Members of Yale’s clerical and technical union, Local 34, unveiled a petition Wednesday to stress further dialogue with University administrators in these troubling economic times as the two parties quickly approach negotiations for a new contract next year. With new worries about worker conditions — and possible layoffs — Local 34 members reaffirmed their commitment to talking with the University. Yale unions spokesman Evan Cobb said the petition was signed by about 85 percent of the 3,300-person union.