Findings

Science  06 May 2011:
Vol. 332, Issue 6030, pp. 648
  1. First Stars Were Spinning Tops

    The first stars, which were up to hundreds of times bigger than the sun, were also whirling at incredible speeds, suggests a new study.

    Consisting of hydrogen and helium, these early stars burned out by the time the universe was 1 billion years old. But they produced heavier elements that, after their death, were incorporated into new stars. To gather clues about the first generation, a team led by Cristina Chiappini of the Leibniz Institute for Astrophysics in Potsdam, Germany, looked at a member of the second: stars from a 12-billion-year-old Milky Way cluster named NGC 6522.

    A simulation of a fast-spinning early star.

    CREDIT: ADAPTED FROM A. STACY ET AL., MNRAS, 413 (2011)

    The stars' spectra indicated high abundances of the heavy elements strontium and yttrium, which rotating stars can create at high rates. To produce the ratios seen in this cluster, an ancestor star would have to be spinning at 500 km per second, Chiappini and her colleagues reported online last week in Nature. That's 250 times as fast as the sun.

    If the first stars were indeed rapid spinners, they probably went out with a high-energy bang known as a Gamma Ray Burst. These flashes can be seen much farther away than individual stars. That augurs well for astronomers hoping to watch the first stars in the act of dying. http://scim.ag/spin-stars

  2. Computer Algorithm May Speed Drug Discovery

    In 2007, researchers noticed that the anti-HIV drug nelfinavir, developed in the 1990s, also reduced tumors. Now scientists say they've figured out how nelfinavir works its double magic. The finding could open up a new route for drug discovery.

    Pharmacologist Philip Bourne of the University of California, San Diego, and colleagues used a structure-based algorithm to find all the proteins to which nelfinavir might bind, 92 in all. Most were protein kinases, which have been linked to tumor growth because they can speed up cell division. Their shapes' similarity to HIV enzymes allowed nelfinavir to bind and disrupt them. And because improper kinase activity strongly dampens the signals that tell the tumor cell to divide, nelfinavir's weak action against many kinases shrank tumors.

    This computational approach can be used to identify numerous drug targets more cheaply and easily than traditional experimental methods, the researchers reported 28 April in PLoS Computational Biology. Selecting one enzyme and screening libraries of drugs for one that targets it is laborious, says Bourne; computation can save time and money. And with pipelines for drug discovery running dry, searching for substances that weakly interact with many targets provides a welcome fresh strategy for finding effective drugs, say other researchers. http://scim.ag/drug-discovery

  3. At Long Last, Gravity Probe B Satellite Proves Einstein Right

    Fifty years after it was conceived, a $760 million NASA spacecraft has confirmed general relativity, Einstein's theory of gravity, albeit less precisely than hoped. Gravity Probe B circled Earth from pole to pole for 15 months starting 20 April 2004 and used gyroscopes to measure two aspects of general relativity, which states that gravity arises when mass bends space and time. The satellite confirmed to 0.25% precision the geodetic effect in which the circumference of a circle around Earth is slightly shorter than 2π times the circle's radius, researchers reported this week at NASA headquarters in Washington, D.C. It also confirmed to 20% precision the frame-dragging effect, in which the rotating Earth twists spacetime much as turning a heavy bowl twists a table cloth beneath it. In 2004, a team from Italy reported a similar result.

    Researchers aimed to measure frame dragging to 1% precision, but were thwarted by electrostatic imperfections in the gyroscopes—rapidly spinning, almost perfectly round quartz spheres covered in superconducting niobium. Just to reach 20% precision, they spent 5 years figuring out how to correct for the slight tugs caused by those imperfections, says Francis Everitt, a physicist at Stanford University in Palo Alto, California.

    CREDIT: NASA

    But the experiment's full value goes beyond the results, Everitt says: “Just the element of challenge, the element of invention in it” made it worthwhile.

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