function filter_news()
{
	var categories = '';	
	var subject = document.getElementyById('thema');
	//weiter Medientypen
	var mediaType = document.getElementyById('medienTyp');
	var author = document.getElementyByID=('author');
	
	categories = subject + ',' + mediaType + ',' + author;
	
	//neue URL zusammenbauen	
	window.location = document.getElementById('filter-formular').action +
		'?no_cache=1&categories=' + categories;
}