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2003, Medical & Biological Engineering & Computing
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2000
2009, 2009 International Multiconference on Computer Science and Information Technology
2008, Annals of Noninvasive Electrocardiology
2002, Physiological Measurement
This review first gives an overview on the concept of fractal geometry with definitions and explanations of the most fundamental properties of fractal structures and processes like self-similarity, power law scaling relationship, scale invariance, scaling range and fractal dimensions. Having laid down the grounds of the basics in terminology and mathematical formalism, the authors systematically introduce the concept and methods of monofractal time series analysis. They argue that fractal time series analysis cannot be done in a conscious, reliable manner without having a model capable of capturing the essential features of physiological signals with regard to their fractal analysis. They advocate the use of a simple, yet adequate, dichotomous model of fractional Gaussian noise (fGn) and fractional Brownian motion (fBm). They demonstrate the importance of incorporating a step of signal classification according to the fGn/fBm model prior to fractal analysis by showing that missing out on signal class can result in completely meaningless fractal estimates. Limitation and precision of various fractal tools are thoroughly described and discussed using results of numerical experiments on ideal monofractal signals. Steps of a reliable fractal analysis are explained. Finally, the main applications of fractal time series analysis in biomedical research are reviewed and critically evaluated.
2011, Arabian Journal of Geosciences
Background: Research on functional water has revealed its physiological functions and health-beneficial effects. Accordingly, this study explored the effects of drinking an average dietary volume of functional coherent mineral water (FCMW) on blood pressure, short-term cardiovascular variables, fractal heart rhythm dynamics, and salivary immunoglobulin A. Methods: Fifteen healthy subjects were randomized in a pre-post crossover design, selected the morning after an overnight fast. Short-term electrocardiography (ECG) was measured before and after drinking either control mineral water (CMW) or FCMW on two separate occasions. Saliva was collected for four minutes before the start of each ECG measurement. Blood pressure was monitored in five-minute intervals for one hour. Results: Drinking 100 ml of FCMW temporarily increased arterial blood pressure at 20 to 25 minutes in the 60 minutes post-drinking. Drinking CMW led to a significant reduction in the heart rate, while all-time domain and Power Spectral Density parameters (PSD) were unaffected. Consumption of FCMW resulted in a highly significant difference and decrease in heart rate, and an increase in NN interbeat intervals, and in two of the PSD parameters. A large increase in total power had a significant increasing effect on 2–3-minute oscillations of the very low frequency (VLF) power, indicating a specific change in the heartʼs intrinsic cardiac rhythm that is fundamental to health and well-being. An extension in mono and multifractal scaling of heart rate dynamics defines a healthy function and non-local adaptability, indicating a higher capacity to respond to unpredictable stimuli and stresses, a function which improves autonomic stability. The effect on the heart rate and VLF power suggest an efficient cellular metabolism and a stabilizing effect on mucosal immunoglobulin A. Conclusions: Functional coherent mineral water with an apparent non-local electromagnetic identity triggered in healthy subjects a sustainable sympathetic response in cardiac VLF power, which is considered an intrinsic health-promoting rhythm produced by the heart itself that accompanies adaptive mono and multifractal heart rhythm dynamics.
This paper proposes a combined coarse-grained multifractal method to discriminate between distressed and normal foetuses. The coarse-graining operation was performed by means of a coarse-grained procedure and the multifractal operation was based on a structure function. The proposed method was evaluated by one hundred recordings including eighty normal foetuses and twenty distressed foetuses. We found that it was possible to discriminate between distressed and normal foetuses using the Hurst exponent, singularity, and Holder spectra.
2007
We investigate the statistical properties of high-latitude magnetometer data for differing geomagnetic activity. This is achieved by characterizing changes in the nonlinear statistics of the geomagnetic field, by means of the Hurst exponent, measured from a single ground-based magnetometer station.
2002, IEEE Signal …
2011, Medical Physics
2009, Philosophical Transactions of The Royal Society A: Mathematical, Physical and Engineering Sciences
2011, Pattern Recognition
2007, Biophysical Journal
2010, IRBM
2007, Chaos: An Interdisciplinary Journal of Nonlinear Science
2012, Methodology and Computing in Applied Probability
2014, International archives of medicine
We evaluated the effects of the PCM on the fractal analysis of the HRV in healthy women. We evaluated healthy women between 18 and 30 years old. HRV was analyzed in the time (SDNN, RMSSD, NN50 and pNN50) and frequency (LF, HF and LF/HF ratio) domains as well as short and long-term fractal exponents (alpha-1 and alpha-2) of the detrended fluctuation analysis (DFA). HRV was recorded at rest for ten minutes at seated rest and then the women quickly stood up from a seated position in up to three seconds and remained standing for 15 minutes. HRV was recorded at the following time: rest, 0-5 min, 5-10 min and 10-15 min during standing. We observed decrease (p < 0.05) in the time-domain indices of HRV between seated and 10-15 minutes after the volunteer stood up. The LF (ms(2)) and HF (ms(2)) indices were also reduced (p < 0.05) at 10-15 minutes after the volunteer stood up compared to seated while the LF (nu) was increased at 5-10 min and 10-15 min…
2006, Physica A: Statistical Mechanics and its Applications
2001
Abstract We present results obtained from the analysis of 50 heart rate variability series (HRV) which have been extracted from Holter recordings in the 24-hours in normal subjects and pathological patients. Data have been collected inside a multicentric research program, which aimed at the nonlinear analysis of HRV series. Multifractal approaches such as generalized structure functions have been used to characterize the HRV signal.
2002, IEEE Transactions on Information Theory
2000, Self-Similar Network Traffic and Performance Evaluation
2006, IEEE Transactions on Biomedical Engineering
2011
Abstract. Some signals obtained from biological systems evince a great complexity. Recently, new tools which allow the extraction of information from them have been proposed. In particular, multifractal analysis gives a quantification of the degree and distribution of irregularities in a signal. A possible approach for this analysis is the one based on wavelet leaders.
2008, Medical Imaging 2008: Computer-Aided Diagnosis
2013, Autonomic Neuroscience
2010, … Symposium on Space …
... Atiq Islama , Khan M. Iftekharuddin*a, Robert J. Oggb , Fred H. Laninghamb, and Bhuvaneswari Sivakumara a Intelligent Systems and Image Processing ... in MRIs are affected by various unwanted sources of variations such as different parameter settings and the physics of the ...
2015, Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology
Following the publication of the Task Force document on heart rate variability (HRV) in 1996, a number of articles have been published to describe new HRV methodologies and their application in different physiological and clinical studies. This document presents a critical review of the new methods. A particular attention has been paid to methodologies that have not been reported in the 1996 standardization document but have been more recently tested in sufficiently sized populations. The following methods were considered: Long-range correlation and fractal analysis; Short-term complexity; Entropy and regularity; and Nonlinear dynamical systems and chaotic behaviour. For each of these methods, technical aspects, clinical achievements, and suggestions for clinical application were reviewed. While the novel approaches have contributed in the technical understanding of the signal character of HRV, their success in developing new clinical tools, such as those for the identification of h...
2007
Fluctuations of the SYM-H index were analyzed for several space storms preceded by more than a week of extremely quiet conditions to establish that there was a rapid and unidirectional change in the Hurst scaling exponent at the time of storm onset. That is, the transition was accompanied by the specific signature of a rapid unidirectional change in the temporal fractal scaling of fluctuations in SYM-H, signaling the formation of a new dynamical phase (or mode) which was considerably more organized than the background state.
2012, Medical & Biological Engineering & Computing
2006, IEEE Transactions on Biomedical Engineering
Abstract In this paper we present evidence that the magnetosphere-ionosphere system is always in a critical state. This idea has been previously considered for magnetospheric substorms, but here we present evidence that even global space storms feature self-similarity and scaling behavior.
2008, Proceedings of SPIE …
... Atiq Islama , Khan M. Iftekharuddin*a, Robert J. Oggb , Fred H. Laninghamb, and Bhuvaneswari Sivakumara a Intelligent Systems and Image Processing ... in MRIs are affected by various unwanted sources of variations such as different parameter settings and the physics of the ...
Comparison of Linear Method and Non Linear Method for Analysis of Heart Rate Variability using Matlab
2004, Physica A-statistical Mechanics and Its Applications
2011, The Journal of Physiology
Acta Physica Polonica Series B
The rate of heart beat is controlled by autonomic nervous system: accelerated by the sympathetic system and slowed by the parasympathetic system. Scaling properties in heart rate are usually related to the intrinsic dynamics of this physiological regulatory system. The two packages calculating local exponent spectra: Wavelet Transform Modulus Maxima and Multifractal Detrended Fluctuation Analysis (accessible from Physionet home page http://circ.ahajournals.org/cgi/content/full/101/23/e215) are tested, and then used to investigate the spectrum of singularity exponents in series of heart rates obtained from patients suffering from reduced left ventricle systolic function. It occurs that this state of a heart could be connected to some perturbation in the regulatory system, because the heart rate appears to be less controlled than in a healthy human heart. The multifractality in the heart rate signal is weakened: the spectrum is narrower and moved to higher values what indicate the hig...
2010, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
2005, Nonlinear dynamics, psychology, and life sciences
A number of recent research works tried to apply fractal methods to psychological or behavioral variables. Quite often, nevertheless, the use of fractal analyses remains rudimentary, and the goal of researchers seems limited to evidencing the presence of long- range correlation in data sets. This article presents some recent developments in monofractals theory, and some related methodological refinements. We also discuss a number of specific issues related to the application of fractal methods in psychological and behavioral research. Finally, we consider the potential use of such approach for a renewal of classical issues in psychology and behavioral science.
1999, Physica A: Statistical …
2012, International Journal of Bifurcation and Chaos