To address the issue that current dynamic models of drill strings often simplify the mathematical modeling of the interaction between the drill bit and the rock, thereby failing to accurately reflect the actual behavior of the drill bit, this study aims to explore the dynamic behavior of the horizontal well drill string system equipped with PDC drill bits under different drilling parameters, wellbore curvature, rock properties, and drill bit geometries. In this work, a dynamic mathematical model of the coupled nonlinear system of drillstring-PDC bit-rock under the wellbore trajectory of a three-dimensional curved well is established. The drillstring is spatially discretized into multiple Euler–Bernoulli beam elements using the finite element method. The PDC bit model is established based on projection principles and polygon clipping techniques, which fully accounts for the cutters layout, geometric shapes, state-dependent delay effects, and multiple cutters interactions. A new method for calculating the bit’s depth of cut was proposed. The interaction forces between the bit and the rock were introduced as boundary conditions for the drillstring model, while the displacement of the drillstring’s terminal node is used as an input to the bit model, achieving a nonlinear coupling between the bit and the drillstring. The coupled nonlinear dynamic system is solved using the Newmark method combined with an improved Newton–Raphson iteration scheme. The numerical results indicate that increasing the rotational speed and the weight on bit (WOB) will intensify the vibration of the drill string, but it will improve the drilling efficiency. A higher rotational speed helps to suppress the sliding vibration of stuck pipe, while a larger WOB can effectively alleviate the axial stuck pipe sliding phenomenon. An increase in the local curvature of the wellbore trajectory will lead to an increase in the vibration intensity of the drill string at that location. An increase in the strength of the formation rock will cause an increase in the vibration intensity of the drill bit and a greater increase in the axial strength than the torsional strength. In addition, PDC drill bits with more blades and cutting edges help to achieve more stable drilling performance, but too many blades and cutting edges may reduce the drilling speed. The conclusions provide a theoretical basis for vibration control of the drillstring, as well as for the selection of appropriate drilling parameters and bottom hole assembly configurations.
Heart failure (HF) is a chronic and progressive cardiovascular condition associated with significant morbidity, mortality and healthcare burden. Increasing evidence points to a critical role of gut dysbiosis and the gut–heart–brain axis in HF pathophysiology. Altered gut microbiota may influence systemic inflammation, neurohormonal activity and cardiac function through gut-derived metabolites such as trimethylamine N-oxide (TMAO) and short-chain fatty acids (SCFAs). Yoga-based cardiac rehabilitation (Yoga-CaRe) is a cost-effective intervention that has been shown to improve quality of life, exercise capacity and cardiovascular outcomes in cardiac patients. However, the mechanism underlying its benefits remains unclear. Furthermore, its effect on gut microbiota diversity and the downstream impact on the gut–heart–brain axis in HF remains largely unexplored. This study outlines a prospective, randomised, open-label, blinded-endpoint trial investigating the effects of a 12-week Yoga-CaRe intervention versus enhanced standard care in 60 HF patients with reduced ejection fraction. Participants will be randomly assigned in a 1:1 ratio to either the Yoga-CaRe or the control group. The Yoga-CaRe group will participate in 20 supervised yoga sessions, complemented by guided daily home practice, while the control group will receive enhanced standard care. The trial will assess changes in gut microbiota composition, levels of gut-derived metabolites (TMAO and SCFAs), inflammatory biomarkers (TNF-α and high-sensitivity C reactive protein), heart rate variability, 6 min walk test (6MWT) and echocardiography. Biological samples and clinical data will be analysed using integrated bioinformatics and statistical approaches to evaluate intervention efficacy and identify potential mechanistic pathways. The YoGH-Biome study has received ethical clearance from the Institutional Ethics Committee of the SDM College of Medical Sciences and Hospital, India (SDMIEC/2025/1073). It is registered with the Clinical Trials Registry of India. Study results will be disseminated via scientific publications, conferences and stakeholder forums to inform integrative strategies for HF management. Trial registration number: CTRI/2023/12/060757.
Antenatal care (ANC) is crucial for maternal and newborn health. Although ANC coverage has improved globally, ANC quality remains suboptimal. This study assessed the quality of first ANC visits and their association with perinatal outcomes. We used data from the eCohort study that collected longitudinal data on ANC utilization and quality until the end of pregnancy in Ethiopia, Kenya, South Africa, and India. Perinatal outcomes of interest included fetal losses (miscarriages ≥13 weeks of gestation or stillbirths) and low birth weight (LBW) newborns. Good quality ANC at first visits was defined as receiving six essential care components: blood pressure measurement, blood and urine tests, ultrasound, iron and folic acid supplementation, and counseling on pregnancy danger signs. We conducted mixed-effect logistic regressions to assess associations between good quality ANC and perinatal outcomes, with sensitivity analyses where good quality ANC excluded ultrasound scans. Among 3,600 pregnant women followed until the end of pregnancy, 5.8% received all six components at their first visits (from 1.3% in India to 14.0% in Ethiopia), and 30.7% received five components (5.7% in India to 52.5% in Kenya). Between 3.7% of women in Ethiopia and 6.3% in India experienced a fetal loss. Between 8.5% of newborns in Ethiopia and 16.3% in India were born LBW. Good quality ANC at first visits was associated with a 32% to 59% lower risk of fetal loss (primary analysis: risk ratio (RR) 0.41, 95% confidence interval (CI) 0.10-0.72; sensitivity analysis: RR 0.68, 95% CI 0.44-0.92). No significant associations were observed between good quality ANC and LBW. This study identified important gaps in ANC quality and found that good quality ANC is associated with a lower fetal loss risk. Investments must be made to improve ANC quality and ensure the delivery of essential care in pregnancy.
Background:Despite epidemiological evidence linking fine particulate matter (PM2.5) to cardiometabolic diseases, links between PM2.5 and kidney function or chronic kidney disease (CKD) remain inconclusive. Methods:In a population representative cohort of 12,271 adults (age ≥ 20 years) in 2 Indian cities (Chennai and Delhi), we investigated time-varying associations between annual average ambient PM2.5 and estimated glomerular filtration rates (eGFR) calculated using CKD-Epidemiology Collaboration (EPI) 2009 equations, at 3 time points during 2010 to 2016. Ambient PM2.5 exposures were assessed at residential geocodes using a national high-resolution spatiotemporal model for daily PM2.5 at 1 km × 1 km. City-specific linear mixed effect models were employed, incorporating inverse probability-based weighting to account for loss-to-follow-up. Effect modification by sex, waist-to-hip ratio, hypertension, and diabetes status were assessed using stratified models. Results:Annual average PM2.5 at baseline and 2 follow-ups in Chennai were 33, 37, and 30 μg/m3 whereas those in Delhi were 118, 123, and 130 μg/m3. Median eGFRs at baseline were 112 ml/min per 1.73 m2 (interquartile range [IQR]: 101.9-121.0) in Chennai and 106.4 ml/min per 1.73 m2 (IQR: 94.4-116.6) in Delhi. Over time, a 5 ug/m3 increase in annual average PM2.5 was associated with a significant decline in eGFR in both cities as follows: -0.32 (95% confidence interval [CI]: -0.49 to -0.15) ml/min per 1.73 m2 in Chennai and -0.42 (95% CI: -0.57 to -0.27) ml/min per 1.73 m2 in Delhi. Conclusion:Annual average PM2.5 levels were associated with declines in eGFR. These data from a relatively young South Asian urban cohort underscore the need to further investigate the potential renal and cardiovascular impacts of sustained air pollution exposure.
BackgroundPostnatal care (PNC) plays a crucial role in averting newborn mortality, yet its use remains low, particularly in regions with the highest mortality. While demographic and social determinants of PNC use have been well studied and have informed current strategies focused on changing care-seeking behaviors, the stagnating decline in neonatal mortality highlights the need for upstream and system-wide approaches to increase PNC uptake. Limited evidence exists to guide system-level reforms; therefore, we investigated whether health systems that ensure high-quality perinatal care are associated with increased use of PNC.Methods and findingsWe performed a cross-sectional observational study using Demographic and Health Survey data from 38 countries that had not met SDG neonatal mortality targets by 2020. The study population comprised women aged 15-49 years whose most recent live birth occurred within five years preceding the survey. We employed logistic regression models with country fixed effects to examine associations between: (1) perinatal service utilization, (2) service quality; and their relationship with postnatal checkups for newborns within 28 days. We analyzed utilization-quality interactions to determine how the effects of service coverage on PNC use varied by care quality and conducted wealth-stratified analyses to assess how quality effects on PNC use differed across socioeconomic groups. High-quality perinatal care was associated with a 2-fold increase in the probability of postnatal checkups within 28 days (0.406 in the highest quality tertile versus 0.221 in the lowest quality tertile). For mothers who received the lowest tertile of service quality, full utilization of perinatal services yielded negligible changes in postnatal checkup probability (0.217 to 0.216). Conversely, for mothers who received the highest quality of antenatal and perinatal care, full access to perinatal care improved the probability of postnatal check-ups (0.392 to 0.428). Notably, women in the lowest wealth quintile experienced a substantial increase in postnatal checkup probability from 0.224 to 0.481 between low and high-quality care cohorts, while this differential was less pronounced in the highest wealth quintile (0.236 to 0.450). Key limitations include restricted quality indicators, potential recall bias from self-reported measures, limited information on follow-up care, and the cross-sectional nature of the data, which limits causal interpretation.ConclusionsOur interaction analysis reveals a critical insight: high-quality care substantially enhanced the magnitude of the association between expanded perinatal service use and PNC use, whereas increased utilization alone was not linked to higher PNC uptake. Notably, the impact of improved care quality was most pronounced among the lowest wealth groups, highlighting its potential as a mechanism for promoting equity. By demonstrating the central role of care quality in promoting PNC utilization, particularly among disadvantaged populations, our findings suggest that improving health system quality could be a more effective strategy for achieving universal maternal healthcare coverage than traditional access-focused approaches.
