An innovative data mining procedure, using clean algorithm and factor analysis, for irregularly sampled temporal environmental data sets

Οι περιβαλλοντικές βάσεις δεδομένων συχνά αντιμετωπίζουν τα προβλήματα της άτακτης δειγματοληψίας στον χρόνο και της έλλειψης μετρήσεων για κάποιες περιόδους. Το γεγονός αυτό εμποδίζει τη χρήση των κλασικών μεθόδων ανάλυσης χρονοσειρών, οι οποίες απαιτούν σταθερό χρονικό βήμα ενώ ταυτόχρονα τα χρονικά κενά εισάγουν δυσκολίες στην χρήση των περισσοτέρων μεθόδων πολυδιάστατης σταπστικής ανάλυσης. Η παρούσα εργασία προτείνει ένα πλήρες μεθοδολογικό σχήμα ανάλυσης χρονικών περιβαλλονπκών δεδομένων με δειγματοληπτική ανομοιογένεια, στο οποίο γίνεται χρήση του αλγορίθμου CLEAN και της Παραγοντικής ανάλυσης (Factor Analysis). Ο αλγόριθμος CLEAN έχει την ικανότητα να αναπλάθει τις αρχικές χρονοσειρές της βάσης δεδομένων χρησιμοποιώντας φασματική ανάλυση και να δημιουργεί καινούργιες με σταθερό χρονικό βήμα και έλλειψη κενών. Λαμβάνει χώρα δηλαδή τόσο συμπλήρωση των κενών τ?/ς βάσης, όσο και «εξυγίανση» της δειγματοληψίας της. Η παραγοντική ανάλυση ομαδοποιεί τις μεταβλητές, ανάλογα με τον περιβαλλοντικό μηχανισμό από τον οποίο κάθε μια ελέγχεται και επιπλέον αποκαλύπτει τη χαρακτηριστική χρονική διακύμανση της κάθε ομάδας. Το συγκεκριμένο μεθοδολογικό σχήμα εφαρμόστηκε με πλήρη επιτυχία σε μια βάση υδροχημικών δεδομένων μεγάλης χρονικής περιόδου (1980-94) στον ποταμό ΣτρυμόναEnvironmental data are often irregularly collected in the time domain due to various reasons which affect the field sampling schedule. As a result, data sets with uneven time step and time periods with no measurements are frequently built. Many problems occur in such data sets when processed owing to that neither statistical nor spectral analysis methods can easily be applied to them without any specific pre-treatment. In our study it is demonstrated a unified methodological scheme especially designed to deal with incomplete and unevenly sampled temporal data sets. This method consists of the CLEAN algorithm and the Factor analysis. The proposed methodology is successfully applied to data sets that belong to two sampling sites of the Greek river Strimona

Sudden Death and Left Ventricular Involvement in Arrhythmogenic Cardiomyopathy

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disorder characterized by myocardial fibrofatty replacement and an increased risk of sudden cardiac death (SCD). Originally described as a right ventricular disease, ACM is increasingly recognized as a biventricular entity. We evaluated pathological, genetic, and clinical associations in a large SCD cohort. METHODS: We investigated 5205 consecutive cases of SCD referred to a national cardiac pathology center between 1994 and 2018. Hearts and tissue blocks were examined by expert cardiac pathologists. After comprehensive histological evaluation, 202 cases (4%) were diagnosed with ACM. Of these, 15 (7%) were diagnosed antemortem with dilated cardiomyopathy (n=8) or ACM (n=7). Previous symptoms, medical history, circumstances of death, and participation in competitive sport were recorded. Postmortem genetic testing was undertaken in 24 of 202 (12%). Rare genetic variants were classified according to American College of Medical Genetics and Genomics criteria. RESULTS: Of 202 ACM decedents (35.4±13.2 years; 82% male), no previous cardiac symptoms were reported in 157 (78%). Forty-one decedents (41/202; 20%) had been participants in competitive sport. The adjusted odds of dying during physical exertion were higher in men than in women (odds ratio, 4.58; 95% CI, 1.54-13.68; P=0.006) and in competitive athletes in comparison with nonathletes (odds ratio, 16.62; 95% CI, 5.39-51.24; P<0.001). None of the decedents with an antemortem diagnosis of dilated cardiomyopathy fulfilled definite 2010 Task Force criteria. The macroscopic appearance of the heart was normal in 40 of 202 (20%) cases. There was left ventricular histopathologic involvement in 176 of 202 (87%). Isolated right ventricular disease was seen in 13%, isolated left ventricular disease in 17%, and biventricular involvement in 70%. Among whole hearts, the most common areas of fibrofatty infiltration were the left ventricular posterobasal (68%) and anterolateral walls (58%). Postmortem genetic testing yielded pathogenic variants in ACM-related genes in 6 of 24 (25%) decedents. CONCLUSIONS: SCD attributable to ACM affects men predominantly, most commonly occurring during exertion in athletic individuals in the absence of previous reported cardiac symptoms. Left ventricular involvement is observed in the vast majority of SCD cases diagnosed with ACM at autopsy. Current Task Force criteria may fail to diagnose biventricular ACM before death