1. Diet of three cryptobenthic clingfish species and the factors influencing itDomen Trkov, Danijel Ivajnšič, Marcelo Kovačić, Lovrenc Lipej, 2024, original scientific article Abstract: Cryptobenthic fish are small benthic fish species that normally live in various hiding places. Due to their large numbers, they are very important for energy transfer to higher trophic levels. However, due to their small size and hidden lifestyle, knowledge about them and their ecology, including their diet, is still limited. Using a non-destructive method based on faecal pellets, we investigated the diet of three clingfish species, Lepadogaster lepadogaster, L. candolii, and Apletodon incognitus, in the shallow northern Adriatic Sea. To better understand the results, we studied the fauna of potential prey in the habitats of the fish studied and also took fish specimens to observe their behaviour in the laboratory. The three species feed predominantly on crustaceans, particularly amphipods, copepods, and decapods. The proportion of the different taxa in the diet depends on the species of clingfish, the size of the specimens, and the size of the prey. In addition, the behaviour of the fish, the home range of the specimens, and the availability of food played an important role. The presence of certain crustacean groups in the environment also determines the occurrence of clingfish of different species and sizes.
Keywords: cryptobenthic fish, clingfish species, diet, diet habits, non-destructive method, faecal pellets, crustaceans, northern Adriatic Sea
Published in DiRROS: 03.10.2024; Views: 15; Downloads: 6
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2. On the 2-rainbow independent domination numbers of some graphsBoštjan Gabrovšek, Aljoša Peperko, Janez Žerovnik, 2023, original scientific article Abstract: By suitably adjusting the tropical algebra technique we compute the rainbow independent domination numbers of several infinite families of graphs including Cartesian products $C_n \Box P_m$ and $C_n \Box C_m$ for all $n$ and $m\le 5$, and generalized Petersen graphs $P(n,2)$ for $n \ge 3$.
Keywords: graph theory, rainbow independent domination number, path algebra, tropical algebra
Published in DiRROS: 03.10.2024; Views: 18; Downloads: 9
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3. Inequalities and equalities on the joint and generalized spectral and essential spectral radius of the Hadamard geometric mean of bounded sets of positive kernel operatorsKatarina Bogdanović, Aljoša Peperko, 2023, original scientific article Abstract: We prove new inequalities and equalities for the generalized and the joint spectral radius (and their essential versions) of Hadamard (Schur) geometric means of bounded sets of positive kernel operators on Banach function spaces. In the case of nonnegative matrices that define operators on Banach sequences we obtain additional results. Our results extend results of several authors that appeared relatively recently.
Keywords: Hadamard-Schur geometric mean, Hadamard-Schur product, joint and generalized spectral radius, essential spectral radius, measure of noncompactness, positive kernel operators, non-negative matrices, bounded sets of operators
Published in DiRROS: 03.10.2024; Views: 17; Downloads: 8
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4. Covering the edges of a graph with trianglesCsilla Bujtás, Akbar Davoodi, Laihao Ding, Ervin Győri, Zsolt Tuza, Donglei Yang, 2025, original scientific article Abstract: In a graph $G$, let $\rho_\triangle(G)$ denote the minimum size of a set of edges and triangles that cover all edges of $G$, and let $\alpha_1(G)$ be the maximum size of an edge set that contains at most one edge from each triangle. Motivated by a question of Erdős, Gallai, and Tuza, we study the relationship between $\rho_\triangle(G)$ and $\alpha_1(G)$ and establish a sharp upper bound on $\rho_\triangle(G)$. We also prove Nordhaus-Gaddum-type inequalities for the considered invariants.
Keywords: edge-disjoint triangles, edge clique covering, Nordhaus-Gaddum inequality
Published in DiRROS: 03.10.2024; Views: 15; Downloads: 9
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5. Vertex-primitive digraphs with large fixityMarco Barbieri, Primož Potočnik, 2024, original scientific article Abstract: The relative fixity of a digraph $\Gamma$ is defined as the ratio between the largest number of vertices fixed by a nontrivial automorphism of $\Gamma$ and the number of vertices of $\Gamma$ .We characterize the vertex-primitive digraphs whose relative fixity is at least $1 \over 3$, and we show that there are only finitely many vertex-primitive digraphs of bounded out-valency and relative fixity exceeding a positive constant.
Keywords: vertex-primitive digraphs, fixity, product action, graphs
Published in DiRROS: 03.10.2024; Views: 33; Downloads: 13
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6. Fast winning strategies for Staller in the Maker-Breaker domination gameCsilla Bujtás, Pakanun Dokyeesun, 2024, original scientific article Abstract: The Maker-Breaker domination game is played on a graph $G$ by two players, called Dominator and Staller, who alternately choose a vertex that has not been played so far. Dominator wins the game if his moves form a dominating set. Staller wins if she plays all vertices from a closed neighborhood of a vertex $v \in V(G)$. Dominator's fast winning strategies were studied earlier. In this work, we concentrate on the cases when Staller has a winning strategy in the game. We introduce the invariant $\gamma'_{\rm SMB}(G)$ (resp., $\gamma_{\rm SMB}(G)$) which is the smallest integer $k$ such that, under any strategy of Dominator, Staller can win the game by playing at most $k$ vertices, if Staller (resp., Dominator) plays first on the graph $G$. We prove some basic properties of $\gamma_{\rm SMB}(G)$ and $\gamma'_{\rm SMB}(G)$ and study the parameters' changes under some operators as taking the disjoint union of graphs or deleting a cut vertex. We show that the inequality $\delta(G)+1 \le \gamma'_{\rm SMB}(G) \le \gamma_{\rm SMB}(G)$ always holds and that for every three integers $r,s,t$ with $2\le r\le s\le t$, there exists a graph $G$ such that $\delta(G)+1 = r$, $\gamma'_{\rm SMB}(G) = s$, and $\gamma_{\rm SMB}(G) = t$. We prove exact formulas for $\gamma'_{\rm SMB}(G)$ where $G$ is a path, or it is a tadpole graph which is obtained from the disjoint union of a cycle and a path by adding one edge between them.
Keywords: domination game, Maker–Breaker game, winning number, Maker-Breaker domination game, closed neighborhood hypergraph
Published in DiRROS: 03.10.2024; Views: 26; Downloads: 10
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7. Comparative simulative analysis and design of single-chain self-assembled protein cagesFei Xiao, Longfei Luo, Xin Liu, Ajasja Ljubetič, Nengzhi Jin, Roman Jerala, Guang Hu, 2024, original scientific article Abstract: Coiled-coil protein origami (CCPO) is a modular strategy for the de novo design of polypeptide nanostructures. It represents a type of modular design based on pairwise-interacting coiled-coil (CC) units with a single-chain protein programmed to fold into a polyhedral cage. However, the mechanisms underlying the self-assembly of the protein tetrahedron are still not fully understood. In the present study, 18 CCPO cages with three different topologies were modeled in silico. Then, molecular dynamics simulations and CC parameters were calculated to characterize the dynamic properties of protein tetrahedral cages at both the local and global levels. Furthermore, a deformed CC unit was redesigned, and the stability of the new cage was significantly improved.
Keywords: chemical structure, conformation, genetics oligomers stability
Published in DiRROS: 03.10.2024; Views: 33; Downloads: 5
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8. A note on the 2-colored rectilinear crossing number of random point sets in the unit squareSergio Cabello, Éva Czabarka, Ruy Fabila-Monroy, Yuya Higashikawa, Raimund Seidel, László Székely, Josef Tkadlec, Alexandra Wesolek, 2024, original scientific article Abstract: Let $S$ be a set of four points chosen independently, uniformly at random from a square. Join every pair of points of $S$ with a straight line segment. Color these edges red if they have positive slope and blue, otherwise. We show that the probability that $S$ defines a pair of crossing edges of the same color is equal to $1/4$. This is connected to a recent result of Aichholzer et al. who showed that by $2$-colouring the edges of a geometric graph and counting monochromatic crossings instead of crossings, the number of crossings can be more than halved. Our result shows that for the described random drawings, there is a coloring of the edges such that the number of monochromatic crossings is in expectation ${1 \over 2} - {7 \over 50}$ of the total number of crossings.
Keywords: arrangement of points, flat, hyperplane
Published in DiRROS: 03.10.2024; Views: 17; Downloads: 12
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9. Conservation of molecular responses upon viral infection in the non-vascular plant Marchantia polymorphaEric Ros-Moner, Tamara Jiménez-Góngora, Luis Villar-Martin, Lana Vogrinec, Víctor M. González-Miguel, Denis Kutnjak, Ignacio Rubio-Somoza, 2024, original scientific article Abstract: After plants transitioned from water to land around 450 million years ago, they faced novel pathogenic microbes. Their colonization of diverse habitats was driven by anatomical innovations like roots, stomata, and vascular tissue, which became central to plant-microbe interactions. However, the impact of these innovations on plant immunity and pathogen infection strategies remains poorly understood. Here, we explore plant-virus interactions in the bryophyte Marchantia polymorpha to gain insights into the evolution of these relationships. Virome analysis reveals that Marchantia is predominantly associated with RNA viruses. Comparative studies with tobacco mosaic virus (TMV) show that Marchantia shares core defense responses with vascular plants but also exhibits unique features, such as a sustained wound response preventing viral spread. Additionally, general defense responses in Marchantia are equivalent to those restricted to vascular tissues in Nicotiana, suggesting that evolutionary acquisition of developmental innovations results in re-routing of defense responses in vascular plants.
Keywords: plant-virus interactions, bryophytes, virome analysis, high-throughput sequencing, virology, pathogenic, innovations, interactions, RNA viruses, plant defense response, botany
Published in DiRROS: 02.10.2024; Views: 43; Downloads: 191
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10. Mutual-visibility in strong products of graphs via total mutual-visibilitySerafino Cicerone, Gabriele Di Stefano, Sandi Klavžar, Ismael G. Yero, 2024, original scientific article Abstract: Let $G$ be a graph and $X\subseteq V(G)$. Then $X$ is a mutual-visibility set if each pair of vertices from $X$ is connected by a geodesic with no internal vertex in $X$. The mutual-visibility number $\mu(G)$ of $G$ is the cardinality of a largest mutual-visibility set. In this paper, the mutual-visibility number of strong product graphs is investigated. As a tool for this, total mutual-visibility sets are introduced. Along the way, basic properties of such sets are presented. The (total) mutual-visibility number of strong products is bounded from below in two ways, and determined exactly for strong grids of arbitrary dimension. Strong prisms are studied separately and a couple of tight bounds for their mutual-visibility number are given.
Keywords: mutual-visibility set, mutual-visibility number, total mutual-visibility set, strong product of graphs
Published in DiRROS: 02.10.2024; Views: 45; Downloads: 26
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