In many processes used in fabricating semiconductors the wafer is seated on the top surface of a pedestal and heated in a high energy process step, such as plasma etching. The methods include obtaining a bone marrow sample from a human donor, isolating stromal cells from the bone marrow sample, and administering the isolated stromal cells to the central nervous system of the human patient, wherein the presence of the isolated stromal cells in the brain effects treatment of the disease, disorder or condition. A flexible drive shaft powers the cutting reel from the gearbox and is made from materials that do not require petroleum based lubricants to avoid the possibility of damage to the turf or grass. Hereto, the coating agent is extensible in wet state and comprises thereto a wet-extensible material that has a wet-elongation of at least 400%, or even more preferably at least 500%, and preferably a tensile stress at break in the wet state of at least 1 MPa. A piston is received within and is axially movable relative to the valve seat so as to open and close the one or more apertures and thereby regulate exhaust gas flow between the intake and exhaust ports.