A photoconductor that includes a supporting substrate, a first photogenerating layer, a second photogenerating layer and at least one charge transport layer. The system can include a user computer system interposed between a segment of a network allowing communication between the user computer system and at least one server system, and other segments allowing communication between the user computer system and a plurality of third party server systems. A second signal may also be generated based on the reference signal. A temperature measurement device is provided with a temperature sensing portion that senses the temperature of the bare cells, a contact portion connected to the PCM, and a connecting portion through which the temperature sensing portion and the contact portion are connected to each other. Variable modulation amplitudes may be employed on the dither signals to maximize convergence speed. The first fluid chamber is vacuumized to have a first pressure, and the second fluid chamber is also vacuumized to have a second pressure which is lower than the first pressure.