801. Weighted Padovan graphsVesna Iršič Chenoweth, Sandi Klavžar, Gregor Rus, Elif Tan, 2025, izvirni znanstveni članek Povzetek: Weighted Padovan graphs $\Phi^{n}_{k}$, $n \geq 1$, $\lfloor \frac{n}{2} \rfloor \leq k \leq \lfloor \frac{2n-2}{3} \rfloor$, are introduced as the graphs whose vertices are all Padovan words of length $n$ with $k$ $1$s, two vertices being adjacent if one can be obtained from the other by replacing exactly one $01$ with a $10$. By definition, $\sum_k |V(\Phi^{n}_{k})|=P_{n+2}$, where $P_n$ is the $n$th Padovan number. Two families of graphs isomorphic to weighted Padovan graphs are presented. The order, the size, the degree, the diameter, the cube polynomial, and the automorphism group of weighted Padovan graphs are determined. It is also proved that they are median graphs.
Ključne besede: Padovan sequence, weighted Padovan graph, integer partition, median graphs
Objavljeno v DiRROS: 20.10.2025; Ogledov: 167; Prenosov: 72
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802. A model theoretic perspective on matrix ringsIgor Klep, Marcus Tressl, 2025, izvirni znanstveni članek Povzetek: In this paper natural necessary and sufficient conditions for quantifier elimination of matrix rings $M_n(K)$ in the language of rings expanded by two unary functions, naming the trace and transposition, are identified. This is used together with invariant theory to prove quantifier elimination when $K$ is an intersection of real closed fields. On the other hand, it is shown that finding a natural definable expansion with quantifier elimination of the theory of $M_n({\mathbb C})$ is closely related to the infamous simultaneous conjugacy problem in matrix theory. Finally, for various natural structures describing dimension-free matrices it is shown that no such elimination results can hold by establishing undecidability results.
Ključne besede: model theory, quantifier elimination, matrix rings, trace, decidability, free analysis, simultaneous conjugacy problem
Objavljeno v DiRROS: 20.10.2025; Ogledov: 202; Prenosov: 95
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803. Advanced Monte Carlo analysis of ex-vessel neutron dosimetry for cycle 25 of Krško nuclear power plantTanja Goričanec, Benjamin Barbarič, Vladimir Radulović, Dušan Čalič, Luka Snoj, Marjan Kromar, 2026, izvirni znanstveni članek Povzetek: This paper presents the results of Monte Carlo neutron transport calculations performed for the containment building of the Krško Nuclear Power Plant. The calculations were performed using the Monte Carlo N-Particle Transport Code (MCNP) in combination with the ADVANTG hybrid code to speed up the convergence of the results outside the reactor core. The paper focuses on the analysis of the Ex-Vessel Neutron Dosimetry (EVND) program conducted during the 25th fuel cycle at the Krško nuclear power plant with the irradiation of gradient chains and multiple foil sensor sets. The calculated reaction rates at the dosimeter locations are in good agreement with the measured values. However, deviations were observed in the thermal part of the neutron energy spectrum which cannot be neglected, and investigated were some possible reasons for the deviations: nuclear data, concrete material composition, concrete geometry, sensor position and impurities in sample.
Ključne besede: neutron transport, ex-vessel neutron dosimeters, neutron
Objavljeno v DiRROS: 20.10.2025; Ogledov: 180; Prenosov: 76
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804. Agro-morphological characteristics of selected sweet potato (Ipomoea batatas L.) varieties from organic farming and their genetic backgroundNataša Kunstelj, Lovro Sinkovič, Barbara Pipan, Mohamed Neji, Vladimir Meglič, 2025, izvirni znanstveni članek Ključne besede: allele polymorphisms, genetic diversity, organic farming, plant descriptor, SSR marker
Objavljeno v DiRROS: 18.10.2025; Ogledov: 214; Prenosov: 105
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805. Environmental drivers of scale morphology in a Canary Island lizard across 3700 m of elevationK. Kelly, Rodrigo Megía-Palma, Urban Dajčman, S. Blázquez-Castro, M. R. Pie, Anamarija Žagar, 2025, izvirni znanstveni članek Povzetek: The skin serves as the outermost barrier between an organism and its environment and fulfills numerous physiological and ecological functions. In lizards, scale morphology is an important adaptive trait that mediates responses to environmental influences such as extreme temperatures, ultraviolet radiation, drought and anthropogenic disturbances. Our study provides an analysis of the environmental drivers influencing intraspecific variation in the scale ecomorphology of the island lizard Gallotia galloti across 3700 m of elevation, taking into account different macro- and microclimatic conditions and varying degrees of anthropogenic influences and across three body regions: dorsal, ventral and tail. We found several correlations suggesting multiple dependencies of scale morphology on environmental variation. The positive correlation between July temperature and wind speed at 3 cm above the ground and dorsal scale density showed that more densely packed scales are associated with hotter and drier environments. This could possibly be related to the thermoregulatory and hydroregulatory function of the skin, since the dorsal side of the body is most exposed. Higher sun exposure was associated with larger dorsal and tail scales, indicating a possible photoprotective function. Ventral scales are not exposed to the pressure of solar radiation and wind. Accordingly, ventral scales showed no correlation with these factors, but we found that a higher ratio of day-to-night temperature variation relative to seasonal changes (isothermality) was associated with a higher density of ventral scales. The human footprint index positively correlated with larger and denser ventral (and not dorsal or tail) scales. Overall, our results illustrate the complexity of responses of scale morphology to different environmental variations. Evidently, G. galloti exhibits morphological diversity in response to climatic conditions and urbanization, highlighting the potential ecological significance of scale size variation. Future research should investigate the genetic basis and possible effects of climate change on scale morphology.
Ključne besede: scale morphology, climatic conditions, human footprint, adaptation, skin, elevational gradient, zoology
Objavljeno v DiRROS: 17.10.2025; Ogledov: 223; Prenosov: 120
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806. Exploring marine microbial diversity : an overview of representative sampling strategiesZrinka Ljubešić, Marija Gligora Udovič, Donata Overlingė, Filip Grgurević, Füsun Akgül, Ariola Bacu, Ana R. Díaz Marrero, Dragana Drakulović, Stefano Fazi, Susana P. Gaudêncio, Anamarija Kolda, Lucie Novoveská, Ivo Safarik, Joana Sousa, Olivier Thomas, Maggie M. Reddy, Giovanna Cristina Varese, Marlen Ines Vasquez, Tihomir Makovec, Ana Rotter, 2025, pregledni znanstveni članek Ključne besede: biodiscovery, marine microbial diversity, sampling protocol, sample preservation and storage, biorepositories, cultures, marine biology
Objavljeno v DiRROS: 17.10.2025; Ogledov: 274; Prenosov: 116
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807. An infinite family of simple graphs underlying chiral, orientable reflexible and non-orientable rotary mapsIsabel Hubard, Primož Potočnik, Primož Šparl, 2026, izvirni znanstveni članek Povzetek: In this paper, we provide the first known infinite family of simple graphs, each of which is the skeleton of a chiral map, a skeleton of a reflexible map on an orientable surface, as well as a skeleton of a reflexible map on a non-orientable surface. This family consists of all lexicographic products $C_n[mK_1]$, where $m \ge 3, n=sm$, with $s$ an integer not divisible by $4$. This answers a question posed by Wilson in 2002.
Ključne besede: rotary maps, chiral maps, orientable reflexible maps, non-orientable rotary maps
Objavljeno v DiRROS: 17.10.2025; Ogledov: 186; Prenosov: 87
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808. Cross-positive linear maps, positive polynomials and sums of squaresIgor Klep, Klemen Šivic, Aljaž Zalar, 2026, izvirni znanstveni članek Povzetek: A $\ast$-linear map $\Phi$ between matrix spaces is cross-positive if it is positive on orthogonal pairs $(U,V)$ of positive semidefinite matrices in the sense that $\langle U,V \rangle:={\rm tr}(UV)=0$ implies $\langle\Phi (U),V \rangle \ge 0$, and is completely cross-positive if all its ampliations $I_n \otimes \Phi$ are cross-positive. (Completely) cross-positive maps arise in the theory of operator semigroups, where they are sometimes called exponentially-positive maps, and are also important in the theory of affine processes on symmetric cones in mathematical finance. To each $\Phi$ as above a bihomogeneous form is associated by $p_\Phi (x,y)=y^T\Phi (xx^T)y$. Then $\Phi$ is cross-positive if and only if $p_\Phi$ is nonnegative on the variety of pairs of orthogonal vectors $\{(x,y) | x^Ty = 0\}$. Moreover, $\Phi$ is shown to be completely cross-positive if and only if $p_\Phi$ is a sum of squares modulo the principal ideal $(x^Ty)$. These observations bring the study of cross-positive maps into the powerful setting of real algebraic geometry. Here this interplay is exploited to prove quantitative bounds on the fraction of cross-positive maps that are completely cross-positive. Detailed results about cross-positive maps $\Phi$ mapping between $3\times3$ matrices are given. Finally, an algorithm to produce cross-positive maps that are not completely cross-positive is presented.
Ključne besede: positive polynomials, sum of squares, positive maps, completely positive maps, one-parameter semigroups, convex cones
Objavljeno v DiRROS: 17.10.2025; Ogledov: 176; Prenosov: 94
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