Hasse Fredriksson is professor in the casting of metals in the Department of Materials Science at KTH, Royal Institute of Technology, in Stockholm, (Sweden). He was educated at KTH gaining a Master of Science in 1966 and he received his doctorate of science in 1971 in physical metallurgy. Since 1975, he has been responsible for research and education in the field of casting and solidification of metals at KTH. The aim of the research in the group is to experimentally, theoretically and/or numerically describe solidification processes. The group has published over 200 international scientific papers. Dr Ulla Akerlind is Docent in Physics at the University of Stockholm. She has extensive experience of teaching at university level and writing textbooks at university and college level. Dr Akerlind has been a guest lecturer on summer courses in physics in the US and an exchange teacher in physics at the University of Surrey in 1984.