Estimating a Markov Transition Matrix from Observational Data

Markov chains are frequently used in Operational Research to describe how a system changes over time, its behaviour being governed by its transition matrix. This paper describes a technique for finding a maximum likelihood estimate for such a transition matrix when a system is observed at infrequent time intervals. The technique is called the EM Algorithm which, for this kind of problem, has distinct advantages over other methods of optimization.     

Finite hereditary near-field groups

A group (G,·) is said to be a near-field group ifG is the multiplicative group of a near-field. A near-field groupG is called hereditary if every subgroup ofG is a near-field group. This paper presents a complete characterization of finite hereditary near-field groups.     

The deposition of energy from reactions of laser excited atoms: Strontium 3P1 with hydrogen halides

The chemical reactions of laser excited Sr^*(³P₁) with HF and HCl are studied in a beam gas arrangement with LlF detection. This is the first experiment reported where both the specific electronic state of the reactant is laser prepared and the specific vibrational states of the products are laser detected. The results show that a large fraction of the available energy is released into vibration of SrX.