Systems and methods are disclosed for building and using decision trees, preferably in a scalable and distributed manner. A proximal movement of the first needle shield with respect to the support body releases the retention of the second needle shield in the retracted position, so that the second needle shield is allowed to slide in the distal direction towards an advanced position. When the high-side switch and low-side switch are switched off, the energy stored in the transformer will be transmitted to a secondary circuit and charged to a bulk capacitor. The parameter is extracted from the command by a decoder and is passed to a specific line of an equator set which contains identifiers which determine the partition to be used. After an occurence of the write buffers full condition, a time stamp trace record is inserted before a new trace record can be written.