On-demand scheduling for presentations in movie theatres is enabled by providing users with the ability to communicate content, theatre and time slot selections. The noise cancelling circuit cancels these noise signals from the electrical signals which originate within the heart and which are sensed between the tip electrode of a stimulator lead and the indifferent electrode of the stimulator housing. The handle has a stand-off receiving notch associated with each side and each stand-off receiving notch receives one of the stand-offs when the drive carrier is locked in place on the surface. The tensioners are then linked to each other by a rigid, solid link. The microorganisms are capable of metabolizing the explosive material. The electrical device can be, for instance, a power amplifier.