The object of this study was to develop a model that could be used to find the cost of operation of sections and subjects within Virginia Community Colleges. The model provides a graphic analysis of these costs and derived income as enrollment is varied in a class section. The model is based on certain assumptions that allow for simplification of the allocation of expenditures from the annual operating budget of the college. Since the teacher's salary is such a large percentage of the total cost, the allocation of all other operating costs to overhead introduces a relatively small error in the results. These overhead charges are distributed equally to all students on a credit hour basis. From a comparison of an in-depth study of the actual costs at one college and costs determined by the model formulas, it was established that an error of less than five percent was produced. To calculate costs a computer program was developed. The output is in the form of three curves; first, cost per student; second, total cost; and third, total income. All curves were plotted versus the enrollment in a section or sections of a subject. The computer also provides a printout of the same data in tabular form so information for any particular enrollment may be obtained. To determine the practicality of such a model, data were gathered from five community colleges in the Virginia system. The subjects were selected to include lecture, lecture-laboratory and shop classes, and to provide samples from various divisions of each college. Results were tabulated in various ways to demonstrate the types of information available and the utilization of such a model. If historical data are employed in the model, its output can be used to review operating costs. If estimated data are used, the model becomes a predictive tool for an administrator. / Ed. D.

Radon is a colourless, odourless, inert, radioactive gas found in Group 8 of the Periodic Table; it is formed by the decay of uranium in soils and rocks. The half-life of radon is 3.8 days. Radon, in the built environment, is the second largest cause of lung cancer after cigarette smoking and is responsible for 3-5% of the UK cancer deaths. Radon can accumulate in workplaces to levels (400 Bq.m3), above which action is required under UK legislation by employers to remediate so as to reduce levels and lower the risk to human health. The remediation and post-remediation research programme in the NI-IS properties in Northamptonshire is perhaps the most mature in the UK, commencing in 1993. This thesis includes a review of the main remediation projects in National Health Service (NHS) properties in Northamptonshire. Data has been obtained from a range of sources, post-remediation, to enable a cost-effectiveness assessment. Using direct radon measurements and questionnaires, to determine occupancy, dose reduction has been calculated for all members of staff in the remediated venues. The reduction in dose is lower than the reduction in radon. The trends in radon levels post-remediation have been investigated night-time levels are reduced more than daytime levels and this has a clear implication for dose to staff The effective lifetime of the remediation systems has been investigated. Remediation systems, operated through a clear management system, have been found to remain effective up to eight years after installation. A Decision Support System to support radon management in the workplace is proposed as well as suggestions for future research

The essential findings of this study are that, from a known radium source, radon variability in the environment of the buildings studied is an inevitable consequence of the variability of the prevailing surface boundary layer atmospheric conditions. These influences will be modified by the structural characteristics of the building and will vary directly, relative to the mechanically created variation of the atmospheric conditions inside the building. From the findings, a general hypothesis is postulated. It is probable, that the diurnal variation of radon results from the diurnal variation in ambient water vapour pressure. And that the seasonal variation in radon, arises from the changes in the range of this diurnal variation during the course of a year brought about by changing levels of temperature and barometric pressure. This will be varied to the extent, that wind pressure affects directly both the radon path from source to the building and the level of water vapour pressure. Where mechanically induced air-movement in the building creates overriding pressure and air exchange, then this is likely to determine the pattern of variability; and as a result can be used under some circumstances as a mitigation agent; with levels of concentration anticipated in a predictable way. The current practice of reliance on average radon values derived from time-average radon values of a living room and a bedroom, as being representative of the alpha particle dose delivered to an individual, may well significantly overstate the dose actually delivered to that individual at a particular radon level measured. This would follow potentially from a preponderance of radon transported overnight requiring a lower weighting factor for the amount delivered to above-ground-floor sleepers, and the much reduced level of intake to the respiratory system from reduced breathing rate during the sleep mode. Potentially also, from the mechanism postulated which implies the limitation of the impact of alpha particles, related to an association between water vapour pressure, radon and particulates in the atmosphere. Linkage between elevated radon levels and surface geological was identified; but no positive connection was apparent linking respiratory system cancers relative to radon/geology

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