Mathematical modelling of dynamics and control in metabolic networks. V. Static bifurcations in single biochemical control loops

1985 ◽  
Vol 113 (2) ◽  
pp. 279-298 ◽  
Author(s):  
Bernhard O. Palsson ◽  
Edwin N. Lightfoot
2021 ◽  
Vol 15 (5) ◽  
pp. e0009449
Author(s):  
Maylis Layan ◽  
Simon Dellicour ◽  
Guy Baele ◽  
Simon Cauchemez ◽  
Hervé Bourhy

Background Rabies is a fatal yet vaccine-preventable disease. In the last two decades, domestic dog populations have been shown to constitute the predominant reservoir of rabies in developing countries, causing 99% of human rabies cases. Despite substantial control efforts, dog rabies is still widely endemic and is spreading across previously rabies-free areas. Developing a detailed understanding of dog rabies dynamics and the impact of vaccination is essential to optimize existing control strategies and developing new ones. In this scoping review, we aimed at disentangling the respective contributions of mathematical models and phylodynamic approaches to advancing the understanding of rabies dynamics and control in domestic dog populations. We also addressed the methodological limitations of both approaches and the remaining issues related to studying rabies spread and how this could be applied to rabies control. Methodology/principal findings We reviewed how mathematical modelling of disease dynamics and phylodynamics have been developed and used to characterize dog rabies dynamics and control. Through a detailed search of the PubMed, Web of Science, and Scopus databases, we identified a total of n = 59 relevant studies using mathematical models (n = 30), phylodynamic inference (n = 22) and interdisciplinary approaches (n = 7). We found that despite often relying on scarce rabies epidemiological data, mathematical models investigated multiple aspects of rabies dynamics and control. These models confirmed the overwhelming efficacy of massive dog vaccination campaigns in all settings and unraveled the role of dog population structure and frequent introductions in dog rabies maintenance. Phylodynamic approaches successfully disentangled the evolutionary and environmental determinants of rabies dispersal and consistently reported support for the role of reintroduction events and human-mediated transportation over long distances in the maintenance of rabies in endemic areas. Potential biases in data collection still need to be properly accounted for in most of these analyses. Finally, interdisciplinary studies were determined to provide the most comprehensive assessments through hypothesis generation and testing. They also represent new avenues, especially concerning the reconstruction of local transmission chains or clusters through data integration. Conclusions/significance Despite advances in rabies knowledge, substantial uncertainty remains regarding the mechanisms of local spread, the role of wildlife in dog rabies maintenance, and the impact of community behavior on the efficacy of control strategies including vaccination of dogs. Future integrative approaches that use phylodynamic analyses and mechanistic models within a single framework could take full advantage of not only viral sequences but also additional epidemiological information as well as dog ecology data to refine our understanding of rabies spread and control. This would represent a significant improvement on past studies and a promising opportunity for canine rabies research in the frame of the One Health concept that aims to achieve better public health outcomes through cross-sector collaboration.


Author(s):  
Federico Zenith ◽  
Ulrike Krewer

The current state of research on direct methanol fuel cells focuses heavily on the cell itself, with only a small minority of published articles about the management of the complete DMFC system. It is of particular importance to learn about the dynamics and control of such systems in order to provide autonomous and robust operation in spite of changing environmental conditions. We simulate and analyse a reference DMFC system consisting of, besides a model of the fuel cell, a mixer, coolers, separators, pumps and a fuel tank. A control analysis of a DMFC system is presented, to understand which variables are to be controlled by what means, and what constraints the system sets on the control loops. Some apparently negative phenomena can be beneficial to control performance: methanol cross-over stabilises the concentration dynamics and allows the usage of simple feedforward controllers. A portable DMFC system may be used in various environments, with very different environmental conditions. It is therefore explored how these conditions influence the system’s operation and control strategy, especially in regard to environmental temperature and humidity. The current implementation of the model has been designed to study the long-term transients, such as overall anode-loop water and energy holdups, assuming pseudo-steady state for most units.


2014 ◽  
Vol 14 (12) ◽  
pp. 1189-1195 ◽  
Author(s):  
Joseph A Lewnard ◽  
Martial L Ndeffo Mbah ◽  
Jorge A Alfaro-Murillo ◽  
Frederick L Altice ◽  
Luke Bawo ◽  
...  

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