Upon submitting an article, authors are asked to indicate their agreement to abide by an open access Creative Commons license (CC BY-NC 4.0). Authors retain the copyright Under the terms of this license. However, the license permits any user to download, print out, extract, reuse, archive, and distribute the article, so long as appropriate credit is given to the authors and the source of the work. The license ensures that the article will be available as widely as possible and that the article can be included in any scientific archive.all articles of all issues are open access & free to download without any limitation.