A system and method for storage checkpointing to a group of independent computer applications. The invention further relates to rheology control agents containing polyureas and to the use thereof. A measuring cell housing accommodates the measuring electrode and the counter electrode. In the case that sufficient resources become available, the handoff manager instructs the mobile terminal to return to a connected mode. or lower in an inert atmosphere, heating the material to 1420 to 2200 C. The image forming apparatus has an operation control unit which controls execution of an image stabilization processing during a waiting time till a heating temperature of the fixing unit becomes the fixing temperature.