Effect algebras are the Eilenberg-Moore category for the Kalmbach monad
  The Kalmbach monad is the monad that arises from the free-forgetful adjunction between bounded posets and orthomodular posets. We prove that the category of effect algebras is isomorphic to the Eilenberg-Moore category for the Kalmbach monad. 
Gejza Jen\v{c}a
math.RA