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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.
1

EXTREME TOLERANCE IN THE EUTARDIGRADE SPECIES HYPSIBIUS DUJARDINI

Vasanthan, Tarushika 11 1900 (has links)
Tardigrades are microscopic animals that can survive exposure to multiple extreme conditions. This remarkable ability makes them suitable laboratory model organisms for conducting biological to astrobiological research. Whereas tardigrade extreme-tolerance research has been focused predominantly on their ability to endure extreme desiccation, responses to other extraordinary conditions (i.e. hypergravity, pH, radiation and low temperature) remain un-described. These extreme tolerance research areas, in addition to life history traits, were documented in our studies on the eutardigrade species Hypsibius dujardini. We found that specimens tolerated extreme g-equivalent forces (i.e., 16060g) and radiation levels (i.e. 5 kGy), with decreased survivorship at increased accelerations and radiation doses. Radiation induced bystander effects (RIBEs) manifested as a threshold response, with the threshold value between 3 and 5 kGy. Extreme acidic (pH 1 and 2) and alkaline (pH 11 to 14) conditions caused death instantaneously, while exposures to pH 4, 6, 8, 9, and 10 were tolerated. Tardigrade eggs reared at 0 °C for 4 days developed relatively slowly, diminishing their biological age relative to their chronological age. Extending cold exposure (0 °C) time (days = 10, 20 and 40) decreased incubation time (days = 3, 2 and 1, respectively) at 22 °C; lengthening cold exposure time led to decreased growth in juveniles and lowered survivorship in adults, suggesting that costs are associated with increasing incubation time at 0 °C. Tolerance to hypergravity, large radiation doses and a wide-range in pH conditions support the notion that tardigrades are suitable organisms for astrobiological research, particularly in exploring parameters associated with potential transfer and habitability in extreme environments. RIBEs in adult tardigrades and the ability for tardigrade embryos to alter their ‘biological clocks’ based on exposed cold temperature duration have applications in biological research. Characterizing molecules involved in bystander signaling and response and biological clock adjustments during development could have important implications for improving biological practices such as radiotherapy and cryopreservation. / Thesis / Doctor of Philosophy (PhD) / While interest in tardigrade extreme tolerance research has increased over the last decade, many research areas continue to be underrepresented or non- existent. And, while recognized tardigrade species have been increasing steadily in number, fundamental biological details, like individual life history traits, remain unknown for most. The main objectives in this thesis therefore were to survey the life history traits for the freshwater tardigrade species Hypsibius dujardini, increase knowledge about its extreme-tolerance abilities and describe its utility in astrobiological and biological studies. Research involved tardigrade tolerance to hypergravity, pH levels and radiation exposure (and associated radiation-induced bystander effects) as well as responses to temperature changes during development. Findings reported in this dissertation provide new data about H. dujardini, thereby narrowing the information gap that currently exists in the literature for this species.
2

Parametrické rozpočtování - inovace způsobu určování nabídkových cen ve stavebním podniku / Parametric budget estimation - Innovation of the method of determining bid prices in a construction company

Vrbka, Marek January 2020 (has links)
Today's trend in construction is the emphasis on the most extensive unification. There are a number of building systems and technologies that can be clearly defined in terms of their technological solution. This trend opens up opportunities for innovative pricing approaches, or prices at which their construction products are offered by construction companies to their potential customers. From the customer's viewpoint, the offer price for the building, determined by the construction company, is the dominant part of the purchase price of the building work. The traditional way of determining the offer is the itemised budget. Creating itemised budgets is costly for companies and time-consuming, especially due to the costs of specialised budgets and their hardware and software equipment. The main idea of the dissertation is the effort to innovate in the area of budgeting of building structures designed for housing in the Czech Republic. The dissertation focuses more on the innovation of bidding in construction companies in the form of parametric budgeting. Parametric budgeting is an innovation based on parametric cost estimation methods. The principle of parametric budgeting correlates statistical analyses by calculating the cost of model cases with specific cases using the regression functions set for a given data set. A link between model and specific cases is spatial, technical, technological and material parameters. The dissertation’s overall objective is to evaluate in particular whether parametric budgeting makes it possible to increase the efficiency of the bidding process in enterprises. In the thesis are used calculation methods to determine construction costs in the form of item budgets. In addition, mathematical methods are used to determine the regression function of a particular data set for creating and examining cost estimation relationships. In the dissertation are used investment procedures to determine simple payback period, cash flow, etc.

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