The invention relates to a comparator with a constant duty cycle for high frequency data signals. Moreover, the present invention provides a method for manufacturing the organic EL device and an organic EL display apparatus. A method of compacting a work area may include determining a work material compaction response associated with at least one region of the work area is aberrant, and maneuvering the compactor machine within the work area responsive to a signal associated with the aberrant compaction response. Further, the call over network quality may further be improved by deploying modules over the network. In another example, the LPD may be configured to deliver post-shock pacing after detecting delivery of anti-tachyarrhythmia shock therapy. The method comprises heating the metal mixture to vaporize the metal; condensing the metal contaminants present in the vapour; reacting any contaminants remaining in the vapour with a reagent to precipitate the remaining contaminants, and collecting the purified metal.