  Egorov and March plotted the product of resistivity and the copper
spin-lattice relaxation time vs. temperature for yttrium barium copper oxide
finding a minimum at temperature T greater than the superconducting
temperature, heralding an electronic phase change which can be interpreted as
the formation of a "preformed" pair. In this context we propose a
superconducting mechanism based on the notion that the preformed pair is a
"soft" boson (a localized, different type of Cooper pair) which dissociates
above the classical BKT transition temperature, resulting in two circular
charge density waves. The model suggests explanations for considerable
experimental work and offers a physical explanation for the basis of the
Uemura-Homes law.
