Madison Chaos and Complex Systems Seminar

Spring 2014 Seminars

All seminars are Tuesday at 12:05 pm in 4274 Chamberlin Hall except as noted. Refreshments will be served.

Short List
Join us for lunch during the summer on the Memorial Union Terrace at noon each Tuesday, starting May 13th!

Abstracts

January 21, 2014

Can entropy be thought of as a fluid in biological systems?

Jim Reardon, UW Department of Physics

Climb into an automobile and drive in any direction on the highway of your choice, and in anywhere between a few minutes and a few hours, you'll find that your automobile refuses to go any farther. You could reasonably say that this is because it has run out of energy. You might wait for a while by the side of the road, and then try to start the car again, but it won't work. Since you're now stranded in the middle of nowhere, you now have a good opportunity to try this experiment: after doing appropriate warm-up exercises, start sprinting as fast as you possibly can (presumably in the direction of the nearest gas station). In something less than 40 seconds, your legs will refuse to carry you any farther, and you will either slow down or fall down. Yet if you lie there for a while by the side of the road, and then try to sprint again, you'll find that you can, nearly as well as before. It cannot be said that you have run out of energy. It might perhaps be said that you have temporarily accumulated too much entropy, and have to wait a while for it to dissipate. Whether or not this is a reasonable statement depends on whether entropy can be thought of as a fluid. In this seminar I'll argue that the answer is "yes" and support the argument with quantitative phenomonological data.


January 28, 2014

Fractals for kids

Clint Sprott, UW Department of Physics

This is a tale of how a physics professor at a major research university came to write a coloring book for children. What better way to learn about fractals than to actually try to draw one by hand? I will explain what fractals are, survey some of the many ways of making fractal images, and show lots of pretty (colored) pictures. Suitable for all ages.

This talk is available as a PowerPoint presentation.


February 4, 2014

Predicting fate

Jim Blair, Milton and Edgewood College

Large quantities of agrochemicals are applied to farm fields every year.  What happens to them?  How are they transported and transformed?  How long do they last in the soil?  How rapidly do they move through soil to reach the ground water?  Where do they end up?

This has been studied after the chemicals have been applied.  In this talk I will describe the development of a series of laboratory procedures that attempt to predict the environmental fate of new agrochemicals before they are applied.

Topics include:

Radio-labels and Liquid Scintillation Counting
The Three Faces of Fate
Material Balance
Does History Matter?
MCPA, Dow, and St. Croix
Factory Farms and Frankenfoods

 Predicting fate

February 11, 2014

How does dark matter interact with us?

Yang Bai, UW Department of Physics

Dark Matter occupies about one quarter of the total energy of our Universe. Additional interactions between dark matter and ordinary matter beyond the gravitational one may exist. In this talk, I will discuss how much we have learned about all dark matter interactions with us.


February 18, 2014

Direct imaging of the nearest habitable planets

Margaret Turnbull, Global Science Institute

In the last twenty years, exoplanetary science has revolutionized the study of planetary systems and how they form -- and the next key goal motivating exoplanetary science is to discover and characterize exo-Earths. This talk will review (1) where we stand currently with habitable planet detection, (2) the reasons to attempt a direct imaging mission and the surprising multitude of factors that play into designing such a mission, and (3) what we could conceivably learn about life in the neighborhood of the sun with current and near-term technology. Although this young field has generated intense public interest and yielded thousands of surprising results, we may have barely scratched the surface of what the universe has to offer.
 

February 25, 2014

Roving the Red Planet:  A field geologist explores gale crater on Mars

Rebecca Williams, Planetary Science Institute

On August 5, 2012, NASA’s Mars Science Laboratory rover Curiosity landed in northwest Gale Crater.  With the most sophisticated suite of scientific instruments ever employed to investigate the Martian surface housed within a mini-Cooper-sized rover, Curiosity has been assessing the character of the ancient environments based on examination of clues contained within rocks.  In this presentation, Williams will discuss why Gale Crater was selected as the landing site, the ingenious ‘sky-crane’ landing system developed for this mission, how the science team participates in daily operations from their home institutions, and science results after one year of surface activities.


March 4, 2014

The relationship between obesity, genetics, nutrition, environment and metabolic diseases

James M. Ntambi, UW Departments of Biochemistry and of Nutritional Sciences

Obesity has reached epidemic proportions globally as a major public health problem, and in developing countries often coexists with conditions of widespread under-nutrition. In addition to being a contributor to the global burden of non-communicable diseases that include type 2 diabetes, coronary heart disease, hypertension, osteoarthritis, fatty liver disease, inflammation, sleep apnea and certain cancers, obese individuals of all ages suffer serious social and psychological consequences. Obesity is a multifactorial condition stemming from a combination of genetic, dietary, and environmental factors and the interaction between these components. This article discusses the relationship between genetics, nutrition, environment and non-communicable diseases as risk factors of obesity and highlights available evidence and arguments for increased research on the genetics of metabolism.


March 11, 2014

Variability, uncertainty, and vulnerability in our chaotic climate

John Young, UW Department of Atmospheric and Oceanic Sciences

Climate and weather are part of a chaotic continuum which impact our world through variability, predictive and statistical uncertainty, and damaging extremes. In this talk I will illustrate these issues with examples from observed atmospheric temperature and precipitation patterns and time behavior.

Weather chaos naturally extends to slow variations and often power-law spectra. The probability distributions of temperature differ strongly from those for precipitation, which yield power law distributions at the extreme range. Impacts often result from extreme states which exceed threshold values. Since extremes are typically estimated with large uncertainty, ecological impacts are similarly estimated for a finite range of probability. An example of a physical constraint on extreme precipitation will be given: the "1,000 year flooding rain".


March 25, 2014

Managing complexity at the molecular scale

Tehshik Yoon, UW Department of Chemistry

Chemical synthesis inflects every aspect of modern life. Everything from the clothes we wear to the food we eat to the medicines that so many of us take on a daily basis benefit from the products of chemical synthesis. Chemistry has been able to have such a profound impact on human life because of chemists’ ability to construct complex organic molecules with precisely defined three-dimensional shapes. In this talk, I will attempt to explain what some of the most interesting challenges and opportunities are in contemporary organic synthesis.


April 1, 2014

Modeling issues in emergency medical services and their implications

Laura McLay, UW Department of Industrial and Systems Engineering

In this talk, I will discuss issues that affect models for optimally allocating scarce resources for public services (such as fire and emergency medical services) including issues involving performance benchmarks, equity, natural disasters, and the modeling of human servers in queuing models. I will include stories from my research and from the field.


April 8, 2014

Algorithms, complex systems and chaos

Jerry Tutsch, UW Department of Computer Sciences

Computer programs consist of large collections of interacting algorithms. They are prime examples of complex systems. The recent advent of cheap, fast, small computers has led to an explosion of very complex programs that must remain easy to use. To a large extent, it is the ease-of-use constraint that is driving up the level of complexity. The programs generally have a direct-manipulation user interface, as opposed to a simple text-based interface. They are nonautonomous, that is event-driven. 

Additional technical constraints drive up the complexity. The program's component parts may be distributed over various computers and they may be executing at different times. Furthermore the programs may need to be able execute on different platforms which themselves change over time as operating systems and hardware is updated.  Even with the help of software development tools, an increasingly difficult task facing the software engineer is that of controlling and managing the complexity of a program over its lifetime as it inevitable grows in functionality and size.

In the parlance of  dynamical systems, as perhaps best defined in Math and Physics, computer programs in general are extremely complex nonautonomous t-advancing iterative maps defined on discrete phase spaces of high dimension.

Over the past several years, as an experiment to learn more about controlling and managing the complexity of computer programs, I have been writing a program designed to help students visualize the complexity and chaos that emerges when small nonlinear dynamical systems, in the form of differential equations and iterative maps, evolve in time. In the course of writing the program, I came to the realization that the program itself was a meta dynamical system. 

I will discuss how a program's complexity is controlled and managed in theory. Time permitting, I will also demonstrate how the complexity arises and is managed in practice.

See Introduction and Outline.


April 15, 2014

Criticality and information flow in an adaptive system

Bryan Daniels, Wisconsin Institute for Discovery

In physical systems, boundaries in parameter space that separate different large-scale behavior correspond to phase transitions, where small changes in microscopic parameters lead to drastic changes in macroscopic observables. We use fine-grained data about conflict in a macaque society to ask whether this social system is located near a phase transition. We find using two models (an equilibrium Ising model and a dynamic branching process model) that the system is near but below a transition, indicating that aggression dissipates quickly enough to avoid becoming typically widespread, but not so quickly that large fights are impossible. A relation between thermodynamics and information theory shows that being near the transition implies that it is easier for an observer of fight sizes to infer changes in individual proclivities to fight. More generally, this points to the possibility of quantifying a system's collective behavior by measuring the degree to which information can percolate among different spatial scales.


April 22, 2014

Now you see him, now you don’t — a hitchhiker’s guide to high dimensional data analysis

Ming Yuan, UW Department of Statistics

The analysis of high-dimensional data now commonly arising in scientific investigations poses many statistical challenges not present in smaller scale studies. In this talk, I will survey some main ideas and problems, in particular, in recovering high dimensional sparse signals and estimating large matrices — two classes of problems that have attracted much recent interests in a range of fields including statistics, applied math and electrical engineering. Time permitting, I will also discuss their implications in other scientific domains.


April 29, 2014

Event detection in the Twittersphere

Adel Ardalan, UW Department of Computer Sciences

Twitter has gone viral over the past few years, both in terms of the volume of posted messages and the number of users. People talk about real-world events on Twitter before events start, during the events and after they are finished. In many applications, it is desirable to monitor the Twitter stream and detect the interesting events people are discussing. In this talk, we define and motivate the event detection problem and suggest a model for detecting emerging, dynamic, interesting events. We discuss the challenges we have faced in building a system to generate candidate events based on the aforementioned model in a timely manner and how we have addressed them. Our experiments show promising results both in terms of accuracy of our detection and also the response time of the system.


May 6, 2014

20th Anniversary Celebration

We will celebrate the 20th anniversary of this weekly seminar with a look at the questions asked across the years and the questions that the audience wants to see answered now. What have we learned, and what's next? Bring your thoughts! The webpage contains abstracts of the twenty years of talks.

See photos taken at this seminar.