Science

bats-use-echolocation-to-make-mental-maps-for-navigation

Bats use echolocation to make mental maps for navigation

Bat maps

To evaluate the route each bat took to get back to the roost, the team used their simulations to measure the echoic entropy it experienced along the way. The field where the bats were released was a low echoic entropy area, so during those first few minutes when they were flying around they were likely just looking for some more distinct, higher entropy landmarks to figure out where they were. Once they were oriented, they started flying to the roost, but not in a straight line. They meandered a bit, and the groups with higher sensory deprivation tended to meander more.

The meandering, researchers suspect, was due to trouble the bats had with maintaining the steady path relying on echolocation alone. When they were detecting distinctive landmarks like a specific orchard, they corrected the course. Repeating the process eventually brought them to their roost.

But could this be landmark-based navigation? Or perhaps simple beaconing, where an animal locks onto something like a distant light and moves toward it?

The researchers argue in favor of cognitive acoustic maps. “I think if echolocation wasn’t such a limited sensory modality, we couldn’t reach a conclusion about the bats using cognitive acoustic maps,” Goldshtein says. The distance between landmarks the bats used to correct their flight path was significantly longer than echolocation’s sensing range. Yet they knew which direction the roost was relative to one landmark, even when the next landmark on the way was acoustically invisible. You can’t do that without having the area mapped.

“It would be really interesting to understand how other bats do that, to compare between species,” Goldshtein says. There are bats that fly over a thousand meters above the ground, so they simply can’t sense any landmarks using echolocation. Other species hunt over sea, which, as per this team’s simulations, would be just one huge low-entropy area. “We are just starting. That’s why I do not study only navigation but also housing, foraging, and other aspects of their behavior. I think we still don’t know enough about bats in general,” Goldshtein claims.

Science, 2024.  DOI: 10.1126/science.adn6269

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AIs show distinct bias against Black and female résumés in new study

Anyone familiar with HR practices probably knows of the decades of studies showing that résumé with Black- and/or female-presenting names at the top get fewer callbacks and interviews than those with white- and/or male-presenting names—even if the rest of the résumé is identical. A new study shows those same kinds of biases also show up when large language models are used to evaluate résumés instead of humans.

In a new paper published during last month’s AAAI/ACM Conference on AI, Ethics and Society, two University of Washington researchers ran hundreds of publicly available résumés and job descriptions through three different Massive Text Embedding (MTE) models. These models—based on the Mistal-7B LLM—had each been fine-tuned with slightly different sets of data to improve on the base LLM’s abilities in “representational tasks including document retrieval, classification, and clustering,” according to the researchers, and had achieved “state-of-the-art performance” in the MTEB benchmark.

Rather than asking for precise term matches from the job description or evaluating via a prompt (e.g., “does this résumé fit the job description?”), the researchers used the MTEs to generate embedded relevance scores for each résumé and job description pairing. To measure potential bias, the résuméwere first run through the MTEs without any names (to check for reliability) and were then run again with various names that achieved high racial and gender “distinctiveness scores” based on their actual use across groups in the general population. The top 10 percent of résumés that the MTEs judged as most similar for each job description were then analyzed to see if the names for any race or gender groups were chosen at higher or lower rates than expected.

A consistent pattern

Across more than three million résumé and job description comparisons, some pretty clear biases appeared. In all three MTE models, white names were preferred in a full 85.1 percent of the conducted tests, compared to Black names being preferred in just 8.6 percent (the remainder showed score differences close enough to zero to be judged insignificant). When it came to gendered names, the male name was preferred in 51.9 percent of tests, compared to 11.1 percent where the female name was preferred. The results could be even clearer in “intersectional” comparisons involving both race and gender; Black male names were preferred to white male names in “0% of bias tests,” the researchers wrote.

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RFK Jr. claims Trump promised to put him in charge of NIH, CDC, and more

Earlier this week, Robert F. Kennedy, Jr. used a Zoom call to tell his supporters that Donald Trump had promised him “control” of the Department of Health and Human Services (HHS), the federal agency that includes the Centers for Disease Control, Food and Drug Administration, National Institutes of Health, as well as the Department of Agriculture. Given Kennedy’s support for debunked anti-vaccine nonsense, this represents a potential public health nightmare.

A few days after, Howard Lutnick, a co-chair of Trump’s transition team, appeared on CNN to deny that RFK Jr. would be put in charge of HHS. But he followed that with a long rant in which he echoed Kennedy’s spurious claims about vaccines. This provides yet another indication of how anti-vaccine activism has become deeply enmeshed with Republican politics, to the point where it may be just as bad even if Kennedy isn’t appointed.

Trump as Kennedy’s route to power

Kennedy has a long history of misinformation regarding health, with a special focus on vaccines. This includes the extensively debunked suggestion that there is a correlation between vaccinations and autism incidence, and it extends to a general skepticism about vaccine safety. That’s mixed with conspiracy theories regarding collusion between federal regulators and pharmaceutical companies.

While there is no evidence for any of this, and some of it is clearly wrong, the conspiracies have real-world consequences. An anti-vaccine activist in Samoa, aided by a visit from RFK Jr., helped pave the way for a measles outbreak that shut down the government and ultimately led to over 80 deaths.

Kennedy has long been interested in getting access to the agencies that regulate vaccines and other interests of his, such as food safety, under the assumption they are hiding the data that would vindicate his views. And, long before his recent presidential run, he viewed Trump as the route to that access. Shortly before Trump’s inauguration in 2017, Kennedy claimed that he would be appointed to head a vaccine safety commission that Trump would supposedly create once in office. Nothing ever came of that, and it was never clear whether that was due to Trump lying to him, Kennedy exaggerating his significance, or Trump simply telling him what he wanted to hear at the time and never following up.

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Idaho health district abandons COVID shots amid flood of anti-vaccine nonsense

Slippery slope

In the hearing, board member Jennifer Riebe (who voted to keep COVID-19 vaccinations available) worried about the potential of a slippery slope.

“My concern with this is the process because if this board and six county commissioners and one physician is going to make determinations on every single vaccine and pharmaceutical that we administer, I’m not comfortable with that,” she said, according to Boise State Public Radio. “It may be COVID now, maybe we’ll go down the same road with the measles vaccine or the shingles vaccine coverage.”

Board Chair Kelly Aberasturi, who also voted to keep the vaccines, argued that it should be a choice by individuals and their doctors, who sometimes refer their patients to the district for COVID shots. “So now, you’re telling me that I have the right to override that doctor? Because I know more than he does?” Aberasturi said.

“It has to do with the right of the individual to make that decision on their own. Not for me to dictate to them what they will do. Sorry, but this pisses me off,” he added.

According to Boise State Public Radio, the district had already received 50 COVID-19 vaccines at the time of the vote, which were slated to go to residents of a skilled nursing facility.

The situation in the southwest district may not be surprising given the state’s overall standing on vaccination: Idaho has the lowest kindergarten vaccination rates in the country, with coverage of key vaccinations sitting at around 79 percent to 80 percent, according to a recent analysis by the Centers for Disease Control and Prevention. The coverage is far lower than the 95 percent target set by health experts. That’s the level that would block vaccine-preventable diseases from readily spreading through a population. The target is out of reach for Idaho as a whole, which also has the highest vaccination exemption rate in the country, at 14.3 percent. Even if the state managed to vaccinate all non-exempt children, the coverage rate would only reach 85.7 percent, missing the 95 percent target by nearly 10 percentage points.

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slivered-onions-are-likely-cause-of-mcdonald’s-e.-coli-outbreak,-cdc-says

Slivered onions are likely cause of McDonald’s E. coli outbreak, CDC says

Slivered onions are the likely source of the multi-state E. coli outbreak linked to McDonald’s Quarter Pounder burgers that continues to grow, the Centers for Disease Control and Prevention announced Wednesday.

Onions were one of two primary suspects when the CDC announced the outbreak on October 22, with the other being the beef patties used on the burgers. But onions quickly became the leading suspect. The day after the CDC’s announcement, McDonald’s onion supplier, Taylor Farms, recalled peeled and diced yellow onion products and several other fast food chains took onions off the menu as a precaution. (No other restaurants have been linked to the outbreak to date.)

According to the CDC, traceback information and epidemiological data collected since then have all pointed to the onions and, according to McDonald’s, state and federal testing of the beef patties has all come back negative.

In the CDC’s update Wednesday, the agency reported that 15 more people were identified as sickened in the outbreak, including five who were hospitalized. In all, that brings the outbreak to 90 cases, including 27 hospitalizations and one death, which collectively span 13 states.

All the newly reported illnesses had onsets prior to the October 23 onion recall. The most recent illness onset was October 16. Additional illnesses may be reported, as it can take three to four weeks to link illnesses to an outbreak.

“Due to the product actions taken by McDonald’s and Taylor Farms, the CDC believes the continued risk to the public is very low,” the agency said in a media alert.

McDonald’s says that Quarter Pounders—without onions—will return to the menus of affected restaurants this week. Prior to the recall, 900 restaurants had received onions from Taylor Farms, including in Colorado, Kansas, and Wyoming, as well as portions of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico, Oklahoma, and Utah.

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Person accidentally poisoned 46 coworkers with toxin-loaded homemade lunch

For some, microwaving fish in the employee lunch room is the ultimate work faux pas. But for one (likely mortified) employee of a seafood distribution plant in Maryland, it’s probably causing a mass poisoning with the homemade noodle dish they brought to share for lunch. The dish sickened 46 employees, spurring their employer to hastily release a statement assuring customers that it wasn’t the company’s food that caused the illnesses.

On October 21, first responders and paramedics arrived at the NAFCO Wholesale Fish Distribution Facility in Jessup, where dozens of employees had abruptly fallen ill about three hours after lunch. Helicopter footage of the event captured images of workers around picnic tables outside the plant, some doubled over and with their heads down.

Ultimately, 46 people were sickened, and at least 26 were treated at an area hospital with symptoms of food poisoning, according to The Baltimore Banner. They all recovered.

“NAFCO maintains the highest standards of food safety and regularly undergoes rigorous inspections by health authorities,” NAFCO said in a written statement. “Its products continue to be safely produced and consumed by customers nationwide, and there are no issues related to its supply chain.”

Enterotoxins

In an update on Tuesday, the Maryland Department of Health announced that testing found that Staphylococcus aureus was the cause of the illnesses. S. aureus is often thought of as a skin bacterium, but the pathogen can spread to food from unwashed hands, the Centers for Disease Control and Prevention notes. In food that isn’t thoroughly cooked or is held at warm temperatures (between 40° F and 140° F) conducive to bacterial growth, the germ can grow and produce toxins.

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These hornets break down alcohol so fast that they can’t get drunk

Many animals, including humans, have developed a taste for alcohol in some form, but excessive consumption often leads to adverse health effects. One exception is the Oriental wasp. According to a new paper published in the Proceedings of the National Academy of Sciences, these wasps can guzzle seemingly unlimited amounts of ethanol regularly and at very high concentrations with no ill effects—not even intoxication. They pretty much drank honeybees used in the same experiments under the table.

“To the best of our knowledge, Oriental hornets are the only animal in nature adapted to consuming alcohol as a metabolic fuel,” said co-author Eran Levin of Tel Aviv University. “They show no signs of intoxication or illness, even after chronically consuming huge amounts of alcohol, and they eliminate it from their bodies very quickly.”

Per Levin et al., there’s a “drunken monkey” theory that predicts that certain animals well-adapted to low concentrations of ethanol in their diets nonetheless have adverse reactions at higher concentrations. Studies have shown that tree shrews, for example, can handle concentrations of up to 3.8 percent, but in laboratory conditions, when they consumed ethanol in concentrations of 10 percent or higher, they were prone to liver damage.

Similarly, fruit flies are fine with concentrations up to 4 percent but have increased mortality rates above that range. They’re certainly capable of drinking more: fruit flies can imbibe half their body volume in 15 percent (30 proof) alcohol each day. Not even spiking the ethanol with bitter quinine slows them down. Granted, they have ultra-fast metabolisms—the better to burn off the booze—but they can still become falling-down drunk. And fruit flies vary in their tolerance for alcohol depending on their genetic makeup—that is, how quickly their bodies adapt to the ethanol, requiring them to inhale more and more of it to achieve the same physical effects, much like humans.

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“Impact printing” is a cement-free alternative to 3D-printed structures

Recently, construction company ICON announced that it is close to completing the world’s largest 3D-printed neighborhood in Georgetown, Texas. This isn’t the only 3D-printed housing project. Hundreds of 3D-printed homes are under construction in the US and Europe, and more such housing projects are in the pipeline.

There are many factors fueling the growth of 3D printing in the construction industry. It reduces the construction time; a home that could take months to build can be constructed within days or weeks with a 3D printer. Compared to traditional methods, 3D printing also reduces the amount of material that ends up as waste during construction. These advantages lead to reduced labor and material costs, making 3D printing an attractive choice for construction companies.

A team of researchers from the Swiss Federal Institute of Technology (ETH) Zurich, however, claims to have developed a robotic construction method that is even better than 3D printing. They call it impact printing, and instead of typical construction materials, it uses Earth-based materials such as sand, silt, clay, and gravel to make homes. According to the researchers, impact printing is less carbon-intensive and much more sustainable and affordable than 3D printing.

This is because Earth-based materials are abundant, recyclable, available at low costs, and can even be excavated at the construction site. “We developed a robotic tool and a method that could take common material, which is the excavated material on construction sites, and turn it back into usable building products, at low cost and efficiently, with significantly less CO2 than existing industrialized building methods, including 3D printing,” said Lauren Vasey, one of the researchers and an SNSF Bridge Fellow at ETH Zurich.

How does impact printing work?

Excavated materials can’t be used directly for construction. So before beginning the impact printing process, researchers prepare a mix of Earth-based materials that has a balance of fine and coarse particles, ensuring both ease of use and structural strength. Fine materials like clay act as a binder, helping the particles stick together, while coarser materials like sand or gravel make the mix more stable and strong. This optimized mix is designed such that it can move easily through the robotic system without getting stuck or causing blockages.

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A candy engineer explains the science behind the Snickers bar

It’s Halloween. You’ve just finished trick-or-treating and it’s time to assess the haul. You likely have a favorite, whether it’s chocolate bars, peanut butter cups, those gummy clusters with Nerds on them, or something else.

For some people, including me, one piece stands out—the Snickers bar, especially if it’s full-size. The combination of nougat, caramel, and peanuts coated in milk chocolate makes Snickers a popular candy treat.

As a food engineer studying candy and ice cream at the University of Wisconsin-Madison, I now look at candy in a whole different way than I did as a kid. Back then, it was all about shoveling it in as fast as I could.

Now, as a scientist who has made a career studying and writing books about confections, I have a very different take on candy. I have no trouble sacrificing a piece for the microscope or the texture analyzer to better understand how all the components add up. I don’t work for, own stock in, or receive funding from Mars Wrigley, the company that makes Snickers bars. But in my work, I do study the different components that make up lots of popular candy bars. Snickers has many of the most common elements you’ll find in your Halloween candy.

Let’s look at the elements of a Snickers bar as an example of candy science. As with almost everything, once you get into it, each component is more complex than you might think.

Snickers bars contain a layer of nougat, a layer of caramel mixed with peanuts, and a chocolate coating.

Credit: istarif/iStock via Getty Images

Snickers bars contain a layer of nougat, a layer of caramel mixed with peanuts, and a chocolate coating. Credit: istarif/iStock via Getty Images

Airy nougat

Let’s start with the nougat. The nougat in a Snickers bar is a slightly aerated candy with small sugar crystals distributed throughout.

One of the ingredients in the nougat is egg white, a protein that helps stabilize the air bubbles that provide a light texture. Often, nougats like this are made by whipping sugar and egg whites together. The egg whites coat the air bubbles created during whipping, which gives the nougat its aerated texture.

A boiled sugar syrup is then slowly mixed into the egg white sugar mixture, after which a melted fat is added. Since fat can cause air bubbles to collapse, this step has to be done last and very carefully.

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How can you write data to DNA without changing the base sequence?

The developers of the system call each of these potentially modifiable spots on the template an epi-bit, with the modified version corresponding to a 1 in a conventional computer bit and the unmodified version corresponding to a 0. Because no synthesis is required, multiple bits can be written simultaneously. To read the information, the scientists rigged the system so that 1s fluoresce and 0s don’t. The fluorescence, along with the sequences of bases, was read as the DNA was passed through a tiny pore.

Pictures in a meta-genome

Using this system, Zhang et al. created five DNA templates and 175 bricks to record 350 bits at a time. Using a collection of tagged template molecules, the researchers could store and read roughly 275,000 bits, including a color picture of a panda’s face and a rubbing of a tiger from the Han dynasty, which ruled China from 202 BCE to 220 CE.

They then had 60 student volunteers “with diverse academic backgrounds” store texts of their choice in epi-bits using a simple kit in a classroom. Twelve of the 15 stored texts were read successfully.

We’re not quite ready for your cat videos yet, though. There are still errors in the printing and reading steps, and since these modifications don’t survive when DNA is copied, making additional versions of the stored information may get complicated. Plus, the stability of these modifications under different storage conditions remains unknown, although the authors note that their epi-bits stayed stable at temperatures of up to 95o° C.

But once these and a few other problems are solved—and the technology is scaled up, further optimized and automated, and/or tweaked to accommodate other types of epigenetic modifications—it will be a clever and novel way to harness natural data storage methods for our needs.

Nature, 2024.  DOI: 10.1038/s41586-024-08040-5

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Lidar mapping reveals mountainous medieval cities along the Silk Road

The city of Tugunbulak, which stretched beyond the forest inspector’s house, had powerful walls enclosing the area of 120 hectares, nearly five times larger than the Tashbulak site. With those walls, there was a dense architecture with hundreds of buildings, streets, palaces, plazas—even industrial facilities the Frachetti’s team suspects were used to produce iron or steel.

To put that in perspective, the medieval walls of Siena, one of the foremost cities in Italy during that time, surrounded an area of 105 hectares at the peak of its power. Genoa, another crown jewel among Italian medieval cities, between the 6th and 11th centuries, had walls protecting just 20 hectares, an area bumped up to around 50 hectares by the time of Frederic Barbarossa’s invasion between 1155 and 1158 CE.

Tugunbulak was a monster of a city. But what did it look like?

A city of iron?

“If you looked at Tugunbulak from the outside you would have seen these kind of rocky walls. They appear to have been made in a technology called rammed earth. The builders would take mud and press it into something almost like cement—a very high labor, very dense, very defensive and fortified material,” Frachetti says. Rammed earth was a dominant building technique used in the early stages of Tugunbulak’s development. “The later phase in the site, we see some stone architecture foundations with mud brick on the top. They used local resources and building techniques that were popular in the region,” Frachetti explains.

According to the team, the main contribution of the city to the Silk Road trade was iron, as the surrounding mountains are particularly rich in iron ore. One of the still unanswered questions was about the way Tugunbulak’s people lived and worked. Were they skillful blacksmiths forging iron and perhaps even steel in their mountainous city? Did at least some of its inhabitants live the lives of nomads, visiting the city only periodically to trade on market days or did they live there permanently?  “We’d like to know how extensive was the industry there—what level of production were they actually doing?” Franchetti says. He suggested that a shifting, seasonal population that most likely lived in yurts spread outside of the walls was more likely in the smaller Tashbulak, considering it lacked residential suburbs. “Tugunbulak must have been a far more organized political entity. Their power and their influence must have been significant in the broader economy of the Silk Road,” Frachetti claims.

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NASA’s oldest active astronaut is also one of the most curious humans

For his most recent trip to the International Space Station, in lieu of bringing coffee or some other beverage in his “personal drink bag” allotment for the stay, NASA astronaut Don Pettit asked instead for a couple of bags of unflavored gelatin.

This was not for cooking purposes but rather to perform scientific experiments. How many of us would give up coffee for science?

Well, Donald Roy Pettit is not like most of us.

At the age of 69, Pettit is NASA’s oldest active astronaut and began his third long-duration stay on the space station last month. A lifelong tinkerer and gifted science communicator, he already is performing wonders up there, and we’ll get to his current activities in a moment. But just so you understand who we’re dealing with, the thing to know about Pettit is that he is insatiably curious, and wants to share the wonder of science and the natural world with others.

Here’s just one small example. During his last six-month increment in orbit, from late 2011 to the middle of 2012, Pettit had some Lego blocks he’d been using for student demonstrations. After the final one, he asked if he could use the Legos for a science experiment. He turned them into a belts-and-rollers-type Van de Graaff generator and produced groundbreaking work in electric fluids. This research was published in Physical Review Letters after Pettit returned to Earth. Most of us probably could not even spell Van de Graaff generator, and this dude is up there, in space, building them out of toys.

The way Pettit, a chemical engineer by training, explains things is that he has the “programmatic” scientific research he does for NASA, and then there’s everything else, often done during his limited free time.

“This is well-planned, well thought out, peer-reviewed, and uplinked to station with the supplies needed,” he said of programmatic research. “And then you have what I call science of opportunity. This is science which comes to mind while you are there, simply because you are there, and you can do it because you can. The scientific disciplines that I’ve dabbled in on the International Space Station include fluid physics, classic physics, chemistry, biology, plant growth, and Earth observations.”

Wafers of water ice. Credit: Don Pettit/NASA

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