NIH Eyes Sweeping Reform of Peer Review, Science, B. Agnew 
The research community can be seen as a complex adaptive system
that evolves according to a fitness landscape that evolves according
to support by grant giving institutions. A major agent in this system
is the National Institute of Health (NIH) where a sophisticated
peer-review system has emerged, in which small committees of
scientists, known as "study sections," judge the scientific merit of
about 40,000 grant applications a year. As all evolutionary systems
it is susceptible to exploitation by small sub-groups that recognize
patterns and learn to develop short cuts to get access to the
resources. As a consequence "NIH peer review too often amounts to
error-prone, turf-conscious nitpicking by obsolete study sections
that reject novel ideas out of fear, ignorance, and
self-interest".
Apparently some researchers adapted to the process of grant
writing and marketing with the original goal of scientific content
becoming almost secondary. As a consequence the fitness of the
overall system declined (e.g. number of Nobel prizes per funding
dollar) which then naturally led to a response and the ongoing
mutation of the peer review process: " As a result, NIH is now in the
midst of a major drive to refurbish the system--updating it to fit
today's biomedical science, setting standards of behavior to improve
peer reviewers' manners and methods, and creating a mechanism to
ensure that peer review will adapt as science evolves in the
future."
One consequence will be a streamlining of the information flow
among the peers: "For individual researchers, however, the biggest
boon may come from more efficient communication through the Internet.
NIH officials say they are only a year or two away from establishing
a long-sought system of electronic submission and review of grant
applications that could slash by nearly one-half the 10-month lag
from submission to award. Doing away with time lost to printing,
collating, distributing, and mailing grant applications also might
enable researchers to submit revised proposals without missing a
grant-award cycle."
NIH
Eyes Sweeping Reform of Peer Review ,
Bruce Agnew, Science, Volume 286, Number 5442 Issue of 5 Nov 1999,
pp. 1074 - 1076
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We know little about how ecosystems of different complexity will
respond to global warming.
Petchey et al. studied microcosms of aquatic microbes that permit
experimental control over species composition and rates of
environmental change.
" Diverse communities retain more species than depauperate ones,
as predicted by the insurance hypothesis, which suggests that high
biodiversity buffers against the effects of environmental variation
because tolerant species are more likely to be found. Studies of
single trophic levels clearly show that warming can affect the
distribution and abundance of species2,4,5, but complex responses
generated in entire food webs greatly complicate inferences based on
single functional groups."
"Warmed communities lost more species ( 30-40%) than communities
in constant environments ( 18%; Diversity and species composition did
not significantly affect extinction frequencies. More-diverse
communities were not especially fragile and did not exhibit the
cascading extinctions predicted by models of self-organized systems.
Higher biodiversity provided partial insurance against the complete
loss of functional groups, basically because all communities lost a
similar fraction of their initial species richness."
Environmental
warming alters food-web structure, Owen
L. Petchey, P. Timon Mcphearson, Timothy M. Casey, Peter J. Morin,
Nature 402, 69 - 72 (1999)
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One of the early examples of chaotic dynamics in biological
systems was the "logistic map" introduced by Robert May in the late
seventies. It modeled oscillations in population sizes under
different environmental conditions. For small parameters
(reproduction rates) you get monotonous decay to extinction. For
larger values you observe stable population sizes, for still higher
values periodic oscillations and finally erratic fluctuations and
deterministic chaos. For a long time biologists were looking for real
live examples that would show that transition. Most of those examples
looked a little contrived like data chosen to match the equation.
Therefore the findings of Belovsky et al. is a nice confirmation
of the theoretical work on the importance of non-linear effects in
pepulation systems: "Extinction of populations occurs naturally, but
global extinction rates are accelerating, making understanding
extinction a high priority for conservation. Extinction in
experimental populations of brine shrimp (Artemia franciscana) was
measured to assess hypothesized extinction processes. Greater initial
population size, greater maximum population size supported by the
environment, and lower variation in environmental conditions reduced
the likelihood of extinction, as hypothesized. However, initial
population size was less important, and maximum population size and
environmental variation were more important than often hypothesized.
Unexpectedly, deterministic oscillations in population size due to
inherent nonlinear dynamics and overcrowding were as important or
more important than hypothesized processes."
Experimental
Studies of Extinction Dynamics, Gary E.
Belovsky, Chad Mellison, Chad Larson, Peter A. Van Zandt, Science
Volume 286, Number 5442 Issue of 5 Nov 1999, pp. 1175 - 1177
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"Encoding of information in the cortex is thought to depend on
synchronous firing of cortical neurons. Inhibitory neurons are known
to be critical in the coordination of cortical activity, but how
interaction among inhibitory cells promotes synchrony is not well
understood."
"We show that communication through electrical synapses allows
excitatory signalling among inhibitory cells and promotes their
synchronous spiking. These results indicate that electrical synapses
establish a network of fast-spiking cells in the neocortex which may
play a key role in coordinating cortical activity."
A
network of fast-spiking cells in the neocortex connected by
electrical synapses, Mario Galarreta,
Shaul Hestrin, Nature 402, 72 - 75 (1999)
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Cyborgs - human/machine hybrids have long been the dream of
science fiction authors … and some military enthusiasts: more
than ten years ago some studies have been done about a heavily
armored fighting suit that is hydraulically controlled though some
direct brain interface. The project apparently died because the
communication rate is too low and unreliable. Today, ten years later
we have a thought translation device -which is still very slow- and
some research into direct integration of artificial and biological
neurons. A team led by Alan Selverston und Henry Abarbanel of UCSD
interfaced lobster neurons with an artificial neural net consisting
of fourteen neurons. They removed some of the central neurons that
are participating in the digestive process of the hummer. The lesion
induced epileptic seizures that could be suppressed with the help of
the artificial neurons.
Joel Davis, program-manager of the Office of Naval Research says
that these results show that natural neural networks are understood
sufficiently well that they can be rebuilt "in-silico", taking
advantage of their non-linear properties.
For the future the San Diego group plans to successively
substitute all lobster neurons with their electronic replacement
parts. This is still a far cry from a fighting cyborg but it
definitely is one first step.
Lieber
künstliche Neuronen als gar keine,
Bild Der Wissenschaft,
Dörte Saße, EurekAlert und
ONR
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One of the amazing properties of the brain is its "plasticity" to
re-structure its neuronal connections even in adults. This is
especially important after injuries where other parts of the brain
will take over functions of the damaged areas. One important question
for rehabilitation is how this healing process can be enhanced.
Jones et al. could show that for adult rats with injuries to their
motor area would recover better if they have the opportunity to
practice complex movement tasks as compared to animals who perform
simple repetitive exercise. " On tests of coordinated forelimb use,
lesion-AC rats performed better than lesion-MC rats. In addition to
supporting a link between behavioral experience and structural
plasticity after brain damage, these findings suggest that adaptive
neural plasticity may be enhanced using behavioral manipulations as
"therapy.""
Motor
Skills Training Enhances Lesion-Induced Structural Plasticity in
the Motor Cortex of Adult Rats, Theresa
A. Jones, Catherine J. Chu, Lucinda A. Grande, and Aurora D.
Gregory, The Journal of Neuroscience, November 15, 1999,
19(22):10153-10163
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We all have seen the spectacular color graphics that can be
produced with non-linear equations and chaotic algorithms. And for
more than 20 years some scientists played around listening to the
sounds that their equations would translate into. Some of these
efforts led in the early nineties to SFI's international conference
series on auditory display (ICAD) (now International
Community for Auditory Display) the sixth of which is scheduled
for next year.
More recently composers and musicians have become more seriously
interested in Chaotic music in spite of the significant cultural
differences between the music- and science-world.
Discovery online gives nice introduction to recent activities in
this area:
The
Music Makers - How do they do it and why?
Create
Your Own Chaos
Fantastic
Voyage - Enter a fractal image
Hear
What You See
A
Fractal World See and hear fractal sights and sounds
Sound
of Chaos, Tac Leung , Discovery Channel
Online, http://www.discovery.com/stories/technology/fractals/fractals.html
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Caenorhabditis elegans (C. elegans) is the geneticists' favorite
worm because (among other nice features) it shares with humans a
surprisingly large part of its genetic code. Furthermore its genetic
code is completely known and understood in great detail. Genetic
mechanisms for developmental or pathological properties of C. elegans
are therefore expected to give first important clues to how the
mechanism might work in the human genome. In that sense C. elegans is
like a genetic computer model (not simulation) of the human genome.
That means that it should display universal features of both genetic
systems.
One example of such a universal property seems to be the molecular
mechanism for biological clocks. For humans one of the most visible
effects of that clock is the occurrence of circadian (24h) rhythms.
For worms it seems that the day-night cycle is evolutionary not that
important and so for C. elegans a molting period of six hours has
stabilized.
Jeon et al. studied C.elegans' "heterochronic gene lin-42" that
could be shown to affect the molting clock. They could show that
"LIN-42 most closely resembles the Period family of proteins from
Drosophila and other organisms, proteins that function in another
type of biological timing mechanism: the timing of circadian rhythms.
Per mRNA levels oscillate with an approximately 24-hour periodicity.
lin-42 mRNA levels also oscillate, but with a faster rhythm; the
oscillation occurs relative to the approximately 6-hour molting
cycles of postembryonic development."
Similarity
of the C. elegans Developmental Timing Protein LIN-42 to Circadian
Rhythm Proteins, Mili Jeon, Heather F.
Gardner, Eric A. Miller, Jodie Deshler, Ann E. Rougvie, Science,
Volume 286, Number 5442 Issue of 5 Nov 1999, pp. 1141 - 1146
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Complex systems have the property that they can form structured
patterns out of a large collection of subsystems. Some of the biggest
such self-organized structures are galaxies that form out of gas
and/or already formed stars or other coherent structures such as
smaller galaxies. Those primordial structures would be disrupted
during the formation of the galaxy. Amina Helmi et al. studied the
structure of our own galaxy the Milky Way for signatures of those
pre-galactic structures. Investigating the current positions of the
stars in the Milky Way would reveal some fractal scaling but that
would not give a clue to the nature of the pre-galactic structures.
Therefore Helmi et al. take advantage of conservation of momentum and
search for structures in velocity space: All stars that were part of
a primordial, coherent structure would still share the common
velocity of that structure. "The high-quality proper motions provided
by the Hipparcos satellite allow us to construct accurate
three-dimensional velocity distributions for almost-complete samples
of nearby halo stars."
The method that was used is to detect structures based on
entropies of partitions of velocity space. "We implement this entropy
test initially by partitioning velocity space into cubic cells 70 km
s-1 on a side."
Any partition that would indicate a deviation from random
distributions would yield a lower entropy value. From their data they
conclude: " The precursor object was apparently on an eccentric orbit
with a relatively large apocentre. (…) The absence of satellite
galaxies on eccentric non-polar orbits argues that some dynamical
process preferentially destroys such systems; their stars should then
end up populating the stellar halo. As we have shown, the halo does
indeed contain fossil streams with properties consistent with such
disruption."
Debris
streams in the solar neighbourhood as relicts from the formation
of the Milky Way, Amina Helmi, Simon D.
M. White, P. Tim De Zeeuw, Hongsheng Zhao, Nature 402, 53 - 55
(1999)
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The Earth climate system has a number of coupled components the
most dominant of which are the atmosphere and the ocean. The sea
surface interface determines the exchange of CO2 and water; its
temperature distribution triggers large-scale phenomena like El Nino
with an average recurrence time of a few years.
It is known that the deep ocean water is one of the planet's
largest reservoirs of CO2 and therefore will have profound impact on
the long-term climate dynamics. Two "conveyor belts" -one in each
hemisphere's polar regions- transport cold surface water to the deep
ocean and then towards the equator at the same time moving warm
surface water towards the poles. One of them, the "gulf stream" is
responsible for the current mild climate in Northwestern Europe.
W.S.Broecker et al. observed a dramatic slow-down of the Southern
conveyor belt over the past hundred years. This coincides with the
end of the Little Ice Age (~1350 to 1880 A.D.) of the region around
the northern Atlantic. Based on this and other evidence they propose
that the two deep-ocean currents of both hemispheres together with
the corresponding climate systems perform an oscillation with a
period around 1500 years: "(…) a seesawing of deep water
production between the northern Atlantic and Southern oceans may lie
at the heart of the 1500-year ice-rafting cycle."
We know that non-linear oscillators often can respond very
sensitively (some times with chaos) to external perturbations and
changes in parameters. Global warming of the atmosphere and therefore
the sea-surface temperature has been suggested to be such a control
parameter that could bring the North Atlantic conveyor belt to a halt
with the consequence of regional cooling comparable to the Little Ice
Age. As a consequence of reduced deep water production the uptake of
atmospheric CO2 could be dramatically reduced. Furthermore the
ocean's role as atmospheric heat sink could be diminished which would
in turn lead to an accelerated warming.
The contrast of a cold North Atlantic with a globally increased
temperature could increase temperature gradients, which in turn could
favor conditions of more frequent "extreme weather" conditions like
super-storms and hurricanes.
A
Possible 20th-Century Slowdown of Southern Ocean Deep Water
Formation, Wallace S. Broecker, Stewart
Sutherland, Tsung-Hung Peng, Science, Volume 286, Number 5442
Issue of 5 Nov 1999, pp. 1132 - 1135
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During the eruption of the Soufrière Hills volcano,
Montserrat (1995-99), and several other dome eruptions, shallow
seismicity, short-lived explosive eruptions and ground deformation
patterns indicating large overpressures (of several megapascals) in
the uppermost few hundred metres of the volcanic conduit have been
observed. These phenomena can be explained by the nonlinear effects
of crystallization and gas loss by permeable flow, which are here
incorporated into a numerical model of conduit flow and lava dome
extrusion. Crystallization can introduce strong feedback mechanisms
which greatly amplify the effect on extrusion rates of small changes
of chamber pressure, conduit dimensions or magma viscosity. When
timescales for magma ascent are comparable to timescales for
crystallization, there can be multiple steady solutions for fixed
conditions. Such nonlinear dynamics can cause large changes in dome
extrusion rate and pulsatory patterns of dome growth.
Nonlinear
dynamics of lava dome extrusion, O.
Melnik, R. S. J. Sparks, Nature 402, 37 - 41 (1999)
