以往重複事件分析法主要用於醫學與科學領域，近來學者逐漸將其應用至經濟、商學、社會科學等領域，本篇論文採用重複事件分析法，分析S&P 500公司股票回購的行為，回顧過去學者對股票回購之研究，我們檢視公司執行股票回購的三大原因，根據我們的實證結果發現公司可能會以股票回購作為影響公司資本結構的工具，再者亦可能用以減低剩餘資金，然而，本篇論文的實證結果較不支持訊號發射理論。 / In this study, we apply Cox proportional hazard model in recurrent event analysis, which usually used in medical and science studies, to analyze the determinants of the stock repurchase events of S&P 500 companies. We investigate three main incentives that companies conduct stock repurchase. The empirical results show that companies employ repurchase as a technique to alter capital structure. In addition, companies conduct stock repurchase to distribute excess capital. In contrast, there are little evidences to support signaling undervaluation.

In South Africa there is a need within the milling industry for controlling food safety especially due to customer's demands and government's regulations. The best way to ensure food safety is with the implementation of a HACCP based food safety system. Therefore, the principal aim of this study was to develop a generic HACCP model for the flour milling industry. Afterwards this generic model can then be adapted for each specific mill and its needs.

Analysis of functional connectivity of simultaneously recorded multiple spike trains is one of the major issues in the neuroscience. The progress of the statistical methods to the analysis of functional connectivity of multiple spike trains is relatively slow. In this thesis two statistical techniques are presented to the analysis of functional connectivity of multiple spike trains. The first method is known as the modified correlation grid (MCG). This method is based on the calculation of cross-correlation function of all possible pair-wise spike trains. The second technique is known as the Cox method. This method is based on the modulated renewal process (MRP). The original paper on the application of the Cox method (Borisyuk et al., 1985) to neuroscience data was used to analyse only pairs and triplets of spike trains. This method is further developed in this thesis to support simultaneously recorded of any possible set of multiple spike trains. A probabilistic model is developed to test the Cox method. This probabilistic model is based on the MRP. Due to the common probabilistic basis of the probabilistic model and the Cox method, the probabilistic model is a convenient technique to test the Cox method. A new technique based on a pair-wise analysis of Cox method known as the Cox metric is presented to find the groups of coupled spike trains. Another new technique known as motif analysis is introduced which is useful in identifying interconnections among the spike trains. This technique is based on the triplet-wise analysis of the Cox method. All these methods are applied to several sets of spike trains generated by the Enhanced Leaky and Integrate Fire (ELIF) model. The results suggest that these methods are successful for analysing functional connectivity of simultaneously recorded multiple spike trains. These methods are also applied to an experimental data recorded from cat’s visual cortex. The connection matrix derived from the experimental data by the Cox method is further applied to the graph theoretical methods.

Background: The aim of this study was to investigate the use and management of hazardous chemical substances (HCS) at a chemistry department in a selected Higher Education Institution in Gauteng province. Method: A quantitative, baseline descriptive study was conducted using a structured survey checklist. The population consisted of the chemistry department. Other than purposive observation by the researcher, employees present during data collection were approached for further clarifying comment to survey questions. Results: It emerged that physical-, health- and environmental hazard classes of HCS were present; and that hazard types included flammable liquids, HCS with acute toxicity and carcinogenicity. Selected exposure control measures were lacking which created risks of fire and explosion. Conclusion: The study reflected the use and management of HCS, the actual and potential human exposure and the exposure control measures. Varying degrees of compliance were found, which, if attended to, should mitigate risks to health and safety. / Health Studies

Evidence suggests that child behavior, parent mental health, parent supervision, and home environment conditions impact a child’s risk of injury. Vulnerable families are at greater risk for the occurrence of child behavior problems, poor health, decreased supervision, and hazardous home conditions. Consistent with a model that proposes that parent, child, and environment factors interact within the lens of sociocultural factors to predict injury, the current study aimed to test a statistical model with maternal physical health and child externalizing behaviors as predictors of child injury, and home hazards and supervision as mediators of these relations. Analyses were conducted using a nationally representative sample of 3,288 vulnerable mother-child dyads. Results showed significant relations between parent physical health and child injury, and child aggression and child injury, though home hazards and supervision did not mediate either of these relations. Further research should continue to examine the mechanisms of action in the parent health- child injury relation so that injury prevention interventions can be developed.

Title: Random Processes in Reliability Analysis Author: Kamil Chovanec Department: Department of Probability and Mathematical Statistics Supervisor: Doc. Petr Volf, CSc. Supervisor's e-mail address: volf@utia.cas.cz Abstract: The thesis is aimed at the reliability analysis with special em- phasis at the Aalen additive model. The result of hypothesis testing in the reliability analysis is often a process that converges to a Gaussian martingale under the null hypothesis. We can estimate the variance of the martingale using a uniformly consistent estimator. The result of this estimation is a new hypothesis about the process resulting from the original hypothesis. There are several ways to test for this hypothesis. The thesis presents some of these tests and compares their power for various models and sample sizes using Monte Carlo simulations. In a special case we derive a point that maximizes the asymptotic power of two of the tests. Keywords: Martingale, Aalen's additive model, hazard function 1

This thesis deals with online gambling and specifics of the legislation, which is in the Czech Republic regulated mainly by the Act No. 202/1990, the Lottery Act. After short introduction of the field, there is provided analysis of the latest amendment to the Lottery Act No. 300/2011 and its impact on the poker industry, particularly the online poker industry. Emphasis is placed on the conditions laid down for obtaining a license to operate in lotteries and other similar games, the tax aspects of poker for both operators and players and suitability of inclusion poker under the regime of the Lottery Act. The issue of cross-border gambling is in the European Union closely studied and in the coming years there is to be expected extensive harmonization, which will be based on the fundamental principles of free movement of goods, services, people and capital. In connection with the forthcoming harmonization, the author addresses the issue of incompatibility of the Czech Lottery Act with European law and draws the same conclusion regarding the draft Act on the Operation of gambling, which was originally approved with effect from 1st January 2013. After a brief excursion into the regulation of internet gambling in France and Greece, the author compares the local regulatory tools and instruments with those...

Master of Regional and Community Planning / Department of Landscape Architecture/Regional and Community Planning / Howard Hahn / Since 2005, local jurisdictions have been required to prepare hazard mitigation plans to maintain eligibility for a number of disaster-related federal grant programs. All types of communities prepare these plans, high-risk coastal communities and low-risk Great Plains communities alike. Research, both current and historic, has found hazard mitigation plans have a number of weaknesses, ranging from weak fact bases to weak mitigation actions. The purpose of this study is to explore how this research can be used to prioritize enhancements to hazard mitigation plans in growing rural counties, referred to as urbanizing rural communities, which have limited staff and resources. Specifically, Pottawatomie County, Kansas was the focus of this study. In order to prioritize enhancements, the current issues and challenges related to hazard mitigation were explored through interviews and assessing the quality of hazard mitigation plan documents. Based on the outcome of this initial analysis, plans of comparable communities were explored to identify a range of policies and methods that could be used by Pottawatomie County. Finally, these policies and methods will be prioritized based on the level of enhancement and resource requirements. This study found two possible directions for plan improvements: a combined response/mitigation planning process for a single county and strategies for participation within a regional planning context. The interviews with Pottawatomie County staff reveal an opportunity to combine phases of the emergency management cycle to boost interest and participation. The interviews also revealed a statewide shift to a regional planning process. This shift, while presenting new opportunities, will require Pottawatomie County staff to be more active and engaged to ensure the resulting regional plan will be beneficial to the county.

Master of Science / Department of Grain Science and Industry / Cassandra K. Jones / Animal food manufacturing facilities need to evaluate biological hazards within their facility due to their severity and probability to cause illness or injury in humans or animals. Control of biological hazards, including Salmonella and Porcine Epidemic Diarrhea Virus (PEDV), in animal food manufacturing facilities may require a preventative control to mitigate the risk of the hazard. Thermal processing is an effective point-in-time control, but does not prevent cross-contamination during drying, cooling, and packaging/load-out of animal food. Therefore, it may be appropriate to sanitize surfaces to prevent cross-contamination of animal food during manufacturing. The objective of the first experiment was to evaluate surface decontamination strategies for Porcine Epidemic Diarrhea Virus (PEDV) using chemical disinfectants to reduce viral RNA on various manufacturing surfaces. Concentrated liquid formaldehyde and sodium hypochlorite reduced the quantity of viral PEDV RNA on all tested surfaces. Rubber belting from a bucket elevator retained the most PEDV RNA, while the polyethylene tote bag retained the least. In the second experiment, surface decontamination was evaluated for Salmonella Typhimurium using liquid and dry chemical sanitizers on various manufacturing surfaces. Surfaces treated with concentrated commercial formaldehyde had no detectable Salmonella after treatment, and surfaces treated with medium chain fatty acids (MCFA) had at least a 4-log reduction compared to the control. The dry commercial acidulant, sodium bisulfate, was the most effective dry sanitizer tested, but had limited efficacy depending on surface type. Experiment 3 further tested the application of two chemical sanitizers against Salmonella Enteritidis on residual surface and feed contamination in pilot-scale mixers. Manufacturing sequence, but not treatment impacted feed and surface contamination of Salmonella Enteritidis. Specifically, there was Salmonella-positive residue in the batch of feed manufactured immediately after the positive control batch. However, no Salmonella residue was detected in batches of feed treated with either concentrated commercial essential oil blend or rice hulls treated with 10% MCFA. Low levels of Salmonella residues were observed from feed and surfaces manufactured after Sequence 1, but no residues were observed by Sequence 2. This data suggests that sequencing of feed during manufacturing can reduce Salmonella-positive contamination within animal food and on manufacturing surfaces, particularly after the second batch or with the use of chemical treatments. In summary, liquid sanitizers have been shown to be effective at reducing Salmonella spp. and PEDV contamination on a variety of animal food manufacturing surfaces, but application and practicality may be limited.

Doctor of Philosophy / Department of Computing and Information Sciences / John M. Hatcliff / Medical devices have traditionally been designed, built, and certified for use as monolithic units. A new vision of "Medical Application Platforms" (MAPs) is emerging that would enable compositional medical systems to be instantiated at the point of care from a collection of trusted components. This work details efforts to create a development environment for applications that run on these MAPs. The first contribution of this effort is a language and code generator that can be used to model and implement MAP applications. The language is a subset of the Architecture, Analysis and Design Language (AADL) that has been tailored to the platform-based environment of MAPs. Accompanying the language is software tooling that provides automated code generation targeting an existing MAP implementation. The second contribution is a new hazard analysis process called the Systematic Analysis of Faults and Errors (SAFE). SAFE is a modified version of the previously-existing System Theoretic Process Analysis (STPA), that has been made more rigorous, partially compositional, and easier. SAFE is not a replacement for STPA, however, rather it more effectively analyzes the hardware- and software-based elements of a full safety-critical system. SAFE has both manual and tool-assisted formats; the latter consists of AADL annotations that are designed to be used with the language subset from the first contribution. An automated report generator has also been implemented to accelerate the hazard analysis process. Third, this work examines how, independent of its place in the system hierarchy or the precise configuration of its environment, a component may contribute to the safety (or lack thereof) of an entire system. Based on this, we propose a reference model which generalizes notions of harm and the role of components in their environment so that they can be applied to components either in isolation or as part of a complete system. Connections between these formalisms and existing approaches for system composition and fault propagation are also established. This dissertation presents these contributions along with a review of relevant literature, evaluation of the SAFE process, and concludes with discussion of potential future work.