Predicting School Violence, Wired
Predicting human behavior has been one of the grand
challenges not only for complexity theory. Much research and CPU
time has been invested to predict the decisions of stock market
agents, political leaders, voters, consumers, etc. Whereas the
bulk of academic research is mostly interested in the averaged
behavior of a large number of people there also has been
considerable research efforts in predicting the behavior of
individual humans. After WW-II "personality assessment" methods
like the "Wechsler" test have been developed by the CIA and other
organizations in order to predict the behavior of individuals
(like secret agents) under extreme stress situations (like
interrogations and torture).
It is no surprise that security related organizations and
law-enforcement agencies continued this line of research to
develop "profiles" of criminals and precursor behavior that
typically would precede a crime. After the Columbine high school
shooting one of those companies -Gavin
de Becker, Inc, that has been in the security business for a
number of years-now offers a software package Mosaic 2000 that is
intended to help prevent school violence: "The program, designed
to evaluate specific threats and incidents rather than students
themselves, consists of a series of 40 questions that have not
been revealed to the public, but are said to include queries like:
Does the child have access to a gun at home? Has he threatened to
harm others or himself? Has he exhibited cruelty to animals? "
Naturally, not everyone is happy with the idea of introducing
computer based profiling into schools; school psychologists might
feel that their turf is being invaded. On the other hand websites
for Eric and Dylan" devoted to the memory of the two Littleton
shooters complain that school harassment of the kind that Eric and
Dylan were exposed to is still happening "too much, too often".
Are school psychologists alone capable of detecting dangerous
developments or could they use some electronic help from jointly
developed threat assessment software?
Mechanisms Of Extensive Spatiotemporal Chaos, Nature
"Climate is what you expect and weather is what you get."
This quote from meteorologist and chaos researcher Edward Lorenz
describes the long term unpredictability of atmospheric phenomena
like the weather. His other, more famous quote is that of a
butterfly flapping its wings in Brazil that can possibly cause a
storm in Boston (or something like that; actually in his
publication he mentions seagulls not butterflies) led to the
expression "butterfly effect" to describe the sensitive dependence
on initial conditions for chaotic systems. This extreme
sensitivity, however is not present everywhere all the time, so
most of the flapping butterflies will go without large impact on
Extensive numerical simulations by Egolf et al. of a simple
model atmosphere could identify those conditions as well as the
time and place where the system showed a dramatic increase in
sensitivity of the flow patterns to small perturbations. It is
basically located at boundary points between large, stable flow
patterns. In some way they model situations have some similarity
with conditions under which tornadoes are likely to be created.
Besides the localized nature of the butterfly effect they could
also show for their Rayleigh-Benard convection system that the
number of non-linear dynamical modes or the (Lyapunov) dimension
of the system is many orders of magnitudes smaller than any linear
estimates (Karhunen-Loeve or Fourier methods) of the number of
degrees of freedom.
That indicates the importance of describing the system with
non-linear methods. Furthermore they could show that the chaotic
properties of their system (showing 'spiral defect' chaos) are
"extensive" in the sense that the (Lyapunov) dimension of the
system scales with its size so that the average dimension density
reaches a limiting value.
Where Have All The Frogs Gone?, Nature
As one grows old one tends to remember more frequently
fond childhood memories and the good ol' days where everything was
better and the kids had more respect for grown-ups. Now it seem
that at least some of the romantic childhood memories of cool
summer nights filled with the sounds of frogs and crickets do have
a scientific basis even on a global scale: The frogs are
disappearing at an alarming rate world-wide as if they were an
alien race and an extra-galactic battle cruiser was about to blow
away the planet.
Houlahan et al. did the largest ever published global survey of
amphibians worldwide. They used all available published reports
but they say that their work would not have been possible without
They have "(…) analyzed 936 amphibian population data sets
collected from journal publications and technical reports, as well
as unpublished data provided by herpetologists from around the
world. Every effort was made to be exhaustive, and we believe that
our sample represents the most complete collection of amphibian
population time series to date. In total, over 200 researchers
have contributed data from 37 countries and 8 regions of the world
They found that globally there were at least two periods with a
steady loss of amphibians: 1960-1966 a decline of about 15% (!)
per year and 1966-1997 about 2% per year. It looks like the
decline in the 60's was more pronounced in Europe that in North
America but that since then the population has been more or less
stabilized in Europe whereas it continued to decline in other
parts of the world.
Now that the phenomenon of global disappearance of amphibians
has been scientifically established, the next question is for the
causes. Correlating rates of decline with environmental factors
should reveal some interesting patterns that might be of great
importance for the future of our own species.
"Abstract: The basic role of fiat money
in a dynamic economy is considered. Its role as a virtual asset
whose store of value properties are the outcome of the dynamics is
explored and the role of the limits on the money supply and the
bankruptcy laws in bounding prices are considered. The actions of
the government may serve to bound individual expectations.
THE CENTRAL ASPECTS OF MONETARY DYNAMICS, In God we trust,
all others pay cash! Old American saying
There are three basic aspects to the understanding of the
central role of fiat money in a modern economy. They are (1) the
understanding of the violation of symmetry in the initial
injection of outside or government money into the economy; (2) the
understanding of the laws of conservation of money and how and
when they may be violated and (3) the understanding of the
dynamics of the mix of trust, custom, law, communication and
information in maintaining the worth of "worthless" paper or a
mere abstraction of value in a dynamic economy.
Abstract money is a substitute for trust in trade. The rules
of the game provided by the laws and customs of the society using
a symbolic fiat money can, under the appropriate circumstances
support a system dynamics where individual expectations that other
individuals will accept this intrinsically worthless paper or
cypher will be self-fulfilling. The dynamics may provide for the
reinforcement of these beliefs which will provide for monetary
The Nasdaq Crash Of April 2000, arXiv
Two things are interesting about this article (besides
the content): It appeared on the electronic preprint server two
(!) days after it was submitted and within the same month of the
event that the authors analyze. Secondly, the topic is within
economics but non of the authors has any affiliation with an
economics department but instead they are experts in geophysics
and planetary physics, earth and space science, and condensed
"Abstract: The Nasdaq fell another 10% on Friday the 14th of
April 2000 signaling the end of a remarkable speculative high-tech
bubble starting in spring 1997. The closing of the Nasdaq at 3321
corresponds to a total loss of over 35% since its all-time high of
5133 on the 10th of March 2000. Similarities to the speculative
bubble preceding the infamous crash of October 1929 are quite
striking: The belief in what was coined a "New Economy" both in
1929 and presently made share-prices of companies with three
digits price-earning ratios soar. Furthermore, these two
speculative bubbles, as well as others, both nicely fit into the
quantitative frame-work proposed by the authors in a series of
1 Introduction: A series of recent papers have
presented increasing evidence that market crashes as well as large
corrections are often preceded by speculative bubbles with two
main characteristics: a power law acceleration of the market price
decorated with log-periodic oscillations. Here, "log-periodic"
refers to the fact that the oscillations are periodic in the
logarithm of the time-to-crash. (…)
The difference between "Old Economy" and "New Economy"
stocks is thus the expectation of future earnings as discussed in
: investors expect an enormous increase in for example
the sale of Internet and computer related products rather than in
car sales and are hence more willing to invest in Cisco rather
than in Ford notwithstanding the fact that the dividend-per-share
of the former is much smaller than for the later. For a similar
price per share (approximately $60 for Cisco and $55 for Ford),
the dividend per share is $0.37 for Cisco compared to $5.9 for
Ford (Cisco has a total market capitalisation of $395 billions
(close of April, 14, 2000) compared to $63 billions for Ford). In
the standard fundamental valuation formula, in which the expected
return of a company is the sum of the dividend return and of the
growth rate, "New Economy" companies are supposed to compensate
for their lack of present earnings by a fantastic potential
growth. In essence, this means that the bull market observed in
the Nasdaq the last three years until recently is fueled by
expectations of increasing future earnings rather than economic
fundamentals: The price-to-dividend ratio for a company such as
Lucent Technologies (LU) with a capitalization of over $300
billions prior to its crash on the 5 Jan. 2000 is over 900 which
means that you get a higher return on your checking account(!)
unless the price of the stock increases."
Eye Condition And Attention Deficit Hyperactivity Disorder, UCSD/Science Daily
UCSD Shiley Eye Center ophthalmologists and
researchers have uncovered a relationship between an eye disease
characterized by an inability to focus on a target and attention
deficit hyperactivity disorder (ADHD).
"We showed that children with the disorder, convergence
insufficiency are three times as likely to be diagnosed with ADHD
than children without the disorder," according to David B. Granet,
M.D., a UCSD School of Medicine associate professor of
ophthalmology and pediatrics and director of the UCSD Ratner
Children's Eye Center. "This is the first time such a relationship
has been identified between these two disorders."
Convergence insufficiency, a disorder that affects less than
five percent of children, is a physical eye problem that makes it
hard to keep both eyes pointed and focused at a near target,
making it difficult to maintain concentration when reading. ADHD
is considered to be one of the most common psychiatric disorders
When reviewing 266 charts of patients with convergence
insufficiency, Dr. Granet and his colleagues found that 26
patients (9.8%) were diagnosed with ADHD sometime in their life.
Of those, 20 (76.9%) were on medication for ADHD when they were
diagnosed with convergence insufficiency. "When we turned it
around and looked at the ADHD population we found an almost 16
percent incidence of convergence insufficiency, or again more than
three times what you'd expect."
"The significance of this relationship is intriguing," Dr.
Granet said. "We don't know if convergence insufficiency makes
ADHD worse or if convergence insufficiency is misdiagnosed as
ADHD. What we do know is that more research must be done on this
subject and that patients diagnosed with ADHD should also be
evaluated for convergence insufficiency and treated accordingly.
Further work may aid in understanding both disorders."
Dr. Granet added that convergence insufficiency is one of
the very few ocular conditions that respond to eye exercises
(orthoptics) which can be done at home.
Researchers from Penn State's College of Medicine have
shown that specific tumor cells can be engineered so that they can
suppress growth to a secondary site.
"As with most cancers, it is the spread of the cancer,
rather than the primary malignancy that is the principal cause of
death. We showed that these cells go through all steps in the
metastatic process, except growth, at the secondary site," says
Danny R. Welch, Ph.D., associate professor of pathology. "On a
practical basis, because we are inhibiting cell growth at the site
of metastasis, in this case the lungs, we may be able to treat
cells that have already spread by blocking their ability to grow
into a tumor which impairs function."
Welch and his colleagues, Steven F. Goldberg and John F.
Harms, presented this work in a paper titled,
"Metastasis-suppressed C8161 Melanoma Cells Arrest in Lung but
Fail to Proliferate," at the 91st annual meeting of the American
Association for Cancer Research meeting in San Francisco today.
Welch and his team placed two sets of human malignant
melanoma cells into mice. Those cancer cells with a restored
chromosome 6 did not metastasize. Those cells with a defective
chromosome 6 spread from the skin and developed tumors in the
"We watched the cells closely over hours, days, weeks and
months. The cells completed every step except growth," stated
Welch. "We know there is communication taking place between tumor
cells and cells in the organs to which they spread. There is also
some kind of interaction taking place, but the nature of that
interaction is not well defined. These findings represent an
opening whereby we can understand the communication taking place
so that one day therapies can regulate it."
Welch further explains that this work has implications
beyond melanoma. The molecules involved here may be early insight
as to why certain cancers spread preferentially to some organs.
For example, breast cancer spreads to lymph nodes and then
two-thirds of patients get bone metastasis. Colon cancer spreads
first to the liver. Consequently, he believes that cancer cells
can only survive in certain places and that is where they migrate.
"There is a great potential here to develop very targeted
therapies for cancer that metastasize to different organs," says
This research is funded by the National Institutes of
Health, the National Foundation for Cancer Research, and the Jake
Gittlen Cancer Research Institute at The Milton S. Hershey Medical
Lasers + Photosensitizer Drug Prevent Blindness, Source
Photodynamic therapy (PDT), a treatment for
age-related macular degeneration under study at Emory University
and other sites, received Food and Drug Administration (FDA)
Emory Eye Center can now offer new hope to patients with the
wet form of age-related macular degeneration (AMD), the leading
cause of blindness in Americans over age 50.
PDT is significant because there is no cure for wet AMD and
the most widely available treatment -- photocoagulation therapy
with a heating laser -- can cause blind spots and can be used for
about 10 percent of patients with the disease. About 40 to 60% of
the estimated 200,000 patients who are diagnosed each year with
wet AMD may be eligible for PDT.
According to Paul Sternberg Jr., M.D., director of the
retina section at the Emory Eye Center, "PDT uses a combination of
low-level laser light with a drug to stop the macula-destroying
effects of the disorder. PDT is a promising alternative to the
growing number of treatments we now can offer macular degeneration
patients. The therapy appears to be is safer with fewer risks than
AMD affects more than one-fourth of all Americans over age
75. No one knows what causes the disorder or how to prevent it.
AMD affects central part of the retina or the macula, the area of
sharpest sight and the part we use for reading and central vision.
The wet or exudative form of AMD -- the most blinding form
-- results when abnormal blood vessels form and leak fluid and
blood underneath the retina in the layer of the retina in the back
of the eye called the choroid. The choroid's blood vessels,
combined with tissue, can form a scar-like membrane under the
retina and block central vision.
The goal of PDT is to seal leaking blood vessels and slow or
stop the progression of vision loss. During PDT, the patient
receives an injection of a photosensitizer drug that concentrates
in the abnormal blood vessels from the choroid. A non-thermal
laser light shone onto the retina activates the drug. The therapy
is outpatient and patients can return to normal activities
immediately, though they will need to stay out of direct sunlight
for at least 24 hours. Most need repeat treatments later to
Following treatments, patients sometimes will experience a
temporary reduction of vision, which will improve over the next
few weeks. Research shows that the therapy preserves or improves
vision (defined as no loss of visual acuity or a deterioration of
less than four acuity lines on an eye chart) in 38% of patients
and slows vision loss in another 31 percent.
The Emory Eye Center was one of about 30 centers worldwide
that participated in Phase III clinical trials carried out by CIBA
Vision of Atlanta (QLT PhotoTherapeutics of Vancouver, Canada,
makes the dye and Carl Zeiss makes the laser). The therapy is
marketed as Visudyne™ therapy.
Warmest First Three Months Of The Year On Record, NOAA/Science Daily
The United States has just experienced the warmest
January - March period ever, according to 106 years of
record-keeping compiled by NOAA. The latest data also show that
June 1999 - March 2000 was the warmest June - March on record.
NOAA Administrator D. James Baker and FEMA Director James Lee Witt
released the latest figures at an Earth Week news conference in
New Orleans, La., which focused on global climate change and links
between a warming atmosphere and more severe weather.
"Our climate is warming at a faster rate than ever before
recorded. Ignoring climate change and the most recent warming
patterns could be costly to the nation. Small changes in global
temperatures can lead to more extreme weather events including,
droughts, floods and hurricanes," NOAA Administrator D. James
Baker said. "We will continue to provide the best possible data
and forecasts to the policy makers to help them as they deal with
these difficult issues."
"There is no doubt that the human and financial costs of
weather related disasters have been increasing in recent years. It
is time to increase our efforts in applying prevention strategies
to reduce the impacts of the changes in weather climates," said
FEMA Director James Lee Witt.
At the news conference, FEMA reported that damage from more
frequent and severe weather calamities and other natural phenomena
during the past decade required 460 major disasters to be
declared, nearly double the 237 declarations for the previous
ten-year period and more than any other decade on record.
Financially, comparing a three-year period of 1989 through 1991,
and 1997 through 1999, the federal costs of severe weather
disasters rose a dramatic 337 percent in the latter part of the
The record-breaking warmth for January - March 2000 averaged
41.7 degrees F, 1.0 degree F warmer than the previous record set
in 1990. During this period, every state in the continental U.S.
was warmer than its long-term average; 30 states from just west of
the Rocky Mountains to New England ranked much above average.
Oklahoma, Iowa, and Wisconsin each had the warmest January - March
period on record with Minnesota, South Dakota and Nebraska
experiencing their second warmest.
Warmer than normal conditions during the first half of March
contributed to the overall warmth of the three month period. Many
locations across the Upper Mississippi Valley, Great Lakes, and
Northeast set records for the earliest date with temperatures
reaching 80 degrees; and a few sites set all time March warm
temperature records during this period. Buffalo, NY reported their
harbor water temperature at the end of March equaled the record
warmest (39 degrees) set in 1998. (…)
The Intergovernmental Panel on Climate Change, or IPCC,
which consists of the world's leading climate researchers, has
just released a draft of the latest scientific report on the
science of climate change, projected impacts and vulnerability,
and options for mitigation. Their previous report, released in
1996, concluded that the balance of evidence suggests a
discernable human influence on global climate. (…)
Scientists widely believe that long-term climate changes
such as global greenhouse warming could have major impacts on
human health, the environment, the economy, and society. It could
affect everything from energy use and transportation to water
resource management and agriculture to international trade and
Freezing By Heating, Nature
Physicists often explore domains of reality that are far
removed from direct human experience. At the same time they seem
to getting a kick out of using everyday language to describe what
they find in those far removed worlds. For instance giving a
sub-atomic quark a "flavor" is a mere play of words, especially if
quarks are given flavors strange "strange" or "charmed".
In other domains physicists generalize a concept from a
familiar environment and end up with quite counter-intuitive
consequences. For instance how should we imagine "negative
temperatures", "imaginary masses" etc.? Intuitively we all know
what we mean by "temperature" and we think we recognize a liquid
when we see it. Stanley describes some recent work by Helbing et
al that seems to be quite against our basic intuition: How can we
heat a liquid with the result that it gets frozen? That doesn't
seem to make much sense. On the other hand if we try to visualize
a crowd of people rushing out of a packed disco then it makes
sense that turning up the "heat" for instance by throwing a smoke
bomb could lead to panic and clogged exit doors. Well, people
being stuck in exit doors do have something in common with frozen
water in that they don't move very fluidly. On the other side it
is not quite clear if the insight that "increasing the random
component of the movement (temperature) of a simulated granular
flow leads to jamming" is very helpful for designing better escape
routes in buildings. Are we discovering universal principles of
granular flow systems or are we perhaps creating a new, non-linear
Links & Snippets
Creativity and development, Book Report
"(...) Coen not only uses the analogy with art to explain
mechanisms of development, he also makes use of the analogy for
an extended discussion of the parallels between development and
creativity. The first chapter begins with a review of the
understanding of development throughout history and ends with a
summary of modern metaphors for development. Coen criticizes
the usual metaphors for how a single cell, the zygote, becomes
a complex organism. If development is likened to following a
set of instructions or a blueprint or computer program (encoded
in the genome), this analogy breaks down when you ask how the
instructions are followed. Where does the factory or assembly
line or computer (choose your model) come from? What is the
appropriate model for the developmental process that does not
separate the maker from the made (hence, how do organisms make
and Development, Pamela
K. Diggle, American Journal of Botany.
- The Art Of Genes: How Organisms
Make Themselves, Enrico Coen, 1999. Oxford
University Press. viii + 386 pp., ISBN 0 19 85 03
"(...) For patients, this reduction of the complex and
deeply personal experience of their disease to a generic
collection of symptoms has often turned treatment into an
impersonal ordeal, and contributed to Americans' disenchantment
with their health care system. But the sequencing of the human
genome -- perhaps the ultimate example of scientific
reductionism -- will, paradoxically, demonstrate that each case
of disease is unique, and for the first time, give doctors the
ability to devise individual treatments. (...)"
- Back to the Future: Medicine
and Our Genes, David A. Shaywitz, Dennis A.
Ausiello, New York Times, April 16, 2000
Who's Got Rhythm?, Science
"(...) Sophisticated processing of language is considered
a unique characteristic of humans. However, as Werker and
Vouloumanos discuss in a Perspective, nonhuman primates also
have the ability to distinguish natural rhythmicities in
speech. They explain new findings (Ramus et al.) demonstrating
that both cotton-top tamarin monkeys and human newborn infants
can distinguish between two languages (Dutch and Japanese) when
the languages are played forward but not backward. The
remarkable finding that tamarins may share this fundamental
speech processing capability with human newborns raises
questions about the uniqueness of human language.
The Microbial World Wide Web, Science
"(...) Indeed, the microbial biosphere can be thought of
as a World Wide Web of informational exchange, with DNA serving
as the packets of data going every which way. The analogy isn't
entirely superficial. Many viruses can integrate (download)
their own DNA into host genomes, which subsequently can be
copied and passed on: Hundreds of segments of human DNA
originated from historical encounters with retroviruses whose
genetic information became integrated into our own genomes.