The present invention relates to compounds of formula I:wherein A, X, R1, R2 and R3 are as defined herein and pharmaceutically acceptable salts thereof. The audio signal is divided into a number of frequency domain input signals. The fabricating or manufacturing microelectromechanical systems of the present invention, and the systems manufactured thereby, employ wafer bonding encapsulation techniques. A molded article or substrate is provided with a removable in-mold coating containment flange which extends completely around the perimeter of a surface to be coated in order to substantially contain the in-mold coating within the mold cavity and on the desired area of a part before the coating has been cured. Respiratory airflow estimation data are then calculated for each bin and an entry for each bin associating the discrete range and the estimation data is stored in a lookup table. The tunable light source may include a polarization rotator to rotate a pump beam before a first pass through an OPG, and a linear-to-circular polarization device to polarize the pump beam directed back toward the OPG for a second pass therethrough.