An acoustic transducer comprising: a mechanical acoustic filter configured to be electrically controllable to change the acoustic properties of the transducer. The relative concentration defined by log P\u2212log S are obtained from the fluorescent spectra, where P is the peak height for the element and S is the background height. The anchor peg has a first end portion and a second end portion with the first end portion of the anchor peg being secured to the first surface of the body portion, and the second end portion of the anchor peg having a number of fins secured thereto. The method also includes determining a logical structure for each layer. A controller is configured to calculate a time rate of change of the target braking force; to calculate a time rate of change of the demand braking force; and to calculate the command braking force in the control mode in accordance with the time rate of change of the demand braking force and the time rate of change of the target braking force. The controller calculates an image density difference between the density detection patterns on a basis of a detection result obtained by the detector, and corrects a transfer bias for transferring a toner image on a basis of a value of the image density difference.