A device for inducing weight loss in a patient includes a tubular prosthesis positionable at the gastro-esophageal junction region, preferably below the z-line. An optical data storage medium comprises a plurality of spacer layers and data surfaces. The pivot arm of the tensioner is connected to a one-way clutch. Such parameters are used to generate or address a communications resource for use by the mobile station. At least one of the flow control members allows a user to switch between two states of fluid flow, one in which fluid flow is enabled between the first port and the third port as well as between the third port and the second port, and one in which fluid flow is enabled between the second port and the third port.