This invention relates to novel compounds having the structural formula I below:and their pharmaceutically acceptable salts, tautomers or in vivo-hydrolysable precursors, compositions and methods of use thereof. A lower control arm having first and second opposing portions is pivotally connected to the frame at the first portion. An actuator is disposed between the two end walls and functions as a portion of a common end wall of the two cavities. Radio frequency interference levels between the nodes in the mesh network are measured and channels or PN codes of nodes having interference levels greater than a predetermined amount are changed.