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19.05.19:

PhD Defence

On Friday May 19th, Magne Andre Nordaas successfully defended his PhD thesis Operator preconditioning for PDE-constrained optimisation and multiscale problems.

The defense took place at 13.15 at Storstua, Simula.

Many physical processes are described with partial differential equations (PDE), with important examples such as thermal conduction, Maxwell laws for electrodynamics and Navier-Stokes equations for viscous fluids.

In many applications, we do not want to find just any solution for differential equation, but an optimal solution in a specific sense: We have one or more parameters in the PDE model that we can tune, and we want to find the parameter values that are most beneficial. A classic example is to determine the shape of an airfoil, so that the airflow around the wing results in the best possible flight characteristics.

A related problem is the reconstruction of physical processes based on incomplete measurements. In such a problem, we seek the solution to the differential equation that best fits the measurement data.

Both examples above can be formulated as optimization problems with PDE constraints. In almost all applications, we can not calculate the exact solution for a PDE or a PDE-constrained optimization problem. Instead, we must compute a numerical approximate solution. For PDE-constrained optimization, this usually involves solving large sparse saddle point systems.

In his thesis work Magne has investigated methods to solve such problems in an efficient way. A key technique is operator preconditioning. This involves identifying a mathematical structure in the problem that can be exploited to derive effective solution algorithms. The thesis consists of three papers. The first two paper concerns parameter-robust preconditioning techniques for saddle point systems. In the third paper, a PDE-constrained optimization method is applied to solve a data assimilation problem for cerebral blood flow.

The thesis is written within the field of Scientific Computing. The work has been conducted at Simula Research Laboratory.

Prior to the defense, at 10:15, Magne Nordaas presented his trial lecture Optimality conditions for nonlinear equality constrained optimization problems.

The adjudication committee:

  • Professor Roland Herzog, Technische Universitet Chemnitz, Germany
  • Senior R&D Software Engineer Trygve Karper, Schlumberger Limited, Norway
  • Associate Professor Joakim Sundnes, Department of Informatics, University of Oslo

Chair of the disputation:

  • Professor Fritz Albregtsen, Department of Informatics

Supervisors:

  • Professor Kent-Andre Mardal, Department of Mathematics, University of Oslo
  • Professor Bjørn Fredrik Nielsen, Norwegian University of Life Sciences

14.02.17:

Marie Rognes speaks at the sixth annual TEDxOslo event @ Nationaltheatret, Oslo, May 3rd.

Together with other prominent speakers, Marie Rognes is speaking at the sixth annual TEDxOslo event this spring. Her presentation will address the question: How does someone use mathematics to create future solutions for medical diagnostics and treatment?

Information about the event is found at TEDxOslo's webpage

14.02.17:

Kristian Valen-Sendstad's receives FRINATEK project, with the working title Are Computer Simulations Misleading Us About the Pathobiology of Cerebrovascular Diseases?.

Kristian's project will investigate whether the software simulating blood flow allows for enough precision and complexity to accurately identify budding aneurysms, and the project hopes to pave the way for disease prevention. The funding for this research is a Young Research Talents grant by the Research Council of Norway's FRINATEK and IKTPLUSS programmes.

Abstract

Stroke is one of the leading causes of death worldwide caused by either atherosclerotic plaques or defect balloon-shaped blood vessels in the brain (aneurysms). Both diseases are focally distributed, which highlights the role of blood flow-induced wall shear stress. Direct measurements of these stresses are difficult and medical image-based computational fluid dynamics (CFD) has been extensively used to study the 'patient-specific' local abnormal forces in search for a mechanistic biological link to disease initiation.

However, while robust, the default settings in most commercial codes trade accuracy for speed, and are generally incapable of handling complex flows. The principal investigator (PI) has previously shown that such commercial tools can be misleading about the nature of flow in the cardiovascular system.

The PI's ambition is to holistically answer fundamental questions in vascular biology critical for our understanding of disease initiation, which can ultimately pave the way for prevention or reversal of the disease. The key innovation is development of novel and sophisticated numerical models to test hypotheses in biomechanics and to guide in vitro cell experiments. These experiments will elucidate the role of turbulent-like flows in endothelial phenotype and the frequency spectrum that endothelial cells can sense, distinguish, and finally respond via phenotype shifting. Since aneurysms normally only occurs at one side of the blood vessels in the brain, we will investigate whether there are in vivo differences in flow phenotypes at the aneurysmal side. These experiments will rule out any patient genetic predisposition and effects of systemic risk factors allowing for investigation of hemodynamic effects on aneurysm initiation and development. This unique set of in silico, in vitro, and in vivo experiments will authoritatively elucidate the role of hemodynamic instabilities in aneurysm initiation.

13.01.17:

PhD Defence

On Friday January 13th, Øyvind Evju successfully defended his PhD thesis Computational hemodynamics in cerebral aneurysms: Robustness of rupture risk indicators under different model assumptions .

The defense took place at 13.15 at Storstua, Simula.

About 3-5% of the population will harbor one or more aneurysms at some point. These ballon-like dilations of blood vessels may rupture, and cause a severe stroke. Luckily, ruptured aneurysms are rare, and treatment is available. Choosing which aneurysms to treat is a decision clinicians in this field face daily.

Recently, simulations of the blood flow in the brain has proven to be a promising tool in describing the risk of rupture for aneurysms. This is very attractive because of its non- invasive nature, where only external measurements of the patient are required. However, these simulations are complex, and require multiple assumptions.

In this thesis, the effects of several common assumptions are evaluated. The results of this thesis solidifies the foundations other studies in the field are built upon. Although errors caused by different assumptions may be large, their effects are diminished in large, quantitiative studies. However, for individualized treatment of aneurysms, more and better measurements are required.

The thesis is written within the field of Biomedical Computing. The work has been conducted at Simula Research Laboratory.

Prior to the defense, at 10:15, Øyvind Evju will present his trial lecture Modeling of processes such as inflammation.

The adjudication committee:

  • Professor Juan Cebral, George Mason University, United States of America
  • Professor Trond Kvamsdal, NTNU, Norway
  • Professor Xing Cai, Department of Informatics, University of Oslo

Chair of the disputation:

  • Professor Fritz Albregtsen, Department of Informatics

Supervisors:

  • Professor Kent-Andre Mardal, Department of Mathematics, University of Oslo
  • Senior Research Engineer Martin Sandve Aln¾s, Simula Research Laboratory
  • Research Scientist Kristian Valen-Sendstad, Simula Research Laboratory
  • Professor Hans Petter Langtangen, Department of Informatics, University of Oslo
  • Associate Professor Angelika Sorteberg, Department of Neurosurgery, University of Oslo

13.01.17:

PhD Defence

On Tuesday January 10th, Gabriel Balaban successfully defended his PhD thesis Adjoint Data Assimilation Methods for Cardiac Mechanics.

The defense will take place at 13.15 at Storstua, Simula

Medical images provide detailed information which doctors can use to diagnose heart disease and plan treatements. Conditions such as myocardial infarctions and dyssynchrony can be recognized by their distinct motion patterns in images. The progression of these diseases however, is influenced by elastic forces and the ability of the muscles to contract. These cannot be viewed in images by themselves, but can instead be determined with the help of a mathematical model which is personalized to a patient.

In this thesis methods for the creation of personalized models of heart motion using data from medical images are developed. The result is a computer model of a patient's heart which moves the same way as in the images. The personalized model can then be used to provide elastic force and contraction information. Such models have been contructed before, but with the methods developed in this thesis, much greater resolution and accuracy is possible.

The thesis is written within the field of Biomedical Computing. The work has been conducted at Simula Research Laboratory.

Prior to the defense, at 10:15, Gabriel Balaban will present his trial lecture "Function of the human myocardium and its mechanical, electrical and chemical characterization based on in vivo measurements".

The adjudication committee:

  • Professor Gerhard Holzapfel, Institute of Biomechanics, Graz University of Technology, Austria
  • Professor Johan Hoffmann, Department of Computational Science and Technology, KTH Royal Institute of Technology, Sweden
  • Associate Professor Geir Kjetil Sandve, Department of informatics, University of Oslo

Chair of the disputation:

  • Head of Department for Informatics, Ellen Munthe-Kaas, Research Group for Logic and Intelligent Data

Supervisors:

  • Senior Research Scientist Marie E. Rognes, Simula Research Laboratory
  • Senior Lecturer Joakim Sundnes, Department of Informatics, University of Oslo

 

27.10.16:

Aslak Bergersen wins Norwegian Computing Center's best Master's thesis award

Aslak Bergersen receives flowers for his thesis

CBC congratulates Aslak Bergersen after he recieves the best thesis award from the Norwegian Computing Centre.

Simula congratulates PhD student Aslak Bergersen, who won the award for best Master's thesis in Mathematics and Computer science at the University of Oslo.

The Norwegian Computing Center is a non-profit foundation devoted to research and development within information and communication technology and applied statistical modeling, and they have been giving the award for best Master's thesis since 2009. This year, the award was shared between Solveig Engebretsen and Simula's own Aslak Bergersen. Aslak wrote his thesis under the supervision of Simula researchers.

The thesis, titled "Investigating the Link Between Patient-Specific Morphology and Hemodynamics: Implications for Aneurysm Initiation?" has been evaluated to be very impressive by a jury established by the Norwegian Computing Center. The jury stated that Aslak Bergersen has written a thesis where each of the three subjects contains enough material for a research article, and that each chapter was good enough to be graded "A". Aslak Bergersen continues the work he started in his Master's thesis as a PhD student here at CBC, with Kristian Valen-Sendstad as his supervisor.

 

11.10.16:

PhD defence

On Tuesday, October 11nth, Vinzenz Gregor Eck defended his PhD thesis: Uncertainty Quantification and Sensitivity Analysis for Cardiovascular Models.

The defense took place at 13:15, in Disputasrommet, Gløshaugen, NTNU.

The major challenge for applying cardiovascular models in personalized medicine is as follows: How certain are the predictions of a cardiovascular model, taking the natural variations and measurement uncertainty of model inputs into account?

To address this challenge, we combined methodologies for uncertainty quantification (UQ) and sensitivity analysis (SA) with cardiovascular models. In a comprehensive guide to UQ and SA, we showed how to quantify the uncertainties of model predictions and the sensitivity of model predictions with respect to model inputs. The approach is exemplified for two clinically relevant models, predicting the following: i.) the severity of coronary artery stenosis, which is a predisposition to stroke and transient ischaemic attack, and ii.) the total arterial compliance, which is considered to be a cardiovascular risk factor, indicating the development of hypertension and atherosclerosis. Furthermore, we developed a framework for UQ and SA in a one-dimensional blood flow model, which can be applied for patient-specific simulations of the cardiovascular system under healthy and diseased conditions. Using this framework, we identified that the aortic arteries play a key role in the development of age-related hypertension. Moreover, we demonstrated how UQ and SA can be applied to guide the selection of the most suitable models, exemplified with the choice of arterial wall models when simulating one-dimensional arterial networks.

In the future, personalized computer models will be applied in medical practice and become an integral part of cellphone apps for diagnostics, robots for interventions, and clinical software for diagnostics and intervention planning. Consequently, vital decisions will increasingly be based on the predictions of computer models. With this outlook, the reliability of the applied computer models need to be assessed and proven using methodologies such as those presented in this thesis.

Arbeidet er utf¿rt ved Institutt for konstruksjonsteknikk, NTNU. Hovedveileder har v¾rt professor Leif Rune Hellevik, Institutt for konstruksjonsteknikk.

The thesis is written at the Department of Structural Engineering at the Norwegian University of Technology and Science.

The examination committee:

  • Associate Professor Shawn Shadden, UC Berkely, USA
  • Dr. Andrea Saltelli, University of Bergen
  • Professor Ingelin Steinsland, Norwegian University of Technology and Science

Supervisor

  • Leif Rune Hellevik, Department of Structural Engineering

 

 

10.10.16:

Hans Petter Langtangen (1962-2016)

CBC Director Hans Petter Langtangen

We are very sad to inform you that our friend, colleague, and the Director of CBC, Professor Hans Petter Langtangen, passed away on October 10th.

Hans Petter was an extraordinarily productive author, lecturer, supervisor and researcher. His books on software and methods for solving differential equations are widely used and have influenced these fields considerably. He established one of the most popular enduring courses at the University of Oslo and supervised nearly 100 MSc or PhD graduates. Scientifically, he was always concerned with the efficient solution of differential equations, in terms of both CPU and human efforts. He produced scientific software of extremely high quality that has found users all over the world. Hans Petter led the Norwegian Center of Excellence - Center for Biomedical Computing (CBC) since its start in 2006. The scientific computing community also knows him as a long time member of the editorial board of SISC, and, in particular, as the Editor-in-Chief from 2011 to 2015.

Hans Petter loved his work and intensified his efforts after becoming ill. He concentrated on his books, and finished the last book only one week before he died. During his period of illness, he impressed both friends and colleagues by notable openess about his disease, regularly updating a Facebook group with information about the development of the cancer and his treatment.

Hans Petter was an unusually friendly man, always willing to share whatever knowledge he had with others. His impact on students and colleagues has been enormous; no one left his office or his auditorium without deeper insight, and a feeling of joy.

Hans Petter will be deeply missed by his family, friends and by colleagues from all over the world.

We invite you to share your memories of Hans Petter on: hpl-memorial.simula.no/

 

29.09.16:

ERC Starting grant to Marie E. Rognes

Dr. Marie Rognes

CBC project leader, Marie E. Rognes, has been awarded the very prestigious ERC Starting Grant. Only seven Norwegian researchers has achieved this so far in Horizon 2020, and only a total of 19 ERC grants have been awarded to Norwegian researchers. Securing an ERC Starting Grant is a significant recognition of Marie E. Rognes and her research at CBC. Marie E. Rognes will receive EUR 1.5 million over the next five years in order to conduct the "Waterscales" project.

The full title of the Waterscales project is Mathematical and computational foundations for modeling cerebral fluid flow. The project is awarded from the panel PE1 (Mathematics) of the European Research Council (ERC). The aim of the project is to establish the mathematical, numerical and computational foundations for predictively modeling fluid flow and solute transport through the brain across spatiotemporal scales -- from the cellular to the organ level.

Your brain has its own waterscape: whether you are reading or sleeping, fluid flows through the brain tissue and clears waste in the process. These physiological processes are crucial for the well-being of the brain. In spite of their importance, we have little understanding of these processes. Mathematics and numerics could play a crucial role in gaining new insight. Indeed, medical doctors express an urgent need for multiscale modeling of water transport through the brain, to overcome limitations in traditional techniques. Surprisingly little attention has been paid to the numerics of the brain's waterscape however, and fundamental knowledge is missing.

In response, the ambition of the Waterscales project is to establish the mathematical and computational foundations for predictively modeling fluid flow and solute transport through the brain across scales -- from the cellular to the organ level. The project aims to bridge multiscale fluid mechanics and cellular electrophysiology to pioneer new families of mathematical models that couple macroscale, mesoscale and microscale flow with glial cell dynamics. For these models, we will design numerical discretization that preserve key properties and that allow for whole organ simulations. To evaluate predictability, we will develop a new computational platform for model adaptivity and calibration. The project is multidisciplinary combining mathematics, mechanics, scientific computing, and physiology.

If successful, this project enables the first in silico studies of the brain's waterscape across scales. The new models would open up a new research field within computational neuroscience with ample opportunities for further mathematical and applied study. The processes at hand are associated with neurodegenerative diseases like dementia and brain swelling caused by stroke. The Waterscales project will provide the field with a sorely needed, new avenue of investigation to understand these conditions, with tremendous long-term impact.

 

Chair of the commission:

  • Professor Knut Liest¿l, University of Oslo

Supervisors:

  • Professor Xing Cai, University of Oslo and Simula Research Laboratory (Main Supervisor)
  • Professor Scott B. Baden, University of Computer Science and Engineering, University of California, San Diego (Co-Supervisor)

22.08.16:

PhD defence

On Monday, August 22nd, Kartik Jain defended his PhD thesis: Transition to Turbulence in Physiological Flows: Direct Numerical Simulation of Hemodynamics in Intracranial Aneurysms and Cerebrospinal Fluid Hydrodynamics in the Spinal Canal..

The defense took place at 09:30, in AR-X1.04 room at the University of Siegen, Germany

The examination committee:

  • Professor Sabine Roller, University of Siegen, Germany
  • Professor Kent-Andre Mardal, University of Oslo and Simula Research Lab
  • Professor Andreas Kolb, University of Siegen, Germany
  • Professor Thomas Carolus, University of Siegen, Germany

Chair of the commission:

  • Professor Thomas Carolus, University of Siegen, Germany

Reviewers of the dissertation:

  • Professor Sabine Roller, University of Siegen, Germany (Main Supervisor)
  • Professor Kent-Andre Mardal, University of Oslo and Simula Research Lab (Co-Supervisor)

 

30.06.16:

Hans Petter Langtangen publishes 4 new books in 2016

CONGRATULATIONS to CBC director Hans Petter Langtangen who has just completed four new books that are being published in 2016!
All four books are Open Access and freely available online to anyone.


1) "Finite Difference Computing with Exponential Decay Models" (by: Hans Petter Langtangen)
This text provides a very simple, initial introduction to the complete scientific computing pipeline: models, discretization, algorithms, programming, verification, and visualization. The pedagogical strategy is to use one case study Ð an ordinary differential equation describing exponential decay processes Ð to illustrate fundamental concepts in mathematics and computer science. The book is easy to read and only requires a command of one-variable calculus and some very basic knowledge about computer programming. Contrary to similar texts on numerical methods and programming, this text has a much stronger focus on implementation and teaches testing and software engineering in particular.
Open Access and freely available online to anyone.

2) "Scaling of Differential Equations" (by: Hans Petter Langtangen and Geir K. Pedersen)
The book serves both as a reference for various scaled models with corresponding dimensionless numbers, and as a resource for learning the art of scaling. A special feature of the book is the emphasis on how to create software for scaled models, based on existing software for unscaled models. Scaling (or non-dimensionalization) is a mathematical technique that greatly simplifies the setting of input parameters in numerical simulations. Moreover, scaling enhances the understanding of how different physical processes interact in a differential equation model. Compared to the existing literature, where the topic of scaling is frequently encountered, but very often in only a brief and shallow setting, the present book gives much more thorough explanations of how to reason about finding the right scales. This process is highly problem dependent, and therefore the book features a lot of worked examples, from very simple ODEs to systems of PDEs, especially from fluid mechanics. The text is easily accessible and example-driven. The first part on ODEs fits even a lower undergraduate level, while the most advanced multiphysics fluid mechanics examples target the graduate level. The scientific literature is full of scaled models, but in most of the cases, the scales are just stated without thorough mathematical reasoning. This book explains how the scales are found mathematically. This book will be a valuable read for anyone doing numerical simulations based on ordinary or partial differential equations.
Open Access and freely available online to anyone.

3) "Programming for Computations - MATLAB/Octave" (by: Hans Petter Langtangen and Svein Linge)
This book presents computer programming as a key method for solving mathematical problems. There are two versions of the book, one for MATLAB and one for Python. The book was inspired by the Springer book TCSE 6: A Primer on Scientific Programming with Python (by Langtangen), but the style is more accessible and concise, in keeping with the needs of engineering students. The book outlines the shortest possible path from no previous experience with programming to a set of skills that allows the students to write simple programs for solving common mathematical problems with numerical methods in engineering and science courses. The emphasis is on generic algorithms, clean design of programs, use of functions, and automatic tests for verification.
Open Access and freely available online to anyone.

4) "Programming for Computations - Python A Gentle Introduction to Numerical Simulations with Python" (by: Svein Linge and Hans Petter Langtangen)
This book presents computer programming as a key method for solving mathematical problems. There are two versions of the book, one for MATLAB and one for Python. The book was inspired by the Springer book TCSE 6: A Primer on Scientific Programming with Python (by Langtangen), but the style is more accessible and concise, in keeping with the needs of engineering students. The book outlines the shortest possible path from no previous experience with programming to a set of skills that allows the students to write simple programs for solving common mathematical problems with numerical methods in engineering and science courses. The emphasis is on generic algorithms, clean design of programs, use of functions, and automatic tests for verification.
Open Access and freely available online to anyone.

 

09.02.16:

Dr. Patrick Farrell was appointed to a permanent Associate Professor positon at the Math Department of Oxford University

Collaboration partner Patrick Farrell won the competition for the permanent Associate Professor positon at the Math Department of Oxford University.

 

26.01.16:

Four CBC affiliated researchers recieve FRINATEK funding

FRINATEK, is the science and technology arm of the wider program FRIPRO, and promotes scientific quality at the forefront of international research, boldness inn scientific thinking and innovation, careers for young research talents and mobility for researchers early in their career. For the 2015 round, 304 project proposals were evaluated, leading to 40 awarded projects and a success rate of 13%.

  • The Numerical Waterscape of the Brain (Dr. Marie Rognes, young research talent)
  • Simulation-based optimisation with dynamic domains (Dr. Simon Funke, young research talent)
  • Function-driven Data Learning in High Dimension (Dr. Valeriya Naumova, young research talent)
  • Meeting Exascale Computing with Source-to-Source Compilers (Professor Xing Cai)

For further information please visit the webpages of the Research Council of Norway.

 

14.01.16:

CBC director Hans Petter Langtangen receives the 2016 Olav Thon national prize for excellence in teaching

Rector Ole Petter Ottersen at the University of Oslo announced Thursday 13 January that Professor Hans Petter Langtangen has received an award for excellence in teaching from the Olav Thon Foundation.

Olav Thon Stiftelsens faglige priser og støtte til forskning 2016

Olav Thon Stiftelsen utdeler i år for andre gang, faglige priser og støtte til fremragende undervisning og forskning innen de medisinske og matematisk-naturvitenskapelige fagområder. Dette er tildelinger for høytstående internasjonal og nasjonal forskning og for forskningsbasert undervisning på universitets- og høyskolenivå. Nytt i år er en egen tildeling av støtte til nordisk forskningssamarbeid i medisin.

Stiftelsen utdeler i 2016 drøye NOK 44 millioner. Disse fordeler seg som følger:

  • En internasjonal forskningspris innen de medisinske og naturvitenskapelige fagområder. Prisen er på NOK 5 millioner
  • Støtte til nordisk forskningssamarbeid i medisin innenfor temaene Alzheimers sykdom og Parkinsons sykdom, i alt 3 prosjekter som hver tildeles NOK 10 millioner
  • Seks nasjonale fagpriser for fremragende undervisning, hver på NOK 500 000,-
  • Støtte til undervisningsrelatert forskning til fem norske fagmiljøer, som hver får støtte på mellom NOK 1,2 millioner og 1,5 millioner

Nasjonale priser for fremragende undervisning

Den nasjonale fagprisen for fremragende undervisning gis til følgende:

  • Professor Karin Pittman (biologi/akvakultur), Universitetet i Bergen. Pittmann leder kurs på masternivå. I disse kursene forutsettes det at studentene samarbeider med eksterne aktører utenfor universitetet.
  • Professor Vidar Selås (zoologi, økologi, naturforvaltning), Norges Miljø og Biovitenskapelige universitet, Ås. Selås har utviklet kurs på både lave og høyere studienivå i naturforvaltning, hvor studentene som del av disse kursene bor på en forskningsstasjon over tid og får en flerfaglig introduksjon til metodikk mm i studiet av natur.
  • Professor Inger Njølstad (medisin), Universitetet i Tromsø/ Norges arktiske universitet. Njølstad har utviklet og implementert en ny studieplan for utdanning av leger. Her gis det en vitenskapelig bakgrunn for en endret medisiner-utdanning og om hvordan nye undervisningsformer styrker studenters evne til å håndtere sammensatte (og nye) sykdommer og sykdomstilstander.
  • Professor Hans Petter Langtangen (informatikk), Universitetet i Oslo. Langtangen har vært en pioner innen innovasjon hva gjelder undervisning i programmering og flere andre felt.
  • Førsteamanuensis Christian Jørgensen (biologi og evolusjonsøkologi), Universitetet i Bergen). Jørgensen har utviklet aktive dialogbaserte undervisningsformer som er blitt meget anerkjent av kolleger og studenter. Dette kommer særlig frem i jevnlige studentevalueringer.
  • Professor Per Grøttum (medisin), Universitetet i Oslo. Grøttum har arbeidet med digitale undervisnings- og eksamensformer innen medisinerutdanningen ved UiO.
Hver av de ovennevnte gis en pris på NOK 500 000,-.

 

29.10.15:

CBC projectleader Marie Rognes appointed founding member of The Young Academy of Norway

Dr. Marie Rognes

The Young Academy of Norway is a new, interdisciplinary, Norwegian Academy of Sciences dedicated to young researchers.

Starting out in Germany in 2000, such Young Academies now exist in close to 30 countries. In competition with 160 other researchers, Simula researcher and head of the Biomedical Computing department Marie Rognes has been selected as one of the 20 founding members of the Young Academy of Norway.

The Young Academy of Norway will be established on October 29. Its mission is to be an interdisciplinary meeting place, and serve as a platform for research policy development. The Young Academy of Norway has an ambition to be a power house for research dissemination and an attractive discussion arena. The Academy is an initiative of the Norwegian Academy of Science and Letters, with funding from the Ministry of Research and Education.

Marie will join some of the most promising young researchers in all fields from psychology and applied music to medicine and theoretical chemistry. We congratulate Marie!

You can also read more on the pages of the Norwegian Academy of Science and Letters (in Norwegian).

 

CBC researchers recieve the Wilkinson prize for their work on dolfin-adjoint

The Wilkinson Prize was established to honour the outstanding contributions of Dr James Hardy Wilkinson to the field of numerical software. It is awarded every four years at the International Congress on Industrial and Applied Mathematics by Argonne National Laboratory, the National Physical Laboratory, and the Numerical Algorithms Group. The recipients are authors of an outstanding piece of numerical software, judged on:

  • the clarity of the software implementation and documentation;
  • the importance of the application(s) addressed by the software;
  • the portability, reliability, efficiency and usability of the software implementation;
  • the clarity and depth of analysis of the algorithms and the software in the submission;
  • the quality of the test software.
Dolfin code

The 2015 prize is awarded to P. E. Farrell (University of Oxford and CBC), S. W. Funke (Center for Biomedical Computing at Simula Research Laboratory), D. A. Ham (Imperial College London), and M.E. Rognes (Center for Biomedical Computing at Simula Research Laboratory) for the development of dolfin-adjoint, a package which automatically derives and solves adjoint and tangent linear equations from high-level mathematical specifications of finite element discretisations of partial differential equations.  The prize will be presented at ICIAM 2015 and will consist of $3000 plus a commemorative plaque for each winner.

The need for adjoints of partial differential equations (PDEs) pervades science and engineering. Adjoints enable the study of the sensitivity and stability of physical systems, and the optimization of designs subject to constraints. While deriving the adjoint model associated with a linear stationary forward model is straightforward, the derivation and implementation of adjoint models for nonlinear or time-dependent models is notoriously difficult. dolfin-adjoint solves this problem by automatically analysing and exploiting the high-level mathematical structure inherent in finite element methods.  It is implemented on top of the FEniCS Project for finite element discretisations.

Previous prize winners:

  • 2011: Andreas Waechter and Carl D. Laird for Ipopt.
  • 2007: Wolfgang Bangerth for deal.II.
  • 2003: Jonathan Shewchuch for Triangle.
  • 1999: Matteo Frigo and Steven Johnson for FFTW.
  • 1995: Chris Bischof and Alan Carle for ADIFOR.
  • 1991: Linda Petzold for DASSL.

 

 

PhD defences

17.12.15:

On Thursday, December 17th, Mohammed Sourouri defended his PhD thesis: Scalable Heterogeneous Supercomputing: Programming Methodologies and Automated Code Generation.

The defense will take place at 13:30, in Storstua at Simula Research Laboratory.

Prior to the defense, at 10:15, Mohammed Sourouri presented his trial lecture: ÒDomain-specific systems and frameworks for graph algorithms: research overview and future perspectiveÓ.

The adjudication committee:

  • First opponent: Professor Mary Hall, School of Computing, University of Utah, USA
  • Second opponent: Professor Michael Bader, Institut für Informatik, TU München, Germany
  • Coordinator: Professor Tor Skeie, Department of Informatics, University of Oslo

Chair of the disputation:

  • Professor Knut Liestøl, Department of Informatics, University of Oslo

Supervisors:

  • Professor Xing Cai, University of Oslo and Simula Research Laboratory (Main supervisor)
  • Professor Scott B. Baden, Department of Computer Science and Engineering, University of California, San Diego, USA (Co-supervisor)
  • Professor Scott B. Baden, Department of Computer Science and Engineering, University of California, San Diego, USA

09.10.15:

On Friday, 9th of October 2015, Ole Løseth Elvetun defended his PhD thesis PDE-constrained optimization: Preconditioners and diffuse domain methods.

The defense took place at 13:00 The Centre for Plant Research in Controlled Climate (SKP), Syverudveien 6, Ås.

Prior to the defense, at 11:00, Ole L. Elvetun presented his trial lecture: Multigrid methods: An overview of some important applications and algorithms.

The adjudication committee:

  • First opponent: Professor Walter Zulehner, Johannes Kepler Universität Linz, Austria
  • Second opponent: Professor Xue-Cheng Tai, University of Bergen
  • Coordinator: Associate Professor Ulf Geir Indahl, Department of Mathematical Sciences and Technology, NMBU

Supervisors:

  • Professor Bjørn Fredrik Nielsen, Department of Mathematical Sciences and Technology, NMBU and Simula Research Laboratory (Main supervisor)
  • Professor John Andreas Wyller, Department of Mathematical Sciences and Technology, NMBU (Co-supervisor)
  • Associate Prof Kent-Andre Mardal, Department of Mathematics, University of Oslo and CBC (Co-supervisor)
  • Professor Arkadi Ponossov, Department of Mathematical Sciences and Technology, NMBU (Co-supervisor)

28.08.15:

On Friday, 28th of August 2015, Jonathan Feinberg defended his PhD thesis Some improvements and Applications of Non-intrusive Polynomial Chaos Expansions.

The defense took place at 13:15 in Auditorium 5, Vilhelm Bjerknes hus, University of Oslo.

For scientists to be able to trust their own research results, it is imperative to map the uncertainty in the models they use. However, this is often numerically resource intensive. This thesis introduce polynomial chaos expansions, a completely new research tool to map uncertainty in numerical models. The thesis makes uncertainty quantification easier and more accessible to researchers. The research is split into three papers. The first paper shows that polynomials chaos expansions are applicable in an bio-mechansics model simulating blood flow simulation, out-competing alternative approaches. In the second paper a software toolbox was developed to give researches easy access to polynomial chaos expansions. And lastly, in the third paper, the theoretical framework for polynomial chaos expansions to show that it can be effective for problems previously known to be problematic.

The thesis was written within the field of uncertainty quantification. The work has been conducted at Center for Biomedical Computing at Simula Research Laboratory.

Prior to the defense, at 10:15, Jonathan Feinberg presented his trial lecture: A critical review of numerical methods for stochastic Langevin equations.

The adjudication committee:

  • Professor Daniel Tartakovsky, University of California, San Diego
  • Professor Håvard Rue, Norwegian University of Science and Technology (NTNU)
  • Professor Erik Bølviken, University of Oslo

Chair of the disputation:

  • Professor, Ørnulf Borgan, University of Oslo

Supervisors:

  • Professor Hans Petter Langtangen, University of Oslo and Simula Research Laboratory
  • Professor Arne Bang Huseby, University of Oslo
  • Dr. Stuart Clark, Simula Research Laboratory

05.11.14:

On Wednesday, 5th of November, Bernardo Lino de Oliveira defended his PhD thesis Computational Models for Cardiac Electromechanics.

The defense took place at 13.15 in Storstua at Simula Research Laboratory, Martin Linges vei 17, Fornebu.

The aim of the thesis was to contribute to the progress of cardiac modeling by studying and developing computational models to represent the electromechanical processes in the heart. Several interesting questions can be studied using coupled electromechanical models of the heart as many questions are intrinsically related to the coupling between these problems. These coupled problems give rise to many modeling and numerical challenges, both from the electrophysiology and mechanics parts and are many times related to the coupling itself. This thesis has made a contribution to the understanding and development of coupled electromechanical models of the heart, and to how these models can be solved efficiently.

The thesis was written within the field of Cardiac Modeling. The work has been conducted at Simula Research Laboratory.

Prior to the defense, at 10:15, Bernardo Lino de Oliveira presented his trial lecture: An Overview of Multiscale Cardiac Models.

The adjudication committee:

  • PhD, Professor Leif Rune Hellevik, NTNU
  • PhD, Researcher, Sergio Alonso, Physikalisch-Technische Bundesanstalt, Berlin, Germany
  • PhD, Associate Professor Kent-Andre Mardal, Department of Mathematics, Universitetet i Oslo

Chair of the disputation:

  • Professor, Knut Liestøl, Department of Informatics, University of Oslo

Supervisors:

  • PhD, Joakim Sundnes, Simula Research Laboratory
  • PhD, Samuel Wall, Simula Research Laboratory
  • Dsc, Rodrigo Weber dos Santos, Universidade Federal de Juiz de Fora, Brazil

05.06.14:

On Thursday June 5, at 13:15, Karen Støverud defended her PhD Thesis Relation between the Chiari I malformation and syringomyelia from a mechanical perspective.

The defense took place at 13:15 in Storstua at Simula Research Laboratory, Martin Linges vei 17, Fornebu.

Even though it is unknown to most people, about 0.1 % of the population has Chiari I. The Chiari I malformation is a neurological condition in which parts of the cerebellum is displaced into the spinal column. This causes a partial obstruction of the cerebrospinal fluid (CSF) space surrounding the brain and spinal cord. Chiari I may cause a wide range of symptoms such as severe headaches, sleep apnea, visual disturbances and muscle weakness. Secondary to a Chiari malformation many patients develop fluid filled cavities, syrinxes, within the spinal cord tissue, which causes further symptoms.

To offer these patients optimal treatment and an increased quality of life we need a better understanding of the underlying causes. The exact relation between Chiari I and syrinx formation remains unknown, but it is believed that it is related to an abnormal pressure environment and therefore mechanically driven.

The aim of this thesis were first to simulate CSF flow in healthy subjects and Chiari patients under patient specific anatomy and flow conditions. Second to simulate wave propagation and fluid movement through the spinal cord. Finally, we related results from the simulations to syrinx formation and suggest alternative measures for abnormal CSF flow.

The results showed that obstructions of the CSF space, as seen in Chiari patients, causes increased pressure gradients and decreased phase lag between velocity and pressure. A significant increase in the pressure drop may be used to distinguish a moderate from a severe obstruction. By including parts of the cranial CSF space we reproduced complex flow patterns seen in vivo in Chiari patients. Finally, an open segment of the central canal and/or a stiff spinal cord causes increased pressure gradients and enhance fluid flow in the central canal of the spinal cord.

Prior to the defense, at 10:15, Karen-Helene Støverud presented her trial lecture: Computer simulations of pressure and velocity in cerebral blood flow -tools and clinical applications.

The adjudication committee:

  • Professor Yiannis Ventikos, Department of Mechanical Engineering, University College London, UK
  • Research Scientist, Klas Pettersen, NCMM Erlend Nagelhus Group (Glia-vascular Imaging), University of Oslo
  • Ass.Professor Glenn Terje Lines, Department of Informatics, University of Oslo

Chair of the disputation:

  • Professor, Fritz Albregtsen, Department of Informatics, University of Oslo

Supervisors:

  • Ass. Professor Kent-Andre Mardal, Department of Informatics, University of Oslo and Simula Research Lab
  • Professor Hans Petter Langtangen, Department of Informatics, University of Oslo and Simula Research Lab.
  • Professor Em. Victor Haughton, Department of Radiology, UW Madison and Simula Research Lab
  • Ass. Professor Mikael Mortensen, Department of Mathematics, University of Oslo

04.11.13:

On Monday November 4, at 13:15, Tor Gillberg defended his PhD Thesis Fast and accurate front propagation for simulation of geological folds.

Front propagations described by static Hamilton-Jacobi equations can be used to simulate folded geological structures. Simulations of geological folds are a key ingredient in the Compound Earth Simulator (CES), an industrial software tool used in the exploration of oil and gas. In this thesis, local approximation techniques are investigated with respect to accuracy and efficiency. Several novel algorithms are also introduced, of which some are accelerated by parallel implementations on both multicore CPUs and Graphic Processing Units. These algorithms are able to simulate folds at a fraction of the time needed by the CES industry code, while retaining the same level of accuracy. Complicated tasks that previously needed several minutes to be computed can now be performed in just a matter of a few seconds, thus significantly improving the CES user experience.
The thesis is written within the field of Scientific Computing. The work has been conducted at Simula Research Laboratory and Kalkulo AS.

Prior to the defense, at 10:15, Tor Gillberg presented his trial lecture Aspects of wave front tracing in anisotropic VTI media.

The adjudication committee:

  • Director Tijmen Jan Moser, Moser Geophysical Services, The Netherlands
  • Professor Ross T. Whitaker, University of Utah, USA
  • Professor Anne H Schistad Solberg, Department of Informatics, University of Oslo

Chair of the disputation:

  • Professor, Fritz Albregtsen, Department of Informatics, University of Oslo

Supervisors:

  • Professor Are Magnus Bruaset, Department of Informatics, University of Oslo
  • Professor Aslak Tveito, Department of Informatics, University of Oslo
  • Dr. Christian Tarrou, Kalkulo AS

12.12.12:

On Wednesday December 12, at 13:15, Wenjie Wei successfully defended his PhD Thesis Effective Use o Multicore-based Parallel Computers for Scientific Computing.

The prevalence of multi-core CPUs during the last decade has provided scientists with the possibility of conducting large-scale computer simulations. However, the multi-core architecture brought not only improved computing capabilities but also more programming challenges due to more complex memory hierarchies.
In this thesis, we study how to efficiently utilize the computing power of multi-core CPUs and how to analyze the code performance obtainable on this hardware architecture. A series of interdisciplinary real-world scientific applications have been selected as the cases of study, which arise from computational cardiology and computational geoscience.
The PhD investigation has been carried out from different angles: numerical algorithms, parallel programming and performance modeling and prediction. For two applications of cardiology, mixed programming and relevant optimization strategies have produced good performance for multi-core based clusters, when the solution domain is irregular. In three other geoscience applications, we have studied how to use compressed data structures, optimize cache usage and effectively parallelize various numerical schemes for the multi- core architecture. A practical approach to analyzing and predicting code performance is also proposed.
It is shown that code implementation and optimization must match both the involved computations and the target parallel platform. Several good practices are summarized for parallel programming and performance analysis on the multi-core architecture, which can be of help to many other scientists.

Prior to the defense, at 11.15, Wenjie Wei presented his trial lecture Tools, models and techniques for scientific programming on current and future heterogenous systems that combine multicore hosts with manycore accelerators.

The adjudication committee:

  • Professor Paul H. J. Kelly, Department of Computing, Imperial College London
  • Professor Tor Sørvik, Department of Mathematics, University of Bergen
  • Professor Carsten Griwodz, Department of Informatics, University of Oslo

Chair of the disputation:

  • Lecturer Dag Langmyhr, Department of Informatics, University of Oslo

Supervisors:

  • Professor Xing Cai, CBC, Simula Research Laboratory & Department of Informatics, University of Oslo
  • Dr. Ola Skavhaug, Simula Research Laboratory
  • Professor Dr. Gerhard Zumbusch, Institute for Numerical Simulation, Fredrich-Schiller Universität Jena

05.11.12:

On Monday November 5, at 13:15, Paul Roger Leinan successfully defended his PhD Thesis Biomechanical Modeling of Fetal Veins. The Umbilical Vein and Ductus Venosus Bifurcation

November 5, 2012 MSc Paul Roger Leinan defended his thesis "Biomechanical modeling of fetal veins. The umbilical vein and ductus venous bifurcation". The models developed in the thesis have been used to improve methods for clinical measurement of the amount of blood flow delivered directly towards the fetal heart. An advanced material model for the vein and the surrounding Wharton's jelly within the umbilical chord was also developed. Finally, a generic model for networks of blood vessels was developed. This model may be used for prediction of flow, pressure and wall shear stress in generic networks of both arteries and veins, even though the primary focus in the thesis was the fetal circulatory system. Networks models are also useful as boundary conditions for 3D fluid-structure interaction models of blood flow in compliant vessels.

Prior to the defense, at 10.15, Paul Roger Leinan presented his trial lecture Modeling of Whiplash Injuries from a Biomechanical Point of View.

The adjudication committee:

  • Associate Professor Giancarlo Pennati, Politecnico de Milano, Italia
  • Professor Hans Petter Langtangen, Simula Research Laboratory and University of Oslo
  • Professor Tore Børvik, Norwegian University of Science and Technology

Chair of the disputation:

  • Professor Tore Børvik, Department of Structural Engineering, Norwegian University of Science and Technology

Supervisors:

  • Professor Leif Rune Hellevik, Department of Structural Engineering, Norwegian University of Science and Technology
  • Professor Bjørn Skallerud, Department of Structural Engineering, Norwegian University of Science and Technology
  • Dr.ir. Joris Degroote, Ghent University

18.06.12:

On Monday June 18, at 11:15, André Massing successfully defended his PhD Thesis Analysis and Implementation of Finite Element Methods on Overlapping and Fictitious Domains

In this work, we look at a mathematical method known as Nitsche's method which allows to couple different equations and domains in a flexible way. We investigate how this method can be applied efficiently to challenging 3D problems. Moreover, we strive to extend Nitsche's method to fluid dynamic problems.

Using data structure and algorithms from the field of computational geometry, we were able to implement a flexible and efficient computational framework to solve various problems by the Nitsche method. As an important part of this thesis, we proposed several new Nitsche-based formulation of a fluid dynamic problem (Stokes problem) and proved optimal convergence properties.

The thesis is written within the field of computational mathematics. The work has been conducted at Simula Research Laboratory.

Prior to the defense, at 11.15, André Massing will present his trial lecture Discontinuous Galerkin Methods for Solving Elliptic PDEs.

The adjudication committee:

  • Professor Paul Houston, School of Mathematical Sciences, University of Nottingham
  • Professor Mohammad Asadzadeh, Department of Mathematical Sciences, Chalmers University of Technology
  • Professor Xing Cai, Simula Research Laboratory / Department of Informatics, University of Oslo

Chair of the disputation:

  • Professor Fritz Albregsten, Departments of Informatics, University of ÊOslo

Supervisors:

  • Dr. Anders Logg, Simula Research Laboratory / Department of Informatics, University of Oslo
  • Professor Mats G. Larson, Department of Mathematics and Statistics, University of Umeå
  • Dr. Marie E. Rognes, Simula Research Laboratory / Department of Informatics, University of Oslo

For more information, please read the announcement of the PhD defense at the University of Oslo's web pages (in Norwegian).

 

27.04.12:

On Friday April 27, at 1315, Sigrid Kaarstad Dahl successfully defend her PhD Thesis Numerical simulations of blood flow in the left side of the heart.

Several aspects of hemodynamics have been addressed: fluid-structure interaction between rigid (mechanical) mitral valve during diastolic filling of the left ventricle; influence of pulmonary vein positions in the left atrium on the atrial flow field and velocity profile at the mitral valve plane; 3D mapping of subject specific ultrasound recordings of left ventricle during the heart cycle into a discretised time and space variable boundary condition for CFD simulations of the left ventricle; effect of mitral valve shape on velocity profile in the left ventricle outflow tract during systole.

The committee writes in their assessment that the thesis is an excellent example of cross-disciplinary research at its best, including input from engineering, non-invasive medical imaging, cardiology and surgeons.

Prior to the defence, at 1015, Kaarstad Dahl presented her trial lecture "Pulsatile flow in the arterial system".

The adjudication committee:

  • Matts Karlsson, professor, Division for Biomedical Modelling and Simulation, Linkøping University
  • Stig Urheim, MD PhD, Department of Cardiovascular and Pulmonary Disease, Oslo University Hospital Rikshospitalet
  • Fridtjov Irgens, Professor emeritus, Department of Structrual Engineering, NTNU

Chair of disputation:

  • Fridtjov Irgens, Professor emeritus, Department of Structrual Engineering, NTNU

Supervisors:

  • Professor Leif Rune Hellevik, Department of Structural Engineering, NTNU
  • Professor Bjørn Skallerud, Department of Structural Engineering, NTNU
  • Professor Jan Vierendels, Department of Flow and Combustion Mechanics, Ghent University
  • Dr Kent Andre Mardal, Simula Research Laboratory

 

26.03.12

On Monday March 26, Didem Unat successfully defended her PhD thesis "Domain-specific translator and optimizer for massive on-chip parallelism".

It should also be mentioned that Dr. Unat was already granted the prestigious Luis W. Alvarez Postdoctoral Fellowship in Computational Science at Lawrence Berkeley National Lab. The awarded fellowship is a recognition of her scientific contribution to the development of a fully-automated translator and optimizer, which can generate parallel GPU code based on serial source code. This methodology has the potential of greatly increasing the productivity of many computational scientists, because the time spent on painstakingly writing parallel software codes can be considerably saved.

Committee in charge:

  • Scott Baden, Professor, Department of Computer Science and Engineering, University of California, San Diego
  • Xing Cai, Professor, Center for Biomedical Computing at Simula Research Laboratory, and Department of Informatics at University of Oslo
  • Andrew McCulloch, Professor, University of California, San Diego
  • Allan Snavely, Professor, San Diego Supercomputer Center (SDSC), University of California, San Diego
  • Daniel Tartakovsky, Professor, Department of Mechanical and Aerospace Engineering, University of California, San Diego
  • Dean M. Tullsen, Professor, Department of Computer Science and Engineering, University of California, San Diego

Chair of the disputation:

  • Scott Baden, Department of Computer Science and Engineering, University of California, San Diego

Supervisors:

  • Scott Baden, Department of Computer Science and Engineering, University of California, San Diego
  • Xing Cai, Center for Biomedical Computing at Simula Research Laboratory, and Department of Informatics at University of Oslo

 

16.06.11:

On Thursday June 16, at 13:15, Joachim Berdal Haga successfully defended his PhD thesis "Numerical methods for basin-scale poroelastic modelling.

Poroelastic modelling is a method for computing the interaction between fluids and porous structures, for example in sedimentary rock or biological tissue. Such computations require that large systems of mathematical equations can be solved. In his thesis, Berdal Haga explores and develops methods for solving efficiently such systems arising from modelling sedimentary basins.

The thesis consists of a number of scientific works dealing with various aspects of this problem. Properties of the system is investigated under particular conditions, like large jumps in permeability, and methods that can handle such conditions are developed. The methods are developed in such a way that they can be used for solving the problem by supercomputers with thousands of processors.

Prior to the defence, at 10:15, Berdal Haga presented his trial lecture Iterative solvers for large linear systems.

The adjudication committee:

  • Axel Målqvist, Associate professor, Division of Scientific Computing, Uppsala Universitet
  • Jan Martin Nordbotten, Professor, Matematisk institutt, Universitetet i Bergen
  • Arnold Bertelsen, Professor, Matematisk institutt, Universitetet i Oslo

Chair of the disputation:

  • Instituttleder Arne Bang Huseby

Supervisors:

  • Harald Osnes, Department of Mathamatics, University of Oslo
  • Hans Petter Langtangen, Simula Research Laboratory and Department of Informatics, University of Oslo

 

20.05.11:

On Friday 20 May, at 13:15, Kristoffer Selim successfully defended his PhD thesis "Adaptive Finite Element Methods for Fluid–Structure Interaction and Incompressible Flow".

On Friday 20 May, at 13:15, Kristoffer Selim will defend his PhD thesis Adaptive Finite Element Methods for Fluid-Structure Interaction and Incompressible Flow. Computer simulation is an important tool in many disciplines of science and engineering. Complex mathematical models are solved in large computer simulations as a complement to experimental techniques and theoretical studies. Selim's thesis focuses on how the quality of such computationally expensive simulations can be ensured, while at the same time making efficient use of the available computer resources.

One such example of a computationally expensive problem is fluid-structure interaction (FSI). This type of problem occurs when a fluid interacts with a solid structure in such a way that the solid structure is deformed and the flow of the fluid itself is altered. The FSI category of problems is of great importance and relevance in many applications. In biomedical research, blood flow in arteries and the human respiratory system are typical examples of problems in this category. In industrial applications, such as the design of airplanes, pipelines and fishing lures, the analysis of the FSI problem is an important part of the engineering process.

In his thesis, Selim investigates and designs adaptive numerical methods for FSI and fluid flow. To ensure that a simulation is of high quality, it is crucial that the accuracy of computed solutions can be determined. Selim's investigation is based on so-called goal-oriented adaptive finite element methods, which provide a general framework for the design of methods that ensure the necessary error control, such that accuracy can be determined. Based on the error estimate one may also design adaptive algorithms for efficient use of the computational resources.

Prior to the defence, at 10:15, Selim presented his trial lecture Multiscale problems and techniques.

The adjudication committee:

  • Professor Harald van Brummelen, Eindhoven University of Technology
  • Professor Thomas Grätsch, Hochschule für Angewandte Wissenschaften Hamburg
  • Joakim Sundnes, Simula Research Laboratory and the University of Oslo

Supervisors:

  • Anders Logg, Simula Research Laboratory
  • Harish Narayanan, Simula Research Laboratory
  • Trond Kvamsdal, NTNU
  • Nils Svanstedt, Chalmers

 

05.05.11:

On Thursday 5 May at 13:15, Kristian Valen-Sendstad successfully defended his PhD thesis "Computational Cerebral Hemodynamics".

Stroke is the third most common reason for death in the Western world. One type of stroke is caused by the rupture of an out-pouch of a blood vessel, called an aneurysm. As much as six per cent of us can develop aneurysms during our life time, and the number of incidences of stroke is on the rise.

Understanding the underlying processes of initiation, growth and rupture of aneurysms is of great importance to both a patient and society in general. Therefore, one has to gain detailed knowledge of blood flow and its effects on the blood vessel wall. Blood flow inside aneurysms has previously been believed to be stable and smooth. However, in Valen-Sendstad's thesis, it is proven through very high-resolution computational fluid dynamics that the flow can be complex and turbulent. This means that the cells inside the blood vessels, or aneurysms, might experience forces much stronger than previously assumed.

The rupture of aneurysms is known to occur more frequently in women than men. Measurements from the blood vessels of 55 patients undergoing angiography, were used to create idealised models of the female and male main blood vessel branches. The shear stress acting on the female blood vessel walls was found to be up to 50 per cent greater than that of the males, and could partially explain why more aneurysms develop and rupture in females.

Prior to the defence, at 10:15, Valen-Sendstad presented his trial lecture Fluid-structure simulations for biological flows.

The adjudication committee

  • Professor Francis Loth, Department of Mechanical Engineering, University of Akron, Ohio
  • Professor Atle Jensen, Department of Mathematics, University of Oslo
  • Professor Carsten Griwodz, Department of Informatics, University of Oslo

Supervisors:

  • Professor Hans Petter Langtangen, Simula Research Laboratory
  • Senior Research Scientist Kent-Andre Mardal, Simula Research Laboratory
  • Senior Research Scientist Anders Logg, Simula Research Laboratory
  • Professor Bjørn Anders Pettersson Reif, Norwegian Defence Research Institut

 

 

Successful midterm evaluation of CBC

The Research Council of Norway has published the results of the midterm evaluation of eight Centres of Excellence after three and half years of activity. The Centre for Biomedical Computing (CBC), hosted by Simula, is assessed as Exceptionally good and is secured funding for the next five years.

The midterm evaluation has been carried out by the Research Council of Norway, and involves the centre's self-evaluation, an assessment of the centre by three international experts, and an overall evaluation made by an interdisciplinary, international evaluation committee set up by the Research Council.

In the report made by the international evaluation committee, it is stated: "CBC is a perfect example of the benefits of the Centres of Excellence, in that the establishment of the Centre has created the opportunity for developing a much broader vision than originally planned (tools developed have wide-spread applications to coupled multiphysics problems) so that the Centre has already exceeded its original ambitions, and, in the process developed unanticipated new national and international collaborations."

The midterm evaluation report is available from the Research Council's website.

 

 

Several new major grants!

At the end of 2010, CBC researchers experienced great success with grant proposals. Kent-Andre Mardal, heading the Biomedical Flows and Structure project in CBC, succeeded with a proposal for the prestigious ERC Starting Grant, but due to budget limitations in the European Research Council, the Research Council of Norway contributed with funding. Joakim Sundnes, deputy manager of CBC, and Sam Wall, Postdoctoral Fellow at CBC, received a substantial grant from the eVita program in the Research Council of Norway. Sam Wall was also successful with a personal postdoc grant in the competitive FRIBIO program in the Research Council of Norway. Finally, Molly Maleckar, heading the Cardiac Computations project in CBC, Sam Wall, and Per Grøttum, Professor of Medicine, together with collaborators at the Oslo University Hospital and the GE company Vingmed Sound, managed to obtain the very prestigious grant Center for Research-Driven Innovation, 2011-2019, from the Research Council of Norway. The topic for this new center takes research from the Cardiac Computations project to clinical practice through new diagnostics, new equipment, and new treatment procedures.