A track width defining layer includes: a track width defining portion having an end located in the air bearing surface and the other end located opposite to the air bearing surface; and a wide portion coupled to the other end of the track width defining portion. The connection changer includes a movable delivery connector selectively and independently connectable to each of the plurality of supply connectors associated with the support member. A radiator is disposed outside of and in contact with the insulator and has a slot formed on the top surface thereof extending in parallel with the tube axis. The present invention provides queue-theoretic methods that provide a modeling and simulation capability in support of decisions about the staffing of call-handling centers based on the frequency of incoming calls and the competency of automated dialog systems.