An electrochemical fuel cell stack with improved reactant man folding and sealing includes a pair of separator plates interposed between adjacent membrane electrode assemblies. For that purpose, a threshold matrix is employed wherein the thresholds represent one or more raster dots of a raster arranged at an angle, the desired screen width and the desired angle being approximated therewith. A quantity of suture material is included in the meniscal repair device. The reduction in the step size or pulse duration, or the increase in Vbl, is proportional to N. By thus combining a plurality of delayed detections, it is possible to obtain a UWB demodulating apparatus configured with a circuit suited for integrated circuit fabrication.