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1.
Lipoprotein(a) as a risk factor in a cohort of hospitalised cardiovascular patients : A retrospective clinical routine data analysis
David Šuran, Tadej Završnik, Peter Kokol, Marko Kokol, Andreja Sinkovič, Franjo Naji, Jernej Završnik, Helena Blažun Vošner, Vojko Kanič, 2023, original scientific article

Abstract: Lipoprotein(a) (Lp(a)) is a well-recognised risk factor for ischemic heart disease (IHD) and calcific aortic valve stenosis (AVS). Methods: A retrospective observational study of Lp(a) levels (mg/dL) in patients hospitalised for cardiovascular diseases (CVD) in our clinical routine was performed. The Lp(a)-associated risk of hospitalisation for IHD, AVS, and concomitant IHD/AVS versus other non-ischemic CVDs (oCVD group) was assessed by means of logistic regression. Results: In total of 11,767 adult patients, the association with Lp(a) was strongest in the IHD/AVS group (eβ = 1.010, p < 0.001), followed by the IHD (eβ = 1.008, p < 0.001) and AVS group (eβ = 1.004, p < 0.001). With increasing Lp(a) levels, the risk of IHD hospitalisation was higher compared with oCVD in women across all ages and in men aged ≤75 years. The risk of AVS hospitalisation was higher only in women aged ≤75 years (eβ = 1.010 in age < 60 years, eβ = 1.005 in age 60–75 years, p < 0.05). Conclusions: The Lp(a)-associated risk was highest for concomitant IHD/AVS hospitalisations. The differential impact of sex and age was most pronounced in the AVS group with an increased risk only in women aged ≤75 years.
Keywords: acute myocardial infarction, aortic valve stenosis, atherosclerosis, cardiovascular diseases, cardiovascular risk, ischemic heart disease, lipoprotein(a), postmenopausal women
Published in DKUM: 12.06.2024; Views: 14; Downloads: 0
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2.
Značilnosti igre v napadu proti conski obrambi v rokometu : diplomsko delo
Marko Žuran, 2024, undergraduate thesis

Abstract: V diplomskem delu smo se osredotočili predvsem na tipične kombinacije, ki jih rokometne ekipe uporabljajo pri svojih taktičnih izvedbah proti različnim conskim obrambam. Ker se rokometna igra ves čas razvija in spreminja, smo se odločili za pregled nekaterih kombinacij, ki se uporabljajo v sodobnem rokometu. Pomagali smo si predvsem s sodobno tehnologijo, videovsebinami in strokovno literaturo. Najprej smo te temeljito pregledali in opazili, kako se rokomet skozi čas igra, razvija in kakšni so trendi razvoja – vsaka rokometna ekipa ima svoj način tehnično-taktične priprave. Za uspešnost igre v napadu je pomembno poznati značilnosti posamezne conske obrambe, zato smo poudarek dali predvsem na dominantni conski obrambi v tem trenutku 5 : 1 in 6 : 0. Vsako izmed njih smo predstavili, prikazali dobre in slabe lastnosti obrambe. Tako smo s pridobljenim znanjem lahko opisali značilnosti določene obrambe, kje so šibke točke in na podlagi tega pripravili pravilne smernice taktike napadanja. Najpomembnejše je, da so kombinacije enostavne za razumevanje in enostavne za pripravo. Z njimi potem lažje pridemo do zaključnih strelov in ugodnejšega položaja za strel na gol. Kombinacije so pomembne za začetek napadanja, saj so vsi igralci nevarni za dosego gola. V igri rokometa je pomembna tudi improvizacija napadanja, saj nikoli ne vemo, kako bo odreagirala obramba na določeno kombinacijo in nas želela presenetiti. Predvsem je pomembno, da igralce navajamo na neprestano nevarno igro za strel na gol. Tako bo kombinacija dobila smisel in bo uspešno izvedena.
Keywords: rokomet, obramba, napad, taktika
Published in DKUM: 11.06.2024; Views: 37; Downloads: 0
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3.
Determinants of collective failure in excitable networks
Uroš Barać, Matjaž Perc, Marko Gosak, 2023, original scientific article

Abstract: We study collective failures in biologically realistic networks that consist of coupled excitable units. The networks have broad-scale degree distribution, high modularity, and small-world properties, while the excitable dynamics is determined by the paradigmatic FitzHugh–Nagumo model. We consider different coupling strengths, bifurcation distances, and various aging scenarios as potential culprits of collective failure. We find that for intermediate coupling strengths, the network remains globally active the longest if the high-degree nodes are first targets for inactivation. This agrees well with previously published results, which showed that oscillatory networks can be highly fragile to the targeted inactivation of low-degree nodes, especially under weak coupling. However, we also show that the most efficient strategy to enact collective failure does not only non-monotonically depend on the coupling strength, but it also depends on the distance from the bifurcation point to the oscillatory behavior of individual excitable units. Altogether, we provide a comprehensive account of determinants of collective failure in excitable networks, and we hope this will prove useful for better understanding breakdowns in systems that are subject to such dynamics.
Keywords: collective behavior, excitable media, complex network, neuronal dynamics
Published in DKUM: 10.06.2024; Views: 52; Downloads: 0
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4.
Pojavnost ribarjenja v slovenskih podjetjih : diplomsko delo visokošolskega študijskega programa Informacijska varnost
Aleš Matjaž, 2024, undergraduate thesis

Abstract: Spletno ribarjenje je vrsta kibernetskega napada, pri katerem napadalec načrtno zavede žrtev, da napadalcu razkrije različne občutljive podatke. Z napadi si napadalci prilastijo zaupne podatke, ki predvsem za podjetja predstavljajo veliko vrednost. Napadalci pri napadih ribarjenja uporabljajo metode socialnega inženiringa, pri tem pa po raznih e-poštnih sporočilih, SMS-i, glasovnimi sporočili in mnogo drugimi metodami zavajajo žrtev. Ciljne tarče napadov ribarjenja niso le posamezniki, temveč tudi vsa podjetja, ki težko zagotovijo celovito informacijsko varnost in s tem preprečijo napad. V diplomskem delu je bila opravljena raziskava o pojavnosti napadov ribarjenja v slovenskih podjetjih, v katero je bilo zajetih 77 podjetij, ki delujejo na ozemlju Slovenije. Ugotovitve kažejo, da so podjetja v Sloveniji konstantno na udaru napadov ribarjenja, prav tako pa so uspešna pri njihovem preprečevanju. Z nenehnim izobraževanjem zaposlenih, ob urejanju varnostne politike in ob urejenem oddelku za informacijsko varnost so podjetja uspešna pri preprečevanju uspešnosti napadov ribarjenja, na kar kaže tudi podatek, da 93 % vprašanih še ni utrpelo finančne izgube ob napadih ribarjenja. Slovenska podjetja so najpogosteje tarča napadov ribarjenja po e-pošti, sledijo napadi po SMS-sporočilih in napadi glasovnega ribarjenja.
Keywords: ribarjenje, napadi, informacijska varnost, podjetja, diplomske naloge
Published in DKUM: 10.06.2024; Views: 21; Downloads: 0
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5.
The role of anaplerotic metabolism of glucose and glutamine in insulin secretion : a model approach
Vladimir 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: 70; Downloads: 1
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6.
Assessing different temporal scales of calcium dynamics in networks of beta cell populations
Jan Zmazek, Maša Skelin, Rene Markovič, Jurij Dolenšek, Marko Marhl, Andraž Stožer, Marko Gosak, 2021, original scientific article

Abstract: Beta cells within the pancreatic islets of Langerhans respond to stimulation with coherent oscillations of membrane potential and intracellular calcium concentration that presumably drive the pulsatile exocytosis of insulin. Their rhythmic activity is multimodal, resulting from networked feedback interactions of various oscillatory subsystems, such as the glycolytic, mitochondrial, and electrical/calcium components.How these oscillatory modules interact and affect the collective cellular activity, which is a prerequisite for proper hormone release, is incompletely understood. In the present work, we combined advanced confocal Ca2+ imaging in fresh mouse pancreas tissue slices with time series analysis and network science approaches to unveil the glucosedependent characteristics of different oscillatory components on both the intra- and inter-cellular level. Our results reveal an interrelationship between the metabolically driven low-frequency component and the electrically driven high-frequency component, with the latter exhibiting the highest bursting rates around the peaks of the slow component and the lowest around the nadirs. Moreover, the activity, as well as the average synchronicity of the fast component, considerably increased with increasing stimulatory glucose concentration, whereas the stimulation level did not affect any of these parameters in the slow component domain. Remarkably, in both dynamical components, the average correlation decreased similarly with intercellular distance, which implies that intercellular communication affects the synchronicity of both types of oscillations. To explore the intra-islet synchronization patterns in more detail, we constructed functional connectivity maps. The subsequent comparison of network characteristics of different oscillatory components showed more locally clustered and segregated networks of fast oscillatory activity, while the slow oscillations were more global, resulting in several long-range connections and a more cohesive structure. Besides the structural differences, we found a relatively weak relationship between the fast and slow network layer, which suggests that different synchronization mechanisms shape the collective cellular activity in islets, a finding which has to be kept in mind in future studies employing different oscillations for constructing networks.
Keywords: islets of Langerhans, beta cell network, calcium oscillations, multimodal activity analysis, confocal imaging, functional connectivity, multiplex network
Published in DKUM: 06.06.2024; Views: 67; Downloads: 4
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7.
Role of cAMP in double switch of glucagon secretion
Jan Zmazek, Vladimir Grubelnik, Rene Markovič, Marko Marhl, 2021, original scientific article

Abstract: Glucose metabolism plays a crucial role in modulating glucagon secretion in pancreatic alpha cells. However, the downstream effects of glucose metabolism and the activated signaling pathways influencing glucagon granule exocytosis are still obscure. We developed a computational alpha cell model, implementing metabolic pathways of glucose and free fatty acids (FFA) catabolism and an intrinsically activated cAMP signaling pathway. According to the model predictions, increased catabolic activity is able to suppress the cAMP signaling pathway, reducing exocytosis in a Ca2+ -dependent and Ca2+ independent manner. The effect is synergistic to the pathway involving ATPdependent closure of KATP channels and consequent reduction of Ca2+. We analyze the contribution of each pathway to glucagon secretion and show that both play decisive roles, providing a kind of "secure double switch". The cAMP-driven signaling switch plays a dominant role, while the ATP-driven metabolic switch is less favored. The ratio is approximately 60:40, according to the most recent experimental evidence.
Keywords: pancreatic alpha cell, glucagon, cAMP, mathematical model, diabetes, cellular bioenergetics
Published in DKUM: 06.06.2024; Views: 28; Downloads: 0
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8.
Vpliv mešanja in kompleksnih interakcij na razvoj sodelovanja v igri javnih dobrin : doktorska disertacija po skandinavskem modelu
Maja Duh, 2024, doctoral dissertation

Abstract: Razumevanje razvoja sodelovanja med posamezniki, ki so v osnovi sebični, je eden najpomembnejših izzivov današnjega časa, ki vzbuja zanimanje raziskovalcev iz različnih področij. V ta namen znanstveniki integrirajo evolucijsko teorijo iger z naprednimi metodami s področja znanosti o omrežjih in metodami statistične fizike. V doktorski disertaciji smo s pomočjo takega interdisciplinarnega pristopa raziskali, kako različni tipi mobilnosti oziroma mešanj igralcev na različnih interakcijskih mrežah vplivajo na evolucijo in promocijo sodelovanja v igri javnih dobrin. V ta namen smo raziskovalno delo razdelili v štiri sklope. V prvem delu smo pokazali, da uvedba mešanja igralcev v igri javnih dobrin na regularnem omrežju omogoči prehod iz stanja sistema vpetega v prostorsko mrežo v stanje dobro mešane populacije, kjer struktura interakcijske mreže več nima bistvenega pomena na evolucijsko dinamiko. Izkaže se, da je v primeru mešanja najbližjih sosedov za to potrebna večja frekvenca mešanja kot pri mešanju naključnih igralcev. Nadalje smo pokazali, da oba načina mešanja zavirata evolucijski uspeh kooperatorjev. V nadaljevanju smo raziskavo razširili na področje kompleksnih omrežij, ki podajajo realnejši opis interakcij med posamezniki. V drugem delu doktorske disertacije smo tako igro javnih dobrin postavili na naključno omrežje, vpeto v hiperbolični prostor in v model vključili asortativno in disasortativno mešanje igralcev. Ugotovili smo, da oba tipa mešanja zavirata razvoj sodelovanja ne glede na arhitekturo omrežja, a je vpliv disasortativnega mešanja večji v primerjavi z asortativnim mešanjem. Naslednji tip interakcijske mreže, s katerim se še boljše opišemo realne interakcije, so večplastna soodvisna omrežja, ki smo jih v raziskave vključili v naših naslednjih dveh raziskavah. Soodvisnost med dvema omrežjema smo vpeljali s koristnostno funkcijo in pokazali, da lahko parameter pristranskosti učinkovito vpliva na raven sodelovanja. Pokazali smo, da asortativne medmrežne povezave med dvema skalno neodvisnima omrežjema spodbujajo kooperacijo v igri javnih dobrin v nekoliko večji meri kot naključne in disasortativne povezave. V zadnjem sklopu raziskav smo prišli do presenetljivih zaključkov. Rezultati mešanja na dvoplastnem soodvisnem omrežju, kjer posamezna plast predstavlja naključno omrežje, vpeto v hiperbolični prostor, kažejo, da lahko mešanje znotraj posamezne plasti omrežja, kjer je sodelovanje prvotno uspešno, močno oslabi evolucijsko uspešnost kooperatorjev na tej plasti, medtem ko jo za določene vrednosti normaliziranega sinergijskega faktorja spodbuja sodelovanje na drugi plasti omrežja. Rezultati doktorske disertacije predstavljajo pomemben prispevek k znanstvenemu raziskovanju na področju razumevanja razvoja in vzdrževanja sodelovanja, s poudarkom na uporabi evolucijske teorije iger, kompleksnih omrežij in mobilnosti igralcev.
Keywords: evolucijska teorija iger, igra javnih dobrin, sodelovanje, mešanje, kompleksna omrežja, večplastna omrežja, simulacije Monte Carlo
Published in DKUM: 05.06.2024; Views: 35; Downloads: 1
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9.
Zinka Zorko in raziskovanje slovenskih narečij
Marko Jesenšek, 2023, published scientific conference contribution

Abstract: Akademikinja Zinka Zorko je svoje življenje posvetila znanstvenemu, raziskovalnemu in pedagoškemu delu. Študentom je posredovala znanje z izrazito osebno noto, ki jo je uveljavila za najbolj priljubljeno predavateljico na mariborski slovenistiki. Raziskovala je koroške, štajerske in prekmurske govore, njeno znanstveno delo pa je spodbudilo nastanek mariborske dialektološke šole. V članku je predstavljena njena »jezikovna opo‑ roka«, ki zavezuje in zahteva odgovorno nadaljevanje dela na področju dialektologije.
Keywords: slovenska narečja, dialektologija, slovenščina
Published in DKUM: 31.05.2024; Views: 97; Downloads: 1
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10.
The effect of forskolin and the role of Epac2A during activation, activity, and deactivation of beta cell networks
Maša Skelin, Jurij Dolenšek, Lidija Križančić Bombek, Viljem Pohorec, Marko Gosak, Marjan Rupnik, Andraž Stožer, 2023, original scientific article

Abstract: Beta cells couple stimulation by glucose with insulin secretion and impairments in this coupling play a central role in diabetes mellitus. Cyclic adenosine monophosphate (cAMP) amplifies stimulus-secretion coupling via protein kinase A and guanine nucleotide exchange protein 2 (Epac2A). With the present research, we aimed to clarify the influence of cAMP-elevating diterpene forskolin on cytoplasmic calcium dynamics and intercellular network activity, which are two of the crucial elements of normal beta cell stimulus-secretion coupling, and the role of Epac2A under normal and stimulated conditions. To this end, we performed functional multicellular calcium imaging of beta cells in mouse pancreas tissue slices after stimulation with glucose and forskolin in wild-type and Epac2A knock-out mice. Forskolin evoked calcium signals in otherwise substimulatory glucose and beta cells from Epac2A knock-out mice displayed a faster activation. During the plateau phase, beta cells from Epac2A knock-out mice displayed a slightly higher active time in response to glucose compared with wild-type littermates, and stimulation with forskolin increased the active time via an increase in oscillation frequency and a decrease in oscillation duration in both Epac2A knock-out and wild-type mice. Functional network properties during stimulation with glucose did not differ in Epac2A knock-out mice, but the presence of Epac2A was crucial for the protective effect of stimulation with forskolin in preventing a decline in beta cell functional connectivity with time. Finally, stimulation with forskolin prolonged beta cell activity during deactivation, especially in Epac2A knock-out mice.
Keywords: pancreas, tissue slices, beta cells, calcium imaging, amplifying pathway, forskolin, Epac2A KO, intercellular network
Published in DKUM: 27.05.2024; Views: 93; Downloads: 2
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