Earley, Joseph E.  "On Applying Whitehead's First Category of Existence."  Process Studies 11, no. 1 (Spring 1981): 35-9.

Abstract

A new interpretation is proposed for Whitehead's first category of existence (actual entity, actual occasion).  This category applies if, and to the extent that, all-or-none closure of a network of relationships provides a basis for discrimination of a unitary source of effective action.  This involves matching of the spatial and temporal scales of the defining network and of the percipient(s).  Relevance to the chemical theory of dissipative structure is indicated.  [Abstract from The Philosopher's Index]