Images Dated 29th November 2005

Shared DNA in humans and chimps, art

Shared DNA between humans and chimps, conceptual artwork. The humans look surprised to see the chimp so close to them in the double helix of DNA (deoxyribonucleic acid). Humans and chimps, our closest relatives, share around 99% of their DNA. It is thought that the common ancestor of humans and chimps lived as recently as five million years ago

© BILL SANDERSON/SCIENCE PHOTO LIBRARY

Liver blood supply, SEM

Liver blood supply. Coloured scanning electron micrograph (SEM) of several capillaries running through liver tissue. The functions of the liver include destroying old red blood cells, breaking down harmful waste products and toxins in the blood, and extracting useful nutrients from the blood to make and store proteins and other useful chemicals. Numerous capillaries, veins and arteries supply and remove blood. The structure of the liver tissue allows the blood to percolate through the tissue. At any one moment, the liver holds over 10 percent of the body's blood supply

© SUSUMU NISHINAGA/SCIENCE PHOTO LIBRARY

James Clark Maxwell with his demon

James Clark Maxwell and his demon, artwork. Maxwell (1831-1879) is best known for his laws of electromagnetism, which laid the foundations for modern physics. His "demon" was a thought experiment to question the Second Law of Thermodynamics: the entropy of a system tends to increase. This means that a hot region cannot draw heat from a colder region. Maxwell's demon is a being that can operate a door between a hot and cold gas, opening it to allow a fast-moving (hot) molecule to pass to the hot side, or a slow- moving one to pass to the cold side. This would violate the second law. However, as the demon requires energy to distinguish between fast and slow approaching molecules, and to operate the door, the entropy of the system increases anyway

© BILL SANDERSON/SCIENCE PHOTO LIBRARY