The present invention provides a method for producing a circular DNA molecule having a specific structure that enables to distinguish circular DNA formed from a single DNA molecule, from circular DNA formed from multiple DNA molecules and also from single-molecule circular DNA derived from the circular DNA formed from multiple DNA molecules. In one example, the activationdeactivation andor change to the parameters of the rate smoothing function are temporary, and the pre-event state of the rate smoothing function is set to a post-adjusting state, such as after a first time interval. The clutch actuator assembly includes an electric motor, a geared reduction unit, and a clutch apply operator. When being applied by a pressure, the pressure sensor transmits the pressure to a corresponding electrical signal according to an intension of the pressure. The dolly will trail easily because of the offset of the line of force from the load of the ladder relative to the axle.