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Item type:Item, Access status: Open Access , Monitoring and Diagnostics of Bridges Using Operational Modal Analysis(2025-12-25) Klusáček, Ladislav; Nečas, Radim; Koláček, Jan; Vašinová, Martina; Bezručová, KristínaThe aging and progressive deterioration of prestressed concrete bridges in the Czech Republic highlight the need for advanced monitoring methods of key structural parameters. This study combines numerical modelling and operational modal analysis of bridge structures composed of precast prestressed beams with transverse connections. A numerical model was developed in Midas Civil with several damage variants and validated using measurements on a real bridge with simulated weakening. The results show that partial loss of prestressing caused only a minor reduction of the first natural frequency, while higher modes were more strongly affected and proved more sensitive to local stiffness changes. These findings confirm that higher and asymmetric modes are more suitable for detecting early stages of degradation. Incorporating the transverse stiffness of girder connections into the model significantly improved agreement with experimental data. It is further assumed that reducing the stiffness of the joints may lead to more significant changes in amplitudes within certain frequency bands, which could be verified through harmonic analysis.Item type:Item, Access status: Open Access , Measuring Investor Sentiment in Financial Discourse: How Different Approaches Shape Market Signals(2025-12-22) Janková, Zuzana; Kavelashvili, Nikoloz; Eschenbach, SebastianStock prices are shaped not only by fundamental data but also by investor sentiment, which often deviates from rational decision-making. Given the vast volume of financial texts published by both professional and amateur investors—especially on online financial platforms—sentiment analysis in such unstructured data is essential to understanding their impact on market movements. This study examines the interplay between text data and stock market movements, highlighting the critical role of sentiment extracted from financial news and online news. Existing research has largely relied on general-purpose lexicons or uniform classification techniques, which limits the accuracy of sentiment analysis in financial contexts. To address this gap, we propose a hybrid framework that integrates domain-specific lexicons with advanced machine learning classifiers to improve sentiment extraction from unstructured financial text. Our approach evaluates the impact of lexicon selection on sentiment scores and examines the relationship between classifier choice and prediction accuracy. By improving sentiment analysis methodologies, our findings contribute to the development of more robust stock market forecasting models, strengthen decision-making processes for investors, and increase market efficiency.Item type:Item, Access status: Open Access , Survey of FOSS 3D/2D Graphics Software Blender Usage in Science, Academia, and Industry(2025-12-26) Chlubna, Tomáš; Vlnas, Michal; Milet, Tomáš; Zemčík, PavelFree and open-source software (FOSS) is a preferred tool for individuals and companies. The advantages of FOSS are minimal expenses, multi-platform and community support, transparent privacy policies, no vendor-related limitations, etc. Blender is a FOSS computer graphics 3D and 2D editor. It offers functions such as modeling, animating, video editing, simulations, image processing, scripting, rendering, etc. It is widely used as a free alternative to existing commercial products. This comprehensive survey examines Blender and its features and explores its usage in research, academic, and industrial projects, based on hundreds of collected and referenced sources. A comparison of Blender with alternative proprietary tools was conducted in terms of rendering performance, popularity, support, and feature set. According to this survey, Blender can be used as an efficient tool in film industry for visual effects composition, for dataset production for scientific experiments or deep learning methods, for educational purposes as a 3D geometrical problems demonstration tool, for the design of industrial models prepared, for example, for 3D printing, usage in augmented or virtual reality applications, etc. More specialized features are available as community-developed add-ons. The main reason why Blender is not used more often, is that many professionals are used to other software.Item type:Item, Access status: Open Access , Production of lipids and carotenoids in Coccomyxa onubensis under acidic conditions in raceway ponds(2025-12-14) Szotkowski, Martin; Robles, Maria; Fuentes, Juan Luis; Holub, Jiří; Cuaresma, Maria; Márová, Ivana; Ruiz-Dominguez, Mari Carmen; Torronteras, Rafael; Davila, Javier; Garbayo, Ines; Vilchez, CarlosCoccomyxa onubensis (C. onubensis) belongs to the extensive genus Coccomyxa, which inhabits ecosystems with high metal concentrations, generally at acidic pH. In this study, the feasibility of cultivating the acidotolerant microalga C. onubensis in raceway open ponds was investigated. Specific attention was paid to the production of lipids and carotenoids. C. onubensis was cultivated outdoors, under non-sterile conditions, in three separate ponds that differed in their nutrient concentrations and aeration rates. The results show that C. onubensis was able to grow steadily and free of photosynthetic contaminants throughout the cultivation period. The low pH of the media prevented non-extremophilic competitors from proliferating, thus allowing for the selective growth of C. onubensis. The highest productivity values for the biomass and targeted compounds were obtained in the culture supplemented with twice the amount of nutrients and aeration rate. These significant maximum productivity values were 0.223 mg of carotenoidsg-1d-1, 0.139 mg of chlorophyllsg-1d-1, and 0.031 g of biomassL-1d-1. A significant maximum lipid production of 9.87% in the dry biomass was reached, of which 49.92% corresponded to polyunsaturated fatty acids (PUFAs). Overall, this manuscript demonstrates that the production of acidic-habitat microalgae in open systems can be advantageous for microalgae-based production of carotenoids and PUFAs, while avoiding contamination by photosynthetic competitors.Item type:Item, Access status: Open Access , Application of spectroscopic methods for direct characterization of photosynthetic pigments and inert intracellular components in the model purple non sulfur bacterium Rhodospirillum rubrum(2025-12-14) Slaninova, Eva; Pacasova, Viktorie-Alexandra; Samek, Ota; Fleuriot-Blitman, Hugo; Zinn, Manfred; Koller, Martin; Benešová, Markéta; Obruča, Stanislav; Sedláček, PetrNon-invasive spectroscopic methods are increasingly valued in life sciences, where preserving the native state of biomolecules is essential for accurate interpretation. Traditional analyses of microbial compounds typically involve solvent-based extraction and chromatographic separation processes, which are time consuming, damaging to samples, and can alter biomolecular structures of complexes. To overcome these limitations, we developed a novel spectroscopic workflow for direct metabolite monitoring in microbial cells. In this study, we established a combined spectroscopic methodology that allows direct pigment and polyhydroxyalkanoates (PHAs) analysis in complex biological samples without requiring chemical extraction procedures. The UV-Vis spectroscopy technique using an integrating sphere enables direct monitoring of pigments even in turbid whole cell suspensions, providing detailed fingerprints of bacteriochlorophyll a and carotenoids in their natural environment. Together, these techniques provide consistent information about cellular composition. Using the photosynthetic bacterium Rhodospirillum rubrum as a model organism, we demonstrate that our combined spectroscopic approach can resolve pigment states, reveal intracellular PHA content and crystallinity, and measure carotenoids and bacteriochlorophylls directly in native whole cell suspensions. Furthermore, advanced data processing provided an improved interpretation of pigment and PHA states in different cellular forms. This innovative combination of spectroscopic techniques reduces sample manipulation, preserves cellular integrity and provides rapid, precise, and environmentally friendly analysis of microbial metabolites in their natural physiological conditions. The demonstrated workflow is broadly applicable to biological samples where maintaining biomolecular integrity is crucial, and it has strong potential for applications in process analytical technology and industrial biotechnology.