A method for the formation of a refractory metal nucleation layer on a semiconductor device substrate that includes first depositing a metallic barrier layer on the substrate. The shield may be extended out of the housing with two links and two racks and a motor. A series circuit of a switching element Sa1 and a diode Da3 is connected between a cathode of the diode Da1 and a cathode of the diode Da2. The type and nature of the information presented to the user can be changed according to the user’s distance from emergency services as well as how quickly the user is approaches the safe zones. The notches also function to maintain the film layer of cooling air over the blade tip longer than in the prior art without the notches.