A time-of-arrival estimation method for multi-band orthogonal frequency division multiplexing signals uses a simple equally-spaced channel model to recover the impulse response of the wireless channel, and locates the delay of the first channel path by minimizing the energy leakage from the first channel path. In particular, the polypeptides and polynucleotides of the invention comprise amino acid and nucleic acid sequences of novel CD39-like gene and gene products. The plurality of compressors is arranged in series to sequentially compress the CO2 gas exhausted from the tower. One of the channel grooves is a straight groove passing through the rotational center of the rotor, and the other channel grooves are line-symmetrically arranged with respect to the straight channel groove. 0\xd71016 atomscm2 onto the oxide layer in a given region, and wet-etching the oxide layer in the remaining region where the boron ions are not implanted. In chip formation, a search and optimization algorithm explores, in a clock-less environment, various route lengths and connections such that the chip can behave in a desired fashion to provide a desired output for a given input.