A polyalkylene glycol comprising: a random copolymer comprising units derived from EO and units derived from PO initiated with polytetrahydrofuran; wherein the polyalkylene glycol has a pour point of less than or equal to \u221230\xb0 C. Waveform widths of the waveform data at a mask reference level, or a predetermined level down from the respective peaks, are evaluated as mask reference widths and then masks of the respective peaks are set using the mask reference level and mask reference widths. The microphone boot can be a composite microphone boot that is formed from multiple materials. If the lamp ignite within the predetermined period of time, control circuit ceases controlling inverter to maintain its operating frequency at the present value, so as to allow for normal operation of the lamp. The microwave reflected by the microfibers is received by a receiving antenna coaxial with the transmitting antenna and is used to identify tag by determining the orientation of the fibers. The catheter in one embodiment includes an array of semiconductor light sources near its distal end, energized from the proximal end.