. Scientific Frontline

Wednesday, November 30, 2022

Better Than a Hole in the Head

Just as blood pressure informs heart health, intracranial pressure (ICP) helps indicate brain health. ICP sensing is the burgeoning focus of Jana Kainerstorfer's biomedical optics lab at Carnegie Mellon University. Her team is working to modernize ICP sensing approaches, which historically have been invasive and risky. Their noninvasive alternatives will ease the risk of infection, pain and medical expenses, as well as present new monitoring capabilities for patients with an array of brain injuries and conditions, from stroke to hydrocephalus.

Investigating pressure levels in the brain is a laborious task for health professionals and hasn't progressed much since the 1960s. Current practice involves drilling a hole into a patient's skull and placing a probe inside for continuous monitoring of ICP levels. It comes with the risk of infection and damaging the brain itself, and while valuable data is to have, ICP measurement is reserved only for the most critical of situations.

"At the core of it, what we've done is build a sensor alternative that doesn't require drilling a hole into the patient's head," said Kainerstorfer, an associate professor of biomedical engineering. "We recently published two papers that explore the use of optical sensors on the forehead for noninvasive ICP monitoring, using near-infrared spectroscopy and diffuse correlation spectroscopy. Both approaches represent huge strides in improving the patient experience and providing better tools to monitor pressure levels in the brain, which can be a key variable in both diagnosis and treatment decisions."

Male orb-weaving spiders fight less in female-dominated colonies

 Orb-weaving spiders spin webs connected to each other in vast networks; within their colonies, individual spiders guard their own webs from intruders and often fight each other over food and mates.
Photo Credit: Gregory Grether/UCLA

Birds do it. Bees do it. Even spiders in their webs do it: cooperate for more peaceful colonies.

That’s one of the surprising findings of a new study by UCLA undergraduates of orb-weaving spiders in Peru.

The study also revealed that when there are more females than males in colonies of orb-weaving spiders, males fight less with each other — and that females fight less in female-dominated colonies than in male-dominated ones, leading to colonies that are somewhat more peaceful. The spiders also showed little hostility to individuals from different colonies, a discovery that has not been previously documented for colonial spiders.

The research was published in the Journal of Arachnology.

“We’re used to thinking of animals like honeybees and elephants living cooperatively,” said the paper’s senior author, Gregory Grether, a UCLA professor of ecology and evolutionary biology. “But spiders usually live solitarily, so we were excited to study these colonial spiders and find out how they interact with colony mates as well as with individuals from other colonies.”

Mysteriously bright flash is a black hole jet pointing straight toward Earth, astronomers say

Caption:Astronomers identified an extremely bright black hole jet, halfway across the universe, pointing straight toward Earth.
Illustration Credit: Dheeraj Pasham, Matteo Lucchini, and Margaret Trippe.

Earlier this year, astronomers were keeping tabs on data from the Zwicky Transient Facility, an all-sky survey based at the Palomar Observatory in California, when they detected an extraordinary flash in a part of the sky where no such light had been observed the night before. From a rough calculation, the flash appeared to give off more light than 1,000 trillion suns.

The team, led by researchers at NASA, Caltech, and elsewhere, posted their discovery to an astronomy newsletter, where the signal drew the attention of astronomers around the world, including scientists at MIT. Over the next few days, multiple telescopes focused on the signal to gather more data across multiple wavelengths in the X-ray, ultraviolet, optical, and radio bands, to see what could possibly produce such an enormous amount of light.

Now, the MIT astronomers along with their collaborators have determined a likely source for the signal. In a study appearing in Nature Astronomy, the scientists report that the signal, named AT 2022cmc, likely comes from a relativistic jet of matter streaking out from a supermassive black hole at close to the speed of light. They believe the jet is the product of a black hole that suddenly began devouring a nearby star, releasing a huge amount of energy in the process.

Physicists observe wormhole dynamics using a quantum computer

Artwork depicting a quantum experiment that observes traversable wormhole behavior.
Illustration Credit: inqnet/A. Mueller | Caltech

Scientists have, for the first time, developed a quantum experiment that allows them to study the dynamics, or behavior, of a special kind of theoretical wormhole. The experiment has not created an actual wormhole (a rupture in space and time), rather it allows researchers to probe connections between theoretical wormholes and quantum physics, a prediction of so-called quantum gravity. Quantum gravity refers to a set of theories that seek to connect gravity with quantum physics, two fundamental and well-studied descriptions of nature that appear inherently incompatible with each other.

"We found a quantum system that exhibits key properties of a gravitational wormhole yet is sufficiently small to implement on today's quantum hardware," says Maria Spiropulu, the principal investigator of the U.S. Department of Energy Office of Science research program Quantum Communication Channels for Fundamental Physics (QCCFP) and the Shang-Yi Ch'en Professor of Physics at Caltech. "This work constitutes a step toward a larger program of testing quantum gravity physics using a quantum computer. It does not substitute for direct probes of quantum gravity in the same way as other planned experiments that might probe quantum gravity effects in the future using quantum sensing, but it does offer a powerful testbed to exercise ideas of quantum gravity."

The research will be published December 1 in the journal Nature. The study's first authors are Daniel Jafferis of Harvard University and Alexander Zlokapa (BS '21), a former undergraduate student at Caltech who started on this project for his bachelor's thesis with Spiropulu and has since moved on to graduate school at MIT.

Most distant detection of a black hole swallowing a star

This artist’s impression illustrates how it might look when a star approaches too close to a black hole, where the star is squeezed by the intense gravitational pull of the black hole. Some of the star’s material gets pulled in and swirls around the black hole forming the disc that can be seen in this image. In rare cases, such as this one, jets of matter and radiation are shot out from the poles of the black hole. In the case of the AT2022cmc event, evidence of the jets was detected by various telescopes including the VLT, which determined this was the most distant example of such an event. 
Illustration Credit: ESO/M.Kornmesser

Earlier this year, the European Southern Observatory’s Very Large Telescope (ESO’s VLT) was alerted after an unusual source of visible light had been detected by a survey telescope. The VLT, together with other telescopes, was swiftly repositioned towards the source: a supermassive black hole in a distant galaxy that had devoured a star, expelling the leftovers in a jet. The VLT determined it to be the furthest example of such an event to have ever been observed. Because the jet is pointing almost towards us, this is also the first time it has been discovered with visible light, providing a new way of detecting these extreme events.

Stars that wander too close to a black hole are ripped apart by the incredible tidal forces of the black hole in what is known as a tidal disruption event (TDE). Approximately 1% of these cause jets of plasma and radiation to be ejected from the poles of the rotating black hole. In 1971, the black hole pioneer John Wheeler[1] introduced the concept of jetted-TDEs as “a tube of toothpaste gripped tight about its middle,” causing the system to “squirt matter out of both ends.”

Tropical wildlife follow the same daily patterns worldwide

An elephant faces a camera trap in one of millions of photos analyzed for a new study led by a Rice University visiting student. The study found striking similarities in how rainforest animals across the world spend their days.
Resized Image using AI by SFLORG
Photo Credit: Courtesy of Lydia Beaudrot/Conservation International

How do animals in the wild use their time? A researcher at Rice University is part of a new study that shows what motivates the daily ramble of tropical populations.

The study by an international team that includes Rice bioscientist Lydia Beaudrot and is led by Andrea Vallejo-Vargas, a graduate student at the Norwegian University of Life Sciences and currently a visiting scholar at Rice, found that communities of mammals across the wet tropics divide their days in similar ways, all generally geared toward finding their next meal. (Or avoiding being the next meal.)

Using millions of images from camera trap networks in 16 protected forests around the world, they examined the relationship of mammal activities to body sizes and feeding routines to find common characteristics among diverse populations.

Their open-access study in Nature Communications confirms that despite their diversity, similar patterns dominate the days of wildlife in Africa, Asia and the Americas.

The study showed that the activity of herbivores and insectivores was largely influenced by temperature in the environment (in study-speak, “thermoregulatory constraints”). For instance, large African herbivores are seven times more likely to be nocturnal than smaller herbivores.

Important discovery could help extinguish disease threat to koalas

Retrovirus is more prevalent in New South Wales and Queensland koalas, compared to animals in Victoria and South Australia.
Photo Credit: Jordan Whitt

University of Queensland virologists are a step closer to understanding a mysterious AIDS-like virus that is impacting koala populations differently across state lines.

Dr Michaela Blyton and Associate Professor Keith Chappell from the Australian Institute for Bioengineering and Nanotechnology (AIBN) and School of Chemistry and Molecular Biosciences, have uncovered another piece of the puzzle in their quest to halt the koala retrovirus known as KoRV - a condition strongly associated with diseases that cause infertility and blindness.

“We’ve learned that the retrovirus is far more prevalent in New South Wales and Queensland koalas, compared to the southern populations in Victoria and South Australia,” Dr Blyton said.

“Uncovering crucial patterns like these helps us learn how the disease is evolving, how it’s spreading, and how we can contain the damage through anti-viral medication or koala breeding programs.”

Koala numbers have fallen rapidly over the past decade due to widespread land clearing, climate change induced weather events, and disease.

Dr Blyton’s research has already established the link between KoRV and chlamydia, cystitis and conjunctivitis, which suggests the virus weakens the animal’s immune system.

To track disease-carrying mosquitoes, researchers tag them with DNA barcodes

 The researchers at a field site in Fort Collins, Colorado collecting mosquitoes for analysis.
Photo Credit: Rebekah Kading/Colorado State University

West Nile, Zika, dengue and malaria are all diseases spread by bites from infected mosquitoes. To track the threat of such diseases over large populations, scientists need to know where the mosquitoes are, where they’ve been, and where they might go.

But take it from Rebekah Kading, a Colorado State University researcher who studies mosquito-borne arboviruses: tracking mosquitoes is no easy task. The capture, tagging and release of single mosquitoes – as is commonly done with bats and other disease carriers – would be ridiculous, if not impossible. A common mosquito-tracking technique involves dousing the insects in fluorescent powder and letting them fly away, but the practice is error-prone and unreliable.

Thanks to a collaboration with CSU engineers, Kading and colleagues are introducing a better way to perform mosquito-tracking for disease applications. Their new method, which involves getting larval mosquitoes to eat harmless particles made entirely of DNA and proteins, has the potential to revolutionize how people study mosquito-borne diseases.

The edible mosquito marker particles are the work of Chris Snow, associate professor in the Department of Chemical and Biological Engineering. For the last several years, Snow’s team has been developing microscopic, porous protein crystals that self-assemble from a protein originally found in Camplyobacter jejuni bacteria. Since inventing these very small, non-toxic protein crystals that feature highly precise arrays of pores, Snow’s team has been exploring diverse applications for them, like capturing virus particles to facilitate wastewater testing.

How giant-faced owls snag voles hidden in snow

Video Credit: Sylvain Eckhardt

Hovering over a target helps giant-faced Great Gray owls pinpoint prey hidden beneath as much as two feet of snow.

Several of the owls’ physical features, especially parts of their wings and face, help them correct for sonic distortions caused by the snow, enabling them to find their moving food with astonishing accuracy, according to a new UC Riverside study.

While most owls fly straight at their prey, this species hovers just above a target area before dropping straight down and punching through the snow with its talons.

“These aren’t the only birds to hunt this way, but in some ways, they are the most extreme because they can locate prey so far beneath the snow cover,” said UC Riverside biologist Christopher Clark, who led the study. “This species is THE snow hunting specialist.”

Clark and his team conducted a series of experiments in the forests of Manitoba, Canada, this year to better understand the owls’ precision despite snow-limited visibility and sounds. Their observations are documented in a new Proceedings of the Royal Society B paper.

A key finding relates to the owls’ broad disc-like face, which they use like radar to find food. The fleshy part of our ears works the way their facial features do. An opening under their feathers funnels sound toward their ears, which are located near the center of their faces.

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.

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