A new technique turns climate-warming carbon emissions to stone. In a test program in Iceland, more than 95 percent of the carbon dioxide injected into basaltic lava rocks mineralized into solid rock within two years. This surprisingly fast transformation quarantined the CO2 from the atmosphere and could ultimately help offset society’s greenhouse gas emissions, scientists report in the June 10 Science.

“It’s working, it’s feasible and it’s fast enough to be a permanent solution for storing CO2 emissions,” says study coauthor Juerg Matter, a geochemist at the University of Southampton in England.
Many existing carbon storage schemes pump CO2 underground, though the approach has been prone to leaks. Targeting basalt, the cooled remains of volcanic outpourings, may offer an advantage over other types of rock. As much as 25 percent of basalt is made up of elements that react with CO2 to form solid carbonate minerals such as limestone, a process that occurs naturally during rock weathering. Since it was thought that this mineralization process takes hundreds to thousands of years in most rock, it seemed far too slow to be useful in combating near-term climate change.
In Iceland, Matter and colleagues blended groundwater with 230 tons of CO2 emissions from a geothermal power plant to create a kind of seltzer water. The researchers then injected the mixture 400 to 800 meters belowground into basaltic rock. After about two years, the team collected samples of the deep rock — and discovered that almost all of the CO2 had mineralized.

At $17 per ton, mineralizing carbon emissions is roughly twice as expensive as existing storage methods, though doesn’t require long-term monitoring to prevent leaks, Matter says. Additionally, the approach only requires water and basalt, he says, and “we have enough basalt globally to take care of all anthropogenic CO2 emissions, theoretically.”

Another research group’s work backs up the new findings. Peter McGrail, a geochemist at the Pacific Northwest National Laboratory in Richland, Wash., and colleagues conducted similar tests using pure CO2 without water. The as-yet-unpublished findings revealed rapid mineralization similar to that reported by Matter and colleagues, McGrail says.

If you want to lock new information into your brain, try working up a sweat four hours after first encountering it.

This precisely timed trick, described June 16 in Current Biology, comes courtesy of 72 people who learned the location of 90 objects on a computer screen. Some of these people then watched relaxing nature videos, while others worked up a sweat on stationary bikes, alternating between hard and easy pedaling for 35 minutes. This workout came either soon after the cram session or four hours later.

Compared with both the couch potatoes and the immediate exercisers, the people who worked out four hours after their learning session better remembered the objects’ locations two days later. The delayed exercisers also had more consistent activity in the brain’s hippocampus, an area important for memory, when they remembered correctly. That consistency indicates that the memories were stronger, Eelco van Dongen of the Donders Institute in the Netherlands and colleagues propose.

The researchers don’t yet know how exercise works its memory magic, but they have a guess. Molecules sparked by aerobic exercise, including the neural messenger dopamine and the protein BDNF, may help solidify memories by reorganizing brain cell connections.

Australia has seen zero mass shootings in the 20 years since it enacted strict gun control laws and a mandatory gun buyback program, researchers report June 22 in JAMA.

Key to this success is probably the reduction in people’s exposure to semiautomatic weapons, Johns Hopkins University health policy researcher Daniel Webster writes in an accompanying editorial.

“Here’s a society that recognized a public safety threat, found it unacceptable, and took measures to address the problem,” Webster says.
In April 1996, a man with two semiautomatic rifles shot and killed 35 people in Tasmania and wounded at least 18 others. Two months after the shooting, known as the Port Arthur massacre, Australia began implementing a comprehensive set of gun regulations, called the National Firearms Agreement.

The NFA is famous for banning semiautomatic long guns (including the ones used by the Port Arthur shooter), but, as Webster points out, it also made buying other guns a lot harder too. People have to document a “genuine need,” pass a safety test, wait a minimum of 28 days, have no restraining orders for violence and demonstrate good moral character, among other restrictions, Webster writes.

“In Australia, they look at someone’s full record and ask, ‘Is this a good idea to let this person have a firearm?’” Webster says. In the United States, “we do pretty much the opposite. The burden is on the government to show that you are too dangerous to have a firearm.”

Australia also initiated a mandatory gun buyback program in 1996, leading to the purchase and destruction of more than 650,000 semiautomatic and pump-action rifles and shotguns.

Simon Chapman of the University of Sydney and colleagues tallied up mass shootings before and after the NFA and analyzed 35 years of mortality data from the Australian Bureau of Statistics.
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From 1979 to 1996, Australia had 13 fatal mass shootings involving five or more victims (not including the shooter), Chapman and colleagues report. From 1997 to May 2016, the country has had none. (Three shootings, however, have killed three or four victims.) Chapman’s team also found that the rate of gun deaths dropped rapidly after 1996 but can’t confirm that this reduction is due to the gun laws.

SAN DIEGO — The long-standing mystery of the Milky Way’s missing satellite galaxies has a credible culprit, new research suggests. Supernovas, the vigorous explosions of massive stars, might have shoved much of the matter surrounding our galaxy deep into space, preventing a horde of tiny companion galaxies from forming in the first place.

Millions of teeny galaxies should be buzzing around the Milky Way, according to theories about how galaxies evolve, but observations have turned up only a few dozen (SN: 9/19/15, p. 6). And the brightest of those that have been found are lightweights compared with what theorists expect to find. But new computer simulations designed to track the growth of galaxies down to the level of individual stars reveal the critical role that supernovas might play in resolving these conundrums.
Philip Hopkins, an astrophysicist at Caltech, presented the results June 13 during a news briefing at a meeting of the American Astronomical Society.

“Galaxies don’t just form stars and sit there,” Hopkins said. “If you [add] up all the energy that supernovae emitted during a galaxy’s lifetime, it’s greater than the gravitational energy holding the galaxy together. You cannot ignore it.”

Simulations are typically limited by computing power, and efforts to simulate galaxy evolution have to brush over some details. For instance, rather than capture everything that’s going on in a galaxy, simulations slap on the additive effects of supernovas in an ad hoc fashion. These limitations don’t fully capture all the physics of stellar winds and supernova shocks that ripple through a galaxy.

Hopkins’ simulations grow a galaxy organically within a computer, tracing the evolution of a system such as the Milky Way over 13 billion years. Within a massive virtual blob of dark matter — the elusive substance thought to bind galaxies together — gas collects and fragments into stellar nurseries. Stars are born and die in this digital universe. A volley of life-ending explosions from the most massive of these stars lead to a turbulent galactic history, Hopkins finds.

“As these stars form rapidly in the early universe, they also live briefly and explode and die violently, ejecting material far from the galaxy,” he said. “They’re not just getting rid of gas.” They’re stirring up the dark matter as well, preventing a multitude of satellite galaxies from forming, and whittling away at those few that survive. “It’s not until quite late times … that [the galaxy] settles down and forms what we would call a recognizable galaxy today,” Hopkins said.
The idea that stellar tantrums could chip away at the gas and dark matter around a galaxy is not new, says Janice Lee, an astronomer at the Space Telescope Science Institute in Baltimore. But Hopkins’ simulations bring a lot more detail to that story and show that it’s a plausible reason for our galaxy’s satellite shortfall.

Before declaring that the mystery of the missing satellite galaxies is solved, however, astronomers need to run a few more checks against reality, says Lee. There are still assumptions in the calculations about how energy from dying stars interacts with interstellar gas, for example. The precise details of that interaction can affect how many stellar runts versus behemoths form in star clusters.

NASA’s James Webb Space Telescope, scheduled to launch in 2018, could probe star clusters in several relatively nearby galaxies, she says. Those observations could be compared with virtual clusters that appear in the simulations to see how close they match the real universe.

Even Amelia Earhart couldn’t compete with the great frigate bird. She flew nonstop across the United States for 19 hours in 1932; the frigate bird can stay aloft up to two months without landing, a new study finds. The seabird saves energy on transoceanic treks by capitalizing on the large-scale movement patterns of the atmosphere, researchers report in the July 1 Science. By hitching a ride on favorable winds, the bird can spend more time soaring and less time flapping its wings.

“Frigate birds are really an anomaly,” says Scott Shaffer, an ecologist at San Jose State University in California who wasn’t involved in the study. The large seabird spends much of its life over the open ocean. Both juvenile and adult birds undertake nonstop flights lasting weeks or months, the scientists found. Frigate birds can’t land in the water to catch a meal or take a break because their feathers aren’t waterproof, so scientists weren’t sure how the birds made such extreme journeys.

Researchers attached tiny accelerometers, GPS trackers and heart rate monitors to great frigate birds flying from a tiny island near Madagascar. By pooling data collected over several years, the team re-created what the birds were doing minute-by-minute over long flights — everything from how often the birds flapped their wings to when they dived for food.
The birds fly more than 400 kilometers, about equivalent to the distance from Boston to Philadelphia, every day. They don’t even stop to refuel, instead scooping up fish while still in flight.

And when frigate birds do take a break, it’s a quick stopover.

“When they land on a small island, you’d expect they’d stay there for several days. But in fact, they just stay there for a couple hours,” says Henri Weimerskirch, a biologist at the French National Center for Scientific Research in Villiers-en-Bois who led the study. “Even the young birds stay in flight almost continually for more than a year.”

Frigate birds need to be energy Scrooges to fly that far. To minimize wing-flapping time, they seek out routes upward-moving air currents that help them glide and soar over the water. For instance, the birds skirt the edge of the doldrums, a windless region near the equator. On either side of the region, consistent winds make for favorable flying conditions. Frigate birds ride a thermal roller coaster underneath the bank of fluffy cumulus clouds frequently found there, soaring up to altitudes of 600 meters.

Airplanes tend to avoid flying through cumulus clouds because they cause turbulence. So the researchers were surprised to find that frigate birds sometimes use the rising air inside the clouds to get an extra elevation boost — up to nearly 4,000 meters. The extra height means the birds have more time to gradually glide downward before finding a new updraft. That’s an advantage if the clouds (and the helpful air movement patterns they create) are scarce.

It’s not yet clear how frigate birds manage to sleep while on the wing. Weimerskirch suggests they might nap in several-minute bursts while ascending on thermals.

“To me, the most fascinating thing was how incredibly far these frigate birds go in a single flight, and how closely tied those flight patterns are to the long-term average atmospheric condition,” says Curtis Deutsch, an oceanographer at the University of Washington in Seattle. As these atmospheric patterns shift with climate change, frigate birds might change their path, too.

Even robots can use a heart. Or heart cells, at least.

A new stingray bot about the size of a penny relies on light-sensitive heart cells to swim. Zaps with light force the bot’s fins to flutter, letting researchers drive it through a watery obstacle course, Kit Parker of Harvard University and colleagues report in the July 8 Science.

The new work “extends the state of the art — very much so,” says bioengineer Rashid Bashir of the University of Illinois at Urbana-Champaign. “It’s the next level of sophistication for swimming devices.”
For decades, the field of robotics has been dominated by bulky, rigid machines made mostly of metal or hard plastic. But in recent years, some researchers have turned toward softer, squishier materials, such as silicones and rubbery plastics (SN: 11/1/14, p.11). And a small group of scientists have taken it one step further: combining soft materials with living cells.

So far, there’s just a handful of papers on these hybrid machines, says Bashir, whose own lab recently reported the invention of tiny, muscle-wrapped bots that inch along like worms in response to light.

In 2012, Parker’s team built a robotic jellyfish out of silicone and heart muscle cells. Electrically stimulating the cells let the jellyfish push itself through water by squeezing its body into a bell shape and then relaxing.

But, Parker says, “the jellyfish just swam.” He and his colleagues couldn’t steer it around a tank. They can, however, steer the new stingray.

He explains the team’s strategy with a story about his daughter. When she was little, Parker would point his laser pointer at the sidewalk and she’d try to stomp on the dot. He could guide her down a path as she followed the light. “She got to be independent and I got to make sure she didn’t step out into traffic.”
Parker guides his stingray bot in a similar way.

Layered on top of the bot’s body — a gold skeleton sandwiched between layers of silicone — lies a serpentine pattern of cells. The pattern is made up of about 200,000 these cells, harvested from rat hearts and then genetically engineered to contract when hit with pulses of blue light.
Flashing the light at the bot sets off a wave of contractions, making the fins undulate, like a flag rippling in the wind. To make the stingray turn, the team stimulates the bot’s right and left fins separately. Faster flashing on the right side makes the ray turn left and vice versa, Parker says.

By moving the lights slowly across a fluid-filled chamber, the researchers led the bot in a curving path around three obstacles.

“It’s very impressive,” says MIT computer scientist Daniela Rus. The stingray is “capable of a new type locomotion that had not been seen before” in robots, she says.

Bashir says he can envision such devices one day used in biomedicine or even environmental cleanup: Perhaps researchers could program cells on a swimming bot to suck toxicants out of lakes or streams. But the work is still in its early days, he says.

Parker, a bioengineer interested in cardiac cell biology, has something entirely different in mind. He wants to create an artificial heart that children born with malformed hearts could use as a replacement. Like a heart, a stingray’s muscular body is a pump, he says, designed to move fluids. The robot gave Parker a chance to work on assembling a pump made with living materials.

“Some engineers build things out of aluminum. I build things out of cells — and I need to practice,” he says. “So I practice building pumps.”

There’s another upside to the robot too, he adds: “It’s cool and fun.”

Aging happens to each of us, everywhere, all the time. It is so ever-present and slow that we tend to take little notice of it. Until we do. Those small losses in function and health eventually accumulate into life-changers.

Despite its constancy in our lives, aging remains mysterious on a fundamental level. Scientists still struggle to fully explain its root causes and its myriad effects. Even as discoveries pile up (SN: 12/26/15, p. 20), a clear picture has yet to emerge. Debates continue about whether individual life spans and the problems associated with aging are programmed into our bodies, like ticking time bombs we carry from birth. Others see the process as a buildup of tiny failures, a chaotic and runaway deterioration that steals vim and vigor, if not health and life itself. There is no unified theory of aging. That means that there is no one way to stop it. As longtime aging researcher Caleb Finch put it in an interview with Science News: Aging is still a black box.
The issue is an urgent one. The globe’s population has never been older. According to the U.S. Census Bureau’s 2015 An Aging World report, by 2020 the number of people 65 and older worldwide will outnumber children 5 and under for the first time in history. Seniors will make up 22.1 percent of the U.S. population in 2050, and nearly 17 percent globally (a whopping 1.6 billion people), the demographers predict. Worldwide, the 80-and-above crowd will grow from 126 million to 447 million. It’s a population sea change that will have ripple effects on culture, economics, medicine and society.

Scientists working at the frontiers of the field do agree that there are probably many ways to slow aging, Tina Hesman Saey reports in this special issue. Saey sums up current thinking on the actors of aging, as well as a number of intriguing approaches that might well tame aging’s effects. The goal, most agree, is not to find a fountain of youth but the keys to prolonging health.

It turns out that healthy aging in people does occur naturally. It is, however, in the words of Ali Torkamani, “an extremely rare phenotype.” Torkamani leads a genetic study of people 80 and older who are living free of chronic disease, described by Saey in her story. He and his team failed to find a single set of genes that protect these “wellderly.” Instead, the people studied carry a plethora of different genetic variants. They do share a lower risk of heart disease and Alzheimer’s. And, he says, the data hint that gene variants linked to key cognitive areas may be at play, leading him to ask: “Is cognitive health just one of the components of healthy aging? Or is there something about having a healthy brain that protects against other signs of aging?”

Exactly what happens in the brain as we age is a question Laura Sanders takes up in “The mature mind.” An intriguing idea is that the brain begins to lose the specialization that makes it so efficient in its prime, she reports. Further afield, Susan Milius considers a hydra and a weed, examining what these outliers of aging can tell us about how aging evolved and how flexible it truly is. Her answer: Very. The sheer diversity in life cycles and declines gives credence to arguments that while death may come for all of us, a robust old age could well be in the cards for more of us.

Those little piles of dirt that ant colonies leave on the ground are an indication that ants are busy underground. And they’re moving more soil and sediment than you might think. A new study finds that, over a hectare, colonies of Trachymyrmex septentrionalis fungus-gardening ants in Florida can move some 800 kilograms aboveground and another 200 kilograms below in a year.

The question of how much soil and sand ants can move originated not with entomologists but with geologists and archaeologists. These scientists use a technique called optically stimulated luminescence, or OSL, to date layers of sediment. When minerals such as quartz are exposed to the sun, they suck up and store energy. Scientists can use the amount of energy in buried minerals to determine when they last sat on the surface, taking in the sun.

But ants might muck this up. To find out, a group of geologists and archaeologists reached out to Walter Tschinkel, an entomologist at Florida State University. Figuring out how much sand and soil ants dig up and deposit on the surface — called biomantling — is relatively easy, especially if the color of the soil they’re digging up is different from that found on the ground. But tracking movement underground, or bioturbation, is a bit more complicated.
Tschinkel and his former student Jon Seal, now an ecologist at the University of Texas at Tyler, turned to an area of the Apalachicola National Forest in Florida dubbed “Ant Heaven” for its abundant and diverse collection of ants. Tschinkel has worked there since the 1970s, and for the last six years, he has been monitoring some 450 colonies of harvester ants, which bring up plenty of sandy soil from underground. But he was also curious about the fungus-gardening ants.

Tschinkel and Seal had already shown that the fungus-gardening ant “is extremely abundant, that it moves a very large amount of soil, and that as the summer warms up, it digs a deeper chamber and deposits that soil in higher chambers without exposing it to light,” Tschinkel says. “In other words, it appeared to do a very large amount of soil mixing of the type [that had been] described in harvester ants.”

No one had ever quantified an ant colony’s subterranean digging before. Tschinkel and Seal started by digging 10 holes a meter deep and filling them with layers of native sand mixed with various colors of art sand — pink, blue, purple or yellow, green and orange, with plain forest sand at the top. Each hole was then topped with a cage, and an ant colony was transferred with the fungus that the ants cultivate like a crop. Throughout the experiment, the researchers collected sand that the ants deposited on the surface and provided the colonies with food for their fungus, including leaves, small flowers and oatmeal. Seven months later, Tschinkel and Seal carefully excavated the nine surviving ant colonies and quantified grains of sand moved from one sand layer to another. The team reports its findings July 8 in PLOS ONE.

By the end of the study, each ant colony had deposited an average of 758 grams of sand on the surface and moved another 153 grams between one colored layer and another underground, mostly upward. The ants dug chambers to farm their fungus, and they sometimes filled them up with sand from deeper layers as they dug new chambers in areas with temperature and humidity best suited for cultivation.
With more than a thousand nests per hectare, the ants may be moving about a metric ton of sand each year, covering the surface with 6 centimeters of soil over the course of a millennium, the researchers calculated.

All of this mixing and moving could prove a challenge for geologists and archaeologists relying on OSL. “When ants deposit sand from deeper levels at higher levels (or the reverse), they are mixing sand with different light-emitting capacity, and therefore with different measured ages,” Tschinkel notes. “People who use OSL need to know how much such mixing occurs, and then devise ways of dealing with it.” Now that scientists know that ants could be a problem, they should be able to develop ways to work around the little insects.

To stop snail fever, control the snails.

That’s the takeaway of a new study of snail fever, or schistosomiasis, a tropical disease that affects more than 250 million people worldwide. It’s caused by a water-borne parasite that reproduces inside some snails. Parasite larvae burrow through people’s skin and can cause infertility, cognitive problems and even cancer. Today, most countries manage the disease with a drug that kills the parasite in human hosts. Some nations also control snail populations to hamstring the parasite’s life cycle, but that’s a less popular approach.

But snail control turns out to be more effective than drugs for curbing snail fever, researchers report July 21 in PLOS Neglected Tropical Diseases. The scientists compared a range of disease management strategies in 83 countries in the last century that included killing snails, using drugs or changing infrastructure (such as sanitation services). Projects using snail control cut disease by over 90 percent; those without it, by less than 40 percent.

The researchers suggest a blend of drug therapy and snail management to eradicate disease in the future.

Pollen tainted with neonicotinoid pesticides could interfere with male honeybee reproduction, a new study finds.

After bee colonies fed on pollen spiked with the pesticides thiamethoxam and clothianidin, male bees, or drones, produced almost 40 percent fewer living sperm than did males from colonies fed clean pollen, researchers report July 27 in Proceedings of the Royal Society B. The concentrations of the pesticides, 4.5 parts per billion and 1.5 parts per billion, respectively, were in the range of what free-living bees encounter when foraging around crops, study coauthor Lars Straub of the University of Bern, Switzerland, says.

Pollinator conservationists have raised concerns that chronic exposure to neonicotinoids widely used on crops is inadvertently weakening honeybee colonies working the fields. The amount of sperm males produce might affect how well a colony sustains itself because young queens mate (with about 15 males on average) during one or two early frenzies and then depend on that stored sperm for the rest of their egg-laying years. The new study is the first to examine neonicotinoid effects on honeybee sperm, Straub says.