1. Parkinson’s disease non-motor subtypes classification in a group of Slovenian patients : actuarial vs. data-driven approachTimotej Petrijan, Jan Zmazek, Marija Menih, 2023, izvirni znanstveni članek Opis: Background and purpose: The aim of this study was to examine the risk factors, prodromal symptoms, non-motor symptoms (NMS), and motor symptoms (MS) in different Parkinson’s disease (PD) non-motor subtypes, classified using newly established criteria and a data-driven approach.
Methods: A total of 168 patients with idiopathic PD underwent comprehensive NMS and MS examinations. NMS were assessed by the Non-Motor Symptom Scale (NMSS), Montreal Cognitive Assessment (MoCA), Hamilton Depression Scale (HAM-D), Hamilton Anxiety Rating Scale (HAM-A), REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ), Epworth Sleepiness Scale (ESS), Starkstein Apathy Scale (SAS) and Fatigue Severity Scale (FSS). Motor subtypes were classified based on Stebbins’ method. Patients were classified into groups of three NMS subtypes (cortical, limbic, and brainstem) based on the newly designed inclusion criteria. Further, data-driven clustering was performed as an alternative, statistical learning-based classification approach. The two classification approaches were compared for consistency.
Results: We identified 38 (22.6%) patients with the cortical subtype, 48 (28.6%) with the limbic, and 82 (48.8%) patients with the brainstem NMS PD subtype. Using a data-driven approach, we identified five different clusters. Three corresponded to the cortical, limbic, and brainstem subtypes, while the two additional clusters may have represented patients with early and advanced PD. Pearson chi-square test of independence revealed that a priori classification and cluster membership were significantly related to one another with a large effect size (χ2(8) = 175.001, p < 0.001, Cramer’s V = 0.722). The demographic and clinical profiles differed between NMS subtypes and clusters.
Conclusion: Using the actuarial and clustering approach, marked differences between individual NMS subtypes were found. The newly established criteria have potential as a simplified tool for future clinical research of NMS subtypes of Parkinson’s disease.
Ključne besede: Parkinson’s disease, non-motor symptoms subtypes, a priori classification, cluster analysis
Objavljeno v DKUM: 07.04.2025; Ogledov: 0; Prenosov: 2
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2. Corrosion of NiTiDiscs in different seawater environmentsJelena Pješčić-Šćepanović, Gyöngyi Vastag, Špiro Ivošević, Nataša Kovač, Rebeka Rudolf, 2022, izvirni znanstveni članek Opis: This paper gives an approach to the corrosion resistance analysis and changes in the
chemical composition of anNiTi alloy in the shape of a disc, depending on different real seawater
environments. The NiTi discs were analysed after 6 months of exposure in real seawater environments:
the atmosphere, a tidal zone, and seawater. The corrosion tests showed that the highest corrosion rate
for the discs is in seawater because this had the highest value of current density, and the initial disc
had the most negative potential. Measuring the chemical composition of the discs using inductively
coupled plasma and X-ray fluorescence before the experiment and semiquantitative analysis after
the experiment showed the chemical composition after 6 months of exposure. Furthermore, the
applied principal component analysis and cluster analysis revealed the influence of the different
environments on the changes in the chemical composition of the discs. Cluster analysis detected small
differences between the similar corrosive influences of the analysed types of environments during the
period of exposure. The obtained results confirm that PCA can detect subtle quantitative differences
among the corrosive influences of the types of marine environments, although the examined corrosive
influences are quite similar. The applied chemometric methods (CA and PCA) are, therefore, sensitive
enough to register the existence of slight differences among corrosive environmental influences on
the analysed NiTi SMA.
Ključne besede: NiTi discs, corrosion rate, real seawater environment, cluster analysis (CA), principal component analysis (PCA)
Objavljeno v DKUM: 20.03.2025; Ogledov: 0; Prenosov: 6
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3. Big data usage in European Countries : cluster analysis approachMirjana Pejić Bach, Tine Bertoncel, Maja Meško, Daila Suša-Vugec, Lucija Ivančić, 2020, izvirni znanstveni članek Opis: The goal of this research was to investigate the level of digital divide among selected European countries according to the big data usage among their enterprises. For that purpose, we apply the K-means clustering methodology on the Eurostat data about the big data usage in European enterprises. The results indicate that there is a significant difference between selected European countries according to the overall usage of big data in their enterprises. Moreover, the enterprises that use internal experts also used diverse big data sources. Since the usage of diverse big data sources allows enterprises to gather more relevant information about their customers and competitors, this indicates that enterprises with stronger internal big data expertise also have a better chance of building strong competitiveness based on big data utilization. Finally, the substantial differences among the industries were found according to the level of big data usage.
Ključne besede: big data, cluster analysis, digital divide, k-means, enterprise, industry, Europe, quality
Objavljeno v DKUM: 14.01.2025; Ogledov: 0; Prenosov: 3
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4. Synchronization in simplicial complexes of memristive Rulkov neuronsMahtab Mehrabbeik, Sajad Jafari, Matjaž Perc, 2023, izvirni znanstveni članek Opis: Simplicial complexes are mathematical constructions that describe higher-order interactions within the interconnecting elements of a network. Such higher-order interactions become increasingly significant in neuronal networks since biological backgrounds and previous outcomes back them. In light of this, the current research explores a higher-order network of the memristive Rulkov model. To that end, the master stability functions are used to evaluate the synchronization of a network with pure pairwise hybrid (electrical and chemical) synapses alongside a network with two-node electrical and multi-node chemical connections. The findings provide good insight into the impact of incorporating higher-order interaction in a network. Compared to two-node chemical synapses, higher-order interactions adjust the synchronization patterns to lower multi-node chemical coupling parameter values. Furthermore, the effect of altering higher-order coupling parameter value on the dynamics of neurons in the synchronization state is researched. It is also shown how increasing network size can enhance synchronization by lowering the value of coupling parameters whereby synchronization occurs. Except for complete synchronization, cluster synchronization is detected for higher electrical coupling strength values wherein the neurons are out of the completed synchronization state.
Ključne besede: simplicial complex, higher-order network, memristive Rulkov, synchronization, cluster synchronization
Objavljeno v DKUM: 11.09.2024; Ogledov: 37; Prenosov: 9
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5. Association of circulating tumor cells, megakaryocytes and a high immune-inflammatory environment in metastatic breast cancerCvetka Grašič-Kuhar, Silvester Jernej, Marina Mencinger, Tanja Ovčariček, Maja Čemažar, Simona Miceska, Živa Modic, Anamarija Kuhar, Tanja Jesenko, Veronika Kloboves-Prevodnik, 2023, izvirni znanstveni članek Opis: Liquid biopsy is becoming an important source of new biomarkers during the treatment of metastatic cancer patients. Using size-based microfluid technology, we isolated circulating tumor cells (CTCs) from metastatic breast cancer patients to evaluate their presence and cluster formation, as well as the presence of megakaryocytes and immune-inflammatory blood cells, and to correlate their presence with clinicopathological data and overall survival (OS). In total, 59 patients (median age 60.4 years) were included in the study: 62.7% luminal A/B-like, 20.3% HER2-positive, and 17% triple-negative. Our results showed that at least one CTC was present in 79.7% and ≥5 CTCs in 35.2% of the patients. CTC clusters were present in patients with ≥5 CTCs only (in 19.2% of them), and megakaryocytes were present in 52% of all patients. The presence of CTC clusters and megakaryocytes was positively associated with the CTC count. Patients with low pan-inflammatory value (PIV), low systemic immune-inflammatory index (SII), and low relative change from baseline (ΔPIV%, ΔSII%) were associated with significantly higher OS than their counterparts. ΔPIV%, the presence of infection in the last month, and a long duration of metastatic disease were identified as independent prognostic factors for OS. The interplay of CTCs, CTC clusters, megakaryocytes, and PIV needs to be further explored.
Ključne besede: breast cancer, circulating tumor cell, cluster, megakaryocyte, pan-inflammatory value, overall survival
Objavljeno v DKUM: 19.04.2024; Ogledov: 253; Prenosov: 20
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6. Conserved water networks identification for drug design using density clustering approaches on positional and orientational dataJelena Tošović, Domagoj Fijan, Marko Jukič, Urban Bren, 2022, izvirni znanstveni članek Ključne besede: cluster chemistry, hydrogen, ligands, molecules, oxygen
Objavljeno v DKUM: 10.04.2024; Ogledov: 221; Prenosov: 19
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7. Directions for the sustainability of innovative clustering in a countryVito Bobek, Vladislav Streltsov, Tatjana Horvat, 2023, izvirni znanstveni članek Opis: This paper presents potential improvements through utilizing the cyclical nature of clusters by human capital, technology, policies, and management. A historical review of the formation and sustainable development of clusters in the US, Europe, Japan, China, and other regions is carried out to achieve this. The aim was to identify and assess the prominent occurrence cases, the central institutional actors, the indicators of their innovative activity, and the schematics of successful cluster management. The theory section covers current classification methods and typology of innovation-territorial economic associations. Consequently, a regression analysis model is produced to identify the potential dominant success factors in implementing the innovation policy of the most successful innovative clusters. Comments on the influence of these predictors on the competitiveness and level of innovative development of the 50 inspected countries follow. As a result of qualitative and quantitative analysis, an overview of the best world practice, the new vision, and its priorities are proposed to improve the efficiency at the level of management structures of innovation clusters.
Ključne besede: cluster, cluster policy, state policy, regression analysis, institutions, innovation, R&D
Objavljeno v DKUM: 09.04.2024; Ogledov: 306; Prenosov: 129
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8. Acetan and acetan-like polysaccharides: genetics, biosynthesis, structure, and viscoelasticityJanja Trček, Iztok Dogša, Tomaž Accetto, David Stopar, 2021, pregledni znanstveni članek Opis: Bacteria produce a variety of multifunctional polysaccharides, including structural, intracellular, and extracellular polysaccharides. They are attractive for the industrial sector due to their natural origin, sustainability, biodegradability, low toxicity, stability, unique viscoelastic properties, stable cost, and supply. When incorporated into different matrices, they may control emulsification, stabilization, crystallization, water release, and encapsulation. Acetan is an important extracellular water-soluble polysaccharide produced mainly by bacterial species of the genera Komagataeibacter and Acetobacter. Since its original description in Komagataeibacter xylinus, acetan-like polysaccharides have also been described in other species of acetic acid bacteria. Our knowledge on chemical composition of different acetan-like polysaccharides, their viscoelasticity, and the genetic basis for their production has expanded during the last years. Here, we review data on acetan biosynthesis, its molecular structure, genetic organization, and mechanical properties. In addition, we have performed an extended bioinformatic analysis on acetan-like polysaccharide genetic clusters in the genomes of Komagataeibacter and Acetobacter species. The analysis revealed for the first time a second acetan-like polysaccharide genetic cluster, that is widespread in both genera. All species of the Komagataeibacter possess at least one acetan genetic cluster, while it is present in only one third of the Acetobacter species surveyed.
Ključne besede: Komagataeibacter, Acetobacter, extracellular polysaccharide, acetan, acetan-like polysaccharide, acetan genetic cluster, acetan-like polysaccharide genetic cluster, acetan structure, acetan synthesis, acetan viscoelasticity, applications of acetan
Objavljeno v DKUM: 02.09.2022; Ogledov: 605; Prenosov: 23
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10. Multivariate data analysis of natural mineral watersKatja Šnuderl, Marjana Simonič, Jan Mocak, Darinka Brodnjak-Vončina, 2007, izvirni znanstveni članek Opis: Fifty samples of natural mineral waters from springs in Slovenia, Hungary, Germany, Czech Republic and further countries of former Yugoslavia have been analysed. The mass concentration of cations ($Na^+$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, $Fe^{2+}$, $Mn^{2+}$, $NH^+_4$) and anions ($F^-$, $Cl^-$, $I^-$, $NO^-_3$, $SO_4^{2-}$, $HCO_3^-$), the spring temperature, pH, conductivity and carbon dioxide mass concentration have been measured using standard analytical methods. Appropriate statistical methods and different chemometric tools were used to evaluate the obtained data, namely, (i) descriptive statistics, (ii) principal component analysis (PCA), (iii) cluster analysis, and (iv) linear discriminant analysis (LDA). It was confirmed that Slovenian natural mineral water samples differ most from the German ones but are relatively similar to the Czech and Hungarian ones. Water samples from Hungary are similar to waters from the eastern part of Slovenia.
Ključne besede: natural mineral water, ion determination, principal component analysis, cluster analysis, linear discriminant analysis
Objavljeno v DKUM: 21.12.2015; Ogledov: 1866; Prenosov: 103
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