A communication system for transmitting and receiving data at high speed can be self-tested at actual operating speed with low cost, and without increasing the chip area. The power control circuit is provided in an electronic device and is connected a solar power supply. The second capacitor electrode includes a first section which is opposite to the internal side of the tube-like structure, with the dielectric arranged therebetween, and a second section, which is opposite to the external side of the tube-like structure with the dielectric arranged therebetween. Inhibitors of neurotactin expression or activity can be used to treat inflammation.