A mechanism for raising and lowering a toilet seat in response to actuation of foot pedals. The method and apparatus include quantizing and entropy encoding a second frequency coefficient matrix that is generated by performing a partial exchange of one or more values between rows and between columns of a first frequency coefficient matrix. The invention also relates to novel intermediates prepared during the synthesis of the 9-deoxy-PGF1-type compounds. Each metal sheet has hot and cold edge portions at the hot and cold ends respectively of the heat exchanger.