Association Between Health Plan Design and the Demand for Naloxone: Evidence From a Natural Experiment in New York.

Rail transit and travel satisfaction: Evidence from a natural experiment in Wuhan

Emerging evidence shows that inflammaging varies across populations, challenging universal immune-aging models. Urbanization in sub-Saharan Africa-characterized by reduced exposure to infectious diseases and rising rates of noncommunicable diseases-offers a natural experiment for assessing environmental effects on inflammaging. Lower inflammaging in indigenous groups may reflect adaptation to chronic infection, whereas heightened inflammation in industrialized populations suggests ecological imbalance, underscoring the need to include diverse ecological groups in aging research.

Natural disasters disrupt maritime operations, yet their environmental consequences remain underexplored. This study quantifies CO2 emission changes following the February 2023 İskenderun Bay earthquakes (7.6 Mwg and 7.5 Mwg) using AIS-derived port visit data and graph neural network modeling. Analyzing 25,837 port visits across a 36-month period (January 2022–December 2024), we compared emissions during baseline (pre-earthquake), acute disruption (February–June 2023), and recovery phases. Results revealed a statistically significant 35.9% increase in per-visit CO2 emissions during the acute phase (t = 11.79, p < 0.001, Cohen’s d = 0.27), driven by extended port visit durations (from 77.87 to 105.82 h). Counterfactual analysis estimated 27,574 tonnes of excess CO2 emissions directly attributable to earthquake disruption. Network analysis showed 23.8% reduction in edge density during the acute phase. The graph neural network (GNN) emission prediction model achieved R2 = 0.985 (baseline) and R2 = 0.997 (recovery) in predicting emission patterns, while acute phase showed predictability collapse (R2 = −1.591). These findings demonstrate that seismic events generate sustainability-relevant externalities beyond immediate physical damage, and that quantifying disruption-driven excess emissions supports sustainability-oriented port resilience planning and more robust maritime emission accounting (e.g., under the EU MRV framework).

Evolutionary shifts in diel activity patterns shape sensory remodeling across mammals, yet the genetic basis remains poorly understood. Tapirs represent a unique natural experiment, having reverted from a cathemeral ancestor to a nocturnal niche characterized by reduced vision but enhanced hearing and olfaction. Here, we investigate the genetic basis of this phenomenon by generating high-quality chromosome-level genomes for Tapirus terrestris and Tapirus indicus. Comparative analyses revealed extensive lineage-specific remodeling of genes and cis-regulatory elements linked to sensory pathways. Notably, functional validation via CRISPR-Cas9 editing of a tapir-specific conserved noncoding element (CNE74) upstream of the FLT1 gene in mice revealed coordinated sensory effects, including retinal degeneration and reduced visual acuity, yet enhanced auditory sensitivity. These findings suggest that regulatory element evolution may induce pleiotropic effects on competing sensory modalities, offering genetic insights into sensory evolution during temporal niche adaptation and potential relevance to human retinal vascular diseases.

In Hepatitis C Virus-Negative Recipients of a Hepatitis C Virus-Infected Donor Kidney, Direct Antiviral Agent Therapy for 8 Weeks Is Noninferior to 12 Weeks.

The built environment supports physical activity (PA) by providing opportunities to be active in daily life. Natural experiments are valuable for assessing how real-world changes to the built environment affect PA and are critical for guiding policies to improve population-level PA. The objective of this review was to summarize the evidence from natural experiments that investigated the impacts of built environment changes on PA in Canada. Searches were conducted in MEDLINE, Embase, PsycINFO, ProQuest Public Health and SportDISCUS, from inception to 27 November 2024. Natural experiment evaluations that included a comparator or historical control group and assessed changes in PA associated with changes in the built environment were eligible. A narrative synthesis summarizes the evidence and the certainty of the evidence. Results from the included natural experiments (n = 25) suggest positive effects, with low to moderate certainty, of increased walkability, new cycling and pedestrian infrastructure, bike share (bike rental) programs and new trails. However, there was very low to low certainty of no significant effects for bus rapid transit, school building and yard improvements and school zone improvements. Some evidence suggests negative effects of off-leash dog park areas on children's park-based PA and of daycare yard improvements on moderate-to-vigorous intensity PA. Few Canadian studies have evaluated the impact of built environment changes on PA, with most emerging in the last decade. Future studies should include larger and more diverse samples and all regions, control for confounders including seasonal variation in outdoor PA, use well-matched control groups and incorporate objective PA measures.

We examine how the large expansion of a medical subsidy program changes the behavior of primary care physicians. Since 2000, Japan, has seen a rapid development of a local subsidization program known as the Medical Subsidy for Children and Infants (MSCI), which substantially reduces out-of-pocket expenses for children’s healthcare utilization. Using a census of clinics from 1999 to 2011 matched with municipality-level eligibility criteria for the MSCI, we show that the MSCI increases the monthly number of visits per clinic. However, MSCI increased the likelihood that physicians would choose to open clinics in more densely populated areas, suggesting that expanding the generosity of the health insurance system may accelerate the concentration of physicians in urban centers. • We examine how the large expansion of a medical subsidy program (MSCI) changes pediatricians’ labor supply and practice location choice. • 1,096 changes of the MSCI eligible age in 614 municipalities are exploited for the identification. • The MSCI expansion increases the number of visits in clinics. • The number of consultation days and official business hours remain unchanged. • Pediatricians open their clinics in densely populated areas under the generous MSCI system.

To use a natural experiment to investigate the effect of antenatal corticosteroids on the risk of cerebral palsy. We included singleton livebirths with a maternal admission for delivery from 31 + 0 through 36 + 6 weeks of gestation, in British Columbia, Canada, between 2000 and 2015. Guidelines recommended antenatal corticosteroids through 33 + 6 weeks, and we estimated the effect of the corresponding sharp drop in the proportion treated at 34 + 0 weeks on the risk of a composite of death before age 2 or cerebral palsy. We defined cerebral palsy using diagnostic codes in hospital and physician-billing records before age 5 years and corrected for misclassification using external estimates of the sensitivity and specificity. We used logistic regression to estimate marginal effects at 34 + 0 weeks. There were 20 009 children in our study sample. The crude and misclassification-corrected risks of cerebral palsy were 6.2 and 5.6 per 1000, respectively. The risk of death before age 2 or cerebral palsy declined with increasing gestational age at maternal admission for delivery, but we found no convincing evidence of an abrupt change just before vs just after 34 + 0 weeks (risk ratio: 0.98, 95% confidence interval: 0.50 to 1.98). Results were similar using a composite outcome of in-hospital newborn death or cerebral palsy, and using cerebral palsy alone. We did not find evidence that the lower likelihood of being treated with antenatal corticosteroid at 34 + 0 weeks affected the risk of cerebral palsy, but the estimates were imprecise and compatible with benefits or harms.

Housing affordability and domestic violence: The case of San Francisco's rent control policies.

Abstract Urban infectious disease outbreaks pose critical challenges to public health in rapidly urbanizing cities. The COVID-19 pandemic provided a natural experiment to examine how area-level environmental and socioeconomic contexts are associated with infection risk over time. This study analyzed seven pandemic stages in Tokyo, Japan (2020–2022), across 53 municipalities using Random Forest-based interpretable machine learning models with SHapley Additive exPlanations (SHAP) and partial dependence plots (PDP) diagnostics. Feature selection and nonlinear modeling identified key drivers among 49 candidate variables. The results revealed significant spatial clustering of COVID-19 infection rates, with persistent hotspots in central wards like Shinjuku, Minato, and Shibuya, while suburban regions of Western Tokyo maintained lower infection rates. Key built environment factors exhibited stage-specific, nonlinear, and threshold-like associations with infection rates, including road density (25 km/km²), floor area ratio (0.25 to 0.3), and population density (400 and 600 people/km²). These associations were predominantly positive beyond the identified thresholds, indicating elevated infection risk under higher density and connectivity conditions. Socio-demographic factors also showed temporal specificity: the percentage of foreigners displayed a threshold around 1.5%, and construction worker density emerged as a relevant correlate during the Omicron-dominated phase. Overall, the relative importance and marginal patterns of these associations varied across intervention stages, highlighting temporal instability in area-level risk correlates. Importantly, these findings are associational rather than causal, reflecting contextual exposure conditions at the municipal scale. From an environmental epidemiology perspective, the results suggest that stage-sensitive and spatially explicit interpretation of area-level indicators may enhance infectious disease surveillance, compared with approaches assuming temporally invariant or linear effects.

Many children in poor countries forgo continued education due to both the direct costs of attending school (such as tuition) as well as the indirect opportunity costs. Children in households with greater income should not be as constrained and so are more likely to enrol. This paper exploits a natural experiment from Ghana in 2017 that eliminated the direct costs for secondary school but not the opportunity costs. To what extent did the association between income and enrolment weaken after this policy change? Using data from Ghana’s Socio-Economic Panel Survey from both before and after 2017, we find that associations between the two diminished after 2017, indicating that the policy helped to lower the dependence on household resources. Nevertheless, income remained a statistically significant predictor of enrolment, albeit not uniformly across the sample, especially for males as well as those in northern Ghana, its poorest region, and so delinking income from enrolment is not universal. Finally, we find that the decrease in income’s importance mattered more for retention than upon initial enrolment in secondary school.

A growing number of organizations hire employees with visible physical disabilities into jobs where they can perform as effectively as their nondisabled counterparts. Many practitioners expect such inclusion to positively impact nondisabled coworkers. Yet, the consequences for nondisabled coworkers’ productivity remain unclear. We focus on an underexplored mechanism: frontline managers’ discretionary allocation of supervisory support. Drawing on research on benevolent ableism and finite managerial capacity, we theorize that adding an employee with a visible physical disability—even one fully capable of performing the task—can shift supervisory support toward the disabled employee, reducing the support available to nondisabled coworkers. We test this theory using a natural experiment in a teleservice company that randomly assigned recruits, including individuals with visible physical disabilities, to project teams. We analyze 40,334 employee-month productivity bonus records, a standardized, nondiscretionary measure consolidating multiple performance indicators and net of supervisor evaluations. Supplemented with interviews with 15 frontline managers and 28 subordinate agents, our analyses show that managers allocated more supervisory support to disabled employees and that this reallocation dampened nondisabled coworkers’ productivity. Our study advances understanding of how disability inclusion shapes supervisory support patterns and its implications for coworker performance. Funding: X. Zhou gratefully acknowledges financial support from the National Natural Science Foundation of China [Grant 72102145] and Shanghai Oriental Talents Program. Supplemental Material: The online appendix is available at https://doi.org/10.1287/orsc.2024.19036 .

To assess whether the coronavirus disease 2019 (COVID-19) pandemic altered the clinical composition of HIV/AIDS-related deaths in Peru, distinguishing HIV/AIDS-only deaths from HIV/AIDS-COVID deaths and examining indicators of advanced HIV disease and opportunistic infections (OIs). Nationwide retrospective observational study using the onset of COVID-19 as an exogenous shock within a natural-experiment framework. Triangulation was performed across interrupted time series, ecological, and individual-level analyses. Individual-level mortality records from Peru's National Death Registry (January 2017-December 2024) were analyzed. HIV/AIDS-related deaths were identified using ICD-10 codes and text terms and classified as HIV/AIDS-only or HIV/AIDS-COVID. Segmented interrupted time series models estimated changes in monthly proportions of clinical indicators among HIV/AIDS-only deaths. Ecological models examined relationships between the monthly share of HIV/AIDS-COVID deaths and patterns in HIV/AIDS-only deaths. Multivariable regressions compared individual-level clinical characteristics during 2020-2024. The onset of COVID-19 coincided with abrupt declines in documentation of severe immunosuppression and OI among HIV/AIDS-only deaths. Months with a higher share of HIV/AIDS-COVID deaths were associated with lower prevalence of advanced HIV indicators among HIV/AIDS-only deaths. Individually, HIV/AIDS-COVID deaths showed slightly higher prevalence of advanced HIV disease but lower prevalence of OIs, whereas HIV/AIDS-only deaths more often reflected complex HIV-related pathology. The COVID-19 pandemic reconfigured the clinical composition of HIV/AIDS-related mortality in Peru, concentrating HIV/AIDS-only deaths among individuals with more advanced disease while generating a distinct profile of HIV/AIDS-COVID co-infection. Strengthening diagnostic capacity, continuity of HIV care, and integrated surveillance is essential to protect people living with HIV during future health-system shocks.

We evaluate the extent to which small businesses maintain an online presence and estimate the impact of digital representation on business performance. Looking at a review platform, we find that roughly 18% of bars and restaurants in our sample do not have a listing as of the end of 2017, even though creating one is free. We then estimate the effect of adding a new listing using tax records on revenues combined with temporal variation in listing activity as well as a natural experiment that added over a thousand businesses to the platform via a data acquisition. The results suggest that new listings increase revenues in the range of 5%–10%; however, these effects vary substantially across establishments. Establishments that struggle to develop a reputation (e.g., nonchains or those in tourist areas) and those with a higher quality of product (e.g., larger restaurants or those with good reviews) experience larger increases after being listed. This paper was accepted by Duncan Simester, marketing. Supplemental Material: The online appendix and data files are available at https://doi.org/10.1287/mnsc.2024.04716 .

Black and Hispanic faculty - underrepresented minorities (URMs) within academia - face career barriers that come to a crux in promotion and tenure decisions. Leveraging a natural experiment in choice architecture within a dataset of 1804 promotion and tenure decisions across six universities, we find that joint (906 faculty) vs. separate (898 faculty) evaluation reduces racial disparities in faculty outcomes. Specifically, in joint evaluation, an analysis of the simple slopes finds that Black and Hispanic faculty receive, on average, 9% fewer negative votes at the department level than in separate evaluations when controlling for research productivity, school, gender, rank, discipline, department size, and grant acquisition. Using moderated mediation analyses, we calculate that this translates into a 16.2% increase in the likelihood of a Black/Hispanic faculty member receiving a promotion. In a survey of 289 professors who have served on promotion and tenure committees (i.e., the key P&T decision-makers), we find that only 17% of faculty expect joint evaluation to improve underrepresented minority faculty outcomes and, conversely, 43% expect separate evaluation to improve underrepresented minority faculty outcomes. This natural experiment suggests that altering evaluation mode or simulating joint evaluation mode could help address academia's underrepresentation problem, but not in the way decision-makers expect.

ABSTRACT By exploiting the natural experiment of post-2022 sanctions against Russia, our study contributes to the sanctions literature by offering an empirical analysis of the determinants of the imposition of industry-specific trade sanctions from a cost-benefit point of view. We developed a specialized indicator designed to measure the intensity of trade sanctions imposed by the European Union (EU) and the U.S.A. against Russia in 2022–24, as a share of 2021 trade that would be affected by corresponding trade bans, by 2-digit HS product groups. Using econometric techniques, we show that the sanctioning countries strategically focus on restricting trade flows in order to exert maximum economic pressure on the Russian economy, including effects along value chains. This is consistent with the point of view that the probability of success of sanctions increases with economic harm to the target economy. At the same time, we get no empirical evidence in favor of the deterrent effect of costs related to sanctions. The sanctioning countries do not impose less-intensive restrictions on the trade flows that are economically important to their economies, which seems to indicate the firmness of their intentions.

Abstract Climate change has increased the frequency and severity of drought and large wildfire events across western North America. Despite the increasing concurrence of drought and wildfire events and the importance of forests as a global carbon sink, the impacts of fire on tree drought and carbon acquisition traits are not well understood, particularly on multi‐year time‐scales. In 2022–2024, we leveraged a natural experiment at a large 2018 wildfire in southwestern Colorado, comparing leaf and xylem functional traits related to drought resistance and carbon acquisition in burned and unburned ponderosa pine, quaking aspen, subalpine fir, and Engelmann spruce trees. Relative to unburned trees of the same species, we found reduced xylem vulnerability to embolism (P 50 ) in burned ponderosa pine and subalpine fir; decreased leaf heat tolerance (T 50 ) in burned quaking aspen and ponderosa pine; and increased investment in leaf structural over photosynthetic components (leaf C:N isotopic ratio) in burned quaking aspen, subalpine fir, and Engelmann spruce. In contrast to previous studies, our results suggest that wildfire positively impacts functional traits related to drought resistance and water movement in surviving burned trees. However, generally negative impacts of wildfire were found with respect to leaf physiological and photosynthetic traits, suggesting divergent water and carbon responses to fire. Read the free Plain Language Summary for this article on the Journal blog.

A wildfire occurred in the Gyeongpo district of Gangneung city, South Korea, on 11 April 2023, lasting for 8 h and burning 300 acres. While previous studies have examined the health effects of major wildfires, research on short-lasting, small-scale wildfires remains scarce. By capitalizing on the timing of the wildfire as a natural experiment, we investigated the health effects of the Gangneung wildfire on residents living near the wildfire site. The wildfire-exposed and control districts were determined based on satellite images of land damage. The weekly number of district-level cause-specific hospital visits was extracted from the National Health Insurance Database. The number of hospital visits for residents living in the exposed district was compared with that in 20 control districts by using the Generalized Synthetic Control Method. The excess number of visits attributable to the wildfire was estimated for periods of 0-3 and 0-7 weeks following the wildfire. Over 8 weeks following the wildfire, excess respiratory disease hospital visits {308.7 cases [95% confidence interval (CI): 119.7, 603.6]} were observed in residents of the exposed district, including cases of upper respiratory infections, influenza and pneumonia, and chronic lower respiratory diseases. Cardiovascular disease visits [83.3 cases (95%CI: 32.4, 136.0)] of the exposed district, notably for hypertensive disorders and ischemic heart diseases, increased for ≤4 weeks post-wildfire. Excess respiratory and cardiovascular disease-related hospital visits were observed among residents living near the wildfire site. Even a small-scale wildfire may have health impacts on residents for >2 months.

Elective caesarean sections (c-sections) present a significant public health challenge due to associated health risks and increased costs. This study examines the causal impacts of a unique natural experiment in São Paulo, Brazil: Law 17,137/2019, which temporarily allowed pregnant women to opt for c-sections in public healthcare facilities. Using a difference-in-differences estimator, we analyse the Law's effects on c-section rates across various hospital types, municipal characteristics, and demographics. The Law led to a significant and immediate 3.03 percentage point increase in c-section rates in public hospitals. Notably, this effect was limited to the public sector, with no consistent changes observed in private or mixed facilities. The impact was also temporary; following the Law's revocation less than a year later, c-section rates promptly reverted to pre-enactment levels, indicating no lasting effects. We find no evidence that the Law shifted deliveries from paid private care to free public hospitals. Our analysis reveals heterogeneous impacts, with the largest increases in c-section rates occurring in municipalities that had lower baseline c-section rates, a greater reliance on public healthcare, and fewer healthcare resources. These findings suggest that the law disproportionately affected areas with greater public health system strain. Interestingly, the increase in c-sections primarily occurred among low-risk births and had no detectable effect on newborn health outcomes, such as birth weight or Apgar scores. The additional 4,500 c-sections performed under the law created an added fiscal burden of approximately R$459,000 for the public health system, based on the cost difference between vaginal and c-section deliveries. This study underscores that while granting elective choice may seem empowering, it can lead to a surge in unnecessary, costly, and riskier procedures, highlighting the crucial need to consider both equity and resource implications when designing healthcare policies.