Scalar Perturbations in a String Inspired Inflationary Scenario
  We consider an inflationary model inspired in the low energy limit of string theory. In this model, the scale factor grows exponentially with time. A perturbation study is performed, and we show that there is a mode which displays an exponential growth in the perturbation of the scalar field. 
C.E.M. Batista, J.C.Fabris