A sewing apparatus includes a hollow needle that can pass through a work cloth, and a needle cover that has a passing hole through which the needle passes and holds the work cloth. This activity value is passed to a quantisation control module which determines quantisation parameters for a quantisation module which quantises the transform coefficients output from the wavelet transform module. A target drive force lower limit correction value is computed based on the target input rotation speed lower limit basic value. The PED based locator is arranged to calculate a distance between the PED and the MT using the time-of-flight between the transmission and the receipt of a reply. The crosslinkable copolymers of the invention are especially useful for the manufacture of biomedical mouldings, for example ophthalmic mouldings such as in particular contact lenses. The method includes obtaining a cyclic \u03b1-N protected active amino ester and adding it to a mixture of an amine catalyst in an organic solvent.