Jukka-Pekka Onnela 1,2 Jari Sramaki 1 Jorkki Hyvonen 1 Gabor Szabo 3,4 M. Argollo de Menezes 3 Kimmo kaski 1 Albert-Laszlo Barabasi 3,4 Janos Kertesz 1,5 1 Laboratoryof Computational Engineering, Helsinki Universityof Technology, Finland 2 ClarendonLaboratory, PhysicsDepartment, OxfordUniversity, Oxford, U.K 3 Departmentof PhysicsandCenterforComplexNetworksResearch, University of NotreDame, IN, US