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312. Symmetries of the Woolly Hat graphsLeah Berman, Sergio Hiroki Koike Quintanar, Elías Mochán, Alejandra Ramos Rivera, Primož Šparl, Steve Wilson, 2024, original scientific article Abstract: A graph is edge-transitive if the natural action of its automorphism group on its edge set is transitive. An automorphism of a graph is semiregular if all of the orbits of the subgroup generated by this automorphism have the same length. While the tetravalent edge-transitive graphs admitting a semiregular automorphism with only one orbit are easy to determine, those that admit a semiregular automorphism with two orbits took a considerable effort and were finally classified in 2012. Of the several possible different "types" of potential tetravalent edge-transitive graphs admitting a semiregular automorphism with three orbits, only one "type" has thus far received no attention. In this paper we focus on this class of graphs, which we call the Woolly Hat graphs. We prove that there are in fact no edge-transitive Woolly Hat graphs and classify the vertex-transitive ones.
Keywords: edge-transitive, vertex-transitive, tricirculant, Woolly Hat graphs
Published in DiRROS: 07.10.2024; Views: 136; Downloads: 59
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313. Transfer learning in robotics : An upcoming breakthrough? A review of promises and challengesNoemie Jaquier, Michael C. Welle, Andrej Gams, Kunpeng Yao, Bernardo Fichera, Aude Billard, Aleš Ude, Tamim Asfour, Danica Kragič, 2024, original scientific article Abstract: Transfer learning is a conceptually-enticing paradigm in pursuit of truly intelligent embodied agents. The core concept— reusing prior knowledge to learn in and from novel situations—is successfully leveraged by humans to handle novel situations. In recent years, transfer learning has received renewed interest from the community from different perspectives, including imitation learning, domain adaptation, and transfer of experience from simulation to the real world, among others. In this paper, we unify the concept of transfer learning in robotics and provide the first taxonomy of its kind considering the key concepts of robot, task, and environment. Through a review of the promises and challenges in the field, we identify the need of transferring at different abstraction levels, the need of quantifying the transfer gap and the quality of transfer, as well as the dangers of negative transfer. Via this position paper, we hope to channel the effort of the community towards the most significant roadblocks to realize the full potential of transfer learning in robotics
Published in DiRROS: 07.10.2024; Views: 138; Downloads: 544
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314. Antiviral respiratory masks with plasma-functionalized polypropylene textiles for optimal adsorption of antiviral substanceMark Zver, David Dobnik, Rok Zaplotnik, Miran Mozetič, Alenka Vesel, Arijana Filipić, Polona Kogovšek, Katja Fric, Alja Štern, Gregor Primc, 2024, original scientific article Abstract: During the COVID-19 pandemic, face masks were the first line of defense against the spread of infection. However, infectious viruses may remain on medical textiles, potentially serving as an additional source of infection. Due to their chemical inertness, many textiles cannot be enhanced with antiviral functionalities. Through treatment with low-pressure gaseous plasma, we have activated the surface of a medical-grade melt-blown, non-woven polypropylene textile so that it can absorb sodium dodecyl sulfate, an antimicrobial surfactant. Within two hours of contact time, the functionalized textile has been able to inactivate over 7 log10 PFU mL−1 of bacteriophage phi6, a surrogate of enveloped viruses such as SARS-CoV-2, and it has retained its antiviral properties for over 100 days. The functionalized material has not disrupted facial mask filtration efficiency or breathability. In addition, the in vitro biocompatibility testing in accordance with ISO 10993-5 for testing of medical devices has demonstrated that the selected formulation causes no adverse effects on the mouse fibroblast cell line L-929. With the treatment processes that have been completed within seconds, the method seems to have great potential to produce antiviral textiles against future outbreaks.
Keywords: surgical face masks, plasma functionalization, antiviral materials, virus filtration, breathability
Published in DiRROS: 07.10.2024; Views: 134; Downloads: 359
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315. Water-templated growth of interfacial superglue polymers for tunable thin films and in situ fluid encapsulationVenkata Subba R. Jampani, Miha Škarabot, Urban Mur, Damien Baigl, Ulrich Jonas, Jan P. F. Lagerwall, Miha Ravnik, Manos Anyfantakis, 2024, original scientific article Abstract: Thin polymer films (TPFs) are indispensable elements in numerous technologies ranging from liquid encapsulation to biotechnology to electronics. However, their production typically relies on wet chemistry involving organic solvents or chemical vapor deposition, necessitating elaborate equipment and often harsh conditions. Here, an eco-friendly, fast, and facile synthesis of water-templated interfacial polymers based on cyanoacrylates (superglues, CAs) that yield thin films with tailored properties is demonstrated. Specifically, by exposing a cationic surfactant-laden water surface to cyanoacrylate vapors, surfactant-modulated anionic polymerization produces a manipulable thin polymer film with a thickness growth rate of 8 nm min−1. Furthermore, the shape and color of the film are precisely controlled by the polymerization kinetics, wetting conditions, and/or exposure to patterned light. Using various interfaces as templates for film growth, including the free surface of drops and soap bubbles, the developed method advantageously enables in situ packaging of chemical and biological cargos in liquid phase as well as the encapsulation of gases within solidified bubbles. Simple, versatile, and biocompatible, this technology constitutes a potent platform for programmable coating and soft/smart encapsulation of fluids.
Keywords: thin polymer films, fluid encapsulation
Published in DiRROS: 07.10.2024; Views: 136; Downloads: 294
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316. 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: 193; Downloads: 72
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317. 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: 156; Downloads: 63
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318. 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: 156; Downloads: 89
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319. 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: 137; Downloads: 78
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320. 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: 186; Downloads: 62
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