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Wednesday, February 18, 2009

String theory officially useful, may not represent reality

What do some of the coldest gasses and hottest plasmas have in common? String theory may help model why they seem to behave as quantum liquids.

By John Timmer

String theory officially useful, may not represent reality
A collision in the RHIC collider

Brookhaven National Laboratory has what is currently one of the highest energy particle accelerators on the planet. The Relativistic Heavy Ion Collider (RHIC) hosts collisions between the nuclei of gold atoms that are moving at roughly 99 percent of the speed of light, creating a quark soup similar to the one that existed immediately after the big bang. But the scientists running the experiments started noticing something funny about the data: instead of expanding evenly outward, the collision debris were ellipsoidal (think a 3-D ellipse). What was even stranger was that this sort of behavior had already been described, for a gas of lithium atoms at the opposite end of the temperature spectrum, at a fraction of a microkelvin. As these groups were talking about a collaboration, things got stranger still when string theorists started citing this work, since the behavior had already been predicted through their work—a fact that the physicists weren't aware of until a science reporter called to ask what they thought about it.

The tale of this unlikely collaboration unfolded at the American Association for the Advancement of Science meeting, where the introductory remarks described just how far apart these systems are. In terms of temperature, the RHIC and chilled lithium differ by 19 orders of magnitude (that's a factor of 1019). When it comes to density, the difference is an astonishing 25 orders of magnitude. Meanwhile, the bit of string theory that describes the normal, four-dimensional (3-D + time) behavior of these systems can be predicted by modeling a four-dimensional sphere wrapped around a five dimensional black hole.

Quantum viscosity runs hot and cold

The cold atomic cloud is probably easiest to understand, although John Thomas of Duke, who does the work, claimed that, when dragged to wine tastings with his wife's friends, "I wait until everyone's sufficiently drunk before explaining what we do." His short description is that he makes bowls of light; in principle, the first steps in his system involve the sort of laser cooling that our Chris Lee has described in the past. This can only get things down to a bit under a kelvin above absolute zero, but Thomas then loosens the laser trap, and a few atoms evaporate off, taking most of the remaining heat with them. The end result is an atomic cloud at one-tenth of a microkelvin.

The 6Li atoms that he uses have up and down spins that form an analog of the cooper pairs of electrons that cause high-temperature superconductivity, so his system allows theorists to test some of their ideas in an accessible experimental system. But it also has interesting properties when in a magnetic field. At a specific magnetic field strength, the interactions between the paired atoms start to go asymptotic and, when at a very precise point, the interactions vanish and quantum effects dominate. When the laser trap is released again, the atoms expand elliptically, displaying essentially the smallest amount of quantum viscosity possible. Because the system is experimentally possible, they were able (on the advice of string theorists—more on that below) to measure both the viscosity and entropy, and found that they were related directly to one divided by four π.

Smaller accelerator, bigger atoms: Brookhaven's RHIC

Out at the other end of the temperature spectrum, the collisions in the RHIC were producing what Brookhaven's Barbara Jacack termed "quark soup." In normal matter, quarks interact by exchanging gluons with a limited number of partners. But, at the densities that exist immediately after these collisions, quarks can exchange multiple gluons with multiple partners, leading to longer-range interactions that are more similar to those in a liquid. Two aspects of the behavior seen by RHIC's detectors, however, were a bit surprising. The first is the ellipsoidal expansion that marks the behavior of perfect quantum liquids that we mentioned above. The second is that, although radiation can pass across the small cluster of quark soup, the actual quarks, it appeared, could not. Jacack likened the fact that even the heavy charm quark didn't make it across the collision to a set of bowling pins stopping an incoming ball.

Like Thomas, talking to string theorists allowed Jacack and her team to look for some specific properties—in this case, shock waves of a particular type—of the quark soup. So far, it's looking like they're there. RHIC is about to undergo a retrofit that should make it easier to study this, and the stimulus package may have some money for the DOE that could accelerate the work.

The theory needs a five-dimensional black hole, but reality may not

Clifford Johnson of USC then spoke about how a specific application of string theory helped tie everything together. As he described it, Quantum Chromodynamics (QCD) works very well at describing the interactions of a limited number of particles, and its successes in the early 1970s caused researchers to abandon an earlier version of string theory. But QCD doesn't work that well at the densities seen in the RHIC, where ensembles of particles have emergent behavior—as Johnson noted, a single water molecule isn't wet; that's a property that emerges from a population of water molecules. And this, along with a few other vexing problems, has allowed string theory back in the game.

"String theory," Johnson said, "having failed to explain something, got resurrected a few years on and was used to explain everything," or at least provide a quantum description of gravity. He got interested in the problem of describing quantum black holes, which are far smaller than the macroscopic ones we've observed in space. Based on their emission of quantum radiation, they have to have an internal structure, one that our lack of a quantum gravity is preventing us from probing. (During the questions, it became clear that Johnson is one of the few people hoping that the LHC does spawn a small black hole.) It turns out, using the math of string theory, it's easy to examine a five-dimensional black hole simply by wrapping a four-dimensional sheet around it. When you do that, however, a lot of three-dimensional QCD behavior pops out of the equations—"the bugs of string theory become features," as Johnson put it.

Image courtesy of icanhascheezburger.com

In the extra dimensions, gravitons get pulled towards, and then bounce off, the black hole, undergoing interference as they do. That interference apparently describes the behavior seen in both of these real-world systems. Johnson was emphatic that this doesn't mean that the experiments that have used these string theory models are a test of the theory; rather, it means that the predictions of string theory are being used to guide experiments, which is a measure of its utility.

As for whether there's really an extradimensional black hole tucked away in these conditions, Johnson described himself as "agnostic." It may be possible, he said, to find a way to describe this behavior without resorting to anything beyond our familiar dimensions, but, at the moment, string theory's models are simple and functional, so there's no reason not to use them. In the meantime, everyone seems excited about the prospect of further collaboration. As Jacack said when showing a slide with a certain image of a kitten playing with yarn, "you know your field has hit the big time when you make it into lolcats."

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The green-eyed monster that lives in your brain: Scientists discover the jealousy lobe

By Daily Mail Reporter

It is a vice that few can avoid but that nobody craves.

Now the area of the brain which controls jealousy has been found, scientists have ­announced.

It is the same part which detects real physical pain – perhaps explaining why feeling envious of your lover's philandering ways hurts so much.

The spot which makes people delight in others' misfortune – called schadenfreude – was also located by the team.

'It's interesting the part of the brain which detects physical pain is also associated with mental pain,' said Hidehiko Takahashi, who led the research.

Home of the green-eyed monster: This part of the frontal lobe lights up when you are jealous

Home of the green-eyed monster: This part of the frontal lobe lights up when you are jealous

'Assessing these feelings of jealousy will possibly be helpful in mental care such as counselling.'

'Envy is corrosive and ugly, and it can ruin your life,' Richard Smith, a professor of psychology at the University of Kentucky told the New York Times.

'If you’re an envious person, you have a hard time appreciating a lot of the good things that are out there, because you’re too busy worrying about how they reflect on the self.'

In the experiments, 19 students were asked to talk of a more successful rival while having MRI scans, which monitor brain activity.

Schadenfreude: This is the region of the brain that controls taking delight in other people's misfortune

Schadenfreude: This is the region of the brain that controls taking delight in other people's misfortune

A part of their frontal lobe became more active when the students felt jealous of their rivals, the Japanese study showed.

They then read a story in which the subject of their envy suffered a series of misfortunes, including food poisoning.

Their scan data showed the mishaps sparked greater activity in the 'reward reaction' part of the brain, which normally lights up when receiving social and financial fortune.

'We have a saying in Japanese, ‘The misfortunes of others are the taste of honey,’' said Mr Takahashi. 'The ventral striatum is processing that ‘honey.’'

And there appears to be a relationship between jealousy and schadenfreude. The scientists noted that the more jealous one person was of another, the more schadenfreude they felt at that person's downfall.

'We now have a better understanding of the mechanism at work when people take pleasure in another's misfortune,' said Mr Takahashi.

'This is the way other needs-processing systems like hunger and thirst work,' Matthew Lieberman of the psychology department at the University of California, Los Angeles, who co-wrote a commentary that accompanies the report, told the New York Times.

'The hungrier or thirstier that you feel, the more pleasurable it is when you finally eat or drink.'

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Varying Sweat Scents Are Noted by Women

By NICHOLAS BAKALAR

Men’s sweat smells different when they are sexually aroused, and women can tell the difference, a new study finds — even though they are not conscious of it.

The sexual activity of animals is affected by odor, but little is known about the phenomenon in humans. Although all three types of sweat glands respond to emotion and sexual arousal, no one has ever convincingly established that body odor plays a significant role in human sexual relations or reproduction.

“In surveys, people say that body odors are important in selecting a mate,” said Denise Chen, the lead author of the study. “But we don’t really know exactly what role body odors play in human sexuality.”

The report, published in the January issue of The Journal of Neuroscience, suggests that women distinguish the odor of sexual sweat from neutral sweat by processing the odors in different parts of the brain.

The researchers had 20 heterosexual male volunteers hold absorbent pads in their armpits while they watched 20 minutes of an erotic film, and then again while they watched a 20-minute film with neutral content. Then they had 19 heterosexual women smell the sexual sweat and neutral sweat pads from the three men who reported the highest level of sexual arousal.

The women also sniffed two additional pads, one moistened with androstadienone, a hormone produced naturally in sweat that some believe is a sex pheromone, and the other a control pad with a slight neutral odor. The pads were presented randomly, and the women were asked to rate the pleasantness and intensity of the odors. While the women sniffed, researchers monitored their brain activity with functional magnetic resonance imaging.

Adam K. Anderson, an assistant professor of psychology at the University of Toronto who was not involved in the study, called the methodology impressive.

“What’s being taken as a stimulus is not some chemical created in a lab — it’s real sweat from people who are sexually aroused,” said Dr. Anderson, who does research in human olfaction. “What a scientist would normally do is try to distill the active component of that very complex perfume. They didn’t do that. They compared the complex sweat to the sex pheromone and found that the brain was much more responsive.”

In their verbal responses, all but two subjects denied smelling any sweat, or anything human, and none verbally distinguished the sexual from the neutral sweat. But their brain activity told a different story.

Two regions of the brain, the right orbitofrontal cortex and the right fusiform region, responded significantly more to the sexual sweat of men than to any of the other smells.

Dr. Chen, an assistant professor of psychology at Rice University, said that only one brain area, the hypothalamus, is known to be important in sexual motivation and behavior, and that region did not respond to the odors. But the researchers did find that the brain somehow recognizes social or emotional information contained in sexual sweat, treating it differently from other odors. In this sense, they conclude, humans communicate with smell.

No man should imagine that based on these conclusions he can improve his sex life by refraining from bathing.

“Our findings do not convey the suggestion that human sweat is an aphrodisiac,” Dr. Chen wrote in an e-mail message.

So what does the scent of a man mean to a woman? Dr. Anderson suggested there was no reason to conclude that men now know what women want. “They didn’t find activations of typical reward centers or regions associated with pleasure,” he said. “It’s just as likely that their brains are picking up a man in heat that they are not particularly attracted to.”

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Frozen Smoke:' Ultimate Sponge For Cleaning Up Oil Spills


Aerogels, a super-lightweight solid sometimes called "frozen smoke," may capture oil from wastewater and soak up environmental oil spills. (Credit: NASA/JPL)

Scientists in Arizona and New Jersey are reporting that aerogels, a super-lightweight solid sometimes called “frozen smoke,” may serve as the ultimate sponge for capturing oil from wastewater and effectively soaking up environmental oil spills.

In the new study, Robert Pfeffer and colleagues point out that the environmental challenges of oil contamination go beyond widely publicized maritime oil spills like the Exxon Valdez incident.

Experts estimate that each year people dump more than 200 million gallons of used oil into sewers, streams, and backyards, resulting in polluted wastewater that is difficult to treat. Although there are many different sorbent materials for removing used oil, such as activated carbon, they are often costly and inefficient. Hydrophobic silica aerogels are highly porous and absorbent material, and seemed like an excellent oil sponge.

The scientists packed a batch of tiny aerogel beads into a vertical column and exposed them to flowing water containing soybean oil to simulate the filtration process at a wastewater treatment plant. They showed that the aerogel beads absorbed up to 7 times their weight and removed oil from the wastewater at high efficiency, better than many conventional sorbent materials.

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Diamond is no longer nature’s hardest material

London: Diamond will always be a woman’s best friend but the gemstone is no longer the world’s hardest material, according to scientists.














Instead, a rare natural substance, called lonsdaleite, which is made from carbon atoms just like diamond, has emerged as 58 per cent harder than the gemstone, according to a report in the New Scientist.

An international team, led by Zicheng Pan at Shanghai Jiao Tong University, simulated how atoms in two substances believed to have promise as very hard materials would respond to the stress of a finely tipped probe pushing down on them.

The simulation revealed that the first one, wurtzite boron nitride, withstood 18 per cent more stress than diamond, while the second, the mineral lonsdaleite, 58 per cent more.

Rare mineral lonsdaleite is sometimes formed when meteorites containing graphite hit Earth, while wurtzite boron nitride is formed during volcanic eruptions that produce very high temperatures and pressures.

If confirmed, however, wurtzite boron nitride may turn out most useful of the two, because it is stable in oxygen at higher temperatures than diamond.

And, according to the scientists, this makes it ideal to place on the tips of cutting and drilling tools operating at high temperatures, or as corrosion resistant films on the surface of a space vehicle, for example. Paradoxically, wurtzite boron nitrides hardness appears to come from the flexibility of the bonds between the atoms that make it up.

When its stressed some bonds tend to re-orientate themselves by about 90 to relieve the tension.

Although diamond undergoes a similar process, something about the structure of wurtzite boron nitride makes it nearly 80 per cent stronger after the process takes place, the studys co-author Changfeng Chen of University of Nevada wrote in the Physical Review Letters journal.

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Most People Believe Dreams Are Meaningful

By LiveScience Staff

Dreams might mean nothing, but many people take them seriously nonetheless, as Sigmund Freud did, new research finds.

People in at least three countries, including the United States, believe dreams contain important hidden truths, said researcher Carey Morewedge, an assistant professor at Carnegie Mellon University in Pittsburgh.

In six different studies, Morewedge and his colleagues surveyed nearly 1,100 people about their dreams. The results are detailed in the February issue of the Journal of Personality and Social Psychology.

"Psychologists' interpretations of the meaning of dreams vary widely," Morewedge said. "But our research shows that people believe their dreams provide meaningful insight into themselves and their world."

In one study that surveyed general beliefs about dreams, Morewedge and co-author Michael Norton, an assistant professor at Harvard Business School, surveyed 149 university students in the United States, India and South Korea. The researchers asked the students to rate different theories about dreams.

Across all three cultures, an overwhelming majority of the students endorsed the theory that dreams reveal hidden truths about themselves and the world, a belief also endorsed by a nationally representative sample of Americans, Morewedge said.

In another study, Morewedge and his colleagues wanted to explore how dreams might influence people's waking behavior. A total of 182 commuters at a Boston train station were asked to imagine that one of four possible scenarios had happened the night before a scheduled airline trip: The national threat level was raised to orange, indicating a high risk of terrorist attack; they consciously thought about their plane crashing; they dreamed about a plane crash; or a real plane crash occurred on the route they planned to take.

A dream of a plane crash was more likely to affect travel plans than either thinking about a crash or a government warning, and the dream of a plane crash produced a similar level of anxiety as did an actual crash, Morewedge found.

Finally, Morewedge wanted to find out whether people perceive all dreams as equally meaningful, or whether their interpretations were influenced by their waking beliefs and desires. So, in another study, 270 men and women from across the United States took a short online survey in which they were asked to remember a dream they had had about a person they knew. People ascribed more importance to pleasant dreams about a person they liked as compared to a person they did not like, while they were more likely to consider an unpleasant dream more meaningful if it was about a person they disliked.

"In other words, people attribute meaning to dreams when it corresponds with their pre-existing beliefs and desires," Morewedge said. "This was also the case in another experiment which demonstrated that people who believe in God were likely to consider any dream in which God spoke to them to be meaningful; agnostics, however, considered dreams in which God spoke to be more meaningful when God commanded them to take a pleasant vacation than when God commanded them to engage in self-sacrifice."

More research is needed to explore fully how people interpret their dreams, and in what cases dreams may actually reveal hidden information, Morewedge said.

"Most people understand that dreams are unlikely to predict the future but that doesn't prevent them from finding meaning in their dreams, whether their contents are mundane or bizarre," he said.

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Darwin the Buddhist? Empathy Writings Reveal Parallels

Christine Dell'Amore in Chicago
National Geographic News

Charles Darwin probably didn't know it, but he held views on human empathy that mirror Buddhist beliefs, says a pioneer in decoding facial expressions. Based on his interactions with foreign cultures, Darwin came to define empathy as a desire to end someone's suffering to assuage one's own discomfort.

Buddhist teachings also see empathy as a somewhat selfish motivation, but one that the Dalai Lama, the spiritual leader of Tibet, calls the "seed of compassion."

"It's an amazing coincidence that [Darwin's] views on compassion and morality are identical to the Tibetan Buddhist view," said Paul Ekman, a psychologist whose work decoding so-called micro-expressions is the basis for the new Fox television show Lie to Me.

Indeed, after reading Darwin's work on emotions, the Dalai Lama told Ekman he "would consider himself a Darwinian."

The parallel inspired Ekman to study the little-understood trait of compassion, which he discussed this weekend in Chicago at the annual meeting of the American Association for the Advancement of Science.

Though everyone is capable of compassion, Ekman said, some people seem to manifest it without effort.

(A related study revealed how bullies seem to experience pleasure when they see others suffer.)

Until psychologists figure out why the disparity exists, he said, "the survival of our planet" depends on cultivating compassion.

Universal Trait

Darwin became fascinated with the expression of emotions during his five-year voyage on the H.M.S. Beagle in the 1830s.

The British naturalist couldn't understand the words or gestures of the people he met, but he had no trouble interpreting their facial expressions.

In his lesser known 1872 book The Expression of Emotions in Man and Animals, Darwin proposed that empathy is a universal trait. "He saw this book as an important contribution showing the commonality of all people," Ekman said. (Read more about Darwin's scientific legacy.)

It's also possible that Darwin encountered Buddhist teachings through letters from other scholars of the time, he added.

Over the past few years, Ekman examined Darwin's book along with Buddhist teachings and divided compassion into three types: simple, global, and heroic.

Simple compassion is the almost instinctual form that exists mostly between a mother and an infant.

Global compassion appears when people help distant strangers, such as the outpouring of international aid after the 2004 Indian Ocean tsunami.

And heroic compassion occurs when a person is motivated into epic acts of bravery, for instance, jumping into an icy pond to save someone else's life.

In a recent book co-authored with the Dalai Lama, Ekman suggests creating "compassion gyms" that could test a person's level of compassion and even offer exercises to prompt deeper caring for others.

The Dalai Lama, meanwhile, believes that just the sight of unbearable suffering is enough to inspire compassion.

Animal Emotions

Darwin also argued fervently in his 1872 book that animals and humans share the capacity for emotion, an idea that has been borne out by later research, Ekman noted.

(See photos showing how a dying elephant seems to elicit compassion from its herd.)

Many great ape studies, for example, show that the animals can place themselves into another's shoes, so to speak. This sensitivity comes from being self-aware, Barbara King, an anthropologist at the College of William and Mary in Virginia, told National Geographic News.

"We wouldn't be human in the ways we are human today if apes were not deeply emotional creatures and deeply social ones," King said. "We are … products of our past."

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Researchers crack the code of the common cold

Scientists have begun to solve some of the mysteries of the common cold by putting together the pieces of the genetic codes for all the known strains of the human rhinovirus. Researchers at the University of Maryland School of Medicine in Baltimore and colleagues at the University of Wisconsin-Madison have completed the genomic sequences of the viruses and assembled them into a "family tree," which shows how the viruses are related, with their commonalities and differences. The study will be released on the online version of the journal Science (Science Express) at 2 p.m. EST on February 12.

The researchers say this work provides a powerful tool that may lead to the development of the first effective treatments against the common cold.

"There has been no success in developing effective drugs to cure the common cold, which we believe is due to incomplete information about the genetic composition of all these strains," says the study's senior author, Stephen B. Liggett, M.D., professor of medicine and physiology at the University of Maryland School of Medicine and director of its Cardiopulmonary Genomics Program.

"We generally think of colds as a nuisance, but they can be debilitating in the very young and in older individuals, and can trigger asthma attacks at any age. Also, recent studies indicate that early rhinovirus infection in children can program their immune system to develop asthma by adolescence," says Dr. Liggett, who is a pulmonologist and molecular geneticist.

Major discoveries of the study

The researchers found that human rhinoviruses are organized into about 15 small groups that come from distant ancestors. The discovery of these multiple groups explains why a "one drug fits all" approach for anti-viral agents does not work. But, says Dr. Liggett, "Perhaps several anti-viral drugs could be developed, targeted to specific genetic regions of certain groups. The choice of which drug to prescribe would be based on the genetic characteristics of a patient's rhinovirus infection."

Dr. Liggett adds that while anti-viral drugs seem to be the most likely to succeed, "the data gathered from these full genome sequences gives us an opportunity to reconsider vaccines as a possibility, particularly as we gather multiple-patient samples and sequence the entire genomes, to see how frequently they mutate during a cold season. That work is underway now."

The researchers also found that the human rhinovirus skips a step when it makes its protein product, a shortcut that probably speeds up its ability to make a person feel sick soon after infection. "This is a new insight," says co-investigator Claire M. Fraser-Liggett, Ph.D., director of the Institute for Genome Sciences and professor of medicine and microbiology at the University of Maryland School of Medicine. "We would not have had any sort of intuition about this had it not been revealed through genome analysis. Information that comes from this discovery might present a completely different approach in terms of therapy."

The analysis shows that some human rhinoviruses result from the exchange of genetic material between two separate strains of the virus that infect the same person. Such a swap, known as recombination, was previously not thought possible in human rhinovirus. During cold season, when many different strains of rhinovirus may be causing infections, recombination could rapidly produce new strains.

Multiple mutations (as many as 800) were evident in virus samples taken recently from patients with colds, compared to older rhinovirus reference strains. Some viruses mutate by making slight changes in certain proteins to avoid being destroyed by antibodies from a person's immune system. "Mutations were found in every area of the genome," says Dr. Liggett.

The study's lead author, Ann C. Palmenberg, Ph.D., professor of biochemistry and chair of the Institute for Molecular Virology at the University of Wisconsin-Madison, notes, "As we begin to accumulate additional samples from a large number of patients, it is likely that hotspots for mutation or recombination will become apparent, and other regions resistant to mutational change may emerge. This will provide clues as to how flexible the virus is as it responds to the human environment, important hints if you are designing new therapeutics."

Study background

Human rhinovirus infection is responsible for half of all asthma attacks and is a factor in bronchitis, sinusitis, middle ear infections and pneumonia. The coughs, sneezes and sniffles of colds impose a major health care burden in the United States—including visits to health care providers, cost of over-the-counter drugs for symptom relief, often-inappropriate antibiotic prescriptions and missed work days—with direct and indirect costs of about $60 billion annually.

Prior to the start of this project, the genomes of only a few dozen rhinoviruses had been sequenced from what was considered the reference library, a frozen collection of 99 different rhinovirus strains taken from patients over a span of more than two decades. During this team's work, several other groups began to report the full genomes of some of these viruses, as well as some odd rhinovirus-like strains from relatively sick patients.

"It was clear to us that the spectrum of rhinoviruses out there was probably much greater than we realized. Further, we needed to develop a framework from which we could begin to figure out ways to combat these viruses and use their genetic signatures to predict how a specific virus would affect a patient," says Dr. Fraser-Liggett.

The current study adds 80 new full genome sequences to the rhinovirus library and 10 more acquired recently from people with colds. Each sequence was modeled and compared to each other. Dr. Liggett says, "Now we can put together many pieces of the human rhinovirus puzzle to help us answer some fundamental questions: how these rhinoviruses might mutate as they spread from one person to another; which rhinoviruses are more associated with asthma exacerbations and why rhinovirus exposure in infancy may cause asthma later in life. With all this information at hand, we see strong potential for the development of the long-sought cure for the common cold, using modern genomic and molecular techniques."

"With recent improvements in technology, including next-generation DNA sequencing tools, it has become easier to generate whole genome sequence information," says Dr. Fraser-Liggett. "There is no reason any longer to focus on a very limited part of the rhinovirus molecule to learn what it's doing, what the predominant strain is in a population, or to try to infer what the evolution of the entire molecule might be. Instead, by studying the complete genome sequence, we can answer multiple questions in parallel."

Can geo-engineering rebuild the planet?

In the 1960s, two Russian scientists set out ambitious plans to reshape the world around us: to reverse the flow of rivers, shoot tiny white particles into space to illuminate the night sky, and melt the Arctic to water fields of Soviet wheat. "If we want to improve our planet and make it more suitable for life," wrote NP Rusin and L Flit, "we must alter its climate."

Four decades later, we have done plenty to alter the climate, but not for the better. And as we grapple with the problems of global warming, the standard prescription – cutting greenhouse gas emissions – is proving problematic. "I cannot see that we will be able to keep carbon levels low enough to prevent catastrophe," says Professor Brian Launder, of the University of Manchester. "Over the past five years, emissions have gone up, not down."

Which means that "geo-engineering" – using technology on an almost unimaginable scale to tinker with the environment and correct our mistakes – could move from fantasy to necessity. Professor James Lovelock, who came up with the "Gaia" hypothesis, in which the Earth is thought to behave rather like a living, self-regulating organism, thinks we have exceeded the planet's natural capacity to counteract the changes we have made, and are rapidly heading towards a situation that will be calamitous for our species.

"Whatever we do is likely to lead to death on a scale that makes all previous wars, famines and disasters small," he says. "To continue business as usual will probably kill most of us during the century."

Even those of a less alarmist bent are worried enough to be taking geo-engineering seriously. Last September, Prof Launder co-edited a special edition of a Royal Society journal which examined various proposals, such as injecting sulphur into the stratosphere to reflect sunlight back into space.

Most of the schemes suggested, there and elsewhere, involve dramatic alterations to the Earth's weather systems, whether by deflecting the Sun's rays, removing carbon from the atmosphere or cooling the oceans. Prof Lovelock has come up with one of the most ambitious: he and Professor Chris Rapley, from the Science Museum, would like a system of pipes to be held vertically below the ocean's surface. These tubes, each 100 metres long, would draw cold water from below; wave action would then mix four tons of cooler water per second into the ocean at the surface. Cooler oceans mean a cooler planet, while the nutrient-rich water brought up from the bottom could encourage algal blooms, which use carbon to grow and thereby remove it from the atmosphere.

Supporters of another approach, known as Oceanic Iron Fertilisation, believe that promoting the growth of algae should be our main objective, rather than just a side effect. According to Dr Victor Smetacek, of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, the theory is that adding iron to the oceans will encourage algal blooms. When the algae die, they sink to the bottom of the ocean, locking away their cargo of carbon.

There are plans to test this proposal off the island of South Georgia in the Atlantic. At the very least, Dr Smetacek hopes that large blooms of algae will act as food for krill, helping resurrect declining populations of squid and even some whales.

A third oceanic idea has been suggested by Professor Stephen Salter, from Edinburgh University's School of Engineering: a wind-driven fleet of Flettner ships. Originally designed by German engineer Anton Flettner, these vessels have no sails and are powered by rotors; the first one sailed across the Atlantic in 1926.

The ships would drag propeller-like turbines behind them to generate electricity, and pump out a very fine spray of seawater into the air. These tiny drops would join low clouds, with the salt making them whiter and better at reflecting sunlight back into the atmosphere, thus cooling the oceans. The beauty of this system is that it uses natural materials – seawater – and is powered by a renewable source of energy.

Finally, instead of reflecting sunlight using sea-level contraptions, some scientists have suggested shading the Earth from space. The most recent idea was put forward by Dr Roger Angel at the University of Arizona: to launch into space trillions of thin transparent discs, each about 60cm across. This cloud of 100,000 lenses would reflect sunlight back into space, shielding us from 1.8 per cent of the Sun's radiation.

But as intoxicating as such ideas are – and as tempting as a "quick fix" to the climate would be – they are not the finished article. Not only would the costs be enormous, but in a recent paper in Atmospheric Chemistry and Physics Discussions, Dr Tim Lenton of the University of East Anglia compared the possible effectiveness of 17 different geo-engineering techniques, and found severe problems with many of them. The Lovelock/Rapley plan to cool the oceans would, he says, be ineffective at reducing carbon on a global scale, and he is similarly sceptical about the algal blooms.

"There's huge disagreement in the scientific community about ocean fertilisation," agrees Prof Launder. "The ocean is very complex – elsewhere, perhaps thousands of miles away, you might be causing an adverse effect." Scientists from Britain's National Oceanography Centre, writing in the journal Nature, have demonstrated that adding iron to the ocean does boost algae growth rates by up to three times, and lock away carbon on the sea floor. But they added that geo-engineers overestimated the amount of carbon removed by between 15 and 50 times.

Prof Salter's Flettner ships have also sailed into stormy waters. Dr Lenton has calculated that they could cope with half the projected carbon emissions during the coming century, but Professor Stephen Schneider, from Stanford University, says that oceanic currents and winds might distribute the cooling effect unevenly, resulting in even greater climatic change.

As for Dr Angel's sun shield, Dr Lenton believes it would do the most to compensate for carbon emissions – but there is a downside, in that the sunshades would need to be launched in stacks of 800,000 units every five minutes for 10 years. "They might well work," says Prof Launder, "but this system wouldn't be ready soon enough."

So instead of alleviating global warming by trying to cool the planet or creating giant algal blooms, why not simply remove the carbon? Trees are pretty good at doing this naturally – but according to Prof Lovelock, we do not have enough forested regions left and could not plant enough trees to save us.

Instead, Dr Klaus Lackner, of Columbia University in New York, has come up with the idea of an artificial tree that directly "scrubs" carbon from the sky. Each one would be around the size of a shipping container and would, he estimates, be able to capture a ton of carbon dioxide a day. Of course, the carbon dioxide still has to be disposed of; Dr Lackner suggests pumping it into greenhouses to be absorbed by crop plants.

"In a way, this sort of scheme is the most desirable," says Prof Launder, "because it doesn't just reflect sunlight, it grabs carbon dioxide in the atmosphere. Sadly, I don't think these 'trees' can sequester anything like the amount of carbon required."

The grim conclusion is that while some of these schemes have potential, there is no magic answer. "Geo-engineering is not a solution," says Prof Launder, "but it could give the world a chance to come to its senses. In 50 years we'll have carbon-free energy schemes in place, but we need a solution that can be put into place shortly, and will gain us breathing space."

Yet even if any of these schemes could be made to work, a global scheme requires global co-operation. Given how hard that has proved over the financial crisis, it is difficult to imagine world leaders reaching an agreement over a radical – and expensive – alteration to the environment.

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Earth facing critical climate decline

(UPI) -- A U.S. scientist says Earth's atmospheric greenhouse gases are increasing more rapidly than expected, resulting in worsening global warming predictions.

Chris Field, a member of the Nobel Prize-winning Intergovernmental Panel on Climate Change, says decisive action is needed to prevent the planet's climate system from crossing a critical threshold by the end of the century.

Field, director of the Carnegie Institution's Department of Global Ecology, said studies indicate greenhouse warming could trigger a vicious cycle in which carbon dioxide released from thawing tundra and increasingly fire-prone forests drives global temperatures even higher.

"The data now show that greenhouse gas emissions are accelerating much faster than we thought," said Field, with new studies also revealing potentially dangerous feedbacks in the climate system that could convert current carbon sinks into carbon sources.

"One thing that seems to be certain, however, is that as a society we are facing a climate crisis that is larger and harder to deal with than any of us thought," Field said. "The sooner we take decisive action, the better our chances are of leaving a sustainable world to future generations."

The research was presented this week in Chicago during the annual meeting of the American Association for the Advancement of Science.

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