Sheila Stepanek has resigned from Partizan. Stepanek, who had been with the company for four and a half years, had occupied the role of executive producer out of L.A., managing the company with Maya Brewster. ... Ira Matathia has joined TAXI New York as VP of development and integrated strategy director. ... Tim O’Kennedy has joined Wieden + Kennedy/Amsterdam managing director. ... davidandgoliath today announced the hire of Jill Pool as the agency’s new Creative Services Manager. ... Troika Design Group has named Robert E. Blatchford director of business development. ... MRB Productions has signed Director/DP Gary Califano for exclusive commercial representation.