A brushless direct current magnetic pump includes a drive shaft that passes through and that is coupled to a magnet carrier. The pickup cap, when connected to the electrical connector, may cover the sides of the electrical connector, but not cover the central portion of the electrical connector. Since the source-side local bit line is coupled to a ground node at its both ends, source resistance of the memory cell can be reduced, and dependency of the source resistance of the memory cell on the position within the memory cell array can also be reduced. The treelets are restructured, by a processor, to produce an optimized hierarchical tree data structure.