Nowadays, this doctoral programme has been quality accredited by the Ministry of Educacion and Science, valid for the next four academic years, from 2007-2008 to 2010-2011 (Resolution of MEC on 19/09/2007). The Quality Certification constitutes a recognition for the scientific-technical and educational solvency of the whole programme and of the groups or departments which develope the doctoral training. This certification is not only a referent of quality guarantee but it gives access to national programmes of grants and the Highest Education and Scientific Research promotion.