671. Comparison of elemental composition of surface and subsurface soils on national level and identification of potential natural and anthropogenic processes influencing its compositionEmil Pučko, Gorazd Žibret, Klemen Teran, 2024, izvirni znanstveni članek Povzetek: The elemental composition of soils is governed by geogenic processes and anthropogenic activities. A comprehensive soil study was conducted on a national level, in which the elemental composition of soils from two different layers was compared with the intention to differentiate between natural and anthropogenic sources of elemental enrichments. Topsoil (0–5 cm) and subsoil (20–30 cm) samples were collected from 249 different locations on a national scale (Slovenia). Elemental composition for 55 major, minor, and trace elements (ICP-MS, aqua regia digestion) was determined on the fraction <0.063 mm. By calculating the enrichment ratios in different lithological units, it was determined that levels of Ti are higher in soils overlying metamorphic and igneous rocks, Zr and Ca are more abundant over carbonates, while levels of Ni are higher in soils overlying marlstones. Elevated levels of Hg were detected in subsoils in the historical Hg mining area in Idrija, which indicates the presence of nearby orebodies as a potential source for the geochemical anomaly. Spatial distribution of elements showed that higher levels of Pb, Zn, Cu, and Hg were detected in topsoils of urban areas, indicating that anthropogenic sources could be the potential cause of soil contamination. Pb, Zn, Cu, and Hg levels were up to four times higher in topsoils compared to subsoils sampled at historical mining areas (e.g., Mežica, Idrija, Litija), which shows that historical mining left a significant environmental impact. Although mining and smelting activities ended a few decades ago, soils in some areas are still heavily enriched with various metals. Some other potential anthropogenic sources of elements were identified, such as farming and ironworks. Based on the results of this study, we can conclude that by comparing elemental compositions of soils from different layers, we can recognise the origin of elemental enrichments.
Ključne besede: smelting, mining, urbanisation, traffic, ironworks, weathering
Objavljeno v DiRROS: 18.03.2024; Ogledov: 180; Prenosov: 50
 Celotno besedilo (16,11 MB) |
672. |
673. |
674. |
675. A method for computing the edge-Hosoya polynomial with application to phenylenesMartin Knor, Niko Tratnik, 2023, izvirni znanstveni članek Povzetek: The edge-Hosoya polynomial of a graph is the edge version of the famous Hosoya polynomial. Therefore, the edge-Hosoya polynomial counts the number of (unordered) pairs of edges at distance $k \ge 0$ in a given graph. It is well known that this polynomial is closely related to the edge-Wiener index and the edge-hyper-Wiener index. As the main result of this paper, we greatly generalize an earlier result by providing a method for calculating the edge-Hosoya polynomial of a graph $G$ which is obtained by identifying two edges of connected bipartite graphs $G_1$ and $G_2$. To show how the main theorem can be used, we apply it to phenylene chains. In particular, we present the recurrence relations and a linear time algorithm for calculating the edge-Hosoya polynomial of any phenylene chain. As a consequence, closed formula for the edge-Hosoya polynomial of linear phenylene chains is derived.
Ključne besede: edge-Hosoya polynomial, graphs, phenylenes
Objavljeno v DiRROS: 18.03.2024; Ogledov: 368; Prenosov: 345
Celotno besedilo (530,53 KB) |
676. How to compute the M-polynomial of (chemical) graphsEmeric Deutsch, Sandi Klavžar, Gašper Domen Romih, 2023, izvirni znanstveni članek Povzetek: Let $G$ be a graph and let $m_{i,j}(G)$, $i,j\ge 1$, be the number of edges $uv$ of ▫$G$▫ such that $\{d_v(G), d_u(G)\} = \{i,j\}$. The M-polynomial of $G$ is $M(G;x,y) = \sum_{i\le j} m_{i,j}(G)x^iy^j$. A general method for calculating the M-polynomials for arbitrary graph families is presented. The method is further developed for the case where the vertices of a graph have degrees 2 and $p$, where $p\ge 3$, and further for such planar graphs. The method is illustrated on families of chemical graphs.
Ključne besede: M-polynomial, chemical graph, planar graph
Objavljeno v DiRROS: 18.03.2024; Ogledov: 181; Prenosov: 51
Celotno besedilo (376,13 KB) |
677. Qualitative analysis of the minimal Higgins model of glycolysisBrigita Ferčec, Matej Mencinger, Tatjana Petek, Orhan Ozgur Aybar, Ilknur Kusbeyzi Aybar, 2023, izvirni znanstveni članek Povzetek: Glycolysis, one of the leading metabolic pathways, involves many
different periodic oscillations emerging at positive steady states of
the biochemical models describing this essential process. One of
the models employing the molecular diffusion of intermediates is
the Higgins biochemical model to explain sustained oscillations. In
this paper, we investigate the center-focus problem for the minimal
Higgins model for general values of the model parameters with the
help of computational algebra. We demonstrate that the model
always has a stable focus point by finding a general form of the first
Lyapunov number. Then, varying two of the model parameters, we
obtain the first three coefficients of the period function for the stable focus point of the model and prove that the singular point is actually a bi-weak monodromic equilibrium point of type $[1, 2]$. Additionally, we prove that there are two (small) intervals for a chosen parameter $a > 0$ for which one critical period bifurcates from this singular point after small perturbations.
Ključne besede: biological processes, biochemical models, glycolysis
Objavljeno v DiRROS: 18.03.2024; Ogledov: 202; Prenosov: 81
Celotno besedilo (837,28 KB)
Gradivo ima več datotek! Več... |
678. |
679. CT colonography in detection of colorectal carcinomaAmela Sofić, Šerif Beslić, Igor Kocijančič, Nedžad Šehović, 2010, izvirni znanstveni članek Povzetek: Background. Diagnostic methods used in screening and detectingand 2 lipomas,and 2 lipomas, among tumours there were 55 adenocarcinomas and 1 lymphoma. Results showed CT colonography among tumours there were 55 adenocarcinomas and 1 lymphoma. Results showed CTsensitivity to polyps to be 89.7%, barium enema 48.7%, and colonoscopy 94.9%. Sensitivity to tumours of CT colonography colonography colorectal CT barium enema followed by colonoscopy wereand colonoscopy was 100% and of barium enema 94.6%. Specificities and PPV were 100% in all procedures. The performed. After thesensitivity to polyps to be 89.7%, barium enema 48.7%, andcomfort assessment showed CT colonography as the far most comfortable out of three procedures. colonoscopy 94.9%. Sensitivity to tumours of CT colonography procedures a comfort assessment was done in all colonography. The aim of thisand colonoscopy was 100% and of barium enema 94.6%. Specificities and PPV were 100% in all procedures. The study was to establish diagnostic accuracy andpatients. Diagnostic positive comfort assessment showed CT colonography as the far most comfortable out of three procedures. results were verified by the pato-histological examination. Sensitivity, specificity, positive comfort of CT colonography compared carcinoma are digitorectal examination,topredicative value (PPV) and negative predicative value (NPV) were calculated for each procedure.
Ključne besede: CT colonography, barium enema, colonoscopy, colorectal polyp, colorectal carcinoma
Objavljeno v DiRROS: 18.03.2024; Ogledov: 163; Prenosov: 55
Celotno besedilo (933,29 KB) |
680. Resonance graphs and a binary coding of perfect matchings of outerplane bipartite graphsSimon Brezovnik, Niko Tratnik, Petra Žigert Pleteršek, 2023, izvirni znanstveni članek Povzetek: 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 DiRROS: 18.03.2024; Ogledov: 191; Prenosov: 53
Celotno besedilo (433,15 KB) |
