public function isNew($new = null)
    {
        if ($new === null) {
            return $this->_new;
        }

        $new = (bool)$new;

        if ($new) {
            foreach ($this->_properties as $k => $p) {
                $this->_dirty[$k] = true;
            }
        }

        return $this->_new = $new;
    }