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1.
2.
Interlayer connectivity affects the coherence resonance and population activity patterns in two-layered networks of excitatory and inhibitory neurons
David Ristič, Marko Gosak, 2022, izvirni znanstveni članek

Opis: The firing patterns of neuronal populations often exhibit emergent collective oscillations, which can display substantial regularity even though the dynamics of individual elements is very stochastic. One of the many phenomena that is often studied in this context is coherence resonance, where additional noise leads to improved regularity of spiking activity in neurons. In this work, we investigate how the coherence resonance phenomenon manifests itself in populations of excitatory and inhibitory neurons. In our simulations, we use the coupled FitzHugh-Nagumo oscillators in the excitable regime and in the presence of neuronal noise. Formally, our model is based on the concept of a two-layered network, where one layer contains inhibitory neurons, the other excitatory neurons, and the interlayer connections represent heterotypic interactions. The neuronal activity is simulated in realistic coupling schemes in which neurons within each layer are connected with undirected connections, whereas neurons of different types are connected with directed interlayer connections. In this setting, we investigate how different neurophysiological determinants affect the coherence resonance. Specifically, we focus on the proportion of inhibitory neurons, the proportion of excitatory interlayer axons, and the architecture of interlayer connections between inhibitory and excitatory neurons. Our results reveal that the regularity of simulated neural activity can be increased by a stronger damping of the excitatory layer. This can be accomplished with a higher proportion of inhibitory neurons, a higher fraction of inhibitory interlayer axons, a stronger coupling between inhibitory axons, or by a heterogeneous configuration of interlayer connections. Our approach of modeling multilayered neuronal networks in combination with stochastic dynamics offers a novel perspective on how the neural architecture can affect neural information processing and provide possible applications in designing networks of artificial neural circuits to optimize their function via noise-induced phenomena.
Ključne besede: neuronal dynamics, coherence resonance, excitatory neurons, inhibitory neurons, neural network, multilayer network, interlayer connectivity
Objavljeno v DKUM: 20.12.2024; Ogledov: 0; Prenosov: 2
.pdf Celotno besedilo (6,72 MB)
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3.
Resonance graphs and a binary coding of perfect matchings of outerplane bipartite graphs
Simon Brezovnik, Niko Tratnik, Petra Žigert Pleteršek, 2023, izvirni znanstveni članek

Opis: The aim of this paper is to investigate resonance graphs of $2$-connected outerplane bipartite graphs, which include various families of molecular graphs. Firstly, we present an algorithm for a binary coding of perfect matchings of these graphs. Further, $2$-connected outerplane bipartite graphs with isomorphic resonance graphs are considered. In particular, it is shown that if two $2$-connected outerplane bipartite graphs are evenly homeomorphic, then its resonance graphs are isomorphic. Moreover, we prove that for any $2$-connected outerplane bipartite graph $G$ there exists a catacondensed even ring systems $H$ such that the resonance graphs of $G$ and $H$ are isomorphic. We conclude with the characterization of $2$-connected outerplane bipartite graphs whose resonance graphs are daisy cubes.
Ključne besede: graph theory, resonance graphs, bipartite graphs
Objavljeno v DKUM: 10.12.2024; Ogledov: 0; Prenosov: 6
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4.
Binary coding of resonance graphs of catacondensed polyhexes
Aleksander Vesel, 2023, izvirni znanstveni članek

Opis: A catacondensed polyhex H is a connected subgraph of a hexagonal system such that any edge of H lies in a hexagon of H, any triple of hexagons of H has an empty intersection and the inner dual of H is a cactus graph. A perfect matching M of a catacondensed polyhex H is relevant if every cycle of the inner dual of H admitsa vertex that corresponds to the hexagon which contributes three edges in M. The vertex set of the graph R˜(H) consists of all relevant perfect matchings of H, two perfect matchings being adjacent whenever their symmetric difference forms the edge set of a hexagon of H. A labeling that assigns in linear time a binary string to every relevant perfect matching of a catacondensed polyhex is presented. The introduced labeling defines an isometric embedding of R˜(H) into a hypercube.
Ključne besede: graphs, graph theory, resonance graphs
Objavljeno v DKUM: 07.06.2024; Ogledov: 99; Prenosov: 12
.pdf Celotno besedilo (518,69 KB)
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5.
6.
Autolysis affects the iron cargo of ferritins in neurons and glial cells at different rates in the human brain
Sowmya Sunkara, Snježana Radulović, Saška Lipovšek Delakorda, Christoph Birkl, Stefan Eggenreich, Anna Maria Birkl-Toeglhofer, Maximilian Schinagl, Daniel Funk, Michael Stöger-Pollach, Johannes Haybaeck, Walter Gössler, Stefan Ropele, Gerd Leitinger, 2023, izvirni znanstveni članek

Opis: Iron is known to accumulate in neurological disorders, so a careful balance of the iron concentration is essential for healthy brain functioning. An imbalance in iron homeostasis could arise due to the dysfunction of proteins involved in iron homeostasis. Here, we focus on ferritin—the primary iron storage protein of the brain. In this study, we aimed to improve a method to measure ferritin-bound iron in the human post-mortem brain, and to discern its distribution in particular cell types and brain regions. Though it is known that glial cells and neurons differ in their ferritin concentration, the change in the number and distribution of iron-filled ferritin cores between different cell types during autolysis has not been revealed yet. Here, we show the cellular and region-wide distribution of ferritin in the human brain using state-of-the-art analytical electron microscopy. We validated the concentration of iron-filled ferritin cores to the absolute iron concentration measured by quantitative MRI and inductively coupled plasma mass spectrometry. We show that ferritins lose iron from their cores with the progression of autolysis whereas the overall iron concentrations were unaffected. Although the highest concentration of ferritin was found in glial cells, as the total ferritin concentration increased in a patient, ferritin accumulated more in neurons than in glial cells. Summed up, our findings point out the unique behaviour of neurons in storing iron during autolysis and explain the differences between the absolute iron concentrations and iron-filled ferritin in a cell-type-dependent manner in the human brain.
Ključne besede: ferritin, human brain, energy-filtered transmission electron microscopy, quantitative magnetic resonance imaging, autolysis
Objavljeno v DKUM: 20.03.2024; Ogledov: 228; Prenosov: 25
.pdf Celotno besedilo (2,73 MB)
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7.
Outerplane bipartite graphs with isomorphic resonance graphs
Simon Brezovnik, Zhongyuan Che, Niko Tratnik, Petra Žigert Pleteršek, 2024, izvirni znanstveni članek

Opis: We present novel results related to isomorphic resonance graphs of 2-connected outerplane bipartite graphs. As the main result, we provide a structure characterization for 2-connected outerplane bipartite graphs with isomorphic resonance graphs. Three additional characterizations are expressed in terms of resonance digraphs, via local structures of inner duals, as well as using distributive lattices on the set of order ideals of posets defined on inner faces of 2-connected outerplane bipartite graphs.
Ključne besede: distributive lattice, inner dual, isomorphic resonance graphs, order ideal, 2-connected outerplane bipartite graph
Objavljeno v DKUM: 29.02.2024; Ogledov: 290; Prenosov: 10
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8.
Measurement of two-particle correlations of hadrons in ▫$e^+ e^-$▫ collisions at Belle
Y.-C. Chen, Marko Bračko, Samo Korpar, Peter Križan, Tomaž Podobnik, Marko Starič, Luka Šantelj, 2022, izvirni znanstveni članek

Opis: The measurement of two-particle angular correlation functions in high-multiplicity e+e− collisions at √s=10.52  GeV is reported. In this study, the 89.5  fb−1 of hadronic e+e− annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle (Δϕ) and three units of pseudorapidity (Δη), defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant anisotropic collective behavior is observed with either coordinate analyses. Near-side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and are expected to provide new constraints to the phenomenological models in the low-energy regime.
Ključne besede: Particle & resonance production, Quark & gluon jets, Quark-gluon plasma
Objavljeno v DKUM: 24.08.2023; Ogledov: 396; Prenosov: 9
.pdf Celotno besedilo (634,71 KB)
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9.
MRI of subcutaneous granuloma annulare: A series of four cases
Liona Jug, Mitja Rupreht, 2022, drugi znanstveni članki

Ključne besede: subcutaneous granuloma annulare, soft tissue tumor, children, magnetic resonance, MRI
Objavljeno v DKUM: 16.02.2023; Ogledov: 658; Prenosov: 55
.pdf Celotno besedilo (222,27 KB)
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10.
A microtremor HVSR study of the seismic site effects in the area of the town of Brežice (SE Slovenia)
Andrej Gosar, 2009, izvirni znanstveni članek

Opis: The wider region of Brežice is one of the most seismically active areas of Slovenia. The most damaging earthquake occurred in 1917, when Brežice was hit by an ML=5.7 earthquake that had an VIII MSK maximum intensity. Seismic site effects due to Quaternary sediments can be expected in the whole area of the town. Since there is a lack of boreholes and geophysical data to assess the site effects, the microtremor (ambient vibrations) horizontal-to-vertical spectral ratio (HVSR) method was applied at 113 free-field measuring points. In general, clear spectral peaks were obtained, but there were also examples of flat spectral ratios indicating a low impedance contrast between the sediments and the bedrock. A map of the sediment resonance frequency was drawn, which shows a frequency range of 1–15 Hz. In the southern part of the town higher frequencies correspond to the thin sediments (the Brežice terrace and the middle Sava terrace) and the high HVSR peak amplitudes indicate a great impedance contrast with the Sarmatian and Badenian bedrock. The northern part is characterized by very low frequencies, indicating thick sediments (Plio-Quaternary gravel) and a small impedance contrast with Pontian marl. The transition between the high and low frequencies is relatively steep. In addition, measurements were performed in 12 characteristic houses to assess the longitudinal and transverse building frequencies. The established building frequency range of 5–10 Hz indicates some areas in the southern part of the town where there is a potential danger of soil-structure resonance. Two buildings show direct evidence of a potential soil-structure resonance. According to this study, more pronounced seismic site effects are expected in the southern part of Brežice.
Ključne besede: ambient vibrations, microtremors, horizontal-to-vertical spectral ratio (HVSR), seismic site effects, soil-structure resonance
Objavljeno v DKUM: 06.06.2018; Ogledov: 1396; Prenosov: 245
.pdf Celotno besedilo (403,95 KB)
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