The invention includes, among its various aspects, an apparatus, method and system in which an electric machine includes at least a portion of a magnetic circuit composed of an electromagnetic material having a Curie temperature, and further includes a heating apparatus for selectively heating the portion sufficiently close to its Curie temperature to thereby regulate operation of the machine. The upper plate of plasma display panel comprises an upper substrate, a transparent electrode disposed on a predetermined position of the upper substrate, a bus electrode disposed on a predetermined position of the transparent electrode and a black matrix disposed between the transparent electrode and the bus electrode, and in each discharge cell. A background picture database can provide a background picture to be transmitted instead of the background scene. The methods can prolong the useful life of the fuel cell or fuel cell system. The systems and methods include an automated process for creating jointed target pairs or horizontal laterals to be utilized for planning horizontal wells in order to position the horizontal laterals within limited pre-defined boundary. The electrically conductive body is located such that the emitted secondary electrons impinge on the target body to neutralise positive charge which may build up on the target body.