Madison Chaos and Complex Systems Seminar

Spring 2007 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 15th!


January 23, 2007

Human Actions and a Changing Biosphere

Jonathan Foley, Nelson Institute for Environmental Studies

Human activities, especially land use, have been generally considered a local environmental issue, but they are becoming a force of global importance.  Worldwide changes to forests, farmlands, waterways and air are being driven by the need to provide food, fiber, water and shelter to over six billion people.  Global croplands, pastures, plantations and urban areas have expanded in recent decades, accompanied by large increases in energy, water and fertilizer consumption, plus significant losses of biodiversity.  Such changes in land use have enabled humans to appropriate an increasing share of the planet’s resources, but they also potentially undermine the capacity of ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate and air quality, and ameliorate infectious diseases.  We face the challenge of managing tradeoffs between immediate human needs and maintaining the capacity of the biosphere to provide goods and services in the long term.

January 30, 2007

Hurricane variability and trends in a changing climate

Jim Kossin, UW Department of Atmospheric and Oceanic Sciences

The relationship between global climate variability and hurricane activity is presently a topic of active research and debate – particularly since the 1995 Atlantic hurricane season, which apparently foreshadowed the beginning of a series of active Atlantic seasons after a period of relative inactivity from 1971 to 1994. The numerous hurricane landfalls in Florida during the 2004 season and the hyperactive Atlantic season of 2005 have further fueled speculation that the recent upswing in hurricane frequency is linked to increasing global temperature and concomitant upward trends in sea surface temperature (SST), which have been documented in all hurricane-prone ocean basins. Much of the debate regarding the existence of upward trends in hurricane metrics is rooted in questions about the suitability of the global data that has been used to identify these trends. Other debates regarding internal (natural) and external (anthropogenic) forcing of Atlantic climate on multi-decadal timescales are ongoing. I will introduce some of the main ideas that these debates are based on, and will present new evidence that Atlantic climate variability and its relationship to upward trends in hurricane activity may be unique when compared to the rest of the world.

February 6, 2007

Premotor cortex, action control, and language

Art Glenberg, UW Departments of Psychology and Educational Psychology

To effectively control action, the brain has evolved to solve a number of thorny problems: Learning complex action sequences with hierarchical structure, exquisite timing of movements (e.g., in tennis, piano playing, and walking) when sensory feedback may be too slow to help, and determining just what information in the sensory array might be useful. Interestingly, these same problems arise in learning and using a language. Might the brain use mechanisms of action control to learn, produce, and comprehend language? Recent findings of mirror neurons tuned for action and speech recognition in premotor cortex, Broca's area in particular, suggest a positive answer. In this talk, I will illustrate how a formal theory of action control, Wolpert's HMOSAIC model, can be easily modified to account for basic facts in language. Then, I will discuss the results of several projects testing theoretically derived claims regarding language acquisition, how manipulating the motor system affects language comprehension, and how manipulating language comprehension affects the motor system.

February 13, 2007

Fetal programming of a complex women's health disorder: polycystic ovary syndrome

David Abbott, UW Department of Ob/Gyn and Wisconsin National Primate Research Center.

Polycystic ovary syndrome (PCOS) afflicts about 10% of women in their reproductive years, yet its origins and genetic basis in humans remain unknown. PCOS is multi-faceted and has considerable heterogeneity in its phenotype: ovarian and adrenal testosterone excess, intermittent or absent menstrual cycles, polycystic ovaries, increased miscarriage, obesity, type 2 diabetes, cardiovascular disease, chronic inflammation, endometrial cancer, sleep apnea and depression. It would therefore appear that this complex syndrome most likely has multiple pathological mechanisms. The establishment of a nonhuman primate model for PCOS, however, suggests a single developmental origin for the syndrome: fetal testosterone excess. This talk will discuss the unique insight gained into a complex human disease process from the study of its developmental progression in animal models.

February 20, 2007

Simple models of complex chaotic systems

Clint Sprott, UW Department of Physics

A complex system is one with many parts that interact nonlinearly and that exhibits self-organization, adaptation, and chaos. Such systems are ubiquitous in fields as diverse as ecology, economics, meteorology, and sociology. This talk will describe several such systems and will include a tutorial on how to model them in the most general sense. It will conclude with new examples of extraordinarily simple models that exhibit complex and perhaps universal behavior.

This talk is available as a PowerPoint presentation.

February 27, 2007

Nitrogen cycling in the Wisconsin River floodplain

Emily Stanley, UW Center for Limnology

Human activities often increase nitrogen (N) concentrations in streams and rivers. In turn, excess nitrogen in water has been associated with a range of environmental problems, including human health concerns associated with high-N drinking water and low oxygen concentrations (hypoxia) in coastal waters fed by nutrient-rich rivers. Nutrient-rich waters of the Mississippi Rivers have created such a hypoxic zone in the Gulf of Mexico, which has spurred interest in identifying management approaches to reduce N losses from Midwestern watersheds. In this context, we have been studying N cycling in the Wisconsin River and its floodplain to determine if floodplain environments in particular can reduce the rivers N load, and how N cycling is regulated in floodplains. I will discuss some of the complexities of the nitrogen cycling in floodplains, and how human activities have constrained their potential to reduce watershed N losses.

March 6, 2007

Hermes: God of complexity theory?

Dennis Merritt, The Integral Psychology Center

Many of the anicient Greeks knew the gods weren't real but the effects of many powerful forces from within and without were very real. Personifcations of these forces were recognized as the gods and goddesses and the dynamics personified as attributes of Hermes can now be described largely by complexity theory. Hermes is the god of alchemy, Jungian psychology, ecopsychology and certainly of the genius of a psychoanalyst, D. W. Winnicott. Jungian analyst George Hogenson has been instrumental in reframing Jung's basic concepts of word association, archetypes, the Self and synchronicity within the framework of complexity theory.

March 13, 2007

Modeling and mapping human influence on California fire regimes

Alexandra Syphard, UW Department of Forest Ecology and Management

 Periodic wildfire is an important ecological process in the Mediterranean-climate shrublands of California. However, altered fire regimes threaten ecosystem integrity, create hazards for people, and increase fire suppression expenditures. From a biophysical perspective, fire is influenced by the climate, terrain, and fuels in a region. However, humans are now the dominant cause of ignitions in California (and elsewhere), which also affects fire frequency and spatial pattern. There is growing awareness that fire management should be adapted to both the human and ecological landscape characteristics that vary from region to region; however, it is first necessary to understand how humans influence fire and why fire patterns vary. I will present the results of two research projects in which we used a combination of biophysical and anthropogenic variables to model human influence on fire at a broad scale (state of California) and a landscape scale in southern California, where we also mapped where fires are most likely to occur. In both of these studies, we found that humans significantly affect fire frequency, and fire ignitions are most likely to occur close to human infrastructure. On the other hand, area burned is more a function of the biophysical setting, and fires spread more when they’re farther from human infrastructure because there is greater fuel connectivity. Understanding both the human and the biophysical factors that determine fire patterns will be necessary for managers to anticipate where fires are most likely to occur.

March 20, 2007

Cooperative learning in cooperatively breeding monkeys
Charles T. Snowdon , UW Department of Psychology
 Commonly we think that species closest to humans should be most similar in cognition and behavior, due to greater similarities of brain size and brain structure. An alternative view is that species sharing similar social structures may be more similar in cognitive skills involving social interaction. Our group has been studying the cooperatively-breeding tamarins and marmosets, small monkey from the neotropics which lives in family groups and where all family members assist in child care, vigilance and locating food. These monkeys learn quickly from observing each other, behave cooperatively when two individuals must work together to solve a problem and demonstrate reciprocal altruism. They show rudimentary aspects of teaching and in the wild show variation in food selection and communication possibly indicative of “culture”. In many of these tasks, marmosets and tamarins exceed the abilities of chimpanzees, our closest biological relatives.

This talk is available on video.

March 27, 2007

Nuclear power, the obvious solution to many environmental problems

Max Carbon, UW Department of Engineering Physics

The pros and cons of nuclear energy as a source of electricity will be discussed.  Among the topics will be the phenomenal safety record of nuclear power over its entire lifetime; the huge benefit it offers in terms of handling its wastes; its beneficial effects on the environment such as zero release of  carbon dioxide;  the thousands of lives it saves yearly in Wisconsin and elsewhere;  the fact that nuclear electricity is cheaper than coal electricity, and much cheaper than natural gas and renewable electricity; and the fact that, while nuclear proliferation is a very serious problem, it is essentially unrelated to nuclear power.  The talk will end with the vision of relatively-pollution-free battery driven automobiles, charged nightly by almost-pollution-free nuclear electricity.

This talk is available as a PowerPoint presentation.
See also Prof. Carbon's downloadable book, Nuclear Power: Villian or Victim.

April 10, 2007

The relationship between West African dust outbreaks and Atlantic hurricane activity

Amato Evan, UW Space Science and Engineering Center

It is well known that Atlantic tropical cyclone activity varies strongly over time, and that summertime dust transport over the North Atlantic also changes from year to year, but any connection between these tropical storms and atmospheric dust has been limited to a few case studies. Here I report new results that demonstrate a strong connection between interannual variations in North Atlantic tropical cyclones and atmospheric dust cover as measured by satellite, for the years 1982–2005. I will also discuss the physical mechanisms that may be underlying these observations; including links between ocean temperature, the West African monsoon, and vegetation changes across the Sahel.

April 17, 2007

Coevolution, cooperation and complexity

Cameron Currie, UW Departments of Bacteriology and Zoology

Symbiotic associations, the living in close intimate association of unlike organisms, has shaped the history of life on earth and helped generate biological complexity. The fungus-growing ant–microbe symbiosis is an outstanding example of coevolution between microbial symbionts and their hosts resulting in unique innovations and a high degree of biocomplexity. The ants tend their fungal mutualist, providing it with optimal conditions for growth. In exchange, the fungus serves as the main food source for the ants. The origin of this mutually beneficial interaction is likely more than 45–65 million years ago. In addition to the ants and their fungal crops, the gardens of fungus-growing ants are host to specialized and virulent fungal pathogens in the genus Escovopsis. Extensive molecular phylogenetic analyses of the garden pathogen reveal both an early origin and tightly coevolved relationship with the ants and their fungal mutualist. To deal with the pathogen the ants have evolved a mutualistic association with filamentous bacteria (actinomycetes) that produce antibiotics that suppress the growth of Escovopsis. The mutualism between fungus-growing ants and their antibiotic-producing actinomycetes also has an early origin. I will discuss the role of symbiotic associations in shaping biological complexity and the possibility that complex multipartite associations could help explain the evolutionary stability of mutually beneficial associations.

April 24, 2007

Population games and evolutionary dynamics

William Sandholm, UW Department of Economics

Population games provide a general model of strategic interactions among large numbers of agents; highway congestion, multilateral externalities, and natural selection are among their many applications. As the direct assumption of equilibrium play seems difficult to justify in population games, behavior is most naturally modeled as a dynamic adjustment processes. To accomplish this, we begin with an explicit stochastic description of how individual agents make decisions. When the number of agents is large enough, the evolution of aggregate behavior is well approximated by solutions to ordinary differential equations. We discuss various classes of population games in which these evolutionary dynamics lead to equilibrium play. We also consider simple examples in which cycling and chaos can arise.

May 1, 2007

Interpreting a snapshot of gene expression in a living cell

David Brow, UW Department of Biomolecular Chemistry

For a cell to use the information stored in its DNA genome, it must first make an RNA copy of the DNA. This is the job of an enzyme called RNA polymerase (RNAP). How does RNAP "know" what bits of the genome to copy at any given time? We approached this question by asking where RNAP is concentrated on each of the 16 chromosomes of brewer's yeast cells that are growing happily in rich medium. We collected data for the entire 12 million base pair (bp) genome at a resolution of about 100 bp. Surprisingly, there is some RNAP bound almost everywhere in the genome, but this "basal" level does not appear to result in RNA accumulation. Genes that are strongly expressed have lots of RNAP on them, and RNAP is excluded from genes that are actively turned off, as expected. But we see lots of "peaks" and "valleys" of RNAP that are not over known genes. Are these cases of experimental noise, biological noise, newly discovered genes, or none of the above? I will describe what we have learned so far.

May 8, 2007

Midge Madness! Quantifying linkages between lake and land

Claudio Gratton, UW Department of Entomology

Recent empirical and theoretical models indicate that the dynamics within food webs are often influenced by resources coming from outside of the focal food web, also termed a “spatial subsidy”. Lake Mývatn is a eutrophic lake in Northern Iceland with an exceptional natural phenomenon of large-scale chironomid midge (aquatic insect) outbreaks that occur every 5-7 yr in which densities increase over 4 orders of magnitude. We used this lake and the surrounding landscape to examine the effect that large-scale spatial subsidies have on terrestrial arthropod food webs. Our studies have shown that by moving from lake onto land, the midges act as two types of subsidies. First, they can transfer as much as 70 kg N and 10 kg P ha-1 yr-1 to a 100-200m wide area surrounding the lake, resulting in increased plant quality, biomass and increased detritivore and herbivore abundance. Second, they subsidize the food base of the natural enemies (mainly spiders) on the terrestrial shoreline. As a result, food web interactions on land are significantly affected by the adjacent lake ecosystem, effects that have the potential to propagate over the long-term, even after midge abundances subside.

See publicity photo