology and planning of future experiments.Comment: 9 pages, 10 table

Investigation of stratiform sulphide mineralisation at Meall Mor, South Knapdale, Argyll

A co-ordinated geochemical-geophysical-geological investigation of copper mineralisation in the Meal1 ?46r area, South Knapdale, Argyll was carried 0th in 1976 and followed by a drilling programme of 3 shallow holes in early 1977. The mineralisation occursin a zone of weak stratiform sulphide mineralisation (the pyrite zone) with a strike length of 1Okm in the Upper &ins Quartz&e of the Middle Dalradian. The geochemical drainage survey showed the existence of a strongly anomalous distribution of Cu and Sb in the Abhainn Srathain draining south from . Meal1 M&- and detailed soil sampling over the pyrite zone outlined a broad area enriched in copper. Deeper soil sampling confirmed the anomalously high copper values and a coincident IP anomaly was found stretching from Meal1 M& south to the old mine workings on Abhainn Srathain, and is probably caused by a local enrichment of pyrite and chalcopyrite within the pyrite zone. Three boreholes were drilled; two on coincident geochemical and geophysical anomalies, and the third beneath the old mines at Abhainn Srathain. Copper values in the first two holes range up to 0.24% Cu over 4.27m, but up to 1.06% Cu over 2.67m in the third and this enrichment may be related to a later remobilisation of the disseminated chalcopyrite. The results of subsequent drilling at two other sites are given in Appendix III