alternative_right shares a report from ScienceAlert: At the Experimental Advanced Superconducting Tokamak (EAST), physicists successfully exceeded what is known as the Greenwald limit, a practical density boundary beyond which plasmas tend to violently destabilize, often damaging reactor components. For a long time, the Greenwald limit was accepted as a given and incorporated into fusion reactor engineering. The new work shows that precise control over how the plasma is created and interacts with the reactor walls can push it beyond this limit into what physicists call a 'density-free' regime. [...] A team led by physicists Ping Zhu of Huazhong University of Science and Technology and Ning Yan of the Chinese Academy of Sciences designed an experiment to take this theory further, based on a simple premise: that the density limit is strongly influenced by the initial plasma-wall interactions as the reactor starts up. In their experiment, the researchers wanted to see if they could deliberately steer the outcome of this interaction. They carefully controlled the pressure of the fuel gas during tokamak startup and added a burst of heating called electron cyclotron resonance heating. These changes altered how the plasma interacts with the tokamak walls through a cooler plasma boundary, which dramatically reduced the degree to which wall impurities entered the plasma. Under this regime, the researchers were able to reach densities up to about 65 percent higher than the tokamak's Greenwald limit. This doesn't mean that magnetically confined plasmas can now operate with no density limits whatsoever. However, it does show that the Greenwald limit is not a fundamental barrier and that tweaking operational processes could lead to more effective fusion reactors. The findings have been published in Science Advances.

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Researchers at Stanford University have created a programmable synthetic "skin" that can independently change color and texture, "a feat previously only available within the animal kingdom," reports the Register. From the report: The technique employs electron beams to write patterns and add optical layers that create color effects. When exposed to water, the film swells to reveal texture and colors independently, depending on which side of the material is exposed, according to a paper published in the scientific journal Nature this week. In an accompanying article, University of Stuttgart's Benjamin Renz and Na Liu said the researchers' "most striking achievement was a photonic skin in which color and texture could be independently controlled, mirroring the separate regulation... in octopuses." The research team used the polymer PEDOT:PSS, which can swell in water, as the basis for their material. Its reaction to water can be controlled by irradiating it with electrons, creating textures and patterns in the film. By adding thin layers of gold, the researchers turned surface texture into tunable optical effects. A single layer could be used to scatter light, giving the shiny metal a matte, textured appearance. To control color, a polymer film was sandwiched between two layers of gold, forming an optical cavity, which selectively reflects light.

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An anonymous reader quotes a report from NPR: [I]t turns out that some genius dogs can learn a brand new word, like the name of an unfamiliar toy, by just overhearing brief interactions between two people. What's more, these "gifted" dogs can learn the name of a new toy even if they first hear this word when the toy is out of sight -- as long as their favorite human is looking at the spot where the toy is hidden. That's according to a new study in the journal Science. "What we found in this study is that the dogs are using social communication. They're using these social cues to understand what the owners are talking about," says cognitive scientist Shany Dror of Eotvos Lorand University and the University of Veterinary Medicine, Vienna. "This tells us that the ability to use social information is actually something that humans probably had before they had language," she says, "and language was kind of hitchhiking on these social abilities." [...] "There's only a very small group of dogs that are able to learn this differentiation and then can learn that certain labels refer to specific objects," she says. "It's quite hard to train this and some dogs seem to just be able to do it." [...] To explore the various ways that these dogs are capable of learning new words, Dror and some colleagues conducted a study that involved two people interacting while their dog sat nearby and watched. One person would show the other a brand new toy and talk about it, with the toy's name embedded into sentences, such as "This is your armadillo. It has armadillo ears, little armadillo feet. It has a tail, like an armadillo tail." Even though none of this language was directed at the dogs, it turns out the super-learners registered the new toy's name and were later able to pick it out of a pile, at the owner's request. To do this, the dogs had to go into a separate room where the pile was located, so the humans couldn't give them any hints. Dror says that as she watched the dogs on camera from the other room, she was "honestly surprised" because they seemed to have so much confidence. "Sometimes they just immediately went to the new toy, knowing what they're supposed to do," she says. "Their performance was really, really high." She and her colleagues wondered if what mattered was the dog being able to see the toy while its name was said aloud, even if the words weren't explicitly directed at the dog. So they did another experiment that created a delay between the dog seeing a new toy and hearing its name. The dogs got to see the unfamiliar toy and then the owner dropped the toy in a bucket, so it was out of sight. Then the owner would talk to the dog, and mention the toy's name, while glancing down at the bucket. While this was more difficult for dogs, overall they still could use this information to learn the name of the toy and later retrieve it when asked. "This shows us how flexible they are able to learn," says Dror. "They can use different mechanisms and learn under different conditions."

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