National Repository of Grey Literature 9 records found  Search took 0.01 seconds. 
High-Level Petri Nets Interpreter in Python
Grigorev, Danil ; Kočí, Radek (referee) ; Janoušek, Vladimír (advisor)
This work is targeting a goal of implementing a high level Petri net interpret in Python. The implementation is based on SNAKES library. The final product is capable of executing and visualising Petri nets, created by user. The simulator is based on distributed systems theory and is executed in real-time. The end user is able to experience a simple and human-friendly API, made for creation and execution of High-Level Petri Nets.
Evolution of sex determination and sex chromosomes in snakes
Charvát, Tomáš ; Kratochvíl, Lukáš (advisor) ; Šmíd, Jiří (referee)
Snakes form with almost 3700 described species more than one third of all squamate reptiles. The vast majority of snake species belong to the group Caenophidia, which is the best explored group of snakes for sex chromosomes. In contrast, sex chromosomes of the two other groups of snakes - Scolecophidia and Henophidia have so far been paid little attention. All snakes studied so far possess genotypic sex determination. Representatives of all Caenophidian families were observed with a female heterogamety sex determination system (ZZ/ZW) and it was widely accepted that this system was common to all snakes. This claim was recently refuted when a male heterogamety (XX/XY) was confirmed in a python (Python bivittatus) and a boa (Boa imperator), two representatives of Henophidia. In Henophidia, besides the XX/XY system, the ZZ/ZW system was reported in the only known representative of this group with heteromorphic sex chromosomes - A. sp. cf. dumerili. Sex chromosomes or sex determination systems are unknown in Scolecophidia. Caenophidian heteromorphic sex chromosomes have enabled the study of the phenomena associated with the gradual differentiation of sex chromosomes. These include W chromosome degeneration, the accumulation of repetitive elements, the fast Z phenomena, gene dosage compensation, and...
Evolution of sex chromosomes and karyotypes in snakes
Augstenová, Barbora ; Kratochvíl, Lukáš (advisor) ; Majtánová, Zuzana (referee)
Snakes (Serpentes) are a group of squamate reptiles (Squamata) including more than 3600 species. The vast majority of snakes are from the group Caenophidia, which includes approximately 90% of all extant snake species and represents the most studied lineage. Squamate reptiles are variable in sex determination and genome organisation, however, caenophidian snakes are quite stable in these respects. The typical - and probably ancestral - snake karyotype is composed of 36 chromosomes with 16 macro- and 20 microchromosomes. In all snake species, genotypic sex determination (GSD) is expected and it was assumed until recently that all snakes possessed ZZ/ZW sex chromosomes. The main reason for this is that most of the studied snakes were from the group Caenophidia and in the rest of the snake lineages it was believed that their sex chromosomes were homologous. In fact, the sex chromosomes of non-caenophidian snakes have not yet been identified - with the single exception of Acrantophis dumerili. Nevertheless, a recent study showed that there was an independent evolution of XX/XY sex chromosomes in pythons and boas. Sex chromosomes of these snakes are homomorphic and so far they have not been detected by classical cytogenetic methods. In this context, the aim of this study is to explore whether it is...
Factors influencing worldwide zoo collections of lizards, snakes, turtles and crocodiles: effect of conservation status, body size and their attractiveness to humans
Janovcová, Markéta ; Landová, Eva (advisor) ; Komárek, Stanislav (referee)
There is a large number of species existing in the world; each year, however, the number of the endangered ones rapidly increases. Nowadays, captive breeding becomes an option for their survival in refugees. Sufficient population with satisfactory breeding management gives hope for survival to the endangered species (in mid-term) or even possible future reintroduction to their natural habitat. WAZA is currently the world's leading association of worldwide zoos and similar breeding facilities. Because these institutions operate as a network to facilitate the exchange of reared individuals, for conservation purposes, their captive populations may be seen as one large population characterized by its size, i.e., the total number of individuals. Such view is currently recognized by many conservationists as the so-called concept of Noah's Ark. The space on the Ark is limited, therefore it is needed to heed the characteristics of the species aboard to maximize the conservation potential. Many factors influence the presence of species in zoological gardens. Following previous studies we selected some factors that may be important, i.e., body lenght, taxonomy, and IUCN status. Analysis of these factors among the main reptile clades shall reveal the pattern of reptile composition in worldwide zoos. One of the factors...
Reproductive strategies in boid snakes
Vejvodová, Tereza ; Frynta, Daniel (advisor) ; Rehák, Ivan (referee)
The important part of life history of species is number and size of offspring, which is limited by size of maternal investment. Family of boas (Boidae) comprises species with various maternal investments. The species of study was Cuban boa (Chilabothrus angulifer) having small litter size, but producing one of the biggest neonates from family Boidae. The aim of the thesis was to analyze relationships between life-history parameters and try to find possible evolutionary causes of this huge maternal investment. Results show, that the female's decision to reproduce is under "Capital breeder" strategy, when size of the female positively influence litter size and offspring size. Surprising result is that smaller (younger) females are producing more sons than daughters in accordance with "Local resource competition" hypothesis. Fitness of the young should increase with birth size. That was confirmed only in interspecific survival rate being very high in Cuban boa. Keywords: snakes, Cuban boa, maternal investment, life history, SSD, sex ratio
Evolutionary and developmental aspects of dentition of squamate reptiles
Zahradníček, Oldřich ; Horáček, Ivan (advisor) ; Míšek, Ivan (referee) ; Peterková, Renata (referee)
EVOLUTIONARY AND DEVELOPMENTAL ASPECTS OF DENTITION OF SQUAMATE REPTILES Summary of the PhD. thesis Dentition and its evolutionary modifications played important roles during the radiation of reptiles. It is generally accepted that a plesiomorphic state for reptiles is represented by homodont, polyphyodont dentition with conical or cylindroconical teeth. However, in contrast to mammalian dentition which is the object of intensive research, reptilian dentition is studied only rarely. I therefore focused on developmental and evolutionary aspects of squamate dentition and used histological, immunohistochemical and in situ hybridization methods, computerised tomography, rentgenography and scanning electron microskopy. The goals of this work were as following: (a) to choose the model taxa representing squamate lineages relevant from a phylogenetic position as well as possessing dissimilar types of dental adaptations; (b) to evaluate using of these taxa as model species; (c) in these taxa describe basic odontogenic features. As a species with generalized dentition gecko Paroedura picta was chosen, the up coming reptilian model species with features also present in a wide spectrum of other lizards. I focused mainly on the developmental differences between teeth of the null and functional generations, development...
The key to determining the boid snakes of the subfamily Erycinae for the needs of the ČIŽP.
ŽÍDEK, Jakub
Snakes of the subfamily Erycinae belong to family Boidae. Erycinae are spread to the North America, North Africa and Asia. Due to their attractive appearance and small size are interesting business article. Every species of this subfamily is subject of CITES agreement. This work contains collected data from imports of subfamily Erycinae to the Czech Republic and EU and contains data from trade websites and Finally comprehensive key was made for all 15 species of subfamily Erycinae which was verified by inexpert public and all deficits were corrected.
Key to boiinae snakes for The Czech Environmental Inspectorate.
Species of Boinae are of a great interest among breeders, wheter it?s due to their size, attractive colour patters or the way they hunt their prey. However, some species are endemic, threatened by the habitat loss or other causes and therefore they are subject to the CITES or they are placed on the IUCN Red List. In the last 20 years there have been numerous changes in the taxonomy of all families. New species were discovered, many were also lifted from the level of subspecies to the species level. This work focuses on 34 species of the subfamily Boinae, summarizes the hitherto published data and determination characters. It also contains data collected from web advertising sites iFauna and Terraristik, which is used to form images of the species traded in the Czech Reublic respectively neighboring Germany. Finaly the work includes a comprehensive key to all 34 snakes species complemented by illustrations.
Active contour models in medical image segmentation
Nagy, Ivan ; Szabó, Z.
Active contour models are very suitable to image segmentation. A contour is a set of point which has an energy function. This energy function comes from both internal and external sources. This paper includes internal and external energy definition and a Matlab implementation of active contours.

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