Electrical test instruments and systems provider !%Keithley Instruments Inc.%! of Cleveland has completed a merger with Aegean Acquisition Corp., an indirect wholly owned subsidiary of Danaher Corp. Under terms of the merger, all outstanding common shares and class B common shares of Keithley Instruments have been converted into the right to receive $21.60 per share, in cash, without interest. Now an indirect wholly owned subsidiary of Danaher, Keithley will not trade its shares on the New York Stock Exchange.