Fractal structure underlying patterns of premature heart beats

1993 ◽  
Vol 265 (5) ◽  
pp. H1603-H1613 ◽  
Author(s):  
R. De Paola ◽  
H. X. Wang ◽  
W. I. Norwood
Keyword(s):  
Heart Rate ◽  
Clinical Data ◽  
Fractal Structure ◽  
Nonlinear Mathematical Model ◽  
Time Intervals ◽  
Data Set ◽  
Apparent Lack ◽  
Term Order ◽  
Premature Beats

Distinctive patterns of premature heart beats are frequently observed in clinical data, yet transitions from one pattern to another often appear to occur unpredictably. In this study we investigate the origins of this apparent lack of long-term order by processing the time intervals between successive R wave features of the electrocardiogram to obtain a symbolic description of all characteristic patterns of premature beats observed in a clinical data set. These characteristic patterns are found to be 1) associated with fixed ranges of heart rate over periods of many hours and 2) organized into an interwoven fractal structure that corresponds to the sequence of mode-locked states predicted by a nonlinear mathematical model. The apparent randomness of transitions from one pattern to another results from the normal fluctuations in heart rate which can sample many such patterns on a minute-by-minute basis.

scholarly journals Long-Term Forecasting of Death in the Neonatal ICU using Heart Rate Characteristics Monitoring and Clinical Data

2011 ◽  
Vol 70 ◽  
pp. 37-37
Author(s):  
J R Moorman ◽  
W A Carlo ◽  
J Kattwinkel ◽  
R L Schelonka ◽  
P J Porcelli ◽  
...  
Keyword(s):  
Heart Rate ◽  
Clinical Data ◽  
Neonatal Icu ◽  
Long Term Forecasting

scholarly journals Construction of intensity-duration-frequency (IDF) curves for precipitation with annual maxima data in Rwanda, Central Africa

2013 ◽  
Vol 35 ◽  
pp. 1-5 ◽  
Author(s):  
G. R. Demarée ◽  
H. Van de Vyver
Keyword(s):  
Central Africa ◽  
Fixed Time ◽  
Data Sets ◽  
Time Intervals ◽  
Data Set ◽  
Probabilistic Information ◽  
Idf Curves ◽  
Intensity Duration Frequency ◽  
Term Data

Abstract. Detailed probabilistic information on the intensity of precipitation in Central Africa is highly needed in order to cope with the risk analysis of natural hazards. In the mountainous areas of Rwanda land slides frequently occur and might cause a heavy toll in human lives. The establishment of Intensity-Duration-Frequency curves for precipitation in Central Africa remains a difficult task as adequate long-term data sets for short aggregation times are usually not available. In 1962 recording raingauges were installed at several stations in Rwanda. According to the climatological procedures in use at that time in Congo, Rwanda and Burundi, maximum monthly and annual precipitation depths for fixed-time durations of 15, 30, 45, 60 and 120 min were determined from the rainfall charts. The data set is completed by the monthly and annual daily precipitation extremes from the non-recording raingauge at the stations. The authors used the dataset to establish the IDF-curves for precipitation at 3 stations in Rwanda having more than 20 yr of operation. The fixed-hour intervals of multiple 15 min require the use of a technique converting data from fixed-time intervals into data of arbitrary starting intervals. Therefore, the van Montfort technique was used.

A proposed algorithm for analysing heart sounds and calculating their time intervals

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Abdulrahman K. Eesee ◽  
Hassan M. Qassim ◽  
Mothanna Sh. Aziz
Keyword(s):  
Heart Rate ◽  
Clinical Assessment ◽  
Crucial Role ◽  
Heart Sounds ◽  
Time Intervals ◽  
Data Set ◽  
Performance Accuracy ◽  
Free Data

AbstractHeart sounds play a crucial role in the clinical assessment of patients. Stethoscopes are used for detecting heart sounds and diagnosing potential abnormal conditions. However, several parameters of the cardiac sounds cannot be extracted by traditional stethoscopes. This paper presents a proposed algorithm based on peaks detection. Besides its ability of filtering the heart sounds signals, the time intervals of these sounds in addition to the heart rate were calculated by the proposed algorithm in an efficient way. Signals of the heart sounds from two sources were used to evaluate the efficiency of the algorithm. The first source was the data recorded from 14 participants, whereas the second source was the free data set sponsored by PASCAL. The algorithm showed different performance accuracy for detecting the main heart sounds based on the source of the data used in the study. The accuracy was 93.6% when using the data recorded from the first source, whereas it was 76.194% for the data of the second source.

scholarly journals Using Flexible Curved Noncontact Active Electrodes to Monitor Long-Term Heart Rate Variability

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Ji-Jer Huang ◽  
Zhe-Lin Cai
Keyword(s):  
Heart Rate ◽  
Time Domain ◽  
Healthy Subjects ◽  
Measurement Accuracy ◽  
Standard System ◽  
Heart Rate Monitoring ◽  
Average Sensitivity ◽  
Time Intervals ◽  
Ecg Signals

The purpose of this study is to utilize flexible curved noncontact active electrodes to develop a nonperception, long-term, and wireless heart rate monitoring system. This study also verified the functions and capabilities of the system and provided information on physiological parameters recorded during our tests. Our system was used in tandem with a commercially standard measurement system; both systems were used to measure ECG signals on 10 healthy subjects under the simulated home and office scenarios. We verified the R-peak measurement accuracy of our system and used T-tests to analyze the data collected by both systems; our system reached an average sensitivity value of 0.983 and an average positive predictive value of 0.991 over several different scenarios where R-peak measurements were also highly accurate. The R-R time intervals of our system were highly consistent with the standard system. The correlation coefficient calculated reached almost one, and the differences between the two systems mostly fell within the ±10 ms range. Further study of the HRV time-domain parameters under four different scenarios showed no significant differences in most HRV parameters compared to the measurements by the standard system. We also used our system to record long-term heart rate signals.

Rotational Characteristics of the Green Solar Corona: 1947-1991

1994 ◽  
Vol 144 ◽  
pp. 139-141 ◽  
Author(s):  
J. Rybák ◽  
V. Rušin ◽  
M. Rybanský
Keyword(s):  
Solar Corona ◽  
World Wide ◽  
Rotation Period ◽  
Original Data ◽  
Coronal Emission ◽  
Time Intervals ◽  
Data Set ◽  
The World ◽  
Coronal Emission Line ◽  
Homogeneous Data

AbstractFe XIV 530.3 nm coronal emission line observations have been used for the estimation of the green solar corona rotation. A homogeneous data set, created from measurements of the world-wide coronagraphic network, has been examined with a help of correlation analysis to reveal the averaged synodic rotation period as a function of latitude and time over the epoch from 1947 to 1991.The values of the synodic rotation period obtained for this epoch for the whole range of latitudes and a latitude band ±30° are 27.52±0.12 days and 26.95±0.21 days, resp. A differential rotation of green solar corona, with local period maxima around ±60° and minimum of the rotation period at the equator, was confirmed. No clear cyclic variation of the rotation has been found for examinated epoch but some monotonic trends for some time intervals are presented.A detailed investigation of the original data and their correlation functions has shown that an existence of sufficiently reliable tracers is not evident for the whole set of examinated data. This should be taken into account in future more precise estimations of the green corona rotation period.

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