POWER OF ATTORNEY

     Know all by these presents, that the undersigned hereby constitutes and
appoints each of Brenda Meyette, Jacquelyn Cannata, Anne T. Leland or Nishant
Dharia of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., signing singly,
with full power of substitution, the undersigned's true and lawful
attorney-in-fact to:

     (1)  execute for and on behalf of the undersigned, forms and authentication
          documents for EDGAR Filing Access;

     (2)  do and perform any and all acts for and on behalf of the undersigned
          which may be necessary or desirable to complete and execute any such
          forms and authentication documents; and

     (3)  take any other action of any type whatsoever in connection with the
          foregoing which, in the opinion of such attorney-in-fact, may be of
          benefit to, in the best interest of, or legally required by, the
          undersigned, it being understood that the documents executed by such
          attorney-in-fact on behalf of the undersigned pursuant to this Power
          of Attorney shall be in such form and shall contain such terms and
          conditions as such attorney-in-fact may approve in such
          attorney-in-fact's discretion.

     The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary, or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or revocation,
hereby ratifying and confirming all that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be
done by virtue of this power of attorney and the rights and powers herein
granted.

     This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file forms and execute authentication
documents with respect to the undersigned's EDGAR Filing Access, unless earlier
revoked by the undersigned in a signed writing delivered to the foregoing
attorneys-in-fact.

     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed this 5th day of January, 2017.

                                        /s/ Oern Stuge
                                        ----------------------------------------
                                        Oern Stuge