K Bedair1,2, A Elhadad3, S Hamad4, J Ferguson1, P Donnan5, R S Dawe1. 1. Photobiology Unit, Dermatology Department, University of Dundee, Dundee, DD1 9SY, UK. 2. Department of Statistics and Mathematics, Faculty of Commerce, Tanta University, Tanta, 31521, Egypt. 3. Department of Mathematics and Computer Science, Faculty of Science, South Valley University, Qena, 83523, Egypt. 4. Department of Scientific Computing, Faculty of Computer and Information Sciences, Ain Shams University, Cairo, 11566, Egypt. 5. Department of Population Health Sciences and Medical Research Unit, School of Medicine, University of Dundee, Dundee, DD1 9SY, UK.