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Development of mycorrhizal communities in primary succession
Mádle, Jan ; Kohout, Petr (advisor) ; Ponert, Jan (referee)
Primary succession is the process of ecosystem development that takes place in sites that were not suitable for colonization by plants and organisms dependent on them. These sites arise either naturally, for example after a volcanic eruption or glacial retreat, or anthropogenically, for example by strip mining. During primary succession, plants colonise the bare substrate and gradually modify its abiotic and biotic conditions. During primary succession, interactions between plants and the soil microbiome, especially with fungi and bacteria, occur. Plants and soil microorganisms influence each other's growth and development through various interactions. Plants, or rather their roots, form a specific niche for a wide range of soil microbial communities. Through their roots, plants provide a wide range of substances, organic acids, sugars, amino acids and other often carbon-rich compounds that can serve as a substrate for microorganisms. Plants are able to do this by producing litter, root exudates, and translocation of sugars for symbiotic fungi and bacteria. Soil microorganisms contri- bute to the release of nutrients and the decomposition of organic materials that would otherwise be unavailable to plants. Many soil microorganisms can form a symbiotic relationship with the plant; this relationship may be...
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The mounting jig concept for mounting the LED headlight module
Žlebek, Jan ; Kohout, Marek (referee) ; Zeizinger, Lukáš (advisor)
The aim of this thesis is to propose the concept of a universal preparation for mounting the LED module of the headlamp. The first part of the thesis is devoted to individual components of the headlamp, such as printed circuit boards, coolers, optical elements, etc. Furthermore, the thesis provides an overview of the types of modules currently used, from basic reflector technology to the most modern projection modules. The next part of the thesis is focused on conceptual designs for mounting the modules on pallets. It continues by the design of the pallet, which was further verified by the FEM method whether it complies with the given parameters. The last part of the thesis summarizes the advantages and disadvantages in the implementation of the proposed method into the production.
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Development of Long-pitch Corrugation in Curves of Small Radii
Valehrach, Jan ; Kohout,, Martin (referee) ; Lidmila,, Martin (referee) ; Plášek, Otto (advisor)
Throughout the operation, the rails are worn and deteriorate. With the increasing speed of rolling stock, along with higher track loads and especially in the vicinity of major traffic hubs with a higher frequency of trains, defects that did not occur to such an extent before or were not considered to be significant, are brought to the forefront of the concerns of track infrastructure managers. Even though these defects are not directly restrictive to traffic operation, they are, in any case, a source of noise and vibration. One of these defects on the railway track is the micro-geometry defect of the running surface of the railhead. In directional curves with radii of less than 600 m or 700 m, defects known as long-pitch corrugation occur on the inner rail. In curves with 300 m or smaller radii, these waves are so distinct that they are a significant source of noise and vibration. In particular, vibrations affect the track surroundings and the track itself, as they cause other defects in the track structure. This dissertation deals with long-pitch corrugation, focusing on the monitoring of wave generation and development over time. The verification of the possibility to track the development of slip waves over time is the basis for possible future models predicting the development of defects. Numerous measurements of geometric parameters of the track and microgeometry of the railheads, specifically slip waves, have been carried out in the framework of the problem. Using RMS and peak-to-peak methods, the rate of development of defects over time and the relationship with other track parameters were evaluated. Based on the obtained development curves, intervals for further maintenance interventions were estimated. A part of the thesis focuses on the deficiency or excess of cant concerning the development of long-pitch corrugation.
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Evolution of algorithm for artificial creatures
Kohout, Jan ; Holan, Tomáš (advisor) ; Mráz, František (referee)
The task of this work is to create an application which allows performing of experiments with evolution of artificial creatures. Behavior of each creature is managed by its algorithm. The algorithm is able to use creature's memory cells (which represent logical variables) and is the genome of the creature. By the crossing-over and mutation, the algorithm evolves. The second aim of this work is to make some tests with the application and describe their results.
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Purpose of epicentrum agency and marketpace for a new agency after its closure
Kohout, Jan ; Trunečková, Ludmila (advisor) ; Osvaldová, Barbora (referee)
This thesis recapitulates activities of Epicentrum agency which was reporting from the crisis places in the world and due to its termination of activities it attempts to define the meaning of Epicentrum. There is no doubt that Epicentrum was unique, but the important thing is to understand the causes and circumstances of its establishment and actions and to describe the way Epicentrum worked, including the both positive and negative aspects. Since the days of Epicentrum the world of media has changed fundametally (although it has not been that long). There is the phenomenon of media internetisation which the traditional media do not know how to deal with. Consequences of digitization have meant significant changes in journalists' work and the theme of this thesis is how could similar agency operate in these days. Today the proccess of producing the reports from the field is faster and cheaper which is advantage, on the other hand it is much easier to gather the large amount information for free these days and it is hard to convince media to buy it from such an agency. Therefore the integral part of this work is also a reflection on the value of on-the-spot reporting and its subsequent application possibilities on the market.
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Chemical and Physical Properties of Impact Glasses
Křížová, Šárka ; Skála, Roman (advisor) ; Kohout, Tomáš (referee) ; Macháček, Jan (referee)
Abstract This work deals with microstructural features, chemistry and the search for traces of a meteoritic component in proximal tektite-like glasses from the Zhamanshin impact structure (Kazakhstan; further abbreviated as ZIS), and tektites from two strewn fields - moldavites (Czech Republic) and Australasian tektites (Laos; further abbreviated as AAT). Detailed microstructural observations and subsequent chemical and mineralogical studies of various types of inclusions were also performed; these inclusions were mostly found in the studied types of glasses for the first time ever. The aim of this PhD thesis was to (i) describe the microstructure of all studied glasses with a focus on yet unobserved microstructural phenomena, and (ii) try to determine the admixtures of meteoritic components in these glasses. In addition, the available target rocks, which could be a source of moldavites or AAT, were also studied. The microstructures of the studied glasses mutually differ. This is due to a diversity of parent materials and different glass formation conditions occurring during a particular impact event. A new type of "composite splash-form" has been identified among the ZIS glasses, whose chemical composition does not fit into the previously defined groups of irghizites or basic "splash-forms". For...
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Identification of membrane transporters involved in carbon flux in arbuscular mycorrhizal symbiosis
Konečný, Jan ; Kohout, Petr (referee)
Arbuscular mycorrhizal symbiosis is one of the oldest and still most common interactions. This relationship between small soil fungi and plant roots, especially herbs, is the subject of research with, among other things, a promising use in sustainable agriculture. However, intensive research is also taking place at the cellular and molecular level, as the exact mechanisms of functioning of this symbiosis are still shrouded in mystery. Understanding these processes is desirable not only in the boom of genetic engineering. A commonly used model organism for the research of plant symbioses is a smaller legume of the genus medick - Medicago truncatula. Using a microarray for all known M. truncatula genes and by comparing mycorrhizal and non-mycorrhizal plants, the author identified several genes that could participate in symbiosis and he wrote a thesis from these results. In a follow-up experiment with an intervention in plant physiology, the authors of the article (Konečný et al., 2019) point to the probable involvement of some previously unreported genes in symbiosis, but also to different modes of regulation in genes whose probable symbiotic function is already published. This rigorous thesis focuses on the introduction of the first-author publication, a closer explanation of the experiment, which is not...
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Zooplankton of Bohemian Forest lakes as indicator of recovery from acidity
Kohout, Leoš ; Fott, Jan (advisor) ; Macháček, Jiří (referee) ; Bitušík, Peter (referee)
CONCLUSIONS In my Ph.D. thesisthe ťollowingitems arediscussed It is hypothesisedthat Al govems the P availability in the acidified lakes, as well as shapesthe foodweb structure. Substantialportion of the plankton biomass in the Bohemian Forest lakes is createdby hetelotrophic fi|amentswhen filtering cladocerans aÍenot present (theyareextinctor occuÍseasonal1y). After ťrrstsigns in the nineties further evidence for the ongoing biological recovery was collected. Nevertheless, the lakes are still stongly or partially influenced by acidification and standardfood web relationshipshave not been restored. The significant hysteresisof biological recovery behind the reversal of lake chemistryin theBohemianForest and elsewherecould have severalreasons: - Isolationofremote headwaterlakes makestheprocessofzooplankton re- colonizationstochastic,theprobability being atleastfor somecnrstacean specieslow. The successdependson suitablevector ofpropagules and size of inoculum. - Strong invertebrate predation in some fishless lakes can cause abiological resistancepreventing from zooplankton recovery until fish retum. ln theBohemian Forest for instancethereaÍeknown populations of corixids in some lakes and numerousChaoborus larvae are observed from Laka Lake. - Currenthydrochemicalconditions are still hard for...
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