public function negativeRelativeDateFilter($field, $fromUnit = self::RELATIVE_DATE_FILTER_UNIT_MINUTES, $fromInterval, $toUnit = self::RELATIVE_DATE_FILTER_UNIT_MINUTES, $toInterval = 0, $dateFormat = self::RELATIVE_DATE_FILTER_DATEFORMAT, $isNegative = false) {
        return $this->relativeDateFilter($field, $fromUnit, $fromInterval, $toUnit, $toInterval, $dateFormat, true);	    
	}