This paper provides a treatment of molecule-ion molecule reactions based on stochastic mechanics. Stochastic mechanics is a semi-classical theory in which one assumes that particles move as a stochastic diffusion process. It is shown that the reaction probability and reaction rate can be determined from the solution of certain Partial Differential Equations (PDE). Asymptotic solutions of these PDE are constructed in terms of incomplete special functions. The results derived using stochastic mechanics are compared with results derived using other semi-classical approximations.
A generalized critical point is characterized by totally non-linear dynamics. The deterministic and stochastic theory of relaxation is formulated at such a point. Canonical problems are used to motivate the general solutions. In the deterministic theory, it is shown that at the critical point certain modes have polynomial (rather than exponential) growth or decay. The stochastic relaxation rates can be calculated in terms of various incomplete special functions. First, a substrate inhibited reaction (marginal type dynamical system). Second, the relaxation of a mean field ferromagnet. Third, the relaxation of a critical harmonic oscillator is considered.
In this paper, the following type of harvesting problem is considered. An animal population is divided into two stocks: an 'underlying' population and a 'surface' population. It is assumed that there is a natural exchange between the two population levels. The predator or harvestor affects only the 'surface' population and does not influence the 'underlying' population directly. Such a situation occurs, for example, in the off-shore Eastern Tropical Tuna Fishery. In this case, tuna associate with porpoise schools. The fishery harvests only those tuna associated with porpoise. Consequently, the underlying population of tuna is not sampled by the fishery. One may wonder what information measurements on the surface, harvested population provides about the unobservable underlying population. Furthermore, it is interesting and important to know if the standard, linear relationship between harvest and effort is valid in an aggregating population.