Authors who publish with this journal agree to the following terms:
Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
The journal is published under a Creative Commons Attribution-NonCommercial-NoDerivatives licence. This licence allows the content to be downloaded and shared with others, as long as attribution is credited to the original. The content may not be re-used commercially or altered in any way, including re-use of only extracts or parts. To view a copy of this licence,visithttp://creativecommons.org/licenses/by-nc-nd/3.0/.