In this paper, a virus infection model with time delay and absorption is studied. By analyzing the corresponding characteristic equations, the local stability of each of feasible equilibria of the model is established. By using comparison arguments, it is shown that the infection free equilibrium is globally asymptotically stable when the basic reproduction ratio is less than unity. When the ba...

Robert D. Holt*, Andrew P. Dobson, Michael Begon, Roger G. Bowers and Eric M. Schauber Department of Zoology, University of Florida, Gainesville, FL 32611, USA Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08540, USA Department of Environmental and Evolutionary Biology, Liverpool L69 3BX, UK Department of Applied Mathematics and Theoretical Physics, Univers...

A multi-patch and multi-group modeling framework describing the dynamics of a class of diseases driven by the interactions between vectors and hosts structured by groups is formulated. Hosts' dispersal is modeled in terms of patch-residence times with the nonlinear dynamics taking into account the effective patch-host size. The residence times basic reproduction number R0 is computed and shown ...

This paper deals with the nonlinear dynamics of a susceptible-infectious-recovered (SIR) epidemic model with nonlinear incidence rate, vertical transmission, vaccination for the newborns of susceptible and recovered individuals, and the capacity of treatment. It is assumed that the treatment rate is proportional to the number of infectives when it is below the capacity and constant when the num...

A semi-stochastic model for schistosomiasis was developed based on the immune response built up by human host after elapsing a fixed period of time L from the first infection, and on the parasite infection with multiple occurrences. Both acquired immunity and multiple parasite infections reproduced a great endemic stability for the disease and a high value for the basic reproduction ratio.

In many epidemiological models of microparasitic infections it is assumed that the infection process is governed by the mass-action principle, i.e. that the infection rate per host and per parasite is a constant. Furthermore, the parasite-induced host mortality (parasite virulence) and the reproduction rate of the parasite are often assumed to be independent of the infecting parasite dose. Howe...

We define a linear physiologically structured population model by two rules, one for reproduction and one for “movement” and survival. We use these ingredients to give a constructive definition of next-population-state operators. For the autonomous case we define the basic reproduction ratio R0 and the Malthusian parameter r and we compute the resolvent in terms of the Laplace transform of the ...

Ecological and evolutionary population changes are often interlinked, complicating the understanding of how each is affected by environmental change. Using a male dimorphic mite as a model system, we studied concurrent changes in the expression of a conditional strategy and in the population in response to harvesting over 15 generations. We found evolutionary divergence in the expression of alt...

the objectives of this study were to 1) describe the risk factors, incidence, production and reproduction consequences of retained placenta in dairy cows, and 2) estimate the financial losses associated with retained placenta. calving records from march 2008 to december 2013 comprising 59,341 calving were included in the data set. the effects of risk factors on retained placenta incidence were ...