Month: June 2008
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First X-ray diffraction image of a single virus
X-ray crystallography has been a workhorse technique for chemists since the 1940s and 50s. For many years, it was the only way to determine the 3D structure of complex biological molecules such haemoglobin, DNA and insulin. Many a Nobel prize has been won poring over diffraction images with a magnifying glass. But x-ray crystallography has…
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Why gamma ray bursts are not standard candles
A revolution is currently underway in our knowledge of gamma ray bursts thanks to NASA’s Swift telescope which has been looking out for them from its perch in orbit since 2004. But in the wild enthusiasm to embrace the firehose of data that Swift is sending back, it looks as if astronomers have made a…
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The embarrassing lightness of photons
Here’s a conundrum for you. What is the momentum of light in a transparent dielectric medium? If the answer doesn’t trip off your tongue, that might be because nobody else knows either. Amazingly, there are two lines of thought: In 1908, the German mathematician Hermann Minkowski guessed that the momentum was equal to nE/c (where…
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How to bury an ion (and find it again later)
The future of computing depends on our ability to bury single ions within the crystal structure of silicon and diamond in a way that allows us to find them again, quickly and repeatably. The burying part of all this isn’t difficult: simply aim a beam of ions at a substrate and you can be pretty…
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Extraterrestrial nucleobases found in meteorite
In 1969, a large meteorite fell near the town of Murchison in Victoria, Australia. Scientists collected more than 100 kilograms of rock, making it the largest sample of carbonaceous chondrite ever recovered. Since then numerous groups have found evidence that the Murchison meteorite contains common amino acids, the building blocks of proteins, as well as…
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In case ya missed ’em…
This week’s sweetmeats from the physics arXiv blog: Testing “spooky action-at-a-distance” on the International Space Station Oil prices: a classic bubble economy? Cellphone records reveal the basic pattern of human mobility Let the SPIT wars begin How to build a quantum eavesdropper
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Adam ‘n’ Eve
Other highlights from the physics arXiv this week… Planetesimal Formation around the Snow Line in MRI-driven Turbulent Protoplanetary Disks On Career Longevity Distributions in Professional Sports Dark Entropy Landau’s Last Paper and its Impact on Developments in Mathematics, Physics and Other Disciplines in New Millennium Whispering-gallery Modes and Light Emission from a Si-nanocrystal-based Single Microdisk…
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How to build a quantum eavesdropper
In the cat and mouse game of preparing and eavesdropping on secret messages, quantum encryption trumps all. At least, that’s what we’ve been told. The truth is a little more complex. Quantum key distribution, the quantum technique by which a classical encryption key can be transferred, is perfectly secure in theory. In practice, there are…
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Let the SPIT wars begin
If SPAM arrives in your inbox at 4am, the chances are your antispam software will catch it. But even if it doesn’t, you won’t lose much sleep over its arrival. But it’ll be a different story with SPIT (spam over internet telephony). Junk phone calls at 4am are going to drive you mad because the…
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Cellphone records reveal the basic pattern of human mobility
A few months back, we saw what happens when researchers get their paws on anonymixed mobile phone records. Albert-Laszlo Baribasi at the University of Notre Dame in Indiana and some buddies used them to discover entirely new patterns of human behaviour. Now Baribasi has dug deeper into the data and discovered a single basic pattern…