1. Macroeconomics, Department of Economics; University of Duisburg-Essen; D-45117 Essen Germany
2. Ruhr University of Bochum; Germany and Kiel Institute for the World Economy; Germany
3. Chemnitz University of Technology; Germany
4. Department of Economics; University of Duisburg-Essen; Germany and FOM Hochschule für Oekonomie & Management, University of Applied Sciences, Essen, Germany