A University of Iowa labor expert says unions appear to be on the upswing this Labor Day. Laurence Clements is the director of the U-of-I Labor Center. He says last year was the biggest net growth in trade union membership in the last decade.Clements credits the union revival to a concentrated recruitment effort — and worker dissatisfaction with what’s being offered by employers.Clements says unions not only help workers, but they still carry a lot of influence in politics.In Iowa, Clements says the unions are still riding high from the election of Democrat Governor Tom Vilsack and will try to build on that this fall.The U-of-I Labor Center teaches labor law and other labor issues. The Center is celebrating its 50th anniversary this year.