text: 15 
  
  F. Marsiglio for many discussions concerning the infrared 
  conductivity and optical integrals and thank A. Boris, E. 
  van Heumen, J. Hirsch, and F. Marsiglio for the com- 
  ments on the manuscript. The work was supported by 
  nsf-dmr 0906953. 
  
  We would like to thank M. Norman, Tom Timusk, 
  Dmitri Basov, Chris Homes, Nicole Bontemps, Andres 
  Santander-Syro, Ricardo Lobo, Dirk van der Marel, A. 
  Boris, E. van Heumen, A. B. Kuzmenko, L. Benfato, and 