<PAGE>



                                                                      EXHIBIT 24



                               POWERS OF ATTORNEY

<PAGE>



                                POWER OF ATTORNEY



         Know all men by these presents, that the undersigned constitutes and
appoints Stephen L. Way and Edward H. Ellis, Jr., and each of them, his true and
lawful attorney-in-fact and agent, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign this Annual Report on Form 10-K and any and all amendments
thereto, 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, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents or any of the, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.



                              /s/ FRANK J. BRAMANTI
                              ---------------------
                              Frank J. Bramanti

                              Date: March 1, 2005


<PAGE>




                                POWER OF ATTORNEY


         Know all men by these presents, that the undersigned constitutes and
appoints Stephen L. Way and Edward H. Ellis, Jr., and each of them, his true and
lawful attorney-in-fact and agent, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign this Annual Report on Form 10-K and any and all amendments
thereto, 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, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents or any of the, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.





                               /s/ PATRICK B. COLLINS
                               ----------------------
                               Patrick B. Collins

                               Date: March 1, 2005



<PAGE>


                                POWER OF ATTORNEY



         Know all men by these presents, that the undersigned constitutes and
appoints Stephen L. Way and Edward H. Ellis, Jr., and each of them, his true and
lawful attorney-in-fact and agent, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign this Annual Report on Form 10-K and any and all amendments
thereto, 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, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents or any of the, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.




                               /s/ JAMES R. CRANE
                               ------------------
                               James R. Crane

                               Date: March 1, 2005


<PAGE>



                                POWER OF ATTORNEY


         Know all men by these presents, that the undersigned constitutes and
appoints Stephen L. Way and Edward H. Ellis, Jr., and each of them, his true and
lawful attorney-in-fact and agent, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign this Annual Report on Form 10-K and any and all amendments
thereto, 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, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents or any of the, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.





                               /s/ J. ROBERT DICKERSON
                               -----------------------
                               J. Robert Dickerson

                               Date: March 1, 2005


<PAGE>


                                POWER OF ATTORNEY


         Know all men by these presents, that the undersigned constitutes and
appoints Stephen L. Way and Edward H. Ellis, Jr., and each of them, his true and
lawful attorney-in-fact and agent, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign this Annual Report on Form 10-K and any and all amendments
thereto, 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, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents or any of the, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.





                                 /s/ WALTER M. DUER
                                 ------------------
                                 Walter M. Duer

                                 Date: March 1, 2005



<PAGE>


                                POWER OF ATTORNEY


         Know all men by these presents, that the undersigned constitutes and
appoints Stephen L. Way and Edward H. Ellis, Jr., and each of them, his true and
lawful attorney-in-fact and agent, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign this Annual Report on Form 10-K and any and all amendments
thereto, 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, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents or any of the, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.





                               /s/ JAMES C. FLAGG, PHD.
                               ------------------------
                               James C. Flagg, PhD.

                               Date: March 1, 2005


<PAGE>



                                POWER OF ATTORNEY


         Know all men by these presents, that the undersigned constitutes and
appoints Stephen L. Way and Edward H. Ellis, Jr., and each of them, his true and
lawful attorney-in-fact and agent, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign this Annual Report on Form 10-K and any and all amendments
thereto, 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, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents or any of the, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.





                               /s/ ALLAN W. FULKERSON
                               ----------------------
                               Allan W. Fulkerson

                               Date: March 1, 2005


<PAGE>




                                POWER OF ATTORNEY


         Know all men by these presents, that the undersigned constitutes and
appoints Stephen L. Way and Edward H. Ellis, Jr., and each of them, his true and
lawful attorney-in-fact and agent, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign this Annual Report on Form 10-K and any and all amendments
thereto, 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, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents or any of the, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.




                               /s/ WALTER J. LACK
                               ------------------
                               Walter J. Lack

                               Date: March 1, 2005


<PAGE>






                                POWER OF ATTORNEY


         Know all men by these presents, that the undersigned constitutes and
appoints Stephen L. Way and Edward H. Ellis, Jr., and each of them, his true and
lawful attorney-in-fact and agent, with full power of substitution and
re-substitution, for him and in his name, place and stead, in any and all
capacities, to sign this Annual Report on Form 10-K and any and all amendments
thereto, 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, and each of them, full power and authority to
do and perform each and every act and thing requisite and necessary to be done
in and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that such
attorneys-in-fact and agents or any of the, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.



                              /s/ MICHAEL A. F. ROBERTS
                              -------------------------
                              Michael A. F. Roberts

                              Date: March 1, 2005