The transverse magnetic reflectivity minimum of metals.

Metal surfaces, which are generally regarded as excellent reflectors of electromagnetic radiation, may, at high angles of incidence, become strong absorbers for transverse magnetic radiation. This effect, often referred to as the pseudo-Brewster angle, results in a reflectivity minimum, and is most strongly evident in the microwave domain, where metals are often treated as perfect conductors. A detailed analysis of this reflectivity minimum is presented here and it is shown why, in the limit of very long wavelengths, metals close to grazing incidence have a minimum in reflectance given by (square root 2-1)2.

Master-equation approach to the study of phase-change processes in data storage media.

We study the dynamics of crystallization in phase-change materials using a master-equation approach in which the state of the crystallizing material is described by a cluster size distribution function. A model is developed using the thermodynamics of the processes involved and representing the clusters of size two and greater as a continuum but clusters of size one (monomers) as a separate equation. We present some partial analytical results for the isothermal case and for large cluster sizes, but principally we use numerical simulations to investigate the model. We obtain results that are in good agreement with experimental data and the model appears to be useful for the fast simulation of reading and writing processes in phase-change optical and electrical memories.

Oxygen diffusion in tissue preparations with Michaelis-Menten kinetics.

A model is introduced for the oxygen consumption in thin vital tissue preparation. The steady uptake kinetics is modelled by a Michaelis-Menten form and for this case it proved that the resulting boundary value problem admits a unique solution for those parameter ranges typical of related physiological experiments. This solution is compared with Otto Warburg's hyperoxia model and with a hypoxia model. Useful and easily computed approximations are derived for the minimum oxygen supply across the tissue and some numerical solutions of the governing equations are discussed.