A differential for motor vehicles installed between two half-shafts on which two drive wheels are keyed includes a box driven by the engine by a connecting element which causes it to rotate about axes of the half-shafts, on free ends of the latter there being keyed two bevel gears housed inside the box, the differential and the half-shafts being contained inside a casing. Saids derivatives show a specific cytotoxicity to tumour cells, also of neuroectodermal origin, to which they may in particular act as aloe-emodin prodrugs. The system also provides the capability of contemporaneously playing a message received from the caller to the subscriber. If the subsequent review takes too long to complete, then a second computer may be used to compute a second fraud score to determine an outcome for the transaction. A depletion region of the photodiode is constantly maintained in a defect-free region during operation of the CMOS image sensor. The method comprises the steps of categorizing said available frequency spectrum resources with respect to volatility, and categorizing said one or several services with respect to compressibility, and assigning said one or several services to the available spectrum resources such that compressible services are assigned to volatile spectrum resources.