THE INFLUENCE OF CARDIOTOCOGRAM SIGNAL FEATURE SELECTION METHOD ON FETAL STATE ASSESSMENT EFFICACY

Cardiotocographic (CTG) monitoring is a method of assessing fetal state. Since visual analysis of CTG signal is difficult, methods of automated qualitative fetal state evaluation on the basis of the quantitative description of the signal are applied. The appropriate selection of learning data influences the quality of the fetal state assessment with computational intelligence methods. In the presented work we examined three different feature selection procedures based on: principal components analysis, receiver operating characteristics and guidelines of International Federation of Gynecology and Obstetrics. To investigate their influence on the fetal state assessment quality the benchmark SisPorto dataset and the Lagrangian support vector machine were used

Zmienność morfologii wektora elektrokardiogramu. Analiza z cyklu na cykl

W pracy przedstawiono nową metodę analizy z cyklu na cykl w dziedzinie czasowo-częstotliwościowej morfologii wektora EKG. Na przykładowych rejestracjach EKG wysokiej rozdzielczości wskazano nowe możliwości diagnostyczne wynikające z odmiennych sposobów synchronizacji kolejnych cykli serca, odpowiednio załamkiem R i T. Zaproponowano nowy sposób liczbowego określania zmienności kształtu wektora QRS i T przy pomocy tzw. dyspersji kształtu

Zmienność morfologii wektora elektrokardiogramu. Analiza z cyklu na cykl

W pracy przedstawiono nową metodę analizy z cyklu na cykl w dziedzinie czasowo-częstotliwościowej morfologii wektora EKG. Na przykładowych rejestracjach EKG wysokiej rozdzielczości wskazano nowe możliwości diagnostyczne wynikające z odmiennych sposobów synchronizacji kolejnych cykli serca, odpowiednio załamkiem R i T. Zaproponowano nowy sposób liczbowego określania zmienności kształtu wektora QRS i T przy pomocy tzw. dyspersji kształtu

Rigid spheres in Riemannian spaces

Choice of an appropriate (3+1)-foliation of spacetime or a (2+1)-foliation of the Cauchy space, leads often to a substantial simplification of various mathematical problems in General Relativity Theory. We propose a new method to construct such foliations. For this purpose we define a special family of topological two-spheres, which we call "rigid spheres". We prove that there is a four-parameter family of rigid spheres in a generic Riemannian three-manifold (in case of the flat Euclidean three-space these four parameters are: 3 coordinates of the center and the radius of the sphere). The rigid spheres can be used as building blocks for various ("spherical", "bispherical" etc.) foliations of the Cauchy space. This way a supertranslation ambiguity may be avoided. Generalization to the full 4D case is discussed. Our results generalize both the Huang foliations (cf. \cite{LHH}) and the foliations used by us (cf. \cite{JKL}) in the analysis of the two-body problem.Comment: 23 page

On ε -insensitive simplification of fuzzy rules for fetal distress assessment

Objective: The work introduces -insensitive distance based approach to simplification (by reducing the rules number) of the fuzzy classifier rule base. To obtain premises of the initial rules, a modified clustering with pairs of -hyperballs procedure is used. The goal of the presented solutions is to achieve high quality support for fetal distress assessment, based on cardiotocographic (CTG) signals classification with a reduced number of fuzzy rules. Methods: In the presented rule base simplification solution, two rules are considered similar (or contradictory) when the distances between their premises do not exceed the assumed value of . The proposed simplification process consists of two phases: the first with combining similar rules into representative rules, and the second (optional) with the removal of contradictory rules. In addition, two methods of determining conclusions for representative rules are considered: a representative rule retains the original (unchanged) conclusion, or from the conclusions of similar rules the one with the highest absolute value is chosen. In the introduced clustering with pairs of -hyperballs the sizes of object classes are taken into account, to reduce the potential adverse impact of the unbalanced classes in the considered research material. In experiments, two reference assessments for CTG signals based on the retrospective fetal state evaluation were considered. Results and conclusions: In the two-stage classification, the modified clustering outperformed the original procedure in terms of classification sensitivity and the QI index being the geometric mean of sensitivity and specificity. Among the examined rule base simplification methods, we consider the best to be the one based only on combining similar rules, with the unchanged value of conclusion for a representative rule. With the smallest number of rules (after simplification), an increased sensitivity, and in the case of pH-based reference assessment also increased QI value is obtained. Moreover, the achieved sensitivity and QI are higher in comparison to the reference methods and values reported in literature. Significance and main impact: The results confirmed the effectiveness of the -insensitive distance rule base simplification. The proposed methods can be applied to any fuzzy rules with premise membership functions with a defined center. Therefore, we believe that this work may have a positive impact on other studies concerning fuzzy rule-based systems.Web of Science179art. no. 11505