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POPSThinking ahead: Bacteria anticipate coming changes in their environment To test this idea, the researchers exposed a population of E. coli to different temperatures and oxygen changes, and measured the gene responses in each case. The results were striking: An increase in temperature had nearly the same effect on the bacterium's genes as a decrease in oxygen level. Indeed, upon transition to a higher temperature, many of the genes essential for aerobic respiration were practically turned off. To prove that this is not just genetic coincidence, the researchers then grew the bacteria in a biologically flipped environment where oxygen levels rose following an increase in temperature. Remarkably, within a few hundred generations the bugs partially adapted to this new regime, and no longer turned off the genes for aerobic respiration when the temperature rose.
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POPS3-D Viewing without Goofy Glasses As with earlier techniques, the illusion requires specially-created content to start with. In this case, a digital movie file effectively has two frames for each ordinary movie frame. The first is an ordinary color image, identical to what would be seen on a two-dimensional screen. A second frame, rather than showing a second offset view, encodes information about how viewers should perceive depth in the first frame. It appears as a grayscale version of the first, with white indicating foreground objects, black denoting deep background, and shades of gray indicating points in between.
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POPSNASA Plans to Visit the Sun The two mysteries prompting this mission are the high temperature of the sun's corona and the puzzling acceleration of the solar wind: Mystery #1—the corona: If you stuck a thermometer in the surface of the sun, it would read about 6000o C. Intuition says the temperature should drop as you back away; instead, it rises. The sun's outer atmosphere, the corona, registers more than a million degrees Celsius, hundreds of times hotter than the star below. This high temperature remains a mystery more than 60 years after it was first measured. Mystery #2—the solar wind: The sun spews a hot, million mph wind of charged particles throughout the solar system. Planets, comets, asteroids—they all feel it. Curiously, there is no organized wind close to the sun's surface, yet out among the planets there blows a veritable gale. Somewhere in between, some unknown agent gives the solar wind its great velocity. The question is, what?
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POPSTiger Pictures Siberian tigers are among the world's most endangered species. They are estimated to number less than 500 in the wild. In about 100 years only a dozen white tigers have been seen in the wild in India. Other Photos at the website include: A 26-day-old endangered Sumatran tiger cub cuddles up to a 5-month-old female orangutan One of Australia's only two 'tigons,' a man-made hybrid created by crossing a male tiger with a lioness, licks its lips at the National Zoo. Bearing the stripes of a tiger and the physique of a lioness, tigons are usually infertile. An Indian Bengal Tiger (Panthera tigris) walks in a pool at a zoo
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POPSBefore the beginning of the universe Alan Guth of MIT, who first proposed the inflation theory nearly three decades ago, says he suspects “the reported lopsidedness will more likely turn out to be a fluke.” However, he adds, “the concept of inflation is really only the framework of a theory, and so far experiment has given us very little guidance in trying to fill in the details.
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