Five-dimensional solutions for the modified Einstein-Hilbert lagrangian

We find five-dimensional solutions to the equations of motion developed by Henriques. These equations are associated with the Einstein-Hubert lagrangian as modified in order to model the low-energy limit of some superstring theories. We look at extensions of both Friedmann-Robertson-Walker and Kasner models and find a large variety of behavior for both vacuum and matter-filled cases. In the case of the Kasner extension we find that the generalized Einstein equations do not admit analytic power-law solutions.