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Study Shows How Defective DNA Repair Triggers 2 Neurological Diseases


PhysOrg
Thu, 15 Jan 2009 13:00 UTC
Scientists at St. Jude Children's Research Hospital have teased apart the biological details distinguishing two related neurological diseases - ataxia telangiectasia-like disease (ATLD) and Nijmegen breakage syndrome (NBS).

Both disorders arise from defects in a central component of the cell's machinery that repairs damaged DNA, but each disease presents with distinct pathologies. Defects in DNA repair dramatically increase the risk of cancer, which is found in NBS. However, NBS is also characterized by the occurrence of small brain size, or microcephaly, while in contrast, ATLD causes predominantly neurodegeneration.

The research involved the use of mouse models of each the diseases to analyze how the gene defects in ATLD and NBS give rise to the different pathologies. The researchers published their findings in the Jan.15, 2009, issue of the journal Genes & Development.
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Sun

Exoplanet Atmospheres Detected from Earth for the First Time


PhysOrg
Wed, 14 Jan 2009 20:02 UTC
Star
© D. Sing (IAP) / A&AThis is an artist's impression of the star OGLE-TR-56 and its planet, as the planet is passing behind the star.
Transiting exoplanets are routinely detected when they pass in front of their parent star as viewed from the Earth, which only happens by chance. The transit event causes a small drop in the observed starlight, which can then be detected. Fifty-five exoplanets have been detected this way since the observation of the first transiting planet HD 209458 b in 1999.

When the planet revolves around its star or when it goes behind, the light coming from the system also varies, though the resulting smaller modulation is much harder to detect. This is mostly due to the small amount of light emitted by these exoplanets which are believed to be as dark as coal and reflect little of the incoming starlight. Fortunately, some of these planets are very hot, thus emitting light, mostly at infrared wavelengths. Up to now, detections of this kind have only been made using the Spitzer infrared space telescope.

This week, Astronomy & Astrophysics is publishing the two first ground-based detections of thermal emission from transiting, hot-Jupiter exoplanets, from two independent teams of astronomers that used different approaches.
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Laptop

Internet Growth Follows Moore's Law


PhysOrg
Wed, 14 Jan 2009 18:37 UTC
Map
© Internet Mapping Project, Bell Labs/Lumeta CorporationInternet map as of 16th January.
Originally, Moore's Law described the number of transistors that can fit on an integrated circuit, which doubles approximately every 18 months. Now, a team of researchers from China has discovered that Moore's Law can also describe the growth of the Internet. In a recent study, the researchers have predicted that the Internet will double in size every 5.32 years.

That finding is one of several results from the study published by Guo-Qing Zhang, et al., in a recent issue of the New Journal of Physics. The researchers investigated the evolution of large-scale Internet topology, or how the Internet is structured and connected. Based on routing data of six-month intervals from December 2001 to December 2006, the researchers predicted not only the Internet's exponential growth rate which follows Moore's Law, but also more specifically how the Internet evolves.

The study looked at the Internet not in terms of Web sites in the World Wide Web, but at the level of autonomous systems (AS). As Zhang explained, an AS, the unit of routing policy, is an administrative routing domain that can apply its own policy, which is a result of a mutual commercial agreement between autonomous systems. A university, an ISP, or a large company network can own an AS.
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Info

Possible Mammoth Tusk Found On Southern California Island

Alicia Chang
Associated Press
Wed, 14 Jan 2009 16:14 UTC
A complete tusk believed to belong to a prehistoric mammoth was uncovered on Santa Cruz Island off the Southern California coast, researchers reported Tuesday. If the discovery is confirmed, it would mean the tusked beasts roamed 62,000-acre Santa Cruz Island more widely than previously thought.

A graduate student at the University of California, Santa Barbara, came across the tusk while working in a canyon on the island's remote north shore earlier this month. Nearby were several rib bones and possible thigh bones, said Lotus Vermeer, the Nature Conservancy's Santa Cruz Island project director.

"We've never discovered mammoth remains in this particular location on this island before," Vermeer said.

The Nature Conservancy and a leading mammoth expert will excavate the remains next week and use radiocarbon dating to determine their age.
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Meteor

Two Newly Discovered Meteorites May Rewrite the Book On How Some Asteroids Form and Evolve


Media Newswire
Mon, 12 Jan 2009 16:11 UTC
The researchers hypothesize that that the asteroid had a diameter somewhat larger than 100 kilometers, which would be sufficient to hold enough heat for the asteroid's rocks to partially, but not completely, melt. The asteroid would remain undifferentiated, but the melted portions could erupt on the asteroid's surface to form the andesitic crust.

Asteroids are hunks of rock that orbit in the outer reaches of space, and scientists have generally assumed that their small size limited the types of rock that could form in their crusts. But two newly discovered meteorites may rewrite the book on how some asteroids form and evolve. Researchers from the Carnegie Institution, the University of Maryland, and the University of Tennessee report in the January 8th edition of Nature that these meteorites are ancient asteroid fragments consisting of feldspar-rich rock called andesite. Similar rocks were previously known only from Earth, making these samples the first of their kind from elsewhere in the Solar System.

The two meteorites were discovered during the Antarctic Search for Meteorites (ANSMET) 2006/2007 field season in a region of the Antarctic ice known as the Graves Nunatak icefield. The light-colored meteorites, designated GRA 06128 and GRA 06129, were immediately recognized as being different from previously known meteorites.
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Sherlock

New Archaeological Site Discovered in Egypt


Afrique en ligne
Wed, 14 Jan 2009 16:04 UTC
Egypt's Supreme Council of Antiquities (SCA) announced that a new archaeological site dating some 4,000 years has been discovered northeast of the capital, Cairo. According to Antiquities chief Zahi Hawass, the site dates back to the Middle Kingdom and was unearthed near the Ein el Sokhna resort, some 120 kilometers northeast of Cairo.

The discovery was made by a joint Egyptian-French archaeological mission, Hawass said.

He added that 9 storehouses and a rectangular building containing an ancient chamber were discovered at the site.
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Sherlock

Archaeologist Uncovers Evidence of Ancient Chemical Warfare


PhysOrg
Wed, 14 Jan 2009 14:11 UTC
A researcher from the University of Leicester has identified what looks to be the oldest archaeological evidence for chemical warfare - from Roman times.

At the meeting of the Archaeological Institute of America, University of Leicester archaeologist Simon James presented CSI-style arguments that about twenty Roman soldiers, found in a siege-mine at the city of Dura-Europos, Syria, met their deaths not as a result of sword or spear, but through asphyxiation.

Dura-Europos on the Euphrates was conquered by the Romans who installed a large garrison. Around AD 256, the city was subjected to a ferocious siege by an army from the powerful new Sasanian Persian empire. The dramatic story is told entirely from archaeological remains; no ancient text describes it. Excavations during the 1920s-30s, renewed in recent years, have resulted in spectacular and gruesome discoveries.
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Telescope

Stardust Scoots Pass Earth On Route For Comet Tempel 1


Space Daily
Wed, 14 Jan 2009 05:08 UTC
NASA's Stardust-NExT spacecraft
© NASAStardust-NExT on Its Way to Explore Comet Tempel 1.

On Jan. 14, NASA's Stardust-NExT spacecraft will fly by Earth during a gravity assist maneuver that will increase its velocity and sling shot the spacecraft into an orbit to meet up with comet Tempel 1 in February 2011. Flight operations for the spacecraft are performed from Lockheed Martin's Mission Support Area in Denver, Colo. The Jet Propulsion Laboratory in Pasadena, Calif. provides the precision navigation need for the flyby and the journey to Tempel 1.

The Lockheed Martin-built spacecraft's closest approach will happen at 12:33 p.m. MST as it comes within 5,690 miles (9,157 km) of Earth. At its closest point, the spacecraft will fly over the California/Mexico border south of San Diego at a speed of approximately 22,400 miles per hour (36,000 kilometer per hour).

"We performed our final trajectory correction maneuver on Jan. 5 that put us into a precise position for the flyby," said Allan Cheuvront, Stardust-NExT program manager at Lockheed Martin Space Systems Company.
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Telescope

XMM-Newton Measures Speedy Spin Of Rare Celestial Object


European Space Agency
Tue, 13 Jan 2009 21:32 UTC
SGR
© ESA/XMM-Newton/EPICFalse colour X-ray image of the sky region around SGR 1627-41 obtained with XMM-Newton. The emission indicated in red comes from the debris of an exploded massive star. It covers a region more extended than that previously deduced from radio observations, surrounding the SGR. This suggests that the exploded star was the magnetar’s progenitor.
XMM-Newton has caught the fading glow of a tiny celestial object, revealing its rotation rate for the first time. The new information confirms this particular object as one of an extremely rare class of stellar zombie - each one the dead heart of a star that refuses to die.

There are just five so-called Soft Gamma-ray Repeaters (SGRs) known, four in the Milky Way and one in our satellite galaxy, the Large Magellanic Cloud. Each is between 10 and 30 km across, yet contains about twice the mass of the Sun. Each one is the collapsed core of a large star that has exploded, collectively called neutron stars.

What sets the Soft Gamma-ray Repeaters apart from other neutron stars is that they possess magnetic fields that are up to 1000 times stronger. This has led astronomers to call them magnetars.
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Laptop

Trivial: the environmental impact of Google searches

Jonathan Leake and Richard Woods
Times Online
Sun, 11 Jan 2009 18:05 UTC
Physicist Alex Wissner-Gross says that performing two Google searches uses up as much energy as boiling the kettle for a cup of tea

Performing two Google searches from a desktop computer can generate about the same amount of carbon dioxide as boiling a kettle for a cup of tea, according to new research.

While millions of people tap into Google without considering the environment, a typical search generates about 7g of CO2 Boiling a kettle generates about 15g. "Google operates huge data centres around the world that consume a great deal of power," said Alex Wissner-Gross, a Harvard University physicist whose research on the environmental impact of computing is due out soon. "A Google search has a definite environmental impact."
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