The principal, as a key leadership person in the staff development program, must know how to facilitate staff development in the school, particularly in the areas of instruction, shared decision making and management of change. Most principals are not prepared for, nor do they understand their role in staff development for all school personnel. Effective staff development requires comprehensive training for principals in order to prepare them for leadership roles in the schools (Wood, 1980).
"Depolarization-dependent calcium influx is biphasic in synaptosomes (Nachshen and Blaustein, 1980, 1982). The fast and slow components of 45 Ca++ influx are proposed to occur through separate calcium channels. In this report the fast and slow components of depolarization-dependent 45Ca++ influx are resolved. The fast component is inactivated by predepolarization, inhibited by low concentrations of lanthanum and closely correlates with the rapid release of 3H-norepinephrine from synaptosomes. The properties of the fast component of influx suggest that it is mediated by calcium channels which inactivate during the first second of depolarization. The slow component is not sensitive of predepolarization and is partially dependent on the internal Na+ content of the synaptosomes. It is proposed that during depolarization a portion of the slow component of Ca++ influx in synaptosomes is mediated by a Na i/Cao exchange mechanism."
"The effects of various technical and economic parameters on LMFBR deployment plans have been studied to assess the best future mix of light water reactors and fast breeder reactors which will result in minimum cumulative nuclear generating costs discounted to the year 1985. Projected growth in domestic nuclear generating capacity was taken from various predictions [19, 20, 21], and the future domestic nuclear generating capacity was assumed to consist only of light water reactors and liquid metal cooled fast breeder reactors. Technical characteristics representing the two reactor types were taken as fixed, typical values for this study. The light water reactor characteristics represent a composite between PWRs and BWRs, whereas the most recent follow-on design was used as the reference for LMFBRs. Annual domestic power generation costs are calculated as a function of the installed capacity of both light water and fast breeder reactors in each particular year, the unit costs of each reactor type, the load factor, plutonium requirements, plutonium price and discount rate, and other factors. The cumulative nuclear generating costs are then computed as the sum of the discounted annual costs."
Recent advances in virtual-interface and computer technologies, including helmet-mounted displays (HMDs), three-dimensional auditory displays, haptic displays, head and eye position tracking devices, and computer-generated imaging techniques, have permitted the development of multi-sensory, interactive virtual environments. In spite of the dramatic ability of these environments to represent the perceptual world, they are limited by the problem of time delay---the delay between the input to a system and its corresponding output. For example, in the case of HMDs, time delays are present in the sampling of head position by a tracking device attached to the user's helmet and the appearance of the updated image in the HMD. Such delays cause the image to lag behind the user's head movement, thereby causing the image to be displayed in an incorrect position.