Evolutionary changes in the periods of galactic RRab stars
  Le Borgne et al. (2007) report on the determination of evolutionary changes in the periods of field RR Lyr stars. Thanks to the extension of the GEOS database, we could analyze a sample twice larger than the previous one. We obtained a different picture of the period changes, with a number of stars showing an increasing period greater than that of stars showing a decreasing period. 
Jacqueline Vandenbroere, Ennio Poretti, and Jean-Francois Le Borgne
astro-ph.SR