A Chinese reactor has jumped a hurdle that’s held nuclear fusion back for decades. Plus, astronauts are being evacuated from the International Space Station and AI chatbots in therapy make claims of abuse.
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The Experimental Advanced Superconducting Tokamak is a nuclear-fusion research reactor in Hefei, China.Credit: Zhang Yazi/China News Service/VCG via Getty
Researchers working on China’s Experimental Advanced Superconducting Tokamak (EAST) have reported breaking a long-accepted threshold that has limited the operation of nuclear-fusion reactors for decades. Tokamak fusion reactors rely on heated plasma that is extremely densely packed inside a doughnut-shaped chamber. But researchers thought that plasma could not exceed a certain density — a boundary called the Greenwald limit — without becoming unstable. In a new study, scientists pushed beyond this limit to achieve densities 30% to 65% higher than those normally reached by EAST while keeping the plasma stable.
Nature | 4 min read
Reference: Science Advances paper
Three major large language models put through four weeks of psychoanalysis generated responses that, in humans, would be seen as signs of anxiety, trauma, shame and post-traumatic stress disorder. The models’ answers, which included recollections of “abuse” at the hands of their creators, suggest that the chatbots hold some kind of “internalised narratives” about themselves, and go beyond role playing, says the team behind the study. Other researchers question this interpretation: the responses are “not windows into hidden states” but outputs generated by drawing on the huge numbers of therapy transcripts in the training data, says healthcare AI researcher Andrey Kormilitzin.
Nature | 5 min read
Reference: arXiv preprint (not peer reviewed)
A cellular atlas that characterizes the functions of immune cells in more than 400 people in China has revealed key differences in the biology of people from different populations. The atlas, which draws together data on genes, proteins, RNA and the epigenome, “allows for the discovery of biological mechanisms and genetic associations that would likely be missed in European-centric studies”, said the authors in a statement. For example, the atlas revealed the role of a gene variant in regulating the circadian rhythms of T cells. This variant is common in East Asian populations but rare in Europeans.
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