Spectral models of stellar populations resolved in chemical abundances
  We present model spectra of stellar populations with variable chemical
composition. We derived the [alpha/Fe] abundance ratio of the stars of the most
important libraries (ELODIE, CFLIB and MILES) using full spectrum fitting and
we generated PEGASE.HR models resolved in [\alpha/Fe]. We used a semi-empirical
approach that combines the observed spectra with synthetic stellar spectra. We
tested the models using them to derive [\alpha/Fe] in galaxies and star
clusters using full spectrum fitting. The present models are available from
http://ulyss.univ-lyon1.fr
