A fixing device includes a fixing belt, a pressuring member, a pressing member, a guiding member, a cap member, an elastic member and a detecting mechanism. In one embodiment patients exhibiting social or learning disabilities as well as abnormally low NF1 activity are administered PAK inhibitors to treat the social or learning disabilities. In a preferred embodiment, the fiber component is a mixture of polyester and glass fibers and the binder is a latex binder. Notably, the first length of the first gate is different from the second length of the second gate.