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Diversity and function of pattern structures in the microworld
Hirnerová, Anna ; Škaloud, Pavel (advisor) ; Němcová, Yvonne (referee)
This thesis summarizes current knowledge of patterns and structures at various scales, with an emphasis on the use of these patterns in the microworld and also on the materials that are most often used. Patterns are applied in all areas of natural processes and human activity. There are many analogous models at different scales, but we do not know if they have the same self-organizing mechanisms. Many patterns formed by microorganisms can be prepared without their presence, on the basis of physical and chemical methods, so they are probably created under certain parameters that can be influenced by a given protist. These patterns are evolutionarily advantageous for microorganisms, because they provide them with a number of functional adaptations, mainly in connection with defense against predators and movement in the water column, which is based on the organism's life strategy. The mathematical description of the pattern is extremely important for its further research and for determining the laws that have allowed the organism to benefit from its parameters. Keywords: pattern, structure, convection, reaction - diffusion model, geometry, protist, microorganism, skeletons, shells, scales
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Evolution of silica structures in SAR protists
Čížková, Natálie ; Čertnerová, Dora (advisor) ; Kulichová, Jana (referee)
Silicon is an important element in the earth's crust. In nature it mainly occurs in the form of silicic acid. This element is used by marine and freshwater organisms to form their siliceous structures. The organisms that make up these structures are located throughout the phylogenetic tree and are not limited just to protist groups. The SAR line includes Stramenopila, Alveolata and Rhizaria. The main protist taxa forming the mentioned siliceous structures are in these groups. These are mainly diatoms, silicoflagellates, radiolarians and the group chrysophyceae. The formation of siliceous structures usually provides evolutionary benefits to organisms, such as protection of the cell from actions of biotic and abiotic factors. The availability of dissolved silicon changed during evolution, thus affecting the appearance and functionality of the structures of individual species. Structural changes were manifested by thinning of the shells, change of cell size, enlargement or decrease of pores, increase of the number of thorns or, conversely, their loss. The individual lines thus had to choose the best possible strategies in response to the decreasing availability of silicic acid. Therefore, there was frequent competition between the groups for the remaining dissolved silicon. The current diversity of...
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Shell-Like Structures in the ISM: Observation Versus Simulations
Sidorin, Vojtěch ; Palouš, Jan
The interstellar medium in galaxies is a turbulent environment with a plethora of holes, bubbles and shells. All these shell-like structures are thought to be closely related to the formation, evolution and death of stars. In most cases, they are likely created by the winds of OB stars and supernovae. The material collected along the borders of shells may fragment, become unstable under its own gravity, and create a new generation of stars. This is a variant of triggered star formation referred to as the collect-and-collapse scenario. The aim of our research is to compare numerical simulations of shell-like structures to observations and to search for and investigate regions of triggered star formation in the Milky Way.
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