A pair of thrust hydrodynamic bearing portions are made to communicate with each other to form fluid circulating passages for equalizing a pressure imbalance between both thrust hydrodynamic bearing portions. The invention also includes semiconductor structures having two doped regions of a semiconductive material separated by a region less heavily doped than the doped regions. A thermal energy beam is directed onto the first doped region of the wide bandgap semiconductor material in the presence of a doping gas for converting a portion of the first doped region into a second doped region in the wide bandgap semiconductor material. The present invention is applicable to systems such as cdma2000, W-CDMA, and EDGE, wherein data is transferred using an ARQ mechanism, and wherein data packets are sometimes received in an order different from that in which they were transmitted. The ratio of the content of the alkali metal element to the sum of the content of the bismuth plus the content of the rare earth element, is preferably from 1. The lens body includes a lens first surface that has two convex portions or two concave portions that extend in parallel to each other in a constant direction and have the same shape, and a lens second surface.