Thesis (MMed)--Stellenbosch University, 2014. / No abstract available

Tout individu extrait de ses informations sensorielles des invariants directionnels lui permettant de percevoir sa propre situation spatiale ainsi que celle des objets qui l'entourent. Dans les situations habituelles, les traitements relatifs à l'orientation spatiale s'effectuent à partir de référentiels relativement redondants. Cette redondance autorise à la fois la mise en place d'une sensibilité individuelle préférentielle à l'égard d'un de ces référentiels ainsi qu'une large flexibilité dans le choix du référentiel. Lors de ce travail nous avons voulu tester deux hypothèses principales. La 1ère est que les différences interindividuelles observées lors de tâches de perception d'orientation spatiales dépendent du choix du référentiel. La 2nd hypothèse est que l'un des facteurs explicatifs de la variabilité interindividuelle lors de tâches de perception d'orientation spatiale se situe au niveau des règles d'intégration multisensorielle utilisées par les individus. Les résultats montrent que l'ensemble des cadres de références semblent pris en compte par les individus rejetant ainsi la 1ère hypothèse selon laquelle les différences interindividuelles s'expliqueraient par la capacité de certains sujets à exploiter le "bon" cadre de référence. Les résultats montrent que l'un des facteurs explicatifs des différences interindividuelles se situe dans la manière dont le système nerveux central combinerait les différentes informations, certains sujets (DC) semblant incapables de minimiser l'influence des "mauvais" cadre de référence (les moins appropriés, les plus biaisés) en diminuant leur poids respectifs. / Each person extract from sensory information directional invariant which allow him to perceive his spatial situation as well as those of objects surround him. In usual situations, processing relative to spatial orientation is carried out from relatively redundant reference. This redundancy allows both the setting up of preferential individual sensibility regarding those reference and important flexibility in choice of reference. Durant this work, we tested two main hypotheses. The first one is that observed interindividual differences during spatial orientation perception task depend on reference choice. The second one is that one of explanatory factors of interindividual differences during spatial orientation perception task be set in multisensory integration rules level used by the person. Results show that all frame of reference seem to consider by the people rejecting the first hypothesis according to which interindividual differences be explained by the ability of some subjects to exploit the "good" frame of reference. Results show that one of explanatory factors of interindividual differences is set in the way of central nervous system combine several information, some subjects (DC) seems unable to minimize "wrong" frame of reference influence (the least appropriate, the most biased) by reducing respective weight.

Background: In an ongoing study conducted at Karolinska Institutet & Karolinska University Hospital, Positron Emission Tomography (PET)/Computed Tomography (CT) scans are performed on patients with tibia fractures and deformations treated with Taylor Spatial Frames (TSFs) in order to monitor their bone remodeling progress. Each patients receive an administration of approximately 2 MBq/kg bodyweight of Na18F associated with PET scans on two sessions, six and twelve weeks after the attachment of the TSF. These PET/CT scans provide information about the progress of the healing bone and can be used to estimate the optimal time point for de-attachment of the TSF. The Standardized Uptake Value (SUV) is used as a measure of the rate of bone remodeling for these patients, however, there is a need for verification of this practice by a method independent of the PET scanner. Furthermore, information regarding the biodistribution of the Na18F throughout the body of these patients and the effects of the TSF on the CT scan X‑rays is required. Additionally, an investigation of alternative methods that have the potential to provide similar information with a lower absorbed dose to the patients is desirable. Materials and methods: Thermoluminescent Dosimeters (TLDs) were attached on the skin at the position of the heart, urinary bladder, femurs, fracture, and the contralateral tibia of twelve patients during the first one hour and five minutes after the administration of the Na18F. Additional TLD measurements were performed during the CT scan of two of these patients. From the PET scan images, SUVs at the fracture site of these patients were collected. An investigation of the possibility of exploiting the “naturally” occurring bone seeking radionuclide Strontium-90 (90Sr) in the human body to gain information about the fracture site was undertaken. Using a 90Sr source, three different detection techniques were evaluated and a practical methodology for in vivo measurements on the tibia fracture patients was developed. As it was concluded that TLD based measurements were the most suitable technique for this purpose, and it was tested on five patients with tibia fractures. Results: From the collected TLD data, it was concluded that for these patients the urinary bladder is the organ receiving the greatest amount of absorbed dose and the organ most affected as the administered activity exceeds 2 MBq/kg. On average, a three times higher surface dose was measured on the tibia fracture compared to the un-fractured tibia. A linear relationship between the surface dose and SUVmax was shown. A strong positive correlation between the activity concentration at the fracture site and the amount of injected activity was found, and it was demonstrated that this also affects the SUVs. For patients who were administered different amounts of Na18F for the two PET scans, maximum activity concentrationwas less affected than mean activity concentration. It was concluded that TSF’s effect on the scatter of the X-rays to organs higher up in the body is negligible. Regarding “naturally” occurring 90Sr in the human body, no higher activity at the fractured tibia compared to the non‑fractured tibia could be found. Conclusions: This project assessed the accumulation of Na18F in the fracture site of patients treated with TSF by a method independent of the PET scanner. The methodology of using SUVs as an indicator for bone remodeling was verified. It was shown that the uptake of Na18F by the fracture site is strongly correlated to the amount of injected activity. The importance of considering the amount of injected activity when evaluating and comparing SUVs was highlighted. In vivo measurements using LiF:Mn TLDs did not indicate any quantifiable higher concentration of 90Sr at the fracture in the tibia bone.

This thesis is a result of research aimed at analysis of the Taylor Spatial Frames (TSF) in Orthopaedics. The TSF is a ring external fixator, which are used to stabilise a fracture or provide stability during skeletal limb reconstruction procedures. A sound understanding of the mechanics of the fixator is essential, because mechanical stability is a key factor in bone healing. TSF is in fact an adaptation of the hexapod parallel manipulators for dynamisation of the classical ring fixators of Ilizarov type. Therefore, a general solution for Forward kinematics of parallel manipulators was provided and the solution is visualised in real-time. A three-dimensional visualisation tool for TSF, was developed, which offers improvements over the software provided by the manufacturer. Abaqus/CAE programming interfaces were used to develop two separate systems for automatic creation of FEMs of the TSF: one using beam elements and the other using 3D solid elements. The systems were used for a parametric study on axial compression of the TSF. Components of the TSF were also tested and analysed: o TSF rings were studied extensively, which lead to revealing important facts about their role in the TSF. o Fixation bolts in external fixators were studied by FE technique and the results used to relate bolt-load to the bolt-torque applied. o TSF struts were tested in compression and their load-deflection behaviour and the role of universal joints in them were described. TSF and Ilizarov fixators were tested and compared in axial compression. The results highlighted the important role of the pins and wires in deflection of the fixators.

This thesis deals with the ways to create narrative space and its function in two novels of psychological fiction: 'Vlčí jáma' written by Jarmila Glazarová, and 'Helimadoe' by Jaroslav Havlíček. The narrative space is studied from the point of view of the relationship to the character, which is the central focus of psychological fiction. The first part of the thesis includes characteristics of respective characters based on the concept of chronotopes devised by Michail M. Bachtin. Following that, the thesis addresses the narrative approaches represented by theorists such as Marie-Laure Ryan, who focuses on cognitive maps as mental models of spatial relations, and Gabriel Zoran. Particular focus is devoted to the spatial frames put forward by Ruth Ronen, which can be used to observe all characteristics of narrative space. The thesis evaluates the possibilities of narrative space analysis for the interpretation of the selected works of psychological fiction, and compares the contribution of the different approaches to the research of narrative space. KEYWORDS Helimadoe, Vlčí jáma, narrative space, chronotope, Michail M. Bachtin, spatial frame

The subject of the diploma thesis is the design and structural assessment of the load-bearing steel structure of the airport terminal located in Pardubice. Te project is designed in two variants. The dimensions of the foor plan are 83,2x54,295 m. The maximum height of the terminal is 14,662 m.The load-bearing structure consist of a eleven spatial frames at an axial distance of 8,0 m. The spacial rigidity of the structure is ensured by a system of sway and longitudinal bracings.

The Taylor Spatial Frame (TSF) is a recently introduced form of a circular external orthopaedic fixator for long bone fracture reduction and deformity correction. The TSF is constructed from two circular rings interconnected with six variable-length struts. Its kinematics are based on the Stewart-Gough platform. The TSF is attached to the patient's anatomy using fine wires and half-pins. In this thesis, three aspects of the TSF are analysed. First, the solution to non-trivial forward and inverse kinematics has been addressed. Second, the mechanical properties of the TSF fixator are investigated. Individual component stiffness is assessed separately and then the complete fixator is modelled. Simple stiffuess models of fine wires and half-pins are derived. Considerations for the use of the TSF for the peri-articular fractures are investigated and potential modifications are proposed. The effect of backlash in the frame components on the accuracy of the fixator has been analysed. Finally, in rder to validate the kinematics solution, to provide a training aid for surgeons and to demonstrate the concept of accurately controlled interfragmentary motion, a prototype of an active TSF was designed and built. Computationally efficient algorithms for solving the forward and inverse kinematics have been developed that require little numerical processing overhead and can be implemented on a mobile computing device. It was found that the TSF fixator has similar axial stiffuess to the circular Ilizarov ring fixator, since wires and half-pins are significantly less stiff than the frames. Furthermore, the TSF exhibits more uniform stiffuess for a range of off-axis loads and is significantly stiffer for torsional loads than the Ilizarov fixator. Slack, in the form of a backlash, can lead to severe strains in the unloaded frames and therefore fractures, and hence precautions are recommended. Finally, considerations and prototype for the automated TSF are presented that can be utilised for demonstration purposes and surgeon training.

A crescente valorização das áreas disponíveis para a construção de edifícios nas grandes cidades tem constantemente elevado a altura das edificações. Nos edifícios altos, a consideração das ações horizontais na verificação da estabilidade da construção passa a ter um caráter essencial. As ações horizontais podem ser absorvidas, basicamente, por dois sistemas estruturais: por uma estrutura composta por pórticos de grande rigidez ou pela combinação de pórticos e paredes estruturais. Dentro deste contexto, esta dissertação trata da análise tridimensional de estruturas de edifícios altos de concreto armado, considerando a presença de paredes estruturais. Ao longo do trabalho é desenvolvido um modelo computacional em linguagem FORTRAN 90, baseado no Método dos Elementos Finitos, para realizar este tipo de análise. O modelo segue as recomendações da NBR6118 (ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS, 2007). Conforme esta norma, a não linearidade física é considerada de forma simplificada pela redução da rigidez dos elementos através de um fator fixo, função do nível de fissuração esperado A não linearidade geométrica, por outro lado, pode ser considerada de maneira simplificada ou de forma exata a partir de uma formulação desenvolvida por Argyris et al. (1979). No modelo analisado, foram implementados elementos de pórtico espacial para a representação de vigas e pilares, e de casca poliédrica para as paredes e lajes. Com o objetivo de se obter um sistema computacional eficiente, são utilizados recursos como a hipótese de diafragma rígido nos pavimentos e a subestruturação. Tais recursos permitem diminuir o tamanho do problema a ser resolvido, sem, no entanto, perder precisão nos resultados. O desenvolvimento do modelo computacional permitiu uma análise crítica de casos, confrontando as duas alternativas de sistemas para edifícios altos, ou seja, de pórticos com e sem paredes estruturais. / The on going increase in value of available construction sites in big cities has steadily pushing up the height of new buildings. In high-rise buildings, the consideration of lateral loads when stability is verified gains an essential role. Basically, lateral loads can be carried out by two types of structural systems: by a structure composed of high-stiffness frames or by a combination of these frames and shear walls. In this context, this work focuses on 3D analyses of high-rise reinforced concrete buildings with the consideration of shear walls. A computational model based on the Finite Element Method is developed for the analyses, being the model described in detail in the text. The model follows the recommendations given in the Brazilian code NBR6118:2007. According to this code, physical nonlinearities are considered in a simplified manner by decreasing stiffnesses by a fixed factor, which depends on the expected level of cracking. Geometrical nonlinearities, on the other hand, could be considered either in a simplified manner or in an exact approach from the formulation developed by Argyris et al. (1979). In the developed model, spatial frame elements were implemented to represent beams and columns, while polyedric shells would represent shear walls and slabs. Targeting an efficient computational system, the rigid diaphragm hypothesis for the slabs as well as substructuring procedures were demanded strategies. Such means allowed smaller problem sizes to be solved without putting in jeopardy the results’ precision. It is also presented an analysis confronting the two alternatives of systems for high-rise building structures, i.e., frames with and without shear walls.

A crescente valorização das áreas disponíveis para a construção de edifícios nas grandes cidades tem constantemente elevado a altura das edificações. Nos edifícios altos, a consideração das ações horizontais na verificação da estabilidade da construção passa a ter um caráter essencial. As ações horizontais podem ser absorvidas, basicamente, por dois sistemas estruturais: por uma estrutura composta por pórticos de grande rigidez ou pela combinação de pórticos e paredes estruturais. Dentro deste contexto, esta dissertação trata da análise tridimensional de estruturas de edifícios altos de concreto armado, considerando a presença de paredes estruturais. Ao longo do trabalho é desenvolvido um modelo computacional em linguagem FORTRAN 90, baseado no Método dos Elementos Finitos, para realizar este tipo de análise. O modelo segue as recomendações da NBR6118 (ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS, 2007). Conforme esta norma, a não linearidade física é considerada de forma simplificada pela redução da rigidez dos elementos através de um fator fixo, função do nível de fissuração esperado A não linearidade geométrica, por outro lado, pode ser considerada de maneira simplificada ou de forma exata a partir de uma formulação desenvolvida por Argyris et al. (1979). No modelo analisado, foram implementados elementos de pórtico espacial para a representação de vigas e pilares, e de casca poliédrica para as paredes e lajes. Com o objetivo de se obter um sistema computacional eficiente, são utilizados recursos como a hipótese de diafragma rígido nos pavimentos e a subestruturação. Tais recursos permitem diminuir o tamanho do problema a ser resolvido, sem, no entanto, perder precisão nos resultados. O desenvolvimento do modelo computacional permitiu uma análise crítica de casos, confrontando as duas alternativas de sistemas para edifícios altos, ou seja, de pórticos com e sem paredes estruturais. / The on going increase in value of available construction sites in big cities has steadily pushing up the height of new buildings. In high-rise buildings, the consideration of lateral loads when stability is verified gains an essential role. Basically, lateral loads can be carried out by two types of structural systems: by a structure composed of high-stiffness frames or by a combination of these frames and shear walls. In this context, this work focuses on 3D analyses of high-rise reinforced concrete buildings with the consideration of shear walls. A computational model based on the Finite Element Method is developed for the analyses, being the model described in detail in the text. The model follows the recommendations given in the Brazilian code NBR6118:2007. According to this code, physical nonlinearities are considered in a simplified manner by decreasing stiffnesses by a fixed factor, which depends on the expected level of cracking. Geometrical nonlinearities, on the other hand, could be considered either in a simplified manner or in an exact approach from the formulation developed by Argyris et al. (1979). In the developed model, spatial frame elements were implemented to represent beams and columns, while polyedric shells would represent shear walls and slabs. Targeting an efficient computational system, the rigid diaphragm hypothesis for the slabs as well as substructuring procedures were demanded strategies. Such means allowed smaller problem sizes to be solved without putting in jeopardy the results’ precision. It is also presented an analysis confronting the two alternatives of systems for high-rise building structures, i.e., frames with and without shear walls.

A crescente valorização das áreas disponíveis para a construção de edifícios nas grandes cidades tem constantemente elevado a altura das edificações. Nos edifícios altos, a consideração das ações horizontais na verificação da estabilidade da construção passa a ter um caráter essencial. As ações horizontais podem ser absorvidas, basicamente, por dois sistemas estruturais: por uma estrutura composta por pórticos de grande rigidez ou pela combinação de pórticos e paredes estruturais. Dentro deste contexto, esta dissertação trata da análise tridimensional de estruturas de edifícios altos de concreto armado, considerando a presença de paredes estruturais. Ao longo do trabalho é desenvolvido um modelo computacional em linguagem FORTRAN 90, baseado no Método dos Elementos Finitos, para realizar este tipo de análise. O modelo segue as recomendações da NBR6118 (ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS, 2007). Conforme esta norma, a não linearidade física é considerada de forma simplificada pela redução da rigidez dos elementos através de um fator fixo, função do nível de fissuração esperado A não linearidade geométrica, por outro lado, pode ser considerada de maneira simplificada ou de forma exata a partir de uma formulação desenvolvida por Argyris et al. (1979). No modelo analisado, foram implementados elementos de pórtico espacial para a representação de vigas e pilares, e de casca poliédrica para as paredes e lajes. Com o objetivo de se obter um sistema computacional eficiente, são utilizados recursos como a hipótese de diafragma rígido nos pavimentos e a subestruturação. Tais recursos permitem diminuir o tamanho do problema a ser resolvido, sem, no entanto, perder precisão nos resultados. O desenvolvimento do modelo computacional permitiu uma análise crítica de casos, confrontando as duas alternativas de sistemas para edifícios altos, ou seja, de pórticos com e sem paredes estruturais. / The on going increase in value of available construction sites in big cities has steadily pushing up the height of new buildings. In high-rise buildings, the consideration of lateral loads when stability is verified gains an essential role. Basically, lateral loads can be carried out by two types of structural systems: by a structure composed of high-stiffness frames or by a combination of these frames and shear walls. In this context, this work focuses on 3D analyses of high-rise reinforced concrete buildings with the consideration of shear walls. A computational model based on the Finite Element Method is developed for the analyses, being the model described in detail in the text. The model follows the recommendations given in the Brazilian code NBR6118:2007. According to this code, physical nonlinearities are considered in a simplified manner by decreasing stiffnesses by a fixed factor, which depends on the expected level of cracking. Geometrical nonlinearities, on the other hand, could be considered either in a simplified manner or in an exact approach from the formulation developed by Argyris et al. (1979). In the developed model, spatial frame elements were implemented to represent beams and columns, while polyedric shells would represent shear walls and slabs. Targeting an efficient computational system, the rigid diaphragm hypothesis for the slabs as well as substructuring procedures were demanded strategies. Such means allowed smaller problem sizes to be solved without putting in jeopardy the results’ precision. It is also presented an analysis confronting the two alternatives of systems for high-rise building structures, i.e., frames with and without shear walls.