public function filterByActivated($activated = null, $comparison = null)
    {
        if (is_string($activated)) {
            $activated = in_array(strtolower($activated), array('false', 'off', '-', 'no', 'n', '0', '')) ? false : true;
        }

        return $this->addUsingAlias(UserPeer::ACTIVATED, $activated, $comparison);
    }