On The Dynamics Of The Difference Equation

In this paper, we studied the global behavior of the difference equation nbspwith non-negative parameters and the initial conditions nbspare non-negative real numbers

The Growth Dynamics on Tree Species of Fagaceae Family in a Tropical Montane Rain Forest of West Java, Indonesia

A one ha (100 x 100 m ) permanent plot each was established at sub-mountain (1000 m altitude) and mountain forests (1800 m altitude)in Gunung Halimun National Park,West Java in 1996.Both plots were monitored periodically in order to understand the population dynamics of tree species, an important aspect on understanding forest ecology.Number of individuals and total basal areas of Fagaceae species represented about 10 and 20.5% of total species in sub-mountain and 38 and 56.1% of total species in mountain forest.The distribution pattern of tree height(H, in m) of the similar diameter (D in cm) was consistently lower in mountain forest than of sub-mountain forest.The highest mortality index in sub-mountain and mountain forests was occurred on Lithocarpus sp.(ruui) and Castanopsis acuminatissima, respectively.As a whole, in both study sites, number of mortal individuals of all Fagaceae species during 1996-200 was higher than of recruit individuals.The growth and population dynamics of the Fagaceae species in both sites within 1996-2000 study periods were also discussed

The effects of Prandtl number on the nonlinear dynamics of Kelvin-Helmholtz instability in two dimensions

It is known that the pitchfork bifurcation of Kelvin-Helmholtz instability occurring at minimum gradient Richardson number in viscous stratified shear flows can be subcritical or supercritical depending on the value of the Prandtl number,. Here, we study stratified shear flow restricted to two dimensions at finite Reynolds number, continuously forced to have a constant background density gradient and a hyperbolic tangent shear profile, corresponding to the 'Drazin model' base flow. Bifurcation diagrams are produced for fluids with (typical for air), 3 and (typical for water). For and, steady billow-like solutions are found to exist for strongly stable stratification of beyond. Interestingly, these solutions are not a direct product of a Kelvin-Helmholtz instability, having half the wavelength of the linear instability, and arising through a superharmonic bifurcation. These short-wavelength states can be tracked down to at least and act as instigators of complex dynamics, even in strongly stratified flows. Direct numerical simulations of forced and unforced two-dimensional flows are performed, which support the results of the bifurcation analyses. Perturbations are observed to grow approximately exponentially from random initial conditions where no modal instability is predicted by a linear stability analysis.</p

Dynamics of the predator-prey models on the two-patch fragmented habitat with dispersal

[[abstract]]In this work, we consider the population-dispersal dynamics for predator-prey interactions in a two-patch environment. On each fragmented patch, there is a two-species predator-prey ecological system. It is assumed that the predator species are mobile. The existence and local dynamics of boundary equilibria and interior equilibria with respect to parameters are completely classified. Moreover, global extinction results are established analytically. In particular, the phenomenon of over-exploitation is also found in these discrete patches models. Finally, some biological interpretations are discussed.[[notice]]補正完

THE ENVIRONMENT DYNAMICS IDENTIFICATION BASED ON THE MODULAR COMPUTING COMPLEX

The research aims at covering the mathematical modeling issues of multidimensional applied problems of ecology based on the application of a modular computing complex. The problem of modeling air pollution processes is solved by mathematical models that adequately describe fundamental processes. That reveals issues such as a detailed analysis of the atmosphere of the city or industrial area, short-term forecast of air quality in the region, assessment of long term air purification programs, optimal emission management, transboundary transfer, etc. At the same time, the formulation and methods of solving problems of environmental dynamics identification are considered, which essence is to estimate the input parameters based on the factual information about the modeled system known from the experiment. In these studies, the multidimensional equation of harmful impurities transfer was reduced to a sequence of schemes involving unknown values in a single direction, alternately in the longitudinal, transverse and vertical.The implicit schemes lead to systems of algebraic linear equations with a three-diagonal structure. Thus, the methodological basis of the difference splitting schemes provides the economic and sustainable implementation of numerical models by the scalar runs method. That approach focuses on the fact that the greatest effect of a parallel processor is achieved when it is used to perform matrix computations of linear algebra.In order to analyze the feasibility of mathematical models, a package of applications was developed to compute the transfer of harmful impurities. A solution to several applied problems for the identification of the environmental dynamics is given.The research aims at covering the mathematical modeling issues of multidimensional applied problems of ecology based on the application of a modular computing complex. The problem of modeling air pollution processes is solved by mathematical models that adequately describe fundamental processes. That reveals issues such as a detailed analysis of the atmosphere of the city or industrial area, short-term forecast of air quality in the region, assessment of long term air purification programs, optimal emission management, transboundary transfer, etc. At the same time, the formulation and methods of solving problems of environmental dynamics identification are considered, which essence is to estimate the input parameters based on the factual information about the modeled system known from the experiment. In these studies, the multidimensional equation of harmful impurities transfer was reduced to a sequence of schemes involving unknown values in a single direction, alternately in the longitudinal, transverse and vertical.The implicit schemes lead to systems of algebraic linear equations with a three-diagonal structure. Thus, the methodological basis of the difference splitting schemes provides the economic and sustainable implementation of numerical models by the scalar runs method. That approach focuses on the fact that the greatest effect of a parallel processor is achieved when it is used to perform matrix computations of linear algebra.In order to analyze the feasibility of mathematical models, a package of applications was developed to compute the transfer of harmful impurities. A solution to several applied problems for the identification of the environmental dynamics is given

Can environmental toxins increase parasite fitness? Ecotoxicological studies on the effects of microcystin on the host-parasite dynamics of Schistocephalus solidus

Background: Eutrophication of aquatic biomes and exacerbated climate change effects are expected to result in a global increase in harmful cyanobacterial blooms. Cyanotoxins are detrimental to animal health, but how they affect the dynamics within ecosystems is still mostly unknown. With a host-parasite system acting as a microcosm, I wanted to explore the changes in host-parasite dynamics with a cyanotoxin present. Methods: In a set of laboratory studies with the copepod-Scistocephalus solidus system, I looked at the host-parasite dynamics in the presence of the hepatotoxin microcystin. In four different groups (control, toxin-only, infection-only, toxin-infection combined) of individually isolated copepods, I examined if mortality increased in the first intermediate host, or if the toxin would increase mortality or curb the growth in the parasite. Results: While the presence of toxin alone increased copepod mortality significantly, microcystin did not exhibit any toxin-parasite interaction leading to increased mortality. However, the host’s ability to hinder parasite growth was affected. Since tapeworms accumulate environmental toxins, I expected a lower growth rate of the parasites in the toxin group, but procercoids from toxin-parasite groups were found to have a significantly larger surface area (P.007) than procercoids from the infection-only group. Conclusions: The increased growth of parasites in the presence of microcystin, suggests a change in the host-parasite dynamic. While host mortality was not significantly affected by the parasite infection. Increased procercoid growth points to a rise in pathogen virulence or weakened immunity in the host, which could be detrimental in less robust host individuals.Masteroppgave i biologiBIO399MAMN-BI

“The Psychological Dynamics on Pandemic Period”

Hari ini dunia dilanda pandemi covid-19 yang menuntut perubahan dramatis. Secara alamiah, perubahan perilaku manusia merupakan basis terkuat dan terampuh untuk menghambat penyebaran pandemi. Ditambah lagi, perubahan disruptif yang juga menuntut adaptasi pada berbagai lapis kehidupan.&nbsp;Psychosophia Vol. 2, No. 2 (December 2020) berusaha untuk ikut serta dalam berkontribusi “nimbrung” dalam isu tersebut. Meskipun, karena keterbatasan di sana-sini, kami menjangkau sejauh yang kami mampu

Simple Dynamics on the Brane

We apply methods of dynamical systems to study the behaviour of the Randall-Sundrum models. We determine evolutionary paths for all possible initial conditions in a 2-dimensional phase space and we investigate the set of accelerated models. The simplicity of our formulation in comparison to some earlier studies is expressed in the following: our dynamical system is a 2-dimensional Hamiltonian system, and what is more advantageous, it is free from the degeneracy of critical points so that the system is structurally stable. The phase plane analysis of Randall-Sundrum models with isotropic Friedmann geometry clearly shows that qualitatively we deal with the same types of evolution as in general relativity, although quantitatively there are important differences.Comment: an improved version, 34 pages, 9 eps figure