public function findUserGroups()
    {
        if ( null === $this->userGroups )
        {
            $this->userGroups = array();

            $select = $this->sql( 'user_group' )
                           ->select()
                           ->columns( array( 'id', 'name' ) );

            /* @var $result \Zend\Db\Adapter\Driver\ResultInterface */
            $result = $this->sql()
                           ->prepareStatementForSqlObject( $select )
                           ->execute();

            foreach ( $result as $row )
            {
                $this->userGroups[$row['id']] = $row['name'];
            }
        }

        return $this->userGroups;
    }