This invention provides methods and systems for trading and investing in groups of demand-based adjustable-return contingent claims, and for establishing markets and exchanges for such claims. The fluorescent lamp can include a discharge tube extending from a first end to a second end; a resistive transparent coating on the outer surface of the discharge tube; and a pair of electric terminals positioned on the discharge tube such that a first terminal is on the first end and a second terminal is on the second end. A correction unit corrects, based on the correction relative phase angle \u03b8 set by the setting unit, a relative phase shift between a periodic variation in the circumferential speed of a first image bearing member and a periodic variation in the circumferential speed of a second group image bearing member by operationally controlling at least one of first and second drive units. Adaptive recommendation delivery can take the form of visual-based or audio-based formats. The monitored waveform of the switching voltage is compared to the monitored waveform of the at least one of the high and low-side drive signals to determine whether the switching voltage is high or low during at least one of the dead-time periods.