2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/34399Singularity-free cosmological solutions may be obtained from the string action at tree level if the dimension of the space-time is greater than 10 and if brane configurations are taken into account. The behaviour of the dilaton field in this case is also regular. Asymptotically a radiative phase is attained indicating a smooth transition to the standard cosmological model.6 pages, latex fileGeneral Relativity and Quantum Cosmologytext