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Spatial Extrapolation in Ecological Effect Assessment of Chemicals
Published in Keith R. Solomon, Theo C.M. Brock, Dick de Zwart, Scott D. Dyer, Leo Posthuma, Sean M. Richards, Hans Sanderson, Paul K. Sibley, Paul J. van den Brink, Extrapolation Practice for Ecotoxicological Effect Characterization of Chemicals, 2008
Theo C. M. Brock, Lorraine Maltby, Christopher W. Hickey, John Chapman, Keith R. Solomon
Metapopulation models explicitly deal with environmental heterogeneity in the distribution of habitats and organisms in the landscape. According to Hanski and Gyllenburg (1993), a metapopulation is a “population of populations” of the same species connected through immigration and emigration. In discontinuous habitats, corridors can connect habitat patches and integrate them into networks where populations can sustain in metapopulations. The minimum viable population (MVP) size is a population size below which patch extinction occurs. The carrying capacity (CC) is that population size that can just be maintained without a tendency to increase or decrease. A subpopulation may serve as a sink if it is below the MVP and drains immigrants, or it may serve as a source for nearby patches by providing immigrants to them. The addition of a toxicant to a source patch will have a greater impact than the same toxicant addition to a sink patch.
Dynamics of Population
Published in Robert Ehrlich, Harold A. Geller, John R. Cressman, Renewable Energy, 2023
Robert Ehrlich, Harold A. Geller, John R. Cressman
We have already noted that we were well aware that our models do not consider the emigration or immigration of individual members of the population to another population. This consideration leads to the concept that has been termed metapopulation since 1970. A metapopulation is a set of populations that are linked by the ability of members to exit or enter another population. As we noted earlier in this chapter, from the viewpoint of the use of energy resources of the planet Earth, we are most interested in the entirety of the human population. One is inevitably drawn to politics when one considers the human metapopulation and differences in time caused by the movement of members from one population to another.
Infectious disease control in metapopulations with limited resources
Published in IISE Transactions on Healthcare Systems Engineering, 2023
Ceyda Best, Amin Khademi, Burak Ekşioğlu
Motivated by aforementioned challenges, we propose a framework to study the dynamic containment of an epidemic in a metapopulation with limited resources. In particular, we consider a metapopulation, which is a collection of possibly dependent populations. Each population consists of susceptible, infected, and quarantined individuals, where susceptible individuals become infected by interacting with infected individuals in any of the populations. In particular, we assume that quarantined individuals stay in quarantine until they die. We relax this assumption, along with other assumptions, in our detailed simulation model in Section 6 and discuss the inclusion of recovered individuals in the optimization setting in Section 3. One important feature for such a metapopulation construction is that it can handle any type of interaction among populations for disease transmission. Previous models only consider geographical proximity in order to connect populations, but our framework generalizes the concept of dependency by introducing a metapopulation based model. Another feature of our construction is that all dynamics (e.g., disease transmission, death, and birth) are stochastic because the natural state of disease transmission is stochastic, and stochastic models predict the trajectory of epidemics more realistically (King et al., 2015). However, all previous optimization attempts for geographical consideration of infectious disease control are deterministic. Another layer of connection between populations is scarce capacity which is shared among all populations. This linking constraint is in addition to a limited capacity that each population may have for containing the disease. For example, suppose that each population is a state and the metapopulation is the country. An instance of limited capacity/resource for a state may be the limited number of nurses and physicians in that state for containing the disease and a limited shared capacity/resource could be the limited budget that the federal government has for assigning to different states for disease containment.