The invention relates to 7-5-hydroxy-2–3-hydroxy-cyclopentyl heptanoic or heptenoic acids and derivatives of said acids, wherein one or more of said hydroxy groups are replaced by an ether group. For example, a friction force being applied to a driving belt of a continuously variable transmission is regulated according to the compensated estimated input torque TINE. The P wells contact an emitter electrode while the floating P layers are not in direct contact with the emitter electrode. Finally, the pattern data, which are used for digital watermarking, are inserted into the picture with the adjusted insertion intensity. Dopants may be introduced in the silicon film during or after deposition. A pointer to a respective buffer space subportion is presented to a protocol stack, so that one or more overhead bytes for the stored voice samples can be generated and written into adjacent address space of the preallocated portion of random access memory.