1. Department of Health Research, SINTEF Technology and Society, Trondheim, Norway,
2. Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
3. Department of Health Research, SINTEF Technology and Society, Trondheim, Norway
4. Department of Lung Medicine, St Olavs Hospital, Trondheim, Norway, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway