We study local stability of equilibria of selection-mutation equations when mutations are either very small in size or occur with very low probability. The main mathematical tools are the linearized stability principle and the fact that, when the environment (the nonlinearity) is finite dimensional, the linearized operator at the steady state turns out to be a degenerate perturbation of a known operator with spectral bound equal to 0. An example is considered where the results on stability are applied.
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http://dx.doi.org/10.1007/s00285-006-0056-4 | DOI Listing |
PLoS One
January 2025
Department of Mathematics, College of Natural and Computational Science, Debre Berhan University, Debre Berhan, Adis Ababa, Ethiopia.
Tuberculosis (TB) is one of the deadly infectious diseases affecting millions of individuals throughout the world. The main objective of this study is to investigate the impact of media coverage on the transmission dynamics of TB with vaccine and treatment strategy using mathematical model analysis. In the qualitative analysis of the proposed model we proved the existence, uniqueness, positivity, and boundedness of the model solutions, investigated both the disease-free and endemic equilibrium points, computed the basic and effective reproduction numbers using next generation matrix approach, analyzed the stability analysis of the equilibrium points, the backward bifurcation using the Castillo-Chavez and Song theorem and we re-formulated the corresponding optimal control problem and analyzed by applying the Pontryagin's Minimum Principle.
View Article and Find Full Text PDFSci Rep
January 2025
Qatar Environment & Energy Research institute (QEERI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, P.O. Box 34110, Doha, Qatar.
Keto-enol tautomerism in organic molecules presents a potential for modulating the charge transport at the nanoscale. The reduction of the isomerization barrier and favoring the highly conductive enol form are the main challenges towards practical implementation of this phenomenon. Using density functional theory calculations, we have demonstrated that pyridinic nitrogen in biphenyl molecules with keto-enol tautomerism can successfully make the conductive enol form energetically more favorable.
View Article and Find Full Text PDFMath Biosci
January 2025
Department of Applied Mathematics, The Hong Kong Polytechnic University, Hong Kong, China. Electronic address:
Amphibian decline and extinction have been observed on a global scale, highlighting the urgency of identifying the underlying factors. This issue has long been recognized as a critical concern in conservation ecology and continues to receive significant attention. Pathogen infection, in particular the chytrid fungus Batrachochytrium dendrobatidis, is postulated as a key factor contributing to the decline of certain species within specific regions.
View Article and Find Full Text PDFMath Biosci Eng
December 2024
Department of Engineering and Natural Sciences, University of Applied Sciences Merseburg, Eberhard-Leibnitz-Str. 2, D-06217 Merseburg, Germany.
In this article, we reconsider the classical target cell limited dynamical within-host HIV model, solely taking into account the interaction between $ {\rm{CD}}4^{+} $ T cells and virus particles. First, we summarize some analytical results regarding the corresponding dynamical system. For that purpose, we proved some analytical results regarding the system of differential equations as our first main contribution.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Applied Mathematics Laboratory, Courant Institute of Mathematical Sciences, Department of Mathematics, New York University, New York, NY 10012.
Mechanical systems with moving points of contact-including rolling, sliding, and impacts-are common in engineering applications and everyday experiences. The challenges in analyzing such systems are compounded when an object dynamically explores the complex surface shape of a moving structure, as arises in familiar but poorly understood contexts such as hula hooping. We study this activity as a unique form of mechanical levitation against gravity and identify the conditions required for the stable suspension of an object rolling around a gyrating body.
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