1. Department of Physics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
2. Center for Soft Matter and Biological Physics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
3. Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg SE-412 96, Sweden
4. Department of Physics, University of Gothenburg, Universitetsplatsen 1, Gothenburg 405 30, Sweden
5. Centre for Molecular Medicine Norway, Faculty of Medicine, University of Oslo, 0318 Oslo, Norway