/**
* get the top concepts for a vocabulary
*
* @return void
* @param Vocabulary $vocabulary
*/
function getTopConcepts($vocabulary, $ts = null)
{
//get top concepts for vocabulary
$c = new Criteria();
$c->add(ConceptPeer::IS_TOP_CONCEPT, 1);
$this->topConcepts = $vocabulary->getConcepts($c);
return;
}