Methods and apparatus are described by which media assets may be prioritized and published in accordance with current topics of interest derived from a dynamic data set representing the online activity of a relevant population of users. The arc tube has two spiral parts that are wound around an axis \u201cA\u201d, and a turning part joining the two spiral parts. The at least two sensors read an image formed on the rotary body. An insulation boundary is defined between the communication microcomputer and the motor control microcomputer to isolate a low-voltage side electric component receiving electric power of the low-voltage battery from a high-voltage side electric component receiving electric power of the high-voltage battery. Outgoing data packets are sent alternately to one or the other processor, whereby transmission processing can be accelerated relative to receive processing.