http://phys.org/ en-us Phys.org internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine. (Phys.org) —Quantum dot LEDs (QLEDs) are a promising technology for creating large-area displays that could have applications for TVs, cell phones, and digital cameras. So far, however, the highest efficiencies of QLEDs have fallen short of those of organic LEDs (OLEDs), another large-area LED technology. Now in a new study, researchers have developed a new type of QLED with an efficiency and luminance that are the highest reported to date and comparable to state-of-the-art phosphorescent OLEDs. The new QLED's external quantum efficiency of 18% more than doubles the current highest value of which the researchers are aware, which is 8%. The efficiency is also close to the theoretical maximum for any planar thin-film LED, which is 20%. http://phys.org/news287764572.html Physics Tue, 14 May 2013 15:40:01 EST news287764572 (Phys.org) —In today's wireless communication systems, the wireless signals are non-chaotic, meaning they have a well-defined period and frequency. Non-chaotic wireless signals are used in many applications, such as satellite communications, GPS navigation, cell phones, and Wi-Fi devices. However, as many people know first-hand, wireless systems usually have inferior performance compared to wired systems. The problem is due to physical impediments that the wireless signal faces in open space caused by the atmosphere, water, mountains, buildings, and other different media. Now in a new study, researchers have investigated how wireless communication could be implemented with chaotic signals, and found that chaotic signals could overcome some of these physical constraints and lead to superior performance. http://phys.org/news287642002.html Physics Mon, 13 May 2013 09:00:02 EST news287642002 (Phys.org) —One of the more controversial theories of quantum gravity, which attempts to unify quantum mechanics and general relativity, is semiclassical gravity, which was proposed in the 1960s. As its name suggests, semiclassical gravity involves a combination of quantum and classical components. Specifically, matter obeys the rules of quantum mechanics while gravity and the spacetime structure obey classical laws. Many physicists think that integrating quantum and classical systems in this way creates physical contradictions and mathematical inconsistencies. However, in a new paper, physicists have closely analyzed exactly how classical gravity might affect the quantum properties of macroscopic objects, and found that the effects of semiclassical gravity may be experimentally detectable with state-of-the-art technology. http://phys.org/news287213873.html Physics Wed, 08 May 2013 09:00:01 EST news287213873 Although eleventh-century Vikings did not have magnetic compasses at their disposal, it is thought that they could determine their orientation at sea using sun-compasses. Sun-compasses use the position of the sun's shadow to tell which way north is, and look somewhat similar to sundials, which use the position of the sun's shadow to tell the time of day. But the famous Viking-era wooden fragment that inspired the idea that Vikings used sun-compasses contains some lines that don't quite match scientists' interpretations. In a new study, a team of researchers has proposed that these flaws hint at the possibility that the instrument served a more sophisticated purpose than determining orientation, which was determining latitude. http://phys.org/news286551435.html Physics Tue, 30 Apr 2013 14:37:43 EST news286551435 (Phys.org) —While the natural world is replete with compounds that form the basis of many disease-fighting pharmaceuticals, it is also the case that humans and other mammals produce their own host-defense peptide-derived broad-spectrum antibiotics to combat bacterial and fungal infections. By attacking microbial cell membranes, these peptides prevent bacteria from developing rapid antibiotic resistance. While over 1,700 of these peptides are known, the structural and mechanical aspects of their functional activity have remained an unanswered question. Recently, however, scientists at Max Planck Institute for Biophysical Chemistry, Max Planck Institute for Developmental Biology, The University of Edinburgh, and other instiutions1 determined the X-ray crystal structure as well as solid-state nuclear magnetic resonance (NMR) spectroscopy, electrophysiology, and molecular dynamic (MD) simulations of human dermcidin (DCD), revealing its mechanism at atomic scale. The researchers conclude that their results may lead to the peptide structure-based design of second-generation antibiotics. http://phys.org/news286537497.html Chemistry Tue, 30 Apr 2013 10:45:17 EST news286537497 (Phys.org) —Mathematics is, in essence, an artificial language for precisely articulating theories about the physical world. Unlike natural language, however, translating different classes of mathematics can be difficult at best. Such is the case encountered in the attempt to unify general relativity and quantum theory, since they are expressed in differential geometry and functional analysis, respectively. That being said, spectral geometry – a field in mathematics which concerns relationships between geometric structures of manifolds and spectra of canonically defined differential operators – may resolve this long-standing quandary by allowing spacetime to be treated as simultaneously continuous and discrete, essentially relating the frequency-based ringing of the fabric of spacetime to its manifold-based shape. Recently, scientists at California Institute of Technology, Princeton University, University of Waterloo, and University of Queensland normalized and segmented spectral geometry into small, finite-dimensional steps. They then demonstrated their approach of calculating the shapes of two-dimensional objects from their vibrational spectra as being viable in two, and possibly more, dimensions. http://phys.org/news286449018.html Physics Mon, 29 Apr 2013 11:00:01 EST news286449018 (Phys.org) —The results of a new study support what many people intuitively know about winning political elections: the party that has a more connected voter network usually receives more votes. However, the study also found that, if the less connected network has even a small fraction of strongly committed voters, these voters have the ability to reverse the election outcome. The study demonstrates how multiple interacting and interdependent networks can be used to model and gain insight into real-world political elections, with the potential to influence future campaign strategies. http://phys.org/news286186785.html Technology Fri, 26 Apr 2013 10:10:01 EST news286186785 (Phys.org) —That Homo sapiens exhibits both cooperative and competitive behavior is a topic that continues to be the subject of ongoing discussion. In terms of cooperation, altruism (a selfless type of prosocial behavior in which an organism acts to benefit another at a cost to itself), has received significant attention from evolutionary biologists, neuroscientists, economists, psychologists, philosophers, social scientists, game theorists, and computer scientists. In particular, altruistic punishment – in which individuals who, at no apparent benefit (or even at a cost) to themselves, punish someone who has treated another unfairly – has been demonstrated in a range of studies. Recently, however, scientists at the University of Miami posited that the evidence for these results is possibly affected by experimental artifacts, and is therefore questionable. To address their hypothesis, the researchers designed and performed an experiment without such artifacts, finding that while victims punished offenders, witnesses did not – and moreover reacted with envy for ill-gotten gains rather than moralistic anger. In addition, a second experiment showed that previous evidence was due to what is known as affective forecasting error (inaccurate estimations of reactions to hypothetical situations). The scientists concluded that evidence supporting human altruistic punishment has been overstated. http://phys.org/news286186391.html Other Sciences Fri, 26 Apr 2013 09:13:40 EST news286186391 (Phys.org) —While everyone is familiar with water in the liquid, ice, and gas phases, water can also exist in many other phases over a vast range of temperature and pressure conditions. One lesser known phase of water is the superionic phase, which is considered an "ice" but exists somewhere between a solid and a liquid: while the oxygen atoms occupy fixed lattice positions as in a solid, the hydrogen atoms migrate through the lattice as in a fluid. Until now, scientists have thought that there was only one phase of superionic ice, but scientists in a new study have discovered a second phase that is more stable than the original. The new phase of superionic ice could make up a large component of the interiors of giant icy planets such as Uranus and Neptune. http://phys.org/news286086930.html Physics Thu, 25 Apr 2013 09:00:04 EST news286086930 (Phys.org) —Using an ink containing tiny graphene flakes, scientists have inkjet-printed graphene patterns that can be used for printing finely detailed, highly conductive electrodes. Although inkjet-printed graphene has been previously demonstrated, the graphene patterns printed in the new study are about 250 times more conductive than previous patterns. The printed graphene ink is also highly tolerant to bending stresses, with the ability to withstand folding with only a slight decrease in conductivity. http://phys.org/news286000280.html Nanotechnology Wed, 24 Apr 2013 08:40:01 EST news286000280 (Phys.org) —While previous research has shown that wind turbulence causes the power output of wind turbines to be intermittent, a new study has found that wind turbulence may have an even greater impact on power output than previously thought. The researchers modeled the conversion of wind speed to power output using data from a rural wind farm. The results showed that the intermittent properties of wind persist on the scale of an entire wind farm, and that wind turbines do not only transfer wind intermittency to the grid, but also increase it. The findings highlight the importance of fully understanding the physics of wind turbulence in order to ensure future grid stability. http://phys.org/news285597144.html Physics Fri, 19 Apr 2013 13:33:15 EST news285597144 (Phys.org) —Devices that harvest energy from the environment require specific environmental conditions; for instance, solar cells and piezoelectric generators require sunlight and mechanical vibration, respectively. Since these conditions don't exist all the time, most energy harvesters don't generate a constant stream of electricity. In order to harvest ubiquitous energy continuously, researchers have designed and fabricated a hybrid energy harvester that integrates a solar cell and piezoelectric generator, enabling it to harvest energy from both sunlight and sound vibration simultaneously. http://phys.org/news285412932.html Nanotechnology Wed, 17 Apr 2013 11:00:01 EST news285412932 (Phys.org) —In most demonstrations of quantum teleportation between remote atomic qubits, the atoms exist in free space. In a new study, scientists have discovered that trapping the atoms in optical cavities can overcome some of the previous obstacles facing matter teleportation, which enables an improvement in efficiency of almost 5 orders of magnitude and teleportation across a record-breaking distance of 21 m. These improvements in quantum teleportation could open the doors to realizing quantum networks with many nodes for teleporting qubits to various destinations. http://phys.org/news285329545.html Physics Tue, 16 Apr 2013 12:00:01 EST news285329545 (Phys.org) —At very low temperatures, near absolute zero, multiple particles called bosons can form an unusual state of matter in which a large fraction of the bosons in a gas occupy the same quantum state—the lowest one—to form a Bose-Einstein condensate (BEC). In a sense, the bosons lose their individual identities and behave like a single, very large atom. But while previously BECs have only existed below a critical temperature, scientists in a new study have shown that BECs can exist above this critical temperature for more than a minute when different components of the gas evolve at different rates. http://phys.org/news284792079.html Physics Wed, 10 Apr 2013 09:00:01 EST news284792079 (Phys.org) —One of the cornerstones of quantum physics is the Schrödinger equation, which describes what a system of quantum objects such as atoms and subatomic particles will do in the future based on its current state. The classical analogies are Newton's second law and Hamiltonian mechanics, which predict what a classical system will do in the future given its current configuration. Although the Schrödinger equation was published in 1926, the authors of a new study explain that the equation's origins are still not fully appreciated by many physicists. http://phys.org/news284638321.html Physics Mon, 08 Apr 2013 11:30:01 EST news284638321 (Phys.org) —Ants have long been known to choose the shortest of several routes to a food source, but what happens when the shortest route is not the fastest? This situation can occur, for example, when ants are forced to travel on two different surfaces, where they can walk faster on one surface than on the other. In a new study, scientists have found that ants behave the same way as light does when traveling through different media: both paths obey Fermat's principle of least time, taking the fastest route rather than the most direct one. Besides revealing insight into ant communities, the findings could offer inspiration to researchers working on solving complex problems in robotics, logistics, and information technology. http://phys.org/news284034410.html Other Sciences Mon, 01 Apr 2013 11:27:52 EST news284034410 (Phys.org) —In 1936, Alan Turing showed that all computers are simply manifestations of an underlying logical architecture, no matter what materials they're made of. Although most of the computer's we're familiar with are made of silicon semiconductors, other computers have been made of DNA, light, legos, paper, and many other unconventional materials. http://phys.org/news283681065.html Physics Thu, 28 Mar 2013 10:10:01 EST news283681065 (Phys.org) —By growing 2D nanosheets along the surface of a 1D nanowire, scientists have synthesized a new 3D nanoscale heterostructure that they call—for appropriate reasons—"shish kabobs." Due to the integration of the two dimensionalities, the new structures could have a wide variety of applications, such as for solar energy conversion, energy storage, and photonics. http://phys.org/news283606040.html Nanotechnology Wed, 27 Mar 2013 12:40:02 EST news283606040 (Phys.org) —While most people know that using a cell phone means that the phone's location is being recorded, a new study has revealed just how little information is required to determine an individual's personal identity. By analyzing 15 months of cell phone mobility data from 1.5 million people, researchers have found that only four spatio-temporal points (an individual's approximate whereabouts at the approximate time when they're using their cell phone) are all that's needed to uniquely identify 95% of the individuals. The study has implications for modifying privacy law in order to keep pace with technological advances. http://phys.org/news283434206.html Technology Mon, 25 Mar 2013 13:00:03 EST news283434206 (Phys.org) —Scientists have found evidence for the existence of magnetic superatoms—small, compact clusters of atoms whose electrons occupy a set of orbitals around the entire cluster rather than around the individual atoms. If scientists can synthesize superatoms with magnetic properties, then one day they may use them to create new spin-dependent electronics. http://phys.org/news283168346.html Physics Fri, 22 Mar 2013 12:00:04 EST news283168346 (Phys.org) —Scientists have a great deal of evidence to support the fact that the universe contains much more baryonic matter than baryonic anti-matter, a phenomenon known as baryon asymmetry. Baryons, which are defined as being made of three quarks, include protons and neutrons and make up the bulk of the atomic matter that we're familiar with in everyday life. But much less is known about the possibility of a lepton asymmetry, in which there are unequal amounts of leptons and anti-leptons in the universe. The best known examples of leptons are electrons and neutrinos. Neutrinos in particular are much harder to detect than baryons because they're much lighter, and so much less energetic. http://phys.org/news283083710.html Physics Thu, 21 Mar 2013 11:40:01 EST news283083710 (Phys.org) —As is the case in all areas of science, our understanding of evolutionary biology is… well, evolving. Two such areas are macroevolution (any evolutionary change at or above the level of species – that is, on a scale of separated gene pools) and microevolution (any evolutionary change below the level of species, such as the effect of changes in allele frequency on phenotype). Interestingly, macroevolution and microevolution can be seen as describing fundamentally identical processes on different time scales. Through their divergent effects on population genetics, sexual reproduction strategies could significantly influence phenotypic expression – but the impact of mating system transitions has not been well understood. Recently, however, scientists at Cornell University have shown that the repeated, unidirectional transition from self-incompatibility to self-compatibility (increased inbreeding) leads to the evolution of an inducible (a gene whose expression is responsive to environmental change) – as opposed to a constitutive (a gene that is always expressed) – strategy of plant resistance to herbivores, as well as a strategy in which the loss of self-incompatibility is associated with the evolution of increased specificity in induced plant resistance. Moreover, they demonstrate that these two defense strategies represent evolutionary alternatives, leading to a macroevolutionary tradeoff whose magnitude is dependent on the mating system. The scientists conclude that the evolution of sexual reproductive variation may have profound effects on plant–herbivore interactions, suggesting a new hypothesis for the evolution of two primary plant defense strategies. http://phys.org/news282825307.html Biology Mon, 18 Mar 2013 11:50:01 EST news282825307 (Phys.org) —In a new study, physicists have teleported photonic qubits made of pairs of entangled photons that are generated by an LED containing an embedded quantum dot. The novel set-up has advantages compared to the conventional method of generating entangled photons using a laser, and could lead to a simplified technique for implementing quantum teleportation in quantum information applications. http://phys.org/news282559863.html Physics Fri, 15 Mar 2013 10:30:01 EST news282559863 (Phys.org) —Most batteries, supercapacitors, and other energy storage devices are based on a sandwich structure, where two electrodes face each other and the charge flows between them. However, when these structures are folded or bent, the electrodes can easily fracture or the device can short-circuit if the electrodes come in direct contact. In a new study, researchers have come up with a new design for energy storage devices that is both flexible and semitransparent, in which the electrodes are fabricated on the same two-dimensional plane in a novel comb-teeth structure. http://phys.org/news282309782.html Nanotechnology Tue, 12 Mar 2013 12:40:02 EST news282309782 (Phys.org) —In the strange world of quantum mechanics, the vacuum state (sometimes referred to as the quantum vacuum, simply as the vacuum) is a quantum system's lowest possible energy state. While not containing physical particles, neither is it an empty void: Rather, the quantum vacuum contains fluctuating electromagnetic waves and so-called virtual particles, the latter being known to transition into and out of existence. In addition, the vacuum state has zero-point energy – the lowest quantized energy level of a quantum mechanical system – that manifests itself as the static Casimir effect, an attractive interaction between the opposite walls of an electromagnetic cavity. Recently, scientists at Aalto University in Finland and VTT Technical Research Centre of Finland demonstrated the dynamical Casimir effect using a Josephson metamaterial embedded in a microwave cavity. They showed that under certain conditions, real photons are generated in pairs, and concluded that their creation was consistent with quantum field theory predictions. http://phys.org/news281960445.html Physics Fri, 08 Mar 2013 10:20:57 EST news281960445 (Phys.org) —A complex system can, in principle, be observable – that is, the system's complete internal state can be reconstructed from its outputs, which would ostensibly involve describing in complete quantitative detail all of its internal state variables at once. In an actual experiment, however, such measurement is typically beyond our reach, and so is limited to a smaller number of those variables. Referred to as sensors (or sensor nodes), these key variables can be used to make the complete system observable. Recently, scientists at Northeastern University and MIT devised a graphical approach that first derives the math­e­mat­ical equa­tions describing a complex system's dynamics, and then determines the key sensors for that system. Moreover, when applying their approach to biochemical reaction systems, the researchers discovered that the derived sensors were both necessary and sufficient to describe the complete system. The scientists conclude that their findings allow a systematic exploration of many diverse natural, technological and socioeconomic systems. http://phys.org/news281856591.html Physics Thu, 07 Mar 2013 05:30:22 EST news281856591 (Phys.org) —By some estimates, continued growth in hydraulic fracturing (or "fracking"/"fraccing") could put the US on the path to self-sufficiency in energy over the next few decades. Yet despite the potential economic benefits, fracking has also generated controversy due to the unknown long-term consequences of all the drilling, pumping, fracturing, and extracting processes involved. Now, two scientists have identified several important scientific challenges encountered in fracking that can be addressed with physical chemistry, which could lead to improved fracking techniques. http://phys.org/news281701080.html Chemistry Tue, 05 Mar 2013 10:50:01 EST news281701080 (Phys.org)—The presence of quantum coherence in photosynthesis in plants, bacteria and marine algae at ambient temperatures is well-established. Two such effects that appeared to be unrelated – enhanced solar cell efficiency and population oscillations in photosynthetic antennae – have been detected in natural and artificial light-harvesting systems. Recently, however, scientists at Texas A&M University and University of California-Irvine have shown that these effects are, in fact, deeply connected: Both arise from the same population–coherence coupling term that is noise-induced and does not require coherent light – meaning that these effects will take place under the incoherent conditions of natural solar excitation. By focusing on the fact that charge separation in light-harvesting complexes occurs in a pair of tightly coupled chlorophylls (the so-called "special pair") at the core of plant, bacteria and algae photosynthetic reaction centers (RCs), and using an analogy between the energy level schemes of the core of the reaction center (including the special pair) and those of the laser/photocell quantum heat engines (QHEs), the scientists were able to demonstrate that both effects operate as QHEs that convert solar photon energy into useful work. The scientists predict that when coexisting they can potentially increase charge separation yield by 27%, and conclude that their findings suggest the viability of artificial solar energy devices based on biomimetic quantum heat engine architectures. http://phys.org/news281186550.html Physics Wed, 27 Feb 2013 11:23:45 EST news281186550 (Phys.org)—The world of rechargeable batteries is full of trade-offs. While lithium-ion (Li-ion) batteries are currently the most commercially successful, their low energy density doesn't allow for a long driving range. They are also very expensive, often accounting for half the price of electric vehicles. One alternative is lithium-sulfur (Li-S) batteries, which are attractive for their high gravimetric energy density that allows them to store more energy than Li-ion batteries. And although they still use some lithium, the sulfur component allows them to be much cheaper than Li-ion batteries. But one of the biggest drawbacks of Li-S batteries is their short cycle life, which causes them to lose much of their capacity every time they are recharged. http://phys.org/news281008430.html Nanotechnology Mon, 25 Feb 2013 09:54:06 EST news281008430 (Phys.org)—Although the LHC has often been called the largest machine in the world, that title may be more appropriately given to something much more familiar: power grids. Consisting of thousands of generators and substations linked across thousands of miles, these networks form the backbone of society in developed countries. Yet most of the grids that power our modern economy are based on technology from the 1960s, even though power demands have changed dramatically since then. As a result of the additional strain, power grids have been failing more often, causing billions of dollars in business losses. http://phys.org/news280749451.html Physics Fri, 22 Feb 2013 10:20:02 EST news280749451