New Tasks Become as Simple as Waving a Hand With Brain-Computer Interfaces

Small electrodes placed on or inside the brain allow patients to interact with computers or control robotic limbs simply by thinking about how to execute those actions. This technology could improve communication and daily life for a person who is paralyzed or has lost the ability to speak from a stroke or neurodegenerative disease.

University of Washington researchers have demonstrated that when humans use this technology -- called a brain-computer interface -- the brain behaves much like it does when completing simple motor skills such as kicking a ball, typing or waving a hand. Learning to control a robotic arm or a prosthetic limb could become second nature for people who are paralyzed.

"What we're seeing is that practice makes perfect with these tasks," said Rajesh Rao, a UW professor of computer science and engineering and a senior researcher involved in the study. "There's a lot of engagement of the brain's cognitive resources at the very beginning, but as you get better at the task, those resources aren't needed anymore and the brain is freed up."

Rao and UW collaborators Jeffrey Ojemann, a professor of neurological surgery, and Jeremiah Wander, a doctoral student in bioengineering, published their results online June 10 in the Proceedings of the National Academy of Sciences.

In this study, seven people with severe epilepsy were hospitalized for a monitoring procedure that tries to identify where in the brain seizures originate. Physicians cut through the scalp, drilled into the skull and placed a thin sheet of electrodes directly on top of the brain. While they were watching for seizure signals, the researchers also conducted this study.

The patients were asked to move a mouse cursor on a computer screen by using only their thoughts to control the cursor's movement. Electrodes on their brains picked up the signals directing the cursor to move, sending them to an amplifier and then a laptop to be analyzed. Within 40 milliseconds, the computer calculated the intentions transmitted through the signal and updated the movement of the cursor on the screen.

Researchers found that when patients started the task, a lot of brain activity was centered in the prefrontal cortex, an area associated with learning a new skill. But after often as little as 10 minutes, frontal brain activity lessened, and the brain signals transitioned to patterns similar to those seen during more automatic actions.

"Now we have a brain marker that shows a patient has actually learned a task," Ojemann said. "Once the signal has turned off, you can assume the person has learned it."

While researchers have demonstrated success in using brain-computer interfaces in monkeys and humans, this is the first study that clearly maps the neurological signals throughout the brain. The researchers were surprised at how many parts of the brain were involved.

"We now have a larger-scale view of what's happening in the brain of a subject as he or she is learning a task," Rao said. "The surprising result is that even though only a very localized population of cells is used in the brain-computer interface, the brain recruits many other areas that aren't directly involved to get the job done."

Several types of brain-computer interfaces are being developed and tested. The least invasive is a device placed on a person's head that can detect weak electrical signatures of brain activity. Basic commercial gaming products are on the market, but this technology isn't very reliable yet because signals from eye blinking and other muscle movements interfere too much.

A more invasive alternative is to surgically place electrodes inside the brain tissue itself to record the activity of individual neurons. Researchers at Brown University and the University of Pittsburgh have demonstrated this in humans as patients, unable to move their arms or legs, have learned to control robotic arms using the signal directly from their brain.

The UW team tested electrodes on the surface of the brain, underneath the skull. This allows researchers to record brain signals at higher frequencies and with less interference than measurements from the scalp. A future wireless device could be built to remain inside a person's head for a longer time to be able to control computer cursors or robotic limbs at home.

Source: Science Daily

R.Sawas

Black hole caught napping after meal

A black hole 11 million light-years away has gone dormant, a decade after being spotted consuming cosmic debris.

The black hole lies at the center of the Sculptor galaxy, a so-called starburst galaxy where stars are being born at a prodigious rate.

But the X-ray light corresponding to a black hole's snack has dimmed markedly.

The find, to appear in Astrophysical Journal, has mystified astronomers because star formation and black hole activity tend to go hand-in-hand.

The Sculptor galaxy - also known as NGC 253 - hosts a central black hole with a mass some five million times that of our Sun - a quarter again as plump as the black hole at the center of our own Milky Way galaxy.

In 2003, researchers using the Chandra space telescope caught sight of the X-rays that correspond to matter spiraling down into the black hole and heating up to millions of degrees.

    Black holes are incredibly dense objects with gravity strong enough to trap even light

    A 'medium' black hole could have the mass of 1,000 Suns but be no bigger than Earth

    Supermassive black holes are thought to be at the center of most large galaxies - including ours

But as of mid-2012, the X-ray sky has a new observer: a space telescope called the Nuclear Spectroscopic Telescope Array or Nustar, already a successful black-hole hunter.

Nustar can spot even higher-energy X-rays than Chandra, and in late 2012, both telescopes were trained on NGC 253 - with the surprise finding that the X-ray emission seems to have stopped.

"Black holes feed off surrounding accretion disks of material. When they run out of this fuel, they go dormant," said Ann Hornschemeier of Nasa's Goddard Space Flight Center, a co-author on the new study.

"NGC 253 is somewhat unusual because the giant black hole is asleep in the midst of tremendous star-forming activity all around it".

The subtle interplay between black hole activity and the birth rate of new stars remains somewhat mysterious, but Bret Lehmer of Nasa's Goddard Space Flight Center, lead author on the paper, said that the Sculptor galaxy could shed new light on these dark galactic corners.

"Periodic observations with both Chandra and Nustar should tell us unambiguously if the black hole wakes up again. If this happens in the next few years, we hope to be watching," he said.

Source :BBC

N.H.Khider

Biological clocks 'beat quicker' in cities

City living could have a major impact on the biological clocks of humans and animals, a new study has found.

Researchers measured the circadian rhythms - the 24-hour cycle of biological activity - of urban and rural blackbirds in southern Germany.

German and Scottish researchers found the city birds woke up earlier and rested less than forest dwelling birds.

The team has raised the possibility the differences could be the result of micro-evolutionary changes.

The study, which has been published in the journal Proceedings of the Royal Society B, was carried out by Glasgow University and the Max Planck Institute for Ornithology in Germany.

A number of adult male European blackbirds were captured from Munich and a nearby rural forest.

Each bird was equipped with a lightweight radio-transmitter which monitored their daily levels of activity in the wild for 10 days before they were recaptured.

"Our work shows for the first time that that when sharing human habitats, a wild animal species has a different internal clock".

They were then kept in light-proofed, sound-insulated chambers and their circadian rhythms were measured under constant conditions

Once the tests were complete the birds were returned to the wild

Dr Barbara Helm, from Glasgow University's institute of biodiversity, animal health and comparative medicine, said: "We found that the rhythms of urban birds in the wild differ significantly from their forest counterparts.

"On average, they began their daily activities around 30 minutes before dawn, while forest birds began their day as the sun rose.

"The city birds ended their days around nine minutes later, meaning they were active for about 40 minutes longer each day".

Dr Helm said in "constant laboratory conditions" the circadian rhythms of urban birds were clearly altered".

"There seems to be a different beat to city life", she said. "City clocks were also less persistent, especially in the business district".

The team said its research added "to a growing consensus" that towns and cities "have a profound effect on the internal clocks" of humans and animals

It said further study was needed to determine whether these changes could lead to increased health problems or were related to better function in urban areas.

Dr Helm added: "Previous research undertaken by other researchers has suggested strong links in humans between disrupted sleep patterns and an increased incidence of depression and diseases including obesity and some types of cancers.

"Our work shows for the first time that when sharing human habitats, a wild animal species has a different internal clock.

"We'd be keen to find out the costs and benefits of modifying biological rhythms in blackbirds and other animals commonly found in our cities. This may help us to better understand the challenges of coping with urban life".

The researchers have raised the possibility the differences in the biological rhythms could be the result of micro-evolutionary changes in response to urban phenomena such as artificial light and increased noise levels.

Source:BBC

N.H.Khider

Even With Defects, Graphene Is Strongest Material in the World

In a new study, Columbia Engineering researchers demonstrate that graphene, even if stitched together from many small crystalline grains, is almost as strong as graphene in its perfect crystalline form. This work resolves a contradiction between theoretical simulations, which predicted that grain boundaries can be strong, and earlier experiments, which indicated that they were much weaker than the perfect lattice.

Graphene consists of a single atomic layer of carbon, arranged in a honeycomb lattice. "Our first Science paper, in 2008, studied the strength graphene can achieve if it has no defects -- its intrinsic strength," says James Hone, professor of mechanical engineering, who led the study with Jeffrey Kysar, professor of mechanical engineering. "But defect-free, pristine graphene exists only in very small areas. Large-area sheets required for applications must contain many small grains connected at grain boundaries, and it was unclear how strong those grain boundaries were. This, our second Science paper, reports on the strength of large-area graphene films grown using chemical vapor deposition (CVD), and we're excited to say that graphene is back and stronger than ever."

The study verifies that commonly used methods for post-processing CVD-grown graphene weaken grain boundaries, resulting in the extremely low strength seen in previous studies. The Columbia Engineering team developed a new process that prevents any damage of graphene during transfer. "We substituted a different etchant and were able to create test samples without harming the graphene," notes the paper's lead author, Gwan-Hyoung Lee, a postdoctoral fellow in the Hone lab. "Our findings clearly correct the mistaken consensus that grain boundaries of graphene are weak. This is great news because graphene offers such a plethora of opportunities both for fundamental scientific research and industrial applications."

In its perfect crystalline form, graphene (a one-atom-thick carbon layer) is the strongest material ever measured, as the Columbia Engineering team reported in Science in 2008 -- so strong that, as Hone observed, "it would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap." For the first study, the team obtained small, structurally perfect flakes of graphene by mechanical exfoliation, or mechanical peeling, from a crystal of graphite. But exfoliation is a time-consuming process that will never be practical for any of the many potential applications of graphene that require industrial mass production.

Currently, scientists can grow sheets of graphene as large as a television screen by using chemical vapor deposition (CVD), in which single layers of graphene are grown on copper substrates in a high-temperature furnace. One of the first applications of graphene may be as a conducting layer in flexible displays.

"But CVD graphene is 'stitched' together from many small crystalline grains -- like a quilt -- at grain boundaries that contain defects in the atomic structure," Kysar explains. "These grain boundaries can severely limit the strength of large-area graphene if they break much more easily than the perfect crystal lattice, and so there has been intense interest in understanding how strong they can be."

The Columbia Engineering team wanted to discover what was making CVD graphene so weak. In studying the processing techniques used to create their samples for testing, they found that the chemical most commonly used to remove the copper substrate also causes damage to the graphene, severely degrading its strength.

Their experiments demonstrated that CVD graphene with large grains is exactly as strong as exfoliated graphene, showing that its crystal lattice is just as perfect. And, more surprisingly, their experiments also showed that CVD graphene with small grains, even when tested right at a grain boundary, is about 90% as strong as the ideal crystal.

"This is an exciting result for the future of graphene, because it provides experimental evidence that the exceptional strength it possesses at the atomic scale can persist all the way up to samples inches or more in size," says Hone. "This strength will be invaluable as scientists continue to develop new flexible electronics and ultrastrong composite materials."

 Strong, large-area graphene can be used for a wide variety of applications such as flexible electronics and strengthening components -- potentially, a television screen that rolls up like a poster or ultrastrong composites that could replace carbon fiber. Or, the researchers speculate, a science fiction idea of a space elevator that could connect an orbiting satellite to Earth by a long cord that might consist of sheets of CVD graphene, since graphene (and its cousin material, carbon nanotubes) is the only material with the high strength-to-weight ratio required for this kind of hypothetical application.

The team is also excited about studying 2D materials like graphene. "Very little is known about the effects of grain boundaries in 2D materials," Kysar adds. "Our work shows that grain boundaries in 2D materials can be much more sensitive to processing than in 3D materials. This is due to all the atoms in graphene being surface atoms, so surface damage that would normally not degrade the strength of 3D materials can completely destroy the strength of 2D materials. However with appropriate processing that avoids surface damage, grain boundaries in 2D materials, especially graphene, can be nearly as strong as the perfect, defect-free structure."

The study was supported by grants from the Air Force Office of Scientific Research and the National Science Foundation.

Source: Science Daily

R.Sawas

Water-Rock Reaction May Provide Enough Hydrogen 'Food' to Sustain Life in Ocean's Crust or On Mars

A chemical reaction between iron-containing minerals and water may produce enough hydrogen "food" to sustain microbial communities living in pores and cracks within the enormous volume of rock below the ocean floor and parts of the continents, according to a new study led by the University of Colorado Boulder.

The findings, published in the journal Nature Geoscience, also hint at the possibility that hydrogen-dependent life could have existed where iron-rich igneous rocks on Mars were once in contact with water.

Scientists have thoroughly investigated how rock-water reactions can produce hydrogen in places where the temperatures are far too hot for living things to survive, such as in the rocks that underlie hydrothermal vent systems on the floor of the Atlantic Ocean. The hydrogen gases produced in those rocks do eventually feed microbial life, but the communities are located only in small, cooler oases where the vent fluids mix with seawater.

The new study, led by CU-Boulder Research Associate Lisa Mayhew, set out to investigate whether hydrogen-producing reactions also could take place in the much more abundant rocks that are infiltrated with water at temperatures cool enough for life to survive.

"Water-rock reactions that produce hydrogen gas are thought to have been one of the earliest sources of energy for life on Earth," said Mayhew, who worked on the study as a doctoral student in CU-Boulder Associate Professor Alexis Templeton's lab in the Department of Geological Sciences.

"However, we know very little about the possibility that hydrogen will be produced from these reactions when the temperatures are low enough that life can survive. If these reactions could make enough hydrogen at these low temperatures, then microorganisms might be able to live in the rocks where this reaction occurs, which could potentially be a huge subsurface microbial habitat for hydrogen-utilizing life."

When igneous rocks, which form when magma slowly cools deep within Earth, are infiltrated by ocean water, some of the minerals release unstable atoms of iron into the water. At high temperatures -- warmer than 392 degrees Fahrenheit (200 degrees Celsius) -- scientists know that the unstable atoms, known as reduced iron, can rapidly split water molecules and produce hydrogen gas, as well as new minerals containing iron in the more stable, oxidized form.

Mayhew and her co-authors, including Templeton, submerged rocks in water in the absence of oxygen to determine if a similar reaction would take place at much lower temperatures, between 122 and 212 degrees Fahrenheit (50 to 100 degrees Celsius). The researchers found that the rocks did create hydrogen -- potentially enough hydrogen to support life.

To understand in more detail the chemical reactions that produced the hydrogen in the lab experiments, the researchers used "synchrotron radiation" -- which is created by electrons orbiting in a humanmade storage ring -- to determine the type and location of iron in the rocks on a microscale.

The researchers expected to find that the reduced iron in minerals like olivine had converted to the more stable oxidized state, just as occurs at higher temperatures. But when they conducted their analyses at the Stanford Synchrotron Radiation Lightsource at Stanford University, they were surprised to find newly formed oxidized iron on "spinel" minerals found in the rocks. Spinels are minerals with a cubic structure that are highly conductive.

Finding oxidized iron on the spinels led the team to hypothesize that, at low temperatures, the conductive spinels were helping facilitate the exchange of electrons between reduced iron and water, a process that is necessary for the iron to split the water molecules and create the hydrogen gas.

"After observing the formation of oxidized iron on spinels, we realized there was a strong correlation between the amount of hydrogen produced and the volume percent of spinel phases in the reaction materials," Mayhew said. "Generally, the more spinels, the more hydrogen."

Not only is there a potentially large volume of rock on Earth that may undergo these low temperature reactions, but the same types of rocks also are prevalent on Mars, Mayhew said. Minerals that form as a result of the water-rock reactions on Earth have been detected on Mars as well, which means that the process described in the new study may have implications for potential Martian microbial habitats.

Mayhew and Templeton are already building on this study with their co-authors, including Thomas McCollom at CU-Boulder's Laboratory for Atmospheric and Space Physics, to see if the hydrogen-producing reactions can actually sustain microbes in the lab.

Source: Science Daily

R.Sawas

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