Aorta: structure to rupture

Decorative image from a video showing predicted flow through aortic valve and resultant stress in leaflets of valveRegular readers have probably already realised that I have very broad interests in engineering from aircraft and power stations [see ‘Conversations about engineering over dinner and haircut‘ on February 16th, 2022] to nanoparticles interacting with cells [see ‘Fancy a pint of science‘ on April 27th, 2022].  So, it will come as no surprise to hear that I gave a welcome address to a workshop on ‘Aorta: Structure to Rupture‘ last week.  The workshop was organised in Liverpool by one of my colleagues, with sponsorship from the British Heart Foundation, and I was invited to welcome delegates in my capacity as Dean of the School of Engineering.  It was exciting on two levels: speaking, for the first time in more than two years, to an audience who had travelled from around the world to discuss research. And because the topic was closely associated with cardiac dynamics, which is a field that I worked in for nearly twenty years until around 2006.  I was part of an interdisciplinary team modelling the fluid-structure interaction in the aortic valve as it opens when blood is pumped through it by the heart and then closes to prevent back flow into the heart.  The team dispersed after I moved to the USA in 2004.  So speaking to the workshop last week was something of a trip down memory lane for me and led me to look up our last publication in the field.  I was surprised to find it was cited seven times last year.

The image in the thumbnail is a snapshot from a video showing the predicted time-varying distribution of blood flow through the aortic valve and the resultant distribution of stress in the leaflets of the valve during a heart beat.  The simultation is described in our last publication in cardiac dynamics: Carmody, C. J., Burriesci, G., Howard, I. C., & Patterson, E. A.,  An approach to the simulation of fluid–structure interaction in the aortic valve. J. Biomechanics, 39(1), 158-169, 2006.

Unrecognised brilliance of shy and fearless leaders

Red tulips in a window boxAre you a quiet person? Perhaps shy would be an appropriate description. Do you have a clear vision of where you would like to lead your organisation but perhaps you are hesitant about stepping forward into a leadership position because you think that successful leaders are bold, self-confident, large-than-life and enjoy the limelight. You should think again. Research by Jim Collins and his team, published in the Harvard Business Review, has shown that the most powerfully transformative leaders have a paradoxical mixture of personal humility and professional resolve. They found that companies were transformed from a merely good performance to a sustained great performance in terms of their stock value only when led by a CEO who was both self-effacing and fearless. They called these class of people, level 5 leaders. They are ambitious for their organisation not themselves, assign credit for successes to others while accepting the blame for failures and have an unwavering resolve to do whatever is necessary to achieve the best long-term results despite the obstacles. So, if you worry that you lack the charisma to inspire your team then pause and consider whether you might be a level 5 leader with the rare combination of modesty and willfulness that, Jim Collins has suggested, are required to transform the performance of your organisation. Unfortunately, if you think you possess these characteristics then you almost certainly are not a level 5 leader because your humility would never allow you to entertain the thought!


Jim Collins, Level 5 Leadership: The Triumph of Humility and Fierce Resolve, Harvard Business Review, January 2001.

Exploiting complexity to help society adapt

photograph of a flower for decorative purposes onlyI am worried that engineering has become a mechanism for financial returns in an economic system that values profit above everything with the result that many engineers are unwittingly, or perhaps in a few cases wittingly, supporting the concentration of wealth into the hands of a few capitalists.  At the start of the industrial revolution, when engineering innovation started to make a difference to the way we live and work, very few engineers foresaw the impact on the planet of the large scale provision to society of products and services.  Nowadays most engineers understand the consequences for the environment of their work; however, many feel powerless to make substantial changes often because they are constrained by the profit-orientated goals of their employer or feel that they play a tiny role in a complex system.  Complex systems are often characterised by self-organisation in which order appears without any centralised control or planning and by adaptation to change and experience.  Such systems are familiar to many engineers and perhaps they do not, but should, think of the engineering profession as complex system capable of adaptation and self-organisation in which the actions and decisions of individual engineers will cause the emergence of a new order. Our individual impact might be tiny but by acting we influence others to act and the cumulative effect will emerge in ways that no one can predict – that’s emergence for you.

Collaboration and competition

Close-up picture Californian Redwood trees showing some fallen trunks and branches amonst living treesCompetition has become a characteristic of many activities in life, whether it is teams vying to win a trophy, universities attempting to be top of a league table, retailers trying to persuade you to buy from them, or politicians seeking power. Natural selection is often cited to demonstrate that competition is ubiquitous in nature and therefore something to be embraced and celebrated as a route to success. However, Suzanne Simard has highlighted that competition is only part of Darwin’s theory of natural selection. It was popularised following the publication of his book ‘The Origin of Species’ in 1859; however, Darwin also wrote about the ways in which plants co-operate and collaborate and Simard believes that collaboration is ‘as important, if not more important’ than competition in the development of ecosystems. Trees may have a better chance of adapting to climate change because they are adapting faster than us.  A number of mass movements of plants are in progress – the fastest appears to be the northwards migration of white spruce trees in the eastern US which have moved 100 km every decade for the last thirty years. Perhaps it is time to apply some more comprehensive biomimetics to the organisation of society at all levels and consider how greater levels of collaboration rather than competition would help us tackle the challenges facing civilisation.


Henry Mance, Lunch with the FT: Suzanne Simard ‘I say to the trees, “I hope I’m helping”‘, FT Weekend, 26 March / 27 March 2022.

James Bridle, The speed of a dandelion, FT Weekend, 2 April / 3 April 2022.