Periodic negative magnetoresistance in granular YBa2Cu3O7−δ nanowires D. Levi, A. Shaulov, A. Frydman, G. Koren, B. Ya. Shapiro and Y. Yeshurun EPL, 101 6 (2013) 67005 Published online: 03 April 2013 DOI: 10.1209/0295-5075/101/67005