Sun unleashes X6.9 class flare; Earth spared this time

On August 9, 2011 at 3:48 a.m. EDT, the sun emitted an Earth-directed X6.9 flare, as measured by the NOAA GOES satellite.

This was the largest flare of the current solar cycle, an R3 (Strong) Radio Blackout, alternatively classified as an X6, according to the U.S. NOAA Space Weather Prediction Center.

These gigantic bursts of radiation can disrupt GPS and communications signals. In this case, scientists say the eruption took place on the side of the sun that was not facing Earth, so there’ll be little impact to satellites and communication systems, AP reports.

Space scientist Joe Kunches at the U.S. Space Weather Prediction Center in Colorado says there were reports of brief short-wave radio disruptions in Asia, but little else.

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What You Learned About Static Electricity Is Wrong

For many of us, static electricity is one of the earliest encounters we have with electromagnetism, and it’s a staple of high school physics. Typically, it’s explained as a product of electrons transferred in one direction between unlike substances, like glass and wool, or a balloon and a cotton T-shirt (depending on whether the demo is in a high school class or a kids’ party). Different substances have a tendency to pick up either positive or negative charges, we’re often told, and the process doesn’t transfer a lot of charge, but it’s enough to cause a balloon to stick to the ceiling, or to give someone a shock on a cold, dry day.

Nearly all of that is wrong, according to a paper published in today’s issue of Science. Charges can be transferred between identical materials, all materials behave roughly the same, the charges are the product of chemical reactions, and each surface becomes a patchwork of positive and negative charges, which reach levels a thousand times higher than the surfaces’ average charge.

Where to begin? The authors start about 2,500 years ago, noting that the study of static began with a Greek named Thales of Miletus, who generated it using amber and wool. But it wasn’t until last year that some of the authors of the new paper published a surprising result: contact electrification (as this phenomenon is known among its technically oriented fans) can occur between two sheets of the same substance, even when they’re simply allowed to lie flat against each other. “According to the conventional view of contact electrification,” they note, “this should not happen since the chemical potentials of the two surfaces/materials are identical and there is apparently no thermodynamic force to drive charge transfer.”

One possible explanation for this is that a material’s surface, instead of being uniform from the static perspective, is a mosaic of charge-donating and charge-receiving areas. To find out, they performed contact electrification using insulators (polycarbonate and other polymers), a semiconductor (silicon), and a conductor (aluminum). The charged surfaces were then scanned at very high resolution using Kelvin force microscopy, a variant of atomic force microscopy that is able to read the amount of charge in a surface.

The Kelvin force microscopy scans showed that the resulting surfaces were mosaics, with areas of positive and negative charges on the order of a micrometer or less across. All materials they tested, no matter what overall charge they had picked up, showed this mosaic pattern. The charges will dissipate over time, and the authors found that this process doesn’t seem to occur by transferring electrons between neighboring areas of different charge—instead of blurring into the surroundings, peaks and valleys of charge remain distinct, but slowly decrease in size. The authors estimate that each one of these areas contains about 500 elementary charges (that’s ±500 electrons), or about one charge for each 10nm2.

The reason that this produces a relatively weak charge isn’t because these peaks and valleys are small; the charge difference between them is on the order of 1,000 times larger than the average charge of the whole material. It’s just that the total area of sites with positive and negative charges are roughly equal (the two are typically within a fraction of a percent of each other). The distribution appears to be completely random, as the authors were able to produce similar patterns with a white noise generator that fluctuated on two length scales: 450nm and 44nm.

So, what causes these charges to build up? It’s not, apparently, the transfer of electrons between the surfaces. Detailed spectroscopy of one of the polymers (PDMS) suggests that chemical reactions may be involved, as many oxidized derivatives of the polymer were detected. In addition, there is evidence that some material is transferred from one surface to another. Using separate pieces of fluorine- and silicon-containing polymers allowed the authors to show that signals consistent with the presence of fluorine were detected in the silicon sample after contact.

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Hand-hacking lets you pluck strings like a musical pro

PossessedHand, being developed jointly by the University of Tokyo, Japan, and Sony Computer Science Laboratories, electrically stimulates the muscles in the forearm that move your fingers.

A belt worn around that part of the subject’s arm contains 28 electrode pads that flex the joints between the three bones of each finger and the two bones of the thumb, and provide two wrist movements. Users were able to sense the movement of their hands that this produced, even with their eyes closed.

Having successfully hijacked a hand, the researchers tried to teach it how to play the koto, a traditional Japanese stringed instrument. Koto players wear different picks on three fingers, but pluck the strings with all five fingertips, so each finger produces a distinctive sound.

PossessedHand does not generate enough force to pluck the koto strings, but it could help novice players by teaching them the correct finger movements.

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Antiproton ring found around Earth

Antiprotons appear to ring the Earth, confined by the planet’s magnetic field lines. The antimatter, which may persist for minutes or hours before annihilating with normal matter, could in theory be used to fuel ultra-efficient rockets of the future.

Charged particles called cosmic rays constantly rain in from space, creating a spray of new particles – including antiparticles – when they collide with particles in the atmosphere. Many of these become trapped inside the Van Allen radiation belts, two doughnut-shaped zones around the planet where charged particles spiral around the Earth’s magnetic field lines.

Satellites had already discovered positrons – the antimatter partners of electrons – in the radiation belts. Now a spacecraft has detected antiprotons, which are nearly 2000 times as massive.

Heavier particles take wider paths when they spiral around the planet’s magnetic lines, and weaker magnetic field lines also lead to wider spirals. So relatively heavy antiprotons travelling around the weak field lines in the outer radiation belt were expected to take loops so big they would quickly get pulled into the lower atmosphere, where they would annihilate with normal matter. The inner belt was thought to have fields strong enough to trap antiprotons, and indeed that is where they have been found.

Piergiorgio Picozza from the University of Rome Tor Vergata, Italy, and colleagues detected the antiprotons using PAMELA, a cosmic-ray detector attached to a Russian Earth-observation satellite. The spacecraft flies through the Earth’s inner radiation belt over the south Atlantic.

Between July 2006 and December 2008, PAMELA detected 28 antiprotons trapped in spiralling orbits around the magnetic field lines sprouting from the Earth’s south pole. PAMELA samples only a small part of the inner radiation belt, but antiprotons are probably trapped throughout it. “We are talking about of billions of particles,” says team member Francesco Cafagna from the University of Bari in Italy.

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Scientists drag light by slowing it to speed of sound

Scientists at the University of Glasgow have, for the first time, been able to drag light by slowing it down to the speed of sound and sending it through a rotating crystal.
Most people may think the speed of light is constant, but this is only the case in a vacuum, such as space, where it travels at 671million mph.
However, when it travels through different substances, such as water or solids, its speed is reduced, with different wavelengths (colours) travelling at different speeds.
In addition, it has also been observed, but is not widely appreciated, that light can be dragged when it travels through a moving substance, such as glass, air or water – a phenomenon first predicted by Augustin-Jean Fresnel in 1818 and observed a hundred years later.
Prof. Miles Padgett in the Optics Group in the School of Physics & Astronomy, said: “The speed of light is a constant only in vacuum . When light travels through glass, movement of the glass drags the light with it too.

“Spinning a window as fast as you could is predicted to rotate the image of the world behind it ever so slightly. This rotation would be about a millionth of a degree and imperceptible to the human eye.”

In research detailed in the latest edition of the journal Science (“Rotary Photon Drag Enhanced by a Slow-Light Medium”), researchers Dr Sonja Franke-Arnold, Dr Graham Gibson and Prof Padgett, in collaboration with their colleague Professor Robert Boyd at the Universities of Ottowa and Rochester, took a different approach and set up an experiment: shining a primitive image made up of the elliptical profile of a green laser through a ruby rod spinning on its axis at up to 3,000 rpm.

Once the light enters the ruby, its speed is slowed down to around the speed of sound (approximately 741mph) and the spinning motion of the rod drags the light with it, resulting in the image being rotated by almost five degrees: large enough to see with the naked eye.

Dr Franke-Arnold, who came up with the idea of using slow light in ruby to observe the photon drag, said: “We mainly wanted to demonstrate a fundamental optical principle, but this work has possible applications too.
“Images are information and the ability to store their intensity and phase is an important step to the optical storage and processing of quantum information, potentially achieving what no classical computer can ever match.
“The option to rotate an image by a set arbitrary angle presents a new way to code information, a possibility not accessed by any image coding protocol so far.”

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Feel the Noise: Touch, Hearing May Share Neurological Roots

About a year and a half after her stroke, a 36-year-old professor started to feel sounds. A radio announcer’s voice made her tingle. Background noise in a plane felt physically uncomfortable.

Now Tony Ro, a neuroscientist at the City College of New York and the Graduate Center of the City University of New York, might have figured out the cause of this synesthesia. Sophisticated imaging of the woman’s brain revealed that new links had grown between its auditory part, which processes sound, and the somatosensory region, which handles touch.

“The auditory area of her brain started taking over the somatosensory area,” says Ro, who used diffusion tensor imaging, which focuses on the brain’s white matter connections, to spot the change.

This connection between sound and touch may run deep in the rest of us as well, Ro and colleagues said during presentations May 25 at a meeting of the Acoustical Society of America. Both hearing and touch, the scientists pointed out, rely on nerves set atwitter by vibration. A cellphone set to vibrate can be sensed by the skin of the hand, and the phone’s ringtone generates sound waves — vibrations of air — that move the eardrum.

Elizabeth Courtenay Wilson, a neuroscientist who did not attend the Seattle meeting, has also seen strong connections between areas of the brain that process hearing and touch. “We’re suggesting that the ear evolved out of the skin in order to do more finely tuned frequency analysis,” adds Wilson, of Beth Israel Deaconess Medical Center in Boston.

Wilson earned her Ph.D. in an MIT laboratory focused on studying whether vibrations could boost hearing aid performance. She published a series of papers showing that people with normal hearing were much better at detecting the combination of an extremely weak sound and an extremely weak vibration applied to the skin than either stimulus on its own.

Other researchers have shown that hearing a sound can boost touch sensitivity. Ro calls this the mosquito effect: The bug’s buzz makes our skin prickle. The frequency of the sound and the frequency of the vibrations our hands feel must match for this to work, according to a 2009 paper he published in Experimental Brain Research.

Frequency may be a two-way street in the brain that unites these two senses, says Jeffrey Yau, a neuroscientist at the Johns Hopkins University School of Medicine in Baltimore. A vibration that has a higher or lower frequency than a sound, he found, tends to skew pitch perception up or down. Sounds can also bias whether a vibration is perceived.

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Sounds of Japan Earthquake and Aftershocks from Underwater Observatories

The Laboratory of Applied Bioacoustics (LAB), a unit of the Universitat Politècnica de Catalunya (UPC), directed by Professor Michel André, has recorded the sound of the earthquake that shook Japan on Friday, March 11. The recording, now available online, was provided by a network of underwater observatories belonging to the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) and located on either side of the earthquake epicenter, close to the Japanese island of Hatsushima.

More on “Listening to the Deep Ocean Environment”:

The sea environment is filled with natural sounds, although increasingly many anthropogenic sources have contributed to the general noise budget of the oceans. The extent to which sound in the sea impacts and affects marine life is a topic of considerable current interest both to the scientific community and to the general public. Scientific interest arises from a need to understand more about the role of sound production and reception in the behaviour, physiology, and ecology of marine organisms and how anthropogenic sound, including sound necessary to study the marine environment, can interfere with the natural use of sound by marine organisms. Public interest concerns primarily the potential effects of anthropogenic sound on marine mammals, given the broad recognition of the importance of sound in the lives of these species. For acoustical oceanographers, marine seismologists, and minerals explorers, sound is the most powerful remote-sensing tool available to determine the geological structure of the seabed and to discover oil and gas reserves deep below the seafloor.

The scientific as well as the public’s interest in the impact of human-generated ocean noise on marine animals has greatly increased. Concerns include whether human-generated sounds may interfere with the normal use of sound by the marine animals or whether the human-generated sounds may cause the animals physical harm.

Many aquatic animals use sound for communication between members of their species. But equally important is the fact that all of these species probably also use sound to learn about their environment and to survive. Therefore, there should be concern not only about the effects of anthropogenic sounds on communication but also about the impact on general extraction of information from the environment. A fundamental question is whether the impact of anthropogenic sounds on marine mammals and the marine ecosystem is sufficiently important to warrant concern by both the scientific community and the public. The data currently available suggest that such interest is indeed justified.

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Augmented instruments add virtual input to live music

They look like just another three-piece band, with drums, violin and guitar. But stop and listen to Edgar Berdahl and his colleagues, and you’ll notice things aren’t quite what they seem. Strange tones emerge from their instruments, sometimes without any of the performers moving, as an abstract soundscape washes over you.

The Haptic Drum, Overtone Fiddle and Feedback Resonance Guitar are all examples of what Berdahl, who researches technology in music at Stanford University in California, calls actuated instruments.

Berdahl and his colleagues have modified traditional instruments by adding electromagnets and other sensors that can both detect and induce vibrations, blurring the line between physical and computer-generated sounds. The instruments can essentially play themselves, while also allowing a person to control them. This allows very different sounds to be created. “The manner in which the external energy is injected into the instrument enables and even compels the performer to interact in new ways,” says Berdahl.

Take the Overtone Fiddle, created by Dan Overholt at Aalborg University, Denmark. It can be played like a regular violin, but signals can also be pumped directly into the instrument’s body, causing it to resonate and produce a wider variety of sounds. An iPod Touch controls the signals, allowing the performer to modify effects on the fly, while a bow fitted with a position sensor provides another form of input that can be used to modify the sounds.

The Feedback Resonance Guitar follows a similar construction, using electromagnets to vibrate each of the instrument’s six strings at a variety of frequencies. Notes can be artificially sustained, and the guitar can also play traditional rock “feedback” tones without the usual corresponding rise in volume – handy if you want to avoid blowing your amp.

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Does coffee make you hear things?

Scholars at Australia’s La Trobe University just released a study showing a correlation between caffeine intake and auditory hallucinations. In layman’s terms: Lots of coffee might make you more likely to hear things that aren’t there.

Researchers came to the conclusion after studying 92 people with a broad range of java-drinking habits. Participants — who were told they were taking part in hearing tests — were set up with headphones and asked to press a buzzer every time they heard audio from Bing Crosby’s classic “White Christmas.” As a matter of fact, the only sound played into the headsets was white noise. But participants who drank at least 400 milliliters (or about 13.5 fluid ounes) of coffee per day were significantly more likely to identify Crosby’s soulful croon.

“On average, low-caf subjects heard it once. But stressed coffee guzzlers buzzed three times,” said Australia’s Herald Sun newspaper.

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What Tau Sounds Like

Musician interprets the mathematical constant Tau to 126 decimal places

See also What Pi Sounds Like

via Higher Music.

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