Accordign to a report from Scripps Howard News Service, a paper appearing in the Journal of Human Reproduction today warns of potential dangers from using a laptop computer on your lap. The culprit is a simple one-- Heat! The study shows that testicular temperatures rose between 4.6 and 5 degrees F in an hour among a group of healthy male volunteers using laptop computers on their lap. "Laptops can reach internal operating temperatures of over 158 degrees (surface temperatures of 104 degrees), they are frequently positioned close to the scrotum and as well as being capable of producing local heat, they require the user to sit with the thighs close together to balance the machine," said Dr. Yefim Shenykin, associate professor of urology and Director of Male Infertility and Microsurgery at the State University of NY Stony Brook. Studies have shown that increses in testicular temperature between 1.8 and 5.2 degrees have a substantial negative effect on sperm development and fertility, according to the news item.