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