Exhibit 24**POWER OF ATTORNEY**     Know all men by these presents, that the undersigned constitutes and appoints Frank J.Bramanti and Edward H. Ellis, Jr. and each of them, his true and lawful attorney-in-fact and agentwith full power of substitution and resubstitution, for him and in his name, place, and stead, inany and all capacities, to sign this Annual Report on Form 10-K/A and any and all amendmentsthereto, and to file same, with all exhibits thereto, and other documents in connection therewith,with the Securities and Exchange Commission, granting unto such attorneys-in-fact and agents, andeach of them, full power and authority to do and perform each and every act and thing requisite andnecessary to be done in and about the premises, as fully to all intents and purposes as he might orcould do in person, hereby ratifying and confirming all that such attorneys-in-fact and agents orany of them, or their or his substitute or substitutes, may lawfully do or cause to be done byvirtue hereof.        December 18, 2006 /s/ PATRICK B. COLLINS   Patrick B. Collins      

 
Exhibit 24**POWER OF ATTORNEY**     Know all men by these presents, that the undersigned constitutes and appoints Frank J.Bramanti and Edward H. Ellis, Jr. and each of them, his true and lawful attorney-in-fact and agentwith full power of substitution and resubstitution, for him and in his name, place, and stead, inany and all capacities, to sign this Annual Report on Form 10-K/A and any and all amendmentsthereto, and to file same, with all exhibits thereto, and other documents in connection therewith,with the Securities and Exchange Commission, granting unto such attorneys-in-fact and agents, andeach of them, full power and authority to do and perform each and every act and thing requisite andnecessary to be done in and about the premises, as fully to all intents and purposes as he might orcould do in person, hereby ratifying and confirming all that such attorneys-in-fact and agents orany of them, or their or his substitute or substitutes, may lawfully do or cause to be done byvirtue hereof.        December 18, 2006 /s/ JAMES R. CRANE   James R. Crane     
 

 
     Exhibit 24**POWER OF ATTORNEY**     Know all men by these presents, that the undersigned constitutes and appoints Frank J.Bramanti and Edward H. Ellis, Jr. and each of them, his true and lawful attorney-in-fact and agentwith full power of substitution and resubstitution, for him and in his name, place, and stead, inany and all capacities, to sign this Annual Report on Form 10-K/A and any and all amendmentsthereto, and to file same, with all exhibits thereto, and other documents in connection therewith,with the Securities and Exchange Commission, granting unto such attorneys-in-fact and agents, andeach of them, full power and authority to do and perform each and every act and thing requisite andnecessary to be done in and about the premises, as fully to all intents and purposes as he might orcould do in person, hereby ratifying and confirming all that such attorneys-in-fact and agents orany of them, or their or his substitute or substitutes, may lawfully do or cause to be done byvirtue hereof.        December 18, 2006 /s/ J. ROBERT DICKERSON   J. Robert Dickerson     
 

 
     Exhibit 24**POWER OF ATTORNEY**     Know all men by these presents, that the undersigned constitutes and appoints Frank J.Bramanti and Edward H. Ellis, Jr. and each of them, his true and lawful attorney-in-fact and agentwith full power of substitution and resubstitution, for him and in his name, place, and stead, inany and all capacities, to sign this Annual Report on Form 10-K/A and any and all amendmentsthereto, and to file same, with all exhibits thereto, and other documents in connection therewith,with the Securities and Exchange Commission, granting unto such attorneys-in-fact and agents, andeach of them, full power and authority to do and perform each and every act and thing requisite andnecessary to be done in and about the premises, as fully to all intents and purposes as he might orcould do in person, hereby ratifying and confirming all that such attorneys-in-fact and agents orany of them, or their or his substitute or substitutes, may lawfully do or cause to be done byvirtue hereof.        December 18, 2006 /s/ WALTER M. DUER   Walter M. Duer     
 

 
     Exhibit 24**POWER OF ATTORNEY**     Know all men by these presents, that the undersigned constitutes and appoints Frank J.Bramanti and Edward H. Ellis, Jr. and each of them, his true and lawful attorney-in-fact and agentwith full power of substitution and resubstitution, for him and in his name, place, and stead, inany and all capacities, to sign this Annual Report on Form 10-K/A and any and all amendmentsthereto, and to file same, with all exhibits thereto, and other documents in connection therewith,with the Securities and Exchange Commission, granting unto such attorneys-in-fact and agents, andeach of them, full power and authority to do and perform each and every act and thing requisite andnecessary to be done in and about the premises, as fully to all intents and purposes as he might orcould do in person, hereby ratifying and confirming all that such attorneys-in-fact and agents orany of them, or their or his substitute or substitutes, may lawfully do or cause to be done byvirtue hereof.        December 18, 2006 /s/ JAMES C. FLAGG   James C. Flagg, Ph.D.     
 

 
     Exhibit 24**POWER OF ATTORNEY**     Know all men by these presents, that the undersigned constitutes and appoints Frank J.Bramanti and Edward H. Ellis, Jr. and each of them, his true and lawful attorney-in-fact and agentwith full power of substitution and resubstitution, for him and in his name, place, and stead, inany and all capacities, to sign this Annual Report on Form 10-K/A and any and all amendmentsthereto, and to file same, with all exhibits thereto, and other documents in connection therewith,with the Securities and Exchange Commission, granting unto such attorneys-in-fact and agents, andeach of them, full power and authority to do and perform each and every act and thing requisite andnecessary to be done in and about the premises, as fully to all intents and purposes as he might orcould do in person, hereby ratifying and confirming all that such attorneys-in-fact and agents orany of them, or their or his substitute or substitutes, may lawfully do or cause to be done byvirtue hereof.        December 18, 2006 /s/ ALLAN W. FULKERSON   Allan W. Fulkerson     
 

 
     Exhibit 24**POWER OF ATTORNEY**     Know all men by these presents, that the undersigned constitutes and appoints Frank J.Bramanti and Edward H. Ellis, Jr. and each of them, his true and lawful attorney-in-fact and agentwith full power of substitution and resubstitution, for him and in his name, place, and stead, inany and all capacities, to sign this Annual Report on Form 10-K/A and any and all amendmentsthereto, and to file same, with all exhibits thereto, and other documents in connection therewith,with the Securities and Exchange Commission, granting unto such attorneys-in-fact and agents, andeach of them, full power and authority to do and perform each and every act and thing requisite andnecessary to be done in and about the premises, as fully to all intents and purposes as he might orcould do in person, hereby ratifying and confirming all that such attorneys-in-fact and agents orany of them, or their or his substitute or substitutes, may lawfully do or cause to be done byvirtue hereof.        December 18, 2006 /s/ JOHN N. MOLBECK, JR.   John N. Molbeck, Jr.     
 

 
     Exhibit 24**POWER OF ATTORNEY**     Know all men by these presents, that the undersigned constitutes and appoints Frank J.Bramanti and Edward H. Ellis, Jr. and each of them, his true and lawful attorney-in-fact and agentwith full power of substitution and resubstitution, for him and in his name, place, and stead, inany and all capacities, to sign this Annual Report on Form 10-K/A and any and all amendmentsthereto, and to file same, with all exhibits thereto, and other documents in connection therewith,with the Securities and Exchange Commission, granting unto such attorneys-in-fact and agents, andeach of them, full power and authority to do and perform each and every act and thing requisite andnecessary to be done in and about the premises, as fully to all intents and purposes as he might orcould do in person, hereby ratifying and confirming all that such attorneys-in-fact and agents orany of them, or their or his substitute or substitutes, may lawfully do or cause to be done byvirtue hereof.        December 18, 2006 /s/ MICHAEL A. F. ROBERTS   Michael A.F. Roberts