HIV-1–driven CD4-to-CD8 T cell conversion results in a distinct cellular reservoir of viral persistence.
Get the latest international news and world events from around the world.
JWST ‘weighs’ dormant black hole 10 billion light-years away
The most distant, nearly invisible dormant black hole has been detected and “weighed” by an international team of astronomers that includes researchers from UCL. The study, published in Science, identified a dormant black hole at the heart of a galaxy known as MRG-M0138 located over 10 billion light years away. It is the most distant dormant black hole yet detected, 15 times farther away than the previous record.
The black hole’s mass is about 6 billion times that of the sun, and is being observed at a time when the universe was only about 3 billion years old, about a quarter of its current age, offering unprecedented details into black holes in the early universe.
To find this, the team used data from NASA’s James Webb Space Telescope to track the motion of stars orbiting around the otherwise invisible black hole to measure its mass. Though the technique—known as stellar dynamics —has been used to measure dormant black holes in galaxies much closer to Earth, this is the first time it has been used to weigh one located such a great (cosmological) distance away.
Measuring gravitational waves in a humming universe with a coordinate-free approach
Gravitational waves are tiny ripples in spacetime. Their first direct detection in 2015 marked a revolutionary moment in astronomy. Today, we have a thorough understanding of signals that travel far from their sources through quiet, nearly empty space, such as those emitted when black holes merge. In this case, the wave can be considered a minor disturbance on a silent background. The distinction between “background” and “wave” is clear, and the quantity measured by the detector—a tiny stretching and squeezing—is clearly determined.
In cosmology, however, things are more subtle. The focus shifts to the universe in its entirety—encompassing spacetime and everything contained within it, such as stars, black holes and galaxies. The background itself is dynamic. Small fluctuations in density and velocity gently stir spacetime everywhere, blurring the boundary with the wave.
But what exactly does a gravitational-wave detector measure when the entire universe is gently vibrating? Previously, theoretical predictions were entirely dependent on the choice of mathematical coordinates. However, the only meaningful quantity is what a real instrument records, which must be coordinate-independent.
Record ultraviolet quasar wind reaches 30% light speed near supermassive black hole
A team led by York University researchers has discovered the fastest wind near a supermassive black hole ever found at ultraviolet wavelengths, driven by the disk of matter (quasar) surrounding the black hole.
“This quasar has a black hole of 1.7 billion times the mass of the sun. That’s typical. What’s not typical is that it has gas moving towards us at 30% of the speed of light,” says York Professor Patrick Hall of the Faculty of Science.
The finding is published in a paper in The Astrophysical Journal.
Novel synthetic biomolecule degrades disease-related proteins
Northwestern Medicine scientists have developed a novel synthetic biomolecular condensate that can degrade intracellular disease-causing proteins, providing a framework for new therapeutic approaches for a wide range of diseases, as detailed in a recent study published in Nature Communications.
Shana Kelley, Ph.D., the Neena B. Schwartz Professor of Chemistry, Biomedical Engineering, and Biochemistry and Molecular Genetics and the president of the Chan Zuckerberg Biohub Chicago, was senior author of the study.
Targeted protein degradation is an emerging therapeutic strategy that harnesses cells’ own degradation machinery to clear disease-causing proteins. However, achieving this degradation process across different cell types has remained a challenge due to subtle variations in protein structure.
Photoexcitation flips 2D moiré devices from metals to insulators in ultrafast test
Quantum materials, materials with properties that are governed by the laws of quantum mechanics describing many-body interactions, have proved promising for the development of various advanced technologies. Many of these materials undergo so-called phase transitions, switching between different physical states that alter how electrons flow through them.
Some previous studies have demonstrated the transition from insulating states to metallic states in quantum materials, via a process called photoexcitation (i.e., the excitation of electrons using light). Yet the opposite transition, from metallic to insulating states, has so far proved difficult to realize using light alone.
Researchers at Columbia University, in collaboration with UC Riverside, recently demonstrated an ultrafast photo-induced metal-to-insulator transition in two-dimensional (2D) moiré heterostructures, quantum materials consisting of 2D layers stacked on top of each other, with a slight misalignment between them.
Full faces sharpen emotion recognition, even when eye details are blurred
A teary eye, a furrowed eyebrow, creases at the edge of the eye tell us what a person is feeling without them having to express it with words. New data indicate that eyes might be the window to the soul, but with curtains blocking half of their view, because the eyes alone do not contain enough information for our brain to derive emotions solely from them.
Researchers from the College of Wooster, USA, wanted to understand how much we actually rely on the eyes versus the whole face to recognize emotions. After examining participants’ brain activity using EEG (electroencephalography) as they viewed photographs of people displaying different emotions, they discovered that people can recognize emotions both more quickly and more accurately when they can see the entire face rather than just the eyes.
Blurring details in the eyes had little impact on people’s ability to recognize facial expressions as long as the rest of the face remained visible. When details in the eyes are reduced, the ability to read emotions takes a hit if the rest of the face is concealed, suggesting that the brain uses other features to fill in the gaps when information from the eyes is missing.
Teaching AI to design optical surfaces using real-world imperfections
Designing surfaces that precisely control how light behaves at the nanoscale is tricky. Optical Fourier surfaces, which are nanostructured gratings that redistribute light into specific directions and wavelengths, hold enormous potential for compact spectrometers, augmented-reality displays, and advanced sensors. However, their standard design process relies on computer simulations that assume idealized conditions such as single-angle illumination and the absence of fabrication imperfections—a far cry from reality.
The gap between what simulations predict and what fabricated devices actually do has long frustrated researchers. It widens further when designers try to exploit one of the most powerful but underused design parameters: the angle of incoming light. Changing the incident angle can activate or suppress optical modes without any physical modification to the structure, effectively enabling multiple functions on a single device.
“This effectively introduces an additional degree of freedom beyond geometry, expanding the design space significantly,” said Associate Professor Dong Zhaogang from the Singapore University of Technology and Design (SUTD). “But its practical use has been limited because simulations at oblique incidence are often computationally unstable and costly, while real experimental systems involve angular distributions rather than single-incident angles.”
Quantum shell structure reveals new rule for proton-neutron pairing inside nuclei
Nuclear physicists used a little magic in their latest experiment conducted at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility, and the result has revealed surprising new information about the behavior of protons and neutrons inside the atom’s nucleus. Specifically, the research revealed another requirement that determines how protons and neutrons pair up.
The result is reported in the journal Nature.
The research involves short-range correlations (SRCs). This phenomenon describes when a proton and a neutron, or two protons or two neutrons, briefly pair up inside the nucleus.
New X-ray method captures solid-liquid interfaces and bulk liquids simultaneously
Researchers have developed a method for making simultaneous soft X-ray absorption spectroscopy (XAS) measurements of solid-liquid interfaces and bulk liquids. By controlling the thickness of the liquid layer, they obtained the O K-edge XAS spectrum of bulk H2O from a liquid H2O layer on a thin Au film using the transmission method, and they used the electron-yield method to obtain the XAS spectrum of the H2O/Au interface by measuring the drain currents from the Au surface following soft X-ray absorption. This method for obtaining simultaneous XAS measurements of solid-liquid interfaces and bulk liquids can be utilized to investigate the mechanisms of a variety of catalytic, electrochemical, and biological reactions involving solid-liquid interfaces.
Water molecules at solid-liquid interfaces play important roles in various catalytic, electrochemical, and biological reactions. Soft X-ray absorption spectroscopy (XAS) is an element-specific method for investigating the electronic structures of liquid water and organic molecules. In this study, the researchers developed a method for simultaneously obtaining XAS measurements of a solid-liquid interface, using the electron-yield method, and of the bulk liquid, using the transmission method. The paper is published in the Journal of Synchrotron Radiation.
In the present work, they measured the XAS spectra while precisely controlling the thickness of the liquid layer in the range from 20 nm to 40 μm in a liquid cell for the transmission of soft X-rays. The XAS spectra acquired in transmission mode are derived mainly from the bulk liquid because the contributions from the solid-liquid interfaces are smaller than those from the bulk liquid. In contrast, the XAS spectra of solid-liquid interfaces are obtained by detecting Auger electrons, which originate mostly from those interfaces because they escape only from shallow depths.