771. 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: 209; Prenosov: 105
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772. 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: 268; Prenosov: 113
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773. 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: 178; Prenosov: 84
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774. 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: 168; Prenosov: 85
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778. A contribution to the vascular and bryophyte flora of the upper Neretva and Zalomka river valleys (Bosnia and Herzegovina)Đorđije Milanović, Simona Strgulc Krajšek, Jugoslav Brujić, Valentin Heimer, Dragan Koljanin, Marija Kravanja, Ivana Rešetnik, Vladimir Stupar, Peter Schönswetter, Božo Frajman, 2025, izvirni znanstveni članek Povzetek: etween 1st and 6th June 2023, we conducted floristic research on sev-eral sites in the upper Neretva River valley and along Zalomka River at Nevesinjsko Polje. We recorded 933 taxa in total; 897 plant taxa including 125 bryophytes were found at 51 localities in the upper Neretva River val-ley, and 200 plant taxa, including 32 bryophytes, were found at 11 sites in the Zalomka River valley. Among the registered taxa, 39 taxa are endemic to the Balkan Peninsula, 56 are listed in the List of endangered and rare taxa of Bosnia and Herzegovina, 27 are on the Red List of the Federation of Bosnia and Herzegovina, and 95 taxa are protected in the Republic of Srpska. We also registered several species new to the flora of Bosnia and Herzegovina. Among Angiosperms these were Barbarea intermedia, Lamium hybridum, Myosotis sicula and Poa ursina, and among bryophytes Fissidens gracilifolius, Grimmia dissimulata, Plagiomnium ellipticum, Schistidium robustum, Sphenolobus minutus, Tortella fasciculata and T. pseudofragilis. Our study reveals the high nature conservation value of the upper Neretva and Zalomka River valleys that should be protected for future generations. In addition, further systematic research of the flora of Bosnia and Herzegovina is needed
Ključne besede: angiosperms, mosses, nature conservation, Neretva River, vegetation, are species
Objavljeno v DiRROS: 16.10.2025; Ogledov: 231; Prenosov: 103
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779. Optimal version of the fundamental theorem of chronogeometryMichiya Mori, Peter Šemrl, 2025, izvirni znanstveni članek Povzetek: We study lightlikeness preserving mappings from the $4$-dimensional Minkowski spacetime $\mathcal{M}_4$ to itself under no additional regularity assumptions like continuity, surjectivity, or injectivity. We prove that such a mapping $\phi$ satisfies one of the following three conditions. (1) The mapping $\phi$ can be written as a composition of a Lorentz transformation, a multiplication by a positive scalar, and a translation. (2) There is an event $r\in \mathcal{M}_4$ such that $\phi(\mathcal{M}_4\setminus\{r\})$ is contained in one light cone. (3) There is a lightlike line $\ell$ such that $\phi(\mathcal{M}_4\setminus \ell)$ is contained in another lightlike line. Here, a line that is contained in some light cone in $\mathcal{M}_4$ is called a lightlike line. We also give several similar results on mappings defined on a certain subset of $\mathcal{M}_4$ or the compactification of $\mathcal{M}_4$.
Ključne besede: fundamental theorem of chronogeometry, special relativity, coherency preserving mapping
Objavljeno v DiRROS: 16.10.2025; Ogledov: 198; Prenosov: 83
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780. Randomized methods for computing joint eigenvalues, with applications to multiparameter eigenvalue problems and root findingHaoze He, Daniel Kressner, Bor Plestenjak, 2025, izvirni znanstveni članek Povzetek: It is well known that a family of $n \times n$ commuting matrices can be simultaneously triangularized by a unitary similarity transformation. The diagonal entries of the triangular matrices define the $n$ joint eigenvalues of the family. In this work, we consider the task of numerically computing approximations to such joint eigenvalues for a family of (nearly) commuting matrices. This task arises, for example, in solvers for multiparameter eigenvalue problems and systems of multivariate polynomials, which are our main motivations. We propose and analyze a simple approach that computes eigenvalues as one-sided or two-sided Rayleigh quotients from eigenvectors of a random linear combination of the matrices in the family. We provide some analysis and numerous numerical examples, showing that such randomized approaches can compute semisimple joint eigenvalues accurately and lead to improved performance of existing solvers.
Ključne besede: commuting matrices, joint eigenvalues, Rayleigh quotient, randomized numerical linear algebra, multiparameter eigenvalue problems, polynomial systems
Objavljeno v DiRROS: 16.10.2025; Ogledov: 211; Prenosov: 112
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