BACKGROUND-Variations in the ventricular response interval (VRI) during atrial fibrillation (AF) may be reduced in patients with adverse clinical outcomes. The properties of VRI dynamics associated with prognosis remain undetermined. METHODS AND RESULTS-In 107 patients with chronic AF (age, 64+/-9 years), we analyzed a 24-hour ambulatory ECG for VRI variability (SD, SD of successive differences...

1. Introduction. Diaphony (see Zinterhof [13] and Kuipers and Nieder-reiter [6, Exercise 5.27, p. 162]) is a numerical quantity that measures the irregularity of the distribution of sequences in the s-dimensional unit cube [0, 1[

We wish to discriminate spike sequences based on the degree of irregularity. For this purpose, we search for a rational expressions of quadratic functions of consecutive interspike intervals that efficiently measures spiking irregularity. Under natural assumptions, the functional form of the coefficient can be parameterized by a single parameter. The parameter is determined so as to maximize th...

We consider only finite undirected graphs without loops or multiple edges. For terminology and notation not defined here we refer the reader to Bondy and Murty’s textbook [6]. In this note we investigate irregularity measures of graphs. A graph is regular if all its vertices have the same degree, otherwise it is irregular. However, it is of interest to measure how irregular it is. Several appro...

Malignant melanoma, a skin cancer, manifests itself as a dark lesion, most often with an irregular boundary. The degree of irregularity is an important diagnostic indicator. This paper presents a new measure of irregularity using Hidden Markov Models (HMMs) based on the Weibull probability distribution. The measure was tested on 98 skin lesions of which 16 were malignant melanoma. The ROC analy...

Two new shape measures for quantifying the degree of convexity are described. When applied to assessment of skin lesions they are shown to be an effective indicator of malignancy, outperforming Lee et al.’s OII scale-space based irregularity measure. In addition, the new measures were applied to the classification of mammographic masses and lung field boundaries and were shown to perform well r...

The purpose of this work is to explore and quantify physical metrics of breast tumors in both magnetic resonance imaging (MRI) and breast tomosynthesis (BT) images, and relate these metrics to pathophysiological and histopathological ndings. An analysis of breast specimens containing tumors will be employed to determine BT metrics of interest. These metrics will then be applied to patient image...

The aim of this paper is to evaluate the evolution of irregularity and variability of airflow (AF) signals as sleep apnoea-hypopnoea syndrome (SAHS) severity increases in children. We analyzed 501 AF recordings from children 6.2 ± 3.4 years old. The respiratory rate variability (RRV) signal, which is obtained from AF, was also estimated. The proposed methodology consisted of three phases: (i) e...

Meteorological observing networks are nearly always irregularly distributed in space. This irregularity generally has an adverse impact on objective analysis and must be accounted for when designing an analysis scheme. Unfortunately, there has been no completely satisfactory measure of the degree of irregularity, which is of particular significance when designing artificial sampling networks fo...