A wood screw includes a head part, a tapered insert part, and a shank part disposed between the head part and the tapered insert part. The shift register comprises: a signal outputting circuit, a signal inputting circuit, an inverting circuit and a logic circuit. In a deep sleep mode the supply voltage for the bit cell in the SRAM macro is lowered by about 20-40% of the SRAM supply voltage, sufficient to retain the data in the bit cell. The system still further includes storage means adapted for storing at least one selected constant value associated with the selected polynomial relationship, which constant values are chosen so as to define at least one curve associated with the selected polynomial relationship.