A base station calculates the number of terminals which have transmitted messages at ith frame, and calculates the number of messages to be transmitted at th frame by using the number of terminals which have transmitted the messages in the ith frame. The projection screen includes a lens member including a plurality of lens portions splitting the laser light and a diffusion member arranged to be opposed to the lens member, having an incident surface and a diffusion portion. Still other embodiments of the invention comprise processes for capping nucleophilic groups in a polymer or monomer which comprises combining and reacting the polymer or monomer with a triazine-comprising capping agent. The retrieval unit updates a retrieval condition by use of the recognition candidate and outputs a retrieval result. An N+ region as a first conductive type impurity region provided in a Si substrate with an upper surface being exposed on one main surface of the Si substrate, a P+ polysilicon plug provided with a bottom being contacted with an upper surface of the N+ region, and wiring connected to a top of the P+ polysilicon plug are included.