Made out of a mere five molecules, the Ohio Bobcat Nanowagon checks in at 3.5 nanometers long and 2.5 wide — about the width of a DNA strand. Even so, it was the heftiest contender in the first-ever nanocar race earlier this year. This pip-squeak vehicle took home the bronze, but perhaps more importantly, researchers made a surprising observation while manufacturing this model of nanoracer. About 90 percent of the Bobcat Nanowagons that researchers produced broke apart when the scientists tried attaching them to a racetrack. Most broken bits looked like two-wheel hoverboards.
“It’s very surprising that it seems to be easier to break the chassis than to remove the wheel from the chassis,” study coauthor Eric Masson said August 23 in a news conference at the American Chemical Society Meeting. The type of chemical bond linking atoms in the car frame is typically thought to be stronger than the kind of bond attaching its wheels.
Masson, a chemist at Ohio University in Athens, and colleagues aren’t sure why the Bobcat Nanowagon was more liable to snap in half than lose a wheel. Explaining this chemical quirk could help scientists better understand the operations of molecular machines, which may be useful for transporting information in electronic devices or delivering drugs to specific cells (SN: 10/29/16, p. 6).
In the early evening of March 27, 1964, a magnitude 9.2 earthquake roiled Alaska. For nearly five minutes, the ground shuddered violently in what was, and still is, the second biggest temblor in recorded history.
Across the southern part of the state, land cracked and split, lifting some areas nearly 12 meters — about as high as a telephone pole — in an instant. Deep, house-swallowing maws opened up. Near the coast, ground turned jellylike and slid into bays, dooming almost everyone standing on it. Local tsunamis swamped towns and villages. Not many people lived in the newly formed state at the time. If the quake had struck in a more developed place, the damage and death toll would have been far greater. As it was, more than 130 people were killed.
In The Great Quake, Henry Fountain, a science journalist at the New York Times, tells a vivid tale of this natural drama through the eyes of the people who experienced the earthquake and the scientist who unearthed its secrets. The result is an engrossing story of ruin and revelation — one that ultimately shows how the 1964 quake provided some of the earliest supporting evidence for the theory of plate tectonics, then a disputed idea.
Using details from his own interviews with survivors — along with newspaper articles, diaries and other published accounts — Fountain focuses his story on two places near Prince William Sound. More people died in the port of Valdez (a familiar name because of the 1989 Exxon Valdez oil spill) than in any other Alaskan community, while the small village of Chenega suffered the highest proportional loss of life. Fountain’s tracking of the myriad small decisions people made that fateful day — that either put them in harm’s way or kept them safe — is meticulous. The experiences of the survivors and the lost are haunting.
Interwoven with stories of the human tragedy is Fountain’s account of the painstaking scientific gumshoe work necessary to piece together how such a monster earthquake had occurred. That’s where George Plafker, a geologist with the U.S. Geological Survey, comes in. In surveying the quake’s aftermath, Plafker, along with others, noticed something strange: There was no surface evidence of a fault large enough to explain the colossal shaking or the widespread uplift and sinking of land over hundreds of thousands of square kilometers.
Today, scientists know that Earth’s outer layer is divided into giant pieces and that the motion of tectonic plates — as they bump together or slide past each other — helps explain how some earthquakes occur. But in the mid-1960s, plate tectonics was just a hypothesis in need of real-world validation. Plafker’s crucial contribution was to realize that the powerful Alaskan quake had no surface fault because it took place at what is now known as a subduction zone, where dense oceanic crust sinks under lighter continental crust. The insight into the quake’s origin provided some of the first real proof of tectonic plate movements.
Throughout the book, Fountain weaves in brief histories of key people and ideas in the development of the theory of plate tectonics. For those familiar with the history, Fountain doesn’t offer much new. People less familiar may find it a little difficult to keep one geologist straight from another geophysicist.
But The Great Quake is an elegant showcase of how the progressive work of numerous scientists over time — all the while questioning, debating, changing their minds — can be pieced together into an idea that reshapes how we see and understand the planet.
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.
Story continues below image 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.
Story continues after image 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.
A new robotic arm made of DNA moves 100,000 times faster than previous DNA machinery.
The DNA nanobot is shaped like a gearshift, with an extendible arm that ranges from 25 to more than 400 nanometers long that’s attached to a 55-by-55-nanometer platform. Researchers remotely control this DNA device, described in the Jan. 19 Science, with electric fields that tug on charged molecules in its arm. Those electric fields help the nanomachine’s arm move much more quickly than previous DNA robots, which relied on chemical interactions between DNA molecules to move (SN: 9/11/10, p. 18).
Friedrich Simmel, a biophysicist at the Technical University of Munich, and his colleagues could swivel their DNA robotic arm 360 degrees in a matter of milliseconds. To lock the arm down in particular positions, the team built latches made of short, single-stranded DNA into the platform.
Such quick, efficient DNA nanobots could someday help move tiny cargo, such as molecules or nanoparticles, in a nanofactory that manufactures new types of materials.
Airborne particles smaller than 50 nanometers across can intensify storms, particularly over relatively pristine regions such as the Amazon rainforest or the oceans, new research suggests. In a simulation, a plume of these tiny particles increased a storm’s intensity by as much as 50 percent.
Called ultrafine aerosols, the particles are found in everything from auto emissions to wildfire smoke to printer toner. These aerosols were thought to be too small to affect cloud formation. But the new work suggests they can play a role in the water cycle of the Amazon Basin — which, in turn, has a profound effect on the planet’s hydrologic cycle, researchers report in the Jan. 26 Science. “I have studied aerosol interactions with storms for a decade,” says Jiwen Fan, an atmospheric scientist at the Pacific Northwest National Laboratory in Richland, Wash., who led the new study. “This is the first time I’ve seen such a huge impact” from these minute aerosols.
Larger aerosol particles greater than 100 nanometers, such as soot or black carbon, are known to help seed clouds. Water vapor in the atmosphere condenses onto these particles, called cloud condensation nuclei, and forms tiny droplets. But water vapor doesn’t condense easily around the tinier particles. For that to be possible, the air must contain even more water vapor than is usually required to form clouds, reaching a very high state of supersaturation.
Such a state is rare — larger aerosols are usually also present to form water droplets, removing that extra water from the atmosphere, Fan says. But in humid places with relatively low background air pollution levels, such as over the Amazon, supersaturation is common, she says. From 2014 to 2015, Brazilian and U.S. research agencies collaborated on a field experiment to collect data on weather and pollution conditions in the Amazon Basin. As part of the experiment, several observation sites tracked plumes of air pollution traveling from the city of Manaus out across the rainforest. During the warm, wet season, there is little difference day to day in most meteorological conditions over the rainforest, such as temperature, humidity and wind direction, Fan says. So a passing pollution plume represents a distinct, detectable perturbation to the system.
Story continues after image The international team examined vertical wind motion, or updrafts, and aerosol concentration data from one of these stations from March to May 2014. When a large plume of aerosols with an abundance of ultrafine particles passed by an observation station, the researchers observed a corresponding, more powerful vertical wind motion and heavier rain. Such updrafts intensify storms, helping to drive stronger circulation.
Next, the researchers conducted simulations of an actual storm that occurred on March 17, 2014, matching its temperature, wind and water vapor conditions, as well as a low level of background aerosols in the atmosphere. Then, the team introduced several pollution scenarios to interact with the storm, including no plume and a typical plume from the Manaus metropolis. The results suggested that the ultrafine aerosol particles, in particular, were not only acting as cloud condensation nuclei over the Amazon Basin, but also that the water droplets the aerosols created significantly strengthened the gathering storm.
If the conditions are right, the sheer abundance of the ultrafine particles in such a plume would rapidly create a very large number of cloud droplets. The formation of those droplets would also suddenly release a lot of latent heat — released from a substance as it changes from a vapor to a liquid — into the atmosphere. The heat would rise, creating updrafts and quickly strengthening the storm.
Aside from the Amazon, Fan notes that such pristine, humid conditions can also exist over large swaths of the oceans. One recent study in Geophysical Research Letters that she points to found a link between well-traveled shipping lanes, which would contain abundant exhaust including ultrafine aerosols, and an increase in lightning strikes. “This mechanism may have been at play there,” she says.
Atmospheric scientist Joel Thornton of the University of Washington in Seattle, who led the study on the shipping exhaust, says it’s possible that ultrafine particles play a role in that scenario. “What this paper does is raise the stakes in needing to develop a deeper, more accurate understanding of the sources and fates of atmospheric ultrafine particles,” Thornton says.
Meteorologist Johannes Quaas of the University of Leipzig in Germany, who was not involved in either study, agrees. “It’s a very interesting hypothesis.”
But the observations described in the new study don’t definitively demonstrate that ultrafine aerosols alone drive updrafts, Quaas adds. The weather conditions may appear highly consistent from day to day, but such systems are still highly chaotic. Everything from wind to temperature to how the land surface interacts with incoming solar radiation may be variable, he notes. “In reality, it’s not just the aerosols that change.”
“The strangest place in the whole universe might just be right here.” So says actor Will Smith, narrating the opening moments of a new documentary series about the wonderful unlikeliness of our own planet, Earth.
One Strange Rock, premiering March 26 on the National Geographic Channel, is itself a peculiar and unlikely creation. Executive produced by Academy Award–nominated Darren Aronofsky and by Jane Root of the production company Nutopia and narrated by Smith, the sprawling, ambitious 10-episode series is chock-full of stunningly beautiful images and CGI visuals of our dynamic planet. Each episode is united by a theme relating to Earth’s history, such as the genesis of life, the magnetic and atmospheric shields that protect the planet from solar radiation and the ways in which Earth’s denizens have shaped its surface. The first episode, “Gasp,” ponders Earth’s atmosphere and where its oxygen comes from. In one memorable sequence, the episode takes viewers on a whirlwind journey from Ethiopia’s dusty deserts to the Amazon rainforest to phytoplankton blooms in the ocean. Dust storms from Ethiopia, Smith tells us, fertilize the rainforest. And that rainforest, in turn, feeds phytoplankton. A mighty atmospheric river, fueled by water vapor from the Amazon and heat from the sun, flows across South America until it reaches the Andes and condenses into rain. That rain erodes rock and washes nutrients into the ocean, feeding blooms of phytoplankton called diatoms. One out of every two breaths that we take comes from the photosynthesis of those diatoms, Smith adds. As always, Smith is an appealing everyman. But the true stars of the series may be the eight astronauts, including Chris Hadfield and Nicole Stott, who appear throughout the series. In stark contrast to the colorful images of the planet, the astronauts are filmed alone, their faces half in shadow against a black background as they tell stories that loosely connect to the themes. The visual contrast emphasizes the astronauts’ roles as outsiders who have a rare perspective on the blue marble. “Having flown in space, I feel this connection to the planet,” Stott told Science News . “I was reintroduced to the planet.” Hadfield had a similar sentiment: “It’s just one tiny place, but it’s the tiny place that is ours,” he added. Each astronaut anchors a different episode. In “Gasp,” Hadfield describes a frightening moment during a spacewalk outside the International Space Station when his eyes watered. Without gravity, the water couldn’t form into teardrops, so it effectively blinded him. To remove the water, he was forced to allow some precious air to escape his suit. It’s a tense moment that underscores the pricelessness of the thin blue line, visible from space, that marks Earth’s atmosphere. “It contains everything that’s important to us,” Hadfield says in the episode. “It contains life.”
Stott, meanwhile, figures prominently in an episode called “Storm.” Instead of a weather system, the title refers to the rain of space debris that Earth has endured throughout much of its history — including the powerful collision that formed the moon (SN: 4/15/17, p. 18). Stott describes her own sense of wonder as a child, watching astronauts land on our closest neighbor — and how the travels of those astronauts and the rocks they brought back revealed that Earth and the moon probably originated from the same place.
It’s glimpses like these into the astronauts’ lives and personalities — scenes of Hadfield strumming “Space Oddity” on a guitar, for example, or Stott chatting with her son in the family kitchen — that make the episodes more than a series of beautiful and educational IMAX films. Having been away from the planet for a short time, the astronauts see Earth as precious, and they convey their affection for it well. Stott said she hopes that this will be the ultimate takeaway for viewers, for whom the series may serve as a reintroduction to the planet they thought they knew so well. “I hope that people will … appreciate and acknowledge the significance of [this reintroduction],” she said, “that it will result in an awareness and obligation to take care of each other.” Editor’s note: This story was updated on March 19, 2018, to add a mention of a second executive producer.
