1. Topological features of spike trains in recurrent spiking neural networks that are trained to generate spatiotemporal patternsOleg Maslennikov, Matjaž Perc, Vladimir Nekorkin, 2024, original scientific article Abstract: In this study, we focus on training recurrent spiking neural networks to generate spatiotemporal patterns in the form of closed two-dimensional trajectories. Spike trains in the trained networks are examined in terms of their dissimilarity using the Victor-Purpura distance. We apply algebraic topology methods to the matrices obtained by rank-ordering the entries of the distance matrices, specifically calculating the persistence barcodes and Betti curves. By comparing the features of dierent types of output patterns, we uncover the complex relations between low-dimensional target signals and the underlying multidimensional spike trains.
Keywords: topological features, neural networks, spatiotemporal patterns, nonlinear dynamics
Published in DKUM: 27.11.2024; Views: 0; Downloads: 0
 Full text (6,96 MB)
This document has many files! More... |
2. Predictors of reactive agility in early puberty: a multiple regression gender-stratified studyVladimir Pavlinović, Nikola Foretić, Šime Veršić, Damir Sekulić, Silvester Lipošek, 2022, original scientific article Abstract: Reactive agility (RAG) is a crucial factor of success in sports, but there are practically no
studies dealing with RAG among children. The main aim of this study was to identify predictors
of RAG among early pubescent boys and girls. The participants were primary school boys (n = 73)
and girls (n = 59) aged 11–12. The criterion variable was the originally developed “Triangle” test
of reactive agility (Triangle-RAG). Predictors included anthropometric/body composition indices
(body height, seated height, body mass, and body fat percentage) and motor abilities (10 and 20 m
sprint, broad jump, squat jump, countermovement jump, drop jump, and two tests of change of
direction speed—CODS (Triangle-CODS, and 20 yards)). The results of the univariate analysis
showed that anthropometric/body composition indices were not significantly correlated to TRAG
(0–4% of the common variance), while all motor abilities were significantly associated with TRAG
(7–43% of the common variance) in both genders. Among boys, 64% of the TRAG variance was
explained by multiple regression, with TCODS as the only significant predictor. Among girls, multiple
regression explained 59% of the TRAG-variance with TCODS, countermovement jump, and drop
jump as significant predictors. Differences in multivariate results between genders can be explained
by (i) greater involvement in agility-saturated sports (i.e., basketball, tennis, soccer) in boys, and
(ii) advanced maturity status in girls. The lack of association between anthropometric/body built and
TRAG was influenced by the short duration of the TRAG (3.54 ± 0.4 s). Our findings suggest that
pre-pubescent and early pubescent children should be systematically trained on basic motor abilities
to achieve fundamentals for further developing RAG. Since in this study we observed predictors
including only athletic abilities and anthropometric/body composition, in future studies, other motor
abilities, as well as cognitive, perceptual, and decision-making parameters as potential predictors of
RAG in children should be investigated.
Keywords: non-planned agility, pre-planned agility, anthropometry, children
Published in DKUM: 03.10.2024; Views: 0; Downloads: 8
Full text (584,27 KB)
This document has many files! More... |
3. Experimental characterization and phase-field damage modeling of ductile fracture in AISI 316lVladimir Dunić, Nenad Gubeljak, Miroslav Živković, Vladimir Milovanović, Darko Jagarinec, Nenad Djordjevic, 2024, original scientific article Abstract: ) Modeling and characterization of ductile fracture in metals is still a challenging task in
the field of computational mechanics. Experimental testing offers specific responses in the form of
crack-mouth (CMOD) and crack-tip (CTOD) opening displacement related to applied force or crack
growth. The main aim of this paper is to develop a phase-field-based Finite Element Method (FEM)
implementation for modeling of ductile fracture in stainless steel. (2) A Phase-Field Damage Model
(PFDM) was coupled with von Mises plasticity and a work-densities-based criterion was employed,
with a threshold to propose a new relationship between critical fracture energy and critical total
strain value. In addition, the threshold value of potential internal energy—which controls damage
evolution—is defined from the critical fracture energy. (3) The material properties of AISI 316L steel
are determined by a uniaxial tensile test and the Compact Tension (CT) specimen crack growth test.
The PFDM model is validated against the experimental results obtained in the fracture toughness
characterization test, with the simulation results being within 8% of the experimental measurements.
Keywords: phase-field damage modeling, ductile fracture, crack-tip opening displacement, crack growth, resistance curve, finite element method, simulations
Published in DKUM: 19.09.2024; Views: 0; Downloads: 8
Full text (3,84 MB)
This document has many files! More... |
4. Modelling of dysregulated glucagon secretion in type 2 diabetes by considering mitochondrial alterations in pancreatic ▫$\alpha$▫-cellsVladimir Grubelnik, Rene Markovič, Saška Lipovšek Delakorda, Gerd Leitinger, Marko Gosak, Jurij Dolenšek, Ismael Valladolid-Acebes, Per-Olof Berggren, Andraž Stožer, Matjaž Perc, Marko Marhl, 2020, original scientific article Abstract: Type 2 diabetes mellitus (T2DM) has been associated with insulin resistance and the failure of β-cells to produce and secrete enough insulin as the disease progresses. However, clinical treatments based solely on insulin secretion and action have had limited success. The focus is therefore shifting towards α-cells, in particular to the dysregulated secretion of glucagon. Our qualitative electron-microscopy-based observations gave an indication that mitochondria in α-cells are altered in Western-diet-induced T2DM. In particular, α-cells extracted from mouse pancreatic tissue showed a lower density of mitochondria, a less expressed matrix and a lower number of
cristae. These deformities in mitochondrial ultrastructure imply a decreased efficiency in mitochondrial ATP production, which prompted us to theoretically explore and clarify one of the most challenging problems associated with T2DM, namely the lack of glucagon secretion in hypoglycaemia and its oversecretion at high blood glucose concentrations. To this purpose, we constructed a novel computational model that links α-cell metabolism with their electrical activity and glucagon secretion. Our results show that defective mitochondrial metabolism in α-cells can
account for dysregulated glucagon secretion in T2DM, thus improving our understanding of T2DM pathophysiology and indicating possibilities for new clinical treatments.
Keywords: diabetes, pancreatic alpha cells, glucagon, mitochondrial dysfunction, free fatty acid
Published in DKUM: 03.09.2024; Views: 49; Downloads: 4
Full text (1,60 MB)
This document has many files! More... |
5. Mitochondrial dysfunction in pancreatic alpha and beta cells associated with type 2 diabetes mellitusVladimir Grubelnik, Jan Zmazek, Rene Markovič, Marko Gosak, Marko Marhl, 2020, original scientific article Abstract: Type 2 diabetes mellitus is a complex multifactorial disease of epidemic proportions. It involves genetic and lifestyle factors that lead to dysregulations in hormone secretion and metabolic homeostasis. Accumulating evidence indicates that altered mitochondrial structure, function, and particularly bioenergetics of cells in different tissues have a central role in the pathogenesis of type 2 diabetes mellitus. In the present study, we explore how mitochondrial dysfunction impairs the coupling between metabolism and exocytosis in the pancreatic alpha and beta cells. We demonstrate that reduced mitochondrial ATP production is linked with the observed defects in insulin and glucagon secretion by utilizing computational modeling approach. Specifically, a 30-40% reduction in alpha cells' mitochondrial function leads to a pathological shift of glucagon secretion, characterized by oversecretion at high glucose concentrations and insufficient secretion in hypoglycemia. In beta cells, the impaired mitochondrial energy metabolism is accompanied by reduced insulin secretion at all glucose levels, but the differences, compared to a normal beta cell, are the most pronounced in hyperglycemia. These findings improve our understanding of metabolic pathways and mitochondrial bioenergetics in the pathology of type 2 diabetes mellitus and might help drive the development of innovative therapies to treat various metabolic diseases.
Keywords: pancreatic endocrine cells, mathematical model, mitochondrial dysfunction, cellular bioenergetics, diabetes, glucagon, insulin
Published in DKUM: 03.09.2024; Views: 47; Downloads: 8
Full text (1,63 MB)
This document has many files! More... |
6. Exploring the neglected voices of children in sustainable tourism development : a comparative study in six european tourist destinationsMarko Koščak, Mladen Knežević, Daniel Binder, Antonio Pelaez-Verdet, Cem Işik, Vladimir Mićić, Katarina Borisavljević, Tina Šegota, 2023, original scientific article Abstract: For years, sustainable tourism has commanded the attention of academics and practitioners given its achievement through participatory planning. However, much research in the area has neglected to consider all voices of those (i.e., children) affected by tourism. This study, employing a post-test only experimental design, addresses this gap by including the voices of 498 children from six diverse European destinations concerning perceptions of tourism. Results show that children are willing to express their opinions given the opportunity. Moreover, their attitude towards tourists is negative, while they perceive locals to hold a subordinate position to tourists. In general, this study offers insight into children's attitudes to tourism from the host perspective, demonstrating that there is a unique insider's perspective that needs further research.
Keywords: tourism, sustainable development, environmental protection, children, sustainable tourism, resident attitudes, experiment, involvement
Published in DKUM: 27.08.2024; Views: 95; Downloads: 14
Full text (2,61 MB)
This document has many files! More... |
7. Comparison of emissions depending on the type of vehicle engineVladimír Rievaj, Ján Gaňa, František Synák, 2019, original scientific article Abstract: Road transport is showing growth in the period of globalization. Its task is to transport cargo as well as people to the required location within the shortest possible time and at the lowest price. Thus, road transport plays a crucial role in enabling the globalization to be developed and improved. However, the internal combustion engine hat prevail among the vehicles of freight and passenger transport are the producers of gaseous emissions from the exhaust gases. Many developed countries of the world has committed themselves, inter alia also trough the Paris Agreement, to reduce global warming, and thus to reduce the production of harmful gaseous emissions. The result is the endeavour to replace the internal combustion engine vehicles that burn carbon fuels with the vehicles powered by electric motors consuming electric energy. The reason of such trying claims that road transport using the internal combustion engine vehicles is environmentally aggressive, and the problem would not be solved by implementation of the vehicles with electric motors. Such claim is based on the fact that an electric car does not produce any of primary emissions. From an overall perspective, it is also necessary to take into account secondary emissions that are produced during the electric energy production by which is the vehicle with electric motor powered. The purpose of this article is to assume the possibility of reducing global pollution by replacing the internal combustion engine vehicles with the vehicles powered by electric motors in dependence with producing the emissions during the production of electric energy.
Keywords: electric energy, emissions, electric vehicle, internal combustion engine, global pollution
Published in DKUM: 22.08.2024; Views: 43; Downloads: 8
Full text (409,89 KB)
This document has many files! More... |
8. Cardiovascular comorbidities in COVID-19 : comprehensive analysis of key topicsRene Markovič, Luka Ternar, Tim Trstenjak, Marko Marhl, Vladimir Grubelnik, 2024, original scientific article Keywords: hypertension, hyperglycemia, embolism, thrombosis, heart failure, vascular disease
Published in DKUM: 22.08.2024; Views: 53; Downloads: 10
Full text (1,12 MB)
This document has many files! More... |
9. Urinary incontinence – from childhood onwardsDragana Živković, Damir Franić, Vladimir Kojović, 2022, review article Abstract: Urinary incontinence (UI) is a condition that affects patients of all ages, starting with childhood. There are two peaks in its incidence, i.e., in childhood and another one in patients over 40 years of age, which increases continuously with patient age. It is a condition recognized by the World Health Organization as a set of diseases (International Classification of Diseases, ICD-10), and the International Classification of Functionality recognizes the associated extreme disablement. UI is a major health problem affecting the lives of an estimated 400 million persons worldwide. The global aging of the population will cause rise in the incidence of UI in the future. It is expected that UI itself will become a serious health and social burden for both patients and health service providers. UI can be an isolated problem, or it can be associated and/or aggravated by any associated disorder affecting the nervous system such as myelomeningoceles, Parkinson’s disease or stroke. UI often affects the patient daily life, and it can have repercussions on their physical, financial, social, and emotional well-being. At last, it has a negative influence on their sexual health.
Keywords: Urinary incontinence, stress urinary incontinence, mixed urinary incontinence, dysfunctional voiding
Published in DKUM: 09.07.2024; Views: 99; Downloads: 9
Full text (222,78 KB)
This document has many files! More... |
10. The role of anaplerotic metabolism of glucose and glutamine in insulin secretion : a model approachVladimir Grubelnik, Jan Zmazek, Marko Gosak, Marko Marhl, 2024, original scientific article Abstract: We propose a detailed computational beta cell model that emphasizes the role of anaplerotic metabolism under glucose and glucose-glutamine stimulation. This model goes beyond the traditional focus on mitochondrial oxidative phosphorylation and ATP-sensitive K+ channels, highlighting the predominant generation of ATP from phosphoenolpyruvate in the vicinity of KATP channels. It also underlines the modulatory role of H2O2 as a signaling molecule in the first phase of glucose-stimulated insulin secretion. In the second phase, the model emphasizes the critical role of anaplerotic pathways, activated by glucose stimulation via pyruvate carboxylase and by glutamine via glutamate dehydrogenase. It particularly focuses on the production of NADPH and glutamate as key enhancers of insulin secretion. The predictions of the model are consistent with empirical data, highlighting the complex interplay of metabolic pathways and emphasizing the primary role of glucose and the facilitating role of glutamine in insulin secretion. By delineating these crucial metabolic pathways, the model provides valuable insights into potential therapeutic targets for diabetes.
Keywords: mathematical models, pancreatic beta cell, pyruvate-malate cycle
Published in DKUM: 06.06.2024; Views: 162; Downloads: 7
Full text (5,53 MB)
This document has many files! More... |
