An energy absorbing sports board assembly that is not fixed to the floor of the arena but is allowed to move relative to the arena floor. An inductor switch control signal controls an inductor switch through which the inductor current flows. The light detector is adapted to detect a light beam emitted by the light source. A tip is formed at the distal end of the inner member. The prosthetic section is connected to the three commissure posts and defines three leaflets, preferably formed of pericardial tissue. In one embodiment, the present invention provides nucleic acids encoding gag, pol andor env genes of plant retroelements.