MIT Free English Class is for international students, sholars, spouses. Twenty seven years ago we created a community to welcome the nations to MIT and assist with language and friendship. Join our Tuesday/Thursday conversation classes around tables inside W11-190.

Ten minutes for your mind@2:50 every day at 2:50 pm in multiple time zones:Europa@2:50, EET, Athens, Helsinki (UTC+2) (7:50 am EST) https://us02web.zoom.us/j/88298032734Atlantica@2:50, EST, New York, Toronto (UTC-4) https://us02web.zoom.us/j/85349851047Pacifica@2:50, PST, Los Angeles, Vancouver (UTC=7) (5:50 pm EST) https://us02web.zoom.us/j/85743543699Almost everything works better again if you unplug it for a bit, including your mind. Stop by and unplug. Get the benefits of mindfulness without the fuss.@2:50 meets at the same time every single day for ten minutes of quiet together.No pre-requisite, no registration needed.Visit the website to view all @2:50 time zones each day.at250.org or at250.mit.edu

Speaker: Johan Asplund (Stony Brook)

Colloquium on the Brain and Cognition with Joni Wallis, PhD, University of California, BerkeleyDate: Thursday, May 8, 2025Time: 4:00pmLocation: 46-3002, Singleton Auditorium (Third floor of MIT Building 46)Zoom: https://mit.zoom.us/j/92722264638&nbspTalk title and abstract to come.

Speaker: Graeme Milton (University of Utah)Title: Guiding Stress: From Pentamodes to Cable Webs to Masonry StructuresAbstract: Pentamode materials are a class of materials that are useful for guiding stress. In particular, they have been proposed for acoustic cloaking by guiding stress around objects and have been physically constructed. A key feature of pentamode materials is that each vertex in the material is the junction of 4 double cone elements. Thus, the tension in one element determines the tension in the other elements, and by extension uniquely determines the stress in the entire metamaterial. Here we show how this key feature can be extended to discrete wire networks, supporting forces at the terminal nodes and which may have internal nodes where no forces are applied. In usual wire or cable networks, such as in a bridge or bicycle wheel, one distributes the forces by adjusting the tension in the wires. Here our discrete networks provide an alternative way of distributing the forces through the geometry of the network. In particular the network can be chosen so it is uniloadable, i.e. supports only one set of forces at the terminal nodes. Such uniloadable networks provide the natural generalization of pentamode materials to discrete networks. We extend such a problem to compression-only 'strut nets' subjected to fixed and reactive nodal loads. These systems provide discrete element models of masonry bodies. In particular, we solve the arch problem where one wants the strut net to avoid a given set of obstacles and also allow some of the forces to be reactive ones. This is joint work with Ada Amendola, Guy Bouchitte, Andrej Cherkaev, Antonio Fortunato, Fernando Fraternali, Ornella Mattei, and Pierre Seppecher.