An optical amplifier comprises an active fiber, a pump unit spaced from the active fiber and adapted to give a nominal, continuous pump power in an operational state, and a pump fiber adapted to transfer optical pump power from the pump unit to the active fiber. The shaft has an uninsulated outer surface that is electrically conductive and is electrically connected to one of the conductive elements. Then for a cell, the rules can be recursively applied. A sector represents the minimum data size that is erased from the sectored EEPROM in any single erase cycle. Performance of the target system is modeled under the failure scenarios using a performance predictor module for generating a multi-part performability function. Such treatment of the ferromagnetic alloy may be augmented by application thereto of a compressive stress.