Johan van der Merwe
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View article: Evaluation of the Haemodynamic Behaviour of Stenosed Aortic Heart Valves Using Fuid Structure Interaction Modelling
Evaluation of the Haemodynamic Behaviour of Stenosed Aortic Heart Valves Using Fuid Structure Interaction Modelling Open
Aortic stenosis is a valvular heart disease characterised by the narrowing of the valve opening area. Calcific and rheumatic aortic stenosis (AS) have distinctly different valve morphologies. The haemodynamic environment of generic calcifi…
View article: A method for determining machine configurations for multidirectional pin-on-plate wear testing
A method for determining machine configurations for multidirectional pin-on-plate wear testing Open
Pin-on-plate wear testing is a commonly employed technique for preclinical evaluation of the wear performance of articulating joint implant materials, as specified by ASTM F732. The latest revision of ASTM F732, introduced multidirectional…
View article: Knee arthrodesis using biplanar external fixation and vascularised patella autograft: a novel approach
Knee arthrodesis using biplanar external fixation and vascularised patella autograft: a novel approach Open
BACKGROUND: Knee arthrodesis, though a rare procedure in current practice, remains an option in managing non-reconstructable, non-functional knees, especially if from persistent periprosthetic joint infection (PJI). It is even more of an o…
View article: Linear and Non-Linear Regression Methods for the Prediction of Lower Facial Measurements from Upper Facial Measurements
Linear and Non-Linear Regression Methods for the Prediction of Lower Facial Measurements from Upper Facial Measurements Open
Accurate assessment and prediction of mandible shape are fundamental prerequisites for successful orthognathic surgery. Previous studies have predominantly used linear models to predict lower facial structures from facial landmarks or meas…
View article: A method for determining machine configurations for multidirectional pin-on-plate wear testing
A method for determining machine configurations for multidirectional pin-on-plate wear testing Open
Pin-on-plate wear testing is a commonly employed technique for preclinical evaluation of the wear performance of articulating joint implant materials, as specified by ASTM F732. The latest revision of ASTM F732, introduced multidirectional…
View article: The Influence that the Complexity of the Three-Dimensional Eye Model Used to Generate Simulated Eye-tracking Data Has on the Gaze Estimation Errors Achieved Using the Data
The Influence that the Complexity of the Three-Dimensional Eye Model Used to Generate Simulated Eye-tracking Data Has on the Gaze Estimation Errors Achieved Using the Data Open
Simulated eye-tracking data are an integral tool in the development of eye-tracking methods. Most of the simulated data used in eye-tracking-related research has been generated using low-complexity eye models that include a single spherica…
View article: Evaluation of Aortic Valve Pressure Gradients for Increasing Severities of Rheumatic and Calcific Stenosis Using Empirical and Numerical Approaches
Evaluation of Aortic Valve Pressure Gradients for Increasing Severities of Rheumatic and Calcific Stenosis Using Empirical and Numerical Approaches Open
The evaluation and accurate diagnosis of the type and severity of aortic stenosis relies on the precision of medical imaging technology and clinical correlations and the expertise of medical professionals. The application of the clinical c…
View article: Minimally Invasive Pectus Excavatum Correction and Endoscopic Port Access Mitral Valve Surgery
Minimally Invasive Pectus Excavatum Correction and Endoscopic Port Access Mitral Valve Surgery Open
This case study describes the successful short-term outcome of staged minimally invasive pectus excavatum correction and endoscopic mitral valve repair in a patient with severe mitral valve regurgitation and pectus excavatum.
View article: Wear characterisation of additively manufactured Ti6Al4V for patient-specific joint implant applications
Wear characterisation of additively manufactured Ti6Al4V for patient-specific joint implant applications Open
This study uses multidirectional pin-on-plate wear testing to present a pre-clinical wear assessment of additively manufactured (AM) Ti6Al4V with ASTM F732 guided testing conditions. Wear assessment of moderately cross-linked polyethylene …
View article: A Method for Determining Machine Configurations for Multidirectional Pin-on-Plate Wear Testing
A Method for Determining Machine Configurations for Multidirectional Pin-on-Plate Wear Testing Open
View article: Oxygen Boost Diffusion of Additively Manufactured Ti-6al-4v for Improved Oxide Layer Adhesion
Oxygen Boost Diffusion of Additively Manufactured Ti-6al-4v for Improved Oxide Layer Adhesion Open
View article: A Method for Determining Machine Configurations for Multidirectional Pin-on-Plate Wear Testing
A Method for Determining Machine Configurations for Multidirectional Pin-on-Plate Wear Testing Open
View article: A comprehensive roadmap to minimally invasive coronary artery surgery
A comprehensive roadmap to minimally invasive coronary artery surgery Open
A comprehensive roadmap to minimally invasive coronary artery surgeryWe are currently witnessing exciting developments in percutaneous coronary intervention and minimally invasive surgical coronary artery revascularization technology and i…
View article: The influence of eye model parameter variations on simulated eye-tracking outcomes
The influence of eye model parameter variations on simulated eye-tracking outcomes Open
The simulated data used in eye-tracking-related research has been largely generated using normative eye models with little consideration of how the variations in eye biometry found in the population may influence eye-tracking outcomes. Thi…
View article: Circumflex Coronary Artery Injury during Modern Mitral Valve Surgery—A Review of Current Concepts and Perspectives
Circumflex Coronary Artery Injury during Modern Mitral Valve Surgery—A Review of Current Concepts and Perspectives Open
The devastating impact of a circumflex coronary artery (CX) injury during mitral valve (MV) surgery is well reported. Despite significant improvements in preoperative risk assessment, intraoperative diagnosis and perioperative treatment st…
View article: Minimally invasive surgical coronary artery revascularization—how to initiate a safe and sustainable program
Minimally invasive surgical coronary artery revascularization—how to initiate a safe and sustainable program Open
The recent reconfirmation of coronary artery bypass grafting (CABG) superiority over current percutaneous coronary interventions (PCIs) in various clinical scenarios resulted in renewed interest in less invasive surgical coronary artery re…
View article: Minimally invasive surgical coronary artery revascularization—current status and future perspectives in an era of interventional advances
Minimally invasive surgical coronary artery revascularization—current status and future perspectives in an era of interventional advances Open
We are currently witnessing rapid advances in coronary artery disease (CAD) diagnostic-and treatment technology, which include exciting developments in the utilisation of artificial intelligence, stem cell and genetic therapy and pharmacol…
View article: Estimation of Pulmonary Arterial Pressure Using Simulated Non-Invasive Measurements and Gradient-Based Optimization Techniques
Estimation of Pulmonary Arterial Pressure Using Simulated Non-Invasive Measurements and Gradient-Based Optimization Techniques Open
Reliable quantification of pulmonary arterial pressure is essential in the diagnostic and prognostic assessment of a range of cardiovascular pathologies, including rheumatic heart disease, yet an accurate and routinely available method for…
View article: Inference of Pulmonary Arterial Pressure using Non-invasive Measurements and Scientific Machine Learning Techniques
Inference of Pulmonary Arterial Pressure using Non-invasive Measurements and Scientific Machine Learning Techniques Open
Reliable quantification of pulmonary arterial pressure is essential in the diagnostic and prognostic assessment of a range of cardiovascular pathologies including rheumatic heart disease, yet an accurate and routinely available method for …
View article: Non-invasive estimation of left ventricle elastance using a multi-compartment lumped parameter model and gradient-based optimization with forward-mode automatic differentiation
Non-invasive estimation of left ventricle elastance using a multi-compartment lumped parameter model and gradient-based optimization with forward-mode automatic differentiation Open
Accurate estimates of left ventricle elastances based on non-invasive measurements are required for clinical decision-making during treatment of valvular diseases. The present study proposes a parameter discovery approach based on a lumped…
View article: Yesterday, today, and tomorrow
Yesterday, today, and tomorrow Open
Rev. Dr Andrew Murray Jr became a well-known theologian in the history of South Africa. He wrote many books and played a founding role in establishing the Huguenot College in Wellington in the Cape Colony. A lesser-known fact is the import…
View article: Truth or DAIR? A review of debridement, antibiotics and implant retention
Truth or DAIR? A review of debridement, antibiotics and implant retention Open
Debridement, antibiotics and implant retention (DAIR) is a viable treatment option in early postoperative and acute haematogenous periprosthetic joint infections (PJIs) with a stable implant. Despite lower success rates compared to one- an…
View article: The Rustenburg Church Conference of 1990: A call to the churches in South Africa after 30 years
The Rustenburg Church Conference of 1990: A call to the churches in South Africa after 30 years Open
The Rustenburg Church Conference took place in 1990, 30 years after the historic Cottesloe
\nChurch Consultation of 1960. Both these conferences had a huge influence on the history of
\nthe churches in South Africa. Thirty years after the …
View article: Armoede : ’n Uitdaging aan die Afrikaanse gereformeerde kerke (1994–2019)
Armoede : ’n Uitdaging aan die Afrikaanse gereformeerde kerke (1994–2019) Open
This contribution gives an overview of how four of the important reformed churches
\nin South Africa responded to the challenge of poverty from 1994 to 2019. Following
\nan introduction, the first part of the chapter defines poverty and de…
View article: Armoede
Armoede Open
Poverty: A challenge for the Afrikaans reformed churches, 1994-2019This contribution gives an overview of how four of the important reformed churches in South Africa responded to the challenge of poverty from 1994 to 2019. Following an int…
View article: PARAMETRIC MANDIBLE RECONSTRUCTION PLATE
PARAMETRIC MANDIBLE RECONSTRUCTION PLATE Open
CITATION: Giddy, B. & Van der Merwe, J. 2020. Parametric mandible reconstruction plate. South African Journal of Industrial Engineering, 31(3):253-261, doi:10.7166/31-3-2444.
View article: Effect of including canola meal in diets of slaughter ostriches (Struthio camelus var. domesticus)
Effect of including canola meal in diets of slaughter ostriches (Struthio camelus var. domesticus) Open
Canola meal (CM) is a locally produced protein source that may be less expensive than soybean meal (SBM). This study evaluated the effects of replacing 0%, 25%, 50%, 75%, and 100% SBM with CM in diets for slaughter ostriches. The CM was ad…
View article: A roadmap for valve repair surgery
A roadmap for valve repair surgery Open
It is well established that mitral valve repair has better outcomes than mitral valve replacement surgery. In the Western world, degenerative mitral valve pathology leading to severe mitral valve regurgitation is the most frequent disease …
View article: Minimally invasive atrioventricular valve surgery – current status and future perspectives
Minimally invasive atrioventricular valve surgery – current status and future perspectives Open
We are currently witnessing rapid evolution in minimally invasive and catheter-based atrioventricular valve interventions as acceptable alternatives to classic sternotomy access (CSA). Collectively, minimally invasive atrioventricular valv…
View article: Effect of varying levels of protein concentration on production traits of ostriches (<i>Struthio camelus</i> var. <i>domesticus</i>)
Effect of varying levels of protein concentration on production traits of ostriches (<i>Struthio camelus</i> var. <i>domesticus</i>) Open
The ostrich industry is poised to recover from the recent lifting of the four-year export ban on fresh meat products to the European Union EU). However, during this period profit margins were severely affected and the need to minimize inpu…