Madison Chaos and Complex Systems Seminar

Fall 2001 Seminars

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

Short List


September 4, 2001

Revenge and emerging stories of hope

Harold Scheub, UW Department of African Languages and Literature

How storytellers take themes of revenge and transform these into stories of  hope: this takes us into the area of metaphor.  Storytellers move characters from realistic environments, in which human relations are cast in terms of anger and revenge, into storytelling (or fantasy, or metaphorical) environments, in which those emotions of anger and revenge are recast in terms of harmony and hope.  Storytellers look at life steadily, focusing on basic human emotions, and with the tools of the craft dissect those emotions and reconstitute them.  We shall study the art of the storyteller.

September 11, 2001

Human story-use to manage competition and cooperation: towards a basic science for psychiatry

Russell Gardner, Department of Psychiatry, Medical College of Wisconsin

There will be five parts, as follows:

I. Gell-Mann's dream for psychology/psychiatry

II. Four fundamentals for a basic science for psychiatry and related clinical human service disciplines.

III. R-theory for competition/cooperation; humans as the story-using animal

IV. Clinical illustrations from the forensic units at Mendota

V. Request to the group: would those assembled help me render these concepts in tune with Gell-Mann's dream?

September 18, 2001

Calculating climate effects on birds and mammals: Impacts on biodiversity, conservation, population parameters, and global community structure

Warren Porter, UW Department of Zoology

This paper describes how climate variation in time and space can constrain community structure on a global scale. We explore body size scaling and the energetic consequences in terms of absorbed mass and energy and expended mass and energy. We explain how morphology, specific physiological properties, and temperature dependent behaviors are key variables that link individual energetics to population dynamics and community structure.

This paper describes an integrated basic principles model for mammal energetics and extends the model to bird energetics. The model additions include molar balance models for the lungs and gut. The gut model couples food ingested to respiratory gas exchanges and evaporative water loss from the respiratory system. We incorporate a novel thermoregulatory model that yields metabolic calculations as a function of temperature. The calculations mimic empirical data without regression. We explore the differences in the quality of insulation between hair and feathers with our porous media model for insulation.

For mammals ranging in size from mice to elephants we show that calculated metabolic costs are in agreement with experimental data, We also demonstrate how we can do the same for birds ranging in size from hummingbirds to ostriches, We show the impact of changing posture and changing air temperatures on energetic costs for birds and mammals, We demonstrate how optimal body size that maximizes the potential for growth and reproduction changes with changing climatic conditions and with diet quality. Climate and diet may play important roles in constraining community structure (collection of functional types of different body sizes) at local and global scales, Thus, multiple functional types may coexist in a locality in part because of the temporal and spatial variation in climate and seasonal food variation. We illustrate how the models can be applied in a conservation and biodiversity context to a rare and endangered species of parrot, the Orange-bellied Parrot of Australia and Tasmania.

September 25, 2001 (In 5280 Chamberlin)

Nonlinear phase response curve in the human circadian oscillator

Ron S. Leder, Universidad Autonoma de Morelos (Mexico)

For at least the last 270 years there has been evidence that biological systems have endogenous periodic behavior, however scientists have regarded biological rhythms as mysterious. Today virtually all investigators agree that endogenous biological oscillators produce observable biological rhythms and the molecular mechanisms of these oscillators are now being elucidated.  A large class of biological rhythms has a period of about 24 hours and these are called circadian rhythms. This might not be a surprise given that our environment has a strong circadian light/dark periodicity. If allowed to free-run circadian rhythms may be a little longer or a little shorter than 24 h depending on the organism; diurnal or nocturnal. In order to provide an advantage for the organism, the oscillators should be able to adapt to a changing environment like changing period length and phase as happens with day and night through an annual cycle on most places on this planet. It turns out that most circadian rhythms can be photically synchronized to external light cues. This process is called entrainment. This means that the biological oscillators or clocks show nonlinear behavior and are reset daily by an external zeitgeber (from the German time giver) and do keep the organism’s rhythms in phase with its environment. This mechanism by which light entrains circadian rhythms has been investigated by application of discrete light pulses to organisms that are free-running in constant darkness and assessing the effects of the light pulses on the phase of the circadian rhythms. Brief light pulses cause phase shifts of free-running circadian rhythms. The magnitude and direction of the phase shift depends on when in the circadian cycle the light pulse is applied. This relationship between phase of zeitgeber and magnitude of phase of change is called the phase response curve, for light in this case. The purpose of this talk is to provide a brief introduction to biological rhythms so that the phase response curve can be understood in context I will also describe how “forward genetics” was used to identify the genetic loci per, and clock in the bread mold Neurospora, the fruit fly Drosophila, and the mouse. Once the genetic loci were identified the molecular species that make up the clock mechanism in a negative feedback loop for transcription were found.

The information for this talk came from a review of three books:

Biological Timekeeping (1982) edited by John Brady Cambridge University Press, Cambridge, UK.

The Clocks That Time Us (1982) Martin C. Moore-Ede, Frank M. Sulzman, and Charles A. Fuller, Harvard University Press, Cambridge, MA.

The eight chronobiology chapters of Principles and Practices of Sleep Medicine (2000) , Meir Kryger, Thomas Roth, William Dement eds. W. B. Saunders Co., Philadelphia.

This talk should provide a more applied background in which to understand circadian rhythms. The next step I would take is to look at the work of Glass and Mackay on phase resetting (Chapter six of their book From Clocks to Chaos) or something recent form Arthur Winfree in light of the recent knowledge about the circadian timing genes in the mouse. If I have time I will try to browse the web and report to you what’s new with the human phase response curve to light.

It may turn out that our Correlation, Chaos, and Complexity group will have some ideas about the implications of this information or about the biochemical chemical mechanism for entrainment of biological rhythms that is still under investigation.

In summary the topics of the talk are:

1. Endogenous biological rhythms
2. Characteristics and entrainment of circadian rhythms; photic and nonphotic zeitgebers
3. Genetic and molecular evidence of biological rhythms from Neurospora, Drosophila, and the mouse.

October 2, 2001

The coherence of turbulence

Fabian Waleffe, UW Department of  Mathematics

Turbulence in fluids is a common phenomena characterized by the erratic motion of fluid particles. Turbulence is also characterized by increased transport. It is natural to believe that these two characteristics are linked.  Indeed, most engineering turbulence models are based on the concept that macroscopic `randomness' leads to increased transport coefficients.  However, several decades of experiments have shown that the increased transport results from `coherent structures' embedded in a sea of disorder. Recently, traveling wave solutions of the governing equations have been obtained. The structure of these solutions is remarkably similar to the observed coherent structures and remarkably robust. The transport properties of these traveling waves are excellent, perhaps optimal.  The solutions are typically unstable, suggesting that turbulence may correspond to a strange repellor, not attractor.  Whatever the final answer will be, the exact coherent structures and their instabilities are key to elucidating the nature of turbulence.

October 9, 2001

Dirty children, unfaithful husbands and similar problems

Marty Isaacs, UW Department of Mathematics

There are certain fairly well known "brain teasers" or "logic puzzles" that share the property that a seemingly tiny input of information into a stable situation can cause a dramatic shift. We will discuss some of these problems and then a far-reaching generalization due to John Conway.

October 16, 2001

Cross-cultural dynamics of judgment, guilt, and forgiveness

Joe Elder, UW Department of Sociology

Studies of Judgment, Guilt, and Forgiveness (drawing largely from Jewish/Christian/Islamic roots) often operate on the assumption that the "judging" party, the "guilty" party, and the "forgiving" party all operate with the same set of cultural values. Acknowledgement of guilt by the "guilty" party and forgiveness of the "guilty" party by the injured party are often seen as necessary conditions for "reconciliation." But what if the "judging" party, the "guilty" party, and the "forgiving" party do NOT share the same cultural values? Is reconciliation possible? The complexities of such a situation are explored, and a Hindu/Buddhist alternative conceptual perspective is presented."

October 23, 2001

Dynamical analysis of bone elongation in children and adolescent animals

Norm Wilsman, UW School of Veterinary Medicine

For decades, the growth of kids has been marked by annual height measurements.  These are then compared by pediatrician and parent to standard growth curves, recently (2000) revised by the CDC.  These standardized growth curves are created by annual measurements of a large population of girls and boys.  These annual height measurements are then transformed by means of measures of central tendencies into
smooth growth curves.

More recently Lampl (Science '93), by measuring the height of kids daily, challenged the idea that the dynamics of rate of growth (in height) of children fit a smooth continuous curve.  Her analysis of change in daily height measurement suggested a pattern of growth by saltatory bursts that occurred over a few days followed by much longer periods of time where no growth or stasis occurred.  The pattern was non-predictable and non-recursive and for the first time suggested that bone elongation was something other than a continuous function.

Recently, we have implanted linear displacement microtransducers across the growth region of the tibia of adolescent lambs.  As control we implanted a second microtransducer across a non-growing region of the same bone.  As the bone elongates the positions of both microtransducers relative to a fixed point is recorded (by telemetry) once per minute.

Our hypothesis was that the position of the transducer would change in small short saltatory bursts followed by longer periods of no displacement to stasis.  Alternatively, displacement would be by a smooth curve.  The results we obtained were neither and by visual inspection suggest an underlying dynamical process with alternating transitional or chaotic states followed by steady states and only during this period of steady state, does the bone actually elongate. This pattern is repeated several times within a day but at unpredictable intervals.  Each growth period lasts an unpredictable amount of time and results in unpredictable amounts of growth.  We predict that the distribution of growth events and static events will have a fractal dimension.

We believe that this also suggests bone elongation proceeds as a non-linear dynamical system and that an understanding of this dynamical pattern is important for both understanding regulatory mechanism and therapies.  We will attempt to argue that this is logical, given what we and others have contributed to our current knowledge of the cell biology of bone elongation.

October 30, 2001

Bark beetles in conifers: How a boring life style can lead to complex interactions among insects, plants, fungi, and humans

Kenneth F. Raffa, UW Department of Entomology

Bark beetles are indigenous herbivores that breed in the subcortical sections of trees, and comprise a major source of mortality to conifers.  They are both important agents of natural ecosystem processes such as forest succession, and sources of severe economic losses and value-laden management challenges.  Trees are equipped with sophisticated preformed and inducible defenses for resisting bark beetles.  In turn, these herbivores have evolved complex mechanisms for overcoming these defenses, including social interactions mediated by chemical communication, and associations with specific fungi.  In order to reproduce, these beetles must kill host trees.  The outcomes of these interactions are discrete, yet they are governed by quantitative and conflicting rate processes.   Although the complexity of these interactions makes empirical research into the dynamics of bark beetle behavior and population dynamics a difficult challenge,  this complexity also provides some very specific environmentally compatible management approaches.

November 6, 2001

Chaos in magnetic fields

Leon Shohet, UW Department of Electrical and Computer Engineering

Magnetic fields have been used for many years in experiments to attempt to confine plasmas.  If magnetic confinement is successful, it could be used to produce energy by means of the fusion process in which a miniature star is produced inside the magnetic confinement region.  In order to do so, it was found that a simple spherical arrangement always leaves a hole in the magnetic field arrangement through which the plasma can leak out.  A cylindrical magnetic system, although perhaps the simplest of all, has two ends where the plasma can leak out.  The next simplest arrangement is to bend the cylinder into a torus.  This has been used for fusion-research experiments since the mid-1950s.  The magnetic fields are produced by various combinations of magnet coils and currents flowing in the plasma.  The fields are designed to travel around and around the torus tracing out nested closed toroidal magnetic surfaces.  Such surfaces can exist if there is an ignorable coordinate, so that the problem reduces to two dimensions.  In a real three dimensional torus, it has been found that there are regions of stochasticity in which a single magnetic field line samples a region that is bounded between regions of toroidal magnetic surfaces.  Once the confinement surfaces are formed, then plasma must be confined long enough for the fusion reaction to take place.  Limits to the confinement are often found where the plasma diffuses out of the toroidal confinement region too rapidly or the magnetic surfaces break open. Some plasma confinement schemes use combinations of both well formed magnetic surfaces and stochastic regions.  A key question to answer is why three-dimensional magnetic configurations can exhibit regions of stochasticity whereas two-dimensional configurations do not.

November 13, 2001 (In 5280 Chamberlin)

Analysis of memory T cell populations responding to a virally-derived peptide: An immunologist looks at modeling a complex system with possible fractal properties.

Jack Gorski, Blood Research Institute of Milwaukee

The response of T cells to antigen stimulation can be viewed as evolution by natural selection.  The unselected population is composed of single individual T cells, each identified by a unique receptor.  The shape of this T cell receptor (TCR), which is generated by a pseudorandom process, is the primary phenotype that defines fitness of the individual in the selection event. Selection by antigen results in generation of progeny and maintenance of the selected lineage as memory cells. We have analyzed the number and distribution of memory T cells involved in responding to a particular viral antigenic peptide.  Responsive T cells were identified by restimulation of a sample population in vitro with the antigen and by molecular analysis of the TCR beta chain gene. The 141 distinct responders identified showed a complicated frequency distribution.  134 of these, representing all but the seven highest frequency components, could be best modeled as a power law.  Interestingly, the exponent of decay was 1.6.  The distribution of the responding T cells can be described by a self-similar iterative process, indicating an underlying fractal nature of the response.  The repertoire itself can be subdivided on the basis of a number of molecular properties of the receptor.  In each case the distribution of the responding population showed a power law distribution. The biphasic nature of the distribution could indicate two different modes of memory cell selection. The significance of the possible fractal nature of the frequency distribution of memory T cells is not entirely clear.

November 20, 2001

Could language have evolved?

Chuck Snowdon, UW Department of Psychology

Recent popular treatments of human language and cognition proposing species-specific language instincts or cognitive modules are essentially neo-creationist (or Pan-creationist, if they admit the cognitive skills of some chimpanzees) models that are fundamentally at odds with evolutionary theory. Although often couched in evolutionary theory (in terms of species-specific adaptations) the models often fail to acknowledge any continuity between human and nonhuman animals and provide unsatisfactory hypotheses for what adaptive changes have led to the evolution of human traits so apparently different from those of other species.

The challenge is to develop models that acknowledge what is unique in human cognition and communication while at the same time demonstrating parsimoniously how these traits evolved. Since access to the cognitive and communicative skills of our hominid ancestors is at best sketchy through the archeological record, our best hope for success comes in use of the comparative method with extant species. There are two very different comparative approaches that are possible.

If one views cognition and communication as essentially hard wired neurological processes, then the best models are likely to be those species that are closest to humans in brain size and complexity such as the anthropoid apes or, possibly, cetaceans. Indeed these species display impressive cognitive accomplishments in tool use, in cultural-specific traits, group coordination in hunting, and possibly in teaching and taking the perspective of others. However, great apes are remarkably silent compared with chattering humans (and many other more vocal species) and therefore, to date, we have little information on the communication skills of apes to rival what we know of their cognitive skills.

An alternative approach is to view cognition and communication not as hard-wired processes but socially-constructed. By this approach our best hope for understanding complex cognition and communication is to look at species with similar social structure. Recently Sarah Blaffer Hrdy has argued (Mother Nature) that the available evidence suggests that humans are cooperative breeders. Thus few mothers can raise infants successfully without assistance from others. Both mothers and allo-mothers contribute to the nurturing and education of human infants. A direct corollary of this argument is that other cooperatively breeding species might display more complex cognitive and communicative skills and that these skills would be socially constructed.

Among nonhuman primates only marmosets and tamarins are cooperative breeders. Although they are phylogenetically remote from humans, there is much similarity in their social structure and infant rearing. Marc Hauser and his colleagues have demonstrated remarkable cognitive skills in tamarins. In addition, there is evidence of social learning of new skills and avoidance of noxious foods not seen in other monkeys, as well as imitation. Evidence from food sharing supports the idea that adults teach infants about food. Infant "babbling" in marmosets leads to improved communication skills. Marmosets show dialects in different populations and adults alter call structure when joining new groups. There are simple grammars and referential signaling. All of these findings suggest that at least some cognitive and communicative processes might emerge from species with social structure and rearing conditions similar to humans.

Although there are obvious differences in "hardware", the similarities in the "software" of social interactions may provide a fruitful focus for developing evolutionary models of human cognition and communication. (Supported by USPHS Grants MH29775 and MH00177)

November 27, 2001

Measuring Dynamical Entropy in Brownian Motion

Matt Briggs, UW Department of Physics

I'll report on our measurement of the trajctory of a single colloidal particle, and how we calculated from this a dynamical entropy.  I will discuss our claim that the scaling behavior of this entropy demonstrates the exitence of microscopic chaos.  Nature 394, 865-868 (1998), Comment and response Nature 401, 875-6 (1999), experiment details Physica A 296 (2001) 42-59.

December 4, 2001

Comparing classical and quantum complex systsems

Susan Coppersmith, UW Department of Physics

The fundamental insight that ``More is Different'' (Anderson, 1972) encapsulates much of the intellectual excitement of investigating systems with many degrees of freedom, particularly those that are far from thermal equilibrium.  This talk will discuss ``more quantum'' versus ``more classical,'' the relationships between nonequilibrium quantum complex systems and their classical analogs.

December 11, 2001

Complexity and self-organized criticality of a historical landscape

Janine Bolliger, Swiss Federal Research Institute

Self-organization is a process of evolution where complex structures emerge from a random disordered initial state through repeated application of simple rules.  By altering the rules and comparing the resulting patterns with those observed in nature, it is possible to test hypotheses about environmentally driven evolution in natural processes such as landscape pattern formation.

In this paper, a stochastic, two-dimensional cellular automaton with periodic boundary conditions was applied to a landscape pattern from southern Wisconsin prior to Euro-American settlement, consisting of general topological features such as prairies, savannas, open forests, and closed forests.  The cellular automaton evolves using one simple rule: At each time step, the content of each cell is replaced by one chosen randomly from some neighborhood of radius r.  This single-parameter model gives realistic time-varying landscapes for values near r = 5 km.

The increase in organization can be measured by the statistical distribution of cluster sizes and the fractal dimension of the patterns.  These topological properties are found to be independent of initial conditions and compare well with the same quantities calculated for the natural landscape. The results suggest that the simple rule suffices to explain major statistical and spatial characteristics of the observed landscape.