Provided herein are compounds of the formula :as well as pharmaceutically acceptable salts thereof, wherein the substituents are as those disclosed in the specification. In one embodiment system and method includes a reactor having a molten pool of a material comprising sodium carbonate. Additionally, the architecture provides the ability to compute animation positions and redraw entirely on the GPU without per primitive CPU intervention. The variable resistor body is contacted to an upper electrode at a surface different from a contact surface to the bump electrode material.