Determination of stability constants using genetic algorithms

A genetic algorithm (GA)-simplex hybrid approach has been developed for the determination of stability constants using calorimetric and polarographic data obtained from literature sources. The GA determined both the most suitable equilibrium model for the systems studied and the values of the stability constants and the heats of formation for the calorimetric studies. As such, a variable length chromosome format was devised to represent the equilibrium models and stability constants (and heats of formation). The polarographic data were obtained from studies of cadmium chloride and lead with the crown ether dicyclohexyl-18-crown-6. The calorimetric data were obtained from a study of a two step addition reaction of Hg(CN)2 with thiourea. The stability constants obtained using the GA-simplex hybrid approach compare favourably with the values quoted in the literature

Rechtvaardigheid in alarmerende omstandigheden

In this paper, I propose an alarm-system model of the justice judgment process. Specifically, I argue that the process by which justice judgments are formed may be influenced reliably by the activation of psychological systems that people use to detect and handle alarming situations. Building on this analysis, I predict that if this line of reasoning is true then presenting (vs. not presenting) alarm-related stimuli to people should lead to more extreme judgments about subsequent justice-related events than not presenting these alarming stimuli. Findings from different studies are reviewed that support this prediction. In particular, the findings indicate that after the presentation of alarming stimuli, people are strongly influenced by fair (as opposed to unfair) events, suggesting that under alarming conditions people are in need for fair treatment. In closing, I discuss the implications the model may have for both scientists and practitioners interested in the justice judgment process

Origin of Lagrangian Intermittency in Drift-Wave Turbulence

The Lagrangian velocity statistics of dissipative drift-wave turbulence are investigated. For large values of the adiabaticity (or small collisionality), the probability density function of the Lagrangian acceleration shows exponential tails, as opposed to the stretched exponential or algebraic tails, generally observed for the highly intermittent acceleration of Navier-Stokes turbulence. This exponential distribution is shown to be a robust feature independent of the Reynolds number. For small adiabaticity, algebraic tails are observed, suggesting the strong influence of point-vortex-like dynamics on the acceleration. A causal connection is found between the shape of the probability density function and the autocorrelation of the norm of the acceleration

Rapid generation of angular momentum in bounded magnetized plasma

Direct numerical simulations of two-dimensional decaying MHD turbulence in bounded domains show the rapid generation of angular momentum in nonaxisymmetric geometries. It is found that magnetic fluctuations enhance this mechanism. On a larger time scale, the generation of a magnetic angular momentum, or angular field, is observed. For axisymmetric geometries, the generation of angular momentum is absent; nevertheless, a weak magnetic field can be observed. The derived evolution equations for both the angular momentum and angular field yield possible explanations for the observed behavior

Valence bond glass on an fcc lattice in the double perovskite Ba2YMoO6

Peer reviewedPublisher PD