Climate change introduces substantial uncertainty to water resources planning and raises the key question: when, or under what conditions, should adaptation occur? A number of recent studies aim to ...identify policies mapping future observations to actions—in other words, framing climate adaptation as an optimal control problem. This paper uses the control paradigm to review and classify recent dynamic planning studies according to their approaches to uncertainty characterization, policy structure, and solution methods. We propose a set of research gaps and opportunities in this area centered on the challenge of characterizing uncertainty, which prevents the unambiguous application of control methods to this problem. These include exogenous uncertainty in forcing, model structure, and parameters propagated through a chain of climate and hydrologic models; endogenous uncertainty in human‐environmental system dynamics across multiple scales; and sampling uncertainty due to the finite length of historical observations and future projections. Recognizing these challenges, several opportunities exist to improve the use of control methods for climate adaptation, namely, how problem context and understanding of climate processes might assist with uncertainty quantification and experimental design, out‐of‐sample validation and robustness of optimized adaptation policies, and monitoring and data assimilation, including trend detection, Bayesian inference, and indicator variable selection. We conclude with a summary of recommendations for dynamic water resources planning under climate change through the lens of optimal control.
Key Points
This paper reviews dynamic planning studies for water resources systems under climate change framed as optimal control problems
Multiple sources of uncertainty, including climate and human system dynamics, prevent the identification of an optimal adaptation policy
Research opportunities remain to link dynamic planning with climate process insights and to identify indicator variables for monitoring
Abstract Complex three-dimensional (3-D) heart structure is an important determinant of cardiac electrical and mechanical function. In this study, we set to develop a versatile tissue-engineered ...system that can promote important aspects of cardiac functional maturation and reproduce variations in myofiber directions present in native ventricular epicardium. We cultured neonatal rat cardiomyocytes within a 3-D hydrogel environment using microfabricated elastomeric molds with hexagonal posts. By varying individual post orientations along the directions derived from diffusion tensor magnetic resonance imaging (DTMRI) maps of human ventricle, we created large (2.5 × 2.5 cm2 ) 3-D cardiac tissue patches with cardiomyocyte alignment that replicated human epicardial fiber orientations. After 3 weeks of culture, the advanced structural and functional maturation of the engineered 3-D cardiac tissues compared to age-matched 2-D monolayers was evident from: 1) the presence of dense, aligned and electromechanically-coupled cardiomyocytes, quiescent fibroblasts, and interspersed capillary-like structures, 2) action potential propagation with near-adult conduction velocity and directional dependence on local cardiomyocyte orientation, and 3) robust formation of T-tubules aligned with Z-disks, co-localization of L-type Ca2+ channels and ryanodine receptors, and accelerated Ca2+ transient kinetics. This biomimetic tissue-engineered platform can enable systematic in vitro studies of cardiac structure–function relationships and promote the development of advanced tissue engineering strategies for cardiac repair and regeneration.
Table of Contents Preamblee79 Introductione81 Methodology and Evidence Reviewe81 Organization of the GWCe82 Document Review and Approvale82 Scope of the CPGe82 Definitions of Urgency and Riske83 ...Clinical Risk Factorse83 Coronary Artery Diseasee83 Heart Failuree85 Role of HF in Perioperative Cardiac Risk Indicese85 Risk of HF Based on Left Ventricular Ejection Fraction: Preserved Versus Reducede85 Risk of Asymptomatic Left Ventricular Dysfunctione85 Role of Natriuretic Peptides in Perioperative Risk of HFe86 Cardiomyopathye86 Valvular Heart Disease: Recommendationse87 Aortic Stenosis: Recommendatione87 Mitral Stenosis: Recommendatione88 Aortic and Mitral Regurgitation: Recommendationse88 Arrhythmias and Conduction Disorderse88 Cardiovascular Implantable Electronic Devices: Recommendatione89 Pulmonary Vascular Disease: Recommendationse90 Adult Congenital Heart Diseasee90 Calculation of Risk to Predict Perioperative Cardiac Morbiditye90 Multivariate Risk Indices: Recommendationse90 Inclusion of Biomarkers in Multivariable Risk Modelse91 Approach to Perioperative Cardiac Testinge91 Exercise Capacity and Functional Capacitye91 Stepwise Approach to Perioperative Cardiac Assessment: Treatment Algorithme93 Supplemental Preoperative Evaluatione95 The 12-Lead Electrocardiogram: Recommendationse95 Assessment of LV Function: Recommendationse96 Exercise Stress Testing for Myocardial Ischemia and Functional Capacity: Recommendationse97 Cardiopulmonary Exercise Testing: Recommendatione97 Pharmacological Stress Testinge97 Noninvasive Pharmacological Stress Testing Before Noncardiac Surgery: Recommendationse97 Radionuclide MPIe98 Dobutamine Stress Echocardiographye98 Stress Testing--Special Situationse99 Preoperative Coronary Angiography: Recommendatione99 Perioperative Therapye99 Coronary Revascularization Before Noncardiac Surgery: Recommendationse100 Timing of Elective Noncardiac Surgery in Patients With Previous PCI: Recommendationse115 Future Research Directionse116 Referencese117 Appendix 1 Author Relationships With Industry and Other Entities (Relevant)e129 Appendix 2 Reviewer Relationships With Industry and Other Entities (Relevant)e131 Appendix 3 Related Recommendations From Other CPGse136 Appendix 4 Abbreviationse137 Preamble The American College of Cardiology (ACC) and the American Heart Association (AHA) are committed to the prevention and management of cardiovascular diseases through professional education and research for clinicians, providers, and patients. Since 1980, the ACC and AHA have shared a responsibility to translate scientific evidence into clinical practice guidelines (CPGs) with recommendations to standardize and improve cardiovascular health.
Aim: The aetiology of acute pancreatitis (AP) is complex, and many risk factors for AP are shared by patients with type 2 diabetes mellitus (T2DM). However, few have assessed risk factors for AP ...specifically in T2DM patients.
Methods: Patients in the General Practice Research Database (2 984 755, 5.0% with T2DM) were used to estimate incidence of AP for T2DM relative to non‐diabetes, adjusting for prior pancreatitis, gallbladder disease, obesity, smoking and alcohol use. Multivariate Cox regression analysis adjusting for risk factors and Charlson comorbidity index (CCI) was used to estimate hazard ratios (HR) with 95% confidence intervals (CI).
Results: Between 2003 and 2007, 301 of 148 903 patients with T2DM and 2434 of almost 3 million patients without diabetes developed AP. Patients with T2DM had higher risk for AP compared with patients without diabetes (crude HR: 2.89, 95% CI: 2.56–3.27). Patients with T2DM had significantly higher rates of prior alcohol and tobacco exposure (44.2 and 61.9% vs. 34.1 and 35.9%, p < 0.001) and of comorbid conditions (14.7% with CCI ≥1 vs. 4.3%, p < 0.001). Histories of obesity, pancreatitis, gallbladder disease, smoking or alcohol use were significant predictors of AP. After adjusting for these factors, age, gender and comorbidities, the risk of developing AP remained elevated in patients with T2DM (adjusted HR: 1.49, 95% CI: 1.31–1.70).
Conclusion: After adjusting for risk factors, patients with T2DM had an elevated risk of AP compared with patients without diabetes. Physicians should be aware of the increased risk in patients with T2DM, particularly in those with prior pancreatitis.
► Evaluation of multi-objective evolutionary algorithms for water resources. ► Contributes a new comprehensive diagnostic framework for MOEA evaluation. ► Provides a vision for important new areas ...for future research advances. ► Results for challenging calibration, monitoring, and water management applications. ► Borg is introduced as a new benchmark MOEA for water resources applications.
This study contributes a rigorous diagnostic assessment of state-of-the-art multiobjective evolutionary algorithms (MOEAs) and highlights key advances that the water resources field can exploit to better discover the critical tradeoffs constraining our systems. This study provides the most comprehensive diagnostic assessment of MOEAs for water resources to date, exploiting more than 100,000 MOEA runs and trillions of design evaluations. The diagnostic assessment measures the effectiveness, efficiency, reliability, and controllability of ten benchmark MOEAs for a representative suite of water resources applications addressing rainfall–runoff calibration, long-term groundwater monitoring (LTM), and risk-based water supply portfolio planning. The suite of problems encompasses a range of challenging problem properties including (1) many-objective formulations with four or more objectives, (2) multi-modality (or false optima), (3) nonlinearity, (4) discreteness, (5) severe constraints, (6) stochastic objectives, and (7) non-separability (also called epistasis). The applications are representative of the dominant problem classes that have shaped the history of MOEAs in water resources and that will be dominant foci in the future. Recommendations are given for the new algorithms that should serve as the benchmarks for innovations in the water resources literature. The future of MOEAs in water resources needs to emphasize self-adaptive search, new technologies for visualizing tradeoffs, and the next generation of computing technologies.
While optimality is a foundational mathematical concept in water resources planning and management, “optimal” solutions may be vulnerable to failure if deeply uncertain future conditions deviate from ...those assumed during optimization. These vulnerabilities may produce severely asymmetric impacts across a region, making it vital to evaluate the robustness of management strategies as well as their impacts for regional stakeholders. In this study, we contribute a multistakeholder many‐objective robust decision making (MORDM) framework that blends many‐objective search and uncertainty analysis tools to discover key tradeoffs between water supply alternatives and their robustness to deep uncertainties (e.g., population pressures, climate change, and financial risks). The proposed framework is demonstrated for four interconnected water utilities representing major stakeholders in the “Research Triangle” region of North Carolina, U.S. The utilities supply well over one million customers and have the ability to collectively manage drought via transfer agreements and shared infrastructure. We show that water portfolios for this region that compose optimal tradeoffs (i.e., Pareto‐approximate solutions) under expected future conditions may suffer significantly degraded performance with only modest changes in deeply uncertain hydrologic and economic factors. We then use the Patient Rule Induction Method (PRIM) to identify which uncertain factors drive the individual and collective vulnerabilities for the four cooperating utilities. Our framework identifies key stakeholder dependencies and robustness tradeoffs associated with cooperative regional planning, which are critical to understanding the tensions between individual versus regional water supply goals. Cooperative demand management was found to be the key factor controlling the robustness of regional water supply planning, dominating other hydroclimatic and economic uncertainties through the 2025 planning horizon. Results suggest that a modest reduction in the projected rate of demand growth (from approximately 3% per year to 2.4%) will substantially improve the utilities' robustness to future uncertainty and reduce the potential for regional tensions. The proposed multistakeholder MORDM framework offers critical insights into the risks and challenges posed by rising water demands and hydrological uncertainties, providing a planning template for regions now forced to confront rapidly evolving water scarcity risks.
Key Points
We advance many‐objective robust decision making for multiple stakeholders
Stakeholders' robustness exhibits dependencies, vulnerabilities, and tradeoffs
A modest reduction in demand growth rate insulates against future uncertainty
California's Central Valley is one of the world's most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports from a vast network of reservoirs ...and canals as well as groundwater, which has been substantially overdrafted to support irrigation. The region has undergone a shift to perennial (tree and vine) crops in recent decades, which has increased water demand amid a series of severe droughts and emerging regulations on groundwater pumping. This study quantifies the expansion of perennial crops in the Tulare Lake Basin, the southern region of the Central Valley with limited natural water availability. A gridded crop type dataset is compiled on a 1 mi2 spatial resolution from a historical database of pesticide permits over the period 1974-2016 and validated against aggregated county-level data. This spatial dataset is then analyzed by irrigation district, the primary spatial scale at which surface water supplies are determined, to identify trends in planting decisions and agricultural water demand over time. Perennial crop acreage has nearly tripled over this period, and currently accounts for roughly 60% of planted area and 80% of annual revenue. These trends show little relationship with water availability and have been driven primarily by market demand. From this data, we focus on the increasing minimum irrigation needs each year to sustain perennial crops. Results indicate that under a range of plausible future regulations on groundwater pumping ranging from 10% to 50%, water supplies may fail to consistently meet demands, increasing losses by up to 30% of annual revenues. More broadly, the datasets developed in this work will support the development of dynamic models of the integrated water-agriculture system under uncertain climate and regulatory changes to understand the combined impacts of water supply shortages and intensifying irrigation demand.
•Effect of uniform and non-uniform magnetic field on flow as well as heat transfer.•Effect of Cu, Al, TiO2 and hybrid (Cu + TiO2) nanofluids.•Direct as well as transverse jet impingement comparison ...and evaluation.•Equivalent nanofluid pairs as a switching option for efficient heat transfer fluid.
Effect of uniform and non-uniform magnetic field and jet impingement on the hydrodynamic and heat transfer performance of nanofluids has been investigated numerically. Five types of magnetic field with different strengths (Ha = 0–40) are applied externally to the flow domain under direct and transverse jet (cross-flow) impingement conditions. The effect of Reynolds number (Re = 200–600), nanoparticle type (Cu, Al, TiO2, and hybrid (Cu + TiO2)), nanoparticle diameter (dp = 20 nm–80 nm) and concentration (Ø = 1 vol% to 3 vol%) on the hydrodynamic and heat transfer behavior under uniform and non-uniform magnetic field are predicted. The presence of magnetic field introduced a Lorentz force responsible for higher values of flow velocity particularly near the walls resulting in the enhancement of average Nusselt number. Moreover, the direct and transverse jet against the applied uniform/non-uniform magnetic field also enhanced the local flow velocity near the impingement region leading to enhancement in the local Nusselt number. Transverse jet exhibits higher average Nusselt number in comparison with direct jet. A maximum heat transfer enhancement of 173% is obtained for 3 vol% Cu nanofluid under magnetic field. Moreover, two equivalent nanofluid pairs are also identified that will provide a better switching option in thermal management of high power electronic devices and nuclear reactors.
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