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Short-Term Forecast Based on Image of Sky
Volf, Martin ; Španěl, Michal (referee) ; Hradiš, Michal (advisor)
The bachelor's thesis submitted is dedicated to weather forecast based only on a video stream. At first, basic weather information which the sky can provide are presented. Cloud types including their properties and methods which the sky can most efficiently describe are dealt with. At second, basic circumstances between weather information are discussed. The objective of this work is to prove accuracy of the methods used for gaining data from the video stream and to find out whether it could be possible to use them for forecasting the rain, air humidity and sunshine for the period of time one hour later.
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The archeological evidence of medieval pottery production in Bohemia
Volf, Martin ; Sláma, Jiří (referee) ; Klápště, Jan (advisor)
Ve většině archeologických situací, ať již pravěkých či středověkých, tvoří keramika nejpočetnější a často i jedinou kategorii nálezů. Z tohoto faktu vyplývá potřeba pracovat s keramikou jakožto archeologickým pramenem. Archeologové jsou nuceni pracovat každodenně s touto poměrně na první pohled zanedbatelnou součástí života minulého člověka a na jejím základě konstruovat své teorie. V momentě zpracovávání keramiky však nastává zásadní problém, který tkví ve výpovědních možnostech keramiky jako archeologického pramene. Otázky, které si archeolog na počátku práce s keramikou klade (pokud si vůbec nějaké klade), jsou často nepoučené a žádají odpovědi, které studium keramiky samo o sobě neposkytuje. Práce vznikající na základě těchto otázek jsou pak často zavádějící, či v lepším případě konstatují neřešitelnost původních otázek, z čehož vyplývá posléze skepse, která je dnes spojena s tématem středověké keramiky. Předpokladem pro řešení této situace je uvědomění si pozice tohoto tématu na pomezí několika vědních oborů Středověká keramika je jedním z témat, u kterých si je třeba uvědomit nutnost interdisciplinárního studia. Spoluprácí s keramology (technology keramiky) a dalšími odborníky ( etnografy a samotnými hrnčíři) můžeme dospět k formulování otázek, které se můžeme pokusit zodpovědět na základě středověké...
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Specificity of insect-plant associations and their role in the formation of plant defenses and speciation
VOLF, Martin
The aim of this dissertation is to investigate what role insect-plant interactions play in the formation of host-plant defenses and in the diversification of both groups. We show that various groups of herbivore respond differently to host-plant defenses. Therefore plant defenses diversify into suites of complementary traits, as individual traits fail to provide protection against specialized herbivores. Further, we identify what levels of host-phylogeny shape the food-web structure of insect herbivores. We show that specialized herbivores are affected mainly by the terminal parts of the host-phylogeny. In contrast, more polyphagous guilds are affected mainly by the mid-levels of the host phylogeny because the effects of terminal or deeper phylogeny seem to be surpassed by other factors in more generalist insect species. In the last chapter, we show how specialized insect-plant interactions generated by tight insect-plant coevolution can influence the speciation in plants over environmental gradients.
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Magnetic orientation of spider webs of the Amaurobiidae spiders
Volf, Martin ; Nováková, Petra (advisor) ; Mrkvičková Kořanová, Diana (referee)
Abstract
First of all in theoretical part of my bachelor thesis I deal with general characteristics of spiders and more specifically Amaurobiidae spiders. My first section summarizes information about magnetoreception as an ability to sense the Earth´s magnetic field. Next I describe basic information about three theories that represent models of functioning magnetoreception. Electromagnetic induction theory is based on the principle of an electric circuit through which flows electricity. Chemical magnetoreception theory or free radical theory is based on complex biochemical reactions which are produced by magnetic field and includes pairs of free radicals as intermediates. And the last but not least magnetite theory that presume presence of magnetite in various tissue which acts as a magnet, and at the moment of trying to compare with magnetic field applying pressure to the secondary receptors or directly affects the activity of nerve cells. Further I describe various forms of magnetic orientation for example magnetic compass, magnetic alignment and magnetic map. The end of the theoretical part is about the general knowledge of magnetoreception and magnetic orientation in Amaurobiidae spiders.
The practical part is about my own research. I examined magnetic orientation of particular spider webs at 3 locations. I tried to find varied locations in different forest stands and slopes. My data collection was more difficult because of meteorological conditions. Long sweltering summer completely dried forests and all animals activity was inhibited. Then it came dramatic cooling and large amounts of rainfalls. In 2015 wasn´t basically a kind of transition phase between summer and autumn. Finally I gathered all data that I needed, and from the statistical processing clearly concluded that the resulting vectors were most commonly ranged from 100° to 180°. More than 60% spider webs were oriented southeast to south. Of course I founded exceptions and curious cases.
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Short-Term Forecast Based on Image of Sky
Volf, Martin ; Španěl, Michal (referee) ; Hradiš, Michal (advisor)
The bachelor's thesis submitted is dedicated to weather forecast based only on a video stream. At first, basic weather information which the sky can provide are presented. Cloud types including their properties and methods which the sky can most efficiently describe are dealt with. At second, basic circumstances between weather information are discussed. The objective of this work is to prove accuracy of the methods used for gaining data from the video stream and to find out whether it could be possible to use them for forecasting the rain, air humidity and sunshine for the period of time one hour later.
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Insect herbivores drive the loss of unique chemical defense in willows
VOLF, Martin
The thesis examines the effects of chemical and mechanical defensive traits on insects in a local community of 11 Salicaceae species growing in sympatry. The results repeated loss of willow specialized chemical defense. This could be due to its low protective value and high energy costs. Our study thus shows that the balance between costs and benefits of defensive traits is not necessarily in favor of specialized defenses and illustrates a process, which may lead to the reduction in a defensive trait.
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