Delay-independent stability in bidirectional associative memory networks

It is shown that if the neuronal gains are small compared with the synaptic connection weights, then a bidirectional associative memory network with axonal signal transmission delays converges to the equilibria associated with exogenous inputs to the network. Both discrete and continuously distributed delays are considered; the asymptotic stability is global in the state space of neuronal activations and also is independent of the delays

Convergence in neural networks with interneuronal transmission delays

We obtain sufficient conditions for the global asymptotic stability of the equilibrium of a class of neural networks with inter-neuronal transmission delays

Time delays and stimulus-dependent pattern formation in periodic environments in isolated neurons

The dynamical characteristics of a single isolated Hopfield-type neuron with dissipation and time-delayed self-interaction under periodic stimuli are studied. Sufficient conditions for the hetero-associative stable encoding of periodic external stimuli are obtained. Both discrete and continuously distributed delays are included

Convergence under dynamical thresholds with delays

Necessary and sufficient conditions are obtained for the existence of a globally asymptotically stable equilibrium of a class of delay differential equations modeling the action of a neuron with dynamical threshold effects

Analysis of deposition of heavy metal dust on the leaves of few selected tree species in Kanchipuram town, Tamil Nadu, India

Biomonitoring of heavy metals is one of the economic methods to identify and improve the quality of air. The aim of this work was to identify the concentration of nine heavy metals viz. Fe, Pb, Cu, Zn, Al, Cd, As, Cr and Mn in the ambient air deposited on the leaves of five tree species such as Saraca asoca, Terminalia catappa, Syzygium cumini, Ficus religiosa and Pongamia glabra collected from six sites such as Pallavarmedu (Site I), CSI hospital (Site II), Moongilmandapam (Site III), Collectrate (Site IV), Near Cancer Institute (Site V) and VellaGate (Site VI) of the Kanchipuram town of TamilNadu State, in the months of February - March 2019. Even with some differences in the concentration of nine heavy metals on the species, few were identified with significant correlation, suggesting that these pollutants were emitted from similar sources. The deposition of iron (235.53mg/kg) and aluminium (157.91mg/kg) were higher on the leaves of S.asoca compared with other species. The metals such as Cu, Cd, As, Pb and Cr were nil and not detected on the leaves, but Pb concentration was high (185.79 mg/kg) only on P. glabra at Site 2 and Cr (2.37 mg/kg) was found on the leaves of S. asoca at Site 1. The heavy metal dust deposited on the leaf surface was probably due to vehicular emission and other anthropogenic activities. The analysis showed that all the selected tree species acted as a biomonitor and should be grown that may help to improve the air quality of the area

Persistence and Global Stability in a Population Model

AbstractA difference equation modelling the dynamics of a population undergoing a density-dependent harvesting is considered. A sufficient condition is established for all positive solutions of the corresponding discrete dynamic system to converge eventually to the positive equilibrium. Elementary methods of differential calculus are used. The result of this article provides a generalization of a result known for a simpler special model with no harvesting

Industrial Ecology as an Integrated Framework for Business Management

Growing global concerns about a plethora of environmental and social problems related to working circumstances, health, safety and inequity have currently fostered sustainability approaches for industry. Sustainable industrialization has emerged as a new strategic trend for facilitating socio-economic benefits without impairing basic environmental quality. This change in paradigm has led to a new concept in industrial sector called “Industrial Ecology (IE). Based on a straightforward analogy with the natural ecology, IE aims at transforming open linear industrial systems towards closed, cyclical independent systems. With a multidisciplinary scientific approach and many practical tools and strategies, it addresses various cross cutting themes related to pollution and environment and the entire spectrum of issues that are involved in the management of enterprises. The delineation of various concepts synthesized in this paper reveal a largely untapped potential of IE as a promising integrated framework for managing industrial practices. Keywords: Industrial Ecology, Sustainability, Integrated framework, Business, Management? Corporate Environmentalism, Waste

Oscillations of delay differential equations

[Mathematical equations cannot be displayed here, refer to PDF

Limicolaria flammea (Müller, 1774), another potentially invasive African land snail in tropical Asia

The pulmonate land snail, Limicolaria flammea (Müller, 1774), is native to West Africa and its invasive potential is hitherto unknown. We report this species in Asia, specifically on the tropical island of Singapore. The presence of this alien species is of grave concern because its congener (L. aurora) has invaded the French West Indies and the confamilial giant African land snail (Achatina fulica) has colonized the globe to an extent where it is regarded as one of the world's worst 100 invasive alien species. In order to curb the spread of L. flammea into the native forests in Singapore, local authorities should start employing mechanical eradication methods (e.g., handpicking). We hypothesize that L. flammea arrived together with an exotic plant species, whose identity and import origin must be determined urgently to prevent the spread of this species into the rest of tropical Asia

Hopf Bifurcation and Chaos in Tabu Learning Neuron Models

In this paper, we consider the nonlinear dynamical behaviors of some tabu leaning neuron models. We first consider a tabu learning single neuron model. By choosing the memory decay rate as a bifurcation parameter, we prove that Hopf bifurcation occurs in the neuron. The stability of the bifurcating periodic solutions and the direction of the Hopf bifurcation are determined by applying the normal form theory. We give a numerical example to verify the theoretical analysis. Then, we demonstrate the chaotic behavior in such a neuron with sinusoidal external input, via computer simulations. Finally, we study the chaotic behaviors in tabu learning two-neuron models, with linear and quadratic proximity functions respectively.Comment: 14 pages, 13 figures, Accepted by International Journal of Bifurcation and Chao