A distributed system in which time-dependent credentials are supplied by controllers that operate according to different local times. The hydrogen generator includes a cartridge, a housing with a cavity to removably contain the cartridge, and an initiation system. The shoulder includes two key channels extending therethrough parallel to the axis and spaced apart 90\xb0. The mobile agent is deployed onto an application server to monitor the effectiveness of operation of the heap of a virtual machine within the application server. When an obstacle is detected by obstacle sensors, the caution-image generating unit extracts an image of those stored in an image memory, in an area including a part of the vehicle and the obstacle, generate a caution image, and displays the caution image at a position on the overhead image via the display processing unit corresponding to the position of the obstacle. The protective agent for a neuronal cell according to the present invention contains a compound represented by the following general formula I or a salt thereof as an active ingredient.