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Ecological differences between herbs and woody plants, and evolution of the herbaceous habit
Klimeš, Adam ; Herben, Tomáš (advisor) ; Lens, Frederic (referee) ; Těšitel, Jakub (referee)
Ecological differences between herbs and woody plants, and evolution of the herbaceous habit Adam Klimeš, doctoral thesis Abstract Flowering plants (angiosperms), which make up most present-day vegetation, were originally woody. While flowering plants have repeatedly given rise to herbaceous lineages since their first appearance, we lack a clear explanation for these common evolutionary events. Freezing temperatures and drought periods have been proposed as factors which had caused huge success of the younger growth form but the evidence is very limited and not in favour of these hypotheses. In this thesis, we aimed to build the foundations of research on the evolution of herbs. We outlined new potential drivers of the evolution of herbs, suggested solutions to some methodological challenges and provided evidence about differences between herbs and woody plants relevant to the hypotheses on herb evolution. To this end, we used common garden experiments with young plants of both growth forms and global trait data from public databases which we evaluated using phylogenetic comparative techniques. Annuality of aboveground biomass and fast life-strategy of herbs are characteristics which differentiate them from woody plants and which in some conditions are expected to be behind their success. Apart from the...
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Central Bank Transparency and Price Stability
Katuščáková, Dominika ; Horváth, Roman (advisor) ; Luňáčková, Petra (referee)
The thesis investigates the central bank transparency employing the Monetary Policy Transparency Index. The main objective is to investigate recent trends in the central bank transparency. First, the level of monetary policy transparency is investigated from various aspects, as, for instance, time or geographical aspect. In the next part, all the data are averaged and linear regression analysis is carried out to detect the determinants of the monetary policy which explain the variation among the individual central banks. Finally, panel regressions are conducted to explore the time variation in the monetary policy transparency in the countries. Throughout the text, all the results are compared with the results presented in the paper by Dincer & Eichengreen (2009). The data show that the overall time trend in the level of monetary transparency is increasing. It can be concluded that inflation targeters are generally more transparent than countries with other frameworks. The same applies to advanced countries and emerging and developing countries. The de facto exchange rate regime and all political variables used significantly determine the variation in the monetary policy transparency comparing individual countries. GDP per capita and financial depth significantly influence the time variation in the...
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Relationship among moisture flux anomalies, extreme precipitation, and floods in central Europe
Gvoždíková, Blanka
Floods associated with extreme precipitation are one of the most serious natural hazards, which produce substantial human and socio-economic losses in central Europe. One way to reduce the impact of flooding is by increasing preparedness with better flood forecasts and warnings, which is not possible without a proper understanding of physical processes leading to a flood hazard. However, frequent research on floods in relation to causal precipitation and synoptic conditions is usually carried out regionally, although some events often affect areas of a size of entire countries or even larger. The thesis was focused exactly on these large-scale precipitation and flood events that occurred in the second half of the 20th century and then until 2013, for which the size of the affected area is as crucial in the extremity assessment as the magnitude of flood discharges or precipitation totals. The extremity indices used for the assessment of extreme precipitation and flood events connected both aspects. The larger area of interest defined within central Europe allowed examining the spatial structure of events, the differences between them, and their relation to conditions in the atmosphere. To connect the extremes of precipitation with extremes in atmospheric conditions, the causal circulation was...
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Evaluating the predictability of virtual exchange rates using daily data
Řanda, Martin ; Polák, Petr (advisor) ; Kukačka, Jiří (referee)
Virtual worlds have garnered the attention of researchers from various disci- plines and are viewed as particularly valuable to economists due to their open- ended design. In this thesis, we review a popular online multiplayer game's economy and focus on exchange rate predictability in a virtual setting as only a limited body of literature investigated this topic. The well-established unpre- dictability puzzle is addressed by exploiting a unique daily time series dataset using a vector autoregressive framework. Apart from a significant Granger- causal relationship between the virtual exchange rate and the player popula- tion, the system is shown to be less interconnected than expected. Furthermore, an out-of-sample exercise is conducted, and the forecasting performance of our models is examined in comparison to that of a simple no-change benchmark in the short term. Based on the evaluation methods used, the two measures of the virtual exchange rate are found to be somewhat predictable. We suggest two explanations for this inconsistency between the virtual and real-world exchange rates: data frequency and lack of complexity in the considered online economy.
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Relationship among moisture flux anomalies, extreme precipitation, and floods in central Europe
Gvoždíková, Blanka ; Müller, Miloslav (advisor) ; Nissen, Katrin (referee) ; Wypych, Agnieszka (referee)
Floods associated with extreme precipitation are one of the most serious natural hazards, which produce substantial human and socio-economic losses in central Europe. One way to reduce the impact of flooding is by increasing preparedness with better flood forecasts and warnings, which is not possible without a proper understanding of physical processes leading to a flood hazard. However, frequent research on floods in relation to causal precipitation and synoptic conditions is usually carried out regionally, although some events often affect areas of a size of entire countries or even larger. The thesis was focused exactly on these large-scale precipitation and flood events that occurred in the second half of the 20th century and then until 2013, for which the size of the affected area is as crucial in the extremity assessment as the magnitude of flood discharges or precipitation totals. The extremity indices used for the assessment of extreme precipitation and flood events connected both aspects. The larger area of interest defined within central Europe allowed examining the spatial structure of events, the differences between them, and their relation to conditions in the atmosphere. To connect the extremes of precipitation with extremes in atmospheric conditions, the causal circulation was...
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Liquidity and Predictability of Cryptoassets
Mjartanová, Viktória ; Krištoufek, Ladislav (advisor) ; Čech, František (referee)
The relationship between liquidity and return predictability may be an im- portant aspect to consider when investing in cryptoassets. We examine this relation using both cross-sectional as well as panel data. First, we calculate a set of predictability measures and aggregate the results into four variables. We then regress the predictability variables on a set of controls and two measures of liquidity, specifically the Amihud illiquidity ratio and the Corwin-Schultz spread estimate. The other independent variables include the logarithm of volume, turnover ratio and Garman-Klass volatility. Results from the cross- sectional analysis indicate that liquidity negatively impacts the degree of return predictability. Moreover, findings from a subset of panel data, including only 50 cryptoassets with the largest market capitalization, provide some evidence in favor of this relationship. Results from full panel data, however, present contradictory evidence. For these regressions, liquidity is found to be either in- significant or to possess a positive impact on the degree of return predictability. Altogether, we obtain mixed evidence about the effect of cryptoasset liquidity on return predictability. JEL Classification C53, C58, G14 Keywords Cryptoassets, Predictability, Liquidity, Panel data Title...
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Ecological differences between herbs and woody plants, and evolution of the herbaceous habit
Klimeš, Adam ; Herben, Tomáš (advisor) ; Lens, Frederic (referee) ; Těšitel, Jakub (referee)
Ecological differences between herbs and woody plants, and evolution of the herbaceous habit Adam Klimeš, doctoral thesis Abstract Flowering plants (angiosperms), which make up most present-day vegetation, were originally woody. While flowering plants have repeatedly given rise to herbaceous lineages since their first appearance, we lack a clear explanation for these common evolutionary events. Freezing temperatures and drought periods have been proposed as factors which had caused huge success of the younger growth form but the evidence is very limited and not in favour of these hypotheses. In this thesis, we aimed to build the foundations of research on the evolution of herbs. We outlined new potential drivers of the evolution of herbs, suggested solutions to some methodological challenges and provided evidence about differences between herbs and woody plants relevant to the hypotheses on herb evolution. To this end, we used common garden experiments with young plants of both growth forms and global trait data from public databases which we evaluated using phylogenetic comparative techniques. Annuality of aboveground biomass and fast life-strategy of herbs are characteristics which differentiate them from woody plants and which in some conditions are expected to be behind their success. Apart from the...
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Forecasting in futures markets: Front, back and rolling contracts
Badáňová, Martina ; Krištoufek, Ladislav (advisor) ; Adam, Tomáš (referee)
In the thesis we analyze sixteen commodity futures markets belonging to four families (energy type, grains, metals and other agricultural commodities) utilizing futures prices of front, back and roll futures contracts. As the tests for cointegration between front and back futures prices give us contradictory results we concentrate on roll contracts defined as the difference between front and back commodity futures contracts. We found that all commodity roll futures except natural gas and wheat futures exhibit long memory, which is usually connected with the fractal market hypothesis. Further, we employ specific ARMA and ARFIMA models and rolling window one-day-ahead technique to predict roll futures contract prices. Based on analysis of relation between resulting predictability and liquidity of roll futures contracts we concluded that lowest predictability is linked with the lowest liquidity among all commodities except metals and found evidence that predictability is positively dependent on liquidity among all commodities except metals, lumber, soybean oil and soybeans. The revealed dependence is strongest for energy type commodities. The relations and dependencies on the commodity futures markets are of high importance for all market participants such as hedge managers, investors, speculators and also for...
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Některé aspekty dynamiky letního monsunu v Asii v reanalyzovaných meteorologických datech
Jajcay, Nikola ; Raidl, Aleš (advisor) ; Mikšovský, Jiří (referee)
The Asian summer monsoon (ASM) is a high-dimensional and highly complex phenomenon affecting more than one fifth of the world population. The intraseasonal component of the ASM undergoes periods of active and break phases associated respectively with enhanced and reduced rainfall over the Indian subcontinent and surroundings. In this thesis the nonlinear nature of the intraseasonal monsoon variability is investigated using the leading Empirical Orthogonal Functions of ERA-40 sea level pressure reanalyses field over the ASM region. The probability density function is then computed in spherical coordinates using the Epaneshnikov kernel method. Three significant modes are identified. They represent respectively (i) the East - West mode with above normal sea level pressure over East China sea and below normal pressure over Himalayas, (ii) the mode with above normal sea level pressure over East China sea (without compensating centre of opposite sign as in (i)) and (iii) the mode with below normal sea level pressure over East China sea (same as (ii) but with opposite sign). The relationship with large-scale forcing is also investigated by stratifying the PCs according to representing indices. The regimes derived from spherical PDFs appear to be opposite under opposite large-scale conditions. EOF technique with...
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