Effect of aging and degeneration on the human intervertebral disc during the diurnal cycle: A finite element study

Alterations in the major biochemical constituents of intervertebral discs coincide with aging and degeneration, and can alter the disc's ability to support load. The most significant biochemical change that occurs in degeneration is the loss of proteoglycans in the nucleus pulposus. During a diurnal cycle, the disc experiences approximately 16 hours of functional loading, followed by 8 hours of recovery. An axisymmetric, poroelastic model was created using ABAQUS finite element software. Standard poroelastic theory is utilized, but a user-defined material was written to include the effects of osmotic swelling, which is directly related to proteoglycan content. Due to the high stresses in the nucleus, the annulus fibrosus must remodel itself to account for the change in properties of the nucleus. The stress experienced by the nucleus increases greatly in Grade 2 from Grade 1, but then decreases in Grade 3, and even Grade 4 experiences lower stresses than in Grade 2. The osmotic pressure in the central nucleus decreases approximately 75% with degeneration. This explains the increasing inability of Grades 3 through 5 to recover the fluid lost during loading, since the osmotic pressure gradient is the primary mechanism with which fluid flows back into the disc

Evaluation of Sliding Identation, an Innovative Loading Regime for Cartilage Tissue Engineering

Abstract only

'Bodily': Conjunction and Fermentation

'This cult of thinness has burrowed its way into my body. Into our bodies. It’s a way of life. The head knows we shouldn’t, but the heart has no choice . . . This is our contradiction'. This paper looks at the “before, during and after” of my 2006 Ph.D. performance 'Bodily', which explores the multiplicity of attitudes towards female beauty and body image in contemporary society. It traces the development of the performance, the experience during the show, and a discussion and evaluation of the receptions to the performance and its research outcomes. The focus of this paper is on how the theory and practice components of my project complement each other, emphasising the line of development from research and construction to performance and evaluation. It therefore investigates how I am integrating the experience of 'Bodily' with my theoretical research.The conference was sponsored by A.D.S.A., the Department of Performance Studies, the School of Letters, Arts and Media, and the Faculty of Arts of the University of Sydney

Improving The Urban Public Transport In Developing Countries: The Design Of A New Integrated System In Santiago De Chile

Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne

No one knows which city has the highest concentration of fine particulate matter

This is the final version. Available from the publisher via the DOI in this record.Exposure to ambient fine particulate matter (PM2.5) is the leading global environmental risk factor for mortality and disease burden, with associated annual global welfare costs of trillions of dollars. Examined within is the ability of current data to answer a basic question about PM2.5, namely the location of the city with the highest PM2.5 concentration. The ability to answer this basic question serves as an indicator of scientific progress to assess global human exposure to air pollution and as an important component of efforts to reduce its impacts. Despite the importance of PM2.5, we find that insufficient monitoring data exist to answer this basic question about the spatial pattern of PM2.5 at the global scale. Only 24 of 234 countries have more than 3 monitors per million inhabitants, while density is an order of magnitude lower in the vast majority of the world's countries, with 141 having no regular PM2.5 monitoring at all. The global mean population distance to nearest PM2.5 monitor is 220 km, too large for exposure assessment. Efforts to fill in monitoring gaps with estimates from satellite remote sensing, chemical transport modeling, and statistical models have biases at individual monitor locations that can exceed 50 μg m−3. Progress in advancing knowledge about the global distribution of PM2.5 will require a harmonized network that integrates different types of monitoring equipment (regulatory networks, low-cost monitors, satellite remote sensing, and research-grade instrumentation) with atmospheric and statistical models. Realization of such an integrated framework will facilitate accurate identification of the location of the city with the highest PM2.5 concentration and play a key role in tracking the progress of efforts to reduce the global impacts of air pollution.Natural Sciences and Engineering Research Council of CanadaDepartment of Biotechnology on ‘Air Pollution and Human Health

Depth-Dependent Compressive Equilibrium Properties of Articular Cartilage Explained by Its Composition,” Biomech.

Abstract For this study, we hypothesized that the depthdependent compressive equilibrium properties of articular cartilage are the inherent consequence of its depth-dependent composition, and not the result of depth-dependent material properties. To test this hypothesis, our recently developed fibril-reinforced poroviscoelastic swelling model was expanded to include the influence of intra-and extra-fibrillar water content, and the influence of the solid fraction on the compressive properties of the tissue. With this model, the depth-dependent compressive equilibrium properties of articular cartilage were determined, and compared with experimental data from the literature. The typical depth-dependent behavior of articular cartilage was predicted by this model. The effective aggregate modulus was highly strain-dependent. It decreased with increasing strain for low strains, and increases with increasing strain for high strains. This effect was more pronounced with increasing distance from the articular surface. The main insight from this study is that the depth-dependent material behavior of articular cartilage can be obtained from its depth-dependent composition only. This eliminates the need for the assumption that the material properties of the different constituents themselves vary with depth. Such insights are important for understanding cartilage mechanical behavior, cartilage damage mechanisms and tissue engineering studies

Pseudo-wound infection after a caesarean section:Case report of unrecognized Pyoderma Gangrenosum

Background: Pyoderma Gangrenosum (PG) is a rare auto-inflammatory disease, characterized by painful ulcerative skin-lesions often developing at sites of injury or surgery because of the typical pathergy phenomena. We describe an unusual case of PG after a caesarean section with excessive extra-cutaneous manifestation within internal organs. Presentation of case: A 21-year-old Dutch primigravida developed signs of sepsis after a caesarean section. Despite antibiotic treatment, fast clinical deterioration occurred. Exploration of the wound showed necrosis of the uterus and surrounding tissues. Due to the progression of necrosis, consecutive debridement procedures were executed resulting in a substantial abdominal wall defect. The progressive clinical course of the necrosis combined with absence of positive wound cultures and histology of prominent interstitial neutrophilic infiltration, led to the diagnosis ‘Pyoderma Gangrenosum’. Treatment with high dose corticosteroids led to rapid regression of the disease. After several weeks, the abdominal wall defect was surgically corrected under systemic corticosteroid therapy. Discussion: This case of PG is unique due to the excessive extra-cutaneous presentation, which contributed to delayed diagnosis. Several surgical interventions in the active stage of disease resulted in expansion of PG and substantial morbidity for the patient. Conclusion: Post-operative PG can mimic infectious diseases, but treatment is substantially different. This case of extensive PG highlights the importance of timely recognition and treatment of the disease to reduce iatrogenic morbidity