An approximation technique is developed for studying the deterministic spread of a simple epidemic which avoids a difficulty inherent in the diffusion approximation. Travelling wave solutions are found and calculated for various contact distributions. The solution developing from an isolated infective is also briefly discussed.

An M/G/1 service system with finite waiting room is studied. A customer is served by one server in two phases, during the first of which a place in the waiting room is occupied. Starting from a determinant expression for the Laplace-Stieltjes transform of the busy period given in [2] we obtain contour integral expressions for the transform and the expectation, thereby generalising a result by Cohen [1]. This is effected by developing the determinants along the first row.

A multi-dimensional generalisation of a well-known duality relation in random walk theory is given.

This note considers a finite dam fed by independently and identically distributed (i.i.d.) inputs, being either (i) of at least size β (> 0) or (ii) negative exponentially distributed, occurring in a Poisson process. The instantaneous release rate may be a function r(·) of the content; additional and numerical results are given for the special case where r(x) = µxα (0 ≦ α<∞, 0 < µ <∞) is proportional to the αth power of the content. The basic method used in [7] for the special case r(x) = µx for obtaining the distribution of the number of steps and of the time to first overflowing is shown to carry over almost completely in case (i), but only partially so in case (ii).

The paper considers some properties of the reversible counters system of Lampard [1]. Lampard considers the properties of the process imbedded at the epochs when the counter receiving pulses from the ‘down’ process reaches zero. We consider here the time-dependent and stationary distributions of the original process. Their derivation gives rise to some interesting functional equations, besides being useful for studying queues with Markov-dependent inter-arrival or service times.

This paper illustrates a simple method of deriving distributions for samples from cell populations in exponential growth. The distribution of the elapsed proportion of the DNA-synthetic phase of the cell cycle is derived and used to find the distribution of DNA content in a random sample of cells. Allowing for a normally-distributed measurement error, the resulting distribution agrees well with DNA distributions observed empirically. The statistical analysis of DNA distributions, and the interpretation of the distributional parameters in terms of cell population kinetics, are discussed and illustrated with an example.

Expressions for the mean and variance of the recurrence time of non-overlapping draft-patterns of draft from a Moran Reservoir Model (discrete-state and discrete-time Markov chain) are derived using Feller's Renewal argument. In addition an expression for the mean recurrence time for self-overlapping patterns of draft is derived using run-theory.

We investigate the nature of the set of emptiness times of a dam whose release rate depends on the content and whose cumulative input process is a pure-jump Lévy process. Detailed results are obtained for stable input processes and release functions of the form r(x) = xβ I(o,∞)(x).

A stochastic tessellation automaton (STA) is introduced and analysed as an analogue to a stochastic lattice process, called the Markov configuration process. The STA is considered as an (infinite regular) array with interconnected Moore-type automata, each of these representing a B-object interacting with its neighbours. The objective of the paper is to examine some consequences of the analogy between an STA and the Markov configuration process. In addition, the possibility of finding a suitable stochastic grammar arising from the study of this configuration model is briefly considered.

Consider two queues with k servers. Inequalities between their sample paths and thence between the distribution functions of their waiting times and queue sizes are deduced from inequalities between the conditional distribution functions, given previous interarrival and service times, for the two queues.