Inelastic X-ray scattering study of the collective dynamics in liquid sodium

Inelastic X-ray scattering data have been collected for liquid sodium at T=390 K, i.e. slightly above the melting point. Owing to the very high instrumental resolution, pushed up to 1.5 meV, it has been possible to determine accurately the dynamic structure factor, $S(Q,\omega)$, in a wide wavevector range, $1.5 \div 15$ nm$^{-1}$, and to investigate on the dynamical processes underlying the collective dynamics. A detailed analysis of the lineshape of $S(Q,\omega)$, similarly to other liquid metals, reveals the co-existence of two different relaxation processes with slow and fast characteristic timescales respectively. The present data lead to the conclusion that: i) the picture of the relaxation mechanism based on a simple viscoelastic model fails; ii) although the comparison with other liquid metals reveals similar behavior, the data do not exhibit an exact scaling law as the principle of corresponding state would predict.Comment: RevTex, 7 pages, 6 eps figures. Accepted by Phys. Rev.

Assessing the contribution of R&D to total factor productivity—a Bayesian approach to account for heterogeneity and heteroskedasticity

R&D, Productivity, Heteroskedasticity, Hierarchical Bayes, Markov Chain Monte Carlo simulations, Panel data, Random coefficient model,

On the Relative Strengths of Altruism and Fairness

Some researchers have attributed deviations from selfish behavior to fairness. Violations of fairness theories, however, are observed in experimental dictator games with transfer rates greater than 1 (a transfer of x from the dictator yields an income of tx for the beneficiary, where x > tx): the dictator’s final income is less than the beneficiary’s. We theoretically propose that dictator giving also involves altruism, further supporting our claim with empirical evidence from four separate samples of dictator game experiments. Our nonlinear specification allows the relative measurement of the independent motives in dictator behavior. Copyright Springer 2006altruism, fairness, dictator game, transfer rate, social welfare,

Cytogenetics of B-Chromosomes

SUMMARYThe author intends to give this as a contribution in the discussion relating to a non-homogeneous group of chromosomes, variously known as accessory, B, extra or supernumerary. The term B-chromosome is considered the most appropriate. Moreover, the author discusses the terminology, the presence of B-chromosomes in animals and plants, and their principal cytogenetic characteristics