The present invention discloses a spike free circuit, which comprises a first flip-flop stage, a time shift means, a group of logic gates and a second flip-flop stage. The first region is a portion for isolating circuitry. The occluding device may prevent the passage of embolic or other material to or from the left atrial appendage by volumetrically filling the appendage, closing the opening of the appendage with an occluding member, or pulling the tissue around the opening of the appendage together and fixing it in a closed state. Current data is viewed by supplying via the tag node the most recently added child, and older versions of the database are similarly supplied via the tag nodes transparently presenting older versions of the time-stamped audit nodes. The method also includes creating a local physical-memory descriptor to reference physical memory on the GPU associated with that physical-memory allocator, assigning a physical-memory handle to the local physical-memory descriptor, and returning the physical-memory handle to the graphics-driver process to fulfill a subsequent memory-map request from the graphics-driver process. The amplitude of the filtered signal is adjusted so that it fits in the operational range of the decoder.