An information processing system includes an information management apparatus that accepts image generation requests and an image generation section that generates image data, which is provided independently of the information management apparatus. In one example embodiment, an x-ray tube includes a housing, a window frame attached to the housing, and a window attached to the window frame. The trigger comprises a compression spring 26 and a cam 33 which engages a pressure sensitive puff lever 28 with a plate 29 that releases the cocked trigger when a user sucks on the mouthpiece and draws in air through air inlet opening 26. For other types of communication sessions, such as high-speed data and streaming video, the reverse link frequency band and the second forward link frequency band are used. The upper surface of the second insulating layer connecting to the outer side surface thereof is exposed from the third insulating layer. The server determines whether the chunk stored at the local cache of the first one of the client computers is globally oldest among the chunks stored in the local caches at the client computers, and authorizes the first one of the client computers to evict the chunk when the chunk is the globally oldest among the chunks stored in the local caches at the client computers.