Complexity Digest 2000.16 April-29-2000

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"I think the next century will be the century of complexity." Stephen Hawking


1. Lightning Studies May Provide Earlier Tornado Alerts, Science Daily
It's been a year almost to the day, but NASA researcher Dr. Steve Goodman still hasn't forgotten May 3, 1999.

On that date, more than 50 tornadoes cut a killer swath across the Great Plains of Kansas and Oklahoma. Property damage was estimated at $1.2 billion. More than 40 people died.

In hope of avoiding another May 3, 1999, Goodman and other scientists at the Global Hydrology and Climate Center, managed by NASA's Marshall Space Flight Center in Huntsville, Ala., are studying new methods of predicting severe storms.

And they believe another dangerous element of severe weather may be the key.

Using a combination of ground and space-based weather monitoring equipment, Goodman and colleagues at the National Oceanic and Atmospheric Administration in Washington, D.C., and at MIT Lincoln Laboratories in Lexington, Mass., have documented nearly a dozen cases in which lightning rates increased dramatically as tornadic storms developed.

"Our studies show a very big spike in the lightning's flash rate prior to formation of a tornado," Goodman says. "It's an early clue for weather forecasters to take a more detailed look at other storm characteristics with radar. And perhaps a chance for them to get warnings out earlier, saving more lives."

Goodman's team will present its research to scientists, meteorologists and emergency management officials from around the country at the "National Symposium on the Great Plains Tornado Outbreak of 3 May 1999," which opens April 30 at the Westin Hotel and Resort in Oklahoma City.

Spotting the telltale lightning flashes isn't as easy as keeping an eye on the sky from your front porch. According to Goodman, the type of lightning NASA is researching occurs within clouds, invisible to the naked eye by day. To properly monitor this type of lightning takes special equipment like NASA's Lightning Imaging Sensor, an instrument flying aboard the Tropical Rainfall Measuring Mission (TRMM) satellite launched in 1997. The sensor tracks worldwide lightning strikes and their relationship to storm centers.

Theories linking in-cloud lightning and tornadic storms have been debated for many years, according to Goodman. For decades, meteorologists and scientists pondered the connection. "But they lacked the ability to properly document and map in-cloud lightning," he says. "With the technological advances we've made in recent years, we can see what they couldn't."

Goodman is realistic about the work that remains ahead. "We don't have enough data yet to say how often the high flash rate precedes tornado formation," Goodman says. "But looking at this lightning signature can help pinpoint storms that are likely candidates, and that can make a big difference."

That difference would provide earlier warnings to increase citizens' chance of reaching shelter, and would likely reduce the number of false alarms that go out every year.

"Lead time for tornado warnings is better than it's ever been," Goodman says. "It's gone from eight to 12 minutes nationally. But the false-alarm rate hasn't changed. Only 30 percent of rotating storms ever make a tornado. That leads to a lot of false alarms lulling the public into ignoring the threat."

"It's a question of accuracy," he adds. "The more accurate we are, the more people take the proper response. That's what this research is all about."

Goodman's presentation, "May 3 Tornadic Supercells Viewed from Space During an Overpass of the NASA TRMM Observatory," will be May 1 at 4:10 p.m. CDT. The Great Plains Symposium runs through Wednesday, May 3 -- the anniversary of last year's devastating tornado outbreak.

The Global Hydrology and Climate Center is a joint venture between government and academia to study the global water cycle and its effect on Earth's climate. Funded by NASA and its academic partners and jointly operated by NASA's Marshall Space Flight Center in Huntsville, Ala., and the University of Alabama in Huntsville, the Center conducts research in a number of critical areas. Satellite tracking of hurricanes promises to improve global severe-weather forecasting capabilities; research into lightning activity is providing new insight on tornado formation; and NASA remote sensing technologies explore new ways to improve the health of our cities, aid farm productivity and identify outbreaks of disease.

2. Nature's Cycles In A Fractal State Of Mind, Rochester Univ/Science Daily

Weather, battery life and even the way your lawn grows are all linked by four mathematical laws, according to a paper published in the April 3rd Physical Review Letters. Yonathan Shapir and Jacob Jorné of the University of Rochester have shown how natural cyclical events, such as seasonal weather, generate very specific patterns-the same patterns that govern the geometric images called fractals.

Fractals are mathematical designs that repeat their patterns on infinitely smaller scales: No matter how much you magnify a fractal, the same patterns appear. These patterns can be created over time. As sediment builds up on a surface, for instance, the tiny irregularities in the first layer become larger and more exaggerated in successive layers as they are laid down. Scientists have shown previously that many structures in nature, from lightning bolts to cauliflower heads, produce this fractal pattern, but the new findings are the first to demonstrate that the fractal patterns hold true for nature's next level of complexity, cycles.

"Often things are not formed by a single process, but by a combination of growth and recession," explains theoretical physicist Shapir. "What's amazing is that so many growth and recession cycles can be described by just a few fractal solutions."

Fractal solutions-equations with numbers that create fractal patterns-can help predict events that are based on natural cycles that build up and break down materials over and over, explains Jorné, professor of chemical engineering. Jorné and Shapir expect that fractal equations can help physicians estimate the spread of cells that grow and recede, such as a tumor in a chemotherapy patient. They also expect that the life span of car batteries can be predicted faster and more cheaply because engineers will be able to extrapolate the data from a few charge cycles to thousands. Even predicting such seemingly random things like how your lawn will spread may be possible by measuring rain and light cycles and matching them to the proper equation.

"This work shows that there are some basic laws underlying many of nature's cycles," says Jorné. "They may not be obvious, we may not see the connections at first, but underneath it all the same patterns are running."

Jayanth Banavar, head of physics at Penn State University and an expert on fractal phenomena, said, "This work is very exciting and opens entirely new avenues for future investigations. Besides its scientific interest, this work promises to have important technological ramifications." Jorné first approached Shapir with a simple question: Would natural cycles create fractal patterns?

"I had a hunch they would," says Shapir. It took him several months of mathematical tinkering, however, before he discovered the right approach. "The hardest nut to crack was how to make a certain, very complicated mathematical framework fit this experiment." That complex framework, known by the equally complex name "Renormalization Group Theory," helps reveal fractal-like properties in equations, and earned its developer the Nobel Prize in physics in 1982. "Once we understood how to apply it to cycles, everything fell into place in a matter of days."

Shapir and graduate student Subhadip Raychaudhuri used a computer to run cycle simulations. Tiny objects were randomly deposited on different types of surfaces. After each deposition, the researchers simulated a process, like water erosion or battery discharge, that removed some of the objects in an equally random way. After running the simulations tens of thousands of times, Shapir and Raychaudhuri found that no matter what the type of objects, forces or surfaces involved, each of the simulations could be described by fractal solutions. As each new layer of objects was laid down, its surface became more and more irregular, repeating the same basic shapes on larger and larger scales, just like a fractal.

With the simulation results in hand, Jorné and David G. Foster, a former graduate student and senior engineer at Eastman Kodak Co., designed an experiment that deposited atoms of silver onto an electrode for five minutes, followed by a reverse in charge to remove some of the silver for two and one-half minutes. The silver atoms accumulated in a fractal pattern just as predicted.

Shapir and Jorné already see practical applications for their findings. Often rechargeable batteries fail because each charge deposits material inside the battery, and each discharge charge removes some of that material. After several such charge cycles, the buildup can span the two leads inside the battery and short it out. Since the material does not accumulate in a uniform fashion, battery makers have had to test batteries by discharging and recharging them over and over until they fail. Shapir and Jorné think that with fractal equations, manufacturers can run through only a few charge accelerated cycles and calculate how long it will be until the battery fails without doing expensive, prolonged testing.

The research was funded by the National Science Foundation, the Office of Naval Research, and Kodak.

3. The Six Webs, worldlink

The hunger in Davos for anything to do with technology and the Internet was clear from standing-room only sessions and eager trails of participants quizzing panellists long after the formal conclusion to discussions. But while most participants were eager to find out about the Web, Forum Fellow Bill Joy, founder and chief scientist of Sun Microsystems, opened up the perspective of six webs.

The web we are familiar with Joy terms the Near Web, which is accessed through a browser on a desktop computer. We are only just beginning to use what Joy calls the Pocket Web, which might be accessed from a WAP-enabled mobile phone (WAP stands for Wireless Application Protocol) or an information appliance like the Palm VII or Psion Revo. The Pocket Web is always connected and is a truly personal web. The small screen means that existing Web pages need to be reconfigured and new programming code will be required to optimise use. "It's unrealistic to think you could transfer the code from the existing Web to fit these devices. It is a different kind of information," Joy says. With the mobile phone, billing systems already exist (through your mobile network) so transactions, possibly using micropayments, should proliferate on the Pocket Web.

Joy's third web is the Entertainment Web. "The Entertainment Web is a new opportunity for designing for a pleasant place to be that we really don't have yet," he cautions. The Entertainment Web will most likely be in a form such as a television set with an interactive Web connection. Disney characters might, for example, speak in a personalised way to your children through the Entertainment Web.

The Voice Web uses voice recognition to navigate the Web. "This is a totally different modality of use," Joy says. You might tell your networked radio to turn on a newscast, or to find a football game. Voice recognition technology, says Joy, is already very effective.

The first four webs in Joy's taxonomy "leave the human in the loop". The final two, which are computer-to-computer webs, will allow for far fewer errors. The fifth web, the Computer Web, would allow one company's ordering system to talk to another company's parts fulfillment system without any human interaction. "There's a much, much higher requirement for correctness and consistency," Joy says.

The sixth web, the Pervasive Web, revolves around embedded systems and sensors that "confederate and work together to do things". This may range from the mundane, a washable chip in your shirt which might help you find it or tell a washing machine the right instructions for its care, to a household or office where all devices intelligently interact with one another.

 

4. Wired For Sadness, Discover Magazine

Excerpts: "Brain imaging has revealed that positive and negative emotions are polarized on opposite sides of the prefrontal cortex. The right side governs a physiological loop that produces negative, inhibiting feelings, while the left commands a loop for positive, outward-reaching emotions. Research now suggests that a person's natural temperament--optimistic, pessimistic, extroverted, or introverted--may depend on which side of the prefrontal cortex is more active. In one study of 10-month-old infants who were briefly separated from their mothers, researchers found that babies who cried had a dominant right prefrontal cortex, and that those who calmly explored the area where they had been abandoned had a more active left cortex. " (...)

"In neurofeedback, as the patient increases alpha brainwaves on the right (calming the right cortex) and decreases them on the left (upping activity in the left cortex), he is rewarded with the sound of a flute playing at an ever higher pitch. After 20 to 40 half-hour sessions, tracings show the left cortex activity overtaking the right. So far, more than 20 people, from adolescents to a 65-year-old, have been treated with the technique. Except for those with bipolar depression, all patients reported feeling better, says psychologist J. Peter Rosenfeld, who developed the method. "

 

5. Brain Size Does Not Predict General Cognitive Ability Within Families

Abstract: Hominid brain size increased dramatically in the face of apparently severe associated evolutionary costs. This suggests that increasing brain size must have provided some sort of counterbalancing adaptive benefit. Several recent studies using magnetic resonance imaging (MRI) have indicated that a substantial correlation (mean r = 0.4) exists between brain size and general cognitive performance, consistent with the hypothesis that the payoff for increasing brain size was greater general cognitive ability. However, these studies confound between-family environmental influences with direct genetic/biological influences. To address this problem, within-family (WF) sibling differences for several neuroanatomical measures were correlated to WF scores on a diverse battery of cognitive tests in a sample of 36 sibling pairs. WF correlations between neuroanatomy and general cognitive ability were essentially zero, although moderate correlations were found between prefrontal volumes and the Stroop test (known to involve prefrontal cortex). These findings suggest that nongenetic influences play a role in brain volume/cognitive ability associations. Actual direct genetic/biological associations may be quite small, and yet still may be strong enough to account for hominid brain evolution.

 

6. Brainwaves Induce Order in Spatio-Temporal Chaos, PRL

Abstract: A time series from a human electroencephalogram (EEG) is used as a local perturbation to a reaction-diffusion model with spatio-temporal chaos.For certain finite ranges of amplitude and frequency it is observed that the strongly irregular perturbations can induce transient coherence in the chaotic system. This could be interpreted as "on-line" detection of an inherently correlated pattern embedded in the EEG.

Summary: Electrical activity as measured by EEG is a complicated mixture of many local nerve cell events within the human brain. It is generally assumed that many of these local events, for instance cognitive processes, contribute to the EEG in the form of short-term patterns with correlations.

Among the myriads of activities going on at the same time such transient patterns are not detectable by conventional methods of analysis. We have developed a method to automatically search for such short-term events without the need for further sophisticated analysis. The method employs a novel type of dynamics called "excitable chaos" to perform continuous processing of highly irregular input signals like EEG. Presently we are optimizing the procedure to search for a given specific event which might have clinical applications, for instance, in predicting an epileptic seizure.

  • Human Electroencephalogram Induces Transient Coherence In Excitable Spatio-Temporal Chaos, Gerold Baier, Ron S. Leder, and P. Parmananda, Physical Review Letters volume 84 issue 19, pages 4501-4504, 2000
  • Contributed by Gerold Baier

 

 7. Illusions in Reasoning About Consistency, Science

Reasoners succumb to predictable illusions in evaluating whether sets of assertions are consistent. We report two studies of this computationally intractable task of "satisfiability." The results show that as the number of possibilities compatible with the assertions increases, the difficulty of the task increases, and that reasoners represent what is true according to assertions, not what is false. This procedure avoids overloading memory, but it yields illusions of consistency and of inconsistency. These illusions modify our picture of human rationality

 

 8.Polarons In DNA, PNAS

Abstract: Many experiments have been done to determine how far and how freely holes can move along the stack of base pairs in DNA. The results of these experiments are usually described in terms of a parameter under the assumption that it describes an exponential decay with distance. The reported values range from < 0.2/Å to > 1.4/Å. For the larger values of , the transport can be accounted for as single step superexchange-mediated hole transfer. To account for the smaller values, hopping models have been proposed, the simplest being nearest-neighbor hopping. This model assumes that, between hops, the hole is localized on a single base with no overlap to neighbors. Noting that an electron or hole added to a DNA stack, as to other essentially one-dimensional entities, should distort its structure to form a polaron, Schuster and coworkers (...) proposed that transport occurs by polaron hopping between sites having approximately equal energies as a result of overlap. A recent experimental determination by Wan et al. (...) of the time required for an injected hole on DNA to travel a known distance leads to a large value of the diffusion constant. From this constant, a mobility of 0.2 cm2/V·s was deduced, orders of magnitude larger than typical hopping mobilities. We suggest that this ultrafast transport is due to polaron drift, which has been shown to lead to similar mobilities in chains of conjugated polymers. Using a simple model for the polaron, similar to that used for conjugated polymers such as polyacetylene, we show that, for reasonable values of the parameters, an injected electron or hole can form a polaron on a DNA stack.
  • Polarons In DNA, Esther M. Conwell and Svetlana V. Rakhmanova, PNAS 2000;97 4556-4560

 

 9. Authors Sought For UNESCO Encyclopaedia Project, Announcement

UNESCO has launched a major project to develop an Encyclopedia of Life Support Systems (EOLSS). The aim is to assemble together all the information essential for management of the global environment.

Authors are sought for chapters in Theme 6.48: Hierarchy and Complexity and Agent Based Models.

This theme concerns phenomena in which properties or behaviour emerge through the interactions of agents.

The 50 chapters are arranged under the following topics:

For a full list of the chapters and the theme contents see http://life.csu.edu.au/~dgreen/eolss/

The chapters need to be written by the end of 2000. If you have relevant expertise and could contribute a chapter, then please contact the appropriate topic subeditor, or the Theme Editor: David G. Green

 

 10. Links & Snippets


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