Process for the preparation of acetylene from hydrocarbons by partial oxidation, arc cleavage or pyrolysis, the material stream comprising the acetylene and soot obtained being fed to a compressor, wherein a liquid which takes up the major part of the soot present in the material stream is sprayed into the compressor. The method includes providing a magnetic recording channel, reading and digitizing a stored signal, introducing an error signal that emulates off-track interference, adding the error to the digitized signal, and determining an error rate. Other aspects of the invention include vectors containing processes for producing novel human secreted semaphorin-like polypeptides, and antibodies specific for such polypeptides. Each FBAR has opposed planar electrodes and a piezoelectric element between the electrodes. When power boost is enabled, the controller will increase maximum power limits to above normal levels, so that, for example, the desired road or transport speed can be maintained as the vehicle goes up a hill. The foam shows improved capability to resist collapse during any subsequent handling, drying to greenware, or firing steps.