How did the advanced search change?

Bookshare recently implemented a small change to our advanced search.  Traditionally when checking multiple categories all books that appear in any of those categories would be given as search results, even if they only appeared in one of the selected categories.  

Now when checking multiple categories on the advanced search only books that appear in all checked categories will appear in the search results.  We hope this small change makes our advanced search much more useful for our members.