Dr. Xi-Qiao FENG is a Chang Jiang Chair Professor and Head of the Department of Engineering Mechanics at Tsinghua University. He earned his B.Sc. (1990), M.Sc. (1991) and Ph.D. (1995) degrees in Solids Mechanics from Tsinghua University at Beijing. From September 1997 to May 1999, he was awarded the Alexander von Humboldt of Germany and worked at the Technical University of Darmstadt and Delft University of Technology. He rejoined Tsinghua University as an associate Professor in 1999 and was promoted to a full professor in 2001. Selected Feng’s honors include: Award of Science and Technology for Young Scientists of China (2007), Distinguished Young Scholars Award of NSFC (2005), Young Scientist Award of Fok Ying Tong Education Foundation (2004), Award for Best Doctoral Theses of China (1999). Currently, he is the Secretary-General of the Chinese Society of Theoretical and Applied Mechanics (CSTAM) and Director of the Institute of Biomechanics and Medical Engineering (IBME). He also serves as a member of the editorial board of more than 10 international journals, such as Applied Physics Letters, Journal of Applied Physics, Molecular and Cellular Biomechanics, Engineering Fracture Mechanics, and Archive of Applied Mechanics. Professor Feng’s current interests include: molecular and cellular biomechanics, mechanics of biomaterials, damage and fracture mechanics. He has authored and co-authored two books and more than 200 journal papers.
Surface wrinkling of soft biological tissue
Surface instability and morphological evolution of such soft materials as hydrogels and biological tissues is a major concern in a wide diversity of fields. In this talk, surface instability of soft materials and biological tissues are discussed within the framework of continuum mechanics. Firstly, a generic method is presented for analyzing the surface stability of a thin film resting on a substrate with arbitrary geometry. Secondly, the growth and buckling of mucosas that commonly line organs and cavities throughout the animal body are analyzed theoretically, numerically and experimentally. Finally, the surface wrinkling of soft core-shell matters induced by swelling or shrinking is investigated. The results demonstrate that the evolution of the sphere may be characterized by a process of smooth surface, buckyball-like wrinkling pattern, and then undergoing a wrinkling-to-fold transition into labyrinth-like folded patterns, in agreement with our experimental observations.
Xiaoyu Luo is a Professor in the School of Mathematics and Statistics at the University of Glasgow. She received her BSc (1982) in Solid Mechanics, MSc (1985) in Applied Mechanics, and (1990) PhD in Bio-fluid Mechanics from the Xi'an Jiaotong University (XJTU), China. She was a lecturer/associate professor at XJTU until 1992, when she moved to the UK to work with Professor TJ Pedley, FRS, on modelling fluid flows in collapsible tubes. She was appointed as a lecturer at the Queen Mary and Westfield College in 1997, and then a lecturer/SL at the University of Sheffield from 2000-2005. She joined the University of Glasgow in 2005, and was promoted to full professor in 2008. Her current research interests include modelling and numerical simulations of soft tissue mechanics, bio-fluids and fluid-structure interaction, with particular applications to heart, heart valves, biliary system, and arteries. Xiaoyu has published over 60 peer-reviewed journal papers and book chapters, one of these was voted the ''Best Paper'' of IJAM in 2009, and one won the top prize of best overall paper at UKISCRS meeting in 2011. She supervised 17 PhD students and 10 post-doctoral Research Associates, and secured over 30 research grants, including 7 from the UK Engineering and Physics Sciences Research Council (EPSRC) and a Global Research Award from the Royal Academy of Engineering. Xiaoyu is a Fellow of the Institution of Mechanical Engineers, a member of the EPSRC College, and is on the editorial boards of three international journals
Soft tissue mechanics and fluid-structure interaction
Soft tissue mechanics and fluid-structure interaction are among the most challenging issues in modelling and simulation of physiological systems. This is because one needs to solve momentum equations for the biofluid and soft tissues in two different coordinate systems. In addition, soft tissues present multi-physics, anisotropic and fibre-reinforced constitutive behaviours, and often undergo finite strain, nonlinear and dynamic deformation under physiological and pathological conditions. In this talk, I shall select a few applications involving soft tissue mechanics and fluid-structure interaction that are studied by the Glasgow group. These range from human gallbladder pain, arteries and dissection, mitral valves and multi-scale heart modelling, and are studied using various numerical methods, including the finite element method, the immersed boundary method, and a hybrid immersed-boundary finite-element method, as well as analytical approaches. Material parameters may be estimated based on patient-specific information and experimental data, and numerical simulations provide physical insights into complex physiological systems.
Professor Marie Oshima finished her Ph.D program in the Department of Nuclear Engineering at the University of Tokyo in March 1992. She becamse Professor in 2005 at the University of Tokyo, and became Joint Professor at the Interfaculty Initiative in Information Studies and Institute of Industrial Science, the University of Tokyo. She has been engaged in computational hemodynamics, particularly medical-image based modeling and cerebrovasculr flow simulation for medical applications. Her research includes development of multi-scale and multi-physics models for hemodynamic simulations and blood flow-arterial wall interactions. She has been also working on flow visualization and measurements using PIV (Particle Image Velocimetry) technique for blood flow related problems and micro PIV measurement of flow in a micro scale.
Numerical investigation of cerebrovascular circulation after carotid artery stenting
When atherosclerosis progresses and carotid artery stenosis becomes severe, carotid stenting is performed. After stenting, sometimes cerebral hyperperfusion syndrome is caused. Therefore, it is important to examine the changes in the flow distributions in the cerebrovascular circulation. The purpose of the paper is to develop a numerical method for one-dimensional (1D) and zero-dimensional (0D) simulations to predict the flow distribution in the cerebrovascular circulation after carotid stenting by considering the entire circulation. The general circulation is modeled such that the large arteries are modeled in 1D and the remaining parts, like the peripheral arteries, vein and heart are modeled in 0D. The 1-D simulation is conducted for the patient-specific geometry of the arterial circle of Willis combined with 1D-0D simulation of the general circulatory system. The present method is applied to the pre- and post-operative medical images of the patient, who had carotid stenting. Results such as flow rate and the pressure distributions are compared between pre- and post- operation and the effects of the 1D-0D simulation are investigated.
Prof. Zhong-can Ou-Yang, a theoretical physicist, was born on Jan. 25, 1946, in Quanzhou, Fujian Province of China. He received his Ph.D. in Tsinghua University, in 1984, and worked the next two years in the Institute of Theoretical Physics, Chinese Academy of Sciences (ITP-CAS) as postdoctoral fellow. From 1987 to 1988 he worked with Prof. W. Helfrich at FU Berlin as an Alexander von Humboldt Foundation fellow. In 1989 he joined ITP-CAS, first as an associated professor and then (1992) as a full professor. He has been serving as the Director of the institute from 1998 to 2007. He has made distinguished contributions to a number of theoretical subjects in soft condensed matter physics, nanostructure formation, and biophysics. He has been awarded several renowned prizes, and elected as an academician of Chinese Academy of Sciences in 1997, and a member of Third World Academy of Sciences in 2003.
Elastic theory of fluid membranes of Helfrich model and its application in other soft matters
Shape problems stemmed from real bio- and abiotic materials in nature initiate many nice theories in sciences. The observation of the law of constant angle of crystal planes by N. Stensen (1669) leaded G. Wulff to the construction of convex crystal shape (1901). From the beautiful shapes of soap films observed by J. Plateau (1803) emerged a “golden age” in the study of minimal surfaces. From investigations on the rise of a liquid in a capillary tube originate T. Young (1805) and P.S. Laplace (1806) theory for surfaces of constant mean curvature, which predicts that liquid bubbles are spherical only (Alexandrov (1950’s)). However, a long-standing problem in physiology is to know why the red blood cells (RBCs) in human bodies are always in a rotationally symmetric and biconcave shape. This problem has puzzled peoples for more than 100 years. It has finally been solved by W. Helfrich (1973), who recognized a membrane as being a liquid crystal (LC) film and derived from curvature elastic theory of LC a free energy of fluid membranes. The variation with the energy leads a generalized Young-Laplace shape equation (Ou-Yang and Helfrich, 1987). In this talk some progress of our study following Helfrich model for the last 25 years are reported. We found that the shape equation predicts not only the exact solution for RCB shape but also a special kind of torus vesicle which was soon afterwards confirmed by experimental observations. Especially, the Helfrich model was successfully extended to investigate the complex structures in other soft matters such as the formation of focal conic domains in smectic LC, helical carbon nanotubes, the tube to sphere transition in peptide nanostructures, and icosahedral self-assemblies in virus capsids.
Alessandro Veneziani has completed his PhD in Computational and Applied Mathematics at the University of Milan. He is currently associate professor at the Department of Mathematics and Computer Sciences at Emory University, GA, USA. He was assistant professor at the Politecnico di Milano (MOX) from 2002 to 2007. Professor Veneziani is recipient with A. Quarteroni and P. Zunino of the 2004 SIAM Outstanding Paper Prize. Professor Veneziani his co-editor of two books on cardiovascular mathematics, 54 peer-reviewed papers on international journals, 9 chapters of scientific books and 19 peer-reviewed proceedings of international conferences. His research interest include: Numerical Approximation of Partial Differential Equations, Preconditioning Techniques, Computational Fluid Mechanics, Domain Decomposition Methods, Multiscale Modeling, Numerical Modeling of the Cardiovascular System, Data Assimilation, Industrial Applications of Scientific Computing.
From simulations to assimilations: challenges and perspectives of bringing cardiovascular mathematics to the bedside
Mathematical and numerical modeling of cardiovascular problems has experienced a terrific progress in the last years, evolving into a unique tool for patient-specific analysis. In silico models are acknowledged to be not only complementary but also sometimes more reliable than animal models in representing specific pathologies. However, the extensive introduction of numerical procedures as a part of an established clinical routine and more in general of a consolidated support to the decision making process of physicians still requires some steps both in terms of infrastructures (to bring computational tools to the operating room or to the bedside) and methods. In particular, the quality of the numerical results needs to be carefully assessed and certified. In this scenario, an important research line quite established in other fields is the integration of numerical simulations and measurements in what is usually called Data Assimilation. A rigorous merging of available data (images, measures) and mathematical models is expected to reduce the uncertainty intrinsic in mathematical models featuring parameters that would require a patient-specific quantification; and to improve the overall quality of information provided by measures. However, computational costs of assimilation procedures - and in particular variational approaches - may be quite high, as typically we need to solve inverse problems, dual and possibly backward-in-time equations. For this reason, appropriate model reduction techniques are required, to fit assimilation procedures within the timelines and the size of patient cohorts usually needed by medical doctors. In this talk, we will consider some applications of variational data assimilation in vascular and cardiac problems and associated model reduction techniques currently investigated to bring operatively numerical simulations into the clinical routine. In particular, hierarchical modeling of the solution of partial differential equations in domains featuring a prevalent mainstream, like arteries, will be addressed.
Yiannis Ventikos is the Kennedy Professor of Mechanical Engineering and the Head of the Mechanical Engineering Department at University College London, since the summer of 2013. He moved to UCL fromOxford where he was a Professor of Engineering Science and a Fellow at Wadham College, since December 2003.His research focuses on transport phenomena and fluid mechanics, as they are applied to biomedical engineering problems, energy, innovative industrial processes and biocomplexity. Areas of research include arterial haemodynamics and tissue remodelling (with an emphasis on vascular malformations, like aneurysms),cerebrospinal fluid dynamics, shock-induced bubble collapse, droplet generation and deposition, targeted drug delivery, swirling flows, chaos, mixing and dynamical systems, organogenesis & tissue engineering, micro- and nano-technologies. Prof Ventikos has established the Fluidics and Biocomplexity Group that currently involves more than twenty researchers, mostly at the doctoral and postdoctoral level. He has published about 100 papers in peer-reviewed scientific journals, has contributed chapters in 5 books, has presented more than 200 papers in international conferences and workshops and has filed six international patents to date. He is the senior academic founder of a spinout company and consults internationally in topics of his expertise. He serves as a regular reviewer for more than 50 academic journals as well as for textbook and monograph publishers; he is on the editorial board of four journals, and on the scientific and/or organising committee of numerous international conferences and workshops.
Evaluation of device efficacy for cerebral aneurysm treatment: from deployment to clot development
Cerebral aneurysm treatment outcome is dependent on the specific patient in question. A framework which could be used to predict outcome is presented and is used to compare the efficacy of different treatment methods. This framework accounts for vascular architecture reconstruction, device deployment, computation of local haemodynamics and clot development in the aneurysm sac. The results illustrate that in some cases, device deployment improves the situation and depicts characteristics associated with reduced rupture risk.
Wolfgang A Wall
Wolfgang A. Wall is full professor and founding director of the Institute for Computational Mechanics at the Technische Universität München in Germany since 2003. He received his diploma in Civil Engineering from the University of Innsbruck (Austria) and his PhD from the University of Stuttgart (Germany) in 1999. He acted as founding director of the Munich School of Engineering as well as of the Center for Computational Biomedical Engineering and is co-founder of the company AdCo EngineeringGW. Wolfgang A. Wall has published far more than hundred peer-reviewed journal papers and also serves on several editorial boards of international journals. Among others he currently is president of the German Association of Computational Mechanics, Chairman of the ECCOMAS CFD committee and member of the executive council of IACM. He has received several awards, including the IACM Fellow award in 2008, the Computational Mechanics award from IACM in 2012 and several Golden Teaching awards. His research interests can be described as “application motivated fundamental research” in a broad range of areas in computational mechanics, including both computational solid and fluid mechanics. His current focus is on multifield and multiscale problems as well as on computational biomedical engineering. The biomedical engineering area includes the development of a comprehensive coupled multiscale model of the respiratory system, of a model for rupture risk prediction of abdominal aortic aneurysms and was in recent years also extended to other fields like comprehensive cardiac modelling, simulation of surgical procedures or cellular modeling. In recent years they also successfully entered the area of biophysics, where they could develop a novel, theoretically sound and highly efficient approach for the Brownian dynamics of polymers and hence were a.o. able to study the polymorphism of the cytosceleton. In all these areas they cover the full cycle from advanced modeling to the development of novel methods to advanced software development and simulation on High Performance Computers – and meanwhile even include optimization, inverse analysis, uncertainty quantification aspects as well as some experimental work.
A comprehensive computational model to obtain clinically relevant insight into the human respiratory system
Essential processes in the human lung span a variety of different scales and different fields in a rather complex geometrical setup. This combination of complexities together with the fact that only very few relevant quantities can be measured in patients, is causing a huge lack of knowledge about the detailed functioning of this organ. This is in clear contradiction to the importance of this organ and to how desperately the medical community is looking for a better understanding. For this purpose we are developing a number of different novel computational models and are combining it to a comprehensive model of the respiratory system. Our original motivation was the development of protective ventilation strategies and hence our research was mainly concerned with computational modeling of the respiratory system against the background of acute lung diseases and mechanical ventilation. But meanwhile we also extended it to other scenarios. In this talk we will give an overview of our comprehensive computational model of the human lung and will provide a deeper focus into a few specific and important theoretical and methodical developments. In this context we will cover different relevant aspects like states of strain, flow and transport in this complex system. Models will include the full range from three-dimensional to 0D models also incorporating some important coupled models. A focus will also be on the interplay between flow and tissue deformation, since this has a special importance in this scenario – it is not only defining challenging flow boundary condition information but often is also the actuator of the flow. As a last important aspect of this organ we will also briefly address different transport phenomena and how these can be modeled in such a complex setup.
Frans van de Vosse
Frans van de Vosse is professor of Cardiovascular Biomechanics. From 1976 to 1982 he studied Applied Physics at Eindhoven University of Technology (TU/e). He earned his Ph.D. degree from the same university in 1987. His Ph.D. research was focussed on the numerical analysis of carotid artery flow. From 1987 to 2001 he was lecturer in fluid mechanics with the Materials Technology group in the department of Mechanical Engineering (W, TU/e). In 2001 he was appointed at the department of Biomedical engineering (BMT, TU/e). His current research interests are related to the computational and experimental biomechanical analysis of the cardiovascular system and its application to clinical diagnosis and intervention, cardiovascular prostheses, extra corporeal systems and medical devices
Model predictive clinical decision support in cardiovascular intervention
Although mathematical models have proved their use to obtain more insights into human (patho-)physiology, their use for clinical decision support is currently hardly exploited and deserves more attention in a world where health care demands and costs increase globally. Five main steps towards the clinical applicability of computational models for clinical decision support can be discerned. First, the mathematical model and the applied computational technique must be developed based on physical understanding of the final clinical application. In general the mechanical interaction between blood flow and cardiovascular tissue deformation must be dealt with in a fluid-structure interaction model. Next these models need to be verified with respect to the physical phenomena they are supposed to describe. In many cases in-vitro models that represent a specific site of the cardiovascular system can be used for this purpose. Thirdly, proper constitutive models for both the solid as well as the fluid must be defined and parameters must be derived from either ex-vivo or in-vivo experimental studies. Next, clinical measurement and imaging techniques that are suitable to assess the parameters that define the patient specificity of the model must be developed and evaluated. Finally, the predictive value of the computational model must be determined using uncertainty analysis in clinical studies. In the presentation this sequence of steps will be illustrated by their application to clinical decisions regarding coronary artery revascularisation, management of abdominal aortic aneurysm patients, and planning of vascular access for dialysis patients.