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What actually IS angular momentum?

When we talk about physics, boiling it right down to its most basic principles, we’re really just talking about the motion of the stuff around our Universe. For some objects, this is simple – some move that way, and others move the other way. But what about objects that move without moving? Or, put another way, what about objects that move, but that movement doesn’t really take them anywhere, such as a planet around a star, an electron around an atom, and our Solar System going around the gravitational centre of the Milky Way?

So we’ve got plain old ‘momentum’, which is mass x velocity, and the ‘oomph’ an object has when it’s going in a straight line; and then we’ve got ‘angular momentum’, “which is a way to explain how much oomph objects have when they’re going in circles, figuratively or literally,” says Henry in the latest episode of MinutePhysics.

The reason we care about angular momentum, he says, is that if you take a bunch of objects that are interacting, for example the Earth orbiting the Sun, you can add up all their angular momenta into one number (don’t worry, Henry shows you how to do this in the video above), and then that total value won’t change over time. It’s a constant. Unless of course, something comes in from outside to mess with the system, but you get the idea.

And here’s where it gets mind-blowing. Imagine if we looked at the Earth rotating around the Sun, calculated its angular momentum, and then suddenly took away the Sun and the rest of the Solar System. Turns out, the Earth would still have that same angular momentum about the point where the Sun was, says Henry. Of course, in the absense of the Sun’s major gravitational pull, the Earth would now be moving in a straight line, but if you calculate its angular momentum, you’re going to end up with the exact same figure that you calculated when the Earth was rotating around the Sun! Via ScienceAlert.

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Newly discovered ‘Super Saturn’ has colossal ring system

This is the first planetary ring system discovered outside the Solar System, and it’s got a diameter roughly 200 times larger than Saturn’s. Astronomers have found a planetary ring system with such enormous proportions, it makes Saturn’s rings look puny. The rings have formed around a young, giant exoplanet called J1407b, and they’re the first of their kind to be found outside our Solar System.

The rings were first discovered in 2012, thanks to a team led by Eric Mamajek from the University of Rochester in the US, but back then, they had no way of knowing just how big they were. They’ve since teamed up with researchers led by Matthew Kenworthy at Leiden Observatory in the Netherlands to analyse 30 individual J1407b rings to finally realise the true scale of these concentric beauties.

Turns out, each ring is tens of millions of kilometres in diameter, and the gaps between them suggest that whole satellites – or ‘exomoons’ – have formed there, just like the many tiny ’shepherd’ moons of Saturn, such as Pan and Daphnis, that continue to orbit it. The diameter of the whole system is about 120 million kilometres wide.

“This planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn’s rings are today,” said Mamajek in a university press release. “You could think of it as kind of a super Saturn.” Via ScienceAlert.

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Prof Raymond Tallis to challenge Stephen Hawking claim that “philosophy is dead”

Leading polymath Prof Raymond Tallis is set to use a Birmingham pub to challenge Stephen Hawking’s declaration that “philosophy is dead”. In a meeting of the Birmingham Salon at the Victoria in John Bright Street, Prof Tallis will discuss ‘Has physics destroyed philosophy?’

To do so, he will use a prepared set of notes with slides – before taking questions and answers. “I like to set out a case and not miss the steps,” said the Manchester-based retired medic who specialised in the neuroscience of strokes and epilepsy while becoming a renowned philosopher, poet, novelist and cultural critic.

Married for 42 years and a father of two, Prof Tallis said: “Hawking said ‘philosophy is now dead… because it hasn’t kept up with physics’. “But, although science is our greatest cognitive achievement, it can never explain consciousness and it will never tell us what it is like to be a human being.” Edited from an article in the Birmingham Post.

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Building the world’s tallest lift for the world’s tallest building

By the end of this decade the records for the world’s tallest building and highest lift are going to be broken. It has been estimated it will cost $1.2bn to build Saudi Arabia’s Kingdom Tower But this is more meaningful than just another skyscraper, in another place, that most of us will never set eyes on. This could change architecture as we know it.

There are some things most of us just don’t think about. Stepping into a lift and wondering how many floors it could travel may seem too much of a challenge to be worthwhile. Lift-maker Kone has spent many years considering this problem though.

“While elevators have enabled the rise of city skylines, the technology had reached its height limit,” explains its director of high rise technology, Santeri Suoranta. “Elevators travelling distances of more than 500m [1,640 ft] were not feasible as the weight of the [steel] ropes themselves become so large that more ropes were needed to carry the ropes themselves.”

ultra rope koneBut the company’s quest for a solution has borne fruit. After nine years of rigorous testing, it has released Ultrarope – a material composed of carbon-fibre covered in a friction-proof coating. It weighs a seventh of the steel cables, so is more energy efficient, has twice the lifespan, and most notably, it makes lifts of up to 1km (0.6 miles) in height a lot easier to build.

Other lift manufacturers, like Toshiba, Mitsubishi, Otis, Schindler, et al, have been raising their game too. They’ve been battling on in the contest to create more eco-friendly, less expensive to run, easier to install, taller and/or faster lifts. But Kone’s creation was chosen to be installed in what’s destined to become the world’s tallest building. When completed in 2020, The Kingdom Tower, in Jeddah, Saudi Arabia will stand a full kilometre in height, and will boast the world’s tallest lift at 660m (2,165ft). Edited from Lift me higher: Building the world’s tallest lift.

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Smart doorbell turns your phone into an intercom

doorbellThe idea of a smart doorbell seems plain ridiculous on paper. But when we actually checked out with German company Doorbird’s new device, we got it instantly. When someone prods your button, Doorbird sends an alert to your iOS or Android phone. Tapping that notification opens the app, which then gives you a high definition image of whoever’s stood on your doorstep.

This basically has the effect of turning your phone into a long-distance intercom – you can chat with the postie and even let them into your home or office if you’re away. Our demo guy told us that might be handy if a delivery guy wants to drop off a package, but we were a little concerned about granting a total stranger unsupervised access to our home. You’d want to pair this up with something like Netatmo’s Welcome or Manything for continued supervision.

Doorbird says that you can hook up to another webcam so you can see what they get up to directly through the Doorbird app. No word yet on whether Doorbird is getting into bed with Apple HomeKit or Samsung SmartHome, which could make webcam integration easier. With extra features such as an IR motion detector and full visitor history, the Doorbird is a nifty little device that could be great for families, especially if you don’t have a spare set of keys for visiting relatives. If anything, it’s a little on the big and bulky side, lacking the metallic finesse promised by Schlage’s Siri-compliant smart locks and Kwikset’s Bluetooth-powered Kevo. Hopefully future versions of the Doorbird will feature some sexier looks to complement its great functionality. Via Doorbird’s smart doorbell turns your phone into an intercom.

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The Real Railgun of the U.S. Navy

Railguns: weapons that can tear through walls like a pencil punctures a balloon. If you thought lasers were going to change the game, rail guns are going to blast the doors wide open.

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Scientists slow the speed of light

Thanks to Jacki Thomas for suggesting this post.

A team of Scottish scientists has made light travel slower than the speed of light. They sent photons – individual particles of light – through a special mask. It changed the photons’ shape – and slowed them to less than light speed.The photons remained travelling at the lower speed even when they returned to free space. The experiment is likely to alter how science looks at light. The collaborators – from Glasgow and Heriot-Watt universities – are members of the Scottish Universities Physics Alliance. They have published their results in the journal Science Express.

The speed of light is regarded as an absolute. It is 186,282 miles per second in free space. Light propagates more slowly when passing through materials like water or glass but goes back to its higher velocity as soon as it returns to free space again. Or at least it did until now. Two and a half years ago, the experimenters set out to see if they could slow down light just a little – and keep it moving more slowly. In a laboratory at Glasgow university, Dr Jacquiline Romero, Dr Daniel Giovannini and colleagues built what amounts to a racetrack for photons, the individual particles of light.

Photon race – Then they raced them in pairs. One photon they left in its normal state. The other photon was sent through a special mask. The mask forced the photon to change its shape and travel slower than the speed of light. Dr Romero explains: “After the mask, the photon is launched into a sort of racetrack about a metre in length.

“Then we take the time in which the unshaped photon finishes the racetrack, and the shaped photon’s time as well, and then compare the two times.” If they had both been travelling at the speed of light it would have been a dead heat. But the re-shaped photon came in second. Not by much – a few millionths of a metre – but it showed that it had not just been slowed by the mask, but had continued to travel at less than light speed even after it had returned to free space. Light travelling at less than the speed of light. Whose bright idea was that? Edited from Scientists slow the speed of light.

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Featured Artworks – Lady with a Ferret – Leonardo da Vinci

Alan Mason tells us all about the lady with a ferret (or ermine) by Leonardo da Vinci


Leonardo da Vinci is famous for a single female portrait, “La Gioconda” (The Smiling One) also known as “The Mona Lisa”, but he painted just three other portraits of young women. I have always been fascinated by his painting “Lady with a Ferret”, as much for the rare appearance in fine art of a ferret, as for the beautiful young woman.

Stoats, Ermines, Weasels, Polecats, and Ferrets

As is often the case, the painting has alternative titles, and in the book from which the first illustration is taken, (References A) it is called, “Lady with an Ermine, or Weasel” neither of which is correct. Consequently, some examination of natural history is needed here. The Mustelidae are a group of small carnivorous killers, the best-known European ones are the stoat, the weasel and the polecat. The stoat and weasel are quite small, while the polecat is bigger (2). The ferret is a domesticated albino version of the polecat. The animal in the painting is too big for a weasel or stoat, and is undoubtedly a ferret.

More accurate information on the relative sizes of the three species of animals is given below. The published data from References C has been processed by the author, in an “Excel” program, to create the two graphs. These show that polecats and ferrets are distinctly longer in the body than weasels or stoats, and also, in terms of body weight, they are far and away heavier. Continue reading

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Harnessing data from Nature’s great evolutionary experiment

deskarati dnaThere are 3 billion letters in the human genome, and scientists have endlessly debated how many of them serve a functional purpose. There are those letters that encode genes, our hereditary information, and those that provide instructions about how cells can use the genes. But those sequences are written with a comparative few of the vast number of DNA letters. Scientists have long debated how much of, or even if, the rest of our genome does anything, some going so far as to designate the part not devoted to encoding proteins as “junk DNA.”

In work published today in Nature Genetics, researchers at Cold Spring Harbor Laboratory (CSHL) have developed a new computational method to identify which letters in the human genome are functionally important. Their computer program, called fitCons, harnesses the power of evolution, comparing changes in DNA letters across not just related species, but also between multiple individuals in a single species. The results provide a surprising picture of just how little of our genome has been “conserved” by Nature not only across species over eons of time, but also over the more recent time period during which humans differentiated from one another.

“In model organisms, like yeast or flies, scientists often generate mutations to determine which letters in a DNA sequence are needed for a particular gene to function,” explains CSHL Professor Adam Siepel. “We can’t do that with humans. But when you think about it, Nature has been doing a similar experiment on a very large scale as species evolve. Mutations occur across the genome at random, but important letters are retained by natural selection, while the rest are free to change with no adverse consequence to the organism.” Continue reading

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New Horizons probe eyes Pluto for historic encounter

A Nasa probe is to start photographing the icy world of Pluto, to prepare itself for a historic encounter in July. The New Horizons spacecraft has travelled 5bn km (3bn miles) over nine years to get near the dwarf planet. And with 200m km still to go, its images of Pluto will show only a speck of light against the stars. But the data will be critical in helping to align the probe properly for what will be just a fleeting fly-by.

Pluto will be photographed repeatedly during the approach, to determine the probe’s position relative to the dwarf planet, explained Mark Holdridge, from the Johns Hopkins University’s Applied Physics Laboratory (JHUAPL) in Baltimore. “We then perform a number of correction manoeuvres to realign our trajectory with the reference trajectory, thus ensuring we hit our aim point to travel through the Pluto system,” he said. Any initial correction is likely to be made in March.

When New Horizons arrives at Pluto it will be moving so fast – at almost 14km/s – that going into orbit around the distant world is impossible; it must barrel straight through instead. One complication is that the seven different instruments aboard the spacecraft need to work at different distances to get their data, and so the team has constructed a very elaborate observation schedule for them all. But what this means is that very precise timing will be required to make sure the flyby runs smoothly.

The closest approach to Pluto is set for around 11:50 GMT on 14 July – at a miss distance of roughly 13,695km from the surface. Mission planners want the exact timings nailed to within 100 seconds. New Horizons will know then where and when to point the instruments. Edited from New Horizons probe eyes Pluto for historic encounter.

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Plane miraculously landing with one wing

Thanks to Phil Krause for sending us this video. Brilliant bit of flying.

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Post-traumatic stress ‘evident in 1300BC’

Evidence of post-traumatic stress disorder can be traced back to 1300BC – much earlier than previously thought – say researchers. The team at Anglia Ruskin University analysed translations from ancient Iraq or Mesopotamia. Accounts of soldiers being visited by “ghosts they faced in battle” fitted with a modern diagnosis of PTSD. The condition was likely to be as old as human civilisation, the researchers concluded.

Prof Jamie Hacker Hughes, a former consultant clinical psychologist for the Ministry of Defence, said the first description of PTSD was often accredited to the Greek historian Herodotus. Referring to the warrior Epizelus during the battle of Marathon in 490BC he wrote: “He suddenly lost sight of both eyes, though nothing had touched him.” But Prof Hughes’ report – titled Nothing New Under the Sun – argues there are references in the Assyrian Dynasty in Mesopotamia between 1300BC and 609BC. In that era men spent a year being toughened up by building roads, bridges and other projects, before spending a year at war and then returning to their families for a year before starting the cycle again.

Prof Hughes told the BBC News website: “The sorts of symptoms after battle were very clearly what we would call now post-traumatic stress symptoms. “They described hearing and seeing ghosts talking to them, who would be the ghosts of people they’d killed in battle – and that’s exactly the experience of modern-day soldiers who’ve been involved in close hand-to-hand combat.” Edited from Post-traumatic stress ‘evident in 1300BC’.

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Crash Course Astronomy – Naked Eye Observations

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The unique geology of Macquarie Island

Macquarie Island is located in the south-west Pacific Ocean, between Australia and New Zealand, and officially belongs to the Australian state of Tasmania. The island is tiny, only 5 km (3.1 mi) wide and 35 km (21.7 mi) long, covering a total area of 128 km2 (49 sq mi). It is a unique place: it is the only sub-Antarctic island to be fully oceanic in origin, and it is the only known site on Earth where an ophiolite complex is presently undergoing formation in it’s original geological setting, actively exposing mantle rocks on the Earth’s surface.

macquarie island

An ophiolite is essentially oceanic lithosphere (crust and upper mantle) that has been emplaced upon continental crust and can be identified by a classic stratigraphic sequence that reflects the geological processes at work along a mid-ocean ridge. Ophiolites are special to geologists as they are places where the oceanic crust and upper mantle rocks can be seen on land – normally, these are only found in the deep ocean and along active spreading ridges (such as Iceland). These features are the main reason for Macquarie Island’s 1997 inclusion on the UNESCO World Heritage List, along with the gorgeous natural landscape and prolific wildlife such as seabirds and seals.

The island is actually an exposed section of the Macquarie Ridge which is a major geological feature of the Macquarie Fault Zone which runs from the Macquarie Triple Junction (the intersection of the Indo-Australian, Pacific and Antarctic Plates) up to New Zealand where it intersects with the famous Alpine Fault.

The Macquarie Ridge formed 12 mya when basalt lava erupted from a fissure between the Pacific and Indo-Australian plates. Subsequent uplift is due to the incipient subduction of the Pacific Plate beneath the Indo-Australian – although the fault is a right-laterally moving, transform fault (a fault between two plates which essentially just slide past each other) the overall anticlockwise motion of the Pacific Plate movement causes it to start subducting here at a rate of ~ 2-3 cm/yr instead. Edited from The unique geology of Macquarie Island

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Lucid dreams and metacognition: Awareness of thinking—awareness of dreaming

To control one’s dreams and to live out there what is impossible in real life – a truly tempting idea. Some persons – so-called lucid dreamers -can do this. Researchers from the Max Planck Institute for Human Development in Berlin and the Max Planck Institute of Psychiatry in Munich have discovered that the brain area which enables self-reflection is larger in lucid dreamers. Thus, lucid dreamers are possibly also more self-reflecting when being awake.

Lucid dreamers are aware of dreaming while dreaming. Sometimes, they can even play an active role in their dreams. Most of them, however, have this experience only several times a year and just very few almost every night. Internet forums and blogs are full of instructions and tips on lucid dreaming. Possibly, lucid dreaming is closely related to the human capability of self-reflection – the so-called metacognition.

Neuroscientists from the Max Planck Institute for Human Development and the Max Planck Institute of Psychiatry have compared brain structures of frequent lucid dreamers and participants who never or only rarely have lucid dreams. Accordingly, the anterior prefrontal cortex, i.e., the brain area controlling conscious cognitive processes and playing an important role in the capability of self-reflection, is larger in lucid dreamers.

The differences in volumes in the anterior prefrontal cortex between lucid dreamers and non-lucid dreamers suggest that lucid dreaming and metacognition are indeed closely connected. This theory is supported by brain images taken when test persons were solving metacognitive tests while being awake. Those images show that the brain activity in the prefrontal cortex was higher in lucid dreamers. “Our results indicate that self-reflection in everyday life is more pronounced in persons who can easily control their dreams,” states Elisa Filevich, post-doc in the Center for Lifespan Psychology at the Max Planck Institute for Human Development. Via Lucid dreams and metacognition: Awareness of thinking—awareness of dreaming.

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Team discovers evolutionary mechanism that allows bacteria to resist antibiotics


In research published in Proceedings of the National Academy of Sciences, assistant professor of biochemistry and molecular biology at Saint Louis University Mee-Ngan F. Yap, Ph.D., discovered new information about how antibiotics like azithromycin stop staph infections, and why staph sometimes becomes resistant to drugs. Her evidence suggests a universal, evolutionary mechanism by which the bacteria eludes this kind of drug, offering scientists a way to improve the effectiveness of antibiotics to which bacteria have become resistant.

Staphylococcus aureus (familiar to many as the common and sometimes difficult to treat staph infection) is a strain of bacteria that frequently has become resistant to antibiotics, a development that has been challenging for doctors and dangerous for patients with severe infections. Yap and her research team studied staph that had been treated with the antibiotic azithromycin and learned two things: One, it turns out that the antibiotic isn’t as effective as was previously thought. And two, the process that the bacteria use to evade the antibiotic appears to be an evolutionary mechanism that the bacteria developed in order to delay genetic replication when beneficial.

The team studied the way antibiotics work within the ribosome, the site where bacteria translates the genetic codes into protein. When the bacteria encounter a potential problem in copying its genetic material, as posed by an antibiotic, it has a mechanism to thwart antibiotic inhibition by means of “ribosome stalling” that is mediated by special upstream peptide elements. As the bacteria’s ribosome copies the strings of genetic code, “ribosome stalling” at upstream elements often promotes the rearrangement of messenger RNA and activates downstream translation of the resistance gene. Many resistant pathogens exploit this mechanism to up-regulate antibiotic resistance genes, and so survive even in the presence of antibiotics. In effect, the delay allows the bacteria to prepare a defense against the antibiotic further down the line of genetic code.

Yap found that the azithromycin-bound ribosomes do not simply stall at random residues, but only at specific sites. Intriguingly these residues seem to be the preferred stalling site in the “ribosome stalling” peptide elements that stop genetic activity. Edited from Team discovers evolutionary mechanism that allows bacteria to resist antibiotics.

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Transform your world with holograms

For the first time ever, Microsoft HoloLens seamlessly blends high-definition holograms with your real world. Holograms will improve the way you do things every day, and enable you to do things you’ve never done before.

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Rosetta: ‘Goosebumps’ on ‘space duck’ hint at comet formation

Scientists working on Europe’s Rosetta probe, which is tracking Comet 67P, say they may have found evidence for how such icy objects were formed. New pictures of the surface reveal a lumpy texture in places that researchers speculate could have been the body’s original building blocks. Their appearance means they are being dubbed “goosebumps”, which is a bit of fun given the comet’s duck-like shape. But if this interpretation is correct, it represents a major discovery.

“We still have to model this, but I think they really could be pointing back in time to the early days of the Solar System – to the formation of the building blocks of cometary nuclei,” said imaging team leader Holger Sierks from the Max-Planck-Institute for Solar System Research in Göttingen, Germany. “Our thinking is that accreting gas and dust would have formed little ‘pebbles’ at first that grew and grew until they got up to the size of these goosebumps – about 3m in size – and for whatever reason, they couldn’t then grow any further. “Eventually, they’d have found a region of instability and clumped together to form the nucleus,” he told BBC News. Via Rosetta: ‘Goosebumps’ on ‘space duck’ hint at comet formation.

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Researchers are turning old plastic bottles into waterproof paper

A team of Mexican entrepreneurs has found a way to save 20 trees and 56,000 litres of water for every ton of paper produced – simply make it out of recycled plastic bottles instead. Young entrepreneurs in Mexico have developed a system that can convert PET (polyethylene terephthalate) bottles into a type of mineral paper that’s waterproof and phytodegradable. Developed by a company called Cronology, the new technique claims to be 15 percent cheaper than traditional paper manufacturing methods because it doesn’t use water or chemicals such as chlorine, as well as being far more environmentally friendly.

“By not cutting trees, nor using water we reduce costs and help the planet,” Ever Adrian Nava, co-founder of Cronology, explained in a press release. “The mineral paper is stronger than the standard, you can not break it with your hands, is waterproof, has the quality of being photodegradable and only absorbs the necessary amount of ink when printing,” Nava added. Mineral paper is also known as peta paper and stone paper, and it meets the quality standards required to be used to print books, general stationary and also boxes. Via Researchers are turning old plastic bottles into waterproof paper

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Genome-wide search reveals new genes involved in long-term memory

A study conducted in C. elegans worms (left) revealed genes involved in forming long-term memories. These genes are activated by a transcription factor called CREB in the worm’s AIM neurons (shown by arrows in right). Credit: Image source: Murphy lab

A new study has identified genes involved in long-term memory in the worm as part of research aimed at finding ways to retain cognitive abilities during aging. The study, which was published in the journal Neuron, identified more than 750 genes involved in long-term memory, including many that had not been found previously and that could serve as targets for future research, said senior author Coleen Murphy, an associate professor of molecular biology and the Lewis-Sigler Institute for Integrative Genomics at Princeton University.

“We want to know, are there ways to extend memory?” Murphy said. “And eventually, we would like to ask, are there compounds that could maintain memory with age?” The newly pinpointed genes are “turned on” by a molecule known as CREB (cAMP-response element-binding protein), a factor known to be required for long-term memory in many organisms, including worms and mice. “There is a pretty direct relationship between CREB and long-term memory,” Murphy said, “and many organisms lose CREB as they age.” By studying the CREB-activated genes involved in long-term memory, the researchers hope to better understand why some organisms lose their long-term memories as they age. Via Genome-wide search reveals new genes involved in long-term memory.

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