64055671
submission
KentuckyFC writes:
In 1980 and 1981, Voyager 1 and 2 flew past Saturn providing unprecedented images of its magnificent ring system. At that time, its most distant discrete ring, the F ring, was about 200 kilometres wide. But puzzlingly, images sent back by Cassini show that the ring is now 580 kilometres wide and twice as bright as it was thirty years ago. Now astronomers think they have finally solved the mystery of the expanding F ring. The ring is shepherded by a number of small moons, the most famous of which is Prometheus. These moons interact gravitationally with the ring creating structures such as braids and spokes. The new thinking is that the moons' orbits resonate with the F ring, pushing clouds of dust and ice further away from Saturn. This makes the ring wider. But beyond a certain radius the orbit of the dust becomes unstable and it begins to spiral back towards Saturn and collides with the rest of the ring. This causes a chain reaction of collisions that dramatically increases the number of particles in the ring and hence its brightness. This theory also leads to a prediction--the resonant process is currently at a maximum but should reduce sharply in the coming years, if the theory is correct. So by 2018, the F ring should be back to the same configuration the Voyagers saw in 80/81.
63891781
submission
KentuckyFC writes:
The Great Pyramid of Giza in Egypt is constructed from 2.4 million limestone blocks, most about 2.5 tonnes but some weighing in at up to 80 tonnes, mostly sourced from local limestone quarries. That raises a famous question. How did the ancient Egyptians move these huge blocks into place? There is no shortage of theories but now a team of physicists has come up with another that is remarkably simple--convert the square cross section of the blocks into dodecadrons making them easy to roll. The team has tested the idea on a 30 kg scaled block the shape of a square prism. They modified the square cross-section by strapping three wooden rods to each long face, creating a dodecahedral profile. Finally, they attached a rope to the top of the block and measured the force necessary to set it rolling. The team say a full-sized block could be modified with poles the size of ships masts and that a work crew of around 50 men could move a block with a mass of 2.5 tonnes at the speed of 0.5 metres per second. The result suggests that this kind of block modification is a serious contender for the method the Egyptians actually used to construct the pyramids, say the researchers.
63774237
submission
KentuckyFC writes:
Superconductors allow current to flow with zero resistance when cooled below some critical temperature. They are the crucial ingredients in everything from high-power magnets and MRI machines to highly sensitive magnetometers and magnetic levitation devices. But one big problem is that superconductors work only at very low temperatures--the highest is around 150 kelvin (-120 degrees centigrade). So scientists would dearly love to find ways of raising this critical temperature. Now a group of physicists say they've found a promising approach--to build metamaterial superconductors that steer electrons in the same way as other metamaterials steer light to create invisibility cloaks. The inspiration for the work comes from the observation that some high temperature superconductors consist of repeated layers of conducting and dielectric structures. So the team mixed tin--a superconductor at 3.7 kelvin--with the dielectric barium titanate and found that it raised the critical temperature by 0.15 kelvin. That's the first demonstration that superconductors can be thought of as metamaterials. With this proof of principle under their belts, the next step is to look for bigger gains at higher temperatures.
63695807
submission
KentuckyFC writes:
Art experts look for influences between great masters by studying the artist’s use of space, texture, form, shape, colour and so on. They may also consider the subject matter, brushstrokes, meaning, historical context and myriad other factors. So it's easy to imagine that today's primitive machine vision techniques have little to add. Not so. Using a new technique for classifying objects in images, a team of computer scientists and art experts have compared more than 1700 paintings from over 60 artists dating from the early 15th century to the late 20 the century. They've developed an algorithm that has used these classifications to find many well known influences between artists, such as the well known influence of Pablo Picasso and George Braque on the Austrian symbolist painter Gustav Klimt, the influence of the French romantic Delacroix on the French impressionist Bazille, the Norwegian painter Munch’s influence on the German painter Beckmann and Degas’ influence on Caillebotte. But the algorithm also discovered connections that art historians have never noticed (judge the comparisons for yourself). In particular, the algorithm points out that Norman Rockwell’s Shuffleton’s Barber Shop painted in 1950 is remarkably similar to Frederic Bazille’s Studio 9 Rue de la Condamine painted 80 years before.
63581625
submission
KentuckyFC writes:
In 1931, after a 3- month visit to the US , Einstein penned a little known paper that attempted to show how his theory of general relativity could account for some of the latest scientific evidence. In particular, Einstein had met Edwin Hubble during his trip and so was aware of the latter's data indicating that the universe must be expanding. The resulting model is of a universe that expands and then contracts with a singularity at each end. In other words, Einstein was studying a universe that starts with a big bang and ends in a big crunch. What's extraordinary about the paper is that Einstein misspells Hubble's name throughout and makes a number of numerical errors in his calculations. That's probably because he wrote the paper in only 4 days, say the historians who have translated it into English for the time. This model was ultimately superseded by the Einstein-de Sitter model published the following year which improves on this in various ways and has since become the workhorse of modern cosmology.
63513537
submission
KentuckyFC writes:
One of the most interesting emerging treatments for certain types of cancer aims to starve the tumour to death. The strategy involves destroying or blocking the blood vessels that supply a tumour with oxygen and nutrients. Without its lifeblood, the unwanted growth shrivels up and dies. This can be done by physically blocking the vessels with blood clots, gels, balloons, glue, nanoparticles and so on. However, these techniques have never been entirely successful because the blockages can be washed away by the blood flow and the materials do not always fill blood vessels entirely, allowing blood to flow round them. Now Chinese researchers say they've solved the problem by filling blood vessels with an indium-gallium alloy that is liquid at body temperature. They've tested the idea in the lab on mice and rabbits. Their experiments show that the alloy is relatively benign but really does fill the vessels, blocks the blood flow entirely and starves the surrounding tissue of oxygen and nutrients. The team has also identified some problems such as the possibility of blobs of metal being washed into the heart and lungs. Nevertheless, they say their approach is a promising injectable tumour treatment.
63415133
submission
KentuckyFC writes:
One curious property of massless particles like photons is that their energy or momentum can take any value across many orders of magnitude, a property that physicists call scale invariance. By contrast, massive particles like electrons always have the same mass regardless of their energy or momentum. So massive particles are not scale invariant. The concept of unparticles is the idea that some “stuff” may have mass, energy and momentum and yet also be scale invariant. This stuff must be profoundly different from ordinary particles, hence the name: unparticles. Nobody has ever seen an unparticle but now physicists are suggesting that unparticles may hold the key to understanding unconventional superconductivity. Their thinking is that at very low temperatures, ordinary particles can sometimes behave like unparticles. In other words, their properties become independent of the scale at which they're observed. So if an unparticle moves without resistance on a tiny scale, then it must also move without resistance at every scale, hence the phenomenon of superconductivity. That could provide some important insights into unconventional superconductivity which has puzzled physicists since it was discovered in the 1980s.
63381317
submission
KentuckyFC writes:
Researchers from Cornell University glued a tiny magnetic bar to the back of fruit flies and allowed them to fly through an electromagnet. Pulsing the magnet then causes the flies to roll in mid-air, like victorious Spitfire pilots. The work isn't entirely frivolous. The team was studying how fruit flies achieve stable flight when they ought to be particularly susceptible to being rolled by tiny gusts of air. It turns out that fruit flies have incredibly fast reactions. They respond to being rolled within a single wing beat, that's 5 milliseconds, flapping their wings asymmetrically to regain stable flight. That kind of reaction time makes them one of the fastest creatures in the animal world. By comparison, the visual startle response in flies takes 20 milliseconds and the quickest reactions humans can manage is about 100 milliseconds or 0.1 seconds.
63333493
submission
KentuckyFC writes:
In a classic The Far Side cartoon by Gary Larson, a group of cows stand on two legs chatting by the side of a road when a lookout shouts “car”. The cows immediately drop to a four-legged stance as the car passes by and return to their usual position and continue chatting when it has gone. Now a team of animal behaviour specialists have discovered that the social lives of cattle are more complex than biologists had ever imagined (although not quite into Larson territory). These guys attached RFID tags to 70 Holstein-Fresian calves kept in three pens. They then monitored the position of each cow for a week to see which other animals they tended to have contact with. This allowed them to construct the social network for the cows with unprecedented detail. It turns out these social networks have many of the properties of human social networks. Cows have preferred partners who they tend to spend more time with and 60 per cent of their contacts occur during feeding which amounts to only 6 per cent of their time. The work has important applications. It should help biologists more accurately model how disease spreads through herds of cattle and therefore better understand how to tackle epidemics. Udderly fascinating (cough).
63107293
submission
KentuckyFC writes:
One of the great challenges in neurobiology is to work out the entire wiring diagram of the human brain, a structure known as the human connectome. That’s going to be tricky. Researchers have successfully constructed the connectome of only one creature, the nematode worm C. elegans with a grand total of 302 neurons and 8000 connections between them. By contrast, the human cerebral cortex contains 10^10 neurons linked by 10^14 synaptic connections. One reason why progress has been slow is that the neurons have to be imaged using electronmicroscopy and the resulting images stacked and aligned so that every part of each neuron can be mapped by hand. In this way, the C. elegans connectome took 50 person-years to assemble. So biologists are racing to develop faster techniques that automate the mapping process. But that creates another problem. The wiring diagram and its spatial layout do not uniquely specify the function of a neural system. To gain a full understanding of what’s going on, biologists need to know the types of cells involved and how they connect to each other in microcircuits. That helps distinguish, for example, the function of circuitry involved in retinal tissue from that in brain tissue. Now researchers have developed an algorithmic technique that uses the spatial wiring diagram from an organism as an input and then uses it to automatically identify cell types, the circuits they form and hence the function of these neural systems. They have tested it on the connectome of C. elegans and say it reproduces the work of many years in just a few hours. They have even used it to work out the type of circuits in the 6502 microprocessor from the Apple II computer using only its ‘connectome’ as an input. This tool and others for automating the mapping of connectomes look set to revolutionise neurobiology. In particular it should allow the comparison of cell types across animals and species. That will be particularly important when different cell types emerge because of the stimuli they receive rather than the biomolecular properties of the cells themselves. So it looks as if connectomics is finally about to be revolutionised by bio informatics, jesters gene finding algorithms revolutionised molecular biology and computational phylogenetics revolutionised evolutionary biology.
62856281
submission
KentuckyFC writes:
Black holes are singularities in spacetime formed by stars that have collapsed at the end of their lives. But while black holes are one of the best known ideas in cosmology, physicists have never been entirely comfortable with the idea that regions of the universe can become infinitely density. Indeed, they only accept this because they can't think of any reason why it shouldn't happen. But in the last few months, just such a reason has emerged as a result of intense debate about one of cosmology's greatest problems--the information paradox. This is the fundamental tenet in quantum mechanics that all the information about a system is encoded in its wave function and this always evolves in a way that conserves information. The paradox arises when this system falls into a black hole causing the information to devolve into a single state. So information must be lost. Earlier this year, Stephen Hawking proposed a solution. His idea is that gravitational collapse can never continue beyond the so-called event horizon of a black hole beyond which information is lost. Gravitational collapse would approach the boundary but never go beyond it. That solves the information paradox but raises another question instead: if not a black hole, then what? Now one physicist has worked out the answer. His conclusion is that the collapsed star should end up about twice the radius of a conventional black hole but would not be dense enough to trap light forever and therefore would not be black. Indeed, to all intents and purposes, it would look like a large neutron star.
62740565
submission
KentuckyFC writes:
When animals lose a limb, they learn to hobble remarkably quickly. And yet when robots damage a leg, they become completely incapacitated. That now looks set to the change thanks to a group of robotics engineers who have worked out how to dramatically accelerate the process of learning to walk again when a limb has become damaged. They've tested it on a hexapod robot which finds an efficient new gait in under two minutes (with video), and often faster, when a leg becomes damaged. The problem for robots is that the parameter space of potential gaits is vast. For a robot with six legs and 18 motors, the task of finding an efficient new gait boils down to a search through 36-dimensional space. That's why it usually takes so long. The new approach gets around this by doing much of this calculation in advance, before the robot gets injured. The solutions are then ordered according to the amount of time each leg remains in contact with the ground. That reduces the dimension of the problem from 36 to 6 and so makes it much easier for the robot to search. When a leg becomes damaged, the robot selects new gaits from those that minimise contact with the ground for the damaged limb. It compares several and then chooses the fastest. Voila! The resulting gaits are often innovative, for example, with the robot moving by springing forward. The new approach even found a solution should all the legs become damaged. In that case, the robot flips onto its back and inches forward on its 'shoulders'.
62479791
submission
KentuckyFC writes:
The idea of negative mass has fascinated scientists since it was first used in the 16th century to explain why metals gain weight when they are oxidised. Since then, theoretical physicists have shown how it could be used to create exotic objects such as wormholes and the Alcubierre warp drive. But cosmologists' attempts to include negative matter in any reasonable model of the cosmos have always run into trouble because negative mass violates the energy conditions required to make realistic universes with Einstein's theory of general relativity. Now a pair of cosmologists have round a way round this. By treating negative mass as a perfect fluid rather than a solid point-like object, they've shown that negative mass does not violate the energy conditions as had been thought and so must be allowed in our universe. That has important consequences. If positive and negative mass particles were created in the early universe, they would form a kind of plasma that absorbs gravitational waves. Having built a number of gravitational wave observatories that have to see a single gravitational wave, astronomers might soon need to explain the absence of observations. Negative mass would then come in extremely handy.
62363111
submission
KentuckyFC writes:
When Japan’s Hayabusa spacecraft gently manoeuvred into a parking orbit around the asteroid Itokawa in September 2005, it conducted a comprehensive photographic survey, the most detailed ever taken of an asteroid. This survey revealed that Itokawa is covered in large boulders that look like ejecta from craters in other parts of the asteroid. But when astronomers added up the total volume of these boulders, it turned out to be greater than the volume of the craters there were supposed to have come from. Other asteroids also show a similarly skewed distribution of large boulders. That has caused some significant head-scratching among astronomers who are at a loss to explain where the boulders come from. Now an international team has solved the mystery. They say the boulders float to the surface of asteroids in an astrophysical example of the Brazil nut effect. This is the long observed phenomenon in which shaking a mixture of big and small particles causes the larger ones to rise to the top. That's because the shaking creates gaps beneath the large particles that small particles fall into. The result is that the large particles float. The team simulated the shaking effect that collisions between asteroids would produce and say that these vibrations would cause large boulders to float to the surface in a few hours, finally explaining why asteroids have such boulder-strewn surfaces. Problem solved!
62174515
submission
KentuckyFC writes:
On 13 March 1989, a powerful geomagnetic storm severely disrupted the Hydro-Québec high-voltage grid triggering numerous circuit breakers and blacking out much of eastern Canada and the north eastern US. Since then, Earth has been hit by numerous solar maelstroms although without such large-scale disruption. But the smaller-scale effect of these storms on low voltage transmissions line, and the equipment connected to them, has been unknown. Until now. Researchers from the Lockheed Martin Solar and Astrophysics Laboratory have analysed insurance claims for damage to industrial electrical equipment between 2000 and 2010 and found a clear correlation with geomagnetic activity. They say that the number of claims increases by up to 20 per cent on the days of highest geomagnetic activity. On this basis, they calculate that the economic impact of geomagnetic damage must amount to several billion dollars per year. That raises the question of the impact these storms are having on household electronic equipment, such as computers, smartphones and tablets, and whether domestic insurance claims might throw some light on the issue. So if your iPhone has ever been fried in mysterious circumstances, the culprit may have been the Sun.
