A wheel cover attachment system including a cover for a wheel wherein the wheel includes a plurality of wheel fasteners and a valve stem. The exercise apparatus allows the user to exercise the mid-section, hips, legs, ankles and connective tissues enjoining all the muscles in these areas. The second audio signals are then filtered with an adaptive filter, so that third audio signals are generated, in which the components of the useful signal are equalized to an even greater degree than in the second audio signals. The resistor string is directly connected to the current DAC without the need of buffer amplifiers. An event mask permits selective masking of event types. The process in accordance with the invention can be used with an alkeneone substituent or an alkyneone substituent on a steroid ring base to make squalamine or other useful aminosterol compounds and intermediates for making aminosterol compounds.