The present invention provides compounds of Formula :or a stereoisomer or pharmaceutically acceptable salt or hydrate form thereof, wherein the variables A, B, L1, L2, X1, X2, X3, X4 and W are as defined herein. Continuous adaptive digital to analog control may also include converting the error value into a digital pulse time value representing a correction to compensate for the error value. A probe packet comprising a departure timestamp, Ts, may be transmitted from the source node to the destination node based on receiving one or more congestion notification frames. The automation is made based on oxygen sensors and on sulfur and SO2 flow meters with their respective control connections and proportional valves permitting a fine control of the sulfur combustion reaction. The waveforms have parameters selected to block propagation of neural action potentials. The armature includes a magnetic slug.