Looking inside a neutron star -- new model will improve insights gleaned from gravitational waves

The unique oscillations in binary neutron stars right before they merge could have big implications for the insights scientists can glean from gravitational wave detection.

Researchers at the University of Birmingham have demonstrated the way in which these vibrations, caused by the interactions between the two stars' tidal fields as they get close together, affect gravitational-wave observations. The study is published in Physical Review Letters.

Taking these movements into account could make a huge difference to our understanding of the data taken by the Advanced LIGO and Virgo instruments, set up to detect gravitational waves -- ripples in time and space -- produced by the merging of black holes and neutron stars.

The researchers aim to have a new model ready for Advanced LIGO's next observing run and even more advanced models for the next generation of Advanced LIGO instruments, called A+, which are due to begin their first observing run in 2025.

Since the first gravitational waves were detected by the LIGO Scientific Collaboration and Virgo Collaboration in 2016, scientists have been focused on advancing their understanding of the massive collisions that produce these signals, including the physics of a neutron star at supra nuclear densities.

Dr Geraint Pratten, of the Institute for Gravitational Wave Astronomy at University of Birmingham, is lead-author on the paper. He said: "Scientists are now able to get lots of crucial information about neutron stars from the latest gravitational wave detections. Details such as the relationship between the star's mass and its radius, for example, provide crucial insight into fundamental physics behind neutron stars. If we neglect these additional effects, our understanding of the structure of the neutron star as a whole can become deeply biased."

Dr Patricia Schmidt, co-author on the paper and Associate Professor at the Institute for Gravitational Wave Astronomy, added: "These refinements are really important. Within single neutron stars we can start to understand what's happening deep inside the star's core, where matter exists at temperatures and densities we cannot produce in ground-based experiments. At this point we might start to see atoms interacting with each other in ways we have not yet seen -- potentially requiring new laws of physics."

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Which animals can best withstand climate change?

Extreme weather such as prolonged drought and heavy rainfall is becoming more and more common as the global average temperature rises -- and it will only get worse in the coming decades. How will the planet's ecosystems respond?

"That is the big question and the background for our study," said biologist John Jackson, who, together with his biologist colleagues Christie Le Coeur from the University of Oslo and Owen Jones from University of Southern Denmark, authored a new study, published in eLife.

John Jackson is now at Oxford University but was at the University of Southern Denmark when the study was made. Owen Jones is associate professor at the Department of Biology, University of Southern Denmark.

Llama, moose and elephant

In the study, the authors analyzed data on population fluctuations from 157 mammal species from around the world and compared them with weather and climate data from the time the animal data were collected. For each species there are 10 or more years of data.

Their analysis has given them an insight into how populations of animal species have coped at times of extreme weather: Did they become more, or less, numerous? Did they have more or fewer offspring?

"We can see a clear pattern: Animals that live a long time and have few offspring are less vulnerable when extreme weather hits than animals that live for a short time and have many offspring. Examples are llamas, long-lived bats and elephants versus mice, possums and rare marsupials such as the woylie," said Owen Jones.

Less affected by extreme weather:

African elephant, Siberian tiger, chimpanzee, greater horseshoe bat, llama, vicuña, white rhinoceros, grizzly bear, American bison, klipspringer, Schreibers's bat.

More affected by extreme weather:

Azara's grass mouse, olive grass mouse, elegant fat-tailed mouse opossum, Canadian lemming, Tundra vole, Arctic fox, stoat, common shrew, woylie, arctic ground squirrel.

Quick drop -- but also quick boom

Large, long-lived animals are better able to cope with conditions like prolonged drought; their ability to survive, to reproduce and to raise their offspring is not affected to the same extent as small, short lived animals. They can, for example, invest their energy into one offspring, or simply wait for better times when conditions become challenging.

On the other hand, small short-lived rodents have more extreme population changes in the short term. In the event of a prolonged drought, for example, large parts of their food base may disappear more rapidly: insects, flowers, fruits, and they are left to starve because they have limited fat reserves.

The populations of these small mammals may also boom to take advantage when conditions improve because, in contrast to large mammals, they can produce many offspring.

Not the same as risk of extinction

"These small mammals react quickly to extreme weather, and it goes both ways. Their vulnerability to extreme weather should therefore not be equated with a risk of extinction," said John Jackson.

He also reminds us that the ability of an animal species to withstand climate change must not stand alone when assessing the species' vulnerability to extinction:

"Habitat destruction, poaching, pollution and invasive species are factors that threaten many animal species -- in many cases even more than climate change," he emphasized.

The animals we don't know much about

The researchers' study not only gives an insight into how these specific 157 mammal species react to climate changes here and now. The study can also contribute to a better general understanding of how the planet's animals will respond to ongoing climate change.

"We expect climate change to bring more extreme weather in the future. Animals will need to cope with this extreme weather as they always have. So, our analysis helps predict how different animal species might respond to future climate change based on their general characteristics -- even if we have limited data on their populations," said Owen Jones.

An example is the woylie, a rare Australian marsupial. Biologists do not know very much about this species, but because it shares a similar life style with mice -- that is, it is small, lives for a short time and reproduces quickly -- it can be predicted that it will respond to extreme weather in a similar way to mice.

Entire ecosystems will change

"In the same way, there are lots of animal species that we don't know very much about, but whose reaction we can now predict," explained John Jackson.

In this way, the researchers expect that the ability of different animal species to adapt to climate change is related to their life strategy, and this can help us predict ecological changes:

As habitat suitability changes due to climate change, species may be forced to move to new areas as old areas become inhospitable. These shifts depend on species' life strategies and can have big impacts on ecosystem function.

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Musical tests can detect mental deterioration in old age

Researchers at Tel Aviv University have developed a method that employs musical tests and a portable instrument for measuring brain activity to detect cognitive decline in old age. According to the researchers, the method, which is based on the measurement of 15 minutes of electrical activity in the brain while performing simple musical tasks, can be easily implemented by any staff member in any clinic, without requiring special training.

The researchers: "Our method enables routine monitoring and early detection of cognitive decline in order to provide treatment and prevent rapid, severe deterioration. Prophylactic tests of this kind are commonly accepted for a variety of physiological problems such as diabetes, high blood pressure or breast cancer; however, to date no method has yet been developed to enable routine, accessible monitoring of the brain for cognitive issues." The researchers further note that tests of this kind are particularly important in light of increasing longevity and associated growth of the elderly population.

The study was led at Tel Aviv University by PhD student Neta Maimon from the School of Psychological Sciences and the Buchmann-Mehta School of Music, and Lior Molcho from Neurosteer Ltd, headed by Prof. Nathan Intrator from the Blavatnik School of Computer Science and the Sagol School of Neuroscience. Other participants included: Adi Sasson, Sarit Rabinowitz, and Noa Regev-Plotnick from the Dorot-Netanya Geriatric Medical Center. The article was published in the journal Frontiers in Aging Neuroscience.

As part of the study, the researchers developed a groundbreaking method combining a portable device for the measurement and innovative analysis of electroencephalography (EEG), developed by Neurosteer, and a short musical test of about 12-15 minutes, developed by Neta Maimon. During the test, the subject is connected to the portable EEG device by means of a adhesive band with only three electrodes attached to the forehead. The subject performs a series of musical-cognitive tasks according to audible instructions given automatically through earphones. The tasks include short melodies played by different instruments, with the subjects instructed to perform various tasks on them at varying levels of difficulty. For example, pressing a button each time any melody is played or pressing it only when the violin plays. In addition, the test includes several minutes of musically guided meditation designed to bring the brain to a resting state, as this state is known to indicate cerebral functioning in various situations.

Neta Maimon, who specializes in musical cognition, explains that music has great influence on different centers in the brain. On the one hand, music is known to be a quick mood stimulant, particularly of positive emotion. On the other hand, in different situations, music can be cognitively challenging, activating the frontal parts of the brain, especially if we try to concentrate on different aspects of the music, and at the same time perform a particular task.

According to Maimon, if we combine these two capabilities, we can create cognitive tests that are quite complex, yet also pleasant and easy to perform. Furthermore, music that is positive and reasonably rhythmic will enhance concentration and performance of the task. Thus, for example, the famous "Mozart effect," showing improved performance on intelligence tests after listening to Mozart's music, actually has nothing to do with Mozart's music, but rather the fact that music creates a positive mood and stimulates us to a state that is optimal for performing intelligence and creativity tests.

Accordingly, the researchers hypothesized that with musical tools, it would also be possible to challenge the subjects to an extent that would enable testing of the brain's frontal activity as well as raising their spirits, thus enhancing their performance on the test while the overall experience is pleasant.

The study included an experiment at the Dorot-Netanya Geriatric Medical Center. Neta Maimon: "Anyone hospitalized at Dorot, or any other geriatric rehabilitation institution, undergoes a standard test called "mini-mental," designed to evaluate their cognitive condition as a routine part of the intake process. The test is conducted by an occupational therapist specially trained for it, and includes a variety of tasks. For example, enumerating the days of the week or months of the year backwards. In this test, up to 30 points can be accrued. A high score indicates normal cognition.

The experiment included the testing of 50 elderly people hospitalized at Dorot who scored 18-30 on the mini-mental test, indicating various levels of cognitive functioning. The participants performed the musical-cognitive tasks, administered automatically. The EEG device registered the electrical activity in the brain during the activity, with the results analyzed using machine learning technology. This allowed mathematical indices to be identified that were precisely correlated with the mini-mental test scores; in other words, we obtained new neuro-markers (brain markers) that may stand alone as indices of the subject's cognitive status.

Maimon adds: "We have actually succeeded in illustrating that music is indeed an effective tool for measuring brain activity. The brain activity and response times to tasks correlated to the subjects' cerebral conditions (correlating to the mini-mental score assigned to them). More importantly, all those who underwent the experiment reported that, on the one hand, it challenged the brain, but on the other it was very pleasant to perform."

The researchers conclude: "Our method enables the monitoring of cognitive capability and detection of cognitive decline already in the early stages. all by simple and accessible means, with a quick and easy test that can be conducted in any clinic. This method is of special importance today due to the increase in longevity and accelerated population growth, particularly among the elderly. Today, millions of people around the world already suffer or are liable to suffer soon from cognitive decline and its dire consequences, and their number will only increase in the coming decades. Our method could pave the way towards efficient cognitive monitoring of the general population, and thus detect cognitive decline in its early stages, when treatment and prevention of severe decline are possible. It is therefore expected to improve the quality of life of millions around the world."

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Non-nutritive sweeteners affect human microbiomes and can alter glycemic responses

Since the late 1800s non-nutritive sweeteners have promised to deliver all the sweetness of sugar with none of the calories. They have long been believed to have no effect on the human body, but researchers publishing in the journal Cell on August 19 challenge this notion by finding that these sugar substitutes are not inert, and, in fact, some can alter human consumers' microbiomes in a way that can change their blood sugar levels.

In 2014, senior author Eran Elinav an immunologist and microbiome researcher at the Weizmann Institute of Science and the German National Cancer Center (DKFZ) and his team found that non-nutritive sweeteners affected the microbiomes of mice in ways that could impact their glycemic responses. The team was interested in whether these results would also be found in humans.

To address this important question, the research team carefully screened over 1300 individuals for those who strictly avoid non-nutritive sweeteners in their day-to-day lives, and identified a cohort of 120 individuals. These participants were broken into six groups: two controls and four who ingested well below the FDA daily allowances of either aspartame, saccharin, stevia, or sucralose.

"In subjects consuming the non-nutritive sweeteners, we could identify very distinct changes in the composition and function of gut microbes, and the molecules they secret into peripheral blood. This seemed to suggest that gut microbes in the human body are rather responsive to each of these sweeteners," says Elinav. "When we looked at consumers of non-nutritive sweeteners as groups, we found that two of the non-nutritive sweeteners, saccharin and sucralose, significantly impacted glucose tolerance in healthy adults. Interestingly, changes in the microbes were highly correlated with the alterations noted in people's glycemic responses."

To establish causation, the researchers transferred microbial samples from the study subjects to germ-free mice -- mice that have been raised in completely sterile conditions and have no microbiome of their own.

"The results were quite striking," says Elinav. "In all of the non-nutritive sweetener groups, but in none of the controls, when we transferred into these sterile mice the microbiome of the top responder individuals collected at a time point in which they were consuming the respective non-nutritive sweeteners, the recipient mice developed glycemic alterations that very significantly mirrored those of the donor individuals. In contrast, the bottom responders' microbiomes were mostly unable to elicit such glycemic responses," he adds. "These results suggest that the microbiome changes in response to human consumption of non-nutritive sweetener may, at times, induce glycemic changes in consumers in a highly personalized manner."

Elinav says that he expects the effects of the sweeteners will vary person to person because of the incredibly unique composition of our microbiome. "We need to raise awareness of the fact that non-nutritive sweeteners are not inert to the human body as we originally believed. With that said, the clinical health implications of the changes they may elicit in humans remain unknown and merit future long-term studies."

Read more at Science Daily

Breaking in a new planet

The harder you hit something -- a ball, a walnut, a geode -- the more likely it is to break open. Or, if not break open, at least lose a little bit of its structural integrity, the way baseball players pummel new gloves to make them softer and more flexible. Cracks, massive or tiny, form and bear a silent, permanent witness to the impact.

Studying how those impacts affect planetary bodies, asteroids, moons and other rocks in space helps planetary scientists including Brandon Johnson, associate professor, and Sean Wiggins, postdoctoral researcher, in the College of Science's Department of Earth, Atmospheric, and Planetary Sciences at Purdue University, understand extraplanetary geology, especially where to look for precious matter including water, ice and even, potentially, microbial life.

Every solid body in the solar system is constantly pummeled by impacts, both large and small. Even on Earth, every single spot has been affected by at least three big impacts. Using the moon as a test subject, Johnson, Wiggins and their team set out to quantify the relationship between impacts and a planet's porosity.

The researchers used extensive lunar gravity data and detailed modeling and found that when large objects hit the moon or any other planetary body, that impact can affect surfaces and structures, even very far away from the point of impact and deep into the planet or moon itself. This finding, detailed in their new study published in the journal Nature Communications, explains existing data on the moon that had puzzled scientists. The research was partially funded by funded by NASA's Lunar Data Analysis Program.

"NASA's GRAIL (Gravity Recovery and Interior Laboratory) mission measured the gravity of the moon and showed that the moon crust is very porous to very great depths," Johnson said. "We didn't have a description of how the moon would get so porous. This is the first work that really shows that large impacts are capable of fracturing the moon's crust and introducing this porosity."

Understanding where planets and moons have fractured, and why, can help direct space exploration and tell scientists where the best place to look for life might be. Anywhere that rock, water and air meet and interact, there is a potential for life.

"There's a lot to be excited about," Wiggins said. "Our data explains a mystery. This research has implications for the early Earth and for Mars. If life existed back then, there were these intermittently big impacts that would sterilize the planet and boil off the oceans. But if you had life that could survive in pores and interstices a few hundred feet or even a few miles down, it could have survived. They could have provided these refuges where life could hide out from these kinds of impacts.

Read more at Science Daily

Why heat makes us sleepy

On the hottest summer days, you may find yourself dozing off in the middle of the day. In some parts of the world, it's a cultural norm to schedule "siestas" and shutter businesses during the warmest hours of the day. As it turns out, biology, not just culture, may be behind this.

Temperature affects the span of human behavior, from eating and activity levels to sleep-wake cycles. We may have a harder time sleeping in the summer and be slow to get out of bed on colder mornings. But the link between sensory neurons and neurons that control this cycle are not understood completely.

Northwestern University neurobiologists have found a few clues about what's happening. In a new study, published today (Aug. 17) in the journal Current Biology, researchers found that fruit flies are pre-programmed to take a nap in the middle of the day. A follow-up to their 2020 Biology paper that identified a brain thermometer only active in cold weather, the new paper explores a similar "thermometer" circuit for hot temperatures.

"Changes in temperature have a strong effect on behavior in both humans and animals, and offer animals a cue that is time to adapt to the changing seasons," said Marco Gallio, associate professor of neurobiology in the Weinberg College of Arts and Sciences. "The effect of temperature on sleep can be quite extreme, with some animals deciding to sleep off an entire season -- think of a hibernating bear -- but the specific brain circuits that mediate the interaction between temperature and sleep centers remain largely unmapped."

Gallio led the study and said fruit flies are a particularly good model to study big questions like "why do we sleep," and "what does sleep do for the brain" because they don't attempt to disrupt instinct in the same way humans do when we pull all-nighters, for example. They also allow researchers to study the influence of external cues like light and temperature on cellular pathways.

Cells that stay on longer

The paper is the first to identify "absolute heat" receptors in fly head, which respond to temperatures above about 77 degrees Fahrenheit -- the fly's favorite temperature. As it turns out, the common laboratory fruit fly (Drosophila) has colonized nearly the entire planet by forming a close association with humans. Not surprisingly, its favorite temperature also matches that of many humans.

Just as they expected based on the results of their previous paper on cold temperature, researchers found that brain neurons receiving information about heat are part of the broader system that regulates sleep. When the hot circuit, which runs parallel to the cold circuit, is active, the target cells that promote midday sleep stay on longer. This results in an increase in midday sleep that keeps flies away from the hottest part of the day.

The study was enabled by a 10-year initiative that produced the first completed map of neural connections in an animal (a fly), called the connectome. With the connectome, researchers have access to a computer system that tells them all possible brain connections for each of the fly's ~100,000 brain cells. However, even with this extremely detailed road map, researchers still need to figure out how information in the brain goes from point A to B. This paper helps fill that gap.

The different circuits for hot versus cold temperatures make sense to Gallio because "hot and cold temperatures can have quite different effects on physiology and behavior," he said. This separation may also reflect evolutionary processes based on heat and cold cycles of the Earth. For example, the possibility that brain centers for sleep may be directly targeted in humans by a specific sensory circuit is now open to be investigated based on this work.

Next steps

Next, Gallio's team hopes to figure out the common targets of the cold and hot circuit, to discover how each can influence sleep.

"We identified one neuron that could be a site of integration for the effects of hot and cold temperatures on sleep and activity in Drosophila," said Michael Alpert, the paper's first author and a post-doctoral researcher in the Gallio lab. "This would be the start of interesting follow-up studies."

Gallio added that the team is interested in looking at the long-term effects of temperature on behavior and physiology to understand the impact of global warming, looking at how adaptable species are to change.

"People may choose to take an afternoon nap on a hot day, and in some parts of the world this is a cultural norm, but what do you choose and what is programmed into you?" Gallio said. "Of course, it's not culture in flies, so there actually might be a very strong underlying biological mechanism that is overlooked in humans."

Read more at Science Daily

A warming planet could mess with our sleep -- and make us more vulnerable to infectious disease

It's a scene that will be familiar for many after yet another scorching summer: You're lying awake during a warm night, bedsheets kicked aside, an overmatched ceiling fan providing little respite as you struggle to get a good night's sleep.

But a warming planet doesn't just mean more people may find it harder to get quality sleep. There is also evidence suggesting that sleep disturbance could make it harder for the body to fend off infection, according to a new research paper from Dr. Michael Irwin, a professor of psychiatry and biobehavorial sciences at UCLA.

Irwin, who has extensively studied how sleep regulates the immune system, said while there are few studies on how ambient, or surrounding air, temperature affects sleep, they indicate that warmer temperatures contribute to sleep disturbance. Studies have also shown that poor sleep is associated with heightened risk of infectious disease and could make some vaccination less effective, Irwin writes in a research review published in the peer-reviewed journal Temperature last week.

Given research showing a potential link between poor sleep and reduced immune response, Irwin said this raises timely questions about whether climate change results in heightened infectious disease risk amid the ongoing COVID-19 pandemic, a monkeypox outbreak and the reemergence of the poliovirus in New York and London.

"No one has previously put together this notion that the ongoing climate crisis is contributing to sleep disturbance and that it's possibly contributing to the altered risk of infectious disease we're seeing," said Irwin, the director of the Cousins Center for Psychoneuroimmunology at the Jane and Terry Semel Institute for Neuroscience and Human Behavior at UCLA.

Irwin said the issue also raises important implications about disparities, since low-income communities and communities of color face heightened risk from heat and have less access to air conditioning.

What the research shows

Irwin's paper reviews how poor sleep affects the immune system and could make people more vulnerable to infectious disease threats. Among the research he cites:

- There's a strong association between sleep and thermoregulation, or how humans maintain a steady core internal temperature. Experimental studies have shown that reducing air temperatures to a range in which humans can maintain a normal body temperature without expending excess energy improves sleep quality, while increases in air temperature result in increased wakefulness. Survey data of 765,000 people in the United States also found increases in nighttime temperatures amplified self-reported nights of insufficient sleep, with the largest effects during the summer and among lower-income and elderly people.

- It's thought that sleep helps prepare the body's response to possible injury or infection that could occur the following day. When sleep is disrupted, that contributes to increases in inflammation and dampens the body's ability to fight off infections. That means there may be heightened risk among older adults and patients with inflammatory disorders, like cardiovascular disease and some types of depression, who have higher prevalence of insomnia.

- Some small experimental studies in humans indicate that poor sleep could also result in poorer vaccine response. In one study, for instance, people who had four straight nights of partial sleep deprivation before receiving a trivalent influenza vaccine had a 50% reduction in antibody titers compared to those with normal sleep. Other studies that tested the effects of sleep disruption after influenza or hepatitis vaccination suggest that short sleep duration, at least in healthy adults, is likely associated with a reduced adaptive immunologic response and possibly clinical protection.

- Sleep duration is also associated with infectious disease risk outcomes. Basic research has shown that longer sleep leads to decreases in bacterial load and improved survival in a variety of infectious disease models. Self-reported surveys have also shown an association between shorter sleep and higher infection risk.

- While there's abundant evidence that sleep disturbance and depressive symptoms have greatly increased during the COVID-19 pandemic, there's little known about how poor sleep may be affecting risk of COVID-19 infection and outcomes. However, a recent study of over 46,000 patients indicated that a significant sleep disturbance was associated with an over 2-fold increase in the mortality risk for patients who had COVID-19, while no similar association was found in those who did not.

Irwin said that future research on this topic should evaluate how altering ambient temperatures affects sleep and, as a result, immune function. He said there should also be a focus on how rising ambient temperatures may be affecting diverse and disadvantaged communities.

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Researchers invent self-charging, ultra-thin device that generates electricity from air moisture

Imagine being able to generate electricity by harnessing moisture in the air around you with just everyday items like sea salt and a piece of fabric, or even powering everyday electronics with a non-toxic battery that is as thin as paper. A team of researchers from the National University of Singapore's (NUS) College of Design and Engineering (CDE) has developed a new moisture-driven electricity generation (MEG) device made of a thin layer of fabric -- about 0.3 millimetres (mm) in thickness -- sea salt, carbon ink, and a special water-absorbing gel.

The concept of MEG devices is built upon the ability of different materials to generate electricity from the interaction with moisture in the air. This area has been receiving growing interest due to its potential for a wide range of real-world applications, including self-powered devices such as wearable electronics like health monitors, electronic skin sensors, and information storage devices.

Key challenges of current MEG technologies include water saturation of the device when exposed to ambient humidity and unsatisfactory electrical performance. Thus, the electricity generated by conventional MEG devices is insufficient to power electrical devices and is also not sustainable.

To overcome these challenges, a research team led by Assistant Professor Tan Swee Ching from the Department of Materials Science and Engineering under CDE devised a novel MEG device containing two regions of different properties to perpetually maintain a difference in water content across the regions to generate electricity and allow for electrical output for hundreds of hours.

This technological breakthrough was published in the print version of scientific journal Advanced Materials on 26 May 2022.

Long-lasting, self-charging fabric-based 'battery'

The NUS team's MEG device consists of a thin layer of fabric which was coated with carbon nanoparticles. In their study, the team used a commercially available fabric made of wood pulp and polyester.

One region of the fabric is coated with a hygroscopic ionic hydrogel, and this region is known as the wet region. Made using sea salt, the special water-absorbing gel can absorb more than six times its original weight, and it is used to harvest moisture from the air.

"Sea salt was chosen as the water-absorbing compound due to its non-toxic properties and its potential to provide a sustainable option for desalination plants to dispose of the generated sea salt and brine," shared Asst Prof Tan.

The other end of the fabric is the dry region which does not contain a hygroscopic ionic hydrogel layer. This is to ensure that this region is kept dry and water is confined to the wet region.

Once the MEG device is assembled, electricity is generated when the ions of sea salt are separated as water is absorbed in the wet region. Free ions with a positive charge (cations) are absorbed by the carbon nanoparticles which are negatively charged. This causes changes to the surface of the fabric, generating an electric field across it. These changes to the surface also give the fabric the ability to store electricity for use later.

Using a unique design of wet-dry regions, NUS researchers were able to maintain high water content in the wet region and low water content in the dry region. This will sustain electrical output even when the wet region is saturated with water. After being left in an open humid environment for 30 days, water was still maintained in the wet region demonstrating the effectiveness of the device in sustaining electrical output.

"With this unique asymmetric structure, the electric performance of our MEG device is significantly improved in comparison with prior MEG technologies, thus making it possible to power many common electronic devices, such as health monitors and wearable electronics," explained Asst Prof Tan.

The team's MEG device also demonstrated high flexibility and was able to withstand stress from twisting, rolling, and bending. Interestingly, its outstanding flexibility was shown by the researchers by folding the fabric into an origami crane which did not affect the overall electrical performance of the device.

Portable power supply and more

The MEG device has immediate applications due to its ease of scalability and commercially available raw materials. One of the most immediate applications is for use as a portable power source for mobile powering electronics directly by ambient humidity.

"After water absorption, one piece of power-generating fabric that is 1.5 by 2 centimetres in size can provide up to 0.7 volts (V) of electricity for over 150 hours under a constant environment," said research team member Dr Zhang Yaoxin.

The NUS team has also successfully demonstrated the scalability of its new device in generating electricity for different applications. The NUS team connected three pieces of the power-generating fabric together and placed them into a 3D printed case that was the size of a standard AA battery. The voltage of the assembled device was tested to reach as high as 1.96V -- higher than a commercial AA battery of about 1.5V -- which is enough to power small electronic devices such as an alarm clock.

The scalability of the NUS invention, the convenience of obtaining commercially available raw materials as well as the low fabrication cost of about S$0.15 per metre square make the MEG device suitable for mass production.

"Our device shows excellent scalability at a low fabrication cost. Compared to other MEG structures and devices, our invention is simpler and easier for scaling-up integrations and connections. We believe it holds vast promise for commercialisation," shared Asst Prof Tan.

Read more at Science Daily

Black hole collisions could help us measure how fast the universe is expanding

A black hole is usually where information goes to disappear -- but scientists may have found a trick to use its last moments to tell us about the history of the universe. In a new study, two University of Chicago astrophysicists laid out a method for how to use pairs of colliding black holes to measure how fast our universe is expanding -- and thus understand how the universe evolved, what it is made out of, and where it's going. In particular, the scientists think the new technique, which they call a "spectral siren," may be able to tell us about the otherwise elusive "teenage" years of the universe.

A cosmic ruler

A major ongoing scientific debate is exactly how fast the universe is expanding -- a number called the Hubble constant. The different methods available so far yield slightly different answers, and scientists are eager to find alternate ways to measure this rate. Checking the accuracy of this number is especially important because it affects our understanding of fundamental questions like the age, history and makeup of the universe.

The new study offers a way to make this calculation, using special detectors that pick up the cosmic echoes of black hole collisions.

Occasionally, two black holes will slam into each other -- an event so powerful that it literally creates a ripple in space-time that travels across the universe. Here on Earth, the U.S. Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Italian observatory Virgo can pick up those ripples, which are called gravitational waves.

Over the past few years, LIGO and Virgo have collected the readings from almost 100 pairs of black holes colliding.

The signal from each collision contains information about how massive the black holes were. But the signal has been traveling across space, and during that time the universe has expanded, which changes the properties of the signal. "For example, if you took a black hole and put it earlier in the universe, the signal would change and it would look like a bigger black hole than it really is," explained UChicago astrophysicist Daniel Holz, one of the two authors on the paper.

If scientists can figure out a way to measure how that signal changed, they can calculate the expansion rate of the universe. The problem is calibration: How do they know how much it changed from the original?

In their new paper, Holz and first author Jose María Ezquiaga suggest that they can use our newfound knowledge about the whole population of black holes as a calibration tool. For example, current evidence suggests that most of the detected black holes have between five and 40 times the mass of our sun. "So we measure the masses of the nearby black holes and understand their features, and then we look further away and see how much those further ones appear to have shifted," said Ezquiaga, a NASA Einstein Postdoctoral Fellow and Kavli Institute for Cosmological Physics Fellow working with Holz at UChicago. "And this gives you a measure of the expansion of the universe."

The authors dub it the "spectral siren" method, a new approach to the 'standard siren' method which Holz and collaborators have been pioneering. (The name is a reference to the 'standard candle' methods also used in astronomy.)

The scientists are excited because in the future, as LIGO's capabilities expand, the method may provide a unique window into the "teenage" years of the universe -- about 10 billion years ago -- that are hard to study with other methods.

Researchers can use the cosmic microwave background to look at the very earliest moments of the universe, and they can look around at galaxies near our own galaxy to study the universe's more recent history. But the in-between period is harder to reach, and it's an area of special scientific interest.

"It's around that time that we switched from dark matter being the predominant force in the universe to dark energy taking over, and we are very interested in studying this critical transition," said Ezquiaga.

The other advantage of this method, the authors said, is that there are fewer uncertainties created by gaps in our scientific knowledge. "By using the entire population of black holes, the method can calibrate itself, directly identifying and correcting for errors," Holz said. The other methods used to calculate the Hubble constant rely on our current understanding of the physics of stars and galaxies, which involves a lot of complicated physics and astrophysics. This means the measurements might be thrown off quite a bit if there's something we don't yet know.

By contrast, this new black hole method relies almost purely on Einstein's theory of gravity, which is well-studied and has stood up against all the ways scientists have tried to test it so far.

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Wobbling droplets in space confirm late professor's theory

At a time when astronomers around the world are reveling in new views of the distant cosmos, an experiment on the International Space Station has given Cornell researchers fresh insight into something a little closer to home: water.

Specifically, the space station's microgravity environment illuminated the ways that water droplets oscillate and spread across solid surfaces -- knowledge that could have very earthbound applications in 3D-printing, spray cooling, and manufacturing and coating operations.

The team's paper, "Oscillations of Drops with Mobile Contact Lines on the International Space Station: Elucidation of Terrestrial Inertial Droplet Spreading," published Aug. 16 in Physical Review Letters. The lead author is Joshua McCraney, M.S. '19, Ph.D. '21.

The experiment and its findings, while successful, are also bittersweet. The paper's co-senior author Paul Steen, the Maxwell M. Upson Professor in the Smith School of Chemical and Biomolecular Engineering in the College of Engineering, died in September 2020, just before the experiment was conducted.

"It's sad that Paul didn't get to see the experiments launch into space," said co-senior author Susan Daniel, the Fred H. Rhodes Professor in the Smith School of Chemical and Biomolecular Engineering, and Steen's longtime collaborator. "We hope that we did right by him in the end, and that the paper that we produced from the work would make him proud."

Daniel began collaborating with Steen shortly after she first came to Cornell as an assistant professor in 2007. While her current research is focused on the biological interface of the coronavirus, her graduate work was in chemical interfaces and fluid mechanics -- a field in which Steen was advancing a number of theoretical predictions based upon how droplets resonate when subjected to vibrations. The two researchers instantly connected.

"He knew the theory and made predictions, and I knew how to execute the experiments to test them," Daniel said. "Basically, from the moment I got here in 2007 until he passed away, we worked on trying to understand how liquids and surfaces interact with each other, and how the contact line at the interface between them behaves under different conditions."

Their collaboration resulted in a "photo album" of the dozens of possible shapes that an oscillated drop of water can take. Steen later expanded on that project by cataloging the droplets' energy states as evidenced by those resonant shapes, organizing them into a "periodic table" classification.

In 2016, Steen and Daniel received a four-year grant from the National Science Foundation (NSF) and NASA's Center for the Advancement of Science in Space to conduct fluid dynamics research aboard the International Space Station U.S. National Laboratory.

Space is an ideal place to study the behavior of fluids because of the radical reduction of gravity, which on the ISS is about one-millionth of its terrestrial level. This means that fluid-surface interactions which are so small-scale and speedy on Earth that they are practically invisible can be, in space, nearly 10 times larger -- from microns to centimeters -- and their duration slows nearly 30-fold.

"It's harder to study these drop motions, experimentally and fundamentally, when you have gravity in your way," Daniel said.

Steen and Daniel selected a few resonance shapes from their photo album that they wanted to explore in detail, with a focus on how a water droplet's contact line -- or outer edge -- slides back and forth across a surface, driving the way the liquid will spread, a phenomenon that can be controlled by varying vibration frequencies.

The team prepared meticulous instructions for the astronauts to follow, compressing four years of planning into a several-minute experiment in which every second was tightly choreographed.

With the researchers monitoring and providing feedback in real time on the ground, the astronauts deposited 10 mL water droplets via a syringe onto nine different hydrophobic surfaces with varying degrees of roughness. They also forced pairs of droplets to coalesce together, and placed droplets onto an oscillator and tuned its vibrations to achieve the targeted resonance shapes. The water droplets' wobbling and jiggling movements were filmed, and the researchers spent the next year analyzing the data.

That analysis ultimately confirmed Steen's theories about the way a liquid's density and surface tension control the contact line's mobility, overcoming a surface's roughness.

Daniel credits co-author Joshua Bostwick, Ph.D. '11, a former student of Steen's and now the Stanzione Collaboration associate professor at Clemson University, with ensuring that the experiment results squared with Steen's theoretical predictions.

"Josh was able to carry on with the theoretical side of this work in Paul's absence, which was not something I was ready to step into and do. It was nice to have him rejoin the team and help us make sure that we were able to extract everything we could from the data we collected," Daniel said. "Now we can essentially use the theory that Paul created to make predictions, for example, in processes where you're spraying droplets on surfaces, or in 3D-printing, or where liquids spread across a surface really quickly."

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New 3D model shows: Megalodon could eat prey the size of entire killer whales

Megalodon, the largest shark that ever lived, is famous for its huge, human-hand-sized teeth. However, there is little fossil evidence of its whole body. International researchers in collaboration with UZH used an exceptionally preserved specimen to create a 3D computer model of its full body. Their results suggest that the megalodon could fully consume prey the size of today's killer whales and then roam the seas without more food for two months.

The reconstructed megadolon (Otodus megalodon)was 16 meters long and weighed over 61 tons. It was estimated that it could swim at around 1.4 meters per second, require over 98,000 kilo calories every day and have stomach volume of almost 10,000 liters. These results suggest that the megalodon could travel long distances and was capable of eating whole prey of up to 8 meters long. This is notably the size of modern killer whales, today's top ocean predator. An ability to eat large apex predators of comparable size millions of years ago places megalodon at a higher trophic level than modern top predators.

Well-preserved spine enables reconstruction

These are the findings of an international study carried out in collaboration with the University of Zurich. The research was only possible thanks to the 3D modelling of one individual megalodon which was discovered in the 1860s. Against all odds, a sizeable portion of its vertebral column was left behind in the fossil record after the creature died in the Miocene oceans of Belgium at the age of 46 about 18 million years ago.

"Shark teeth are common fossils because of their hard composition which allows them to remain well preserved," says first author Jack Cooper, PhD student at Swansea University. "However, their skeletons are made of cartilage, so they rarely fossilize. The megalodon vertebral column from the Royal Belgian Institute of Natural Sciences is therefore a one-of-a-kind fossil."

From single vertebra to whole body mass

The research team, which includes researchers from Switzerland, UK, USA, Australia and South Africa, first measured and scanned every single vertebra, before reconstructing the entire column. They then attached the column to a 3D scan of a megalodon's dentition from the United States. They completed the model by adding "flesh" around the skeleton using a 3D-scan of the body of a great white shark from South Africa.

"Weight is one of the most important traits of any animal. For extinct animals we can estimate the body mass with modern 3D digital modelling methods and then establish the relationship between mass and other biological properties such as speed and energy usage," says co-author John Hutchinson, professor at the Royal Veterinary College in the UK.

A trans-oceanic super-apex predator

The high energetic demand would have been met by feeding on calorie-rich blubber of whales, in which megalodon bite marks have previously been found in the fossil record. An optimal foraging model of potential megalodon prey encounters found that eating a single 8-meter-long whale may have allowed the shark to swim thousands of miles across oceans without eating again for two months. "These results suggest that this giant shark was a trans-oceanic super-apex predator," says Catalina Pimiento, Professor at the University of Zurich and senior author of the study. "The extinction of this iconic giant shark likely impacted global nutrient transport and released large cetaceans from a strong predatory pressure."

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Floating 'artificial leaves' ride the wave of clean fuel production

Researchers have developed floating 'artificial leaves' that generate clean fuels from sunlight and water, and could eventually operate on a large scale at sea.

The researchers, from the University of Cambridge, designed ultra-thin, flexible devices, which take their inspiration from photosynthesis -- the process by which plants convert sunlight into food. Since the low-cost, autonomous devices are light enough to float, they could be used to generate a sustainable alternative to petrol without taking up space on land.

Outdoor tests of the lightweight leaves on the River Cam -- near iconic Cambridge sites including the Bridge of Sighs, the Wren Library and King's College Chapel -- showed that they can convert sunlight into fuels as efficiently as plant leaves.

This is the first time that clean fuel has been generated on water, and if scaled up, the artificial leaves could be used on polluted waterways, in ports or even at sea, and could help reduce the global shipping industry's reliance on fossil fuels. The results are reported in the journal Nature.

While renewable energy technologies, such as wind and solar, have become significantly cheaper and more available in recent years, for industries such as shipping, decarbonisation is a much taller order. Around 80% of global trade is transported by cargo vessels powered by fossil fuels, yet the sector has received remarkably little attention in discussions around the climate crisis.

For several years, Professor Erwin Reisner's research group in Cambridge has been working to address this problem by developing sustainable solutions to petrol which are based on the principles of photosynthesis. In 2019, they developed an artificial leaf, which makes syngas -- a key intermediate in the production of many chemicals and pharmaceuticals -- from sunlight, carbon dioxide and water.

The earlier prototype generated fuel by combining two light absorbers with suitable catalysts. However, it incorporated thick glass substrates and moisture protective coatings, which made the device bulky.

"Artificial leaves could substantially lower the cost of sustainable fuel production, but since they're both heavy and fragile, they're difficult to produce at scale and transport," said Dr Virgil Andrei from Cambridge's Yusuf Hamied Department of Chemistry, the paper's co-lead author.

"We wanted to see how far we can trim down the materials these devices use, while not affecting their performance," said Reisner, who led the research. "If we can trim the materials down far enough that they're light enough to float, then it opens up whole new ways that these artificial leaves could be used."

For the new version of the artificial leaf, the researchers took their inspiration from the electronics industry, where miniaturisation techniques have led to the creation of smartphones and flexible displays, revolutionising the field.

The challenge for the Cambridge researchers was how to deposit light absorbers onto lightweight substrates and protect them against water infiltration. To overcome these challenges, the team thin-film metal oxides and materials known as perovskites, which can be coated onto flexible plastic and metal foils. The devices were covered with micrometre thin, water-repellent carbon-based layers that prevented moisture degradation. They ended up with a device that not only works, but also looks like a real leaf.

"This study demonstrates that artificial leaves are compatible with modern fabrication techniques, representing an early step towards the automation and up-scaling of solar fuel production," said Andrei. "These leaves combine the advantages of most solar fuel technologies, as they achieve the low weight of powder suspensions and the high performance of wired systems."

Tests of the new artificial leaves showed that they can split water into hydrogen and oxygen, or reduce CO2 to syngas. While additional improvements will need to be made before they are ready for commercial applications, the researchers say this development opens whole new avenues in their work.

"Solar farms have become popular for electricity production; we envision similar farms for fuel synthesis," said Andrei. "These could supply coastal settlements, remote islands, cover industrial ponds, or avoid water evaporation from irrigation canals."

"Many renewable energy technologies, including solar fuel technologies, can take up large amounts of space on land, so moving production to open water would mean that clean energy and land use aren't competing with one another," said Reisner. "In theory, you could roll up these devices and put them almost anywhere, in almost any country, which would also help with energy security."

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Ready for its close-up: New technology sharpens images of black holes

When scientists unveiled humanity's historic first image of a black hole in 2019 -- depicting a dark core encircled by a fiery aura of material falling toward it -- they believed even richer imagery and insights were waiting to be teased out of the data.

Simulations predict that, obscured by that bright orange glow, there should exist a thin, bright ring of light created by photons flung around the back of the black hole by its intense gravity.

Now, a team of researchers has combined theoretical predictions and sophisticated imaging algorithms to "remaster" the original imagery of the supermassive black hole at the center of the galaxy M87*, first captured by the Event Horizon Telescope (EHT) in 2019. Their findings, published today in The Astrophysical Journal, are consistent with theoretical predictions and offer new ways to explore these mysterious objects, which are believed to reside at the hearts of most galaxies.

"The approach we took involved leveraging our theoretical understanding of how these black holes look to build a customized model for the EHT data," says Dominic Pesce, a study co-author based at the Center for Astrophysics | Harvard & Smithsonian and member of the EHT collaboration. "Our model decomposes the reconstructed image into the two pieces that we care most about, so that we can study both pieces individually rather than blended together."

The result was made possible because the EHT is a "computational instrument at its heart," says Avery Broderick, who led the study and holds the Delaney Family John Archibald Wheeler Chair at the Perimeter Institute. "It is as dependent on algorithms as it is upon steel. Cutting-edge algorithmic developments have allowed us to probe key features of the image while rendering the remainder in the EHT's native resolution."

To achieve this result, the team employed imaging software they developed called THEMIS, which enabled them to isolate the distinct ring features from the original observations of the M87* black hole -- as well as reveal the telltale footprint of a powerful jet blasting outward from the black hole.

By essentially "peeling off" elements of the imagery, says co-author Hung-Yi Pu, an assistant professor at National Taiwan Normal University, "the environment around the black hole can then be clearly revealed."

Black holes were long considered unseeable until scientists coaxed them out of hiding with a globe-spanning network of telescopes known as the EHT. Using eight observatories on four continents, all pointed at the same spot in the sky and linked together with nanosecond timing, the EHT researchers observed two black holes in 2017.

The EHT collaboration first unveiled the supermassive black hole in M87* in 2019. Later in 2022, they revealed the comparatively small but tumultuous black hole at the heart of our own Milky Way galaxy, called Sagittarius A* (or Sgr A*).

Supermassive black holes occupy the centers of most galaxies, packing an incredible amount of mass and energy into a small space; the M87* black hole, for example, is 2 quadrillion (that's a two followed by 15 zeros) times more massive than Earth.

The M87* image that scientists unveiled in 2019 was a landmark discovery, but the researchers felt that they could still sharpen the image further and glean new insights. By applying their new software technique to the original 2017 data, the team was able to focus the data's constraining power on phenomena that theories and models predict are lurking beneath the surface.

The newly-developed technique is just now showing its promise on the existing EHT data from 2017.

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Solving Everest's wildlife mysteries with eDNA

A team of scientists led by the Wildlife Conservation Society (WCS) and Appalachian State University used environmental DNA (eDNA) to document the breadth of high-alpine biodiversity present on Earth's highest mountain, 29,032-foot Mt. Everest (8,849 m).

Describing their findings in the journal iScience, the team collected eDNA from water samples over a four-week period in ten ponds and streams between 14,763 feet (4,500 meters) and 18,044 feet (5,500 meters). The sites included areas of the alpine zone that exist above the tree line and contain an array of flowering plants and shrub species, along with the aeolian zone that reaches beyond the range of flowering plants and shrubs at the uppermost reaches of the biosphere. From just 20 liters of water, they identified organisms belonging to 187 taxonomic orders, which corresponds to 16.3 percent, or one sixth, of the total known orders across the tree of life -- a family tree of Earth's biodiversity.

eDNA searches for trace amounts of genetic material left behind by organisms and wildlife and offers a more accessible, rapid, and comprehensive approach to increasing survey capacity for assessing biodiversity in aquatic environments. Samples are collected using a sealed cartridge containing a filter that captures genetic material that is later analyzed at a lab using DNA metabarcoding and other sequencing methodologies. WCS has been using eDNA for detection of rare and threatened species from humpback whales to Swinhoe's softshell turtle, one of the rarest species on the planet.

Although the Everest study focused on identification at the order level, the team was able to identify many organisms to the genus or species level.

For example, the team identified both rotifers and tardigrades, two tiny animal organisms that are known to occur in the harshest and most extreme environments and are considered to be among the most resilient animals known on Earth. In addition, they identified Tibetan snow cock, which are found in Sagarmatha National Park, and were surprised to find species such as domestic dog and chicken, representing how human activities are influencing the landscape.

They also identified pine trees, which only are found far downhill from where they sampled, demonstrating how wind-blown pollen can make its way high up into these watersheds. Another organism they identified from several sites were mayflies, which are known indicator species for environmental change.

The eDNA inventory will aid future high-Himalayan biomonitoring and retrospective molecular studies to assess changes over time as climate-driven warming, glacial melt, and human-caused influences reshape this rapidly transforming world-renowned ecosystem.

Said Dr. Tracie Seimon of WCS's Zoological Health Program, co-lead of the Everest biology field team and lead of the study: "High-alpine and aeolian environments, which have often been thought of as barren and mostly devoid of life, in fact have abundant biodiversity. High mountain environments including Mount Everest should be recognized as a target for sustained long-term biodiversity monitoring of high-alpine taxa to complement bioclimatic monitoring and climate change impact assessments."

Said Dr. Marisa Lim of the Wildlife Conservation Society: "We went in search for life on the roof of the world. This is what we found. However, the story does not end here. There is more to be discovered and we hope our findings help to inform future exploration."

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Exercise answer: Research shows it's how often you do it, not how much

So… should I exercise a little bit every day, or exercise for longer once a week?

It's a dilemma faced by many health-conscious people -- and new research from Edith Cowan University (ECU) is answering the question.

This latest research indicates a little bit of daily activity could well be the most beneficial approach, at least for muscle strength.

And happily, it also suggests you don't have to put in a mountain of work every day.

In collaboration with Niigata University and Nishi Kyushu University in Japan, the four-week training study had three groups of participants performing an arm resistance exercise and changes in muscle strength and muscle thickness were measured and compared.

The exercise consisted of 'maximal voluntary eccentric bicep contractions' performed on a machine which measures muscle strength in each muscle contraction you would do at the gym.

An eccentric contraction is when the muscle is lengthening; in this case, like lowering a heavy dumbbell in a bicep curl.

Two groups performed 30 contractions per week, with one group doing six contractions a day for five days a week (6x5 group), while the other crammed all 30 into a single day, once a week (30x1 group).

Another group only performed six contractions one day a week.

After four weeks, the group doing 30 contractions in a single day did not show any increase in muscle strength, although muscle thickness (an indicator of increase in muscle size) increased 5.8 per cent.

The group doing six contractions once a week did not show any changes in muscle strength and muscle thickness.

However, the 6x5 group saw significant increases in muscle strength -- more than 10 per cent -- with an increase in muscle thickness similar to the 30x1 group.

Frequency, not volume

Importantly, the increase in muscle strength of the 6x5 group was similar to the group in a previous study that performed only one three-second maximal eccentric contraction per day for five days a week for four weeks.

ECU Exercise and Sports Science Professor Ken Nosaka said these studies continue to suggest very manageable amounts of exercise done regularly can have a real effect on people's strength.

"People think they have to do a lengthy session of resistance training in the gym, but that's not the case," he said.

"Just lowering a heavy dumbbell slowly once or six times a day is enough."

Professor Nosaka said while the study required participants to exert maximum effort, early findings from current, ongoing research indicated similar results could be achieved without needing to push as hard as possible.

"We only used the bicep curl exercise in this study, but we believe this would be the case for other muscles also, at least to some extent," he said.

"Muscle strength is important to our health. This could help prevent a decrease in muscle mass and strength with ageing.

"A decrease in muscle mass is a cause of many chronic disease such as cardiovascular disease, type 2 diabetes, some cancers, dementia, plus musculoskeletal problems such as osteoporosis."

Rest up

It is not yet known precisely why the body responds better to resistance exercises with eccentric contractions in smaller doses rather than bigger loads less frequently.

Professor Nosaka said it may relate to how often the brain is asked to make a muscle perform in a particular manner.

However, he stressed it was also important to include rest in an exercise regimen.

"In this study, the 6x5 group had two days off per week," he said.

"Muscle adaptions occur when we are resting; if someone was able to somehow train 24 hours a day, there would actually be no improvement at all.

"Muscles need rest to improve their strength and their muscle mass, but muscles appear to like to be stimulated more frequently."

He also highlighted if someone was unable to exercise for a period, there was no value in trying to "make up" for it with a longer session later.

"If someone's sick and can't exercise for a week, that's fine, but it is better to just return to regular exercise routine when you're feeling better" he said.

Clarifying advice

Current Australian Government guidelines already indicate adults should try to be active every day and perform 2.5-5 hours of moderate physical activity per week.

Professor Nosaka said there needed to be more emphasis on the importance of making exercise a daily activity, rather than hitting a weekly minute goal.

"If you're just going to the gym once a week, it's not as effective as doing a bit of exercise every day at home," he said.

"This research, together with our previous study, suggests the importance of accumulating a small amount of exercise a week, than just spending hours exercising once a week.

"We need to know that every muscle contraction counts, and it's how regularly you perform them that counts."

Read more at Science Daily

Today's heat waves feel a lot hotter than heat index implies

If you looked at the heat index during this summer's sticky heat waves and thought, "It sure feels hotter!," you may be right.

An analysis by climate scientists at the University of California, Berkeley, finds that the apparent temperature, or heat index, calculated by meteorologists and the National Weather Service (NWS) to indicate how hot it feels -- taking into account the humidity -- underestimates the perceived temperature for the most sweltering days we're now experiencing, sometimes by more than 20 degrees Fahrenheit.

The finding has implications for those who suffer through these heat waves, since the heat index is a measure of how the body deals with heat when the humidity is high, and sweating becomes less effective at cooling us down. Sweating and flushing, where blood is diverted to capillaries close to the skin to dissipate heat, plus shedding clothes, are the main ways humans adapt to hot temperatures.

A higher heat index means that the human body is more stressed during these heat waves than public health officials may realize, the researchers say. The NWS currently considers a heat index above 103 to be dangerous, and above 125 to be extremely dangerous.

"Most of the time, the heat index that the National Weather Service is giving you is just the right value. It's only in these extreme cases where they're getting the wrong number," said David Romps, UC Berkeley professor of earth and planetary science. "Where it matters is when you start to map the heat index back onto physiological states and you realize, oh, these people are being stressed to a condition of very elevated skin blood flow where the body is coming close to running out of tricks for compensating for this kind of heat and humidity. So, we're closer to that edge than we thought we were before."

Romps and graduate student Yi-Chuan Lu detailed their analysis in a paper accepted by the journal Environmental Research Letters and posted online Aug. 12.

The heat index was devised in 1979 by a textile physicist, Robert Steadman, who created simple equations to calculate what he called the relative "sultriness" of warm and humid, as well as hot and arid, conditions during the summer. He saw it as a complement to the wind chill factor commonly used in the winter to estimate how cold it feels.

His model took into account how humans regulate their internal temperature to achieve thermal comfort under different external conditions of temperature and humidity -- by consciously changing the thickness of clothing or unconsciously adjusting respiration, perspiration and blood flow from the body's core to the skin.

In his model, the apparent temperature under ideal conditions -- an average-sized person in the shade with unlimited water -- is how hot someone would feel if the relative humidity were at a comfortable level, which Steadman took to be a vapor pressure of 1,600 pascals.

For example, at 70% relative humidity and 68 F -- which is often taken as average humidity and temperature -- a person would feel like it's 68 F. But at the same humidity and 86 F, it would feel like 94 F.

The heat index has since been adopted widely in the United States, including by the NWS, as a useful indicator of people's comfort. But Steadman left the index undefined for many conditions that are now becoming increasingly common. For example, for a relative humidity of 80%, the heat index is not defined for temperatures above 88 F or below 59 F. Today, temperatures routinely rise above 90 F for weeks at a time in some areas, including the Midwest and Southeast.

To account for these gaps in Steadman's chart, meteorologists extrapolated into these areas to get numbers that, Romps said, are correct most of the time, but not based on any understanding of human physiology.

"There's no scientific basis for these numbers," Romps said.

He and Lu set out to extend Steadman's work so that the heat index is accurate at all temperatures and all humidities between zero and 100%.

"The original table had a very short range of temperature and humidity and then a blank region where Steadman said the human model failed," Lu said. "Steadman had the right physics. Our aim was to extend it to all temperatures so that we have a more accurate formula."

One condition under which Steadman's model breaks down is when people perspire so much that sweat pools on the skin. At that point, his model incorrectly had the relative humidity at the skin surface exceeding 100%, which is physically impossible.

"It was at that point where this model seems to break, but it's just the model telling him, hey, let sweat drip off the skin. That's all it was," Romps said. "Just let the sweat drop off the skin."

That and a few other tweaks to Steadman's equations yielded an extended heat index that agrees with the old heat index 99.99% of the time, Romps said, but also accurately represents the apparent temperature for regimes outside those Steadman originally calculated. When he originally published his apparent temperature scale, he considered these regimes too rare to worry about, but high temperatures and humidities are becoming increasingly common because of climate change.

Romps and Lu published the revised heat index equation earlier this year. In the most recent paper, they apply the extended heat index to the top 100 heat waves that occurred between 1984 and 2020. The researchers find mostly minor disagreements with what the NWS reported at the time, but also some extreme situations where the NWS heat index was way off.

One surprise was that seven of the 10 most physiologically stressful heat waves over that time period were in the Midwest -- mostly in Illinois, Iowa and Missouri -- not the Southeast, as meteorologists assumed. The largest discrepancies between the NWS heat index and the extended heat index were seen in a wide swath, from the Great Lakes south to Louisiana.

During the July 1995 heat wave in Chicago, for example, which killed at least 465 people, the maximum heat index reported by the NWS was 135 F, when it actually felt like 154 F. The revised heat index at Midway Airport, 141 F, implies that people in the shade would have experienced blood flow to the skin that was 170% above normal. The heat index reported at the time, 124 F, implied only a 90% increase in skin blood flow. At some places during the heat wave, the extended heat index implies that people would have experienced an increase of 820% above normal skin blood flow.

"I'm no physiologist, but a lot of things happen to the body when it gets really hot," Romps said. "Diverting blood to the skin stresses the system because you're pulling blood that would otherwise be sent to internal organs and sending it to the skin to try to bring up the skin's temperature. The approximate calculation used by the NWS, and widely adopted, inadvertently downplays the health risks of severe heat waves."

Physiologically, the body starts going haywire when the skin temperature rises to equal the body's core temperature, typically taken as 98.6 F. After that, the core temperature begins to increase. The maximum sustainable core temperature is thought to be 107 F -- the threshold for heat death. For the healthiest of individuals, that threshold is reached at a heat index of 200 F.

Luckily, humidity tends to decrease as temperature increases, so Earth is unlikely to reach those conditions in the next few decades. Less extreme, though still deadly, conditions are nevertheless becoming common around the globe.

"A 200 F heat index is an upper bound of what is survivable," Romps said. "But now that we've got this model of human thermoregulation that works out at these conditions, what does it actually mean for the future habitability of the United States and the planet as a whole? There are some frightening things we are looking at."

Read more at Science Daily

Underwater snow gives clues about Europa's icy shell

Below Europa's thick icy crust is a massive, global ocean where the snow floats upwards onto inverted ice peaks and submerged ravines. The bizarre underwater snow is known to occur below ice shelves on Earth, but a new study shows that the same is likely true for Jupiter's moon, where it may play a role in building its ice shell.

The underwater snow is much purer than other kinds of ice, which means Europa's ice shell could be much less salty than previously thought. That's important for mission scientists preparing NASA's Europa Clipper spacecraft, which will use radar to peek beneath the ice shell to see if Europa's ocean could be hospitable to life. The new information will be critical because salt trapped in the ice can affect what and how deep the radar will see into the ice shell, so being able to predict what the ice is made of will help scientists make sense of the data.

The study, published in the August edition of the journal Astrobiology, was led by The University of Texas at Austin, which is also leading the development of Europa Clipper's ice penetrating radar instrument. Knowing what kind of ice Europa's shell is made of will also help decipher the salinity and habitability of its ocean.

"When we're exploring Europa, we're interested in the salinity and composition of the ocean, because that's one of the things that will govern its potential habitability or even the type of life that might live there," said the study's lead author Natalie Wolfenbarger, a graduate student researcher at the University of Texas Institute for Geophysics (UTIG) in the UT Jackson School of Geosciences.

Europa is a rocky world about the size of the Earth's moon that is surrounded by a global ocean and a miles-thick ice shell. Previous studies suggest the temperature, pressure and salinity of Europa's ocean nearest to the ice is similar to what you would find beneath an ice shelf in Antarctica.

Armed with that knowledge, the new study examined the two different ways that water freezes under ice shelves, congelation ice and frazil ice. Congelation ice grows directly from under the ice shelf. Frazil ice forms as ice flakes in supercooled seawater which float upwards through the water, settling on the bottom of the ice shelf.

Both ways make ice that's less salty than seawater, which Wolfenbarger found would be even less salty when scaled up to the size and age of Europa's ice shell. What's more, according to her calculations, frazil ice -- which keeps only a tiny fraction of the salt in seawater -- could be very common on Europa. That means its ice shell could be orders of magnitude purer than previous estimates. This affects everything from its strength, to how heat moves through it, and forces that might drive a kind of ice tectonics.

"This paper is opening up a whole new batch of possibilities for thinking about ocean worlds and how they work," said Steve Vance, a research scientist at NASA's Jet Propulsion Laboratory (JPL) who was not involved in the study. "It sets the stage for how we might prepare for Europa Clipper's analysis of the ice."

According to co-author Donald Blankenship, a senior research scientist at UTIG and principal investigator for Europa Clipper's ice penetrating radar instrument, the research is validation for using the Earth as a model to understand the habitability of Europa.

"We can use Earth to evaluate Europa's habitability, measure the exchange of impurities between the ice and ocean, and figure out where water is in the ice," he said.

Read more at Science Daily

All the better to better eat you with -- dinosaurs evolved different eye socket shapes to allow stronger bites

Large dinosaur predators, such as Tyrannosaurus rex, evolved different shapes of eye sockets to better deal with high bite forces, new research has shown.

While in many animals -- and most dinosaurs -- the eye socket is just a circular hole in the skull housing the eyeball, this is very different in large carnivores.

In a new study, published today in Communications Biology, researchers at the University of Birmingham reveal how the unusual elliptical, or oval eye sockets found in the skulls of these predators, could have evolved to help the skull absorb impact as they pounced on prey.

Dr Stephan Lautenschlager, Senior Lecturer for Palaeobiology at the University of Birmingham and author of the new study, analysed the shape of the eye sockets of ca. 500 different dinosaurs and related species.

"The results show that only some dinosaurs had eye sockets that were elliptical or keyhole-shaped," said Dr Stephan Lautenschlager. "However, all of those were large, carnivorous dinosaurs with skull lengths of 1 m or more."

Using computer simulations and stress analysis, Dr Lautenschlager tested what purpose these unusual eye socket shapes could have.

The results demonstrated that a skull with a circular eye socket was more prone to high stresses during biting. However, if these were replaced with other eye socket shapes stresses were considerably reduced allowing top predators, including Tyrannosaurus rex, to evolve high bite forces without compromising skull stability.

The study also showed that most plant-eating species and juvenile individuals retained a circular eye socket. Only large carnivores adopted other morphologies, such as elliptical, keyhole-shaped or figure-of-eight-shaped eye sockets.

Dr Lautenschlager added: "In these species, just the upper part of the eye socket was actually occupied by the eyeball. This also led to a relative reduction of eye size compared with skull size."

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Nuclear war would cause a global famine and kill billions

More than 5 billion people would die of hunger following a full-scale nuclear war between the U.S. and Russia, according to a global study led by Rutgers climate scientists that estimates post-conflict crop production.

"The data tell us one thing: We must prevent a nuclear war from ever happening," said Alan Robock, a Distinguished Professor of climate science in the Department of Environmental Sciences at Rutgers Universityand co-author of the study. Lili Xia, an assistant research professor in the Department of Environmental Sciences at Rutgers,is lead author of the study published in the journal Nature Food.

Building on past research, Xia, Robock and their colleagues worked to calculate how much Sun-blocking soot would enter the atmosphere from firestorms that would be ignited by the detonation of nuclear weapons. Researchers calculated soot dispersal from six war scenarios -- five smaller India-Pakistan wars and a large U.S.-Russia war -- based on the size of each country's nuclear arsenal.

These data then were entered into the Community Earth System Model, a climate forecasting tool supported by the National Center for Atmospheric Research (NCAR). The NCAR Community Land Model made it possible to estimate productivity of major crops (maize, rice, spring wheat and soybean) on a country-by-country basis. The researchers also examined projected changes to livestock pasture and in global marine fisheries.

Under even the smallest nuclear scenario, a localized war between India and Pakistan, global average caloric production decreased 7 percent within five years of the conflict. In the largest war scenario tested -- a full-scale U.S.-Russia nuclear conflict -- global average caloric production decreased by about 90 percent three to four years after the fighting.

Crop declines would be the most severe in the mid-high latitude nations, including major exporting countries such as Russia and the U.S., which could trigger export restrictions and cause severe disruptions in import-dependent countries in Africa and the Middle East.

These changes would induce a catastrophic disruption of global food markets, the researchers conclude. Even a 7 percent global decline in crop yield would exceed the largest anomaly ever recorded since the beginning of Food and Agricultural Organization observational records in 1961. Under the largest war scenario, more than 75 percent of the planet would be starving within two years.

Researchers considered whether using crops fed to livestock as human food or reducing food waste could offset caloric losses in a war's immediate aftermath, but the savings were minimal under the large injection scenarios.

"Future work will bring even more granularity to the crop models," Xia said.

"For instance, the ozone layer would be destroyed by the heating of the stratosphere, producing more ultraviolet radiation at the surface, and we need to understand that impact on food supplies," she said.

Climate scientists at the University of Colorado, which partnered with Rutgers on the study, are also creating detailed soot models for specific cities, such as Washington, D.C., with inventories of every building to get a more accurate picture of how much smoke would be produced.

Robock said researchers already have more than enough information to know that a nuclear war of any size would obliterate global food systems, killing billions of people in the process.

"If nuclear weapons exist, they can be used, and the world has come close to nuclear war several times," Robock said. "Banning nuclear weapons is the only long-term solution. The five-year-old UN Treaty on the Prohibition of Nuclear Weapons has been ratified by 66 nations, but none of the nine nuclear states. Our work makes clear that it is time for those nine states to listen to science and the rest of the world and sign this treaty."

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Road signs for immune defense cells

Organisms are constantly invaded by pathogens such as viruses. Our immune system swings into action to combat these pathogens immediately. The innate non-specific immune response is triggered first, and the adaptive or acquired immune response follows. In this second defence reaction, specialised cytotoxic T lymphocytes known as killer T cells destroy cells in the body that have been infected and thus prevent damage from spreading. Humans possess a repertoire of some 20 million T cell clones with varying specificity to counter the multitude of infectious agents that exist. But how do the killer T cells know where danger is coming from? How do they recognise that something is wrong inside a cell in which viruses are lurking? They can't just have a quick peek inside.

At this point, antigen processing comes into play. The process can be compared to making a road sign. The molecular barcode is "processed" or assembled in the cell -- in the endoplasmic reticulum, to be exact. Special molecules are used in its making, the MHC class I molecules. They are loaded with information about the virus invader in a molecular machine, the peptide loading complex (PLC). This information consists of peptides, fragments of the protein foreign to the body. These fragments also contain epitopes, the molecular segments that elicit a specific immune response. During the loading process, an MHC I-peptide epitope complex thus forms, and this is the road sign that is then transported to the surface of the cell and presented in a readily accessible form to the killer T cells -- we could almost say that it is handed to them on a silver platter. The chaperones, special accessory proteins that assist the correct folding of proteins with complex structures in cells, also play a significant role.

The chaperones that support antigen processing are calreticulin, ERp57, and tapasin. But how do they work together? And how important are they for antigen processing? An answer has now been supplied by a study carried out by Goethe University Frankfurt and the University of Oxford and published in Nature Communications. "With this study, we have achieved a breakthrough in our understanding of cellular quality control," says Professor Robert Tampé, Director of the Institute of Biochemistry at Goethe University Frankfurt. He explains the logic underlying this quality control process as follows: "The MHC I-peptide epitope complex, the road sign, needs to be exceptionally stable, and for quite a long time, because the adaptive immune response does not start instantly. It needs 3 to 5 days to get going." So, the sign must not collapse after one day; that would be disastrous, as the immune defence cells would then fail to detect cells infected by a virus. This would mean that they would not destroy these cells and the virus would be able to continue its spread unhindered. A similar problem would arise if a cell in the body had mutated into a tumour cell: the threat would remain undetected. It is imperative, therefore, that a quality control system is in place.

As the study shows, the chaperones are central process components: they give the road sign the long-term stability it must have by making a strict selection. By rejecting the short-lived virus fragments in the mass of available material, they ensure that only MHC I molecules loaded with the best and most stable peptide epitopes in complex with MHC I are released from the peptide loading complex. The chaperones have different tasks in this selection process that is so important for the adaptive immune response, Tampé says: "Tapasin acts as a catalyst that accelerates the exchange of suboptimal peptide epitopes for optimal epitopes. Calreticulin and ERp57, in contrast, are deployed universally." This concerted approach ensures that only stable MHC I complexes with optimal peptide epitopes reach the cell surface and perform their role of guiding the killer T cells to the infected or mutated cell.

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Meteorite provides record of asteroids 'spitting out' pebbles

In 2019, NASA's OSIRIS-REx spacecraft sent back images of a geological phenomenon no one had ever seen before: pebbles were flying off the surface of the asteroid Bennu. The asteroid appeared to be shooting off swarms of marble-sized rocks. Scientists had never seen this behavior from an asteroid before, and it's a mystery exactly why it happens. But in a new paper in Nature Astronomy, researchers show the first evidence of this process in a meteorite.

"It's fascinating to see something that was just discovered by a space mission on an asteroid millions of miles away from Earth, and find a record from the same geological process in the museum's meteorite collection," says Philipp Heck, the Robert A. Pritzker Curator of Meteoritics at Chicago's Field Museum and the senior author of the Nature Astronomy study.

Meteorites are pieces of rock that fall to Earth from outer space; they can be made of pieces of moons and planets, but most often, they're broken-off bits of asteroids. The Aguas Zarcas meteorite is named after the Costa Rican town where it fell in 2019; it came to the Field Museum as a donation from Terry and Gail Boudreaux. Heck and his student, Xin Yang, were preparing the meteorite for another study when they noticed something strange.

"We were trying to isolate very tiny minerals from the meteorite by freezing it with liquid nitrogen and thawing it with warm water, to break it up," says Yang, a graduate student at the Field Museum and the University of Chicago and the paper's first author. "That works for most meteorites, but this one was kind of weird -- we found some compact fragments that wouldn't break apart."

Heck says that finding bits of meteorite that won't disintegrate isn't unheard of, but scientists usually just shrug and break out the mortar and pestle. "Xin had a very open mind, he said, 'I'm not going to crush these pebbles to sand, this is interesting,'" says Heck. Instead, the researchers devised a plan to figure out what these pebbles were and why they were so resistant to breaking apart.

"We did CT scans to see how the pebbles compared to the other rocks making up the meteorite," says Heck. "What was striking is that these components were all squished -- normally, they'd be spherical -- and they all had the same orientation. They were all deformed in the same direction, by one process." Something had happened to the pebbles that didn't happen to the rest of the rock around them.

"This was exciting, we were very curious about what it meant," says Yang.

The scientists had a clue, though, from the 2019 OSIRIS-REx findings. From there, they put together a hypothesis, which they supported with physical models. The asteroid underwent a high-speed collision, and the area of impact got deformed. That deformed rock eventually broke apart due to the huge temperature differences the asteroid experiences when it rotates, since the side facing the sun is more than 300° F warmer than the side facing away. "This constant thermal cycling makes the rock brittle, and it breaks apart into gravel," says Heck.

These pebbles are then ejected from the asteroid's surface. "We don't yet know what the process is that ejects the pebbles," says Heck -- they might be dislodged by smaller impacts other space collisions, or they might just get released by the thermal stress the asteroid undergoes. But once the pebbles are disturbed, Heck says, "you don't need much to eject something -- the escape velocity is very low." A recent study of Bennu revealed that its surface is loosely bound and behaves like popcorn in a bucket.

The pebbles then entered a very slow orbit around the asteroid, and eventually, they fell back down to its surface further away where there was no deformation. Then, Heck and Yang say, the asteroid underwent another collision, the loose mixed pebbles on the surface got transformed into a solid rock. "It basically packed everything together, and this loose gravel became a cohesive rock," says Heck. The same impact may have dislodged the new rock, sending it careening into space. Eventually, that chunk fell to Earth as the Aguas Zarcas meteorite, carrying evidence of the pebble mixing.

This could explain the pebbles present in Aguas Zarcas, making the meteorite the first physical evidence of the geological process observed by OSIRIS-REx on Bennu. "It provides a new way of explaining the way that minerals on the surfaces of asteroids get mixed," says Yang.

That's a big deal, Heck says, because for a long time, scientists assumed that the main way that the minerals on the surfaces of asteroids get rearranged is through big crashes, which don't happen very often. "From OSIRIS-REx we know that these particle ejection events are much more frequent than these high-velocity impacts," says Heck, "so they probably play a more important role in determining the makeup of asteroids and meteorites."

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Newly identified fossil insect used 360-degree vision and sticky feet to find and snare its meals

With bulging eyes, an elongated mouth and feet that oozed resin, a fossil insect identified by Oregon State University research is so different from anything alive today that it needed to be placed in its own, extinct family.

George Poinar Jr., professor emeritus in the OSU College of Science, named the insect Palaeotanyrhina exophthalma in a paper published in BioOne Complete. Encased in 100-million-year-old amber from Burma, P. exophthalma is a member of the Hemiptera order -- a "true bug," Poinar said.

"It is a small predator that used its protruding eyes to locate insect prey," said Poinar, an international expert in using plant and animal life forms preserved in amber to learn about the biology and ecology of the distant past.

More than 80,000 species including cicadas, aphids, planthoppers, leafhoppers, bed bugs and shield bugs comprise the order of Hemiptera, an ancient Greek word meaning half-winged. True bugs' size varies widely, from as small as 1 millimeter to as large as 15 centimeters, but they all have a similar arrangement of sucking mouthparts.

P. exophthalma has a body length of just over 5 millimeters. It shares some features with members of the Reduvoidea superfamily, which includes the assassin bug and the kissing bug, but its long labium (lower mouth), its head shape and its forewing veins disqualify it from placement in any modern Reduvoidea family, Poinar said.

Thus he assigned it to a new, extinct family: Palaeotanyrhinidae.

"Its eyes provided a clear, 360-degree view of its habitat so it could see prey that might appear from any side," Poinar said.

It reminded Poinar of the phrase, "Big brother is always watching you," from George Orwell's novel "1984" in which security cameras followed individuals' every movement.

The other strange feature on this fossil is an extended sheath on the final leg segment of the front tarsus, he added.

"That sheath was filled with a resinous substance," Poinar said. "The sticky substance was produced by dermal glands and helped the insect grasp potential prey."

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Sponges 'sneeze' to dispose of waste

Sneezing out mucus may be one of the oldest ways for organisms to get rid of unwanted waste. A group of researchers found that sponges, one of the oldest multicellular organisms in existence, "sneeze" to unclog their internal filter systems that they use to capture nutrients from the water. Additionally, authors find that other animals who live with the sponges use their mucus as food. Their findings are publishing August 10 in the journal Current Biology.

"Our data suggest that sneezing is an adaptation that sponges evolved to keep themselves clean," says Jasper de Goeij, a marine biologist at the University of Amsterdam and the senior author of the paper.

While the field has known about this behavior for years, the authors of this paper show that these sneezes get rid of materials the sponges cannot use. "Let's be clear: sponges don't sneeze like humans do. A sponge sneeze takes about half an hour to complete. But both sponge and human sneezes exist as a waste disposal mechanism," says de Goeij.

Sponges gather food for themselves by filtering out organic matter from the water. They draw in and eject water from different openings, and sometimes the sponges will suck in particles that are too big. "These are sponges; they can't just walk to somewhere else when the water around them gets too dirty for them to handle," says de Goeij. This is when the "sneezing" mechanism comes in handy.

In videos that the authors included in the paper, you can see the water inlets slowly release mucus, and the mucus will accumulate at the surface of the sponge. Occasionally, sponge tissue will contract and push the waste-containing mucus into the surrounding water.

While the mucus may be waste to sponges, the fishes who live around them think otherwise. "We also observed fish and other animals feeding off of the sponge mucus as food," says Niklas Kornder, the first author of the study and a doctoral researcher in de Goeij's research group. "Some organic matter exists in the water surrounding the coral reef, but most of it is not concentrated enough for other animals to eat. Sponges transform this material into eatable mucus," says Kornder.

The paper recorded "sneezing" behavior in two species of sponges, the Caribbean tube sponge Aplysina archeri and another Indo-Pacific species of the genus Chelonaplysilla. "We actually think that most, if not all, sponges sneeze. I've seen mucus accumulate on different sponges while diving and in pictures taken by other scientists for other purposes," says Kornder.

"Our findings highlight opportunities to better understand material cycling in some of the most ancient Metazoans," say the authors in the paper.

There are still many aspects about sponge "sneezes" that remain open questions. "In the videos, you can see that the mucus moves along defined paths on the surface of the sponge before accumulating. I have some hypotheses, but more analysis is needed to find out what is happening," says Kornder.

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