Wednesday 23 February 2011

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

Cellphone Radiation Increases Brain Activity

Posted: 22 Feb 2011 03:00 PM PST

Radiation from a mobile phone call can make brain regions near the device burn more energy, according to a new study.

Cellphones emit ultra-high-frequency radio waves during calls and data transfers, and some researchers have suspected this radiation — albeit inconclusively — of being linked to long-term health risks like brain cancer. The new brain-scan-based work, to be published Feb. 23 in the Journal of the American Medical Association, shows radiation emitted from a cellphone's antenna during a call makes nearby brain tissue use 7 percent more energy.

"We have no idea what this means yet or how it works," said neuroscientist Nora Volkow of the National Institutes of Health. "But this is the first reliable study showing the brain is activated by exposure to cellphone radio frequencies."

More than 5 billion mobile devices may be in use worldwide today. From behavioral quirks to brain cancer, researchers have looked for any health risks associated with cellphone radiation for years. Volkow said, however, that most research has produced conflicting results.

"These studies used only 14 people, at most, and looked at brain activity over brief time spans of about 60 seconds. A cellphone's effect on the brain is very weak, so you lose statistical power with small sample sizes and durations," said Volkow. "Our study had 47 usable subjects monitored over a long time to get us significant data."

Cancer epidemiologist Geoffrey Kabat of the Albert Einstein College of Medicine said the work can't and doesn't offer any clinical predictions, but regarded it as the best to date on cellphone radiation's effects on the brain.

"It's a really even-handed look at this problem, and it shows a small effect that scales with exposure," said Kabat, author of the book Hyping Health Risks. "I'm really curious to see where future research leads."

 

Cellphones use ultra-high-frequency radio waves to connect with telecommunications networks. Antennas within phones emit the waves and, while the strength tails off quickly as distance from the antenna increases, a sizable chunk of it is beamed through the brain.

As a result, federal agencies require phone manufacturers to post information about how much radiation the body might absorb for each model, called its Specific Absorption Rate or SAR. Measured in watts per kilogram of tissue, it reveals how much radiation parts of the body are exposed to during use of a mobile device.

The simple cellphone used in Volkow's study, a Samsung Knack phone popular in New York, has a peak SAR in the head of just under 1 watt per kilogram of tissue. The Phone 4 has a peak SAR in the head twice as high, while sun's average SAR across the body is 4 or 5 times higher.

Some studies have suggested a small yet significant link between long-term cellphone SARs and certain brain cancers, including glioma and meningioma, but most investigations have found no such links. To abolish any uncertainty, the World Health Organization tasked a group of scientists to review all known related research. Their 2010 Interphone report showed no substantial link with mobile phone use and incidence of brain cancers, and in fact found reduced rates for some types.

'The effect is very small, but it's still unnatural. Nature didn't prepare our brains for this.'

Still, Volkow said, understanding close-up and long-term exposure to cellphone radiation is important.

"The state of knowledge is really speculative. No studies have determined mechanisms for what we have seen, or other effects such as increased blood flow in the brain," Volkow said. "I have spent hours on the phone with my sister every week, and have done it for years, so I would like to know if that's harmful or not."

Volkow and a team of researchers scanned the brains of 47 people with a cellphone attached to each side of their head. One phone was turned off, while the other had an active call going for 50 minutes. It was muted to prevent the audio from having effects on brain activity.

Twenty minutes into the call, clinicians injected a radioactive form of sugar into each person, then began imaging their brains with a Positron Emission Topography machine. Over the course of 30 minutes, the sugar pooled in the brain's most active regions and revealed the energy use to the brain scanner.

Accounting for normal activity, the subjects showed about a 7 percent boost in sugar use on the side of the head where the active cellphone was.

Brain imaging physicist Dardo Tomasi of Brookhaven National Laboratory, who co-authored the study, said that's several times less activity than visual brain regions show during an engaging movie.

"The effect is very small, but it's still unnatural. Nature didn't prepare our brains for this," Tomasi said.

Although the mechanism for the effect and its long-term consequences aren't known, Volkow said it's cheap and worthwhile to take matters into your own hands.

"You don't have to wait around on us for the answers. Just use a wired headset or the speakerphone function," she said. "That keeps the phone far enough away to make it an insignificant risk."

Image: A bottom-of-the-brain view showing average use of radioactive glucose in the brains of 47 subjects exposed to a 50-minute phone call on the right side of their head. (Nora Volkow/JAMA)

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Shields Up: Why Last Week’s Solar Storm Was a Dud

Posted: 22 Feb 2011 02:37 PM PST

When the largest flare in four years erupted from the sun Feb. 14, sky watchers across the Northern Hemisphere braced themselves for a geomagnetic storm. Space weather experts predicted that jets of charged particles smacking into the Earth's magnetic field could disrupt navigation and communication systems, and spark a bonus of bright northern lights dancing across the ionosphere.

Instead, nothing much happened.

"There were some nice displays of aurora, but you had to live in Finland, northern Canada or Alaska to see them," said Joe Kunches, a forecaster at the National Oceanic and Atmospheric Administration's Space Weather Prediction Center. "This one was the lowest storm category that we even pay any attention to."

The storm was so weak because the flare's magnetic field happened to be aligned parallel to the Earth's. When the sun sends a mass of hot plasma hurtling toward the planet in a coronal mass ejection, the plasma is imprinted with its own magnetic field separate from the sun's. Astronomers can't predict the direction of the plasma's magnetic field until the burst hits Earth.

If the plasma's magnetic field is parallel to the Earth's, the incoming charged particles are effectively blocked from entering Earth's magnetosphere. An identical flare with a perpendicular magnetic field would have triggered a much stronger storm.

"If the magnetic fields are parallel, then the shields are up. We are well protected," said space weather expert Juha-Pekka Luntama of the European Space Agency Feb. 19 at the meeting of the American Association for the Advancement of Science in Washington, DC.

 

But next time we might not be as lucky with alignment, and we can expect up to 1,700 more storms like last week's in the coming months as the sun wakes back up.

NOAA ranks geomagnetic storms on a scale from G1, minor storms that spark auroras in Michigan and Maine, to G5, extreme storms that can shut down power grids and cause northern lights as far south as Florida. The ranking is based on how much more active the local magnetic field is than a normal, quiet day.

The Feb. 14 storm turned out to be a G1, meaning "it wasn't that big a deal," Kunches said.

The storm was mostly notable for being the first of the new solar cycle, Kunches said. The sun goes through periods of relative violence and calm every 11 years or so. This last solar minimum was longer and quieter than astronomers expected. Many predict that the ensuing solar maximum, when magnetic activity on the sun will cause more frequent and severe flares, will also be relatively serene.

But space-weather experts are more nervous about this solar maximum than ever before. Since the last solar maximum in 2000, society has grown more dependent on systems that can be knocked out by a strong solar flare.

"Things have changed a lot since 2000," Tom Bogdan, director of NOAA's Space Weather Prediction Center, told reporters Feb. 19 at AAAS. "What's at stake are the advanced technologies that underlie our lives."

A strong flare would send ultraviolet and X-ray radiation to the sunlit side of the Earth, ionizing the upper atmosphere and potentially shutting down GPS satellites. Losing GPS would cause chaos in more than just car navigation systems, Bogdan said.

"GPS is involved in everything we do," he said, including financial transactions. Prices fluctuate so quickly that traders need a time stamp accurate to a millionth of a second every time they buy or sell something. Every time you swipe your credit card at the gas station or buy a bag of oranges, Bogdan said, it goes through a GPS satellite.

Ten to 20 minutes after the flare, a burst of high-energy protons would enter the Earth's magnetic field at the poles, causing processing errors in other satellites.

About half an hour later, the hot cloud of plasma that the sun spit out with the flare would bump into the Earth's magnetic field. If it's strong enough, the plasma's magnetic field can induce currents in electric transmission lines, which could cause widespread blackouts. The most powerful solar flare in recorded history, the Carrington flare in September 1859, sent currents through telegraph wires and even set a few buildings on fire.

Bogdan noted that that storm and the next-strongest storm in 1921 both happened during particularly weak solar cycles.

Still, he said, "don't panic." Many satellites and transmission lines are already fitted with shields to prevent the worst of the damage from a strong flare. Others can be shut down preemptively. Sun-observing satellites give space weather experts about 20 hours to come up with a plan to deal with an impending storm, during which NOAA sends out detailed alerts.

"This recent solar flare really illustrates that we need to pay attention to space weather," said NOAA administrator Jane Lubchenco at the AAAS meeting. "The watchword is, predict and prepare."

Interested sky watchers can sign up to receive space-weather alerts on their phones, and watch for more flares in the next two years. NOAA predicts 100 storms that will spark auroras as far south as Alabama.

Image: NASA/Solar Dynamics Observatory

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Tiny Capsules Can Heal Worn-Out Batteries

Posted: 22 Feb 2011 07:22 AM PST

WASHINGTON — A newly created lithium-ion battery that can heal itself may improve the life span and safety of today's energy-storage technologies, researchers report.

Rechargeable lithium-ion batteries power cell phones, laptops and other portable electronics. But, like any batteries, they tend to break down over time.

"There are many different types of degradation that happen, and fixing this degradation could help us make longer-lasting batteries," said Scott White, a materials engineer at the University of Illinois at Urbana-Champaign who reported the details of the battery Feb. 20 at a meeting of the American Association for the Advancement of Science.

One site of damage is the anode, a battery's negatively charged terminal. As a battery charges and discharges, the anode swells and shrinks. Over time, this cycling causes damage, creating cracks that can interfere with the flow of current and, ultimately, kill the battery.

To counteract this cracking, White embedded tiny microspheres inside the graphite of an anode. As cracks formed in the anode, they tore open the plastic shells, releasing the contents within: a material called indium gallium arsenide. This liquid metal alloy seeped out of the spheres and filled the cracks in the anode, restoring the flow of electricity.

 

Damage to a battery — or a short circuit between its components — can cause problems other than a shorter life span. Out-of-control electrical currents have been known to create hot spots that grow into a raging fire.

"It's not a common occurrence, but when it happens, the consequences are severe," White said. Battery fires have prompted laptop recalls by Dell and Hewlett-Packard, and the U.S. Department of Transportation has proposed stricter rules for cargo planes that transport large quantities of lithium-ion batteries.

To safeguard against this type of failure, White developed a second kind of microsphere made of solid polyethylene, an inexpensive and widely available plastic. A small quantity of these spheres embedded in the anode and other battery components can function as a safety cutoff switch. If the temperature inside the battery rises above 105° Celsius, the spheres melt into a thin layer of insulating material that shuts off the flow of electricity, preventing a conflagration.

"We've tested this in real batteries," said White, whose research is funded by the U.S. Department of Energy. "It works beautifully." This safety feature, he said, could be useful for the electric cars emerging on the market.

"Lithium-ion batteries will continue to be the technology used for the next 10 to 15 years in electric cars," said Kristin Persson of Lawrence Berkeley National Laboratory in California, who is looking for new battery materials that not only have better energy storage but also avoid some of the pitfalls of traditional batteries. "It will take at least that amount of time to develop new materials."

Images: 1) A scanning electron microscope image of microcapsules used in self-healing polymers. Microcapsules in the center are about 100 microns wide. (Ben Blaiszik/University of Illinois) 2) Tiny plastic microcapsules are the secret to a battery that can heal itself when damaged. (Magnus Andersson/University of Illinois)

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Alan Turing’s Patterns in Nature, and Beyond

Posted: 22 Feb 2011 04:00 AM PST

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Alan Turing's Biology Paper

Near the end of his life, the great mathematician Alan Turing wrote his first and last paper on biology and chemistry, about how a certain type of chemical reaction ought to produce many patterns seen in nature.

Called "The Chemical Basis of Morphogenesis," it was an entirely theoretical work. But in following decades, long after Turing tragically took his own life in 1954, scientists found his speculations to be reality.

First found in chemicals in dishes, then in the stripes and spirals and whorls of animals, so-called Turing patterns abounded. Some think that Turing patterns may actually extend to ecosystems, even to galaxies. That's still speculation — but a proof published Feb. 11 in Science of Turing patterns in a controlled three-dimensional chemical system are even more suggestion of just how complex the patterns can be.

On the following pages, Wired.com takes you on a Turing pattern tour.

Images: Left: Alan Turing. (Ohio State University) Right: Patterns generated by a computer simulation of the Turing model. each is made by the same basic equation, with its parameters slightly tweaked. (Shigeru Kondo & Takashi Miura/Science)

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