Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2008.

Fault diagnosis of sensors, devices, and equipment is an important topic in the nuclear industry for effective and continuous operation of nuclear power plants. All the fault diagnostic approaches depend critically on the sensors that measure important process variables. Whenever a process encounters a fault, the effect of the fault is propagated to some or all the process variables. The ability of the sensor network to detect and isolate failure modes and anomalous conditions is crucial for the effectiveness of a fault detection and isolation (FDI) system. However, the emphasis of most fault diagnostic approaches found in the literature is primarily on the procedures for performing FDI using a given set of sensors. Little attention has been given to actual sensor allocation for achieving the efficient FDI performance. This dissertation presents a graph-based approach that serves as a solution for the optimization of sensor placement to ensure the observability of faults, as well as the fault resolution to a maximum possible extent. This would potentially facilitate an automated sensor allocation procedure. Principal component analysis (PCA), a multivariate data-driven technique, is used to capture the relationships in the data, and to fit a hyper-plane to the data. The fault directions for different fault scenarios are obtained from the prediction errors, and fault isolation is then accomplished using new projections on these fault directions. The effectiveness of the use of an optimal sensor set versus a reduced set for fault detection and isolation is demonstrated using this technique. Among a variety of desalination technologies, the multi-stage flash (MSF) processes contribute substantially to the desalinating capacity in the world. In this dissertation, both steady-state and dynamic simulation models of a MSF desalination plant are developed. The dynamic MSF model is coupled with a previously developed International Reactor Innovative and Secure (IRIS) model in the SIMULINK environment. The developed sensor placement design and fault diagnostic methods are illustrated with application to the coupled nuclear desalination system. The results demonstrate the effectiveness of the newly developed integrated approach to performance monitoring and fault diagnosis with optimized sensor placement for large industrial systems.

Dans le contexte des améliorations du LHC, des efforts importants sont fournis pour concevoir des aimants d'accélérateurs utilisant l'alliage supraconducteur Nb3Sn, qui permet d'atteindre des champs magnétiques plus élevés (>12T). Le but de cette thèse est de proposer de nouvelles méthodes de calcul et de fabrication de dipôles à haut champ en Nb3Sn. Une isolation céramique, mise au point précédemment au CEA Saclay, a été testée pour la première fois sur des câbles, dans les conditions d'utilisation d'un aimant d'accélérateur. Des mesures de courant critique sous champ magnétique et contrainte mécanique ont notamment été réalisées. Ces campagnes d'essais ont révélé que l'isolation céramique actuelle est trop fragile mécaniquement et que les propriétés de courant critique sont dégradées. Une étude a ensuite été menée, afin d'améliorer la tenue mécanique de l'isolation et de mieux répartir les contraintes à l'intérieur du câble. Des méthodes de conception magnétique ont par ailleurs été proposées afin d'optimiser la forme des bobinages, tout en respectant des contraintes d'homogénéité de champ, de marges de fonctionnement, de minimisation des efforts... Pour cela plusieurs codes d'optimisation ont été élaborés. Ils se basent sur des méthodes nouvelles utilisant des formules analytiques. Un code 2D a d'abord été élaboré pour des conceptions en blocs rectangulaires. Ensuite, deux codes 3D ont été conçus pour l'optimisation des têtes de dipôles. Le premier consiste à modéliser le bobinage à l'aide de blocs élémentaires, et le deuxième se base sur une modélisation des câbles supraconducteurs par des rubans. Ces codes d'optimisation ont permis de proposer des configurations magnétiques pour des aimants à haut champ.

<p>Species of Campylobacter, Arcobacter and Helicobacter have been associated with various diseases in humans and animals / and chickens have been identified as a reservoir of these microorganisms. Two published techniques and a new technique, developed in this dissertation, were evaluated to test its efficiency in removing PCR inhibitors from chicken samples. All of the techniques were based on agarose/DNA slants and were evaluated using multiplex PCR and an Internal Amplification Control. The new technique was found to be most effective and consequently used further in the study. A novel study was done to evaluate the survival of Campylobacter, Arcobacter and Helicobacter strains in chicken blood at -20, 4, 37 and 42&ordm / C as well as at ambient room temperature (&plusmn / 22&ordm / C). It was found that all strains could survive at all temperatures, albeit at different duration times. Most notably, an A. butzleri strain was able to survive at 4oC for up to 297 days.</p>

In complex and automated technological processes the effects of a fault can quickly propagate and lead to degradation of process performance or even worse to a catastrophic failure. This means that faults have to be found as quickly as possible and decisions have to be made to stop the propagation of their effects and to minimize process performance degradation. The behavior of the process is affected in different ways by different faults and the fault can be found by ruling out faults for which the expected behavior of the process is not consistent with the observed behavior. In model-based diagnosis, a model describes the expected behavior of the process for the different faults. A device for finding faults is called a diagnosis system. In the diagnosis systems considered here, a number of tests check the consistency of different parts of the model, by using observations of the process. To be able to identify which fault that has occurred, the set of tests that is used must be carefully selected. Furthermore, to reduce the on-line computational cost of running the diagnosis system and to minimize the in general difficult and time-consuming work of tests construction, it is also desirable to use few tests. A two step design procedure for construction of a diagnosis systems is proposed and it provides the means for selecting which tests to use implicitly by selecting which parts of the model that should be tested with each test. Then, the test design for each part can be done with any existing technique for model-based diagnosis. Two different types of design goals concerning the capability of distinguishing faults is proposed. The first goal is to design a sound and complete diagnosis system, i.e., a diagnosis system with the following property. For any observation, the diagnosis system computes exactly the faults that together with the observation are consistent with the model. The second goal is specified by which faults that should be distinguished from other faults, and this is called the desired isolability. Given any of these two design goals, theory and algorithms for selecting a minimum cardinality set of parts of the model are presented. Only parts with redundancy can be used for test construction and a key result is that there exists a sound and complete diagnosis system based on the set of all minimal parts with redundancy in the model. In differentialalgebraic models, it is in general difficult to analytically identify parts with redundancy, because it corresponds to variable elimination or projection. It is formally shown that redundant parts can be found by using a structural approach, i.e., to use only which variables that are included in each equation. In the structural approach, parts with more equations than unknowns are identified with efficient graph-theoretical tools. A key contribution is a new algorithm for finding all minimal parts with redundancy of the model. The efficiency of the algorithm is demonstrated on a truck engine model and compared to the computational complexity of previous algorithms. In conclusion, tools for test selection have been developed. The selection is based on intuitive requirements such as soundness or isolability requirements specified by the diagnosis system designer. This leads to a more straightforward design of diagnosis systems, valuable engineering time can be saved, and the resulting diagnosis systems use minimum number of tests, i.e., the on-line computational complexity of the resulting diagnosis systems become low.

To improve safety, reliability, and efficiency of automotive vehicles and other technical applications, embedded systems commonly use fault diagnosis consisting of fault detection and isolation. Since many systems are constructed as distributed embedded systems including multiple control units, it is necessary to perform global fault isolation using for example a central unit. However, the drawbacks with such a centralized method are the need of a powerful diagnostic unit and the sensitivity against disconnections of this unit. Two alternative methods to centralized fault isolation are presented in this thesis. The first method performs global fault isolation by a istributed sequential computation. For a set of studied systems, themethod gives, compared to a centralizedmethod, amean reduction inmaximumprocessor load on any unitwith 40 and 70%for systems consisting of four and eight units respectively. The second method instead extends the result of the local fault isolation performed in each unit such that the results are globally correct. By only considering the components affecting each specific unit, the extended result in each agent is kept small. For a studied automotive vehicle, the second method gives, compared to a centralized method, a mean reduction in the sizes of the results and the maximum processor load on any unit with 85 and 90% respectively. To perform fault diagnosis, diagnostic tests are commonly used. If the additional evaluation of tests can not improve the fault isolation of a component then the component is ready. Since the evaluation of a test comes with a cost in for example computational resources, it is valuable to minimize the number of tests that have to be evaluated before readiness is achieved for all components. A strategy is presented that decides in which order to evaluate tests such that readiness is achieved with as few evaluations of tests as possible. Besides knowing how fault diagnosis is performed, it is also interesting to assess the effect that fault diagnosis has on for example safety. Since fault tree analysis often is used to evaluate safety, this thesis contributes with a systematic method that includes the effect of fault diagnosis in fault trees. The safety enhancement due to the use of fault diagnosis can thereby be analyzed and quantified.

The aim of this thesis is to provide a thorough characterization of the photosynthetic machinery from the heterocysts of Nostoc punctiforme strain ATCC 29133. In this thesis I describe the protocols I have optimized for the isolation of thylakoids from vegetative cells, the purification of heterocysts and the isolation of thylakoids from the purified heterocysts. The composition of the thylakoid membranes was studied by two dimensional electrophoresis and mass-spectrometry. Further insight into the functionality of the photosynthetic complexes was obtained by EPR, electron transport measurements through Photosystem II (PSII), and fluorescence spectroscopy. The proteome of the heterocysts thylakoids compared to that of the vegetative cell was found to be dominated by Photosystem I (PSI) and ATP-synthase complexes, both essential for keeping high nitrogenase activities. Surprisingly, we found a significant amount of assembled monomeric PSII complexes in the heterocysts thylakoid membranes. We measured in vitro light-driven electron transfer from PSII in heterocysts using an artificial electron donor, suggesting that under certain circumstances heterocysts might activate PSII. Parallel to my main research I also worked in a collaboration to elucidate the total proteome of Nostoc sp. strain 7120 and Nostoc punctiforme using quantitative shotgun proteomics. Several hundred proteins were quantified for both species. It was possible to trace the detailed changes that occurred in the energy and nitrogen metabolism of a heterocyst after differentiation. Moreover, the presence of PSII proteins identified in our membrane proteome was also confirmed and extended. Lastly, I studied how the heterocysts are capable of responding to variations in light quality as compared to vegetative cells. Using 77 K fluorescence spectroscopy on heterocysts and vegetative cells previously illuminated with light at specific wavelengths, I was able to demonstrate that heterocysts still possess a possibly modified but functional antenna system, capable of harvesting light and transferring energy preferentially to PSI. The characterization of the membrane and total proteome permitted to draw a more comprehensive and integrated picture of the interplay between the distinct metabolic processes that are carried out in each cell type at the same time; from oxygenic photosynthesis and carbon fixation in the vegetative cells to the anoxygenic cyclic photophosphorylation essential to power nitrogen assimilation in the heterocysts.

Sammanfattning   Studien syftade till att belysa hur vuxna patienter som isolerats på en infektionsavdelning upplever sin vårdtid. Den ville även utröna om patienterna från sitt perspektiv kunde ge några förslag på hur vårdprocessen skulle kunna förbättras. Fem informanter valdes ut genom bekvämlighetsurval och intervjuades utifrån en strukturerad frågeguide innehållande både faktafrågor, åsiktsfrågor och känslolägesfrågor. Den insamlade informationen bearbetades genom innehållsanalys. Denna process ledde fram till sex kategorier av vikt. Av dessa handlade tre om patienternas känslor och uppleveler – vilka var instängdhet, långtråkighet och fördelar av att vara isolerad – och tre berörde områden som informanterna ansåg kunde förbättras – bättre miljö, hjälp med tidsfördriv samt förbättrad information. Informanterna upplevde överlag att sjukvården tog väl hand om deras somatiska behov emedan det psykosociala omhändertagandet hade något större behov av förbättring. Slutsatsen blev att isolering kan ge upphov till både positiva och negativa känslor och att patienter ofta kan uppleva fluktuationer mellan dessa. Studien visade att behovet av god information inte kan anses vara tillfredsställt. Vidare önskade informanterna bättre hjälp från vårdpersonalen att hantera den tristess som uppkom under tiden som isolerad. Tristessen ökades av en ostimulerande miljö. Kvaliteten på omvårdnaden av isolerade patienter kan därmed ökas genom att öka resurserna inom dessa områden. / Abstract   The study aimed to enlighten how adult patients isolated in an infection ward experienced their stay. A further object was to explore if the patients from their point of view could suggest any improvements in the nursing process. Five informants were chosen by convenience sampling and were interviewed using a structured questioning guide containing questions about facts, opinions and emotions. The collected information was processed with content analysis. This process resulted in six categories of importance. Three of these were about the informant’s feelings and experiences – which were a feeling of being shut in, boredom and advantages of being isolated – and the other three concerned areas that the informants thought could be improved – better environment, help with recreation and improved information. The total experience of the informants was that the medical service handled their somatic needs well while improvements can be done considering the psychosocial care. The conclusion is that isolation care can bring both positive and negative feelings and that the patients often experience fluctuations between these. The study showed that the need of information is not satisfactory fulfilled. Furthermore the informants wished for better help from the hospital staff to counteract the boredom brought on by isolation. This boredom was increased by an uninspiring environment. The quality of care of isolated patients can be improved by increased resources in these areas.

Bakgrund: Vårdpersonal som vårdar isolerade patienter kan känna en viss rädsla för att själva bli smittade och för att sprida smittan vidare till sina medarbetare och till övriga patienter. Denna rädsla kan uppstå till följd av okunskap och informationsbrist vilket i sin tur kan förvärra upplevelsen hos patienten som hålls isolerad. Problem: Patienter som vårdas isolerat påverkas i stor grad av sin situation. För att sjuksköterskor och övrig vårdpersonal ska kunna ge dessa patienter en god vård behövs en bättre förståelse för hur isolerade patienter upplever isoleringsvård. Syfte: Beskriva hur patienter upplever isoleringsvård. Metod: Systematisk litteraturstudie av kvalitativa studier. Resultat: De isolerade patienternas upplevelser kategoriserades i två teman; Frihet och Ensamhet med totalt åtta subteman; Brist på kommunikation, Patienters upplevelser av vårdpersonalens tillvägagångssätt, Att inte få besök, Negativa upplevelser av den fysiska miljön, God kommunikation, Stöd från anhöriga, Tro och reflektion, och Positiva upplevelser av den fysiska miljön. Slutsats: Slutsatsen dras att utan rätt stöd från anhöriga och personal blir isoleringen en negativ upplevelse som leder till en känsla av ensamhet oavsett varför patienten hålls isolerad. / Background: Nursing staff that care for patients in isolation can feel a certain fear, a fear for also being infected and also infecting colleagues and other patients. This fear is based on a lack of knowledge and information which can lead to negative experience for the patient in isolation. Problem: Patients who are cared for in isolation are often significantly impacted by their current surroundings. It is necessary, that if nurses and other nursing staff are to give the patients good healthcare then they need a better understanding of how patients experience isolation. Aim: To describe how patients experience healthcare in Isolation. Method: Systematic literature review of qualitative studies. Result: The experience for isolated patients are categorized into two themes; Freedom and Loneliness which in turn have eight sub-themes; Lack of communication, Patients experience of how the nursing staff act, To not get visits, Negative experience of the physical environment, Good communication, Support from relatives, Faith and reflection, and Positive experience of the physical environment. Conclusion: That, without the correct support from relatives and nursing staff, care for patients in isolation will be considered as negative and will lead to a feeling of loneliness, irrespective for the reason why the patient is in care.

Community-acquired Clostridium difficile infections have recently been increasing in incidence and severity. Several studies have isolated C. difficile spores from livestock and retail meats, suggesting that food may play a role in transmission. No research has been done, however, on what food conditions might allow for the survival and/or growth of the bacterium. We therefore modelled the minimum thresholds for C. difficile growth under low pH, water activity (aw), and temperature. We also sampled retail ground meats, cheese, and milk for the presence of C. difficile spores and subtyped food isolates for comparison with clinical strains. We found that C. difficile growth could be prevented by refrigeration temperatures. C. difficile spores were also detected for the first time in Canada in ground lamb, ground turkey, ground chicken, cheese and milk. The majority of these food isolates were genetically similar to epidemic strain NAP7/078, suggesting that food may not be a direct vector for C. difficile transmission, but could still be clinically relevant.