Leonardo’s sketch showing the spiral motion of an ascending bubble from his manuscript known as the Codex Leicester
Prof. Miguel Ángel Herrada, from the University of Seville, and Prof. Jens G. Eggers, from the University of Bristol, have discovered a mechanism to explain the unstable movement of bubbles rising in water. According to the researchers, the results, which are published in the journal PNAS, may be useful to understand the motion of particles whose behavior is intermediate between a solid and a gas.
Leonardo da Vinci observed five centuries ago that air bubbles, if large enough, periodically deviate in a zigzag or spiral from straight-line movement. However, no quantitative description of the phenomenon or physical mechanism to explain this periodic motion had ever been found.
The authors of this new paper have developed a numerical discretization technique to characterize precisely the bubble’s air-water interface, which enables them to simulate its motion and explore its stability. Their simulations closely match high-precision measurements of unsteady bubble motion and show that bubbles deviate from a straight trajectory in water when their spherical radius exceeds 0.926 millimeters, a result within 2% of experimental values obtained with ultrapure water in the 90s.
The researchers propose a mechanism for the instability of the bubble trajectory whereby periodic tilting of the bubble changes its curvature, thus affecting the upward velocity and causing a wobble in the bubble’s trajectory, tilting up the side of the bubble whose curvature has increased.
Then, as the fluid moves faster and the fluid pressure falls around the high-curvature surface, the pressure imbalance returns the bubble to its original position, restarting the periodic cycle.
More information:
Miguel A. Herrada et al, Path instability of an air bubble rising in water, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2216830120
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Leonardo da Vinci’s paradox on the periodic motion of bubbles cracked (2023, January 17)
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On Monday, December 19, a mysterious shockwave in a gust of solar wind crashed into the Earth’s magnetic field, opening up a crack in the magnetosphere. According to Space Weather – an organization keeping track of such events – the barrage of plasma that penetrated the magnetosphere has led to a geomagnetic storm.
Although the shockwave’s origins are not exactly known, scientists believe it could have come from a coronal mass ejection (CME) launched by the sunspot AR3165, an area on the Sun’s surface which already released at least eight solar flares on December 14, causing a brief radio blackout over the Atlantic Ocean.
Sunspots are areas on the Sun’s surface where strong magnetic fields, created through the flow of electrical charges, entangle before suddenly snapping and releasing bursts of radiation called solar flares, or plumes of solar material called coronal mass ejections. Once launched, these CMEs can travel at extremely high speeds (often millions of miles per hour), sweeping up charged particles from the solar wind which, if pointed toward the Earth, can trigger geomagnetic storms.
These storms occur when solar debris consisting of electrons, protons, and alpha particles gets absorbed by the Earth’s magnetic field. If they are strong enough, they can create cracks in the magnetosphere which remain open for several hours, enabling some solar material to stream through and disrupt power systems, satellites, and radio communications.
Fortunately, the current storm was rather weak, causing only minor fluctuations in the power grids and impairing some satellite functions, such as those for mobile devices and GPS systems. However, scientists anticipate that in the following years, more powerful geomagnetic storms could warp our planet’s magnetic field to such an extent that satellites may tumble to Earth, electrical systems could be severely disrupted, and the Internet might stop working completely, thus causing trillions of dollars’ worth of damage, while triggering widespread blackouts and endangering thousands of lives.
—
By Andrei Ionescu, Earth.com Staff Writer
Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.
Long after its ancestors deleted their genetic code for a tough coat of armor, a seafaring octopus has reinvented a recipe for making a shell.
A recent genetic analysis of the paper nautilus or greater argonaut (Argonauta argo) has revealed a surprising origin for its protective casing, one that doesn’t resemble the shell of its closest relatives.
Instead of wearing their shells on the outside like sensible snails, most cephalopods (which are also mollusks), have done away with their tough outer garment. Many, like octopus and squid, have either lost their shells entirely or have only vestigial remnants left.
Others, like cuttlefish and the ram’s horn squid (Spirula spirula), wear their shells on the inside. The ram’s horn squid has an internal chambered spiral shell that acts like a skeleton of sorts. Buoyant and surprisingly durable, it’s often found washed up on beaches.
A rare exception among cephalopods is the nautilus (Nautilus belauensis), which still has an external shell – complete with air chambers that it uses to regulate its buoyancy as it floats through the open oceans. Its shell, and those of the now-extinct cephalopod ancestors, comprise of proteins incorporating minerals such as aragonite and calcite in intricate microscopic structures.
Having originated sometime in the Ordovician period, at least 440 million years ago, ancestors of all modern cephalopods are thought to have had these protective structures.
In spite of being commonly referred to as paper nautili, argonauts are actually a genus of octopus. In this unusual group, only the females produce a protective spiral casing, by secreting calcifying proteins from their arms. Argonauts wear these shells externally like a nautilus does, and their shapes are almost identical, yet this shell has a completely different microscopic structure.
What’s more, instead of being attached to their mantle, argonauts grip onto their shell homes with several of their arms.
Shells of the six still-living argonaut species. (Mgiganteus1/Wikimedia commons/CC BY-SA 3.0)
As most octopuses lost their external casings long ago, researchers have wondered how and why a single group reclaimed a shell.
Working with a team of researchers from across Japan, marine biologist Masa-aki Yoshida from Shimane University sequenced the DNA of Argonauta argo. They compared the argonauts’ genome to other mollusks, including the California two-spot octopus (Octopus bimaculoides) and the nautilus.
“Consistent with previous results, most of the proteins are apparently not shared with the shell matrix proteins of [cephalopods and relatives], including those of Nautilus,” the team writes in their paper.
Some of the genes and the proteins they express have, however, been found in other shelled mollusks like the limpet (Lottia gigantea) and Japanese pearl oyster (Pinctada fucata). Other sequences were found in shell-less octopuses – suggesting the argonaut cobbled together their protective casing using proteins unrelated to ancestral shell formation.
Unlike other octopuses, argonauts aren’t benthic – they don’t live near the sea floor or other structures. Instead, they’ve taken on the life of drifters, floating amidst the tropical and subtropical open seas their entire life. This is the same pelagic lifestyle shared by the nautilus.
To achieve this, argonauts needed techniques to allow easy floating too, Yoshida and team explain. While their shell lacks the nautilus’ more complicated internal structure of air chambers, it can still trap some air.
This shell is also known to be the argonaut’s egg case, which would explain why only females develop them. The females brood their eggs within the shell’s protection, eliminating the need to hide their eggs away on a substrate like the sea floor as most other octopus do.
Argonauts appear to have completely reinvented the shell from scratch to aid its transition from substrate dweller to water drifter, mimicking the nautilus in a remarkable example of convergent evolution.
This research was published in Genome Biology and Evolution.
Dodgers manager Dave Roberts told reporters, including Juan Toribio of MLB.com, that Mookie Betts is headed to the injured list due to a cracked rib. Roberts said that the corresponding move will likely be the recall of Zach McKinstry, per Fabian Ardaya of The Athletic.
Betts sat out last night’s game due to this issue, though he was back in the lineup today. However, shortly before game time, he was scratched as his soreness lingered. As the club continued testing, an MRI revealed a cracked rib, per Ardaya.
The expected timeline for the absence of Betts isn’t known at this time, but the loss of a talent like his for any amount of time is significant. The former MVP is having yet another excellent campaign, hitting .273/.349/.535 for a 148 wRC+. Combining that batting line with his excellent defense and baserunning, Betts has already accrued 3.3 wins above replacement on the year, in the estimation of FanGraphs.
The Dodgers are having another excellent season, as has come to be the norm for them. However, they appear to be in for a fight this year, as their 40-24 record is just percentage points ahead of the Padres, with the Giants lurking just three games back. That means that every inch will count in the postseason race to come, with the loss of Betts marking a significant blow.
Enlarge / A laboratory reproduction of the Zen stone phenomenon in a lyophilizer.
Nicolas Taberlet / Nicolas Plihon
Visit the Small Sea of Lake Baikal in Russia during the winter and you’ll likely see an unusual phenomenon: a flat rock balanced on a thin pedestal of ice, akin to stacking Zen stones common to Japanese gardens. The phenomenon is sometimes called a Baikal Zen formation. The typical explanation for how these formations occur is that the rock catches light (and heat) from the Sun and this melts the ice underneath until just a thin pedestal remains to support it. The water under the rock refreezes at night, and it’s been suggested that wind may also be a factor.
Now, two French physicists believe they have solved the mystery of how these structures form, according to a new paper published in the Proceedings of the National Academy of Sciences—and their solution has nothing to do with the thermal conduction of the stone. Rather, they attribute the formation to a phenomenon known as sublimation, whereby snow or ice evaporates directly into vapor without passing through a water phase. Specifically, the shade provided by the stone hinders the sublimation rates of the surrounding ice in its vicinity, while the ice further away sublimates at a faster rate.
Many similar formations occur naturally in nature, such as hoodoos (tall, spindly structures that form over millions of years within sedimentary rock), mushroom rocks or rock pedestals (the base has been eroded by strong dusty winds), and glacier tables (a large stone sitting precariously on top of a narrow pedestal of ice). But the underlying mechanisms by which they form can be very different.
For instance, as we reported last year, a team of applied mathematicians from New York University studied the so-called “stone forests” common in certain regions of China and Madagascar. These pointed rock formations, like the famed Stone Forest in China’s Yunnan Province, are the result of solids dissolving into liquids in the presence of gravity, which produces natural convective flows.
On the surface, these stone forests look rather similar to “penitentes”: snowy pillars of ice that form in very dry air found high in the Andean glaciers. Charles Darwin described penitentes in 1839 during a March 1835 excursion in which he squeezed his way through snowfields covered in penitentes on the way from Santiago, Chile, to the Argentine city of Mendoza. Physicists have been able to recreate artificial versions of penitentes in the lab. But penitentes and stone forests are actually quite different in terms of the mechanisms involved in their formation. The spikes of a stone forest are carved by flows, which don’t play a big role in the formation of penitentes.
Some physicists have suggested that penitentes form when sunlight evaporates the snow directly into vapor (sublimation). Tiny crests and troughs form, and sunlight gets trapped within them, creating extra heat that carves out even deeper troughs, and those curved surfaces in turn act as a lens, speeding up the sublimation process even more. An alternative proposal adds an additional mechanism to account for the oddly periodic fixed spacing of penitentes: a combination of vapor diffusion and heat transport that produces a steep temperature gradient and, hence, a higher sublimation rate.
Enlarge / Zen stones in nature, in the Small Sea of Lake Baikal (a, b); in the laboratory (c); and in numerical simulations (d). (a) Photograph taken by O. Zima. (b) Photograph taken by A. Yanarev.
Nicolas Taberlet/Nicolas Plihon
In the case of the Baikal Zen stone formations, the process seems similar to the sublimation hypothesis for penitentes, according to co-authors Nicolas Taberlet and Nicolas Plihon of CNRS in Lyon, France. Earlier this month, they published a somewhat related study in Physical Review Letters on the natural formation of glacier tables (a rock supported by a slender column of ice). They were able to produce small-scale artificial glacier tables in a controlled environment, and found two competing effects that control the onset of glacier table formation.
With smaller stone caps with higher thermal conductivity, geometrical amplification of the heat flux causes the cap to sink into the ice. For a larger cap with less thermal conductivity, a reduction in heat flux arises from the fact that the cap has a higher temperature than the surrounding ice, forming a table.
For this latest study, Taberlet and Plihon wanted to explore the underlying mechanisms behind the natural formation of Baikal Zen structures. “The scarcity of the phenomenon stems from the rarity of thick, flat, snow-free layers of ice, which require long-standing cold and dry weather conditions,” the authors wrote. “Weather records show that melting of the ice is virtually impossible and that, instead, the weather conditions (wind, temperature, and relative humidity) favor sublimation, which has long been known to be characteristic of the Lake Baikal area.”
So the researchers set about trying to reproduce the phenomenon in the laboratory to test their hypothesis. They used metal disks as experimental analogs of the stones, placing the disks on the surface of blocks of ice in a commercial lyophilizer. The instrument freezes material, then reduces the pressure and adds heat, such that the frozen water sublimates. The higher reflectivity of the metal disks compared to stones kept the disks from overheating in the lyophilizer’s chambers.
Extraterrestrial
Both aluminum and copper disks produced the Baikal Zen formations, even though copper has almost twice the thermal conductivity of aluminum. The authors concluded that, therefore, the thermal properties of stone were not a crucial factor in the process. “Far from the stone, the sublimation rate is governed by the diffuse sunlight, while in its vicinity the shade it creates inhibits the sublimation process,” the authors wrote. “We show that the stone only acts as can umbrella whose shade hinders the sublimation, hence protecting the ice underneath, which leads to the formation of the pedestal.”
This was subsequently confirmed by numerical modeling simulations. Taberlet and Plihon also found that the dip, or depression, surrounding the pedestal is the result of far infrared radiation emitted by the stone (or disk) itself, which enhances the overall sublimation rate in its vicinity.
It’s quite different from the process that leads to glacier tables, despite the similar shape of the two formations. In the case of glacier tables, the umbrella effect is only a secondary factor in the underlying mechanism. “Glacier tables appear on low-altitude glaciers when the weather conditions cause the ice to melt instead of to sublimate,” the authors wrote. “They form in warm air while the ice remains at 0 degrees Celsius, whereas Zen stones form in air that is colder than the ice.”
Understanding how these formations occur naturally could help us learn more about other objects in the universe, since ice sublimation has produced penitentes on Pluto and have influenced landscape formation on Mars, Pluto, Ceres, the moons of Jupiter, the moons of Saturn, and several comets. “Indeed, NASA’s Europa Lander project aims to seek biosignatures on Jupiter’s ice-covered moon, on the surface of which differential sublimation may threaten lander stability, and this needs to be fully understood,” the authors concluded.
An image of an Old German Owl, left, and Racing Homer, right. The two domestic pigeon species were the the grandparents of over 100 pigeons researched in a study regarding why domestic pigeon beaks widely range in size. (Sydney Stringham via University of Utah)
SALT LAKE CITY — There are many animals that piqued Charles Darwin’s interest during his legendary studies in the 19th century.
He may be mostly associated with tortoises and finches, but he also dwelled often on the domestic pigeon. That’s because the species helped form his theory of natural selection because he noted domestic pigeons were artificially selected, Michael Wheelock wrote in a piece for Rockefeller University’s “The Incubator” back in 2013.
But one facet of pigeons he wondered about was why, exactly, did the more than 300 various breeds of pigeons have beaks of different shapes and sizes, including beaks short enough to make it difficult for parents to feed their young?
Well over a century later, University of Utah researchers say they now have an answer to what they called “Darwin’s short-beak enigma.” They say short beaks in pigeons are the result of a genetic mutation, the same genetic mutation that causes Robinow syndrome in humans. Their findings were published Tuesday in the journal “Current Biology.”
To get to their finding, a team of researchers bred two pigeons with different beaks. Michael Shapiro, who is the James E. Talmage Presidential Endowed Chair in Biology at the University of Utah and senior author of the study, explained that domestic pigeon breeders selected beaks based on aesthetics and not anything that would benefit the species in nature. Because of this, the researchers knew they could find genes responsible for different beak sizes.
“One of Darwin’s big arguments was that natural selection and artificial selection are variations of the same process,” Shapiro said in a statement Tuesday. “Pigeon beak sizes were instrumental in figuring out how that works.”
The team started by breeding a Racing Homer with a medium-sized beak similar to the ancestral rock pigeon with an Old German Owl, which despite the name is a fancy pigeon breed with a small beak. Their brood featured intermediate-length beaks; when those birds mated with another, their offspring featured various beak sizes and shapes.
Elena Boer — a clinical variant scientist at ARUP Laboratories, former postdoctoral research fellow at the University of Utah and the study’s lead author — then used micro-CT scans to measure the beaks of the over 100 birds produced as grandchildren of the original pigeon couple. She found that not only did the beaks differ but so did the shape of the birds’ braincases.
“These analyses demonstrated that beak variation within the (grandchild) population was due to actual differences in beak length and not variation in overall skull or body size,” she said in a statement.
But the largest finding of the paper is that the short beaks are the result of alterations to the ROR2 gene. This was discovered through two steps.
They first used a process called quantitative trait loci mapping, which helped them identify DNA sequence variants and also the ability to search for mutations in the chromosomes of the grandchildren. The results confirmed what the researchers expected based on previous classical genetic experiments, according to Shapiro. He said they found that the grandchildren with small beaks had “the same piece of chromosome” as the grandparent with a small beak.”
They then analyzed all of the genome sequences from the different pigeon breeds. This research showed that all the birds with small beaks had the same DNA sequence in the genome that contains the ROR2 gene. Boer said finding the same results in two different approaches was “really exciting” because it strongly indicates ROR2 gene is the leading factor for the beak size.
She added that ROR2 gene mutations also result in Robinow syndrome within humans.
“Some of the most striking characteristics of Robinow syndrome are the facial features, which include a broad, prominent forehead and a short, wide nose and mouth, and are reminiscent of the short-beak phenotype in pigeons,” she explained. “It makes sense from a developmental standpoint because we know that the ROR2 signaling pathway plays an important role in vertebrate craniofacial development.”
And one of Darwin’s many quandaries regarding animal mutations is now solved.
Resident Evil Village is a good game. But on the PC the game has suffered from annoying stuttering issues that have left many frustrated. Capcom has yet to fix these issues, but now a cracked release of the game that removes all DRM seems to have fixed all the stuttering.
As reported by Dark Side Of Gaming, the PC version of Resident Evil Village was recently cracked by EMPRESS, a famous DRM remover. Now that Village has been cracked, anyone who knows where to look can download a pirated version of the game and play it without DRM. Removing DRM from Village also seems to have fixed those nasty stuttering issues that have been plaguing the game since it was released back in May.
In a message announcing the cracked release of Village, EMPRESS claims that Capcom is using both Denuvo and its own DRM technology. And it seems that all that DRM inside Village was the culprit behind the stutters and gameplay hitches players have experienced.
“All in-game shutters like the one from when you kill a zombie are fixed because Capcom DRM’s entry points are patched out,” explained EMPRESS. “So most of their functions are never executed anymore. This results in much smoother game experience.”
Gameplay of the cracked RE Village.
According to DSOG, after testing the newly cracked version of the game for a few hours, they can confirm that it indeed runs better and is a more enjoyable experience. In a video posted by the DSOG’s EIC, you can clearly see how smooth the game now runs with all the DRM patched out. Compare that to this video of an uncracked version of the game running on RTX 3080.
G/O Media may get a commission
Kotaku has reached out to Capcom and Denuvo about the stuttering and the recent cracked version that appears to fix the issue in Village.
Capcom confirmed in June during E3 that it had started work on DLC for Resident Evil Village. No more details about the upcoming DLC were revealed, but hopefully, Capcom can get the PC version of Village running better before then, even if it means removing DRM from it.
Read More:Resident Evil Village Vs. Resident Evil 4: The Best Merchant
The mystery of the Dyatlov Pass has raised questions for over half a century.
Soviet investigators/Creative Commons
The Dyatlov Pass incident is a spooky tale most often told in hushed tones around a campfire, but this very real — and very mysterious — event has long been the subject of conspiracy theories, scientific conjecture and even a movie or two. But the truth of what drove nine experienced hikers to slash through the safety of their own tent and flee, half-dressed into the snow of the Ural mountains, has remained inconclusive for over half a century.
That is, until now. After 62 years of speculation, scientists believe they may have figured out what happened in the Ural Mountains, all those years ago.
Thanks to simulations, analytical models and even some borrowed Disney technology, the data indicates an impactful force of nature could very well be the conclusive answer.
What is the Dyatlov Pass mystery?
In January 1959, a team of experienced Russian mountaineers were trekking in the Ural Mountains — at least, they were, until they perished under mysterious circumstances.
Personal diaries and film discovered on site confirm that the team had made camp on a stretch of the slopes known as Kholat Saykhl, or “dead mountain.” However, something caused the hikers to flee in the middle of the night, cutting their way out of the tent and sprawling across the mountain — barely dressed despite subzero temperatures and a thick layer of snow.
When a search and rescue team finally found them, scattered over the pass weeks later, they discovered that while six of the hikers had died from hypothermia, the remaining three hikers had been killed by extreme physical trauma. There were body parts missing — one hiker’s eyes, another’s tongue — and severe skeletal damage to some of the skulls and chests.
The only problem? There was no convincing evidence to explain why or how this had happened. At the time, the investigators concluded only that an unknown but powerful “natural force” had compelled them to leave their tent. Conspiracies range from katabatic winds through to Yeti attack and even infrasound-induced panic, but no definitive conclusion was ever made to explain the deaths.
Until, potentially, now.
From the lab to your inbox. Get the latest science stories from CNET every week.
Simulations, Disney and a potential answer
In an article published in the journal Communications Earth and Environment, researchers identified data supporting the theory that a small, impactful avalanche could have been the culprit.
It’s not the first time such a hypothesis has arisen. In fact, it was one of the first conclusions drawn — it just had no supporting evidence. In 2019, a team of Russian scientists also concluded that it was an avalanche, but the data to support the theory was once again lacking. There had been no definitive evidence of an avalanche — even a small one. The topography and snowfall levels didn’t match such an incident.
Now, however, a team from the Snow Avalanche Simulation Laboratory at the École polytechnique fédérale in Lausanne, Switzerland, has been able to use analytical models, simulations and even technology from Disney’s animation studios to explain how an avalanche may have occurred without leaving behind evidence.
Reported by National Geographic, the data indicated the avalanche would have been particularly small — perhaps as small as 16 feet of ice and snow, compacted into a solid slab. This would allow for the conditions to mask the phenomena over time, with snowfall obscuring any debris, while still creating enough of a threat to compel the hikers to slash their way out.
But it still didn’t explain the extreme trauma left on some of the bodies. To answer that question, the team looked to Disney’s Frozen. Johan Gaume, head of the laboratory, combined their simulation tools with animation models borrowed from Frozen’s creative team to analyze how the impact of the avalanche would affect the bodies.
Using the simulation, enhanced by these animation models, the team was able to conclude that the suspected avalanche could have had enough of an impact if the hikers had arranged their bedding on top of their skis, providing a rigid base upon which the force would have been exerted — crushing skulls and chests between the two hard forces.
There’s still little evidence as to what happened next, given that all the hikers were found outside the tent, but the best theory is that they then tried to escape the avalanche and rescue their injured teammates — though their injuries and the extreme temperature would eventually prove fatal. As for the missing body parts? Animal scavengers are the likely culprit.
So while the study goes a long way in explaining a possible, even likely, scenario for the deaths of the hikers on Dyatlov Pass, a lot of questions still remain.
And those questions are inevitably going to keep conspiracy theorists busy speculating for years to come.
