A strip of photographic film is moved relative to the photographic film cassette from which the strip extends. A plurality of motion signals representing motion of the structure are mode selective filtered to generate a plurality of mode selective filtered motion signals such that the mode selective filtered motion signals preferentially represent motion associated with a vibrational mode of the structure. A central axial plane of the third converging lens is perpendicular to the light output surface. The variable capacitor is configured such that a contact area between the second surface portion and the dielectric contacting portion is changed in correspondence to a depressing force, which is applied against the dielectric contacting portion in a direction toward the dielectric, thereby changing an electrostatic capacitance of the variable capacitor. Such increases in efficiency are also obtained where the energy source for the microbial fermentation contains carbon dioxide and the method includes a carbon dioxide stripping step prior to extraction of acetic acid in solvent.