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© 2016 SECV. Published by Elsevier Espan˜ a, S.L.U. This is an open access article under the
CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Except where otherwise noted, this item's license is described as © 2016 SECV. Published by Elsevier Espan˜ a, S.L.U. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).