Notes, Comments and Preliminary results Apr 22 2010 Essahbi Essaadi and Mohamed Boutahar   A Measure of Variability in Comovement for Economic Variables: a Time-Varying Coherence Function Approach   Abstract  Contact Information  Citation  Full Text  -  Preliminary Result   Jan 11 2010 Marcel Aloy , Mohamed Boutahar , Karine Gente and Anne Péguin-feissolle   Fractional integration and cointegration in stock prices and exchange rates   Abstract  Contact Information  Citation  Full Text  -  Note