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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Utilizace vybraných sacharidů houbového původu orchidejemi a jejich možný přenos v mykorhize / Utilization of selected fungal saccharides by orchids and possibility of their transport in mycorrhiza

Dostálová, Magdalena January 2016 (has links)
Orchideoid mycorrhizal symbiosis (OM) can be found in nearly one tenth of higher plant species. This symbiosis is absolutely critical for orchids as they are unable to grow from seeds without external energy which is in nature provided by symbiotic fungi. The mechanism of transport between symbionts remains unknown. It is supposed that trehalose is one of the substances transported from fungi to plants as the source of energy. This thesis mainly aims to find out which other fungal saccharides could contribute to the process. The ability to utilize selected compounds was tested on protocorms of the common marsh orchid, Dactylorhiza majalis. The results showed that arabitol, erythritol, mannitol and sucralose are not utilized, while xylitol, sorbitol, glycerol and mannose are. Glutamin, an amino acid also suspected of participation in the OM transport, does not suffice as a source of energy. In orchids there were identified three groups of sequences coding for manitol dehydrogenase and two groups of sequences coding for sorbitol dehydrogenase. Key words: orchideoid mycorrhizal symbiosis, sugar alcohols, mannose, glutamine, carbon flow, energy flow, sorbitol dehydrogenase, in vitro
32

Využití analýzy stabilních izotopů uhlíku a dusíku k rekonstrukci výživy ve vztahu ke zdravotnímu stavu langobardské populace / The use of the stable isotope analysis of carbon and nitrogen in the dietary reconstruction of the Lombard population in relation to the health status

Novotná, Adéla January 2017 (has links)
This diploma thesis deals with a reconstruction of the Germanic tribe of the Lombards' diet found at Kyjov burial site dated back to the Migration Period (5th - 6th century A.D.) as well as a research of their living conditions. The principal aim is a description of this population diet and its comparison to the other populations within this period and the Early Middle Ages era. The diet was examined by considering of carbon (δ13 C) and nitrogen (δ15 N) stable isotopes analysis received and evaluated from a group of 60 adult individuals (30 men and 30 females). In regard to the interpretation of the isotopes values, the stable isotopes C and N were present in some animal species (N=19). Apart from the above mentioned, several significant health indicators were chosen for evaluation which indirectly show health condition and quality of living conditions of the examined group. These health indicators were evaluated in relation to the diet. The results of this study indicate that the diet of Lombards' population was based on C3 plants and animal proteins, which is similar to the other localities in the time of the Migration Period. It shows a difference, namely in consumption of millet, providing that the Lombards to the Great Moravian's localities are compared. The millet seemed to be common part of...
33

Rámování klimatických politik: Diskurzivní analýza debat o oceňování emisí oxidu uhličitého v Kanadě a Austrálii / Framing Climate Policies: Discourse Analysis of Carbon Pricing Debates in Canada and Australia

Davidová, Kateřina January 2017 (has links)
Framing Climate Policies: Discourse Analysis of Carbon Pricing Debates in Canada and Australia Abstract The aim of this paper is to analyze and compare the discourses of Stephen Harper and Tony Abbot during federal election campaigns where climate policies played an unusually important role (2008 in Canada and 2013 in Australia). The study builds on a hypothesis, that according to the post-materialist theory and the Environmental Kuznets Curve, such economically advanced, democratic countries as Canada and Australia should be at the vanguard of climate action. However, in reality they are some of the worst performers when it comes to tackling carbon emissions. Both Harper and Abbott publicly promised to put in serious efforts to tackle climate change. However, when the question of setting a national price on carbon came up for discussion during the above-mentioned election campaigns, they both not only opposed it, but even tried to discredit it by framing the whole debate in overwhelmingly negative terms. In order to uncover what kind of frames and other discursive strategies the two politicians used to shape the debate, critical discourse analysis was applied to their public statements on the policy of carbon tax. Results of this analysis show that they used all of the frames that are typically associated...
34

Vývoj voltametrických metod pro detekci fytosterolů na elektrodách na bázi uhlíku / Development of voltammetric methods for detection of phytosterols on carbon-based electrodes

Zelenský, Michal January 2020 (has links)
The aim of this diploma thesis was to develop an electrochemical method for three phytosterols, namely stigmasterol β-sitosterol and ergosterol using voltammetry techniques on glassy carbon electrode and boron doped diamond electrode. The work builds on previous results, where it was shown that the electrochemical oxidation of phytosterols requires perchloric acid in acetonitrile. When this acid is used, a dehydration reaction occurs. Calibration dependences were measured here for all phytosterols in an environment with a water content of 0.43%. The stability of the signal with increasing distilled water content was further investigated. Then the calibration dependences in the increased water content were measured again. If we want to use HPLC-type separation techniques, we must first find out how the phytosterols will behave in this environment, and therefore the signal stability on the buffer content was investigated. The buffers used were phosphate and acetate buffer. Subsequently, the concentration dependence was measured in an environment with a higher content of phosphate buffer. Furthermore, the possibility of detecting two phytosterols at once was investigated. Key words: dehydration, glassy carbon electrode, boron doped diamond electrode, oxidation, phytosterols, voltammetry
35

Využití elektrochemického DNA biosenzoru při detekci poškození DNA způsobeného genotoxickým 2-nitrofluorenem / The Use of an Electrochemical DNA Biosensor in Detection of DNA Damage Caused by Genotoxic 2-Nitrofluorene

Stávková, Klára January 2014 (has links)
2-Nitrofluorene is a model representative of nitrated polycyclic aromatic hydrocarbons (NPAH) which belongs to a group of mutagens and carcinogens. Interaction of DNA with genotoxic 2-nitrofluorene was monitored by an electrochemical DNA biosensor made of a glassy carbon electrode (GCE) and low molecular weight DNA from salmon sperm. Techniques used are electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square-wave voltammetry (SWV). Using the EIS technique, no damage to DNA, which would cause strand breaks in DNA, was observed, whereas using the CV technique, the intercalation of NF to the structure of DNA was observed, leading to the formation of a NF-DNA complex. The intercalation results in a reduction of electroactive sites which can be oxidized. It was verified using the SWV technique, by which a decrease of the peak heights of adenosine and guanosine was observed. Because of the dangerous effect of NF on the structure of DNA, an electroanalytical method for its determination was developed. An applicability of the method was successfully tested on a model sample of sand. For the development of the technique, differential pulse voltammetry (DPV) was used in a mixture of the Britton-Robinson buffer of pH 7.0 and ethanol in a ratio of 7:3 (v/v) and with a periodic...
36

Stanovení butylhydroxyanisolu na elektrodách modifikovaných uhlíkovými nanotrubičkami / Determination of butylhydroxyanisole using electrodes modified by carbon nanotubes

Krejčová, Markéta January 2015 (has links)
This work was focused on study of a behaviour of the food additivum butylated hydroxyanisole on modified carbon electrodes by the voltammetric techniques - cyclic and differential pulse voltammetry. Glassy carbon and carbon paste electrode were used. Multiwalled carbon nanotubes (MWCNT) in combination with three different binders (acetonitrile, nafione or chitosane) were employed for the electrode modification. Carbon paste electrode was unable to modificate with film containing carbon nanotubes and acetonitrile, its active surface was treated only with nafione and chitosane film. All three mentioned modifications were applied in case of glassy carbon electrode. Butylated hydroxyanisole provided a significantly higher signal using electrodes modified with carbon nanotubes with all three binders in contrast to electrodes without any surface modification. The glassy carbon electrode with carbon nanotube / acetonitrile film on its surface appeared to be the most effective for analytical purposes. Voltammetric determination of butylated hydroxyanisole using this electrode provided a better defined and higher analytical signal and lower relative standard deviations in comparison with other ways of modification. The limit of detection of butylated hydroxyanisole obtained by cyclic voltammetry on glassy...
37

Voltametrické stanovení vybraných psychofarmak pomocí uhlíkových elektrod / Voltammetric Determination of Selected Psychopharmaceuticals Using Carbon Electrodes

Matouš, Petr January 2019 (has links)
Differential pulse voltammetry (DPV) was used for developing a method for the determination of phenothiazine derivatives, namely chlorpromazine (CHP) and levomepromazine (LMP), using a glassy carbon electrode (GCE) and a graphite electrode, both with a 2 mm disc diameter. Comparison of quantification limits (LQ) for both substances on both electrodes was performed. After optimizing and processing the results, the optimal conditions for measuring calibrations were as follows: Britton- Robinson (BR) buffer at pH 4.0. Calibration dependences were measured inthe concentration range from 1·10-7 to 1·10-4 mol·dm-3 . There was no need for electrochemical electrode regeneration or matrix pretreatment. The results showed higher measurement sensitivity for CHP, and the graphite electrode also showed higher sensitivity. Although there were measured lower concentrations with the graphite electrode in comparison to the GCE, because of the low repeatability of the measurements in the lower concentration range 1-10·10-7 mol·dm-3 , the LQ is comparable to the results reached on the GCE. Besides to the BR buffer, measurements in other matrices (drinking water and river water) were also made. The following LQ values were achieved: 1.0·10-6 mol·dm-3 (in BR buffer), 1.1·10-6 -1.4·10-6 mol·dm-3 (in drinking water) and...
38

Šest esejí o meta-regresní analýze / Six Essays on Meta-Regression Analysis

Havránková, Zuzana January 2015 (has links)
This dissertation thesis consists of six papers on macroeconomics, international economics, and energy economics. All the papers are tied together by the use of meta-regression analysis, which is essential for the derivation of robust policy-relevant conclusions from often conflicting results presented in the empirical literature. I use meta-analysis to quantitatively synthesize the reported research results on a given topic, correct the literature for publication selection bias, and filter out the effect of various misspecifications present in some primary studies. My results can be summarized as follows: 1) The elasticity of intertemporal substitution in consumption, a key input to all dynamic models in finance and macroeconomics, varies significantly across countries. The differences can be explained by the level of stock market participation, when countries with higher participation exhibit larger values of the elasticity; the mean reported elasticity is 0.5. 2) The effect of borders on international trade, which most authors find to be surprisingly large, can be explained away by innovations in methodology introduced in the last decade. When these innovations are taken into account jointly, the border effect disappears for developed countries, and is relatively small for developing countries. 3) When...
39

Stabilní izotopy uhlíku v letokruzích smrku jako marker napadení stromu patogenní houbou. / Carbon Stable Isotopes in Spruce Tree Rings as a Marker of Pathogenic Fungal Attack of Trees.

NECUDOVÁ, Lucie January 2013 (has links)
Trees are long living plants, which use carbon from the air and hydrogen and oxygen predominantly from soil water for their growth. They deposit these elements largely into a wood where they may persist for thousands of years. Tree growth is influenced by environment, especially by air temperature and precipitation. These factors have an effect on stomatal conductance and photosynthesis rate which influence carbon stable isotope ratio (13C/12C) in the tree tissue. This thesis is focus on stable carbon isotopes in tree-rings of Norway spruce attacked by honey mushroom, and Norway spruce which doesn?t show any signs of disease. The hypothesis of the thesis is based on an expected difference in carbon isotope fractionation during photosynthesis between the spruce attacked by honey mushroom and a ?healthy? spruce. The difference in isotope fractionation could be caused by water deficit induced by honey mushroom disease in the tree. We expect that the attacked spruce defends against water loss by closing stomata, and it could lead to lower CO2 concentration in the needles and higher ?13C value in tree-rings biomass The stable carbon isotope analysis (IRMS) was done on tree-rings of four spruce pairs, each one including an attacked spruce and spruce which didn?t show any signs of disease. Carbon isotope ratio of early wood, late wood and in biomass of the whole annual increment was measured. In contrary to our hypothesis we did not fined any systematic difference in isotopic composition between the attacked spruce and the spruce which did not show any signs of disease.
40

Ekologická omezení odnožování z kořenů u mokřadních rostlin / Ecological constraints limiting the root-sprouting ability in wetland plant species

SOSNOVÁ, Monika January 2010 (has links)
Wetland plant species rely largely on vegetative reproduction. Although all types of clonal growth organs are found in wetlands, special adaptations, e.g., turions, fragmentation and budding, are more frequent in true aquatic communities. However, root-sprouting is underrepresented, although it can be beneficial under disturbed conditions. This thesis focuses on ecological constrains potentially hindering root-sprouting in wetlands. This ability was studied in a wetland herb Rorippa palustris in relation to life history, injury timing and carbon economy of a plant. In addition, plant regeneration following submergence and severe disturbance was assessed.

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