Les endoscopes utilisés en gastro-entérologie ne permettent pas d’obtenir une réelle chirurgie dans le tube digestif en passant par les voies naturelles. Cette thèse a pour ambition de pallier ce manquement grâce au développement d’une plate-forme de triangulation universelle. Cette plateforme donne la possibilité au gastro-entérologue d’augmenter de manière significative ses possibilités thérapeutiques en lui permettant de réaliser des actes chirurgicaux de base tels que “soulever-couper” et “suturer” les tissus. Ces actes ne peuvent être réalisés qu’extrêmement difficilement avec les endoscopes conventionnels. Ils constituent pourtant les éléments essentiels en vue de traiter l’obésité morbide ou le traitement du reflux gastro-oesophagien par les voies naturelles. La caractéristique principale de la plate-forme développée dans cette thèse est son universalité lui permettant une utilisation avec pratiquement n’importe quel type d’endoscope et outils thérapeutiques existants sur le marché. La plate-forme a obtenu le marquage CE. Des études cliniques ont été réalisées avec cet instrument dans le cadre du traitement de l’obésité. Cette thèse comprend également une méthodologie de conception pour des guidages flexibles utilisés dans le domaine médical. Cette méthodologie basée sur l’élaboration d’abaques théoriques permet, d’une part, à partir des desiderata du médecin, d’identifier les paramètres externes (rigidité, longueur.) d’un guidage flexible et ce peu importe le type de guidage utilisé et, d’autre part, de déduire les paramètres internes associés à ces paramètres externes pour un type de guidage particulier: un élastomère renforcé par un ressort hélicoïdal. La méthode a été appliquée `a posteriori `a la plate-forme de triangulation et donne, dans ce cas, de bons résultats. Flexible endoscopes used in gastro-enterology do not allowed a real surgery in the gastrointestinal tract passing through natural orifices. This thesis aimed to overcome these limitations by developing a universal triangulation platform. This platform allows the gastro-enterologist to significantly increase his therapeutic possibilities by enabling him to perform basic surgical procedures such as "lifting-cutting" and "suturing" the tissues. These procedures can only be performed with extreme difficulty with conventional endoscopes. They are, however, the essential elements for the treatment of morbid obesity or gastroesophageal reflux through natural orifice. The main feature of the platform developed in this thesis is its universality allowing it to be used with any type of endoscopes and existing tools available on the market. The platform has obtained the CE marking. Clinical studies have been conducted with this instrument for treatment of obesity. This thesis includes also a design methodology for flexible guides used in the medical field. This methodology, based on the elaboration of theoretical abacuses, allows, firstly, from the physician's specifications, to identify the external parameters (rigidity, length .) of the flexible guide regardless of the type of the used guide. Secondly, it allows to determine the internal parameters associated with these external parameters for a particular type of guide: an elastomer reinforced by a helical spring. The method was applied a posteriori to the triangulation platform and, in this case, gives good results. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

Extragalactic charged particles, each with energies rising up to and beyond 1 Joule, have been studied for almost a century. Yet, no precise evidence have proven to show where they might originate from as their energy levels rise above the current familiar acceleration sources in outer space. The highly energetic particles have been given the name Ultra-High Energy Cosmic Rays (UHECR) and investigations of particle properties such as primary energy, mass composition and direction can be made through indirect measurements of the interaction between the UHECR and Earth's atmosphere. The considered interaction induces an Extensive Air Shower (EAS) which emits fluorescent light in the Ultraviolet (UV) range. The probability of detecting such events is, however, as low as a few particles per km2 per century. Making observations more sufficient therefore requires larger detection volumes. By introducing the Mini-EUSO instrument, a telescope of which the main purpose is to measure the UV-light radiated from the Earth in the wavelength range of 300-400 nm, allows just for this. To be accommodating the International Space Station and targeting Earth in the nadir direction, the Mini-EUSO instrument will allow for a higher exposure to the interactions than what is currently available. The use of two Fresnel lenses provides the instrument with a large field of view (±22o) and the detections are made through multiple photomultiplier tubes. The scope of this thesis is to evaluate the main detector of the Mini-EUSO instrument (i.e. the UV-detector) through ground-based tests. The procedures involved in the evaluation have consisted of; validating the statistical distributions of the signals, implementing dark field and flat field calibrations, and radiations measurements with three kinds of radiation sources. The data from the tests were provided during two periods and the visualization was made by adapting an already existing piece of code, using Python and ROOT Cern, to perform step by step procedures such that all operations are overlooked properly. The analysis showed that the implementation of the dark field and flat field procedures improved the original image significantly. It also showed that both the lower and higher photon count values in a pixel indeed gave the expected statistical behaviours, with a Poissonian distribution for low values and a Gaussian distribution for higher values. The flat fielding screen did however show unknown fluctuations in the emitted light and further tests have to be implemented to assure its functionality. Under proper covering, almost no dark current was found, however, observation tests showed that the borders of the Multi-Anode Photomultiplier Tubes (MAPMTs) gave higher photon count values than the center part even when they were emitted with Lambertian light.

Le travail de cette thèse concerne l’étude des écoulements diphasiques dans les mini-canaux d’une pile à combustible. Ces canaux, de taille millimétrique, ont un double rôle d’alimentation de la pile en combustibles gazeux et d’évacuation de l’eau produite. Il a été montré expérimentalement que la configuration d’écoulement a un impact direct sur les performances de la pile. L’objectif est donc de progresser dans la compréhension des mécanismes physiques présents dans ces canaux. Pour cela, l’outil de simulation numérique JADIM est développé pour modéliser la physique de la ligne triple afin de permettre la description des écoulements diphasiques et les transitions entre configurations, où la mouillabilité joue un rôle déterminant. Deux phénomènes physiques sont essentiellement étudiés : la migration dans le canal de gouttelettes formées par l’introduction d’eau dans le canal, et l’évolution et la stabilité de la répartition spatiale des phases lors du remplissage progressif des canaux.

Magister Scientiae - MSc / The Bredasdorp Basin is one of the largest hydrocarbon producing blocks within Southern Africa. The E-M field is situated approximate 50 km west from the FA platform and was brought into commission due to the potential hydrocarbons it may hold. If this field is brought up to full producing capability it will extend the lifespan of the refining station in Mosselbay, situated on the south coast of South Africa, by approximately 8 to 10 years. An unexpected pressure drop within the E-M field caused the suite not to perform optimally and thus further analysis was imminent to assess and alleviate the predicament. The first step within the project was to determine what might have cause the pressure drop and thus we had to go back to cores drilled by Soekor now known as Petroleum South Africa, in the early 1980’s. Analyses of the cores exposed a high presence of granulation seams. The granulation seams were mainly subjected within sand units within the cores. This was caused by rolling of sand grains over one another rearranging themselves due to pressure exerted through compaction and faulting, creating seal like fractures within the sand. These fractures caused these sand units to compartmentalize and prohibit flow from one on block to the next. With advance inquiry it was discovered that there was a shale unit situated within the reservoir dividing the reservoir into two main compartments. At this point it was determined to use Petrel which is windows based software for 3D visualization with a user interface based on the Windows Microsoft standards. This is easy as well as user friendly software thus the choice to go with it. The software uses shared earth modeling tool bringing about reservoir disciplines trough common data modelling. This is one of the best modelling applications in the available and it was for this reason that it was chosen to apply within the given aspects of the project A lack of data was available to model the granulation seams but with the data acquired during the core analyses it was possible to model the shale unit and factor in the influences of the granulation seams to asses the extent of compartmentalization. The core revealed a thick shale layer dividing the reservoir within two sections which was not previously noted. This shale layer act as a buffer/barrier restricting flow from the bottom to the top halve of the reservoir. This layer is thickest at the crest of the 10km² domal closure and thins toward the confines of the E-M suite. Small incisions, visible within the 3 dimensional models could serve as a guide for possible re-entry points for future drilling. These incisions which were formed through Lowstand and Highstand systems tracts with the rise and fall of the sea level. The Bredasdorp Basin consists mainly of tilting half graben structures that formed through rifting with the break-up of Gondwanaland. The model also revealed that these faults segregate the reservoir further creating bigger compartments. The reservoir is highly compartmentalized which will explain the pressure loss within the E-M suite. The production well was drilled within one of these compartments and when the confining pressure was relieved the pressure dropped and the production decrease. As recommendation, additional wells are required to appraise the E-M structure and determine to what extent the granulation seems has affected fluid flow as well as the degree of sedimentation that could impede fluid flow. There are areas still containing untapped resources thus the recommendation for extra wells. / South Africa

Les mini-granules enrobées offrent un grand potentiel pour la libération contrôlée de médicament par voie orale. Cependant, les mécanismes de libération impliqués ne sont pas toujours élucidés et compris. Ainsi, l’impact de certains paramètres de formulation peut être surprenant. Par exemple, il a été démontré dans ce travail :- La libération du propranolol HCl à partir de mini-granules enrobées avec du Kollicoat SR est plus lente si les mini-granules sont composées de noyaux de sucre comparé à des noyaux de cellulose microcristalline (CMC).Généralement, la tendance inverse est observée, car les noyaux de sucre ont une activité osmotique attirant plus rapidement l’eau à l’intérieur du système et entrainant ainsi, une dissolution et diffusion de la substance active. Ce résultat inattendu est dû à une association de 2 phénomènes : (i) l’effet plastifiant dû au sucre sur le film de Kollicoat SR et (ii) la diminution de la solubilité de cette SA dans le milieu de dissolution en présence de sucre dissous.De plus, le Kollicoat SR 30 D [dispersion aqueuse de poly(vinyl pyrrolidone)] offre des possibilités intéressantes de formulation par sa haute flexibilité et ses propriétés mécaniques stables. En revanche, les mini-granules composées de noyaux de sucre ont tendance à gonfler de par le cumul de l’activité osmotique du noyau et de la SA jusqu’à l’apparition de « cracks », révélés par des images obtenues par micro tomographie à rayons X.- Lorsqu’on augmente la quantité en propranolol HCl dans le système, la cinétique de libération est augmentée, particulièrement avec les mini-granules composées de noyaux de CMC.L’opposé est souvent constaté car accroitre la quantité de SA nécessite un plus grand apport en eau afin de pouvoir tout dissoudre. Les mini-granules à base de CMC présentent probablement des « cracks » malgré un faible gonflement du système, et sont accentués par l’augmentation de la concentration en propranolol HCl.En conclusion, des nouvelles connaissances sur les mécanismes de libération à partir de mini-granules enrobées avec du Kollicoat SR ont été apportées et l’importance du type de SA et la nature du noyau composant le système ont été élucidées.- Dans une deuxième partie, des mini-granules enrobées avec un mélange de polymère (Aquacoat ECD et Eudragit NM 30 D) ont été formulées dans le but de libérer la diprophylline, SA modèle, par diffusion à travers le film de polymère et de pouvoir modéliser sa cinétique à partir de modèles mathématiques. / Polymer coated pellets offer a great potential for control drug delivery system. Nevertheless, the underlying drug release mechanisms can be complex and are not fully understood. Thus, the impact of formulation parameters can be surprising. For example, it has been demonstrated during this thesis that:- The release of propranolol HCl was slower from sugar-based pellets coated with Kollicoat SR compared to microcrystalline cellulose (MCC)-based pellets.Generally, the opposite was observed because the sugar cores are osmotically active attracting more and more water into the system leading to a fast dissolution and diffusion of the drug, especially with high water-soluble drug. This unexpected result is due to a combination of two phenomena: (i) The plasticizing effect of sugar for the film coating and (ii) Decrease in drug solubility in the release medium due to the presence of co-dissolved sugar.In addition, Kollicoat SR 30 D [an aqueous dispersion of poly(vinyl acetate) also containing small amounts of poly(vinyl pyrrolidone) and sodium lauryl sulfate] is a very interesting polymer owing to its high flexibility and stable mechanical properties. However, sugar-based pellets tend to swell by the osmotic pressure created by the high water-soluble API and the sugar until crack formation, clearly visible on the images obtained by X-ray micro tomography.- Propranolol HCl release in phosphate buffer pH 7.4 increases by increasing the drug loading into the system, especially from MCC-based pellets.The opposite was often observed since the amount of water within the drug reservoir might not be sufficient to dissolve all drug. MCC-based pellets likely presented also cracks despite a low swelling of the system, accentuated by the increase of propranolol HCl concentration.To conclude, new insights on the underlying drug release mechanisms from Kollicoat SR coated pellets were provided. The importance of the type of drug and the nature of starter cores were elucidated.- In the second part, diprophylline loaded pellets coated with a polymer blend composed of Aquacoat ECD and Eudragit NM were prepared in order to control the drug release only by diffusion through the intact polymeric film and to predict the drug kinetics using mathematical models.

There is no evidence in the literature of biomechanical stability characteristics comparing conventional rectangular screw placement with that of an angled mono-cortical screw plating system where standard 2mm diameter screws are applied at angles more acute than conventional 90° screws, through plate holes machined (cut) for a definite specific screw angle placement P. Angled screws will have an obvious clinical advantage of direct line of vision insertion, through an intra-oral route without the disadvantage of trans-buccal (cutaneous) approach required for conventional 90° rectangular screw application. Angled screw application will result in the prevention of possible, less post-operative swelling, nerve fall out (motor and/or sensory), haematoma, false aneurysm and scarring as unwanted clinical complications associated with trans-buccal extra-oral surgical technique. Intra-oral angled screw application will result in definitive cost saving due to less operating time required. Post-treatment removal of angled screws is uncomplicated, requiring only intra-oral surgical approach, without trochar use or skin incisions for screwdriver application. By determining angle displacement values at certain clinical relevant force values for both compression/tension and torsion, preference can be established for ideal angle(s) of screw application in a plating system. An own unique, designed and manufactured, jig and inclined screw insertion (ISI) plates were implemented during the biomechanical evaluation of stability at different screw angle applications in a Zwick machine. For the purpose of this biomechanical comparative investigation an inclined screw insertion (ISI) plate was manufactured with 90°, 75°, 60° and 45° angled plate holes orientated in line with the long-axis (quadrant 3) of the distal section of the plates and diagonal across (quadrant 1) in the proximal section of the plates. Screws with an ISI angle of 30° in any quadrant application resulted in lifting the plate from the bone surface and caused cortical bone destruction during pilot drilling. The results for mono-cortical 7mm screw placement proved superior in biomechanical stability during tension/compression - forces for screw insertion angles of 60° and 45°, when compared to conventional 90° rectangular screw placement. Screws inserted at an angle of 75° demonstrated no improvement in compression/tension stability when compared with 90°.Torsion force stability for all of the 75°, 60° and 45° inclined screw insertion (ISI) systems proved more stable compared to conventional 90° screw angle plates. It is concluded that angled monocortical screw placement between angles 60° and 45° has clinical significance as far as stability, intra-oral surgical technique and time-cost factor is concerned. The results of this biomechanical behaviour investigation of ISI, evolved new terminology such as screw-tip shifting, screw-tip travel, lag potential and clinical significance for the range of screw angle placement. Angled orientation to the plate design and plate geometry is also defined in terms of tension line distribution in the anatomical region for application in the mandible. An unique quadrant description for ISI is described for future communication. An international patent, based on the ISI principle, has been registered for monocortical six-hole plates of firstly different geometric designs to conform to specific anatomical topographic sites in the mandible and secondly specific screw plate-holes angled at 60° in different orientation to the plate (Patent:PCT/EP 2006/006365), (Addendum 6). A specific L-shaped, mandibular angle plate with screw holes at a 60° angle where orientation shifts from in-line with the long-axis of the plate in the distal three plate holes to diagonal orientation in the proximal section of the plate, is designed and manufactured by Stryker/Leibinger as an example of such a patent plate. It is recommended that a smart-lock plate with plate holes at 55° angles be manufactured to allow screw angle placements of 65° - 45° in different angle orientations. Pilot hole drilling and ISI can be performed without the use of a drill-guide. / Thesis (PhD)--University of Pretoria, 2009. / Maxillo-Facial and Oral Surgery / unrestricted

Background: Malnutrition occurs in almost one-fifth of the elderly in nursing homes. Malnutrition may contribute to problems such as impaired immune system, impaired healing, decreased lung and muscle function, as well as prolonged care in hospitals and increased mortality. Energy and protein dense dietary is prescribed to prevent and treat malnutrition. Objective: To investigate how many of the elderly in nursing homes were malnourished or at risk of malnutrition and how many of them were prescribed energy and protein dense dietary. Method: The design of this study was retrospective descriptive, with quantitative approach. Data from completed Mini Nutritional Assessments and existing diet certificates were collected and reviewed using a review template. Results: According to the Mini Nutritional Assessments, 144 (70%) elderly were screened for malnutrition. Of these 14 (10%) were assessed to be malnourished and 66 (46%) were at risk of malnutrition. Energy and protein dense dietary was prescribed in 12 (86%) of those who were malnourished, while 21 (32%) elderly at risk of malnutrition were prescribed energy and protein dense dietary. The difference between the groups was significant (p= .000). Conclusion: A majority was screened with Mini Nutritional Assessment. Nutritional status showed a small proportion of malnourished, and the majority were at risk of malnutrition. Most of the malnourished were prescribed energy and protein dense dietary, while the recommendation to prescribe this diet at risk of malnutrition had low compliance.

This dissertation investigates the significant problem of abandoned buildings in the Pretoria Central Business District and, to a lesser extent, the lack of public exposure to art, architecture and design. For the purpose of this study, empty spaces in the City Centre and Die Meent buildings are examined. A new system for their reuse is developed and a gallery for the exhibition of multiple art forms is incorporated therein, as an example of how the aforementioned system can be appropriated. These problems, especially the first, is not restricted to the local urban context. The investigation is thus divided into two phases: the first provides a solution to the challenge of reusing abandoned spaces in buildings; the second phase, as a proposed future exploration of this system, provides a solution to the need for a multi-purpose exhibition area. City Property is the proposed client for the first phase, while MINI Space is the proposed client for the second phase. Empty buildings are a growing concern worldwide, due to concerns for sustainable development and decreasing greenfield sites. This dissertation proposes that the term ‘site’ should be redefined, using the x-y-z axes as a base. By applying the theory of Deconstruction, it is argued that ‘ground zero’ be shifted to a higher level, to include not only the x- and y-axis, but also the z-axis, leading to the creation of truly three-dimensional cities. This project aims to advance a new way of looking at the city and promoting different forms of art. Culturally rich spaces within vibrant cities with multiple levels of living, working and playing, aid the creation of new communities and unique spaces for each individual. Copyright / Dissertation (MArch(Prof))--University of Pretoria, 2010. / Architecture / unrestricted

Fluxes of carbon dioxide (CO2), being a major greenhouse gas, are of great importance to understand and monitor. Findings have shown that while CO2 emissions enhanced by humans triggered the greenhouse gas effect, several significant CO2 fluxes in nature that are climate sensitive may still be poorly constrained, especially those from inland waters and its surrounding soils and sediments. This including different processes such as decomposers degrading organic material. At present, direct measurements of CO2 from soils, waters or CO2 concentrations in surface water, are typically labour intensive or require costly equipment. Therefore, small inexpensive CO2 mini loggers, originally made for indoor air quality monitoring, are for this project being developed further for field use, as a convenient equipment to measure CO2 emissions. However, a requirement is that the mini loggers are stable and robust against interference by other air components, including water vapour, and physical factors such as temperature. Therefore, the mini loggers were for this project studied further under different environmental conditions such as temperature and humidity in a controlled environment. The results were analysed using multiple regression analysis where the CO2 concentration (CO2), measured by the LGR instrument, versus the logger IR signal (IR), temperature (T) and relative humidity (RH) were studied. Unlike some previous studies, this project studied a large CO2 concentration interval (400 – 10 000 ppm).  The results show that there was a strong regression for IR versus CO2. The regression for both RH and the T was on the other hand very weak. However, there were factors that could have affected the mini logger. This since it was noticed that the mini loggers’ ability to calculate the CO2 concentration was worsened when the humidity was increased during the experiments. It is believed that the cause was condensed water, gathering in the inner parts of the mini logger. This because the sensor chamber had a lower temperature than the hot air entering the sensor chamber from the humidity bottle, together with the CO2, leading to condensation. Hence, prevention of condensation inside the measurement cell is important. However, the results from the analysis shows that the factors; RH and T do not need to be taken into account when studying the CO2 concentration over a larger interval, as long as the conditions are not condensing.

More spirometric analysis needs to be performed in order to discover lung diseases like chronic obstructive pulmonary disease (COPD). A mini spirometer can quickly and easily be used for screening. Today, a plethysmograph is used at the hospital in Helsingborg at the department of clinically physiology. However, they also have a mini spirometer, which is seldom used. By comparing the mini spirometer with the reference (the plethysmograph), results may indicate whether it could be possible to use the mini spirometer for screening or in other situations at the department when immediate and reliable information about lung function is needed. As a total of 45 patients participated in this study. All were examined with the mini spirometre after the conventional spirometry using a reversibility test. Of these there were 41 who were used in the study. After the conventional spirometry, they performed 4 - 7 forced expirations followed by inspirations. Theparameters investigated were FVC (forced vital capacity), FEV1 (forced expiratory vital capacity in 1 second), and FEV1/FVC. For the conventional spirometry slow VC was used, according to clinical routine. With 95 % CI the mean ・} SD was calculated to be for FVC between the 2 methods -0,19 ・} 0,30 litre. For FEV1 the results were 0,04 ・} 0,13 litre and for FEV1/FVC 0,05 ・} 0,05 litre. Paired t-test resulted for FVC in t = 4,1. FEV1 gave t= 1,79 and for FEV1/FVC was t= 6,28. The t-values were compared with t critical= 2,03 which were taken from a table. A lower t- value than t critical suggests that the methods are comparable. When comparing the difference between the both methods, FEV1 agreed well, while FVC and FEV1/FVC was too large. / Fler spirometrier behover genomforas for att upptacka lungsjukdomar som t.ex. kronisk obstruktiv lungsjukdom (KOL). En minispirometer kan snabbt och enkelt screena for detta. Pa Helsingborgs lasarett pa avdelningen for klinisk fysiologi anvands rutinmassigt enbart en plethysmograf-spirometer, trots att det dar aven finns en minispirometer. Genom att undersoka hur noggrann minispirometern ar jamfort med den vanligtvis anvanda spirometern, kan den lilla varianten i vissa fall anvandas vid t.ex. screening eller i samband med andra undersokningar dar information om lungfunktion behovs. Sammanlagt stallde 45 konsekutiva patienter upp pa analys via minispirometri efter genomford konventionell spirometri med reversibilitetstest. Av dessa anvandes 41 stycken i undersokningen. Efter den konventionella spirometrin fick de utfora 4 - 7 forcerade expirationer direkt foljt av inspirationer. De parametrar som anvandes var forcerad expiratorisk volym under den forsta sekunden (FEV1), forcerad vital kapacitet (FVC) och kvoten FEV1/FVC. For den konventionella spirometrin anvandes langsam VC enligt klinisk rutin. Med 95 % KI beraknades medelvardet och SD for skillnaden i FVC mellan de bada metoderna till -0,19 ・} 0,30 liter. For FEV1 var resultatet 0,04 ・} 0,13 liter och kvoten FEV1/FVC gav 0,05 ・} 0,05. Parat t-test gav for FVC t= 4,1. For FEV1 t= 1,79 och for kvoten FEV1/FVC t= 6,28. T- vardena jamfordes med t kritiskt = 2,03 som erholls ur en tabell. Ett lagre t- varde an tkritiskt antyder att metoderna ar tillrackligt lika. FEV1 stamde bra overens mellan de bada metoderna. Det fanns en signifikant skillnad for FVC och forkvoten FEV1/FVC.