Several problems have been investigated relating to photon migration in a turbid medium. These were suggested by diagnostic applications of laser technology. The research is aimed at finding a way to incorporate anisotropic scattering effects into transport theory that are not computationally intensive, and therefore both easy to implement and able to provide physical insight. An earlier-published theory of anisotropic scattering in an infinite medium in discrete time has been extended to the continuous time domain. Further work, both theoretical and by simulation, has been carried out on utilizing the telegrapher's equation for this purpose, but this has so far proved to be more difficult than anticipated due to problems in framing appropriate boundary conditions. An approximation scheme has been developed for including the effects of pairwise distance constraints between different amino acids in a protein. This is presently being applied to evaluating the accuracy of structures determined from multidimensional NMR experiments. A next step is that of constructing an R factor for NMR, analogous to that used in crystallography. Seemingly anomalous properties of water such as an increase in diffusion constant with increasing pressure have been analyzed both theoretically and by performing molecular dynamics simulations of a lattice model of a physical system. Thermodynamic arguments have been adduced to show that one need not postulate critical behavior in order to explain anomalous properties. A study has been completed with A.M. Berezhkovskii and A. Szabo on models of chemical reaction rates that generalize the commonly-used Smoluchowski model by taking many-body effects into account as well as allowing for the motion of all species of molecules taking part in the reaction. A model of virus capping has been developed together with J. Spouge and A. Szabo. Aspects of the kinetic properties of the model are presently being investigated.
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