A retractable bed is disclosed which can be automatically raised and lowered in a vertical fashion. The PLL can further include a loop filter coupled to the three-state phase detection circuit, a VCO coupled to the output of the loop filter, a VCO buffer coupled to the output of the VCO for providing an output frequency signal, and a dual modulus prescaler having a synchronous counter using feedback among D flip-flops for generating the divided output frequency signal. The flapper is operably connected to the trigger for moving the trigger. The controller generates an autoregulation status signal representing a status of cerebral autoregulation. Thus, the hot water and steam generator increases the water temperature rapidly due to collision and friction of water molecules by rotation of the rotation wheel so as to produce hot water and steam easily, rapidly and conveniently. The program outputs multiple solutions with varying degrees of difficulty and varying amounts of performance improvement.