Chaos and Complex Systems Seminar
Spring 1997 Seminars
Dates, speakers, titles and abstracts will be listed as they become
available. Meetings will be noon Tuesdays in 4274 Chamberlin Hall
unless otherwise noted.
- 21 January. Steering Committee Meeting.
- 28 January. Fred Brauer: ``A Simple Model
for Increasing Returns in a Competitive Economic Market.''
- 4 February. Clint Sprott: ``A Fractal View
- 11 February. Paul Milewski: ``Waves
Generated by Water Flowing over a Bump.''
- 18 February. David Newman:
``Self-organization in Nature: from Sandpiles to Plasmas.''
- 25 February. Ray Kent: ``Sounding Off in
First Year of Life: The Complex System of Infant Vocalization.''
- 4 March. Jon Foley: ``Exploring Dynamic
Interactions Between Ecosystems and the Atmosphere.''
- 11 March. David Griffeath: ``Digital
- 18 March. Grace Wahba: ``How to Smooth
Curves and Surfaces, or, Statistical Model Building with
in Demographic Risk Factor Estimation, Climate, and Numerical
- 1 April. Ann Palmenberg: ``Structural
vs Thermodynamics in the Evolution of Viral RNA Genomes. Part 1:
Optimal RNA Folding: Thermodynamics of Genomic vs Randomized
- 8apr. Ann Palmenberg: ``Structural Chaos
Thermodynamics in the Evolution of Viral RNA Genomes. Part 2:
Suboptimal RNA Folding: Thermodynamics and the Evolution of RNA
- 15 April. Bob Wilson: ``A Closer Look at
the Mandelbrot Set.''
- 18 April. Seminar of possible
interest: Scott Camazine: ``House-hunting by Honey
Individual Behaviors to collective decisions.''
- 22 April. Robert Jeanne: ``Social Insects
are Self-Organized Biological Systems.''
- 29 April. Cosma Shalizi: ``Watching
(Digital) Pots Boil, and Other Exciting Things.''
- 6 May. John Cameron: ``A Proposed Model
Imagination and Creativity.''
21 January. Steering Committee Meeting
28 January. Fred Brauer, UW Math: ``A Simple
Model for Increasing Returns in a Competitive Economic Market.''
The possibility of multiple equilibria in competitive markets with
increasing returns has long been troublesome to economists. A
stochastic model proposed by Brian Arthur to explain this
was one of the early successes in the study of complex systems,
to much discussion of the economy as an evolving adaptive system. In
fact, the crucial breakthrough was the willingness to consider a
dynamic model rather than an equilibrium model, not the introduction
Uninhibited by knowledge of either ecomomics or complex adaptive
systems, we formulate a simple deterministic dynamic model (i.e.,
two-dimensional autonomous system of differential equations) which
be analyzed by an easy geometric argument to show similar
4 February. Clint Sprott,
Physics: ``A Fractal View of the World.''
Since the time of the ancient Greek philosophers, we have been
that the geometry of lines and surfaces and solids is the proper
description of the world. Recently, a new type of geometry has
in which the fundamental objects are "fractals." Fractals have
non-integer dimension and self-similar structure on all scales.
objects such as rivers, mountains, clouds, and plants are best
described by fractal geometry. Examples of fractals will be shown,
methods will be described whereby you can generate fractal patterns
11 February. Paul Milewski,
Math: ``Waves Generated by Water Flowing over a Bump.''
When a fluid flows over a bump, the surface of the fluid will be
affected (we have all watched a stream flowing over rocks). In this
talk we will discuss models that have been derived to study this
problem, and show some simple solutions that can be obtained from
As the models become more involved (and presumably describe the
more accurately), numerical solutions show a wealth of behavior:
waves, periodic solitary wave generation, and more complex flows.
will be an introductory talk, assuming no prior knowledge of fluid
18 February. David Newman, Fusion Energy
Division, Oak Ridge National Lab: ``Self-organization in Nature:
Sandpiles to Plasmas.''
In nature there are many systems which exhibit some form of
self-organization. Among these are forest fires, earthquakes,
and even life itself. Investigations into the similarity of the
dynamics of such systems have been undertaken by using simple
automata models. These models have produced a remarkable amount of
insight into the dynamics of such systems. Recently a Self-Organized
Criticality (SOC) model for turbulent transport in magnetically
confined plasmas has been proposed in order to explain some of the
observed features of the transport dynamics in these plasmas. The
features of SOC systems, from forest fires to earthquakes, the
extension to a sandpile model for turbulent transport and potential
methods for control of SOC systems will be discussed.
25 February. Ray Kent, UW Communicative
Disorders: ``Sounding Off in the First Year of Life: The Complex
of Infant Vocalization.''
CANCELLED due to an unfortunate illness; Dr. Kent's
talk will be re-scheduled later in the semester.
Abstract: Beginning with the birth cry and proceeding
through grunts, babbles, and maybe first words, the typical infant
accomplishes a number of vocal milestones in this so-called
``prespeech'' period from birth to one year of age. This talk
some recent perspectives from complex systems theory as they
4 March. Jon Foley, UW Atmospheric and
Sciences: ``Exploring Dynamic Interactions Between Ecosystems and
No abstract yet.
Abstract: A colorful slide show will survey the theory of
discrete growth dynamics. For the simplest cellular automaton
growth models one can identify a linear speed of spread and
convex asymptotic shape. Only slightly more complex local rules give
rise to nonconvex chapes, dendritic crystals, fractal patterns, and
other complex phenomena. We will also briefly discuss recent work on
the ``reverse shape'' attained by basic automata just before they
18 March. Grace Wahba, UW
Statistics: ``How to Smooth Curves and Surfaces, or, Statistical
Building with Applications in Demographic Risk Factor Estimation,
Climate, and Numerical Weather Prediction.''
Abstract:We begin by describing the popular cubic smoothing
spline as a tool for fitting smooth curves to noisy data, and go on
describe generalizations of the variational problem it solves. These
generalizations can be used to build flexible models for discrete,
noisy observational data in such diverse fields as analysis of
demographic studies of risk factors for heart attacks and diabetic
retinopathy, extracting patterns from global historical surface
temperature records that may be relevant to global warming, tuning
imperfect dynamical systems models of the atmosphere and ocean, and
1 April. Ann Palmenberg, UW Animal Health and
Biomedical Sciences: ``Structural Chaos vs Thermodynamics in the
Evolution of Viral RNA Genomes. Part 1: Optimal RNA Folding:
Thermodynamics of Genomic vs Randomized Sequences.''
Did you ever wonder why most complex genomes are encoded by DNA? As
informational context, RNA surely predates DNA by any evolutionary
measure. Yet today, only certain genomically simple, highly
viruses still use RNA as their genetic format. We have found the
informational complexity of single-stranded viral RNA genomes is
by a delicate balance between biological selective pressures and the
thermodynamics of RNA folding. Energetically plausible alternative
configurations punctuate and dominate these genomes, creating
regions topological disorder. The observed pattern of permissible
in the thermodynamics of RNA folding suggests that information
conversion to DNA (topologically linear) was an evolutionary
for larger genome organization.
8 April. Ann Palmenberg, UW Animal Health and
Biomedical Sciences: ``Structural Chaos vs Thermodynamics in the
Evolution of Viral RNA Genomes. Part 2: Suboptimal RNA Folding:
Thermodynamics and the Evolution of RNA Genomes.''
See abstract for 1 April above.
15 April. Bob Wilson, UW Math: ``A Closer
Fractals and the Mandelbrot Set.''
Abstract: It is one thing to say that the ``dimension'' of
such as the Sierpinski Gasket should be more than 1 but less than 2,
should it be 1.58496...? Magazines and coffee-table books have
of the Mandelbrot Set, and we can even ``dive'' into it using
software, but what is it and how is it produced? This talk will
answers questions like these, with no attempt at mathematical rigor:
mathematics will be used beyond high school algebra.
18 April. Seminar of Possible
Interest: Scott Camazine, Dept. of Entomology, Penn
``House-hunting by Honey Bee Swarms: from Individual Behaviors to
Unusual time and place: Entomology seminar, Friday, 3:30 pm
150 Russell Labs.
Bob Jeanne writes: ``Camazine has done some of the best work on
self-organizing systems, especially insect group behavior. Much of
has been with honey bees, but he has investigated non-social
well. ... Scott will be available most of Friday and Saturday to
anyone interested in meeting with him. Please let me know if you
some time with him (2-0899; firstname.lastname@example.org).''
22 April. Robert Jeanne, UW Entomology and
Zoology: ``Social Insects are Self-Organized Biological Systems.''
No abstract yet.
29 April. Cosma Shalizi,
Physics: ``Watching (Digital) Pots Boil, and Other Exciting
Digital boiling is one of a large class of celluar automata
which model excitable media, such as cardiac tissue, neurons, fires,
aggregating cellular slime molds, and chemical oscillators. After
customary three-sentence explanation of what a cellular automaton
I'll talk about the history and use of CA in studying excitable
in general. Finally, I will discuss some recent findings about
boiling in particular, trying to make them both understandable and
interesting to non-mathematicians. Technology permitting, the talk
be accompanied by animations of the CA and of physical excitable
6 May. John Cameron, UW Medical Physics: ``A
Proposed Model for Imagination and Creativity.''
In this talk I will propose a model for imagination and creativity
based on known physical and chemical principles. The model does not
depend on a detailed understanding of the memory or reasoning powers
the brain. I will suggest the use of pulsed magnetic fields to
the imagination. I will describe a simple type of computer
I will describe an analogy between imagination and mutations in
and animals. I will suggest a possible inverse relation between
and imagination. Finally, I will discuss some possible experiments.
Up to the Chaos and Complex Systems Seminar
Last change worth mentioning Mon Apr 28 16:35:04 1997