Global warming has increased moss growth at sites across the Antarctic Peninsula over the past half-century.
Much of Antarctica is covered in ice, but parts of its peninsula are instead blanketed in moss. Each year, more moss grows over the top of the previous season’s growth, providing a record of moss health over thousands of years.
Matthew Amesbury at the University of Exeter, UK, and his colleagues isolated moss-bank cores dating back 150 years from three sites across the peninsula. They found that since 1950 moss growth and accumulation have increased markedly at all sites. This shift is probably due to the increasing global temperatures associated with climate change.
Continued warming will probably trigger large-scale changes to Antarctic terrestrial ecosystems, the authors suggest.
The gases that envelop the distant dwarf planet might finally be freezing out and falling to the surface.
Pluto’s atmosphere appears to be collapsing — much more dramatically than scientists had anticipated.
Out on the chilly fringes of the Solar System, Pluto’s thin atmosphere is created by sunlight warming nitrogen ice and other ices on the planet’s surface, which vaporizes them. As a result, the atmosphere gets thicker and warmer when Pluto is closer to the Sun.
Since 1989, Pluto has been moving away from the Sun. Scientists had expected to see its atmosphere nearly vanish as the planet got colder, but had not observed this yet.
A team led by Ko Arimatsu at Kyoto University in Japan probed Pluto’s atmosphere by watching the planet pass in front of a distant star in July 2019. This rare ‘occultation’ allowed the scientists to measure the density of Pluto’s atmosphere as it slid on and off the face of the star.
Atmospheric pressure had dropped by one-fifth of what it was in 2016, the last time scientists measured it during an occultation. But more observations are needed to confirm the result, the team cautions — models suggest that the pressure should have dropped by only around 1% over that time period.
Emissions of sulfur hexafluoride soared over the 40 years to 2018, despite some countries’ efforts to curb its use.
A powerful greenhouse gas called sulfur hexafluoride is swiftly building up in the atmosphere, driven in part by the rapid growth of Asia’s electrical-power industry.
Sulfur hexafluoride is used in electrical equipment such as circuit breakers and transformers. It is the most potent of the six greenhouse gases regulated by the 1997 Kyoto Protocol: one tonne of it, released into the atmosphere, causes about 23,500 times as much warming as one tonne of carbon dioxide. The protocol requires some nations to cut their output of greenhouse gases, and many report that they have lowered their sulfur hexafluoride emissions.
Peter Simmonds at the University of Bristol, UK, and his colleagues calculated annual emissions of sulfur hexafluoride between 1978 and 2018. The researchers drew on measurements from a global network of air-monitoring sites and archived air samples.
Between 2008 and 2018, annual emissions of the gas increased by about 24% to around 9,000 tonnes a year. The rise reflects an increased demand for electrical equipment, especially in countries that are not bound by the Kyoto Protocol.
Some snakes can ‘fly’ — and can lengthen their flight by undulating as they travel through the air.
Flying snakes, which belong to the genus Chrysopelea, do not perform powered flight. Instead they glide, undulating as they go. But does their sinuous movement control their glide path or is it simply a vestigial wriggle connected to evolutionarily ancient movement centres in the brain?
To find out, Isaac Yeaton and his colleagues at Virginia Tech in Blacksburg captured the snakes’ airborne action with 23 cameras that tracked a number of markers on the reptiles in 3D space. The researchers then used that data to build a 3D mathematical model of snake ‘flight’ with and without the undulation.
A snake jumps to get going, flattens its body into a triangular aerofoil that acts similarly to the wing of a plane, and then starts to undulate. The undulation stabilizes the snake’s glide: the motion controls the animal’s roll and pitch, allowing the snake to travel further than it would do if it did not undulate.
Intriguingly — or horrifyingly, depending on your feelings about snakes — the researchers suggest that the aerial undulation could be used by flying snake-like robots.
A virus identified in China can infect human airway cells and seems to have infected pig-farm workers.
A swine flu virus prevalent in China has the potential to spread in people, according to a survey of the country’s pig population.
From 2011 to 2018, George Gao at the Chinese Academy of Sciences in Beijing, Jinhua Liu at China Agricultural University, also in Beijing, and their colleagues tested thousands of pigs across ten Chinese provinces. They isolated 179 types of swine influenza virus, which is the porcine version of human influenza virus. Tests showed that one type of virus, which the researchers call G4, can proliferate in human airway cells. In ferrets, which are a model for human flu, G4 causes lung inflammation and respiratory symptoms, including coughing. The virus can spread between ferrets by direct contact or through airborne particles of mucus or saliva.
The researchers found that about 10% of 338 pig-farm workers tested had developed antibodies against the virus, which suggests that the virus can jump from pigs to people. To prevent an outbreak, it’s crucial that the virus is kept in check in pigs and that individuals who work closely with the animals are monitored, the researchers say.
High-powered microscope allows scientists to visualize an exotic structure called a superlattice.
A widely used type of microscopy can reveal the structure of 2D ‘wonder materials’ in superb detail.
Take two carbon sheets, each only one atom thick. Stack them, then rotate them so that their crystal structures are slightly misaligned. The resulting structure, called a ‘twisted bilayer’, can have surprising properties, such as superconductivity, making this and similar structures of great interest to physicists.
To image a type of twisted bilayer called a superlattice, Abhay Pasupathy at Columbia University in New York City and his collaborators used a room-temperature technique that applies alternating electric fields to a material, creating slight changes in the material’s surface. A fine probe detects these changes to reveal the material’s topography.
The bilayer contains tile-shaped regions where its two crystalline sheets are close to an energetically favourable alignment. Interesting physics arises from the interaction between the tiles and the material’s electrons — but the details have been inaccessible to scientists relying on more-standard forms of room-temperature microscopy, which typically cannot image the tiles.
The new method not only reveals the tiles but shows, unexpectedly, that the electrons in the material move to the edges of the tiles.
Miniature plaster delivers stem cells designed to heal damaged heart tissue.
A 3D bioprinted ‘cardiac patch’ might be able to repair the damage caused by a heart attack.
Myocardial infarction, or heart attack, is a leading killer that permanently damages heart-muscle cells called cardiomyocytes. Researchers are interested in repairing the damage using cardiomyocytes made in the laboratory from stem cells, but integrating such cells into the heart has proved challenging.
Lijie Grace Zhang, at the George Washington University in Washington, DC, and her colleagues used 3D bioprinting to create patches of stretchable gel scaffolding that matched the curvature of the heart and could expand and contract as the heart beats. After being loaded with cardiomyocytes made from stem cells, these cardiac patches were placed onto the hearts of mice that had survived an experimental form of myocardial infarction.
After four months, the patches were still attached to the rodents’ beating hearts and had acquired a blood supply. The patches had also stimulated heart-muscle formation, providing a potential avenue for therapies that repair heart damage.
Springtails, some of the most isolated animals on Earth, harbour polystyrene foam in their guts.
Plastic has found its way into a tiny animal in one of the most remote spots on the planet — an invasion that could degrade a food web already under threat from climate change.
In February 2016, researchers on King George Island off the coast of Antarctica came across a large piece of polystyrene foam, which is used for home insulation, packaging and other purposes. The foam was covered in moss, lichens, microscopic algae and one-millimetre-long six-legged creatures known as Antarctic springtails (Cryptopygus antarcticus).
Elisa Bergami at the University of Siena in Italy and her colleagues detected polystyrene’s chemical fingerprint in four springtail specimens, suggesting that the animals ingested the fragments accidentally while grazing on the algae and lichen that grew on the foam.
That’s cause for concern, the researchers warn. Cryptopygus antarcticus forms part of simple but functional food webs in glacier-free areas and rocky coastal sites where penguins roost and seals gather. Plastic waste might become a new danger in the already fragile ecosystems of Antarctica.
Late-blossoming neurons show intriguing features that might endow them with advanced capabilities.
The hippocampus, a brain region involved in learning and memory, is known to include cells that arise during both infancy and adulthood. Now, experiments on rats have revealed key differences between those two classes of cell — differences that could endow the late-blooming cells with important capabilities.
To study the hippocampal cells that arise during maturity, Jason Snyder at the University of British Columbia in Vancouver, Canada, and his colleagues injected the hippocampi of infant and adult rats with viruses that mark only newly created neurons. The researchers estimated that half of the neurons in the hippocampus are generated during adulthood.
Compared to neurons born in the hippocampi of baby rats, those that grew in the brains of adult animals had more thorny protrusions crowning the part of the cell that receives information from other neurons. Adult-born neurons also had a higher number of finger-like structures connecting them with neurons that send inhibitory signals to the brain.
These differences could confer advanced functions on adult-born neurons, including the ability to stimulate other brain cells involved in cognition, the researchers say.
A violent eruption in the far north might have changed the course of history.
The eruption of an Alaskan volcano more than two millennia ago caused ruinous climate change — and might have spurred the rise of the Roman Empire.
Julius Caesar’s assassination in 44 BC kicked off political instability across the Mediterranean region. Written accounts and environmental proxies from the time also document conditions such as severe cold in the Northern Hemisphere in 43 and 42 BC that could have contributed to the social unrest. Scientists suspected that a volcano played a part in the weird weather, but did not know the eruption’s location.
Joseph McConnell at the Desert Research Institute in Reno, Nevada, and his colleagues analysed five ice cores from Greenland and one from the Russian Arctic. All contained layers high in sulfur that came from a 43 BC eruption. The team’s chemical analysis matched ash fragments in the cores to ash from Alaska’s Okmok volcano.
Computer modelling simulations suggest that the eruption could have flung enough sun-reflecting particles into the atmosphere to cause temperatures in the Mediterranean to plummet to as much as 7°C below normal, which could have contributed to the famine and disease described by writers of the day.
Personality traits help to explain why some people and not others hoarded a humdrum product in the face of a deadly virus.
People who felt seriously threatened by the COVID-19 pandemic are more likely to have stockpiled toilet paper in the pandemic’s early days than are those who were less worried about the disease.
As the new coronavirus began to spread across the Western Hemisphere this year, sales of toilet paper skyrocketed by up to 700% from February to March, prompting psychologists to argue about the reason for the buying spree.
Theo Toppe at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues surveyed 996 people in 22 countries across North America and Europe about how they purchased and stored toilet paper. Participants also ranked the threat of COVID-19 on a ten-point scale and took a test that rated them on several core personality traits.
Those who placed COVID-19 high on the risk scale were the most likely to bulk-buy toilet paper. Emotional people tended to worry most about the disease and thus tended to stockpile. Conscientiousness was also linked to stockpiling.
However, the variables studied accounted for only 12% of the variability in hoarding, so other factors must also influence people’s purchasing, the researchers say.
A coating made of liquid crystals perspires a drug-laced liquid.
A synthetic coating can ‘sweat’ droplets of fluid containing ibuprofen or other compounds when stimulated by radio waves.
Coatings that can secrete fluids on demand could keep themselves clean or administer medicines to a wound. Danqing Liu at the Eindhoven University of Technology in the Netherlands and her colleagues created such a coating from liquid-crystal molecules, which can move like a liquid but, when exposed to an electric field, align themselves neatly like a crystal’s atoms.
The fluid that serves as sweat is stored in numerous micrometre-sized pores surrounded by the long liquid-crystal molecules, which stand vertically on their ends. The coating rests on a layer of glass embedded with metallic electrodes that generate radio waves similar to those produced by a Wi-Fi router.
When the radio waves are turned on, the long liquid-crystal molecules twist to orient with the waves’ direction of travel. This twisting motion wrings liquid out of the coating’s pores. The coating sweats more as the radio waves become stronger.
After the radio waves are switched off, the coating re-absorbs any sweat left on its surface in seconds.
The brilliant auroras seen near Earth’s poles have a rival on Mars.
Mars’s atmosphere has a green glow, much like the Northern and Southern lights on Earth.
Researchers predicted four decades ago that Mars’s atmosphere should emit green light, but it has proved elusive. Jean-Claude Gérard at the University of Liège in Belgium and his colleagues finally spotted the glow by using the European Space Agency’s Trace Gas Orbiter spacecraft to scan the planet’s edge against the dark background of space.
The green glow is given off by oxygen, which forms when the Sun’s radiation breaks apart carbon dioxide in Mars’s atmosphere. The team’s measurements suggest that much of the glow comes from oxygen produced in two regions, 80 and 120 kilometres above the Martian surface.
The spacecraft measured the glow’s intensity in both visible and ultraviolet wavelengths, allowing the researchers to calculate the ratio between the two. The ratio should be the same for other planets. As a result, researchers studying other planets’ glows will be able to confirm that their instruments are working correctly by comparing the intensity ratio in their own measurements with that in the European team’s measurements of Mars.
Correction: An earlier version of this article misspelled Jean-Claude Gérard’s name.
A mission to explore the planets also furnishes insights into the small stuff.
A spacecraft that whizzed past Venus and Mercury more than a decade ago could help to solve one of physics’ most enduring puzzles: the lifetime of the neutron.
Neutrons are long-lived when combined with other particles in the nuclei of stable atoms, but when they are free-floating they decay within minutes. Laboratory experiments have disagreed on how long it takes free neutrons to die. One leading method yields an estimate of around 880 seconds; the other, around 888 seconds.
Jack Wilson at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, and his colleagues looked off-Earth for an answer. In 2007 and 2008, NASA’s MESSENGER spacecraft measured neutrons in space as it flew past Venus and Mercury. The particles form when cosmic rays hit the planets’ surfaces, knocking neutrons out of atomic nuclei.
The scientists compared the number of neutrons MESSENGER observed with what might be expected to be formed from such cosmic-ray collisions. The observed abundance can be attained if neutrons live around 780 seconds (plus or minus 70 seconds), the researchers say.
Radar shows the surprisingly complex architecture of Falerii Novi, a now-buried settlement founded in 241 BC.
Archaeologists have revealed the public baths, monuments and other grand structures of a buried Roman city — without having to dig it up.
Excavating an entire city is both costly and labour-intensive. As a result, archaeologists’ knowledge of ancient Roman settlements is based on a few well-studied locales.
Instead of relying on excavation, Martin Millett at the University of Cambridge, UK, and his colleagues used ground-penetrating radar (GPR) to scan and map the buried city of Falerii Novi north of Rome. GPR enabled the team to survey the entire city, which was inhabited from 241 BC until the seventh century, at a resolution of 6.25 centimetres.
The scans revealed that for a fairly small Roman city, Falerri Novi had unexpectedly rich and complex architecture, including what the researchers believe to be a large monument or sacred site. The 3D reconstruction even allowed the team to identify the large underground network of pipes that carried water across the city.
When combined with other tools, the authors say, GPR has the potential to “revolutionise” urban archaeology.
Bowhead whale stock has survived by wintering under the Arctic ice.
A cold-loving ocean giant called the Spitsbergen’s bowhead whale had been hunted almost to extinction by the 1990s. The whales’ songs were recently detected in the waters east of Greenland, but scientists knew little about the endangered animals’ habits.
Kit Kovacs at the Norwegian Polar Institute in Tromsø and her team sought hard data about these elusive whales, which belong to the Spitsbergen stock of bowheads (Balaena mysticetus), named for an island in the Arctic Circle. Riding in a helicopter dispatched from an icebreaker, the researchers shot transmitter tags into the blubber of 13 Spitsbergen’s bowheads.
The animals’ paths show that, contrary to other bowheads’ habits, Spitsbergen’s bowheads journey south in summer and north in winter. As a result, the whales spend the winter in deep, cold seas almost completely covered in ice, often more than 100 kilometres from large stretches of open water, relying on a few cracks in the ice to breathe.
The authors suggest that whalers eliminated whales that frequented balmier winter seas. The steadfastness of the ice protected the hardy whales that wintered farther north. Now their descendants are multiplying, and filling the deep with their songs.
Some drug-resistant pathogens might persist in patient wards for as long as eight years.
A sweeping effort to map a hospital’s microorganisms has found that infectious pathogens hide in a place that’s all about cleaning: the sink.
Niranjan Nagarajan at the Genome Institute of Singapore and his colleagues sampled bacteria from bed rails, sinks and other sites in a Singapore hospital. Microbes that tend to grow in slimy ‘biofilms’ and cause hospital-acquired infections were prevalent on sink traps and faucet aerators, whereas skin-dwelling bacteria were abundant on objects, such as door knobs and bed rails, that are often touched. Frequently touched sites harboured multidrug-resistant microbes such as methicillin-resistant Staphylococcus aureus, which might persist in the hospital environment for more than eight years, the team suggested.
On all surfaces, the researchers detected reservoirs of genes that confer resistance to antibiotics, but the resistance genes on aerators were different from those on bed rails and bedside lockers. Because bacteria can acquire antibiotic-resistance genes from their environment, these reservoirs can give rise to new microbes resistant to multiple drugs.
Understanding how hospitals’ microbial communities evolve could help to protect patients from hospital-borne infections, the researchers say.
Advice from special relativity: avert your eyes as that bicycle whizzes by.
Physicists have made the most realistic calculations yet of what a cyclist would look like if moving at close to the speed of light — the scenario in a classic thought experiment of special relativity.
Albert Einstein’s special theory of relativity implies that the dimensions of a fast-moving object are squashed along the direction of motion. But the implications for how the object looks to an observer are subtle. Different parts of the cyclist are at slightly different distances from the observer, so a photograph of the rider would be made up of photons that left the cyclist and bicycle at different times. As a consequence, the cyclist would look grotesquely distorted, with their back visible even when they were approaching.
Evan Cryer-Jenkins and Paul Stevenson at the University of Surrey in Guildford, UK, have calculated the 3D view seen not by a single camera but with binocular vision. Because the two eyes see different distortions, the authors speculate that a human observer would get motion sickness.
The research could help astronomers to design sensors for future interstellar probes moving at extremely high speed.
Bacteria embedded with coded snippets of DNA survive microwaving, boiling and frying.
A method that uses harmless microorganisms as biological labels could allow consumers to find out which farm grew the salad that made them sick and whether the designer shoes they bought were counterfeited.
Michael Springer at Harvard Medical School in Boston, Massachusetts, and his colleagues inserted short DNA sequences into the genomes of inactive forms of the bacterium Bacillus subtilis and the yeast Saccharomyces cerevisiae. The DNA sequences serve as biological barcodes that can be used in different combinations and identified with several DNA-detection tools.
Barcoded microbes that were sprayed onto sand, soil, carpet and wood remained detectable for months, even after being exposed to wind, rain, vacuuming or sweeping. They could also be transferred from surfaces to other objects, such as shoes worn in a sandpit that had been sprayed with the microorganisms.
Using DNA-tagged bacteria, the researchers were also able to map a leafy plant back to the specific pot in which it was grown. The barcoded microbes persisted on produce even after washing and cooking, so the approach could be used to track food contamination to its source, the researchers say.
The connections and information provided by a mobile phone could improve women’s well-being.
Possession of a mobile phone has been linked to greater gender equality and improved maternal health, especially in lower-income nations.
Valentina Rotondi at the University of Oxford, UK, and her colleagues compared the prevalence of mobile-phone subscriptions in 209 countries with data on measures of women’s health and freedom from 1993 to 2017. The team found that countries with more mobile phones per capita have less gender inequality and lower maternal and child mortality. These correlations hold even when controlling for developmental indicators, such as gross domestic product.
Surveys of girls and women aged 15 to 49 in 7 sub-Saharan African countries support the correlation. Women with mobiles were more likely to have decision-making power in their households and to use contraception than were women without them. The poorer the country, the greater the effect of mobile ownership.
It’s possible that women are simply more likely to own mobile phones in places where they are more empowered than in places where they are more oppressed. The researchers call for further studies, but say that in the meantime, getting phones into women’s hands should be a development priority.
A tumour’s genomic fingerprint provides a way to track minute quantities of cancer DNA in a person’s bloodstream.
A genomic technique that detects minuscule quantities of tumour DNA in the blood could help to determine whether people who have had tumour-removal surgery are cancer-free or need further treatment.
Available tests do detect DNA that tumour cells shed into the bloodstream, but can miss low levels of cancer DNA in people whose tumours have largely been removed through surgery.
Dan Landau at the New York Genome Center in New York City and his colleagues sequenced the genomes of tumour and normal cells from people with cancer to create a ‘mutational fingerprint’ — a list of the mutations in each person’s tumour. Next, the researchers trained an algorithm to compare a fingerprint with DNA from a blood sample. The algorithm identified tumour DNA even when it comprised only 0.001% of the total DNA in the bloodstream.
The researchers tested this approach on people with colon or lung cancer who had had their tumours removed. Individuals positive for circulating tumour DNA after surgery tended to have a high risk of relapse, whereas none of those with a negative test showed cancer recurrence during the study follow-up period.