A method of determining materials of lenses contained in an optical system of a projection exposure apparatus is described. The pitcher has a side wall extending from a floor to a rim. The inner conductor and upper contact are generally exposed to higher voltages than the outer conductor, and the upper contact is shorter than the outer conductor. By using an array of counters to collect data rather than averaging values over time, a more accurate indication of computer resource utilization is determined. The server splits the multimedia data for streaming via multiple multicast group addresses. The storage controller, which is coupled to a physical memory cache, allows the mapping of a virtual address from one of the volatile cache memories to a physical disk address directed to a storage location within the hard disk without transitioning through a real address.