But superconductors typically only work at extremely cold temperatures. When these materials are heated, they become ordinary conductors, which allow electricity to flow but with some energy lost, or insulators, which don’t conduct electricity at all.

Researchers have been hard at work looking for superconductor materials that can perform their magic at higher temperatures — perhaps even room temperature someday. Finding or building such a material could change modern technology, from computers and cell phones to the electric grid and transportation. Furthermore, the unique quantum state of superconductors also makes them excellent building blocks for quantum computers.

Now, researchers have observed that a necessary characteristic of a superconductor — called electron pairing — occurs at much higher temperatures than previously thought, and in a material where one least expects it — an antiferromagnetic insulator. Although the material did not have zero resistance, this finding suggests researchers might be able to find ways to engineer similar materials into superconductors that operate at higher temperatures. The research team from SLAC National Accelerator Laboratory, Stanford University, and other institutions published their results August 15 in Science.

“The electron pairs are telling us that they are ready to be superconducting, but something is stopping them,” said Ke-Jun Xu, a Stanford graduate student in applied physics and paper co-author. “If we can find a new method to synchronize the pairs, we could apply that to possibly building higher temperature superconductors.”

Out-of-sync electrons

Over the past 100 years, researchers have learned a lot about how exactly superconductors work. We know, for instance, that for a material to superconduct, electrons have to pair off, and these pairs must be coherent — i.e., their movements must be synchronized. If electrons are paired but incoherent, the material might end up being an insulator.

In superconductors, the electrons act like two reticent people at a dance party. At first, neither person wants to dance with the other. But then the DJ plays a song that both people like, allowing them to relax. They notice one another enjoying the song and become attracted from afar — they have paired but have not yet become coherent.

Then the DJ plays a new song, one that both people absolutely love. Suddenly, the two people pair and start to dance. Soon everyone at the dance party follows their lead: They all come together and start dancing to the same new tune. At this point, the party becomes coherent; it is in a superconducting state.

In the new study, the researchers observed electrons in a middle stage, where the electrons had locked eyes, but were not getting up to dance.

Cuprates acting oddly

Not long after superconductors were first discovered, researchers found that the thing that got electrons paired up and dancing was vibrations in the underlying material itself. This kind of electron pairing happens in a class of materials known as conventional superconductors, which are well understood, said Zhi-Xun Shen, a Stanford professor and investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC who supervised the research. Conventional superconductors work at temperatures typically close to absolute zero, below 25 Kelvin, in ambient pressure.

Unconventional superconductors — such as the copper oxide material, or cuprate, in the current study — work at significantly higher temperatures, sometimes up to 130 Kelvin. In cuprates, it is widely believed something beyond lattice vibrations helps pair up electrons. Although researchers aren’t sure exactly what’s behind it, the leading candidate is fluctuating electron spins, which cause the electrons to pair and dance with a higher angular momentum. This phenomenon is known as a wave channel — and early indications of such a novel state were seen in an experiment at SSRL about three decades ago. Understanding what drives electron pairing in cuprates could help design superconductors that work at higher temperatures.

In this project, scientists chose a cuprate family that had not been studied in depth because its maximum superconducting temperature was relatively low — 25 Kelvin — compared to other cuprates. Even worse, most members of this family are good insulators. To see the atomic details of the cuprate, researchers shined ultraviolet light onto material samples, which eject electrons from the material. When the electrons are bound, they are slightly more resistant to being ejected, resulting in an “energy gap.” This energy gap persists up to 150 Kelvin, suggesting that electrons are paired at much higher temperatures than the zero resistance state at about 25 Kelvin. The most unusual finding of this study is that the pairing is the strongest in the most insulating samples.

The cuprate in the study might not be the material to reach superconductivity at room temperature, around 300 Kelvin, Shen said. “But maybe in another superconductor material family, we can use this knowledge for hints to get closer to room temperature,” he said.

“Our findings open a potentially rich new path forward,” Shen said. “We plan to study this pairing gap in the future to help engineer superconductors using new methods. On the one hand, we plan to use similar experimental approaches at SSRL to gain further insight into this incoherent pairing state. On the other hand, we want to find ways to manipulate these materials to perhaps coerce these incoherent pairs into synchronization.”

This project was supported in part by the DOE’s Office of Science. SSRL is a DOE Office of Science user facility.

In a new study published Aug. 15 in Science, Yale researchers identified how brain cells begin to coalesce into this wired network in early development before experience has a chance to shape the brain. It turns out that very early development follows the same rules as later development — cells that fire together wire together. But rather than experience being the driving force, it’s spontaneous cellular activity.

“One of the fundamental questions we are pursuing is how the brain gets wired during development,” said Michael Crair, co-senior author of the study and the William Ziegler III Professor of Neuroscience at Yale School of Medicine. “What are the rules and mechanisms that govern brain wiring? These findings help answer that question.”

For the study, researchers focused on mouse retinal ganglion cells, which project from the retina to a region of the brain called the superior colliculus where they connect to downstream target neurons. The researchers simultaneously measured the activity of a single retinal ganglion cell, the anatomical changes that occurred in that cell during development, and the activity of surrounding cells in awake neonatal mice whose eyes had not yet opened. This technically complex experiment was made possible by advanced microscopy techniques and fluorescent proteins that indicate cell activity and anatomical changes.

Previous research has shown that before sensory experience can take place — for instance, when humans are in the womb or, in the days before young mice open their eyes — spontaneously generated neuronal activity correlates and forms waves. In the new study, researchers found that when the activity of a single retinal ganglion cell was highly synchronized with waves of spontaneous activity in surrounding cells, the single cell’s axon — the part of the cell that connects to other cells — grew new branches. When the activity was poorly synchronized, axon branches were instead eliminated.

“That tells us that when these cells fire together, associations are strengthened,” said Liang Liang, co-senior author of the study and an assistant professor of neuroscience at Yale School of Medicine. “The branching of axons allows more connections to be made between the retinal ganglion cell and the neurons sharing the synchronized activity in the superior colliculus circuit.”

This finding follows what’s known as “Hebb’s rule,” an idea put forward by psychologist Donald Hebb in 1949; at that time Hebb proposed that when one cell repeatedly causes another cell to fire, the connections between the two are strengthened.

“Hebb’s rule is applied quite a lot in psychology to explain the brain basis of learning,” said Crair, who is also the vice provost for research and a professor of ophthalmology and visual science. “Here we show that it also applies during early brain development with subcellular precision.”

In the new study, the researchers were also able to determine where on the cell branch formation was most likely to occur, a pattern that was disrupted when the researchers disturbed synchronization between the cell and the spontaneous waves.

Spontaneous activity occurs during development in several other neural circuits, including in the spinal cord, hippocampus, and cochlea. While the specific pattern of cellular activity would be different in each of those areas, similar rules may govern how cellular wiring takes place in those circuits, said Crair.

Going forward, the researchers will explore whether these patterns of axon branching persist after a mouse’s eyes open and what happens to the downstream connected neuron when a new axon branch forms.

“The Crair and Liang labs will continue to combine our expertise in brain development and single-cell imaging to examine how the assembly and refinement of brain circuits is guided by precise patterns of neural activity at different developmental stages,” said Liang.

The research was supported in part by the Kavli Institute of Neuroscience at Yale School of Medicine.

Incentivising climate action and innovation in the corporate world is essential says co-author Dr Matilda Becker: “Of the 2000 largest companies, close to half still do not yet have a net zero target, while some are going further without reward. We need to incentivise companies’ efforts beyond their boundaries.”

The authors discuss actions that companies can take to accelerate the global transition to net zero across three spheres of influence: product power, purchasing power and political power, and propose an additional reporting track to capture their impact in these areas. This track would demonstrate a company’s wider contribution to global net zero, and examples could include lobbying for cleaner energy systems or signalling financial support for new net zero technologies.

To date, corporate climate standards have been created primarily to guide companies in setting targets (e.g. through the Science Based Targets initiative) and to help them track their own emissions resulting from their activities (e.g. using the Greenhouse Gas Protocol). While these standards have been essential for reducing the emissions of individual companies, say the authors, they fail to incentivise broader climate action and can even discourage it.

“It is essential that companies report and reduce emissions across their value chains,” says co-author Claire Wigg, Head of Climate Performance Practice at the Exponential Roadmap Initiative. “But it is also essential that they drive — and are rewarded for driving — systemic change via the products they produce, the purchases they make and the policies they lobby for or against.”

“The way standards are currently set up, a high-growth renewable energy company might fare poorly because of the emissions generated in making turbines and solar panels, despite the fact these products can help to reduce emissions globally,” explains lead author Kaya Axelsson, Research Fellow and Head of Policy and Partnerships at the Smith School. “We need a way to compare and reward companies that are changing the world, not just their operations.”

Psychologists wanted to study “earworms,” the types of songs that get stuck in your head and play automatically on a loop. So they asked people to sing out any earworms they were experiencing and record them on their phones when prompted at random times throughout the day. When researchers analyzed the recordings, they found that a remarkable proportion of them perfectly matched the pitch of the original songs they were based upon.

More specifically, 44.7% of recordings had a pitch error of 0 semitones, and 68.9% were accurate within 1 semitone of the original song. These findings were recently published in the journal Attention, Perception, & Psychophysics.

“What this shows is that a surprisingly large portion of the population has a type of automatic, hidden ‘perfect pitch’ ability,” said Cognitive Psychology Ph.D. candidate Matt Evans, who led the study with support from Psychology Professor Nicolas Davidenko and undergraduate research assistant Pablo Gaeta.

“Interestingly, if you were to ask people how they thought they did in this task, they would probably be pretty confident that they had the melody right, but they would be much less certain that they were singing in the right key,” Evans said. “As it turns out, many people with very strong pitch memory may not have very good judgment of their own accuracy, and that may be because they don’t have the labeling ability that comes with true perfect pitch.”

Evans explained that true perfect pitch is the ability to accurately produce or identify a given note on the first try and without a reference pitch. Less than 1 in 10,000 people possess that ability, with the list including famed musicians like Ludwig van Beethoven, Ella Fitzgerald, and Mariah Carey. But, scientists are increasingly finding that accurate pitch memory is much more common.

Prior research has shown that participants in laboratory settings who are asked to recall a well-known song and sing it from memory end up singing it in the right key at least 15% of the time, which is much more often than could be expected by chance. But there are still a lot of unknowns about how this memory process works, and that included questions about whether it took deliberate effort for people to recall songs in the right key, or if it happened automatically.

That’s where earworms came in handy. Because earworms are a type of musical memory experience that happens involuntarily, the UC Santa Cruz team decided to use them to test whether pitch memory was still relatively accurate when music wasn’t being recalled purposefully. The team’s findings that earworms did in fact very strongly follow the key of the original song suggests that there may be something unique about musical memories and the ways they are encoded and maintained inside our brains.

“People who study memory often think about long-term memories as capturing the gist of something, where the brain takes shortcuts to represent information, and one way our brains could try to represent the gist of music would be to forget what the original key was,” explained Professor Davidenko. “Music sounds very similar in different keys, so it would be a good shortcut for the brain to just ignore that information, but it turns out that it’s not ignored. These musical memories are actually highly accurate representations that defy the typical gist formation that happens in some other domains of long-term memory.”

As researchers continue working to unpack the mechanisms behind musical memory, Evans says he hopes the current findings will also help more people have the confidence to participate in music. He noted that the pitch accuracy of participants in the study was not predicted by any objective measures of singing ability, and none of the participants were musicians or reported having perfect pitch. In other words, you don’t have to have special abilities to demonstrate this foundational musical skill.

“Music and singing are uniquely human experiences that so many people don’t allow themselves to engage with because they don’t think they can, or they’ve been told they can’t,” Evans said. “But in reality, you don’t have to be Beyonce to have what it takes to make music. Your brain is already doing some of it automatically and accurately, despite that part of you that thinks you can’t.”