sentences:  In 1982 he was appointed the position of Professor of Sociology at the University of Uppsala, which he held until 2002 after which he became Emeritus Professor.Back in the United States he was also Clarence J. Robinson University Professor at the George Mason University from 1987 to 1990.From 2003 to 2006 he was NORFA Professor at the Centre for International Environment and Development Studies Nof theorwegian University of Life Sciences.