Complexity Digest 2000.29

17-Jul-2000

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Content

  1. Education More Than Digital Divide, G8 Online
  2. Structure and Dynamics of Complex Interactive Networks, SFI Workshop Website
  3. Synaptic Networks Of Neurons And Glia, PNAS
  4. A Neural Basis for General Intelligence, Science
  5. Consciousness, Annu. Rev. Neurosci.
  6. Patterns Underlying Gene Expression, PNAS
  7. Behavioral Responses to Drugs of Abuse After a Brief Experience, Science
  8. Is Music Part Of Our Genetic Past?, MSNBC News
  9. Scientists Invent Meat-Eating Robot, CBC News
  10. Inspiration For Optimization From Social Insect Behaviour, Nature
  11. Links & Snippets
    1. Self-Organization: The Next Big Thing?, Response
    2. Melting Polar Icecaps And Some Consequences, Response
    3. Polynesian Origins: Insights From The Y Chromosome, PNAS
    4. Interpreting The Universal Phylogenetic Tree, PNAS
    5. Mid Latitude Ozone Hole, sci.environment
    6. Neural Representation And The Cortical Code, Annu. Rev. Neurosci.
    7. Link Between Global Lightning Activity And Upper Tropospheric Water Vapour, Nature

  1. Education More Than Digital Divide, G8 Online Next Article Bookmark and Share

    g8online.org brings up-to-date information from the G8 summit in Okinawa in text and streaming media. There a number of centrally important global issues are discussed. One focus is information technology and the danger of an information society with information-haves and have-nots. Education is an essential part of that issue. Job security on a global market requires some form of standardization. On the other hand this should not be done at the cost of global cultural diversity.

    Mr. Yamazaki was quick to remind the gallery that Japan has pledged $15 billion package over 5 years to help countries struggling to alleviate debt and at the same time provide their citizens with basic education and health. Back in May of this year, Japan also pledged to initiate a satellite based education program that would provide IT training for 10,000 workers in developing countries. There was also talk of creating a centre in Japan for growing human resources in Asian countries to support IT training.

    While it is necessary to support the development of IT in poorer countries, more affluent nations must also keep an eye on domestic educational issues. At a pre-summit meeting of Education Ministers, there were many other concerns raised. For instance, the idea of lifelong learning was held up as a standard to which all countries should strive to support. The evolution of technology has also increased the capacity for distance learning, or the idea of education any time, anywhere. Traditional methods of teaching are just as much in need of attention. The ministers agreed that more effort should be made to standardize curriculae and encourage the transferability of qualifications and credits. Borderless education and training ties in well with this year's summit theme of globalization.


  2. Structure and Dynamics of Complex Interactive Networks, SFI Workshop Website Next Article Bookmark and Share

    Today's world is highly connected with networks, the most prominent of them is the Internet. As the numbers of nodes in these networks increases and the connectivity becomes more efficient one would expect the emergence of global, self-organized, coherent structures with new and complex properties.

    The Santa Fe Institute is launching a new research program with the goal to study the structures and dynamics of these networks. The founding workshop is held with a select group in the Santa Fe Institute, necessarily small because of physical constraints of person to person meetings. The project website, however, makes relevant links and information available to the global network of researchers and students interested in the study of networks. This seems like a nice application of the "Small World" network theory of Duncan Watts, one of the organizers, that implies that efficient global networking only requires a few links among localized clusters. Whereas this academic networking was already possible with letter correspondence, the Internet reduces the involved time scales by several orders of magnitude. We know that for complex systems that intrinsic timescales are often critical parameters that can lead to bifurcations and qualitative changes in the system.

    It seems that up-to-date conference websites have become common standard in academic and professional meetings. In many cases conference presentations are broadcast on the Internet either live or from an archive (see e.g. World Economic Forum, ComDig 2000.4.1 , Internet and Society Conference 2000, Harvard University, World Congress on Information Technology, ComDig 2000.23.11.1). Perhaps the organizers will also add some streaming video to their fascinating web-site especially with intel as the main sponsor.

    From the Founding Workshop Announcement:

    "Networks are everywhere in the real world: The brain is a network of neurons; societies and organizations alike are networks of people; and the WWW is a network of pages connected by hotlinks. Diseases and rumors both transmit themselves through social networks, and computer viruses can now propagate via the Internet. Food webs and ecosystems can be represented by networks, as can the social connections between securities traders or the steps in a sequential, online search. The harder we look at the world around us, the more we see networks.

    The apparent ubiquity of networks in the social and natural sciences, as well as in everyday life, leads to a fascinating set of common problems concerning how network structure facilitates and constrains network behavior. These problems remain largely unanalyzed, yet answers to them would have far reaching consequences for many disciplines: How do social networks mediate the transmission of a disease or the emergence of a new political order? How do cascading failures propagate throughout a large power transmission grid or a global financial network? What is the most efficient and robust architecture for an organization in an uncertain environment or for a distributed computer? "


  3. Synaptic Networks Of Neurons And Glia, PNAS Next Article Bookmark and Share

    When we talk about information processing in brains we mostly think of neurons receiving electrical input from dendrites and -if those reach a threshold- firing a pulse down an axon. We know that learning takes place at synapses where electrical stimuli lead to the release of neuro-transmitters, some molecules that are involved in how well a neuronal pulse is propagated to neighboring neurons.

    It has become evident that this is not the whole story that there is a "shadow network" working in the background working not with electrical but chemical signals like calcium waves that trigger glutamate that can influence the threshold of neurons and thereby couple directly to the electrical brain network:

    "Parpura and Hayden (2 ), show that two different types of glial cells are involved directly in rapid glutamate-mediated neural signaling. One glial cell type, oligodendrocyte precursor cells (OPCs), was shown to receive direct synaptic input from neurons in the hippocampus (1), and another glial cell type, astrocytes, was shown to release glutamate rapidly in response to physiological increases in intracellular calcium concentration (2)."

    Abstract: Astrocytes can release glutamate in a calcium-dependent manner and consequently signal to adjacent neurons. Whether this glutamate release pathway is used during physiological signaling or is recruited only under pathophysiological conditions is not well defined. One reason for this lack of understanding is the limited knowledge about the levels of calcium necessary to stimulate glutamate release from astrocytes and about how they compare with the range of physiological calcium levels in these cells. We used flash photolysis to raise internal calcium in astrocytes, while monitoring astrocytic calcium levels and glutamate, which evoked slow inward currents that were recorded electrophysiologically from single neurons grown on microislands of astrocytes. With this approach, we demonstrate that modest changes of astrocytic calcium, from 84 to 140 nM, evoke substantial glutamatergic currents in neighboring neurons (…). Because the agonists glutamate, norepinephrine, and dopamine all raise calcium in astrocytes to levels exceeding 1.8 µM, these quantitative studies demonstrate that the astrocytic glutamate release pathway is engaged at physiological levels of internal calcium. Consequently, the calcium-dependent release of glutamate from astrocytes functions within an appropriate range of astrocytic calcium levels to be used as a signaling pathway within the functional nervous system.


  4. A Neural Basis for General Intelligence, Science Next Article Bookmark and Share

    Excerpts: "Since the time of Plato, we have been fascinated by the notion of intelligence and how to measure it. In 1904, Spearman proposed the existence of a general factor of intelligence (g), which represents what is general or common to all the abilities that constitute so-called IQ (intelligence quotient). Spearman argued that g contributes to success on a wide range of cognitive tasks. A competing hypothesis put forward by Thomson in 1916 proposed that what appeared to be a unitary general ability was in fact a collection of multitudinous and diverse skills needed to complete most intellectual tasks."

    "Spatial, verbal, and perceptuo-motor tasks with high-g involvement are compared with matched low-g control tasks. In contrast to the common view that g reflects a broad sample of major cognitive functions, high-g tasks do not show diffuse recruitment of multiple brain regions. Instead they are associated with selective recruitment of lateral frontal cortex in one or both hemispheres. (…) The results suggest that "general intelligence" derives from a specific frontal system important in the control of diverse forms of behavior."


  5. Consciousness, Annu. Rev. Neurosci. Next Article Bookmark and Share

    Abstract: Until recently, most neuroscientists did not regard consciousness as a suitable topic for scientific investigation. This reluctance was based on certain philosophical mistakes, primarily the mistake of supposing that the subjectivity of consciousness made it beyond the reach of an objective science. Once we see that consciousness is a biological phenomenon like any other, then it can be investigated neurobiologically. Consciousness is entirely caused by neurobiological processes and is realized in brain structures. The essential trait of consciousness that we need to explain is unified qualitative subjectivity. Consciousness thus differs from other biological phenomena in that it has a subjective or first-person ontology, but this subjective ontology does not prevent us from having an epistemically objective science of consciousness. We need to overcome the philosophical tradition that treats the mental and the physical as two distinct metaphysical realms. Two common approaches to consciousness are those that adopt the building block model, according to which any conscious field is made of its various parts, and the unified field model, according to which we should try to explain the unified character of subjective states of consciousness. These two approaches are discussed and reasons are given for preferring the unified field theory to the building block model. Some relevant research on consciousness involves the subjects of blindsight, the split-brain experiments, binocular rivalry, and gestalt switching.
    • Consciousness John R. Searle, Annu. Rev. Neurosci. 2000. 23:557-578

  6. Patterns Underlying Gene Expression, PNAS Next Article Bookmark and Share

    When physicists approach a problem in an interdisciplinary collaboration with experts from specialized disciplines, they often contribute a "fresh", sometimes naive approach to complex problems. They always have to find the subtle balance expressed in Einstein's advice: "Simplify as much as possible. But not more."

    A number of researchers have been fascinated by the patterns that are apparent in the organization of the genome and a number of non-linear data analysis and visualization techniques have been applied (recent work by Hao Bai-lin and his group comes to my mind). Holter et al. use linear statistical methods based on singular value decomposition. The appearance of patterns is evident , the question is what we can read from these patterns and which predictions can we make.

    Abstract: Analysis of previously published sets of DNA microarray gene expression data by singular value decomposition has uncovered underlying patterns or "characteristic modes" in their temporal profiles. These patterns contribute unequally to the structure of the expression profiles. Moreover, the essential features of a given set of expression profiles are captured using just a small number of characteristic modes. This leads to the striking conclusion that the transcriptional response of a genome is orchestrated in a few fundamental patterns of gene expression change. These patterns are both simple and robust, dominating the alterations in expression of genes throughout the genome. Moreover, the characteristic modes of gene expression change in response to environmental perturbations are similar in such distant organisms as yeast and human cells. This analysis reveals simple regularities in the seemingly complex transcriptional transitions of diverse cells to new states, and these provide insights into the operation of the underlying genetic networks.


  7. Behavioral Responses to Drugs of Abuse After a Brief Experience, Science Next Article Bookmark and Share

    Drug abuse is of serious social, medical, as well as economic concern for many industrialized and developing countries. As a largely self-organized phenomenon with global connections and implications, traditional method of control via education, law-enforcement, and rehabilitation have not been too successful. It is therefore a challenge for the complexity community to identify critical parameters and their dynamical relationships that could induce transitions in societies to new dynamical states that are characterized with significantly reduced drug abuse and mitigation of the associated problems like crime and teenage delinquency.

    The paper by Cabib et al. shows that even seemingly unrelated factors like food shortages can significantly change the behavior of mice in relation to drug seeking or avoidance.

    Abstract: Inbred strains of mice are largely used to identify the genetic basis of normal and pathological behaviors. This report demonstrates that a moderate period of food shortage, an ecologically common experience, can reverse or abolish strain differences in behavioral responses to the abused psychostimulant amphetamine. The period of food shortage occurred when the animals were mature and was terminated before the administration of amphetamine. Strain differences in behavior appear highly dependent on environmental experiences.

    Consequently, to identify biological determinants of behavior, an integrated approach considering the interaction between environmental and genetic factors needs to be used.


  8. Is Music Part Of Our Genetic Past?, MSNBC News Next Article Bookmark and Share

    Scientists have recently proposed that music may have been an evolutionary adaptation, like upright walking or spoken language, that arose early in human history and helped the species survive. (…)

    if it was an adaptation, what was it an adaptation to? How could participating in musical activities have given early humans any sort of survival advantage? (…)

    Other scientists believe that if music was an evolutionary adaptation, it initially functioned as a way to bind people together, both on an individual level (such as mothers singing to their infants) and as groups (fostering group identity, social cohesion, coordinating emotional states, and even keeping group members from fighting).

    Music is all about groups (…). Maybe people with a biological penchant for music lived more effectively in societies. (…) "National hymns, military music,(…), or the strict musical preferences of youth gangs may serve as examples of this phenomenon, whose origin may go back to the very beginning of human evolution," (…)

    An alternative explanation is music served as a memory-aid or mnemonic device during evolution and the rhythm and tones helped people accurately recall and pass on information. "We should pay more attention to music as a medium for memory and cultural knowledge," says Jamshed Bharucha, a Professor in the Department of Psychological and Brain Sciences at Dartmouth. "Prior to writing, which is very recent, [music may have provided a way] of asserting our cultural memory and passing that on through generations."


  9. Scientists Invent Meat-Eating Robot, CBC News Next Article Bookmark and Share

    In science fiction the issue comes up what happens when robots turn against their creators and try to take over the earth. Conditions when such a scenario would become feasible would require that there is a conflict of interests between robots and humans and that would require that robots have "interests" in the first place. The strongest interests of biological organisms are to survive long enough to reproduce and guarantee the survival of the offspring. We are a long way from self-reproducing "real" robots (not talking about self-reproducing alife creatures in silico). But a step in the direction of autonomous, self-sustaining robots has been made by Stuart Wilkinson who built an autonomous, moving system (Gastrobot) that produces its electrical energy from digesting organic food, especially meat. In principle that is a step towards direct conflict between organic organisms ("meat") and robots. And it would be no surprise if some military researchers in some lab try to figure out, how to turn this into an autonomous fighting unit.

    The term Gastrobot was coined in 1998 by Dr. Stuart Wilkinson, and means: "An intelligent machine (robot) that derives all its energy requirements from the digestion of real food". By being able to sustain itself by consuming naturally occurring food (such as vegetation) a Gastrobot is able to perform outdoor "Start-&-Forget" missions.

    The three-metre robotic train, appropriately named Chew Chew, has a microbial fuel cell for a stomach. The device uses bacteria, in this case E. coli, to break down food and convert chemical energy into electricity. The energy must charge the robot's battery before it has enough power to move itself. When the power runs out, the robot has to be fed again. Inventor Stuart Wilkinson, of the University of South Florida in Tampa, says meat is the ideal fuel in terms of energy gain.

  10. Inspiration For Optimization From Social Insect Behaviour, Nature Next Article Bookmark and Share

    Abstract: Research in social insect behavior has provided computer scientists with powerful methods for designing distributed control and optimization algorithms. These techniques are being applied successfully to a variety of scientific and engineering problems. In addition to achieving good performance on a wide spectrum of `static' problems, such techniques tend to exhibit a high degree of flexibility and robustness in a dynamic environment.

    (…)Recent research in social insect behavior suggests that models based on self-organization can help explain how complex colony-level behavior emerges out of interactions among individual insects.

    Among the studied problems are some forms of traveling salesman problems and those of finding the shortest path to a food source. Since the ants apply a pheromone marking strategy, they share a problem with many AI systems: The run the risk of getting trapped in a local minimum when, for instance a longer path is available or discovered first and consequently soaked in pheromones nd stabilized before the shorter path can be exploited. (This is also an ant version of getting stuck with a qwerty keyboard.) In simulations the problem can be fixed by making the ants "forget" through pheromone evaporation. It would be curious to see if there is a species somewhere that figured this solution out themselves.


  11. Links & Snippets Next Article Bookmark and Share


    1. Self-Organization: The Next Big Thing?, Response Next Article Bookmark and Share

      "The article mentions work at the Santa Fe Institute in the early 1990s. Although the Santa Fe Institute deserves credit for promoting the idea and for extending it, particularly in the direction of computer simulation, the earliest use of the term was in the 1960s. See the books Self-Organizing Systems, edited by Marshall Yovits and S. Cameron, Pergamon, 1960, and Principles of Self-Organization, edited by H. von Foerster and G.W. Zopf, Jr. Pergamon, 1962."

      This is a frequently-repeated claim, but is simply wrong.

      Principles of the Self-Organizing Dynamic System, Ashby, W. Ross, Journal of General Psychology,Vol.37,125--128,1947}

      There may be even earlier uses, but I've not found 'em.


    2. Melting Polar Icecaps And Some Consequences, Response Next Article Bookmark and Share

      "By most accounts ice in the Kara Sea, just beyond the Yamal Peninsula, is retreating. According to satellite photos, the average coverage of sea ice in the Arctic has shrunk by 6 percent since 1978. Furthermore to sonar measurements taken by U.S. submarines report that ice is thinning from 10 feet in the 1950s to 5.9 feet today.

      But the peninsula, so to speak, is only the tip of the iceberg. Until now, the giant Russian gas concern, Gazprom, has been unable to prospect, much less exploit, the Arctic Ocean. Currently, only icebreakers can navigate the Kara Sea 10 months of the year. However, with the pack ice in retreat, the opportunity arises for Gazprom and other Russian petroleum firms, to drill in the relatively shallow - and increasingly ice-free - waters. If the Russians succeed here, and in finishing a network of pipelines, they can dominate European energy markets for decades.

      The diminution of Arctic ice is being greeted in some quarters as an environmental disaster. But Russia, victim of many environmental disasters, ironically stands to benefit. With its vast Arctic coast, Russia stands to add new fisheries and shorten the time to ship goods between Asia and Europe."


    3. Polynesian Origins: Insights From The Y Chromosome, PNAS Next Article Bookmark and Share

      Abstract: The question surrounding the colonization of Polynesia has remained controversial. Two hypotheses, one postulating Taiwan as the putative homeland and the other asserting a Melanesian origin of the Polynesian people, have received considerable attention. In this work, we present haplotype data based on the distribution of 19 biallelic polymorphisms on the Y chromosome in a sample of 551 male individuals from 36 populations living in Southeast Asia, Taiwan, Micronesia, Melanesia, and Polynesia. Surprisingly, nearly none of the Taiwanese Y haplotypes were found in Micronesia and Polynesia. Likewise, a Melanesian-specific haplotype was not found among the Polynesians. However, all of the Polynesian, Micronesian, and Taiwanese haplotypes are present in the extant Southeast Asian populations. Evidently, the Y-chromosome data do not lend support to either of the prevailing hypotheses. Rather, we postulate that Southeast Asia provided a genetic source for two independent migrations, one toward Taiwan and the other toward Polynesia through island Southeast Asia.


    4. Interpreting The Universal Phylogenetic Tree, PNAS Next Article Bookmark and Share

      Abstract: The universal phylogenetic tree not only spans all extant life, but its root and earliest branchings represent stages in the evolutionary process before modern cell types had come into being. The evolution of the cell is an interplay between vertically derived and horizontally acquired variation. Primitive cellular entities were necessarily simpler and more modular in design than are modern cells. Consequently, horizontal gene transfer early on was pervasive, dominating the evolutionary dynamic. The root of the universal phylogenetic tree represents the first stage in cellular evolution when the evolving cell became sufficiently integrated and stable to the erosive effects of horizontal gene transfer that true organismal lineages could exist.


    5. Mid Latitude Ozone Hole, sci.environment Next Article Bookmark and Share

      Viewing NASA's EarthProbe TOMS Web Site from July 14 through July 19th, the latest date available at the time of this post, one can follow the development of what appears to be a new development in ozone depletion in the southern hemisphere.

      Large areas of the stratosphere are currently showing significant ozone depletion (…). This is the depth of winter withkjust a few hours of weak sunlight outside permanent darkness Such early ozone depletion is, I believe, unprecedented. Last year there were small patches of ozone depletion outside the area traditionally depleted within the Antarctic Circle. (…)

      • Mid Latitude Ozone Hole, sci.environment, Contributed by Jim Scanlon

    6. Neural Representation And The Cortical Code, Annu. Rev. Neurosci. Next Article Bookmark and Share

      Abstract: The principle function of the central nervous system is to represent and transform information and thereby mediate appropriate decisions and behaviors. The cerebral cortex is one of the primary seats of the internal representations maintained and used in perception, memory, decision making, motor control, and subjective experience, but the basic coding scheme by which this information is carried and transformed by neurons is not yet fully understood. This article defines and reviews how information is represented in the firing rates and temporal patterns of populations of cortical neurons, with a particular emphasis on how this information mediates behavior and experience.


    7. Link Between Global Lightning Activity And Upper Tropospheric Water Vapour, Nature Bookmark and Share

      Abstract: Tropospheric water vapour is a key element of the Earth's climate, which has direct effects as a greenhouse gas, as well as indirect effects through interaction with clouds, aerosols and tropospheric chemistry. Small changes in upper-tropospheric water vapour have a much larger impact on the greenhouse effect than small changes in water vapour in the lower atmosphere, but whether this impact is a positive or negative feedback remains uncertain. (…)

      Here I show that upper-tropospheric water-vapour variability and global lightning activity are closely linked.


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