2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/190668We study a class of braneworlds where the cosmological evolution arises as the result of the movement of a three-brane in a five-dimensional static dilatonic bulk, with and without reflection symmetry. The resulting four-dimensional Friedmann equation includes a term which, for a certain range of the parameters, effectively works as a quintessence component, producing an acceleration of the universe at late times. Using current observations and bounds derived from big-bang nucleosynthesis we estimate the parameters that characterize the model.29 pages. LaTeX. 5 postscript figures included. v2 typos corrected and references added. Final version to appear in Phys.Rev.DHigh Energy Physics - TheoryAstrophysicsGeneral Relativity and Quantum Cosmologytext