[1] Queen Mary Univ London, London E1 4NS, England
[2] Kyushu Sangyo Univ, Fac Sci & Engn, Higashi Ku, 3-1 Matsukadai 2 Chome, Fukuoka, Fukuoka 8138503, Japan
[3] Hiroshima Inst Technol, Hiroshima 7315193, Japan
[4] Senshu Univ, Sch Commerce, Kawasaki, Kanagawa 2148580, Japan
[5] Babes Bolyai Univ, Fac Math & Comp Sci, 1 M Kogalniceanu Str, Cluj Napoca 400084, Romania