Effects of hypercapnia and hypocapnia on ventilatory variability and the chaotic dynamics of ventilatory flow in humans

2007 ◽  
Vol 292 (5) ◽  
pp. R1985-R1993 ◽  
Author(s):  
Marie-Noëlle Fiamma ◽  
Christian Straus ◽  
Sylvain Thibault ◽  
Marc Wysocki ◽  
Pierre Baconnier ◽  
...  
Keyword(s):  
Chaotic Dynamics ◽  
Initial Conditions ◽  
Lung Ventilation ◽  
Largest Lyapunov Exponent ◽  
Ventilatory Control ◽  
Method Noise ◽  
Noise Limit ◽  
Breathing Variability ◽  
Sensitivity To Initial Conditions

In humans, lung ventilation exhibits breath-to-breath variability and dynamics that are nonlinear, complex, sensitive to initial conditions, unpredictable in the long-term, and chaotic. Hypercapnia, as produced by the inhalation of a CO2-enriched gas mixture, stimulates ventilation. Hypocapnia, as produced by mechanical hyperventilation, depresses ventilation in animals and in humans during sleep, but it does not induce apnea in awake humans. This emphasizes the suprapontine influences on ventilatory control. How cortical and subcortical commands interfere thus depend on the prevailing CO2 levels. However, CO2 also influences the variability and complexity of ventilation. This study was designed to describe how this occurs and to test the hypothesis that CO2 chemoreceptors are important determinants of ventilatory dynamics. Spontaneous ventilatory flow was recorded in eight healthy subjects. Breath-by-breath variability was studied through the coefficient of variation of several ventilatory variables. Chaos was assessed with the noise titration method (noise limit) and characterized with numerical indexes [largest Lyapunov exponent (LLE), sensitivity to initial conditions; Kolmogorov-Sinai entropy (KSE), unpredictability; and correlation dimension (CD), irregularity]. In all subjects, under all conditions, a positive noise limit confirmed chaos. Hypercapnia reduced breathing variability, increased LLE ( P = 0.0338 vs. normocapnia; P = 0.0018 vs. hypocapnia), increased KSE, and slightly reduced CD. Hypocapnia increased variability, decreased LLE and KSE, and reduced CD. These results suggest that chemoreceptors exert a strong influence on ventilatory variability and complexity. However, complexity persists in the quasi-absence of automatic drive. Ventilatory variability and complexity could be determined by the interaction between the respiratory central pattern generator and suprapontine structures.

scholarly journals Sources of uncertainty in deterministic dynamics: an informal overview

2011 ◽  
Vol 369 (1956) ◽  
pp. 4705-4729 ◽  
Author(s):  
Ian Stewart
Keyword(s):  
Chaotic Dynamics ◽  
Chaotic Systems ◽  
Initial Conditions ◽  
Sources Of Uncertainty ◽  
Deterministic Systems ◽  
Coin Tossing ◽  
Random Switching ◽  
Butterfly Effect ◽  
Basin Boundaries ◽  
Sensitivity To Initial Conditions

The discovery of chaotic dynamics implies that deterministic systems may not be predictable in any meaningful sense. The best-known source of unpredictability is sensitivity to initial conditions (popularly known as the butterfly effect), in which small errors or disturbances grow exponentially. However, there are many other sources of uncertainty in nonlinear dynamics. We provide an informal overview of some of these, with an emphasis on the underlying geometry in phase space. The main topics are the butterfly effect, uncertainty in initial conditions in non-chaotic systems, such as coin tossing, heteroclinic connections leading to apparently random switching between states, topological complexity of basin boundaries, bifurcations (popularly known as tipping points) and collisions of chaotic attractors. We briefly discuss possible ways to detect, exploit or mitigate these effects. The paper is intended for non-specialists.

Chaos-Based Cryptography for Voice Secure Wireless Communication

2014 ◽  
pp. 97-132 ◽  
Author(s):  
Sattar B. Sadkhan Al Maliky ◽  
Rana Saad
Keyword(s):  
Wireless Communication ◽  
Chaos Theory ◽  
Initial Conditions ◽  
Security Research ◽  
Speech Encryption ◽  
Modern Cryptography ◽  
Long Term Prediction ◽  
The Voice ◽  
Sensitivity To Initial Conditions

Chaos theory was originally developed by mathematicians and physicists. The theory deals with the behaviors of nonlinear dynamic systems. Chaos theory has desirable features, such as deterministic, nonlinear, irregular, long-term prediction, and sensitivity to initial conditions. Therefore, and based on chaos theory features, the security research community adopts chaos theory in modern cryptography. However, there are challenges of using chaos theory with cryptography, and this chapter highlights some of those challenges. The voice information is very important compared with the information of image and text. This chapter reviews most of the encryption techniques that adopt chaos-based cryptography, and illustrates the uses of chaos-based voice encryption techniques in wireless communication as well. This chapter summarizes the traditional and modern techniques of voice/speech encryption and demonstrates the feasibility of adopting chaos-based cryptography in wireless communications.

LOW-DIMENSIONAL BEHAVIOR OF NONLINEAR TEARING MODE DYNAMICS IN A ROTATING PLASMA

1993 ◽  
Vol 03 (05) ◽  
pp. 1155-1168 ◽  
Author(s):  
M. PERSSON ◽  
C. R. LAING
Keyword(s):  
Lyapunov Exponent ◽  
Initial Conditions ◽  
Largest Lyapunov Exponent ◽  
Tearing Mode ◽  
Oscillatory State ◽  
The Largest Lyapunov Exponent ◽  
Low Dimensional ◽  
Sensitivity To Initial Conditions

Simulations of resistive magnetohydrodynamics in a rotating plasma are analyzed by calculating the correlation dimensions and the local intrinsic dimensions. A rotating plasma with a nonlinear oscillatory state is found to be associated with a low-dimensional attractor. The solutions are also checked for sensitivity to initial conditions, characterized by the sign of the largest Lyapunov exponent.

The chaotic dynamics of a quantum Cournot duopoly game with bounded rationality

2020 ◽  
Vol 18 (06) ◽  
pp. 2050029
Author(s):  
Xinli Zhang ◽  
Deshan Sun ◽  
Wei Jiang
Keyword(s):  
Quantum Entanglement ◽  
Stability Region ◽  
Chaotic Dynamics ◽  
Initial Conditions ◽  
Equilibrium Points ◽  
Largest Lyapunov Exponent ◽  
Cournot Duopoly ◽  
The Stability ◽  
The Impact ◽  
Rational Players

This paper analyzes the chaotic dynamics of a quantum Cournot duopoly game with bounded rational players by applying quantum game theory. We investigate the impact of quantum entanglement on the stability of the quantum Nash equilibrium points and chaotic dynamics behaviors of the system. The result shows that the stability region decreases with the quantum entanglement increasing. The adjustment speeds of bounded rational players can lead to chaotic behaviors, and quantum entanglement accelerates the bifurcation and chaos of the system. Numerical simulations demonstrate the chaotic features via stability region, bifurcation, largest Lyapunov exponent, strange attractors, sensitivity to initial conditions and fractal dimensions.

scholarly journals Chaos-Based Cryptography for Voice Secure Wireless Communication

Economics ◽  
2015 ◽  
pp. 460-493
Author(s):  
Sattar B. Sadkhan Al Maliky ◽  
Rana Saad
Keyword(s):  
Wireless Communication ◽  
Chaos Theory ◽  
Initial Conditions ◽  
Security Research ◽  
Speech Encryption ◽  
Modern Cryptography ◽  
Long Term Prediction ◽  
The Voice ◽  
Sensitivity To Initial Conditions

Chaos theory was originally developed by mathematicians and physicists. The theory deals with the behaviors of nonlinear dynamic systems. Chaos theory has desirable features, such as deterministic, nonlinear, irregular, long-term prediction, and sensitivity to initial conditions. Therefore, and based on chaos theory features, the security research community adopts chaos theory in modern cryptography. However, there are challenges of using chaos theory with cryptography, and this chapter highlights some of those challenges. The voice information is very important compared with the information of image and text. This chapter reviews most of the encryption techniques that adopt chaos-based cryptography, and illustrates the uses of chaos-based voice encryption techniques in wireless communication as well. This chapter summarizes the traditional and modern techniques of voice/speech encryption and demonstrates the feasibility of adopting chaos-based cryptography in wireless communications.

scholarly journals Seeking a Chaotic Order in the Cryptocurrency Market

2019 ◽  
Vol 24 (2) ◽  
pp. 36 ◽  
Author(s):  
Samet Gunay ◽  
Kerem Kaşkaloğlu
Keyword(s):  
Initial Conditions ◽  
Largest Lyapunov Exponent ◽  
Fluctuation Analysis ◽  
Multifractal Detrended Fluctuation Analysis ◽  
The Public ◽  
Box Counting ◽  
The Media ◽  
Bds Test ◽  
Detrended Fluctuation

In this study, we investigate the existence of chaos in the global cryptocurrency market. Specifically, we analyze parameters of chaotic order, nonlinearity, sensitivity to the initial conditions, monofractality, and multifractality. For this purpose, we conduct a comprehensive series of tests, including Brock–Dechert–Scheinkman (BDS) test, largest Lyapunov exponent, box-counting, and monogram analysis for fractal dimension, and multiple tests for long-range dependence (Aggregated Variances, Peng, Higuchi, R/S Analysis, and Multifractal Detrended Fluctuation Analysis (MFDFA)). All tests are performed over a variety of major cryptocurrencies: Bitcoin, Litecoin, Ethereum, and Ripple. The empirical results support the existence of chaos in the cryptocurrency market. Accordingly, cryptocurrency returns are not random and follow a chaotic order. Therefore, long term predictions are not possible, contrary to most of the discussions ongoing in the media and the public.

scholarly journals Chaotic dynamics of cardioventilatory coupling in humans: effects of ventilatory modes

2009 ◽  
Vol 296 (4) ◽  
pp. R1088-R1097 ◽  
Author(s):  
Laurence Mangin ◽  
Christine Clerici ◽  
Thomas Similowski ◽  
Chi-Sang Poon
Keyword(s):  
Time Series ◽  
Correlation Dimension ◽  
Chaotic Dynamics ◽  
Chaotic Behavior ◽  
Intrathoracic Pressure ◽  
Ventilator Weaning ◽  
Largest Lyapunov Exponent ◽  
Ventilatory Mode ◽  
Limit Value ◽  
Noise Limit

Cardioventilatory coupling (CVC), a transient temporal alignment between the heartbeat and inspiratory activity, has been studied in animals and humans mainly during anesthesia. The origin of the coupling remains uncertain, whether or not ventilation is a main determinant in the CVC process and whether the coupling exhibits chaotic behavior. In this frame, we studied sedative-free, mechanically ventilated patients experiencing rapid sequential changes in breathing control during ventilator weaning during a switch from a machine-controlled assistance mode [assist-controlled ventilation (ACV)] to a patient-driven mode [inspiratory pressure support (IPS) and unsupported spontaneous breathing (USB)]. Time series were computed as R to start inspiration (RI) and R to the start of expiration (RE). Chaos was characterized with the noise titration method (noise limit), largest Lyapunov exponent (LLE) and correlation dimension (CD). All the RI and RE time series exhibit chaotic behavior. Specific coupling patterns were displayed in each ventilatory mode, and these patterns exhibited different linear and chaotic dynamics. When switching from ACV to IPS, partial inspiratory loading decreases the noise limit value, the LLE, and the correlation dimension of the RI and RE time series in parallel, whereas decreasing intrathoracic pressure from IPS to USB has the opposite effect. Coupling with expiration exhibits higher complexity than coupling with inspiration during mechanical ventilation either during ACV or IPS, probably due to active expiration. Only 33% of the cardiac time series (RR interval) exhibit complexity either during ACV, IPS, or USB making the contribution of the cardiac signal to the chaotic feature of the coupling minimal. We conclude that 1) CVC in unsedated humans exhibits a complex dynamic that can be chaotic, and 2) ventilatory mode has major effects on the linear and chaotic features of the coupling. Taken together these findings reinforce the role of ventilation in the CVC process.

THE ORIGIN OF A CONTINUOUS TWO-DIMENSIONAL "CHAOTIC" DYNAMICS

2005 ◽  
Vol 15 (09) ◽  
pp. 3023-3029
Author(s):  
JOSE ALVAREZ-RAMIREZ ◽  
JOAQUIN DELGADO-FERNANDEZ ◽  
GILBERTO ESPINOSA-PAREDES
Keyword(s):  
Chaotic Dynamics ◽  
Initial Conditions ◽  
Dimensional System ◽  
Two Dimensional ◽  
Time System ◽  
Paradoxical Situation ◽  
Numerical Studies ◽  
Regularization Techniques ◽  
Sensitivity To Initial Conditions ◽  
Continuous Time System

Ten years ago, Dixon et al. [1993] studied the behavior of a continuous-time system displaying erratic, apparently chaotic, dynamics. This is a paradoxical case since the system is two-dimensional, which is seemingly a violation of the Poincare–Bendixon theorem. Using numerical studies, Dixon et al. explained such a behavior from the presence of an attracting singularity, which induces arbitrarily large sensitivity to initial conditions. The aim of this letter is to use singularity regularization techniques to study the dynamics around the system singularity. The results obtained in this way explain the paradoxical situation of having continuous "chaotic" dynamics in a two-dimensional system.

A New Image Encryption Scheme Using Dual Chaotic Map Synchronization

2020 ◽  
Vol 18 (1) ◽  
Keyword(s):  
Image Encryption ◽  
Chaotic Systems ◽  
Initial Conditions ◽  
Chaotic Map ◽  
Security Applications ◽  
The Common ◽  
And Diffusion ◽  
Confusion And Diffusion ◽  
Sensitivity To Initial Conditions ◽  
Diffusion Properties

Chaotic systems behavior attracts many researchers in the field of image encryption. The major advantage of using chaos as the basis for developing a crypto-system is due to its sensitivity to initial conditions and parameter tunning as well as the random-like behavior which resembles the main ingredients of a good cipher namely the confusion and diffusion properties. In this article, we present a new scheme based on the synchronization of dual chaotic systems namely Lorenz and Chen chaotic systems and prove that those chaotic maps can be completely synchronized with other under suitable conditions and specific parameters that make a new addition to the chaotic based encryption systems. This addition provides a master-slave configuration that is utilized to construct the proposed dual synchronized chaos-based cipher scheme. The common security analyses are performed to validate the effectiveness of the proposed scheme. Based on all experiments and analyses, we can conclude that this scheme is secure, efficient, robust, reliable, and can be directly applied successfully for many practical security applications in insecure network channels such as the Internet

scholarly journals Aircraft Maintenance Check Scheduling Using Reinforcement Learning

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 113
Author(s):  
Pedro Andrade ◽  
Catarina Silva ◽  
Bernardete Ribeiro ◽  
Bruno F. Santos
Keyword(s):  
Reinforcement Learning ◽  
Time Horizon ◽  
Learning Algorithm ◽  
Initial Conditions ◽  
Q Learning ◽  
Scheduling Policy ◽  
Real Scenario ◽  
Maintenance Plan ◽  
Small Disturbances

This paper presents a Reinforcement Learning (RL) approach to optimize the long-term scheduling of maintenance for an aircraft fleet. The problem considers fleet status, maintenance capacity, and other maintenance constraints to schedule hangar checks for a specified time horizon. The checks are scheduled within an interval, and the goal is to, schedule them as close as possible to their due date. In doing so, the number of checks is reduced, and the fleet availability increases. A Deep Q-learning algorithm is used to optimize the scheduling policy. The model is validated in a real scenario using maintenance data from 45 aircraft. The maintenance plan that is generated with our approach is compared with a previous study, which presented a Dynamic Programming (DP) based approach and airline estimations for the same period. The results show a reduction in the number of checks scheduled, which indicates the potential of RL in solving this problem. The adaptability of RL is also tested by introducing small disturbances in the initial conditions. After training the model with these simulated scenarios, the results show the robustness of the RL approach and its ability to generate efficient maintenance plans in only a few seconds.

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