There is provided a column repair technology of a semiconductor memory device. The pivot end is pivotal horizontally on a base pivot positioned on a chair attachment that is fixable to a motorized chair. This is generally accomplished by using a pair of capacitors that are cross-coupled across the differential input pair of the amplifier. The combination is subjected to conditions for amplifying the target polynucleotide and the reference polynucleotide. The shielding member includes a slit or a groove and is pressed against an opening edge of the opening portion.