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University of Nebraska - Lincoln
Department of Mathematics: Dissertations, Theses, and Student Research
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Full-Text Articles in Physical Sciences and Mathematics
Spectral Properties Of A Non-Compact Operator In Ecology, Matthew Reichenbach
Spectral Properties Of A Non-Compact Operator In Ecology, Matthew Reichenbach
Department of Mathematics: Dissertations, Theses, and Student Research
Ecologists have used integral projection models (IPMs) to study fish and other animals which continue to grow throughout their lives. Such animals cannot shrink, since they have bony skeletons; a mathematical consequence of this is that the kernel of the integral projection operator T is unbounded, and the operator is not compact. A priori, it is unclear whether these IPMs have an asymptotic growth rate λ, or a stable-stage distribution ψ. In the case of a compact operator, these quantities are its spectral radius and the associated eigenvector, respectively. Under biologically reasonable assumptions, we prove that the non-compact operators in …
Optimal Allocation Of Two Resources In Annual Plants, David Mcmorris
Optimal Allocation Of Two Resources In Annual Plants, David Mcmorris
Department of Mathematics: Dissertations, Theses, and Student Research
The fitness of an annual plant can be thought of as how much fruit is produced by the end of its growing season. Under the assumption that annual plants grow to maximize fitness, we can use techniques from optimal control theory to understand this process. We introduce two models for resource allocation in annual plants which extend classical work by Iwasa and Roughgarden to a case where both carbohydrates and mineral nutrients are allocated to shoots, roots, and fruits in annual plants. In each case, we use optimal control theory to determine the optimal resource allocation strategy for the plant …