Analysis of heart rate variability (HRV) has become a popular non-invasive tool for assessing the activities of autonomic nervous system. Most of the methods were hired from techniques used for time series analysis. Currently used methods are time domain, frequency domain, geometrical and fractal methods. A new technique, which searches for pattern repeatability in a time series, is proposed fo...

The effect of day-night variations was evaluated in both a female and a male population of healthy subjects. A total of 239 subjects were included in this study, of which 119 male and 120 female. 24 hour Holter recordings were used to analyze heart rate variability. Power spectral indices (total power, low and high frequency power) were calculated together with the nonlinear indices fractal dim...

Entropies are among the most popular and promising complexity measures for biological signal analyses. Various types of entropy measures exist, including Shannon entropy, Kolmogorov entropy, approximate entropy (ApEn), sample entropy (SampEn), multiscale entropy (MSE), and so on. A fundamental question is which entropy should be chosen for a specific biological application. To solve this issue,...

Newell and Vaillancourt (2001) hypothesized that the dimensionality of motor behavior is a function of the level of task performance and the task dynamic. The present study examined high (in-phase), moderate (antiphase) and low (45°, 90°, and 135° relative phase) levels of task performance in bimanual coordination. Estimates of dimensionality were calculated for the component (effector movement...

Sensing the radio frequency bands is an open problem for dynamic spectrum access (DSA) in cognitive radio networks. To address this, numerous signal processing algorithms have been described based on entropy measurement. However, most of the methods lack connectivity between signal detection and appropriateness of the selected entropy. In this work, we propose an optimal detection method which ...

The entropy computation of Gaussian mixture distributions with a large number of components has a prohibitive computational complexity. In this paper, we propose a novel approach exploiting the sphere decoding concept to bound and approximate such entropy terms with reduced complexity and good accuracy. Moreover, we propose an SNR regionbased enhancement of the approximation method to reduce th...

The sport of equestrianism is defined through close horse-rider interaction. However, no consistent baseline parameters currently exist describing the coordination dynamics of horse-rider movement across different equine gaits. The study aims to employ accelerometers to investigate and describe patterns of motor coordination between horse and rider across the equine gaits of walk, rising trot, ...

The aim of our study was to evaluate rapid insulin pulses and insulin secretion regularity in fasting state in lean women with polycystic ovary syndrome (PCOS) in comparison to lean healthy women. PCOS (n=8) and controls (n=7) underwent every minute blood sampling for 60 min. Insulin pulsatility was assessed by deconvolution and insulin secretion regularity by approximate entropy methodology. P...

We develop the general, multivariate case of the Edgeworth approximation of differential entropy, and introduce an approximate formula for Gaussian mixture densities. We use these entropy approximations in a new algorithm for selecting the optimal number of clusters in a data set, and in a new mutual information test with which one can statistically decide whether a distribution can be factoriz...

PURPOSE The purpose of our study was to investigate the functional outcome after anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) and quadrupled semitendinosus and gracilis tendon (ST/G) autografts by evaluating stride-to-stride variability. METHODS Six patients with BPTB and 6 patients with STG ACL reconstruction, 2 years postoperatively, and 6 healthy c...