Abstract: A location-limited channel is implemented using physical exchanges of physical tokens. The physical tokens are implemented using writeable or re-writeable storage media. Location-limited channels, when used to implement pre-authentication protocols, provide demonstrative identification and authenticity. A group originator loads pre-authentication information and a network location from a communication device onto the location-limited physical token channel. The location-limited physical token channel is passed to another participant, who copies the originator's pre-authentication information and location onto that participant's communication device. That participant then adds that participant's own pre-authentication information and network location onto the location-limited physical token channel. This is repeated until the last participant passes the location-limited physical token channel back to the group originator.

Abstract: A recreational ramp suitable for use with wheeled vehicles, including a support structure and a molded concrete layer mounted on the support structure. The layer includes a sloping region that extends from a ground level to an above-ground level. Also, a process for the fabrication of a molded concrete layer for such a recreational ramp. The process includes preparing a mold from complementary parts, closing the parts onto one another, thus defining an interior space representative of a concrete layer, pouring concrete mixture into the mold; allowing the concrete to settle and separating the complementary parts of the mold to expose the molded concrete layer. Embodiments of the invention offer the advantages of conventional concrete, i.e., a smooth, quiet and durable surface for riding, while the ramp as a whole remains lightweight and less bulky as compared with conventional concrete ramps. A particularly advantageous embodiment uses self-leveling concrete.