Swarm-mongering: Brainless blobs flock together

Birds of a feather flock together and now so do brainless, inanimate blobs. Made of microscopic particles, the artificial swarms could shed light on the mysterious mechanisms behind the natural swarming seen in fish and birds. They might also lead to materials with novel properties like self-healing.

Animals such as birds, fish and even humans that move together in swarms have individual intelligence, but Jérémie Palacci of New York University and colleagues wondered whether inanimate objects could also swarm. "From a physicist's point of view, if many different systems behave in the same way there must be an underlying physical rule," he says.

To explore this idea, the team created microscopic plastic spheres, each one with a cubic patch of haematite, an iron oxide, on its surface. When submerged in hydrogen peroxide, the spheres spread out in a disordered fashion. The team then shone blue light on the particles, causing the haematite cubes to catalyse the breakdown of any nearby hydrogen peroxide into water and oxygen. As hydrogen peroxide concentration dropped temporarily in these regions due to the reaction, osmotic forces cause more hydrogen peroxide to flow into them, and that in turn buffets the spheres. The whole process then repeats.

Self-healing swarm

When two spheres come close enough to each other, the balance of chemical forces shifts so that the two spheres are attracted. If there are enough spheres in the same place they will cluster together to form shapes of symmetrically arranged particles, which the team call crystals (see video, above). These crystals continue to be buffeted by the movement caused by the breakdown of hydrogen peroxide – but now they move together as one object, replicating a life-like swarm. Switch off the light, however, and the reaction stops, causing the crystal to lose the forces that hold it together, and the particle distribution becomes disordered once again.

"This system shows that even though the particles have no social interaction or intelligence, you can exhibit collective behaviour with no biology involved," says Palacci. Since the haematite is magnetic, it is even possible to steer the crystals in one direction by applying a magnetic field. Such control might be useful if the artificial swarms are to be harnessed for applications.

As the particles automatically fill any gaps that form in the crystal, again thanks to the chemical dynamics of the system, they could be used to create a self-assembling, self-healing material. The work is published in the journal Science today.

Schooled by fish

Iain Couzin of Princeton University says these kinds of systems are very useful for studying biological collective behaviour because researchers have complete control over their interactions – unlike natural systems.

His team has its own swarming experiment published in the same issue of Science, based on schools of fish that prefer to stay in shade. Their paper shows that shining a light on some of the fish in the school causes them to speed up, to get away from the light. But as a result, non-illuminated fish also speed up, even though, if acting purely as individuals, they would have had no reason to do so. "We show just by using simple interactions that schools can have a sense of responsiveness to the environment that individuals do not have," he says.

Couzin sees no reason why such behaviour should be limited to natural systems. "In future it may be possible to create systems of particles that can make collective decisions – something we often think of as only possible in biological systems," he says.

Journal references: Living crystals: Science, DOI: 10.1126/science.1230020; Fish: Science, DOI: 10.1126/science.1225883

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"The sooner, the better" for COC on South China Sea: Shanmugam

SINGAPORE: Foreign Affairs Minister K Shanmugam has reiterated the need for a Code of Conduct (COC) on the South China Sea, saying the sooner it is started the better.

He said this in a live interview with the BBC on Friday morning, covering issues such as the South China Sea claims, US-China relations and ASEAN.

He was asked whether it is possible to have some kind of resolution via ASEAN.

Mr Shanmugam replied that ASEAN has been trying to make it clear that territorial disputes can only be solved by the claimant states themselves.

But the regional grouping can put in place a structure that shows and tells people how they have to structure their conduct with each other. And this is why ASEAN has been pushing for the COC.

Mr Shanmugam said the COC should apply to all countries in the way they interact with each other in the region.

Asked how concerned Asia should be over what's perceived as an increasingly assertive China, Mr Shanmugam said this has to be looked at in context.

He said no leader of China, as well as leaders of many countries, can afford to be seen to be soft on sovereignty.

The real issue is whether they can put in place a modus vivendi to deal with territorial and sovereignty issues.

Mr Shanmugam pointed out that the actual disputes will take a very long time to settle and stressed that the issue is how countries behave so that the disputes do not escalate into clashes, which could be terrible for the region.

- CNA/ir

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DotCom's Mega removing legitimate files

Thousands of legitimate files are being blocked and removed from users' Mega accounts, even when the file is legal for sharing, according to a report.

TorrentFreak tested the situation, uploading a number of files free for sharing, including, amusingly, a video explaining fair use and a copy of Mega founder Kim DotCom's own music single. All were removed within minutes, with TorrentFreak receiving e-mails from Mega explaining that a take-down notice had been issued on the files.

The problem is that Kim DotCom recently took to Twitter to claim that Mega was receiving only 50 copyright take-down notices a day, which doesn't explain the number of files being removed.

Read more of "Kim Dotcom's Mega removing legitimate files" at CNET Australia.

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Sinkhole Swallows Buildings in China

Photograph from AFP/Getty Images

The sinkhole that formed in the southern Chinese city of Guangzhou (pictured) is, unfortunately, not a new occurrence for the country.

Many areas of the world are susceptible to these sudden formations, including the U.S. Florida is especially prone, but Guatemala, Mexico, and the area surrounding the Dead Sea in the Middle East are also known for their impressive sinkholes. (See pictures of a sinkhole in Beijing that swallowed a truck.)

Published January 31, 2013

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Arias' Lawyer Shows Ex-Boyfriend's Lewd Photos

Accused murderer Jodi Arias was kept away from the Mormon friends of her lover Travis Alexander and their torrid sex affair was kept secret by Alexander, even as he sent lewd photos of himself to her online, according to court testimony today.

The testimony in Arias' trial for killing Alexander in 2008 was intended to bolster the defense's argument that she killed him in self defense, that Alexander was a sexual deviant who treated Arias as his "dirty little secret."

Arias' attorneys introduced as evidence photos that Alexander took of his penis and sent to Arias, part of a string of graphic messages and sexual phone calls the two engaged in while Alexander, an elder in the Mormon church, was supposed to be chaste.

Today's witness was the latest in a string called by the defense, including Alexander's former girlfriend Lisa Daidone, who told the court that Alexander had professed to be a virgin.

Daniel Freeman continued his testimony today, describing how he was a friend of both Arias and Alexander but that Alexander kept Arias distanced from his Mormon pals.

"Travis had made more friends at (the Mormon) ward, and had (Ultimate Fighting Championship) fight nights at his house many times, and Jodi was in town, but she wasn't there," Freeman said.

"There was that group of friends, them and Jodi, two different groups, and so Lisa [Daidone] and friends from church were there, but Jodi wasn't there," Freeman said.

Jodi Arias Murder Trial: Former Boyfriend Takes Stand Watch Video

Jodi Arias Murder Trial: Defense's First Day of Witnesses Watch Video

Alexander's behavior, the defense hopes to prove, shows that he mistreated Arias.

Arias, 32, is on trial for murdering Alexander, whom she dated for a year and continued to have a sexual relationship for a year after that. Her attorneys claim that Alexander was abusive and controlling toward Arias, and that she was forced to kill him.

Freeman described how he took a trip with his sister, Alexander, and Arias, and how Alexander had asked him to come along so that he and Arias "would not get physical."

"I don't know that I can say he didn't want to be alone with her, but he liked that when I was there, and my sister was there. They weren't as physical," Freeman said.

Freeman admitted that he had no idea Alexander and Arias had been having a sexual relationship the entire time they were together. He said Alexander never mentioned that to his friends.

In fact, Freeman noted that Alexander was considered to be a church elder when he baptized Arias into the Church of Latter-Day Saints. Both a church elder and a convert were expected to abide by the church's strict law of chastity, which banned any sexual relations outside of marriage.

"One thing people give up in this baptism process was sex," prosecutor Juan Martinez said. "Did you know she was having oral sex with Mr. Alexander at the time of her baptism? Would that be an insincere baptism?"

"She would not be ready to be baptized in that case," Freeman said.

"You were asked about Miss Arias, whether she was worthy of baptism if she was performing oral sex, but what about the elder receiving oral sex?" defense attorney Kirk Nurmi said.

"They would not be worthy of performing that ordinance at that time until they had gone through repentance," Freeman said. "They would go to a discipline council and could face excommunication or a probation period or have their priesthood removed."

Freeman said that Alexander never confessed to having a sexual relationship with Arias.

Freeman's testimony came on the third day of the defense's attempt to paint Alexander as a controlling, sex-obsessed liar who was cruel to Arias. Other witnesses have said that Alexander cheated on other women he dated with Arias, and lied to his friends and family about their relationship.

The defense also had Freeman point out that Alexander was strong and fit. They are expected to conclude that Alexander was physically threatening Arias when she killed him.

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Today on New Scientist: 30 January 2013

Timbuktu's precious scientific texts must be saved

Islamist militants in Mali have burned documents that attest to science in Africa before European colonisation - what remains must be protected

Think that massage feels good? Try adding drugs

Nerve bundles that respond to stroking have been identified and chemically activated in mice

How Obama will deliver his climate promise

The US is set to meet - and maybe exceed - Obama's pledge to cut US emissions by 17 per cent, which could give a boost to international climate talks

Minimum booze price will rein in alcohol abuse

Evidence suggests the UK government's proposal to set a minimum price for alcohol could save thousands of lives, and billions of pounds of public money

First real time-travel movies are loopers

Hollywood has played with time travel for decades, but now physicists have the first movies of what travelling to the past actually looks like

Surfer rides highest wave ever caught

Garret McNamara of Hawaii claims to have ridden the highest wave ever caught by a surfer, a 30-metre monster off the coast of Nazaré, Portugal

Infrared laptop trackpad ignores accidental touches

Longpad is a touchpad that extends the full width of your laptop and uses infrared sensors to ignore any unwanted touches

Close call coming: Averting the asteroid threat

With an errant space rock heading this way, just how good are our asteroid defences - and how do we avert the cataclysm?

The right to fight: women at war

The US military has accepted women into combat. What can science tell us about how women deal with being in the line of fire? And are they any different to men?

Earth and others lose status as Goldilocks worlds

Several planets are taking a hit thanks to a redefinition of the habitable zone - the area around a star in which liquid water can theoretically exist

The 10,000-year bender: Why humans love a tipple

Our taste for alcohol results from an evolutionary tussle between humans and yeast - one in which the microbes have often had the upper hand

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More people volunteering their services to help others: survey

SINGAPORE: More people are giving their time and making the effort to help others, with one in three serving as volunteers in 2012.

A survey by the National Volunteer & Philanthropy Centre (NVPC) found that about 32 per cent of its respondents were volunteers, which is the highest rate since it started the survey in 2000.

The same survey conducted in 2010 had 23 per cent.

The survey, conducted between July and September 2012, found that the increase was largely driven by the interest in informal volunteering.

This refers to activities like reading to the child of a needy neighbour, instead of being part of a formal organisation.

The survey also found that individual donations remained steady at about $1.1 billion in 2012, compared with $1.07 billion in 2010.

Those who earned below $1,000 a month donated a bigger share of their income - at 1.8 per cent.

That's higher than the 0.5 per cent for those earning between $5,000 and below $6,000.

More than 1,500 people took part in the survey, which did not include compulsory community work by students.

- CNA/de

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Tumblr avoids porn label and adds mature rating to iOS app

Tumblr's iPhone app.

(Credit:
Tumblr)

Tumblr looks to be trying to avoid the porn-war that recently harangued the 500px photo app and Twitter's Vine app.

The microblogging company threw up a 17-and-over age warning for its iOS app for all new users and any people updating their app to the 3.2.4 version, which was released today.

"You must be at least 17 years old to download this app," Tumblr writes in its description of the app in the iTunes App Store, because it contains "Frequent/Intense Sexual Content or Nudity."

The app's upgrade says only that it will carry out "small bug fixes." However, when users click on the 3.2.4 version, they're forced to confirm they are over the age of 17. "Tumblr contains age-restricted material," the app says when upgrading. "Tap OK to confirm that you are 17 or over. Your content will then begin downloading immediately."

It's unclear exactly why Tumblr changed its app to contain a mature rating. But it's no secret that certain blogs on the site contain "sexual content" and "nudity." In an interview last June, Tumblr founder David Karp noted that 2 percent to 4 percent of the traffic on Tumblr is porn-related.

Tumblr's 17+ rating comes as 500px and Vine have been scrutinized for making porn easily accessible. When Twitter released the Vine app last week, many users quickly found a handful of videos featuring male exhibitionism and other activity. Apple quickly stopped promoting Vine in its App Store.

500px had an even more severe reprimand. After complaints of the app containing pornographic images and material, Apple pulled it from
iTunes. Now that 500px has added warnings and a 17+ rating, Apple allowed it back into the App Store.

Maybe Tumblr is acting preemptively with its new 17+ rating. CNET contacted Tumblr for comment. We'll update the story when we get more information.

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New Theory on How Homing Pigeons Find Home

Jane J. Lee

Homing pigeons (Columba livia) have been prized for their navigational abilities for thousands of years. They've served as messengers during war, as a means of long-distance communication, and as prized athletes in international races.

But there are places around the world that seem to confuse these birds—areas where they repeatedly vanish in the wrong direction or scatter on random headings rather than fly straight home, said Jon Hagstrum, a geophysicist who authored a study that may help researchers understand how homing pigeons navigate.

Hagstrum's paper, published online Wednesday in the Journal of Experimental Biology, proposes an intriguing theory for homing pigeon disorientation—that the birds are following ultralow frequency sounds back towards their lofts and that disruptions in their ability to "hear" home is what screws them up.

Called infrasound, these sound waves propagate at frequencies well below the range audible to people, but pigeons can pick them up, said Hagstrum, who works at the U.S. Geological Survey in Menlo Park, California.

"They're using sound to image the terrain [surrounding] their loft," he said. "It's like us visually recognizing our house using our eyes."

Homeward Bound?

For years, scientists have struggled to explain carrier pigeons' directional challenges in certain areas, known as release-site biases.

This "map" issue, or a pigeon's ability to tell where it is in relation to where it wants to go, is different from the bird's compass system, which tells it which direction it's headed in. (Learn about how other animals navigate.)

"We know a lot about pigeon compass systems, but what has been controversial, even to this day, has been their map [system]," said Cordula Mora, an animal behavior researcher at Bowling Green State University in Ohio who was not involved in the study.

Until now, the two main theories say that pigeons rely either on their sense of smell to find their way home or that they follow the Earth's magnetic field lines, she said.

If something screwed up their sense of smell or their ability to follow those fields, the thinking has been, that could explain why pigeons got lost in certain areas.

But neither explanation made sense to Hagstrum, a geologist who grew interested in pigeons after attending an undergraduate lecture by Cornell biologist William Keeton. Keeton, who studied homing pigeons' navigation abilities, described some release-site biases in his pigeons and Hagstrum was hooked.

"I was just stunned and amazed and fascinated," said Hagstrum. "I understand we don't get dark matter or quantum mechanics, but bird [navigation]?"

So Hagstrum decided to look at Keeton's pigeon release data from three sites in upstate New York. At Castor Hill and Jersey Hill, the birds would repeatedly fly in the wrong direction or head off randomly when trying to return to their loft at Cornell University, even though they had no problems at other locations. At a third site near the town of Weedsport, young pigeons would head off in a different direction from older birds.

There were also certain days when the Cornell pigeons could find their way back home from these areas without any problems.

At the same time, homing pigeons from other lofts released at Castor Hill, Jersey Hill, and near Weedsport, would fly home just fine.

Sound Shadows

Hagstrum knew that homing pigeons could hear sounds as low as 0.05 hertz, low enough to pick up infrasounds that were down around 0.1 or 0.2 hertz. So he decided to map out what these low-frequency sound waves would have looked like on an average day, and on the days when the pigeons could home correctly from Jersey Hill.

He found that due to atmospheric conditions and local terrain, Jersey Hill normally sits in a sound shadow in relation to the Cornell loft. Little to none of the infrasounds from the area around the loft reached Jersey Hill except on one day when changing wind patterns and temperature inversions permitted.

That happened to match a day when the Cornell pigeons had no problem returning home.

"I could see how the topography was affecting the sound and how the weather was affecting the sound [transmission]," Hagstrum said. "It started to explain all these mysteries."

The terrain between the loft and Jersey Hill, combined with normal atmospheric conditions, bounced infrasounds up and over these areas.

Some infrasound would still reach Castor Hill, but due to nearby hills and valleys, the sound waves approached from the west and southwest, even though the Cornell loft is situated south-southwest of Castor Hill.

Records show that younger, inexperienced pigeons released at Castor Hill would sometimes fly west while older birds headed southwest, presumably following infrasounds from their loft.

Hagstrum's model found that infrasound normally arrived at the Weedsport site from the south. But one day of abnormal weather conditions, combined with a local river valley, resulted in infrasound that arrived at Weedsport from the Cornell loft from the southeast.

Multiple Maps

"What [Hagstrum] has found for those areas are a possible explanation for the [pigeon] behavior at these sites," said Bowling Green State's Mora. But she cautions against extrapolating these results to all homing pigeons.

Some of Mora's work supports the theory that homing pigeons use magnetic field lines to find their way home.

What homing pigeons are using as their map probably depends on where they're raised, she said. "In some places it may be infrasound, and in other places [a sense of smell] may be the way to go."

Hagstrum's next steps are to figure out how large an area the pigeons are listening to. He's also talking to the Navy and Air Force, who are interested in his work. "Right now we use GPS to navigate," he said. But if those satellites were compromised, "we'd be out of luck." Pigeons navigate from point to point without any problems, he said.

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No Device Eliminates Concussion Risk, Experts Say

As the long-term consequences of concussions become clearer, a cottage industry has popped up to sell athletes and worried parents products designed to mitigate risks of concussions that even helmets cannot prevent.

Despite the bold claims of some companies, however, many experts say the Holy Grail in contact sports -- a device that prevents concussions -- simply does not exist. Indeed, experts say, there is no proof that any current device significantly reduces the risk of concussions beyond the protections already provided by helmets.

"Nightline" found several products for sale online that aim to reduce the risk of concussions or even alert parents and coaches when a kid has supposedly taken a concussion-level hit. The claims the manufacturers make are often breathtakingly reassuring.

Concern about the risk of concussion is mounting at every level of the gridiron from the NFL to colleges and even high schools. Concussions are the most common injury among high school football players.

Jennifer Branin, whose son Tyler Branin is one of the stars of the Woodbridge Warriors high school football team in Irvine, Calif., said "it was scary" the first time he had a concussion.

"He had lost his balance on the field," she said. "He got up and tried to continue, but couldn't keep his balance."

Junior Seau Had Brain Disease, Researchers Say Watch Video

She said the effects of the concussion lingered, causing Tyler to miss a week of school and football practice. Even months later, he complained of difficulty concentrating in class.

Parents such as Jennifer Branin, who is president of the team's booster club, and her husband, Andy Branin, a former college football player himself, were looking for a way to support their son's desire to play football while also keeping him safe.

"He wants to play and, as a mom, you may want to put bubble-wrap around them and protect them forever, but that's not going to happen," she said.

So Jennifer Branin decided to do something. She raised money to buy the team helmet inserts by Unequal Technologies for added protection.

Unequal Technologies, one of the highest profile players in this new market, described its product explicitly on the box as "Concussion Reduction Technology," or "CRT." It is a strip of composite material including bullet-proof Kevlar that is designed to stick inside the helmet as a liner to the existing helmet pads.

Unequal Technologies uses its material in products ranging from padded sleeves to shin guards. The company counts NFL players and X-Games athletes among its fans.

On board as paid spokesmen are Philadelphia Eagles quarterback Michael Vick and James Harrison, a linebacker for the Pittsburgh Steelers. Harrison is one of the hardest-hitting guys in the NFL and said he uses Unequal Technology's liners in his helmet.

"I don't know what it's made of but it works," Harrison says in one of Unequal's promotional videos. "I really don't feel like I'm taking a risk."

Vick wasn't wearing the CRT product when he suffered a season-ending concussion in November, but he has since promised that he will be wearing it when he returns to the field next season.

Rob Vito, founder and CEO of the Kennett Square, Pa.-based company, said he worked with scientists to create a military-grade composite material that can help protect athletes from all kinds of injuries from head to toe.

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