Scientists Take Global Warming's Temperature

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 By how many degrees would the average temperature of the Earth rise if carbon dioxide levels doubled? Scientists have been pursuing an accurate estimate of this figure since the late 19th century—it’s the “holy grail of climate science,” writes Justin Gillis in
 
 The New York Times.
 
 Most experts believe that this “climate sensitivity” figure lies somewhere just above five degrees Fahrenheit.
 
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 That may not sound like a particularly scary number to many people — after all, we experience temperature variations of 20 or 30 degrees in a single day. But as an average for the entire planet, five degrees is a huge number.
 

 The ocean, covering 70 percent of the surface, helps bring down the average, but the warming is expected to be higher over land, causing weather extremes like heat waves and torrential rains. And the poles will warm even more, so that the increase in the Arctic could exceed 10 or 15 degrees Fahrenheit. That could cause substantial melting of the polar ice sheets, ultimately flooding the world’s major coastal cities.
 
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 Some recent studies, though, have proposed estimates below four degrees, stirring climate change skeptics and making some wonder if the future might look better than expected. But the well-regarded climate scientist James Annan warns against dismissing the threat of global warming. Gillis concludes:
 
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 Even if climate sensitivity turns out to be on the low end of the range, total emissions may wind up being so excessive as to drive the earth toward dangerous temperature increases.
 

 So if the recent science stands up to critical examination, it could indeed turn into a ray of hope — but only if it is then followed by a broad new push to get the combustion of fossil fuels under control.
 
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 Alternatively, we might be able to put excessive carbon dioxide
 <a href="http://www.pbs.org/wgbh/nova/tech/carbon-sink.html" title="into storage.">
 into storage
 </a>
 .
 
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Electric Shocks to Brain Could Improve Math Skills

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 Oxford University researchers found that students were better number-crunchers after a five-day course of brain stimulation. Here’s Ian Sample writing for Guardian Science:
 
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 If future studies prove that it works – and is safe – the cheap and non-invasive procedure might be used routinely to boost the cognitive power of those who fall behind in maths, the scientists said. Researchers led by Roi Cohen Kadosh zapped students’ brains with a technique called transcranial random noise stimulation (TRNS) while they performed simple calculations, or tried to remember mathematical facts by rote learning.
 

 In the study published in
 <a href="http://dx.doi.org/10.1016/j.cub.2013.04.045" title="">
 Current Biology
 </a>
 , 25 students had electrical pulses fired across their brains, while 26 others had a sham treatment, in which they thought they had brain stimulation, but the equipment was turned off.
 

 In tests afterwards, the students who had their brains stimulated solved maths puzzles 27% faster than the control group, suggesting that their brains were working more efficiently.
 
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 Some scientists doubt the claim’s validity, primarily because the study’s sample size was so small. Widespread implementation of this practice could also have ethical ramifications. Listen to this NOVA
 <a href="http://www.pbs.org/wgbh/nova/body/boost-kids-brainpower.html" title="radio story">
 radio story
 </a>
 (co-produced with PRI’s The World) to learn more.
 
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How to Grow a Green Roof

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 Green rooftops aren’t just verdant escapes for urban dwellers. For the past two years, New York City
 <a href="http://www.nyc.gov/html/planyc2030/html/home/home.shtml" target="_blank">
 Mayor Michael Bloomberg’s PlaNYC initiative
 </a>
 has offered tax abatements for green roof construction projects, which help stabilize building temperatures and manage stormwater runoff. Many of these rooftops are populated with sedum, a plant that’s resilient to wind and UV rays, but, unfortunately, can sometimes make buildings hotter by absorbing heat rather than reflecting it. So what’s a good alternative? The answer might lie in the soil—not the plants themselves. Here’s Amy Kraft writing for Scientific American:
 
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 Krista McGuire has taken sedum’s inadequacy as a challenge. The assistant professor of biological sciences at Barnard College wanted to see if a variety of native plants could survive on green roofs and how well they would deliver the desired benefits. Since 2010, the year Bloomberg announced his green roof initiative, McGuire has been comparing soil samples from 10 roofs planted with native vegetation with soil from five city parks spanning New York’s five boroughs, seeking to identify the microbial communities that thrive on green roofs to better to understand how healthy rooftop ecosystems sustain themselves.
 

 Her study,
 <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0058020" target="_blank">
 published in
 
 PLoS ONE
 
</a>
 last April,
 

 found that green roofs have distinct fungal communities that help plants to thrive in harsh, polluted environments and filter heavy metals. On average, 109 different types of fungi were present on each roof including
 
 Pseudallescheria fimeti
 
 , a fungus that grows in polluted soils and human-dominated environments. Rooftop soil also contained fungi from the genus
 
 Peyronellaea,
 
 which live in the tissues of plants to help them take in nutrients.
 
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 Her study might be a step in right direction:
 
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 “In the long term, this information may help individuals decide which types of soil microbes to amend on their green roofs, so that they can maximize plant survival and minimize management,” she says.
 
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 This discovery is a variation on
 <a href="http://www.pbs.org/wgbh/nova/next/nature/fungal-network-helps-plants-communicate/" title="last week's">
 last week’s
 </a>
 ; a study published in Ecology Letters found that subterranean fungal networks help plants warn each other against impending aphid attacks.
 
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An Icy Neutrino Observatory

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 Usually, astrophysicists have their minds fixed on the heavens. But now, they’re are keeping a watchful eye on the icy shield that covers one of the most frigid, remote places on Earth—the South Pole.
 

 There, they’ve built an outpost packed with 5,000 sensors designed to detect neutrinos, the fleeting subatomic particles that fly through our bodies at a rate of a trillion times a second. Neutrinos rarely interact with normal matter, which makes them extremely difficult for physicists to identify. One option is to build a big detector to increase the likelihood of collisions, and the IceCube Observatory—a $271 million endeavor—appears large enough to do the trick. So why Antarctica? Here’s Kenneth Chang, writing for the New York Times:
 
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 Once in a great while, a neutrino does collide with something, setting off a cascade of electrons and other subatomic debris. Charged particles in a transparent material like ice give off blue light. Phototubes record the bursts of light, and from the patterns, scientists can determine the direction and energy of the incoming neutrinos.
 
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<img alt="IceCube Observatory" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/icecube-observatory.width-990_U0kahwJ.jpg"/>
<figcaption>Antarctica's IceCube Observatory is searching for neutrinos from the outer reaches of space.
 
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 IceCube’s mission is to catch neutrinos from the outer reaches of space as they pass through the Earth. This type of neutrino—as opposed to the kind cooked up by our sun during fusion—can provide astronomers with information about the calamitous events that happen thousands of light-years away. But separating these from more prosaic solar neutrinos is anything but easy.
 

 Here’s John Timmer,
 <a href="http://arstechnica.com/science/2013/11/south-pole-detector-spots-28-out-of-this-world-neutrinos/">
 writing for ArsTechnica
 </a>
 :
 
<blockquote>

 Cosmic rays slam into the atmosphere all the time, and these can produce neutrinos that then enter the ice cap. They can also produce other exotic particles that produce light as they pass through the ice. Muons, for example, only live about 10
 
 -6
 
 seconds, but they’re moving so fast that time dilation means they live longer from the Earth’s frame of reference. As a result, they may travel several kilometers through the ice before decaying.
 

 To handle these cases of background, the authors eliminated any signals that were present in the outermost edges of the detector. Cosmic rays are especially easy to spot given that they tend to produce a spray of particles, many of which will be found at the detectors closest to the surface. You might still get a few neutrinos created above the North Pole and passing through on their way out of Earth, but the authors found that the majority of their signals came from the south, suggesting that these neutrinos aren’t a major problem for this detector.
 
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 Francis Halzen, a physics professor at the University of Wisconsin, reported in the journal Science that he and his team had discovered 26 new neutrinos that hadn’t originated from the sun in addition to the two announced earlier this year, named Bert and Ernie. (All 28 were named after Sesame Street characters; Bert and Ernie were the most energetic.)
 

 The first and only other successful neutrino detection occurred in 1987, when detectors in the U.S., Japan, and Russia found two dozen of them originating from a supernova about 165,000 light-years away. Now that IceCube is up and running, though, scientists hope an avalanche of data awaits them.
 
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 Photo Credit: © Sven Lindstrom, IceCube/NSF

Thank the Microbes, This Is a Good Malbec

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 What do wine, coffee, and chocolate have in common?
 

 Besides delectability, their flavors are derived in part from terroir, a loanword from French which roughly means “a sense of place.” From a scientific standpoint, terroir refers to the combined effects of geography, soil, local climate, and plant genetics on certain agricultural products. French winemakers put great stock in terroir, though not all of their American peers have been sold on the idea. There’s little data to define what terroir is. Testing the concept is incredibly difficult—there are almost too many potential variables.
 
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/malbec-grapes.width-990_tsrHuw3.jpg"/>
<figcaption>Wines are said to get some of their flavor from terroir, or the peculiarities of the region in which its grapes are grown.
 
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 But now, DNA analysis appears to have nailed down at least one part of the terroir equation. A research team led by David A. Mills and Nicholas A. Bokulich of the University of California, Davis sampled grape musts—the mashed grapes that are the starting point for making wine—and
 <a href="http://www.pnas.org/content/early/2013/11/20/1317377110.abstract?sid=8f8cd724-4105-404f-ac6b-b1f4716426de" title="discovered">
 discovered
 </a>
 that different grape varieties carry distinct patterns of fungi and bacteria.
 

 Here’s Nicholas Wade, writing for The New York Times:
 
<blockquote>

 They found, for instance, that one set of microbes is associated with chardonnay musts from the Napa Valley, another set with those of a must in Central Valley and a third grouping with musts from Sonoma. They noticed a similarly distinctive pattern of microbes in cabernet sauvignon musts from the north San Joaquin Valley, the Central Coast, Sonoma and Napa.
 

 The discovery of stable but differing patterns of microbial communities from one region’s vineyards to another means that microbes could explain, at least in part, why one region’s zinfandel, say, tastes different from another’s. The links between microbes and wine-growing regions “provide compelling support for the role of grape-surface microbial communities in regional wine characteristics,” the researchers conclude.
 
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 The scientists still need to prove whether or not these microbes influence the quality of the wine. Scientists are excited to continue this research, though even Mills admits that there’s an argument for holding off. “Many people don’t want this figured out,” he tells Wade, “because it demystifies the wonderful mystery of wine.”
 
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 Photo credit:
 <a href="http://www.flickr.com/photos/ccourtenay/9733201327/">
 ccourtenay/Flickr (CC BY-NC-ND 2.0)
 </a>

How to Make a False Memory

“Remembrance of things past is not necessarily the remembrance of things as they were.” —Marcel ProustProust was on to something. As powerful as our memories may be, they’re certainly not infallible. Our minds lead us astray all the time, but experts hadn’t gotten to the root of the brain’s deceptiveness—until now.Scientists at the Massachusetts Institute of Technology say they have successfully implanted a false memory in a mouse, giving insight into how memories—true and false—may form in the human brain. Led by Susumu Tonegawa (a Nobel laureate for his work in immunology), the team <a href="http://www.sciencemag.org/">reported Thursday in the journal Science</a> that they caused genetically modified mice to remember being shocked in a particular place when, in reality, that electric shock was delivered when the mouse was somewhere else entirely. Here’s <a href="http://www.technologyreview.com/news/517226/scientists-make-mice-remember-things-that-didnt-happen/">Susan Young, writing</a> for Technology Review:Previously, the MIT-based team had <a href="http://www.ncbi.nlm.nih.gov/pubmed/22441246">shown</a> that it could pinpoint the location and assemblage of cells that carry a memory, and that activating those cells stimulated memory recall in mice. To create the new, false memory, Tonegawa’s team reactivated a mouse’s memory of a safe place while the animal received shocks in its feet, thus transforming the original memory.First, the team used genetic tricks to label the brain cells involved in the memory of a chamber that was safe and neutral. The next day, they put the animal in a second chamber, a completely different setting. There, the animal got foot shocks while the researchers simultaneously shone light to reactivate the memory of the harmless first chamber. When the animal was put back in the first chamber, it fearfully froze—a clear indication that it remembered getting shocked in that chamber, even though that never happened.<a href="http://www.nytimes.com/2013/07/26/science/false-memory-planted-in-a-mouse-brain-study-shows.html">James Gorman wrote in The New York Times</a> that although mice and people are evolutionarily distant, the processes that govern memory formation in mammals are ancient. In both mice and men, memories form in an area of the hippocampus called the dentate gyrus—so conclusions drawn from this study are likely to apply to humans as well. Moreover, the scientists’ ability to locate and edit a memory is a significant achievement. Gorman quotes <a href="http://www.nytimes.com/2013/04/30/science/may-britt-and-edvard-moser-explore-the-brains-gps.html?pagewanted=all">Edvard I. Moser</a> , a neuroscientist at the Norwegian University of Science and Technology:“What I find fascinating about this,” Dr. Moser said, “is that you actually can point to a physical substrate to memory,” what the researchers call an engram. Neuroscientists have long talked about engrams, but Dr. Moser said the recent research is the closest they have gotten to pointing to a spot in the brain and saying, “That is the memory.”Of course, researchers have long known that memory blurs fact and fiction. But this new discovery is an important step toward figuring out how that actually works. <a href="http://www.guardian.co.uk/science/2013/jul/25/false-memory-implanted-mouse-brain">Writes Alok Jha</a> for The Guardian :The mouse models created by the MIT team will help scientists ask ever more complex questions about memories in people. “Now that we can reactivate and change the contents of memories in the brain, we can begin asking questions that were once the realm of philosophy,” said Steve Ramirez, a colleague of Tonagawa’s at MIT.

This Insect Jumps Using Built-In Gears

Biomimicry—the use of nature to inspire design—is
 <a href="http://mentalfloss.com/article/22702/10-technologies-we-stole-animal-kingdom">
 widely used by cutting-edge technologists
 </a>
 to design everything from bullet train noses, new X-ray machines, and lighter and safer cars. But let’s take a moment to flip that idea on its head. Are there things we thought humans invented that have been later discovered in nature?

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 As a matter of fact, yes. Nymphs of a common insect found in Britain—
 
 Issus coeleoptratus
 
 , a species of planthopper—has what were presumably a very human creation—gears. While working at the University of Cambridge, Greg Sutton noticed a strange mechanism on the insect’s back legs. Here’s Adam Cole
 <a href="http://www.npr.org/2013/09/13/219739500/living-gears-help-this-bug-jump">
 reporting
 </a>
 for NPR’s Morning Edition:

<blockquote>

 There was a tiny row of bumps on the inside of each leg where it met the insect’s body. The bumps looked just like the teeth of gears. And when the planthopper jumped, they acted like gears too — as teeth meshed, the legs turned in synchrony. Sutton says his finding,
 <a href="http://www.sciencemag.org/content/341/6151/1254">
 published
 </a>
 this week in
 
 Science
 
 , is the first mechanical gear system ever observed in nature.

</blockquote>
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 The small bumps—called trochanters—are incredibly well suited to the planthopper, which springs away from danger in the blink of an eye. Sutton filmed the bugs hopping with a high-speed camera and noticed that both leaping legs moved almost simultaneously—the difference between the two was as short as 30 millionths of a second. That’s much shorter than the time it takes for a neuron to execute even the smallest, most rudimentary task. The synchrony propels the insect faster, farther, and straighter.


 Ed Yong,
 <a href="http://phenomena.nationalgeographic.com/2013/09/12/this-insect-has-gears-in-its-legs/">
 writing
 </a>
 for Not Exactly Rocket Science, has more background on Sutton’s research:

<blockquote>

 The planthopper nymphs lose them when they become adults. But the adults don’t shoot off in uncoordinated spins—if anything, they’re better jumpers than the youngsters. Their hind trochanters make much closer contact with each other, and Sutton thinks that
 <a href="http://www.ncbi.nlm.nih.gov/pubmed/20086132">
 the friction between them helps to keep them in time
 </a>
 . “We’re kind of sure about that, but not entirely sure,” he says.

</blockquote>


 Issus coeleoptratus
 
 ‘s gears work similarly to their human-designed counterparts, but they have a leg up at smaller scales. Sutton—a mechanical engineer—thinks the trochanters could help us build more efficient machines:

<blockquote>

 Modern machines, such as 3-D printers, could easily create gears with these shark-fin teeth. Sutton is really excited by the prospect, and suspects that they may perform better in very small machines. “Modern machinery often doesn’t work at very small scales,” he says. “Friction doesn’t matter so much when you have two big gears next to each other but when you get small, friction starts killing you.”

</blockquote>

 The planthoppers might help to solve that problem. “We’re still being impressed and shocked by what we find in the back garden,” says Sutton.



 For more bioinspired technologies, watch “Making Stuff Wilder”, airing October 23 at 9/8 central on PBS.
 

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 Photo by Burrows/Sutton

Are there things we thought humans invented that have been later discovered in nature?

Allison Eck

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