The Wisdom of (Little) Crowds - 1 views
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What is the best (wisest) size for a group of individuals? Couzin and Kao put together a series of mathematical models that included correlation and several cues. In one model, for example, a group of animals had to choose between two options-think of two places to find food. But the cues for each choice were not equally reliable, nor were they equally correlated. The scientists found that in these models, a group was more likely to choose the superior option than an individual. Common experience will make us expect that the bigger the group got, the wiser it would become. But they found something very different. Small groups did better than individuals. But bigger groups did not do better than small groups. In fact, they did worse. A group of 5 to 20 individuals made better decisions than an infinitely large crowd. The problem with big groups is this: a faction of the group will follow correlated cues-in other words, the cues that look the same to many individuals. If a correlated cue is misleading, it may cause the whole faction to cast the wrong vote. Couzin and Kao found that this faction can drown out the diversity of information coming from the uncorrelated cue. And this problem only gets worse as the group gets bigger.
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Couzin research was the starting point that co-inspired PaGMO from the very beginning. We invited him (and he came) at a formation flying conference for a plenary here in ESTEC. You can see PaGMO as a collective problem solving simulation. In that respect, we learned already that the size of the group and its internal structure (topology) counts and cannot be too large or too random. One of the project the ACT is running (and currently seeking for new ideas/actors) is briefly described here (http://esa.github.io/pygmo/examples/example2.html) and attempts answering the question :"How is collective decision making influenced by the information flow through the group?" by looking at complex simulations of large 'archipelagos'.
Bacteria grow electric wire in their natural environment - 1 views
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Bacterial wires explain enigmatic electric currents in the seabed: Each one of these 'cable bacteria' contains a bundle of insulated wires that conduct an electric current from one end to the other. Cable bacteria explain electric currents in the seabed Electricity and seawater are usually a bad mix.
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WOW!!!! don't want to even imagine what we do to these with the trailing fishing boats that sweep through sea beds with large masses .... "Our experiments showed that the electric connections in the seabed must be solid structures built by bacteria," says PhD student Christian Pfeffer, Aarhus University. He could interrupt the electric currents by pulling a thin wire horizontally through the seafloor. Just as when an excavator cuts our electric cables. In microscopes, scientists found a hitherto unknown type of long, multi-cellular bacteria that was always present when scientists measured the electric currents. "The incredible idea that these bacteria should be electric cables really fell into place when, inside the bacteria, we saw wire-like strings enclosed by a membrane," says Nils Risgaard-Petersen, Aarhus University. Kilometers of living cables The bacterium is one hundred times thinner than a hair and the whole bacterium functions as an electric cable with a number of insulated wires within it. Quite similar to the electric cables we know from our daily lives. "Such unique insulated biological wires seem simple but with incredible complexity at nanoscale," says PhD student Jie Song, Aarhus University, who used nanotools to map the electrical properties of the cable bacteria. In an undisturbed seabed more than tens of thousands kilometers cable bacteria live under a single square meter seabed. The ability to conduct an electric current gives cable bacteria such large benefits that it conquers much of the energy from decomposition processes in the seabed. Unlike all other known forms of life, cable bacteria maintain an efficient combustion down in the oxygen-free part of the seabed. It only requires that one end of the individual reaches the oxygen which the seawater provides to the top millimeters of the seabed. The combustion is a transfer of the electrons of the food to oxygen which the bacterial inner wires manage over centimeter-long distances. However, s
Accelerated search for materials with targeted properties by adaptive design - 0 views
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There has been much recent interest in accelerating materials discovery. High-throughput calculations and combinatorial experiments have been the approaches of choice to narrow the search space. The emphasis has largely been on feature or descriptor selection or the use of regression tools, such as least squares, to predict properties. The regression studies have been hampered by small data sets, large model or prediction uncertainties and extrapolation to a vast unexplored chemical space with little or no experimental feedback to validate the predictions. Thus, they are prone to be suboptimal. Here an adaptive design approach is used that provides a robust, guided basis for the selection of the next material for experimental measurements by using uncertainties and maximizing the 'expected improvement' from the best-so-far material in an iterative loop with feedback from experiments. It balances the goal of searching materials likely to have the best property (exploitation) with the need to explore parts of the search space with fewer sampling points and greater uncertainty.
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Higgs Boson Particles being sold on eBay ! - 0 views
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"Higgs Boson partices - guaranteed to satisfy! Need mass in your objects? Get some Higg Bosons!" "The Higgs Boson particles are SOLD WITH THE JAR! You may not be able to SEE the Higgs Boson particles unless you use a large hadron collider." "Q: Since it is, after all, the god particle; can you observe closely and tell use what religion it is?"
Coherent Schrödinger's cat still confounds - physicsworld.com - 1 views
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The famous paradox of Schrödinger's cat starts from principles of quantum physics and ends with the bizarre conclusion that a cat can be simultaneously in two physical states - one in which the cat is alive and the other in which it is dead. In real life, however, large objects such as cats clearly don't exist in a superposition of two or more states and this paradox is usually resolved in terms of quantum decoherence. But now physicists in Canada and Switzerland argue that even if decoherence could be prevented, the difficulty of making perfect measurements would stop us from confirming the cat's superposition.
Higgs hunters close in on their quarry - 1 views
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The first solid experimental evidence for the existence of the Higgs boson has been unveiled today by physicists working on the Large Hadron Collider (LHC) at CERN in Geneva. Members of the ATLAS experiment revealed evidence that the Higgs particle has a mass of about 126 GeV/c2. "By 2014/2015 we could have enough additional data to eliminate large classes of theories that attempt to explain the Higgs,"
Getting to the froth of the matter - physicsworld.com - 1 views
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Whether it is the frothy milk on your cappuccino, the soapy suds in your bath or the large-scale structure of the universe, foams have intrigued physicists for many years. Now, for the first time in a lab, an international group of scientists has made the Weaire-Phelan foam - which physicists believe is the lowest-energy structure for a foam formed of equal-volume bubbles.
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Does this mean that there is foam that is non regular that can have even less energy structure? "which physicists believe is the lowest-energy structure for a foam formed of equal-volume bubbles."
Laser gyroscope measures the Earth's 'wobble' - physicsworld.com - 2 views
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An international team of researchers have developed a new type of gyroscope that is the first to measure the "wobble" in the rotational axis of the Earth from a ground-based laboratory. Astronomers normally track this wobble by continuously monitoring the position of distant objects, such as quasars. But this new method will provide a much simpler and cheaper alternative to these large-scale astronomical readings, the scientists claim.
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is this of any use for spacecraft?
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mmm it's like saying that you can replace satellite tracking by accelerometers on-board satellites... for Leo: you'd better put an atomic gyro on a spacecraft these laser gyro are huge !
LHC trials proton-lead collisions - physicsworld.com - 0 views
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Physicists at CERN's Large Hadron Collider (LHC) are analysing the results of their first attempt at colliding protons and lead ions. Further attempts at proton-lead collisions are expected over the next few weeks. If these trials are successful, a full-blown experimental programme could run in 2012.
Invisibility cloaks shield the large and visible - physicsworld.com - 1 views
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Two independent groups of physicists have built invisibility cloaks that can shield large objects lying on a plane. These "carpet cloaks" are far closer to the intuitive idea of an invisibility cloak than devices previously built, they argue, because they hide objects that can be seen with the naked eye and do so at visible wavelengths. The cloaks are also relatively cheap and easy to make, being constructed from the natural material calcite.
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The team used a technique known as transformation optics to design their cloak.
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Tomas Tyc of Masaryk University in the Czech Republic, who was not a member of either group, thinks that the papers "describe important achievements in the area of experimental cloaking." But he maintains that a carpet cloak is quite different to a fully fledged Harry Potter-style invisibility cloak. He points out that a carpet cloak only really works when viewing an object – be it a rucksack or a sword on someone's back, for example – side on. Otherwise the object will appear flat but still be visible.
Migration of Planets Embedded in a Circumstellar Disk - 0 views
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Planetary migration poses a serious challenge to theories of planet formation...When multiple planets stir the disk, our simulations yield the new result that large-scale migration ceases. Thus, growing planets do not migrate through planetesimal disks....Although migration through a gaseous disk is an important issue for the formation of gas giants, we conclude that migration has little impact on the formation of terrestrial planets.
Access : Coherent emission of light by thermal sources : Nature - 0 views
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how "large" could these distances be? - ready for SPS?
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I don't think that the distance is the important criteria... It seems that the directivity is of the order of a laser one, so the divergence will be equivalent. Perhaps the important criteria is that the cost of these type of light sources could be cheaper...? and also perhaps what power transmission is achievable? It seems also that now that this concept could be used for to focus cheap lasers, instead of using complex optics in cd-rom players, etc... see http://news.softpedia.com/news/Highly-Directional-Semiconductor-Laser-Created-at-Harvard-90839.shtml
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