POWER OF ATTORNEY


      KNOW ALL PERSONS BY THESE PRESENTS, that I, TIMOTHY R. BARAKETT, hereby
make, constitute and appoint each of SCOTT KISLIN, DENNIS BERTRON and CHARLES
FORTIN, acting individually, as my agent and attorney-in-fact for the purpose of
executing in my name, (a) in my personal capacity or (b) in my capacity as chief
executive officer of, managing member of or in other capacities with Atticus
Capital LP or its general partner, Atticus Management LLC (collectively,
"Atticus"), and each of their affiliates, including Atticus UK LLP and Atticus
UK Services Ltd., and entities advised by me or Atticus, all documents,
certificates, instruments, statements, filings and agreements ("documents") to
be filed with or delivered to any foreign or domestic governmental or regulatory
body or required or requested by any other person or entity pursuant to any
legal or regulatory requirement relating to the acquisition, ownership,
management or disposition of securities, futures contracts or other investments,
and any other documents relating or ancillary thereto, including without
limitation all documents relating to filings with the Commodities Futures
Trading Commission and National Futures Association, the United States
Securities and Exchange Commission (the "SEC") pursuant to the Securities Act of
1933 or the Securities Exchange Act of 1934 (the "Act") and the rules and
regulations promulgated thereunder, including all documents relating to the
beneficial ownership of securities required to be filed with the SEC pursuant to
Section 13(d) or Section 16(a) of the Act and any information statements on Form
13F required to be filed with the SEC pursuant to Section 13(f) of the Act. All
past acts of the attorneys-in-fact in furtherance of the foregoing are hereby
ratified and confirmed.

      THIS POWER OF ATTORNEY shall remain in full force and effect until either
revoked in writing by the undersigned or until such time as the person or
persons to whom power of attorney has been hereby granted cease(s) to be an
employee of, or otherwise associated with, Atticus or one of its affiliates.
Execution of this power of attorney revokes that certain Power of Attorney dated
as of January 18, 2007 with respect to substantially the same matters addressed
above.

      IN WITNESS WHEREOF, the undersigned has duly subscribed these presents as
of June 7, 2007.

                                          /s/ Timothy R. Barakett
                                          -----------------------
                                          Timothy R. Barakett