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Caste determination in social insects with morphologically distinct castes occurs during a critical period during the larval stage. In contrast, in social insects without morphologically distinct castes the time of eclosion can act as an additional critical period. A number of cues have been identified that influence caste differentiation in social insects but to date, most of the studies have used physiological correlates to determine the effects of these cues on caste determination. Few studies have measured behavioral differences in a natural setting. In this field study, the behavioral and nutritional profiles of individuals of the paper wasp Polistes metricus emerging on nests with and without larvae were determined and compared to emerging workers and gynes from unmanipulated colonies. Based on previous studies, it was predicted that individuals eclosing on nests with larvae would have similar profiles to workers and those eclosing on nests without larvae would have similar profiles to gynes. Individuals that emerged on colonies with larvae had similar behavioral and nutritional profiles to workers as expected. Individuals that emerged on nests without larvae had behavioral and nutritional profiles that were in between workers and gynes and showed signs of active reproduction and nest construction. The results of this study were combined with those of other studies into a model that proposes that there are three thresholds, one in response to photoperiod, one during the larval stage, and one during eclosion that determines if individuals will be workers, active reproducers, or overwintering gynes. This model provides a more complete picture of caste determination in Polistes. [ABSTRACT FROM AUTHOR]

Most acute-care hospitals in the United States own at least one computed tomography scanner. Service contracts offered by scanner manufacturers cost approximately 10% of the equipment's purchase price. Equivalent service support can be provided at a lower cost to scanner owners by a CT scanner service group, in which a program director and a senior biomedical equipment technician in a central office oversee purchase of replacement parts and supervise and train biomedical equipment technicians assigned to each participating hospital. The service group saves money by purchasing replacement parts in quantity from a less expensive source than the CT manufacturer, and by employing a technician at each hospital rather than having one BMET travel between several hospitals. Scanner downtime is significantly reduced because the staff technician is available immediately in the event of equipment failure and routine preventive maintenance tasks can be performed after business hours. By encouraging communication and cooperation the service group enables the technicians to keep abreast of the latest technology.

A fully developed in-house clinical engineering program has much to offer to a large community hospital. In the southeast U.S., many community hospitals-600 beds or fewer-have implemented partial programs and, as a result, have received only a partial return on their investment. A comprehensive program extends maintenance support to all patient-care devices, is intimately involved in the new device specification, evaluation, and selection process with the medical staff-standardizing whenever appropriate- and significantly involved in the continuing education program for in-house users of devices.