W.J. Mikowycz is the James P. Hartnett professor of mechanical engineering at the University of Illinois at Chicago. E.M. Sparrow is a member of the National Academy of Engineering at the University of Minnesota, Minneapolis, Minnesota. J.P. Abraham is a professor of mechanical engineering at the University of St. Thomas in St Paul, Minnesota. J.M. Gorman is research associate at the University of Minnesota, Minneapolis, Minnesota.