POWER OF ATTORNEY

I, Gregory W. Scott, do hereby constitute and appoint Joseph S.
Konowiecki, Michael E. Jansen and Ellen K. Erickson, or each one of them
separately, as my true and lawful attorneys and agents, to do any and all
lawful acts and things in my name and on my behalf, and to execute any and
all instruments, forms or filings in my name and on my behalf, which said
attorneys and agents, or each one of them separately, may deem necessary or
advisable in order for me to comply with the disclosure requirements of
Section 16(a) of the Securities Exchange Act of 1934, and any related rules,
regulations, and requirements of the Securities and Exchange Commission;
and do hereby ratify and confirm all that said attorneys and agents, or
each one of them separately, shall do or cause to be done by virtue hereof.

Date:  May 17, 2004

Gregory W. Scott