Time to rinse! AI assistant helps clean your teeth

FOR most of us, brushing our teeth is just a tedious part of the daily grind. But for people with dementia or learning difficulties, such tasks can be difficult. They could soon gain more independence thanks to an AI designed by Christian Peters at Bielefeld University in Germany and his colleagues.

Peters has already come up with a system that guides people when washing their hands. Brushing teeth is more complicated because it involves many steps - such as putting toothpaste on the brush, filling a glass with water or rinsing the mouth.

The TEBRA system uses a video camera to monitor someone brushing their teeth and checks that each step happens at the right time. It prompts them via a screen on the washstand if they forget a step or if they get stuck. The idea is not to dictate a routine, but to adapt to that of the user, says Peters.

TEBRA is being tested at a care home in Bielefeld for people with learning disabilities. Caregivers there reported that the system was less distracting for some people than a human carer. The work will be presented at the International Conference on Health Informatics in Barcelona, Spain, next week. Peters also plans to adapt his system to tasks such as shaving.

This article appeared in print under the headline "Time to rinse! An AI to help you clean your teeth"

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Sooty ships may be geoengineering by accident

GEOENGINEERING is being tested - albeit inadvertently - in the north Pacific. Soot from oil-burning ships is dumping about 1000 tonnes of soluble iron per year across 6 million square kilometres of ocean, new research has revealed.

Fertilising the world's oceans with iron has been controversially proposed as a way of sucking carbon dioxide out of the atmosphere to curb global warming. Some geoengineers claim releasing iron into the sea will stimulate plankton blooms, which absorb carbon, but ocean processes are complex and difficult to monitor in tests.

"Experiments suggest you change the population of algae, causing a shift from fish-dominated to jellyfish-dominated ecosystems," says Alex Baker of the University of East Anglia, UK. Such concerns led the UN Convention on Biological Diversity (CBD) to impose a moratorium on geoengineering experiments in 2010.

The annual ship deposition is much larger, if less concentrated, than the iron released in field tests carried out before the moratorium was in place. Yet because ship emissions are not intended to alter ocean chemistry, they do not violate the moratorium, says Jim Thomas of the ETC Group, a think tank that consults for the CBD. "If you intentionally drove oil-burning ships back and forth as a geoengineering experiment, that would contravene it."

The new study, by Akinori Ito of the Japan Agency for Marine-Earth Science and Technology, is the first to quantify how shipping deposits iron in parts of the ocean normally deficient in it. Earlier models had assumed that only 1 to 2 per cent of the iron contained in aerosols, including shipping emissions, is soluble in seawater, so the remaining 98 to 99 percent would sink to the bottom without affecting ocean life. But Ito found that up to 80 per cent of the iron in shipping soot is soluble (Global Biogeochemical Cycles, doi.org/kdj). As this soot rapidly falls to the sea surface, it is likely to be fertilising the oceans.

In the high-latitude north Pacific - a region that is naturally iron-poor and therefore likely to be most affected by human deposits - ship emissions now account for 70 per cent of soluble iron from human activity, with the burning of biomass and coal accounting for the rest. Shipping's share will rise as traffic continues to grow and regulations restrict coal and biomass emissions.

Can we learn anything from this unintentional experiment? Baker thinks not. "The process isn't scientifically useful," he says, because the uncontrolled nature of the iron makes it difficult to draw meaningful comparisons.

The depositions are unlikely to be harmful at current levels, he says, but "given the uncertainties, I just don't know how much these iron emissions would have to increase before there was demonstrable harm to an ecosystem, or benefit in terms of carbon uptake, for that matter".

This article appeared in print under the headline "Ships inadvertently fertilise the oceans"

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Sleep and dreaming: Why can't we stay awake 24/7?

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New map pinpoints cities to avoid as sea levels rise

See our interactive map of regional sea-level rises

SYDNEY, Tokyo and Buenos Aires watch out. These cities will experience some of the greatest sea level rises by 2100, according to one of the most comprehensive predictions to date.

Sea levels have been rising for over 100 years - not evenly, though. Several processes are at work, says Mahé Perrette of the Potsdam Institute for Climate Impact Research in Germany. Some land is sinking, some is rising. Stronger currents create slopes in sea surface, and since all things with mass exert a gravitation pull, disappearing ice sheets lead to a fall in sea levels in their surrounding areas.

Perrette has modelled all of these effects and calculated local sea level rises in 2100 for the entire planet. While the global average rise is predicted to be between 30 and 106 centimetres, he says tropical seas will rise 10 or 20 per cent more, while polar seas will see a below-average rise. Coasts around the Indian Ocean will be hard hit, as will Japan, south-east Australia and Argentina (Earth System Dynamics, doi.org/kbf).

New York's position may be less perilous than previously thought. A weakening of the Atlantic Gulf Stream will cause water to slop westwards, triggering a rapid rise on the eastern seaboard, but this will be counteracted by Greenland's weaker gravitational pull. The city is not out of the woods, though, warns Aimée Slangen of Utrecht University in the Netherlands, whose own model suggests that Antarctica could lose a lot of ice, which would produce an above-average rise throughout the northern hemisphere.

For now, Perrette offers a warning to tropical countries. "You may have 120 centimetres of sea level rise on your coastline," he says. "Build defences."

This article appeared in print under the headline "Where not to be when seas rise up to meet us"

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Sleep and dreaming: Slumber at the flick of a switch

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New 17-million-digit monster is largest known prime

The largest known prime number has just shot up to 2^57,885,161 - 1, breaking a four-year dry spell in the search for new, ever-larger primes.

Curtis Cooper at the University of Central Missouri in Warrensburg made the find as part of the Great Internet Mersenne Prime Search (GIMPS), a distributed computing project designed to hunt for a particular kind of prime number first identified in the 17th century.

All prime numbers can only be divided by themselves and 1. The rare Mersenne primes all have the form 2^p - 1, where p is itself a prime number.

The new prime, which has over 17 million digits, is only the 48th Mersenne prime ever found and the 14th discovered by GIMPS. The previous record holder, 2^43,112,609 - 1, which was also found by GIMPS in 2008, has just under 13 million digits. All of the top 10 largest known primes are Mersenne primes discovered by GIMPS.

Volunteer sifters

Though there are an infinite number of primes, there is no formula for generating these numbers, so discovering them requires intensive computation. GIMPS uses volunteers' computers to sift through each prime-number candidate in turn, until eventually one lucky user discovers a new prime.

Cooper runs GIMPS software on around a thousand university computers, one of which spent 39 days straight proving that the number was prime. This was then independently verified by other researchers.

Though there is little mathematical value to finding a single new prime, these rare numbers are prized in their own right by some. "It's sort of like finding a diamond," says Chris Caldwell at the University of Tennessee, Martin, who keeps a record of the largest known primes. "For some reason people decide they like diamonds and so they have a value. People like these large primes and so they also have a value."

Prime-hunting isn't a completely esoteric pastime though, as these numbers underpin the cryptographic techniques used to make online transactions secure.

Prizes for primes

The Electronic Frontier Foundation, an internet civil liberties group, is offering prizes of $150,000 and $250,000 to the discovery of the first prime with at least 100 million and a billion digits, respectively. Previous prizes for primes 1 million and 10 million digits long have already been awarded.

Cooper will receive a $3000 prize from GIMPS for making the discovery.

Don't expect to see the next largest prime any time soon though. The problem becomes harder over time, as larger primes are both more rare and harder to check. "Those two things work together to spread them out as time goes on," says Caldwell.

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Lefty nonsense: When progressives wage war on reason

Conservatives rightly get a bad rap for anti-science policies. But progressives can be just as bad, say Alex Berezow and Hank Campbell

Editorial: "Challenge unscientific thinking, whatever its source"

IN 2007, fresh off an election victory in both chambers of Congress, the Democratic party set out to fulfil its campaign promise to make the US more sustainable - starting with the building they had just gained control of.

With their "Green the Capitol" initiative, the Democrats planned to make the building a model of sustainability and an example to us all. They replaced light bulbs and bathroom fixtures, but perhaps most significantly, they took the step of greening the congressional cafeteria. Cost was no object. Good thing, too.

The problem, as they saw it, was an excessive reliance on environmentally wasteful styrofoam containers and plastic utensils. And so they issued a decree: from now on, the cafeteria would use biodegradable containers and utensils.

They claimed science was on their side: the utensils could be composted, and would thus be better for the environment. The result was a miracle of sustainability, at least according to internal reports, which claimed to have kept 650 tonnes of waste out of landfill between 2007 and 2010.

The only problem was that the "green" replacements were worse for the environment. The spoons melted in soup, so people had to use more than one to get through lunch. The knives could barely cut butter without breaking. And instead of composting easily, they had to be processed in a special pulper and then driven to Maryland in giant trucks.

In 2010 an independent analysis found that the saving was equivalent to removing a single car from the road - at a cost of $475,000 per year. Wary of disappointing their environmentally concerned supporters, Democrats waited until the Republicans regained control of the House of Representatives in 2011 - and then suggested that the programme be killed. Republicans duly instructed the cafeteria to revert to using utensils and containers that actually worked.

Deposed Democrat speaker Nancy Pelosi saw an opportunity, and took it: "GOP brings back Styrofoam & ends composting - House will send 535 more tons to landfills," she tweeted.

Did progressives call her to account? No, but they should have. According to the Democrats' own figures their programme only saved about 200 tonnes of waste per year. Where did Pelosi get 535 tonnes from?

This anecdote is both illuminating and chilling: if an environmental story is being told about people on the right of the political spectrum, anything goes. But if progressives play fast and loose with the facts, they are given a free ride.

Conservatives' sins against science - objections to stem cell research, denial of climate science, opposition to evolution and the rest - are widely reported and well known. But conservatives don't have a monopoly on unscientific policies. Progressives are just as bad, if not worse. Their ideology is riddled with anti-scientific feel-good fallacies designed to win hearts, not minds. Just like biodegradeable spoons, their policies often crumble in the face of reality and leave behind a big mess. Worse, anyone who questions them is condemned as anti-science.

We have all heard about the Republican war on science; we want to draw attention to the progressive war on reason.

We recognise that the term "progressive" is potentially troublesome, so let us lay our cards on the table. In the US, "progressive" and "liberal" are often used interchangeably. But the two should not be confused.

Liberalism, as defined by John Locke, means the pursuit of liberty. By that definition progressives are not liberal. Though they claim common cause with liberals (and most of them are Democrats because very few progressives are Republican), today's progressive movement is actually socially authoritarian.

Unlike conservative authoritarians, however, they are not concerned with banning "immoral" things like sex, drugs and rock and roll. They instead seek dominion over issues such as food, the environment and education. And they claim that their policies are based on science, even when they are not.

For example, progressive activists have championed the anti-vaccine movement, confusing parents and causing a public health disaster. They have campaigned against animal research even when it remains necessary, in some cases committing violence against scientists. Instead of embracing technological progress, such as genetically modified crops, progressives have spread fear and misinformation. They have waged war against academics who question their ideology, and they are opposed to sensible reforms in science education.

We do not want not to demonise all progressives. Some are genuinely pro-science. We recognise the huge value some progressive ideas have had, and that vilifying an entire philosophy based on the actions of its radical ideologues would be unfair.

But we do want to demonise the lunatic fringe. We contend that there is a disturbing and largely unreported trend among influential progressive activists who misinterpret, misrepresent and abuse science to advance their ideological and political agendas.

Of all of today's political philosophies, progressivism stands as the most pressing problem for science. Progressives, not conservatives, are the ones most likely to replace scientific research with unscientific ideology.

Conservatives who endorse unscientific ideas are blasted by the scientific community, yet progressives who do the same get a free pass. It is important the problem be recognised, and that free pass revoked.

This article appeared in print under the headline "Science left out"

Alex Berezow is editor of RealClearScience.com

Hank Campbell is founder of Science 2.0. Berezow and Campbell are authors of Science Left Behind: Feel-good fallacies and the rise of the anti-scientific left (PublicAffairs, 2012)

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Sneaky ninja robot silently stalks its prey

MOVE over David Attenborough. A robot that moves only when it won't be seen or heard might make it easier to sneak up on animals and film them in the wild.

Defence labs have built robots that track people through cities, avoiding well-lit areas. But cities are noisy, so if a robot keeps a certain distance it's unlikely to be heard. Tracking and filming animals in the wild is tougher because they often have keen hearing and the environment is usually quieter. Matthew Dunbabin and his collaborator Ashley Tewes at the CSIRO Autonomous Systems Laboratory in Brisbane, Australia, are teaching a four-wheeled robot to move only when intermittent sounds - like bird or frog calls - will mask its movements.

In tests, the robot picked up the sounds of things like fork-lifts, cellphones and birds, and was able to predict whether they were likely to persist long enough to cover its movement. The robot can also identify its own noise, and guess how it will vary at different speeds and turning angles - calculating what this will sound like to a target up to 50 metres away.

With the help of a camera, laser scanner and the right algorithm, the robot can figure out which vantage points will provide the best cover so it can skulk in the shadows.

This article appeared in print under the headline "Sneaky ninja robot silently films its prey"

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Two worms, same brains – but one eats the other

IF TWO animals have identical brain cells, how different can they really be? Extremely. Two worm species have exactly the same set of neurons, but extensive rewiring allows them to lead completely different lives.

Ralf Sommer of the Max Planck Institute for Developmental Biology in Tübingen, Germany, and colleagues compared Caenorhabditis elegans, which eats bacteria, with Pristionchus pacificus, which hunts other worms. Both have a cluster of 20 neurons to control their foregut.

Sommer found that the clusters were identical. "These species are separated by 200 to 300 million years, but have the same cells," he says. P. pacificus, however, has denser connections than C. elegans, with neural signals passing through many more cells before reaching the muscles (Cell, doi.org/kbh). This suggests that P. pacificus is performing more complex motor functions, says Detlev Arendt of the European Molecular Biology Laboratory in Heidelberg, Germany.

Arendt thinks predators were the first animals to evolve complex brains, to find and catch moving prey. He suggests their brains had flexible wiring, enabling them to swap from plant-eating to hunting.

This article appeared in print under the headline "Identical brains, but one eats the other"

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Fishy origin of remora's shark-sucking hat

Julia Sklar, reporter

(Image: Dave Johnson)

This spectacular headpiece isn't the latest head-turning
fashion in hats. Instead, this remora is sporting the feature that gives the fish its
nickname, "sharksucker": a sucking disc on top of its head, allowing it to
benignly attach itself to other sea creatures.

The disc's ribbed appearance gives a clue to its intriguing
origin: the sucker develops from the same larval
bones that grow into dorsal fins in other species, despite their drastically
different shapes on the adult fish.

By using a red dye to stain the bones of larval remoras, researchers were able to track the
growth of what would become the sucking disc. At the same time, they followed
the development of dorsal bones in a different kind of fish. They noticed that the
dorsal fins and sucking discs developed in exactly the same way in both animals,
up to a certain point.  

The pivotal moment comes when the bones of the remora's dorsal
fin begin to expand and inch forward, towards the head.  By the time the fish is 30 millimetres long,
the dorsal fin bones have become a fully formed sucking disc about 2 millimetres
long. Inside, the sucker keeps many structures in common with a dorsal fin, with
minuscule fin spines and supporting bones. However, the remora's bones underpin
movable slats that open and close to create suction.

Ralf
Britz of the Natural History Museum in London, who worked on the study, said the sucker reminded him of Linnaeus's observation of nature's
magnificent ability to recycle
useful parts.

"What keeps impressing me when I study the development of
some of the weirdest structures in the fish world is that natura non facit saltus, "nature does not make jumps", and even the
strangest anatomical modifications happen through small gradual changes in
development," Britz says.

In 2006, Britz was a member of the team that discovered the
world's smallest vertebrate, the Sumatran fish Paedocypris progenetica, which also flaunts
an unusual gripping fin.

Journal reference: Journal of Morphology, DOI: 10.1002/jmor.20105

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Fluorescent protein lets us read a fish's thoughts

The zebrafish spots its lunch. What goes through its brain? Now, for the first time, we can see exactly what it is thinking, thanks to a new way of studying single neurons that lets researchers track patterns of brain activity in a live animal.

A standard way to achieve detailed imaging of cellular activity is by genetically altering cells to express green fluorescent proteins (GFPs) which light up when calcium concentrations rise – such as occurs when neurons are activated.

To try to see activity in individual neurons, Koichi Kawakami at the National Institute of Genetics in Shizuoka, Japan, and colleagues created a super-sensitive GFP and tested it in zebrafish larvae between four and seven days old, when they are transparent.

The researchers focused on capturing activity in the zebrafish's tectum – a region of the brain that processes vision. They set up an LCD screen that displayed a blinking dot to one side of an immobilised zebrafish larva. As the dot appeared and disappeared, they saw corresponding flashes of light from the tectum, reflecting neural activity.

When the team moved the dot from left to right and top to bottom, they saw horizontal and vertical movement of brain signals in the tectum, revealing what is known as the visuotopic map. Visual information from each eye is processed in the opposite hemisphere of the brain, so movement seen by the right eye was replicated in the left side of the tectum and vice versa.

Magnification factor

The difference in scale between the brain map and the actual movement showed that the magnification factor was larger in the vertical direction than the horizontal, but why this should be is unclear. "I think fish eyes and our eyes could be better at finding differences in height rather than those in the horizontal direction," says Kawakami. "It's an interesting question."

The team then introduced a live paramecium – a tiny single-celled organism eaten by zebrafish – near the larva's head. There was no response when the paramecium was motionless, but when it started swimming, signals in the zebrafish brain matched the movement of its prey.

Finally, the team observed brain signals while the zebrafish larva and prey both swam freely. Just before the larva caught its prey, the signals converged in the front of the tectum, suggesting that activation of this area could be connected with subsequent activation of the larva's motor pathways.

"This is very exciting work," says Martha Constantine-Paton, who studies brain development at the Massachusetts Institute of Technology. She hopes that it will soon be possible to watch how neural circuits grow as a zebrafish matures.

That will be the next big hurdle, she says, and since the fish are only transparent as larvae, it would require a cranial window or especially sensitive optical reagents. But we might not be far off. "The sensitivity resolution of this new green fluorescent protein is amazing," she says.

Kawakami and colleagues are now attempting to observe activity across the whole brain. "We will explore neurons that work while the fish learns and thinks," he says. "This will lead to an understanding of the fundamental neuronal circuits at work during human thought."

Journal reference: Current Biology, DOI: 10.1016/j.cub.2012.12.040

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Minimum booze price will rein in alcohol abuse

Binge drinking and preloading – drinking cheap shop-bought alcohol before going to a bar – are two behaviours the UK government hopes to curb by imposing a minimum price for alcohol. A 10-week consultation period for the policy, which could see a ban on alcohol being sold at less than 45 pence per unit in England and Wales, ends on 6 February. Meanwhile, Scotland is considering a minimum of 50 pence. But will the policy succeed in tackling alcohol overconsumption and its consequences?

"There's a huge amount of evidence that pricing is linked to consumption," says John Holmes at the University of Sheffield, UK, whose research into the link between alcohol pricing and public health was used by the government in framing the proposed pricing policy.

The government hopes that the impact of a minimum price will be felt mainly by those who drink more than is recommended, since they tend to drink cheaper alcohol. In the UK, the recommended limits are 21 units for a man and 14 units for a woman, per week. A unit is equivalent to 10 millilitres of pure alcohol.

The government claims that the policy could lead to a 3.3 per cent fall in consumption across all alcoholic drinks. This will in turn lead to at least 5200 fewer crimes, 24,600 fewer alcohol-related hospital admissions and over 700 fewer alcohol-related deaths per year after 10 years, it says.

Holmes and his colleagues used spending data from 9000 UK households to model how different demographics respond to price changes. The model shows that a minimum price of 35 pence per unit would lead to a significant cut in the amount that people drink. For "hazardous drinkers" – men who drink over 50 units and women who drink over 35 units a week – a 40 pence minimum price would reduce consumption by 4 per cent; 60 pence would reduce it by 16 per cent.

The team also used epidemiological evidence to link consumption with risk of harm. "The specific numbers can be debated, but most would agree that lower consumption generally leads to lower rates of harm," says Holmes. He estimates that reductions in public health costs and crime resulting from the new policy could lead to savings of about £4 billion over 10 years. However, the policy will not help people with an alcohol dependency, he says, since they are likely to buy alcohol even at higher prices.

Canadian backing

Holmes's model is backed by evidence from Canada, which has set a minimum price for alcoholic drinks in British Columbia and Saskatchewan on several occasions – most recently in 2010. Tim Stockwell at the University of Victoria in British Columbia and colleagues looked at data from both provinces over a 20-year period. On average, there was a 3.4 per cent fall in total alcohol consumption across the population for every 10 per cent increase in minimum price.

In Canada, the immediate effects of a higher minimum price included fewer acute hospital admissions and fewer deaths caused solely by alcohol, such as alcoholic gastritis. After two to four years there were also fewer cases of alcohol-related diseases.

The pricing model in Canada is not the same as that proposed for the UK. Rather than setting a minimum price per unit of alcohol, the Canadian policy sets prices for each type of alcoholic drink.

Stockwell thinks the UK's approach is preferable, since it takes the strength of the drink into account. "In my opinion, the model being proposed in the UK is perfect from the public health and safety point of view."

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Drug reduces enlarged prostate with few side effects

Relief from the constant call of nature is the aim of a new drug, tested in rats, which can shrink an enlarged prostate and is likely to have few side effects.

By the age of 60 an estimated 70 per cent of men have prostate enlargement. Treatment involves surgery or drugs that block testosterone, a hormone that drives unwanted growth. Side effects can include loss of libido and erectile dysfunction.

The new drug, RC-3940-II, developed by Andrew Schally of the Miami Veterans Affairs Medical Center in Florida and colleagues works by blocking gastrin-releasing peptide – another potent growth factor.

In rats, a six-week treatment shrank prostates by 18 per cent. It also shrank human prostate cells by 21 per cent. Importantly, fewer side effects are likely as testosterone pathways are avoided.

Journal reference: PNAS, DOI: 10.1073/pnas.1222355110

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First video reveals working tractor beam in action

Sandrine Ceurstemont, editor, New Scientist TV

A working tractor beam has now been caught on video, showing how light can pull objects - on a microscopic scale.

While it's well known that light can push objects as they follow the flow of photons, attracting them isn't as simple. By shining a laser through a lens and mirror set-up, Tomas Cizmar from the University of St Andrews in the UK and colleagues were able to reverse the effect, thanks to the interference pattern of reflected beams. Their technique works both in liquids and in a vacuum.

In this video, the first clip shows how the system can be used to separate objects of different sizes. When a tractor beam in the centre of a mixture of particles is turned on, large spheres move left towards the light, while smaller ones are pushed to the right. 

A second clip shows how the beam can pull a collection of particles. "When the right configuration of particles occurs the tractor beam makes it stable and the whole structure moves against the tractor beam," says Cizmar.

The technique has medical applications: by targeting and attracting certain types of cells, it could, for example, help sort components of blood samples. Another recent tractor beam system attracted NASA's attention as a way of collecting dust or atmosphere samples on space missions.

If you enjoyed this post, watch how light can create instant origami or see how to play a tiny game of Tetris with a laser.

Journal reference: Nature Photonics, DOI: 10.1038/nphoton.2012.332

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DNA privacy: don't flatter yourself

The secrets contained in our individual genomes are less valuable than we like to believe

IMAGINE donating your DNA to a project aimed at discovering links between genes and diseases. You consent to your genome sequence being released anonymously into the public domain, though you are warned there is a remote possibility that it might one day be possible to link it back to you.

A few years later, that remote possibility comes to pass. How should you feel? This is no longer a hypothetical scenario. About 50 people who participated in a project called 1000 Genomes have been traced (see "Matching names to genes: the end of genetic privacy?").

The researchers' intentions were honourable. They have not revealed these identities, and the original data has been adjusted to make a repeat using the same technique impossible. All they wanted to do was expose privacy issues.

Consider them exposed. It is clear that genomics has entered a new phase, similar to that which social media went through a few years ago, when concerns were raised about people giving away too much personal information.

What happens when the same applies to our DNA? Having your genome open to public scrutiny obviously raises privacy issues. Employers and insurers may be interested. Embarrassing family secrets may be exposed.

But overall, personal genetic information is probably no more revealing than other sorts. In fact there are reasons to believe that it is less so: would an insurance company really go to the trouble of decoding a genome to discover a slightly elevated risk of cancer or Alzheimer's disease?

The available evidence suggests not. In 2006, Harvard University set out to sequence the genomes of 100,000 volunteers and make them publicly available, along with personal information such as names and medical records. One of the goals was to see what happens when such data is open to all. The answer seems to be "not a lot". So far this Personal Genome Project has published 148 people's full genomes. Not one volunteer has reported a privacy issue.

This is not a reason for complacency, but it suggests that our genomic secrets are less interesting to other people than we might like to believe.

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Get cirrus in the fight against climate change

FEATHERY cirrus clouds are beautiful, but when it comes to climate change, they are the enemy. Found at high-altitude and made of small ice crystals, they trap heat - so more cirrus means a warmer world. Now it seems that, by destroying cirrus, we could reverse all the warming Earth has experienced so far.

In 2009, David Mitchell of the Desert Research Institute in Reno, Nevada, proposed a radical way to stop climate change: get rid of some cirrus. Now Trude Storelvmo of Yale University and colleagues have used a climate model to test the idea.

Storelvmo added powdered bismuth triiodide into the model's troposphere, the layer of the atmosphere in which these clouds form. Ice crystals grew around these particles and expanded, eventually falling out of the sky, reducing cirrus coverage. Without the particles, the ice crystals remained small and stayed up high for longer.

The technique, done on a global scale, created a powerful cooling effect, enough to counteract the 0.8 °C of warming caused by all the greenhouse gases released by humans (Geophysical Research Letters, DOI: 10.1002/grl.50122).

But too much bismuth triiodide made the ice crystals shrink, so cirrus clouds lasted longer. "If you get the concentrations wrong, you could get the opposite of what you want," says Storelvmo. And, like other schemes for geoengineering, side effects are likely - changes in the jet stream, say.

Different model assumptions give different "safe" amounts of bismuth triiodide, says Tim Lenton of the University of Exeter, UK. "Do we really know the system well enough to be confident of being in the safe zone?" he asks. "You wouldn't want to touch this until you knew."

Mitchell says seeding would take 140 tonnes of bismuth triiodide every year, which by itself would cost $19 million.

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Dung beetles navigate using the Milky Way

Ever look up at the stars and wonder if some bug-eyed creature is doing the same? It turns out at least one does: the dung beetle uses the glow of the Milky Way to navigate.

Once a beetle (Scarabaeus satyrus) has constructed its dung ball, it moves off in a straight line in order to escape from rival beetles as quickly as possible, lest they try and steal its carefully crafted ball. This behaviour doesn't sound complicated, but several years ago, Marie Dacke of Lund University in Sweden and colleagues showed that polarised light from the moon is important for dung beetles to keep to a straight line.

Then the researchers were surprised to find the insects were able to stay on course even on a moonless night. "We thought there was something wrong in our set-up," Dacke says.

The team allowed the beetles to crawl around the floor of a plain-walled cylindrical drum with an open top, meaning they could only use the night sky to orientate themselves. The researchers timed how long it took the beetles to reach the edge of the drum from the centre, and found that under a full moon, the insects took around 20 seconds on average; on a starry but moonless night, they took around 40 seconds.

But when beetles had a cardboard cap placed on them to prevent them from seeing the sky, they needed over two minutes, suggesting the stars were playing a role.

Planetarium clincher

To test this, the team moved the experiment to a planetarium. By switching stars on and off, Dacke discovered that the glowing strip of the whole Milky Way was what guided the beetles' movement. "Before it was assumed insects could not use the stars because their eyes don't have the resolution to see them," she says. Navigating using the whole of the Milky Way does away with the need to see individual stars.

Dacke says the results suggest moths, locusts and other insects might navigate by the Milky Way, too. Her team is now looking at whether the beetles prefer to navigate by the moon or the Milky Way when both are on view.

Journal reference: Current Biology, doi.org/kbm

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The real lesson from the bird flu storm

The controversy over whether work on airborne H5N1 bird flu can be published shows that transparency is vital to upholding public trust

So the research moratorium on H5N1 bird flu is over. In 2011 I was one of the first journalists to report the discovery that H5N1 bird flu, which is highly lethal in humans, can mutate to become readily transmissible not just in birds but also in mammals like us – while, apparently, remaining lethal.

What happened next shocked the researchers. Publication of the work was blocked, as US biosecurity experts insisted it would be crazy to tell would-be bioterrorists about this. The 39 labs around the world that do this research responded by declaring a moratorium on further work: there's little point doing research you can't publish.

A year later, the US will shortly launch a new review process to address this. This week, the labs said they would soon resume work on whether, and how, a virus now evolving across Eurasia might become an apocalyptic threat to humanity.

This resumption is good news – but there's a proviso. Hypothetical bioterrorists aside, the real worry for many critics is the danger posed by research itself. We don't want labs to inadvertently release the virus we fear.

That doesn't just require stringent containment and more bureaucracy – it means doing experiments only when benefits really outweigh risks. If, as seems likely, all parties involved cannot agree on that, then the whole process should at least be as transparent as possible. Top research officials in the US have been saying this, and that too is good.

Alarming spin

But are researchers as committed to transparency? The H5N1 kerfuffle has been notable for an alarming amount of spin. Details of the findings have been reinterpreted as pressures have mounted. The experience may have left some researchers even less likely to tell us what they're doing.

The story emerged at a flu meeting in Malta in September 2011. Ron Fouchier of the Erasmus Medical Center in Rotterdam reported that he had made H5N1 able to spread between ferrets via airborne droplets, by simply passing it repeatedly between the animals.

This was the $64,000 question in flu research. At present, H5N1 cannot become a human pandemic as it does not spread this way in mammals. But can it evolve this ability? Some virologists said no. Others said it might, but the mutant would not be as lethal.

No such luck. "All the ferrets died," Fouchier told me. "We have to do more to control H5N1." He was clearly upset at the prospect of such a virus evolving naturally; so were other flu researchers at the meeting. I reported it

Fouchier had left out a lot of detail as the research had been submitted to the journal Science, which doesn't allow authors to say much before publication. When he said the ferrets all died, I thought he was referring to the ones that inhaled the virus. In fact those ferrets lived; the ones that died had had that same virus put into their windpipe.

We would have corrected the article had the researchers complained. Maybe it seemed a minor point: the team had also reported that putting a flu virus in a ferret's windpipe was the best test of its danger to humans. The transmissible virus killed in a way that might be relevant to people – that's what mattered. The detail wouldn't have changed our conclusion.

Dangerous or not?

But then the dispute over whether the work could be published blew up, and The New York Times charged that this research was just too dangerous.

In February last year, the researchers' story had changed dramatically. The press had blown things out of proportion. The mutant virus wasn't dangerous. None of the ferrets that inhaled it died, you had to practically shove it into their lungs to kill them. Anyway, animal work doesn't show what will happen in people.

Efforts to portray the transmissible virus as harmless were almost comical. One researcher told me the mutant H5N1 was no biggie – even the 2009 pandemic flu kills in ferrets' tracheas. Ah, but only one in three – the H5N1 killed them all, so not quite the same.

When the research was finally published, none of the spin seemed very relevant. The message of Malta remained: H5N1 became airborne in mammals, and could still kill. That's enough. Yes, this is animal work: if a virus that kills in a ferret's throat, but not in its nose, emerges in nature, we may get lucky. Or maybe we'd best not inhale.

Full transparency

Some defensiveness is understandable if scientists fear work they rightly consider vitally important may be banned. Yet full transparency is the answer. I fear that lesson has not sunk in. After the papers were published, one of the researchers insisted to me that there was no reason why he should ever talk to a journalist; this week that person begged journalists to tell the public the researchers' side of the story, so they wouldn't get this kind of opposition.

That's not how it's done. Transparency is an important safeguard against some who may take excessive risks (it happens) as well as showing the good that scientists do. It must serve both these functions, or no one will believe the good news.

I gave a talk in Malta too, about public communication. I told a roomful of flu researchers the old risk-management saying: strive to be, not trusted, but accountable. I got a lot of blank, angry stares.

This problem won't go away until that gets rueful, knowing nods. It isn't happening yet.

Debora MacKenzie is a consultant for New Scientist based in Brussels

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Can we really 'cure' autism?

Some claim that new research shows people can grow out of autism, but it is more likely that they simply cope better with the condition over time

The New York Times has pointed to an intriguing study ostensibly showing that some small percentage of people with autism can "outgrow" their symptoms. The story was oddly unsatisfying, claiming in one paragraph that the study, published in The Journal of Child Psychology and Psychiatry, will alter the way parents "think and talk about autism" but also cautioning against false hope.

The writer seems only dimly aware how this half-hearted message will set off a bomb in the world where Jenny McCarthy lives – that she will turn on that wicked grin and brandish this study to launch another 40 years of vicious debate over whether autism is caused by environmental factors, namely vaccines, and thus can be cured by brave and dedicated parents like her, or whether it's just a condition people are born with.

Thankfully, science writer Emily Willingham has parsed through the study in Forbes to show us what it really finds, which is not much that's new and certainly nothing that will change our thinking about the progress of autism or make us believe in the McCarthy miracle cure. As Willingham points out, the people who seem to have "grown out" of their autism had higher cognitive functioning and milder symptoms in the first place, and "many of them had behavioral interventions in childhood".

One measure the researchers used to evaluate progress was "typically developing friends", which people with autism sometimes have anyway. Seven of the 34 had some impairment in "non verbal social interactions" which the researchers decided, somewhat arbitrarily, was due to other factors such as anxiety or depression.

Anyone who has read a single memoir by someone with Asperger's or known someone well with the condition can intuit what's going on. At the moment, I happen to be reading Look Me in the Eye: My life with Asperger's by John Elder Robison. Over the course of his life, Robison learns to compensate for his social limitations. As a child he teaches himself to say appropriate things to children and not just foist on them his own obsessive interests. As an adult he learns that blurting out the truth – "you look fatter" – is not always the right thing to do.

Working around autism

He doesn't "outgrow" his autism, he just learns to work around it. Even later in his life he writes that he wishes his disability were more obvious; when we see someone in a wheelchair we know they can't walk, so we help them across the street. There is no way to "see" Asperger's so people just assume he's a jerk.

Willingham makes the comparison to diabetes, which I have. I have learned how to control my blood sugar pretty well, but I still have diabetes. Autism for high-functioning kids works something like that, even more so these days.

When Robison was a kid, no one understood him at all. They just thought he was odd and would grow up to be a failure. But now there is a well-developed understanding of Asperger's and its symptoms, and many behavioural therapies that can help people, especially if they are smart enough to absorb them. So it stands to reason that as time goes on, more people with Asperger's or autism will look, to all the world, as if they are "cured" without actually being so.

This article originally appeared in Slate. Hanna Rosin is the author of The End of Men and a co-founder of Slate's Double X

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