Lexicographic ordering is a pretty simple mathematical technique used to determine the best order a set of values should come in. It's most commonly used in libraries or dictionaries for arranging books and words, for instance, with the alphabet determining the order of the letters.
Murphy created two programs, LearnFun and PlayFun, and began recording himself playing the first level (world 1-1) of Super Mario Bros. The NES puts out 60 frames of 2048 bytes per second, and each of these was fed into LearnFun. Everything in the NES's memory—the buttons being pressed, the number of lives left, the score, the locations of enemies, Mario's position as coordinates, and so on—is taken in by the LearnFun algorithm.
Similar techniques have already been applied successfully in people with simpler tissue, such as windpipes. But the kidney is by far the most complex organ successfully recreated.
"If this technology can be scaled to human-size grafts, patients suffering from renal failure, who are currently waiting for donor kidneys, could theoretically receive an organ grown on demand," says Harald Ott, head of the team that developed the rat kidneys at the Massachusetts General Hospital in Boston.
The idea would be that traditional chemical rockets could deliver payloads to low Earth orbit and solar electric propulsion could then power a spacecraft to higher energy orbits, including Lagrange points or a potential assembly point in space between Earth and the moon. This approach could facilitate missions to near Earth asteroids and other destinations in deep space, NASA said.