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Stellar occultations by asteroids
Černý, Dominik ; Ďurech, Josef (advisor) ; Hanuš, Josef (referee)
The thesis deals with the processing of data from stellar occultation observations, which are available online. The main goal is to verify whether asteroid models from inversion techniques correspond with the observations or, if an asteroid has more models, to determine which one fits better. Data are processed using a~series of programs in Matlab studio that plot the projections of observations and models on the same plane. The comparison of models with occultations is then done based on generated graphs. This method also enables the computation of the diameter of asteroids, which is compared with previously obtained values. Overall, 516 occultations for 274 asteroids were processed. At least one model is suitable for 190 asteroids, 40 asteroids had no corresponding model and 44 have their occultations observed insufficiently. For most asteroids with a suitable model, the computed diameter corresponds to previous observations in the IR spectrum. However, in some cases, the observations of occultations were sufficient for model verification but insufficient for confident diameter computation.
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Physical model of asteroid (130) Elektra based on adaptive optics images obtained by the VLT/SPHERE instrument
Fuksa, Matyáš ; Hanuš, Josef (advisor) ; Scheirich, Petr (referee)
Using the ADAM software package, the shape model of the asteroid (130) Elektra was reconstructed. The model is based on 60 lightcurves from the DAMIT database, 46 AO images obtained by the NIRC2 and SPHERE in- struments and two occultations. The best-fit model assigns Elektra the vol- ume of (4.3 ± 0.1) × 106 km3 . After that, using the Xitau program, the orbital model of the two moons S/2014 1 and S/2003 was constructed. It is based on astrometry of the moons reduced from the 2014 and 2019 SPHERE images of Elektra. The model is a dipole non-Keplerian one, which resulted in an adjustment to the periods of the two moons to P1 = (1.2185 ± 0.0004) d & P2 = (5.3015 ± 0.0001) d. The main result is the more precise mass of Elektra at (6.59 ± 0.08) × 1018 kg, which revises the bulk density to ̄ρ = (1.533 ± 0.066) g cm−3 .
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Trends and Significance of the Migration of Foreign Students mainly from non-EU Countries in the Czech Republic and Europe.
Zábranská, Agáta ; Šatava, Leoš (advisor) ; Hanuš, Josef (referee)
in English The diploma Thesis "Trends and Significance of the Migration of Foreign Students mainly from non-EU Countries in the Czech Republic and Europe." discusses the phenomenon of migration for study purposes from non-EU countries (mainly Russia, Ukraine and Bosnia and Herzegovina) in the Czech Republic. The percentage of immigrants coming to study in Czech Republic has been growing and it constitutes an important tool for a positive development of the international cooperation. The aim of this work is to describe and analyze, based on the questionnaire method and specialized texts, the reasons for the choice of this type of migration, underling the administrative, economic and social issues that might be involved. Furthermore the objective is to evaluate the participation of qualified foreigners in the Czech labor market as well as to determine, presenting specific cases collected by a qualitative method, the human, cultural and social added value that they might gain by being awarded with an European diploma. Finally, in order to study the phenomenon from an anthropological perspective, the study attempts a comparative analysis of the academic mobility as a mean of temporary circular migration, enabling an optmized prediction of the current trends and tendencies while considering the issues of...
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Utilization of Cone Beam CT for Reconstruction of Dose Distribution Delivered in Image-guided Radiotherapy of Prostate Carcinoma - Bony Landmark Setup Compared to Fiducial Markers Setup
Paluska, Petr ; Hanuš, Josef (advisor) ; Doležel, Martin (referee) ; Podzimek, František (referee)
The purpose of my doctoral thesis was to compare two different styles of prostate image- guided radiotherapy: bony landmark (BL) setup vs. fiducial markers (FM) setup. Twenty-nine prostate patients were treated with daily BL setup and 30 patients with daily FM setup. Delivered dose distribution was reconstructed on cone-beam CT (CBCT) acquired once a week immediately after the alignment. Target dose coverage was evaluated by the proportion of the CTV encompassed by the 95% isodose. Original plans employed 1 cm safety margin. Alternative plans assuming smaller 7 mm margin between CTV and PTV were evaluated in the same way. Rectal and bladder volumes were compared with initial ones. While the margin reduction in case of BL setup makes the prostate coverage significantly worse (p = 0.0003, McNemar's test), in case of FM setup with the reduced 7 mm margin, the prostate coverage is even better compared to BL setup with 10 mm margin (p = 0.049, Fisher's exact test). Moreover, partial volumes of organs at risk irradiated with a specific dose can be significantly lowered (p < 0.0001, unpaired t-test). Reducing of safety margin is not acceptable in case of BL setup, while the margin can be lowered from 10 mm to 7 mm in case of FM setup.
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Asteroid Models from Sparse Photometry
Hanuš, Josef ; Ďurech, Josef (advisor) ; Harris, Alan (referee) ; Tanga, Paolo (referee)
We investigate the photometric accuracy of the sparse data from astrometric surveys available on AstDyS. We use data from seven surveys with the best accu- racy in combination with relative lightcurves in the lightcurve inversion method to derive ∼300 new asteroid physical models (i.e., convex shapes and rotational states). We introduce several reliability tests that we use on all new asteroid mod- els. We investigate rotational properties of our MBAs sample (∼450 models here or previously derived by the lightcurve inversion), especially the spin vector dis- tribution. It is clear that smaller asteroids (D 30 km) have strongly anisotropic spin vector distribution even when we remove the bias of the lightcurve inversion, the poles are clustered towards ecliptic poles. We explain this anisotropy as a re- sult of non-gravitational torques (YORP effect) acting on these objects, because without accounting these torques, we were not able to create such anisotropic dis- tribution by our model of the spin evolution. We also estimate sizes for 41 and 10 asteroids by scaling their models to fit the adaptive optics profiles and occultation observations, respectively.
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Dynamical processes in Jupiter's and Saturn's ring systems
Řehák, Matyáš ; Brož, Miroslav (advisor) ; Hanuš, Josef (referee)
The main subject of this thesis is a review of dynamical processes acting in Jupiter's and Saturn's rings. The thesis is divided into three chapters. Observed orbital and physical characteristics of the rings are described in the first one. In Chapter 2, we discuss physical processes forming the rings. Tidal disruptions, mutual collisions of ring particles, meteoroid bombardment and ballistic transport are among them. Various electromagnetic effects are analyzed too - e.g. the Poynting-Robertson effect, the Lorentz resonaces, plasma drag and radiation pressure. Yet another types of phenomena are resonant gravitational influence of satellites, shepherding moons and also collective dynamics of ring particles which results in formation of spiral waves. Finally, there is a review of theories concerning the origin of Saturn's rings in Chapter 3. We can distinguish three types of models - a disruption of a moon, a disruption of an external body and a formation from protolunar matter. At present, a tidal disruption of large differentiated moon seems to be the most probable theory.
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Asteroid Models from Sparse Photometry
Hanuš, Josef
We investigate the photometric accuracy of the sparse data from astrometric surveys available on AstDyS. We use data from seven surveys with the best accu- racy in combination with relative lightcurves in the lightcurve inversion method to derive ∼300 new asteroid physical models (i.e., convex shapes and rotational states). We introduce several reliability tests that we use on all new asteroid mod- els. We investigate rotational properties of our MBAs sample (∼450 models here or previously derived by the lightcurve inversion), especially the spin vector dis- tribution. It is clear that smaller asteroids (D 30 km) have strongly anisotropic spin vector distribution even when we remove the bias of the lightcurve inversion, the poles are clustered towards ecliptic poles. We explain this anisotropy as a re- sult of non-gravitational torques (YORP effect) acting on these objects, because without accounting these torques, we were not able to create such anisotropic dis- tribution by our model of the spin evolution. We also estimate sizes for 41 and 10 asteroids by scaling their models to fit the adaptive optics profiles and occultation observations, respectively.
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Media portrayal of Andrej Babis before the elections to the Chamber of Deputies of Parliament of the Czech republic in 2017
Hanus, Josef ; Hanzal, Jaromír (advisor) ; Lütke Notarp, Ulrike (referee)
The Master's thesis focuses on the creation of the media image of one of the most distinctive and controversial current Czech politicians, Andrej Babiš, in the period prior to the 2017 general elections in the Czech Republic. The media image building process is viewed through the lens of agenda-setting theory in major daily newspapers and the Facebook page of ANO, Mr. Babiš's party. The aim of the thesis is to use mixed research to describe the creation of Mr. Babiš's media persona and to determine whether media discourse was influenced by intermedia agenda-setting process. In the quantitative analysis of this research, the volume and content of topics established by Mr. Babiš's media activity will be explored. The topic with the greatest relevancy and frequency will be used to determine the framework of the creation of Mr. Babiš's media image, discuss to what extent Mr. Babiš managed to control the outcome, and what role was played by the intermedia agenda-setting process. Keywords Andrej Babis, agenda-setting, daily newspapers, Facebook, media image building
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