Madison Chaos and Complex Systems Seminar

Spring 2010 Seminars

All seminars are Tuesday at 12:05 pm in 4274 Chamberlin except as noted.

Short List

Join us for lunch during the summer on the Union Terrace at noon each Tuesday, starting May 11th!


January 19, 2010

An amazing freak wave

Chin H. Wu, UW Department of Civil and Environmental Engineering

Freak waves, alternatively called rogue waves or giant waves, are exceptionally large, steep, and asymmetric waves whose heights usually exceed by 2.2 times the significant wave height. They have also been described as “holes in the sea”, “walls of waters”, or three sisters! These waves have been long known to be notorious hazards to navigation vessels and marine structures. Many sinister marine episodes and their devastating impacts have prompted a great interest in freak waves. With little warning, freak waves often mysteriously occur as transient giant waves from wave groups in random coastal and open seas. While statistical methods are widely employed in examining the occurrence of such extreme sea conditions, it is still unclear whether freak waves are rare realization of a typical population or typical realization of a rare population. Likewise, it is unclear the physical mechanisms of freak wave formation and its characteristics. In this talk, we will report the recent laboratory measurements on limiting freak waves on currents. It is found that wave group structure is critical to determine the formation and the geometric properties of freak waves. Strong opposing currents inducing partial wave-blocking can significantly promote the freak waves, which occur often in the Great Lakes and Oceans.

January 26, 2010

Auditory activation with electric hearing: Studies on auditory plasticity in deaf humans

Ruth Litovsky, UW Department of Communicative Disorders

It is not uncommon for individuals who are deaf to undergo surgical treatment whereby they are fitted with cochlear implants (CIs). These devices send electrical stimulation to the auditory nerve in such a way that the brain can learn to interpret the stimulation, and CI users can effectively understand speech and enjoy the auditory world. Until recently, the standard of care had been to implant candidate patients with a single device in one ear. More recently, this standard has shifted such that two devices, bilateral CIs, are being provided to growing number of patients. Being able to hear with two ears affords humans functional abilities such as localization of sounds and segregation of sources from background noise. These abilities depend on binaural brain function, that is, on neural circuits that integrate inputs from the two ears with great precision. Our lab studies the emergence of binaural hearing abilities in children and adults who had experienced various periods of auditory deprivation prior to being activated with electric hearing. Our studies address questions regarding the ability of the auditory system to retain sensitivity to binaural hearing after deprivation. In addition, in children who have never heard with acoustic hearing, but whose brains are wired for acoustics, we study the ability of the brain to respond to electric stimulation such that the children attain age-appropriate abilities in domains of language, speech and hearing.

February 2, 2010

Complex families: Some implications of multiple partner fertility for research and policy

Maria Cancian, UW La Follette School of Public Affairs

We most often think of families with children as including a mother, father, and their children in common. However, 40 percent of children are now born to unmarried parents, and recent research suggests that more often than not, one or both of these parents will go on to have children with other partners. The complex families that result-- with siblings, half siblings and step siblings sharing parents and sometimes living quarters-- raise a host of challenges for research and policy. In this seminar I will draw on a series of papers, coauthored with Dan Meyer and other collaborators, to discuss the evolution of complex families and key related policy issues.

This talk is available as a PowerPoint Presentation.

February 9, 2010

Elegant chaos: Algebraically simple chaotic flows

Clint Sprott, UW Department of Physics

The quest for algebraically simple chaotic systems began fifty years ago when Ed Lorenz discovered chaos in a simple model of atmospheric convection. By now, dozens of chaotic systems, some even simpler than the celebrated Lorenz attractor, have been identifed and studied. This talk will describe a 20-year effort to find even simpler chaotic systems as summarized in a soon-to-be-published book by the same title in which 280 examples, most of which have never been previously published, are cataloged. Some new chaotic electrical circuits will also be described and demonstrated.

This talk is available as a PowerPoint Presentation.

February 16, 2010

Why doesn't my electricity come from the sun? Future photovoltaic materials for harnessing solar energy

Mike Arnold, UW Department of Materials Science and Engineering

The Earth is continuously bathing in over 1017 watts of sunlight. This talk will discuss the science, technology, and economics of using photovoltaic solar cells to collect and convert a fraction of this free solar energy into electricity. In particular, this talk will focus on the materials and composition of photovoltaic solar cells and the principles of their operation and will attempt to answer the question of why past and current solar cell technologies have failed to become widespread. The talk will conclude by discussing the future of solar photovoltaics and new materials and technologies (with a focus on those being pursued by my research group such as semiconducting carbon nanotubes) that have the potential to boost the efficiency, decrease cost, and increase the practicality of solar cells.

February 23, 2010

Pictures from piles of data
Michael Gleicher, UW Department of Computer Sciences

Most of my work is focused around a single (broad) question: How can we use our understanding of human perception and artistic traditions to improve our tools for communicating and data understanding? In problems ranging from molecular biology to video editing, we are faced with a deluge of data. In this talk, I'll survey some of the ways we've tried to turn this problem into solutions. I'll discuss our efforts in scientific visualization and multimedia, showing how we can use ideas from art and perception to create novel tools for a range of problems. Time permitting, I might also discuss some of my efforts to create a cross-disciplinary course on Visualization.

March 2, 2010

Overview of satellite-based aviation applications for detection of thunderstorms, turbulence, and volcanic ash

Wayne Feltz, UW Space Science and Engineering Center

The University of Wisconsin-Madison Cooperative Institute for Meteorological Satellite Studies (CIMSS) Satellite Nowcasting and Aviation APplication (SNAAP) team is heavily involved in research to develop satellite-based nowcasting tools (0-3 hour forecast) for improving aviation weather forecasting. Current areas of research focus on satellite detection of aviation hazards such as convection, turbulence, and volcanic ash using current and future weather satellite systems.  This seminar will overview this research as well as in context toward improvement of future air transportation route planning and warning for the general public.

March 9, 2010

Why we need to conserve crop diversity and what we need to know - An example from the Andes

Eve Emshwiller, UW Department of Botany

Dr Emshwiller will provide an overview of the value of crop genetic diversity and the kinds of information needed to conserve the diversity of crop plants and their wild relatives. An ongoing project in the Andes Mountains provides an example of research designed to provide information for conservation. The tuber crop “oca,” Oxalis tuberosa, is second to potatoes in the diet and farming systems of traditional agriculturists in rural highland communities of Peru and Bolivia. The crop is a polyploid, with eight sets of chromosomes. Dr. Emshwiller’s research has focused on finding out which wild Oxalis species may have hybridized to contribute oca’s several genomes, and studying how the exchange of planting material among farming families has affected the distributions of varieties of the crop.

This talk is available on video.

March 16, 2010

Exploring the conformational search leading to protein folding in vitro and in the cell

Silvia Cavagnero, UW Department of Chemistry

Proteins are key components of all living cells and their correct in vivo function is intimately connected to the well-being of every living organism. The large conformational freedom of a protein chain and its structural complexity suggests that understanding folding mechanisms and predicting protein structure from amino acid sequence may be dauntingly difficult. What have we learned from the studies carried out on protein folding mechanisms over the last three decades; are there any leading trends; and how do these trends change (or are predicted to change) for proteins folding in the cellular environment, where a lot of the relevant parameters are dramatically tuned by various cellular components? This talk will attempt to address some key aspects of the above topics and highlight research directions in crucial need of further exploration.

March 23, 2010

Emotional communication in primates: Music to their ears?

Chuck Snowdon, UW Department of Psychology

Vocal communication in nonhuman animals is thought to communicate the emotional state of the caller and provide information about the caller's behavior. An alternative view is that animal signals induce emotional states in listeners. In support of this alternative are the prosodic features of speech that humans use to communicate with infants ("parentese") or their animals ("doggeral"). Building on this idea, my collaborator, David Teie, a musician and composer and I have hypothesized that music evolved from emotional communication and is a powerful means to communicate emotions. We have hypothesized several acoustic features that are emotional universals and have tested these using music-naive cotton-top tamarins. Since tamarins communicate with higher pitch and faster tempo than humans, we also hypothesized that they would be indifferent to human based music, but would instead respond emotionally to music composed at their frequency range and tempo. Tamarins did show appropriate emotional responses to music composed for them by David Teie and were generally unresponsive to human music. The results have several implications: emotional aspects of music may have a long evolutionary history, animal vocalizations may serve to induce emotional contagion in listeners and, although musical aspects of emotions follow universal principles they actual music tested must be appropriate to the vocal range and tempo of the species tested.

This talk is available on video.

April 6, 2010

Running form modification: When self-selected is not preferred.

Bryan Heiderscheit, UW Orthopedics and Rehabilitation

While it is generally well accepted that an individual's patten of running is optimized to conserve metabolic energy, at times, this self-selection process may increase injury risk. That is, the selected pattern may be one that increases local joint loading and the potential for repetitive microtraumatic injury.  This is most evident in those just beginning to run as part of a regular exercise program. Using research and patient care findings, I will discuss how a simple modification to one's running gait can be an effective component to the treatment and prevention of common running-related injuries.

April 13, 2010

Shock waves in nature and in numerical computations

James Rossmanith, UW Department of Mathematics

Shock waves are propagating disturbances that are characterized by an abrupt, nearly discontinuous change in the characteristics of a fluid or plasma. They can occur in a variety of phenomena in both laboratory and natural settings. Mathematically, shock waves are difficult to handle since in general they are not unique solutions of the equations that model them. Computationally, shock waves are difficult to handle for several reasons: (1) most discontinuous cannot be exactly represented on a discrete mesh, (2) standard high-order methods are unstable for shocks, and (3) the numerical schemes must be carefully constructed to yield the physically correct solution.

In this talk I will begin by briefly reviewing the basic theory of shock waves. I will then, mostly through computational examples, describe the various pitfalls in trying to numerically solve equations with shock solutions. Finally, I will describe some strategies based on adaptive mesh refinement to obtain highly accurate numerical solutions.

April 20, 2010

The dynamics of performance management: Governance reform amidst complexity

Donald Moynihan, La Follette School of Public Affairs

Professor Moynihan examines efforts to make the public sector more focused on outcomes through performance measurement techniques.  Bureaucrats use the data for different purposes, and with different consequences, some unintended. This talk will summarize these reforms, their consequences, and the particular factors that affect how public actors use performance data.

April 27, 2010

Health and wealth over the life-cycle

Ananth Seshadri, UW Department of Economics

This talk presents a model of health investments over the life cycle. Health affects both longevity and provides flow utility. We analyze the interplay between consumption choices and investments in health by solving each household's dynamic optimization problem to obtain predictions on health investments and consumption choices over the lifecycle. Our model does a good job of matching the distribution of medical expenses across the households in the sample. We use the model to examine the effects of several policies on patterns of wealth and mortality.

May 4, 2010

Who wants to know? - The nature of our subjective "I"

Deric Bownds, UW Department of Zoology

Most cognitive neuroscientists are practicing Cartesian dualists in their daily lives, even while knowing that there is no distinction between our minds and bodies. They accept compelling modern experiments (as well as ancient religious insights) demonstrating that the 'self' or 'I' is a fiction, albeit a useful one we could not live without. It is a ancient fiction that co-evolved with a supportive neuroendocrine emotional repertoire to eventually generate social brains capable of scientific and artistic culture. The purpose of this talk is to outline a few central observations on the nature of this phenomenal self, how it is constructed with respect to the physical world and the social world of other humans.