This invention relates generally to apparatus and methods for the calibration of implanted pressure transducers. A first signal indicates the direction that electric current exists between a first voltage bus and an output terminal of the power inverter. Catalyst usable for the polymerization of -olefins, including a compound containing at least one transition metal belonging to groups IIIb, IVb, IVb and VIb of the Periodic Table, bound in or on this support. The apparatus may also include an active testing function, wherein the active testing function is configured to provide a sequence of step changes to an input of the control system, receive data from the control system in response to the sequence of step changes, and calculate a parameter related to the performance of the control system. According to the invention, a fastening mechanism is provided, with elongate profiles which extend separately from each other with a clearance in between them and to which the device for controlling the movement can be attached. The present invention includes an electric circuit coupled to, for example, a blood circuit used during dialysis therapy.