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883. Capacity building to support forest management in protective forests of SloveniaKristina Sever, Milan Kobal, Matjaž Guček, Andrej Breznikar, Aleš Poljanec, 2025, objavljeni povzetek znanstvenega prispevka na konferenci Ključne besede: protective forest, adaptive forest management, Forest Living Lab, natural hazard mitigation, marteloscope
Objavljeno v DiRROS: 01.10.2025; Ogledov: 255; Prenosov: 114
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886. Construction of exceptional copositive matricesTea Štrekelj, Aljaž Zalar, 2025, izvirni znanstveni članek Povzetek: An $n \times n$ symmetric matrix $A$ is copositive if the quadratic form $x^TAx$ is nonnegative on the nonnegative orthant ${\mathbb R}^n_{\ge 0}$. The cone of copositive matrices contains the cone of matrices which are the sum of a positive semidefinite matrix and a nonnegative one and the latter contains the cone of completely positive matrices. These are the matrices of the form $BB^T$ for some $n \times r$ matrix $B$ with nonnegative entries. The above inclusions are strict for $n\ge 5$. The first main result of this article is a free probability inspired construction of exceptional copositive matrices of all sizes $\ge 5$ i.e., copositive matrices that are not the sum of a positive semidefinite matrix and a nonnegative one. The second contribution of this paper addresses the asymptotic ratio of the volume radii of compact sections of the cones of copositive and completely positive matrices. In a previous work by Klep and the authors, it was shown that, by identifying symmetric matrices naturally with quartic even forms, and equipping them with the $L^2$ inner product and the Lebesgue measure, the ratio of the volume radii of sections with a suitably chosen hyperplane is bounded below by a constant independent of $n$ as $n$ tends to infinity. In this paper, we complement this result by establishing an analogous bound when the sections of the cones are unit balls in the Frobenius inner product.
Ključne besede: copositive matrix, completely positive matrix, positive polynomial, sum of squares, convex cone
Objavljeno v DiRROS: 01.10.2025; Ogledov: 223; Prenosov: 92
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887. On reduced Hamilton walksAleksander Malnič, Rok Požar, 2026, izvirni znanstveni članek Povzetek: A Hamilton walk in a finite graph is a walk, either open or closed, that traverses every vertex at least once. Here, we introduce Hamilton walks that are reduced in the sense that they avoid immediate backtracking: a reduced Hamilton walk never traverses the same edge forth and back consecutively. While every connected graph admits a Hamilton walk, existence of a reduced Hamilton walk is not guaranteed for all graphs. However, we prove that a reduced Hamilton walk does exist in a connected graph with minimal valency at least $2$. Furthermore, given such a graph on $n$ vertices, we present an $O(n^2)$-time algorithm that constructs a reduced Hamilton walk of length at most $n(n+3)/2$. Specifically, for a graph belonging to a family of regular expander graphs, we can find a reduced Hamilton walk of length at most $c(6n−2)\log n+2n$, where $c$ is a constant independent of $n$.
Ključne besede: algorithm, Hamilton walk, nonstandard metric, reduced walk
Objavljeno v DiRROS: 01.10.2025; Ogledov: 168; Prenosov: 79
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888. Deformations of an affine Gorenstein toric pairMatej Filip, 2026, izvirni znanstveni članek Povzetek: We consider deformations of a pair $(X,\partial X)$, where $X$ is an affine toric Gorenstein variety and $\partial X$ is its boundary. We compute the tangent and obstruction space for the corresponding deformation functor and for an admissible lattice degree $m$ we construct the miniversal deformation of $(X,\partial X)$ in degrees $-km$, for all $k\in{\mathbb N}$. This in particular generalizes Altmann's construction of the miniversal deformation of an isolated Gorenstein toric singularity to an arbitrary non-isolated Gorenstein toric singularity. Moreover, we show that the irreducible components of the reduced miniversal deformation are in one to one correspondence with maximal Minkowski decompositions of the polytope $P\cap(m=1)$, where $P$ is the lattice polytope defining $X$.
Ključne besede: deformation theory, toric singularities
Objavljeno v DiRROS: 01.10.2025; Ogledov: 186; Prenosov: 65
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889. Taxonomy, phylogeny, and size evolution in the spider genus Megaraneus Lawrence, 1968 (Araneae: Araneidae)Klemen Čandek, Eva Turk, Pedro de Souza Castanheira, Kuang-Ping Yu, Matjaž Gregorič, Volker W. Framenau, Ingi Agnarsson, Matjaž Kuntner, 2025, izvirni znanstveni članek Povzetek: Among terrestrial animals, spiders exhibit the most striking examples of sexual size dimorphism (SSD) but better understanding of its evolution requires improved taxonomy and phylogeny. Many sexually dimorphic spiders lack adequate description, phylogenetic placement, and natural history observations. In South Africa, we documented the natural history of a poorly known spider, Megaraneus gabonensis (Lucas, 1858), with extreme, female-biased SSD (eSSD, female:male approximately 4:1). Here, we redescribe M. gabonensis, place Megaraneus Lawrence, 1968 phylogenetically for the first time, assess whether the observed eSSD represents an independent evolutionary origin, and test whether the macroevolutionary pattern is better explained by male dwarfism or female gigantism. The recovered phylogenetic placement of Megaraneus in the araneid ‘backobourkiines’, a clade previously considered as restricted to East Asia and Australasia, extends the range of this clade to the Afrotropics. We find that eSSD was present in the common ancestor of the ‘backobourkiines’, with further increases in female body length occurring independently in Megaraneus, Backobourkia Framenau, Dupérré, Blackledge & Vink, 2010, and the currently misplaced Parawixia dehaani (Doleschall, 1859). We conclude that the evolution of eSSD reflects a complex pattern of sex-specific size changes across spider phylogeny, but that in Megaraneus it results from female gigantism.
Ključne besede: sexual size dimorphism, backobourkiines, trait evolution, South Africa
Objavljeno v DiRROS: 30.09.2025; Ogledov: 274; Prenosov: 108
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890. Deregulations of DNA damage-responsive genes, genes involved in the endocrine system, in an advanced in vitro 3D zebrafish hepatic cell model after exposure to Bisphenol A (BPA) and its emerging alternatives BPAF, BPAP and BPPH : version v1Alja Štern, Špela Rozman, Bojana Žegura, 2025, zaključena znanstvena zbirka raziskovalnih podatkov Povzetek: Bisphenol AF (BPAF), Bisphenol AP (BPAP), and Bisphenol PH (BPPH) are being introduced into consumer products to replace BPA and are subsequently detected in ecosystems. This study investigates the genotoxic and endocrine-disruptive potential of these emerging bisphenols using a 3D in vitro liver spheroid model derived from Danio rerio (ZFL cell line), on the transcriptional level. The selected genes targeted DNA damage response pathways (TP53, NER, BER) and endocrine-related signalling (Table 1). ZFL spheroids were prepared by a force floating method as described by Štampar et al. (2019)1. Four-day-old ZFL spheroids were exposed to BPA (50 and 200 µM), BPAF (25 and 100 µM), BPAP (25 and 100 µM), and BPPH (10 and 50 µM) for 24 (Table 2) and 96 (Table 3) hours. Following exposure, total RNA was extracted using the RNeasy® Mini Kit (Qiagen, Germany). RNA quality and quantity were assessed prior to reverse transcription (Applied Biosystems, USA), followed by gene-specific preamplification (TATAA PreAmp GrandMasterMix, Tataa Biocenter, Sweden). Gene expression analysis was performed using TaqMan Gene Expression Assays (Applied Biosystems, USA) on the Fluidigm One 48.48 Dynamic Array IFC microfluidic system as described by Štern et al. (2024)2. The generated data was analysed using the Fluidigm Gene Expression Analysis Software and with a free-accessible web program, quantGenious3. The difference in gene expression greater than 1.5-fold was considered a biologically important up/downregulation (relative expression >1.5 or <0.66, respectively). Statistically significant differences were analysed using ANOVA and Dunnett’s multiple comparison test in GraphPad Prism v9 (GraphPad Software, San Diego, CA, USA).
Ključne besede: bisphenols, genotoxicity, endocrine disruption, ZFL spheroids, gene expression, data
Objavljeno v DiRROS: 30.09.2025; Ogledov: 264; Prenosov: 158
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