  In this short note I give an alternative proof of a generalization of the
result in math.AC/0407464. Namely I show that for most regular rings R, the
localization R[1/f] at an element f of R is generated as a module over the ring
of differential operators of R by 1/f itself. Due to the greater generality
this answers some questions raised in math.AC/0407464. Some further
generalizations and a brief discussion of the main technique (Frobenius
descent) are also included.
