Kibble-Zurek Mechanism for Nonequilibrium Phase Transitions

The Kibble-Zurek (KZ) mechanism, confirmed experimentally only for equilibrium phase transitions, is also applicable for non-equilibrium phase transitions, as is now shown by Tokyo Tech researchers in a landmark study. The KZ mechanism is characterized by the formation of topological defects during continuous phase transition away from the adiabatic limit. This breakthrough finding could open the doors to investigation of the mechanism for other nonequilibrium phase transitions.

Phase transitions describe various phenomena around us, from water turning into ice to magnetic transitions to the superconducting transition where electrical resistance vanishes. In the cases of superconductivity and magnetism, the phase transition is continuous, characterized by "symmetry breaking" that leads to the formation of an ordered state. The ordered state is perfect (defect-free) when this transition is very slow, a regime called the "adiabatic limit". However, for transitions not satisfying this limit, there appear topological defects, whose generation is described by the Kibble-Zurek (KZ) mechanism. Experimentally, the KZ mechanism manifests as a power-law dependence of the defect density on the cooling rate.

Interestingly, the KZ mechanism, while widely studied for phase transitions at thermal equilibrium, has not yet been demonstrated experimentally for nonequilibrium phase transitions. However, a recent simulation study has suggested that the KZ mechanism can be applied to dynamical ordering transitions between disordered and ordered flow states, a phenomenon that can be experimentally tested in superconducting vortex systems.

Sex roles in the animal kingdom are driven by the ratio of females to males

A female (left) and a male (right) red-fronted lemur with an infant (center).
Photo Credit: Louise Peckre

How picky should females and males be when they choose a mate? How fiercely should they compete for mates? And how much should they engage in raising their offspring? The answers to these questions largely depend on the ratio of adult females to males in the social group, population or species. This is the conclusion of a review by a scientific team with the participation of the German Primate Center – Leibniz Institute for Primate Research (DPZ), the Max Planck Institute for Biological Intelligence, in foundation, and the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW). The paper is published in the journal Biological Reviews.

In species with separate sexes, females and males often differ in their morphology, physiology and behavior. Such sex-specific adaptations imply differences between females and males in the degree of mate competition, mate choice and parental care. Empirical research showed that females generally tend to be choosier than males about whom to mate with, and males are more likely than females to compete for mating opportunities. This pattern is often referred to as “conventional” sex roles. But the opposite pattern (“reversed” sex roles) also exists and there generally is a lot of variation in sex roles both between and within species. How can this surprisingly large variation in sex roles be explained? The team led by Peter Kappeler from the German Primate Center now reviewed the sex roles literature in animals and found that the ratio of adult males to females in a population likely is a strong evolutionary driver of sex roles. The scientific paper also identifies unanswered questions and proposes research that can lead to a better understanding of sexual selection and the evolution of sex roles.

Automated chemical reaction prediction: now in stereo

The AFIR method traces back the reaction of endiandric acid C methyl ester, a 52-atom natural product, to its starting materials using only quantum chemical calculations.
Illustration Credit: Tsuyoshi Mita et al. JACS. November 30, 2022

Automated reaction path search method predicts accurate stereochemistry of pericyclic reactions using only target molecule structure.

Researchers at the Institute for Chemical Reaction Design and Discovery (WPI-ICReDD) have demonstrated the expanded use of a computational method called the Artificial Force Induced Reaction (AFIR) method, predicting pericyclic reactions with accurate stereoselectivity based only on information about the target product molecule. The accurate prediction of a molecule’s stereochemistry—i.e., the 3D arrangement of its constituent atoms—is unprecedented for such an automated reaction path search method. This study serves as proof of concept that the AFIR method has the potential to discover novel reactions with specific stereochemistry.

In this study, AFIR is used to calculate retrosynthetic, or reverse, reactions going from product molecules to starting materials. Previously, AFIR has been used to predict small, simple reactions, but accurate stereochemistry predictions were out of reach, limiting the technique’s applicability. In this study, researchers overcome this hurdle by using the AFIR method on a major class of chemical reactions called pericyclic reactions, which are commonly found in biological processes, including the synthesis of Vitamin D.

Small asteroids are probably young

Simulation of the SCI impact. a) – c) Snapshots of the simulation at different times. At t = 1200s, the development of the crater is over. d) SCI crater on the asteroid Ryugu. The key characteristics of the observed crater, including the displacement of the boulders, are recreated in the simulation.
Credit: Courtesy of Martin Jutzi

The impact experiment conducted on the asteroid Ryugu by the Japanese Hayabusa2 mission which took place two years ago resulted in an unexpectedly large crater. With the use of simulations, a team led by the University of Bern and the National Center of Competence in Research (NCCR) PlanetS has recently succeeded in gaining new insights from the experiment regarding the formation and development of asteroids. These insights are also important for the DART mission of NASA.

The Hayabusa2 spacecraft was developed in order to study the history of the asteroid Ryugu, and collected samples and returned them to earth for laboratory analysis. The project participants are Dr. Martin Jutzi and Dr. Sabina Raducan, both from the Physical Institute of the University of Bern, Department for Space Research and Planetology (WP), and are members of the National Center of Competence in Research (NCCR) PlanetS. Under their leadership, in a study which has recently been published in Nature Communications, the team has presented new findings on the formation and development of asteroids.

New quantum computing feat is a modern twist on a 150-year-old thought experiment

UNSW Sydney research demonstrates a 20x improvement in resetting a quantum bit to its ‘0’ state, using a modern version of the ‘Maxwell’s demon’.

A team of quantum engineers at UNSW Sydney has developed a method to reset a quantum computer – that is, to prepare a quantum bit in the ‘0’ state – with very high confidence, as needed for reliable quantum computations. The method is surprisingly simple: it is related to the old concept of ‘Maxwell’s demon’, an omniscient being that can separate a gas into hot and cold by watching the speed of the individual molecules.

“Here we used a much more modern ‘demon’ – a fast digital voltmeter – to watch the temperature of an electron drawn at random from a warm pool of electrons. In doing so, we made it much colder than the pool it came from, and this corresponds to a high certainty of it being in the ‘0’ computational state,” says Professor Andrea Morello of UNSW, who led the team.

“Quantum computers are only useful if they can reach the final result with very low probability of errors. And one can have near-perfect quantum operations, but if the calculation started from the wrong code, the final result will be wrong too. Our digital ‘Maxwell’s demon’ gives us a 20x improvement in how accurately we can set the start of the computation.”

Common Veterinary Drugs Show Effectiveness Against Bed Bugs

Fluralaner and ivermectin were tested for their effectiveness in killing bed bugs.
Photo Credit: Courtesy of Coby Schal and Maria Gonzalez-Morales.

Two common drugs used by veterinarians to combat parasites may be effective against bed bugs, with one showing especially strong potential, according to a new study from North Carolina State University that examined the drugs in the context of controlling resurgent bed bug populations on poultry farms.

Fluralaner and ivermectin, which are used to kill fleas and ticks on household pets like dogs and cats, among other uses, were tested for their effectiveness in killing bed bugs. In a collaboration between entomologists and veterinary scientists from NC State’s College of Veterinary Medicine, researchers tested bed bug mortality rates in different experiments: after the pests consumed blood mixed with the drugs on the lab bench and after bed bugs bit and fed off chickens that had either ingested or received topical treatment with the drugs.

Fluralaner is a relatively new, longer-lasting anti-parasitic drug used mostly for companion animals; however, Europe and Australia have approved its use for the poultry industry. Besides household pet uses, ivermectin effectively serves anti-parasitic uses in human populations, particularly in Africa, as well as in larger animals.

Gut Microbes Influence Binge-Eating of Sweet Treats in Mice

Sarkis Mazmanian, Luis B. and Nelly Soux Professor of Microbiology
Photo Credit: Caltech

We have all been there. You just meant to have a single Oreo as a snack, but then you find yourself going back for another, and another, and before you know it, you have finished off the entire package even though you were not all that hungry to begin with.

But before you start feeling too guilty for your gluttony, consider this: It might not be entirely your fault. Now, new research in mice shows that specific gut bacteria may suppress binge eating behavior.

Oreos and other desserts are examples of so-called "palatable foods"—food consumed for hedonistic pleasure, not simply out of hunger or nutritional need. Humans are not alone in enjoying this kind of hedonism: Mice like to eat dessert, too. Even when they have just eaten, they will still consume sugary snacks if available.

The new Caltech study shows that the absence of certain gut bacteria causes mice to binge eat palatable foods: Mice with microbiotas disrupted by oral antibiotics consumed 50 percent more sugar pellets over two hours than mice with gut bacteria. When their microbiotas were restored through fecal transplants, the mice returned to normal feeding behavior. Further, not all bacteria in the gut are able to suppress hedonic feeding, but rather specific species appear to alter the behavior. Bingeing only applies to palatable foods; mice with or without gut microbiota both still eat the same amount of their regular diet. The findings show that the gut microbiota has important influences on behavior and that these effects can be modulated when the microbiota is manipulated.

Major fires an increasing risk as the air gets thirstier, research shows

Researchers examined global climate and fire records for the world’s forests over the last 20 years, linking fire activity and a measure of the atmosphere’s thirst.
Photo Credit: Mike Newbry

Greater atmospheric demand for water means a dramatic increase in the risk of major fires in global forests unless we take urgent and effective climate action, new research finds.

Published in Nature Communications, researchers have examined global climate and fire records in all of the world’s forests over the last 20 years.

The researchers found that in all kinds of forests, there is a strong link between fire activity and vapor pressure deficit (VPD), which is a measure of the atmosphere’s thirst.

VPD is calculated from temperature and humidity. It describes the difference between how much moisture there is in the air, and how much moisture the air can hold when it’s saturated (which is when dew forms.) The greater this difference, or deficit, the greater the air’s drying power on fuels.

Importantly, warmer air can hold more water, which means that VPD increases – and fuels will dry out more often – with rising temperatures due to climate change.

Neurotic personality trait a key risk factor for stress perception

While all of the “Big Five” personality traits – agreeableness, conscientiousness, extraversion, neuroticism and openness – are related to experiencing stress, neuroticism showed the strongest link, according to research co-written by Bo Zhang, a professor of labor and employment relations and of psychology at Illinois. 
Photo Credit: Fred Zwicky

A new paper co-written by a team of University of Illinois Urbana-Champaign experts who study the science of personalities points to the important role of personality traits to account for individual differences in experiencing stress.

In a meta-analysis synthesizing more than 1,500 effect sizes from about 300 primary studies, the team showed that while all of the “Big Five” personality traits – agreeableness, conscientiousness, extraversion, neuroticism and openness – are related to experiencing stress, neuroticism showed the strongest link, said Bo Zhang, a professor of labor and employment relations and of psychology at Illinois and a co-author of the paper.

“Stress is a significant mental and physical health issue that affects many people and many important domains of life, and some individuals are more likely to experience or perceive stress disproportionately or more intensely than others, which can then play a role in mental and physical health problems such as anxiety or depression,” he said. “We found that individuals high in neuroticism” – a heightened tendency toward negative affect as well as an exaggerated response to threat, frustration or loss – “demonstrated a relationship with both stressor exposure and perceived stress that was stronger than the other four personality traits.”

Strongest Arctic cyclone on record led to surprising loss of sea ice

A ship-based view of the Arctic Ocean in October 2015, when the ocean’s surface is beginning to freeze. In January, when the massive 2022 cyclone occurred, large sections of the Arctic Ocean would be covered in a layer of sea ice.
Photo Credit: Ed Blanchard-Wrigglesworth/University of Washington

A warming climate is causing a decline in sea ice in the Arctic Ocean, where loss of sea ice has important ecological, economic and climate impacts. On top of this long-term shift due to climate change are weather events that affect the sea ice from week to week.

The strongest Arctic cyclone ever observed poleward of 70 degrees north latitude struck in January 2022 northeast of Greenland. A new analysis led by the University of Washington shows that while weather forecasts accurately predicted the storm, ice models seriously underestimated its impact on the region’s sea ice.

The study, published in October in the Journal of Geophysical Research–Atmospheres, suggests that existing models underestimate the impact of big waves on ice floes in the Arctic Ocean.

“The loss of sea ice in six days was the biggest change we could find in the historical observations since 1979, and the area of ice lost was 30% greater than the previous record,” said lead author Ed Blanchard-Wrigglesworth, a research assistant professor of atmospheric sciences at the UW. “The ice models did predict some loss, but only about half of what we saw in the real world.”

Fertilizing the Ocean to Store Carbon Dioxide

Seeding the oceans with nano-scale fertilizers could create a much-needed, substantial carbon sink.
  Illustration Credit: Stephanie King | Pacific Northwest National Laboratory

The urgent need to remove excess carbon dioxide from Earth’s environment could include enlisting some of our planet’s smallest inhabitants, according to an international research team led by Michael Hochella of the Department of Energy’s Pacific Northwest National Laboratory.

Hochella and his colleagues examined the scientific evidence for seeding the oceans with iron-rich engineered fertilizer particles near ocean plankton. The goal would be to feed phytoplankton, microscopic plants that are a key part of the ocean ecosystem, to encourage growth and carbon dioxide (CO2) uptake. The analysis article appears in the journal Nature Nanotechnology.

“The idea is to augment existing processes,” said Hochella, a Laboratory fellow at Pacific Northwest National Laboratory. “Humans have fertilized the land to grow crops for centuries. We can learn to fertilize the oceans responsibly.”

A pair of lizard ‘kings’ from the old, old West

This photograph shows two blocks containing the holotype of Microteras borealis. It consists of a portion of the snout (left) and the braincase (right).
Resized Image using AI by SFLORG
Photo Credit: Courtesy of the Yale Peabody Museum of Natural History

Yale researchers have identified the oldest-known, definitive members of the lizard crown group that includes all living lizards and their closest extinct relatives.

The two new species, Eoscincus ornatus and Microteras borealis, fill important gaps in the fossil record and offer tantalizing clues about the complexity and geographic distribution of lizard evolution. The new lizard “kings” are described in a study published in Nature Communications.

“This helps us time out the ages of the major living lizard and snake groups, as well as when their key anatomical features originated,” said Chase Brownstein, first author of the study. Brownstein, a Yale senior, collaborated on the study with Yale paleontologists Jacques Gauthier and Bhart-Anjan S. Bhullar.

Gauthier is a professor of Earth and planetary sciences in Yale’s Faculty of Arts and Science and curator at the Yale Peabody Museum of Natural History. Bhullar is an associate professor of Earth & planetary sciences and an associate curator at the Peabody Museum.

The brain's immune cells can be triggered to slow down Alzheimer's disease

Joana B. Pereira, researcher at Lund University and Karolinska Institutet who is first author of the study.
Photo Credit: Courtesy of Lund University

The brain's big-eating immune cells can slow down the progression of Alzheimer's disease. This is shown by a study that is now published in Nature Aging.

The brain's own immune cells are called microglia and are found in the central nervous system. They are big eaters that kill viruses, damaged cells and infectious agents they come across. It has long been known that microglial cells can be activated in different ways in several neurological diseases such as Alzheimer's and Parkinson's diseases. Depending on how they are activated, they can both drive and slow disease development. Researchers from Lund University and Karolinska Institutet have now shown that a certain type of activation of the microglial cells triggers inflammatory protective mechanisms in the immune system:

“Most people probably think that inflammation in the brain is something bad and that you should inhibit the inflammatory system in case of illness. But inflammation doesn't just have to be negative”, says Joana B. Pereira, researcher at Lund University and Karolinska Institutet who is first author of the study.

Machine learning model builds on imaging methods to better detect ovarian lesions

(From left) The top row shows an ultrasound image of a malignant lesion, the blood oxygen saturation, and hemoglobin concentration. The bottom row is an ultrasound image of a benign lesion, the blood oxygen saturation, and hemoglobin concentration.
Image Credit: Zhu lab

Although ovarian cancer is the deadliest type of cancer for women, only about 20% of cases are found at an early stage, as there are no real screening tests for them and few symptoms to prompt them. Additionally, ovarian lesions are difficult to diagnose accurately — so difficult, in fact that there is no sign of cancer in more than 80% of women who undergo surgery to have lesions removed and tested.

Quing Zhu, the Edwin H. Murty Professor of Biomedical Engineering at Washington University in St. Louis’ McKelvey School of Engineering, and members of her lab have applied a variety of imaging methods to diagnose ovarian cancer more accurately. Now, they have developed a new machine learning fusion model that takes advantage of existing ultrasound features of ovarian lesions to train the model to recognize whether a lesion is benign or cancerous from reconstructed images taken with photoacoustic tomography. Machine learning traditionally has been focused on single modality data. Recent findings have shown that multi-modality machine learning is more robust in its performance over unimodality methods. In a pilot study of 35 patients with more than 600 regions of interest, the model’s accuracy was 90%.

To Battle Climate Change, Scientists Tap into Carbon-Hungry Microorganisms for Clues

Electron microscopy images of 7-nanometer-diameter copper nanoparticles (shown left) and silver nanoparticles (center). At right: Electron microscopy image of ultrathin material synthesized from copper and silver nanoparticles, which could potentially be coupled with light-absorbing silicon nanowires for the design of efficient artificial photosynthesis systems. 
Credit: Peidong Yang/Berkeley Lab; courtesy of Nature Catalysis

Scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) have demonstrated a new technique, modeled after a metabolic process found in some bacteria, for converting carbon dioxide (CO2) into liquid acetate, a key ingredient in “liquid sunlight” or solar fuels produced through artificial photosynthesis.

The new approach, reported in Nature Catalysis, could help advance carbon-free alternatives to fossil fuels linked to global warming and climate change.

The work is also the first demonstration of a device that mimics how these bacteria naturally synthesize acetate from electrons and CO2.

“What’s amazing is that we learned how to selectively convert carbon dioxide into acetate by mimicking how these little microorganisms do it naturally,” said senior author Peidong Yang, who holds titles of senior faculty scientist in Berkeley Lab’s Materials Sciences Division and professor of chemistry and materials science and engineering at UC Berkeley.