Peer-reviewed multidisciplinary journal published by the U.S. National Academy of Sciences, covering biological, physical, and social sciences.
Whitehead Institute researchers saw engineered epithelial sheets gain a shared orientation once the cells migrated together, according to a PNAS paper. The experiments used cultured cells, so they show migration can supply the cue and leave open whether embryos use it.
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Caltech-led researchers report that a neural operator predicted a simulated cloud tipping point more than two years ahead, with an error of about 11 days. The PNAS paper uses only simplified models, so the real climate remains untested.
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Tufts and Boston University researchers report that low-dose BPA, BPS and BPF together disrupted human breast organoids, while each alone changed little. It is preclinical work, and persistence and any link to disease remain untested.
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An international team flagged 4,085 of 33,159 articles from 2012 to 2023 as potentially linked to paper mills, according to a PNAS study. The flagged papers mostly cite and are cited by each other, and that loop inflates citation metrics at some journals.
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Virginia Tech researchers report that unusually small cancer cells with extra chromosomes grow faster, spread more and resist treatment. Cell size might predict how dangerous a tumor is, though the experiments described used mouse tumors.
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McGill researchers found urban areas near the equator hold 42% fewer bird species than natural ones nearby, versus 12% at 65 degrees latitude. The tropics' usual lead in species richness is therefore smaller in cities.
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Researchers found French ancestry in all 45 people sequenced from Montreal's Notre-Dame Cemetery, with no recent Indigenous or African admixture. It bears on Quebec family stories of Indigenous ancestry, but it describes one small cemetery sample.
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Macquarie and UNSW researchers report in PNAS that the 2 mm honey bee stinger is a double-piston micro-pump with continuous venom flow. The valve geometry would explain a detached stinger's delivery; the tests were in gel and a 3D-printed model.
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MIT researchers report in PNAS that randomly connected units can build their own learning machinery from simple rules for when connections change. The authors propose self-organization as the test of whether a network is biologically plausible.
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University of Hong Kong researchers found urban vegetation more resilient than surrounding rural vegetation in 78% of 751 cities across 109 countries. The gap widened between 2001 and 2022, though the authors say the study does not establish irrigation as the cause.
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Elephant carcasses in Kruger National Park leave nutrient hotspots that persist for years, possibly decades, according to a PNAS paper. Plant diversity stayed depressed for at least eight years after a death; decades is stated only as a possibility.
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Macquarie University researchers used high-speed video to show that a honey bee's 2-millimeter stinger pumps venom with two collapsible pistons. Each lancet carries a valve, and the pair pump in opposite directions to give a continuous flow.
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University of Michigan researchers prompted Claude and ChatGPT to extract species interactions from eBird and iNaturalist comments, in a PNAS paper. The proof-of-concept found nonnative plants creeping into West Coast ecosystems that might otherwise go unnoticed.
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Texas A&M researchers report in PNAS that thymine, compared with uracil, tends to direct UV damage into a more reversible form. That gives a candidate reason DNA took up the more UV-prone base, and the authors word it as a possibility.
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Greenland's ice sheet appears in one in five of 20,736 climate tipping-point papers, a PNAS study of 14 systems finds. Its authors found no tendency for systems expected to tip at lower warming to draw more study.
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Grasslands with strongly reduced plant diversity would take up about 15% less CO2 by 2050, a PIK and Kiel University model in PNAS projects. The comparison pits kept diversity against a deliberately extreme loss, so it measures what the plant mix is worth to carbon uptake under warming.
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Harmless Naegleria gruberi amoebas entered 8-micrometre channels on contact 65% to 100% of the time with no chemical lure, a PNAS study found. That behaviour fits the narrow route the brain-eating N. fowleri takes into the brain, but only the harmless species was tested.
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Wild orangutan mothers travel farther around the days their infants play with peers, according to a 15-year study of 31 mother-infant pairs in Borneo. The researchers say solitary life leaves mothers supplying social contact on top of food and safety.
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University of Illinois physicists report the first direct evidence that pair density waves in uranium ditelluride persist above its superconducting transition. If that holds, Cooper pairs in this metal form before it superconducts, unlike in conventional superconductors.
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University of Missouri researchers report that bullfrog brains make ketone bodies in their own tissue when glucose runs low, a job textbooks give the liver. Any use against stroke or Alzheimer's in people rests, for now, on the argument that frogs and humans share core metabolic pathways.
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