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Habitat requirements of two species Huperzia selago and Lycopodium annotinum in sandstone area of NP Bohemian Switzerland
Trachtová, Pavla ; Hadincová, Věroslava (advisor) ; Adámek, Martin (referee)
Species Huperzia selago and Lycopodium annotinum occur in cold and humid habitats with acid substrate. These are mainly mountain areas in the Czech Republic, but also sand gorges, where the temperature inversion is common. The temperature inversion causes the fact, that temperature conditions in ravines are different from the climatic conditions of surroundings, which causes high rate of species variety among the habitats. In these places, Montane and Boreal species grow in low altitudes and in the proximity of thermophile species. The presence of montane and boreal species in sand ravines is largely influenced by inherence of temperature inversion, which is determined by features of ravine (depth, breadth, orientation) and by weather conditions. Other important agents (excepting microclimatic conditions), which influence the prevalence of these kinds, are microelement availability and the rate of competition. In Czech Republic, both species Huperzia selago and Lycopodium annotinum fall into C3 category, which means that they indicate permanent regression in our nature. In the case of my field survey in the area of the Bohemian Switzerland National Park I confirmed this tendency for species Huperzia selago.
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Temperature Inversion and Heat Transport Against the Temperature Drop in Two-Phase Convection of Cryogenic Helium
Urban, Pavel ; Schmoranzer, D. ; Hanzelka, Pavel ; Skrbek, L.
In the system of two bodies A and B connected by a two-phase vapour-liquid system consisting only of cryogenic helium, we observed anomalous heat transport from the colder but heated body B to the warmer but cooled body A. We noticed this effect during the process of liquid evaporation inside a cylindrical pressure convection cell used for study of Rayleigh-Bénard convection. This anomalous heat transfer occurs under non-equilibrium conditions, owing to the phase transitions that take place inside the cell while temperature inversion develops between the heated but cooler bottom plate and the cooled but warmer top plate. This process is, by virtue of the system being open with respect to heat transport, in no contradiction to the second law of thermodynamics, and a numerical model was formulated that describes the observations with good agreement.
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