<http://schema.org/image_url>
"http://media.nola.com/politics/photo/flu-shotjpg-e5f1b4d651efa238.jpg"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.nola.com/politics/index.ssf/2009/10/obama_declares_swine_flu_a_nat.html>