$(function() {
    $('div.articles> div').hide();
    $('div.articles> h2').click(function() {
        var $nextDiv = $(this).next();
        var $visibleSiblings = $nextDiv.siblings('div:visible');
        if ($visibleSiblings.length ) {
            $visibleSiblings.slideUp('fast', function() {
                $nextDiv.slideToggle('fast');
            });
        } else {
            $nextDiv.slideToggle('fast');
        }
        return false;
    });
});