 NASA | The existence of a magnetic field four billion years ago may have given Mars its best chance for life. Was it brought on by the gravitational tug of orbiting asteroids? Some scientists think so. By Michael Reilly Before they brought destruction, a series of huge asteroids orbiting Mars four billion years ago may have sparked its magnetic field, giving the planet its greatest chance for harboring life. Mars has no magnetic field today. Cosmic radiation ravages its atmosphere and surface, a big reason why it is thought to be inhospitable to life. But between 4.5 and 4.0 billion years ago, its core of liquid iron and rock churned with intense heat, creating a dynamo that raised a protective magnetic force field around the planet. Then the magnetic field abruptly disappeared, and no one knows why. Jafar Arkani-Hamed of the University of Toronto thinks the field could've been powered by between one and four huge asteroids captured in Mars' orbit. About one percent the size of Earth's moon, any one of the enormous rocks would have had sufficient gravity to tug on Mars' core, causing enough convection to create a magnetic dynamo. "Theoretically, a retrograde orbiting, captured asteroid can produce a dynamo in the planet," Arkani-Hamed said. "If our moon orbited against Earth's rotation instead of with it, it could've have excited the dynamo here."
If Arkani-Hamed's theory is right, that would mean some of the 20 or so giant impact basins on Mars were formed when a few huge asteroids broke into pieces before landing in a fiery salvo. Many of the basins are scattered in arc-shaped patterns across the planet, each cluster suggesting that several rocks all traveled in the same orbital path, and may have once been one solid mass. "I don't think it's a crazy idea," Francis Nimmo of the University of California Santa Cruz, "but the problem you run into is one of duration." Phobos, one of Mars' two present-day moons, is also destined for impact. Arkani-Hamed's theory requires the giant asteroids of antiquity to power the dynamo for 500 million years before finally crashing home. Phobos only has about 50 million years before it hits. Nimmo also noted that not all of the basins in each arc match up in age, making it tough to argue that the cluster came from the same original giant rock. |
Wednesday, February 4, 2009
Did asteroids spark Mars' magnetic field?
Five mysteries of the universe
Dark matter ring in galaxy cluster Cl 0024+17. Some 96% of the universe is dark energy or dark matter. Photograph: Johns Hopkins University/Esa/Nasa
Even today, there are scientific phenomena that defy explanation. If history is anything to go by, resolving these anomalies could lead to a great leap forward, so what are the greatest mysteries, and what scientific revolutions might they bring?
1 The missing universe
Everything in the universe is either mass or energy, but there's not enough of either. Scientists think 96% of the cosmos is missing. They have come up with names for the missing stuff - "dark energy" and "dark matter" - but that doesn't really tell us anything about them. And it's not as if they're not important: dark energy is continually creating new swaths of space and time, while dark matter appears to be holding all the galaxies together. No wonder cosmologists are searching for clues to their whereabouts.
2 Life
I know you think you're more than a sack of molecules, but why? Next time you see a tree, ask yourself why that is alive when your wooden dining table is not. The phenomenon we call life is something that biologists have almost given up trying to define - instead they're investigating ways to make different combinations of molecules come alive. Bizarrely, the best hope is similar in chemical terms to laundry detergent.
3 Death
Here's the flip side: in biology, things eventually die, but there's no good explanation for it. There are hints that switching genes on and off controls ageing, but if our theory is right, those switches shouldn't have survived natural selection. Then there's the argument that an accumulation of faults does us in. However, there are plenty of whales and turtles who seem to age ridiculously slowly - if at all. Of course, if we can work out why, that could be great news for future humans (if not for the planet).
4 Sex
Charles Darwin might have fathered 10 children, but he couldn't understand why almost everything in biology uses sexual reproduction rather than asexual cloning - sex is a highly inefficient way to reproduce. We still don't know the answer. The suggestion that sex's gene shuffling makes us more able to deal with changing environments seems plausible, but the evidence is scarce. At the moment, sex only seems to exist to give males some role in life.
5 Free will
If you want to keep your sanity, look away now. Neuroscientists are almost convinced that free will is an illusion. Their experiments show that our brains allow us to think we are controlling our bodies, but our movements begin before we make a conscious decision to move. Some researchers have already been approached to testify in court that the defendant is not to blame for anything they did. A scary legal future awaits.
US wind power grew by 50% in 2008 as China's doubled
Many renewable energy technologies, most notably photovoltaic, are struggling to reach what's called "grid parity," where the cost of the power they generate matches that of fossil fuel generation. One technology that's largely there is wind, as maturing turbine technology and economies of scale have made the economics of wind power quite competitive. Those economics can clearly be seen in the latest figures on the growth of the wind industry, which cover 2008. Among the milestones: wind was the largest component of Europe's growth in electric generating capacity, the US became the world's top wind energy producer, and China doubled its installed capacity in just a year—for the fourth year running.
In total, the global installed capacity for wind energy went up nearly 30 percent last year, reaching 121GW. The 27GW installed represent an increase in total installations of 36 percent compared to the figures from 2007. The Global Wind Energy Council estimates that the market for new facilities alone is nearly $50 billion dollars.
With growth like that, there is a lot of good news to go around. Europe accounted for 8.9GW of the global growth, which made wind the leading source of new grid capacity (in the US, it came in at 42 percent of new capacity). The GWEC says that, in contrast to years past, when growth was concentrated in Denmark, Germany, and Spain, it was more evenly distributed in 2008, with countries like France and the UK adding significant capacity.
Asia as a whole accounted for about a third of the added global capacity, but there was nothing like an even distribution there—China accounted for 6.3GW of new installation, which marks the fourth year in a row that the country has doubled its installed wind power capacity. With more projects already in the works and the government having chosen to build wind capacity as part of its response to the economic crisis, the country is set for a repeat performance in 2009, which would take it past traditional wind users like Spain and Germany to second place in the global market.
It would be taking second place behind the US, which took the top spot after increasing its capacity by 50 percent in 2008, building 8.4GW of new facilities. The pace of growth had been picking up, as nearly half that figure came online during the fourth quarter. Unfortunately, the US affiliate of the GWEC, the American Wind Energy Council, says that orders have tailed off due to the credit crunch, and turbine manufacturers are beginning to cut jobs. That's bad news for one of the economy's bright spots—the AWEC estimates that wind energy jobs grew 70 percent last year.
As is happening globally, on the state level, the traditional users of wind power are being passed by some of the newer converts. California, with its famed Altamont Pass Wind Farm looking increasingly quaint compared to more recent facilities, has seen Iowa push it into third in terms of total installed capacity. Both are dwarfed by Texas' 7+ GW of capacity, which is more than the next three states combined. With facilities that are in the works, all of the top-10 states should exceed a Gigawatt shortly; that list includes New York, indicating that this growth isn't limited to the western two-thirds of the US.
Like most energy projects, wind power facilities are capital intensive, and capital is hard to come by in the US these days, so the report is accompanied by hopes that the US stimulus package will include provisions to expand wind energy even further, which should limit the job losses in manufacturing and prevent them from spreading downstream to construction and maintenance. The AWEA's CEO, Denise Bode, stated, "The hope is that provisions such as those included in the House stimulus bill to restore the effectiveness of the tax incentives for renewable energy will quickly become law and provide the capital needed to continue to build projects."
Research Breakthrough: Human Clones May Be Genetically Viable
For the first time since Hwang Woo-Suk's cloned stem cells were revealed as fakes, human cloning — for medical purposes, or even for reproduction — appears to be a realistic possibility. "We show for the first time that the same genes turned on in normal human embryos are the same genes turned on in human clones," said Robert Lanza, scientific director of Advanced Cell Technologies and co-author of a study published Monday in Cloning and Stem Cells.
Lanza's team inserted human cell nuclei into hollowed-out egg cells from both humans and animals, then stimulated them into development, a process called somatic cell nuclear transfer (SCNT), or more informally, cloning. When compared to a normal human embryo produced through in vitro fertilization, the animal-human hybrids didn't develop normally, but the human-human cloned embryos displayed many of the genetic characteristics of healthy development.
The research is the first step toward therapeutic cloning — making embryonic stem cells from a patient's own DNA capable of replacing diseased tissue, failing organs and even lost limbs. And, theoretically, the same technique could be used to produce a cloned person.
In 2001, Lanza's team claimed to have made cloned human embryos, stoking public hopes that cloning would soon produce thousands of embryonic stem cell lines — one for every common genetic group, capable of replacing diseased tissue, failing organs and lost limbs. It wasn't clear, however, whether those embryos were actually healthy, and their DNA was never analyzed.
Four years later, researchers led by the now-infamous Woo Suk Hwang claimed to have actually harvested embryonic stem cells from cloned embryos. The findings again raised public hopes, only to be revealed as fraudulent. Hwang now works for a controversial dog cloning company, and embryonic stem cells taken from a human clone remains hypothetical.
However, even if the scientific challenges of so-called therapeutic cloning are overcome, ethical problems remain. Harvesting human eggs requires women to take ovulation-inducing hormones, a process that is arguably dangerous and inarguably arduous. As a result, egg supplies are limited and expensive. Some scientists hoped to solve this by substituting animal eggs for human.
Research on these hybrid embryos — as well as chimeric embryos, formed by mixing actual human and animal DNA — was approved last year in the United Kingdom. But that approval came after bitter public debate in which opponents raised the specter of sentient human-animal hybrids being used as biological parts factories.
The latest findings suggest that hybrids are incapable of growing to a medically useful stage, much less sentience. But both cloning and induced pluripotency — a recently-developed procedure in which adult cells are transformed into an embryo-like state — should work.
"Science has a way to go with both of these, but we will soon have a way to create a bank of stem cells to expand the range of stem cell therapies," said Lanza.
His team compared the gene expression of a human embryo produced through in vitro fertilization with clones that incorporated human, cow, rabbit and mouse eggs. Several thousand genes were active in the fully human clones, but almost completely silent in their counterparts, which stopped developing after several days.
Among these were the genetic targets stimulated during induced pluripotency, in which adult cells are returned to an embryo-like state. Their silence suggests that animal eggs will not be useful in making clones capable of generating embryonic stem cells, much less growing to adulthood.
"You can never say never," said Lanza, "but we've been at this a very long time, and despite literally thousands of these attempts, we've never seen one of these hybrids advance further than what we're reporting here. And though negative results don't often get reported, I know for a fact that other experts have had the same results."
But the fully human cloned embryos could produce stem cells and, if permitted, perhaps grow into a person.
"The DNA resembles the DNA of a normal human embryo, which raises the question of human reproductive cloning," said Lanza.
However, New York Medical College cell biologist Stuart Newman disagreed with Lanza's assessment. Though the paper "shows that interspecies SCNT is a bust," he said, there are still "substantial differences" between fully-human cloned and IVF embryos.
But even if Lanza's embryos cannot develop, other scientists may come up with a more effective process. And though reproductive cloning has not yet been attempted, some experts say it's inevitable.
The procedure is illegal in the United States, but a global ban proposed in the United Nations fell apart after the U.S. insisted that therapeutic cloning be banned as well.
"Virtually every country agreed, but President Bush held it hostage," said Lanza.
President Barack Obama has promised to overturn President Bush's moratorium on federal funding of most embryonic stem cell research. Lanza hopes he will abandon Bush's position at the U.N. as well.
"Reproductive cloning is unsafe and unethical," he said. "This raises the urgency that those laws need to be passed."
A Leap for Teleporting, Between Ions Feet Apart
Without quite the drama of Alexander Graham Bell calling out, “Mr. Watson, come here!” or the charm of the original “Star Trek” television show, scientists have nonetheless achieved a milestone in communication: teleporting the quantum identity of one atom to another a few feet away.
The contraption is a Rube Goldberg-esque mix of vacuum chambers, fiber optics, lasers and semitransparent beam splitters in a laboratory at the Joint Quantum Institute in Maryland.
Even in the far future, “Star Trek” transporters will probably remain a fantasy, but the mechanism could form an important component in new types of communication and computing.
Quantum teleportation depends on entanglement, one of the strangest of the many strange aspects of quantum mechanics. Two particles can become “entangled” into a single entity, and a change in one instantaneously changes the other even if it is far away.
Previously, physicists have shown that they could use teleportation to transfer information from one photon to another or between nearby atoms. In the new research, the scientists used light to transfer quantum information between two well-separated atoms.
“It’s that hybrid approach that we’ve demonstrated that looks to be an interesting way to proceed,” said Christopher Monroe, a University of Maryland physicist and the senior author of a paper describing the research in the Jan. 23 issue of the journal Science.
Present-day digital computers store information as zeroes and ones. In a future quantum computer, a single bit of information could be both zero and one at the same time. (In essence, a quantum coin toss would be both heads and tails until someone actually looked at the coin, at which time the coin instantly becomes one or the other.) In theory, a quantum computer could calculate certain types of problems much more quickly than digital computers.
In the experiment, two ytterbium ions, cooled to a fraction of a degree above absolute zero, served as the two quantum coins. A microwave pulse wrote quantum information onto one; a second microwave pulse placed the ion into a state of equal probabilities of heads and tails.
A laser then induced each ion to emit exactly one photon, collected by a lens and guided through fiber optics to a beam splitter that could reflect the photons or let them pass through. Two detectors then captured and recorded the photons. Because it was not known which photon came from which atom, the photons became “entangled,” meaning that the behavior of the two particles became wrapped up in a single equation even though they were not in the same place. And, oddly, because the photons were emitted by the ions, the two ions also became entangled.
“That’s the magic of entanglement,” Dr. Monroe said. “Now, the atoms are entangled. The photons are gone and out of the picture.”
The information in the first ion was then measured in a way that did not reveal the information and that teleported the information to the second ion. (If that did not make any sense, take a look at this animated graphic.)
By repeating the experiment many times and taking many measurements of the second ion, the researchers, from Maryland and the University of Michigan, confirmed that the second ion contained the information that had been originally written to the first ion.
The method is not particularly practical at the moment, because it fails almost all of the time. Only 1 of every 100 million teleportation attempts succeed, requiring 10 minutes to transfer one bit of quantum information.
“We need to work on that,” Dr. Monroe said.
But he said that a success rate of just 1 in 10,000 would be high enough for some uses. Such systems could be used as “quantum repeaters” — reading the information from one photon and then imprinting it on a new photon for the next leg of its communications journey.
Chinese earthquake may have been man-made, say scientists
The 511ft-high Zipingpu dam holds 315 million tonnes of water and lies just 550 yards from the fault line, and three miles from the epicentre, of the Sichuan earthquake.
Now scientists in China and the United States believe the weight of water, and the effect of it penetrating into the rock, could have affected the pressure on the fault line underneath, possibly unleashing a chain of ruptures that led to the quake.
Fan Xiao, the chief engineer of the Sichuan Geology and Mineral Bureau in Chengdu, said it was "very likely" that the construction and filling of the reservoir in 2004 had led to the disaster.
"There have been many cases in which a water reservoir has triggered an earthquake," said Mr Fan. "This earthquake was very unusual for this area.
There have been no seismic activities greater than a magnitude seven quake along this particular seismic belt before."
The 7.9 magnitude quake struck last May and left more than five million people homeless. It remains a raw and emotional topic for most Chinese, and the government has been quick to quash any suggestion that Zipingpu may have been responsible for the catastrophe. Researchers have been denied access to seismological and geological data to examine the earthquake further.
Zipingpu is only one of nearly 400 hydroelectric dams in the earthquake zone. Mr Fan said the government had been warned of the danger of building so many large-scale projects in a seismically active area, but that the warnings had gone unheeded.
"I not only opposed the construction of Zipingpu, but also the overdevelopment of the reservoirs on Minjiang River. There are ten major reservoirs on the main river, 29 on its tributaries and a lot more smaller-scale reservoirs, all of which block the flow of the entire river, and are very hazardous to the local geology," he said.
Although Sichuan is an earthquake-prone region, many scientists were caught by surprise by the magnitude of the quake. Christian Klose, a scientist at Columbia University's Lamont-Doherty Earth Observatory, said there had not been any "major seismic activity" on that fault line for millions of years.
He argued that the sudden shift of a huge quantity of water into the region could have simultaneously relaxed the tension between the two sides of the fault, allowing them to move apart, and also increased the direct pressure enough to cause a violent rupture. The effect was "25 times more" than a year's worth of natural stress from tectonic movement, he said.
Although the official government line is that its massive construction projects had nothing to do with the quake, some state researchers in Beijing have called for a full investigation. Lei Xinglin, of the China Earthquake Administration, said that the Zipingpu reservoir "clearly affected the local seismicity and it is worthwhile to study the role it played in triggering the earthquake further". He added that firm conclusions remain "premature" however.
There is a history of earthquakes triggered by dams, including several caused by the construction of the Hoover dam in the US, but none of such a magnitude.
Original hereMany New Species Discovered In Hidden Mozambique Oasis With Help Of Google Earth
Space may be the final frontier, but scientists who recently discovered a hidden forest in Mozambique show the uncharted can still be under our noses. BirdLife were part of a team of scientists who used Google Earth to identify a remote patch of pristine forest. An expedition to the site discovered new species of butterfly and snake, along with seven Globally Threatened birds.
The team were browsing Google Earth – freely available software providing global satellite photography – to search for potential wildlife hotspots. A nearby road provided the first glimpses of a wooded mountain topped by bare rock. However, only by using Google Earth could the scientists observe the extent of woodland on the other side of the peak. This was later discovered to be the locally known, but unmapped, Mount Mabu. Scientific collections and literature also failed to shed light on the area.
“This is potentially the biggest area of medium-altitude forest I’m aware of in southern Africa, yet it was not on the map”, related Jonathan Timberlake from the Royal Botanic Gardens, Kew (RBG Kew), who led the expedition. “Most Mozambicans would not even have recognised the name Mount Mabu.”
Following scoping trips, a team of 28 experts from the UK, Mozambique, Malawi, Tanzania, Belgium, Ireland, and Switzerland ventured into it last autumn. They included scientists from BirdLife. The group was able to stay in an abandoned tea estate where the road ended, but had to hike the last few kilometres into the forest to set up camp. They had to contend with steep terrain and dense vegetation.
Inside, they found a wealth of wildlife, including three new species of butterfly and an undiscovered species of adder. The scientists believe there are at least two novel species of plant and perhaps more new insects to identify. They took home over 500 samples. “The phenomenal diversity is just mind-boggling”, exclaimed Jonathan Timberlake. Despite civil war from 1975 to 1992 ravaging parts of Mozambique, the landscape was found virtually untouched.
The site also proved to be important for birds, especially Endangered Thyolo Alethe Alethe choloensis, which is common throughout. “This may be the most important population of Thyolo Alethe known”, remarked Dr Lincoln Fishpool, BirdLife’s Global IBA Co-ordinator, who joined the expedition. “At other sites, forest is rapidly being lost or much of the habitat is sub-optimal”. There were six other Globally Threatened birds among the 126 species identified. Of these, Vulnerable Swynnerton's Robin Swynnertonia swynnertoni is particularly significant - bridging a large gap between known populations. Mozambique’s only endemic species, Near Threatened Namuli Apalis Apalis lynesi, was also seen. This was the first record of it away from nearby Mount Namuli.
Conserving Mount Mabu is now a priority. The forest’s value as a refuge to villagers during the war has thus far helped to protect it, along with poor access and ignorance of its existence. However local people are returning to the area and Mozambique’s economy is booming. There is a risk the forest will come under pressure to be cut for wood or burnt for crop space.
RBG Kew is working to protect the forest, as part of ongoing efforts with the Mozambique government. BirdLife has plans to recognise it as an Important Bird Area (IBA), “Mount Mabu effortlessly qualifies as an IBA”, said Dr Fishpool. Ground-level measures could be most effective conservation for the immediate future: “Remoteness is currently its best protection. We hope to work alongside the local tea-estate managers who are conservation-sympathetic and want to maintain the status quo of the forest”.
As for Google Earth, Jonathan Timberlake says the digital imagery has helped scientists realise more about the world. It may reveal further unnoticed pockets of diversity, especially in areas like Mozambique or Papua New Guinea. “We cannot say we have discovered all the biodiversity areas in the world”.
The expedition was led by RBG Kew and involved scientists from the Mozambique Agronomic Research Institute and the Mulanje Mountain Conservation Trust in Malawi, as well as BirdLife International. It was funded by the Darwin Initiative.
Sometimes 100 Cents Feels Like It's Worth More Than A Dollar
We all know that $1 is equal to 100 cents. But a new study suggests that, in some situations, people may behave as if 100 cents actually has more value.
That’s because people may pay more attention to the size of the numbers involved than the actual economic value, according to the research.
“In some cases, money may just serve as a score – the higher number wins, regardless of the actual value,” said John Opfer, co-author of the study and assistant professor of psychology at Ohio State University.
One important implication of this is that economic rewards don't necessarily affect behavior because of their economic value, Opfer said. Sometimes, it’s the numeric value of economic rewards that makes the difference. So people are more impressed by 100 cents than they are with $1, because 100 is larger than 1.
Opfer conducted the study with Ellen Furlong, a graduate student in psychology at Ohio State. Their study appears in the January 2009 issue of the journal Psychological Science.
The study involved testing subjects using a version of an often-used game in psychology, called the prisoner’s dilemma. In this version, two players had to decide separately and privately whether they were going to cooperate with each other or defect against their partner in exchange for a monetary reward.
If they both privately said they would cooperate, they both earned $3. If just one decided to defect, he earned $5 while the other person earned nothing. If they both chose to defect, they both earned only $1.
The game is designed to see under which conditions people will decide to cooperate with each other. Previous studies have shown that people are more likely to cooperate when the stakes are higher. In other words, players would be more likely to cooperate when they could both earn $300 for cooperating versus when they could only earn $3 for cooperating.
But Opfer said he wanted to find out whether it was really the economic value that predicted people’s decisions -- or simply the number value.
So in one study, the researchers had 48 college students play the prisoner’s dilemma game. Half of them played for dollars, and half played for the equivalent amount in cents. For example, some pairs could earn $3 for mutual cooperation, while others would earn 300 cents. They played the game 80 times in a row.
The study showed that the students who played for 300 cents cooperated more often than those who played for 3 dollars – even though both groups were playing for the same economic reward.
That means that those students playing for 300 cents acted as if they had more at stake than did those who were playing for 3 dollars.
“People were keeping track of the numbers, and not necessarily the values that were at stake,” Opfer said.
In a second study, the researchers tested to make sure that the findings from the first study didn’t result from a preference for dollars or cents, rather than a preference for higher numeric rewards.
Results of this study showed that players cooperated a similar number of times whether they were playing for $300 or 300 cents, even though the economic values are obviously extremely different.
They also cooperated a similar amount of times for $3 as they would for 3 cents – but there were fewer instances of cooperation here than there were for $300 or 300 cents.
“It shows that the effects of dollars or cents is minimal when people are deciding whether to cooperate– all that matters is whether you’re playing for a “3” or a “300,” Opfer said.
“The incentive to cooperate isn’t really an economic incentive. It is a confusability about numbers.”
The fact that people are easily impressed by large numbers has many real-world implications. For instance, while the economic difference between $3 and $5 is identical to the economic difference between $103 and $105 ($2 in both cases), the difference between 3 and 5 feels more important to us than the difference between 103 and 105.
“The differences between big numbers don’t seem as important to us as the differences between small numbers,” he said. “We think about the numbers differently.”
These findings challenge some basic assumptions about how people make decisions. For one thing, political parties or large corporations may be willing to cooperate when dealing with large amounts of money, such as in the recent $700 billion bailout of the financial industry, simply because they are awed by the large numbers, Opfer said.
For smaller amounts, like the proposed $15 billion bailout of the auto industry, people would be expected to be less cooperative.
“We’re not alone in our tendency to treat differences between small numbers as more important than differences among large numbers -- pigeons, rats, monkeys and human infants all do the same thing,” Opfer said.
Political parties and large corporations aside, when an individual decides whether to save for the future, or evaluates the risk of an investment, their decisions may also be influenced by the size of the numbers involved, according to Opfer.
“For better or worse, reframing our choices in terms of smaller numbers allow us to better see the relative risks and benefits of our decisions,” he said.
Swearing and social networks
The Enron email dataset provides a nice chance to test out these claims. It is large (about 250,000 distinct messages, sent and received by over 11,000 distinct email addresses), and it contains a moderate amount of bad language. Not everyone swears, but a fair number of people do. The topics range widely: fantasy football, faith, energy markets, vacation time (and of course bankruptcy and the FERC). So, with some qualifications that I'll get to, it is a useful testing ground for claims about swearing and risky verbal behavior. The following email network graph is my first stab at conducting such a test:
The nodes represent 99 people with Enron email addresses who had relatively high email traffic in the dataset: at least 50 messages sent to other people in this group of 99, and at least 50 messages received from other people in this group of 99. (Messages that included any outsiders in their "To" lists were excluded.)
- A red arrow from node A to node B means that user A swore in a message to user B at least once.
- The thickness of the arrow's line represents the amount of traffic from A to B: a thick arrow from A to B means that A sent at least 20 messages to B, and a thin arrow means A sent between 1 and 19 messages (inclusive) to B.
The different line thicknesses might be hard to see at first, because the vast majority of the lines in this network are thick. I claim that this is no accident. It reflects the fact that, in this corporate setting, swearing is risky enough that it is best done only with people you know well. Your first few messages to someone are unlikely to contain swears, but you might build up the courage over time.
I can quantify the visual impression that these arrows are mostly thick: just 1.6% of the possible from–to pairs in this sample set have message counts of 20 or more, whereas 78% of the from–to swearing-pairs have message counts of 20 or more. If you squint, you can see this contrast reflected in the following version of the network, in which a gray arrow from A to B means that A swore at someone or other in the sample but sent only swear-free messages to B in this dataset. (Note: This is an update/improvement; the previous visualization included arrows for nonswearers as well, which resulted in a mass of gray in the middle of the network. My thanks to Dougal Stanton for the suggestion in the comments.)
There is one effect that I expected to observe but did not. Because swearing is risky, the safest situation in which to swear is one in which your hearer has already sworn with you. Thus, I expected most of the red arrows to form symmetric pairs. (See also this post on Jamie Pennebaker's work.) In fact, very few red arrows run in both directions in this sample. I suspect that this is due to a major drawback (for my purposes) to the dataset: many of these relationships are hierarchical. It's one thing if Skilling calls you or someone else an asshole, and quite another to use that as an invitation to do some swearing yourself.
In closing, thanks are in order: to the people behind statnet, the amazing R library that let me build the above networks using just simple matrices of counts, and to all the people who worked to tame the wild Enron dataset, especially Andrés Corrada-Emmanuel for his tools for identifying users and removing repeat messages.
Original hereGlobal Scientists Draw Attention To Threat Of Ocean Acidification
More than 150 leading marine scientists from 26 countries are calling for immediate action by policy-makers to sharply reduce CO2 emissions so as to avoid widespread and severe damage to marine ecosystems from ocean acidification.
The scientists issued this warning Jan 30, 2009 in the Monaco Declaration, a statement based on the conclusions of participants at last October’s 2nd international symposium on The Ocean in a High-CO2 World.
Professor Andrew Dickson, a marine chemist at Scripps Institution of Oceanography, UC San Diego and professor Victoria Fabry, a visiting research scientist at Scripps, were among the signatories to the declaration.
The scientists note that ocean acidification is already detectable and is accelerating. They caution that its negative impacts can be avoided only by limiting future atmospheric CO2 levels.
“Studies presented at the Monaco meeting further highlighted the likely problems of ocean acidification to our oceans,” said Dickson. “I am glad to be a signatory to this declaration, and look forward to working with my colleagues to improve our knowledge of this important area and to communicate that knowledge to a wider audience.”
It is well established among researchers that the uptake of increased amounts of carbon dioxide will make ocean water more acidic as the gas dissolves to create carbonic acid. Ocean chemistry is changing 100 times more rapidly than in the 650,000 years that preceded the modern industrial era and since the late 1980s, researchers at Scripps Oceanography and others have recorded an overall drop in the pH of the oceans from 8.16 to 8.05.
This increased acidity can hamper the ability of a wide variety of marine organisms ranging from coral to abalone to form calcium carbonate shells and skeletonal structures. Researchers believe that at crucial stages in the larval and juvenile stages in the lives of many marine invertebrates, ocean acidification inhibits calcification, and also appears to affect reproduction and growth in some organisms.
Scripps Oceanography is emerging as an international center of ocean acidification research. Late Scripps geochemist Charles David Keeling is best known for his famous record of atmospheric carbon dioxide concentrations known as the Keeling Curve, but he also started the first time series of ocean carbon dioxide content in 1983 near Bermuda. Dickson established the reference standards for measurements of carbon dioxide content and alkalinity of ocean water that have helped researchers accurately measure trends in acidification over the past 20 years. Additionally Scripps researchers have deployed one carbon dioxide sensor off the California coast and have plans to launch two more in 2009.
“This declaration clearly articulates the urgency of the problem of ocean acidification and the potential severity of its impacts to marine ecosystems,” said Fabry, a marine biologist who also works as a professor at Cal State University, San Marcos.
Prince Albert II of Monaco has urged political leaders to heed the Monaco Declaration as they prepare for climate negotiations at the United Nations Framework Convention on Climate Change conference in Copenhagen this year.
“I strongly support this declaration, which is in full accord with my efforts and those of my Foundation to alleviate climate change,” he said.
Scripps Director Tony Haymet and Prince Albert recently met to consider ways in which Scripps and the Prince Albert II of Monaco Foundation could marshal their resources in one or more joint scientific collaborations to better understand and address the growing threat of ocean acidification.
“Scripps and Monaco have a shared commitment to meet this challenge,” Haymet said. “We are working toward creating a partnership on ocean acidification, knowing our combined expertise and resources will have a much greater impact.”
The Monaco Declaration is based on the Research Priorities Report developed by participants at last October’s 2nd international symposium on The Ocean in a High-CO2 World, organized by UNESCO’s Intergovernmental Oceanographic Commission, the Scientific Committee on Oceanic Research (SCOR), the International Atomic Energy Agency (IAEA) and the International Geosphere Biosphere Programme (IGBP), with the support of the Prince Albert II of Monaco Foundation and several other partners.
“The chemistry is so fundamental and changes so rapid and severe that impacts on organisms appear unavoidable,” said James Orr of the Marine Environment Laboratories (MEL-IAEA) and chairman of the symposium. “The questions are now how bad will it be and how soon will it happen. The report from the symposium summarizes the state of the science and priorities for future research, while the Monaco Declaration implores political leaders to launch urgent actions to limit the source of the problem.”
“In order to advance the science of ocean acidification, we need to bring together the best scientists to share their latest research results and to set priorities for research to improve our knowledge of the processes and of the impacts of acidification on marine ecosystems,” explained Patricio Bernal, executive secretary of UNESCO IOC. “The Ocean in a High-CO2 World Symposia Series provides this forum to scientists every four years, and the Research Priorities Report it produces represents an authoritative assessment of what we know about acidification impacts.”
Potential New Target For Hypertension Treatment Discovered
The LSUHSC research team showed that Angiotensin-converting enzyme 2 (ACE2) helps preserve the function of a key spontaneous reflex involved in blood pressure regulation and confirms its potential as a target for the prevention or treatment of High Blood Pressure. The research is published in the February 1, 2009 issue of the peer reviewed journal, Hypertension.
The LSUHSC researchers had previously identified ACE2 in the mouse brain in areas involved in the central regulation of cardiovascular function. In this study, they wanted to clarify the role it plays.
Beat-to-beat short term regulation of blood pressure is provided by a spontaneous reflex called the baroreceptor reflex. Receptors in the arteries sense blood pressure and relay the information to the central nervous system where a network of brain stem cells adjust vascular resistance and heart rate. Action of a hypertensive hormone – Angiotensin II – is known to interfere with that process.
First, the researchers demonstrated that chronically hypertensive mice showed dramatically decreased baroreceptor reflex sensitivity and ACE2 activity. Following treatment with compounds to block both Angiotensin II receptors, the researchers found that by blocking one of these receptors – AT1Rs – ACE2 activity increased. In order to determine the relationship between AT1Rs blockade and ACE2, as well as the significance of ACE2, the LSUHSC researchers generated a triple-transgenic mouse model with increased ACE2 on a background of chronic hypertension. In this model, they observed that the impaired baroreceptor reflex and other critical functions normalized, as did blood pressure.
"We now have evidence that brain ACE2 plays a critical role in baroreceptor reflex function and , consequently, in the prevention of hypertension," says Dr. Xia.
"Blood pressure" is the force of blood pushing against the walls of the arteries as the heart pumps out blood. If this pressure rises and stays high over time, it can damage the body in many ways. According to the National Institutes of Health, in the United States, about 72 million people have hypertension or High Blood Pressure (HBP). This is about 1 in 3 adults. HBP itself usually has no symptoms. Rarely, headaches may occur. Some people only learn that they have HBP after it causes health problems, such as coronary heart disease, stroke, or kidney failure.
"Beyond our discovery of ACE2, we have now confirmed its potential as a target for the treatment of hypertension and other cardiovascular diseases," concludes Dr. Lazartigues.
Women with large chins are more likely to cheat
Psychologists have found that adult females who have prominent chins are more sexually active than those with softer features, yet are less attractive to men looking for a long-term partner.
Larger chins on women are often caused by a high level of the male growth hormone testosterone, present in all women in various amounts.
The hormone also increases sexual assertiveness in a woman, a tendency more commonly attributed to males.
The researchers, from four universities across the US and Canada, took a group of young women and questioned them on their sexual histories and fantasies.
These women were then rated by a group of men on their desirability as a life partner.
It was concluded that men will shun women with such masculine features when looking for a long-term partner because they fear being cuckolded.
Psychologists believe it is linked to their evolutionary desire to have a partner who will produce children for only one man.
Authors of the study, published in the journal Personality And Individual Differences, said: "The findings are important in demonstrating that perceptions of women as desirable and trustworthy long-term mates can be reliably gleaned by men from viewing only the women's facial features.
"Results suggest that information about women's sexual unrestrictedness, which is related to their risk of infidelity, can potentially be conveyed by the masculinity of women's faces."
The theory has many examples in the celebrity world.
Actress Meg Ryan, 47, who has a strong chin, famously cheated on her husband Dennis Quaid with her co-star Russell Crowe.
However, the actress Joanne Woodward, who has a dainty jawline, was happily married for 50 years to Hollywood icon Paul Newman until his death in September.
Dr Lorne Campbell, a psychologist from Western Ontario University, who took part in the project, wrote: "It is difficult to conceal physical features, such as facial characteristics, that are partly governed by testosterone and reliably correlate with one's sexual history and attitudes.
The research is the first to our knowledge to suggest that a more masculine facial appearance in women might convey their sexual unrestrictedness and perhaps their long-term mate quality."
Original hereFingerprints Are Tuned to Amplify Vibrations and Send Info to the Brain
Fingerprints are for more than a good grip; they also allow fingers to feel fine textures, according to a new study. As fingers move across a surface, the intricate geography of the finger tips, known as epidermal ridges, help select and amplify just the right vibrations to convey information from the skin to the brain. Neuroscientist Ellen Lumkin compares the ridges on fingers to the cochlea in the ear. “Like the cochlea is a frequency analyzer for sounds, the fingertips are frequency analyzers for fingers,” says Lumpkin [Science News] Fingerprints help filter out the tactile equivalent of white noise.
When a finger sweeps over a finely textured surface, such as a cotton sleeve or a wooden coffee table, the interaction sends a large range of vibrations into the skin. Specialized sensors called Pacinian fibers, the tips of nerve fibers, detect only a select few of the vibrations — those right around 250 hertz — before sending the signal to the brain, where the touch sensation is processed [Science News]. But since Pacinian fibers are located relatively deep—about 2 millimeters—under the skin, researchers guessed that fingerprints help magnify the vibrations.
To study the effect of fingerprints, they created a tactile sensor that closely mimics the actions of our fingers. Their sensor can be equipped with either a smooth fingertip or a “fingerprinted” one. The researchers compared how these two types of fingertips performed on different textures by measuring their pressure variations with a microforce device [Ars Technica]. The “fingerprinted” sensor, which has parallel ridges about half a millimeter apart, imitates the human finger. Like sunglasses that filter out UV light and let the useful visible light through, the artificial fingerprints filtered out vibrations above and below 250 hertz, leaving only the vibrations that could be detected by Pacinian fibers [Science News]. The smooth sensor created less friction and picked up a wider range of unamplified signals, researchers reported in Science [subscription required]. Lead researcher Georges Debrégeas says, “Fingerprints might actually improve the sensitivity of perception by enhancing the skin vibrations at a frequency that matches the best frequency of these Pacinian corpuscles,” [Nature News].
The researchers noted that their artificial fingerprints worked only if the direction of motion was perpendicular to the direction of the ridges. Thankfully, the whorls, arches, and loops on real human fingertips mean that swiping in any direction will activate the filtering effect. This could imply that the contours of our fingerprints are patterned to optimize texture perception [Ars Technica]. Understanding the physics behind touch could help scientists build better prosthetics for amputees or robots capable of a sensitive touch and delicate handiwork. But the first challenge, the researchers say, is to replicate the results from the elastic faux fingers using real human fingers.
How Ancient Greeks Chose Temple Locations
To honor their gods and goddesses, ancient Greeks often poured blood or wine on the ground as offerings. Now a new study suggests that the soil itself might have had a prominent role in Greek worship, strongly influencing which deities were venerated where.
In a survey of eighty-four Greek temples of the Classical period (480 to 338 B.C.), Gregory J. Retallack of the University of Oregon in Eugene studied the local geology, topography, soil, and vegetation — as well as historical accounts by the likes of Herodotus, Homer, and Plato — in an attempt to answer a seemingly simple question: why are the temples where they are?
No clear pattern emerged until he turned to the gods and goddesses. It was then that he discovered a robust link between the soil on which a temple stood and the deity worshiped there.
For example, Demeter, the goddess of grain and fertility, and Dionysos, the god of wine, both were venerated on fertile, well-structured soils called Xerolls, which are ideal for grain cultivation.
Artemis, the virgin huntress, and her brother Apollo, the god of light and the Sun, were worshiped in rocky Orthent and Xerept soils suitable only for nomadic herding.
And maritime deities, such as Aphrodite, the goddess of love, and Poseidon, the sea god, were revered on Calcid soils on coastal terraces too dry for agriculture.
The pattern suggests that the deities' cults were based on livelihood as much as on religion. And, says Retallack, temple builders may have chosen sites to make the deities feel at home.
Across the ocean in a pedal-powered submarine
Ted Ciamillo's pedal-powered submarine may seem like a stunt, but marine biologists are paying serious attention (Image: Subhuman Project)
SOME men mark their 40th birthday by buying a flashy new car, changing jobs or finally getting started on that novel. Ted Ciamillo decided he would pedal across the Atlantic in a one-man submarine he has designed and built himself.
It may sound like a crazy stunt dreamed up by an adrenalin junkie, but the plan, dubbed the "Subhuman project", has attracted serious attention from marine biologists. That's because the sub, when it takes to the seas later this year, could for the first time allow them to explore the upper layers of the ocean silently and unobtrusively, revealing marine life as it has never been seen before.
Ciamillo, a machinist by training and an inventor by trade, does have a track record in underwater exploration. In 1997 he made his name designing a James Bond-style underwater propulsion vehicle called the Hydrospeeder, which looks something like an underwater motorbike. Although the company that sold the Hydrospeeder later folded, Ciamillo remained keen to speed up underwater exploration. "I found myself frustrated by how slowly you move under water, especially with a bunch of dive gear on your back," he says. "It's like dropping someone in the middle of the forest in a wheelchair."
So, in collaboration with marine biologist Frank Fish of West Chester University in Pennsylvania, who specialises in the biomechanics of cetacean swimming, Ciamillo designed a carbon-fibre "tail" for divers, called the Lunocet. Modelled on Fish's CAT scans of dolphin flukes, the Lunocet has a hydrofoil profile, like an underwater wing. "As dolphins move their tails up and down, they create a forward-directed lift," says Fish. This lift becomes thrust, and lots of it: dolphins have been clocked at 54 kilometres per hour. They can turn 80 per cent of their energy into thrust, compared with a paltry 3 per cent or so for unaided human swimmers and about 10 per cent for people wearing ordinary swim fins.
The Lunocet operates in a similar way, to enable the diver to swim as efficiently as possible. A dolphin-tail configuartion has previously been shown to be up to 15 per cent more efficient at transforming energy into forward motion than even the best rigid propellers.
Ciamillo and Fish say they knew they were onto something when the first prototype Lunocet, a piece of sculpted foam sandwiched between two pieces of carbon fibre, essentially swam by itself. When they released it at the bottom of a test pool, its buoyancy combined with its cambered shape generated a forward thrust that made it scoot across the tank. The company started selling the Lunocet last year and Ciamillo has already used one to propel himself at nearly 13 kilometres per hour, almost twice the top speed of Olympic swimming champion Michael Phelps.
Ciamillo designed his mini-submarine around a larger version of the Lunocet. The body of the vessel is built from lightweight yet tough materials: a stainless steel frame, a polycarbonate shell and a propulsion system made from aluminium and titanium. It will operate as a "wet" sub: instead of having a pressurised shell filled with air, it will be full of water at all times. Buoyancy is provided by PVC foam packed into the shell and from air bladders that can be filled or emptied to keep the vessel at the desired depth. At 1.2 metres at its widest point by 5 metres long it is not exactly roomy, but neither is it claustrophobic. "Being weightless, with all the windows, you feel like you have plenty of room," Ciamillo says.
Ciamillo will wear a wetsuit and breathe using scuba gear or a specially adapted snorkel. A major challenge will be keeping cool, since the average water temperature will be around 30 °C. One plan is to use a reflective coating to prevent the sun shining in through the top of the sub and heating the water inside.
Ciamillo will drive the sub from a seated position by pushing pedals back and forth, while also moving his arms forwards and backwards. It's "like a Stairmaster crossed with a cross-country ski machine", he says. The arm-and-leg drive system is linked to the flapping tail through a system of pulleys linked by a stainless steel cable.
To pedal the 3700 kilometres of open water from Cape Verde off the west coast of Africa to Barbados in the Caribbean should take around 50 days, Ciamillo estimates. He plans to pedal 2 metres below the surface all day, coming up only at night when he will sleep in a tent erected on the top of the sub. If the wind is blowing in the right direction he'll fly a kite to gain a few extra miles while he sleeps. In bad weather he'll take the sub below the surface and sit out the storm. This could be risky. If the waves take him too deep for too long and he then surfaces too quickly he risks the "bends", caused by dangerous bubbles of nitrogen in his blood. Another risk it that his air tanks run out of air while he sleeps, or if he is unable to surface to exchange them. "There are dangers in every point in the water column for a diver in a wet sub operating in high seas," says Ciamillo.
Perhaps unsurprisingly, not everyone is convinced he'll make it across the Atlantic. "Most human-powered subs seem to work best with propeller mechanisms," says Jerry Rovner, director of operations for the annual International Submarine Races in Bethesda, Maryland. "It's been our experience that the fish-design boats don't have enough power," he explains. "We get them in every race... he's not going to get very far unless he's superhuman."
Undaunted, Ciamillo says he plans on intense physical training, including running and weightlifting, and may even have his appendix removed before the attempt, to eliminate the tiny chance that it may burst during the 50 days he is at sea. In an attempt to prepare mentally for the journey he consulted sailor Steven Callahan, who famously spent two-and-a-half months in a survival raft after his yacht sank in the Atlantic in 1982, and wrote the book Adrift about his experiences.
While Ciamillo freely admits that his project began as a way to get publicity for the Lunocet, it has also attracted the attention of marine researchers, excited by the wealth of data he could gather for them on his journey. The surface of the sea is a surprisingly little-known part of the biosphere, considering it covers two-thirds of the planet, says marine ecologist Cindy Van Dover of the Duke Marine Laboratory in Beaufort, North Carolina. "Current technologies and sampling methods allow us to study surface waters more as series of discrete points rather than as an environment and habitat," she says. "Near-surface waters are nearly as impenetrable as the depths of the ocean."
Studies that have been done, covering about 5 per cent of the ocean, have used destructive nets, or noisy boats or submarines studded with claws, motors and lights. The small size and motorless stealth of Ciamillo's sub, combined with its range and manoeuvrability, will allow it to gather data like no other vehicle, Van Dover says. "The Subhuman project could give us sustained access to these immense fields of biological productivity in a way we have not experienced before."
To that end, high-resolution video cameras mounted on the sub will run constantly to record everything from whales to plankton, as well as pollution such as floating trash and oil slicks. Once a day, Ciamillo will rendezvous with a support boat that will trail him the entire way and exchange exhausted batteries, videotapes, hard drives and air cylinders for fresh ones.
Bioluminescence researcher Edie Widder of the Ocean Research and Conservation Association in Fort Pierce, Florida, is particularly excited by what Ciamillo might see. They are working together to mount a highly sensitive camera called the Eye in the Sea on the sub's nose, to search for elusive bioluminescent creatures that venture up at night from the depths to feed in surface waters. As many as 80 to 90 per cent of species in the open ocean may be bioluminescent, says Widder, making it possibly the most common form of visual communication on the planet. Even so, "we still don't know precisely why animals light up," she says, "or even how many types of glowing creatures there are down in the depths."
Widder has already used the Eye on the floor of the Gulf of Mexico. There the camera was fitted with a lure nicknamed the "e-jelly" that mimics the flashing distress pattern of a deep-sea jellyfish. Less than 90 seconds after they first turned on the lights, the camera recorded a 2-metre-long squid that didn't fit into any category known to science. Another time, something larger left the camera face-down in the mud 50 metres away from its original position.
Ciamillo hopes to avoid whatever that was, but still plans to use the Eye for some night-time exploration, taking the sub down to 20 metres for 45 minutes at a time in search of bioluminescent creatures. It will be the first time the Eye has ventured beyond the continental shelf. "I've spent a lot of my career exploring the ocean with submersibles, but I've always been frustrated by the thought of how many animals we must be frightening away," says Widder. "I can't imagine a better vehicle as a first approach."
Before any of this can happen, though, the sub has to complete a programme of rigorous test runs in the 4000-cubic-metre lagoon that Ciamillo had dug outside his workshop in Georgia. So far it has proved buoyant and manoeuvrable, and the team are now tweaking the propulsion mechanism. That done, a series of two and three-day trial expeditions in the Florida Keys in the next few months will give both sub and pilot a thorough shakedown before the final launch from Cape Verde, slated for November.
Whether or not Ciamillo makes it to Barbados, the project will provide an invaluable service to marine science, Van Dover says. "So long as the vehicle doesn't become prey itself, the sensors it carries and the observer inside have a real possibility of changing the way textbooks describe the upper layers of the water column."
For her part, Widder hopes the audacious plan will help focus attention on the marine environment. "This is an ocean planet we're living on," she says. "If the oceans are in trouble, we're all in trouble. Maybe Ted swimming across the Atlantic will help to hammer than point home."
As for Ciamillo, he just wants to get across the Atlantic in one piece, mainly to see if he can. "This is the craziest thing I have ever done or ever will do," he says. "So I'm going to have as much fun doing it as I can."
Efficiency and Recycling at the Super Bowl
When Super Bowl XLIII kicks off this evening in Tampa Bay, officials at Raymond James Stadium are ready to showcase not just football, but energy efficiency and recycling.
Over the past five years, efficiency measures like smarter use of chillers and better lighting have saved the stadium $580,000, officials estimated. (That’s roughly the price of 300 low-end Super Bowl tickets available Friday for resale on Stub Hub.)
The stadium’s electric bill has risen by just 23 percent in five years, better than the average increases of 42 percent.
“Those are things that the fan doesn’t really notice or see, but we’re certainly making a big impact on the bottom line,” said Mickey Farrell, the director of the stadium operations, who has been working with Johnson Controls, a company specialized in energy efficiency, to put in state-of-the-art efficiency systems — including L.E.D. lighting, which is now used in some of the stadium’s colorful displays.
One particular challenge, Mr. Farrell said, is Tampa Bay’s humid climate. The goal is to use the “least amount of power we possibly can to make sure the humidity is controlled,” he added.
Recycling and composting are also being deployed on game day. Plates, napkins and even forks and straws are supposed to be biodegradable — and cooking grease is to be recycled. Plastic drink bottles will also be recycled, stadium officials said.
Other stadiums have made an effort to go green, too. Last month, I reported on the composting efforts at the University of Colorado’s football games.
Transport hit as UK wakes to heaviest snow in decades
A bus goes past the House of Commons as it crosses Westminister Bridge during a snow fall in London Photograph: Andrew Parsons/Reuters
The heaviest snow for two decades moved into Britain on a freezing easterly wind last night after gathering strength over the North Sea. Falls of up to 10cm (4in) are predicted initially on the south-east coast and inland as far as London before the storms head north.
The Met Office said it was classifying today's expected snowfall as an "extreme weather event".
It was already causing chaos last night as trains were delayed and some airport runways temporarily closed. Gatwick and London City airports were both temporarily shut as their runways were de-iced, although City failed to reopen, as it closes ordinarily at 10pm. A Gatwick spokeswoman said that 23 flights had been cancelled and 18 diverted, although the runway reopened at 10pm.
A number of train services linking London and the south coast were also delayed or cancelled as snow drifted on to the tracks. And all London bus services were withdrawn, according to Transport for London's website.
High ground in Kent and Sussex could see as much as 20cm fall. "Severe disruption to roads and airports is extremely probable during the peak of the Monday afternoon rush hour," said Tom Defty, head of forecasting operations at MetService.
Blizzards and drifts may affect coastal areas and close scores of roads if high winds persist. The northbound M20 in Kent was closed last night between Ashford and Leeds castle after icy roads caused a series of minor collisions. There were no injuries. Forecasters predicted the gathering strength of the cold front would see heavy falls well inland and moving north, with 5cm predicted for Leeds and Bradford in Yorkshire.
Forecasters predict that the freeze will match conditions in the winter of 1991 when blizzards were followed by a prolonged period of temperatures well below freezing. Drifts up to three metres high closed roads and rail lines and shops saw a brief but marked drop in takings as fewer people ventured out.
The current snap is expected to thaw much sooner, with temperatures rising later this week, but further snow is forecast. Overall, the renewed cold spell is certain to seal this winter's dubious distinction of being the coldest for 13 years.
Gale force winds were recorded in several areas offshore as the snow moved towards the long curve of the Yorkshire and Lincolnshire coastline between Bridlington and Skegness.
People across the country were warned to avoid unnecessary journeys, with below-freezing temperatures dropping even further in many areas because of wind chill. The snow follows a relatively mild spell after the three-week freeze in early January which saw lows of -13C (8.6F). The previous coldest winter was in 1995 when -27.2C was recorded at Altnaharra in the northern Highlands.
Bookmakers have cut odds against 2009 being the coldest winter on record from 12-1 to 8-1 but a counter-trend is also seeing betting on a hot summer.
Rupert Adams of William Hill said: "Punters seem to be confidently optimistic about that and we have odds of as low as 6-1 on temperatures topping 100F."
Robert Hutchison of Ladbrokes said bets had started coming in that the Thames would freeze, with odds at 80-1. He said: "We're also seeing plenty of bets on a white Valentine's Day after the disappointment of missing out on snow at Christmas."
Iowa's green energy policy struggle
BBC News, Iowa
The presence of prairie winds and rich soil makes Iowa literally fertile ground for developing alternative energy sources from wind turbines and biofuels.
 Iowa invested $6m in wind turbine manufacturing |
But the landscape is also a reminder that achieving energy independence is a formidable challenge and making an agricultural economy green is not easy.
Farm workers cannot take subways to work, farmers have to drive long distances into the fields to sow and harvest their crops and to deliver them to markets.
Farm animals themselves, not to put too fine a point on it, produce methane - a powerful greenhouse gas - that is trapped in the atmosphere.
Those challenges have not stopped the state setting itself ambitious goals.
Energy pioneers
The Iowa Climate Change Advisory Panel recently wrote a report for Governor Chet Culver setting out how the state can reduce carbon emissions by 90% by 2030.
The state has set up an Office of Energy Independence - surely the perfect place, I thought, to test how easy it will be for President Obama to achieve energy independence for the whole of America.
There are plenty of energy pioneers to be found in Iowa.
 |  I feel like I'm doing something more than just building a washing machine, I'm building something for everyone to capitalise on  Crugar Tuttle Wind turbine factory worker |
Roger Neuberger, a farmer, lives near Clear Lake in the north-west part of the State - where the wind blows hardest.
He gets money from an energy company each year for making room for two wind turbines on his land.
Mr Neuberger has promised the energy company that he will not publicly reveal how much he is being paid, but other farmers have let it be known that, depending on when their contracts were signed, they can receive somewhere between $2,000 (£1,400) and $4,000 per turbine every year for the next 30 years.
Mr Neuberger is very happy, if rather modest about his role at the new frontier.
Asked if he felt like a pioneer, he replied: "Yeah, I suppose so."
"There were a number of farmers who didn't want to do this because they didn't understand - they were concerned how they were going to be treated. We've been treated wonderful. I couldn't ask for anything better."
Foreign oil
Iowa hopes that wind energy will deliver more than just electricity - and that investment in wind technology will help to transform towns depressed by unemployment.
Towns like Newton, which is just to the east of the capital, Des Moines.
Nearly 2,000 people lost their jobs in Newton when the town's biggest employer, Whirlpool, shut its doors in 2007.
 Is ethanol really a clean alternative to fossil fuels? |
But the jobs did not come cheap.
The state gave the manufacturer $6m in subsidies and tax breaks - in return the company promised to hire 500 people.
Larry Crady worked at Whirlpool for 23 years, making coin-operated laundry machines.
"It just wows you when you see a blade open and close," Larry says. "When you pull that blade out of the mould it's exciting, I feel like I'm doing something more than just building a washing machine, I'm building something for everyone to capitalise on."
Mr Crady's sense of wonder is understandable - the plant certainly has the "wow" factor.
The turbine blades are as long as a 747 jet and the factory is longer than an aircraft carrier.
It is fitting, then, that - according to the plant's manager - so many of those that work there feel that making the blades is as much about national security as it is about electricity.
"A lot of us in this company and in wind energy have a sense of calling to this," Crugar Tuttle says. "I think in the interview process it comes out with a lot of our veterans that this is about weaning us off foreign oil."
But wind energy is a long way from delivering independence for Iowa any time soon.
It provides just 8% of Iowa's energy needs.
If it is to go any way towards making the rest of the country energy independent, a distribution grid would be needed.
Controversial
President Obama has promised to invest $150bn in renewable energy over the next 10 years.
He hopes to increase dramatically the contribution that wind, solar and other renewable sources can make to the country's energy supply.
According to current projections, renewables will still be providing only 8% of the country's energy supply 20 years from now.
Certainly, energy independence will not be possible without replacing the foreign petrol used in cars.
| We need sources of power that are constant and don't rely on things like whether the wind's blowing or the sun's shining Phil Wyse Iowa state representative |
Many Iowans think the solution is biofuels (as do most presidential candidates - albeit only while they are campaigning in the crucial Iowa caucuses).
Refineries across the state produce 1.5 billion gallons of ethanol a year - enough to replace 10% of the petrol in America's cars.
But biofuels are controversial.
A UN report says they drive up the price of food.
And is ethanol really clean?
We visited POET's ethanol plant in Hanlontown in the northern part of Iowa.
The plant, like most in the state, is powered by fossil fuels.
I spoke to POET's Vice President for Project Development, Larry Ward.
He insists that despite the use of natural gas in the production of ethanol, it is a good bargain.
"There's a tremendous net gain from an energy standpoint. Using natural gas to produce ethanol you have a gain - for every unit of energy you put into the plant you get two units of energy out."
The trouble is, many of Iowa's ethanol refineries use coal - the dirtiest fuel of all.
It is one of the reasons why Iowa will soon be building another coal-fired power plant.
More than half of all the electricity produced by the new plant is expected to be used to fuel the state's ethanol refineries.
King coal
Another problem is that Iowa gets very cold in winter.
How many Americans would risk living in a place where January temperatures hover around -18F, if they had to rely on sun or wind power for heat?
What happens when the sun goes down and the wind dies?
That is why, despite the push for ethanol and wind power, coal is still king when it comes to powering Iowa.
It currently provides 85% of the state's energy needs.
Phil Wyse, a state representative for 22 years, believes Iowa and America need nuclear power.
"We need sources of power that are constant and don't rely on things like whether the wind's blowing or the sun's shining," he says.
"Alternative to coal? Nuclear more in the mix."
Despite all the wind energy and ethanol Iowa strives to produce, carbon emissions are still growing here - and they are 1% higher than the average for the whole of the US.
Iowa may have much to show the rest of America about green energy - including how hard it will be to make America energy independent.
Tadpoles may hold cancer clue
Tadpoles could hold the key to developing effective skin cancer drugs according to researchers at the University of East Anglia.
The scientists have identified a compound which blocks the movement of the pigment cells that give the tadpoles their distinctive markings.
It is the uncontrolled movement of pigment cells that causes skin cancer in both humans and frogs.
The next step, the researchers say, is to test the compound in other animals.
The man-made compound, NSC 84093, was chosen out of a list of 3,000 which were screened to see if they affected the pigment cells.
It produced a distinct change in the colour markings on the tadpoles at very low concentrations.
The continuous stripe along the back of a wild tadpole was replaced by a pattern of individual blocks of colour.
The study is published in the journal, Chemistry & Biology.
 Top tadpole has normal markings. The one underneath has broken markings along back |
Grant Wheeler, a developmental biologist and lead researcher at the University of East Anglia, said:
"Forty of the compounds gave us an interesting difference which we wanted to follow up."
"The reason we were able to look at so many compounds was because it's very easy to look at the embryos and see the colour change."
"The pigment cells are interesting for a number of reasons.
"The first is that the place where they develop is not where they end up - they move through the embryo in a process called cell migration."
Invasive melanomas
It is when melanoma cells migrate through the body to the organs and cause secondary tumours that the disease becomes deadly.
Melanomas are one of the most dangerous forms of skin cancer because they are highly invasive and resistant to treatment.
Scientists hope that if they can block this process they can halt the cancer.
The compound in this study works by inhibiting matrix metaloproteinases (MMP) which are expressed by melanoma tumours in both humans and frogs.
Mr Wheeler said a chemist at the university recognised the structure of their compound and realised that part of it had known properties that meant it should bind to a zinc molecule.
MMPs are zinc-dependant enzymes and the researchers observed varying changes to the patterning on the tadpoles according to the strength of dose they were receiving.
Mr Wheeler added: "It's a long shot. We are quite far away from a cure for melanoma."
Ed Yong, health information manager at Cancer Research UK, said:
"There is still a lot of work to do before these interesting but preliminary results can be used to benefit people affected by cancer.
"But it just goes to show that studying animals like tadpoles, which may seem unusual, could lead to potential cancer drugs in the future."
Bevis Man from the British Skin Foundation said: "This is certainly an interesting discovery and is worth keeping an eye on, but is unlikely to get a breakthrough in terms of treatment within the next ten years."
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