my $dom = XML::LibXML->new->parse_file($file);
     my $study_str = 'Purpose and rationale|Study purpose|Study rationale'
    for my $search ('/root/part/sect/header') {
        my $nodeset = $dom->find($search);
    foreach my $node($nodeset -> get_nodelist)
    {
        $node -> string_value;

        if ($node =~ m/$study_str/i)
        {
          my $protocol = $node;
          print $protocol,"\n";
         #go to the next sibling
         while ($node -> { Node }) {
        if ($node -> { Node } -> getNextSibling ) {
         $node -> { Node } = $node -> getNextSibling;
        return $node -> { Node };
        }
        }
        }
}
}