Northampton city officials are expressing disappointment at the loss of yet another school superintendent. Brian Salzer is resigning his position after two years to take a job as principal of the JFK International School in Berlin, Germany. Mayor David Narkewicz says he does not attribute the resignation to the flap over the anti-violence pledge at the high school. Salzer is expected to officially announce his resignation at Thursday's Northampton School Committee meeting. At that time, the board will start the process of finding his replacement.