How the Outliers Influence the Quality of Clustering?

In this article, we evaluate the efficiency and performance of two clustering algorithms: AHC (Agglomerative Hierarchical Clustering) and K-Means. We are aware that there are various linkage options and distance measures that influence the clustering results. We assess the quality of clustering using the Davies-Bouldin and Dunn cluster validity indexes. The main contribution of this research is to verify whether the quality of clusters without outliers is higher than those with outliers in the data. To do this, we compare and analyze outlier detection algorithms depending on the applied clustering algorithm. In our research, we use and compare the LOF (Local Outlier Factor) and COF (Connectivity-based Outlier Factor) algorithms for detecting outliers before and after removing 1%, 5%, and 10% of outliers. Next, we analyze how the quality of clustering has improved. In the experiments, three real data sets were used with a different number of instances.

Qualitative Data Clustering to Detect Outliers.

Detecting outliers is a widely studied problem in many disciplines, including statistics, data mining, and machine learning. All anomaly detection activities are aimed at identifying cases of unusual behavior compared to most observations. There are many methods to deal with this issue, which are applicable depending on the size of the data set, the way it is stored, and the type of attributes and their values. Most of them focus on traditional datasets with a large number of quantitative attributes. The multitude of solutions related to detecting outliers in quantitative sets, a large and still has a small number of research solutions is a problem detecting outliers in data containing only qualitative variables. This article was designed to compare three different categorical data clustering algorithms: K-modes algorithm taken from MacQueen's K-means algorithm and the STIRR and ROCK algorithms. The comparison concerned the method of dividing the set into clusters and, in particular, the outliers detected by algorithms. During the research, the authors analyzed the clusters detected by the indicated algorithms, using several datasets that differ in terms of the number of objects and variables. They have conducted experiments on the parameters of the algorithms. The presented study made it possible to check whether the algorithms similarly detect outliers in the data and how much they depend on individual parameters and parameters of the set, such as the number of variables, tuples, and categories of a qualitative variable.

Exploration of Outliers in If-Then Rule-Based Knowledge Bases.

The article presents both methods of clustering and outlier detection in complex data, such as rule-based knowledge bases. What distinguishes this work from others is, first, the application of clustering algorithms to rules in domain knowledge bases, and secondly, the use of outlier detection algorithms to detect unusual rules in knowledge bases. The aim of the paper is the analysis of using four algorithms for outlier detection in rule-based knowledge bases: Local Outlier Factor (LOF), Connectivity-based Outlier Factor (COF), K-MEANS, and SMALLCLUSTERS. The subject of outlier mining is very important nowadays. Outliers in rules If-Then mean unusual rules, which are rare in comparing to others and should be explored by the domain expert as soon as possible. In the research, the authors use the outlier detection methods to find a given number of outliers in rules (1%, 5%, 10%), while in small groups, the number of outliers covers no more than 5% of the rule cluster. Subsequently, the authors analyze which of seven various quality indices, which they use for all rules and after removing selected outliers, improve the quality of rule clusters. In the experimental stage, the authors use six different knowledge bases. The best results (the most often the clusters quality was improved) are achieved for two outlier detection algorithms LOF and COF.

The influence of p02, BE, BB parameters of perinatally obtained cord blood on quantity of obtained cells and focus on the perfect donor criteria.

The aim of the study was to analyze the influence of oxygene partial pressure (p02), base excess (BE) and buffer base (BB) parameters of cord blood obtained perinatally on quantity of obtained cells and focus on the perfect donor criteria. The study included 50 pregnant women aged between 18 and 38 years in which spontaneous labors and elective cesarean sections were performed. Umbilical cord blood was collected immediately after the women were delivered of newborns. The cells were analyzed in the Polish Stem Cells Bank in Warsaw. In the study group of patients different stem cells viability levels did not differ significantly in terms of pO2, BB and BE level, however, there was a trend that the higher the viability the lower BE value. The experiment showed also that the cord blood (CB) oxygenation scope is vitally important for the CB cells viability.

Maternal predictors and quality of umbilical cord blood units.

The aim of the study was to determine the relationship between the maternal age at delivery and selected properties of the cord blood stem cells. The study included 50 pregnant women aged between 18 and 38 years in which spontaneous labors or elective cesarean sections were performed. Umbilical cord blood was collected immediately after the women were delivered of newborns. The samples were analyzed in the Polish Stem Cells Bank in Warsaw. The highest mean WBC level (p < 0.05) was observed in the umbilical blood collected from patients aged 35 years and more. Similarly, the highest mean cell viability was observed in the umbilical cord blood collected from patients aged 35 and more. There were no statistically significant correlations between the CD34+ cells count and mean cell viability in the umbilical cord blood and the maternal age. With the significance level at p < 0.001, the females after spontaneous labor revealed a visibly higher WBC level than patients after a cesarean section. The higher mean WBC concentration (24.95 thousand/µl) was observed in the umbilical cord blood of patients aged 35 and more after spontaneous labors. In the same group, the umbilical cord blood was also characterized by the highest mean cell viability (98.72%). The number of nucleated cells in the umbilical cord blood collected in the perinatal period increases together with the maternal age. In the course of physiological spontaneous labors, the collected umbilical cord blood has more nucleated cells as compared with elective caesarian sections.

[The influence of pH and pCO2 levels of umbilical cord blood obtained perinatally on selected parameters of stem cells]. / Wplyw pH i pCO2 krwi pepowinowej uzyskiwanej okoloporodowo na wybrane parametry komórek macierzystych.

OBJECTIVE: The aim of the study was to demonstrate a correlation between pH and pCO2 levels in umbilical cord blood and the quality of the harvested material. Additionally the effect of pH and pCO2 on the number of cord blood CD34+ cells and their vitality was analyzed. MATERIAL AND METHODS: The study included 50 pregnant women after vaginal delivery at term or elective cesarean section. Umbilical cord blood was collected immediately after birth. The probes were analyzed at the Polish Stem Cell Bank in Warsaw. RESULTS: The number of CD34+ cells ranged from 0.1-0.2 in white blood cells count over 12 thousand/ml and pH of > 7.3. If pH ranged between 7.35-7.40, the number of CD34+ was 0.3-0.4. The highest number of CD34+ cells was noted for pH of 7.30-7.35 and amounted to 0.4-0.5. Analysis of stem cell vitality showed that the highest level, over 98%, was obtained when pH was < 7.3 and > or = 7.4. The study revealed the viability of stem cells to drop to 97-98% at pH level of 7.3-7.4. Low values of CD34+ (0.01-0.09) were related to pCO2 of > 40.0 mmHg. For pCO2 < 38 mmHg, the value of CD34+ cells was 0.2-0.3%, which is relatively high. However when pCO2 was > or = 38 mmHg, the number of CD34+ ranged between 0.1-0.2. CONCLUSIONS: Viability of the umbilical cord stem cells increases along with the decrease of pH and pCO2 levels. The mode of delivery does not influence the viability of the stem cells.

Sexuality of Disabled Athletes Depending on the Form of Locomotion.

The main purpose of this study was to determine sexuality of disabled athletes depending on the form of locomotion. The study included 170 disabled athletes, aged between 18 and 45. The entire population was divided into 3 research groups depending on the form of locomotion: moving on wheelchairs (n=52), on crutches (n=29) and unaided (n=89). The research tool was a questionnaire voluntarily and anonymously completed by the respondents of the research groups. The questionnaire was composed of a general part concerning the socio-demographic conditions, medical history, health problems, a part dedicated to physical disability as well as the Polish version of the International Index of Erectile Function (IIEF) and the Female Sexual Function Index (FSFI) evaluating sexual life. STATISTICA 10.0 for Windows was used in the statistical analysis. Subjects moving on crutches were significantly older than ones moving on wheelchairs and unaided (34.41 ±11.00 vs. 30.49 ±10.44 and 27.99 ±10.51 years, respectively) (p=0.018). Clinically significant erectile dysfunctions were most often diagnosed in athletes moving on wheelchairs (70.27%), followed by athletes moving on crutches and moving unaided (60% and 35.42%, respectively; p=0.048). Clinical sexual dysfunctions were diagnosed on a similar level among all female athletes. It was concluded that the form of locomotion may determine sexuality of disabled men. Males on wheelchair revealed the worst sexual functioning. Female athletes moving on wheelchairs, on crutches and moving unaided were comparable in the aspect of their sexual life.

Sexual Health of Polish Athletes with Disabilities.

The purpose of this study was to determine sexual functioning of Polish athletes with disabilities (including paralympians). The study encompassed 218 people with physical disabilities, aged between 18 and 45 (149 men and 69 women). The entire research population was divided into three groups: Polish paralympians (n = 45), athletes with disabilities (n = 126) and non-athletes with disabilities (n = 47). The quality of sexual life of Polish paralympians was measured by using the Polish version of Female Sexual Function Index and International Index of Erectile Function. Clinically significant erectile dysfunctions were most often diagnosed in non-athletes (83.33%) with 50% result of severe erectile dysfunctions, followed by athletes and paralympians with comparable results of 56.98% and 54.17% respectively (p = 0.00388). Statistically significant clinical sexual dysfunctions concerned lubrication, orgasm as well as pain domains, and prevailed among female non-athletes (68.42%, 68.42% and 57.89%). Practising sports at the highest level has a favourable effect on the sexuality of men and women with physical disabilities. Men with physical disabilities manifest more sexual disorders than women, an aspect which should be considered by health-care professionals working with people with disabilities.