A method of locating a mobile device, and a mobile device utilizing the same are provided. In this configuration, the pre-pits are detected from only the read signals input during a period of irradiation of the second light beam. The receiver is configurable according to the receiving channel and processing type selected. The invention also provides methods of using these triplex structures for making recombinant cells, as well as methods of using the recombinant cells to express proteins of interest both in vitro and in vivo. If the count differs between the two operations, the circuit determines that the encoder strip is damaged, and the circuit develops a signal indicating this damage. As the demand curve shifts, the price is adjusted to maintain optimal demand.