1. GENERALIZED RESULT ON THE GLOBAL EXISTENCE OF POSITIVE SOLUTIONS FOR A PARABOLIC REACTION DIFFUSION MODEL WITH A FULL DIFFUSION MATRIX. Authors: NABILA BARROUK, SALIM MESBAHI.2. INVARIANT REGIONS AND GLOBAL EXISTENCE OF UNIQUENESS WEAK SOLUTIONS FOR TRIDIAGONAL REACTION-DIFFUSION SYSTEMS. Authors: NABILA BARROUK, KARIMA ABDELMALEK, MOUNIR REDJOUH.