2009 Advanced Laboratories Conference Abstract Detail Page
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||A Knots Experiment
||Understanding how knots form and untie is crucial in understanding the biophysics of DNA or the structural properties of polymers, but it is very difficult to study these processes directly. This experiment studies the dynamics of knots in granular chains (the type used to hold drain plugs) on a plate vibrating at varying frequencies and amplitudes. These chains are interesting in their own right, and the subject of a number or recent papers in Physical Review Letters and other major research journals.
Students explore how the unknotting time of the chain depends on different parameters such as length, frequency, amplitude, linear mass density, and number and type of knots. They can also examine the statistics of the unknotting process, study the radius-of-gyration and pattern formation in unknotted chains, and investigate other aspects of the shaker and its dynamical relation with a chain (or other materials) on its surface. The phase space of possible measurements is very large, so students can explore many ideas of their own. The experiment is a bit noisy, but is simple, inexpensive, and easy to use. The challenge for the student is in the planning and analysis, and in having enough patience to take sufficient data.
The basic apparatus for the experiment will be demonstrated at the workshop. More information can be found at www.physics.utoronto.ca/~phy326/knot/.
Download the Contributed Poster
||Session IX - Effective Experiments Poster Session
David C. Bailey
University of Toronto
60 St. George Street
Phone: 416-978-6674 or -4993
Jason J. B. Harlow, Physics Department, University of Toronto
Natalia N. Krasnopolskaia, Physics Department, University of Toronto
Stephen W. Morris, Physics Department, University of Toronto