Footnotes:

¹This work was supported by the Director of Energy Research, Office of Basic Energy Sciences. The Ames Laboratory is operated for the U. S. Department of Energy by Iowa State University under Contract W-7405-ENG-82.

²E-mail: carlson@decst2.ams.ameslab.gov

³Replacement of r by r+1 and q by q-1 yields Equation (5.12) in [ Carlson1998], an equation that is now seen to be merely a special case of Equation (5.13) and so can be omitted.