This thesis is focused on entropy sources and their evaluation. It includes a brief introduction to the information theory, description of entropy sources, their parameters and characteristics and methods of evaluation based on the NIST organisation standard SP 800-90B. The following part of the thesis is dedicated to the description of two created programs and evaluation and comparison of entropy sources. Additionally, the last part describes the usage of hash functions in association with entropy sources.

The analysis of HRV is an advanced and noninvasive method which is used to investigate the involuntary nervous system. It is also one of the important parameters of its proper function. Heart rate variability can also be analyzed by entropy, which studies the discrepancy of the RR intervals of the HRV signal and thus can be used to diagnose cardiac diseases

This master thesis deals with a generation of random numbers and Fortuna generator implementation in Java language. In the first part the theoretical familiarization to the issues is introduced. Various entropy sources like mouse movement, keyboard typing, microphone and web camera noise are described and analysed. The analysis focuses on randomness, usability and volume of gathered data. Also the Fortuna random number generator is described from the theoretical view. Object analysis and implementation details are described in the last chapter of the document.

This thesis solves possibility of using entropy for anomaly detection in data communication and especially for security attacks. The main advantage of using entropy is ability to identify unknown attacks because entropy detects changes in network traffic but not the content as existing methods. In this work was tested the suitability of different models entropy (Shannon, Renyi, Tsallis). Also been tested the effect of Renyi and Tsallis parameter on resulting entropy. From the resulting values, I found that all tested entropy achieve good result in the identification of anomalies in network traffic.

This paper is focused on generating random number via entropy generators. There are described sources of entropy on personal computer and described methods of detecting their entropy. There are also described basic operations used for construction and for concept solution this generator under NIST recommendation for personal computer and methods of their testing.

This dissertation thesis is dedicated to the heart rate variability and methods of its evaluation. It mainly focuses on nonlinear methods and especially on the Poincaré plot. First it deals with the principle and nature of the heart rate variability, then the ways of its representation, linear and also nonlinear methods of its analysis and physiological and pathophysiological influence on heart rate variability changes. In particular, there is emphasis on the metabolic syndrome. In the next section of the thesis there are compared and evaluated different ways of representation of the heart rate variability and further are tested selected methods of heart rate variability analysis on unique data from patients with the metabolic syndrome and healthy subjects provided by the Institute of Scientific Instruments, Academy of Sciences of Czech Republic. In particular, they are used the Poincaré plot and its parameters SD1 and SD2, commonly used time domain and frequency domain parameters, parameters evaluating signal entropy and the Lyapunov exponent. SD1 and SD2 combining the advantages of time and frequency domain methods of heart rate variability analysis distinguish successfully between patients with the metabolic syndrome and healthy subjects.

In this study, entropy in reorganisation is investigated due to the individual co-workers being an ever more important component of his or her contemporary organisation, where change and reorganisation is undertaken continuously. Earlier research regarding entropy in reorganisation have mainly been done from a financial perspective; diversification. Hence there is room for additional research, with the individual in focus, rather than the company portfolio. This study aims at enlighten the entropy prevalent trough lost information in reorganisation. With qualitative method and phenomenological onset, five respondents in different positions from Swedish and global organisations, have been interviewed about their and their co-workers experience of reorganisation. The study shows the discrepancy between, the by the management defined finish­, vs. when the co-workers sense that a reorganisation de factois finished. The study also shows how individual motivation, psychosocial health and work effort can be affected through loss of the three types of information; descriptive, operative and narrative. / I denna studien undersöks entropi i omorganisering mot bakgrund av att den individuella med­arbet­aren utgör en allt viktigare del av sin samtida organisation, där förändring och omorgani­sering sker kontinuerligt. Tidigare forskning kring entropi i omorganisering har främst gjorts ur ett finansiellt perspektiv, s.k. diversifieringsperpektiv. Således finns utrymme för ytterligare forskning med individen i fokus snarare än företagsportföljen. Studien syftar till att belysa den entropi som genom för­lorad informa­tion gör sig påtaglig i samband med omorganisering. Med kvalitativ metod och feno­men­ologisk ansats har fem respondenter, i olika positioner från svenska och globala organisa­tioner, inter­vjuats om sin och sina kollegors upplevelse av omorganisering. Studien påvisar en diskre­pansen mellan det av ledningen definierade färdigställandet respektive när medarbet­arna upplever att en omorganisa­tion de factoär klar. Här påvisas även hur individens motivation, psyko­­sociala hälsa och arbets­insats kan påverkas genom förlust av de identifierade tre typerna av information deskrip­tiv, operativ och narrativ.

Le but principal de cette thèse est de présenter des conditions suffisantes pour garantir l'existence de subdivisions dans les graphes dirigés. Bien que ce genre de questions soit assez bien maitrisé dans le cas des graphes non orientés, très peu de résultats sont connus sur le sujet des graphes dirigés. La conjecture la plus célèbre du domaine est sans doute celle attribuée à Mader en 1985 qui dit qu'il existe une fonction f tel que tout graphe dirigé de degré sortant minimal supérieur à f(k) contient le tournoi transitif sur k sommets comme subdivision. Cette question est toujours ouverte pour k=5. Cette thèse présente quelques résultats intermédiaires tendant vers cette conjecture. Il y est d'abords question de montrer l'existence de subdivisions de graphes dirigés autre que les tournois, en particulier les arborescences entrantes. Il y a aussi la preuve que les graphes dirigés de grand degré sortant contiennent des immersions de grand tournois transitifs, question qui avait été posée en 2011 par DeVos et al. En regardant un autre paramètre, on montre aussi qu'un grand nombre chromatique permet de forcer des subdivisions de certains cycles orientés, ainsi que d'autre structures, pour des graphes dirigés fortement connexes. Cette thèse présente également la preuve de la conjecture de Erd\H{o}s-Sands-Sauer-Woodrow qui dit que les tournois dont les arcs peuvent être partitionnés en k graphes dirigés transitifs peuvent être dominé par un ensemble de sommet dont la taille dépend uniquement de k. Pour finir, cette thèse présente la preuve de deux résultats, un sur l'orientation des hypergraphes et l'autre sur la coloration AVD,utilisant la technique de compression d'entropie. / The main purpose of the thesis was to exhibit sufficient conditions on digraphs to find subdivisions of complex structures. While this type of question is pretty well understood in the case of (undirected) graphs, few things are known for the case of directed graphs (also called digraphs). The most notorious conjecture is probably the one due to Mader in 1985. He asked if there exists a function f such that every digraph with minimum outdegree at least f(k) contains a subdivision of the transitive tournament on k vertices. The conjecture is still wide open as even the existence of f(5) remains open. This thesis presents some weakening of this conjecture. Among other results, we prove that digraphs with large minimum outdegree contain large in-arborescences. We also prove that digraphs with large minimum outdegree contain large transitive tournaments as immersions, which was conjectured by DeVos et al. in 2011. Changing the parameter, we also prove that large chromatic number can force subdivision of cycles and other structures in strongly connected digraphs. This thesis also presents the proof of the Erd\H{o}s-Sands-Sauer-Woodrow conjecture that states that the domination number of tournaments whose arc set can be partitioned into k transitive digraphs only depends on k. The conjecture, asked in 1982, was still open for k=3. Finally this thesis presents proofs for two results, one about orientation of hypergraphs and the other about AVD colouring using the recently developed probabilistic technique of entropy compression.

A multivariate generalization of mutual information, multi-information, is defined in the thermodynamic limit. The definition takes phase coexistence into account by taking the infimum over the translation-invariant Gibbs measures of an interaction potential. It is shown that this infimum is attained in a pure state. An explicit formula can be found for the Ising square lattice, where the quantity is proved to be maximized at the phase-transition point. By this, phase coexis-tence is linked to high model complexity in a rigorous way.

Art, process, and materials offer me an escape from the sometimes-crushing realities of my personal struggle with chronic mental illness. Escape is often my primary motivator for making art. However, personal meaning and understanding sometimes come while I'm working in the studio. Sometimes the meanings of the work only become clear years later. Personal experience and experimenting with materials and processes have led me to an appreciation and awareness of entropy--the second law of thermodynamics. My sculptures use spontaneity, abstraction, and process to dialogue with entropy.