A semiconductor light emitting device of double hetero junction includes an active layer and clad layers. Methods of use of the cells for screening for anti-hyperproliferative agents, and use of the cells for animal models of hyperproliferative disorders including metastatic cancer, diagnostic methods, and therapeutic methods are provided. A pulse generator includes circuits that prevent the pulse generator from being reactivated until after a power cycle. Each of the first and second touch operations includes a press, a touch track, or a combination of a press and a touch track on a key.