'Tis the season for many holiday traditions, including the Ugly Christmas Sweater—you know, those 1950s-style heavy knits featuring some kind of cartoonish seasonal decoration, like snowflakes, Santa Claus, or—in the case of Mark Darcy from Bridget Jones' Diary (2001)—Rudolph the Red-Nosed Reindeer. "It’s obnoxious and tacky, but also fuzzy and kind of wholesome—the fashion equivalent of a Hallmark Christmas movie (with a healthy dose of tongue-in-cheek)," as CNN's Marianna Cerini recently observed.

Fashion (or lack thereof) aside, sweaters and other knitted fabric are also fascinating to physicists and mathematicians. Case in point: a recent paper published in the journal Physical Review Letters examining the complex mechanics behind the many resting shapes a good Jersey knit can form while at rest.

Knitted fabrics are part of a class of intertwined materials—which also includes birds' nests, surgical knots, knotted shoelaces, and even the degradation of paper fibers in ancient manuscripts. Knitted fabrics are technically a type of metamaterial: an engineered material that gets its properties not from the base materials but from their designed structures. The elasticity (aka, stretchiness) of knitted fabrics is an emergent property: the whole is more than the sum of its parts. How those components (strands of yarn) are arranged at an intermediate scale (the structure) determines the macro scale properties of the resulting fabric.

Read full article

Comments

There are thousands of YouTube videos in which DIY science enthusiasts cut grapes in half—leaving just a thin bit of skin connecting them—and put the grapes in the microwave, just to marvel at the sparks and plume of ionized gas (plasma) that the grapes produce. This quirky property of grapes might help make more efficient quantum sensors, according to a new paper published in the journal Physical Review Applied.

The plasma-inducing grape effect was first observed in 1994, per the authors. As previously reported, the usual explanation for the generation of plasmas is that grapes are so small that the irradiating microwaves become highly concentrated in the grape tissue, ripping some the molecules apart to generate charged ions (adding to the electrolytes already present in the grapes). The electromagnetic field that forms causes ions to flow from one grape half to the other via the connecting skin—at least at first. That's when you get the initial sparks. Eventually, the ions start passing through the surrounding air as well, ionizing it to produce that hot plume of plasma.

But in 2019, Trent University scientists showed that explanation isn't quite right. The skin bridge isn't necessary for the effect to occur. Rather, the plasma is generated by an electromagnetic "hot spot." The grapes have the right refractive index and size to "trap" microwaves, so putting two of them close together leads to the generation of a hot spot between them. The trick also works with gooseberries, large blackberries, and quail eggs, as well as hydrogel beads—plastic beads soaked in water. ("Many microwaves were in fact harmed during the experiments," co-author Hamza Khattak admitted at the time.)

Read full article

Comments

We think of squirrels as adorably harmless creatures, admiring their bushy tails and twitchy little noses and the way they cram their cheeks with nuts or seeds to bring back to their nests for later. But the rodents turn out to be a bit more bloodthirsty than we thought. According to a new paper published in the Journal of Ethology, California ground squirrels have been caught in the act—many times over—of chasing, killing, and eating voles.

Co-author Jennifer Smith, a biologist at the University of Wisconsin, Eau Claire, described the behavior as "shocking," given the sheer number of times they watched squirrels do this. “We had never seen this behavior before," she said. "Squirrels are one of the most familiar animals to people. We see them right outside our windows; we interact with them regularly. Yet here’s this never-before-encountered-in-science behavior that sheds light on the fact that there’s so much more to learn about the natural history of the world around us.”

Squirrels mainly consume acorns, seeds, nuts, and fruits, but they have been known to supplement that diet with insects and, occasionally, by stealing eggs or young hatchlings from nests. And back in 1993, biologist J.R Callahan caused a stir by reporting that as many as 30 species of squirrel could be preying on smaller creatures: namely, fish, amphibians, reptiles, birds, and the occasional small mammal.

Read full article

Comments

The fall of the Berlin Wall in November 1989 was a seminal moment in 20th century history, paving the way for German reunification. Many segments, both large and small, were preserved for posterity—including portions covered in graffiti or murals. A team of Italian scientists used a combination of spectroscopic analysis and machine learning to study paint chips from wall fragments to learn more about the chemistry of the paints and pigments used, according to a new paper published in the Journal of the American Chemical Society.

There has been increased attention in recent years to preserving street art, which is vulnerable both to degradation over time as well as deliberate vandalism. For instance, in 2021, Italian chemists figured out how to use hydrogels to remove added graffiti from vandalized murals in Florence. (Over-painting by vandals is so chemically similar to the original painting underneath that it is difficult to selectively remove just the over-painting without damaging the original.) Unlike most classic masterpieces of the past, created with paints designed to last centuries, street art is more ephemeral in nature, using materials that lack such longevity.

In many cases, like the Berlin Wall, the painters didn't bother to document the specific materials they used, their application techniques, or other useful information that conservators could use to restore or conserve street art. Modern painting materials are also much more complex, and manufacturers typically do not report specific information on the composition of those materials.

Read full article

Comments

Archaeologists excavating a paleolithic cave site in Galilee, Israel, have found evidence that a deep-cave compound at the site may have been used for ritualistic gatherings, according to a new paper published in the Proceedings of the National Academy of Sciences (PNAS). That evidence includes the presence of a symbolically carved boulder in a prominent placement, and well as the remains of what may have been torches used to light the interior. And the acoustics would have been conducive to communal gatherings.

Dating back to the Early Upper Paleolithic period, Manot Cave was found accidentally when a bulldozer broke open its roof during construction in 2008. Archaeologists soon swooped in and recovered such artifacts as stone tools, bits of charcoal, remains of various animals, and a nearly complete human skull.

The latter proved to be especially significant, as subsequent analysis showed that the skull (dubbed Manot 1) had both Neanderthal and modern features and was estimated to be about 54,700 years old. That lent support to the hypothesis that modern humans co-existed and possibly interbred with Neanderthals during a crucial transition period in the region, further bolstered by genome sequencing.

Read full article

Comments

Physicists have been puzzling over conflicting observational results pertaining to the accelerating expansion rate of our Universe—a major discovery recognized by the 2011 Nobel Prize in Physics. New observational data from the James Webb Space Telescope (JWST) has confirmed that prior measurements of distances between nearby stars and galaxies made by the Hubble Space Telescope are not in error, according to a new paper published in The Astrophysical Journal. That means the discrepancy between observation and our current theoretical model of the Universe is more likely to be due to new physics.

As previously reported, the Hubble Constant is a measure of the Universe's expansion expressed in units of kilometers per second per megaparsec (Mpc). So, each second, every megaparsec of the Universe expands by a certain number of kilometers. Another way to think of this is in terms of a relatively stationary object a megaparsec away: Each second, it gets a number of kilometers more distant.

How many kilometers? That's the problem here. There are basically three methods scientists use to measure the Hubble Constant: looking at nearby objects to see how fast they are moving, gravitational waves produced by colliding black holes or neutron stars, and measuring tiny deviations in the afterglow of the Big Bang known as the Cosmic Microwave Background (CMB). However, the various methods have come up with different values. For instance, tracking distant supernovae produced a value of 73 km/s Mpc, while measurements of the CMB using the Planck satellite produced a value of 67 km/s Mpc.

Read full article

Comments

Epidermal electronics attached to the skin via temporary tattoos (e-tattoos) have been around for more than a decade, but they have their limitations, most notably that they don't function well on curved and/or hairy surfaces. Scientists have now developed special conductive inks that can be printed right onto a person's scalp to measure brain waves, even if they have hair. According to a new paper published in the journal Cell Biomaterials, this could one day enable mobile EEG monitoring outside a clinical setting, among other potential applications.

EEGs are a well-established, non-invasive method for recording the electrical activity of the brain, a crucial diagnostic tool for monitoring such conditions as epilepsy, sleep disorders, and brain injuries. It's also an important tool in many aspects of neuroscience research, including the ongoing development of brain-computer interfaces (BCIs). But there are issues. Subjects must wear uncomfortable caps that aren't designed to handle the variation in people's' head shapes, so a clinician must painstakingly map out the electrode positions on a given patient's head—a time-consuming process. And the gel used to apply the electrodes dries out and loses conductivity within a couple of hours, limiting how long one can make recordings.

By contrast, e-tattoos connect to skin without adhesives, are practically unnoticeable, and are typically attached via temporary tattoo, allowing electrical measurements (and other measurements, such as temperature and strain) using ultra-thin polymers with embedded circuit elements. They can measure heartbeats on the chest (ECG), muscle contractions in the leg (EMG), stress levels, and alpha waves through the forehead (EEG), for example.

Read full article

Comments

Ray spiders deploy an unusual strategy to capture prey in their webs. They essentially pull it back into a cone shape and release it when prey approaches, trapping said prey in the sticky silken threads. A few years ago, scientists noticed that they could get the spiders to release their webs just by snapping their fingers nearby, suggesting that the spiders relied at least in part on sound vibrations to know when to strike. Evidence for that hypothesis has now been confirmed in a new paper published in the Journal of Experimental Biology.

Most spider orb webs are static: the spiders weave them and fix them in place and then wait for prey to fly into the webs. That causes the silk threads to vibrate, alerting the spider that dinner is served. There are some species that actively actuate their webs, however, per the authors.

For instance, the triangle weaver spring-loads its triangular web once an insect has made contact so that the threads wrap around the prey in fractions of a second. Bolas spiders seem to detect prey in their vicinity through auditory cues, throwing a line of silk with a sticky end at passing moths to catch them. Ogre-faced spiders also seem to be able to hear potential prey, striking backward with a small silk net held in their front legs. It's a more proactive hunting strategy than merely waiting for prey to fly into a web.

Read full article

Comments

On April 15, 2019, the world watched in transfixed horror as a fire ravaged the famed Cathedral of Notre Dame in Paris, collapsing the spire and melting the lead roof. After years of painstaking restoration costing around $740 million, the cathedral reopens to the public this weekend. The December issue of National Geographic features an exclusive look inside the restored cathedral, accompanied by striking photographs by Paris-based photographer and visual artist Tomas van Houtryve.

For several hours, it seemed as if the flames would utterly destroy the 800-year-old cathedral. But after a long night of work by more than 400 Paris firefighters, the fire finally began to cool and attention began to shift to what could be salvaged and rebuilt. French President Emmanuel Macron vowed to restore Notre Dame to its former glory and set a five-year deadline. The COVID-19 pandemic caused some delays, but France nearly met that deadline regardless.

Those reconstruction efforts were helped by the fact that, a few years before the fire, scientist Andrew Tallon had used laser scanning to create precisely detailed maps of the interior and exterior of the cathedral—an invaluable aid as Paris rebuilds this landmark structure. French acousticians had also made detailed measurements of Notre Dame's "soundscape" that were instrumental in helping architects factor acoustics into their reconstruction plans. The resulting model even enabled Brian FG Katz, research director of the National Center for Scientific Research (CNRS) at Sorbonne University, to create a virtual reality version of Notre Dame with all the acoustical parameters in place.

Read full article

Comments

There's a common popular science demonstration involving "soap boats," in which liquid soap poured onto the surface of water creates a propulsive flow driven by gradients in surface tension. But it doesn't last very long since the soapy surfactants rapidly saturate the water surface, eliminating that surface tension. Using ethanol to create similar "cocktail boats" can significantly extend the effect because the alcohol evaporates rather than saturating the water.

That simple classroom demonstration could also be used to propel tiny robotic devices across liquid surfaces to carry out various environmental or industrial tasks, according to a preprint posted to the physics arXiv. The authors also exploited the so-called "Cheerios effect" as a means of self-assembly to create clusters of tiny ethanol-powered robots.

As previously reported, those who love their Cheerios for breakfast are well acquainted with how those last few tasty little "O"s tend to clump together in the bowl: either drifting to the center or to the outer edges. The "Cheerios effect is found throughout nature, such as in grains of pollen (or, alternatively, mosquito eggs or beetles) floating on top of a pond; small coins floating in a bowl of water; or fire ants clumping together to form life-saving rafts during floods. A 2005 paper in the American Journal of Physics outlined the underlying physics, identifying the culprit as a combination of buoyancy, surface tension, and the so-called "meniscus effect."

Read full article

Comments

Paleontologists have long puzzled over how the dinosaurs—originally relatively small and of minor importance to the broader ecosystem—evolved to become the dominant species some 30 million years later. Fossilized feces and vomit from dinosaurs might hold important clues to how and why this evolutionary milestone came about, according to a new paper published in the journal Nature.

Co-author Martin Qvarnström, an evolutionary biologist with Uppsala University in Sweden, and his collaborators studied trace fossils known as bromalites, a designation that includes coprolites as well as vomit or other fossilized matter from an organism's digestive tract. As previously reported, coprolites aren't quite the same as paleofeces, which retain a lot of organic components that can be reconstituted and analyzed for chemical properties. Coprolites are fossils, so most organic components have been replaced by mineral deposits like silicate and calcium carbonates.

For archaeologists keen on learning more about the health and diet of past populations—as well as how certain parasites evolved in the evolutionary history of the microbiome—coprolites and paleofeces can be a veritable goldmine of information. For instance, in 2021 we reported on an analysis of preserved paleo-poop revealing that ancient Iron Age miners in what is now Austria were fond of beer and blue cheese.

Read full article

Comments

Virtual reality (VR) technology has long sought to incorporate the human senses into virtual and mixed-reality environments. In addition to sight and sound, researchers have been trying to add the sensation of human touch and smell via various user interfaces, as well as taste. But the latter has proved to be quite challenging. A team of Hong Kong scientists has now developed a handheld user interface shaped like a lollipop capable of re-creating several different flavors in a virtual environment, according to a new paper published in the Proceedings of the National Academy of Sciences (PNAS).

It's well established that human taste consists of sweet, salty, sour, bitter, and umami—five basic flavors induced by chemical stimulation of the tongue and, to a lesser extent, in parts of the pharynx, larynx, and epiglottis. Recreating those sensations in VR has resulted in a handful of attempts at a flavor user interface, relying on such mechanisms as chemical, thermal, and electrical stimulation, as well as iontophoresis.

The chemical approach usually involves applying flavoring chemicals directly onto the tongue, but this requires room for bulk storage of said chemicals, and there is a long delay time that is not ideal for VR applications. Thermal variations applied directly to the tongue can stimulate taste sensations but require a complicated system incorporating a cooling subsystem and temperature sensors, among other components.

Read full article

Comments

In the wee hours of December 26, 2004, a massive 9.2 earthquake occurred in the Indian Ocean, generating an equally massive tsunami that caused unprecedented devastation to 14 countries and killed more than 230,000 people. Twenty years later, National Geographic has revisited one of the deadliest natural disasters in recorded history with a new documentary: Tsunami: Race Against Time. The four-part series offers an in-depth account of the tsunami's destructive path, told from the perspectives of those who survived, as well as the scientists, journalists, doctors, nurses, and everyday heroes who worked to save as many as possible.

Geophysicist Barry Hirshorn—now with Scripps Institution of Oceanography at the University of California, San Diego—was on duty at the Pacific Tsunami Warning Center in Hawaii that day (3 pm on Christmas Day local time). His pager went off, indicating that seismic waves had set off a seismometer in Australia, and Hirshorn rushed to the control room to locate the quake's epicenter with his colleague, Stuart Weinstein.

They initially pegged the quake at 8.5 magnitude. (It was later upgraded to 8.9 and subsequently to a whopping 9.2 to 9.3 magnitude.) But despite its strength, they initially did not think the quake would generate a tsunami, at least in the Pacific. And such events were incredibly rare in the Indian Ocean.

Read full article

Comments

The duck-billed dinosaur Parasaurolophus is distinctive for its prominent crest, which some scientists have suggested served as a kind of resonating chamber to produce low-frequency sounds. Nobody really knows what Parasaurolophus sounded like, however. Hongjun Lin of New York University is trying to change that by constructing his own model of the dinosaur's crest and its acoustical characteristics. Lin has not yet reproduced the call of Parasaurolophus, but he talked about his progress thus far at a virtual meeting of the Acoustical Society of America.

Lin was inspired in part by the dinosaur sounds featured in the Jurassic Park film franchise, which were a combination of sounds from other animals like baby whales and crocodiles. “I’ve been fascinated by giant animals ever since I was a kid. I’d spend hours reading books, watching movies, and imagining what it would be like if dinosaurs were still around today,” he said during a press briefing. “It wasn’t until college that I realized the sounds we hear in movies and shows—while mesmerizing—are completely fabricated using sounds from modern animals. That’s when I decided to dive deeper and explore what dinosaurs might have actually sounded like.”

A skull and partial skeleton of Parasaurolophus were first discovered in 1920 along the Red Deer River in Alberta, Canada, and another partial skull was discovered the following year in New Mexico. There are now three known species of Parasaurolophus; the name means "near crested lizard." While no complete skeleton has yet been found, paleontologists have concluded that the adult dinosaur likely stood about 16 feet tall and weighed between 6,000 to 8,000 pounds. Parasaurolophus was an herbivore that could walk on all four legs while foraging for food but may have run on two legs.

Read full article

Comments

The US Capitol building in Washington, DC, is adorned with multiple lavish murals created in the 19th century by Italian artist Constantino Brumidi. These include panels in the Senate first-floor corridors, Room H-144, and the rotunda. The crowning glory is The Apotheosis of Washington on the dome of the rotunda, 180 feet above the floor.

Brumidi worked in various mediums, including frescoes. Among the issues facing conservators charged with maintaining the Capitol building frescoes is delamination. Artists apply dry pigments to wet plaster to create a fresco, and a good fresco can last for centuries. Over time, though, the decorative plaster layers can separate from the underlying masonry, introducing air gaps. Knowing precisely where such delaminated areas are, and their exact shape, is crucial to conservation efforts, yet the damage might not be obvious to the naked eye.

Acoustician Nicholas Gangemi is part of a research group led by Joseph Vignola at the Catholic University of America that has been using laser Doppler vibrometry to pinpoint delaminated areas of the Capitol building frescoes. It's a non-invasive method that zaps the frescoes with sound waves and measures the vibrational signatures that reflect back to learn about the structural conditions. This in turn enables conservators to make very precise repairs to preserve the frescoes for future generations.

Read full article

Comments

Archaeologists have discovered numerous ceramic or clay whistles at Aztec sites, dubbed "death whistles" because of their distinctive skull shapes. A new paper published in the journal Communications Psychology examines the acoustical elements of the unique shrieking sounds produced by those whistles, as well as how human listeners are emotionally affected by the sounds. The findings support the hypothesis that such whistles may have been used in Aztec religious rituals or perhaps as mythological symbols.

Archaeologists unearthed the first Aztec death whistles, also known as ehecachichtlis, in 1999 while excavating the Tlatelolco site in Mexico City. They found the body of a sacrificial victim, a 20-year-old male who had been beheaded, at the base of the main stairway of a temple dedicated to the wind god Ehecatl. The skeleton was clutching two ceramic skull-shaped whistles, one in each hand, along with other artifacts. More skull whistles were subsequently found, and they've found their way into popular culture. For instance, in Ghostbusters: Afterlife (2021), Egon Spengler had such a whistle in his secret laboratory collection.

Scholars have puzzled over the purpose of the skull whistles, although given the dearth of concrete evidence, most suggestions are highly speculative. One hypothesis is that it was used in battle, with hundreds of warriors blowing their whistles simultaneously as a battle cry. Music archaeologist Arnd Adje Both has dismissed that idea, suggesting instead that the whistle's purpose was more likely tied to ceremonial or religious practices, like human sacrifice. Yet another hypothesis proposes that the whistles were intended as symbols of a deity. The skull shape, for instance, might allude to the Aztec god of the underworld, Mictlantecuhtli.

Read full article

Comments

University of Rochester physicist Ranga Dias made headlines with his controversial claims of high-temperature superconductivity—and made headlines again when the two papers reporting the breakthroughs were later retracted under suspicion of scientific misconduct, although Dias denied any wrongdoing. The university conducted a formal investigation over the past year and has now terminated Dias' employment, The Wall Street Journal reported.

Ars has been following this story ever since Dias first burst onto the scene with reports of a high-pressure, room-temperature superconductor, published in Nature in 2020. Even as that paper was being retracted due to concerns about the validity of some of its data, Dias published a second paper in Nature claiming a similar breakthrough: a superconductor that works at high temperatures but somewhat lower pressures. Shortly afterward, that paper was retracted as well. As Ars Science Editor John Timmer reported previously:

Dias' lab was focused on high-pressure superconductivity. At extreme pressures, the orbitals where electrons hang out get distorted, which can alter the chemistry and electronic properties of materials. This can mean the formation of chemical compounds that don't exist at normal pressures, along with distinct conductivity. In a number of cases, these changes enabled superconductivity at unusually high temperatures, although still well below the freezing point of water.

Dias, however, supposedly found a combination of chemicals that would boost the transition to superconductivity to near room temperature, although only at extreme pressures. While the results were plausible, the details regarding how some of the data was processed to produce one of the paper's key graphs were lacking, and Dias didn't provide a clear explanation.

The ensuing investigation cleared Dias of misconduct for that first paper. Then came the second paper, which reported another high-temperature superconductor forming at less extreme pressures. However, potential problems soon became apparent, with many of the authors calling for its retraction, although Dias did not.

Read full article

Comments

Spooky season has come and gone, but those Halloween revelers who took in a haunted house during the season might just have boosted their immune systems by doing so, according to a new paper published in the journal Brain, Behavior, and Immunity.

As previously reported, fear is typically viewed as a negative emotion, an adverse reaction to keep us on our toes with regard to potential dangers in our environment. But human beings also tend to seek out scary movies, horror novels, or haunted houses—and not just during the Halloween season. This tendency has been dubbed "recreational fear" in the academic literature: a "mixed emotional experience of fear and enjoyment."

Co-author Mathias Clasen of Aarhus University, author of Why Horror Seduces, specializes in studying recreational fear and and co-directs the Recreational Fear Lab with cognitive scientist Marc Andersen. For instance, Clasen and his colleagues have examined the dominant personality traits of horror fans. (They tend to score high on openness to experience, also called intellect imagination.) In 2019 we reported on his investigation of two different fear-regulation strategies employed by subjects participating in a Danish haunted house: "adrenaline junkies," who lean into the fear, and "white-knucklers," who try to tamp down their fear.

Read full article

Comments

Last year we reported on preliminary research suggesting that ancient Egyptians may have used hallucinogens in their religious rituals, based on the presence of a few key chemical signatures taken from a ceremonial mug. Now those researchers have extended their analysis and fully identified the chemical components of those samples, confirming those preliminary findings, according to a new paper published in the journal Scientific Reports.

There is ample evidence that humans in many cultures throughout history used various hallucinogenic substances in religious ceremonies or shamanic rituals. That includes not just ancient Egypt but also ancient Greek, Vedic, Maya, Inca, and Aztec cultures. The Urarina people who live in the Peruvian Amazon Basin still use a psychoactive brew called ayahuasca in their rituals, and Westerners seeking their own brand of enlightenment have also been known to participate.

Last year, David Tanasi, of the University of South Florida, posted a preprint on his preliminary analysis of a ceremonial mug decorated with the head of Bes, a popular deity believed to confer protection on households, especially mothers and children. So unlike most other Egyptian deities, images of Bes were quite common in Egyptian homes. There were even special chambers built to honor Bes and his wife, Beset, at the Saqqara site near Cairo, which Egyptologists think could have been used for fertility or healing rituals, although their exact purpose is not certain (Bes was an ancient Egyptian deity of protection, fertility, healing, and purification). The mug is part of the collection of the Tampa Museum of Art.

Read full article

Comments