PNAS nexus最新文献

{"title":"Adaptive human behavior and delays in information availability autonomously modulate epidemic waves.","authors":"Md Shahriar Mahmud, Solomon Eshun, Baltazar Espinoza, Claus Kadelka","doi":"10.1093/pnasnexus/pgaf145","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgaf145","url":null,"abstract":"<p><p>The recurrence of epidemic waves has been a hallmark of infectious disease outbreaks. Repeated surges in infections pose significant challenges to public health systems, yet the mechanisms that drive these waves remain insufficiently understood. Most prior models attribute epidemic waves to exogenous factors, such as transmission seasonality, viral mutations, or implementation of public health interventions. We show that epidemic waves can emerge autonomously from the feedback loop between infection dynamics and human behavior. Our results are based on a behavioral framework in which individuals continuously adjust their level of risk mitigation subject to their perceived risk of infection, which depends on information availability and disease severity. We show that delayed behavioral responses alone can lead to the emergence of multiple epidemic waves. The magnitude and frequency of these waves depend on the interplay between behavioral factors (delay, severity, and sensitivity of responses) and disease factors (transmission and recovery rates). Notably, if the response is either too prompt or excessively delayed, multiple waves cannot emerge. Our results further align with previous observations that adaptive human behavior can produce nonmonotonic final epidemic sizes, shaped by the trade-offs between various biological and behavioral factors-namely, risk sensitivity, response stringency, and disease generation time. Interestingly, we found that the minimal final epidemic size occurs on regimes that exhibit a few damped oscillations. Altogether, our results emphasize the importance of integrating social and operational factors into infectious disease models, in order to capture the joint evolution of adaptive behavioral responses and epidemic dynamics.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf145"},"PeriodicalIF":2.2,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12107549/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144163786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence from counterfactual tasks supports emergent analogical reasoning in large language models.","authors":"Taylor W Webb, Keith J Holyoak, Hongjing Lu","doi":"10.1093/pnasnexus/pgaf135","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgaf135","url":null,"abstract":"<p><p>A major debate has recently arisen concerning whether large language models (LLMs) have developed an emergent capacity for analogical reasoning. While some recent work has highlighted the strong zero-shot performance of these systems on a range of text-based analogy tasks, often rivaling human performance, other work has challenged these conclusions, citing evidence from so-called \"counterfactual\" tasks-tasks that are modified so as to decrease similarity with materials that may have been present in the language models' training data. Here, we report evidence that language models are also capable of generalizing to these new counterfactual task variants when they are augmented with the ability to write and execute code. The results further corroborate the emergence of a capacity for analogical reasoning in LLMs and argue against claims that this capacity depends on simple mimicry of the training data.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf135"},"PeriodicalIF":2.2,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12107539/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144163898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Desiccated desert locust embryos reserve yolk as a \"lunch box\" for posthatching survival.","authors":"Koutaro Ould Maeno, Cyril Piou, Nicolas Leménager, Sidi Ould Ely, Mohamed Abdallahi Ould Babah Ebbe, Ahmed Salem Benahi, Mohamed El Hacen Jaavar","doi":"10.1093/pnasnexus/pgaf132","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgaf132","url":null,"abstract":"<p><p>Oviparous animals often prioritize the allocation of reproductive resources to egg size over clutch size, but the impact of this maternal investment on the allocation of embryonic yolks and its ecological functions is poorly understood. We investigated how desert locust embryos allocate yolk for survival energy after hatching, rather than embryonic somatic growth depending on egg size in response to desiccation stress. Crowd-reared females (gregarious phase) produced significantly larger progeny with higher tolerance to starvation than females reared in isolation (solitarious phase). Abnormally small hatchlings with residual yolk in their gut emerged from small and large eggs when exposed to desiccation. In particular, these small hatchlings of desiccated eggs survived significantly longer under starvation than those of wet ones, with larger eggs providing even greater survival benefits. Physiological analysis showed that hatchlings from desiccated eggs showed a trade-off by reserving more lipids without somatic growth than those from normal eggs. Desiccation could be a reliable signal for embryos to predict future poor vegetation, and reserved energy could increase the chance of accessing food after hatching. Our results underscore adaptive plasticity in maternal and embryonic resource allocation in desert locusts in response to unpredictably variable semi-arid habitats.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf132"},"PeriodicalIF":2.2,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12107552/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144163852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Marine ecosystem services and natural capital in China: Opportunities for improved understanding, valuing, and policy.","authors":"Laurence J McCook, Lyutong Cai, Chung Wing Yeung, Shang Chen, Zhiyun Ouyang, Put Ang, Michael Bordt, Ling Cao, Zhu Chen, Baolong Han, Hui Huang, Xinming Lei, Jiansheng Lian, Feixue Li, Guifang Xue, Peng Zhao","doi":"10.1093/pnasnexus/pgaf110","DOIUrl":"10.1093/pnasnexus/pgaf110","url":null,"abstract":"<p><p>This paper reviews the context and prospects for markedly improved sustainability of marine ecosystems and resources in China, based on accounting of marine ecosystem services and natural capital along with supporting policy and governance frameworks, in turn based on existing approaches in China's terrestrial social-ecological systems. Such integrated accounting, policy, and governance would provide a unique, novel, and innovative approach to regional-scale, sustainable ocean management. China is uniquely placed to implement such accountability, given the extensive adoption of accountability in terrestrial landscapes and the strong commitment to \"ecological civilization\" at the highest levels of national policy. Specifically, the paper outlines: The current, seriously degraded state of marine ecosystems and resources in China, largely due to economic drivers that ignore the valuable economic services provided by healthy marine ecosystems;The critical context of, and high-level commitment to, China's considerable development of environmental accounting, implementation and governance frameworks in terrestrial landscapes;Existing approaches for assessing marine natural capital in China, and the relationships between them;Currently available assessments;Current governance arrangements for marine ecosystem management in China.The paper then provides a potential implementation pathway for a system of standardised, nationally integrated, provincially-implemented marine environmental accounts, policy and governance, adapted from existing terrestrial arrangements. Such accounting, if embedded in rigorous governance and policy structures to drive real-world implementation, could generate a major improvement in sustainability of China's marine ecosystems. Given the extent of China's marine jurisdiction, and severity of ongoing degradation, such improvement could have enormous environmental and economic benefits within China, and at a global scale.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf110"},"PeriodicalIF":2.2,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12090196/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144112906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neurosymbolic AI as an antithesis to scaling laws.","authors":"Alvaro Velasquez, Neel Bhatt, Ufuk Topcu, Zhangyang Wang, Katia Sycara, Simon Stepputtis, Sandeep Neema, Gautam Vallabha","doi":"10.1093/pnasnexus/pgaf117","DOIUrl":"10.1093/pnasnexus/pgaf117","url":null,"abstract":"<p><p>The recent progress in machine learning has shifted the trends in artificial intelligence (AI) toward an overreliance on increasing amounts of data, computing power, and model parameters. These trends have resulted in success, but have also created a monolithic perspective for AI, increased the barriers to entry outside of large tech companies, and raised concerns about computational sustainability. Neurosymbolic AI is a growing area that promotes methodological heterogeneity and aims to push the frontiers of AI through affordable data and computing power.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf117"},"PeriodicalIF":2.2,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12084822/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144112913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Larger brains and relatively smaller cerebella in Asian elephants compared with African savanna elephants.","authors":"Malav Shah, Olivia Heise, Peter Buss, Lin-Mari de Klerk-Lorist, Stefan Hetzer, John-Dylan Haynes, Thomas Hildebrandt, Michael Brecht","doi":"10.1093/pnasnexus/pgaf141","DOIUrl":"10.1093/pnasnexus/pgaf141","url":null,"abstract":"<p><p>Elephants are the largest terrestrial animals, but our knowledge of their brains is limited. We studied brain size, proportions, and development in Asian (<i>Elephas maximus</i>) and African savanna (<i>Loxodonta africana</i>) elephants. Specifically, we weighed, photographed, and analyzed postmortem magnetic resonance scans of elephant brains in addition to collecting elephant brain data from the literature. Despite their smaller body size, adult Asian female elephants have substantially and significantly heavier brains (mean 5,346 ± 916 g SD) than adult African savanna female elephants (mean 4,417 ± 593 g SD). In line with their larger body size, adult African savanna male elephants (mean 5,603 ± 1,159 g SD) have significantly heavier brains than African female elephants; the brain weight of the adult male Asian elephant remains unclear. Elephant brain weight increases ∼3-fold postnatally. This postnatal increase is similar to that of the human brain but is larger than that seen in nonhuman primates. Asian elephants likely have more cerebral cortical gray matter than African ones; their cerebellum is relatively smaller (19.1% of total brain weight) than in African elephants (22.3%). Our data indicate a higher degree of encephalization in Asian than in African savanna elephants. The massive postnatal brain growth of elephants is likely related to prolonged adolescence and the important role of experience in elephant life history.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf141"},"PeriodicalIF":2.2,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12089752/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144113003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Perceived legitimacy of layperson and expert content moderators.","authors":"Cameron Martel, Adam J Berinsky, David G Rand, Amy X Zhang, Paul Resnick","doi":"10.1093/pnasnexus/pgaf111","DOIUrl":"10.1093/pnasnexus/pgaf111","url":null,"abstract":"<p><p>Content moderation is a critical aspect of platform governance on social media and of particular relevance to addressing the belief in and spread of misinformation. However, current content moderation practices have been criticized as unjust. This raises an important question-who do Americans want deciding whether online content is harmfully misleading? We conducted a nationally representative survey experiment (<i>n</i> = 3,000) in which US participants evaluated the legitimacy of hypothetical content moderation juries tasked with evaluating whether online content was harmfully misleading. These moderation juries varied on whether they were described as consisting of experts (e.g. domain experts), laypeople (e.g. social media users), or nonjuries (e.g. computer algorithm). We also randomized features of jury composition (size and necessary qualifications) and whether juries engaged in discussion during content evaluation. Overall, participants evaluated expert juries as more legitimate than layperson juries or a computer algorithm. However, modifying layperson jury features helped increase legitimacy perceptions-nationally representative or politically balanced composition enhanced legitimacy, as did increased size, individual juror knowledge qualifications, and enabling juror discussion. Maximally legitimate layperson juries were comparably legitimate with expert panels. Republicans perceived experts as less legitimate compared with Democrats, but still more legitimate than baseline layperson juries. Conversely, larger lay juries with news knowledge qualifications who engaged in discussion were perceived as more legitimate across the political spectrum. Our findings shed light on the foundations of institutional legitimacy in content moderation and have implications for the design of online moderation systems.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf111"},"PeriodicalIF":2.2,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12063528/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144112914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exposure to green space is associated with higher skin microbiota species richness in children.","authors":"Thessa Van Pee, Hanne Croons, Esmée Bijnens, Doris Vandeputte, Eleni Renaers, Hanne Sleurs, Lore Verheyen, Nick Giesberts, Maartje Vangeneugden, Leen Rasking, Michelle Plusquin, Janneke Hogervorst, Tim S Nawrot","doi":"10.1093/pnasnexus/pgaf115","DOIUrl":"10.1093/pnasnexus/pgaf115","url":null,"abstract":"<p><p>Skin is the exterior interface of the human body with the environment and harbors millions of microorganisms crucial for skin health. Associations between early-life green space exposure and the skin microbiome of children remain unstudied. Skin swabs were collected from 402 children (4-12 years old) enrolled in the ENVIR<i>ON</i>AGE birth cohort. Skin alpha diversity indices and the relative abundance at family and species levels were determined using 16S rRNA gene HiFi amplicon sequencing. Total green, high-growing green, and low-growing green were estimated in several radii around their current residential and school address based on high-resolution land cover data. Multiple linear regression models between green-space indices and skin microbiome alpha diversity indices were adjusted for sex, age, frequency of soap use, maternal education, season of skin swab collection, sequencing batch, and storage duration of the skin swab. As interaction terms between green-space indices and season were borderline statistically significant, we also ran the linear regression models stratified by season. Last, we performed a differential relative abundance analysis, accounting for the covariables above. Total green and high-growing green in multiple radii (from 100 to 500 m) were positively associated with observed richness (regression coefficients ranging from 10.06 to 15.31 [<i>P</i>-value ranging from 0.03 to 0.12] per interquartile range increase in green). The associations were only statistically significant when skin swabs were collected in the warm season. The relative abundance of the bacterial families <i>Xanthomonadaceae</i>, <i>Intrasporangiaceae</i>, <i>Pseudomonadaceae</i>, and <i>Caulobacteraceae</i> was statistically significantly positively associated with total and high-growing green within 300 m. Our findings suggest an influential role of early-life green space exposure on skin microbiome composition. Additional research is needed to investigate whether the observed positive relationship between green space and skin bacterial richness has implications for human health.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf115"},"PeriodicalIF":2.2,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12087450/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144103289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular choreography of sludge extracellular polymeric substances-From biomolecule identification to energetics and assembly dynamics.","authors":"Sainan Peng, Zhiyue Wang, Jing Ai, Lanfeng Li, Hao Zhou, Yu Zhang, Guiying Liao, Dongsheng Wang, Bing-Jie Ni, Guo-Ping Sheng, Chengzhi Hu, Weijun Zhang","doi":"10.1093/pnasnexus/pgaf157","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgaf157","url":null,"abstract":"<p><p>Extracellular polymeric substances (EPS) shape the immediate environment for microbial survival and biofilm formation. Dynamic agglomeration of EPS dominates the formation kinetics and structural properties of activated sludge flocs as a consequence of biopolymer interactions across the wastewater treatment process. Current partial understanding and imprecise modeling of the structure hinder the comprehensive elucidation of the dynamic reorganization of clusters as component interactions change, causing a gap in the fundamental knowledge of EPS generation and functions. Here, biopolymer models of aerobic activated sludge and anaerobic digestion sludge (ADS) were constructed through molecular screening, and the dynamic landscape of EPS multicomponent clusters was then captured by an extensive set of molecular dynamics simulations. Biopolymer chains are assembled hierarchically driven by interactions between polar functional groups and stabilized by hydrogen bonding and van der Waals forces after several substates to obtain the final conformation. Electrostatic repulsion induced by carboxylic groups causes the rugged energy landscape of the process. Biopolymer molecular arrangement governed by polar interactions determines the nonuniform distribution of functional groups and characteristic regions, resulting in the microscopic heterogeneity of EPS clusters. The structure of alpha-helices enhances protein aggregation efficacy by facilitating more polar interactions compared with other residues. Meanwhile, the flexible branched structure and amphiphilic unit improve the energetic contribution of polysaccharides to EPS structural stabilization. Higher humic substance and carboxyl groups content primarily weaken the structural strength of ADS EPS. In general, this study proposes a powerful approach for investigating the molecular choreography within EPS, utilizing atomic simulations based on solved structures to explore the contribution of specific biopolymer features to structural energetics, providing theoretical insights to guide EPS-engineered regulation in wastewater treatment processes.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf157"},"PeriodicalIF":2.2,"publicationDate":"2025-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12117330/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144176077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to: Nonnegligible cascading impacts of global urban expansion on net primary productivity.","authors":"","doi":"10.1093/pnasnexus/pgaf142","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgaf142","url":null,"abstract":"<p><p>[This corrects the article DOI: 10.1093/pnasnexus/pgae220.].</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"4 5","pages":"pgaf142"},"PeriodicalIF":2.2,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12077137/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144082674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}