“We’re trying to measure the composition of gases inside galaxies,” said Yuguang Chen, a postdoctoral researcher working with Professor Tucker Jones in the Department of Physics and Astronomy at the University of California, Davis.

Most elements other than hydrogen, helium and lithium are produced inside stars, so the composition and distribution of heavier elements — especially the ratio of oxygen to hydrogen — can help astronomers understand how many and what kinds of stars are being formed in a distant object.

Astronomers use two methods to measure oxygen in a galaxy, but unfortunately, they give different results. One common method, collisionally excited lines, gives a strong signal, but the results are thought to be sensitive to temperature changes, Chen said. A second method uses a different set of lines, called recombination lines, which are fainter but not thought to be affected by temperature.

The recombination line method consistently produces measurements about double those from collisionally excited lines. Scientists attribute the discrepancy to temperature fluctuations in gas clouds, but this has not been directly proven, Chen said.

Chen, Jones and colleagues used optical and infrared astronomy to measure oxygen abundance in dwarf galaxy Markarian 71, about 11 million light years from Earth. They used archived data from the recently retired SOFIA flying telescope and the retired Herschel Space Observatory, as well as making observations with telescopes at the W.M. Keck Observatory in Mauna Kea, Hawaii.

SOFIA (Stratospheric Observatory For Infrared Astronomy) was a telescope mounted in a Boeing 747 aircraft. By flying at 38,000 to 45,000 feet, the aircraft could get above 99% of the water vapor in Earth’s atmosphere, which effectively blocks infrared light from deep space from reaching ground level. A joint project of NASA and the German space agency, SOFIA made its last operational flight in September 2022 and is now headed for a museum display in Tucson.

The Herschel Space Observatory, named after astronomers William and Caroline Herschel, was an infrared space telescope operated by the European Space Agency. It was active from 2009 to 2013.

A surprising result

With data from these instruments, Chen and Jones examined oxygen abundance in Markarian 71 while correcting for temperature fluctuations. They found that the result from collisionally excited infrared lines was still 50% less than that from the recombination line method, even after eliminating the effect of temperature.

“This result is very surprising to us,” Chen said. There is no consensus on an explanation for the discrepancy, he said. The team plans to look at additional objects to figure out what properties of galaxies correlate with this variation, Chen said.

One of the goals of the James Webb Space Telescope, launched in 2022, is to make infrared observations of the composition of distant galaxies in the first billion years of the universe. The new results provide a framework for making these measurements with the JWST and the Atacama Large Millimeter Array in Chile.

Additional co-authors on the paper are: Ryan Sanders and Erin Huntzinger, UC Davis; Dario Fadder, Jessica Sutter and Robert Minchin, SOFIA Science Center, NASA Ames Research Center; Peter Senchyna, Observatories of the Carnegie Institute for Science, Pasadena; Daniel Stark and Benjamin Weiner, Steward Observatory, University of Arizona; Justin Spilker, Texas A&M University; and Guido Roberts-Borsani, UCLA. The work was financially supported in part by NASA. SOFIA was jointly operated by the Universities Space Research Association, Inc., and the Deutsches SOFIA Institut.

The W.M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, with financial support from the W.M. Keck Foundation. The researchers would like to thank the Hawaiian community for the privilege of allowing them to conduct observations on Mauna Kea, which plays a significant cultural and religious role.

The international team, led by the University of Cambridge, have previously demonstrated that woven displays can be made at large sizes, but these earlier examples were made using specialised manual laboratory equipment. Other smart textiles can be manufactured in specialised microelectronic fabrication facilities, but these are highly expensive and produce large volumes of waste.

However, the team found that flexible displays and smart fabrics can be made much more cheaply, and more sustainably, by weaving electronic, optoelectronic, sensing and energy fibre components on the same industrial looms used to make conventional textiles. Their results, reported in the journal Science Advances, demonstrate how smart textiles could be an alternative to larger electronics in sectors including automotive, electronics, fashion and construction.

Despite recent progress in the development of smart textiles, their functionality, dimensions and shapes have been limited by current manufacturing processes.

“We could make these textiles in specialised microelectronics facilities, but these require billions of pounds of investment,” said Dr Sanghyo Lee from Cambridge’s Department of Engineering, the paper’s first author. “In addition, manufacturing smart textiles in this way is highly limited, since everything has to be made on the same rigid wafers used to make integrated circuits, so the maximum size we can get is about 30 centimetres in diameter.”

“Smart textiles have also been limited by their lack of practicality,” said Dr Luigi Occhipinti, also from the Department of Engineering, who co-led the research. “You think of the sort of bending, stretching and folding that normal fabrics have to withstand, and it’s been a challenge to incorporate that same durability into smart textiles.”

Last year, some of the same researchers showed that if the fibres used in smart textiles were coated with materials that can withstand stretching, they could be compatible with conventional weaving processes. Using this technique, they produced a 46-inch woven demonstrator display.

Now, the researchers have shown that smart textiles can be made using automated processes, with no limits on their size or shape. Multiple types of fibre devices, including energy storage devices, light-emitting diodes, and transistors were fabricated, encapsulated, and mixed with conventional fibres, either synthetic or natural, to build smart textiles by automated weaving. The fibre devices were interconnected by an automated laser welding method with electrically conductive adhesive.

The processes were all optimised to minimise damage to the electronic components, which in turn made the smart textiles durable enough to withstand the stretching of an industrial weaving machine. The encapsulation method was developed to consider the functionality of the fibre devices, and the mechanical force and thermal energy were investigated systematically to achieve the automated weaving and laser-based interconnection, respectively.

The research team, working in partnership with textile manufacturers, were able to produce test patches of smart textiles of roughly 50×50 centimetres, although this can be scaled up to larger dimensions and produced in large volumes.

“These companies have well-established manufacturing lines with high throughput fibre extruders and large weaving machines that can weave a metre square of textiles automatically,” said Lee. “So when we introduce the smart fibres to the process, the result is basically an electronic system that is manufactured exactly the same way other textiles are manufactured.”

The researchers say it could be possible for large, flexible displays and monitors to be made on industrial looms, rather than in specialised electronics manufacturing facilities, which would make them far cheaper to produce. Further optimisation of the process is needed, however.

“The flexibility of these textiles is absolutely amazing,” said Occhipinti. “Not just in terms of their mechanical flexibility, but the flexibility of the approach, and to deploy sustainable and eco-friendly electronics manufacturing platforms that contribute to the reduction of carbon emissions and enable real applications of smart textiles in buildings, car interiors and clothing. Our approach is quite unique in that way.”

The research was supported in part by the European Union and UK Research and Innovation.

In order to better understand the relationship between these Polynesian societies of the western Pacific, Melanesia and Micronesia — often referred to as “Polynesian Outliers” — a multidisciplinary team of researchers analysed the geochemical signature of stone artefacts collected in Vanuatu, the Solomon Islands and the Caroline Islands between 1978 and 2019. An international research team, led by the Centre National de la Recherche Scientifique, was able to identify the geological origin of these artefacts after comparing their geochemical and isotopic compositions with reference datasets of natural rocks and archaeological quarries in the region.

The connection to the Polynesian homeland

Adzes are versatile cutting tools comparable to axes. Among the eight adzes or adze fragments the researchers analysed, six were sourced to the same large fortified quarry complex of Tatagamatau on Tutuila Island (American Sāmoa), which is located more than 2,500 kilometres away in the Polynesian homeland. “Tatagamatau adzes were among the most disseminated items across West and East Polynesia, and the sourcing of Taumako and Emae adzes suggest bursts of long-distance mobility towards the Outliers similar to those that led to the settlement of East Polynesia,” says lead author Aymeric Hermann, researcher at Centre National de la Recherche Scientifique and associate researcher at the Department of Linguistic and Cultural Evolution at the Max Planck Institute for Evolutionary Anthropology. Hermann points out that the transportation of such socially valued items — often passed down for generations among Polynesian chiefly families — suggests carefully planned voyages, rather than accidental landfalls.

The geochemical investigation of stone artefacts from the Polynesian Outliers also provides critical information on inter-island transfers between the Polynesians and their neighbours in the western Pacific, specifically between the Banks Islands and Central Vanuatu, and between the Bismarck and the Caroline Islands. The team highlights that such inter-island contacts are signals that Polynesian sailors might have played an important role in the reappraisal of long-distance mobility and in the distribution of specific material culture items and technologies such as shell adzes, back-strap loom, and obsidian points among the mosaic of Pacific Island societies in the western Pacific during the last millennium A.D. “A recent study describes an obsidian stemmed point as a chiefly heirloom found on Kapingamarangi Island with a geochemical signature matching an obsidian source on Lou Island in the Admiralties: this is an exciting find that echoes our identification of a basalt flake from mainland New Britain on that same atoll,” adds Hermann.

Long-distance mobility in the past

In the Pacific region, geochemical sourcing has been particularly successful at locating sources of stone artefacts and tracing the transport of specific items across distant islands and archipelagos. Such material evidence of long-distance inter-island voyaging shows that Pacific Island societies were never completely isolated from one another. These patterns of interaction are central to our understanding of the deeply intertwined history of cultural systems in the Pacific.

In this study, atomic emission spectroscopy and mass spectrometry were used to measure concentration of oxides, trace elements and ratios of radiogenic isotopes in order to identify geological provenances with a high level of accuracy. Thanks to the collaboration of experts in archaeology, geochemistry and data science, a cutting-edge approach to geochemical sourcing was developed, which involves the use of computer-assisted comparisons with open-access databases.

Ceperley, also a member of the Illinois Quantum Information Science and Technology Center, uses computer simulations to study how hydrogen atoms interact and combine to form different phases of matter like solids, liquids, and gases. However, a true understanding of these phenomena requires quantum mechanics, and quantum mechanical simulations are costly. To simplify the task, Ceperley and his collaborators developed a machine learning technique that allows quantum mechanical simulations to be performed with an unprecedented number of atoms. They reported in Physical Review Letters that their method found a new kind of high-pressure solid hydrogen that past theory and experiments missed.

“Machine learning turned out to teach us a great deal,” Ceperley said. “We had been seeing signs of new behavior in our previous simulations, but we didn’t trust them because we could only accommodate small numbers of atoms. With our machine learning model, we could take full advantage of the most accurate methods and see what’s really going on.”

Hydrogen atoms form a quantum mechanical system, but capturing their full quantum behavior is very difficult even on computers. A state-of-the-art technique like quantum Monte Carlo (QMC) can feasibly simulate hundreds of atoms, while understanding large-scale phase behaviors requires simulating thousands of atoms over long periods of time.

To make QMC more versatile, two former graduate students, Hongwei Niu and Yubo Yang, developed a machine learning model trained with QMC simulations capable of accommodating many more atoms than QMC by itself. They then used the model with postdoctoral research associate Scott Jensen to study how the solid phase of hydrogen that forms at very high pressures melts.

The three of them were surveying different temperatures and pressures to form a complete picture when they noticed something unusual in the solid phase. While the molecules in solid hydrogen are normally close-to-spherical and form a configuration called hexagonal close packed — Ceperley compared it to stacked oranges — the researchers observed a phase where the molecules become oblong figures — Ceperley described them as egg-like.

“We started with the not-too-ambitious goal of refining the theory of something we know about,” Jensen recalled. “Unfortunately, or perhaps fortunately, it was more interesting than that. There was this new behavior showing up. In fact, it was the dominant behavior at high temperatures and pressures, something there was no hint of in older theory.”

To verify their results, the researchers trained their machine learning model with data from density functional theory, a widely used technique that is less accurate than QMC but can accommodate many more atoms. They found that the simplified machine learning model perfectly reproduced the results of standard theory. The researchers concluded that their large-scale, machine learning-assisted QMC simulations can account for effects and make predictions that standard techniques cannot.

This work has started a conversation between Ceperley’s collaborators and some experimentalists. High-pressure measurements of hydrogen are difficult to perform, so experimental results are limited. The new prediction has inspired some groups to revisit the problem and more carefully explore hydrogen’s behavior under extreme conditions.

Ceperley noted that understanding hydrogen under high temperatures and pressures will enhance our understanding of Jupiter and Saturn, gaseous planets primarily made of hydrogen. Jensen added that hydrogen’s “simplicity” makes the substance important to study. “We want to understand everything, so we should start with systems that we can attack,” he said. “Hydrogen is simple, so it’s worth knowing that we can deal with it.”

This work was done in collaboration with Markus Holzmann of Univ. Grenoble Alpes and Carlo Pierleoni of the University of L’Aquila. Ceperley’s research group is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Computational Materials Sciences program under Award DE-SC0020177.

It is a food lift for bottom-dwelling animals in the deep sea: the alga Melosira arctica grows at a rapid pace under the sea ice during spring and summer months and forms metre-long cell chains there. When the cells die and the ice to whose underside they adhere melts, they stick together to form clumps that can sink several thousand metres to the bottom of the deep sea within a single day. There they form an important food source for bottom-dwelling animals and bacteria. In addition to food, however, these aggregates also transport a dubious cargo into the Arctic deep sea: microplastics. A research team led by biologist Dr Melanie Bergmann from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) has now published this in the journal Environmental Science and Technology.

“We have finally found a plausible explanation for why we always measure the largest amounts of microplastics in the area of the ice edge, even in deep-sea sediment,” Melanie Bergmann reports. Until now, the researchers only knew from earlier measurements that microplastics concentrate in the ice during sea ice formation and are released into the surrounding water when it melts. “The speed at which the Alga descends means that it falls almost in a straight line below the edge of the ice. Marine snow, on the other hand, is slower and gets pushed sideways by currents so sinks further away. With the Melosira taking microplastics directly to the bottom, it helps explain why we measure higher microplastic numbers under the ice edge,” explains the AWI biologist.

On an expedition with the research vessel Polarstern in summer 2021, she and a research team collected samples of Melosira algae and the surrounding water from ice floes. The partners from Ocean Frontier Institute (OFI), Dalhousie University and the University of Canterbury then analysed these in the laboratory for microplastic content. The surprising result: the clumps of algae contained an average of 31,000 ± 19,000 microplastic particles per cubic metre, about ten times the concentration of the surrounding water. “The filamentous algae have a slimy, sticky texture, so it potentially collects microplastic from the atmospheric deposition on the sea, the sea water itself, from the surrounding ice and any other source that it passes. Once entrapped in the algal slime they travel as if in an elevator to the seafloor, or are eaten by marine animals,” explains Deonie Allen of the University of Canterbury and Birmingham University who is part of the research team.

Since the ice algae are an important food source for many deep-sea dwellers, the microplastic could thus enter the food web there. But it is also an important food source at the sea surface and could explain why microplastics were particularly widespread among ice-associated zooplankton organisms, as an earlier study with AWI participation shows. In this way, it can also enter the food chain here when the zooplankton is eaten by fish such as polar cod and these are eaten by seabirds and seals and these in turn by polar bears.

The detailed analysis of plastic composition showed that a variety of different plastics are found in the Arctic, including polyethylene, polyester, polypropylene, nylon, acrylic and many more. In addition to various chemicals and dyes, this creates a mix of substances whose impact on the environment and living creatures is difficult to assess. “People in the Arctic are particularly dependent on the marine food web for their protein supply, for example through hunting or fishing. This means that they are also exposed to the microplastics and chemicals contained in it. Microplastics have already been detected in human intestines, blood, veins, lungs, placenta and breast milk and can cause inflammatory reactions, but the overall consequences have hardly been researched so far,” reports Melanie Bergmann. “Micro and nano plastics have basically been detected in every place scientists have looked in the human body and within a plethora of other species. It is known to change behaviours, growth, fecundity and mortality rates in organisms and many plastic chemicals are known toxins to humans,” says Steve Allen, OFI Dalhousie University, a research team member.

Moreover, the Arctic ecosystem is already threatened by the profound environmental upheavals caused by the climate crisis. If the organisms are now additionally exposed to microplastics and the chemicals they contain, it can weaken them further. “So, we have a combination of planetary crises that we urgently need to address effectively. Scientific calculations have shown that the most effective way to reduce plastic pollution is to reduce the production of new plastic,” says the AWI biologist and adds: “This should therefore definitely be prioritised in the global plastics agreement that is currently being negotiated.” That is why Melanie Bergmann is also accompanying the next round of negotiations, which will begin in Paris at the end of May.

“The signal of tidal modulation becomes extremely strong” after 2018, said Eric Beauce of Lamont-Doherty Earth Observatory, who noted that the signal was identified with seismicity that occurred around the faults that broke in the 2019 magnitude 7.1 earthquake.

The link does not mean that tidal stresses — which are very small compared to other tectonic stresses — triggered the earthquake, however.

“We don’t know if something started to happen in the fault zone, something that is an indicator of the upcoming earthquake,” Beauce said. “Maybe that process changed the properties of the crust in a way that made the crust be more sensitive to tidal stresses.”

Pulled by the same gravitational forces of sun and moon that create ocean tides, the solid earth also deforms in the same periodic way. People can’t feel the changes, but the ground deforms between 10 to 20 centimeters a day.

These solid tides “induce very, very small stress changes in the crust,” Beauce explains, “which can induce stress changes in all the faults within the crust.”

Although researchers have known about these tiny stress changes for more than a century, it has been difficult to extract their signal from the seismic record, and to determine whether they modulate seismicity.

In the past ten years, however, better earthquake detection and analysis techniques have made it possible to search through earthquake catalogs to find the signal of tidal stresses, Beauce said.

He and his colleagues built a rich, high-resolution earthquake catalog, using machine learning algorithms along with other techniques, for the past decade of microseismicity in the Ridgecrest area. (Microseismicity usually refers to earthquakes of magnitude 2.0 or smaller).

They found that “there is suggestive evidence that peak seismicity happens when tidal stresses are maximum,” Beauce said, “but this modulation is weak, and because it is weak, it is only suggested.”

Other researchers looking at the 2004 Indian Ocean and 2011 Tohoku megathrust earthquakes have detected an increase in modulation of seismicity connected to tidal stresses, decades before the earthquakes, said Beauce. And some scientists have been able to generate similar results in lab-created earthquake experiments.

The tidal findings do not have direct implications for earthquake forecasting, “as we do not know if we are looking at a general phenomenon or one specific to the Ridgecrest earthquake only, said Beauce, “but I see it as a way of getting new observational constraints on the physics of earthquakes, possibly the preparation and nucleation of earthquakes.”