Competing interest
There was no conflict of interest to be stated.
Authors’ contributions
SRS wrote the first draft of the article and performed intensive review of
literature. PSS edited the article continuously. JR read and approved the final
manuscript. All authors read and approved the final manuscript.
Funding
No sources of support provided.
Received: 22 January 2013 Accepted: 28 February 2013
Published: 5 March 2013