A method is disclosed from constructing a grammar. The invention provides isolated nucleic acid molecules encoding human VR2 receptors. Advantageously, the controller allows the metal-air battery to limit the intake of oxygen and other gases to that amount needed to drive the load. The logic circuit is coupled to the data memory and provides a memory interface for exporting the pixel data. Water or air is injected from the backwashing pipe to agitate and blow upward from the surface layer living organisms or sediments trapped in intermediate layers of the sand filtration layer, and the agitated water is sucked in by a suction pipe and recovered.