A remark on Brans-Dicke cosmological dust solutions with negative ω

Analysing the Brans-Dicke solutions for the dust phase, we show that, for negative values of omega, they contain scenarios that display an initial subluminal expansion followed by an inflationary phase. This is due to a repulsive cosmic effect. We discuss these solutions with respect to the results of the observation of high redshift supernova as well as the age problem and structure formation. We establish possible connections of these solutions with those emerging from string effective models.