Open Access
Research Article
Volume 23, 2016
Article Number 7
Number of page(s) 10
Published online 22 February 2016

© M. Valan et al., published by EDP Sciences, 2016

Licence Creative Commons
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.