Under Emperor Trajan, Rome fought the Dacian Wars (A.D. 101-102 and 105-106) against the denizens of the Dacian kingdom and its leader, Decebalus. Roman legions destroyed Dacia and annexed it as a new province. Trajan celebrated his victory in Rome, complete with a famous column that depicts details of the Dacian Wars.

In addition to the buckle, Moisei collected a decorative belt fitting and three small, round metal objects that probably belonged to the same belt. Moisei created a reconstruction of what the belt might have looked like before it was lost in the forest nearly two millennia ago.

But it's unclear who lost the belt. One of Moisei's theories is that the belt belonged to a horse-riding Sarmatian warrior originally from the Black Sea region. The Sarmatians were a group of tribes that lived outside the borders of the Roman Empire, in what are now central Ukraine, southern Russia and the Balkans. While some Sarmatian warriors fought against the incursion of the Roman Empire, others fought with Rome as mercenaries.

The metal belt fragments are part of a Roman provincial craft tradition, according to the statement, and they may have been obtained through trade or as a trophy of war. But Moisei is still studying the artifacts to confirm whether they were Sarmatian. Either way, the military belt provides new evidence of Roman military contact on the outskirts of the empire, and future work could help experts understand how the Romans interacted with the local Dacians during wartime.

From Augustus to Nero, see how much you know about ancient Rome's famous leaders with our Roman emperor quiz!

'> Colorful 1,800-year-old belt buckle discovered in a Ukrainian forest may have belonged to a nomadic equestrian warrior

Europe's ExoMars Trace Gas Orbiter (TGO) spacecraft spotted a possible signal of hydrogen chloride gas leaking from rifts in the region of Alba Mons, the largest volcano on Mars in terms of surface area. (Mars' famous Olympus Mons is the largest volcano in terms of height.) Scientists interpret this gas as emissions from hot magma below the regolith of Mars.

Although more research is required to confirm the emissions, the team suggested that Alba Mons may host an environment similar to hydrothermal vents on Earth, where life once likely arose and continues to thrive today.

The study, published in the journal Science Advances Wednesday (Nov. 4), is not the first to suggest that magma may be flowing on Mars; NASA's InSight lander interpreted its presence through seismic observations and modeling earlier this year. But the new findings are the strongest evidence yet of gases being released by dormant volcanoes on Mars, first study author Alexander Trokhimovskiy, at Russia's Space Research Institute, told Live Science.

"Our study offers a complementary and potentially independent line of evidence [of Martian magma]: Atmospheric observations that reveal a possible signature of gas release from a subsurface magmatic system," Trokhimovskiy wrote in an email.

Europe smelt it — but what dealt it?

TGO first detected hydrogen chloride gas in Mars' atmosphere in 2021, but scientists were hesitant to link it to volcanic activity. The gas appeared to be seasonal, its distribution was not localized at a possible volcanic region, and other signs of volcanic gases, like sulfur, were not present, study co-author Kevin Olson, a visiting researcher at the University of Oxford who studies Mars gases, told Live Science in a separate email.

Further work, however, suggested that the gas wasn't just popping up in the warmer spring and summer in Mars' southern hemisphere; it also appeared in the winter in the northern hemisphere, he noted.

"I managed to catch two observations from the start of northern winter in the first Mars year of our mission, and a single observation the next year," Olson said, adding that a year on Mars is closer to two years on Earth due to the planet's wider orbit. "These out-of-season measurements were close to one another in location and time in both years, which was rather surprising. We then set about creating a campaign of special, targeted measurements at this time and place."

That campaign lasted two Mars years — roughly four Earth years — and increased the likelihood that scientists are seeing "an injection" of hydrogen chloride into the atmosphere from volcano-adjacent vents, Olson said.

The scientists confirmed the unseasonal observations in the northern hemisphere, finding a "distinct and pronounced signal" that then diminishes and falls below the spacecraft's detection threshold. "This inconsistency is more suggestive of a puff of gas entering the atmosphere than of regular atmospheric chemistry," he said. "While the link remains a hypothesis, we have now seen this gas appear locally, and nowhere else, over four Mars years of observations."

Daniel Mège, also a co-author of the paper and a professor who studies planetary geology at the Polish Academy of Sciences, identified the fissures where the gas may be emerging. He said the complementary evidence from InSight (on the ground) and TGO (circling above) helps give the study weight: InSight spotted activity in the crust, while TGO detected the emissions in the atmosphere.

Although magma activity is not in itself a sign of life, Mège noted that Earth's first life-forms came from sites like hydrothermal zones, which have a similar confluence of materials and energy as the potential vents on Mars. But conditions would need to be favorable in that area for at least millions of years to allow life to form, he cautioned.

"If these requirements are met at local scale, at the scale of the seepage structures, then living organisms might wait for us to discover them," he told Live Science in an email. "But maintaining stable conditions over such a long period at a very local scale is not obvious."

What do you know about the Red Planet? Test your knowledge with our Mars quiz!

'> Scientists find the best evidence yet of potentially habitable volcanic vents on Mars Nicholas Jakubovics, an oral microbiologist at Newcastle University in the U.K. who was not involved in the study. "The idea that the toothbrush surface itself is actively doing something is really interesting."

The experimental brush has bristles made from polyvinylidene fluoride (PVDF), a plastic that generates electricity when bent; these types of energy-producing materials are called piezoelectric. As the bristles flex during brushing, they produce an electrical charge that then triggers chemical reactions in saliva and water. These reactions release reactive oxygen species (ROS), which are highly reactive molecules that can damage bacterial cells.

Even when the bristles are not being used to brush, they carry a faint surface charge that helps prevent bacteria from clinging to the brush head when the toothbrush isn't in use, the team reported Wednesday (Nov. 4) in the journal Science Advances.

In laboratory tests where the toothbrush was used on isolated germs, its electrified bristles killed more than half of the Streptococcus mutans bacteria present. These microbes contribute to tooth decay. By comparison, nylon bristles killed just 9% of the bacteria. They also reduced levels of Porphyromonas gingivalis, a bacterium linked to gum disease, by up to 78%, while nylon brushes reduced them by less than 8%.

When the researchers added an antioxidant — a compound that neutralizes ROS — the new toothbrush's antibacterial effect largely disappeared, highlighting that the ROS are likely the key to its effects.

The team also found that the activity of certain genes in both S. mutans and P. gingivalis fell after exposure to the electrified bristles. These genes are involved in making ATP-binding cassette (ABC) transporters — molecular pumps that help shuttle essential nutrients across bacterial cell membranes. The researchers suspect that disrupting this machinery makes it harder for these microbes to survive and cling to teeth.

But Jakubovics was not convinced by that part of the team's explanation. "ABC transporters transport all sorts of different things," he said, adding that the findings did not clearly show how changes in these genes affected the bacteria.

The researchers also tested the new brush against plaque biofilms — hardy communities of bacteria that stick together and cling to tooth surfaces. For the experiment, they grew human dental plaque on cow tooth enamel and found that the brush removed more than 99% of the biofilm, outperforming a regular nylon brush.

Finally, the team moved to humans, putting the brush to the test in 115 adults with gum inflammation or tooth decay. These study participants were randomly assigned to use either the new toothbrushes or traditional nylon-bristled brushes twice a day for three months. (The study didn't note whether participants noticed a difference in sensation when using the electrified brushes.)

By the end of the trial, the participants who used the electrified bristles had less plaque, less gum inflammation and less bleeding than the participants who used ordinary brushes. Plaque samples also showed that the people who used electrified brushes had lower levels of bacteria associated with oral disease and higher levels of beneficial bacteria, which have previously been reported to suppress harmful oral bacteria and support oral health.

The researchers think that the disease-linked bacteria may have relatively fragile cell membranes, making them more vulnerable to damage from ROS than the beneficial bacteria. That's a theory that requires further study, though, so it's not completely clear how selective the brush is against plaque-causing bacteria.

In a test of the toothbrush's durability, the PVDF bristles retained their structure and electrical properties over three months of simulated use. Lab-grown mouse cells repeatedly exposed to brush material showed no signs of damage, and brushing on cow tooth enamel did not increase surface roughness. However, these tests cannot establish whether repeated use of these brushes is safe for humans.

"We would want to make sure that it is safe on the tissues for long-term use," Jakubovics said. He noted that, in lab tests, bacteria are grown directly on the bristles and exposed to their electricity for hours, "whereas in reality, in the mouth, your bristle is only in contact with the tooth or oral tissue for a very short time."

The trial with humans provides some insight into how the brush works in real life, but it was relatively small. Larger studies will be needed to find out whether the toothbrush offers a meaningful advantage over conventional brushes. For now, Jakubovics sees the recent study as just a proof of concept; more information and more convincing clinical data are still needed, he emphasized.

This article is for informational purposes only and is not meant to offer medical advice.

'> This self-powered toothbrush makes electricity to kill cavity-causing bacteria

Although the Southern Taurids are a minor meteor shower that produces only a handful of "shooting stars" each hour, it occasionally features exceptionally bright meteors called fireballs, which can briefly light up the night sky. According to NASA, fireballs are meteors at least as bright as Venus.

The Southern Taurids are active for several weeks in fall and peak Oct. 14, but the American Meteor Society expects the "fireball swarm component" to peak around Nov. 4-5.

Meteors can streak across any part of the sky, but for this meteor shower, they appear to radiate from the constellation Taurus, which will rise in the eastern sky as night falls and climb higher as the night progresses. That makes the hours around midnight a good time to look for shooting stars. However, unlike major meteor showers such as the Perseids (which peak Aug. 12-13) and the Geminids (which peak Dec. 13-14), the Southern Taurids have a broad peak, so there's no need to be outside at an exact time.

The Southern Taurids are the first of two fireball-rich meteor showers to be visible this month. The Northern Taurids will peak overnight on Nov. 11-12, giving stargazers another chance to spot a fireball. Both meteor showers result from dust and debris left in the inner solar system by Comet 2P/Encke striking Earth's atmosphere.

Discovered in 1786, Encke is a massive comet, measuring 2.98 miles (4.8 kilometers) in diameter, according to NASA ‪—‬ around one-third the size of the object thought to have killed the nonavian dinosaurs. Encke orbits the sun every 3.3 years, one of the shortest known orbital periods of any comet in the solar system. Scientists theorize that Encke is one of many fragments of a giant comet that broke apart 20,000 to 30,000 years ago.

After the Southern and Northern Taurids, the next meteor shower will be the Leonids, which peak Nov. 17-18 and produce around 15 shooting stars per hour, and the Geminids, which peak Dec. 13-14 and can deliver up to 120 shooting stars per hour close to the peak.

It's best to watch meteor showers with the naked eye, but a good backyard telescope will serve you well in the months to come. As the long nights of winter kick off in the Northern Hemisphere, skywatching opportunities abound — including four consecutive supermoons from Nov. 2026 to Feb. 2027.

'> Southern Taurid meteor shower could bring fireballs ‪this week —‬ when and where to look