Affiliation: | Kenneth Thorsen,Jon Arne Sreide,Jan Terje Kvaly,Tom Glomsaker,Kjetil Sreide ,Department of Surgery,Stavanger University Hospital,N-4068 Stavanger,Norway,Department of Mathematics and Natural Science,University of Stavanger,4036 Stavanger,Norway,Department of Surgical Science,University of Bergen,5020 Bergen, Norway |