This invention encompasses novel methods of preparing sibutramine and sibutramine derivatives, and stereomerically pure sibutramine derivatives in particular. An echo cancellation signal is applied to a return path using a combined spatialization and echo path estimate. The carcass part includes wing-joints, coracoids, a wishbone embodied with two legs that merge into each other at an acute angle, a keelbone, a membrane andor ligament that connects at least to the wishbone and the keel-bone, and naturally present meat including inner and outer fillets. When the operation switch on the control panel is then turned on, the ultraviolet lamps and a fan are energized to draw external air from an air inlet. The at least one element is at least partially transparent to radiation passing through the radiation-patterning tool, but does not correspond to a discrete structure printed in the radiation-sensitive material.