Computations in Science Seminars
Wednesdays at KPTC
206, unless otherwise specified
The Kersten Physics Teaching Center is on the
corner of 57th Street and Ellis Avenue.
Discussion over bag-lunch at 12:15 PM.
Talk starts at 12:30 PM.
- September 10, 2008
- Konstantin Turitsyn, University of Chicago
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e-mail:
- Vesicle Dynamics in External Flows
- Dynamics of vesicles in external flows has been a subject
of great experimental and theoretical attention recently.
A vesicle can exhibit a variety of different dynamical behaviors
when placed in an external flow. At least three qualitative
different motions have been observed in recent experiments:
tumbling, tank-treading, trembling. I will review these experiments
and will present a theoretical analysis of this effect, resulting in a
phase-diagram which predicts the type of the vesicle motion. For
planar external flows, the character of the vesicle dynamics is determined
by two dimensionless parameters, which are formed out of viscosities of
inner and outer fluids, external velocity gradient matrix and
vesicle excess area. Transitions between different types of
motions are analyzed separately. The tank-treading to tumbling
transition is described by a saddle-node bifurcation whereas the
tank-treading to trembling transition occurs via a Hopf
bifurcation. In the vicinity of the transition lines the vesicle
experiences critical slowing down, which can be described
universal scaling exponents. In the end of the talk I will also discuss
the effect of vesicle wrinkling in extensional flows.
- September 17, 2008
- Michael Marder, University of Texas
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e-mail:
,
Faculty contact: Leo Kadanoff,
- Student Flows in Texas
- Texas, like all other states, has been gathering test data on public school students for many years. What can one do with test records from 4 million students? I have been visualizing math test scores using ideas loosely borrowed from statistical mechanics and fluid mechanics. The visual representations give a more complete picture than is obtained by focusing on single numbers. They make it possible to address questions about the relative importance of income levels, race, and other factors in the Texas public K-12 educational system, and about whether testing pressure is improving educational performance. I will also comment on local, state, and national efforts in which I have been involved to better educate science and mathematics teachers.
- September 24, 2008
- Lee Smolin, Perimeter Institute for Theoretical Physics
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e-mail:
,
Faculty contact: Leo Kadanoff,
- Quantum Gravity as a Problem in Critical Phenomena
- Several current approaches to quantum gravity construct or derive models of quantum spacetime as discrete quantum systems on dynamical lattices. The key problem to be resolved in these models is whether and how classical spacetime arises from a discrete quantum system. This problem of the emergence of spacetime in the low energy limit is thus a problem in critical phenomena. I will introduce some of the models of quantum spacetime of current interest and illustrate the progress being made using them towards the problem of the emergence of classical spacetime. I will emphasize an important question, which is currently the subject of experimental probes, which is the symmetry of the ground state: is it Poincare, broken Poincare or quantum deformed Poincare?
- September 29, 2008
(Joint seminar with MRSEC: 12:30 in KPTC 206)
- Itai Cohen, Cornell University
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e-mail:
,
Faculty contact: Leo Kadanoff,
- October 1, 2008
- Doug Smith
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e-mail:
,
Faculty contact: Leo Kadanoff,
- October 8, 2008
- Leo Kadanoff, University of Chicago
-
e-mail:
- Problems in Geometry and Analysis in 2-D: Fun with Charges and Eigenvectors
- There is a simple, exact solution to the problem of how charge arranges itself on the surface of a conductor. Put discrete charges on a pointy surface and you have a problem in modern mathematics.
- There is a simple, exact solution to an eigenvalues problem for a matrix M(j,k) when that matrix is constant along any diagonal and its indices run from minus infinity to infinity. Make the matrix finite but large and you have a problem in modern mathematics.
- We (Hui Dai, Zachery Geary, LPK) attacked this problem by constructing eigenvectors for a particular case in which the infinite matrix is singular. The matrix indices run from 0 to N-1; we construct exact eigenvectors for the analogous problem with indices running from zero to infinity. We then speculate about the general form of these vectors in the finite-N case. The speculations are mostly verified by comparison with exact calculations of eigenvectors.
- October 15, 2008
- Dmitri Talapin, University of Chicago
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e-mail:
- October 22, 2008
- Berni Alder, Lawrence Livermore National Laboratory
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e-mail:
,
Faculty contact: Leo Kadanoff,
- October 29, 2008
(^)
- Petia Vlahovska, Dartmouth College
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e-mail:
,
Faculty contact: Wendy Zhang,
- November 5, 2008
(^)
- Benoit Roman, Ecole Superieure de Physique et de Chimie Industrielles
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e-mail:
,
Faculty contact: Tom Witten,
- November 12, 2008
(^)
- Pedro Reis, Massachusetts Institute of Technology
-
e-mail:
,
Faculty contact: Ka Yee Lee,
- November 19, 2008
- (open date)
-
- November 21, 2008
(Special Seminar: 12:30 in KPTC 206)
- Detlef Lohse, University of Twente
-
e-mail:
,
Faculty contact: Leo Kadanoff,
- December 3, 2008
- V. Ramanathan, University of California, San Diego
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e-mail:
,
Faculty contact: Leo Kadanoff,
- January 7, 2009
- (open date)
-
- January 14, 2009
- Marcelo Magnasco, Rockefeller University
-
e-mail:
,
Faculty contact: Leo Kadanoff,
- January 21, 2009
- Margaret Gardel, University of Chicago
-
e-mail:
- January 28, 2009
- Aaron Dinner, University of Chicago
-
e-mail:
- February 4, 2009
- (open date)
-
- February 11, 2009
- Daniel Rothman, Massachusetts Institute of Technology
-
e-mail:
,
Faculty contact: Leo Kadanoff,
- February 18, 2009
- (open date)
-
- February 25, 2009
- (open date)
-
- March 4, 2009
- (open date)
-
- March 11, 2009
- (open date)
-
- March 18, 2009
(During APS March Meeting)
- (open date)
-
- March 25, 2009
- (open date)
-
(&) : When Wendy Zhang is unavailable for
the seminar.
(^) : When Leo Kadanoff is unavailable for the
seminar.
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