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New tensor network-based approach could advance simulation of quantum many-body systems

The quantum many body problem has been at the heart of much of theoretical and experimental physics over the past few decades. Even though we have understood the fundamental laws that govern the behavior of elementary particles for almost a century, the issue is that many interesting phenomena are the result of the complex collective behavior of many interacting quantum particles. In the words of condensed matter theorist Philip W. Anderson: “More is different.”

Since simulating models with this many degrees of freedom exactly is entirely intractable computationally, approximations such as have been widely used to gain insight into their behavior. However, this approach requires that the theory is close to non-interacting, which renders it unusable in many cases of physical interest.

More recently, an approach based on insights from has shown great promise for tackling these non-perturbative regimes. It was understood that the low-energy quantum states of local models display relatively little entanglement compared to generic quantum states, a feature that is exploited in tensor network methods.

Pianists’ subtle finger movements influence variations in timbre, according to new study

While it is known that auditory characteristics like loudness and tempo are associated with the physical movements of musicians, more subtle features, like timbre (also known as the “tone color” or tonal quality), are not as well understood.

‘Invisible’ asteroids near Venus may threaten Earth in the future

An international study led by researchers at São Paulo State University (UNESP) in Brazil has identified a little-known but potentially significant threat: Asteroids that share Venus’s orbit and may completely escape current observational campaigns because of their position in the sky. These objects have not yet been observed, but they could strike Earth within a few thousand years. Their impacts could devastate large cities.

“Our study shows that there’s a population of potentially dangerous asteroids that we can’t detect with current telescopes. These objects orbit the sun, but aren’t part of the asteroid belt, located between Mars and Jupiter. Instead, they’re much closer, in resonance with Venus. But they’re so difficult to observe that they remain invisible, even though they may pose a real risk of collision with our planet in the distant future,” astronomer Valerio Carruba, a professor at the UNESP School of Engineering at the Guaratinguetá campus (FEG-UNESP) and first author of the study, told Agência FAPESP.

The study is published in the journal Astronomy & Astrophysics. The work combined analytical modeling and long-term to track the dynamics of these objects and assess their potential to come dangerously close to Earth.

Pest resistance threatens corn industry’s newest biotech defense, study warns

Corn rootworms, pests responsible for billions of dollars in yearly crop losses, are evolving resistance that weakens even the latest biotechnology controls, according to a new study published in the journal Proceedings of the National Academy of Sciences.

Drawing on decades of data across multiple states, University of Arizona entomologists found that field-evolved to Bacillus thuringiensis, or Bt, is undermining the effectiveness of corn that targets rootworms with the combination of Bt and RNA interference, or RNAi, a new biotech control that turns the rootworms’ own genetic instructions against them.

The research team analyzed extensive field data collected over the past two decades in 12 previous studies, including millions of rootworms evaluated across the Corn Belt, which extends from western Ohio to eastern Nebraska and northeastern Kansas.

Physics-based algorithm enables nuclear microreactors to autonomously adjust power output

A new physics-based algorithm clears a path toward nuclear microreactors that can autonomously adjust power output based on need, according to a University of Michigan-led study published in Progress in Nuclear Energy.

Easily transportable and able to generate up to 20 megawatts of thermal energy for heat or electricity, nuclear microreactors could be useful in such as , disaster zones, or even cargo ships, in addition to other applications.

If integrated into an , nuclear microreactors could provide stable, carbon-free energy, but they must be able to adjust to match shifting demand—a capability known as load following. In large reactors, staff make these adjustments manually, which would be cost-prohibitive in remote areas, imposing a barrier to adoption.

Advanced sensors peer inside the ‘black box’ of metal 3D printing

With the ability to print metal structures with complex shapes and unique mechanical properties, metal additive manufacturing (AM) could be revolutionary. However, without a better understanding of how metal AM structures behave as they are 3D printed, the technology remains too unreliable for widespread adoption in manufacturing and part quality remains a challenge.

Researchers in Lawrence Livermore National Laboratory (LLNL)’s nondestructive evaluation (NDE) group are tackling this challenge by developing first-of-their-kind approaches to look at how materials and structures evolve inside a AM structure during printing. These NDE techniques can become enabling technologies for metal AM, giving manufacturers the data they need to develop better simulations, processing parameters and predictive controls to ensure part quality and consistency.

“If you want people to use metal AM components out in the world, you need NDE,” said David Stobbe, group leader for NDE ultrasonics and sensors in the Materials Engineering Division (MED). “If we can prove that AM-produced parts behave as designed, it will allow them to proliferate, be used in safety-critical components in aerospace, energy and other sectors and hopefully open a new paradigm in manufacturing.”

Beyond BMI: Analysis links fat distribution to distinct brain aging patterns

Research led by The Hong Kong Polytechnic University finds that regional fat distribution exerts distinct effects on brain structure, connectivity and cognition, revealing patterns not explained by body mass index (BMI).

Obesity has been associated with structural and functional changes in the brain, including reductions in , disruptions in white matter and impaired connectivity, which have been associated with cognitive decline.

Previous studies frequently used BMI as the central measure of obesity, a highly generalized metric that cannot capture the biological differences in fat depots. Adipose tissue in different body regions is known to affect metabolic and inflammatory pathways differently, and earlier work has suggested that visceral (around organs in the ) and leg fat contribute unequally to disease risk.

Drinking any amount of alcohol likely increases dementia risk

Drinking any amount of alcohol likely increases the risk of dementia, suggests the largest combined observational and genetic study to date, published in BMJ Evidence-Based Medicine.

Even light drinking—generally thought to be protective, based on observational studies—is unlikely to lower the risk, which rises in tandem with the quantity of alcohol consumed, the research indicates.

Current thinking suggests that there might be an “optimal dose” of alcohol for brain health, but most of these studies have focused on and/or didn’t differentiate between former and lifelong non-drinkers, complicating efforts to infer causality, note the researchers.

Through multiplexed theta waves, brain’s place cells navigate using both external and internal cues

Place cells are specialized neurons in a brain region known as the hippocampus, which have been found to fire when animals are in specific locations. These cells don’t fire randomly, but their activity is known to be organized by theta oscillations, which in rats means that they fire in sync with rhythmic brain waves between 7–9 Hz.

While many past studies have explored the role and firing patterns of place cells, the extent to which their activity is influenced by different types of spatial cues has not yet been fully elucidated. Spatial cues are essentially pieces of information that help animals and humans to determine where they are and where they should head toward to reach a desired location.

Researchers at Johns Hopkins University gathered new experimental evidence suggesting that the multiplexed theta phase coding of place cells, or, in other words, their ability to tackle different tasks in the same “wave” of theta rhythm activity, is controlled by external (i.e., allothetic) and self-motion-related (i.e., idiothetic) spatial cues.

People’s neural responses while watching videos predict whether they will become friends in the future, study finds

Throughout the course of their lives, people typically encounter numerous other individuals with different interests, values and backgrounds. However, not all these individuals will become their good friends, life partners, or meaningful people in their lives.

Many past psychology and behavioral science studies investigated the relationships between different people and what contributes to their perceived affinity to others. While some of these studies linked friendship to physical proximity, interpersonal similarities and other factors, the associated with between people have not yet been fully elucidated.

Researchers at University of California Los Angeles (UCLA) and Dartmouth College recently carried out a study exploring the possibility that people who end up becoming friends exhibit similar neural activity patterns. Their findings, published in Nature Human Behavior, suggest that people are in fact drawn to others who exhibit similar emotional and mental responses to their surroundings.

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