A technique for realtime-safe detection of a grace period for deferring the destruction of a shared data element until pre-existing references to the data element have been removed. The method includes the following steps. They may be mounted for example beside doors or on fence or gate posts, or on walls such as the outside walls of buildings or enclosures such as storage sheds, metal storage containers, etc. Thus, heat from the module is provide directly to the chassis of the set-top box from which it is released by convention into the ambient environment. The actively shielded gradient windings and passive shielding should be designed concurrently in order to substantially optimize the gradient linearity and reduce the eddy currents generated in metallic parts of the magnetic resonance imaging system. These compounds can be used in the treatment of pathologies associated with hyperglycaemia.