Plant leaves play a pivotal role in automated species identification using deep learning (DL). However, achieving reproducible capture of leaf variation remains challenging due to the inherent "black box" problem of DL models. To evaluate the effectiveness of DL in capturing leaf shape, we used geometric morphometrics (GM), an emerging component of eXplainable Artificial Intelligence (XAI) toolkits. We photographed Ranunculus auricomus leaves directly in situ and after herbarization. From these corresponding leaf images, we automatically extracted DL features using a neural network and digitized leaf shapes using GM. The association between the extracted DL features and GM shapes was then evaluated using dimension reduction and covariation models. DL features facilitated the clustering of leaf images by source populations in both in situ and herbarized leaf image datasets, and certain DL features were significantly associated with biological leaf shape variation as inferred by GM. DL features also enabled leaf classification into morpho-phylogenomic groups within the intricate R. auricomus species complex. We demonstrated that simple in situ leaf imaging and DL reproducibly captured leaf shape variation at the population level, while combining this approach with GM provided key insights into the shape information extracted from images by computer vision, a necessary prerequisite for reliable automated plant phenotyping.

• Klíčová slova
• Ranunculus auricomus, deep learning, eXplainable AI, geometric morphometrics, leaf images, phenotypic variation, smartphone imaging in situ,
• MeSH
• deep learning * MeSH
• fylogeneze MeSH
• listy rostlin * anatomie a histologie   MeSH
• neuronové sítě MeSH
• počítačové zpracování obrazu * metody   MeSH
• Publikační typ
• časopisecké články MeSH

OBJECTIVES: The Sahel/Savannah belt is a region where two sympatric human subsistence strategies-nomadic pastoralism and sedentary farming-have been coexisting for millennia. While earlier studies focused on estimating population differentiation and genetic structure of this ecologically remarkable region's inhabitants, less effort has been expended on understanding the morphological variation among local populations. MATERIALS AND METHODS: To fill this gap, we used geometric morphometrics to analyze the facial features of three groups of pastoralists and three groups of sedentary farmers belonging to three language families (Niger-Congo, Nilo-Saharan, and Afro-Asiatic) whose mitochondrial DNA sequences have been published previously. RESULTS: Our results show that pastoralists differ from farmers with several facial features. We also found that individuals who bear maternally inherited haplotypes of Eurasian ancestry do not significantly morphologically differ from individuals whose maternal ancestry is sub-Saharan. CONCLUSIONS: Our study follows up and builds upon population genetic and phylogeographic studies of Eurasian haplogroups in the Fulani pastoralists and sub-Saharan haplogroups in the Arab pastoralists, as well as studies on the spread of lactase persistence mutations and other genetic markers. Our results suggest that recent gene flows across the Sahel/Savannah belt were not strong enough to erase a genetic structure established by Paleolithic foragers and further shaped by the adoption of agropastoral food-producing strategies.

• Klíčová slova
• Sahel Savannah belt, food-producing strategies, geometric morphometrics,
• MeSH
• antropologie fyzická MeSH
• Arabové genetika   statistika a číselné údaje   MeSH
• běloši genetika   statistika a číselné údaje   MeSH
• černoši * genetika   statistika a číselné údaje   MeSH
• dieta statistika a číselné údaje   MeSH
• dospělí MeSH
• haplotypy genetika   MeSH
• lidé MeSH
• mitochondriální DNA genetika   MeSH
• mladý dospělý MeSH
• obličej anatomie a histologie   MeSH
• osoby s přechodným pobytem a migranti statistika a číselné údaje   MeSH
• populační genetika MeSH
• zemědělci statistika a číselné údaje   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• severní Afrika MeSH
• subsaharská Afrika MeSH
• Názvy látek
• mitochondriální DNA MeSH

The most pervasive species-richness pattern, the latitudinal gradient of diversity, has been related to Rapoport's rule, i.e., decreasing latitudinal extent of species' ranges toward the equator. According to this theory, species can have narrower tolerances in more stable climates, leading to smaller ranges and allowing coexistence of more species. We show, using a simple geometric model, that the postulated decrease of species' potential range sizes toward the tropics would itself lead to a latitudinal gradient opposite to that observed. In contrast, an increase in extent of potential ranges toward the tropics would lead to the observed diversity gradient. Moreover, in the presence of geographic barriers constraining actual species' ranges, Rapoport's rule emerges if the latitudinal trend in extents of potential ranges (as defined by climatic tolerance) is opposite to that postulated or if variability in potential range extents decreases toward the poles. A strong implicit latitudinal diversity gradient (i.e., higher concentration of midpoints of species' potential ranges in the tropics), however, produces both observed macroecological patterns without the contribution of any latitudinal trends in species climatic tolerances or in potential range sizes. Our model underscores the necessity of discriminating theoretical processes and principles from the patterns we observe, and it is well supported by data on global distribution of species' range sizes.

• MeSH
• biodiverzita * MeSH
• biologická evoluce * MeSH
• biologické modely * MeSH
• demografie MeSH
• druhová specificita MeSH
• ekosystém MeSH
• fylogeneze MeSH
• fyziologická adaptace fyziologie   MeSH
• podnebí * MeSH
• populační dynamika MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Many dynamic interactions within the cell microenvironment modulate cell behavior and cell fate. However, the pathways and mechanisms behind cell-cell or cell-extracellular matrix interactions remain understudied, as they occur at a nanoscale level. Recent progress in nanotechnology allows for mimicking of the microenvironment at nanoscale in vitro; electron-beam lithography (EBL) is currently the most promising technique. Although this nanopatterning technique can generate nanostructures of good quality and resolution, it has resulted, thus far, in the production of only simple shapes (e.g., rectangles) over a relatively small area (100 × 100 μm), leaving its potential in biological applications unfulfilled. Here, we used EBL for cell-interaction studies by coating cell-culture-relevant material with electron-conductive indium tin oxide, which formed nanopatterns of complex nanohexagonal structures over a large area (500 × 500 μm). We confirmed the potential of EBL for use in cell-interaction studies by analyzing specific cell responses toward differentially distributed nanohexagons spaced at 1000, 500, and 250 nm. We found that our optimized technique of EBL with HaloTags enabled the investigation of broad changes to a cell-culture-relevant surface and can provide an understanding of cellular signaling mechanisms at a single-molecule level.

• Klíčová slova
• biomimetic surface, cell adhesion and spreading, cell−cell interaction, electron-beam lithography, ligand clustering, nanopatterning, nanospacing,
• MeSH
• buněčná diferenciace MeSH
• buněčné kultury MeSH
• extracelulární matrix MeSH
• nanostruktury * chemie   MeSH
• nanotechnologie * metody   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Translucent elements in the form of truncated cones, which are made of organic glass, are widely used in the structures of portholes, submersible vessels, space vehicles, pressure chambers, teleboxes and other types of technical equipment. The decisive factor in designing portholes is to ensure the strength of their translucent elements. In order to reduce the weight of portholes and, accordingly, to increase the payload, it is necessary to optimise the geometric parameters of the translucent elements, which include the tapering angle and the ratio of thickness to radius of the smaller base. The paper deals with development of the applied (engineering) method for determining the stress-strain behaviour of the conical translucent elements of portholes made of organic glass under the action of a uniform hydrostatic pressure. Finite-element modelling of the translucent element of the conical porthole is performed, with the calculation of its stress-strain behaviour. External hydrostatic pressure of 10 MPa, absence of loads from the inside and continuous sliding of the translucent element with friction along the conical supporting surface of the porthole metal body are the boundary conditions for the computational model. Full-scale tests of translucent elements of portholes made of organic glass were performed under the action of uniform hydrostatic pressure. Analysis of the influence of geometric characteristics of the portholes on stress-strain behaviour showed that the increase in the tapering angle at the constant relative thickness of the translucent element reduced its axial displacement in all cases. Equivalent stresses acquire minimum values when the tapering angle is in the range from 75° to 105° (when the relative thickness increases, the optimal tapering angle becomes smaller). It is shown that the developed method for determination of the stress-strain behaviour of the conical translucent elements of portholes made of organic glass reflects the real picture of deformation and agrees with the results of full-scale tests. Results of the work allow us to choose the rational parameters of the translucent element for increasing the reliability of portholes through the creation of an effective distribution of stresses and strains in the translucent element, and improving its optical characteristics due to a relatively small deflection in operation.

• Klíčová slova
• hydrostatic load, organic glass, polymethyl methacrylate plastic, translucent element,
• Publikační typ
• časopisecké články MeSH

Selective laser melting (SLM) is an additive technology that allows for the production of precisely designed complex structures for energy absorbing applications from a wide range of metallic materials. Geometrical imperfections of the SLM fabricated lattice structures, which form one of the many thin struts, can lead to a great difference in prediction of their behavior. This article deals with the prediction of lattice structure mechanical properties under dynamic loading using finite element method (FEA) with inclusion of geometrical imperfections of the SLM process. Such properties are necessary to know especially for the application of SLM fabricated lattice structures in automotive or aerospace industries. Four types of specimens from AlSi10Mg alloy powder material were manufactured using SLM for quasi-static mechanical testing and determination of lattice structure mechanical properties for the FEA material model, for optical measurement of geometrical accuracy, and for low-velocity impact testing using the impact tester with a flat indenter. Geometries of struts with elliptical and circular cross-sections were identified and tested using FEA. The results showed that, in the case of elliptical cross-section, a significantly better match was found (2% error in the Fmax) with the low-velocity impact experiments during the whole deformation process compared to the circular cross-section. The FEA numerical model will be used for future testing of geometry changes and its effect on mechanical properties.

• Klíčová slova
• ANSYS Workbench, aluminum alloy AlSi10Mg, energy absorption, finite element analysis (FEA), lattice structure, low-velocity impact, material model, numerical model,
• Publikační typ
• časopisecké články MeSH

OBJECTIVES: This study assessed the safety and efficacy of an internal geometric annuloplasty ring in a regulatory trial of aortic valve reconstruction (ClinicalTrials.gov Identifier: NCT01400841). METHODS: Sixty-five patients with predominant moderate-to-severe trileaflet aortic insufficiency (AI) underwent aortic valve repair with an average age of 63 ± 13 years (mean ± SD). All had initial implantation of an internal aortic annuloplasty ring to correct annular dilatation and facilitate leaflet reconstruction. Leaflet plication was performed for prolapse in 80% of patients, and more complex leaflet procedures, usually employing autologous pericardium, were required in 22%. Ascending aortic and/or root aneurysms were replaced in 62%. RESULTS: Follow-up was for a maximum of 3 years and a mean of 2 years. No in-hospital operative mortalities, major complications or early or late valve-related events occurred. The annular diameter before repair was 26.5 ± 2.3 mm, and the average ring diameter used was 21.5 ± 1.6 mm. The preoperative AI grade (0-4) was 2.9 ± 0.8 and improved after repair to 0.6 ± 0.7 (P < 0.0001), as did the NYHA class. The mean valve gradient was 8.6 ± 4.3 mmHg, and at 3 years, the Kaplan-Meier survival rate was 95%, with no valve-related mortality. Over the 3 years, aortic valve replacement was required in 7 patients (10.8%) for reasons usually related to surgical technique. Most repair failures occurred early, and results stabilized after 6 months. No structural complications of the rings were observed. CONCLUSIONS: Geometric ring annuloplasty was a safe and effective adjunct to aortic valve repair. Initial correction of annular dilatation seemed to facilitate overall reconstruction. Because most early repair failures were technical, increasing experience with geometric ring annuloplasty for aortic valve reconstruction has the potential to standardize and improve outcomes.

• Klíčová slova
• Aortic annuloplasty, Aortic insufficiency, Aortic valve repair,
• MeSH
• anuloplastika srdeční chlopně škodlivé účinky   přístrojové vybavení   metody   mortalita   MeSH
• aortální chlopeň chirurgie   MeSH
• aortální insuficience chirurgie   MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• prospektivní studie MeSH
• reoperace MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• srdeční chlopně umělé škodlivé účinky   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• klinické zkoušky MeSH
• práce podpořená grantem MeSH

A convenient geometrical description of the microvascular network is necessary for computationally efficient mathematical modelling of liver perfusion, metabolic and other physiological processes. The tissue models currently used are based on the generally accepted schematic structure of the parenchyma at the lobular level, assuming its perfect regular structure and geometrical symmetries. Hepatic lobule, portal lobule, or liver acinus are considered usually as autonomous functional units on which particular physiological problems are studied. We propose a new periodic unit-the liver representative periodic cell (LRPC) and establish its geometrical parametrization. The LRPC is constituted by two portal lobulae, such that it contains the liver acinus as a substructure. As a remarkable advantage over the classical phenomenological modelling approaches, the LRPC enables for multiscale modelling based on the periodic homogenization method. Derived macroscopic equations involve so called effective medium parameters, such as the tissue permeability, which reflect the LRPC geometry. In this way, mutual influences between the macroscopic phenomena, such as inhomogeneous perfusion, and the local processes relevant to the lobular (mesoscopic) level are respected. The LRPC based model is intended for its use within a complete hierarchical model of the whole liver. Using the Double-permeability Darcy model obtained by the homogenization, we illustrate the usefulness of the LRPC based modelling to describe the blood perfusion in the parenchyma.

• MeSH
• anatomické modely * MeSH
• biologické modely MeSH
• játra anatomie a histologie   krevní zásobení   MeSH
• lidé MeSH
• mikrocirkulace MeSH
• ověření koncepční studie MeSH
• perfuze MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Green microalgae of the Micrasterias lineage are unicellular microorganisms with modular morphology consisting of successively differentiated lobes. Due to their morphological diversity and peculiar morphogenesis, these species are important model systems for studies of cytomorphogenesis and cellular plasticity. Interestingly, the phylogenetic structure of the Micrasterias lineage and most other Desmidiales is poorly related to the traditional morphological characters used for delimitation of taxa. In this study, we focused on symmetry breaking between adjacent cellular lobes in relation to phylogeny of the studied species. While pronounced morphological asymmetry between the adjacent lobes is typical for some species, others have been characterized by the almost identical morphologies of these structures. We asked whether there is any detectable average shape asymmetry between the pairs of lobes and terminal lobules in 19 Micrasterias species representing all major clades of this desmidiacean lineage. Then, we evaluated whether the asymmetric patterns among species are phylogenetically structured. The analyses showed that the phylogeny was in fact strongly related to the patterns of morphological asymmetry between the adjacent cellular lobes. Thus, evolution of the asymmetric development between the adjacent lobes proved to be the key event differentiating cellular shape patterns of Micrasterias. Conversely, the phylogeny was only weakly related to asymmetry between the pairs of terminal lobules. The subsequent analyses of the phylogenetic morphological integration showed that individual hierarchical levels of cellular morphology were only weakly coordinated with regard to asymmetric variation among species. This finding indicates that evolutionary differentiation of morphogenetic processes leading to symmetry breaking may be relatively independent at different branching levels. Such modularity is probably the key to the evolvability of cellular shapes, leading to the extraordinary morphological diversity of these intriguing microalgae.

• Klíčová slova
• Asymmetry, Cytomorphogenesis, Desmidiales, Geometric morphometrics, Phenotype evolution, Phylomorphospace,
• Publikační typ
• časopisecké články MeSH

The infrared (IR) and vibrational circular dichroism (VCD) spectra of guanosine-5'-hydrazide ( G-1), a powerful hydrogelator, have been measured and analyzed on the basis of ab initio modeling. B3LYP/6-31G** DFT calculations predict that G-1, forming a clear solution in deuterated DMSO, is present in monomeric form in this solvent, whereas strong gelation in a phosphate buffer is due to the formation of a guanine-quartet structure, ( G-1)4, in which the four G-1 are linked by hydrogen-bonded guanine moieties and stabilized by an alkali metal cation. The B3LYP/6-31G** IR and VCD spectra of the nearly planar G-quartet, whose structure is slightly distorted from the C4h symmetry, in which the G-bases interact via four Hoogsteen-type hydrogen bonds and a sodium cation is positioned in the middle of the G-quartet, are in very good agreement with the experimental spectra, indicating that this structure is the predominant structure in the gel state. The geometric parameters are discussed. This study is the first to use IR and VCD spectroscopies coupled with DFT calculations to elucidate the structure of a supramolecular species in a gel state and shows the VCD spectroscopy as a powerful method for investigating the structure of complex supramolecular self-assemblies where the use of other structural methods is limited.

• MeSH
• cirkulární dichroismus MeSH
• dimerizace MeSH
• gely chemie   MeSH
• guanin chemie   MeSH
• molekulární modely MeSH
• molekulární struktura MeSH
• sacharidy chemie   MeSH
• spektrofotometrie infračervená MeSH
• vibrace * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• gely MeSH
• guanin MeSH
• sacharidy MeSH