An optical fiber comprising a core capable of transmitting light incident from one end in the lengthwise direction toward the other end, the core consisting of a polymer of a polymerizable stock material that contains a polymerizable hydroxy monomer with a hydroxyl group in the molecule, wherein the content of the polymerizable hydroxy monomer is 0. According to one embodiment of the invention, a method for managing user registrations in the first IMS network is provided. Further, a refresh frequency for the refresh operation is selected such that the refresh frequency is minimized to conserve power consumed by the memory device while being sufficient to refresh the rows of the memory cells. The average power is controlled using an outer fairness loop balancing the average channel power against average bit rate per channel. The aqueous solution is maintained at a temperature ranging from about 50 to about 60 Degrees Celsius.