On quasi-Baer modules

Let R be a ring, be an endomorphism of R and MR be a -rigid module. A module MR is called quasi-Baer if the right annihilator of a principal submodule of R is generated by an idempotent. It is shown that an R-module MR is a quasi-Baer module if and only if M[x] is a quasi-Baer module over the skew power series ring R[x; ].