Phys.org

Red, yellow, green and blue may arise because the natural world has a restricted color palette that is simplest to encode with four opponent hues. The theory offers a possible resolution between three cone types in the eye and the four “pure” colors people perceive, while the full neural basis remains unresolved.

Himalayan “mad honey” can send heart rate to life-threatening lows after just a few tablespoons, and it is now being sold worldwide online. Poisonings cluster in spring, when toxin levels are highest, but the exact harmful dose still varies by batch, season and location.

Very weak far-infrared radiation can switch magic-angle twisted bilayer graphene from a correlated insulator to a metallic state. In this case, absorbed light heats the electrons while the crystal lattice remains cold, and even a slight electron-temperature increase is enough to melt the fragile insulating phase. The result points to a controllable electronic transition in a part of the spectrum that remains difficult to detect.

JWST infrared images revealed four close pairs of “Little Red Dots” from 12.5–12.8 billion years ago. Their separations span only a few thousand to a few tens of thousands of light-years, hinting that some rapidly growing early black holes may have been on the path to merging.

A new chemical editing method swaps a single atom to convert isoxazoles into pyrroles without changing the rest of the molecule. The process can run in the same flask from start to finish and takes one to two days, making it simpler, faster, and more cost-effective than previous routes. It does not work on every variation.

Air conditioning cut U.S. heat-attributable mortality by 57%, saving more than 5,000 lives a year across the contiguous U.S. from 2010 to 2020. But the protection leveled off once use passed a certain point, and risk still increased on days of extreme heat.

About 21% of surveyed students in grades 4 to 12 said they had used an AI chatbot for emotional support or relationship advice. That use was linked to greater loneliness, a lower sense of mattering, and a 26% higher prevalence of clinical-level emotional difficulties after accounting for other factors. The cross-sectional data show association, not whether distress drives youth to AI or whether AI use might make distress worse.

Plastic was detected in more than 71% of southern giant petrel chicks, and even small amounts were associated with physiological changes during development. The clearest signals appeared around 1 month old and involved nutrition, metabolism, liver and muscle function, and immune response. By about 3 months old, most changes had weakened or disappeared, but whether chicks compensated as they grew or exposure and response operate on different timescales remains unresolved.

PEC ion channels in chloroplasts appear to connect rapid calcium signaling with jasmonic-acid defense in plants. After herbivore or pathogen attack, jasmonic acid synthesis increases PEC production within hours, and elevated levels persist for several days. If stress recurs, this may help trigger a stronger chloroplast calcium signal and a faster, more sustained defense response, including increased resistance to Botrytis cinerea.

Multicellular cyanobacteria appear to regulate their cell-to-cell connecting structures through calcium signals, echoing a core feature of communication in human cells. A calcium-binding protein found only in these bacteria functioned as a calcium buffer, and mutant cells lacking it had significantly fewer connecting structures. The work suggests this cellular principle may be far older than assumed.