Just a few tweaks to a bacterial enzyme make it a lean, mean plastic-destroying machine.
One type of plastic, polyethylene terephthalate, or PET, is widely used in polyester clothing and disposable bottles and is notoriously persistent in landfills. In 2016, Japanese scientists identified a new species of bacteria, Ideonella sakaiensis, which has a specialized enzyme that can naturally break down PET.
Now, an international team of researchers studying the enzyme’s structure has created a variant that’s even more efficient at gobbling plastic, the team reports April 17 in Proceedings of the National Academy of Sciences.
The scientists used a technique called X-ray crystallography to examine the enzyme’s structure for clues to its plastic-killing abilities. Then, they genetically tweaked the enzyme to create small variations in the structure, and tested those versions for PET-degrading performance. Some changes made the enzyme work even better. Both the original version and the mutated versions could break down both PET and another, newer bio-based plastic called PEF, short for polyethylene-2,5-furandicarboxylate. With a little more engineering, these enzymes could someday feast at landfills.
Ancient surgeons may have practiced dangerous skull-opening procedures on cows before operating on people.
A previously excavated cow skull from a roughly 5,400- to 5,000-year-old settlement in France contains a surgically created hole on the right side, a new study finds. No signs of bone healing, which start several days after an injury, appear around the opening. One or more people may have rehearsed surgical techniques on a dead cow, or may have tried unsuccessfully to save a sick cow’s life in what would be the oldest known case of veterinary surgery, researchers conclude online April 19 in Scientific Reports.
Evidence of skull surgery on humans, whether for medical or ritual reasons, goes back about 11,000 years (SN: 5/28/16, p. 12). Ancient surgeons needed to know how and where to scrape away bone without harming brain tissue and blood vessels. So practicing bone removal on cows or other animals is plausible.
The ancient cow’s skull opening, shaped almost in a square and framed by scrape marks, resembles two instances of human skull surgery from around the same time in France, say biological anthropologists Fernando Ramirez Rozzi of CNRS in Montrouge, France, and Alain Froment of IRD-Museum of Man in Paris. Microscopic and X-ray analyses found no fractures or splintered bone that would have resulted from goring by another cow’s horn. No damage typical of someone having struck the cow’s head with a club or other weapon appeared, either.
Club-wielding assailants struck the Scandinavian settlement with devastating violence, slaughtering at least 26 people and leaving the bodies where they fell. There, the bodies lay for 1,500 years until recovered recently by archaeologists analyzing clues about the Iron Age massacre.
It’s unclear why the seaside ringfort of Sandby borg, on the Baltic Sea island of Ӧland, was targeted at a time of political turmoil following the Roman Empire’s fall in Western Europe. Adults, teenagers and children died suddenly and brutally — their skeletons showing bones fractured by clubs, but no defensive wounds, say archaeologist Clara Alfsdotter of Bohuslӓns Museum in Udevalla, Sweden, and her colleagues. When the slaughter was over, the attackers left the sheep and other animals to starve and the valuables untouched, the scientists report in the April Antiquity. No one came back to bury the dead. That’s somewhat unusual: At most other excavated battlefield and massacre sites in Europe, bodies have been found in mass graves ( SN: 1/23/16, p. 7). However, 67 farming villagers slaughtered around 7,200 years ago at Austria’s Asparn-Schletz site were also left in place. Circumstances surrounding the attacks on Asparn-Schletz and Sandby borg are poorly understood, making it difficult to compare the two events, says anthropologist Bruno Boulestin of the University of Bordeaux in France, who did not participate in the excavation. The bones from Sandby borg have yet to undergo radiocarbon dating, making it impossible to say precisely when the massacre occurred, says archaeologist Ian Armit of the University of Bradford in England, who did not participate in the Sandby borg research. But the researchers suspect the killing happened after 476, when the fall of the Western Roman Empire left a power vacuum and power struggles broke out across parts of Europe and southern Scandinavia. Sandby borg’s attackers may have installed themselves as the new local rulers, the team suggests.
“It was not the killing that was the point, but the statement toward those witnessing it from a distance that ‘if you mess with us, this is what happens,’” says study coauthor Ludvig Papmehl-Dufay of Kalmar County Museum in Sweden.
Sandby borg, spanning roughly 5,000 square meters contained by an eroded oval stone wall, has been a center for archaeological excavations since 2011. Aerial photographs and ground surveys have revealed stone structures buried inside the ringfort off Sweden’s southeast coast. Investigators have located 53 houses, some within a central block circled by a street. By 2016, two houses had been fully excavated and seven others had undergone some investigation. Inside, researchers found gilded silver brooches, glass beads and silver bell pendants, in styles suggesting the fort was occupied in the late 400s. In one house, the skeletons of nine individuals of various ages were found. Their positions suggested they had been surprised by the attack, say Alfsdotter, Papmehl-Dufay and coauthor Helena Victor, also of Kalmar County Museum. One teenage boy appears to have fallen backward over an adult victim. Two corpses showed evidence of being partially burned, suggesting the attackers tried unsuccessfully to set the structure on fire or that a fire accidentally broke out. A tiny half skeleton from a herring lay next to the fireplace, adding support to the theory that the attackers left quickly without touching or eating anything. A pile of lamb skeletons stacked in the corner and showing signs of recent slaughter suggests the attack occurred sometime between late spring and early fall, the researchers say.
Scientists are working on radiocarbon dating the Sandby borg skeletons as the annual excavations continue, Papmehl-Dufay says. With more than 90 percent of the ringfort settlement yet to be excavated, there are likely more clues to the killing to be found.
He advertised as much in the subtitle of his autobiography, Surely You’re Joking, Mr. Feynman!: Adventures of a Curious Character. Everybody knew that, in many respects, Feynman was an oddball.
But he was curious in every other sense of the word as well. His curiosity about nature, about how the world works, led to a Nobel Prize in physics and a legendary reputation, both among physicists and the public at large. Feynman was born 100 years ago May 11. It’s an anniversary inspiring much celebration in the physics world. Feynman was one of the last great physicist celebrities, universally acknowledged as a genius who stood out even from other geniuses.
In 1997 I interviewed Nobel laureate Hans Bethe, a Cornell University physicist who worked with Feynman during World War II on the atomic bomb project at Los Alamos (and later on the Cornell faculty). “Normal” geniuses, Bethe said, did things much better than other people but you could figure out how they did it. And then there were magicians. “Feynman was a magician. I could not imagine how he got his ideas,” Bethe told me. “He was a phenomenon. Feynman certainly was the most original physicist I have seen in my life, and I have seen lots of them.”
Apart from his brilliance as a physicist, Feynman was also known for his skill at playing the bongo drums and cracking safes. Public acclaim came after he served on the presidential commission investigating the explosion of the space shuttle Challenger. In a dramatic moment during a hearing about that disaster, he dipped material from an O-ring (a crucial seal on the shuttle’s rockets) into icy water, demonstrating that an O-ring would not have remained flexible at the launch-time temperature. His autobiography had already become a best seller, so Feynman was well-known when he died in February 1988.
When I heard of Feynman’s death, I called John Wheeler, Feynman’s doctoral adviser at Princeton University before World War II.
“I felt very lucky to have him as my graduate student,” said Wheeler, who died in 2008. “There was an immense vitality about Feynman. He was interested in all kinds of problems.”
Feynman’s curiosity was not satisfied merely by being told the solution to a problem, though.
“If you said you had the answer to something, he wouldn’t let you tell it,” Wheeler said. “He had to stand on his head and pace up and down and figure out the answer for himself. It was his way of keeping the ability to make headway into brand new frontiers.”
Feynman found fascination in all sorts of things, some profound, some trivial. In his autobiography, he revealed that he spent a lot of time analyzing ant trails. He sometimes entertained Wheeler’s children by tossing tin cans into the air and then explaining how the way the can turned revealed whether the contents were solid or liquid.
Curiosity of that type was instrumental in the work that led to his Nobel Prize. While eating in the Cornell cafeteria, Feynman noticed someone tossing a plate, kind of like a Frisbee. As the plate flew by, Feynman noticed that the Cornell medallion on the plate was rotating more rapidly than the plate was wobbling. He performed some calculations and showed that the medallion’s rotation rate should be precisely twice the rate of the wobbling. He then perceived an analogy to a problem he had been investigating relating to the motion of electrons. The wobbling plate turned out to provide the clue he needed to develop a new version of the theory of quantum electrodynamics.
“The whole business that I got the Nobel Prize for came from that piddling around with the wobbling plate,” he wrote in his autobiography.
It was not curiosity alone that made Feynman a legend. His approach to physics and life incorporated a willful disdain for authority. He regularly disregarded bureaucratic rules, ignored expert opinion and was willing to fearlessly criticize the most eminent of other scientists.
During his time at Los Alamos, for instance, he encountered Niels Bohr, the foremost atomic physicist of the era. Other physicists held Bohr in awe. “Even to the big shot guys,” Feynman recalled, “Bohr was a great god.” During a meeting in which the “big shots” deferred to Bohr, Feynman kept pestering him with questions. Before the next meeting, Bohr called Feynman in to talk without the big shots. Bohr’s son (and assistant) later explained why. “He’s the only guy who’s not afraid of me, and will say when I’ve got a crazy idea,” Niels had said to his son. “So next time when we want to discuss ideas, we’re not going to be able to do it with these guys who say everything is yes, yes, Dr. Bohr. Get that guy and we’ll talk with him first.”
Feynman knew that he sometimes made mistakes. Once he foolishly even read some papers by experts that turned out to be wrong, retarding his work on understanding the form of radioactivity known as beta decay. He vowed never to make the mistake of listening to “experts” again.
“Of course,” he ended one chapter of his autobiography, “you only live one life, and you make all your mistakes, and learn what not to do, and that’s the end of you.”
You would be forgiven for thinking that real numbers are, in fact, real — the word is right there in the name. But physicist Nicolas Gisin doesn’t think so.
He’s not questioning the mathematical concept of a real number. The term refers to a number that isn’t imaginary: It has no factor of i, the square root of negative one. Instead, Gisin, of the University of Geneva, debates the physical reality of real numbers: Do they appropriately represent nature? Physicists regularly use real numbers to describe the world: velocities, positions, temperatures, energies. But is that description really correct? Gisin — known for his work on the foundations and applications of quantum mechanics — takes issue with real numbers that consist of a never-ending string of digits with no discernable pattern and that can’t be calculated by a computer. Such numbers (for example, 1.9801545341073… and so on) contain an infinite amount of information: You could imagine encoding in those digits the answers to every fathomable question in the English language — and more.
But to represent the world, real numbers shouldn’t contain unlimited information, Gisin says, because, “in a finite volume of space you will never have an infinite amount of information.”
Instead, Gisin argues March 19 on arXiv.org, only a certain number of digits of real numbers have physical meaning. After some number of digits, for example, the thousandth digit, or maybe even the billionth digit, their values are essentially random.
Most physicists don’t give much thought to philosophical puzzles like this one, but Gisin’s argument has big implications for the seemingly unrelated concept of free will. Standard classical physics, the branch of physics that governs the everyday, human-sized world, leaves no room for free will. Given the appropriate equations and the conditions of the world, classical physics says, everything can, in principle, be calculated, and therefore, predetermined. But if the world is described by numbers that have randomness baked into them, as Gisin suggests, that would knock classical physics from its deterministic perch. That would mean that the behavior of the universe — and everything in it — can’t be predetermined, Gisin says. “There really is room for creativity.”
Ebola has reemerged. The virus has killed at least 25 people since early April in an ongoing outbreak in Congo. And on May 18, the World Health Organization declared a “high” public health risk in Congo, as well as a “high risk” of the disease spreading to neighboring countries, but stopped short of declaring a global public health emergency.
Most of the 43 confirmed and suspected cases reported as of May 18 have been in a rural area called Bikoro, within the same northwest Congolese province struck by the virus in 2014. (A separate, unrelated outbreak in West Africa at the same time made headlines as the deadliest in history.) And in May 2017, eight cases were reported in the nearby province of Bas Uélé. But this year is different — for a couple of reasons. As of May 18, four cases have been confirmed in Mbandaka, a riverside city of at least 1.2 million people, raising the risk of the disease spreading. Health officials are also trying out an experimental vaccine this year in hopes of containing the outbreak. “We’ve seen what Ebola can do, but we know what needs to be done,” says WHO spokesperson Tarik Jasarevic.
Here’s what we know so far:
How did this year’s outbreak start? Details are spotty. A report by the International Red Cross identifies the first suspected case as a policeman in a Bikoro village called Ikoko Impenge. Another 11 family members later fell ill after the policeman’s funeral, and seven of those relatives have also since died. (Because the bodies of Ebola victims remain contagious after death, funerary rituals can be a source of transmission.) However, the investigation is still in progress, and both the WHO and local health officials say the first case hasn’t been identified. “We still don’t know exactly what started this outbreak,” says Jasarevic.
What’s the biggest worry right now? Now that the virus has been detected in a city, more people could come into contact with it. “That means we have to scale up the response,” Jasarevic says. Both the 2014 and 2017 outbreaks were largely confined to remote, rural areas, which made them easier to contain. On May 17, the WHO confirmed the first urban case in Mbandaka. A day later, the Congolese Department of Health confirmed three more.
How have health officials responded so far? On May 9, epidemiological teams from the WHO and Doctors Without Borders arrived in Bikoro and set up a mobile lab and a treatment center. They began tracking the spread of the virus. Supplies are also en route — including the experimental vaccine.
Just how experimental is this vaccine? Researchers began working on vaccines after the deadly 2014 outbreak killed some 11,000 in West Africa (SN: 12/26/15, p. 33). The first batch of one experimental vaccine called rVSV-ZEBOV, manufactured by Merck pharmaceutical company, reached the Congolese capital of Kinshasa on May 16.
The vaccine performed well in a 2016 field trial involving 5,837 people in Guinea (SN Online: 12/22/16). But the drug must be kept at a temperature between –60° Celsius and –80°C, making transportation and storage tricky.
The vaccine still lacks formal approval, but was cleared by both the WHO and Congolese officials for “compassionate use” in response to the most recent outbreak. Vaccination could begin in the next few days, and would mark the first time a vaccine has been used in response to an Ebola outbreak in the field.
In the trial, the WHO used a “ring vaccination” strategy, immunizing family and immediate contacts of victims immediately, to help stave off the virus’ spread. A similar approach will likely be used in Congo.
Is this a new strain of Ebola? No. Test results show that Zaire ebolavirus, which caused the 2014 and 2017 illnesses, is also responsible for this year’s outbreak, Jasarevic says. There could be some small genetic differences between versions from different years; only further genetic testing could reveal if that’s the case here.
But the good news is that the rVSV-ZEBOV vaccine targets a protein on the surface of the Zaire strain of Ebola, so it should work against the virus in the current outbreak.
Editor’s note: The Chang’e-4 relay satellite successfully lifted off from the Xichang Satellite Launch center at 5:28 a.m. Beijing time on May 21 (5:28 p.m. EDT on May 20).
The Chinese space program is set to launch a satellite aimed at supporting future communications from a planned mission to the farside of the moon.
The Chang’e-4 mission, which will include a rover and a lander, would be the first to visit the moon’s farside. In the first of a two-launch plan to get all the pieces in place, the supporting relay satellite, named Queqiao, is scheduled to lift off from the Xichang Satellite Launch Center on May 21, Chinese media report. The three-day launch window opens at 5 a.m. Beijing time (5 p.m. EDT on May 20), according to the Chinese online news site GB Times. Queqiao will go to an orbit beyond the moon that will allow it to communicate simultaneously with points on both the moon and Earth. It will also carry a Dutch-built radio telescope, which will be switched on in 2019 to search for long-wavelength signals from the universe’s first stars.
The Chang’e-4 rover and lander were originally built as backups for the Chang’e-3 mission, which landed two spacecraft on the moon in 2013. Another 2019 mission, Chang’e-5, aims to bring back the first rocks from the moon since Apollo 17 in 1972.
The Chang’e missions are named for the Chinese moon goddess. The satellite’s name comes from another Chinese myth about two lovers separated by the Silver River, also known as the Milky Way. According to the myth, a flock of magpies form a bridge called the Queqiao once a year so the lovers can meet.
Colorectal cancer screening should begin at age 45 rather than 50, according to new guidelines released May 30 by the American Cancer Society. The recommendation is a response to the steady rise over decades in the colorectal cancer rate in younger Americans (SN: 4/1/17, p. 5).
For people at average risk for colorectal cancer — those without a personal or family history of the disease and who haven’t had inflammatory bowel disease — the ACS suggests regular screening begin at 45 with either stool-based tests or visual exams, such as a colonoscopy. The new ACS guidelines, published in CA: A Cancer Journal for Clinicians, equally endorse six possible screening methods. Colorectal cancer is the second-most common cause of cancer death in the United States. Lifestyle choices such as smoking cigarettes, drinking alcohol, not exercising, eating processed and red meats and forgoing fruits and vegetables can increase a person’s risk for the disease.
The ACS says that screening can catch precancerous polyps and early-stage cancers, when they may be more easily treated. Journalist Katie Couric, whose husband died of colorectal cancer, and comedian Jimmy Kimmel have televised their colonoscopies to encourage viewers to get screened. “Overall rates of colorectal cancer have declined by more than 45 percent since the 1980s, owing in part to screening,” says gastroenterologist Andrew Chan at Massachusetts General Hospital in Boston who was not involved in the guidelines. “In sharp contrast, the rates of colorectal cancer have been increasing among all age groups between 20 and 49.” Those ages have experienced a 51 percent rise in the incidence of colorectal cancer since 1994.
Scientists aren’t sure why the disease is increasing among younger Americans. But Chan says it’s not just in relation to the older group; the absolute case numbers are going up in the younger group, too. “The increase we are seeing is not simply a reflection of the drop in cancer among older groups who are being screened.”
Pluto’s heart-shaped plains are striped with sand dunes, where the sand is made of solid methane ice, a new study finds.
Images from the New Horizons spacecraft’s July 2015 flyby of Pluto show 357 linear ridges that planetary scientist Matt Telfer of the University of Plymouth in England and colleagues interpret as dunes that have been shaped by a novel process, the team reports in the June 1 Science.
The ripples lie parallel to the Al-Idrisi Montes mountain range at the western edge of Sputnik Planitia, the wide plains of nitrogen and methane ice that form part of Pluto’s famous heart-shaped region. Relatively strong winds, between about 1 and 10 meters per second, should blow from those mountains across the plains. Computer simulations suggest that despite Pluto’s thin atmosphere, these winds are strong enough to keep sand-sized methane ice particles moving once they become airborne. But the winds are probably too weak to lift the grains off the ground in the first place.
Instead, little puffs of air coming from Sputnik Planitia’s nitrogen ice as the sun heats it could boost the methane ice particles skyward and into the wind, the team suggests. That process by which solids turn directly into vapor is called sublimation. “That’s a novel, interesting idea,” says planetary scientist Alexander Hayes of Cornell University who was not involved in the work, but wrote a commentary piece in the same issue of Science. But the notion raises a reason for caution: Sublimation alone could explain some of the features, without the need for wind, he says. Dunes are found across the solar system, from Earth (SN: 12/26/15, p. 5) to Mars (SN Online: 2/10/10) to Saturn’s moon Titan (SN Online: 8/28/13). Each of these worlds has the ingredients for dunes: a supply of loose, grainy material and an atmosphere or fluid to carry grains around.
“When you look at dunes across the solar system, something that always strikes me is that they form the same patterns, regardless of the environment,” Hayes says. Finding dunes on Pluto, too, suggests that the features may be ubiquitous. “If you have the material and a way to move it, you form dunes. That’s what this is telling us.”
Suicide rates have increased across the United States — and in dozens of states by more than 30 percent, according to a new report from the U.S. Centers for Disease Control and Prevention based on public health data from 1999 to 2016.
Among suicide victims counted in 2015 in 27 states, 54 percent had no known mental health condition, researchers say in the June 8 report. For those who died, circumstances surrounding their suicide included relationship or job problems, the loss of a home, legal troubles and physical health issues. These factors played a role whether suicide victims had a diagnosed medical condition or not. With suicide, “there’s no one cause. It’s a confluence of contributors at a particular stress point in time,” says clinical psychologist Jill Harkavy-Friedman, the vice president of research at the American Foundation for Suicide Prevention in New York City. “It’s very important to know that it’s not just mental illness; it’s many factors.”
Overall, close to 45,000 Americans died by suicide in 2016. Suicide is one of three top causes of death on the rise in the country, and has contributed to a drop in U.S. life expectancy (SN Online: 12/21/07). By state or jurisdiction, the rates of suicide in the most recent period studied (2014 to 2016) ranged from 6.9 per 100,000 people in the District of Columbia to 29.2 per 100,000 for Montana. “Suicide is a public health problem that can be prevented,” said Anne Schuchat, the CDC’s principal deputy director, in a news conference on June 7. “That’s why it’s so important to understand the range of factors and circumstances that contribute to suicide risk.”
Starting that prevention early by teaching elementary school kids problem-solving and coping skills and how to take care of their mental and physical health is key, Harkavy-Friedman says.
To reach the National Suicide Prevention Lifeline, call 1-800-273-TALK (8255).
