The present invention provides, in part, NPC1L1 from various species. The characteristic can depend on the relative motion between the magnetic field and the conductive material of the microfeature workpiece. A user interface may be provided to visually present and manipulate a centerline of the tubular structure and the tubular structure itself. The carrier is electrically connected to the circuit board. If a child inserts a conductive article into the first or second insertion hole, the danger of electrical shock can be avoided to ensure safety in use of electricity.