One switch-state aggregation technique uses a digital-to-analog converter in combination with an analog-to-digital converter to aggregate the state of a plurality of switches. A handwashing agent is provided with a detectable, volatile compound, such as odors, which is then rubbed onto a subject’s hands using the subject’s handwashing technique. Further, the headrest includes easily adjustable, wing-like, side-support members that are pivotally connected to a centrally located, vertically adjustable head support member by means of specially designed hinges. When the apparatus turns into a standby state based on an optical signal from a transmitting device, the switch circuit is brought into OFF by a microcomputer in the remote control receiving device. In one embodiment of the method, the casting mold is manufactured for the molding size 1 to 5% less than necessary, and the cusp is placed after molding into an anticoagulant solution and matured therein until expanding by 1 to 5%.