Spatially induced groups of automorphisms of certain von Neumann algebras

This paper gives an affirmative solution, in a large number of cases, to the following problem. Let $\mathcal{R}$ be a von Neumann algebra on the Hilbert space $\mathcal{H}$, let G be a topological group, and let $a \to \varphi (a)$ be a homomorphism of G into the group of $^ \ast$-automorphisms of $\mathcal{R}$. Does there exist a strongly continuous unitary representation $a \to U(a)$ of G on $\mathcal{H}$ such that each $U(a)$ induces $\varphi (a)$?