Earthquake recurrence as a record breaking process

Extending the central concept of recurrence times for a point process to recurrent events in space-time allows us to characterize seismicity as a record breaking process using only spatiotemporal relations among events. Linking record breaking events with edges between nodes in a graph generates a complex dynamical network isolated from any length, time or magnitude scales set by the observer. For Southern California, the network of recurrences reveals new statistical features of seismicity with robust scaling laws. The rupture length and its scaling with magnitude emerges as a generic measure for distance between recurrent events. Further, the relative separations for subsequent records in space (or time) form a hierarchy with unexpected scaling properties

Multi-Objective Optimization for Analysis of Changing Trade-Offs in the Nepalese Water-Energy-Food Nexus with Hydropower Development

While the water–energy–food nexus approach is becoming increasingly important for more efficient resource utilization and economic development, limited quantitative tools are available to incorporate the approach in decision-making. We propose a spatially explicit framework that couples two well-established water and power system models to develop a decision support tool combining multiple nexus objectives in a linear objective function. To demonstrate our framework, we compare eight Nepalese power development scenarios based on five nexus objectives: minimization of power deficit, maintenance of water availability for irrigation to support food self-sufficiency, reduction in flood risk, maintenance of environmental flows, and maximization of power export. The deterministic multi-objective optimization model is spatially resolved to enable realistic representation of the nexus linkages and accounts for power transmission constraints using an optimal power flow approach. Basin inflows, hydropower plant specifications, reservoir characteristics, reservoir rules, irrigation water demand, environmental flow requirements, power demand, and transmission line properties are provided as model inputs. The trade-offs and synergies among these objectives were visualized for each scenario under multiple environmental flow and power demand requirements. Spatially disaggregated model outputs allowed for the comparison of scenarios not only based on fulfillment of nexus objectives but also scenario compatibility with existing infrastructure, supporting the identification of projects that enhance overall system efficiency. Though the model is applied to the Nepalese nexus from a power development perspective here, it can be extended and adapted for other problems

Understanding skeletal muscle adaptation in health and chronic disease: a multi-omics based systems biology perspective

Mammalian skeletal muscle has a major impact on whole-body metabolic homeostasis. Hence, maintenance of a metabolically active muscle mass is key for optimal health. Notably, both muscle function and mass are profoundly negatively affected by environmental factors such as chronic smoking and physical inactivity. RNA abundance integrates genetic, epigenetic and environmental influences. Therefore, while true understanding of physiological adaptation likely require the integration between multi-level datasets, the transcriptome represents a powerful investigative tool in determining the underlying molecular mechanisms behind complex phenotypic traits. The overarching aim of this thesis was to evaluate, using omics-based systems biology approaches, the global regulation of RNAs during exogenous modulation of mammalian muscle phenotype in order to characterize local homeostatic processes as well as identify robust biomarker signatures. The first part of this thesis deals with smoke-induced peripheral muscle wasting. Initially, biological domain knowledge is used to validate a pre-clinical smoking model. Then, specific cytokines are statistically linked to limb muscle energy metabolism; a testable hypothesis supported by both animal and human data. The second part deals with the development of ‘molecular predictors’ of endurance training adaptability. Two complex clinically relevant traits are considered, namely whole-body insulin sensitivity and plasma triglyceride content. Promisingly, quantitative multi-gene predictors of response to training for both traits of interest were developed

The cost of ending groundwater overdraft on the North China Plain

Overexploitation of groundwater reserves is a major environmental problem around the world. In many river basins, groundwater and surface water are used conjunctively and joint optimization strategies are required. A hydroeconomic modeling approach is used to find cost-optimal sustainable surface water and groundwater allocation strategies for a river basin, given an arbitrary initial groundwater level in the aquifer. A simplified management problem with conjunctive use of scarce surface water and groundwater under inflow and recharge uncertainty is presented. Because of head-dependent groundwater pumping costs the optimization problem is nonlinear and non-convex, and a genetic algorithm is used to solve the one-step-ahead subproblems with the objective of minimizing the sum of immediate and expected future costs. A real-world application in the water-scarce Ziya River basin in northern China is used to demonstrate the model capabilities. Persistent overdraft from the groundwater aquifers on the North China Plain has caused declining groundwater levels. The model maps the marginal cost of water in different scenarios, and the minimum cost of ending groundwater overdraft in the basin is estimated to be CNY 5.58 billion yr−1. The study shows that it is cost-effective to slowly recover the groundwater aquifer to a level close to the surface, while gradually lowering the groundwater value to the equilibrium at CNY 2.15 m−3. The model can be used to guide decision-makers to economic efficient long-term sustainable management of groundwater and surface water resources