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After over a year of record-high global sea temperatures, the Atlantic is cooling off more quickly than ever recorded, which could impact weather around the world

Artificial intelligence (AI) has exploded in popularity as of late. But just like a human, it's hard to read an AI model's mind. Explainable AI (XAI) could help us do just that by providing justification for a model's decisions. And now, researchers are using XAI to scrutinize predictive AI models more closely, which could help make better antibiotics.

Some of the attractive hues of brightly colored, cloth-bound books from the Victorian era come from dyes that could pose a health risk to readers, collectors or librarians. The latest research on these 'poison books' used three techniques -- including one that hasn't previously been applied to books -- to assess dangerous dyes in a university collection and found some volumes had levels that might be unsafe.

Children born with certain heart defects undergo a series of invasive surgeries early in life. The first surgery includes implantation of a shunt to improve blood flow. However, as children grow, the shunt must be replaced to accommodate their changing bodies. Now, researchers report designing a shunt that expands when activated by light. This device could reduce the number of open-chest surgeries these children receive.

When a global pandemic forced previous a graduate student out of the lab and onto the computer, he found a world of difference hidden in the long-studied species of Botryoccocus braunii -- and discovered that it isn't one species at all, but three.

According to NASA’s Perseverance rover, ancient rocks in Jezero Crater formed in the presence of water. These sedimentary rocks are more than 3.5 billion years old and may predate the appearance of life on Earth. When and if these samples are returned to Earth, scientists hope to determine if they hold evidence of ancient Martian life.

In 2022, the Perseverance Rover worked its way along Jezero Crater’s western slope and sampled rocks from a feature called the ‘fan front.’ Scientists hypothesized that some of the rocks in this region were formed in the ancient lakebed when the crater was filled with water. Perseverance analyzed the rocks’ chemistry and captured images of their surroundings. Members of the Perseverance science team studied this data and have published their results.

“These rocks confirm the presence, at least temporarily, of habitable environments on Mars.”

Professor Tanja Bosak, MIT

Their work is titled “Astrobiological Potential of Rocks Acquired by the Perseverance Rover at a Sedimentary Fan Front in Jezero Crater, Mars.” It’s published in the journal AGU Advances, and the lead author is Tanja Bosak, professor of geobiology in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS).

“These rocks confirm the presence, at least temporarily, of habitable environments on Mars,” said lead author Bosak. “What we’ve found is that indeed there was a lot of water activity. For how long, we don’t know, but certainly for long enough to create these big sedimentary deposits.”

Perseverance collected seven samples from the fan front. Each of the samples is of a sedimentary rock, and some of them may predate life on Earth. “The samples include a sulphate- and clay-bearing mudstone and sandstone, a fluvial sandstone from a stratigraphically low position at the fan front, and a carbonate-bearing sandstone deposited above the sulphate-bearing strata,” the authors explain.

Sulphates and clays typically form in the presence of water, and so do carbonates. Depending on the types of sulphates, it reveals clues about the ancient water’s chemistry, temperature, and acidity. Carbonates are similar and can also reveal things about Mars’ atmosphere when they formed, like how much carbon dioxide it contained.

“The hydrated, sulphate-bearing mudstone has the highest potential to preserve organic matter and biosignatures, whereas the carbonate-bearing sandstones can be used to constrain when and for how long Jezero crater contained liquid water,” the authors explain.

While the samples were placed in sealed tubes for eventual return to Earth, Perseverance also abraded the rock next to each sample location, allowing the rover to analyze the mineral content of the rocks.

This image from the research article shows the rock cores acquired during the Fan Front Campaign. CacheCam images of the cores in their container tubes are on the left. Red symbols on the High-Resolution Imaging Experiment (HiRISE) map on the right show the locations of the sampled outcrops and the corresponding cores. Image Credit: Bosak et al. 2024

Mars rovers have found other rocks that were deposited by water, but none this old. These ancient Martian rocks are the oldest sedimentary rocks ever studied, and they likely formed when the Jezero Crater was a habitable lake. Because they’re sedimentary rocks, they could hold ancient organic matter. But that determination will have to wait until they make it safely to labs on Earth.

“These are the oldest rocks that may have been deposited by water, that we’ve ever laid hands or rover arms on,” said co-author Benjamin Weiss, the Robert R. Shrock Professor of Earth and Planetary Sciences at MIT. “That’s exciting, because it means these are the most promising rocks that may have preserved fossils, and signatures of life.”

(A) gives the local context for the Amalik outcrop, where two samples were taken. (B) shows the workspace after sampling and abrasion. The white arrow on the left shows where the Mageik sample was taken. The center arrow shows how the rock was fractured when the Shuyak core was sampled. The arrow on the right shows the Novarupta abrasion. (C) is a close-up of the abrasion patch. Image Credit: Bosak et al. 2024.

Most sedimentary rock has two components: grains, which are like the building blocks for sedimentary rock, and cement, which are mineral deposits that come along later and bind the grains together. Over time, pressure forces cement into the rock pores, filling them and creating solid rock in a process called lithification. The researchers think that both the grains and the cement in the fan front sedimentary rocks likely formed in aqueous environments. During lithification, organic matter from ancient life could’ve been trapped in the rock.

The fan front is a prime place to search for evidence of ancient life. “We found lots of minerals like carbonates, which are what make reefs on Earth,” Bosak says. “And it’s really an ideal material that can preserve fossils of microbial life.”

Though sulphates form in the presence of water, the water tends to be very salty, which isn’t necessarily great for life. But it could work out for the best because of salt’s preservative effect. If the brine was restricted to the lake bottom, life could’ve persisted in the upper portions of the ancient lake. When lifeforms died, they could’ve sunk to the bottom. In this case, the brine would’ve acted to preserve signs of ancient life.

“However salty it was, if there were any organics present, it’s like pickling something in salt,” Bosak says. “If there was life that fell into the salty layer, it would be very well-preserved.”

NASA’s Perseverance rover puts its robotic arm to work around a rocky outcrop called “Skinner Ridge” in Mars’ Jezero Crater. Composed of multiple images, this mosaic shows layered sedimentary rocks in the face of a cliff in the delta, as well as one of the locations where the rover abraded a circular patch to analyze a rock’s composition. Image Credit: NASA/JPL-Caltech/ASU/MSSS

It’s fairly well-established that Mars was once warm and wet. The next question is, did life ever exist there? To answer that, we need to find organic matter. But even that can be tricky since some organic matter can be produced geologically without life. The Curiosity Rover found organic carbon in Gale Crater, but scientists showed that UV fractionation is responsible.

Previously, Perseverance also found evidence of organic matter on the floor of Jezero Crater. Subsequent analysis showed that it could be matter that had no connection to life. This is a cautious reminder of the rovers’ limitations. Though they’re powerful, and it’s an amazing feat to have them roam around on another planet studying rocks, they can’t do the same science that’s possible in labs here on Earth.

That’s why the Mars Sample Return is so critical. Only by finally bringing pieces of Mars back to Earth can we fully understand the evidence that Perseverance is collecting.

“On Earth, once we have microscopes with nanometer-scale resolution, and various types of instruments that we cannot staff on one rover, then we can actually attempt to look for life,” Bosak says.

The post Ancient Rocks in Mars’ Jezero Crater Confirm Habitability appeared first on Universe Today.

Black holes are notoriously destructive to stars near them. Astronomers often see flashes representing the death throes of stars collapsing past the event horizon, a black hole they got too close to. However, in rare instances, a star isn’t wholly swallowed by its gigantic neighbor and is pulled into an orbit, causing a much slower death, which would probably be more painful if stars could feel anything. A new study using X-ray results from Chandra and some other instruments details a supermassive black hole at the center of a galaxy far, far away that is slowly devouring a star it has captured in an orbit, and it could teach them more about a variety of interest physical processes. 

The new paper is the latest in a series that goes back a few years. It started with the discovery of AT2018fyk, a “tidal disruption event” (TDE), back in 2018. A TDE is what astronomers see when a star is devoured by a black hole. AT2018fyk was originally captured by NASA’s Neutron star Interior Composition Explorer (NICER). Follow-up observations were completed by Chandra and XMM-Newton, ESA’s X-ray telescope. 

In a typical scenario, that would have been the end of the story – the star got eaten, emitted some exceptionally strong X and UV rays, and we captured them using our instrumentation 860 million light years away. However, astronomers noticed another spike in X-ray and UV emissions coming from the same black hole about two years later. 

Fraser discusses the world’s first direct image of black hole and why it’s important.

That second luminosity spike was likely caused by the star being partially devoured again as it was captured in a highly elliptical orbit around the black hole. Once every few years, it approaches closely enough that more of its material is ripped away, causing another TDE. But this time, scientists were ready and devised a hypothesis for when the TDE would end.

Their calculations pointed to August 2023, so they asked for observational time on Chandra. Sure enough, on August 14th, 2023, they saw a significant dimming of the emissions from the black hole. Either the star finally succumbed completely and was torn apart, or it made it out alive again and will continue its eccentric dance around its much bigger neighbor.

Either way, it definitely loses mass each time, as the second event is less luminous than the first. By that logic, the next one should be even less luminous if there is even a third event.

Video describing the new research around the black hole “snacking”.
Credit – Chandra X-ray Observatory YouTube Channel

The star at the heart of AT2018fyk might not have been alone originally. The researchers predicted that it was part of a binary star system, but its partner star was ejected once the pair were caught up in the gravitational well of the black hole. It is now traveling much faster away from that black hole and might have enough momentum to leave its galaxy entirely. 

Its partner was not so lucky. It remains to be seen if the star has enough material left for a third round of luminous burnoff. The system’s physical characteristics predict that the subsequent increase in brightness will happen between May and August of 2025 and would last for approximately two years, much longer than previous changes. Given the interest this system has now piqued and its ability to test theories about rare events like TDEs, the research team will likely be able to find some more observational time next year to check for the potential third snack of this exciting black hole.

Learn More:
Chandra – NASA Telescopes Work Out Black Hole’s Snack Schedule
Pasham et al. – A Potential Second Shutoff from AT2018fyk: An updated Orbital Ephemeris of the Surviving Star under the Repeating Partial Tidal Disruption Event Paradigm
UT – A Black Hole Consumed a Star and Released the Light of a Trillion Suns
UT – Supermassive Black Holes Grew by Consuming Gas and Entire Stars

Lead Image:
Artist’s depiction of a black hole pulling apart a star.
Credit – NASA/CXC

The post We Know When a Black Hole Will Have its Next Feast appeared first on Universe Today.

Detecting diseases early requires the rapid, continuous and convenient monitoring of vital biomarkers. Researchers have now developed a novel sensor that enables the continuous, and real-time detection of solid-state epidermal biomarkers, a new category of health indicators. The team's wearable, stretchable, hydrogel-based sensor overcomes the limitations of current methods that rely on biofluid samples, such as blood, urine and sweat. This makes it a promising alternative for wearable, continuous, and real-time health monitoring, facilitating the early detection of conditions such as cardiovascular diseases and stroke.

The design of streets and layout of buildings have an impact on a city's resilience in the face of increasingly severe floods brought on by climate change. Researchers look at buildings and other urban structures as physicists consider elements in complex material systems. With this insight, the researchers have developed a new approach to urban flood modelling and found their results helpful in analyzing city-to-city variations in flood risk globally.

Swiping through online videos to relieve boredom may actually make people more bored and less satisfied or engaged with the content, according to new research.

A new study found that using ChatGPT-4 to read medical notes from Emergency Department admissions to determine whether injured scooter and bicycle riders were wearing a helmet finds that AI can't yet do this reliably.

A view into how nanoscale building blocks can rearrange into different organized structures on command is now possible with an approach that combines an electron microscope, a small sample holder with microscopic channels, and computer simulations, according to a new study.

Two new studies are pointing the way toward round-the-clock personalized care for people with Parkinson's disease through an implanted device that can treat movement problems during the day and insomnia at night.

A new machine learning model can predict autism in young children from relatively limited information. The model can facilitate early detection of autism, which is important to provide the right support.

Up to 100,000 extraordinary species, from spiders and beetles to salamanders and fish, live in subterranean caves and cracks. They aren’t as safe down there as we thought

I’ve generally been avoiding the American news, but I know readers are following it, especially since the Democratic National Convention, whose conclusion is foregone, has started in Chicago. (I’m glad I’m not home, as there will be tons of protests and disruption. I had enough of that in 1968.)

So here’s a discussion thread about politics, or anything else you want to get off your chest. I’ll start it off with a headline from today’s NYT. I dare not even mention my own views any more, as I’ll be given a hiding for saying that I don’t want to vote for either Presidential candidate, and be told off for thereby helping Trump (a misguided view for sure).

Click on the link below to read, or find the article archived here. I’ll give an excerpt. Talk about the election, politics, or anything you want.

An excerpt:

When Hillary Clinton ran for president in 2016, she had more than 200 distinct policy proposals. Four years ago, Joseph R. Biden Jr. had a task force write a 110-page policy document for his White House bid.

Now, Vice President Kamala Harris does not have a policy page on her campaign website.

A last-minute campaign born of Mr. Biden’s depreciated political standing has so far been running mainly on Democratic good feelings and warmth toward Ms. Harris, drafting off legislation and proposed policies from the man she is hoping to succeed.

Democrats’ problem for most of this year appeared to be Mr. Biden himself, rather than his policies. For more than a year, as his poll numbers sank, his aides and loyalists insisted that his legislative record and priorities were viewed favorably by Americans and would ultimately carry him to another term.

Ms. Harris is now testing that original theory — but with a younger, more spirited messenger.

On policy, she has essentially cherry-picked the parts of the Biden agenda that voters like most while discarding elements like his “Bidenomics” branding on the economy. She has emphasized what allies call the “care economy”: child care, health care and drug prices, which directly affect voters’ lives.

The link to the whole article is above.  Didn’t Harris propose some kind of ban on high grocery prices?

As I said, you can talk about anything here, not just politics, but do not diss other commenters or your host, and BE CIVIL. (If you’re a newbie, I recommend reading the posting rules.

Have fun! I’m off to see the animals.

Male fireflies caught in an orb-weaver spider’s web start flashing in an unusual pattern, a deadly deception that seems to attract additional victims for the spider

The World Health Organization considers "gaming disorder" a condition, but researchers have now found that playing video games can boost well-being

Wildlife sightings were a bit slim in the bush this morning, but yesterday we had two great highlights: one was an invasion of our swimming pool area by a large breeding herd of nearly two dozen elephants, parched in the heat and eager to drink the water (which is unchlorinated and runs continuously over the pool’s far edge, where excess water fills a smaller pool from which the pachyderms drink). For that we didn’t have to leave the lodge.

The second was our third sighting of a leopard, as well as a new cat for me: the cheetah. We saw both cats within just an hour of setting off on our three-hour afternoon drive. All of these are documented below.

Before lunch every day, they set the tables and put out a plate of bread and rolls. I swear to Ceiling Cat that  the the vervet monkeys know when lunchtime is, and are aware of the tempting breadstuffs. This onr, whom I photographed before his Big Theft, ran into the dining room, and before anyone could stop her (I don’t know the sex, but without balls it seems to be a female), grabbed two pieces of bread, stuffing one in her mouth and holding the other in her hand. She then hied off and ran up a tree while the leader of a group of young Italian visitors, about to sit down at the table, yelled at the vervet. The leader then returned the plate to the kitchen, asking for a replacement (I wouldn’t have asked). The lucky primate then sat in the tree, stuffing herself with carbs.

After lunch the elephants began show up at the pool to drink, for the day was hot.The big one to the right is, I’m told, probably the matriarch of a breeding group that appears to be largely female (yes, elephants have, like all animals, only two sexes).

This gave one Italian visitor the chance to importune her boyfriend for the selfie of a lifetime:

The elephants started showing up individually or in small groups, so that eventually there were 21 of them, all vying to drink! They were of all sizes and ages, but so far as I can tell nearly all were female. Rosemary will, I think, do her best to verify or disconfirm this in the comments.

You can see the small runoff pool where most of the elephants drink, while the bigger one can reach their trunks into the larger and cleaner pool to the left (the regular swimming pool). It’s wonderful that the designers of this lodge provided for the elephants in this way:

All sizes were there; check out the little one under the matriarch. Its trunk could barely reach even the smaller pool.

Adult and infants get a drink of cool water:

What a sight! One of the employees told me that when it’s hot they often get this many elephants. The new human visitors to the lodge were stupefied at the sight.

As it was hot, some of them used the water to spray their backs, like this one. Many also fanned their blood-rich ears to cool off. And they clearly enjoyed playing in the water. One of them even blew bubbles into the small pool.

Within the first two hours of the afternoon drive yesterday, we saw two rare species of cat. The first was the same leopard we saw yesterday, now resting on the ground and apparently unperturbed by our vehicle:

Soon thereafter, our vehicle, which held eight plus local driver/guide Dan (two Italians, a family of four Frenchmen, and two Americans, including me and an astronomer from Baltimore), came upon a great species The French paterfamilias was good at spotting animals, and cried out late in the afternoon. He had seen something in the distance lying atop a large, defunct termite mound.

This is what it was:

Yep, a hard-to-find cheetah (Acinonyx jubatus), the world’s fastest land animal. How fast is it? As you can imagine, its flat-out speed is hard to measure, but it’s about a mile a minute, attaining this speed from a standstill in just a few seconds. Wikipedia says this (bolding is mine):

The cheetah is the world’s fastest land animal. Estimates of the maximum speed attained range from 80 to 128 km/h (50 to 80 mph).  A commonly quoted value is 112 km/h (70 mph), recorded in 1957, but this measurement is disputed.  In 2012, an 11-year-old cheetah from the Cincinnati Zoo set a world record by running 100 m (330 ft) in 5.95 seconds over a set run, recording a maximum speed of 98 km/h (61 mph).

Cheetahs equipped with GPS collars hunted at speeds during most of the chase much lower than the highest recorded speed; their run was interspersed with a few short bursts of a few seconds when they attained peak speeds. The average speed recorded during the high speed phase was 53.64 km/h (33.3 mph), or within the range 41.4–65.88 km/h (25.7–40.9 mph) including error. The highest recorded value was 93.24 km/h (57.9 mph)

. . . Cheetahs have subsequently been measured at running at a speed of 64 mph (103 km/h) as an average of three runs including in opposite direction, for a single individual, over a marked 200 m (220 yd) course, even starting the run 18 m (59 ft) behind the start line, starting the run already running on the course. Again dividing the distance by time, but this time to determine the maximum sustained speed, completing the runs in an average time of 7 seconds. Being a more accurate method of measurement, this test was made in 1965 but published in 1997. Subsequently, with GPS-IMU collars, running speed was measured for wild cheetahs during hunts with turns and maneuvers, and the maximum speed recorded was 58 mph (93 km/h) sustained for 1–2 seconds. The speed was obtained by dividing the length by the time between footfalls of a stride. Cheetahs can go from 0 to 97 km/h (0 to 60 mph) in less than 3 seconds.

I think the one we saw (below) is a female though I couldn’t see teats. But testes should be visible if it were a male. It is slim and graceful, much thinner than the leopard shown above. Its figure shows the need for speed:

More from Wikipedia:

The cheetah lives in three main social groups: females and their cubs, male “coalitions”, and solitary males. While females lead a nomadic life searching for prey in large home ranges, males are more sedentary and instead establish much smaller territories in areas with plentiful prey and access to females. The cheetah is active during the day, with peaks during dawn and dusk. It feeds on small- to medium-sized prey, mostly weighing under 40 kg (88 lb), and prefers medium-sized ungulates such as impala, springbok and Thomson’s gazelles. The cheetah typically stalks its prey within 60–100 m (200–330 ft) before charging towards it, trips it during the chase and bites its throat to suffocate it to death.

What a lovely cat!

Now birds. Rita and Martim, as well as Dan, identify the large woven nests below as the product of the red-billed buffalo weaver (Bubalornis niger), a denizen of dry savanna. Here are three colonial nests in one tree, a tree with bark partly removed by elephant scratching (reddish area near the ground).

Wikipedia describes the nests:

Red-billed buffalo weavers breed in colonies. The nests are composed of an enormous mass of thorny twigs. These twigs are divided into separate lodges (compartments), each with multiple egg chambers. Each chamber has a smaller nest, typically built by the female (unless they are part of a cooperative breeding colony). The smaller nest is composed of grass, leaves, and roots. The whole nest is usually found in a thorny tree or in a windmill near areas inhabited by humans.

Two ways of looking at zebras:

To our best knowledge, as I’ve reported several times, the stripes evolved mainly as a deterrent to biting flies, which simply don’t like landing on striped substrates. They don’t seem to be any kind of camouflage or a deterrent to predation by carnivores.

. . . and a blue wildebeest:

Now from this morning.  These holes appeared overnight in the packed-earth parking lot, and we were told they were made by termites. I’m not sure what’s going on here, but I have inquired of an entomologist:

It was chilly and partly cloudy this morning, and this is an unmanipulated shot of the bush, which really is a black-and-white view at sunrise:

Pickings were slim on this morning’s drive (this is why you must stay at a place like this for, I think, at least four days).  Dan livened things up by propping up the skull of a dead hippo (I showed the skeleton before). He said this hippo had been badly mauled in a battle with another hippo, and died from bleeding out:

We had a rare “sunupper” today (the coffee we get near the end of a morning’s drive): we got to get out of the car and drink our java right near wildlife: a trio of giraffe. They were quite curious about us and looked at our group of nine intently for a long time:

Now that is what I call a coffee break!

Nearby, concentric species of dung: the darker and smaller droppings from a zebra surrounded the larger brownish ones from an elephant:

Every day we see one ostrich, and it’s always crossing the road. One might think it was confecting a joke:

Finally, Dan spotted rhino tracks (see below) and spent a long time trying to find rhinos for us. I’d already seen one, but as the longest resident of the lodge now—I’ve been here four days—none of the others had. Dan always tries hard to find hard-to-see species, but despite his getting out of the car and combing the bush, we found nada except for these prints:

But I have two more 3-hour drives (the animals I have yet to see include the Cape buffalo—my last of the Big Five—a hippo out of water, and the lilac-breasted roller (Coracias caudatus), one of the world’s most beautiful birds. I’ve actually seen the species twice, but they always fly away before I can take a photo. Here’s a shot taken from Wikipedia, as I doubt I’ll be able to photograph one properly: they’re not uncommon, but are also skittish:

The caption says that this one was photographed at Kruger National Park, which is right next door.

Charles J. Sharp, CC BY-SA 4.0, via Wikimedia Commons

Astrologists claim to be able to use the motion of the planets and stars to make predictions about people's lives, but a detailed study has found that they rarely even agree with each other