Time-ordered Sequence Research Articles

Disease associations in linked records: schizophrenia and accidental injury.

The investigation to be reported in this paper was undertaken following a query concerning the relationship between road accidents and the use of psychotropic drugs. One aspect of this problem could be studied easily by using the file of linked records of the Oxford Record Linkage Study (Acheson, 1967; Baldwin, 1973). Statistical methods have been developed to estimate the degree of association between conditions occurring in time-ordered sequences (Baldwin et al, 1978). The existing file of linked hospital discharge and death records in the Oxford Record Linkage Study was therefore searched and relevant material analysed to test the hypothesis that admission to hospital for schizophrenia was followed by an increased risk of accident or injury. (The present data do not allow the more specific question of phenothiazine treatment to be investigated). The statistical procedures simultaneously provide data on the converse situation, namely where injury occurs prior to hospital admission with schizophrenia, and this was studied also.

Designing Experiments When Run Order is Important

Whenever the observations in an experimrnt must be made in somr time order sequence, there is a substantial likelihood that there may bc somo time order dcpendency in the results. In addition, it is frequently cxprnsivr to change levels for one or more of the factors in thr study. In this paper these two facts are documcntcd with personal case histories and a general method is proposed for taking these difficulties into consideration when planning an expcrimrnt. The method introduces Monte Carlo like techniques into the design of cxperimcnts.

Chemistry in Lasers. I. The Role of the Stokes O-O Loss

Abstract In this first paper in a series aimed at studies of chemistry in lasers, the molecular states in a dye laser are compared to those in the same solution under ordinary fluorescence conditions. Significant differences are found to exist which are readily apparent in case of molecules whose normal fluorescence is characterized by a sizeable Stokes O-O loss. Such differences are traced to the invalidity of the Born-Oppenheimer separation approximation for these molecules when the excited state lifetimes are greatly altered as in dyes lasers at high photon density. Representation of this particular type of Stokes shift requires an extension of the usual model based on only two hypersurfaces, namely, a time-ordered sequence of quantum states.

Chemistry in Lasers. II. Contribution from Precursor States: A Comparison of the Time Evolution of Electronically Excited States Under Spontaneous and Stimulated Emission Conditions

Abstract The relative importance of the time-ordered sequence of precursor states is examined; their contribution to the ensemble is negligible for spontaneous emission, but under stimulated emission conditions at high photon density the dominant terms in the sequence, determining the ensemble properties, are different from the Franck-Condon relaxed state. The ‘chirp’ of a traveling wave laser is shown to be related to time-resolved spectroscopic measurements.