494 research outputs found
Ecoepidemics with a nonlinear disease incidence
We present two new models for interacting populations subject to a
transmissible disease. The novelty lies in the assumption that herd behavior
influences the disease incidence, rather than the demographic description of
the interactions, as in previous related similar models. As it is already known
from other ecoepidemiological situations, the epidemics may affect the system
demographic outcomes
On the spreading of communicable diseases in farming environments
Epidemiological models for disease propagation, developed in strict collaboration with veterinarians, are important for providing farmers with guidelines on how to fight diseases that spread by contact among animals.
Directing our attention on hog-raising farms at first, we consider some control issues for containing the Aujeszky disease propagation. This is of high interest in a specific
Piedmontese area, where in the farms occupying an area of 30 square kilometers, about 90,000 hogs are concentrated.
A particularly strong and counterintuitive result for disease eradication is obtained in the second case of interest, concentrating
on CAEV (Caprine Arthritis Encephalitis Virus), a goats-affecting disease.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech.
Departamento de BiologĂa Celular, GenĂ©tica y FisiologĂ
Viral epidemiology of the adult Apis Mellifera infested by the Varroa destructor mite
The ectoparasitic mite Varroa destructor has become one of the major
worldwide threats for apiculture. Varroa destructor attacks the honey bee Apis
mellifera weakening its host by sucking hemolymph. However, the damage to bee
colonies is not strictly related to the parasitic action of the mite but it
derives, above all, from its action as vector increasing the trasmission of
many viral diseases such as acute paralysis (ABPV) and deformed wing viruses
(DWV), that are considered among the main causes of CCD (Colony Collapse
Disorder). In this work we discuss an SI model that describes how the presence
of the mite affects the epidemiology of these viruses on adult bees. We
characterize the system behavior, establishing that ultimately either only
healthy bees survive, or the disease becomes endemic and mites are wiped out.
Another dangerous alternative is the Varroa invasion scenario with the
extinction of healthy bees. The final possible configuration is the coexistence
equilibrium in which honey bees share their infected hive with mites. The
analysis is in line with some observed facts in natural honey bee colonies.
Namely, these diseases are endemic. Further, if the mite population is present,
necessarily the viral infection occurs. The findings of this study indicate
that a low horizontal transmission rate of the virus among honey bees in
beehives will help in protecting bee colonies from Varroa infestation and viral
epidemics
A model for an aquatic ecosystem
An ecosystem made of nutrients, plants, detritus and dissolved oxygen is
presented. Its equilibria are established. Sufficient conditions for the
existence of the coexistence equilibrium are derived and its feasibility is
discussed in every detail
The Galerkin method for singular integral equations revisited
AbstractIn an earlier work, the author has obtained error bounds for the Galerkin method for solving Cauchy singular integral equations, discovering that the usually neglected constants contain the Riemann zeta function, when evaluated in the supremum norm. The aim of this investigation is twofold: to show that the occurrence of the Riemann zeta function in the error bound for the Chebyshev norm is sharp; and secondly to use this result to obtain a class of forcing functions for which the method does not yield an approximate solution differing from the analytical one by at most a prescribed error tolerance. These counterexamples indicate that in practical situations, for functions exhibiting a behavior similar to the one presented here, Galerkin's method might not lead to an acceptable solution
An ecogenetic model
AbstractA model for the effects of a predator on a genetically distinguished prey population is formulated and investigated. The predator-free system settles at an equilibrium which can be destabilized by the predators if a suitably defined parameter, the predator invasion number, exceeds a threshold. The system can then coexist at a stable equilibrium or via persistent oscillations
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