A density centrifuge blood processing system with automatic two-dimensional optical control of fluid separation by observing fluid characteristics in observation regions. A coaxial two-wheel vehicle according to the present invention includes step portions on which feet are placed, and a handle capable of operating back-and-forth movements, and said vehicle moves with a passenger riding thereon. The speed control signal and analog signal are determined based on the luminance signal obtained in digital form from the video camera, and analyzed over at least one field of video. As an alkali carbonate, sodium carbonate is preferably used. Preferably the coronary artery signals are segmented from contrast signals emanating from the myocardium and the heart blood pool so that the coronary arteries are clearly highlighted and distinct in the ultrasonic angiogram. The device includes one or more processors configured to decompose a created credential into credential components, parse the credential components using a limited dictionary, determine a probability of the credential components using a limited ruleset, and calculate a score of the created credential based on the determined probability.