Shellfish stowaways on boat hulls could become castaways, thanks to a superslippery material.

Crowds of mussels can grab onto ships, piers and other infrastructure. They slow down the boats they commandeer, and they’re expensive to remove. The hitchhikers can even travel to new places and become invasive species (SN: 3/18/17, p. 30). A new lubricant-infused material could one day help prevent mussels from getting a grip in the first place, scientists report in the Aug. 18 Science.
Researchers modified a flexible silicone material to which Asian green mussels (Perna viridis) ordinarily stick liberally, suffusing it with a silicone lubricant. Some of the lubricant forms a thin, liquid layer and smooths out any microscopic roughness on the material’s surface; the rest creates a reservoir within the material’s pores. When the top layer wears off, the reservoir replenishes it.

Normally, mussels probe a surface with a footlike appendage and then send out a sticky thread to latch on. But mussels trying to attach to the lubricant-infused material either didn’t send out those threads at all or directed them to the wrong target — to the animals’ own shell or a different surface. That misfire suggests that the shellfish didn’t recognize the lubricated surface as a place to cling to, says study coauthor Joanna Aizenberg, an engineer at Harvard University.
She and colleagues are already commercializing lubricated coatings for use in other applications, such as implanted medical devices where it’s crucial that blood or bacteria not hold on to a surface. Next stop, the slippery coatings could take to the seas.

High-energy particles from outer space have helped uncover an enigmatic void deep inside the Great Pyramid of Giza.

Using high-tech devices typically reserved for particle physics experiments, researchers peered through the thick stone of the largest pyramid in Egypt for traces of cosmic rays and spotted a previously unknown empty space. The mysterious cavity is the first major structure discovered inside the roughly 4,500-year-old Great Pyramid since the 19th century, researchers report online November 2 in Nature.
“It’s a significant discovery,” says Peter Der Manuelian, an Egyptologist at Harvard University not involved in the work, “although precisely what it means is unclear.”

The open space may comprise one or more rooms or corridors, but the particle-detector images reveal only the rough size of the void, not the details of its design. Eventually, though, this detail of the Great Pyramid’s architecture could offer new insights into one of the world’s largest, oldest and most famous monuments. The only one of the ancient Seven Wonders of the World that’s still standing, the Great Pyramid was built as a burial tomb for Pharaoh Khufu.
“Imagine you’re an archaeologist and you walk into this room no one has walked in for [over] 4,000 years,” says Nural Akchurin, a physicist at Texas Tech University in Lubbock who wasn’t involved in the study. “That’s huge. It’s incredible.”
Researchers probed the Great Pyramid’s interior with devices that sense muons — by-products of spacefaring subatomic particles called cosmic rays striking atoms in the atmosphere. Muons continuously rain on Earth at nearly the speed of light. But while the subatomic particles easily streak through open air, rock can absorb or deflect them. By placing detectors near the base and areas deep inside of the Great Pyramid and measuring the number of muons that reach the detectors from different directions, scientists could spot empty spaces inside the ancient edifice.

For instance, if a detector inside the pyramid picked up slightly more muons from the north than the south, that would indicate there was slightly less rock on the north side to intercept incoming muons. That relative abundance of muons could indicate the presence of a chamber in that direction.

Muon imaging an enormous, dense construction like the Great Pyramid “is not an easy game,” Akchurin says. The monument obstructs 99 percent of incoming muons before the particles can reach detectors, so collecting enough data to spot its hollow spaces takes several months.
The newly identified void was first seen with a type of muon detector called nuclear emulsion film, which the researchers laid out in a space called the Queen’s chamber and the adjacent corridor inside the pyramid. When muons zip through these films, the particles’ chemical interactions with the material leave silver trails that reveal which direction the particles came from, explains Elena Guardincerri, a physicist at Los Alamos National Laboratory in New Mexico not involved in the work.

Upon developing these films, the researchers saw a surprising excess of muons coming through a region above the Grand Gallery, a sloping corridor that runs north-south through the center of the pyramid. The cavity appears to be at least 30 meters across — about the size of the Grand Gallery itself. “Our first reaction was a lot of excitement,” says study coauthor Mehdi Tayoubi, cofounder of the Heritage Innovation Preservation Institute in Paris. “We said, ‘Wow, we got something big!’”

Tayoubi and colleagues confirmed their discovery with observations from two other types of muon detectors, which generate electrical signals when muons pass through them, placed inside the Queen’s chamber and outside at the base of the pyramid.

Akchurin hopes this finding will pave the way for muon imaging of other ancient monuments around the world — particularly at archaeological sites where traditional excavation may be difficult, like deep in the jungle or on mountainsides.

Finding the chemical basis for the close association between the Attine ants, inhabiting an area extending from Argentina to the southern United States, and the fungus they culture is the aim of research … by Prof. Michael M. Martin of the University of Michigan. Although many animals feed on fungi, the culturing of fungus by the Attine ants is the only known example of creatures growing their own. — Science News, November 11, 1967

Update
Attine ants, a group of more than 200 species, began cultivating fungus “gardens” for food around 60 million years ago. Total codependence between the ants and fungi evolved around 30 million years ago, scientists wrote in April in Proceedings of the Royal Society B. During a global shift to a more arid climate with long seasonal dry periods, the moisture-loving fungi may have had a harder time surviving outside of ant-tended plots. Ants also became more dependent on fungi, losing, among other things, the ability to produce the amino acid arginine.

Spacetime ripples from black holes are becoming routine.

For a fifth time, scientists have reported the detection of two colliding black holes via their gravitational waves, tiny vibrations that warp the fabric of spacetime. Unlike previous gravitational wave detections, which were heralded with news conferences often featuring panels of scientists squinting at journalists under bright lights, this was a low-key announcement. The event, caught on June 8, 2017, by the Advanced Laser Interferometer Gravitational-Wave Observatory, LIGO, was unceremoniously unveiled in a paper published online November 15 at arXiv.org.

With masses 7 and 12 times that of the sun, the pair of black holes was the lightest LIGO has spotted so far. The lack of fanfare over the detection signals a shift. Scientists are now aiming to collect data from many black hole crashes. That data can be analyzed to answer questions about the population as a whole, such as how two black holes get paired up in the first place.

New observations of the whirling cores of dead stars have deepened the mystery behind a glut of antimatter particles raining down on Earth from space.

The particles are antielectrons, also known as positrons, and could be a sign of dark matter — the exotic and unidentified culprit that makes up the bulk of the universe’s mass. But more mundane explanations are also plausible: Positrons might be spewed from nearby pulsars, the spinning remnants of exploded stars, for example. But researchers with the High-Altitude Water Cherenkov Observatory, or HAWC, now have called the pulsar hypothesis into question in a paper published in the Nov. 17 Science.

Although the new observations don’t directly support the dark matter explanation, “if you have a few alternatives and cast doubt on one of them, then the other becomes more likely,” says HAWC scientist Jordan Goodman of the University of Maryland in College Park.

Earth is constantly bathed in cosmic rays, particles from space that include protons, atomic nuclei, electrons and positrons. Several experiments designed to detect the showers of spacefaring particles have found more high-energy positrons than expected (SN: 5/4/13, p. 14), and astrophysicists have debated the excess positrons’ source ever since. Dark matter particles annihilating one another could theoretically produce pairs of electrons and positrons, but so can other sources, such as pulsars.
It was uncertain, though, whether pulsars’ positrons would make it to Earth in numbers significant enough to explain the excess. HAWC researchers tested how positrons travel through space by measuring gamma rays, or high-energy light, from two nearby pulsars — Geminga and Monogem — around 900 light-years away. Those gamma rays are produced when energetic positrons and electrons slam into low-energy light particles, producing higher-energy radiation.
The size and intensity of the resulting gamma-ray glow indicated that the positrons slowly dissipated away from their pulsar birthplaces, getting bogged down by magnetic fields that permeate the galaxy and twist up the particles’ trajectories. That sluggish departure suggests the particles wouldn’t have made it all the way to Earth, the researchers conclude, and therefore couldn’t explain the excess.

Astrophysicist Dan Hooper of Fermilab in Batavia, Ill., disagrees. He still thinks pulsars are the best explanation for the rogue antimatter. The gamma ray measurements are just one method for studying how cosmic ray particles propagate through space. Other methods indicate that the pulsars’ positrons should be able to make the trek across the galaxy swiftly enough to get to Earth, he says. “I have every confidence that those particles are now reaching the solar system.”

Ruling out pulsars still wouldn’t point the finger at dark matter. “I think they’ve made a good case that these pulsars are not the source,” says astrophysicist Gregory Tarlé of the University of Michigan in Ann Arbor. Instead, Tarlé thinks that scientists can explain the excess positrons by better understanding what happens as cosmic ray particles travel through space. Protons interacting with the interstellar medium — particles that permeate the spaces between stars — could produce positrons that would explain the observations, without invoking either dark matter or pulsars.

The conflict leaves physicists with their work cut out for them. “In order to prove that it’s dark matter, you have to prove that it’s not something ordinary,” says HAWC researcher Brenda Dingus of Los Alamos National Laboratory in New Mexico. Although the new result disfavors the most obvious ordinary candidates, Dingus says, other possibilities are still in the running. “We need to look harder.”

To halt the misuse of opioids, it may help to slash the number of pills prescribed, a new study suggests.

Five months after the implementation of new opioid prescription guidelines at a University of Michigan hospital, roughly 7,000 fewer pills went home with patients — a drop that might reduce the risk of accessible pills leading to substance abuse. But the opioid reduction didn’t leave patients who had undergone a routine surgery with more pain, the team reports online December 6 in JAMA Surgery.
“The decline in opioid volume after the intervention was dramatic,” says physician Mark Bicket of Johns Hopkins University School of Medicine, who was not involved in the study.

Around 50 percent of people who misuse opioids get the drugs from a friend or relative for free, while 22 percent obtain them from a doctor, according to the U.S. Department of Health and Human Services. Michael Englesbe, a surgeon at the University of Michigan in Ann Arbor, says that part of doing a better job of managing patients’ pain “will be preventing chronic opioid use after surgical care and making sure fewer pills get into the community.”

Englesbe and colleagues looked at 170 people who had a minimally invasive surgery to remove their gallbladders at the University of Michigan hospital from 2015 to 2016. All had received a prescription for opioids. Of those patients, 100 completed a survey detailing how much of the prescription they took, whether they also used a common painkiller such as ibuprofen or acetaminophen, and how they rated their pain during the first week after surgery.

The 170 individuals typically received a prescription equivalent to 40 to 60 tablets, each containing 5 milligrams of hydrocodone. Seven of the 170 patients requested an opioid prescription refill. The 100 patients who completed the survey used very little of their prescriptions, usually somewhere from one to 12 pills. And their average pain score on a scale of zero (no pain) to 10 (the worst pain imaginable) was five.
Based on this information, guidelines for opioid prescriptions following the same type of surgery were implemented at the hospital in November of 2016. The researchers recommended prescriptions of 15 opioid pills, plus the use of common painkillers.

In the five months after the guidelines went into effect, 200 patients had the gallbladder surgery. Five of those patients asked for an opioid prescription refill. Eighty-six of the patients filled out the survey and reported that they used even less of their prescriptions — from zero to nine pills — than the pre-guidelines survey group. These patients also noted the same average pain score as the previously surveyed group and similar common painkiller use.

The study demonstrates “a relatively simple intervention at the institutional level with promising results,” Bicket says. “Patients receive opioid prescriptions within a health care system, so it makes sense to focus on getting our systems to work better in reducing the unnecessary supply of opioids after surgery.”

Along with this gallbladder procedure, Englesbe and colleagues have developed opioid prescribing recommendations for other routine surgeries, such as appendix removal and hernia repair, for the state of Michigan.

There have been hints for years that playing football might come at a cost. But a study this year dealt one of the hardest hits yet to the sport, detailing the extensive damage in football players’ brains, and not just those who played professionally.

In a large collection of former NFL players’ postmortem brains, nearly every sample showed signs of chronic traumatic encephalopathy, or CTE, a disorder diagnosed after death that’s associated with memory loss, emotional outbursts, depression and dementia. Damaging clumps of the protein tau were present in 110 of 111 brains, researchers reported in JAMA (SN: 8/19/17, p. 15).
Those startling numbers captured the attention of both the football-loving public and some previously skeptical researchers, says study coauthor Jesse Mez, a behavioral neurologist at Boston University. “This paper did a lot to bring them around.” And that increased awareness and acceptance has already pushed the research further. “The number of brain donors who have donated since the JAMA paper came out has been astronomical,” Mez says.
As the largest and most comprehensive CTE dataset yet, the results described in JAMA are a necessary step on the path to finding ways to treat or prevent CTE, and not just for professional athletes.
Former college and high school football players’ brains were also examined, though in small numbers. Three of 14 high school players and 48 of 53 college players had signs of CTE. Many of the brains were donated by relatives who suspected something was amiss. That skewed sample makes it difficult to draw broad conclusions. Still, the study raised troublesome questions about the safety of youth sports.

Those questions haven’t been answered, though other research this year provided clues. A study of concussed hockey players ages 11 to 14 suggested that young brains may need more time than is usually allotted to heal after a hard knock. Players had troublesome changes in white matter tracts — nerve cell bundles that carry messages across the brain — three months after injury, despite normal thinking and memory abilities, researchers reported in November in Neurology.

To fully understand CTE, scientists need a way to identify and follow the disease as it progresses. A comprehensive study is now under way to look for CTE markers in live people, and has already hit on one clue.

Compared with postmortem brain tissue taken from healthy people and those with Alzheimer’s, tissue from people who had CTE had higher levels of an inflammation protein called CCL11, Mez and other researchers reported in September in PLOS ONE. In people with CTE, the more years that a person played football, the more CCL11. CCL11 levels, or other factors circulating in cerebrospinal fluid or blood, might one day let scientists monitor the brain health of athletes and others exposed to head trauma.

The battle of the sexes, at least among certain ocean mammals, may come down to well-placed skin folds, suggests research by Patricia Brennan, an evolutionary biologist at Mount Holyoke College in South Hadley, Mass., and colleagues.

In some species, enhanced male-female genital fit has evolved over time in ways that make mating easier. This is an example of what scientists call congruent evolution. In other species, genital anatomy reflects a battle, as shape and form change over time to give one sex an edge in control of fertilization. Fittingly, this is called antagonistic evolution.
Brennan’s recent collaboration, examining genitalia of porpoises, dolphins and seals, required extra creativity. In previous studies, her team used saline to inflate preserved penises from birds, snakes, sharks and bats. But the tough, fibroelastic penises of the cetaceans would not inflate with saline alone. So her collaborator, Diane Kelly, a penis biomechanics expert at the University of Massachusetts Amherst, suggested pressurizing the saline with a beer keg.

“We looked at each other and said, ‘This could be the best or worst idea we’ve ever had,’ ” Brennan laughs. But it worked. The scientists then created vaginal endocasts with dental silicone and made 3-D mathematical models to examine male-female fit. The team, led by marine mammalogist Dara Orbach of Dalhousie University in Halifax, Canada, described the work in the Oct. 11 Proceedings of the Royal Society B.

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The results show both antagonistic and congruent coevolution. In the model vaginas of short-beaked common dolphins ( Delphinus delphis) and harbor seals ( Phoca vitulina ), penises encountered no physical barriers to penetration.
But in harbor porpoises (Phocoena phocoena) and bottlenosed dolphins (Tursiops truncatus), the scientists found vaginal folds that may help females physically exert choice over sperm. By subtly changing body position during sex, females may use those folds to decrease penetration depth, reducing the likelihood of fertilization by unwanted males, Brennan says.
Brennan’s work has, understandably, made a splash over the years, attracting media coverage and, in 2013, criticism. Conservative news websites and internet trolls attacked her research, calling it “wasteful government spending.” Surprised by the reaction, Brennan responded publicly with an essay in Slate , arguing that basic science moves society forward and is a valid and valuable use of public funds. The experience convinced her that scientists must defend basic science.
Our ability to innovate is undermined without curiosity-driven science, she says. Brennan has developed an outreach program on basic science and plans to keep expanding knowledge of vertebrate genitalia. “In every species we have looked,” she says, “we have found something weird that nobody else knew.” Reason enough to keep discovering.

NASA’s next mission will go where some spacecraft have gone before. The two finalists in the agency’s selection process will return to either Saturn’s moon Titan or comet 67P/Churyumov-Gerasimenko, NASA announced in a press teleconference on December 20.

The Dragonfly mission would launch a drone-like craft to Saturn’s largest moon in 2025 that would land in 2034. NASA’s Cassini-Huygens mission showed that Titan has lakes and rivers of liquid ethane and methane, and may have chemistry that is conducive to life.
“We can test how far prebiotic chemistry has progressed in an environment that we know has the ingredients for life,” said lead investigator Elizabeth Turtle of the Johns Hopkins Applied Physics Laboratory in Laurel, Md.

The other finalist, the Comet Astrobiology Exploration Sample Return (CAESAR) mission, would launch a spacecraft before the end of 2025 to collect a 100-gram sample from the surface of comet 67P, which was mapped by ESA’s Rosetta spacecraft, and return it to Earth in 2038.

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Rosetta’s mapping work “dramatically improves the chances of success for a very difficult activity, which is grabbing a piece of a comet,” said lead investigator Steven Squyres of Cornell University.
Each project will receive funding to further develop the mission concepts. In July 2019, NASA will announce which mission will fly.

Two other missions, one to search for signs of life in the plumes of Saturn’s moon Enceladus and one to land on Venus, will receive funding to tackle specific technology questions to prepare the missions for future competitions.

No story on the Science News website is complete without visuals. And when it comes to videos, those visuals have lives of their own on other platforms. In addition to incorporating videos into some of our articles, we also post videos to the Science News YouTube channel and the Science News magazine Facebook page, where thousands of people watch them each year.

We tackled all manner of subjects in video form in 2017— from popular events like the eclipse to significant discoveries like the detection of gravitational waves from colliding neutron stars to basic scientific questions like how tuna steer. Our most-viewed videos reflect this variety.
Here are the top five video stories from our YouTube channel in 2017:

1. How do mosquitoes dine and dash? (SN: 11/11/17, p. 13)
2. Light and gravitational waves reveal a neutron star crash (SN: 11/11/17, p. 6)
3. A star explodes: the story of supernova 1987A (SN: 2/18/17, p. 20)
4. How are frog tongues so sticky? (SN: 3/4/17, p. 11)
5. Wild male cuttlefish duke it out over a female (SN Online: 5/12/17)
6. Light and gravitational waves reveal a neutron star crash (SN Online: 10/16/17)

Light and gravitational waves revealed a neutron star crash | …
Gravitational waves from colliding neutron stars have been detected. Here’s why that’s such a huge deal. (Full story: http://ow.ly/JjMn30fUmMJ)

Posted by Science News Magazine on Monday, October 16, 2017

2. Cassini’s timeline to destruction (SN Online: 9/11/17)

The timeline to Cassini’s destruction
On September 15, the Cassini spacecraft will plunge into Saturn and burn up in the atmosphere. Here’s what its final moments will look like, as narrated by lead propulsion engineer Todd Barber.

Posted by Science News Magazine on Tuesday, September 12, 2017

3. How to pack wings like a ladybug (SN Online: 6/13/17)

Watch ladybugs fold their wings like origami masters
Ladybugs are probably better at packing than you are. Here’s how they fold up their wings into tiny spaces. (Full story: http://ow.ly/eZpw30cyS0T)

Posted by Science News Magazine on Saturday, December 2, 2017

4. Seven times Curiosity proved how awesome Mars used to be (SN Online: 8/4/17)

7 times Curiosity proved how awesome Mars used to be | Science…
On August 5, 2012, Curiosity landed on Mars. Since then, it’s taught us a lot about the Red Planet. Here are some highlights. (Read the full story here: http://ow.ly/T1sS30ebhKx)

Posted by Science News Magazine on Monday, September 25, 2017

5. Gecko grippers work in low gravity (SN Online: 6/28/17)

These gecko-inspired grippers could grab hold of space junk in…
Space junk can be dangerous. But most adhesives don’t work in space. So NASA looked to gecko toes for the answer. (Read more: http://ow.ly/9Mn430dbPAb)

Posted by Science News Magazine on Tuesday, August 29, 2017