1,720,996 research outputs found
Permanence and global stability of a class of discrete epidemic models
Full text linkIn this paper we investigate the permanence of a system and give a sufficient condition for the endemic equilibrium to be globally asymptotically stable, which are the remaining problems in our previous paper (G. Izzo, Y. Muroya, A. Vecchio, A general discrete time model of population dynamics in the presence of an infection, Discrete Dyn. Nat. Soc. (2009), Article ID 143019, 15 pages. doi:10.1155/2009/143019.
An affirmative answer to “Gopalsamy and Liu’s conjecture”on population models with multiple piecewise constantarguments
No full textA General Discrete Time Model of Population Dynamics in the Presence of an Infection
No full textWe present a set of difference equations which generalizes that proposed in the work of G. Izzo and A. Vecchio (2007) and represents the discrete counterpart of a larger class of continuous model concerning the dynamics of an infection in an organism or in a host population. The limiting behavior of this new discrete model is studied and a threshold parameter playing the role of the basic reproduction number is derived
Asymptotic Behavior of Solutions for Nonlinear Volterra Discrete Equations
No full textWe consider nonlinear difference equations of unbounded order of the form xi=bi−∑j=0iai,jfi−j(xj), i=0,1,2,…, where fj(x) (j=0,…,i) are suitable functions. We establish sufficient conditions for the boundedness and the convergence of xi as i→+∞. Some of these conditions are interesting mainly for studying stability of numerical methods for Volterra integral equations
Convergence of solutions for two delays Volterraintegral equations in the critical case
No full textAbstractIn this paper, for the “critical case” with two delays, we establish two relations between any two solutions y(t) and y∗(t) for the Volterra integral equation of non-convolution type y(t)=f(t)+∫t−τt−δk(t,s)g(y(s))ds and a solution z(t) of the first order differential equation ż(t)=β(t)[z(t−δ)−z(t−τ)], and offer a sufficient condition that limt→+∞(y(t)−y∗(t))=0
On the Stability of Numerical Methods for Nonlinear Volterra Integral Equations
Full text linkHere we investigate the behavior of the analytical and numerical solution of a
nonlinear second kind Volterra integral equation where the linear part of the kernel
has a constant sign and we provide conditions for the boundedness or decay of solutions
and approximate solutions obtained by Volterra Runge-Kutta and Direct Quadrature methods
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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