Slashdot Mirror
Domain: arxivblog.com
Stories and comments across the archive that link to arxivblog.com.
Stories · 108
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NAO Humanoid Robot Set To Hit the Market
KentuckyFC writes "Earlier this year, Paris-based Aldebaran-Robotics picked up $8 million in venture capital funding to help commercialize its NAO humanoid robot. The target market for this device is research labs working on the next generation of robotic hardware and software. Today, the company has posted a detailed spec of NAO on the arXiv saying that it expects the robot to cost about $15,000 each. That's cheap compared to other humanoids. Fuitsu's HOAP humanoids cost $50,000 each and various estimates price Honda's Asimo at $1 million per bot, although they are not for sale. Aldebaran-Robotics says that NAO's cost should come down to about $6,000 as production ramps up." -
Liquid Mirror Telescopes Set For Magnetic Upgrade
KentuckyFC writes "Liquid mirror telescopes start life as a puddle of mercury in a bowl. Set the bowl spinning and the mercury spreads out in a thin film giving the surface an almost perfect mirror finish. But these telescopes have two important limitations. First, they can only point straight up since tilting the mirror spills the mercury. And second, they cannot be made adaptive to correct for any blurring introduced by the Earth's atmosphere. But liquid mirror telescopes look set for an upgrade thanks to the work of a group of Canadian researchers. Their technique is to change the shape of the liquid mirror using powerful electromagnets. They use a ferromagnetic fluid of iron nanoparticles in oil instead of mercury which is too dense to be easily manipulated in this way. The work is just proof of principle at this stage but the idea is to use magnets to correct for the usual range of optical aberrations that telescopes have to deal with (abstract). And also to allow a liquid telescope to be tilted by using oil that is much more viscous than mercury and correcting any periodic deformation in the fluid that tilting might cause." -
Liquid Mirror Telescopes Set For Magnetic Upgrade
KentuckyFC writes "Liquid mirror telescopes start life as a puddle of mercury in a bowl. Set the bowl spinning and the mercury spreads out in a thin film giving the surface an almost perfect mirror finish. But these telescopes have two important limitations. First, they can only point straight up since tilting the mirror spills the mercury. And second, they cannot be made adaptive to correct for any blurring introduced by the Earth's atmosphere. But liquid mirror telescopes look set for an upgrade thanks to the work of a group of Canadian researchers. Their technique is to change the shape of the liquid mirror using powerful electromagnets. They use a ferromagnetic fluid of iron nanoparticles in oil instead of mercury which is too dense to be easily manipulated in this way. The work is just proof of principle at this stage but the idea is to use magnets to correct for the usual range of optical aberrations that telescopes have to deal with (abstract). And also to allow a liquid telescope to be tilted by using oil that is much more viscous than mercury and correcting any periodic deformation in the fluid that tilting might cause." -
Simple Mod Turns Diodes Into Photon Counters
KentuckyFC writes "The standard way to detect single photons is to use an avalanche photodiode in which a single photon can trigger an avalanche of current. These devices have an important drawback, however. They cannot distinguish the arrival of a single photon from the simultaneous arrival of two or more. But a team of physicists in the UK has found a simple mod that turns avalanche photodiodes into photon counters. They say that in the first instants after the avalanche forms, its current is proportional to the number of photons that have struck. All you have to do is measure it at this early stage. That's like turning a Fiat 500 into a Ferrari. Photon counting is one of the enabling technologies behind optical quantum computing. A number of schemes are known in which it is necessary to count the arrival of 0, 1 or 2 photons at specific detectors (abstract). With such a cheap detector now available (as well as decent photon guns), we could see dramatic progress in this field in the coming months." -
Simple Mod Turns Diodes Into Photon Counters
KentuckyFC writes "The standard way to detect single photons is to use an avalanche photodiode in which a single photon can trigger an avalanche of current. These devices have an important drawback, however. They cannot distinguish the arrival of a single photon from the simultaneous arrival of two or more. But a team of physicists in the UK has found a simple mod that turns avalanche photodiodes into photon counters. They say that in the first instants after the avalanche forms, its current is proportional to the number of photons that have struck. All you have to do is measure it at this early stage. That's like turning a Fiat 500 into a Ferrari. Photon counting is one of the enabling technologies behind optical quantum computing. A number of schemes are known in which it is necessary to count the arrival of 0, 1 or 2 photons at specific detectors (abstract). With such a cheap detector now available (as well as decent photon guns), we could see dramatic progress in this field in the coming months." -
First X-Ray Diffraction Image of a Single Virus
KentuckyFC writes "X-ray crystallography has been a workhorse for chemists since the 1940s and 50s, revealing the 3D structure of complex biological molecules such as haemoglobin, DNA and insulin. But the technique has a severe limitation: it only works with molecules that form into crystals and that turns out to be a tiny fraction of the proteins that make up living things. But today, a team of US researchers say they have created the first image of a single uncrystallized virus using x-ray diffraction. The trick is to take a diffraction pattern of the virus and then subtract the diffraction pattern of its surroundings (abstract). The breakthrough paves the way for scientists to start teasing apart the 3D structures of the many proteins that have eluded biologists to date." -
First X-Ray Diffraction Image of a Single Virus
KentuckyFC writes "X-ray crystallography has been a workhorse for chemists since the 1940s and 50s, revealing the 3D structure of complex biological molecules such as haemoglobin, DNA and insulin. But the technique has a severe limitation: it only works with molecules that form into crystals and that turns out to be a tiny fraction of the proteins that make up living things. But today, a team of US researchers say they have created the first image of a single uncrystallized virus using x-ray diffraction. The trick is to take a diffraction pattern of the virus and then subtract the diffraction pattern of its surroundings (abstract). The breakthrough paves the way for scientists to start teasing apart the 3D structures of the many proteins that have eluded biologists to date." -
How To Build a Quantum Eavesdropper
KentuckyFC writes "Quantum encryption is perfectly secure, in theory. In practice, however, there are loopholes. Now Japanese scientists have designed a quantum eavesdropper that exploits one of these loopholes to listen in to quantum conversations. QC's security arises from the impossibility of making a perfect copy of a quantum object without destroying it — so the sender and receiver can always tell if they've been overheard. But it turns out that an eavesdropper can make imperfect copies and use them to extract information from a quantum message without alerting sender or receiver (abstract). The Japanese design does just this. That should worry banks and government agencies that have begun to use some of the commercial quantum encryption systems now available." -
How To Build a Quantum Eavesdropper
KentuckyFC writes "Quantum encryption is perfectly secure, in theory. In practice, however, there are loopholes. Now Japanese scientists have designed a quantum eavesdropper that exploits one of these loopholes to listen in to quantum conversations. QC's security arises from the impossibility of making a perfect copy of a quantum object without destroying it — so the sender and receiver can always tell if they've been overheard. But it turns out that an eavesdropper can make imperfect copies and use them to extract information from a quantum message without alerting sender or receiver (abstract). The Japanese design does just this. That should worry banks and government agencies that have begun to use some of the commercial quantum encryption systems now available." -
Spit Will Be Worse Than Spam
KentuckyFC writes "A team of German computer scientists has developed a program that reproduces all the known forms of spit (spam over internet telephony) attack. Their plan is to make the spitting software available to computer security experts wanting to test antispit strategies. Developing these won't be easy. There are various antispit techniques, such as white lists that allow only calls from predetermined callers, Turing tests such as audio CAPTCHAs that make a caller prove he or she is human and payment-at-risk services where the caller makes a small payment in advance and is refunded immediately if the receiver acknowledges the call as legitimate. But all have weaknesses, say the researchers. The main difference between junk calls and junk email is that the email arrives at your mail server before you access it. This gives the server time to analyze its content and filter out the junk before it gets to you. Not so with internet telephony, which is why radically different strategies are needed." -
Spit Will Be Worse Than Spam
KentuckyFC writes "A team of German computer scientists has developed a program that reproduces all the known forms of spit (spam over internet telephony) attack. Their plan is to make the spitting software available to computer security experts wanting to test antispit strategies. Developing these won't be easy. There are various antispit techniques, such as white lists that allow only calls from predetermined callers, Turing tests such as audio CAPTCHAs that make a caller prove he or she is human and payment-at-risk services where the caller makes a small payment in advance and is refunded immediately if the receiver acknowledges the call as legitimate. But all have weaknesses, say the researchers. The main difference between junk calls and junk email is that the email arrives at your mail server before you access it. This gives the server time to analyze its content and filter out the junk before it gets to you. Not so with internet telephony, which is why radically different strategies are needed." -
Testing Quantum Behavior — From Earth to the ISS
KentuckyFC writes "Einstein famously believed that the instantaeous effect of quantum entanglement would allow 'spooky action-at-a-distance' in violation of special relativity. Every test of entanglement on Earth has so far agreed with quantum mechanics but naysayers continue to point out various loopholes that might allow the results of these experiments to be determined in advance rather than instantaneously as QM suggests. Today, an international team of scientists is proposing the mother of all entanglement experiments, to be performed in space. The plan is to send entangled photons between an observer on the ground and one on the International Space Station. By the peculiarities of special relativity, the high relative velocity between the observers means that both will always be able to claim to have carried out their measurement first, thereby ruling out the naysayers' arguments (abstract). The experiment, called Space-QUEST, would be housed aboard Europe's Columbus module and would give the much-derided ISS a stab at doing some decent science for a change." -
Testing Quantum Behavior — From Earth to the ISS
KentuckyFC writes "Einstein famously believed that the instantaeous effect of quantum entanglement would allow 'spooky action-at-a-distance' in violation of special relativity. Every test of entanglement on Earth has so far agreed with quantum mechanics but naysayers continue to point out various loopholes that might allow the results of these experiments to be determined in advance rather than instantaneously as QM suggests. Today, an international team of scientists is proposing the mother of all entanglement experiments, to be performed in space. The plan is to send entangled photons between an observer on the ground and one on the International Space Station. By the peculiarities of special relativity, the high relative velocity between the observers means that both will always be able to claim to have carried out their measurement first, thereby ruling out the naysayers' arguments (abstract). The experiment, called Space-QUEST, would be housed aboard Europe's Columbus module and would give the much-derided ISS a stab at doing some decent science for a change." -
Does Antimatter Fall Up Or Down?
KentuckyFC writes "There are enough loopholes in the general theory of relativity to allow antimatter to fall up rather than down in a gravitational field. We've never been able to make enough of the stuff to do the experiment. But at the European particle physics laboratory at CERN, where scientists have been refining the technique for making antihydrogen, researchers are designing an experiment called AEGIS that will finally settle the matter. The idea is simple — fire a beam of antihydrogen atoms and watch which way they fall — but the details are fiendish (abstract). The answer should help solve a number of important conundrums such as why there is so little antimatter in our part of the universe and what the value of the cosmological constant is." -
Does Antimatter Fall Up Or Down?
KentuckyFC writes "There are enough loopholes in the general theory of relativity to allow antimatter to fall up rather than down in a gravitational field. We've never been able to make enough of the stuff to do the experiment. But at the European particle physics laboratory at CERN, where scientists have been refining the technique for making antihydrogen, researchers are designing an experiment called AEGIS that will finally settle the matter. The idea is simple — fire a beam of antihydrogen atoms and watch which way they fall — but the details are fiendish (abstract). The answer should help solve a number of important conundrums such as why there is so little antimatter in our part of the universe and what the value of the cosmological constant is." -
First Exotic Space Thruster Test Ends in Explosion
KentuckyFC writes "A NASA-funded test of an entirely new way to control orbiting satellites has ended with the prototype arcing dangerously and parts of the machine exploding. The new propulsion system is based on the Lorentz force: that a charged particle moving through a magnetic field experiences a force perpendicular to both its velocity and the field. So the plan is to ensure that a satellite passing though the Earth's magnetic field is electrically charged so as to generate a force that can be used to steer the spacecraft. The advantage of the idea is that it requires no propellant, which is a big deal since most satellites' lifespans are limited by the amount of fuel they can carry. But the first ground-based tests haven't gone entirely to plan." -
First Exotic Space Thruster Test Ends in Explosion
KentuckyFC writes "A NASA-funded test of an entirely new way to control orbiting satellites has ended with the prototype arcing dangerously and parts of the machine exploding. The new propulsion system is based on the Lorentz force: that a charged particle moving through a magnetic field experiences a force perpendicular to both its velocity and the field. So the plan is to ensure that a satellite passing though the Earth's magnetic field is electrically charged so as to generate a force that can be used to steer the spacecraft. The advantage of the idea is that it requires no propellant, which is a big deal since most satellites' lifespans are limited by the amount of fuel they can carry. But the first ground-based tests haven't gone entirely to plan." -
ET Will Phone Home Using Neutrinos, Not Photons
KentuckyFC writes "Neutrinos are better than photons for communicating across the galaxy. That's the conclusion of a group of US astronomers who say that the galaxy is filled with photons that make communications channels noisy whereas neutrino comms would be relatively noise free. Photons are also easily scattered and the centre of the galaxy blocks them entirely. That means any civilisation advanced enough to have started to colonise the galaxy would have to rely on neutrino communications. And the astronomers reckon that the next generation of neutrino detectors should be sensitive enough to pick up ET's chatter." -
ET Will Phone Home Using Neutrinos, Not Photons
KentuckyFC writes "Neutrinos are better than photons for communicating across the galaxy. That's the conclusion of a group of US astronomers who say that the galaxy is filled with photons that make communications channels noisy whereas neutrino comms would be relatively noise free. Photons are also easily scattered and the centre of the galaxy blocks them entirely. That means any civilisation advanced enough to have started to colonise the galaxy would have to rely on neutrino communications. And the astronomers reckon that the next generation of neutrino detectors should be sensitive enough to pick up ET's chatter." -
How Water Forms in Interstellar Space at 10K
KentuckyFC writes "Water is the most abundant solid material in space. But although astronomers see it on planets, moons, in comets and in interstellar clouds, nobody has been able to show how it forms. In theory, it should form easily when oxygen and atomic hydrogen meet. The problem is that there is not enough of it floating around as gas in interstellar dust clouds. So instead, the thinking is that water must form when atomic hydrogen interacts with frozen solid oxygen on the surface of dust grains in these clouds. Now Japanese astronomers have demonstrated this process for the first time in the lab in conditions that simulate interstellar space. That's cool because all the water in the solar system, including almost every drop you drink on Earth today, must have formed in exactly this way more than 5 billion years ago in a pre-solar dustcloud (abstract)." -
How Water Forms in Interstellar Space at 10K
KentuckyFC writes "Water is the most abundant solid material in space. But although astronomers see it on planets, moons, in comets and in interstellar clouds, nobody has been able to show how it forms. In theory, it should form easily when oxygen and atomic hydrogen meet. The problem is that there is not enough of it floating around as gas in interstellar dust clouds. So instead, the thinking is that water must form when atomic hydrogen interacts with frozen solid oxygen on the surface of dust grains in these clouds. Now Japanese astronomers have demonstrated this process for the first time in the lab in conditions that simulate interstellar space. That's cool because all the water in the solar system, including almost every drop you drink on Earth today, must have formed in exactly this way more than 5 billion years ago in a pre-solar dustcloud (abstract)." -
Antineutrino Device Tackles Nuclear Proliferation
KentuckyFC writes "One of the biggest problems in nuclear proliferation is verifying that countries are not secretly transferring fissile material by taking it out of reactors and selling it. Now a group of US scientists say they've developed a machine that can remotely detect whether a reactor has been switched on and off by detecting the antineutrinos produced by nuclear reactions. The detector is about the size of a car engine and is designed to be left near a reactor to record data. The group has been testing a prototype at the San Onofre Nuclear Generating Station in Southern California and says it works well (abstract). Now it's up to the International Atomic Energy Authority in Vienna to decide whether to deploy the new machine." -
Antineutrino Device Tackles Nuclear Proliferation
KentuckyFC writes "One of the biggest problems in nuclear proliferation is verifying that countries are not secretly transferring fissile material by taking it out of reactors and selling it. Now a group of US scientists say they've developed a machine that can remotely detect whether a reactor has been switched on and off by detecting the antineutrinos produced by nuclear reactions. The detector is about the size of a car engine and is designed to be left near a reactor to record data. The group has been testing a prototype at the San Onofre Nuclear Generating Station in Southern California and says it works well (abstract). Now it's up to the International Atomic Energy Authority in Vienna to decide whether to deploy the new machine." -
First Superheavy Element Found In Nature
KentuckyFC writes "The first naturally occurring superheavy element has been found. An international team of scientists found several nuclei of unbibium in a sample of the naturally occurring heavy metal thorium. Unbibium has an atomic number of 122 and an atomic weight of 292. In general, very heavy elements tend to be unstable but scientists have long predicted that even heavier nuclei would be stable. The group that found unbibium in thorium say it has a half life in excess of 100 million years and an abundance of about 10^(-12) relative to thorium, which itself is about as abundant as lead." I'd also like it known that my spell checker did not know 'unbibium' before today, but it is now one word closer to encompassing all human knowledge. -
First Superheavy Element Found In Nature
KentuckyFC writes "The first naturally occurring superheavy element has been found. An international team of scientists found several nuclei of unbibium in a sample of the naturally occurring heavy metal thorium. Unbibium has an atomic number of 122 and an atomic weight of 292. In general, very heavy elements tend to be unstable but scientists have long predicted that even heavier nuclei would be stable. The group that found unbibium in thorium say it has a half life in excess of 100 million years and an abundance of about 10^(-12) relative to thorium, which itself is about as abundant as lead." I'd also like it known that my spell checker did not know 'unbibium' before today, but it is now one word closer to encompassing all human knowledge. -
Bluetooth Surveillance Tested In the UK
KentuckyFC writes "If you live in the city of Bath in the UK and carry a Bluetooth-enabled device, your movements may have been secretly monitored in an experiment designed to test surveillance techniques in prisons. Researchers from Bath University recorded the movements of 10,000 Bluetooth-enabled devices during their 6-month trial. They say the experiment was a test of a technique for monitoring the interactions between prisoners in jail that could be used to work out which inmates have become closely associated. The work was prompted by revelations that the Madrid train bombers who devastated the city in 2004 first met in a Spanish prison (abstract)." -
Bluetooth Surveillance Tested In the UK
KentuckyFC writes "If you live in the city of Bath in the UK and carry a Bluetooth-enabled device, your movements may have been secretly monitored in an experiment designed to test surveillance techniques in prisons. Researchers from Bath University recorded the movements of 10,000 Bluetooth-enabled devices during their 6-month trial. They say the experiment was a test of a technique for monitoring the interactions between prisoners in jail that could be used to work out which inmates have become closely associated. The work was prompted by revelations that the Madrid train bombers who devastated the city in 2004 first met in a Spanish prison (abstract)." -
Bird Navigation Based On Quantum Zeno Effect
KentuckyFC writes "How birds use the Earth's magnetic field to navigate has puzzled researchers for decades. In recent years, a growing body of evidence has pointed to the possibility that a weak magnetic field can influence the outcome of a certain type of chemical reaction involving the recombination of pairs of ions in bird retinas. The trouble is that the ion recombination is known to happen too quickly for the Earth's weak magnetic field to have any effect. Now it looks as if the quantum Zeno effect explains all, says one researcher (abstract). This is the watched-pot-never-boils effect in which the act of observing a quantum system maintains it for longer than expected. That's extraordinary news because it means a quantum sensor is determining the macroscopic behavior of living birds." -
Bird Navigation Based On Quantum Zeno Effect
KentuckyFC writes "How birds use the Earth's magnetic field to navigate has puzzled researchers for decades. In recent years, a growing body of evidence has pointed to the possibility that a weak magnetic field can influence the outcome of a certain type of chemical reaction involving the recombination of pairs of ions in bird retinas. The trouble is that the ion recombination is known to happen too quickly for the Earth's weak magnetic field to have any effect. Now it looks as if the quantum Zeno effect explains all, says one researcher (abstract). This is the watched-pot-never-boils effect in which the act of observing a quantum system maintains it for longer than expected. That's extraordinary news because it means a quantum sensor is determining the macroscopic behavior of living birds." -
Nanoclusters Break Superconductivity Record
KentuckyFC writes "A couple of years ago, two Russian physicists predicted that metal nanoclusters with exactly the right number of delocalized electrons (a few hundred or so) could become strong superconductors. Now an American group has found the first evidence that this prediction is correct in individual aluminium nanoclusters containing 45 or 47 atoms. And they found it at 200 K (abstract). That's a huge jump over the previous record of 138K for a high-temperature superconductor. There are a few caveats, however. The result is only partial evidence of superconductivity and the work has yet to be peer-reviewed. But its mere publication will set scientists scrambling to confirm. And 200K! That's practically room temperature in the Siberian winter." -
Nanoclusters Break Superconductivity Record
KentuckyFC writes "A couple of years ago, two Russian physicists predicted that metal nanoclusters with exactly the right number of delocalized electrons (a few hundred or so) could become strong superconductors. Now an American group has found the first evidence that this prediction is correct in individual aluminium nanoclusters containing 45 or 47 atoms. And they found it at 200 K (abstract). That's a huge jump over the previous record of 138K for a high-temperature superconductor. There are a few caveats, however. The result is only partial evidence of superconductivity and the work has yet to be peer-reviewed. But its mere publication will set scientists scrambling to confirm. And 200K! That's practically room temperature in the Siberian winter." -
Qutrits Bring Quantum Computers Closer
KentuckyFC writes "To do anything useful with quantum logic gates, you need dozens to hundreds of them, all joined together. And because of various errors and problems that creep in, that's more or less impossible with today's technology. Now an Australian group has built and tested logic gates that convert qubits into qutrits (three-level quantum states) before processing and then convert them back again. That makes them far more powerful. The group says that a quantum computer that might require 50 conventional quantum logic gates can now be built with just 9 of the new gates. What's more, the gates process photons using nothing more than standard linear optical components (abstract on the physics arxiv)." -
Qutrits Bring Quantum Computers Closer
KentuckyFC writes "To do anything useful with quantum logic gates, you need dozens to hundreds of them, all joined together. And because of various errors and problems that creep in, that's more or less impossible with today's technology. Now an Australian group has built and tested logic gates that convert qubits into qutrits (three-level quantum states) before processing and then convert them back again. That makes them far more powerful. The group says that a quantum computer that might require 50 conventional quantum logic gates can now be built with just 9 of the new gates. What's more, the gates process photons using nothing more than standard linear optical components (abstract on the physics arxiv)." -
Scientists Build New Type of Photon Gun
KentuckyFC writes "Single photons are surprisingly difficult to generate. But since they are crucial for quantum communication, a number of research groups are working on photon guns that fire single photons on demand. The problem they have come up against is that making the photons identical is proving harder than expected. Now a group in Cambridge, UK, has cracked the problem using a quantum dot on a transistor to emit single photons that are essentially identical. In the process, the group has developed an entirely new technique to trigger photon emission (abstract on the physics arxiv)." -
Scientists Build New Type of Photon Gun
KentuckyFC writes "Single photons are surprisingly difficult to generate. But since they are crucial for quantum communication, a number of research groups are working on photon guns that fire single photons on demand. The problem they have come up against is that making the photons identical is proving harder than expected. Now a group in Cambridge, UK, has cracked the problem using a quantum dot on a transistor to emit single photons that are essentially identical. In the process, the group has developed an entirely new technique to trigger photon emission (abstract on the physics arxiv)." -
Rubik's Cube Proof Cut To 25 Moves
KentuckyFC writes "A scrambled Rubik's cube can be solved in just 25 moves, regardless of the starting configuration. Tomas Rokicki, a Stanford-trained mathematician, has proven the new limit (down from 26 which was proved last year) using a neat piece of computer science. Rather than study individual moves, he's used the symmetry of the cube to study its transformations in sets. This allows him to separate the 'cube space' into 2 billion sets each containing 20 billion elements. He then shows that a large number of these sets are essentially equivalent to other sets and so can be ignored. Even then, to crunch through the remaining sets, he needed a workstation with 8GB of memory and around 1500 hours of time on a Q6600 CPU running at 1.6GHz. Next up, 24 moves." -
Rubik's Cube Proof Cut To 25 Moves
KentuckyFC writes "A scrambled Rubik's cube can be solved in just 25 moves, regardless of the starting configuration. Tomas Rokicki, a Stanford-trained mathematician, has proven the new limit (down from 26 which was proved last year) using a neat piece of computer science. Rather than study individual moves, he's used the symmetry of the cube to study its transformations in sets. This allows him to separate the 'cube space' into 2 billion sets each containing 20 billion elements. He then shows that a large number of these sets are essentially equivalent to other sets and so can be ignored. Even then, to crunch through the remaining sets, he needed a workstation with 8GB of memory and around 1500 hours of time on a Q6600 CPU running at 1.6GHz. Next up, 24 moves." -
Astronomers Discover New Class of Pulsating Star
KentuckyFC writes "It doesn't happen very often but astronomers have discovered a new class of pulsating white dwarf. The work began last year when the Sloan Digital Sky Survey found a few exotic white dwarf stars with carbon atmospheres. A mathematical model of these stars showed that in some circumstances the dwarfs could pulsate as the carbon was cycled through the atmosphere by convection. Now a few days observation of one of these stars has shown that it does actually pulsate as predicted." -
Astronomers Discover New Class of Pulsating Star
KentuckyFC writes "It doesn't happen very often but astronomers have discovered a new class of pulsating white dwarf. The work began last year when the Sloan Digital Sky Survey found a few exotic white dwarf stars with carbon atmospheres. A mathematical model of these stars showed that in some circumstances the dwarfs could pulsate as the carbon was cycled through the atmosphere by convection. Now a few days observation of one of these stars has shown that it does actually pulsate as predicted." -
Single Photons Bounced Off Orbiting Satellite
KentuckyFC writes "If we're ever going to benefit from the perfect security of quantum communication, we're going to need ways of transmitting entangled photons around the globe and certainly further than the current record of 144km through the atmosphere. Anton Zeilinger at the University of Vienna and colleagues have taken an important step towards this by bouncing individual photons off the Ajisai geodetic satellite (essentially a space-based disco ball) which is orbiting at 1400km. The group says the experiment is an important proof of principle for satellite-based quantum communications." -
Single Photons Bounced Off Orbiting Satellite
KentuckyFC writes "If we're ever going to benefit from the perfect security of quantum communication, we're going to need ways of transmitting entangled photons around the globe and certainly further than the current record of 144km through the atmosphere. Anton Zeilinger at the University of Vienna and colleagues have taken an important step towards this by bouncing individual photons off the Ajisai geodetic satellite (essentially a space-based disco ball) which is orbiting at 1400km. The group says the experiment is an important proof of principle for satellite-based quantum communications." -
First "Observation" of Hawking Radiation
KentuckyFC writes "Italian physicists are claiming the first observation of Hawking radiation, but not from a black hole. Instead they've spotted it streaming from a sonic horizon in a Bose Einstein Condensate (abstract on the arXiv). That's consistent with previous predictions but they're claiming the 'first' even though the experiment was only a numerical simulation. Does that really count?" -
First "Observation" of Hawking Radiation
KentuckyFC writes "Italian physicists are claiming the first observation of Hawking radiation, but not from a black hole. Instead they've spotted it streaming from a sonic horizon in a Bose Einstein Condensate (abstract on the arXiv). That's consistent with previous predictions but they're claiming the 'first' even though the experiment was only a numerical simulation. Does that really count?" -
Physicist Calculates Trajectory of Tiger At SF Zoo
KentuckyFC writes "Is it really possible for a 350-pound tiger to leap a 12.5-foot barrier from 33 feet away? (Said another way: a 159-kg tiger, a 3.8 m barrier, and 10 m away.) A physicist at Northeastern University has done the math, a straightforward problem in ballistics, and the answer turns out to be yes (abstract on the physics arXiv). But I guess we already knew that following the death of Carlos Souza at the paws of Tatiana, a Siberian Tiger he had allegedly been taunting at San Francisco zoo at the end of last year." -
Physicist Calculates Trajectory of Tiger At SF Zoo
KentuckyFC writes "Is it really possible for a 350-pound tiger to leap a 12.5-foot barrier from 33 feet away? (Said another way: a 159-kg tiger, a 3.8 m barrier, and 10 m away.) A physicist at Northeastern University has done the math, a straightforward problem in ballistics, and the answer turns out to be yes (abstract on the physics arXiv). But I guess we already knew that following the death of Carlos Souza at the paws of Tatiana, a Siberian Tiger he had allegedly been taunting at San Francisco zoo at the end of last year." -
Australian Astronomers Make Interstellar Hologram
KentuckyFC writes "Australian astronomers say the way a beam of light from a pulsar is scattered by interstellar dust is analogous to the way a hologram is made. But to reconstruct an image of this dust, you've got to know what the light was like before it was distorted. With an impressive piece of computer optimization, these astronomers have worked out the 8000 coefficients that determine the light field and so have been able to produce an image of the interstellar medium (abstract on the physics arXiv)." -
Australian Astronomers Make Interstellar Hologram
KentuckyFC writes "Australian astronomers say the way a beam of light from a pulsar is scattered by interstellar dust is analogous to the way a hologram is made. But to reconstruct an image of this dust, you've got to know what the light was like before it was distorted. With an impressive piece of computer optimization, these astronomers have worked out the 8000 coefficients that determine the light field and so have been able to produce an image of the interstellar medium (abstract on the physics arXiv)." -
Anonymity of Netflix Prize Dataset Broken
KentuckyFC writes "The anonymity of the Netflix Prize dataset has been broken by a pair of computer scientists from the University of Texas, according to a report from the physics arXivblog. It turns out that an individual's set of ratings and the dates on which they were made are pretty unique, particularly if the ratings involve films outside the most popular 100 movies. So it's straightforward to find a match by comparing the anonymized data against publicly available ratings on the Internet Movie Database (IMDb) (abstract on the physics arxiv). The researchers used this method to find how individuals on the IMDb privately rated films on Netflix, in the process possibly working out their political affiliation, sexual preferences and a number of other personal details" -
Anonymity of Netflix Prize Dataset Broken
KentuckyFC writes "The anonymity of the Netflix Prize dataset has been broken by a pair of computer scientists from the University of Texas, according to a report from the physics arXivblog. It turns out that an individual's set of ratings and the dates on which they were made are pretty unique, particularly if the ratings involve films outside the most popular 100 movies. So it's straightforward to find a match by comparing the anonymized data against publicly available ratings on the Internet Movie Database (IMDb) (abstract on the physics arxiv). The researchers used this method to find how individuals on the IMDb privately rated films on Netflix, in the process possibly working out their political affiliation, sexual preferences and a number of other personal details" -
The Gap Between Stats and Understanding In Flu Cases
KentuckyFC writes "Bird flu gets all the headlines but ordinary flu kills several orders of magnitude more people each year and represents a significant threat to our society. The frightening thing about ordinary flu is how little we understand about how it spreads. According to a report at the physics arXiv blog, researchers trying to model this process say they still don't know some basic probabilities associated with infection (pdf, abstract). For instance, given that the disease has manifested itself clinically in an individual, what are the chances of that person dying? And if a virus can be caught from a number of different host species (as it might eventually be with bird flu) what is the probability of transmission?"