Luminescence and nonradiative relaxation of Pb2+, Sn2+, Sb3+, and Bi3+ in oxide glasses

Absorption and fluorescence spectra of Sn²⁺ and Sb³⁺ in borax, phosphate, and germanate glasses were measured in the temperature range 87–295°K. Fluorescence decay times of these ions in borax glass at 87°K was a single exponent with τ ≈ 6–11 μsec. At 293°K, two decay times were resolved in the range of 50–2000 nsec. The nonexponential behavior is interpreted by the repopulation of the ³P₁ level from the ³P₀ level. The temperature dependence of fluorescence and the low values of quantum efficiencies of fluorescence are explained by means of the configurational coordinate diagram model.     

Comments on “The matrix sign function and computations in systems” by E. D. Denman and A. N. Beavers

The suggested method of Denman and Beavers for solving a Lyapunov matrix equation is shown to fail when the solution is not unique. It is also shown that sgnA can be used to determine the inertia of A.     

Implications of a light Higgs scalar

Phenomenological consequences of a light neutral Higgs scalar S (mass < 3.7 GeV) are explored in various two-Higgs-doublet models where some of the couplings are strongly enhanced. In one class of models the two-gluon decay mode is predominant, and decays into two muons are quite suppressed. A detailed analysis of the decay b → s + S is given. The consequences a light scalar for supersymmetric models are discussed.     

Crystallographic characterisation of binary alkali metal alkoxide-magnesium bis(alkyl) mixtures: differential binding of Na+ and K+ to a common dinuclear diorganomagnesiate

Relevant to mixtures studied in solution and utilised in styrene polymerisation but hitherto not characterised in the solid, two crystal structures of alkali metal alkoxide-magnesium bis(alkyl) co-complexes have been determined, revealing that in binding to the C2O tripodal face of a common organomagnesiate anion, Na+ prefers O-coordination, whereas K+ prefers C-coordination.     

A heuristic for direct consumer participation in primary health care planning

Recent attempts at consumer participation in the health care planning process have proved weak in their ability to responsively account for consumer health welfare. This can be attributed, in large part, to the mechanisms employed for identifying and utilizing the consumer's health care views and preferences. A heuristic planning procedure designed to overcome these problems by directly incorporating consumer preferences is developed. It identifies that (primary) health care delivery system which maximizes total incremental health benefit to a community subject to a prespecified budget constraint. The model assumes a methodology (previously developed by the author) for measuring, in aggregable units, the benefit, B_ip, from some health care facility p as perceived by some consumer i. Application of the procedure and subsequent sensitivity analyses demonstrate its ability to generate valid solutions that are robust to disturbances in the planning system.     

SEMICONDUCTION AND PHOTOCONDUCTION ACTIVATION ENERGIES OF THE RETINALS

Abstract -The semiconduction and photoconduction currents through 1-ml thick sandwich cells of all-trans-, 13- cis- , 11- cis -retinal-, and 13- cis -retinal-m-nitroaniline-hydrogen chloride were measured as a function of the temperature in both the crystalline and melted states. From the slopes of graphs of the log of the current against 1000/TGK, the activation energies for semiconduction and photoconduction were calculated using the conductivity equations for the band model. The results of the average semiconduction activation energy measurements fell into two categories: The first group has activation energies between 1.9 and 2.4 eV and includes crystalline all- trans- , 13- cis -,9 cis -retinal, and both crystalline and melted 13- cis -retinal- m -nitroanaline hydrogen chloride; the second group has activation energies between 3.1 and 3.6 eV and includes crystalline 11- cis -retinal samples shorted. The average photoconduction activation energy for crysalline 13- cis - and 11- cis -retinal, being 0.25 and 0.24 eV respectively, were essentially identical within experimental error, whereas the same parameter for 13- cis -retinal- m -nitroaniline hydrogen chloride was considerably lower at 0.15 eV. All- trans -retinal was not measurably photoconductive and 9- cis -retinal was only slightly photoconductive.     

The use of a minicomputer for data collection and treatment in the study of electrochemical surface processes

Procedures for on-line acquisition and processing of data from controlled-potential (linear potential sweep and cyclic voltammetric) experiments on electrode surface processes by means of a PDP 11/34 minicomputer are described. Advantages of this procedure over regular recording of current—potential or current —time traces on an oscilloscope are discussed.     

Problems of control and information theory (Hungary)

The bezoutian matrix, which provides information concerning co-primeness and greatest common divisor of polynomials, has recently been generalized by Heinig to the case of square polynomial matrices. Some of the properties of the bezoutian for the scalar case then carry over directly. In particular, the central result of the paper is an extension of a factorization due to Barnett, which enables the bezoutian to be expressed in terms of a Kronecker matrix polynomial in an appropriate block companion matrix. The most important consequence of this result is a determination of the structure of the kernel of the bezoutian. Thus, the bezoutian is nonsingular if and only if the two polynomial matrices have no common eigenvalues (i.e., their determinants are relatively prime); otherwise, the dimension of the kernel is given in terms of the multiplicities of the common eigenvalues of the polynomial matrices. Finally, an explicit basis is developed for the kernel of the bezoutian, using the concept of Jordan chains.     

Linear law for the logarithms of the Riemann periods at simple critical zeta zeros

Each simple zero of the Riemann zeta function on the critical line with is a center for the flow of the Riemann xi function with an associated period . It is shown that, as ,

Numerical evaluation leads to the conjecture that this inequality can be replaced by an equality. Assuming the Riemann Hypothesis and a zeta zero separation conjecture for some exponent , we obtain the upper bound . Assuming a weakened form of a conjecture of Gonek, giving a bound for the reciprocal of the derivative of zeta at each zero, we obtain the expected upper bound for the periods so, conditionally, . Indeed, this linear relationship is equivalent to the given weakened conjecture, which implies the zero separation conjecture, provided the exponent is sufficiently large. The frequencies corresponding to the periods relate to natural eigenvalues for the Hilbert-Polya conjecture. They may provide a goal for those seeking a self-adjoint operator related to the Riemann hypothesis.

     

Observation of Bs(0)-Bs(0) oscillations

We report the observation of Bs(0)-Bs(0) oscillations from a time-dependent measurement of the Bs(0)-Bs(0) oscillation frequency Deltams. Using a data sample of 1 fb(-1) of pp collisions at square root of s=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron, we find signals of 5600 fully reconstructed hadronic Bs decays, 3100 partially reconstructed hadronic Bs decays, and 61,500 partially reconstructed semileptonic Bs decays. We measure the probability as a function of proper decay time that the Bs decays with the same, or opposite, flavor as the flavor at production, and we find a signal for Bs(0)-Bs(0) oscillations. The probability that random fluctuations could produce a comparable signal is 8 x 10(-8), which exceeds 5sigma significance. We measure Deltams=17.77 +/- 0.10(stat) +/- 0.07(syst) ps(-1) and extract /V(td)/V(ts)/=0.2060+/-0.0007(Deltams)(-0.0060)(+0.008)(Deltamd+theor).