arXiv subjects

Paulina Trybek

Publications and source records attributed to Paulina Trybek.

6 recordsLinked to original sources

arXiv2025

Selectivity filter conductance, rectification and fluctuations of subdomains - how can this all relate to the value of Hurst exponent in the dwell-times of ion channels states?

The Hurst effect in the signals describing ion channels' activity has been known for many years. This effect is present in the experimental recordings of single-channel currents, but not only. The sequences of dwell times of functionally different channel states also exhibit long-range correlations. We have found that the memory effect within the dwell-time series is related to the coupling between the channel's activation gate (AG) and selectivity filter (SF), which controls the ion conduction. In this work, we analyzed both the experimental data describing the activity of potassium channels of different types (e.g., BK, mitoBK, mitoTASK-3, mitoKv1.3, TREK-2-like channels) and the series generated according to our previously proposed Hurst effect model. The obtained results suggest that the strength of the allosteric cooperation between the AG and SF determines not only the conductance of the channel - which governs how often ions in SF move or remain blocked - but also modulates the correlations present in the dwell times when sampled with a suitably high sampling rate. Moreover, we found that rectification can interfere with this process, contributing to additional changes in correlations within the channel's sojourns in subsequent states. Similarly, the correlations may be affected by processes proceeding at longer time scales, like interactions with the channel's auxiliary domains or lipid surroundings.

nlin.CD↗

arXiv2018

The distribution of information for sEMG signals in the rectal cancer treatment process

The electrical activity of external anal sphincter can be registered with surface electromyography. This signals are known to be highly complex and nonlinear. This work aims in characterisation of the information carried in the signals by harvesting the concept of information entropy. We will focus of two classical measures of the complexity. Firstly the Shannon entropy is addressed. It is related to the probability spectrum of the possible states. Secondly the Spectral entropy is described, as a simple frequency-domain analog of the time-domain Shannon characteristics. We discuss the power spectra for separate time scales and present the characteristics which can represent the dynamics of electrical activity of this specific muscle group. We find that the rest and maximum contraction states represent rather different spectral characteristic of entropy, with close-to-normal contraction and negatively skewed rest state.

physics.med-ph↗

arXiv2018

Sample entropy of sEMG signals at different stages of rectal cancer treatment

Information theory provides a spectrum of nonlinear methods capable of grasping an internal structure of a signal together with an insight into its complex nature. In this work, we discuss the usefulness of the selected entropy techniques for a description of the information carried by the surface electromyography signals during colorectal cancer treatment. The electrical activity of the external anal sphincter can serve as a potential source of knowledge of the actual state of the patient who underwent a common surgery for rectal cancer in the form of anterior or lower anterior resection. The calculation of Sample entropy parameters has been extended to multiple time scales in terms of the Multiscale Sample Entropy. The specific values of the entropy measures and their dependence on the time scales were analyzed with regard to the time elapsed since the operation, the type of surgical treatment and also the different depths of the rectum canal. The Mann Whithney U test and Anova Friedman statistics indicate the statistically significant differences among all of stages of treatment and for all consecutive depths of rectum area for the estimated Sample Entropy. The further analysis at the multiple time scales signify the substantial differences among compared stages of treatment in the group of patients who underwent the lower anterior resection.

physics.med-ph↗

arXiv2017

Evaluation of the training objectives with surface electromyography

In this work the multifractal analysis of the kinesiological surface electromyographic signal is proposed. The goal was to investigate the level of neuromuscular activation during complex movements on the laparoscopic trainer. The basic issue of this work concerns the changes observed in the signal obtained from the complete beginner in the field of using laparoscopic tools and the same person subjected to the series of training. To quantify the complexity of the kinesiological sEMG, the nonlinear analysis technique, namely the MultiFractal Detrended Fluctuation Analysis was adopted. The analysis was based on the parameters describing the multifractal spectrum -- Hurst exponent and the spectrum width. The statistically significant differences for a selected group of muscles at the different states (before and after training) are presented. Additionally, as the base case, the relaxation state was considered and compared with the working states.

physics.data-an↗

arXiv2017

Multifractal characteristics of external anal sphincter based on sEMG signals

This work presents the application of Multifractal Detrended Fluctuation Analysis for the surface electromyography signals obtained from the patients suffering from rectal cancer. The electrical activity of an external anal sphincter at different levels of medical treatment is considered. The results from standard MFDFA and the EMD--based MFDFA method are compared. Two distinct scaling regions were identified. Within the region of short time scales the calculated spectra exhibit the shift towards higher values of the singularity exponent for both methods. In addition obtained spectra are shifted towards the lower values of singularity exponent for the EMD--based MFDFA.

physics.med-ph↗

arXiv2017

Inter-pulse intervals of external anal sphincter surface EMG signals recorded from colorectal cancer patients

Intervals between electrical pulses generated by the electrical activity produced by the motor units of an external anal sphincter were studied at four time intervals during multimodal rectal cancer treatment. Probability distribution function of such intervals does not exhibit significant differences for all considered time intervals. It is found that the probability distribution rescaled with an average interval time can be described by means of the stretched exponential function with the threshold dependent scale and shape parameters. Interval trains possess rather strong correlations as their shuffled counterparts show exponential Poisson like probability distribution. Finally the clustering effects were not found as the conditional probability distributions can also be described by the exponential function.

physics.med-ph↗