The present invention is directed to a carrier and conveyor system that permits the carrier to be driven by at least two different types of conveyors or drive assemblies, including a power and free conveyor. The network element transmits the message signals to a central network management facility which selects one of the message signals as a timing reference based on the synchronization status messages and based on stored information about the structure and configuration of the network. The exhaust gas treatment system includes particulate filter device in fluid communication with an exhaust gas conduit, an electric heater, a primary energy storage device, a single secondary energy storage device, and a control module. The notch acts to prevent the collection bag from sealing off the conduit during surgery so that a sufficient amount of air will remain within the bag to allow a surgeon to air vent an aspiration path during surgery. The power semiconductor element and the first and second insulating substrates are sealed with a resin. As a result, the pressure compensator assembly compresses the lubricant disposed within the sealed lubricant chamber and, accordingly, functions to maintain a positive pressure situation within the lubricant chamber.