Null-controllability of some systems of parabolic type by one control force Farid Ammar Khodja, Assia Benabdallah, Cédric Dupaix and Ilya Kostin ESAIM: COCV, 11 3 (2005) 426-448 Published online: 15 July 2005 DOI: 10.1051/cocv:2005013