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Thursday, September 18, 2008

Scientists study 'out of body experiences'

People who report seeing bright lights or tunnels as they leave their bodies in near-death experiences are having their claims treated seriously in a hospital study.

By Jessica Salter


Sceintists will see if consciousness continues after brain death Photo: Justin Sutcliffe

Doctors in hospitals in Britain and the US will study 1,500 heart attack patients to see if people with no heartbeat or brain activity can have "out of body" experiences.

Some people report being able to soar out of their bodies and look down on themselves and medical staff.

The study at 25 UK and US hospitals will include doctors placing images on shelves that are only visible from the ceiling to test the theory.

Dr Sam Parnia, an intensive care doctor who is heading the study, said: "If you can demonstrate that consciousness continues after the brain switches off, it allows for the possibility that the consciousness is a separate entity.

"It is unlikely that we will find many cases where this happens, but we have to be open-minded.

"And if no one sees the pictures, it shows these experiences are illusions or false memories.

"This is a mystery that we can now subject to scientific study."

Dr Parnia said that after a cardiac arrest, where the body is technically dead, doctors restart the heart and reverse the dying process.

He said: "What people experience during this period of cardiac arrest provides a unique window of understanding into what we are all likely to experience during the dying process."

Hospitals involved include Addenbrookes in Cambridge, University Hospital in Birmingham and the Morriston in Swansea, as well as nine hospitals in the US.

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Atom-smasher hit by electrical hitch

The worlds largest superconducting solenoid magnet part of the experiment in smashing atoms September 10. The worlds largest particle collider has been stopped a week after its startup as a result of an electrical fault the European Organisation for  ...
The world's largest superconducting solenoid magnet, part of the experiment in smashing atoms, September 10. The world's largest particle collider has been stopped, a week after its startup, as a result of an electrical fault, the European Organisation for Nuclear Research (CERN) said.

The world's largest particle collider was stopped on Wednesday, a week after its startup, as a result of an electrical fault, the European Organisation for Nuclear Research (CERN) said on Thursday.

The problem affected a cooling system for high-powered magnets designed to steer beams of particles around the Large Hadron Collider's 27-kilometre (16.9-mile) circular tunnel, CERN said.

The LHC "is still in commissioning phase, it's a very complex tool and it's normal for there to be stoppages," a CERN spokeswoman told AFP.

Commissioning work stopped on Wednesday, but was likely to resume later Thursday, she said.

The LHC took nearly 20 years to complete and at six billion Swiss francs (3.76 billion euros, 5.46 billion dollars) is one of the costliest and most complex scientific experiments ever attempted.

It aims to resolve some of the greatest questions surrounding fundamental matter, such as how particles acquire mass and how they were forged in the "Big Bang" that created the Universe some 13.7 billion years ago.

Counter-rotating beams, comprising strings of protons, are whizzed around the tunnel and then are smashed together in four huge laboratories.

Arrays of detectors swathing the walls of these chambers will trace the sub-atomic rubble spewed out from the collision, looking for signatures of novel particles.

The September 10 switch-on saw the testing of a clockwise beam, and then an anticlockwise beam. The first collisions are not expected for a number of weeks, given the long process of testing the LHC's equipment.

The steering magnets in the LHC tunnel are chilled to as low as -271 degrees Celsius (-456.25 degrees Fahrenheit), which is close to absolute zero and colder than deep outer space.

At this extreme temperature, electrical currents overcome resistance, thus making it easier and cheaper to power electro-magnets.

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Oil Palm Plantations Are No Substitute For Tropical Rainforests, New Study Shows

The continued expansion of oil palm plantations will worsen the dual environmental crises of climate change and biodiversity loss, unless rainforests are better protected, warn scientists in the most comprehensive review of the subject to date.

Lead author, Emily Fitzherbert from the Zoological Society of London and University of East Anglia said: "There has been much debate over the role of palm oil production in tropical deforestation and its impacts on biodiversity. We wanted to put the discussion on a firm scientific footing."

Palm oil, used in food, cosmetics, biofuels and other products, is now the world's leading vegetable oil. It is derived from the fruit of the oil palm, grown on more than 50,000-square miles of moist, tropical lowland areas, mostly in Malaysia and Indonesia. These areas, once covered in tropical rainforest, the globe's richest wildlife habitat on land, are also home to some of the most threatened species on earth.

The review, published September 15 in the journal Trends in Ecology and Evolution, singles out deforestation associated with plantation development as by far the biggest ecological impact, but finds that the links between the two are often much more complex than portrayed in the popular press.

Co-author Matt Struebig, from Queen Mary, University of London, explains: "Most land-cover statistics do not allow us to distinguish where oil palm has actually driven forest clearance. Oil palm certainly has directly replaced tropical forest in some areas, but oil palm companies also often have close links with timber or paper pulp companies, giving additional motives for deforestation."

Within countries, oil palm is usually grown in a few productive areas, but it looks set to spread further. Demand is increasing rapidly and 'its potential as a future agent of deforestation is enormous', the study says.

Most of the suitable land left is within the last remaining large areas of tropical rainforest in Central Africa, Latin America and Southeast Asia. Where oil palm has replaced tropical forest the impact on wildlife depends on what species survive in the new oil palm habitat.

The study confirmed that oil palm is a poor substitute habitat for the majority of tropical forest species, particularly forest specialists and those of conservation concern.

Emily Fitzherbert continues: "By compiling scientific studies of birds, bats, ants and other species, we were able to show that on average, fewer than one-sixth of the species recorded in primary forest were found in oil palm. Degraded forest, and even alternative crops such as rubber and cocoa, supported higher numbers of species than oil palm plantations."

Even this estimate is likely to be optimistic, because forest habitats are more difficult to survey and some species inhabit plantations briefly before going extinct.

There is little potential to help wildlife within plantations, so ensuring that new plantations do not replace forest and protecting what is left of native forest in and around plantations are the only real options for protecting the majority of species, the researchers say.

International policies demanding evidence of environmental responsibility, in particular that land of high conservation value is not converted to oil palm, can help.

"There is enough non-forested land suitable for plantation development to allow large increases in production without further deforestation," said co-author Ben Phalan, from the University of Cambridge.

However, in identifying these areas, there needs to be a careful distinction between degraded land that is of low conservation value, such as imperata grasslands, and partially logged or degraded forest areas which can still harbour relatively high levels of biodiversity and bring greater wildlife and carbon storage benefits if restored.

"Unless governments in producer countries show stronger leadership in controlling logging, protecting forests and ensuring that crops are planted only in appropriate areas, the impacts of oil palm expansion on biodiversity will be substantial," adds Phalan.

This study is released as pressure mounts on UK and EU officials to rethink targets for biofuel sales. The UK's Renewable Fuels Agency revealed that more than 80 per cent of UK biofuels were not meeting even very basic environmental standards and has urged the UK government to slow the introduction of biofuels until more is known about their negative impacts.

While increases in biofuel use will almost certainly add to pressure on tropical forests, the study highlights how those pressures might be reduced.

A recent initiative, the Roundtable on Sustainable Palm Oil, has encouraged 40 per cent of the palm oil industry to commit to saving wildlife on and around plantations. The scientists hope that the Roundtable will continue to attract many of the remaining 60 per cent.

In Indonesia, local organisations are using satellite technology and the internet to investigate illegal forest clearance by oil palm companies and to put public pressure on them to improve.

These initiatives will help, but the study warns that unless they are scaled up and better supported by stronger government action against deforestation, damage to rainforests and their unique wildlife will continue.

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Large Hadron Collider: First subatomic particle collision to happen next week

By Roger Highfield, Science Editor

The first collisions between subatomic particles will take place in the Large Hadron Collider next week, which will mark another milestone for the biggest experiment in history.

"If we get stable conditions, I am very optimistic things will go quite fast," says Dr Lyn Evans, the coal miner's son from Aberdare, South Wales, who is leader of the £4.4 billion particle accelerator, a project that involves around 10,000 scientists and engineers worldwide.

One of the first images taken with CMS, one of the detectors, after a beam of particles was smashed into a tungsten block
One of the first images taken with CMS, one of the detectors, after a beam of particles was smashed into a tungsten block

The LHC circulates particles in a 17 mile circumference underground tunnel straddling the French-Swiss border at The European Organization for Nuclear Research, near Geneva, Switzerland, known by the acronym Cern.

Although there was much ballyhoo last week about the first particles - protons - to whirl around the LHC at a shade under the speed of light, the real aim of the exercise is to bring counter rotating beams of particles into collision in the four "eyes" - detectors - of the machine to recreate conditions not seen since just after the birth of the universe.

This is the aspect of the experiment that has triggered all the angst and hand-wringing by doomsayers and Jeremiahs who fear that the collisions will mark the end of the world, as it tumbles into the gaping maw of a black hole.

These fears have been dismissed as nonsense by Dr Evans, along with scientists such as Prof Stephen Hawking, who say that the end of the world is not nigh.

The original plan was to take 31 days from the first proton beams circulating in the LHC to smashing protons for the first time.

"We were going along at a real good lick," Dr Evans said of the days after particles first circulated.

But the cryogenics that keep the great machine cool - it is the biggest fridge on the planet - went down on Friday, as a result of thunderstorms disrupting the power supply.

"We have had problems with the electricity supply for various reasons and the cryogenics is recovering from that, so we will not have a beam again, probably until Thursday morning," says Dr Evans.

The team now hopes to achieve collisions at between one fifth and one tenth of the full energy in a few days.

"We are very confident that we can go quite quickly. The experiments have asked us for some early collisions, at low energy. If we get stable conditions, we will get there next week."

The collisions will take place in the two general purpose detectors of the giant machine, called Atlas and CMS, though Dr Evans adds the team will also attempt collisions in Alice, which will study a "liquid" form of matter, called a quark-gluon plasma, that formed shortly after the Big Bang, and an experiment called LHCb, which will investigate the fate of antimatter in the wake of the Big Bang.

Dr Lyn Evans in the control room of the Large Hadron Collider
Dr Lyn Evans in the control room of the Large Hadron Collider

"The main objective is to get to 5TeV" (that target energy per beam is equivalent to 10Tev collisions, while the LHC is designed to reach 14 TeV working full steam), said Dr Evans.

He says "I don't know how long that will take," though the schedule predicts that 14 TeV will be reached next year.

"We would not go to very high energy next, week, we are not that clever," said "Evans the Atom".

The LHC will be able to create fundamental particles that are too heavy to have been produced using existing particle colliders.

One of these could be the Higgs boson, named after the Edinburgh based physicist, which the LHC was built to find using the Atlas and the CMS detectors.

If discovered, the Higgs - jokingly called the "god particle" - would complete the Standard Model of particle physics by explaining how particles get their different masses.

The great machine may also catch a glimpse of a "supersymmetric" world, where a new myriad of heavy particles mirror those of the Standard Model, which may be responsible for a mysterious gravity source, called dark matter.

Although based on much more speculative theories, the LHC may even find exotic entities such as mini black holes or evidence for additional dimensions.

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12 Year Old Boy Invents New Type of Solar Cell

Why Do We Believe Impossible Things?

OPINION By LEE DYE

Why do so many people hold beliefs that are clearly false? A recent story on ABCNews.com said 80 million Americans believe we have been visited by aliens from another planet, and numerous studies show that millions of people believe in ghosts, extrasensory perception and, of course, alien abductions.

caveman fire
Why do so many people hold beliefs that are clearly false? A recent story on this site said 80... Expand
(The Bridgeman Art Library/Getty Images)

According to biologist Lewis Wolpert of University College, London, all those beliefs are clearly false, and they all share a common beginning. It may well have started when the first human realized he, or she, could make a fire by rubbing two sticks together.

Wolpert is the author of a new provocative book exploring the evolutionary origins of belief, called "Six Impossible Things Before Breakfast." The title comes from Lewis Carroll's classic "Through the Looking Glass," when Alice tells the White Queen that she cannot believe in impossible things.

"I dare say you haven't had much practice," the Queen replied. "When I was your age, I always did it for half-an-hour a day. Why, sometimes I've believed as many as six impossible things before breakfast."

Wolpert argues that our wide range of beliefs, some of which are clearly false, grew out of a uniquely human trait. Alone in the animal world, humans understand cause and effect, and that, he says, led ultimately to the invention of tools, the rapid rise of sophisticated technology, and of course, beliefs. Even the earliest humans understood that many events that shaped their lives resulted from specific causes. Therefore, there must be a cause behind every event.

Searching for that cause, Wolpert says, led to the rise of religion because surely there must be some purpose behind all this, some ultimate cause at work in the universe.

Wolpert is an atheist, but he says he isn't trying to convert anyone to atheism. If so, he may be the only person on the planet who is willing to share his deeply held beliefs without caring whether he can convince anyone to believe the same way. But his basic premise is sound. We all know other people, not ourselves of course, who hold some beliefs that are absurd, or at least grossly lacking in evidence. Why?

It all goes back to that first character who rubbed two sticks together.

No other animal has the mental framework for understanding cause and effect, Wolpert says. Chimps, apes and those famously clever New Caledonia crows come close, but they aren't there yet. Once humans reached that point, they turned a corner that ultimately shaped what we are today.

Some animals have used various things as tools, but only humans have put at least two different materials together to fabricate a tool for a specific purpose, and then go on to discover other uses for that same tool. Those first discoveries gave humans an edge on the competition, allowing the species to thrive.

But along the way things happened, some good and some bad. The effort to understand why bad things happen to good people, and so on, gave rise to what Wolpert and others call the "belief engine" in the brain. We want to believe there is a reason for it all, and that leaves us predisposed to believe in some things for which there is little or no evidence. If a certain belief makes sense out of an otherwise senseless event, then it must be true, right?

Wolpert argues that even false beliefs can serve a useful purpose. He concedes that religion, which he regards as false, has a purpose and has played a role in the evolutionary processes. People tend to look out for people of like faith, as in churches, and that support can make them stronger, thus improving the chances that they will live long enough to see their genes passed along.

If Wolpert's compelling argument is right, does that mean we have no control over what we believe? He says he was a very religious child, but became an atheist at the age of 16 because he no longer believed in religion. But could it be that his own "belief engine" made the decision for him?

Ever since Sigmund Freud dug into the secrets of the subconscious, many psychologists have argued that many of our beliefs are beyond our control because they are shaped by unknown secrets buried inside the brain. But if that's true, how do psychologists escape their own scenario? Wouldn't they be just as likely to be deluded as the rest of us?

Similarly, many biologists think the complex organism between our ears is driven entirely by biology. But if we all have a biologically based "belief system," aren't we all -- even biologists -- victims of false beliefs? As Wolpert concedes, maybe people just believe what they want to believe.

None of us approach complex issues, like whether or not to believe in a specific religion, or even a political candidate, with a clean slate.

How else can you explain 80 million Americans who believe we've been visited by aliens? Surely, if aliens invested the enormous costs of interstellar travel and came our way, they must have had a reason. Wouldn't they drop by the White House instead of a desert in New Mexico or Texas? Would there really be any confusion if they had, indeed, visited Earth?

The late astronomer Carl Sagan had a wonderful formula for measuring the truthfulness of any belief. Extraordinary claims, he said, demand extraordinary evidence.

The fact that so many are willing to believe so many impossible things with so little evidence is not comforting.

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Crows make monkeys out of chimps in mental test

Emma Young


Corvus moneduloides (Image: Pawel Ryszawa/Wikimedia Commons)" title="A New Caledonian crow, Corvus moneduloides (Image: Pawel Ryszawa/Wikimedia Commons)" class="centered block">
A New Caledonian crow, Corvus moneduloides (Image: Pawel Ryszawa/Wikimedia Commons)

Crows seem to be able to use causal reasoning to solve a problem, a feat previously undocumented in any other non-human animal, including chimps.

Alex Taylor at the University of Auckland, New Zealand, and his team presented six New Caledonian crows with a series of "trap-tube" tests.

A choice morsel of food was placed in a horizontal Perspex tube, which also featured two round holes in the underside, with Perspex traps below.

For most of the tests, one of the holes was sealed, so the food could be dragged across it with a stick and out of the tube to be eaten. The other hole was left open, trapping the food if the crows moved it the wrong way.

Three of the crows solved the task consistently, even after the team modified the appearance of the equipment. This suggested that these crows weren't using arbitrary features – such as the colour of the rim of a hole – to guide their behaviour. Instead they seemed to understand that if they dragged food across a hole, they would lose it.

Not-so great apes

To investigate further, the team presented the crows with a wooden table, divided into two compartments. A treat was at the end of each compartment, but in one, it was positioned behind a rectangular trap hole. To get the snack, the crow had to consistently choose to retrieve food from the compartment without the hole.

A recent study of great apes found they could not transfer success at the trap-tube to success at the trap-table. The three crows could, however.

"They seem to have some kind of concept of a hole that isn't tied to purely visual features, and they can use this concept to figure out the novel problem," Taylor says. "This is the most conclusive evidence to date for causal reasoning in an animal."

Three of the crows did fail at both tasks, however. The team plans further work to investigate why.

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Why Loud Music in Bars Increases Alcohol Consumption


When the music goes up, the beers go down.
At some point during the evening, in bars across the land, two things happens: the lights go down and the music goes up.

Lowering the lights signals the real beginning of night-time fun: with dimmed lights and alcohol beginning to work its magic the business of loosening up after the day's exertions can truly begin.

But turning the music up so loud that people are forced to shout at each other doesn't have quite the same beneficial effect on social interactions. Because everyone is shouting, the bar becomes even noisier and soon people start to give up trying to communicate and focus on their drinking, meaning more trips to the bar, and more regrets in the morning.

Of course this is exactly what bar owners are hoping for. People sitting around quietly nursing their drinks for hours are no good for profits. Talkers aren't the best drinkers. At least that is the received wisdom in the industry. And this received wisdom turns out to be accurate according to field studies conducted in French bars by Professor Nicolas Guegen and colleagues.

Drink up

One study by Gueguen et al. (2004) (PDF) found that higher sound levels lead to people drinking more. In a new study published in Alcoholism: Clinical & Experimental Research, Gueguen et al. (2008) visited a bar in the west of France to confirm their previous finding in a naturalistic setting. Here, they observed customers' drinking habits across three Saturday nights, in two different bars in the city.

Bar

The level of the music was randomly manipulated to create the conditions of a true experiment. It was either at its usual volume of 72dB or turned up to 88dB. For comparison: 72db is like the sound of traffic on a busy street while 88db is like standing next to a lawnmower.

Sure enough when the music went up the beers went down, faster. On average bar-goers took 14.5 minutes to finish a 250ml (8 oz) glass of draught beer when the music was at its normal level. But this came down to just 11.5 minutes when the music was turned up. As a result, on average, during their time in the bar each participant ordered one more drink in the loud music condition than in the normal music condition.

The observers even measured the number of gulps taken to finish each drink - the level of the music was found to have no effect on this. So the faster drinking was as a result of more gulps rather than bigger gulps.

Drinking instead of talking?

Since the volume of the music was randomly manipulated this experiment suggests that louder music causes more drinking, but what it doesn't tell us is why. Some think that people drink instead of talking while others have argued that they drink more because the music creates greater levels of arousal, which then leads to more drinking.

Evidence from a study carried out in pubs in Glasgow, Scotland by Forsyth and Cloonan (2008) does back up the idea that people do, at least partly, drink because they can't talk to each other. Perhaps further studies comparing lone drinkers with dyads and bigger groups would confirm or disprove this idea.

Whatever the real reason, or combination of reasons, this kind of study is very persuasive about the causal connection between louder music and more drinking because the experimenters have taken the time to go to a bar, set up the random experimental manipulation and then actually observe people to see what they do in a real live environment.

On top of that, from the point of the view of the participant, I think it would definitely enhance your night-out to find out that you'd been inadvertently furthering psychological science by sinking a few cold ones. Or is that just the researcher (or beer-drinker) in me coming out?


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Toronto May Ban the Coffee Cup

Published by Benjamin Jones

Welcome to EcoRenovator! If you like the site and want to get automatic updates, check out the RSS feed. Thanks for visiting!

Image: Toronto Star

Toronto has an ambitious plan to reduce waste to landfill by 70% by 2010. This means that consumption of one-time use containers will have to decrease dramatically. As you can see in the above picture from the Star, trash on city streets is made up of plastic bags, coffee cups, and fast food containers. Just imagine what would happen to New York City’s trash volume if Starbucks forced all their patrons to bring their own cups!

According to the Toronto Star, the city is considering three options:

An outright ban.

A levy or tax on the items. (Charging extra would presumably influence consumers to use recyclable cups or containers.)

A deposit-return program similar to the provincial bottle return program, whereby consumers get at least a portion of their money back if they turn in the container, making the seller responsible for recycling it.

Toronto’s ambitous plans are spurred by a landfill that’s nearing capacity and the desire to avoid incineration, which can release toxic gases and large amounts of global warming gases. But will their initiative work?

Reducing waste to landfill through legislation

Let’s take a look at the three options presented by the Toronto government, as well as their possible pros and cons:

  1. Ban: Considering that the ban would take place on a business level, I think it would be very successful. All one would need to do is pop into any coffee shop and see if they’re handing out disposable cups, then slap a big fine on the company. Since this ban eliminates consumer choice, there are actually very few points of mediation between the government and potential offenders (limited to business owners). However, jumping from no regulation to ban at breakneck speed leaves little room for consumers or businesses to change their habits, and will likely lead to ill will and resistance, even amongst those who agree with the cause in principle.
  2. Tax: I think taxes are the best solution here. No one likes taxes, and they may not affect the type of person who goes into a coffee shop for a $4 mocha latte, but that fact is that taxes get things done. Would you bring your favorite coffee mug to get coffee on the way to work if it meant saving a dollar a week? I would. And for all those people who don’t want to conserve and would rather pay the tax, that money can go to recycling or waste management programs to otherwise deal with the problems caused by disposable food containers.
  3. Deposit: Deposits sound nice in principle, but when was the last time anyone ever turned in a can for deposit? There is a program in my state, but I’m too lazy to do it, so I just put my recycling out and expect nothing in return. Plus, because most of the waste in question here is food waste, the return system would have to be handled within the place of business, which would not only inconvenience people grabbing food and leaving, but the businesses that now have to collect and store trash in a new way, as well as issue deposit refunds. I actually think this would be more burdensome than an outright ban, and would eventually fail insofar as it would not affect any real change.

How would you handle Toronto’s current trash problem?

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Bill Gates invests in algae fuel

Posted by Martin LaMonica

Bill Gates' investment firm is funding Sapphire Energy, a company that intends to make auto fuel from algae.

Sapphire Energy said Wednesday that a series B round will bring the total amount it has raised to more than $100 million. Investors include Gates' investment firm Cascade Investment, as well as Arch Venture Partners, Wellcome Trust, and Venrock.

Green crude gasoline from algae

The lowly algae is the renewable fuel industry's great green hope. Because algae is rich in oil and can grow in a wide range of conditions, many companies are betting that it can create fuels or other chemicals cheaper than existing feedstocks.

So far, no company has made cost-competitive fuel at large scale from algae. But a handful predict they will within three years.

San Diego-based Sapphire Energy said last year that it has successfully made its product, Green Crude, which yielded 91 octane gasoline from algae.

Its process can use algae to yield a range of fuels, including the chemical equivalents of gasoline, jet fuel, and diesel. It has a test facility in New Mexico.

The series B equity will help the company build out its operations with a target of producing 10,000 barrels per day of fuel from algae and help it operate at commercial scale within three to five years.

Sapphire Energy has not provided many details publicly about its technology except to say that it doesn't need fresh water to grow the algae and that it has assembled a team with expertise in cell biology, plant genomics, and algal production.

The stake in Sapphire Energy is not the first foray into alternative fuels for Gates' Cascade Investments. The firm invested in Pacific Ethanol, but later sold its shares as the company's stock price fell.

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Genomatica Develops Method to Replace Oil in Plastic-Making Process

World's first synthetic tree is no giant redwood, but may lead to technologies for heat transfer, soil remediation

In Abraham Stroock's lab at Cornell, the world's first synthetic tree sits in a palm-sized piece of clear, flexible hydrogel -- the type found in soft contact lenses.

Abraham Stroock and Tobias Wheeler
Robert Barker/University Photography
Abraham Stroock, left, and Tobias Wheeler, with a close-up of the synthetic tree on the computer monitor.

Stroock and graduate student Tobias Wheeler have created a "tree" that simulates the process of transpiration, the cohesive capillary action that allows trees to wick moisture upward to their highest branches.

The researchers' work, reported in the Sept. 11 issue of the journal Nature, bolsters the long-standing theory that transpiration in trees and plants is a purely physical process, requiring no biological energy. It also may lead to new passive heat transfer technologies for cars or buildings, better methods for remediating soil and more effective ways to draw water out of partially dry ground.

Of course, the synthetic tree doesn't look much like a tree at all. It consists of two circles side by side in the gel, patterned with evenly spaced microfluidic channels to mimic a tree's vascular system.

In nature, trees use water in tubular tissues, called xylem, like ropes that pull more water out of the ground, delivering it to leaves. They manipulate the water in the xylem under negative pressure -- what's called a metastable liquid state -- right on the verge of becoming a vapor.

synthetic tree image
Abraham Stroock and Tobias Wheeler
A transparent sheet of pHEMA, 1 millimeter thick, is etched with 80 parallel channels of varying lengths arranged to form a circle and connected by a single channel. The inset shows an optical micrograph of the cross-section of one microchannel.

synthetic tree
Tobias Wheeler
This optical micrograph of a synthetic tree shows a "trunk" channel entering from the left into a network of microchannels in the "leaf," or "root," network. The channels are approximately 100 micrometers wide, and total field of view is approximately 1.5 centimeters wide.

Xylem-like capillaries are relatively easy to create by microfabrication, but the researchers' choice of a material to act as membranes in the leaf and root to separate the liquid from the atmosphere and the soil was much trickier.

Stroock, assistant professor of chemical and biomolecular engineering, and Wheeler, a graduate student in his lab, used pHEMA hydrogel, or polyhydroxyethyl methacrylate, to form the plant membranes. The hydrogel is a solid embedded with water and has nanometer-scale pores. The material acts as a wick by holding liquid in the pores, through which capillary action creates tension in the water.

By building mimics of xylem capillaries within the gels, the scientists were able to create negative-pressures of the magnitude observed in trees, and to pump water against large resistances and out of subsaturated, or partially dry, sources.

Besides supporting the theory of transpiration as a physical, not biological, process, the synthetic tree also introduces a new way to study water under tension -- a subject interesting to physicists and chemists. Many questions about the metastable state of water could be answered using this new "tree."

"Water is the most studied substance on Earth, and yet there is a big metastable region in its phase diagram waiting to be characterized," Stroock said. His lab is pursuing these studies with support from the National Science Foundation.

The capillary action used in trees might be applicable to developing new passive heat-transfer methods, Stroock said. The heat-transfer technology commonly used for cooling laptops, which uses vaporization to carry the heat to the fan on the edge of the computer, could be scaled up using the technology developed for the synthetic tree.

"It would be nice if you could, in a building, put these passive elements that carry heat around very effectively, for example, from a solar collector on the roof, to deliver heat all the way down through the building, then recycle that fluid back up to the roof the same way trees do it -- pulling it back up," Stroock said.

He also envisions the synthetic tree helping to build better soil remediation systems. Instead of having to soak contaminated soil to pump contaminants out, transpiration could help pull the contaminated fluid out of the soil without the use of more liquid. Similarly, the technology could also be used to draw water out of relatively dry soil without having to dig a well down to the water table.

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