Auto- and cross-correlation analysis of the QSOs radio wave intensity

© Published under licence by IOP Publishing Ltd. We discuss here the Flicker-Noise Spectroscopy approach to studying astrophysical systems, for example the radio wave intensity of quasi-stellar object (QSO) 1641+399 and BL Lacertae (BL Lac) 0215+015 in different frequency ranges. The presented method allows to parameterize the study dynamics using a short set of characteristics. The considering sources have a significant differences in manifesting the non-stationary effects, dynamical intermittency and synchronization. The radio wave intensity dynamics of the BL Lac 0215+015 is characterized by well-defined set of natural frequencies, persistent behavior with low effects of non-stationarity and high level of frequency-phase synchronization. For dynamics of the QSO 1641+399 reverse occurs including the asymmetrical structure of cross-correlator. Our findings show that using the flicker-noise spectroscopy approach to studying astrophysical objects allows to carry out the more detail analysis of their behavior and evolution

Frequency and Phase Synchronization in Neuromagnetic Cortical Responses to Flickering-Color Stimuli

In our earlier study dealing with the analysis of neuromagnetic responses (magnetoencephalograms - MEG) to flickering-color stimuli for a group of control human subjects (9 volunteers) and a patient with photosensitive epilepsy (a 12-year old girl), it was shown that Flicker-Noise Spectroscopy (FNS) was able to identify specific differences in the responses of each organism. The high specificity of individual MEG responses manifested itself in the values of FNS parameters for both chaotic and resonant components of the original signal. The present study applies the FNS cross-correlation function to the analysis of correlations between the MEG responses simultaneously measured at spatially separated points of the human cortex processing the red-blue flickering color stimulus. It is shown that the cross-correlations for control (healthy) subjects are characterized by frequency and phase synchronization at different points of the cortex, with the dynamics of neuromagnetic responses being determined by the low-frequency processes that correspond to normal physiological rhythms. But for the patient, the frequency and phase synchronization breaks down, which is associated with the suppression of cortical regulatory functions when the flickering-color stimulus is applied, and higher frequencies start playing the dominating role. This suggests that the disruption of correlations in the MEG responses is the indicator of pathological changes leading to photosensitive epilepsy, which can be used for developing a method of diagnosing the disease based on the analysis with the FNS cross-correlation function.Comment: 21 pages, 14 figures; submitted to "Laser Physics", 2010, 2

Studying Properties of Abnormal Human Brain Activity in Photosensitive Epilepsy Caused by Light Stimulation

© 2015 Springer Science+Business Media New York Fractal features of neuromagnetic activity of the cerebral cortex in photosensitive epilepsy (PSE) before and after exposure to light flickering stimulus were studied. It was found that the dynamics of magnetoencephalographic signals of the PSE patient is characterized by higher values of the fractal index than in the control group. The most significant differences are revealed for the parietal, occipital, frontal, left parietal, and left temporal regions of the brain. Switching the stimulus led to a large-scale reaction of various regions of the cortex in the control group, while the patients showed a localized response

Dynamic and spectral X-ray features of the microquasar XTE J1550-564

Memory function formalism is used to investigate the dynamic and spectral features (including a quantitative comparison of the decay of correlations and statistical memory) of the time discrete X-ray signals from the microquasar XTE J1550-564. The X-ray dynamics has been recorded aboard the Rossi X-Ray Timing Explorer. Temporal and event correlations are analyzed to find distinct patterns in the relaxation processes and memory effects in the equi- and nonequidistant dynamics of the X-ray flux from XTE J1550-564. The described method can be used to study a wide range of astrophysical phenomena and processes associated with event representation. © 2014 Allerton Press, Inc

Cross-correlation markers in stochastic dynamics of complex systems

The neuromagnetic activity (magnetoencephalogram, MEG) from healthy human brain and from an epileptic patient against chromatic flickering stimuli has been earlier analyzed on the basis of a memory functions formalism (MFF). Information measures of memory as well as relaxation parameters revealed high individuality and unique features in the neuromagnetic brain responses of each subject. The current paper demonstrates new capabilities of MFF by studying cross-correlations between MEG signals obtained from multiple and distant brain regions. It is shown that the MEG signals of healthy subjects are characterized by well-defined effects of frequency synchronization and at the same time by the domination of low-frequency processes. On the contrary, the MEG of a patient is characterized by a sharp abnormality of frequency synchronization, and also by prevalence of high-frequency quasi-periodic processes. Modification of synchronization effects and dynamics of cross-correlations offer a promising method of detecting pathological abnormalities in brain responses. © 2010 Elsevier B.V. All rights reserved

The FNS-based analyzing the EEG to diagnose the bipolar affective disorder

Here we demonstrate a capability of method based on the Flicker-Noise Spectroscopy (FNS) in analyzing the manifestation bipolar affective disorder (BAD) in EEG. Generally EEG from BAD patient does not show the visual differences from healthy EEG. Analyzing the behavior of FNS-parameters and the structure of 3D-cross correlators allows to discover the differential characteristics of BAD. The cerebral cortex electric activity of BAD patients have a specific collective dynamics and configuration of the FNS-characteristics in comparison with healthy subjects

Studying Properties of Abnormal Human Brain Activity in Photosensitive Epilepsy Caused by Light Stimulation

© 2015, Springer Science+Business Media New York. Fractal features of neuromagnetic activity of the cerebral cortex in photosensitive epilepsy (PSE) before and after exposure to light flickering stimulus were studied. It was found that the dynamics of magnetoencephalographic signals of the PSE patient is characterized by higher values of the fractal index than in the control group. The most significant differences are revealed for the parietal, occipital, frontal, left parietal, and left temporal regions of the brain. Switching the stimulus led to a large-scale reaction of various regions of the cortex in the control group, while the patients showed a localized response

Cross MFF - Analysis in studying the obsessive-compulsive disorder

© Published under licence by IOP Publishing Ltd.There were demonstrated capabilities of the Memory Function Formalism (MFF) in analyzing cross correlations in human brain bioelectric activity at obsessive-compulsive disorder (OCD). To extract the information about collective phenomena in (electroencephalogram) EEG brain activity we use the power spectra of memory functions and the memory quantifiers. We discover the pairs of the electrodes with the greatest differences in dynamic and stochastic parameters for patients with the different condition. The high OCD condition is characterized by the influence of the memory effects. The MFF cross correlation analysis allow to describe the collective phenomena in EEG dynamics at OCD including the dynamic, spectral and stochastic behavior

Age-related alterations of relaxation processes and non-Markov effects in stochastic dynamics of R-R intervals variability from human ECGs

In this paper, we consider the age-related alterations of heart rate variability on the basis of the study of non-Markovian effects. The age dynamics of relaxation processes is quantitatively described by means of local relaxation parameters, calculated by the specific localization procedure. We offer a quantitative informational measure of non-Markovity to evaluate the change of statistical effects of memory. Local relaxation parameters for young and elderly people differ by 3.3 times, and quantitative measures of non-Markovity differ by 4.2 times. The comparison of quantitative parameters allows to draw conclusions about the reduction of relaxation rate with ageing and the higher degree of the Markovity of heart rate variability of elderly people. © 2005 Elsevier B.V. All rights reserved