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An entangled state of two quantum bits (qubits) can be created and stabilized using interactions that are normally thought to be detrimental, according to two international groups of researchers. While the groups studied two
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The Maya refer to both a modern-day people who can be found all over the world as well as their ancestors who built an ancient civilization
Caption George Washington Carver, circa 1910. Credit: Public domain.
George Washington Carver was a prominent American scientist and inventor in the early 1900s. Carver developed hundreds of products using the peanut,
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(ISNS) -- With the wintry holiday season now upon us, icicles will soon join luminous and festive decorative lights along roofs and rafters. Natural icicles are
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Jeff Nesbit was the director of public affairs for two prominent federal science agencies. This article was adapted from one that first appeared in U.S. News & World Report.
Credit: U.S. Fish and Wildlife Service | Alligator River National Wildlife Refuge
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Brown cows may not actually make chocolate milk, but pink silkworms do produce pink skeins of silk, a team of scientists has discovered. To see if they could produce pre-dyed silk—silk that comes colored, straight from the
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"You can ban drugs, but you can't ban chemistry," Mike Power, author of Drugs 2.0, explains in this talk at the HIT Hot Topics Conference. And he gives a personal, investigative story to prove it.
Last summer, the National Institutes of Health announced that it’s phasing out experiments on chimpanzees. All but 50 of its 451 chimps will go to sanctuaries, and it won’t breed the remainder. The change is based on its
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FOREST MAP A new tool layers satellite images onto a Google map to show changes in forest cover.
M. Hansen et al/Science 2013
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The protein structures of strains of the H7N9 virus (transmission electron micrograph shown) still appear to be better adapted to attaching to bird cells instead of human cells, suggesting that an immediate global pandemic is
SUPER SWIRL A sharp boundary defines the six-sided cloud pattern that spans about 30,000 kilometers across Saturn’s north pole, as seen in this new false-color image from the Cassini spacecraft.
(Phys.org) —When Harry Potter walks around with a visible head but an invisible body, the performance seems strongly rooted in fantasy. But in a new study, scientists have designed and fabricated an invisibility cloak
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While the Oxford University Press honored "selfies" as its 2013 Word of the Year, celebrating those quickly snapped self-portraits, Merriam-Webster is taking
A chimpanzee mother with her baby. Credit: neelsky, Shutterstock
In a series of lawsuits, a rights group is asking a judge this week to free four chimpanzees held in captivity in New York. And if they're successful, it
The new open-source 3D metal printer cost less than $1200 to make. Credit: Michigan Tech's Open Sustainability Technology Lab
Anyone with access to a welder and the Internet soon could make his or her own replacement
Wind energy production increased by 16 percent in the United States from 2011 to 2012. Credit: S.R. Lee Photo Traveller | Shutterstock
Elliott Negin is the director of news and commentary at the Union of Concerned
Booty call relationships are based on spur-of-the-moment sex. Credit: Refat, Shutterstock
At long last, science has defined "booty call."
And unsurprisingly, the point of these casual relationships is (drumroll, please)
(Phys.org) —Material design usually follows what is known as the Edisonian method, a traditional process characterized by trial-and-error discovery rather than a systematic theoretical approach. While this may be
(Phys.org) —In the world of biomedical science, optical microscopy rules – and nonlinear optical microscopy, which uses ultrashort pulse lasers as the illumination source, allows researchers to glean much greater
(Phys.org) —It's a first: researchers have built the first artificial-heart-like pump that is powered by microbial fuel cells fed on human urine. But instead of being used as a prosthetic device for human patients
Credit: Raw milk photo via Shutterstock
Marc Bekoff, emeritus professor at the University of Colorado, Boulder, is one of the world's pioneering cognitive ethologists, a Guggenheim Fellow, and co-founder with Jane
Computers have changed the face of chess, and put Carlsen in a winning position. Credit: EPA/Stringer.
This article was originally published at The Conversation. The publication contributed the article to
This time-lapse space wallpaper shows Comet ISON approaching and leaving during its slingshot around the sun — represented by the white circle — on Nov. 28, 2013. The ISON images clearly outline the curve of the comet's
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NASA has revealed a stunning natural-color panoramic mosaic of Saturn, along with its rings and moons, as they'd look to human eyes. The majestic image, which also shows Earth, Venus and Mars, was snapped by NASA's Cassini
Oil and water don't mix: it's an old saying, but it's never more true than when you're talking about a pot of hot cooking oil and the moisture condensed on the surface of a frozen turkey. it's pretty incredible the amount of
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I had actually never seen this before, but maybe that's because I don't hang out with jerks? In any case, apparently if you hit someone's open beer bottle firmly at its mouth, it will
The East Coast may be getting a little damp at the moment, but the subarctic region of Canada has seen a decrease in snowfall in recent years. Because of that, the lakes in the area are drying up significantly, according to a
It can be hard enough to get grown adults to work together. But vervet monkeys are putting us human primates to shame. In a study back in March, researchers had these monkeys play a game called forbidden circle--at least
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Discover how the Brazilian National Research and Education Network is using ultra-high definition video footage of surgical procedures to help train health professionals across the country. This 'telemedicine' technology also
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Petigram is a social media app that lets you focus on sharing silly pet pictures. Credit: Cat in sweatshirt image via Shutterstock
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This article was originally published at The Conversation. The publication contributed the article to LiveScience's Expert Voices: Op-Ed & Insights.
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Scientists have used a single atom trapped in an optical resonator to detect the presence of a reflected photon without destroying that packet of light. Credit: MPQ, Quantum Dynamics Division.
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Ever get that feeling you're being watched? Well, if you're a dog-owner, you may have a point. Dogs are able to watch people's interactions with one another to determine who holds yummier treats, according to a new
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A team of researchers in the US has achieved spin coherence times of more than 200 µs in nitrogen vacancy (NV) centres in tiny "nanodiamonds", shattering the previous record for coherence times in this material. The nanodiamonds were made using a new mask and ion etching process that the team believes could be used to develop real-world applications of NV centres including magnetic-resonance probes and quantum computers.
The NV centre in nanodiamond could be ideal for use in a host of future quantum technologies, including quantum computing and nanoscale sensing. However, most nanodiamonds available today contain a high density of paramagnetic impurities that make the electron spins in NV centres extremely fragile – they cannot hold their spin direction for very long (microseconds at most), which means that they are unable to store quantum information for any practical length of time.
Atomic impurities, or defects, in natural diamond lead to the colour seen in pink, blue and yellow diamonds. One such defect, the NV, occurs when two neighbouring carbon atoms in diamond are replaced by a nitrogen atom and an empty lattice site. NVs in nanodiamonds could be ideal as biological probes because they are non-toxic, photostable and can easily be inserted into living cells. They are also capable of detecting the very weak magnetic fields that come from electronic or nuclear spins, and so can be used as highly sensitive magnetic resonance probes capable of monitoring local spin changes in a material over distances of a few tens of nanometres. And, in contrast to conventional magnetic resonance imaging techniques in biology in which millions of spins are required to produce a measurable signal, the NV defects can detect individual target spins with spatial precision measured in nanometres.
Annoyingly short coherence time
The main problem until now, however, was that the spin coherence time in these NVs was annoyingly short because of the high concentration of paramagnetic impurities (namely nitrogen) in diamond nanocrystals grown by conventional high-pressure high-temperature (HPHT) processes. A team led by Dirk Englund of the Massachusetts Institute of Technology (MIT) has now developed a top-down fabrication technique using a self-assembling porous metal mask and reactive ion etching process that produces extremely pure nanocrystals devoid of paramagnetic impurities. These nanocrystals contain NVs that are able to preserve their spin states for as long as 210 µs.
The defects also have record magnetic field sensitivities of 290 nT Hz–1/2, which means that they can be used as magnetic field probes that have a diameter of just 50 nm. "And that is not all: the NVs can be produced in their billions or more per shot, without much effort on our part, thanks to the simple 'self-guiding' or porous metal mask we employed," MIT team member Matthew Trusheim said.
Single photon sources and solid-state qubits
As well as being ideal as magnetic field sensors, the NVs might be placed in photonic structures and used as single photon sources or as solid-state quantum bits (qubits) entangled with photons, he adds. Quantum computers exploit the counterintuitive idea that tiny objects can exist in more than one state at the same time. Rather than processing classic bits – which are either 0 or 1 – such devices instead manipulate qubits that can be 0 and 1 at the same time. Vast numbers of logic operations could then be possible in parallel, making these computers theoretically far faster than ordinary machines.
Until now, qubits made from nanodiamond NVs were incredibly fragile and the quantum information they held was rapidly destroyed by interactions with noise in the surrounding environment. The new result, published in Nano Lett. DOI: 10.1021/nl402799u, could go a long way in changing all this.
Gold and palladium mask
The researchers made their highly pure nanocrystals of diamond by first depositing a metal mask (made of gold and palladium) onto a high-purity bulk diamond substrate. The mask self-assembles into droplets that are tens of nanometres in size. "Next, we used an oxygen plasma etch, where reactive ions are accelerated onto the substrate surface to remove the diamond," explaind Trusheim. "The metal mask blocks the incoming ions, forming small regions where the diamond is preserved. These regions are then removed mechanically and become our nanodiamond."
The team, which includes scientists from Columbia University, the City College of New York and the University at Albany-State of New York, says that it would now like to use these NV-fluorescent nanodiamonds in real sensing applications. "For example, they could be used to detect the electric fields coming from neural action potentials in the body, or to detect magnetic proteins in living cells," says Trusheim. "We are also integrating these diamond structures into photonic networks to efficiently interface photonic qubits with spin qubits," he reveals.
An entangled state of two quantum bits (qubits) can be created and stabilized using interactions that are normally thought to be detrimental, according to two international groups of researchers. While the groups studied two different physical systems, they have both shown that an entangled quantum system can be produced and maintained by coupling it to an environment that dissipates energy.
Entanglement is a purely quantum-mechanical phenomenon and that plays a crucial role in quantum-information systems. It allows two particles, such as photons or electrons, to have a much closer relationship than predicted by classical physics, and it is this relationship that could be exploited in quantum computers and cryptography. Physicists are keen to create and maintain entangled states in a variety of quantum systems, but a common problem that arises while creating these states is decoherence – the destruction of entanglement that occurs when a quantum system interacts with its surroundings. To avoid this, researchers try to keep an entangled system completely isolated from its environment – a difficult task.
But in recent years, new theoretical work has shown that the dissipative interactions with the environment could instead be used to preserve coherence, and the method has already been used to stabilize the state of a single qubit. Now though, the two research groups have gone one step further by actually using dissipation to create and sustain an entangled state in two different systems – one team uses ions, while the other uses superconducting qubits.
Anders Sørensen and Florentin Reiter at the University of Copenhagen, along with Nobel laureate David Wineland, John Gaebler, and colleagues at the National Institute of Standards and Technology (NIST) in the US produced a stable entangled state between two trapped beryllium ions. They used a set of tailored interactions including "sympathetic cooling" by two magnesium ions in the same trap.
The ions' spins were entangled using two ultraviolet laser beams and induced to "leak" any "unwanted" quantum states to the environment through continuous application of microwaves and one laser beam. "The simple explanation is that it is similar to so-called optical pumping. The two qubits can be in four different states and one of them is the entangled state that we want," explains Sørensen. "If they are in any of the three undesired states, a laser puts them to an excited state from which they decay down again." This excitation is done until all the qubits end up in the desired state, where carefully chosen interactions and resonance conditions ensure that the excitation out of the state is suppressed.
The researchers found that after 12 ms, the spins were still highly entangled. "In principle, you can prepare a dissipative state where you are truly in a steady state so that the lifetime is as long as you wish," says Sørensen. This was almost the case in the team's experiment, but there is a small leak that the researchers do not correct. The team estimates that the lifetime of the entanglement is closer to 84 ms, which is very long compared with any other timescale in the experiment. The qubits approached the target state within a few milliseconds and were found to be in the correct entangled state 75% of the time. By applying about 30 repetitions of their excitation technique, the scientists boosted the success rate to 89% in a separate experiment.
According to Sørensen, the team purposefully designed its system so that it could be scaled up to include more atoms – something that could allow quantum computation. The researchers current experiment also let them investigate whether the method of allowing the system to talk to the environment actually represents an advantage for such real experiments.
Sørensen admits that, for now, the dissipative processes tend to be a bit slower than the more commonly used quantum gate – the basic building block of a quantum circuit that operates on a small number of qubits – but not necessarily much slower. He told physicsworld.com that one benefit of the new dissipative-state preparation is that the researchers can "now really begin to investigate whether there is an advantage of using dissipation as compared to gates. For the concrete system that we used, you probably could have done better with gates, but we can see that there are other scenarios such as optical cavities or if you have fluctuating lasers where using dissipation really helps."
The other team to achieve entanglement using dissipation included Shyam Shankar and Michel Devoret at Yale University, along with other colleagues. Their qubits are superconducting circuits, used along with a microwave cavity that serves as the dissipative reservoir. Shankar explains that, normally, a measurement-based feedback system is used to create entanglement. That involves first measuring the state of the qubit system with high fidelity, then using real-time electronics to determine whether the system is in the desired state or not. If it is not, a control drive would be applied to the system to bring it back to the desired state. Instead, the team uses an "autonomous" feedback scheme that does not require a measurement process to maintain coherence. The researchers apply six continuous drives (tones at carefully chosen microwave frequencies) combined with a specifically engineered coupling between the qubits and the dissipative reservoir. The researchers have engineered their system such that, in the presence of these drives, the ground state of the effective driven system is an entangled state.
Quantum building blocks
The fidelity of the entanglement is determined by the ratio of the feedback rate to the error rate. Currently, the researchers' entangled state was maintained with an average fidelity of 67%, for a maximum of 500 μs. "This time is essentially indefinite...we could have taken the data for a longer time if we wanted to. The entangled state that we stabilize is, of course, a building block to make more complicated multi-qubit entangled states that are required for quantum-information processing," says Shankar, further explaining that this method could allow for a "fully error-corrected logical qubits to be developed in the future".
"Our autonomous method using dissipation eliminates this external feedback loop and is thus simpler to implement," says Shankar. "We also do not have to worry about the latency of an external loop; in fact, the intrinsic dissipation of the system can correct the errors faster than any external loop could." But he also points out that such an autonomous-feedback strategy has to be tailored to the particular system used and the particular state one is trying to stabilize, making it difficult to create any kind of general protocol.
In the coming months, Shankar's team plans to combine the autonomous approach along with an external measurement-based feedback loop to get the best of both worlds. "The simplicity and quick response of autonomous feedback with the flexibility and reliability of measurement-based feedback," says Shankar. On the other hand, Sørensen and colleagues are looking at extending their method to multi-particle entanglement so that they can see just how well and how many qubits they can entangle.
A re-evaluation of a 2005 measurement of the lifetime of the neutron has deepened the mystery of why two different experimental techniques yield two different neutron lifetimes. After recalibrating a key part of their "beam" experiment, physicists in the US confirmed that their value for the neutron lifetime is 8 s longer than that determined by others who had done a "bottle" experiment. What is more, this latest result puts the statistical significance of the discrepancy at nearly 4σ, making it unlikely to be a random anomaly.
While neutrons in stable nuclei can exist for an eternity, a free neutron hangs around for about 15 min before it decays via the weak interaction to a proton, an electron and an antineutrino. A precise measurement of the neutron's lifetime is important for calculating the rates at which lighter elements were formed immediately after the Big Bang in a process called nucleosynthesis. An extremely good lifetime measurement could also reveal new physics beyond the Standard Model of particle physics.
There are currently two experimental strategies for measuring the lifetime. The bottle method involves trapping neutrons in some kind of container and counting the proportion remaining after a fixed time. The beam method involves monitoring a beam of neutrons and measuring the number of the particles that decay to protons as it passes through a particular volume of space. The systematic errors that could occur in each experiment are different and therefore physicists would be confident in a lifetime value that both techniques agree on.
Bottle and beam disagree
But bottle and beam experiments do not agree. The beam method seems to give a lifetime about 8 s longer than the bottle method, and this discrepancy is significant when compared with the uncertainties of the experiments.
The beam-method measurement with the lowest uncertainty was made in 2005 by Jeff Nico and colleagues at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland. The systematic error on this measurement was ±3.2 s, and this was dominated by the uncertainty in the number of neutrons in the beam. Counting neutrons requires a material that, on absorption of a neutron, produces a detectable signal. While a high-intensity neutron beam is needed to provide a reasonable number of neutron decays, absorbing the entire beam would overwhelm the neutron counter. Instead, the researchers used a thin layer of lithium-6 that absorbs only a small proportion of incident neutrons. Knowing this proportion exactly was vital to calculate the lifetime accurately.
New and improved calibration
In 2005 the NIST researchers estimated the absorption probability from the lithium-6 neutron-capture cross-section and the mass of the neutron absorber. Now, Nico has teamed up with Andrew Yue and others to calibrate the same absorber to an accuracy of within 0.05%. This was done by placing the device in a lower-intensity neutron beam and counting the number of neutrons it detected. Another detector called Alpha-Gamma was located downstream from the device, where it measured the entire remaining neutron flux. By comparing the two values, the team could work out almost exactly the proportion of neutrons that its detector had absorbed in the 2005 experiment.
This new information allowed the physicists to reduce the uncertainty of their original neutron-lifetime measurement from ±3.2s to ±1.9s. It also led to a small increase in the value of the lifetime. Consequently, the best available beam and bottle measurements now differ by 3.8σ, rather than the 2005 value of 2.9σ. The researchers are now planning to re-run the entire experiment to try to minimize the errors closer to those quoted for the bottle measurements.
Another decay branch?
The most precise lifetime measurement to date was also made in 2005 by Anatoli Serebrov and colleagues at the St Petersburg Nuclear Physics Institute in Russia. This experiment was done using the bottle method at the Institut Laue-Langevin ultracold neutron source in Grenoble, France. Serebrov points out that, in principle, the discrepancy in measured lifetimes could be explained by another branch of neutron decay that does not produce a proton. Although discovering such a decay channel would be exciting for physicists, Serebrov points out that current theories do not predict an additional decay.
Peter Geltenbort of the ILL is impressed with the latest results from NIST and looks forward to further refinements in both beam and bottle measurements. "Both experiments need to be repeated, and both need to come to an accuracy of below 1 s," he says. "Then one can talk again about whether there is some completely new physics." Forthcoming experiments using the bottle technique will be able to count protons emitted from the decaying neutrons as well as recording how many neutrons survive after a given time, he says: "This apparatus will allow you to measure the lifetime of the same ensemble of neutrons by two completely different methods."
Metamaterials offer route to room-temperature superconductivity
A new way of making high-temperature superconductors that is based on metamaterials has been proposed by physicists in the US. Their plan involves combining a low-temperature superconductor with a dielectric material to create a metamaterial that is a superconductor at much higher temperatures than its constituent materials. The team is now looking at testing its proposal in the lab and is hopeful that its work could offer a route to creating a superconductor that operates at room temperature.
Ever since the first high-temperature superconductor was discovered nearly 30 years ago, physicists have searched in vain for a material that remains a superconductor at room temperature. But despite a massive effort, physicists have not been able to create a superconductor that endures at temperatures higher than about 140 K, which is still 150 degrees below room temperature.
Now Vera Smolyaninova of Towson University and Igor Smolyaninov of the University of Maryland have proposed a new approach to creating a superconductor with a high critical temperature (Tc) – the temperature above which the material ceases to be superconducting. Their proposal involves creating man-made structures called metamaterials, which can be engineered to have electromagnetic properties that are not normally found in nature. This includes negative indices of refraction, which have been used to create devices such as invisibility cloaks and super lenses.
The pair's proposal is inspired by a description of superconductivity that was derived in 1973 by the Russian physicist David Kirzhnits and colleagues. Kirzhnits' approach is complementary to the conventional theory of superconductivity and it points out that the strength of the interaction between electrons in a superconductor is inversely proportional to the dielectric response (ε) of the material.
Conventional superconductivity arises when there is an attraction between electrons, causing them to form pairs. If a metamaterial can be engineered with a small and negative value of ε, it would have a larger attractive interaction between electrons and therefore stand a good chance of being a superconductor with a relatively high Tc.
In a preprint on the arXiv server, Smolyaninova and Smolyaninov argue that the ε-near-zero (ENZ) approach to designing metamaterials could offer a blueprint for creating a material with the appropriate value of ε. ENZ metamaterials are mixtures of metallic and dielectric components and in their proposal the metal is also a conventional superconductor – these are metals such as lead and mercury that have Tc values below 10 K.
The ENZ metamaterial proposed by the researchers involves making a superconductor with random "inclusions" of dielectric material. Smolyaninova told physicsworld.com that a possible candidate for the dielectric is the ferroelectric material strontium titanate, which can be made in nanoparticle form. The sizes of the inclusions and typical distances between them must be smaller than the correlation length between electron pairs in the superconductor – which is about 100 nm.
Another design proposed by the team is a "hyperbolic" metamaterial in which the desired ε is engineered using alternating layers of metallic and dielectric materials. Indeed, the researchers point out that typical high-Tc superconductors do share some properties with hyperbolic metamaterials. Again, the metal would be a conventional superconductor.
"We are working on actual metamaterial designs and preparing actual experiments now," Smolyaninova said. She adds that the ENZ design would be easier to implement than the hyperbolic metamaterial.
Smolyaninova is hopeful that metamaterial superconductors could be made with Tc values above the boiling temperature of liquid nitrogen (77 K). This would make them appropriate for use in systems that currently use high-Tc superconductors.
Improved earthquake early-warning system could be used worldwide
Geophysicists in the US have developed a new way of calculating the magnitude of an imminent earthquake by making better use of measurements of the compression waves produced early in the event. They say that the technique could be used to create a better early-warning system for earthquakes that could be used worldwide.
The majority of earthquake damage is caused by S-waves, which oscillate perpendicular to their direction of travel through the Earth, and by waves that occur on the surface. However, these are preceded by much faster-moving compression waves (called P-waves) that oscillate in the direction of travel and cause minimal damage. By making careful measurements of arriving P-waves, seismologists can get some idea of the strength of the impending earthquake. While this only gives officials tens of seconds to react, it is enough time to take some protective action such as slowing down high-speed trains, switching off gas mains and even warning the public to seek shelter.
Amplitude, period or both?
Current early-warning schemes make use of two properties of P-waves: the displacement amplitude of the P-wave's vertical component (Pd) and maximum predominant period of the P-wave (τpmax). To understand how best to use these measurements, Huseyin Serdar Kuyuk and Richard Allen of the University of California, Berkeley looked at real-life data recorded from 1992 earthquakes processed by California's real-time Earthquake Alarm Systems. They also looked at 174 earthquakes in California and Japan that have already been used in early-warning calibration studies. The earthquakes they studied varied in magnitude (M) from 0.2–8, with M = 8 being a major earthquake.
The team used these data to test five different methods for calculating Earthquake magnitude. The techniques use either Pd, τpmax or both to make their predictions. Some of the methods are already used in early-warning systems and one is a new technique developed by the researchers. The team found that its new technique – which is based on Pd measurements alone – gave the most accurate and robust estimate of earthquake magnitude. In contrast, methods that used τpmax did not do a good job of predicting the magnitudes of small earthquakes (M < 3). They were also less accurate than Pd-based techniques for larger magnitude events.
Kuyuk and Allen's technique differs from the others tested in that it was formulated using Pd data from earthquakes that happened around the world, rather than earthquakes occurring in just one region. This knowledge could potentially now be applied to improve the accuracy of earthquake early-warning networks worldwide.
"The results of this study should further improve the performance of the earthquake early-warning system currently being developed for the west coast of the US," says Elizabeth Cochran of the US Geological Survey, who was not involved in this work. "Accurate magnitude estimates, for example knowing that an earthquake is a potentially damaging M = 6 earthquake rather than a more moderate M = 5, [are] critical for initiating appropriate actions by the public, companies and emergency personnel," she adds.
Other experts express caution about not making use of information derived from τpmax. Mark Hildyard of the University of Leeds in the UK says that while some effort has been made recently to show that amplitude-based methods can outperform their period-based counterparts, he would like to see more effort put into improving techniques that make use of τpmax.
Researchers at Columbia University in the US have built the smallest frequency-modulated (FM) radio transmitter ever. Based on a graphene nanomechanical system (NEMS), the device oscillates at a frequency of 100 MHz. It could find use in a variety of applications, including sensing tiny masses and on-chip signal processing. It also represents an important first step towards the development of advanced wireless technology and the design of ultrathin mobile phones, says team co-leader James Hone.
"Our device is much smaller than any other radio-signal source ever made and, importantly, can be put on the same chip that is used for data processing," he explains.
Graphene is a sheet of carbon atoms arranged in a honeycomb-like lattice that is just one atom thick. Since its discovery in 2004, this "wonder material" has continued to amaze scientists with its growing list of unique electronic and mechanical properties, which include high electrical conductivity and exceptional strength. Indeed, some researchers believe that graphene might even replace silicon as the electronic industry's material of choice in the future.
Ideal for making NEMS
Graphene is ideal for making NEMS – which are scaled-down versions of the microelectromechanical systems (MEMS) that are routinely employed in vibration-sensing applications. The new device made by Hone and colleagues is a NEMS version of a common electronic component known as a voltage-controlled oscillator (VCO) and generates a frequency-modulated (FM) signal of about 100 MHz. This frequency lies exactly in the middle of the FM radio band (87.7–108 MHz) and the researchers say that they have already succeeded in using low-frequency music signals to modulate the 100 MHz carrier signal from their graphene NEMS and recover the signals again using an ordinary FM receiver.
While graphene NEMS might not replace conventional radio transmitters yet, they will certainly be used in many other wireless signal-processing applications. Although electrical circuits have been continuously shrinking over the last few decades (as described by Moore's law), there are still some types of devices – especially those involved in creating and processing radio-frequency (RF) signals – that are notoriously difficult to miniaturize, explains team co-leader Kenneth Shepard. Called off-chip components because they cannot be integrated with miniaturized devices, they require a lot of space and electrical power, and their frequency cannot be easily tuned.
Graphene NEMS offer a solution to this problem because they are very small – the active area is only a few microns across – and they can potentially be integrated directly onto conventional CMOS chips. Most importantly, it is easy to tune their frequency thanks to graphene's exceptional strength.
Adjusting the tension
The Columbia researchers made their devices by contacting graphene sheets to source and drain electrodes and freely suspending the sheets over metal gates. In this configuration, the graphene functions like the skin of a drum. A DC gate voltage pulls the graphene down towards the gate and this adjusts the tension and, therefore, the mechanical resonance frequency, explains Hone. A radio-frequency signal on the gate drives sheet vibrations. "Finally, we apply a DC bias across the graphene and when the graphene vibrates it acts as a transistor whose gate capacitance is constantly changing – and it is this that creates an RF source–drain current," he says.
The team studied the vibrational properties of the device at room temperature in a vacuum chamber. "To make an oscillator, we first adjust the signal gain to just above unity (using a variable amplifier) and the phase to zero (using a phase shifter) at the resonance frequency," says Hone. "We then connect the output to the gate. This creates a closed loop that amplifies random thermal vibrations and makes the device oscillate."
The researchers say they are now busy looking at how to put their devices directly onto integrated circuits that already contain all the necessary drive and readout circuitry. They also hope to improve the performance of their oscillators and reduce device noise.
Quantum dots with confined light holes could have applications in quantum technologies
(Phys.org) —Semiconductor quantum dots are being widely studied for their potential use in future quantum technologies. One of the reasons for their appeal is that they can confine quantum bits such as excitons and spins inside of them. In a new study, researchers have created a quantum dot that contains an exciton in the form of an electron bound to a light hole. The use of a light (as opposed to heavy) hole could enable the quantum dots to have specific advantages for quantum information technologies.
The team of researchers, Y. H. Huo, et al., from institutes in Germany, The Netherlands, and Austria, have published their paper on light-hole excitons confined in quantum dots in a recent issue of Nature Physics.
As the researchers explain, heavy holes and light holes behave differently because they are located on different valence energy bands in a semiconducting material. To create these holes, the researchers excited the electrons in these energy bands using light. When an excited electron moves to the conduction band, it leaves an empty state in one of the valence bands. This missing electron behaves as a particle (a hole) with positive charge and a mass that depends on which valence band it is in. A hole in the so-called "light-hole band" behaves like a particle with a mass that is several times lower than a hole in the "heavy-hole" band.
So far, all experimental studies in which holes are confined in quantum dots have used heavy holes because they are easier to confine from an energetic standpoint. However, some theoretical analyses have suggested that using light holes instead of heavy holes would be beneficial for quantum information technologies. Potential benefits include the ability to achieve faster control and more direct measurements of the spin states.
In order to experimentally investigate these potential benefits, the researchers for the first time created quantum dots with light-hole ground states. Instead of completely redesigning the quantum dot geometry, they demonstrated that strain engineering could be used to create these dots.
The strain method involves creating initially unstrained quantum dots in pre-stressed membranes, and then inducing tensile strain on the dots by releasing the membranes from the substrate. The tensile strain shifts the quantum dots' character from dominantly heavy-hole to dominantly light-hole. When the membranes are placed on a piezoelectric substrate, the tensile strain can be further increased or decreased, enabling the emission energy and the hole character to be tuned. As the researchers showed both experimentally and theoretically, quantum dots that contain dominantly light-hole ground states have a clearly distinct signature compared to those with dominantly heavy-hole ground states.
Using strain engineering, the researchers demonstrated that the ground hole state in the quantum dot can have more than 95% light-hole character for tensile strains of 0.4%. The quantum dots also have a high optical quality that is comparable to that of state-of-the-art quantum dots. Combined with the fact that the membranes are compatible with electric control, these features show that quantum dots with confined light holes can soon be explored as new building blocks for quantum technologies.
"Light-hole excitons may enable direct conversion of the polarization of a photon (flying qubit) into the spin state of an electron confined in a quantum dot (stationary qubit)," coauthor Armando Rastelli, Professor of Semiconductor Physics at Johannes Kepler University Linz in Linz, Austria, told Phys.org. Rastelli is also affiliated with IFW Dresden in Germany. "In addition, light-hole spins (another form of stationary qubit) may be directly manipulated via microwaves and at higher rates compared to heavy-hole spins. Dedicated experiments will be needed to assess which of these potentials can be realized in practice."
In the future, the researchers plan to investigate how heavy holes become light holes, as well as other open questions.
"Next we plan to look in detail at the transition from a heavy-hole to a light-hole ground state," Rastelli said. "With the technological approach used in the paper, this was not possible. We are now designing a piezoelectric actuator which may allow us to follow smoothly the emission changes as heavy- and light-hole states cross each other. In addition, we are in touch with colleagues planning to investigate the properties of light-hole spins."
Two for the price of one: Single-molecule microscopy simultaneously monitors protein structure and function
(Phys.org) —Proteins accomplish something rather amazing: A protein can have many functions, with a given function being determined by the way they fold into a specific three-dimensional geometry, or conformations. Moreover, the structural transitions form one conformation to another is reversible. However, while these dynamics affect protein conformation and therefore function, and so are critical to a wide range of areas, methods for understanding how proteins behave near surfaces, which is complicated by protein and surface heterogeneities, has remained elusive. Recently, however, scientists at University of Colorado utilized a method known as Single-Molecule Förster Resonance Energy Transfer (SM-FRET) tracking to monitor dynamic changes in protein structure and interfacial behavior on surfaces by single-molecule Förster resonance energy transfer, allowing them to explicate changes in protein structure at the single-molecule level. (SM-FRET describes energy transfer between two chromophores – molecular components that determine its color.) In addition, the researchers state that their approach is suitable for studying virtually any protein, thereby providing a framework for developing surfaces and surface modifications with improved biocompatibility.
Prof. Joel L. Kaar discussed the paper he and his co-authors, Dr. Sean Yu McLoughlin, Prof. Mark Kastantin and Prof. Daniel K. Schwartz, recently published in Proceedings of the National Academy of Sciences. "The primary challenges in devising our approach to characterizing changes in protein structure were implementing a site-specific labeling method, which enabled single-molecule resolution, as well as a method to only image molecules at the solution-surface interface," Kaar tells Phys.org. The scientists overcame the former challenge by incorporating unnatural amino acids – that is, those not among the 20 so-called standard amino acids – with unique functional groups for labeling with fluorophores (chemical compounds that can re-emit light upon light excitation); the latter, by using total internal reflection fluorescence microscopy, which only excites molecules in the near-surface environment, thereby minimizing the background fluorescence of molecules free in solution. "Although site-specific labeling methods have been used to monitor changes in protein conformation mainly in bulk solution, such techniques have not previously been exploited to study freely diffusible protein molecules at interfaces," Kaar adds. As such, the researchers are the first to apply site-specific labeling methods to study protein-surface interactions,
"The major challenge associated with incorporating unnatural amino acids for labeling was related to the optimization of protein expression," Kaar continues. Specifically, he explains, the expression of the enzyme organophosphorus hydrolase (OPH) – which is notoriously difficult to make in large quantities due to inclusion body formation – with the unnatural amino acid p-azido-L-Phe (AzF) had to be optimized to efficiently incorporate p-azido-L-Phe. (Inclusion body formation refers to the intracellular aggregation of partially folded expressed proteins,) "This process required modification of expression conditions," he adds, "in which bacteria with modified genetic machinery were grown to enable production of soluble enzyme for single-molecule experiments."
Moreover, Kaar continues, monitoring molecule-by-molecule structure changes in organophosphorus hydrolase had its own challenges related to eliminating mislabeled protein molecules – that is, molecules with other than one donor and one acceptor fluorophore – from analysis. "We met this challenge by creating and implementing filters during data analysis that separated signals from properly labeled and mislabeled species."
Kaar points out that using SM-FRET tracking had its own issue. For one, it required high-throughput tracking algorithms (developed by co-authors Kastantin and Schwartz) critical to monitor changes in FRET signals for large numbers of molecules, which in turn was essential to identifying protein structure changes accurately (that is, with high statistical confidence). He points out that SM-FRET also required prior knowledge of the crystal structure of OPH, which was needed to make the FRET signal indicative of quantitative changes in protein conformation.
The study's results suggest that surfaces may act as a source of unfolded (that is, aggregation-prone) protein back into solution – but validating this implication faces the challenge of identifying the conformation of protein molecules immediately before desorption from the surface. "The question of whether the unfolded proteins induced aggregation in solution after desorption remains to be fully understood," Kaar explains. "Fully understanding if this is actually the case requires further analysis of protein in solution in the presence of the surface."
The team leveraged two key innovations to address these research challenges – the implementation of site-specific labeling methods, and high-throughput tracking algorithms with SM-FRET. "Combining these methods enabled the decoupling of surface-induced conformational changes from protein adsorption and desorption events," Kaar notes. "By decoupling such phenomenon, this approach allowed us to overcome the limitations of conventional surface characterization methods."
The research also shows that SM-FRET permits a unique level of understanding of the ways in which surface chemistry influences molecular conformation and, in turn, function. "By observing molecular-level changes in protein structure in isolation from competing surface dynamics, it's easier to make a direct connection between surface chemistry and conformation," Kaar points out. "Therefore, it is more straightforward to see the effects of surface chemistry and can lead to new ideas for how to improve chemistry for a given application.
Another important finding is that the new method will enable the creation of surfaces and modifications with improved biocompatibility by uncovering the connection between surface properties and protein unfolding. "This connection is critical to inspiring and developing surfaces and modifications that meld with the biological world," Kaar explains. "For example, with this understanding, we can begin to design surfaces that promote protein folding and therefore favorable responses from cells present in the surrounding milieu. In this example, the folded state of the protein may display certain biological signals to cells that thwart unwanted inflammatory or harmful reactions while instructing cells to respond in ways that may facilitate proliferation, differentiation or even wound healing in vivo."
Kaar tells Phys.org that future experiments are aimed at determining if the observed effects of fused silica on organophosphorus hydrolase are general or specific to this combination of surface and protein. "We plan to address this question by probing how fused silica and surfaces with other properties impact the folding of other proteins. We're also interested in expanding our methods to understand how surface effects on conformation impact the binding of a third protein species. Understanding this impact is critical to, for example, enumerating how cells respond to biological cues on surfaces in physiological environments." Other innovations that the researchers may develop, Kaar adds, include more sophisticated labeling to minimize SM-FRET protein mislabeling on surfaces, as well as labeling and detection schemes to enable multiple molecular events, including unfolding and binding, to be monitored simultaneously.
"Given that the interaction of proteins and surfaces are relevant in virtually all areas of biotechnology," Kaar notes, "many other areas of research – for example, tissue engineering and regenerative medicine, biosensing, biocatalysis, and pharmaceutical protein formulation – may benefit from exploiting our approach."
The Maya refer to both a modern-day people who can be found all over the world as well as their ancestors who built an ancient civilization that stretched throughout much of Central America, one that reached its peak during the first millennium A.D.
The Maya civilization was never unified; rather, it consisted of numerous small states, ruled by kings, each apparently centred on a city. Sometimes, a stronger Maya state would dominate a weaker state and be able to exact tribute and labor from it.
A system of writing using glyptic symbols was developed and was inscribed on buildings, stele, artifacts and books (only a few examples of Maya books survive today). They also developed a complicated calendar system that included what scholars call a “long-count” that kept track of time by using different units that range in length from a single day to millions of years (the unit in millions was rarely used). Contrary to popular belief, this system did not predict the end of the world in 2012, the unit in millions of years providing evidence of this.
Also, contrary to popular belief, the Maya civilization never vanished. While many cities were abandoned around 1,100 years ago, other cities, such as Chichén Itzá, grew in their place.
When the Spanish arrived in Central America in force in the 16th century, the diseases they brought devastated the Maya. Additionally, the Spanish forced the Maya to convert to Christianity, going so far as to burn their books (the reason why so few of them survive today). However, it is important to note that the Maya people live on today and can be found all over the world.
“Millions of Maya people live in Central America and throughout the world. The Maya are not a single entity, a single community, or a single ethnic group. They speak many languages including Mayan languages (Yucatec, Quiche, Kekchi and Mopan), Spanish and English. However, the Maya are an indigenous group tied both to their distant past as well as to events of the last several hundred years,” writes Richard Leventhal, Carlos Chan Espinosa and Cristina Coc in a recent edition of Expedition magazine.
While hunters and gatherers had a presence in Central America stretching back thousands of years, it was in what archaeologists call the Pre-classic period (1800 B.C. to A.D. 250) that permanent village life really took off.
“Really effective farming, in the sense that densely inhabited villages were to be found throughout the Maya area, was an innovation of the Pre-classic period,” writes Yale University Professor Michael Coe in his book "The Maya" (Thames and Hudson, 2011).
Coe said farming became more effective during this period, likely because of the breeding of more productive form of maize and, perhaps more importantly, the introduction of the “nixtamal” process. In this process, the maize is soaked in lime, or something similar, and cooked, something that “enormously increased the nutritional value of corn,” writes Coe.
During this time, the Maya were influenced by a civilization to the west of them known as the Olmecs. These people may have initially devised the long count calendar that the Maya would become famous for, Coe writes. Additionally, the recent discovery of a ceremonial site dated to 1000 B.C. at the site of Ceibal sheds more light on the relationship between the Maya and Olmecs suggesting that it was a complex one.
Maya civilization at its peak
Coe writes that the ancient Maya reached a peak between A.D. 250 and 900, a time that archaeologists call the “Classic” period when numerous Maya cities flourished throughout much of Central America.
The civilization “reached intellectual and artistic heights which no other in the New World, and few in Europe, could match at the time,” Coe writes. “Large populations, a flourishing economy, and widespread trade were typical of the Classic …” he said, noting that warfare was also quite common.
The Maya civilization was influenced by the city of Teotihuacan, located farther to the west. At Tikal, it appears that one of their early rulers, named Siyaj K’ak, may have come from there. According to an inscription, he ascended the throne on Sept. 13, A.D. 379, and is depicted wearing feathers and shells and holding an atlatl (spear-thrower), features associated with Teotihuacan, writes researcher John Montgomery in his book "Tikal: An Illustrated History of the Mayan Capital" (Hippocrene Books, 2001).
The numerous cities found throughout the Maya world each had their own individual wonders that made them unique. Tikal, for instance, is known for its pyramid building. Starting at least as early as A.D. 672, the city’s rulers would construct a twin pyramid complex at the end of every K’atun (20-year period). Each of these pyramids would be flat-topped, built adjacent to each other and contain a staircase on each side. Between the pyramids was a plaza that had structures laid out to the north and south.
Copan, a Maya city in modern-day Honduras, is known for its “Temple of the Hieroglyphic Stairway.” It’s a pyramid-like structure that has more than 2,000 glyphs embellished on a flight of 63 steps, the longest ancient Maya inscription known to exist and appears to tell the history of the city’s rulers.
The site of Palenque, another famous Maya city, is known for its soft limestone sculpture and the incredible burial of “Pakal,” one of its kings, deep inside a pyramid. When Pakal died at about age 80, he was buried along with five or six human sacrifices in a jade-filled tomb (including a jade funerary mask he wore). His sarcophagus shows the king’s rebirth and depictions of his ancestors in the form of plants. The tomb was re-discovered in 1952 and is “the American equivalent, if there is one, to King Tut’s tomb,” said archaeologist David Stuart in an online National Geographic lecture.
Contrary to popular belief the Maya civilization did not vanish. It’s true that many cities, including Tikal, Copan and Palenque, became abandoned around 1,100 years ago. Drought, deforestation, war and climate change have all been suggested as potential causes of this.
However, it is important to note that other Maya cities, such as that of Chichén Itzá, grew, at least for a time. In fact Chichén Itzá has the largest ball court in the Americas, being longer than a modern-day American football field. The court’s rings, through which competing teams somehow tried to score, rose about 20 feet (6 meters) off the ground, about twice the height of a modern-day NBA net. The rules for the Maya ball game are not well understood.
As mentioned earlier, the arrival of the Spanish brought about a profound change in the Maya world. The diseases they brought decimated the Maya and the Spaniards forced the Maya to convert to Christianity, even burning their books. Today, despite the devastation they experienced, the Maya people live on, numbering in the millions.
The Maya had a lengthy and complicated mythical origin story that is recorded by the K’iche Maya (based in Guatemala) in the Popol Vuh, the “Book of Counsel,” writes Coe in his book. According to the stories, the forefather gods Tepew and Q’ukumatz “brought forth the earth from a watery void, and endowed it with animals and plants,” writes Coe.
Creating sentient beings proved more difficult, but eventually humans were created, including the hero twins, Hunahpu and Xbalanque, who embark in a series of adventures, which included defeating the lords of the underworld. Their journey climaxed with the resurrection of their father, the maize god. “It seems clear that this whole mythic cycle was closely related to maize fertility,” Coe writes.
The Maya universe
The late Robert Sharer, who was a professor at the University of Pennsylvania, notes in his book "Daily Life in Maya Civilization" (Greenwood Press, 2009) that the ancient Maya believed that everything “was imbued in different degrees with an unseen power or sacred quality,” call k’uh, which meant “divine or sacredness.”
“The universe of the ancient Maya was composed of kab, or Earth (the visible domain of the Maya people), kan, or the sky above (the invisible realm of celestial deities), and xibalba, or the watery underworld below (the invisible realm of the underworld deities),” Sharer wrote.
Caves played a special role in Maya religion as they were seen as entranceways to the underworld. “These were especially sacred and dangerous places where the dead were buried and special rituals for the ancestors conducted.”
Sharer notes that the Maya followed a number of deities, the most central of which was Itzamnaaj. “In his various aspects, Itzamnaaj was the lord over the most fundamental opposing forces in the universe — life and death, day and night, sky and earth,” Sharer writes, noting that “as lord of the celestial realm” Itzamnaaj was the Milky Way and could be depicted as a serpent or two-headed reptile.
Other Maya deities included the sun god K’inich Ajaw, the rain and storm god Chaak and the lightning deity K’awiil, among many others.
Sharer wrote that human sacrifices were made on special occasions. “Among the Maya, human sacrifice was not an everyday event but was essential to sanctify certain rituals, such as the inauguration of a new ruler, the designation of a new heir to the throne, or the dedication of an important new temple or ball court.” The victims were often prisoners of war he notes.
At the site of Chichén Itzá victims would be painted blue, a color that appears to have honored the god Chaak, and cast into a well. Additionally near the site’s ball court there is a panel that shows a person being sacrificed. This may depict a ball-player from either the winning or losing team being killed after a game.
Writing & astronomy
Sharer notes that record keeping was an important part of the Maya world and was essential for agriculture, astronomy and prophecy. “By keeping records of the rainy and dry seasons, the Maya could determine the best times to plant and harvest their crops,” Sharer wrote.
Additionally, by “recording the movements of the sky deities (sun, moon, planets, and stars), they developed accurate calendars that could be used for prophecy,” Sharer wrote.
“With long-term records, the Maya were able to predict planetary cycles — the phases of the moon and Venus, even eclipses,” he said. “This knowledge was used to determine when these deities would be in favorable positions for a variety of activities such as holding ceremonies, inaugurating kings, starting trading expeditions, or conducting wars.”
Economy & power
Sharer wrote that while agriculture and food gathering were a central part of daily life, the Maya had a sophisticated economy capable of supporting specialists and a system of merchants and trade routes. While the Maya did not develop minted currency, they used various objects, at different times, as “money.” These included greenstone beads, cacao beans and copper bells.
“Ultimately, the power of kings depended on their ability to control resources,” Sharer wrote. “Maya rulers managed the production and distribution of status goods used to enhance their prestige and power. They also controlled some critical (non-local) commodities that included critical everyday resources each family needed, like salt,” he said noting that over time Maya rulers managed ever-larger portions of the economy.
Sharer also notes that Maya laborers were subject to a labor tax to build palaces, temples and public works. A ruler successful in war could control more laborers and exact tribute on defeated enemies, further increasing their economic might.
George Washington Carver: Biography, Inventions & Quotes
Caption George Washington Carver, circa 1910. Credit: Public domain.
George Washington Carver was a prominent American scientist and inventor in the early 1900s. Carver developed hundreds of products using the peanut, sweet potatoes and soybeans. He also was a champion of crop rotation and agricultural education. Born into slavery, today he is an icon of American ingenuity and the transformative potential of education.
Carver was likely born in January or June of 1864. His exact birth date is unknown because he was born a slave on the farm of Moses Carver in Diamond, Missouri. Very little is known about George’s father, who may have been a field hand named Giles who was killed in a farming accident before George was born. George’s mother was named Mary; he had several sisters, and a brother named James.
When George was only a few weeks old, Confederate raiders invaded the farm, kidnapping George, his mother and sister. They were sold in Kentucky, and only George was found by an agent of Moses Carver and returned to Missouri. Carver and his wife, Susan, raised George and James and taught them to read.
James soon gave up the lessons, preferring to work in the fields with his foster father. George was not a strong child and was not able to work in the fields, so Susan taught the boy to help her in the kitchen garden and to make simple herbal medicines. George became fascinated by plants and was soon experimenting with natural pesticides, fungicides and soil conditioners. Local farmers began to call George “the plant doctor,” as he was able to tell them how to improve the health of their garden plants.
At his wife’s insistence, Moses found a school that would accept George as a student. George walked the 10 miles several times a week to attend the School for African American Children in Neosho, Kan. When he was about 13 years old, he left the farm to move to Ft. Scott, Kan., but he later moved to Minneapolis, Kan., to attend high school. He earned much of his tuition by working in the kitchen of a local hotel. He concocted new recipes, which he entered in local baking contests. He graduated from Minneapolis High School in 1880 and set his sights on college.
George first applied to Highland Presbyterian College in Kansas. The college was impressed by George’s application essay and granted him a full scholarship. When he arrived at the school, however, he was turned away — they hadn’t realized he was black. Over the next few years, George worked at a variety of jobs. He homesteaded a farm in Kansas, worked a ranch in New Mexico, and worked for the railroads, always saving money and looking for a college that would accept him.
In 1888, George enrolled as the first black student at Simpson College in Indianola, Iowa. He began studying art and piano, expecting to earn a teaching degree. Carver later said, “The kind of people at Simpson College made me believe I was a human being.” Recognizing the unusual attention to detail in his paintings of plants and flowers his instructor, Etta Budd, encouraged him to apply to Iowa State Agricultural School (now Iowa State University) to study Botany.
At Iowa State, Carver was the first African American student to earn his Bachelor of Science in 1894. His professors were so impressed by his work on the fungal infections common to soybean plants that he was asked to remain as part of the faculty to work on his master’s degree (awarded in 1896). Working as director of the Iowa State Experimental Station, Carver discovered two types of fungi, which were subsequently named for him. Carver also began experiments in crop rotation, using soy plantings to replace nitrogen in depleted soil. Before long, Carver became well known as a leading agricultural scientist.
In April 1896, Carver received a letter from Booker T. Washington of Tuskegee Institute, one of the first African American colleges in the United States. “I cannot offer you money, position or fame,” read this letter. “The first two you have. The last from the position you now occupy you will no doubt achieve. These things I now ask you to give up. I offer you in their place: work – hard work, the task of bringing people from degradation, poverty and waste to full manhood. Your department exists only on paper and your laboratory will have to be in your head.” Washington’s offer was $125.00 per month (a substantial cut from Carver’s Iowa State salary) and the luxury of two rooms for living quarters (most Tuskegee faculty members had just one). It was an offer that George Carver accepted immediately and the place where he worked for the remainder of his life.
Carver was determined to use his knowledge to help poor farmers of the rural South. He began by introducing the idea of crop rotation. In the Tuskegee experimental fields, Carver settled on peanuts because it was a simple crop to grow and had excellent nitrogen fixating properties to improve soil depleted by growing cotton. He took his lessons to former slaves turned sharecroppers by inventing the Jessup Wagon, a horse-drawn classroom and laboratory for demonstrating soil chemistry. Farmers were ecstatic with the large cotton crops resulting from the cotton/peanut rotation, but were less enthusiastic about the huge surplus of peanuts that built up and began to rot in local storehouses.
George Washington Carver working in his laboratory. Credit: U.S. Department of Agriculture.
Carver heard the complaints and retired to his laboratory for a solid week, during which he developed several new products that could be produced from peanuts. When he introduced these products to the public in a series of simple brochures, the market for peanuts skyrocketed. Today, Carver is credited with saving the agricultural economy of the rural South.
From his work at Tuskegee, Carver developed approximately 300 products made from peanuts; these included: flour, paste, insulation, paper, wall board, wood stains, soap, shaving cream and skin lotion. He experimented with medicines made from peanuts, which included antiseptics, laxatives and a treatment for goiter.
What about peanut butter?
Contrary to popular belief, while Carver developed a version of peanut butter, he did not invent it. The Incas developed a paste made out of ground peanuts as far back as 950 B.C. In the United States, according to the National Peanut Board, Dr. John Harvey Kellogg, of cereal fame, invented a version of peanut butter in 1895.
A St. Louis physician may have developed peanut butter as a protein substitute for people who had poor teeth and couldn't chew meat. Peanut butter was introduced at the St. Louis World's Fair in 1904.
Aiding the war effort
During World War I, Carver was asked to assist Henry Ford in producing a peanut-based replacement for rubber. Also during the war, when dyes from Europe became difficult to obtain, he helped the American textile industry by developing more than 30 colors of dye from Alabama soils.
After the War, George added a "W" to his name to honor Booker T. Washington. Carver continued to experiment with peanut products and became interested in sweet potatoes, another nitrogen-fixing crop. Products he invented using sweet potatoes include: wood fillers, more than 73 dyes, rope, breakfast cereal, synthetic silk, shoe polish and molasses. He wrote several brochures on the nutritional value of sweet potatoes and the protein found in peanuts, including recipes he invented for use of his favorite plants. He even went to India to confer with Mahatma Gandhi on nutrition in developing nations.
In 1920, Carver delivered a speech to the new Peanut Growers Association of America. This organization was advocating that Congress pass a tariff law to protect the new American industry from imported crops. As a result of this speech, he testified before Congress in 1921 and the tariff was passed in 1922. In 1923, Carver was named as Speaker for the United States Commission on Interracial Cooperation, a post he held until 1933. In 1935, he was named head of the Division of Plant Mycology and Disease Survey for the U.S. Department of Agriculture. By 1938, largely due to Carver’s influence, peanuts had grown to be a $200-million-per-year crop in the United States and were the chief agricultural product grown in the state of Alabama.
Carver died on Jan. 5, 1943. At his death, he left his life savings, more than $60,000, to found the George Washington Carver Institute for Agriculture at Tuskegee. In 1943, President Franklin D. Roosevelt dedicated funds to erect a monument at Diamond, Missouri, in his honor.
Commemorative postage stamps were issued in 1948 and again in 1998. A George Washington Carver half-dollar coin was minted between 1951 and 1954. There are two U.S. military vessels named in his honor.
There are also numerous scholarships and schools named for him. He was awarded an honorary doctorate from Simpson College. Since his exact birth date is unknown, Congress has designated January 5 as George Washington Carver Recognition Day.
Carver only patented three of his inventions. In his words, “It is not the style of clothes one wears, neither the kind of automobile one drives, nor the amount of money one has in the bank that counts. These mean nothing. It is simply service that measures success.”
"Ninety-nine percent of the failures come from people who have the habit of making excuses."
"Fear of something is at the root of hate for others, and hate within will eventually destroy the hater."
"Education is the key to unlock the golden door of freedom."
"When you do the common things in life in an uncommon way, you will command the attention of the world."
"Where there is no vision, there is no hope."
"Nothing is more beautiful than the loveliness of the woods before sunrise."
"There is no short cut to achievement. Life requires thorough preparation - veneer isn't worth anything."
"Learn to do common things uncommonly well; we must always keep in mind that anything that helps fill the dinner pail is valuable."
Credit: Choose_Freewill via flickr| http://bit.ly/II4yWN
(ISNS) -- With the wintry holiday season now upon us, icicles will soon join luminous and festive decorative lights along roofs and rafters. Natural icicles are more than convenient decorations, however, for University of Toronto physicists Antony Szu-Han Chen and Stephen Morris. They are an icy enigma waiting to be solved.
One riddle, in particular, is the origin of the ripple patterns that form around the circumference of icicles. By growing both smooth and rippled icicles in their laboratory, the pair discovered one ingredient that is vital to the formation of icicle ripples: salt.
Adding sodium chloride -- plain table salt -- to water introduces what are called ionic impurities. These form due to the presence of positively and negatively charged atoms. Although others have studied icicle formation, no previous models have considered that ionic impurities could be the primary source for ripples.
Icicles grown from salt water exhibit ripples while icicles grown from pure water are smooth, Chen and Morris reported in the New Journal of Physics this October. The experimental results challenge leading theories, which stipulate that ripples will form on icicles regardless of the water's purity.
"It was a complete surprise that the salt made a difference," said Morris.
In 2010, Chen and Morris built a device that grows icicles under controlled wind and temperature conditions. They found that icicles grown under windless conditions -- in still air -- developed multiple, branch-like pointed tips instead of the familiar single tip often exhibited in nature.
They also discovered that icicles grown from tap water were less uniform in shape, bulging and twisting more than icicles grown from distilled water. Using the same machine three years later, the team grew 67 icicles from solutions of distilled water mixed with different amounts of sodium chloride. This time, instead of analyzing the shape they studied the formation of ripples on the icicle surface.
The icicles grow in a refrigerated box that includes a camera, a nozzle that drips water and a support from which the base of the icicle eventually forms. Like meat on a skewer, the icicle attached to the support rotates at a leisurely speed of one revolution every four minutes as the nozzle continues to drip.
The researchers used six different solutions in their experiment, each with a different amount of dissolved salt. With saltier solutions, the team measured more pronounced ripples that protruded further away from center of the icicle.
Chen and Morris also tested solutions with other types of impurities, such as those formed by including dissolved gases in the water, but found they made no difference to the formation of ripples. Therefore, they concluded that the ionic impurities of a salty solution were key to the formation of ripples. In the future, they plan to test other ionic substances.
Their experimental results are in line with what scientists have observed and known for more than twenty years. In 1990, a pair of scientists at the University of Alberta in Edmonton developed a model based from their observations of "marine" icicles made from salty solutions that "developed horizontal ribs or ridges." In that study, the researchers did not consider the ionic properties of salt dissolved in water.
In fact, all current theories of ripple formation focus on other factors, such as surface tension, said Chen, a physics graduate student. Chen and Morris are still grappling with the theory that will match their experiment.
One person who is especially interested in a working theory that could readily explain icicle ripples is Christopher Batty, a computer graphics researcher at the University of Waterloo, in Ontario.
"With computer graphics, we're getting more interested in detail and realism," Batty said. "With simulations we can explore the theoretical understanding behind effects like icicle ripples and even more obscure phenomena like tip splitting effects."
Batty has developed methods for simulating the flow of honey and animating splashes and droplets of water. While Batty's work combines computer graphics and computational physics for academic purposes, today's commercialized digital age desperately depends on people like Batty who can model fluid dynamics.
For example, in order for Disney animators to create a realistic winter wonderland through which the characters in its latest film Frozen could tromp, it called upon the skills of a few UCLA computer scientists. Although the characters in the film reflect the classic Disney cartoon style, the film's snow is as realistic as ever. To achieve that level of realism, the Disney-UCLA team developed a novel snow simulation method that could model both the clumping and packing behavior of real snow.
"Ideally, it would be great to do something comparable to what UCLA did with Frozen for icicle formation by drawing on what Stephen Morris' experiments reveal," Batty said.
Organic, cage-free or home-grown? We think about our purchasing ethics in many areas of daily life, but not often about technology.
As with any product, though, we should think about the effects of our actions on workers and the environment. The idea of cage-free phones may sound silly, but for certain types of workers it’s a stark reality.
Technologies like mobile phones are often, by nature, small objects purchased infrequently. It’s difficult to put our ethics on the line when the object seems so meagre in size and when you don’t buy one that often.
And it often feels like we don’t have a lot of choice in the ethics of the phones we buy. All mobile phones are produced using the same materials, and some of these come from warzones. So choosing between Samsung and HTC can feel like choosing between a punch in the face and a kick in the guts.
Part of the problem is that we really feel like we have no choice but to buy a phone. Can we realistically expect to “go without” a phone, when our work, family and friends expect us to be available at all times? And when our carrier invites us to upgrade our phone for next to nothing every two years, what incentive do we have to slow down?
The Fairphone is one solution that has already sold out on its first production run. The sole marketing strategy for the Fairphone has been a detailed examination of the production process.
Their website provides photos and other evidence of attempts at ethical sourcing. Using those, you can make up your own mind about the ethics.
The 25,000 devices sold represent a very small proportion of the roughly 1.7 billion phones sold last year. And the Fairphone is not available at all in some markets, including Australia and the United States (though if you have a friend in Europe you can have them pick one up for you).
Fairphone prototype (left) and an iPhone. Credit: Waag Society.
Nonetheless, the sales figures so far suggest consumers are getting interested in finding ethical technologies.
Will this act as a trigger for other producers to become more ethical?
Motorola has announced “Ara”, their attempt to provide a less destructive alternative. The Ara phone is modular, meaning that people can use 3D printers from their homes to replace core technological components as needed and switch aesthetic parts such as the housing at leisure.
Motorola is bargaining that this will reduce the overall impact of our love of mobile phones.
But at the same time, Ara encourages us to throw away phones in dribs and drabs. Because the phone is based on the idea that we can replace any part at any time, it may still generate more waste over time than other gadgets.
As consumers raise concerns about the ethics of their devices, producers are gradually raising their production standards. Apple, Microsoft and Nokia have joined the Public-Private Alliance for Responsible Minerals Trade, which is working to monitor, reform and document the extraction and trade of minerals such as coltan.
While the effects of the Alliance to date are unclear, it at least suggests that progress is possible.
The Fairphone and Ara are small examples, but hopefully they are the start of a growing change in the way we make and use mobile phones. They give us an opportunity to be more ethical in an area in which our choices are often limited.
Robbie Fordyce owns a Nokia phone from about three years ago. It has no smartphone features.
Luke van Ryn is an ambivalent owner of an iPhone 5.
This article was originally published at The Conversation. Read the original article. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on LiveScience.
Will Grizzly-Polar Bear Hybrid Wake People Up to Changing Climate? (Op-Ed)
Credit: Animal Planet, Discovery Channel
Jeff Nesbitwas the director of public affairs for two prominent federal science agencies. This article was adapted from one that first appeared in U.S. News & World Report. Nesbit contributed the article to LiveScience'sExpert Voices: Op-Ed & Insights.
Science speaks most clearly for people when they can actually "see" the truth for themselves — when there's something tangible they can visualize about what might otherwise be just a math equation or a piece of scientific research.
The modern computer/tablet/smartphone era is a good example of this. The devices that billions now rely on each day are built largely on platforms involving sophisticated math equations that were once considered future applications — not present ones. But I dare anyone alive today to think of mobile devices or tablets as a nice math theory.
Albert Einstein had a problem once. He was convinced that some very smart group of physicists — perhaps Nazi scientists — were close to the then-theoretical ability to split the atom and harness its energy.
Einstein desperately wanted to get President Franklin Roosevelt's attention — to warn him of what might happen in the not-too-distant future should Nazi scientists succeed in that effort and create a weapon based on what was (at the time) a possible future built from math equations and theoretical physics.
The myth is that Einstein wrote a letter to FDR, warning him of the grave risk, and that in turn set off a chain of events culminating in the Manhattan Project and the birth of the atomic age. Most people have heard about the "Einstein letter" that allegedly triggered high-level action at the White House.
But the truth, sadly, is that Einstein actually had to write four such letters — each more insistent than the previous one — laying out the potential risks should Nazi scientists succeed in acquiring an atomic weapon before the United States did. Einstein was mostly an irritant to FDR and his senior White House staff with his warnings. FDR had a real war to consider — not some theoretical future threat.
So, mostly to stop him from writing even more letters warning about a potential, future threat from atomic weapons, FDR convened a committee that authorized an extremely modest $6,000 research grant to study it. With that funding, Enrico Fermi created the first "atomic pile" — and the theory of splitting and harnessing the atom was transformed from a distant, future threat to a present one.
On Tuesday, the National Research Council (NRC) issued something akin to that series of Einstein letters.
Its report on the potential for "abrupt climate change" was an update of an earlier report a decade ago, about the potential for the Earth's climate system to shift abruptly in a relatively short period of time if certain breaking points are reached or tipping points are crossed.
The new NRC report was widely covered in the press. Like the Einstein letters to FDR, this report and others like them are a steady, cascading drumbeat desperately trying to get the attention of the world's leaders to warn them of the ways in which a distant, future threat to civilization could become a very real, sudden, present threat.
But something has also changed in the past decade — and it illustrates why this issue may now start to become real and tangible for people.
Climate change is no longer a future threat off in the distance. It's becoming a present one — here, now — that will have a lasting and potentially devastating affect on small-hold farmers in developing countries no longer able to predict the start of the planting season, cities near sea level that haven't planned for storm surge, countries in the path of ever-stronger typhoons and, of course, iconic species that are moving towards or away from the poles to escape the onset of a new climate era.
Seeing is believing when it comes to science — and inside the NRC report is the reminder that we are now seeing what climate science had predicted decades ago. The new NRC report, among many other findings, continues to chronicle the collapse of the ecosystem for polar bears in the face of climate change.
Seven years ago, a hunter killed the first of the "pizzlies" — a hybrid born of two endangered species, the grizzly bear and the polar bear — in Canada's Northwest Territories. Such pizzlies were predicted, and perhaps inevitable, as climate change forced grizzlies north and polar bears south from the melting Arctic.
National Geographic displayed the first recorded picture of such a "pizzly" a few years later. At the same time, Nature chronicled the emergence of dozens of such hybrids — all of them due to climate change shrinking, altering and confounding their ecosystem. New biodiversity research reports on the horizon will similarly detail the imminent collapse of ecosystems for other iconic, recognizable species.
If you're a topical expert — researcher, business leader, author or innovator — and would like to contribute an op-ed piece, email us here.
The science of climate change for these species is no longer theoretical, distant and off in the future. It's here, now — and species are being forced to deal with it however they can. And while there may be only a few of these pizzlies today, they are quite real and they tell a story that society needs to hear before it's too late.
Polar bears were once the face of global warming. Many, many people associated climate change with the notion that polar bears might become extinct as their Arctic habitat disappeared in the face of future climate changes. Thankfully, climate impacts to people — not polar bears — are now the focus of most efforts.
But polar bears are still telling us — by their actions — that humanity is moving into a new climate era. And the story the bears are telling is that climate change is significantly affecting their part of the planet, and that it's only a matter of time before it changes the rest of the planet in equally significant ways.
Credit: U.S. Fish and Wildlife Service | Alligator River National Wildlife Refuge
Wayne Pacelle is the president and chief executive officer of The Humane Society of the United States (HSUS). This Op-Ed is adapted from a post on the blogA Humane Nation, where the content ran before appearing in LiveScience'sExpert Voices: Op-Ed & Insights.
Last month, the South Carolina Department of Natural Resources (DNR) put an end to the archaic and barbaric practice of bear "baying," three years after The HSUS released the results of an undercover investigation that showed dogs attacking a tethered, often declawed and defanged bear, with hundreds of people watching the spectacle just as they'd watch a dogfight or cockfight. Dozens of news outlets covered our original investigation, and there was a collective gasp that such a thing was both permitted and conducted.
Recently South Carolina's DNR announced that the six bears used in bear baying competitions had been relinquished to the agency and were safely transported to the Wild Animal Sanctuary in Keenesburg, Colo., where they will spend the remainder of their lives in peace.
If you're a topical expert — researcher, business leader, author or innovator — and would like to contribute an op-ed piece, email us here.
At the bear baying events The HSUS investigated, handlers released dogs that successively attacked a tethered bear for hours. The supposed goal was for the dogs to corner the bear and keep her still, or "at bay." In reality, the dogs barked furiously at the terrified bear, jumping on her and biting her face and legs — and the bear fought back, swatting at the dogs. While similar spectacles take place in Pakistan, South Carolina was the only U.S. state known to host these cruel events.
Since The HSUS first saw the footage that our undercover investigators captured, we have been working — sometimes quietly behind the scenes — to rid the state of this disgraceful pursuit.
In September, the DNR arrested a man and filed felony charges against him for allowing dogs to repeatedly attack and bite a captive bear. As part of a plea deal, the owner surrendered three bears, which were among the six transported to Colorado. And in early October, The HSUS applauded DNR's entire law-enforcement team, who worked to investigate this activity and ensure that the bears were sent to a reputable sanctuary.
The six rescued bears range in age from 7 to 23 years. We don't know how many years of their lives were spent suffering in what must have been a terrifying existence, but today we are so thankful that we could pull back the curtain on this underground and shameful practice. It's another transformational HSUS investigation that resulted in people of conscience (in this case, law-enforcement personnel) taking action once the truth came to light.
Scientists Color Silk By Feeding Silkworms Fabric Dyes
Brown cows may not actually make chocolate milk, but pink silkworms do produce pink skeins of silk, a team of scientists has discovered. To see if they could produce pre-dyed silk—silk that comes colored, straight from the source—the team fed ordinary silkworms mulberry leaves that had been sprayed with fabric dyes. Out of seven tested dyes, only one worked, producing a thread that reminded me of pink-dyed hair.
And yes, the worms themselves take on some color before they weave their silk cocoons. Their colorful diets did not affect their growth, the team, which included engineers and biologists from the CSIR-National Chemical Laboratory in India, reports in the journal ACS Sustainable Chemistry & Engineering. (The researchers didn't look too deeply into how the dyes affected the silkworms' health. After all, silkworms die when people harvest their silk.)
The team investigated dyeing silk this way because coloring fabric normally uses enormous amounts of fresh water. The water gets contaminated with dangerous chemicals in the process, requiring costly treatment before factories can dump it back into waterways—or wreaking havoc when factory owners dodge cleanup rules.
Dyeing silk directly by feeding silkworms would eliminate those water-washing steps. Scientists are just starting to study this idea, however, it remains to be seen if it's commercially viable. In this experiment, the Indian team tested seven azo dyes, which are cheap and popular in the industry.
The scientists found different dyes moved through silkworms' bodies differently. Some never made it into the worms' silk at all. Others colored the worms and their cocoons, but the color molecules settled mostly in the sticky protein the worms add to their cocoons. That sticky stuff gets washed away before the silk is turned into fabric. Only one dye, named "direct acid fast red," showed up in the final, washed silk threads. By the time it made it there, it was a pleasant, light pink.
Couples Under An X-Ray And Other Amazing Images From This Week
Welcome to the Popular Science Blog Network! The Blog Network is a platform for some of the sharpest minds in science and technology to sound off about their areas of expertise. Check out our blogs here.
"You can ban drugs, but you can't ban chemistry," Mike Power, author of Drugs 2.0, explains in this talk at the HIT Hot Topics Conference. And he gives a personal, investigative story to prove it.
Governments can legislate chemicals--ban a drug, say, a stimulant or a psychedelic--but what happens when chemists make a slightly different version by mixing in a new molecule? The drug becomes, legally, something different, and for as long as it takes the government to catch up on the new substance, the drug can be sold. Power went on a quest to discover just how easy that process was, out-sourcing a version of the stimulant phenmetrazine to a Chinese lab, and in a few weeks, getting the legal version delivered to his door in the United Kingdom. The lab never even learned his name.
What's the answer to that loophole? Power offers one, but it's a slow build to how he gets there, and the video is worth watching in its entirety.
Last summer, the National Institutes of Health announced that it’s phasing out experiments on chimpanzees. All but 50 of its 451 chimps will go to sanctuaries, and it won’t breed the remainder. The change is based on its 2011 study that determined that advancements have rendered human trials, computer-based research, and genetically modified mice more scientifically useful than chimps. The U.S. is late to this. Australia, Japan, and the E.U. have already banned or limited experiments on great apes in medical research. But the science community should take it further. We should work to end all animal testing for good.
Ninety percent of drugs that pass animal testing then fail in human trials.It’s not just a moral question. Ethics aside, there are plenty of scientific reasons to push away from animal testing. The most important is that animal-based methods are being equaled or surpassed by other means. And the result is better science overall. Over the last 10 years, we’ve started replacing rodents with human cells in drug toxicity tests. But the biggest hurdle is probably testing efficacy: how well a drug treats a medical condition. A common tack is to genetically manipulate mice to imitate human diseases, but human and mouse genes still behave differently. In part because of this, 90 percent of drugs that pass animal testing then fail in human trials.
Organs on a chip are one alternative. The thumb- size devices combine a thin layer of human cells with microchips that pump bloodlike fluid through them. At Harvard’s Wyss Institute, researchers have built a human gut-on-a-chip that replicates intestinal muscular contractions and a lung-on-a-chip with air-sac and capillary cells that exchange oxygen for carbon dioxide. The pseudo-lung can get infected and mimic complicated diseases such as chemotherapy-induced pulmonary edema. The institute is also working on chips for bone marrow, heart, and even brain tissue.
Computer models can help replace animals too. In the relatively new field of systems biology, scientists are making digital maps that simulate entire systems of the human body, down to the molecule. The Center for Systems Biology at the University of Iceland recently finished modeling all the chemical interactions of human metabolism and is starting on the blood. Last year, researchers at the University of California at San Francisco used a computer to predict negative side effects in on-market drugs with about 50 percent accuracy. That accuracy will only get better.
Human studies are also getting stronger. Lab animals are usually genetically identical clones, but people have lots of DNA differences that can affect how a drug works. For example, in 2010 it was discovered that the popular heart-attack-prevention drug Plavix is less effective for nearly one in three patients because of variances in their metabolisms. Now, gene tests can help doctors choose whether or not to prescribe it, and similar tests could do the same for other drugs. By relying on cloned animals and cells, we’ve probably been screening out helpful medicines before they even get to human trials.
Some animal testing will remain scientifically necessary for a long time. Studying visual perception, for example, requires a working eyeball connected to a brain (until a computer perfectly mimics it). But the more research options we create, the better science we’ll have.
This article originally appeared in the December 2013 issue of Popular Science.
Mystery Animal Contest: Who Is This Long-Beaked Surveyor?:
So, here are the rules: To answer, follow us on Twitter and tweet at us with the hashtag #mysteryanimal. For example:
Hey @PopSci, is the #mysteryanimal a baboon?
And then I might say...
New App Lets You Photograph Space From Your iPad:
By Rose Pastore Posted 06.10.2013 at 12:00 pm
Slooh Space Camera iPad app Slooh
Slooh, a company known for its helpful live feeds of awesome astronomical events, has just rele...
Magnetic dipoles line up:
The interaction of nanoscale magnetic dipoles has been observed for the first time by researchers in Germany. Unexpectedly, the dipoles were seen to form chains, rather than the zigz...