NONLINEAR DYNAMICS OF EVOKED NEUROMAGNETIC RESPONSES SIGNIFIES POTENTIAL DEFENSIVE MECHANISMS AGAINST PHOTOSENSITIVITY

2004 ◽  
Vol 14 (08) ◽  
pp. 2701-2720 ◽  
Author(s):  
JOYDEEP BHATTACHARYA ◽  
KATSUMI WATANABE ◽  
SHINSUKE SHIMOJO
Keyword(s):  
Nonlinear Dynamical System ◽  
Stimulus Frequency ◽  
Dynamical System Theory ◽  
Healthy Human ◽  
Nonlinear Dynamical ◽  
Time Frequency ◽  
Control Subjects ◽  
Photosensitive Epilepsy ◽  
Different Color ◽  
Measuring Signal

We investigated the dynamical characteristics of neuromagnetic responses by recording magnetoencephalographic (MEG) signals to equiluminant flickering stimulus of different color combinations from a group of control subjects, and from a patient with photosensitive epilepsy. By wavelet based time-frequency analysis, we showed that two distinct neuromagentic responses corresponding to stimulus frequency and its time delayed first harmonic were found in control subjects, whereas no harmonic response was obtained for the patient. We applied a battery of methods (sample entropy measuring signal complexity and index of smoothness measuring determinism) based on nonlinear dynamical system theory in conjunction with bootstrapping surrogate analysis. The results suggested that a significant nonlinear structure was evident in the MEG signals for control subjects, whereas nonlinearity was not detected for the patient. In addition, the couplings between distant cortical regions were found to be greater for control subjects. The important role of combinational chromatic sensitivity in sustained cortical excitation was also confirmed. These findings lead to the hypothesis that the healthy human brain is most likely equipped with significantly nonlinear neuronal processing reflecting an inherent mechanism defending against hyper-excitation to chromatic flickering stimulus, and such nonlinear mechanism is likely to be impaired for a patient with photosensitive epilepsy.

INFLUENCE OF ENVIRONMENTAL NOISE ON THE DYNAMICS OF A REALISTIC ECOLOGICAL MODEL

2007 ◽  
Vol 07 (01) ◽  
pp. L61-L77 ◽  
Author(s):  
R. K. UPADHYAY ◽  
A. MUKHOPADHYAY ◽  
S. R. K. IYENGAR
Keyword(s):  
Ecological Model ◽  
Dynamical Behavior ◽  
Nonlinear Dynamical System ◽  
Growth Parameter ◽  
Environmental Noise ◽  
Model System ◽  
Dynamical System Theory ◽  
Chain Model ◽  
Nonlinear Dynamical ◽  
Food Chain Model

The present paper investigates the influence of environmental noise on a fairly realistic three-species food chain model based on the Leslie-Gower scheme. The self- growth parameter for the prey species is assumed to be perturbed by white noise characterized by a Gaussian distribution with mean zero and unit spectral density. Using tools borrowed from the nonlinear dynamical system theory, we study the dynamical behavior of the model system. The behavior of the stochastic system (perturbed one) is studied and the fluctuations in the populations are measured both analytically (for the linearized system) and numerically by computer simulation. Varying one of the control parameters in its range, while keeping all the others constant, we monitor the changes in the dynamical behavior of the model system, thereby fixing the regimes in which the system exhibits chaotic dynamics. Our study suggests that the trophic level (top, middle or bottom) at which a population is positioned, the amplitude of environmental noise and the population's susceptibility to environmental noise play key roles in how noise affects the population dynamics.

scholarly journals Teams as Complex Adaptive Systems: Reviewing 17 Years of Research

2017 ◽  
Vol 49 (2) ◽  
pp. 135-176 ◽  
Author(s):  
Pedro J. Ramos-Villagrasa ◽  
Pedro Marques-Quinteiro ◽  
José Navarro ◽  
Ramón Rico
Keyword(s):  
Complex Adaptive Systems ◽  
Adaptive Systems ◽  
Nonlinear Dynamical System ◽  
Analytical Techniques ◽  
Turn Of The Century ◽  
Theory And Practice ◽  
Dynamical System Theory ◽  
Nonlinear Dynamical ◽  
Team Research ◽  
Complex Adaptive

At the turn of the century, Arrow, McGrath, and Berdahl portrayed teams as complex adaptive systems (CAS). And yet, despite broad agreement that this approach facilitates a better understanding of teams, it has only now been timidly incorporated into team research. To help fully incorporate the logic of teams as CAS in the science of teams, we review extant research on teams approached from a nonlinear dynamical system theory. Using a systematic review approach, we selected 92 articles published over the last 17 years to integrate what we know about teams as CAS. Our review reveals the evidence supporting teams as CAS, and the set of analytical techniques to analyze team data from this perspective. This review contributes to teams’ theory and practice by offering ways to identify both research methods and managing techniques that scholars and practitioners may apply to study and manage teams as CAS.

STATISTICAL MEMORY OF MEG SIGNALS AT PHOTOSENSITIVE EPILEPSY

2008 ◽  
Vol 18 (09) ◽  
pp. 2799-2805 ◽  
Author(s):  
R. M. YULMETYEV ◽  
E. V. KHUSAENOVA ◽  
D. G. YULMETYEVA ◽  
P. HÄNGGI ◽  
S. SHIMOJO ◽  
...  
Keyword(s):  
Human Brain ◽  
Chaotic Behavior ◽  
Brain Functioning ◽  
Dynamical Characteristics ◽  
Control Subjects ◽  
Brain Responses ◽  
Photosensitive Epilepsy ◽  
Different Color ◽  
Color Combinations

Here we discuss the remarkable role of the statistical memory effects in the human brain functioning at photosensitive epilepsy (PSE). We have analyzed three independent statistical memory quantifiers for the magnetoencephalographic (MEG) signals. These quantifiers reflect the dynamical characteristics of neuromagnetic brain responses to a flickering stimulus of different color combinations. Results for a group of control subjects are contrasted with those from a patient with PSE. The emergence of the strong memory and the transition to a regular and robust regime of chaotic behavior of the signals in separate areas is characteristic for a patient with PSE versus a healthy brain.

DEVELOPMENT OF THE NONLINEAR DYNAMICAL SYSTEMS THEORY FROM RADIO ENGINEERING TO ELECTRONICS

2009 ◽  
Vol 19 (07) ◽  
pp. 2131-2163 ◽  
Author(s):  
CHRISTOPHE LETELLIER ◽  
JEAN-MARC GINOUX
Keyword(s):  
Nonlinear Dynamical Systems ◽  
Nonlinear Dynamical System ◽  
Dynamical System Theory ◽  
Three Body Problem ◽  
Van Der Pol ◽  
Nonlinear Dynamical ◽  
Radio Engineering ◽  
Chua Circuit ◽  
Three Body ◽  
Initial Results

Although initial results that contributed to the emergence of the nonlinear dynamical system theory arose from astronomy (the three-body problem), many subsequent developments were related to radio engineering and electronics. The path between the van der Pol equation and the Chua circuit is thus reviewed through main historical contributions.

Bio-Mimetic Control Systems

1994 ◽  
Vol 6 (1) ◽  
pp. 109-113
Author(s):  
Koji Ito ◽  
Keyword(s):  
Control Systems ◽  
Cooperative Control ◽  
Motor Coordination ◽  
Nonlinear Dynamical System ◽  
Dynamical System Theory ◽  
Multiple Robots ◽  
Motor Patterns ◽  
Nonlinear Dynamical ◽  
Decentralized Architecture ◽  
Motor Control Systems

Bio-mimetic control is intended to study the theoretical framework of autonomous decentralized control systems based on the nonlinear dynamical system theory. It is useful for understanding and designing the parallel-decentralized architecture and the self-organizing function which play an important part in the motor control systems. Based on these theories, research should also be directed toward the analysis of the spatiotemporal motor patterns of the locomotion and arm action as well as toward the application to the sensory-motor coordination and the cooperative control of multiple robots.

scholarly journals Dynamical System Analysis of Interacting Hessence Dark Energy inf(T)Gravity

2017 ◽  
Vol 2017 ◽  
pp. 1-14
Author(s):  
Jyotirmay Das Mandal ◽  
Ujjal Debnath
Keyword(s):  
Dynamical System ◽  
Autonomous System ◽  
System Analysis ◽  
Nonlinear Dynamical System ◽  
Computational Method ◽  
Dynamical Analysis ◽  
Dynamical System Theory ◽  
Nonlinear Dynamical ◽  
The Stability ◽  
The Universe

We have carried out dynamical system analysis of hessence field coupling with dark matter inf(T)gravity. We have analysed the critical points due to autonomous system. The resulting autonomous system is nonlinear. So, we have applied the theory of nonlinear dynamical system. We have noticed that very few papers are devoted to this kind of study. Maximum works in literature are done treating the dynamical system as done in linear dynamical analysis, which are unable to predict correct evolution. Our work is totally different from those kinds of works. We have used nonlinear dynamical system theory, developed till date, in our analysis. This approach gives totally different stable solutions, in contrast to what the linear analysis would have predicted. We have discussed the stability analysis in detail due to exponential potential through computational method in tabular form and analysed the evolution of the universe. Some plots are drawn to investigate the behaviour of the system(this plotting technique is different from usual phase plot and that devised by us). Interestingly, the analysis shows that the universe may resemble the “cosmological constant” like evolution (i.e.,ΛCDM model is a subset of the solution set). Also, all the fixed points of our model are able to avoid Big Rip singularity.

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