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1

Bootstrapping the empirical bounds on the variability of Sample Entropy in 24-hour ECG recordings for 1 hour segments

Zurek S., Grabowski W., Kosmider M., Jurga S., Guzik P., Piskorski J.

Journal of Applied Mathematics and Computational Mechanics

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2018

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Vol. 17, nr 2

105--113

EN

We investigate the variability of one of the most often used complexity measures in the analysis of the time series of RR intervals, i.e. Sample Entropy. The analysis is carried out for a dense matrix of possible r thresholds in 79 24h recordings, for segments consisting of 5000 consecutive beats, randomly selected from the whole recording. It is repeated for the same recordings in random order. This study is made possible by the novel NCM algorithm which is many orders of magnitude faster than the alternative approaches. We find that the bootstrapped standard errors for Sample entropy are large for RR intervals in physiological order compared to the standard errors for shuffled data which correspond to the maximum available entropy. This result indicates that Sample Entropy varies widely over the circadian period. This paper is purely methodological and no physiological interpretations are attempted.

2

Asymmetric detrended fluctuation analysis reveals asymmetry in the rr intervals time series

Mieszkowski D., Kośmider M., Krauze T., Guzik P., Piskorski J.

Journal of Applied Mathematics and Computational Mechanics

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2016

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Vol. 15, nr 1

99--106

EN

In this paper we apply the Asymmetric Detrended Fluctuation Analysis to the RR intervals time series. The mathematical background of the ADFA method is discussed in the context of heart rate variability and heart rate asymmetry. We calculate the α- and α+ ADFA scaling exponents for 100 RR intervals time series recorded in a group of healthy volunteers (20-40 years of age) with the use of the local ADFA. It is found that on average α+ < α-, and that locally α- dominates most of the time over α+ - both results are highly statistically significant.

3

Dynamic Decomposition of Poincaré Plots for Multivariate Analysis and Visualization of Simultaneously Recorded Physiological Time Series

Piskorski J., Guzik P.

Computational Methods in Science and Technology

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2010

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Vol. 16, No. 2

181-186

EN

We apply the dynamic decomposition of Poincaré plots, which is a computationally intensive, visual method of analysing physiological time series, to the analysis of the interbeat interval variability, systolic blood pressure, stroke volume and total peripheral resistance which were simultaneously recorded from a patient with pheochromocytoma and rapid, repetitive haemodynamic changes over 6 hours. The resulting animation is analysed and interpreted. It is found that changes in total peripheral resistance usually precede those of other variables, and the magnitude of changes is greatest for this variable. It is demonstrated that the decomposition of Poincaré plots of multivariate signals can visualise both the order and the extent of ongoing instant changes.

4

Filtering Poincaré plots

Piskorski J., Guzik P.

Computational Methods in Science and Technology

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2005

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Vol. 11, nr 1

39-48

EN

The Poincaré plot (PP) is one of the many techniques used for ascertaining the heart rate variability, which in turn is a marker of the activity of the autonomic system. Poincaré plots are very simple to produce, but their preparation involves a few fine points. This paper describes one of them, namely the filtering of data used for the Poincaré plot. We show the correct way of filtering data, present a few results of not filtering or incorrect filtering and demonstrate how proper filtering helps extract interesting information from the data. A few algorithms for preparing Poincaré plots, filtering data and calculating PP descriptors are included. As Matlab’s programming language is the unquestionable standard for data analysis in the medical sciences, we illustrate these algorithms by snippets of code in this language.

5

Tworzenie systemu wspomagającego organizowanie konferencji medycznych zgodnie z modelem kaskadowym cyklu życia oprogramowania

Całka M., Guzik P., Kniat J., Konieczka G., Luboch R., Sawczyk K., Gorzelańczyk E. J.

Bio-Algorithms and Med-Systems

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2005

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Vol. 1, no. 1/2

139--142

PL

Przedstawiono internetowy system Ordalia, który wspomaga organizację konferencji medycznych. System umożliwia obsługę wielu konferencji jednocześnie. Użytkownicy systemu to: organizatorzy, autorzy artykułów naukowych i recenzenci. Rolę głównego recenzenta pełni system. Zaprezentowano funkcje oferowane dla różnego typu użytkowników w postaci formularzy ekranowych. Przedstawiono krótki przegląd użytych metod i narzędzi programowania oraz możliwości rozwoju systemu.

EN

The paper presents the Ordalia internet-based system which helps to organize medical conferences. The system offers the possibility to run many conferences at the same time. The users of the system are: organizers, authors of scientific papers, and reviewers. The role of the general supervisor is played by the system administrator. In the paper, the functionality, offered to different types of users is briefly presented by describing appropriate screen forms. The short review of used methods and programming tools is also included in the final section of the paper. The summary stresses the benefits of the Ordalia system and the possibilities of its future development.