Methods and apparatus for a bi-directional self-centering linkage are provided. When the switch is first cycled, the control circuit commands the signal driver to emit a verification signal; when the switch is second cycled, the control circuit again commands the signal driver to emit a verification signal; and thereafter, when the switch is opened a third time, the control circuit will begin timing its predetermined fixed time interval. The rotatable member is provided with at least one upstanding bar that is sized to cooperate with the walls of the aspiration port and the inner surface of the catheter assembly to macerate debris that is drawn into the aspiration port. The user’s activities may be examined to identify a set of preferred locations. Compositions and methods for treating cancer and fungal infection are also disclosed. It is an object of the invention to reduce the leakage current.