Fermions are among the most important particles in physics and include both everyday electrons and more exotic variants. Chiral fermions, like gloves, come in left- and right-handed versions and were proposed over a century ago. While high-energy neutrinos—the leading candidates for massless chiral fermions—proved to have mass, nearly (semi-) metallic solid-state crystals were discovered 15 years ago to host electronic versions of massless chiral fermions.
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Mice that watch fights come away battle-ready
People love to watch violent things. From slasher films to boxing, there’s some intrinsic appeal to watching people get pummeled. The dystopian thriller “Squid Game,” for instance, debuted in 2021 and in three years racked up 330 million streams totaling more than 2.8 billion hours viewed. Even monkeys pay more attention to videos of other monkeys fighting.
Now, researchers at Princeton University have found that there may be something useful gained from all this watching: being better prepared if you find yourself in a similar situation.
In a new paper, Princeton neuroscientists reveal that male mice that merely watched other males fight were better prepared fighters themselves without being any meaner or more aggressive than other mice. Their brains changed in many of the same ways, too, as those of mice with actual fighting experience.
How neurons in the hippocampus separate different aspects of experiences
When remembering an experience, people often recall not just where it happened, but also its timing and how it unfolded over time. This helps them to recall sequences of events and associations that can guide their actions in new scenarios.
Memories of events, their timing and the order they occurred in are known to be encoded by the hippocampus. This is a structure located deep inside the brain that plays a key role in memory, the regulation of emotions and spatial navigation.
Past research showed that some neurons in the hippocampus, called place cells, become active when people are in specific locations. These neurons can also respond to other features of an event or experience.
Key gene preserves lifelong supply of stem cells that make bone healing possible, study suggests
The action of a key gene is required to maintain a lifelong supply of stem cells that make bone healing possible, a new study finds.
These immature cells are known to get the signal to either continually divide to make more copies of themselves (self-renewal) as a ready pool of replacements, or to mature into cells with a specific function like bone-building. Once they mature, they generally cannot reverse the process, so the supply of stem cells is limited. Such pools become even more depleted as people age.
Led by NYU Langone Health researchers, the new work identified the gene HOXA10 as a lifelong protector of the stem cell supplies, keeping them from maturing into bone-building cells called osteoblasts until needed for healing.
New CRISPR proteins expand editing access to heart disease genes
Rice University’s Han Xiao has used his AI-supported Sequence Display technology to expand the targeting abilities of CRISPR/Cas9. In a paper recently published in Nature Communications, Xiao evolved several variants of a compact Cas9 that could efficiently target stretches of DNA previously inaccessible for editing. The research included a proof-of-concept study in which the evolved Cas9s were successfully used to edit two genes found in coronary heart disease.
“My team used Sequence Display technology to evolve a compact Cas9 that can efficiently target priority areas of DNA,” said Xiao, a professor of chemistry and corresponding author on this paper. “This shows the power of our approach, which rapidly generates large datasets that AI can use to identify optimal protein sequences for a given function. In this case, it allowed us to evolve several new Cas9 variants with better activities.”
A new superinductor created within a silicon integrated circuit
A recent study published in Nature Electronics and carried out by researchers from nanoGUNE’s Quantum Hardware research group, Quantum Motion, London Center for Nanotechnology, Imperial College London and the University of Cambridge introduces a new superinductor created within a silicon integrated circuit fabricated in a commercial complementary metal–oxide–semiconductor (CMOS) process.
Superinductors are electrical inductors that are engineered to have an extremely large inductance, often far beyond what can be achieved with conventional coils. They are particularly important for superconducting qubits and quantum circuits, as a large inductance can dramatically alter the circuit’s quantum behavior. This makes superinductors interesting for quantum technology, as they enable the creation of circuits with very large impedance and very small inductive energy scales.
In this work, researchers show that superconducting circuit elements can be fabricated with a commercial CMOS process by utilizing titanium nitride (TiN). TiN is particularly well suited for this purpose because of its high kinetic inductance, which makes it possible to create compact, high-inductance circuit elements while maintaining robust superconducting properties.
A carefully timed pair of light pulses can amplify the motion of atomic layers in a quantum material
The principle “Work smarter, not harder!” apparently also applies to controlling quantum materials with light. Many of their fascinating properties depend on how the atoms are arranged in the crystal. Ultrashort laser pulses can be used to alter these structures in a targeted way—the light first excites electrons, whose changed energy and dynamics exert forces on the atomic nuclei and can thereby set the atoms in motion. Such processes unfold within femtoseconds, a millionth of a billionth of a second.
In a study now published in Nature Physics, researchers from the Universities of Würzburg and Rostock and from ETH Zurich investigated this mechanism in WTe₂, a so-called sliding ferroelectric. In such materials, neighboring atomic layers can slide against each other, much like two palms pressed together.
“What makes this particularly exciting is that the relative motion of the atomic layers can influence a range of material properties, such as ferroelectricity and topology,” explains Gerrit Horstmann, first author of the study and head of an Emmy Noether junior research group at the University of Würzburg.
A new route to calculating gluon production in proton–nucleus collisions
In the theoretical study of proton-nucleus collisions, the colliding projectiles can be described as streams of color charges moving along their respective trajectories. These color charges couple to gluons, which then produce the particles that are observed in the final state (gluons and quarks, which eventually produce hadrons).
The traditional approach for carrying out these calculations has been to solve the equations that drive the gluon field (known as the Yang-Mills equations) in terms of the color sources. This solution is then used in order to calculate the probability of obtaining a given final state. A major complication with this approach comes from the fact that these solutions are not unique: There are infinitely many of them that nevertheless describe the same physical situation (they are related by gauge transformations). This complication implies that a lot of effort is spent calculating terms that do not contribute to physical observables in the end.
In a new study published in the Journal of High Energy Physics, François Gélis, a physicist at IPhT, started from the observation that solutions of the Yang-Mills equations are in fact sums of tree Feynman graphs. Using this analogy, he was able to apply to this problem methods that were originally developed for scattering amplitudes.
Five things to know about guiding sound for better communication
Every time someone picks up a call, the phone does a quiet bit of translation. Incoming radio signals are converted into tiny sound waves that ripple across chips before being turned back into data.
“Those waves are useful but unruly,” says physicist A.T. Charlie Johnson of the School of Arts and Sciences. Imperfections in the material, he explains, can bounce waves backward or send them off course, and every stray reflection hampers the signal.
Now, researchers led by Johnson with collaborators at the University of Texas at Austin have developed a device that keeps those waves on track. Their findings are published in Physical Review Applied.
Chatbots with personality? How AI describes itself and judges us
Texts generated by large language models, or AI-powered chatbots, exhibit characteristic “personality” traits. Such chatbots can also identify individual personality traits in texts. However, humans are more reliable at distinguishing between human-written and AI-generated texts, according to researchers at the Institute of Psychology at Johannes Gutenberg University Mainz (JGU).
“Chatbots are becoming part of more and more areas of our lives, from customer service and digital counseling services to personal chatbots that many people already use every day and even share their feelings with,” said Sophie Körner, a research associate in the Department of Personality Psychology and Psychological Assessment at JGU and lead author of the study published in Scientific Reports. “That is why we need to understand how we perceive chatbot-generated texts and whether we can still distinguish them from human-written texts.”