Nevin Manimala

J Med Internet Res. 2026 Aug 17;28:e99762. doi: 10.2196/99762.

ABSTRACT

BACKGROUND: With rising digital media use among young children, concerns have grown regarding its impact on early socioemotional development. However, evidence regarding the dose-response relationship between digital screen time and children’s mental health, as well as the potential indirect statistical association with family factors, remains limited.

OBJECTIVE: The study aimed to explore the nonlinear association between screen time and mental health outcomes in preschool children, identify a potential threshold, and examine the indirect statistical association of parental discipline in this relationship.

METHODS: This cross-sectional study included 21,366 parent-child dyads from Western China. Participants were recruited through stratified cluster sampling from 189 public kindergartens across 13 districts between February 28 and March 5, 2025. Caregivers of children aged 3 to 6 years completed questionnaires administered by trained kindergarten teachers, reporting children’s average daily screen time (weekdays/weekends) over the preceding month. Children’s mental health was assessed using the Strengths and Difficulties Questionnaire. Generalized additive models and piecewise logistic regression identified nonlinear patterns and thresholds. Mediation analysis quantified the indirect statistical association of parental discipline, and moderation analyses examined interaction effects. Sensitivity analyses included threshold dichotomization, exclusion of extreme values, E-value calculation, multiple imputation for missing data, and reverse-direction mediation.

RESULTS: A significant nonlinear association was found, with a saturating dose-response pattern. A 2-piecewise logistic regression reparameterization yielded a policy-interpretable summary of approximately 70 minutes per day (95% CI 66-75) for elevated clinical risk. Below this summary estimate, each additional hour of screen time was associated with 65% greater odds of total difficulties (odds ratio 1.65, 95% CI 1.46-1.85); above the summary estimate, the association was greatly attenuated (odds ratio 1.07, 95% CI 1.01-1.13). However, the smooth generalized additive models fit marginally better (ΔAkaike information criterion=-6.78), indicating that the association is better characterized as a graded, saturating pattern rather than a sharply defined break point. Weekday screen time showed a stronger dose-response pattern than weekend screen time. Subgroup analyses suggested tentative moderation by the number of children and household registration (hukou, the birth-based urban vs rural classification that determines access to locally funded services such as education and health care), although these effects were not significant after false discovery rate correction. Parental discipline accounted for 20.5% of the association with total difficulties (95% CI 15.8%-26.2%), with similar patterns for externalizing (21.2%, 95% CI 15.7%-28.4%) and internalizing problems (23.6%, 95% CI 17.2%-33.5%). Multiple sensitivity analyses confirmed robustness of the findings.

CONCLUSIONS: Daily digital screen time shows a nonlinear association with preschool children’s mental health outcomes. Reducing weekday screen exposure and optimizing parental discipline represent promising intervention targets, based on cross-sectionally derived correlational mediation patterns. These findings offer locally relevant, evidence-based benchmarks for screen-time guidance and highlight modifiable parenting factors for early childhood digital health interventions.

PMID:42607303 | DOI:10.2196/99762

Age Ageing. 2026 Aug 3;55(8):afag242. doi: 10.1093/ageing/afag242.

ABSTRACT

INTRODUCTION: Frailty is a dynamic state linked to disability, hospitalisation and mortality. Cross-country comparisons of frailty progression remain limited. We compared frailty distribution, mortality risk and deficit accumulation across 17 middle-/high-income countries. We then examined whether outcomes among individuals with minimal baseline deficits (‘zero-state’) reflect broader population health patterns to explore utility of the ‘zero-state’ as a marker of population health.

METHODS: Data were from five harmonised longitudinal ageing surveys (Health and Retirement Survey, Survey of Health, Ageing and Retirement in Europe, English Longitudinal Study of Ageing, Chinese Health and Retirement Longitudinal Survey, Mexican Health and Ageing Study). A 31-item frailty index (FI) was constructed using identical variables at baseline, 2- and 4-year follow-up. Participants with <2 deficits were classified as in ‘zero-state’. Outcomes: all-cause mortality and FI change among survivors. Logistic regression (mortality) and negative binomial models (deficit accumulation) were adjusted for age, sex and baseline FI. Analyses were stratified by zero-state and non-zero-state.

RESULTS: Baseline frailty varied between countries: highest in the USA, Mexico and Southern/Eastern European nations, and lowest in Northern/Central Europe. Mortality and deficit accumulation differed substantially. Mexico showed highest mortality and fastest accumulation, while Switzerland and Scandinavian countries showed the lowest. Zero-state analyses revealed larger between-country differences, but lower statistical power, than analyses of those with higher FI. Some countries (e.g. USA, UK) showed favourable zero-state outcomes but more rapid progression among individuals with higher baseline FI.

CONCLUSION: Frailty distribution, mortality and frailty progression vary widely across settings, with poorer outcomes in lower-income countries. Zero-state trajectories capture important population differences but do not fully reflect patterns among those with existing frailty, potentially reflecting within-country inequalities.

PMID:42607277 | DOI:10.1093/ageing/afag242

Clin Transl Gastroenterol. 2026 Aug 17. doi: 10.14309/ctg.0000000000001081. Online ahead of print.

ABSTRACT

INTRODUCTION: Multitarget stool DNA (mt-sDNA) is a sensitive stool-based test for colorectal cancer (CRC) screening. Limited referral-center data suggest low rates of incident aerodigestive cancers after a positive mt-sDNA and negative colonoscopy; community-based outcomes are unknown.

METHODS: Retrospective cohort study of adults referred for colonoscopy after positive mt-sDNA in a large community practice (2017-2021). Among patients with negative colonoscopy, we manually recorded post-colonoscopy recommendations, findings if additional colonoscopies had been performed, aerodigestive cancer diagnosis, and last clinical follow-up. Observed cancer incidence was compared with Surveillance, Epidemiology, and End Results (SEER) data.

RESULTS: Of 1,176 patients completing colonoscopy after positive mt-sDNA, 328 (28%) had negative findings. Median cohort age was 67 (IQR 59-72) years. Colonoscopy was performed at a median of 53 days after mt-sDNA sample collection. Post-colonoscopy recommendations aligned with multi-society task force (MSTF) guidelines in 59% of patients. Thirty-two patients underwent repeat colonoscopy with a median of 3.5 (1.9-4.4) years later; 2 (6.3%) had advanced serrated lesions, and no CRC was detected. Median clinical follow-up was 4.4 (3.4-5.6) years. Seven patients developed aerodigestive cancers (2 pancreatic, 5 lung), consistent with expected age- and sex-adjusted SEER incidence (n=7.62) (p=0.823).

DISCUSSION: In this community cohort, when a positive mt-sDNA was followed by negative colonoscopy, rates of subsequent advanced colorectal neoplasia and aerodigestive cancer were low. Most patients received recommendations for subsequent colonoscopy that were consistent with MSTF guidelines. Findings further support the current MSTF recommendation of no additional evaluation for extra-colonic malignancy in asymptomatic patients after high quality follow-up colonoscopy.

PMID:42607275 | DOI:10.14309/ctg.0000000000001081

Community Dent Health. 2026 Aug 17:265539X261476516. doi: 10.1177/0265539X261476516. Online ahead of print.

ABSTRACT

BackgroundCleft lip and palate (CLP) are common congenital craniofacial anomalies associated with substantial health and psychosocial burdens. Although maternal smoking during pregnancy has been linked to CLP, observational studies cannot establish causality because of confounding and reverse causation.MethodsWe performed a two-sample Mendelian randomization (MR) study to investigate the causal effect of maternal smoking on offspring CLP. Genetic variants associated with maternal smoking were used as instrumental variables. Summary statistics were obtained from the UK Biobank (maternal smoking) and the FinnGen consortium (CLP). The primary analysis used the inverse-variance weighted (IVW) method, with MR-Egger and weighted median analyses conducted as sensitivity analyses.ResultsIVW analysis demonstrated a significant causal association between maternal smoking and CLP (b = 5.34, SE = 2.50, p < 0.05). Sensitivity analyses yielded consistent results and showed no evidence of substantial heterogeneity or horizontal pleiotropy, supporting the robustness of the findings.ConclusionsOur findings provide genetic evidence supporting a causal relationship between maternal smoking and CLP. These results reinforce the importance of smoking cessation during pregnancy and support public health strategies aimed at reducing preventable risk factors for CLP. Further studies are warranted to investigate the underlying biological mechanisms and validate these findings in diverse populations.

PMID:42607267 | DOI:10.1177/0265539X261476516

Am Fam Physician. 2026 Jul;114(1):13-15.

NO ABSTRACT

PMID:42607264

J Craniofac Surg. 2026 Aug 17. doi: 10.1097/SCS.0000000000013279. Online ahead of print.

ABSTRACT

PURPOSE: To compare the accuracy of digital occlusal articulation versus hand occlusal articulation for orthognathic surgical planning.

METHODS: This prospective, randomized clinical trial included 18 patients requiring orthognathic surgery, randomly assigned to a digital articulation group (n=9) or a hand articulation group (n=9). Linear displacements (X, Y, Z axes) at 5 maxillary and 5 mandibular landmarks and rotational errors (roll, pitch, and yaw) were measured postoperatively. Three blinded observers performed triplicate measurements. Interobserver reliability was assessed using intraclass correlation coefficients (ICC). Paired t tests were used for comparisons. Clinical tolerance was defined as <2 mm linear and <2 degrees rotational error.

RESULTS: Interobserver reliability was excellent for both methods (ICC ≥0.98, P<0.001). In the maxilla, overall mean error was similar between digital (0.378±0.201 mm) and hand (0.353±0.155 mm) groups (P=0.367). In the mandible, the digital method showed significantly larger mean error (0.720±0.281 mm) than hand (0.430±0.268 mm) (P<0.001). Axis-specific differences in the mandible were significant for X (P=0.03), Y (P=0.006), and Z (P=0.005). Rotational errors were <0.5 degrees for all axes except mandibular pitch (0.47 degrees, P=0.04). The largest mean linear error was 1.03 mm (digital mandibular left molar), well below the 2 mm clinical tolerance.

CONCLUSION: Digital occlusal articulation is as accurate as hand articulation in the maxilla and produces statistically larger but clinically acceptable errors in the mandible. Both methods are reliable and suitable for orthognathic surgical planning.

PMID:42607234 | DOI:10.1097/SCS.0000000000013279

Proc Natl Acad Sci U S A. 2026 Aug 25;123(34):e2613782123. doi: 10.1073/pnas.2613782123. Epub 2026 Aug 17.

ABSTRACT

Plastics research lags 30 y behind many other environmental crises, with population-level impacts alluded to but not yet demonstrated for any wild species. Addressing this “Grand Challenge” requires robust data that span many years of variable exposure. Here, we use 15 y of mark-recapture data to estimate plastics’ impact on the demography of Sable Shearwaters (Ardenna carneipes). We found that the ingestion of >1 g of plastic is common and associated with at least an 11% reduction in the probability of birds surviving to return and breed at their natal island, with birds that ingested >5 g of plastic almost never seen again. In a time of unprecedented planetary change and biodiversity collapse, these results provide much-needed insight into plastics’ role in potentially driving species decline.

PMID:42607211 | DOI:10.1073/pnas.2613782123

Proc Natl Acad Sci U S A. 2026 Aug 25;123(34):e2610388123. doi: 10.1073/pnas.2610388123. Epub 2026 Aug 17.

ABSTRACT

Social media feed algorithms rank content that is purported to be preferred by users, but the engagement behaviors that drive these algorithms are (at best) indirect proxies for users’ explicitly self-stated values. Are the resulting feeds value aligned, and if not, why? We investigate this question by annotating the basic human values expressed in participants’ X (Twitter) feeds (N = 715 US users), analyzing the relationship between the posts’ value expressions and the posts’ amplification in the ranked “For You” Page feed, and then comparing the amplified values to users’ own values. We observe that the inventory of posts from followed accounts reflects users’ self-stated values-but that there is an overall negative correlation (misalignment) between users’ explicit values and the value expressions the algorithm is more likely to amplify. We turn to engagement behavior to understand this misalignment and observe that users’ engagement behaviors can be misaligned with their stated values-likely causing the algorithm to learn and reflect these misaligned values. We also detect partisan differences consistent with this theory: While the algorithm amplifies values negatively correlated with both Democrats’ and Republicans’ self-stated values, they are more misaligned for Democrats. And in fact replying, a heavily weighted form of engagement, is associated with values that are less aligned for both Democrats’ and Republicans’ self-stated values, and is even more misaligned for Democrats. Taken together, these findings offer a glimpse into the tensions between the values that people hold and those that provoke reactions, and how these value tensions can produce misaligned outcomes.

PMID:42607202 | DOI:10.1073/pnas.2610388123

J Chem Phys. 2026 Aug 21;165(7):074103. doi: 10.1063/5.0341015.

ABSTRACT

This work investigates the emergent thermalization regimes in a chaotic Tavis-Cummings (TC) model and their implications in quantum spectroscopy. While the TC model is a cornerstone of cavity quantum electrodynamics, traditional treatments often overlook many-body effects that arise in the thermodynamic limit. We utilize the eigenstate thermalization hypothesis to demonstrate that a nonintegrable excitonic Hamiltonian within the material manifold drives local thermalization. By tuning the polariton splitting g, we observe two dynamical regimes: a thermalizing regime at low interactions driven by quantum chaos and ergodicity, and a nonthermalizing regime at high interactions where strong coupling suppresses ergodicity. We further show that these regimes have direct implications on output photon statistics, specifically influencing the correlation times τc of the cavity population and the second-order correlation function g(2) (t + τ). We propose that entangled-biphoton spectroscopy serves as an ideal experimental platform to probe these effects and to allow the characterization of the underlying many-body exciton-coupling disorder σ through coincidence measurements of the output. Taken together, these results exploit a naturally occurring many-body phenomenon to bridge theoretical predictions with experimental observables.

PMID:42607177 | DOI:10.1063/5.0341015

J Chem Phys. 2026 Aug 21;165(7):074901. doi: 10.1063/5.0346638.

ABSTRACT

Analysis of frontal dynamics during thermal polymerization was performed using an extension of the Spade and Volpert theory [C. A. Spade and V. A. Volpert, Combust. Theory Modell. 5, 21-39 (2001)]. The theory considers a reaction front of finite width, enabling a more realistic description of the temporal temperature evolution at a fixed point in a unidirectionally propagating reaction front. The predicted temperature profiles were compared with experimental thermocouple data obtained during frontal polymerization of bisphenol A diglycidyl ether (BADGE). By combining theoretical and experimental approaches, key thermal and kinetic parameters specific to the BADGE-based polymerization mixture were estimated.

PMID:42607167 | DOI:10.1063/5.0346638