PNAS Nexus

@pnasnexus.org

Discover groundbreaking news and research from PNAS Nexus, the sibling journal to @pnas.org - both official research journals of the U.S. National Academy of Sciences. Visit www.pnasnexus.org for more information.

When air quality is categorized as “Hazardous” or “Very Unhealthy” in urban China, usage spikes on the Ant Forest program embedded in the Alipay app. Ant Forest offers to plant trees for users in exchange for actions that reduce climate emissions. In PNAS Nexus: https://ow.ly/w1ki50ZXbYP

Photo of a person interacting with a phone. Stock photo.

Researchers surveyed 117 US Catholics four times during the 2025 papal conclave to study how shared emotion and group identity evolve during live-broadcast rituals. Collective enthusiasm peaked at the “Habemus Papam” announcement. In PNAS Nexus: https://ow.ly/r0J850ZWW0W

Newly elected Pope Leo XIV, formerly American Cardinal Robert Francis Prevost, appears on the central balcony of Saint Peter's Basilica. Stock photo.

A study in the UK finds that when researching controversial topics such as climate change, immigration, criminal justice, or COVID-19 policy, AI chatbots may perform on par with a self-directed Google search in terms of accuracy. In PNAS Nexus: https://ow.ly/Rpfp50ZWW0F

A person chats with an LLM using their phone. Stock photo.

More than 41,000 people played a quiz game about famous people. The data show that people are about 10 percentage points more likely to get questions right when asked about a person from their own country rather than from a foreign country. In PNAS Nexus: https://ow.ly/3on850ZWqz9

Bernardo O’Higgins is well known in Chile but not elsewhere in the world. O’Higgins was a military leader during Chile’s independence war. Portrait of Bernardo O’Higgins holding the Chilean Constitution by José Gil de Castro.

Computational language analysis helps explain why the book Bushido: The Soul of Japan was so popular among Western audiences. The study sheds light on how cultural traditions can reach new societies without losing their core meanings. In PNAS Nexus: https://ow.ly/UynW50ZV50L

Front cover of Bushido: The Soul of Japan by Inazō Nitobe. English-language version. Hearn 92.40.10, Houghton Library, Harvard University.

Can complex networks be modeled with less computational work? Researchers developed HierX to efficiently model distance-decay potential fields, using Great Britain’s road network as a test case. In PNAS Nexus: https://ow.ly/cS3O50ZUzea

HierX: Fast multiscale distance-decay interaction on million-node networks

Abstract. Many models across the sciences require global distance-decay interactions on large sparse networks. Gravity models, accessibility measures, spat

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Researchers presented 21 LLMs with ethical dilemmas to explore their social norms when interacting with people who do not cooperate. Differences between models could steer people, and society, in more or less cooperative directions. In PNAS Nexus: https://ow.ly/Ujkf50ZU2a1

Photo illustration of the concept of AI ethics.

An analysis of two of the 14 remaining cubes of uranium from the German WWII nuclear project, along with historical records, reveals that the Nazis wouldn’t have been able to create a working bomb with the materials available to them. In PNAS Nexus: https://ow.ly/KVNO50ZU1Sa

A cube of natural uranium from the German nuclear project.
CREDIT: John T. Consoli, University of Maryland College Park, College Park, MD.

A study fails to find a link between masculine-looking faces and self-reported aggressiveness in 16 populations from South Asia and Cabo Verde, challenging the idea that aggressive disposition is biologically encoded in sexually dimorphic facial structure. In PNAS Nexus: https://ow.ly/9cHL50ZSN6m

A group of friends in Himachal Pradesh, India, one of the study locations. Stock photo.
CREDIT: Sumit.Kumar.99

Smoking appears to be more deadly in recent decades. A study uncovers the reason for the trend: smokers are, on average, older than they once were, due to cultural changes that have reduced the number of young people taking up the habit. In PNAS Nexus: https://ow.ly/4Jkm50ZSkza

Close-up of an elderly person smoking. Stock photo.