A plating apparatus can form a plated film having a uniform thickness on a surface to be plated of a substrate without employing a complicated structure, such as a conduction detection means capable of detecting the state of conduction of feeding contacts in contact with a conductive portion of the substrate. The slew rate control circuit has a predetermined impedance, and supplies a constant current from an output according to an input signal. The present invention also relates to isolated polynucleotides that encode regulatory regions of dwf4. The silicon cap simultaneously surrounds the epitaxial structures. A secondary battery capacity decrease is estimated based on the accumulated current.