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Chaos in motion around black holes
Suková, Petra ; Semerák, Oldřich (advisor) ; Šubr, Ladislav (referee)
The geodesic motion around Kerr black holes is regular, but this may change when an additional source is present, even if the space-time symmetry were not lowered. In this thesis we study the eect of a simple (static and axially symmetric) additional source on geodesic dynamics in the eld of a Schwarzschild black hole. In the static case the complete space-time can be described by an exact solution of Einstein equations thanks to a relatively simple superposition of the central-black-hole and the external-source metrics. Following the astrophysical motivation, we will specically consider, as the external source, the thin ring (linear source) of the Bach-Weyl type and innite thin discs (planar sources) of several types (inverted counter-rotating discs of Morgan and Morgan and the discs with power-law radial shape of density). The results may be relevant e.g. for a long-term behaviour of discrete sources (stars) in the eld of a very massive black hole in a galactic nucleus, surrounded by an accretion disc and/or by a massive toroid.
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Homoclinic Chaos in Black-hole Fields
Hájková, Tereza-Marie ; Semerák, Oldřich (advisor) ; Suková, Petra (referee)
The existence of homoclinic orbits is an intrinsic feature of static black hole's space- time. The regularity of the geodesic motion around these black holes can therefore be quickly disrupted due to the small changes in the original space-time. The nature of the dynamics around a perturbed orbit depends on the manner of intersection of the surrounding stable and unstable manifolds. If they intersect transversally, the homoclinic orbit splits into chaotic layers. In this thesis, the mathematical formulation of chaotic dynamical systems and main properties of the geodesic motion in circular space-times are discussed. Thereupon, the space-time around a static black hole is reproduced by classical approximations by using Paczyński-Wiita and logarithmic pseudo-Newtonian potentials. By means of the effective potential method, the homoclinic orbits are found for these potentials. In addition, the analysis of the general circular space-time is done and the equations of geodesic motion in axially symmetric space-times are examined. Finally, the motion in a Schwarzschild space-time with a static axially symmetric external source is inspected. 1
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Chaotic Motion around Black Holes
Suková, Petra
As a non-linear theory of space-time, general relativity deals with interesting dynamical systems which can be expected more prone to chaos than their Newtonian counter-parts. In this thesis, we study the dynamics of time- like geodesics in the static and axisymmetric field of a Schwarzschild black hole surrounded, in a concentric way, by a massive thin disc or ring. We reveal the rise (and/or decline) of geodesic chaos in dependence on parameters of the sys- tem (the disc/ring mass and position and the test-particle energy and angular momentum), (i) on Poincaré sections, (ii) on time series of position and their power spectra, (iii) by applying two simple yet powerful recurrence methods, and (iv) by computing Lyapunov exponents and two other related quantifiers of or- bital divergence. We mainly focus on "sticky" orbits whose different parts show different degrees of chaoticity and which offer the best possibility to test and compare different methods. We also add a treatment of classical but dissipative system, namely the evolution of a class of mechanical oscillators described by non-standard constitutive relations.
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Missing bright red giants in the Galactic center: A fingerprint of its once active state?
Zajaček, Michal ; Araudo, Anabella ; Karas, Vladimír ; Czerny, B. ; Eckart, A. ; Suková, Petra ; Štolc, Marcel ; Witzany, V.
We propose a novel scenario for the bright red-giant depletion based onthe collisions between red giants and the nuclear jet, which was likely active in the Galactic center a few million years ago and could have led to the formation of the large-scaleγ-ray Fermi bubbles. The process of the jet-induced ablation of red giants appears to be most efficient within∼0.04 pc(S-cluster), while at larger distances it was complemented by star–accretion disc collisions and at smaller scales, tidal stripping operated. These three mechanisms likely operated simultaneously and createdan apparent core of late-type stars within∼0.5 pc.
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Perturbing the accretion flow onto a supermassive black hole by a passing star
Suková, Petra ; Zajaček, M. ; Witzany, V. ; Karas, Vladimír
The close neighbourhood of a supermassive black hole contains not only accreting gas and dust, but also stellar-sized objects like stars, stellar-mass black holes, neutron stars, and dust-enshrouded objects that altogether form a dense nuclear star-cluster.These objects interact with the accreting medium and they perturb the otherwise quasi-stationary configuration of the accretion flow. We investigate how the passages of a star can influence the black hole gaseous environment with GRMHD 2D and3D simulations. We focus on the changes in the accretion rate and the associated emergence of outflowing blobs of plasma.
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Zinc in food suplements
Sauchanka, Katsiaryna ; Suková, Petra (referee) ; Řezáčová, Veronika (advisor)
The aim of this bachelor thesis was to determine zinc in the dietary supplements by the voltammetric method. The general properties of zinc, its occurrence, toxicity and influence on human health are described in the first part. Next the methods, including a detailed description of the voltammetric analysis, are summarized. The experimental part is focused on the process of optimization of the conditions for zinc voltammetric analysis and the application of the optimised method on real samples.
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Removal of sulfonamide antibiotics using advanced oxidation processes
Fučík, Jan ; Suková, Petra (referee) ; Tulková, Tereza (advisor)
This thesis deals with a present problem of increasing concentrations of pharmaceuticals and other micropollutants in aquatic environment, because these micropollutants are not treated sufficiently in conventional wastewater treatment plants. It is necessary to develop new technological processes, that are able to treat these pollutants sufficiently. One of the options is that conventional methods would be complementary with advanced oxidation processes (AOP), which would work as a tertiary cleaning process on wastewater treatment plants. The actual knowledge, principle of the plasma discharge and principle of analytical methods is described in theoretical part of the thesis. In experimental part of the thesis, the plasma discharge is used for removal of sulfonamide antibiotics (sulfamethoxazole), as the representative of AOP. Samples were taken during the plasma treatment of the model solution of sulfamethoxazole. These samples were analysed by LC-ESI-MS as the appropriate analytical method. An efficiency of degradation of sulfamethoxazole in different solutions (neutral, acidic and alkaline) was evaluated in this bachelor thesis. A suitability of plasma application on degradation of sulfonamide antibiotics was reviewed by comparing with other AOP.
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Islamic Art
Šuková, Petra ; Čech, Viktor (advisor) ; Pfeiffer, Jan (referee)
TITLE: Islamic Art AUTHOR: Petra Šuková, Bc. DEPARTMENT: Department of Art Education SUPERVISOR: Viktor Čech, Mgr. ABSTRACT: Object of this thesis is an investigation of islamic art in a context of islamic doctrine with stress on elements which islam has in common with the jewish-christian culture, which was an inspiration for islam as well. The thesis compares certain trends and characters in these monoteistic religions with reference to mutual influences between western and eastern culture, which have been continuing even nowadays. The main object of interest is a human body and its carnality as well as the stereotypes we have about this topic. These stereotypes and prejudices towards islam and islamic art are also the issue for the practical and didactic part, when pupils will have an opportunity to try ornamental and nonfigurative way of depiction as well as a figurative and contemporary islamic art influenced by the western culture. KEYWORDS: islam, nonfigurative art, body, holy books, taboo, transcendence, mysticism, christianity, judaism, identity, stereotype, contemporary art, islamophobia
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Possibilities of elimination of sulfonamides from the aquatic ecosystem
Suková, Petra ; Mravcová, Ludmila (referee) ; Vávrová, Milada (advisor)
This diploma thesis focuses on the determination of sulfonamide antibiotics especially the possibility of elimination of these substances from the aquatic ecosystem. Nowadays, environmental contamination of the pharmaceuticals and their residues is a serious concern. Main sources of this contamination are wastewater treatment plants (WWTPs), where these compounds are not effectively removed by contemporary conventional technology. For this reason, new methods are being developed and tested that could eliminate the number of contaminants entering the environment in this way. There is a possibility to use the potential of the enzymatic system of wood-decay fungi, especially white rot fungi. Six representatives of sulfonamide antibiotics were selected and isolated from the aquatic matrix via solid phase extraction. The final identification and quantification method was high performance liquid chromatography with mass spectrometric detection. Monitoring of the concentration level of selected sulfonamide antibiotics at the inflow and effluent at the Brno-Modřice WWTP was carried out weekly. Moreover, the effectiveness of elimination of selected antibiotics from the aquatic ecosystem by the use of Trametes versicolor wood-decay fungi cultured on a suitable carrier was verified.
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