The invention relates to a crossbar switch controller including an input terminal configured to receive a set of service request signals from a set of virtual output queues each comprising a set of packets. The signal combiner is supplied with a bias-corrected input calculated by a distorted codeword signature generator, which is operative to generate and store a set of N codeword power correction values. The writing surface may be disposed between layers of the mousepad, include the bottom surface of the mousepad, or be contained on a slidable tray located between layers. Utilizing the difference value and the pixel data, a multi-layered background registration is performed to get a background. The present invention further provides a method for searching for a therapeutic agent for pain, a therapeutic agent for inflammation, and a therapeutic agent for pruritus using G protein coupled receptor 83, which is an HK-1 specific receptor. The first surface is formed with a multiplicity of projections 7 having respective tips held in tight contact with the light exit surface of the light guide member 3, at least a portion of each of the projections 7 having a curved facet.