(N+1)-dimensional Lorentzian evolving wormholes supported by polytropic matter Mauricio Cataldo, Fernanda Aróstica and Sebastian Bahamonde Eur. Phys. J. C, 73 8 (2013) 2517 Published online: 09 August 2013 DOI: 10.1140/epjc/s10052-013-2517-4