Although axillary artery injury occurs frequently with dislocations of the shoulder and fractures of the clavicle, it is rarely associated with fractures of the proximal humerus. If the axillary artery is damaged, prompt recognition and treatment are necessary to salvage the involved extremity.

No description available.

Thesis (DMed)--Stellenbosch University, 2008. / The comparative study presented in this dissertation specifically aimed to assess fracture risk in black (Xhosa) and white South African women by evaluating known determinants of bone strength as well as the propensity to falls. We thus compared the prevalence of clinical (historic) risk factors for osteoporosis, measured and compared vertebral and femoral bone mineral density (BMD) employing dual energy X-ray absorptiometry (DEXA), ultrasound variables using the Sahara sonometer, serum parathyroid hormone (PTH) and 25-OH Vitamin D, mineral homeostasis and modern biochemical markers of bone turnover, bone geometry and the propensity to falls. Finally, we determined the prevalence of vertebral fractures in these black and white South African females. 1. Significant ethnic differences were noted in the presence and frequency of historical clinical and lifestyle risk factors for osteoporosis. Blacks were heavier and shorter, they consumed less calcium, were more inactive, preferred depot-medroxyprogesterone acetate as contraceptive agent and were of higher parity. Whites smoked more, preferred oral oestrogen containing contraceptive tablets and were more likely to have a positive family history of osteoporosis. Hormone therapy was used almost exclusively by postmenopausal whites. Inter-ethnic differences in weight, physical activity and high parity was most marked in the older subjects. 2. We found that peak spinal BMD was lower, but peak femoral BMD similar or higher (depending on the specific proximal femoral site measured) in black South-African females compared with whites. The lower peak spinal BMD was mainly attributed to lower BMD’s in the subgroup of black females with normal to low body weight, indicating that obesity either protected black females against a low spinal BMD or enhanced optimal attainment of bone mineral. An apparent slower rate of decline in both spinal- and femoral BMD with ageing was noted in the black females compared with whites in this cross-sectional study – an observation which will require confirmation in longitudinal, follow-up studies. This resulted in similar spinal BMD values in postmenopausal blacks and whites, but significantly higher femoral BMD measurements in blacks. The volumetric calculation of bone mineral apparent density (BMAD) at the lumbar spine and femoral neck yielded similar results to that of BMD. Spinal BMAD was similar in blacks and whites and femoral neck BMAD was consistently higher in all the menopausal subgroups studied. Weight significantly correlated with peak- and postmenopausal BMD at all sites in the black and white female cohorts. Greater and better maintained body weight may be partially responsible for slower rates of bone loss observed in black postmenopausal females. Most of the observed ethnic difference in BMD was, in fact, explained by differences in body weight between the two cohorts and not by ethnicity per se. 3. A low body weight and advanced age was identified as by far the most informative individual clinical risk factors for osteopenia in our black and white females, whereas physical inactivity was also identified as an important individual risk factor in blacks only. Risk assessment tools, developed and validated in Asian and European populations, demonstrated poor sensitivity for identification of South African women at increased risk of osteopenia. The osteoporosis risk assessment instrument (ORAI) showed the best results, with sensitivities to identify osteopenic whites at most skeletal sites approaching 80% (78% - 81%). The risk assessment tool scores appear to be inappropriate for our larger sized study cohort, especially our black subjects, thus resulting in incorrect risk stratification and poor test sensitivity. General discriminant analysis identified certain risk factor subsets for combined prediction of osteopenia in blacks and whites. These risk factor subsets were more sensitive to identify osteopenia in blacks at all skeletal sites, compared with the risk assessment tools described in the literature. 4. Higher ultrasonographically measured broadband ultrasound attenuation (BUA) and speed of sound (SOS) values were documented in our elderly blacks compared with whites, even after correction for differences in DEXA determined BMD at the spine and proximal femoral sites. BUA and SOS showed no decline with ageing in blacks, in contrast to an apparent significant deterioration in both parameters in ageing whites. If these quantitative ultrasound (QUS) parameters do measure qualitative properties of bone in our black population, independent of BMD as has been suggested in previous work in Caucasian populations, the higher values documented in elderly blacks imply better preservation of bone quality in ageing blacks compared with whites. The correlation between QUS calcaneal BMD and DEXA measured BMD at the hip and spine was modest at best. QUS calcaneal BMD was therefore unable to predict DEXA measured BMD at clinically important fracture sites in our study population. 5. Bone turnover, as assessed biochemically, was similar in the total pre- and postmenopausal black and white cohorts, but bone turnover rates appeared to differ with ageing between the two racial groups. A lower bone turnover rate was noted in blacks at the time of the menopausal transition and is consistent with the finding of a lower percentage bone loss at femoral sites at this time in blacks compared with whites. Bone turnover only increased in ageing postmenopausal blacks, and this could be ascribed, at least in part, to the observed negative calcium balance and the more pronounced secondary hyperparathyroidism noted in blacks. Deleterious effects of secondary hyperparathyroidism on bone mineral density at the proximal femoral sites were demonstrated in our postmenopausal blacks and contest the idea of an absolute skeletal resistance to the action of PTH in blacks. The increase in bone turnover and the presence of secondary hyperparathyroidism due to a negative calcium balance may thus potentially aggravate bone loss in ageing blacks, especially at proximal femoral sites. 6. Shorter, adult black women have a significantly shorter hip axis length (HAL) than whites. This geometric feature has been documented to protect against hip fracture. The approximately one standard deviation (SD) difference in HAL between our blacks and whites may therefore significantly contribute to the lower hip fracture rate previously reported in South African black females compared with whites. Average vertebral size was, however, smaller in black females and fail to explain the apparent lower vertebral fracture risk previously reported in this population. Racial differences in vertebral dimensions (height, width) and/or other qualitative bone properties as suggested by our QUS data may, however, account for different vertebral fracture rates in white and black women – that is, if such a difference in fact exists. 7. The number of women with a history of falls was similar in our black and white cohorts, and in both ethnic groups the risk of falling increased with age. There is a suggestion that the nature of falls in our black and white postmenopausal females may differ, but this will have to be confirmed in a larger study. Fallers in our postmenopausal study population were more likely to have osteoporosis than non-fallers. Postmenopausal blacks in our study demonstrated poorer outcomes regarding neuromuscular function, Vitamin D status and visual contrast testing and were shown to be more inactive with ageing compared with whites. An increased fall tendency amongst the black females could not however be documented in this small study. Quadriceps weakness and slower reaction time indicated an increased fall risk amongst whites, but were unable to distinguish black female fallers from non-fallers. 8. Vertebral fractures occurred in a similar percentage of postmenopausal blacks (11.5%) and whites (8.1%) in our study. Proximal femoral BMD best identified black and white vertebral fracture cases in this study. Quite a number of other risk factors i.e. physical inactivity, alcohol-intake, poorer physical performance test results and a longer HAL were more frequent in the white fracture cases and could therefore serve as markers of increased fracture risk, although not necessarily implicated in the pathophysiology of OP or falls. However, in blacks, only femoral BMD served as risk factor. Similar risk factors for blacks and whites cannot therefore be assumed and is deserving of further study. White fracture cases did not fall more despite lower 25-OH-Vitamin D, poorer physical performance and lower activity levels than non-fracture cases. Calcaneal ultrasonography and biochemical parameters of bone turnover were similar in fracture and non-fracture cases in both ethnic groups. Our study data on vertebral fractures in this cohort of urbanized blacks thus cautions against the belief that blacks are not at risk of sustaining vertebral compression fractures and emphasize the need for further studies to better define fracture prevalence in the different ethnic populations of South Africa. 9. In our study, hormone therapy in postmenopausal white women improved bone strength parameters and reduced fall risk. In hormone treated whites compared with non-hormone users, a higher BMD at the spine and proximal femur as determined by DEXA were documented and all QUS measurements were also significantly higher. The biochemically determined bone turnover rate, as reflected by serum osteocalcin levels, was lower in hormone users. Fall frequency was lower in the older hormone treated women (≥ 60yrs) and greater quadriceps strength and reduced lateral sway was noted. Only one patient amongst the hormone users (2%) had radiological evidence of vertebral fractures compared with four patients (6%) amongst the never-users. As hormone therapy was used almost exclusively by whites in this study population, the impact of hormone therapy on postmenopausal black study subjects could not be assessed.

published_or_final_version / Community Medicine / Doctoral / Doctor of Philosophy

A large percentage of oil and gas reservoirs in the most productive regions such as the Middle East, South America, and Southeast Asia are naturally fractured reservoirs (NFR). The major difference between conventional reservoirs and naturally fractured reservoirs is the discontinuity in media in fractured reservoir due to tectonic activities. These discontinuities cause remarkable difficulties in describing the petrophysical structures and the flow of fluids in the fractured reservoirs. Predicting fluid flow behavior in naturally fractured reservoirs is a challenging area in petroleum engineering. Two classes of models used to describe flow and transport phenomena in fracture reservoirs are discrete and continuum (i.e. dual porosity) models. The discrete model is appealing from a modeling point of view, but the huge computational demand and burden of porting the fractures into the computational grid are its shortcomings. The affect of natural fractures on the permeability anisotropy can be determined by considering distribution and orientation of fractures. Representative fracture permeability, which is a crucial step in the reservoir simulation study, must be calculated based on fracture characteristics. The diagonal representation of permeability, which is customarily used in a dual porosity model, is valid only for the cases where fractures are parallel to one of the principal axes. This assumption cannot adequately describe flow characteristics where there is variation in fracture spacing, length, and orientation. To overcome this shortcoming, the principle of the full permeability tensor in the discrete fracture network can be incorporated into the dual porosity model. Hence, the dual porosity model can retain the real fracture system characteristics. This study was designed to develop a novel approach to integrate dual porosity model and full permeability tensor representation in fractures. A fully implicit, parallel, compositional chemical dual porosity simulator for modeling naturally fractured reservoirs has been developed. The model is capable of simulating large-scale chemical flooding processes. Accurate representation of the fluid exchange between the matrix and fracture and precise representation of the fracture system as an equivalent porous media are the key parameters in utilizing of dual porosity models. The matrix blocks are discretized into both rectangular rings and vertical layers to offer a better resolution of transient flow. The developed model was successfully verified against a chemical flooding simulator called UTCHEM. Results show excellent agreements for a variety of flooding processes. The developed dual porosity model has further been improved by implementing a full permeability tensor representation of fractures. The full permeability feature in the fracture system of a dual porosity model adequately captures the system directionality and heterogeneity. At the same time, the powerful dual porosity concept is inherited. The implementation has been verified by studying water and chemical flooding in cylindrical and spherical reservoirs. It has also been verified against ECLIPSE and FracMan commercial simulators. This study leads to a conclusion that the full permeability tensor representation is essential to accurately simulate fluid flow in heterogeneous and anisotropic fracture systems. / text

Le premier but de cette thèse est de développer une méthode objective pour l'interprétation de profils sismiques et des structures qui sont susceptibles d'être des réservoirs pétroliers. Le deuxième but est l'amélioration de la prévision des fractures dans les roches laminées, qui déterminent la perméabilité. Les expériences et les résultats analytiques montrent l'initiation, l'évolution et l'arrêt d'un kink et d'un pli de propagation de rampe (PPR). Les expériences avec paraffine multicouches établissent la relation entre la distribution des fractures, la formation des charnières endommagées et l'évolution d'un pli de kink. Les résultats analytiques se fondent sur des règles géométriques combinées à l'approche externe de l'analyse limite. Les bandes de compaction, les failles et les plis sont en concurrence à l'initiation du kink. Le mode dominant dépend de l'inclinaison des couches et de la profondeur d'enfouissement de la structure. Les résultats sont présentés dans une carte de mécanismes dominant dans l'espace des enfouissements et l'inclinaison des couches. La même approche est utilisée pour étudier le PPR dont l' évolution se termine à cause de l'initiation d'une faille. Parmi tous les paramètres, c'est l'angle de friction dans les charnières qui contrôle cette transition. La deuxième partie de cette thèse présente les résultats expérimentaux, numériques et analytiques sur les fractures. Une couche composée de gypse compacté, est en extension par sa base et se fracture en mode I. La relation entre la distance entre les fractures et l'épaisseur d'une couche est linéaire, quand la structure est saturée en fractures. Cette saturation est liée à un décollement de la base de la couche. La méthode des éléments finis et la théorie de la plasticité permettent de valider ces résultats. L'approche analytique (analyse limite) a donné un critère simple pour prédire si un décollement ou une fracture va se former. Un nouveau critère pour la distance entre deux fractures est proposé. Dans la dernière partie de cette thèse, un nouveau dispositif expérimental est présenté afin d'étudier les fractures en flexion. L'épaisseur d'une couche n'influence pas la distance entre les fractures si il y a seulement une flexure. Cette influence est par contre grande si la couche est cintrée et en extension.

Saab Microwave Systems, SMW is a supplier of radar systems. The circuit boards that are operating in their radars have components which solder joints contains lead. However, the EU directive RoHs and WEEE are causing SMW to prepare for a transition to lead free solder joints. The objective of this thesis is to gain deeper knowledge of lead free solder joints. Brittle fractures in solder joints is a type of failure that might increase in a transition to lead free solder joints. The brittle fractures are induced by the creation of the intermetallic phases which are formed during soldering. The amount and composition of the intermetallics affects the mechanical strength of the joint. An intermetallic layer is thickened during heat exposure as during soldering, thermal aging and rework. The focus of this thesis was to investigate how rework affect the brittleness of the lead free solder joint and thereby how the intermetallic layers change depending on chemical composition, design and reflow cycles. Two types of components and two types of solder materials (SnPb and SAC305) were studied. To study the mechanical properties of the joint a shear testing device was used. This is a way of measuring the reliability of the joint when subjected to mechanical shock. The intermetallic layers were examined in a Scanning Electron Microscope and the fracture surfaces were studied in a optical microscope, a scanning electron microscope and a stereomicroscope. The heat spread over the board where examined by soldering thermocouples to the board and plotting the values of time and temperature. The results showed that the rework process did not have any significant impact of the intermetallic growth. The adjecent and distant components were not damaged during rework. A lead free rework process can therefor be preformed successfully at SMW. The intermetallic layers formed at the interface between the a lead free solder and a nickel finish grew faster than an intermetallic layer formed between a leaded solder and a nickel finish. The presence of nickel could therefore have a more negative effect on the intermetallic growth rate for the lead free material compared to the leaded.

Bakgrund: Kunskapen om barnmisshandel hos vårdpersonal har börjat kritiseras i Sverige. Röntgensjuksköterskan är skyldig att rapportera vid misstänkt barnmisshandel och behöver därför kunna identifiera dessa fall. Syfte: Syftet var att beskriva radiologiska fynd som kan indikera barnmisshandel. Metod: Studierna i denna litteraturstudie kvalitetsgranskades, analyserades och bearbetades för att sammanställa ett resultat. Tio kvantitativa studier ingick i resultatet för litteraturstudien. PubMed och CINAHL användes som sökdatabaser. Resultat: Resultatet presenterades i tre kategorier: hjärnskador och blödningar, frakturer och ligamentskador. Konklusion: Vanliga radiologiska fynd som kan indikera barnmisshandel är subduralblödningar, revbensfrakturer och rörbensfrakturer. Vidare forskning bör utföras för att undersöka prevalensen av frakturer i händer och fötter samt ligamentskador i halsryggen vid misstänkt barnmisshandel. / Background: Swedish health care professionals’ knowledge about child abuse has lately been criticized. The radiographer is obligated to report on suspected child abuse and therefore needs to be able to identify these cases. Aim: The aim was to describe radiological findings that might indicate child abuse. Method: The studies in this literature review were quality assessed, analyzed and processed to compile the results. The results consisted of ten quantitative studies. PubMed and CINAHL were used as search databases. Results: The results were presented in three categories: brain injuries and hemorrhages, fractures and ligamentous injuries. Conclusion: Common radiological findings that might indicate child abuse are subdural hemorrhages, rib fractures and long bone fractures. Continued research should be conducted to investigate the prevalence of fractures in hands and feet, and also ligamentous injuries of the cervical spine in suspected child abuse.

Student Number: 0420801P Master of Science in Engineering. Faculty of Engineering and the Built Environment / Underground observations at a coal mine indicated failure of the immediate roof above the bords while pillars were observed to be intact. To determine the underlying causes of roof failures, careful observations and photographic recording of occurrences of roof failures have been made. Rock samples of the immediate shale roof were collected for laboratory testing to determine the rock strength and deformation properties. Numerical simulations were carried out to analyse stress and strain distributions and also to attempt to explain the guttering process. Mapping of roof failures showed that these took place mainly towards the centre of the roadways. The roof failures, termed “roof guttering”, were observed to occur violently and with little warning. Occurrence of roof guttering had a negative impact on production. Some panels are abandoned, production times have increased and safety of workers is compromised. The mine authorities initially thought that roof guttering was caused by shear failure of the rock mass. Roof bolts are therefore used as a means of primary support. No improvements have been observed. Increasing the size of pillars has not solved the problem either. It has only increased the amount of coal left in the pillars without any improvements in reducing roof failures. Stress measurement results carried out in 2001 showed that high horizontal stresses exist at the mine. The immediate shale roof was observed to be weak. Laboratory testing showed that the shale rock is transversely isotropic. Numerical modelling results indicated that there are insignificant stress concentrations towards the centre of the roadway using the elastic and transversely isotropic elastic models. Stress concentrations were predicted at the roof-pillar contact area. It is therefore expected that failure should initiate and occur at the roof-pillar contact area. The Mohr-Coulomb and Mohr-Coulomb strain softening models predicted shear failure at the roof-pillar contact area. The two models over predicted the depth and under predicted the width of failures. The extension strain criterion predicted correctly the depth and width of failures although the failures were predicted at the roof-pillar contact area while the observations indicated failure mainly towards the centre of the roads. Initiation of failure was predicted ahead of the coal face at the centre of the road position using the extension strain criterion. Although none of the constitutive behaviours predicted correctly the observed underground failures the extension strain criterion has shown the best agreement. Guttering that occurred at the roof-pillar contact was modelled successfully using the extension strain criterion. The extension strain criterion predicted initiation of failure ahead of the coal face at the road centre position. It is possible that fracture initiation could be taking place in this location ahead of the coal face, and, on blasting the rock that has been fractured falls forming a gutter at the centre of the road.

Les lasers femtosecondes sont un outil efficace pour induire des modifications structurelles localisées en volume dans les matériaux diélectriques. Initialement transparents, les diélectriques ne commencent à absorber efficacement l’énergie laser que lorsque l’intensité excède le seuil de claquage optique du matériau. Cette propriété, couplée à une durée d’impulsion femtoseconde plus courte que les temps caractéristiques de relaxation de la matière, permet d’obtenir un dépôt d’énergie précis et localisé dans le volume irradié. Pour modéliser la formation de telles structures, un modèle thermo-élasto-plastique en géométrie 2D planaire, incluant la transition solide-liquide via un modèle de ramollissement, a été implémenté dans un code hydrodynamique lagrangien. Des études de la formation d’une cavité et de l’interaction de multiple cavités ont tout d’abord été réalisées en supposant un dépôt instantané d’énergie laser dans le volume d’une cible de silice fondue. La relaxation de la matière chauffée, portée à l’état de plasma dense, induit alors la propagation d’ondes de choc dans le solide froid environnant. Des déformations permanentes peuvent apparaître dans le matériau si la contrainte, induite par ces ondes, excède la limite élastique. Ces premières études ont notamment permis de comprendre et de décrire les différentes étapes de la formation de micro-structures, fortement corrélées au comportement élasto-plastique du solide environnante. De plus, en utilisant une loi de Weibull, tenant compte de la densité de défauts dans la matière, des probabilités de fractures dans le matériau ont été calculées. Dans un second temps, la structuration de la silice fondue par un faisceau de Bessel a été considérée. Un solveur de Maxwell 3D, couplé à une description fluide de la dynamique électronique, a été utilisé pour modéliser le dépôt d’énergie laser. Les résultats ont permis de comprendre comment s’établit le dépôt d’énergie et rendent compte des effets des différents processus d’ionisation sur les évolutions des profils de densité et d’énergie électronique. Des simulations thermo-élasto-plastiques ont ensuite étaient réalisées en utilisant le dépôt d’énergie calculé. Différents types de déformations induites dans la silice ont pu être mis en évidence en fonction de l’énergie et de la durée de l’impulsion incidente, en accord avec les observations expérimentales. / Femtosecond laser pulses are an efficient tool to induce localized structural modifications in the bulk of dielectrics materials. The dielectrics, initially transparent, start to efficiently absorb the energy when the laser intensity exceeds the optical breakdown threshold of the material. This property, coupled to a femtosecond pulse duration smaller than the caracteristic relaxation times of matter, allows to induce a localized and accurate energy deposition in the irradiated volume. In order to model the formation of such structures, a 2D thermo-elasto-plastic model, including solid-liquid transitions through a softening model, has been implemented in a lagrangian hydrodynamic code. Studies on the formation of a single cavity and several interacting cavities have been firstly performed, assuming an instantaneous energy deposition in the bulk of fused silica. The relaxation of the heated matter, transformed to a warm dense plasma, induces shock waves in the surrounding cold solid. Permanent deformations may appear if the stress, induced by the waves, exceeds the yield strength of the material. This first study allowed to understand and describe the various steps of the micro-structures formation, which are strongly correlated to the elasto-plastic behavior of the surrounding solid. Furthermore, by using a Weibull’s law, accounting for defects density in the material, cracks probabilities have been predicted. Secondly, the structuration of fused silica by a Bessel beam has been considered. For that purpose, a 3D Maxwell solver coupled to a fluid description of the electron dynamics has been used to model the laser energy deposition. Results allow to understand how the energy deposition establishes and show the effects of the different ionization processes on the electron density and energy profiles. Then, thermo-elasto-plastic simulations have been carried out including the calculated energy deposition. Various kinds of induced deformations in fused silica have been obtained depending on the incident pulse energy and duration, which is in agreement with experimental observations.