It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Monday, February 05, 2024
SPACE
A Russian cosmonaut sets a new record for the most time in space
by The Associated Press
From left: CSA astronaut David Saint Jacques, Russian cosmonaut Оleg Kononenko and U.S. astronaut Anne McClain pose for a photo before their final preflight practical examination in a mock-up of a Soyuz space craft at Russian Space Training Center in Star City, outside Moscow, Russia, Wednesday, Nov. 14, 2018. The Russian space agency says one of its cosmonauts has broken the world record for the most time spent in space. Oleg Kononenko, who's 59 has made five journeys to the International Space Station, dating back to 2008.
Credit: AP Photo/Pavel Golovkin, File
Russian cosmonaut Oleg Kononenko has broken the world record for the most cumulative time spent in space, Russia's space agency Roscosmos reported Sunday.
The 59-year-old has now spent more than 878 days and 12 hours in space, surpassing fellow Russian Gennady Padalka, who set the previous record of 878 days, 11 hours, 29 minutes, and 48 seconds in 2015.
Kononenko has made five journeys to the International Space Station, dating back to 2008.
Speaking with Russian state news agency TASS, the engineer said that each trip to the ISS required careful preparation due to the station's constant upgrades—but that life as a cosmonaut was a childhood dream come true.
"I fly into space to do what I love, not to set records. I've dreamt of and aspired to become a cosmonaut since I was a child. That interest—the opportunity to fly into space, to live and work in orbit—motivates me to continue flying," he told TASS.
Kononenko's current trip to the ISS began on Sept. 15, 2023, when he launched alongside NASA astronaut Loral O'Hara and Roscosmos compatriot Nikolai Chub. By the end of this expedition, the cosmonaut is expected to become the first person to accumulate 1,000 days in space.
The International Space Station is one of the few areas in which the United States and Russia still cooperate closely following Moscow's invasion of Ukraine in Feb. 2022. Roscosmos announced in December that its cross-flight program with NASA transporting astronauts to the ISS had been extended until 2025.
Russian Space Agency experts test a space suit of Russian cosmonaut Oleg Kononenko, a crew member of the next mission to the International Space Station, prior to the launch of Soyuz-FG booster rocket with the space capsule Soyuz TMA-14M at the Russian leased Baikonur Cosmodrome, in Kazakhstan, Wednesday, July 22, 2015. The Russian space agency says one of its cosmonauts has broken the world record for the most time spent in space. Oleg Kononenko, who's 59 has made five journeys to the International Space Station, dating back to 2008. Credit: AP Photo/Pavel Golovkin, File
FILE -- Russian cosmonaut Oleg Kononenko, a crew member of the next mission to the International Space Station, attends a news conference at the Russian leased Baikonur Cosmodrome, in Kazakhstan, Tuesday, July 21, 2015. The Russian space agency says one of its cosmonauts has broken the world record for the most time spent in space. Oleg Kononenko, who's 59 has made five journeys to the International Space Station, dating back to 2008. Credit: AP Photo/Pavel Golovkin, File
A color-composite image of PEARLSDG made with JWST NIRCAM data. Individual stars are visible as small points of light in the image. Its somewhat dull color and lack of many bright stars is consistent with its old age and lack of ongoing star formation. Credit: NASA, ESA, CSA, Jake Summers (ASU), Jordan C. J. D'Silva (UWA), Anton M. Koekemoer (STScI), Aaron Robotham (UWA) and Rogier Windhorst (ASU)
A team of astronomers, led by Arizona State University Assistant Research Scientist Tim Carleton, has discovered a dwarf galaxy that appeared in James Webb Space Telescope imaging that wasn't the primary observation target.
Galaxies are bound together by gravity and made up of stars and planets, with vast clouds of dust and gas as well as dark matter. Dwarf galaxies are the most abundant galaxies in the universe, and are by definition small with low luminosity. They have fewer than 100 million stars, while the Milky Way, for example, has nearly 200 billion stars.
Recent dwarf galaxy observations of the abundance of "ultra-diffuse galaxies" beyond the reach of previous large spectroscopic surveys suggest that our understanding of the dwarf galaxy population may be incomplete.
In a newly published study, Carleton and the team were initially looking at a cluster of galaxies as part of the JWST Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS) project.
The dwarf galaxy, PEARLSDG, happened to appear in some of the team's JWST imaging. It wasn't the target at all—just a bit off from the main observation field, in the area of space where they weren't expecting to see anything.
Their results have been published in the Astrophysical Journal Letters.
PEARLSDG did not have the usual characteristics of a dwarf galaxy one would expect to see. It isn't interacting with a nearby galaxy, but it also isn't forming new stars. As it turns out, it is an interesting case of an isolated quiescent galaxy.
"These types of isolated quiescent dwarf galaxies haven't really been seen before except for relatively few cases. They are not really expected to exist given our current understanding of galaxy evolution, so the fact that we see this object helps us improve our theories for galaxy formation," said Carleton. "Generally, dwarf galaxies that are out there by themselves are continuing to form new stars."
Until now, astronomers' understanding of galaxy evolution showed an isolated galaxy that continued to form young stars or it would interact with a more massive companion galaxy. This theory didn't apply to PEARLSDG, which presents as an old stellar population, not forming new stars as well as keeping to itself.
In a further surprise, individual stars can be observed in the team's JWST images. These stars are brighter in JWST wavelengths; it is one of the farthest galaxies that we can see these stars with this level of detail. The brightness of these stars allows astronomers to be able to measure its distance—98 million light-years.
Top: the JWST of the PEARLSDG galaxy (blue = F090W + F150W, green = F200W + 0.5 × F277W, red = 0.5 × F277W+F356W+F444W). Bottom: DECALS grz image of the sky immediately surrounding PEARLSDG. Both images are aligned such that north is up and east is left. PEARLSDG is identified with the cyan box, and the green squares show the area covered by NIRCam imaging. Also shown are two of the closest (in-projection) nearby massive galaxies (identified in red circles). Credit: The Astrophysical Journal Letters (2024). DOI: 10.3847/2041-8213/ad1b56
For this study, Carleton—who is an assistant research scientist at the Beus Center for Cosmic Foundations in the School of Earth and Space Exploration at ASU—and the team used a wide range of data.
This includes imaging data from JWST's Near-InfraRed Camera (NIRCam); spectroscopic data from the DeVeney Optical Spectrograph on the Lowell Discovery Telescope in Flagstaff, Arizona; archival imaging from NASA's Galex and Spitzer space telescopes; and ground-based imaging from the Sloan Digital Sky Survey and the Dark Energy Camera Legacy Survey.
JWST's NIRCam has very high angular resolution and sensitivity, allowing the team to identify individual stars in this distant galaxy. Just like individual cells coming into focus under a microscope, these observations brought the components of PEARLSDG into sharp focus.
Importantly, identifying specific stars in the imaging provided a key clue to its distance—these stars have a specific intrinsic brightness, so by measuring their apparent brightness with JWST, the team was able to determine how far away they are. It turns out that these stars were some of the most distant stars of their type to be observed.
All of the archival imaging data, observed at ultraviolet, optical and infrared wavelengths, was pulled together to study the color of PEARLSDG. Newly formed stars have a specific color signature, so the absence of such a signature was used to show that PEARLSDG was not forming new stars.
The DeVeney Spectrograph at the Lowell Discovery Telescope spreads the light astronomical objects into its distinct components, allowing astronomers to study its properties in detail. For example, the specific wavelength shift observed in features in the spectroscopic data encodes information about the motion of PEARLSDG, using the same Doppler effect that radar guns use to measure the speed of drivers on Arizona roads.
This was key to show that PEARLSDG is not associated with any other galaxy and is truly isolated.
Additionally, particular features in the spectrum are sensitive to the presence of young stars, so the absence of those features further corroborated the measurements of the absence of young stars from the imaging data.
"This was absolutely against people's expectations for a dwarf galaxy like this," Carleton said.
This discovery changes astronomers' understanding of how galaxies form and evolve. It suggests the possibility that many isolated quiescent galaxies are waiting to be identified and that JWST has the tools to do so.
More information: Timothy Carleton et al, PEARLS: A Potentially Isolated Quiescent Dwarf Galaxy with a Tip of the Red Giant Branch Distance of 30 Mpc, The Astrophysical Journal Letters (2024). DOI: 10.3847/2041-8213/ad1b56
Planets can gravitationally affect each other when their orbits line up. Credit: NASA/JPL-Caltech
Planets orbit their parent stars while separated by enormous distances—in our solar system, planets are like grains of sand in a region the size of a football field. The time that planets take to orbit their suns have no specific relationship to each other.
But sometimes, their orbits display striking patterns. For example, astronomers studying six planets orbiting a star 100 light years away have just found that they orbit their star with an almost rhythmic beat, in perfect synchrony. Each pair of planets completes their orbits in times that are the ratios of whole numbers, allowing the planets to align and exert a gravitational push and pull on the other during their orbit.
This type of gravitational alignment is called orbital resonance, and it's like a harmony between distant planets.
Greek mathematician Pythagoras discovered the principles of musical harmony 2,500 years ago by analyzing the sounds of blacksmiths' hammers and plucked strings.
He believed mathematics was at the heart of the natural world and proposed that the sun, moon and planets each emit unique hums based on their orbital properties. He thought this "music of the spheres" would be imperceptible to the human ear.
VIDEO Orbital resonance, as seen with Jupiter’s moons, happens when planetary bodies’ orbits line up – for example, Io orbits Jupiter four times in the time it takes Europa to orbit twice and Ganymede to orbit once.Credit: WolfmanSF/Wikimedia Commons
Four hundred years ago, Johannes Kepler picked up this idea. He proposed that musical intervals and harmonies described the motions of the six known planets at the time.
To Kepler, the solar system had two basses, Jupiter and Saturn; a tenor, Mars; two altos, Venus and Earth; and a soprano, Mercury. These roles reflected how long it took each planet to orbit the sun, lower speeds for the outer planets and higher speeds for the inner planets.
He called the book he wrote on these mathematical relationships "The Harmony of the World." While these ideas have some similarities to the concept of orbital resonance, planets don't actually make sounds, since sound can't travel through the vacuum of space.
Orbital resonance
Resonance happens when planets or moons have orbital periods that are ratios of whole numbers. The orbital period is the time taken for a planet to make one complete circuit of the star. So, for example, two planets orbiting a star would be in a 2:1 resonance when one planet takes twice as long as the other to orbit the star. Resonance is seen in only 5% of planetary systems.
In the solar system, Neptune and Pluto are in a 3:2 resonance. There's also a triple resonance, 4:2:1, among Jupiter's three moons: Ganymede, Europa and Io. In the time it takes Ganymede to orbit Jupiter, Europa orbits twice and Io orbits four times. Resonances occur naturally, when planets happen to have orbital periods that are the ratio of whole numbers.
Musical intervals describe the relationship between two musical notes. In the musical analogy, important musical intervals based on ratios of frequencies are the fourth, 4:3, the fifth, 3:2, and the octave, 2:1. Anyone who plays the guitar or the piano might recognize these intervals.
Musical intervals can be used to create scales and harmony.
Orbital resonances can change how gravity influences two bodies, causing them to speed up, slow down, stabilize on their orbital path and sometimes have their orbits disrupted.
Think of pushing a child on a swing. A planet and a swing both have a natural frequency. Give the child a push that matches the swing motion and they'll get a boost. They'll also get a boost if you push them every other time they're in that position, or every third time. But push them at random times, sometimes with the motion of the swing and sometimes against, and they get no boost.
For planets, the boost can keep them continuing on their orbital paths, but it's much more likely to disrupt their orbits.
Exoplanet resonance
Exoplanets, or planets outside the solar system, show striking examples of resonance, not just between two objects but also between resonant "chains" involving three or more objects.
Orbital resonance can cause planets or asteroids to speed up or start to wobble.
The star Gliese 876 has three planets with orbit period ratios of 4:2:1, just like Jupiter's three moons. Kepler 223 has four planets with ratios of 8:6:4:3.
The red dwarf Kepler 80 has five planets with ratios of 9:6:4:3:2, and TOI 178 has six planets, of which five are in a resonant chain with ratios of 18:9:6:4:3.
TRAPPIST-1 is the record holder. It has seven Earth-like planets, two of which might be habitable, with orbit ratios of 24:15:9:6:4:3:2.
The newest example of a resonant chain is the HD 110067 system. It's about 100 light years away and has six sub-Neptune planets, a common type of exoplanet, with orbit ratios of 54:36:24:16:12:9. The discovery is interesting because most resonance chains are unstable and disappear over time.
Despite these examples, resonant chains are rare, and only 1% of all planetary systems display them. Astronomers think that planets form in resonance, but small gravitational nudges from passing stars and wandering planets erase the resonance over time. With HD 110067, the resonant chain has survived for billions of years, offering a rare and pristine view of the system as it was when it formed.
Orbit sonification
Music from planetary orbits, created by astronomers at the European Southern Observatory.
With exoplanets, sonification can convey the mathematical relationships of their orbits. Astronomers at the European Southern Observatory created what they call "music of the spheres" for the TOI 178 system by associating a sound on a pentatonic scale to each of the five planets.
A similar musical translation has been done for the TRAPPIST-1 system, with the orbital frequencies scaled up by a factor of 212 million to bring them into audible range.
Astronomers have also created a sonification for the HD 110067 system. People may not agree on whether these renditions sound like actual music, but it's inspiring to see Pythagoras' ideas realized after 2,500 years.
Lupus and other autoimmune diseases strike far more women than men. Now there's a clue why
by Lauran Neergaard
This image provided by National Institutes of Health (NIH) shows the X and Y chromosomes. Women are far more likely than men to get autoimmune diseases, illnesses like lupus or rheumatoid arthritis that occur when the immune system mistakenly attacks their own tissues. That gender disparity has baffled scientists for decades but new research may finally explain why. (Jonathan Bailey/National Institutes of Health (NIH) via AP)
Women are far more likely than men to get autoimmune diseases, when an out-of-whack immune system attacks their own bodies—and new research may finally explain why.
It's all about how the body handles females' extra X chromosome, Stanford University researchers reported Thursday—a finding that could lead to better ways to detect a long list of diseases that are hard to diagnose and treat.
"This transforms the way we think about this whole process of autoimmunity, especially the male-female bias," said University of Pennsylvania immunologist E. John Wherry, who wasn't involved in the study.
More than 24 million Americans, by some estimates up to 50 million, have an autoimmune disorder—diseases such as lupus, rheumatoid arthritis, multiple sclerosis and dozens more. About 4 of every 5 patients are women, a mystery that has baffled scientists for decades.
One theory is that the X chromosome might be a culprit. After all, females have two X chromosomes while males have one X and one Y.
The new research, published in the journal Cell, shows that extra X is involved—but in an unexpected way.
Our DNA is carried inside each cell in 23 pairs of chromosomes, including that final pair that determines biological sex. The X chromosome is packed with hundreds of genes, far more than males' much smaller Y chromosome. Every female cell must switch off one of its X chromosome copies, to avoid getting a toxic double dose of all those genes.
Performing that so-called X-chromosome inactivation is a special type of RNA called Xist, pronounced like "exist." This long stretch of RNA parks itself in spots along a cell's extra X chromosome, attracts proteins that bind to it in weird clumps, and silences the chromosome.
Stanford dermatologist Dr. Howard Chang was exploring how Xist does its job when his lab identified nearly 100 of those stuck-on proteins. Chang recognized many as related to skin-related autoimmune disorders—patients can have "autoantibodies" that mistakenly attack those normal proteins.
"That got us thinking: These are the known ones. What about the other proteins in Xist?" Chang said. Maybe this molecule, found only in women, "could somehow organize proteins in such a way as to activate the immune system."
If true, Xist by itself couldn't cause autoimmune disease or all women would be affected. Scientists have long thought it takes a combination of genetic susceptibility and an environmental trigger, such as an infection or injury, for the immune system to run amok. For example, the Epstein-Barr virus is linked to multiple sclerosis.
Chang's team decided to engineer male lab mice to artificially make Xist—without silencing their only X chromosome—and see what happened.
Researchers also specially bred mice susceptible to a lupus-like condition that can be triggered by a chemical irritant.
The mice that produced Xist formed its hallmark protein clumps and, when triggered, developed lupus-like autoimmunity at levels similar to females, the team concluded.
"We think that's really important, for Xist RNA to leak out of the cell to where the immune system gets to see it. You still needed this environmental trigger to cause the whole thing to kick off," explained Chang, who is paid by the Howard Hughes Medical Institute, which also supports The Associated Press' Health and Science Department.
Beyond mice, researchers also examined blood samples from 100 patients—and uncovered autoantibodies targeting Xist-associated proteins that scientists hadn't previously linked to autoimmune disorders. A potential reason, Chang suggests: standard tests for autoimmunity were made using male cells.
Lots more research is necessary but the findings "might give us a shorter path to diagnosing patients that look clinically and immunologically quite different," said Penn's Wherry.
"You may have autoantibodies to Protein A and another patient may have autoantibodies to Proteins C and D," but knowing they're all part of the larger Xist complex allows doctors to better hunt disease patterns, he added. "Now we have at least one big part of the puzzle of biological context."
Stanford's Chang wonders if it may even be possible to one day interrupt the process.
"How does that go from RNA to abnormal cells, this will be a next step of the investigation."
Tracing the evolution of sign languages using computer modeling
by Bob Yirka , Phys.org
Example of recurrent change. Still images from video dictionary entries that illustrate the phonological pattern of thumb extension. Both signs are produced with four fingers extended, but the sign for "work" in New Zealand SL (left) is produced without thumb extension, whereas the sign for "work" in British SL (right) displays thumb extension. Credit: Science (2024). DOI: 10.1126/science.add7766 [From: www.spreadthesign.com].
An international team of linguistics experts has traced the origins of the most common modern sign languages using a computer model to compare them against one another. The research is published in the journal Science.
In this new effort, the research team noted that while studies have traced the linguistic history of written languages, little work has been done on the origin of sign languages. They state that there are more than 300 sign languages used by hearing-impaired people around the globe, and little is known about their origins or how they might have impacted one another.
Sign languages, like spoken and written languages, are unique to groups or cultures, with many corresponding to their written counterparts—there is a Spanish sign language, for example, and French, Spanish and Japanese.
For this new study, the research team sought to learn more about their origins by dissecting the way words in languages are formed using the hands. They first focused their efforts on 19 major sign languages, sorting words into what they describe as core vocabulary attributes—zeroing in on the hand shape for "tree," for example, as opposed to "oak tree." They then entered the core words into a database to conduct a computational analysis of the glossaries for all the languages under study.
As part of that analysis, the modeling took into account physical attributes used to form words and concepts, such as whether they were formed using one or two hands, handshape, hand location and movement of hands and arms. The researchers also programmed their model to conduct a phylogenetic analysis as part of the comparisons between languages to investigate shared traits or similarities in word expression
The research team was able to build family trees of sign languages, with a major split between European and Asian sign languages. They were also able to associate changes or additions to sign languages based on known historical events. For example, they determined that when leaders in France greatly expanded the country's deaf education system in the 18th century, French sign language matured and became a strong influence on other sign languages. The model also allowed the team to discover previously unknown associations, such as those between British and Western English sign language varieties.
More information: Natasha Abner et al, Computational phylogenetics reveal histories of sign languages, Science (2024). DOI: 10.1126/science.add7766
Oklahoma rattled by shallow 5.1 magnitude earthquake
FEBRUARY 3, 2024
Credit: Unsplash/CC0 Public Domain
A 5.1 magnitude earthquake shook an area near Oklahoma City late Friday, followed by smaller quakes during the next several hours, the U.S. Geological Survey reported.
No injuries were reported and damage appeared to be minimal, mostly items overturned or shaken from shelves inside homes, according to Lincoln County Deputy Emergency Management Director Charlotte Brown.
"Nothing significant ... nothing other than lots of scared people," Brown said.
The earthquake struck at 11:24 p.m. and was centered 8 kilometers (5 miles) northwest of Prague, Oklahoma, about 57 miles (92 kilometers) east of Oklahoma City, the agency said.
Residents across the state from Lawton to Enid to Tulsa reported feeling the shaking to the U.S.G.S.
The initial earthquake was followed by at least eight smaller temblors through Saturday morning, ranging in strength from magnitude 2.5 to 3.4, according to the geological survey.
The earthquake was shallow—just 3 kilometers (1.8 miles) deep, according to the USGS—and temblors that hit close to the surface can make the shaking more intense.
At least six earthquakes, including two greater than magnitude 4, were recorded near another Oklahoma City suburb in January. In April, a magnitude 4 earthquake was among a series of six that struck the central Oklahoma town of Carney, about 40 miles (64 kilometers) northeast of Oklahoma City.
A 5.7 magnitude earthquake struck Prague in 2011, about 60 miles (97 kilometers) south of the state's strongest recorded earthquake site in Pawnee, which registered a magnitude 5.8 in 2016.
Thousands of earthquakes have been recorded in Oklahoma in recent years, many linked to the underground injection of wastewater from oil and natural gas extraction, particularly in what is known as the Arbuckle formation that includes the area around Prague.
The epicenter of the Saturday earthquake was nearly the exact spot of the epicenter of the 2011 quake, according to Matt Skinner, spokesperson for the Oklahoma Corporation Commission, which regulates the oil and gas industry in the state.
"That was one of the early areas where action was taken" to limit the injection of wastewater, said Skinner.
"Disposal wells within 10 miles of the quake" must stop operating temporarily, Skinner said.
The corporation commission has directed several producers to close some injection wells and reduce the volumes in others as a result of the quakes.
Block model of a subduction zone with a section of the forearc removed, exposing the top of the downgoing plate. Dashed red lines are isotherms. Pink patches represent locations of accelerated footwall deformation by diffusive mass transfer (DMT). Strain rate in footwall increases on average from the top to the bottom of the seismogenic zone, where steady strain occurs that accommodates the plate rate. Credit: Science Advances (2024). DOI: 10.1126/sciadv.adi7279
Rocks once buried deep in ancient subduction zones—where tectonic plates collide—could help scientists make better predictions of how these zones behave during the years between major earthquakes, according to a research team from Penn State and Brown University.
Clues from rock formations in Alaska and Japan allowed the scientists to develop a new model to predict the pressure solution activity in subduction zones, the researchers reported in the journal Science Advances.
Sedimentary rocks comprise grains surrounded by water-containing pores. When rocks are squeezed together under great pressure, the grains dissolve at their boundaries into the water present in pores, forming pressure solution. This allows the rocks to deform, or change shape, influencing how the tectonic plates slide past each other.
"It's like when you go ice skating—the blade on the surface ends up melting the ice, which allows you to glide along," said corresponding author Donald Fisher, professor of geosciences at Penn State. "In rocks, what happens is quartz grains dissolve at stressed contacts and the dissolved material moves to cracks where it precipitates."
The world's most powerful earthquakes happen in subduction zones, where one tectonic plate slides beneath the other. When these plates become stuck together, stress builds in the crust of the Earth—like a rubber band being stretched. When enough stress builds up to overcome the friction holding the plates together—like a rubber band snapping—an earthquake occurs.
"We've shown that pressure solution is a fundamental process during the interseismic period in subduction zones," Fisher said. "The occurrence of this pressure solution can really affect the amount of elastic strain that accumulates in different parts of the seismogenic zone."
Pressure solution is difficult to explore in the laboratory because it typically occurs very slowly over thousands to millions of years, Fisher said. Speeding up the process in the lab requires higher temperatures, which produces other changes in rocks that impact the experiments.
The scientists instead turned to rocks that once experienced these tectonic pressures and were later brought to the surface by geological processes. The rocks show microscopic shears—or breaks caused by strain—that contain textures that provide evidence for pressure solution, the scientists said.
"This work allows us to test a flow law, or model, that describes the rate of pressure solution in ancient rocks that were once down at the plate boundary and have been exhumed to the surface," Fisher said. "And we can apply this to active margins that are moving today."
A previous study by another team of scientists linked stress the rocks experienced and strain rate—or how much they deformed. In the new work, Fisher and his colleague, Greg Hirth, professor at Brown University, created a more detailed model that considers factors like the rocks' grain size and solubility, or how much of the rock material can dissolve into liquid.
"We were able to parameterize the solubility as a function of temperature and pressure, in a practical way that hadn't been done before," Fisher said. "So now we can plug in numbers—different grain sizes, different temperatures, different pressures and get the strain rate out of that."
The results can help reveal where in the seismogenic layer—the range of depths at which most earthquakes occur—that strain is occurring.
The researchers applied their model to the Cascadia Subduction Zone, an active fault that runs from northern California to Canada and by major cities such as Portland, Oregon, Seattle and Vancouver, British Columbia.
The temperature along the plate boundary and the amount of strain built up is well studied there, and the results of their model match crustal movements based on satellite observations, the scientists said.
"Cascadia is a great example because it's late in the interseismic period—it's been 300 years since the last major earthquake," Fisher said. "We may experience one in our lifetime, which would be the biggest natural disaster that North America can anticipate in terms of the potential for shaking and resulting tsunami."
More information: Donald M. Fisher et al, A pressure solution flow law for the seismogenic zone: Application to Cascadia, Science Advances (2024). DOI: 10.1126/sciadv.adi7279
A type of plastic that can be shape-shifted using tempering
by Bob Yirka , Phys.org
Applications from a single feedstock. A, Batch of as-cast, dried N63. B, Freestanding film of N63. C, N6360 spoon and fork. D, Demonstration of N6360 as a rigid spoon to scoop peanut butter. E, Demonstration of N6360 as a rigid fork to pick up a piece of cheese. F, Demonstration of N63110 as a pressure-sensitive adhesive. G, Demonstration of N6360 immediately failing as an adhesive. Credit: Science (2024). DOI: 10.1126/science.adi5009
A team of molecular engineers have developed a type of plastic that can be shape-shifted using tempering. In their paper published in the journal Science the team, from the University of Chicago, with a colleagues from the US DEVCOM Army Research Laboratory, Aberdeen Proving Ground, the National Institutes of Standards and Technology and the NASA Glenn Research Center, describe how they made their plastic and how well it was able to shape shift when they applied various types of tempering.
McAllister and Julia Kalow, with Northwestern University, have published a Perspective piece in the same issue of Science outlining the work.
Over the past several years, it has become evident that the use of plastics in products is harmful to not only the environment but also human health—bits of plastic have been found in the soil, the atmosphere, the oceans, and the human body.
Consequently, scientists have begun looking for ways to reduce the amount of plastic that is created, used and dumped into the trash. In this new effort, the research team has created a type of plastic that can be converted to something new once its initial purpose has been exhausted—using tempering. A plastic bag holding food, for example, could be converted to a fork or spoon.
To allow for such shape-shifting, the researchers developed a type of plastic using a dynamic cross-linked approach that was based on the reversible addition of thiols to benzalcyanoacetates—a process known as a "Michael addition." The resulting plastic was of a type that could be modified by tempering, which is where a material is heated to a certain point, then chilled quickly. Tempering is most often associated with metalwork
The researchers found by that heating the plastic to temperatures ranging between 60°C and 110°C, then transferring it to a standard food freezer, they could create different objects from the same material based on a whim.
They created a spoon first, which they used to scoop peanut butter from a jar. They then used tempering to change the spoon to a fork, and then to an adhesive material capable of holding two panes of glass together. However, tests showed that there was a limit to the number of times the plastic could be changed, which was seven times. After that, it began to degrade.
More information: Nicholas R. Boynton et al, Accessing pluripotent materials through tempering of dynamic covalent polymer networks, Science (2024). DOI: 10.1126/science.adi5009
Haley P. McAllister et al, Plastics that lose their temper on demand, Science (2024). DOI: 10.1126/science.adn3980
