Category: Science

New research with pythons and lizards identifies a gene that results in white blotches, or piebald coloration, in reptiles.

Much of what we know about skin coloration and patterning in vertebrates generally, including in snakes, is based on lab mice. However, there are limits to what mice can tell us about other vertebrates because they don’t share all of the same types of color-producing cells, known as chromatophores. For example, snakes have a type of chromatophore called iridophores that can generate iridescent colors by reflecting light.

To gain a better understanding of the genetic basis of coloration in vertebrates, researchers combined a range of techniques—whole gene sequencing, gene-editing, and electron microscopy—to look more closely at color variations and patterning in the skin shed by ball pythons bred in captivity.

They were able to identify a particular gene (tfec) that plays a crucial role in reptile pigmentation generally and more specifically in a classic color variant found across vertebrates and distinguished by blotches of white, the piebald.

The sale of captive-bred reptiles is a $1.4 billion industry within the US alone. Over 4.5 million American households keep reptiles, and close to one in five of these are snakes bred in captivity. Due to the spectacular color variations produced through captive breeding, an individual ball python (Python regius, originally found in West and Central Africa) can sell for tens of thousands of dollars.

“Ball pythons show incredible variation in skin coloring and patterning, which is part of their appeal for hobbyists, but also makes them really useful for researchers who want to understand the genetic basis of coloration,” says Rowan Barrett, interim director of McGill University’s Redpath Museum and the senior author of the paper in Current Biology.

“The pet trade has created a huge pool of color variation that would not have existed otherwise. This provides a catalogue for us to figure out the many ways that genes produce the amazing diversity of colors, spots, and stripes we see across different animals.”

To identify the genes that control a particular trait, scientists look for genetic variants that are present in animals that have the trait and absent in animals that don’t. Using shed skin collected from snake breeders, Barrett’s team found that piebald snakes carried the same mutation in the tfec gene.

But a common problem for scientists is that finding a correlation between a gene and a particular trait, such as the piebaldism, does not imply causation. To make that functional link, the McGill researchers collaborated with Doug Menke’s lab at the University of Georgia to modify tfec in a different reptile species, the brown anole lizard, using the gene-editing technology CRISPR. They found that genetically modified lizards do indeed show altered coloration, proving that mutations to tfec cause changes to color-producing cells.

“Our research advances knowledge of the genetics of vertebrate coloration generally and particularly of the development of iridescent cells, which haven’t been studied as much as other color pathways” adds Alan Garcia-Elfring, a PhD student in McGill’s biology department and the first author of the paper.

“It also highlights the potential benefits of working with non-academic communities like ball python breeders to accelerate discoveries in fundamental science. Our job, at this point, is to figure out what other mutations underlie all this variation seen in captivity, and how these mutations interact. It’s an exciting time for both researchers and reptile hobbyists.”

Source: McGill University

The Manis bone projectile point is the oldest weapon made of bone ever found in the Americas, say researchers.

The team studied bone fragments embedded in a mastodon rib bone that Carl Gustafson discovered during an excavation at the Manis site in Washington state from 1977 to 1979.

Using a CT scan and 3D software, Michael Waters, professor of anthropology at Texas A&M University, and his team isolated all the bone fragments to show it was the tip of a weapon—a projectile made from the bone of mastodon, prehistoric relatives of elephants.

“We isolated the bone fragments, printed them out, and assembled them,” says Waters, director of the university’s Center for the Study of First Americans. “This clearly showed this was the tip of a bone projectile point. This is this the oldest bone projectile point in the Americas and represents the oldest direct evidence of mastodon hunting in the Americas.”

Waters says at 13,900 years old, the Manis point is 900 years older than projectile points found to be associated with the Clovis people, whose stone tools he has also studied. Dating from 13,050 to 12,750 years ago, Clovis spear points have been found in Texas and several other sites across the country.

“What is important about Manis is that it’s the first and only bone tool that dates older than Clovis. At the other pre-Clovis site, only stone tools are found,” Waters says. “This shows that the First Americans made and used bone weapons and likely other types of bone tools.”

Stuck in a rib

He says the only reason the Manis specimen was preserved is because the hunter missed, and the projectile got stuck in the mastodon’s rib.

“We show that the bone used to make the point appears to have come from the leg bone of another mastodon and was intentionally shaped into a projectile point form,” Waters says. “The spear with the bone point was thrown at the mastodon. It penetrated the hide and tissue and eventually came into contact with the rib. The objective of the hunter was to get between the ribs and impair lung function, but the hunter missed and hit the rib.”

Waters studied the rib bone before, presenting findings in a 2011 paper in Science, in which radiocarbon dating determined the bone’s age and a genetic study of the bone fragments determined that they were mastodon.

“In our new study, we set out to isolate the bone fragments using CT images and 3D software,” he says. “We were able to create 3D images of each fragment and print them out at six times scale. Then we fit the pieces back together to show what the specimen looked like before it entered and splintered in the rib.” The new findings appear in Science Advances.

Who got to the Americas first?

Not much is known about the people who used the Manis spear point other than they were some of the first Indigenous people to enter the Americas. Waters says the Manis site and others are giving archaeologists some insight.

“It is looking like the first people that came to the Americas arrived by boat,” he says. “They took a coastal route along the North Pacific and moved south. They eventually got past the ice sheets that covered Canada and made landfall in the Pacific Northwest.

“It is interesting to note that in Idaho there is the 16,000-years-old Coopers Ferry site, in Oregon is the 14,100-year-old site of Paisley Caves. And here we report on the 13,900-year-old Manis site. So there appears to be a cluster of early sites in the Northwestern part of the United States that date from 16,000 to 14,000 years ago that predate Clovis. These sites likely represent the first people and their descendants that entered the Americas at the end of the last Ice Age.”

Source: Texas A&M University

A new technique uses liquid metal to create an elastic material that is impervious to both gases and liquids.

Applications for the material include flexible batteries and other packaging for high-value technologies that require protection from gases.

“This is an important step because there has long been a trade-off between elasticity and being impervious to gases,” says Michael Dickey, professor of chemical and biomolecular engineering at North Carolina State University.

“Basically, things that were good at keeping gases out tended to be hard and stiff. And things that offered elasticity allowed gases to seep through. We’ve come up with something that offers the desired elasticity while keeping gases out.”

The new technique makes use of a eutectic alloy of gallium and indium (EGaIn). Eutectic means that the alloy has a melting point that is lower than its constituent parts. In this case, the EGaIn is liquid at room temperature.

The researchers created a thin film of EGaIn, and encased it in an elastic polymer. The interior surface of the polymer was studded with microscale glass beads, which prevented the liquid film of EGaIn from pooling. The end result is essentially an elastic bag or sheath lined with liquid metal, which does not allow gases or liquids in or out.

The researchers tested the effectiveness of the new elastic material by assessing the extent to which it allowed liquid contents to evaporate, as well as the extent to which it allowed oxygen to leak out of a sealed container made of the material.

“We found that there was no measurable loss of either liquid or oxygen for the new material,” says Tao Deng, professor at Shanghai Jiao Tong University and co-corresponding author of the study in the journal Science.

The researchers are also conscious of costs associated with manufacturing the new material.

“The liquid metals themselves are fairly expensive,” Deng says. “However, we’re optimistic that we can optimize the technique—for example, making the EGaIn film thinner—in order to reduce the cost. At the moment, a single package would cost a few dollars, but we did not attempt to optimize for cost so there is a path forward to drive cost down.”

The researchers are currently exploring testing options to determine whether the material is actually an even more effective barrier than they’ve been able to show so far.

“Basically, we reached the limit of the testing equipment that we had available,” Dickey says.

“We’re also looking for industry partners to explore potential applications for this work. Flexible batteries for use with soft electronics is one obvious application, but other devices that either use liquids or are sensitive to oxygen will benefit from this technology.”

Additional coauthors are from Shanghai Jiao Tong University and NC State.

The National Science Foundation, the National Natural Science Foundation of China, the Innovation Program of the Shanghai Municipal Education Commission, and Shanghai Jiao Tong University supported the work.

Source: NC State

Researchers have long wondered if the IRS uses its audit powers equitably. New findings show that it does not.

Black taxpayers receive IRS audit notices at least 2.9 times (and perhaps as much as 4.7 times) more often than non-Black taxpayers, according to the working paper.

The disparity is unlikely to be intentional on the part of IRS staff, says study author Daniel E. Ho, professor of law at Stanford Law School and faculty director of the Stanford RegLab. Rather, as the team’s research demonstrated, the racial disparity in audit selection is driven by a set of internal IRS algorithms that coauthor Jacob Goldin, a professor of tax law at the University of Chicago, likens to the recipe for Coca-Cola. That is: It’s completely secret.

To better understand this audit selection bias, the research team modeled the racial impact that various alternative audit selection policies might have. The result: a demonstration of how the IRS might be able to tweak its secret algorithm to reduce its racially disparate impact.

“The IRS should drill down to understand and modify its existing audit selection methods to mitigate the disparity we’ve documented,” Ho says. “And we’ve shown they can do that without necessarily sacrificing tax revenue.”

Dependents and EITC

Although there have been long-standing questions about whether the IRS uses its audit powers equitably, Ho says, the private nature of tax returns and the confidentiality of the IRS’s approach to audit decisions made it difficult to study. That changed when, on his first day in office, President Biden signed Racial Justice Executive Order 13985 requiring all federal agencies to assess how their programs affect racial and ethnic equity. To apply that order to the IRS tax return audit program, economists at the Treasury Department collaborated with the Stanford RegLab team, allowing them to analyze (on an anonymized basis) more than 148 million tax returns and approximately 780,000 audits for tax year 2014 (an overall audit rate of 0.54%).

Even with all that data in hand, the research team faced a major hurdle: Tax returns do not ask for the taxpayer’s racial or ethnic identity. So, the team adapted and improved on a state-of-the-art approach that uses first names, last names, and geography (US Census block groups) to predict the probability that a person identifies as Black. And they validated their racial identification predictions using a sample of voter registration records from North Carolina—a state where, until recently, citizens were required to check a box for race and ethnicity when they registered to vote.

After finding that Black taxpayers were 2.9 to 4.7 times more likely to be audited than non-Black taxpayers, the team explored possible reasons for that disparity. They suspected that the problem lay with an IRS algorithm’s use of the Dependent Database, which flags a potential problem and generates an audit letter to the taxpayer. That instinct proved to be correct in that the bulk of the observed racial disparity involved so-called “correspondence” audits done by mail rather than more complex, in-person “field” audits.

The team also found that the IRS disproportionately audits people who claim the Earned Income Tax Credit (EITC)—a program that assists low- to moderate-income workers. But claiming the EITC only explains a small percentage of the observed racial disparity. The largest source of disparity occurs among EITC claimants. Indeed, Black taxpayers accounted for 21% of EITC claims, but were the focus of 43% of EITC audits.

The racial disparity in audit rates persists regardless of whether EITC claimants are male or female, married or unmarried, raising children or childless. But it is most extreme for single male taxpayers claiming dependents (7.73% for Black claimants; 3.46% for non-Black claimants) and for single male taxpayers who did not claim dependents (5.66% for Black; 2% for non-Black).

Perhaps the most striking statistic is this: A single Black man with dependents who claims the EITC is nearly 20 times as likely to be audited as a non-Black jointly filing (married) taxpayer claiming the EITC.

Why the audit disparity?

Although the team does not know the precise algorithms the IRS uses to select audits, they modeled several possible explanations for the racial disparity in audit rates.

First, they tried an “oracle” approach using a dataset called the National Research Project (NRP)—a set of nearly 72,000 tax returns that is randomly chosen for audit. Because each tax return in this dataset was subjected to a line-by-line audit, the amount of underreported tax liability is known. So the researchers considered what would happen if they pretended that an omniscient IRS selects taxpayers for audit based on the known amount of underreported tax in the NRP dataset. The result: The racial disparity in audit selection flips—an omniscient IRS aimed at capturing the most underreported income tax would audit more non-Black taxpayers than Black taxpayers.

Since auditors are not omniscient, the team also used the NRP dataset to train a model to predict—for the full 2014 dataset—the likelihood that a taxpayer has underreported income, and the magnitude of a taxpayer’s underreporting. They found that an approach focused just on the likelihood that there’s underreporting of at least $100 would result in auditing more Black taxpayers (as was observed). By contrast, a focus on the magnitude of underreporting (the amount of money unpaid by a taxpayer) would yield a result much closer to the oracle: More non-Black taxpayers would be audited than Black.

Why might this be the case? “The choice to focus on whether there is underreporting, as opposed to magnitude of underreporting, is connected to broader structural sources of economic inequality and racial justice,” says coauthor Evelyn Smith, PhD candidate at the University of Michigan. Because far more Black taxpayers have lower income, they have less opportunity to underreport substantial amounts of income. By contrast, Smith says, “focusing audits on the amount of underreported income will disproportionately end up focusing on higher income individuals who are less likely to be Black taxpayers.”

IRA audit strategy

Finally, the team wondered if the racial disparity in audits springs from IRS and even congressional concerns about refundable tax credits including not only the EITC but several others. When someone claims one of these tax credits, which are part of our country’s social safety net, they receive a refund amount even if they didn’t pay any taxes. And some in government believe it’s more important to make sure we avoid paying money to someone who claims it inappropriately than it is to make sure we collect all of the tax dollars that are due from someone engaged in some other type of tax evasion.

To test the hypothesis that this approach would have a disparate impact on Black taxpayers, the team examined what would happen if the IRS focused audits specifically on the underreporting that is due to over-claiming of refundable tax credits (the EITC as well as two others) rather than total underreporting. Their findings: This policy would result in Black taxpayers being audited at the rates similar to what the team observed in the 2014 data.

Of IRA audits, 70% happen through the mail and and 50% involve EITC claimants. That’s because, compared with labor-intensive field audits, correspondence audits of EITC claimants are easy to trigger, cost very little, and require minimal effort by IRS personnel. Unfortunately, the burden of correspondence audits on EITC claimants is more likely to fall on lower income individuals whose tax returns are less complex and less likely to lead to litigation, as this research team noted in a recent paper about vertical equity in tax audits.

In their new work, the team found that additional aspects of the IRS audit selection process driven by an impetus to reduce costs have a racially disparate impact. For example, even among correspondence audits of EITC claimants, the IRS devotes fewer resources to auditing EITC returns with business income. It’s likely that’s partly because auditing EITC returns with business income would be more expensive (approximately $385 per audit compared to $29 per audit for EITC claimants with no business income), says coauthor Hadi Elzayn, researcher at the Stanford RegLab. And, the team found, this cost-saving measure has a disparate impact on Black taxpayers, who make up only 10% of EITC claimants reporting business income but 20% of EITC claimants who don’t report business income.

Yet even if IRS resource limits explain some of the racial disparities the team observed, they don’t explain all of them. “Even holding fixed how many audits are devoted to EITC claimants who report business income, we still observe racial disparities,” Elzayn says.

Paths to fixing the issue

The study’s authors have not made any formal recommendations for how to make the IRS audit selection algorithm more just. Instead, they have documented the likely effects of alternative policies, which provides the IRS with several potential pathways for alleviating the racial impact of its audit selection system. These include predicting and focusing on the magnitude of taxpayers’ underreported income rather than just the likelihood of it; viewing dollars as equal whether they are to be paid in refundable credits or received in taxes; and using IRS resources to audit more complex returns rather than focusing only on the simpler ones that are cheaper to audit.

Before Biden signed the Racial Justice Executive Order that engendered this research project, the IRS had neither the impetus nor the ability to do that. Now that they know the equity implications of how they select audits, Ho hopes they will tweak their confidential audit selection algorithm.

“Racial disparities in income are well known, and what the IRS chooses to focus on has big implications for whether audits complement, or undercut, a progressive tax system,” Ho says.

Additional coauthors of the paper are from the University of Chicago and the US Department of the Treasury’s Office of Tax Analysis.

Source: Katharine Miller for Stanford University

A 319-million-year-old fossilized fish skull holds the oldest example of a well-preserved vertebrate brain.

Scientists pulled the skull from a coal mine in England more than a century ago. The brain and its cranial nerves are roughly an inch long and belong to an extinct bluegill-size fish. The discovery opens a window into the neural anatomy and early evolution of the major group of fishes alive today, the ray-finned fishes, according to the study in Nature.

The serendipitous find also provides insights into the preservation of soft parts in fossils of backboned animals. Most of the animal fossils in museum collections were formed from hard body parts such as bones, teeth, and shells.

The CT-scanned brain analyzed for the new study belongs to Coccocephalus wildi, an early ray-finned fish that swam in an estuary and likely dined on small crustaceans, aquatic insects, and cephalopods, a group that today includes squid, octopuses, and cuttlefish. Ray-finned fishes have backbones and fins supported by bony rods called rays.

When the fish died, the soft tissues of its brain and cranial nerves were replaced during the fossilization process with a dense mineral that preserved, in exquisite detail, their three-dimensional structure.

“An important conclusion is that these kinds of soft parts can be preserved, and they may be preserved in fossils that we’ve had for a long time—this is a fossil that’s been known for over 100 years,” says senior author Matt Friedman, a paleontologist and director of the Museum of Paleontology at the University of Michigan.

Is this really a brain?

“Not only does this superficially unimpressive and small fossil show us the oldest example of a fossilized vertebrate brain, but it also shows that much of what we thought about brain evolution from living species alone will need reworking,” says lead author Rodrigo Figueroa, a doctoral student who did the work as part of his dissertation, under Friedman, in the earth and environmental sciences department.

“With the widespread availability of modern imaging techniques, I would not be surprised if we find that fossil brains and other soft parts are much more common than we previously thought. From now on, our research group and others will look at fossil fish heads with a new and different perspective.”

The skull fossil from England is the only known specimen of its species, so only nondestructive techniques could be used during the study.

The work on Coccocephalus is part of a broader effort by Friedman, Figueroa, and colleagues that uses computed tomography (CT) scanning to peer inside the skulls of early ray-finned fishes. The goal of the larger study is to obtain internal anatomical details that provide insights about evolutionary relationships.

In the case of C. wildi, Friedman wasn’t looking for a brain when he fired up his micro-CT scanner and examined the skull fossil.

“I scanned it, then I loaded the data into the software we use to visualize these scans and noticed that there was an unusual, distinct object inside the skull,” he says.

The unidentified blob was brighter on the CT image—and therefore likely denser—than the bones of the skull or the surrounding rock.

“It is common to see amorphous mineral growths in fossils, but this object had a clearly defined structure,” Friedman says.

The mystery object displayed several features found in vertebrate brains: It was bilaterally symmetrical, it contained hollow spaces similar in appearance to ventricles, and it had multiple filaments extending toward openings in the braincase, similar in appearance to cranial nerves, which travel through such canals in living species.

“It had all these features, and I said to myself, ‘Is this really a brain that I’m looking at?’” Friedman says. “So I zoomed in on that region of the skull to make a second, higher-resolution scan, and it was very clear that that’s exactly what it had to be. And it was only because this was such an unambiguous example that we decided to take it further.”

Fish evolution

Though preserved brain tissue has rarely been found in vertebrate fossils, scientists have had better success with invertebrates. For example, the intact brain of a 310-million-year-old horseshoe crab was reported in 2021, and scans of amber-encased insects have revealed brains and other organs. There is even evidence of brains and other parts of the nervous system recorded in flattened specimens more than 500 million years old.

The preserved brain of a 300-million-year-old shark relative was reported in 2009. But sharks, rays, and skates are cartilaginous fishes, which today hold relatively few species compared to the ray-finned fish lineage containing Coccocephalus.

Early ray-finned fishes like Coccocephalus can tell scientists about the initial evolutionary phases of today’s most diverse fish group, which includes everything from trout to tuna, seahorses to flounder.

There are roughly 30,000 ray-finned fish species, and they account for about half of all backboned animal species. The other half is split between land vertebrates—birds, mammals, reptiles, and amphibians—and less diverse fish groups like jawless fishes and cartilaginous fishes.

The Coccocephalus skull fossil is on loan to Friedman from England’s Manchester Museum. It was recovered from the roof of the Mountain Fourfoot coal mine in Lancashire and was first scientifically described in 1925. The fossil was found in a layer of soapstone adjacent to a coal seam in the mine.

Though only its skull was recovered, scientists believe that C. wildi would have been 6 to 8 inches long. Judging from its jaw shape and its teeth, it was probably a carnivore, Figueroa says.

When the fish died, scientists suspect it was quickly buried in sediments with little oxygen present. Such environments can slow the decomposition of soft body parts.

In addition, a chemical micro-environment inside the skull’s braincase may have helped to preserve the delicate brain tissues and to replace them with a dense mineral, possibly pyrite, Figueroa says.

Evidence supporting this idea comes from the cranial nerves, which send electrical signals between the brain and the sensory organs. In the Coccocephalus fossil, the cranial nerves are intact inside the braincase but disappear as they exit the skull.

“There seems to be, inside this tightly enclosed void in the skull, a little micro-environment that is conducive to the replacement of those soft parts with some kind of mineral phase, capturing the shape of tissues that would otherwise simply decay away,” Friedman says.

Skull scans

Detailed analysis of the fossil, along with comparisons to the brains of modern-fish specimens from the University of Michigan Museum of Zoology collection, revealed that the brain of Coccocephalus has a raisin-size central body with three main regions that roughly correspond to the forebrain, midbrain, and hindbrain in living fishes.

Cranial nerves project from both sides of the central body. Viewed as a single unit, the central body and the cranial nerves resemble a tiny crustacean, such as a lobster or a crab, with projecting arms, legs and claws.

Notably, the brain structure of Coccocephalus indicates a more complicated pattern of fish-brain evolution than is suggested by living species alone, according to the authors.

“These features give the fossil real value in understanding patterns of brain evolution, rather than simply being a curiosity of unexpected preservation,” Figueroa says.

For example, all living ray-finned fishes have an everted brain, meaning that the brains of embryonic fish develop by folding tissues from the inside of the embryo outward, like a sock turned inside out.

All other vertebrates have evaginated brains, meaning that neural tissue in developing brains folds inward.

“Unlike all living ray-finned fishes, the brain of Coccocephalus folds inward,” Friedman says. “So, this fossil is capturing a time before that signature feature of ray-finned fish brains evolved. This provides us with some constraints on when this trait evolved—something that we did not have a good handle on before the new data on Coccocephalus.”

Comparisons to living fishes showed that the brain of Coccocephalus is most similar to the brains of sturgeons and paddlefish, which are often called “primitive” fishes because they diverged from all other living ray-finned fishes more than 300 million years ago.

Friedman and Figueroa are continuing to CT scan the skulls of ray-finned fish fossils, including several specimens that Figueroa brought to Ann Arbor on loan from institutions in his home country, Brazil. Figueroa says his doctoral dissertation was delayed by the COVID-19 pandemic but is expected to be completed in summer 2024.

Friedman and Figueroa says the discovery highlights the importance of preserving specimens in paleontology and zoology museums.

“Here we’ve found remarkable preservation in a fossil examined several times before by multiple people over the past century,” Friedman says. “But because we have these new tools for looking inside of fossils, it reveals another layer of information to us.

“That’s why holding onto the physical specimens is so important. Because who knows, in 100 years, what people might be able to do with the fossils in our collections now.”

The study includes data produced at University of Michigan’s Computed Tomography in Earth and Environmental Science facility, which is supported by the Department of Earth and Environmental Sciences and the College of Literature, Science, and the Arts.

Sam Giles of London’s Natural History Museum and the University of Birmingham is a senior author of the study. Additional coauthors are from the University of Chicago and the University of Michigan Museum of Paleontology.

Source: University of Michigan

Too much or too little noise in the office can harm our well-being, research finds.

The ideal amount is about 50 decibels, comparable to moderate rain or birdsong.

“Everybody knows that loud noise is stressful, and, in fact, extremely loud noise is harmful to your ear,” says study coauthor Esther Sternberg, director of the University of Arizona Institute on Place, Wellbeing & Performance. “But what was new about this is that with even low levels of sound—less than 50 decibels—the stress response is higher.”

The study’s findings suggest that if employers intend to build or redesign their office spaces with employee health and well-being in mind, they might want to consult acoustical engineers who can help them dial in conditions for good environmental sound, says Sternberg.

The study appears in the journal Nature Digital Medicine. Sudha Ram, professor of management information systems in the Eller College of Management, is the study’s senior author. Karthik Srinivasan, an assistant professor at the University of Kansas, led the research when he was a doctoral student at Eller, and is the paper’s lead author.

“When we think about well-being, typically we think about emotional or mental well-being,” Srinivasan says. “We hardly ever consider the physiological well-being or the actual ‘what’s happening in our body,’ which is also important to understand when we’re continuously exposed to environmental factors such as sound.”

A study Sternberg led in 2018 showed employees who worked in open office seating—at desks that aren’t separated by partitions—had greater daytime activity levels and lower stress levels in the evening, after work hours, compared to workers in private offices and cubicles.

But open office spaces also come with a common complaint from people who work in them: noise. With this latest study, Sternberg and her coauthors shed more light on employees’ physiological reactions to office sound.

The new study was part of Sternberg’s larger research project, called Wellbuilt for Wellbeing, in partnership with the US General Services Administration, the federal agency that oversees basic operations for all nonmilitary federal government buildings, including building and buying real estate, managing buildings’ operating systems, and managing government-wide reentry into the workplace amid the COVID-19 pandemic.

To measure the impact of sound on office workers, researchers asked 231 of the agency’s employees working in four buildings across the US to wear two devices for three days. One device, worn around the neck, measured sound levels in the person’s work environment.

Another, worn on the chest, measured participants’ physiological stress and relaxation levels, using heart rate variability, or the varying lengths of time between each heartbeat. The chest-worn monitors were designed by Aclima, Inc., which also contributed to the study.

Heart rate variability is a direct result of breathing, Sternberg says: As a person inhales, his or her heart rate slightly increases, and it decreases as the person exhales, causing variability between heartbeats.

The more variable the space between heartbeats, the healthier the person is.

“One way to think of it is, the least-variable heart rhythm is a straight line,” Sternberg says, referring to a flatline on an electrocardiogram—a sign someone has died. “You don’t want that—you want a variable heart rate.”

The researchers measured heart rate variability alongside environmental sound, then used mathematical modeling to determine how changing sound levels affect a person’s physiological well-being.

Participants also answered questions sent to their smartphones about how they were feeling at random times throughout the day.

The results show that when a worker’s environmental sound level was above 50 decibels, each 10-decibel increase was related to a 1.9% decrease in physiological well-being. But when office sound was lower than 50 decibels, each 10-decibel increase related to a 5.4% increase in physiological well-being.

Humans’ tendency to get distracted, Sternberg says, is a result of the brain’s stress response to potential threats. Our brains are “difference detectors” that take note of sudden changes in sounds so we can decide to fight or flee, she said.

That may explain why low, steady sounds help mask distractions in the workplace, she adds.

“People are always working in coffee shops—those are not quiet spaces. But the reason you can concentrate there is because the sounds all merge to become background noise,” Sternberg says. “It masks sound that might be distracting. If you hear a pin drop when it’s very, very quiet, it will distract you from what you’re doing.”

The study, Sternberg says, offers precise data that can guide employers in designing office spaces to maximize employee well-being. Acoustical engineers already take great care in choosing or designing furniture, flooring, wall coverings, and other aspects of spaces such as concert halls, recording studios, and museums.

If employee health is a priority, Sternberg says, “There’s no reason why these simple interventions can’t be installed in office spaces to mitigate sound distraction.”

Source: University of Arizona, Jon Niccum for University of Kansas

A new wearable sensor is so cheap and simple to produce it can be hand-drawn with a pencil onto paper treated with sodium chloride.

The sensor could clear the way for wearable, self-powered monitors to predict major health concerns like cardiac arrest and pneumonia. And it could even let you know when your baby’s diaper needs a change.

“Our team has been focused on developing devices that can capture vital information for human health,” says Huanyu “Larry” Cheng, associate professor of engineering science and mechanics at Penn State and lead author of the study in the journal Nano Letters. “The goal is early prediction for disease conditions and health situations, to spot problems before it is too late.”

The paper describes the design and fabrication process for a reliable, hand-drawn electrode sensor created using a pencil, drawn on paper treated with a sodium chloride solution. The hydration sensor is highly sensitive to changes in humidity and provides accurate readings over a wide range of relative humidity levels, from 5.6% to 90%.

Simple and quick sensor

Research into wearable sensors has been gaining momentum because of their wide-ranging applications in medical health, disaster warning, and military defense, Cheng explains.

Flexible humidity sensors have become increasingly necessary in health care, for uses such as respiratory monitoring and skin humidity detection, but it is still challenging to achieve high sensitivity and easy disposal with simple, low-cost fabrication processes, he adds.

“We wanted to develop something low-cost that people would understand how to make and use—and you can’t get more accessible than pencil and paper,” says Li Yang, professor in the School of Artificial Intelligence at Hebei University of Technology in China.

“You don’t need to have some piece of multi-million-dollar equipment for fabrication. You just need to be able to draw within the lines of a pre-drawn electrode on a treated piece of paper. It can be done simply and quickly.”

The device takes advantage of the way paper naturally reacts to changes in humidity and uses the graphite in the pencil to interact with water molecules and the sodium chloride solution. As water molecules are absorbed by the paper, the solution becomes ionized and electrons begin to flow to the graphite in the pencil, setting off the sensor, which detects those changes in humidity in the environment and sends a signal to a smartphone, which displays and records the data.

Essentially, drawing on the pre-treated paper within pre-treated lines creates a miniaturized paper circuit board. The paper can be connected to a computer with copper wires and conductive silver paste to act as an environmental humidity detector.

Smart diapers and masks

For wireless application, such as “smart diapers” and mask-based respiration monitoring, the drawing is connected to a tiny lithium battery which powers data transmission to a smartphone via Bluetooth.

For the respiration monitor, the team drew the electrode directly on a solution-treated face mask. The sensor easily differentiated mouth breathing from nose breathing and was able to classify three breathing states: deep, regular, and rapid.

Cheng explains that the data collected could be used to detect the onset of various disease conditions, such as respiratory arrest and shortness of breath and provide opportunities in the smart internet of things and telemedicine.

He adds that respiratory rate is a fundamental vital sign and research has shown it to be an early indicator of a variety of pathological conditions such as cardiac events, pneumonia, and clinical deterioration. It can also indicate emotional stressors like cognitive load, heat, cold, physical effort, and exercise-induced fatigue.

Compared with breath, the human skin exhibits a smaller change in humidity, but the researchers were still able to detect changes using their pencil-on-paper humidity sensor, even after test subjects applied lotion or exercised. Skin is the body’s largest organ, Cheng says, so if it is not processing moisture correctly, that could indicate that some other health issue is going on.

“Different types of disease conditions result in different rates of water loss on our skin,” he says. “The skin will function differently based on those underlying conditions, which we will be able to flag and possibly characterize using the sensor.”

How wet is wet?

The team also integrated four humidity sensors between the absorbent layers of a diaper to create a “smart diaper,” capable of detecting wetness and alerting for a change.

“That application was actually born out of personal experience,” says Cheng, who is the father of two young children. “There’s no easy way to know how wet is wet, and that information could be really valuable for parents. The sensor can provide data in the short-term, to alert for diaper changes, but also in the long-term, to show patterns that can inform parents about the overall health of their child.”

The applications of the humidity sensor go beyond “smart diapers” and monitoring for respiration and perspiration, Cheng explains. The team also deployed the sensor as a noncontact switch, which could sense the humidity changes in the air from the presence of a finger without the finger touching the sensor. The team used the noncontact switch to operate a small-scale elevator, play a keyboard and light up an LED array.

“The atoms on the finger don’t need to touch the button, they only need to be near the surface to diffuse the water molecules and trigger the signal,” Cheng says. “When we think about what we learned from the pandemic about the need to limit the body’s contact with shared surfaces, a sensor like this could be an important tool to stop potential contamination.”

Additional coauthors are from Hebei University of Technology, Tianjin Tianzhong Yimai Technology Development Co. Ltd., and Penn State.

The National Institutes of Health, the National Science Foundation, and Penn State funded the work.

Source: Penn State

A new study identifies a link between sleep problems and suicidal thoughts, as well as behaviors that may help reduce suicide risk in young adults.

In 2020, the Centers for Disease Control and Prevention reported suicide was the second leading cause of death among people ages 10-14 and 25-34, accounting for more than 9,000 deaths. Suicide also was the third leading cause of death among people ages 15-24, accounting for more than 6,000 deaths.

“Suicide is a difficult problem because it emerges from complex interactions between many, many different factors. Disrupted sleep is one such factor,” says Andrew Tubbs, a medical student researcher in the University of Arizona psychiatry department’s Sleep and Health Research Program.

“Our research shows poor sleep is linked with suicidal ideation, attempts, and deaths among college students. However, unlike other suicide risk factors, poor sleep isn’t permanent. If students can sleep better, maybe we can reduce suicide risk.”

The study evaluated suicidal thoughts and behaviors in college students during the early days of the COVID-19 pandemic, from May 2020 to May 2021. Of the 885 undergraduate students who participated in the study, 41% thought about suicide in their lifetime, with half experiencing suicidal ideation in the last three months.

Eleven percent of students reported a suicide attempt during their lifetime, with 16% of those attempts taking place in the last three months.

The researchers then compared individuals with and without suicidal ideation or prior suicide attempts on multiple measures of sleep including sleep duration, timing, insomnia, nightmares, sleep control, and depressive symptoms.

“The main differences between those with suicidal thoughts and behaviors and those without included sleep time, efficiency, quality, perceived sleep control, clinical insomnia, and clinical nightmares,” says the study’s senior author Michael Grandner, associate professor of psychiatry, director of the Behavioral Sleep Medicine Clinic, and member of the BIO5 Institute. “These findings highlight how multiple sleep deficits may contribute to suicide risk in this population.”

Taking steps to improve sleep health could help reduce suicide risk, Grandner says.

Research shows that collegiate sleep is particularly affected by problematic nighttime use of technology and the misguided use of cannabis to improve sleep. He recommends avoiding using digital devices for at least one hour before going to bed and not consuming cannabis as a sleep aid.

“There are also evidence-based interventions that campus health centers can implement, including cognitive behavioral therapy for insomnia or imagery rehearsal therapy for nightmares,” Grandner says.

“Both have demonstrated efficacy in collegiate populations, and considering the effect of poor sleep on academic performance, these are interventions worth applying.”

“The simplest thing to sleep better is to be consistent,” Tubbs says. “Go to bed and wake up at the same time every day so your body learns to expect sleep at the same time. Even if you go to bed late or wake up in the middle of the night, stick to your schedule because you’ll have an easier time going to sleep the next night.”

The study appears in the Journal of American College Health.

Source: Jamie Manser for University of Arizona

New research digs into how sound waves trigger immune responses to cancer in mice.

By breaking down the cell wall “cloak,” the treatment exposes cancer cell markers that had previously been hidden from the body’s defenses, the researchers report.

The technique, known as histotripsy, offers a two-prong approach to attacking cancers: the physical destruction of tumors via sound waves and the kickstarting of the body’s immune response. It could potentially offer medical professionals a treatment option for patients without the harmful side effects of radiation and chemotherapy.

Until now, researchers didn’t understand how histotripsy was activating the immune system. A study from last spring showed that histotripsy breaks down liver tumors in rats, leading to the complete disappearance of the tumor even when sound waves are applied to only 50% to 75% of the mass. The immune response also prevented further spread, with no evidence of recurrence or metastases in more than 80% of the animals.

“We found that histotripsy somehow not only kills cancer cells, but causes them to undergo a unique pathway of cell death that draws the attention of the immune system,” says Clifford Cho, professor of surgery and vice chair of surgery at the University of Michigan.

Cho’s lab designed immune study protocols and measured immune responses for the study published in Frontiers in Immunology.

The key turned out to be tumor antigens—proteins only found in cancer cells and hidden behind their cell walls. When cells die by chemotherapy or radiation, these antigens are destroyed in the process. In contrast, sound waves kill the cancer cells by breaking their cell walls, releasing tumor antigens that then trigger the body’s defense systems.

The immune response occurred throughout the body, not simply in the area where the histotripsy was applied.

“With histotripsy, we’re not destroying the antigens, we’re releasing them while killing the tumor cells,” says Zhen Xu, professor of biomedical engineering and an inventor of the histotripsy approach. “Once they’re no longer hidden, the body can see them and attack them.”

The team was able to discover the mechanism due to the way mice in cancer studies are typically given genetically identical tumors. After breaking up a tumor in one mouse using histotripsy, the team extracted some of that material, homogenized it, and injected it into another mouse. Both mice developed immune protection from that cancer.

“Injecting the debris into a second mouse had almost a vaccine-like property,” Xu says. “Mice that received this debris were surprisingly resistant to the growth of cancers.”

Since 2001, Xu’s laboratory has pioneered the use of histotripsy in the fight against cancer, leading to the multi-center clinical trial #HOPE4LIVER sponsored by HistoSonics, a University of Michigan spinoff company. More recently, the group’s research has produced promising results on histotripsy treatment of brain cancer therapy and immunotherapy.

The VA Merit Review, the National Institutes of Health, the Forbes Institute for Discovery, Histosonics-Michigan, and Michigan Medicine-Peking Health Sciences University Joint Institute for Clinical and Translational Research supported the work.

Source: University of Michigan

The majority of stock photos related to health topics show light-skinned people in a fairly narrow age range, research finds.

This makes it more difficult—and expensive—for organizations to create health education materials aimed at reaching other groups.

Using images relevant to audiences is an important factor in successful communication and outreach efforts. If stock photography sites don’t represent many populations well, it’s more difficult to develop effective communication tools to reach those populations.

“Many organizations that produce health outreach materials rely on stock photography sites to produce those materials,” says Michelle Jewell, coauthor of the study and a science communicator in the department of applied ecology at North Carolina State University. “In many cases, organizations that create outreach materials for minoritized groups or populations with lower socioeconomic status have limited resources, which exacerbates the challenges they face in producing effective materials that reflect the publics they serve.”

The researchers also found a significant difference between the diversity present on images available on free stock photography sites versus on sites that require users to pay for stock photos.

“Images on stock photo sites with paywalls were significantly more likely to depict a person of perceived minoritized racial/ethnic identity and darker skin tones,” says Catherine LePrevost, coauthor of the study and an associate extension professor of applied ecology at NC State. “The pay sites were also less likely to contain markers of high socioeconomic status than images in databases that were free to use.”

“In other words, it is harder to find health-relevant photos of people who are not light-skinned and upper class,” Jewell says. “And when you do find them, they are more likely to come with a fee.”

The researchers launched the study after they struggled to find a stock image of a Latina pregnant woman for an unrelated science communication effort.

“Anecdotally, this lack of representation in stock photography is a widely known problem among professional communicators,” Jewell says. “We wanted to quantify the problem to get a better understanding of the scope of the problem.”

For the study, the researchers focused on five widely used stock image libraries, and searched each of those sites for five health-related terms: healthy eating, exercising, quitting smoking, vaccination, and pregnancy.

While about half of the images the researchers found included at least one person from a perceived minoritized group, there were stark differences when researchers accounted for skin tone.

For some search terms—healthy diet and quitting smoking—there were no images of people with dark skin tones at all. Only one search term—vaccination – included dark skin tones in 20% of its images.

“It became glaringly evident while searching through the stock photo libraries that certain populations are underrepresented,” says Zachary Chichester, first author of the study and an undergraduate at East Carolina University at the time of the study. “It is imperative that we bring attention to this issue in order to ensure that creators of health education media are able to produce materials that are most effective.”

Another factor was whether the stock photos showed a person’s face.

“If you were looking for photos that included someone’s face, which is important for humanizing the subject matter, things became even more difficult,” LePrevost says. “Basically, if an image included a person’s face, it was much less likely to be someone who could be recognized as being part of a minoritized racial or ethnic group.”

Age presented another challenge, with the researchers finding very few images that included older adults of any racial or ethnic group.

And these disparities became more pronounced when looking only at free stock photo sites and images.

“Effective health communication is incredibly important, and our study outlines a systemic obstacle to developing health communication tools for many groups,” LePrevost says. “Communication is an important component in addressing health disparities, and this work highlights one of the challenges facing those communication efforts.”

“We also hope this work will help health communicators secure the time and financial resources they need in order to develop effective outreach tools,” Jewell says. “Organizations that support health communication and education efforts need to recognize that communicators don’t have access to free images that are relevant to many audiences. Moving forward, granting bodies and other revenue sources should include budgets for photographers and illustrators to create media that best represents relevant audiences.”

The paper appears in the journal Health Promotion Practice.

The work had support from the National Library of Medicine of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Source: NC State