Abstract: Provided herein are compounds of formula (1): or a stereoisomer or tautomer thereof, or a pharmaceutically acceptable salt of any of the foregoing, wherein X1, X2, Ry, Rz, R1, R2, R3, and R4 are as defined herein. Also provided herein is a pharmaceutically acceptable composition comprising a compound of formula (I), or a stereoisomer or tautomer thereof, or a pharmaceutically acceptable salt of any of the foregoing. Also provided herein are methods of using a compound of formula (I), or a stereoisomer or tautomer thereof, or a pharmaceutically acceptable salt of any of the foregoing, to treat various diseases, disorders, and conditions responsive to the modulation of the contractility of the skeletal sarcomere.

Abstract: Fittings configured primarily, although not necessarily exclusively, for connection to aircraft seat tracks are detailed. The fittings may engage multiple openings of a seat track concurrently. No rotation of a fitting need occur when connecting it to a track. Instead, if desired the fitting need move only linearly.