Modeling regional-scale groundwater arsenic hazard in the transboundary Ganges River Delta, India and Bangladesh: Infusing physically-based model with machine learning
SCIENCE OF THE TOTAL ENVIRONMENT
Authors: Chakraborty, Madhumita; Sarkar, Soumyajit; Mukherjee, Abhijit; Shamsudduha, Mohammad; Ahmed, Kazi Matin; Bhattacharya, Animesh; Mitra, Adway
Abstract
For the last few decades, toxic levels of arsenic (As) in groundwater from the aquifers of the Ganges River delta, India and Bangladesh, have been known to cause serious public health concerns. Innumerable studies have advocated the control of geomorphologic, geologic, hydrogeologic, biogeochemical, and anthropogenic factors on arsenic mobilization, flow, and distribution patterns within the Ganges River delta. We have developed transboundary regional-scale models for computing the probability of groundwater As concentrations to exceed the WHO permissible thresholds for drinking water of 10 mu g/L within the Ganges River delta as a function of the various geomorphologic-(hydro)geologic-hydrostratigraphic-anthropogenic controlling factors, using statistical methods and artificial intelligence (Al) [i.e., machine learning] techniques namely, Random Forest (RF), Boosted Regression Trees (BRT) and Logistic Regression (LR) algorithms, followed by probabilistic delineation the high As-hazard zones within the delta. A "hybrid multi-modeling approach" was adapted for this study, which involved the introduction of hydrostratigraphic parameters (aquifer connectivity and surficial aquitard thickness) derived from a high-resolution transboundary hydrostratigraphic model developed for the Ganges River delta aquifer system, as predictors for modeling groundwater As probabilities within the delta. The RF model outperforms the BRT and LR model in terms of model performance. Model outputs suggest the dominant influence of surficial aquitard thickness and groundwater-fed irrigated area (%) on groundwater As. While, the north-central and southern regions of the Ganges River delta show low As-hazard (<10 mu g/L), the western and north-eastern regions demonstrate elevated hazard level (>10 mu g/L). An estimated 30.3 million people are found to be exposed to elevated groundwater As within the study area. Thus, our study demonstrates that such hybrid, predictive models are not only helpful in delineating the regional-scale distribution of groundwater As-hazard zones in the areas with limited As data but is also useful in identifying the possible exogenous forcing that may have led to the worst, natural pollution in human history. (C) 2020 Elsevier B.V. All rights reserved.
Impact of optical coherence tomography findings on clinical outcomes in ST-segment elevation myocardial infarction patients: a MATRIX (Minimizing Adverse Hemorrhagic Events by Trans-radial Access Site and angioX) OCT sub-study
INTERNATIONAL JOURNAL OF CARDIOVASCULAR IMAGING
Authors: Yacob, Omar; Garcia-Garcia, Hector M.; Dan, Kazuhiro; Soud, Mohamad; Adamo, Marianna; Picchi, Andrea; Sardella, Gennaro; Frigoli, Enrico; Limbruno, Ugo; Rigattieri, Stefano; Diletti, Roberto; Boccuzzi, Giacomo; Zimarino, Marco; Contarini, Marco; Russo, Filippo; Calabro, Paolo; Ando, Giuseppe; Varbella, Ferdinando; Garducci, Stefano; Palmieri, Cataldo; Briguori, Carlo; Kuku, Kayode O.; Karagiannis, Alexios; Valgimigli, Marco
Abstract
Purpose To investigate the association of the degree of stent expansion, as assessed by optical coherence tomography (OCT), following stent implantation, and clinical outcomes in ST-segment elevation myocardial infarction (STEMI) patients. Methods STEMI patients from the MATRIX (Minimizing Adverse Haemorrhagic Events by TRansradial Access Site and angioX) OCT study were selected; Clinical outcomes were collected through 1 year. Stent expansion index is a minimum stent area (MSA) divided by average lumen area (average of proximal and distal reference lumen area). The following variables were measured: MSA (< 4.5mm(2)), dissection (> 200 mu m in width and < 5 mm from stent segment), malapposition (> 200 mu m distance of stent from vessel wall), a thrombus (area > 5% of lumen area) were compared. Results A total of 151 patients were included; after excluding patients with suboptimal OCT quality, the population with available OCT was classified into 2 groups: under-expanded < 90% (N = 72, 51%) and well-expanded >= 90% (N = 67, 49%). In the well-expanded group, a significant number of the proximal vessels had a lumen area < 4.5mm(2) (16.1%, p < 0.001) and a greater thrombus burden within stent (56.7%, p = 0.042). The overall 30 day and 1 year major adverse cardiovascular event (MACE) rates were 5% and 6.1%, respectively. Conclusion Irrespective of the degree of stent expansion, the OCT findings, in STEMI patients, and the MACE at 30 days and one year follow up was low; further, well-expanded stents led to a more significant residual thrombotic burden within the stent but seemed to have insignificant clinical impact. Acknowledged stent optimization criteria, traditionally related to worse outcomes in stable patients, do not seem to be associated with worse outcomes in this STEMI population.