Methods and devices are provided for controlling a fluid flow over a sensing surface within a flow cell. In the magnetic recording medium, concave portions between recording elements are filled with a non-magnetic material. A preferred embodiment has three lead screws and three types of floating mountings. Based on path power estimates, the controller adaptively allocates combining correlators to signal paths. The communication apparatus is complied with the IEEE 1394 Standard and capable of managing the other nodes on the communication network.