Custom ‘Headphones’ Boost Atomic Radio Reception 100-Fold

Copper “headphones” boost the sensitivity of NIST’s atomic radio receiver, which is composed of a gas of cesium atoms prepared in a special state inside the glass container. When an antenna located above the setup sends down a radio signal, the headphones boost the strength of the received signal a hundredfold. 
Credit: NIST

Researchers at the National Institute of Standards and Technology (NIST) have boosted the sensitivity of their atomic radio receiver a hundredfold by enclosing the small glass cylinder of cesium atoms inside what looks like custom copper “headphones.”

The structure — a square overhead loop connecting two square panels — increases the incoming radio signal, or electric field, applied to the gaseous atoms in the flask (known as a vapor cell) between the panels. This enhancement enables the radio receiver to detect much weaker signals than before. The demonstration is described in a new paper in Applied Physics Letters.

The headphone structure is technically a split-ring resonator, which acts like a metamaterial — a material engineered with novel structures to produce unusual properties. “We can call it a metamaterials-inspired structure,” NIST project leader Chris Holloway said.

NIST researchers previously demonstrated the atom-based radio receiver. An atomic sensor has the potential to be physically smaller and work better in noisy environments than conventional radio receivers, among other possible advantages.

Discovery of 'ghost' fossils reveals plankton resilience to past global warming events

Ghost nannofossils (left) with virtual casts (right). The fossils are approximately 5 µm in length, 15 times narrower than the width of a human hair.
Credit: S.M Slater

An international team of scientists from UCL, the Swedish Museum of Natural History, the University of Florence and Natural History Museum have found a remarkable type of fossilization that has remained almost entirely overlooked until now.

The fossils are microscopic imprints, or “ghosts”, of single-celled plankton, called coccolithophores, that lived in the seas millions of years ago, and their discovery is changing our understanding of how plankton in the oceans are affected by climate change.

Coccolithophores are important in today’s oceans, providing much of the oxygen we breathe, supporting marine food webs, and locking carbon away in seafloor sediments. They are a type of microscopic plankton that surround their cells with hard calcareous plates, called coccoliths, and these are what normally fossilize in rocks.

Declines in the abundance of these fossils have been documented from multiple past global warming events, suggesting that these plankton were severely affected by climate change and ocean acidification.

Spinning is key for line-dancing electrons in iron selenide

Quantum physicists Pengcheng Dai (left) and Qimiao Si outside Rice’s Brockman Hall for Physics in November 2021.
Photo by Jeff Fitlow/Rice University

Rice University quantum physicists are part of an international team that has answered a puzzling question at the forefront of research into iron-based superconductors: Why do electrons in iron selenide dance to a different tune when they move right and left rather than forward and back?

A research team led by Xingye Lu at Beijing Normal University, Pengcheng Dai at Rice and Thorsten Schmitt at the Paul Scherrer Institute (PSI) in Switzerland used resonant inelastic X-ray scattering (RIXS) to measure the behavior of electron spins in iron selenide at high energy levels.

Spin is the property of electrons related to magnetism, and the researchers discovered spins in iron selenide begin behaving in a directionally dependent way at the same time the material begins exhibiting directionally dependent electronic behavior, or nematicity. The team’s results were published online this week in Nature Physics.

How seascapes of the ancient world shaped genetic structure of European populations

Reconstructed view of the burial caves of the Xaghra Circle (Libby Mulqueeney after an original by Caroline Malone). Source Malone et al.2009. Mortuary Customs in Prehistoric Malta.Cambridge: McDonald, pp 375, 377. Malone, C., Stoddart, S., Trump, D. & Bonanno, A. (eds.). 2009. Mortuary Customs in prehistoric Malta. Excavations at the Brochtorff Circle at Xaghra (1987-1994). Cambridge: McDonald Institute.

Trinity scientists, along with international colleagues, have explored the importance of sea travel in prehistory by examining the genomes of ancient Maltese humans and comparing these with the genomes of this period from across Europe. Previous findings from the archaeological team had suggested that towards the end of the third millennium BC the use of the Maltese temples declined.

Now, using genetic data from ancient Maltese individuals the current interdisciplinary research team has suggested a potential contributing cause. Researchers found that these ancient humans lacked some of the signatures of genetic changes that swept across Europe in this period, because of their island separation. Scientists concluded that physical topography, in particular seascapes played a central role as barriers to genetic exchange.

The study is just published in the journal Current Biology.

Unraveling a perplexing explosive process that occurs throughout the universe

Physicist Kenan Qu with images of fast radio burst in two galaxies.Top and bottom photos at left show the galaxies, with digitally enhanced photos shown at the right. Dotted oval lines mark burst locations in the galaxies.
Qu photo by Elle Starkman; galaxy photos courtesy of NASA; collage by Kiran Sudarsanan

Mysterious fast radio bursts release as much energy in one second as the Sun pours out in a year and are among the most puzzling phenomena in the universe. Now researchers at Princeton University, the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) and the SLAC National Accelerator Laboratory have simulated and proposed a cost-effective experiment to produce and observe the early stages of this process in a way once thought to be impossible with existing technology.

Producing the extraordinary bursts in space are celestial bodies such as neutron, or collapsed, stars called magnetars (magnet + star) enclosed in extreme magnetic fields. These fields are so strong that they turn the vacuum in space into an exotic plasma composed of matter and anti-matter in the form of pairs of negatively charged electrons and positively charged positrons, according to quantum electrodynamic (QED) theory. Emissions from these pairs are believed to be responsible for the powerful fast radio bursts.

Paleontologists Found the Jaws of an Extremely Rare Bear in Tavrida

The bones of an Etruscan bear in the cave were discovered by Dmitry Gimranov and Aleksandr Lavrov.
 Photo: Anastasia Mavrenkova

Ural paleontologists discovered the lower jaws of an Etruscan bear from the Early Pleistocene (2-1.5 million years ago) in the Taurida Cave (Crimean Peninsula). The finding is extremely important, because it is rare and indicates that the territory of Crimea almost 2 million years ago, most likely lived an ancestor of modern man, early Homo. Scientists reported the finding in the international journal of paleobiology Historical Biology.

Remains of Etruscan bears (which is the ancestor of brown and cave bears) as part of the fauna of large mammals of the Early Pleistocene were found in Western Europe, in Asia, as well as in North Africa, but not in Russia. The fact is that in Russia, Early Pleistocene faunas with remains of large terrestrial vertebrates were practically not known before. Crimea in this regard is an attractive and informative place for scientists.

"Our finding, on the one hand, extends the geography of the distribution of the Etruscan bear in Eastern Europe, and on the other hand, indicates that the "Crimean" bear is a link between Asian and European counterparts. It also helps to characterize the evolutionary features within bears and the historical biogeography of this species," says Dmitry Gimranov, senior researcher at the Laboratory of Natural Science Methods in Humanities at Ural Federal University and the Paleoecology Institute of Plant and Animal Ecology, Ural Branch of the Russian Academy of Sciences.

Neuromorphic Memory Device Simulates Neurons and Synapses​

A neuromorphic memory device consisting of bottom volatile and top nonvolatile memory layers emulating neuronal and synaptic properties, respectively
Credit: KAIST

Researchers have reported a nano-sized neuromorphic memory device that emulates neurons and synapses simultaneously in a unit cell, another step toward completing the goal of neuromorphic computing designed to rigorously mimic the human brain with semiconductor devices.

Neuromorphic computing aims to realize artificial intelligence (AI) by mimicking the mechanisms of neurons and synapses that make up the human brain. Inspired by the cognitive functions of the human brain that current computers cannot provide, neuromorphic devices have been widely investigated. However, current Complementary Metal-Oxide Semiconductor (CMOS)-based neuromorphic circuits simply connect artificial neurons and synapses without synergistic interactions, and the concomitant implementation of neurons and synapses still remains a challenge. To address these issues, a research team led by Professor Keon Jae Lee from the Department of Materials Science and Engineering implemented the biological working mechanisms of humans by introducing the neuron-synapse interactions in a single memory cell, rather than the conventional approach of electrically connecting artificial neuronal and synaptic devices.

Neuroscientists Find Brain Mechanism Tied to Age-Related Memory Loss

As the brain ages, a region in the hippocampus becomes imbalanced, causing forgetfulness. Scientists say understanding this region of the brain and its function may be the key to preventing cognitive decline.

Working with rats, neuroscientists at Johns Hopkins University have pinpointed a mechanism in the brain responsible for a common type of age-related memory loss. The work, published in Current Biology, sheds light on the workings of aging brains and may deepen our understanding of Alzheimer's disease and similar disorders in humans.

"We're trying to understand normal memory and why a part of the brain called the hippocampus is so critical for normal memory," said senior author James Knierim, a professor at the university's Zanvyl Krieger Mind/Brain Institute. "But also with many memory disorders, something is going wrong with this area."

Neuroscientists know that neurons in the hippocampus, located deep in the brain's temporal lobe, are responsible for a complementary pair of memory functions called pattern separation and pattern completion. These functions occur in a gradient across a tiny region of the hippocampus called CA3.

In normal brains, pattern separation and pattern completion work hand-in-hand to sort and make sense of perceptions and experiences, from the most basic to the highly complex. If you visit a restaurant with your family and a month later you visit the same restaurant with friends, you should be able to recognize that it was the same restaurant, even though some details have changed—this is pattern completion. But you also need to remember which conversation happened when, so you do not confuse the two experiences—this is pattern separation.

Superconductivity and charge density waves caught intertwining at the nanoscale

Artist's rendering of an infrared laser quenching charge density waves.
Credit: Greg Stewart/SLAC National Accelerator Laboratory

Room-temperature superconductors could transform everything from electrical grids to particle accelerators to computers – but before they can be realized, researchers need to better understand how existing high-temperature superconductors work.

Now, researchers from the Department of Energy's SLAC National Accelerator Laboratory, the University of British Columbia, Yale University and others have taken a step in that direction by studying the fast dynamics of a material called yttrium barium copper oxide, or YBCO.

The team reports May 20 in Science that YBCO's superconductivity is intertwined in unexpected ways with another phenomenon known as charge density waves (CDWs), or ripples in the density of electrons in the material. As the researchers expected, CDWs get stronger when they turned off YBCO's superconductivity. However, they were surprised to find the CDWs also suddenly became more spatially organized, suggesting superconductivity somehow fundamentally shapes the form of the CDWs at the nanoscale.

Boomerang’ effect in droplets could help clean sensitive surfaces

 A water-alcohol-propylene glycol droplet expands and then contracts, an effect that could be used to help remove particles from sensitive surfaces such as microchips.
Credit: Cornell University College of Engineering

While brooms and sponges are the means of choice to fight contamination in everyday life, cleaning sensitive surfaces such as electronic components require different tools, including evaporation-based methods that often leave behind small particles on the surface.

Through their work on the dynamics of liquid mixtures, scientists at Cornell’s Meinig School of Biomedical Engineering and the Max Planck Institute for Dynamics and Self-Organization have developed a new approach to the problem. The method uses liquid droplets that first spread out on surfaces and then contract again on their own – a boomerang effect that leaves virtually no traces when the droplets contract, unlike conventional drying, opening up new possibilities for cleaning and removing particles from sensitive surfaces such as microchips.