The article isn't great, but they do link to an interesting paper on the subject: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0156279 http:

The article isn't great, but they do link to an interesting paper on the subject: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0156279 http://journals.plos.org/plosone/article?id=10.1371/journal....