A peering authority or settlement clearinghouse can be used to control access, collect session accounting information, and provide financial settlement of interconnect or session fees among anonymous Internet Protocol peers or networks. In one embodiment, the SOA includes a Multiple Quantum Well stacks whose thickness varies along the length of the device. The synchronous cell of the extension carrier can be determined so that the extension carrier is available between the network side and a user equipment to thereby improve the performance of the system. As a result, the troublesomeness of an assembly of track roller bogie and a reduction in service life due to defective lubrication can be eliminated. In order to provide protection against input current pulses, an ohmic resistor is provided in the form of a resistive layer that is applied by pressing. A gas conditioning system positioned in the door is configured to maintain a desired concentration and phase of gas constituents in the passageway.