SOft MAtter Theory Group Meeting @ SU
Fall 2011
| Date | 30 miutes | 10 minutes 1 | 10 minutes 2 |
| 12-Sep | Lisa Manning | discussion of meeting format | |
| 19-Sep | Alan Middleton | Xu Ma | Shiladitya Banerjee |
| 26-Sep | Jorge Lopez | Yaouen Fily | Mark Bowick |
| 3-Oct | David M. | Jen Schwarz | Bryce |
| 10-Oct | Moumita Das | Duan Duan Wan | Cristina |
| 17-Oct | Zhenwei Yao | Sean Sweeney | Silke Henkes |
| 24-Oct | Xu Ma | Shiladitya Banerjee | Arun Ramachandran |
| 31-Oct | Yaouen Fily | Lisa Manning | Tao Zhang |
| 7-Nov | Jen Schwarz | Bryce | Cristina Marchetti |
| 14-Nov | Duan Duan Wan | Mark Bowick | Alan Middleton |
| Thanksgiving break | |||
| 28-Nov | Sean Sweeney | Silke Henkes | Moumita Das |
| 5-Dec | Shiladitya Banerjee | Arun Ramachandran | David M. |
| 12-Dec | Mark Bowick | Tao Zhang | Jorge Lopez |
| Winter Break |
| Date | 30 miutes | 10 minutes 1 | 10 minutes 2 |
| 23-Jan | Cristina | Lisa Manning | Zhenwei Yao |
| 30-Jan | Silke Henkes | Alan Middleton | Xu Ma |
| 6-Feb | Liang Cao | Moumita Das | Yaouen Fily |
| 13-Feb | Guest seminar: Dapeng Bi, Brandeis University Stress fluctuations in shear jammed granular materials A wide range of systems including granular materials, colloidal suspensions and glassy molecular systems can undergo a process known as the jamming transition. This is the transition between a fluid-like state (un-jammed) and a solid-like state (jammed). The jamming concept has gathered intense research interests in recent years. In the jamming phase diagram proposed by Liu & Nagel for athermal systems, jamming is induced only through compression, and jammed states exist above a critical density. Recent experiments in frictional disks clearly show shear induced jamming. In my talk, I will explore the various features of these new jammed states. I will also present a statistical ensemble based approach which takes into account unique properties of shear-jammed states as well as the strict constraint set by jamming in general. Local stress distributions predicted from this theoretical framework will be compared with experimental data. |
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| 20-Feb | March meeting practice | ||
| 27-Feb | March meeting | ||
| 5-Mar | Guest seminar: Ana Hocevar, Jozef Stefan Institute Space-filling problems in simple animal tissues We theoretically investigate simple animal tissues and cell aggregates using the elastomechanical theory of phospholipid vesicles based on vesicle bending energy and a model intermembrane adhesion energy. We first study the one-cell-thick epithelium tissue whose en face view resembles a polygonal tiling. We show that the structure of simple epithelia can be explained by an equilibrium model where energy-degenerate polygons in an entropy-maximizing tiling are described by a single geometric parameter that encodes their roundedness . Both the ordered and the disordered tilings found numerically closely reproduce the patterns observed in Drosophila, Hydra, and Xenopus. This model is free of a specific cell self-energy, cell-cell interaction, and cell division kinetics, and thus provides an insight into the universality of living and inanimate two-dimensional cellular structures. We also study periodic three-dimensional assemblies of identical lipid vesicles as models of simple bulk tissues. In this theory, each vesicle is represented as a convex polyhedron with flat faces, rounded edges, and rounded vertices. In the limit of strong adhesion, the minimal- energy shape of cells minimizes the weighted total edge length. We compare several candidate space-filling polyhedra to find that the oblate shapes are preferred over prolate shapes for all volume-to-surface ratios. The model is then extended to aggregates of vesicles whose adhesion strength on lateral faces is different from that on basal and apical faces. In addition, we study gastrulation, a morphogenetic process that takes place during embryonic development of animals. We focus on gastrulation in Drosophila melanogaster and use a simple two-dimensional model based on undifferentiated cells of identical properties whose energy resides in their membrane. Numerical results reproduce the experimentally observed invagination. |
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| 12-Mar | Spring break | ||
| 19-Mar | Tao Zhang | David Mayett | Jen Schwarz |
| 26-Mar | Sven Wijtmans | Jorge Lopez | Duanduan Wan |
| 2-Apr | Xingbo Yang | Zhenwei Yao | Sean Sweeney |
| 9-Apr | Dhagash Bharatbhai Mehta | Xu Ma | Shiladitya Banerjee |
| 16-Apr | Lisa Manning | Yaouen Fily | Mark Bowick |
| 23-Apr | Cancelled | ||
| 30-Apr | Alan Middleton | Jen Schwarz | Cristina Marchetti |
| 7-May | Moumita Das | Duanduan Wan | Silke Henkes |
| 14-May | David Mayett | Sean Sweeney | Liang Cao |