his head is separated from the rest of his aged, diseased body with a high speed surgical saw and transferred the fluid-filled receiving chamber of the revival unit. The fluid in the receiving chamber is tetrafluoromethane; a compound which is liquid even at -130øC. The revival unit appears a combination of living creature and inorganic machine. An Artificial Intelligence, its "brain" contains the sum of all human medical knowledge, which it keeps updated with its link to the worldwide medical information net. Connections are established between the patient's neck and the revival unit. Repairs begin. Countless millions of microscopic devices designed to operate at low temperatures begin to clear out ice from the patient's blood vessels. As they proceed, they assemble behind them fine fibers of electrically conductive polyacetylene which supply power to the ice removal devices. Later these fibers will serve as communications links as well. Once the circulatory system of the patient is free of ice, billions of nanocomputers (cell-sized computers) are moved into strategic positions along the network of conducting fibers. These interconnected computers will coordinate both short-range and long-range repair activities (such as repair of gross fractures). All these processes are carried out sufficiently slowly so that the patient's temperature does not rise significantly above -130øC: the tissues beyond his blood vessels remain virtually unchanged from the time of his suspension. New, more sophisticated devices, are introduced. Capillary walls are partially disassembled, and the devices begin to enter the inter-cellular spaces of the brain. These devices also remove ice, but much more carefully than the earlier ones. As ice crystals are disassembled at the molecular level, information concerning their position and orientation is transmitted back to supervising nanocomputers waiting in nearby blood vessels. When biological structures such as cell membranes or dendrite debris are encountered, they are carefully examined and tagged with special identifying molecules, and anchored to nearby cells if necessary. Their original position is also relayed back to the supervising computers and to the revival unit. ----------------------------------------------------------------------(36)
A week has now passed. Virtually all the ice has been removed from the patient's brain, and cryogenic fluid now freely circulates throughout the extracellular environment. The patient's temperature is now raised until the contents of his cells become a thick liquid (at about -100øC). Devices for the first time begin to enter cell interiors. Their purpose is to lock up metabolic machinery to prevent premature, uncoupled activity. Enzymes are physically bonded to cell structures, and their active sites are blocked by specially fabricated molecules until repairs are completed. Once cell interiors have been adequately stabilized, the tetrafluoromethane is replaced with another solvent, and the patient's temperature is raised above the freezing point of water. Trillions of repair devices are now deployed. In sizes ranging from that of large molecules to small cells, the devices take up strategic positions both inside and outside cells. Among these devices are nanocomputers which will now supervise repairs from inside cells. With the repair system now in essentially complete control of the patient's brain, the most sophisticated operations begin. Small devices examine molecules and report their structures to larger controlling