[1] Univ Paris Est, Lab Anal & Math Appl, F-77454 Marne La Vallee 2, France
[2] Johannes Kepler Univ Linz, Inst Anal, Altenbergerstr 69, A-4040 Linz, Austria
[3] Univ Alberta, Dept Math & Stat Sci, Edmonton, AB T6G 2G1, Canada
[4] Univ Hull, Dept Math, Cottingham Rd, Kingston Upon Hull HU6 7RX, N Humberside, England