An improved thickening composition for organic systems, including paints and coatings, is described. The scaffold is advantageously homocysteine thiolactone. The over-center mechanism includes a pair of levers held together by a single coil spring with trunnions on a first lever pivoting in bearing surfaces of a second lever. In response to determining that the indicators map exists, it is determined whether the indicators map is to be trusted based on a last modified time and a last source file size stored in the indicators map and the source file. At least one of the rotational rate of the screw or the feed rate of the feeder can then be increased during a transient state until a steady state is reached. The mower includes a cutter deck having at least one Rota table cutter driven by a substantially vertically-disposed driven shaft.