A method, computer readable medium, and system for advertisement and content distribution are provided. The distance that the rider is suspended beneath the lift cable is controllably increased and, thereafter, the rider enters the water, such as to surf the waves. An extended lead ECG calculator 16 calculates extended lead ECGs V7-V9 from the ECG signals stored in the ECG memory 12, using coefficients \u03b1 representing a relationship among leads. The method comprises mixing at least one compound of manganese and pore forming articles.