Title: Study of Cosmic-Ray Acceleration in Extragalactic Objects Author: Stanislav tefnik Department: Institute of Particle and Nuclear Physics Supervisor: RNDr. Dalibor Nosek, Dr. Abstract: This thesis deals with production processes of cosmic γ-rays in astro- physical objects and methods of their detection. Possible interactions leading to the emission of high energy γ-rays in the active galaxy Centaurus A are discussed in this context. Cherenkov Telescope Array is presented as a new experiment fo- cused on the detection of air showers initiated by cosmic γ-rays. Cherenkov light of air showers is studied in the simulations done by CORSIKA simulation tool. Method of data analysis within the framework of Cherenkov telescopes is descri- bed and performed on the dataset of the active galaxy PKS 2155-304. The results include statistical tests of γ-ray source presence and its time variability. Keywords: Cosmic rays, gamma rays, astroparticle physics, high energy astro- physics, acceleration, CTA experiment

A proposta deste trabalho é apresentar um modelo específico para gerenciamento de processos de transferência de tecnologias geradas no Centro Técnico Aeroespacial - CTA em decorrência dos projetos de P&D nele desenvolvidos. Inicialmente, foi feito um levantamento da base teórica sobre a qual se assentam os processos de transferência de tecnologia, definindo e abordando os conceitos mais importantes com relação ao assunto. Após essa etapa, foi realizada extensa pesquisa em publicações periódicas especializadas, nacionais e estrangeiras, em teses de pós-graduação e em anais de simpósios, em busca de outros modelos já apresentados para aplicação em outros setores e/ou países, que tenham obtido sucesso, para fins de comparação. Ao final, como somatória de toda a base teórica, com os subsídios fornecidos e adaptados dos modelos externos e com a experiência acumulada pelo CTA em tais processos ao longo dos últimos 30 anos, foi elaborado, de modo sistemático, um modelo que pretende atender ao escopo deste trabalho.

Advances in coronary Computed Tomography Angiography (CTA) have resulted in a boost in the use of this new technique in recent years, creating a challenge for radiologists due to the increasing number of exams and the large amount of data for each patient. The main goal of this study was to develop a computer tool to facilitate coronary CTA analysis by combining knowledge of medicine and image processing, and to evaluate the performance in clinical settings. Firstly, a competing fuzzy connectedness tree algorithm was developed to segment the coronary arteries and extract centerlines for each branch. The new algorithm, which is an extension of the “virtual contrast injection” (VC) method, preserves the low-density soft tissue around the artery, and thus reduces the possibility of introducing false positive stenoses during segmentation. Visually reasonable results were obtained in clinical cases. Secondly, this algorithm was implemented in open source software in which multiple visualization techniques were integrated into an intuitive user interface to facilitate user interaction and provide good over­views of the processing results. An automatic seeding method was introduced into the interactive segmentation workflow to eliminate the requirement of user initialization during post-processing. In 42 clinical cases, all main arteries and more than 85% of visible branches were identified, and testing the centerline extraction in a reference database gave results in good agreement with the gold standard. Thirdly, the diagnostic accuracy of coronary CTA using the segmented 3D data from the VC method was evaluated on 30 clinical coronary CTA datasets and compared with the conventional reading method and a different 3D reading method, region growing (RG), from a commercial software. As a reference method, catheter angiography was used. The percentage of evaluable arteries, accuracy and negative predictive value (NPV) for detecting stenosis were, respectively, 86%, 74% and 93% for the conventional method, 83%, 71% and 92% for VC, and 64%, 56% and 93% for RG. Accuracy was significantly lower for the RG method than for the other two methods (p<0.01), whereas there was no significant difference in accuracy between the VC method and the conventional method (p = 0.22). Furthermore, we developed a fast, level set-based algorithm for vessel segmentation, which is 10-20 times faster than the conventional methods without losing segmentation accuracy. It enables quantitative stenosis analysis at interactive speed. In conclusion, the presented software provides fast and automatic coron­ary artery segmentation and visualization. The NPV of using only segmented 3D data is as good as using conventional 2D viewing techniques, which suggests a potential of using them as an initial step, with access to 2D reviewing techniques for suspected lesions and cases with heavy calcification. Combining the 3D visualization of segmentation data with the clinical workflow could shorten reading time.

Commodity Trading Advisors (CTAs) have gained popularity due to their abilities to generate an absolute return strategy. Little is known about how CTAs work and what variables are important to tune in order to create a profitable strategy. Some investors use CTA-like strategies to leverage their portfolio and create positive returns in times when the spot market is falling. The report is written for Skandinaviska Enskilda Banken and aims to give the bank and readers an understanding on how changes of parameters in a CTA strategy change the outcome of it with focus on three main measurements: Sharpe ratio, drawdown and total return.  The foundation of CTAs is that they rely on signals from some given sets of assets and make investments decisions solely based on them. CTAs can be rule-based with a binomial signal, or they can use a continual signal, like in the report. The thesis aims to recreate a CTA using a continuous momentum signal and with the signal, invest accordingly. Some different variables were tested, most importantly the report focuses on the weights of the assets and investigates if the momentum signal is good as it is or if a risk parity weighting is needed on top of the signal in order to generate a return that matches the expectations of a low drawdown and a high Sharpe ratio.  Beyond the weight allocation, different lookback periods of both the signal and weight were tested. A shorter lookback generated a quicker return that was more sensible to short trends on the market. Which in some cases was profitable but it also lost more of it accumulated return when the trend was "false". The equally weighted signal that only takes the trend into account when allocating the weights of the assets was more volatile it its returns and benefited from a long signal. The CTA results presented can only be seen as an index since it is rebalanced every rebalancing point, the frequency of those points was examined and the strategy was performing well if rebalanced once a week or once a month, every day and once a year did not yield a better result.  As expected, the CTA benefits from trend on the market, no matter the direction of it. The best periods for the CTA were when the market was very volatile, mainly 2008 and 2022. When there is no clear trend, the CTA reacts too slowly and often loses money. One important conclusion is that the CTA never should be used as an investment strategy on its own, rather as a hedging strategy that allocates a fraction of a total long-only portfolio.

<p>In object oriented programming, a Call Graph represents the calling relationships between the program’s methods. To be more precise, a Call Graph is a rooted directed graph where each node of the graph represents a method and each edge <em>(u, v)</em> represents a method call from method <em>u </em>to method <em>v.</em></p><p><em></em>Focus of this thesis is on building a framework for Call Graph construction algorithms which can be used in program analysis. Our framework is able to be initialized by different front-ends and constructs various Call Graph algorithms. Here, we instantiate framework with two bytecode readers (ASM and Soot) as front-ends and implement three Call Graph construction algorithms (CHA, RTA and CTA).<em></em></p><p>At first, we used two above mentioned bytecode readers to read the bytecode of a specific Java program, then we found reachable methods for each invoked method; meanwhile we kept obtained details on our own data structures.  Creating data structures for storing required information about Classes, Methods, Fields and Statements, gives us a great opportunity to implement an independent framework for applying well known Call Graph algorithms. As a result of these data structures, Call Graph construction will not depend on bytecode readers; since, whenever we read the bytecode of a program, we accumulate all necessary points in pre-defined data structures and implement our Call Graphs based on this accumulated data.</p><p>Finally, the result is a framework for different Call Graph construction algorithms which is the goal of this thesis. We tested and evaluated the algorithms with a variety of programs as the benchmark and compared the bytecode readers besides the three Call Graph algorithms in different aspects.</p>

Posttraumatic stress disorder (PTSD) is an anxiety disorder that may follow exposure to severe emotional trauma and presents with various symptoms of anxiety, hyperarousal and cognitive anomalies. Interestingly, only 10-30% of an exposed population will go on to develop full-blown PTSD. Cholinergic neurotransmission is implicated in anxiety as well as other typical manifestations of PTSD, particularly cognitive changes. The frontal cortex and hippocampus regulate and in turn are affected by stress, and have also been implicated in the underlying neuropathology of PTSD. These areas are densely innervated by cholinergic neurons originating from the basal forebrain. In this study, the time dependent sensitization (TDS) model was used to induce symptoms of PTSD in animals. The study was designed to determine the long-term effects of an intense, prolonged aversive procedure on central muscarinic acetylcholine receptor (mAChR) characteristics and the correlation if any of those findings to cognitive aspects and general arousal as characteristics associated with PTSD. In order to achieve this goal, male Sprague-Dawley rats were exposed to the TDS stress paradigm with behavioral/neuro-receptor assessments performed on day 7 post re-stress (duration of each experiment in whole is 14 days). Acoustic startle reflex (ASR) was used to determine emotional state (hyperarousal), while the conditioned taste aversion (CTA) paradigm was implemented in order to assess aversive memory. Muscarinic receptor binding studies were performed in the frontal cortex and hippocampus. Moreover, both the stress-exposed and control animals were pre-tested in the acoustic startle chamber in order to attempt to separate stress sensitive from stress-resilient animals based on predetermined ASR criteria. The ASR niodel was previously validated in our laboratory, while the CTA model was validated in this project before application. In the CTA model, an i.p. injection with lithium chloride (LiCl) (associated with digestive malaise), was used as unconditioned stimulus (US) and was paired with a saccharinlcyclamate drinking solution as conditioned stimulus (CS) to induce aversion to the novel taste (CS) when presented in the absence of the US. Population data of animals tested in the ASR experiment indicated no statistical significant difference between stressed and control animals. However, when each animal was assessed individually, 22.5 % of the exposed population displayed all increase above the predetermined criteria of 35 % in startle response, indicating a state of heightened arousal. In contrast, only 4.2 O h of control animals (no stress) displayed an increase in arousal based on the above mentioned criteria. Muscarinic receptor densities (Bm,) in the total population of animals exposed to stress showed a statistical significant increase in both the hippocampus and frontal cortex when compared to controls, with no changes in & values observed in either one of the areas. In the CTA experiment, TDS stress was implemented as US paired with a saccharinlcyclamate drinking solution as CS. An acute session of prolonged stress (as used in the TDS model) effectively induced aversion to a novel taste and a subsequent reminder of the stress (restress) paired with the CS sustained the acquire adversive memory. Furthermore, LiCl was reintroduced as US in order to assess the effect of prior exposure to two types of stress (acute and TDS) on subsequently acquired CTA memory. Prior exposure to acute stress had no significant effect on subsequently acquired aversive memory when measured either 3- or 7 days post-conditioning (CS-US). Stress-restress (TDS) exposure, however, indicated a significant decrease in aversive memory from 3- to 7 days post-conditioning (CS-US) as well as a significant decrease in aversive memory between the control- and the TDS group 7 days post-conditioning. The mAChR density (B,,) in the frontal cortex; but not in the hippocampus, was elevated at the same point in time (7 days post CS-US pairing) that CTA memory was impaired following TDS stress (stress-restress). Ultimately, these data support an association between altered cholinergic receptors and hyperarousallanxiety in an animal model of PTSD. The data also support the phenomenon of individual susceptibility to stress in animals that parallels that observed in humans exposed to severe trauma. Impaired aversive memory (CTA) is a consequence of prior exposure to TDS stress, but not acute stress, and is likewise mediated by an altered central cholinergic transmission displayed as an increase in mAChRs in the frontal cortex. The lack of studies regarding the influence of the cholinergic system in PTSD related behavior earns ,this project value as inimitable PTSD research. / Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2007.

La qualité microbienne de l’air intérieur représente un enjeu sanitaire important, notamment dans le secteur professionnel. Ces travaux de thèse ont permis d’étudier les conditions favorisant le développement des espèces microbiennes collectées sur des médias fibreux utilisés dans des CTA, ainsi que leur réentrainement an aval de la filtration, susceptible de dégrader la qualité de l’air. La première partie de l’étude s’est déroulée en laboratoire à partir de la filtration d’un consortium bactérien – fongique composé de Staphylococcus epidermidis et Penicillium oxalicum. L’influence de trois paramètres a été étudiée sur la croissance microbienne : le taux d’humidité relative (HR) de l’air, la nature du média fibreux, la présence/absence de flux d’air. Les résultats ont révélé notamment que quelles que soient les conditions,S. epidermidis n’arrive pas à croître. En revanche, lorsque l’HR de l’air approche 100%, P. oxalicum se développe sur les filtres et des spores sont relarguées en aval des filtres après une reprise de la filtration. Une seconde partie de l’étude a consisté à travailler avec un aérosol atmosphérique semi urbain. Deux unités de filtration d’air ont fonctionné pendant 5 mois en parallèle. La ventilation d’une des deux unités a été stoppée chaque week-end et redémarrée en début de semaine. Un suivi de la température, de l’humidité de l’air, de la perte de charge des filtres et de la concentration des particules totales dans l’air en amont de la filtration a été assuré tout au long de l’étude. Les concentrations en microorganismes cultivables ont été mesurées chaque semaine en amont et en aval de chaque filtre, notamment au redémarrage de la ventilation. En fonction des variations saisonnières de la concentration des microorganismes, les résultats ont montré en particulier des efficacités de filtration vis-à-vis des particules bactériennes faibles, voire négatives, dans l’unité de filtration fonctionnant en continu. / Microbial indoor air quality is an important issue in particular in the professional sector. This thesis aims to investigate the conditions leading to microbial development on to fibrous filters and to microbial release down stream of filters that could decrease air quality. The first part of the thesis was realized on laboratory and consisted in the filtration of a microbial consortium composed with Staphylococcus epidermidis (bacterium specie) and Penicillium oxalicum (fungi specie). The effects of three parameters on the microbial behavior were studied : the relative humidity (RH) of the air, the filter material, the airflow presence/absence. Whatever conditions, S. epidermidis did not grow up. However, P. oxalicum has demonstrated its ability to develop itself when RH was close to 100% and some P. oxalicumspores were released downstream of filter after growth, when ventilation was restarted. The second part of the thesis consisted in working with a semi-urban outdoor air. Two air handling unit (AHU) have operated during 5 months. The ventilation of one AHU was stopped each week-end and restarted each beginning of week. Temperature and RH of the air, filters pressure drop and total concentration of PM in air before filtration were monitored. Concentration of total cultivable microorganisms upstream and downstream of both filters was also measured each week, in particular at the restart of ventilation for one AHU. According to seasonal variations of microbial concentrations, results have revealed for instance that the filtration efficiency of cultivable bacteria was particularly weak, and sometimes negative, for the AHU operating continuously.

L'oxyde d'indium dopé à l'étain (ITO) présente une bonne transparence dans le visible<br />et une importante conductivité électrique. Ce travail est consacré à l'étude des performances<br />de films minces multicouches d'ITO obtenus par la voie sol-gel.<br />La microscopie électronique en transmission (MET) a permis d'analyser morphologie<br />et structure, et a mis en évidence pour la première fois la structure complexe de tels films solgel.<br />La MET et l'analyse par rétrodiffusion de particules α ont précisé la corrélation entre la<br />densité des multicouches, l'apparition de croûtes intermédiaires et la conductivité électrique<br />résultante.<br />Ce travail valide l'utilisation du recuit rapide pour la densification des films sol-gel en<br />comparaison avec un traitement classique.<br />Nous démontrons la potentialité de la voie sol-gel pour la croissance d'électrodes<br />d'ITO sur silicium poreux (SP). Les structures ITO/SP, pour lesquelles la photoluminescence<br />du SP est partiellement préservée, ont été étudiées en terme de diode Schottky.

<p>This is a case study of the alternative labour union organization <em>Central de Trabajadores de la Argentina </em>(CTA) in Argentina and the most recent project under process striving for system change, named the Constituyente Social. The case under study is used to illustrate the perception of power in relation to aspirations for societal change among the left in Latin America. The overall struggle of the CTA and the Constituyente Social is to create a more just society based on a deepening of democracy, more participatory in character. Two understandings of power are presented, on the one hand is the <em>taking</em> power concept, inherited from the political struggles where the belief is that power needs to be <em>taken</em> from the elite in order to succeed with structural change in society. On the other hand is the <em>creating </em>power perception, best exemplified with the Zapatista movement in Mexico. There is no conquering of power in this view, but a creation and strengthening of power among the masses. The theoretical chapter presents a view that unites these two perceptions, arguing for the need to intersect the vertical (power taking) and the horizontal (power creating) struggles. The Constituyente Social is analyzed in relation to this intersection, providing concrete examples of where the two power perceptions are utilized, sometimes simultaneously. The overall conclusion is that the dichotomization usually done between the two understandings of power is incomplete and may even damage the struggle for societal change.</p>

Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2007.