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Arctic tundra dendrochronology
Lehejček, Jiří ; Svoboda, Miroslav (advisor) ; Monika, Monika (referee)
Historically unprecedented environmental change in the Arctic ecosystems is often given into the context of its past and possible future development. In the region where instrumental meteorological observations are scarce archives need to be investigated in order to address this issues. The comprehensive synthesis one of the archives: long-live circumpolar evergreen Juniperus communis L. shrub is presented here. 20 individuals from southwest Greenland were investigated at the cell anatomy level to understand the ecology of the species and unhide its potential for environmental and climate reconstructions. The findings are as follows:
i) Stop of exponential cross-sectional conduit-lumen widening with increasing age is in contrast with conduit-lumen nature of trees. This indicates that shrubs do not need to saturate their water and nutrient demands via traits of classical hydraulic conductivity law but rather developed different mechanisms. Extreme weather conditions result in prostrate growth form. However, different weather factors probably influence shrub growth differently: While snow and wind act mechanically (a), temperature influences the form of growth physiologically (b). a) So long as the young shrub stem has high resilience to bend back to an upright position after snow melt and so long as it can withstand the wind during the vegetation season it most likely grows upright and the conduit-lumens widen. b) Temperature, resp. freeze-thaw events are responsible for the shrubs preference of safety (finite size of conduit-lumens) over hydraulic efficiency, thus not allowing for more primary growth. All of these (and other) factors are apparently working together and the transition of vertical to more horizontal growth is gradual. As a consequence, the conduit-lumen sizes may not have to be further increased (due to ecophysiological restrictions possibly also must not) because water is no longer transported against gravity.
ii) Observed age/growth trend has to be taken into consideration for further employment of the wood anatomical parameter in paleoenvironmental studies. That is, shrub cell parameters can only be used for this purposes if correctly detrended. This allows for more accurate as well as longer reconstructions because youth trend was often neglected in reconstructions based on shrub annual-rings.
iii) The south-western Greenland Ice-Sheet (GrIS) melt rates reconstruction is presented for the whole 20th century. This part of GrIS is considered as the most active. According to the presented reconstruction current GrIS melt rates are not uncommon for the last century being comparable to first decades of 20th century. This finding is particularly important contribution to the debate on Atlantic meridional overturning circulation (AMOC). Too high fresh water inputs into the Northern Atlantic from GrIS melting may slow down or even stop the AMOC which would result in more continental climate in Europe. Presented results indicate that this threshold lies higher than observed current melt rates of GrIS.
Fascinating Juniperus comunnis species has shown to be able to address many ecological as well as environmental open questions and due to its longevity and abundant distribution has a great potential to become an important player in the Arctic research.
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Total contents and speciation of arsenic and selenium in plants growing in soils with different physico-chemical properties
Tremlová, Jana ; Száková, Jiřina (advisor) ; Vymazal, Jan (referee)
This dissertation thesis deals with uptake, accumulation and transformation of arsenic and selenium in plants growing on soils with different chemico-physical soil properties. The contents of arsenic were investigated in 99 wild plant species, coming from 27 different families and 6 different vegetables growing in arsenic contaminated soils. The results suggest that there are species-specific mechanisms which protects certain plants from the excessive uptake of arsenic from the soil. On the other hand, there are plants using a strategy of accumulation, which theoretically may increase the risk of arsenic entry into the food chain, whether through grazing cattle and wildlife or through consumption of vegetables growing on arsenic contaminated soils. The most prevalent arsenic compounds are AsV and AsIII. Other arsenic compounds occure as minor species. An important finding was detection of arsenobetaine in Plantago lanceolata L. and Carex praecox Schreb ..
The contents of selenium were examined in 73 species of wild plants, coming from 29 different families. The results suggest that naturally low levels of selenium in the soil of selected locations along with a low capability of selenium uptake via collected plant species lead to the low content of selenium in plant biomass which may contribute to selenium deficient throughout the food chain. Foliar application of selenate on wild plant communities and on some types of vegetables in our case Brassica oleracea var. italica can have a positive impact on increasing the selenium content in the aboveground biomass of these plants and by extension, increase the selenium content in the human diet. Dominant selenium compounds in the aboveground biomass of the analyzed plants were SeVI and selenomethionine, with variable proportion of other commonly occurring organic selenium compounds, which is mainly affected by plant species.
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Non-invasive methods for sex and steroid homones determination in gibbons of the genus Nomascus
Bolechová, Petra ; Bartoš, Luděk (advisor) ; Pavel, Pavel (referee)
The gibbon primates of the family Nomascus are classified as critically endangered species, and, to date, basic understanding and information about their biology is missing. With regard to the status of these animals in the wild and captive populations in zoos, being familiar with their reproduction, may improve captive breeding programs. Data collection in this study was to be carried out by the practical use of non-invasive methods (polymerase chain reaction for DNA extraction and enzyme immunoassays), using faecal samples for analysis. The first method, polymerase chain reaction, was used for sex determination in juveniles, because of their coat colour and visual similarity of secondary sex characteristic in both sexes; it is not possible to determinate sex without handling the animal. Another main purpose of this study is to try and answer the hypothesis regarding the ovarian cycle of females, factors influencing their hormone concentration and also the onset of sexual maturity in females and the timing of their fur colour change. Hypotheses were checked by monitoring the concentration of progesterone and oestrogen faecal metabolites and by evaluation of the composition of breeding groups of gibbons with the ZOO influence. During a four year period (from 2010 till 2014), there were a total of 51 animals analysed from 16 different zoos with a faecal sample count totalling 1618 samples. The results confirmed the use of noninvasive methods for sex determination, and thus ensuring the maximum welfare standards. Endocrinological analysis confirmed the hypothesis of the influence of the environment (ZOO) to the hormone concentrations and female´s pregnancy effect in conjunction with her age on the final results of the male - father hormone concentrations. The initial information in this study is the confirmation of the onset of ovarian cycle in young females without connection to their fur colour change and a significant factor of a mother´s impact and her territoriality. This study is the first to present a long term monitoring of ovarian cycles in females and hormone concentrations of other individuals, both male and female, and from various age groups. The results allow us to understand the possible impact of zoo environments on the reproductive status of these gibbons and contribute to the general improvement of breeding management.
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Confidence Cycles and Liquidity Hoarding
Audzei, Volha
Market confidence has proved to be an important factor during past crises. However, many existing general equilibrium models do not account for agents’ expectations, market volatility, or overly pessimistic investor forecasts. In this paper, we incorporate a model of the interbank market into a DSGE model, with the interbank market rate and the volume of lending depending on market confidence and the perception of counterparty risk. In our model, a credit crunch occurs if the perception of counterparty risk increases. Our results suggest that changes in market confidence can generate credit crunches and contribute to the depth of recessions. We then conduct an exercise to mimic some central bank policies: targeted and untargeted liquidity provision, and reduction of the policy rate. Our results indicate that policy actions have a limited effect on the supply of credit if they fail to influence agents’ expectations. Interestingly, a policy of a low policy rate worsens recessions due to its negative impact on banks’ revenues. Liquidity provision stimulates credit slightly, but its efficiency is undermined by liquidity hoarding.
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A pair of phase-synchronized semiconductor lasers for length metrology
Hucl, Václav ; Holá, Miroslava ; Čížek, Martin ; Řeřucha, Šimon ; Pham, Minh Tuan ; Pravdová, Lenka ; Lazar, Josef ; Číp, Ondřej
Semiconductor lasers are increasingly widespread in areas that have been so far dominated by He-Ne lasers. One of such areas is the length metrology, where He-Ne laser operating at 633nm wavelength is still a traditional source of coherent light for laser interferometers distance measuring. The advantages of semiconductor lasers compared with He-Ne laser are greater optical power and a significantly wider range of wavelength tuning without mode jumps. Another advantage is the possibility of frequency modulation of wavelength of the laser diode by directly changing the injection current. The benefits predetermine these laser diodes for the realization of dual-frequency laser sources for heterodyne interferometry. In this case, using a phase-locked loop technique the optical frequency of a laser diode is locked to the optical frequency of another laser diode with a certain frequency offset in the MHz order. In our contribution we present utilization of DBR laser diodes in implementing a dual-frequency laser source for laser interferometry with heterodyne detection.\n
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Phase coherent transfer of stable optical frequency for sensory networks
Čížek, Martin ; Pravdová, Lenka ; Hucl, Václav ; Řeřucha, Šimon ; Hrabina, Jan ; Mikel, Břetislav ; Lazar, Josef ; Číp, Ondřej
Using long-haul optical fiber links for phase coherent transfers of stable optical frequencies has been developed by metrological laboratories for at least a decade. Present boom of optical fiber sensors puts a demand on transferring this technology from laboratories to industrial practice. A remote calibration of fiber Bragg grating tensometers can be an example. In our contribution we present a 306 km long fiber link between laboratories of ISI in Brno and CESNET in Prague. The line uses a telecom fiber with a dedicated DWDM window at 1540-1546 nm. The setup implements a phase coherent transfer of a laser standard working with 1540.5nm wavelength and a bi-directional transfer of 1PPS timestamps from radiofrequency standards at the both ends of the line. A long-term measurement of transport delay fluctuations and relative stability of the line are discussed.
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HUMAN ACTION RECOGNITION IN VIDEO
Řezníček, Ivo ; Baláž, Teodor (referee) ; Sojka, Eduard (referee) ; Zemčík, Pavel (advisor)
Tato disertační práce se zabývá vylepšením systémů pro rozpoznávání činností člověka. Současný stav vědění v této oblasti jest prezentován. Toto zahrnuje způsoby získávání digitálních obrazů a videí společně se způsoby reprezentace těchto entit za použití počítače. Dále jest prezentováno jak jsou použity extraktory příznakových vektorů a extraktory pros- torově-časových příznakových vektorů a způsoby přípravy těchto dat pro další zpracování. Příkladem následného zpracování jsou klasifikační metody. Pro zpracování se obecně obvykle používají části videa s proměnlivou délkou. Hlavní přínos této práce je vyřčená hypotéza o optimální délce analýzy video sekvence, kdy kvalita řešení je porovnatelná s řešením bez restrikce délky videosekvence. Algoritmus pro ověření této hypotézy jest navržen, implementován a otestován. Hypotéza byla experimentálně ověřena za použití tohoto algoritmu. Při hledání optimální délky bylo též dosaženo jistého zlepšení kvality klasifikace. Experimenty, výsledky a budoucí využití této práce jsou taktéž prezentovány.
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A NEW DAWN OF NAMING, ADDRESSING AND ROUTING ON THE INTERNET
Veselý, Vladimír ; Muntan,, Jordi Perelló (referee) ; Grasa, Eduard (referee) ; Day, John (referee) ; Švéda, Miroslav (advisor)
Internet roku 2015 se potýká s problémy, které jsou důsledky špatného designu pojmenovávání a adresování v TCP/IP a jež mají přeneseny vliv i na škálovatelnost směrování. Problémy jako růst páteřních směrovacích tabulek, neefektivní multihoming sítí či mobilita zařízení a mnohé další zadávají k otázce, jestli není třeba architekturu Internetu pozměnit. V teoretické části je kvantifikován dopad problémů, možná řešení a zejména je formálně definována teorie kompilujicí poznatky významných publikací zabývajících se problematikou pojmenování, adresování a směrování v počítačových sítí. Tato práce se zabývá dvěma konkrétními technologiemi, jež mají ambicí Internet měnit - Locator/Id Separation Protocol a Recursive InterNetwork Architecture. Výstupem práce jsou vylepšení funkcionality obou výše zmíněných technologií. Za účelem praktického ověření dopadů našeho výzkumu jsou vyvinutý a popsány nové simulační modely pro OMNeT++, které jsou věrné úrovni detailu popisu ze specifikací.
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The contributions of the sections (NACE-CZ) to the creation of gross value added
BEDNÁŘOVÁ, Monika
The aim of this thesis was to evaluate the contributions of the sections (NACE-CZ) to the creation of gross value added. The first part of this thesis described the theoretical concepts relating to national economic gross value added. Analytical processes were used for the calculations, which may be used only if we are dealing with an additive link between individual factors. The sections' contributions to the creation of national eco-nomic gross value added were evaluated in the practical part, on the basis of the proc-esses set forth in the methodology. In the given time horizon, contributions by institu-tional sectors and groups of sections classified according to the level of technology showed a certain dependency on the actual economic cycle. Although the strongest in-stitutional sector is non-financial enterprises, they were the ones most affected during the crisis period, together with government institutions. On the contrary, the financial institution sector showed a strong position during the crisis period. In terms of the grouping of the sections according to the level of technology, the greatest contribution to national economic gross value added is by groups B1 and B2. The influence of the economic cycle was noted in all the groups but, according to the results, group C did not react quite as sensitively as the other groups.
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Personal income taxation from employment, self-employment and rental income in 2014
HOUFOVÁ, Petra
The aim of my diploma thesis is to analyze the principles of personal income taxation including social contributions and health insurance. Overall personal income tax is composed of five different partial tax bases. The first partial tax base consists of income from employment, the second one is self employed income, the third is income from rental property, the fourth is income from capital and the last is "other income". This thesis will deal with the first four partial tax bases. In the theoretical section I have described the most important concepts of personal income tax structure, social contribution and health insurance. The practical part is divided into four chapters according to partial tax base. I have chosen six different amounts from 100 000 CZK to 5 000 000 CZK which were used for tax calculation. The main goal is to compare partial tax bases of personal income tax in 2014.
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