21. Conformality of minimal transversals of maximal cliquesEndre Boros, Vladimir Gurvich, Martin Milanič, Dmitry Tikhanovsky, Yushi Uno, 2026, izvirni znanstveni članek Opis: Given a hypergraph ℋ, the dual hypergraph of ℋis the hypergraph of all minimal transversals of ℋ. A hypergraph is conformal if it is the family of maximal cliques of a graph. In a recent work, Boros, Gurvich, Milanič, and Uno (Journal of Graph Theory, 2025) studied conformality of dual hypergraphs and proved several results related to this property, leading in particular to a polynomial-time algorithm for recognizing graphs in which, for any fixed k, all minimal transversals of maximal cliques have size at most k. In this follow-up work, we provide a novel aspect to the study of graph clique transversals, by considering the dual conformality property from the perspective of graphs. More precisely, we study graphs for which the family of minimal transversals of maximal cliques is conformal. Such graphs are called clique dually conformal (CDC for short). It turns out that the class of CDC graphs is a rich generalization of the class of P4-free graphs. As our main results, we completely completely characterize CDC graphs within the families of triangle-free graphs and split graphs. Both characterizations lead to polynomial-time recognition algorithms. Generalizing the fact that every P4-free graph is CDC, we also show that the class of CDC graphs is closed under substitution, in the strong sense that substituting a graph H for a vertex of a graph G results in a CDC graph if and only if both G and H are CDC.
Ključne besede: maximal clique, minimal transversal, conformal hypergraph, triangle-free graph, split graph
Objavljeno v RUP: 16.12.2025; Ogledov: 247; Prenosov: 2
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22. Induced minor models : Structural properties and algorithmic consequencesNicolas Bousquet, Clément Jean Dallard, Maël Dumas, Claire Hilaire, Martin Milanič, Anthony Perez, Nicolas Trotignon, 2026, izvirni znanstveni članek Opis: A graph H is an induced minor of G if there exists an induced minor model of H in G, that is, a collection of pairwise disjoint subsets of vertices of G labeled by the vertices of H, each inducing a connected subgraph in G, such that two vertices of H are adjacent if and only if there is an edge in G between the corresponding subsets. In this paper, we investigate structural properties of induced minor models, including bounds on treewidth and chromatic number of the subgraphs induced by minimal induced minor models. As algorithmic applications of our structural results, we make use of recent developments regarding tree-independence number to show that if H is the 4-wheel, the 5-vertex complete graph minus an edge, or a complete bipartite graph K2,q , then there is a polynomial-time algorithm to find in a given graph G an induced minor model of H in G, if there is one. We also develop an alternative polynomial-time algorithm for recognizing graphs that do not contain K2,3 as an induced minor, which revolves around the idea of detecting the induced subgraphs whose presence is forced when the input graph contains K2,3 as an induced minor. It turns out that all these induced subgraphs are Truemper configurations.
Ključne besede: induced minor, treewidth, chromatic number, tree-independence number, Truemper configuration
Objavljeno v RUP: 16.12.2025; Ogledov: 227; Prenosov: 3
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23. On {k}-Roman graphsKenny Bešter Štorgel, Nina Chiarelli, Lara Fernández, J. Pascal Gollin, Claire Hilaire, Valeria Alejandra Leoni, Martin Milanič, 2025, objavljeni znanstveni prispevek na konferenci Opis: For a positive integer k, a {k}-Roman dominating function of a graph G = (V, E) is a function f : V → {0, 1, . . . , k} satisfying f (N(v)) ≥ k for each vertex v ∈ V with f (v) = 0. Every graph G satisfies γ{Rk}(G) ≤ kγ(G), where γ{Rk}(G) denotes the minimum weight of a {k}-Roman dominating function of G and γ(G) is the domination number of G. In this work we study graphs for which the equality is reached, called {k}-Roman graphs. This extends the concept of {k}-Roman trees studied by Wang et al. in 2021 to gen- eral graphs. We prove that for every k ≥ 3, the problem of recognizing {k}-Roman graphs is NP-hard, even when restricted to split graphs. We provide partial answers to the question of which split graphs are {2}-Roman: we characterize {2}-Roman split graphs that can be decomposed with respect to the split join operation into two smaller split graphs and classify the {k}-Roman property within two specific families of split graphs that are prime with respect to the split join operation: suns and their complements.
Ključne besede: graph domination, {k}-Roman domination, {k}-Roman graph, split graph, split join, NP-completeness
Objavljeno v RUP: 16.12.2025; Ogledov: 230; Prenosov: 2
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24. A systematic review and evaluation of measurement instruments assessing the needs, wellbeing, and living environments of older adultsMateja Erce Paoli, Dean Lipovac, Michael David Burnard, 2025, pregledni znanstveni članek Opis: Understanding the built environment’s impact on older adults’ wellbeing necessitates the identification of high-quality measures that capture environmental properties, wellbeing, and needs. Literature searches were conducted to identify instruments that measure (a) objective environmental properties, (b) wellbeing, (c) needs, and (d) environmental perception, which were evaluated using the COSMIN checklist. Another literature search was conducted to explore which instruments are used in studies examining objective and perceived qualities of the environment in relation to wellbeing. Of the 54 instruments evaluated, most showed strong content or construct validity, but weak or unreported test-retest reliability. Structural validity and internal consistency tended to be satisfactory in instruments assessing wellbeing and the intersection of environment and wellbeing. Instruments evaluating needs and the perceived environment generally had poor results in our evaluation. Our review of studies assessing both perceived and objective built environments alongside wellbeing indicates a lack of consistent use of validated instruments for older adult populations. We have identified instruments in each category with mostly sufficient psychometric properties, while the rest require improvement, particularly in terms of structural validity and reliability. Environment evaluation instruments mainly focus on outdoor spaces, leaving indoor spaces underrepresented in literature.
Ključne besede: ageing, questionnaire, objective measurement, subjective evaluation, psychometric properties
Objavljeno v RUP: 03.12.2025; Ogledov: 289; Prenosov: 2
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25. Investigating the degradation of tannin furanic foams in soil environments : experimental insightsJonas Eckardt, Paolo Carletti, Jakub Grzybek, Giancarlo Renella, Gianluca Tondi, 2025, izvirni znanstveni članek Opis: In the search for bio-based alternatives to petroleum-based materials, extensive research has been carried out on tannin- based foams over the last decades, demonstrating their potential use as insulation materials for buildings. These foams have been studied in depth for their chemical and physical properties and were already considered for upscaling. However, concerns remain about the end of their life cycle. While tannin foams can be partially recycled in new tannin foams, reused as ammonia scavenger, or thermally valorised, their impact on soil upon disposal or when potentially used as ammonia mitigators in agriculture remains unclear. This study investigated the degradation dynamics and potential effects of tan- nin furanic polymer on soil health. A decrease in the mass of the tannin foam particles by about 10% within 24 weeks indicated microbial degradation, which was further enhanced by the occurrence of leachable fractions throughout the experiment. Chemically, this degradation was associated with a reduction in carbohydrates and/or furanics, leading to a relative increase in aromatic components, paralleled by increased β-glucosidase activity. Phenol oxidase and arylesterase activities fluctuated depending on time and soil type, suggesting their roles in different stages of phenolic degradation, while catechol oxidase activity either decreased or remained unchanged. Enzymatic activities for FDA and β-glucosidase, indicators of soil health and microbial activity, tendentially increased in the presence of tannin foam, showing that the tested foam had no negative effect on general soil microbial activity.
Ključne besede: tannin furanic foam, soil FDA hydrolase activity, soil β-glucosidase activity, ATR FT-IR
Objavljeno v RUP: 02.12.2025; Ogledov: 271; Prenosov: 2
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26. A classification of Q-polynomial distance-regular graphs with girth 6Štefko Miklavič, 2025, izvirni znanstveni članek Opis: Let Γ denote a Q-polynomial distance-regular graph with diameter D and valency k≥3. In [Homotopy in Q-polynomial distance-regular graphs, Discrete Math., {\bf 223} (2000), 189–206], H. Lewis showed that the girth of Γ is at most 6. In this paper we classify graphs that attain this upper bound. We show that Γ has girth 6 if and only if it is either isomorphic to the Odd graph on a set of cardinality 2D+1, or to a generalized hexagon of order (1,k−1).
Ključne besede: distance-regular graphs, Q-polynomial property, girth
Objavljeno v RUP: 01.12.2025; Ogledov: 1230; Prenosov: 3
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27. Size effect on bending strength and failure modes of finger-jointed timberMohammad Derikvand, Michael David Burnard, Donya Bazyar Khoshroodi, Rok Barbič, Marko Vouk, Andreja Kutnar, 2025, izvirni znanstveni članek Opis: Finger-jointed timber boards for cross-laminated timber production are typically assigned the same characteristic bending strength (fm,j,k) if produced from the same strength class, regardless of differences in their cross-sectional dimensions. To validate the relevance of this approach, this study investigated the effects of cross-sectional dimensions on the bending performance of finger-jointed timber produced from spruce (strength class: C24). A large industrial dataset of 1100 specimens, with seven thicknesses (ranging 20 to 40 mm) and variable widths, were statistically analyzed. The bending tests were performed with a constant span-to-depth ratio (l/h = 18), meaning thinner specimens had a shorter test span. Bending strength was modeled with Bayesian multilevel linear model, and the proportions of three quality-control failure modes (joint interface failure, joint base failure, and outside-joint failure) were analyzed with a zero-one-inflated Dirichlet regression. Based on the results, all groups with n ≥ 100 exceeded the declared fm,j,k of 27.6 MPa, with characteristic strengths of 43.7 MPa (+58.3 %), 40.0 MPa (+45.0 %), and 38.3 MPa (+38.8 %) for the 20-, 30-, and 40-mm thickness groups, respectively. Thinner specimens demonstrated higher bending strength with convincing evidence (pairwise contrasts PD = 100 % with 95 % HDPIs entirely below zero), while width had no credible effect (PD < 95 %). Dirichlet regression revealed shifts in failure mode proportions with varying strength. Higher bending strengths were associated with a higher proportion of joint interface failure. Outside‑joint failure was observed with a higher proportion in lower-strength and thicker specimens. Overall, assigning uniform fm,j,k to various cross-sectional dimensions proved to give adequate safety margins. Beyond the uniform fm,j,k, however, statistical evidence of a size effect on both bending strength and failure modes was observed. The magnitude of the observed size effect reflects the combined influence of increasing thickness and test span under the current quality control bending test regime, which means a coupled change in stressed volume and geometry rather than a pure cross-section scaling effect. These findings are relevant to flatwise four-point bending tests on finger-jointed boards from industrial production made with visually graded C24 spruce with thickness ranging 20 to 40 mm.
Ključne besede: wood, finger joint, strength
Objavljeno v RUP: 18.11.2025; Ogledov: 346; Prenosov: 5
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28. Interlaboratory study of automated sorption measurements in wood : method for correcting systematic errors with the commonly used 0.002% min[sup] -1 stop criterionSamuel L. Zelinka, Samuel V. Glass, Natalia Farkas, Emil Engelund Thybring, Michael Altgen, Lauri Rautkari, Simon F. Curling, Jinzhen Cao, Yujiao Wang, Tina Künniger, Matthew Schwarzkopf, 2025, izvirni znanstveni članek Opis: Many studies that use an automated sorption balance to determine a water vapor sorption isotherm for wood collect data until the moisture content change is less than or equal to 0.002% min−1 (20 µg g−1 min−1). This stop criterion has been claimed to give errors in equilibrium moisture content (EMC) predictions of less than 0.001 g g−1 but over the past 10 years, studies have shown that the actual errors can be greater than 0.01 g g−1 because the measurements are stopped well before equilibrium is reached. Despite the large errors associated with this stop criterion, it remains popular due to the speed at which isotherms can be measured. This paper utilizes data from a worldwide interlaboratory study on automated sorption balances to develop a correction method for estimating EMC of western larch (Larix occidentalis Nutt.) from the moisture content corresponding to the 20 µg g−1 min−1 criterion. The study uses data from 72 relative humidity absorption steps with hold times of 7–10 days from 21 different laboratories and eight different instrument models. EMC is defined based on the inherent mass stability of automated sorption balances determined in the first part of this interlaboratory study. On average the sorption process is less than 80% complete when the 20 µg g−1 min−1 criterion is reached, resulting in a mean absolute error (MAE) of 0.006 g g−1. The correction equation for estimating EMC reduces the MAE to 0.001 g g−1. The analysis presented in this paper, along with the correction equation, can be considered for certain use cases to reduce systematic errors and shorten measurement times.
Ključne besede: water vapor sorption, dynamic vapor sorption, sorption isotherms, equilibrium moisture content, interlaboratory study
Objavljeno v RUP: 14.11.2025; Ogledov: 351; Prenosov: 5
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29. The role of predictability of delivery, and stress and anxiety management in satisfaction with childbirth and postpartum depressionTina Goznik, Ajda Prah, Meta Lavrič, Vita Poštuvan, 2025, izvirni znanstveni članek Opis: In an online cross-sectional study of 371 Slovenian women, depressive symptoms were assessed using the Edinburgh Post- partum Depression Scale, and satisfaction with childbirth – in- cluding quality of care provision and stress and anxiety manage- ment – was measured with the Birth Satisfaction Scale. The prevalence of depression was 27.22% during pregnancy and 21.32% postpartum. Logistic regression identified significant predictors: stress and anxiety management of childbirth (sig- nificant in severe depression), a history of a depressive episode and depressive symptoms during pregnancy. More predictable deliveries were associated with higher satisfaction with childbirth. Results emphasize the importance of routine depression screening, support for stress and anxiety management, while predictable deliveries increase satisfaction with childbirth.
Ključne besede: postpartum depression, satisfaction with childbirth, depression history, stress and anxiety management, antepartum depression, predictability
Objavljeno v RUP: 28.10.2025; Ogledov: 380; Prenosov: 6
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30. A lonelier world after COVID-19 : longitudinal population-based study of well-being, emotional and social loneliness, and suicidal behaviour in SloveniaVita Poštuvan, Nina Krohne, Meta Lavrič, Vanja Gomboc, Diego De Leo, Lucia Rojs, 2024, izvirni znanstveni članek Opis: Background and Objectives: The impact of coronavirus disease 2019 (COVID-19) goes beyond the consequences of the infectious disease, especially as the measures taken to prevent the spread of the virus have had a very profound impact on people’s social relationships and everyday lives. Several studies have investigated these effects, but there is a lack of longitudinal studies in Central Europe. Objective: The aim of our study was to observe changes in well-being, loneliness, and suicidal behaviour before, during, and after the COVID-19 pandemic using the same population-based cohort. Materials and Methods: A representative sample of 444 participants completed online questionnaires at four time points: 2019 (wave 0), 2021 (wave 1), 2022 (wave 2), and 2023 (wave 3). Results: The results show significant changes in the levels of well-being and emotional loneliness over these periods. In particular, emotional loneliness increased during the pandemic, followed by a later decrease. Well-being appeared to increase after pandemic-related restrictions diminished but decreased again one year later. No significant changes concerning social loneliness and suicidal ideation were observed. Conclusions: Our study suggests that the COVID-19 pandemic changed the way in which people perceive their well-being and especially their relationships with others. From the data, we can conclude that people’s worldview is now lonelier than before the pandemic.
Ključne besede: COVID-19, loneliness, mental health, well-being, suicide
Objavljeno v RUP: 20.10.2025; Ogledov: 424; Prenosov: 7
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