27 May 2018: A visit by Ken Stephenson
Ken Stephenson (University of Knoxville TN) came to visit me for a week in Aberystwyth. Apart from the mountain biking:
We also spent some time discussing circle packings and their applications to problems in physics:
5 Septemeber 2017: Two visits to Cambridge
This month I will be attending two workshops in Cambridge, the first is the 2nd Edwards Symposium - which concentrates on bringing scientists from the soft matter community together with people from industry. The second work shop is at the Newton institute and is titled Form and deformation in solid and fluid mechanics.
22 July 2017 The Packing of Continua
This summer I visited the programme entitled “The Packing of Continua” at Aspen, details below. Probabily one of the best meetings I have ever been to… plenty of time for discussions and not too heavy on talks - perfect!
June 11 - July 2 The Packing of Continua
Organizers:Gregory Grason - University of Massachusetts, Eleni Katifori, University of Pennsylvania, L. Mahadevan - Harvard University, Jennifer Schwarz - Syracuse University
Packing problems have been at the core physical descriptions of matter dating back to at least the time of Kepler. This workshop will bring together researchers from diverse fields working to understand packing of filaments and sheets in three-dimensional space. In comparison to problems of packing compact and rigid elements, the consequences of the more subtle interplay between shape and separation of continuously deformable, extended objects on their space-filling arrangements and collective behaviors at high density are far less understood. And this, despite the diverse applications of filament and sheet packing problems to current challenges in biology and materials science, from the fractal packing of condensed chromosomes to the design of 2D metamaterials. The scope of the workshop will cover recent advances in characterizing, understanding and optimizing multi-filament/sheet assemblies, as well as frontier questions stemming from new observations and emerging challenges in biological and synthetic matter.
Here are some obligatory conference pictures:
6 April 2017: Visit to Mohan Srinivasarao
Next week I will be visiting Georgia Tech in Atlanta USA, where I will be collaborating with Mohan Srinivasarao. I will also be giving a talk on packing hard (and soft) spheres in cylinders.
23 Aug 2016: New preprint: Phyllotaxis, disk packing and Fibonacci numbers.
Phyllotaxis, disk packing and Fibonacci numbers
A Mughal and D Weaire
We consider the evolution of the packing of disks (representing the position of buds) that are introduced at the top of a surface which has the form of a growing stem. They migrate downwards, while conforming to three principles, applied locally: dense packing, homogeneity and continuity. We show that spiral structures characterised by the widely observed Fibonacci sequence (1,1,2,3,5,8,13...), as well as related structures, occur naturally under such rules. Typical results are presented in a animation.
See http://arxiv.org/abs/1608.05824 for full details
7 Jul 2016: EuFoam 2106
At the recent EuFoam conference I gave a talk entitled "Curvature driven motion of soap cells in toroidal Hele-Shaw cells”. In the talk I presented work that will be published in an upcoming paper.
1 Apr 2016: Vladimir Khodygo
Jointly with Martin Swain in IBERS we have a new PhD student working with us on problems relating to active matter and bacterial swarms
3 Jul 2015: Bacteria, liquid crystals and active matter
Yesterday I gave a presentation to the group of Chris Creevey at IBERS:
http://www.aber.ac.uk/en/ibers/staff/chc30/
Title: Bacteria, liquid crystals and active matterShort Abstract: Swarms of bacteria represent examples of what is know as active matter. Active matter describes a system whose constituent elements consume energy to move. When these objects interact with each other, collective behavior can emerge that is unlike anything possible in ordinary matter. In this talk I will give an idiosyncratic overview of bacteria from a physicists point of view that should be accessible to anyone.
31 Dec 2013: New preprint! Theory of cylindrical dense packings of disks
see: http://arxiv.org/pdf/1312.7429v1.pdf
We have previously explored cylindrical packings of disks and their relation to sphere packings. Here we extend the analytical treatment of disk packings, analysing the rules for phyllotactic indices of related structures and the variation of the density for line-slip structures, close to the symmetric ones. We show that rhombic structures, which are of a lower density, are always unstable i.e. can be increased in density by small perturbations.