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Cataclysmic variable stars
Kára, Jan ; Wolf, Marek (advisor) ; Szkody, Paula (referee) ; Mennickent, Ronald (referee)
Cataclysmic variable stars are semi-detached binary systems consisting of a white dwarf primary star and a late-type secondary star. The secondary star in these systems is over- filling its Roche lobe, which enables a mass transfer to occur between the components. The transferred matter forms an accretion disc around the white dwarf when no strong magnetic field is present. This thesis presents a study of four different cataclysmic variables using light-curve modelling of eclipses and Doppler tomography as the main methods of analysis. The systems selected for the study belong to different subtypes of cataclysmic variables, but all of them exhibit mass-transfer rates which put them close to a border between systems with stable and unstable accretion disc. Although each of the systems studied represents a different type of cataclysmic variables, the presented study shows that they share some common characteristics and that the study of such systems is important for understanding the evolution of cataclysmic variables and the physical processes connected with them.
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Cataclysmic variable stars
Kára, Jan ; Wolf, Marek (advisor)
Cataclysmic variable stars are semi-detached binary systems consisting of a white dwarf primary star and a late-type secondary star. The secondary star in these systems is over- filling its Roche lobe, which enables a mass transfer to occur between the components. The transferred matter forms an accretion disc around the white dwarf when no strong magnetic field is present. This thesis presents a study of four different cataclysmic variables using light-curve modelling of eclipses and Doppler tomography as the main methods of analysis. The systems selected for the study belong to different subtypes of cataclysmic variables, but all of them exhibit mass-transfer rates which put them close to a border between systems with stable and unstable accretion disc. Although each of the systems studied represents a different type of cataclysmic variables, the presented study shows that they share some common characteristics and that the study of such systems is important for understanding the evolution of cataclysmic variables and the physical processes connected with them.
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Clustering techniques for ads monitoring
Dzetkulič, Tomáš ; Kolman, Petr (advisor) ; Kára, Jan (referee)
This thesis surveys possibilities of clustering of advertisements, especially those for real estates. It defines clustering itself, its usage and typical requirements for clustering algorithms. We provide list of existing clustering methods and approaches, their properties and suitable application. We consider possiblity of using them for clustering of milions of advertisements and based on that, we choose most suitable algorithm for this problem. We describe how to interpret advertisement as the point in multi dimensional vector space and this algorithm for clustering such points using locality of families of hash functions. We describe algorithm in detail, listing all of its parameters, estimating its complexity and expected results. In the following chapters we describe implementation of the algorithm in Java. We also describe database structure of underlying relational database. In the next chapter we present results of the algorithm based on real data and we compare the results with the expected results of the algorithm. In the end, we discuss possibilities for future extension of the clustering method.
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The Risk Factors of Lung Cancer. Lug Cancer in Women
Čermáková, Anna ; Kára, Jan (advisor)
Theme of her thesis dealing with lung cancer women I have chosen not only because it belongs to the Czech Republic countries with high incidence and mortality for lung cancer, but also personal interest in this issue. Lung cancer is by far the most common malignant us cancer in men. For women, the incidence of this tumor is about four times lower than in men, but worrying is the fact that the curve for women incidence has increased steadily. Although a direct link has been demonstrated a number of risk factors, especially smoking, another question arises about the influence of other substances, especially in women, where the representation ofdifferent histological different types of lung tumors. Therefore, there are hypotheses whether women have no share in the development of lung cancer, especially adenocarcinoma, hormonal influences. That was the impetus for writing this work, which I tried to find association between the occurrence ofadenocarcinoma in women and hormonal contraceptives, hormone replacement therapy and length of time between menarche and menopause.
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Online Contest Programing server
Ďurik, Peter ; Černý, Jakub (advisor) ; Kára, Jan (referee)
The aim of this project is to design and to create an application for evaluating and administration of programming competitions. Application should be designed to be used in programming contests and for evaluating homework from lessons of programming as well. After look into existing solutions it is needed to design system that will contain a comfortable user interface for administration of application and interface for contestants. The system should evaluate solutions enough rightly and evaluating should be resistant against fake solutions.
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Flare stars
Kára, Jan ; Wolf, Marek (advisor) ; Švanda, Michal (referee)
The works deals with the study of the flare stars, which is a group of stars for which sudden brightening can be observed. The work focuses on a star GJ 3236, which is a low-mass eclipsing binary and on which numerous flares have been observed. For the analysis of this system spectroscopic and photometric data were used, which were obtained at various observatories. Parameters of the binary system have been determined by analysing spectroscopic and photometric data with the program PHOEBE. A total of 241 flares have been detected in the photometric data and for 190 flares, which light curves were not affected by eclipses, released energies were estimated. The set of flares was used for the study of stellar activity of the binary. The energy distribution of observed flares is similar to the flares observed on other flare stars and also on the Sun. This suggests, that the flare mechanism is the same for these stars.
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The media stereotyping of Czechs in the case of the National library
Kára, Jan ; Hronová, Tereza (advisor) ; Dvořák, Tomáš (referee)
My bachelor thesis "Media stereotyping of the Czechs in the case of the National Library" explores stereotypes of Czech national identity / Czechness in the contents of Czech printed media. The media chosen are the weekly magazines Respekt and Reflex . The examined period is from 2nd March 2007 to 2nd June 2007, which means three months after the announcement of the winner of international architectural competition for the new National Library building at Letna. Qualitative content analysis method is used to define stereotypes based on the material examined. It is conceived as an interpretation of a media text. The analysis studies and interprets references found to the Czechs / the nation /the society. It examines what identity and character the chosen titles assign to the Czech nation. After that, the thesis examines the similarities and differences between the two titles. The research part is preceded by a theoretical part and a methodological part. The theoretical part explains the concepts of national identity and national character and stereotyping and describes the affair of the National Library from the point of view describing the historical problems of its premises, the course of the architectural competition and the final form of the design by Jan Kaplický. The methodological part describes the...
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Flare stars
Kára, Jan ; Wolf, Marek (advisor) ; Švanda, Michal (referee)
The works deals with the study of the flare stars, which is a group of stars for which sudden brightening can be observed. The work focuses on a star GJ 3236, which is a low-mass eclipsing binary and on which numerous flares have been observed. For the analysis of this system spectroscopic and photometric data were used, which were obtained at various observatories. Parameters of the binary system have been determined by analysing spectroscopic and photometric data with the program PHOEBE. A total of 241 flares have been detected in the photometric data and for 190 flares, which light curves were not affected by eclipses, released energies were estimated. The set of flares was used for the study of stellar activity of the binary. The energy distribution of observed flares is similar to the flares observed on other flare stars and also on the Sun. This suggests, that the flare mechanism is the same for these stars.
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CCD photometry of variable objects in nearby galaxies
Kára, Jan ; Wolf, Marek (advisor) ; Zasche, Petr (referee)
The work concerns the study of variable stars in the Small Magellanic Cloud with use of time series of photometric images of star field NGC 330, which were obtained by the 1,54-m Danish telescope at the observatory La Silla in Chile during years 2012 - 2016. The aim of this work is to produce light curves of variable stars a to determine their period of variability assuming the variations are periodical. For some stars data from earlier published papers were used, which led to the coverage of longer period of time and therefore to the improvement of the accuracy of the period determination. The work lists summary of some of the types of variable stars and of mechanisms causing their variability. The work focus mainly on cepheids, which can be used to determine distances in the Universe thanks to the relation between their absolute magnitude and period of pulsation.
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