Researchers have identified a speed demon at the heart of the Milky Way. This fast-moving star may yield insights into the black hole parked at the center of our galaxy.

(Image credit: Max Planck Institute for Extraterrestrial Physics)

Nevada election officials have questioned the Trump administration’s claims that thousands of noncitizens are registered to vote in the state. Above, a poll worker stands in a polling location in Las Vegas during the state’s primary in June.

Narwhals are toothed whales, renowned for their distinctive straight, spiraling tusks, which many people in medieval times believed were the horns of unicorns and thus held magical healing properties. That belief was debunked long ago, but the tusks remain popular souvenirs in Canada and Greenland. And they still hold a fascination for scientists keen to learn more about their unusual structure. A new paper published in the journal Nature Communications reports that rather than one left-oriented spiral, narwhal tusks also have a second internal spiral oriented in the opposite direction.

Inuit legend holds that a woman was dragged into the ocean by a harpoon rope after the weapon had hit a narwhal and was transformed into the animal herself. Her hair, which she'd worn in a twisted knot, became the spiral tusk. The tusk is actually a canine tooth in the left upper jaw of male narwhals, pushing through the lip when the males reach two or three years of age and growing to lengths as long as 1.5 to 2 meters (just under 5 feet to 9 feet 10 inches). Some males may develop two long spiral tusks or, in rare cases, none at all.

There's a general consensus that these tusks most likely evolved via sexual selection as a form of social status. They clearly aren't crucial for survival, since the females usually don't develop the tusk—and if they do, the tusks are much smaller with fewer spirals—and yet typically live longer than the males. But the precise function of the tusk is still a matter of considerable debate.

Narwhals have been observed using them to stun small Arctic cod while hunting. It's possible they are used as weapons in fights, but this behavior hasn't been directly observed, although there have been narwhals found with tusks embedded in their bodies. The presence of several million nerve endings suggests that narwhals may be able to sense temperature or salinity changes in the water with their tusks.

A double helix

Scientists know that the tusk consistently twists in the left-handed direction and that it is composed of dentine covered by a thin layer of cementum encasing a central pulp chamber. The dentine and cementum, in turn, are made up of microscopic collagen fibrils mineralized with nanoparticles of hydroxyapatite. The macroscale spiral shape emerges somehow from how those fibrils organize themselves. That structure also determines the tusk's material properties. One question is whether the helical structure is also present at the micro- and nanoscale.

But nobody had mapped the interior structure in three dimensions at the atomic, nano, and macroscales. So the authors of this latest paper studied two male narwhal tusk and skull specimens by combining multiple imaging techniques: X-ray computed tomography, scanning X-ray diffraction, scanning small-angle X-ray scattering and tensor tomography, and bifringence microscopy. That required reserving time on three large synchrotrons in Sweden, Switzerland, and France. They also performed standard morphological measurements and conducted mechanical three-point bending tests.

The results showed that the collagen fibrils and hydroxyapatite nanoparticles orient themselves along the tusk's longitudinal axis, so there is a consistently high degree of anisotropy at all scales. But there are tiny systemic deviations at small angles in that orientation, which in turn create the twisted structure. While the cementum layer forms the known left-handed helix, the dentine forms a right-handed helix.

That double-helix structure is the secret to the tusk's remarkable stiffness and strength, with the flexible fibers and stiff mineral matrix enabling the tusk to withstand strong forces, like bending and twisting without cracking. It also allows the narwhal tusk to grow straight, unlike, say, an elephant's curved tusk. The team also noted a finer underlying microstructure in the cementum of collagen fiber bundles radially extending outward, which they plan to study further using micro- and nano-beam experiments.

“Since whales can live for up to 80 years, their teeth form a kind of historical record of changing environmental conditions throughout the animal’s lifetime," said co-author Henrik Birkedal of Aarhus University in Denmark. "And because the North Atlantic is currently undergoing very rapid changes, it is obvious to investigate whether we can trace these changes in the hard tissue of the narwhal tusk. That is what we are now working on."

DOI: Nature Communications, 2026. 10.1038/s41467-026-75689-z  (About DOIs).

Read full article

Comments

Russian tanks have entered battle for the first time with a new active protection system designed to shoot down incoming drones. But the technology’s recent combat debut in Ukraine met with only limited success—Ukrainian drones still destroyed the Russian armored vehicles by attacking in overwhelming numbers.

The first documented battlefield appearance of the Arena-M active protection system took place when Russian forces launched a company-size assault with tanks and other armored vehicles in the Donetsk Oblast of eastern Ukraine on July 22. The Ukrainian defenders repelled the attack and posted video footage of their kamikaze drone strikes destroying at least seven T-72B3A tanks, including some that carried the Arena-M system, according to Euromaidan Press.

However, Ukrainian soldiers also described the Russian Arena-M system successfully shooting down some incoming drones, according to the journalists Dmytro Putiata and Rob Lee. The Ukrainians reported requiring between 15 and 20 drones to finish off each tank.

The incident “demonstrated that the Russian military is learning and is experimenting in how to employ armor on a drone-saturated battlefield,” Lee wrote on X. “The Arena-M [active protection system] demonstrated effectiveness and will likely be improved.”

This development comes more than four years after Russia launched its full-scale invasion of Ukraine in February 2022, as mass armored assaults have become increasingly scarce on the modern battlefield dominated by drone warfare. It’s part of an ongoing arms race where many militaries are struggling to figure out how to protect the weakest points of their expensive main battle tanks and other armored vehicles against swarms of cheap drones.

The Russian military has previously tried adding more physical armor in the form of “cope cages” welded or bolted onto tanks and other vehicles, which inspired the Ukrainian military to do the same. Russian forces even made “turtle tanks” covered in porcupine-style metal spikes and other improvised armor, although the extra weight and encumbrance of such add-ons have often limited both tank mobility and the use of their main guns.

Even up-armored vehicles attempting to enter the drone kill zone usually get destroyed, which is why mechanized assaults have mostly disappeared from the current battlefields in Ukraine in favor of infiltration tactics using small groups of soldiers. Russia’s battlefield deployment of the Arena-M aimed to change that.

The limitations of Arena-M

The Arena-M represents the latest version of the Arena system originally developed in the Soviet era. The technology uses radar to detect incoming rocket-propelled grenades and anti-tank missiles so that it can launch its own projectiles to intercept the incoming warheads.

The Ukrainian news publication Militarnyi reported that Russian engineers have been working to equip their tanks with the Arena-M system since 2019 and that live-fire tests were already being conducted in 2021. However, Militarnyi also highlighted reports suggesting Russia was struggling to adapt the Arena-M system to detect and destroy small drones, because the latter can fly more slowly and in more unpredictable ways than incoming missiles or rockets fired directly at tanks.

Having just a dozen countermunitions for interceptions also proved inadequate in the face of large numbers of Ukrainian drones. Remotely piloted Ukrainian drones capable of disabling or destroying armored vehicles through kamikaze attacks can cost as little as $400 each—so it’s still a very cost-effective trade for Ukrainian drone operators even if they have to use more than 12 drones to take out an armored vehicle costing millions of dollars.

“The Arena-M system, by itself, likely will not be an effective countermeasure to Ukrainian [first-person view drones] alone, as the system can be overwhelmed and only increases the cost and effort required of Ukrainian forces defending against the Russian mechanized assault,” wrote the Institute for the Study of War in an August 9 update on the war in Ukraine.

Pro-Kremlin Russian bloggers apparently acknowledged the Arena-M system's current limitations and called for additional defenses to be integrated to provide tanks with layered air defense against drones. However, tanks and other armored vehicles still face additional battlefield threats beyond drones in the so-called kill zone, including crewed anti-tank weapons, landmines, and artillery.

For now, the Russian military may be considering increasing the number of Arena-M counter munitions to intercept incoming drones and other projectiles. But as Euromaidan Press explained, space constraints for the turret-mounted projectile launchers could ultimately limit that approach.

Concerns beyond the war in Ukraine

The limitations of active protection systems against drones have also appeared beyond the battlefields in Ukraine during the US-Israeli war against Iran. When the Israeli military sent troops into Lebanon to fight the Iranian-backed faction Hezbollah, the Israeli Merkava 4 tanks came equipped with Trophy active protection systems developed by Israel’s Rafael Advanced Defense Systems.

But Hezbollah militants published multiple videos showing their small quadcopter drones loaded with explosives striking Israeli tanks that had Trophy systems still loaded with countermunitions, according to the Ukrainian media company Defense Express. Such videos implied that the Trophy system had difficulty detecting incoming small drones.

Making matters worse for the Israeli military, Hezbollah deployed drones that are immune to radio signal jamming because they are connected to human operators by miles of fiber optic cables. That battlefield innovation first came out of the war in Ukraine and became a crucial part of Hezbollah’s arsenal as the faction ramped up its asymmetric campaign against Israel between March and June 2026, according to the Institute for the Study of War.

Although it’s unclear how many Israeli tanks were damaged or knocked out by Hezbollah’s drones, such drone attacks became the top threat for the Israeli military in Lebanon and accounted for the majority of deaths among Israeli soldiers after a temporary ceasefire went into effect in April, The Wall Street Journal reported.

Despite uncertainty about the Trophy active protection system’s performance, multiple European countries have been buying the Trophy system in an attempt to better protect their tanks against the threat of drones. The EuroTrophy joint venture expects to equip 400 European Leopard tanks with the system, according to Breaking Defense.

The US military has already equipped several hundred M1 Abrams tanks with the Trophy system in recent years. But it’s clear that the United States and many other countries are still sorting out the best way to deploy tanks on drone-dominated battlefields. During the Combined Resolve military exercise held in Germany this year, Ukrainian drone operators wiped out an entire brigade of US Army tanks and armored vehicles.

Read full article

Comments

Rising costs, slowing tax revenue and a sluggish economy have saddled some of Texas’ biggest cities with multimillion-dollar deficits.

Marcus Martin, center, hugs Austin Police Department Officer Steven Creamer, left, on Thursday, Aug. 6, 2026. Officer Edward Soltys is at right. Officers Creamer and Soltys are part of No Wrong Door, a new initiative seeking to better help some of Austin's most vulnerable. Officers call this process a "warm hand-off," which offers the participant a continuity of care.