Humans on the Move, Science 
A handful of ancient sites have convinced most
anthropologists that early humans frequented southern Europe
beginning perhaps 1.2 million years ago. But many researchers
aren't sure just what species name to give to the first Europeans,
or how many species they belonged to. There is even less agreement
on where the first settlers came from and whether they gave rise
to later Europeans. And yet recent discoveries here and at other
sites in Spain and Italy indicate that Europe was more than just a
neglected backwater during the early days of human evolution.
- Humans
On The Move, Elizabeth
Culotta, Andrew Sugden, Brooks Hanson , Science 2001
291: 1721
In Search of the First Europeans, Science
A handful of ancient sites have convinced
most anthropologists that early humans frequented southern Europe
beginning perhaps 1.2 million years ago. But many researchers
aren't sure just what species name to give to the first Europeans,
or how many species they belonged to. There is even less agreement
on where the first settlers came from and whether they gave rise
to later Europeans. And yet recent discoveries here and at other
sites in Spain and Italy indicate that Europe was more than just a
neglected backwater during the early days of human
evolution.
The Riddle of Coexistence, Science
A new look at archaeological sites
throughout the Mediterranean region shows that Neandertals and
modern humans coexisted in Europe for at least several thousand
years and took turns occupying the same caves in the Middle East
for much longer. Although modern humans had a clear technological
and cultural advantage in Europe, they did not rout the
Neandertals. There are no signs of war or rapid replacement. So
far the evidence suggests that there was plenty of room for both
groups for thousands of years, with competition for resources
intensifying only as the climate worsened.
But Did They Mate?, Science
Successful reproduction would imply that
Neandertals and humans were part of the same species and shared a
recent evolutionary history. Studies of the maternally inherited
mitochondrial DNA (mtDNA) from three Neandertals show it to be
distinctly different from that of living humans, suggesting that
Neandertal genes do not survive today and supporting a replacement
view (…) variation between Neandertals and modern humans
falls within the range of mtDNA variation between subspecies of
chimpanzees.
-
The timing of the Clovis people's journey
is pinned down by the melting of the great glaciers of the last
Ice Age. (…) might have trekked through a gap in the glaciers
just east of the ice-covered Pacific coastal mountains and south
of the arctic ice, to the Great Plains (see map). But they
couldn't have gone very far south before the ice melted to open a
path. (…) gap probably did not open earlier than 13,000 years
before the present (BP) (…).
Pre-Clovis Sites Fight for Acceptance, Science
Leaders in the field remain skeptical,
noting that the evidence from pre-Clovis sites is patchy and
uneven, unlike the powerful stone record of the Clovis people. He
and other skeptics have challenged pre-Clovis finds, questioning
everything from dates to stratigraphy. A close look at a few of
the most important and controversial sites illustrates why it is
so difficult to prove very ancient occupation--and why the
peopling of the Americas remains an open question.
Tracking the Sexes by Their Genes, Science
But molecular anthropologists tracking
these ancient travelers by the trails left in their descendents'
DNA are finding a surprise: striking differences in how the two
sexes traveled about parts of this planet.
(…) male explorers or warriors carried their genomes to
distant places. But surprisingly, in general females seem to have
stirred the genetic melting pot by dispersing their DNA more
widely than their brothers dispersed theirs--perhaps as a result
of thousands of years of moving to join their husbands'
clans.
The Peopling of the Pacific, Science
Polynesia, with its dramatic volcanic
islands rising out of the South Pacific, was the last area of the
world to be settled by people. The fossil and archaeological trail
shows that humans first set foot in Fiji only 3000 years ago, then
sailed on within 500 years to Samoa and Tonga, and later reached
Easter Island, Hawaii, and the fringes of remote Oceania,
exploring a realm stretching 4500 kilometers. But just who was in
those outrigger canoes has long been a mystery.
Genealogical and Evolutionary Inference with the Human Y Chromosome, Science
Population genetics has emerged as a
powerful tool for unraveling human history. In addition to the
study of mitochondrial and autosomal DNA, attention has recently
focused on Y-chromosome variation. Ambiguities and inaccuracies in
data analysis, however, pose an important obstacle to further
development of the field. Here we review the methods available for
genealogical inference using Y-chromosome data.
Approaches can be divided into those that do and those that
do not use an explicit population model in genealogical
inference.
Genetic Clues to Dispersal in Human Populations: Retracing the Past from the Present, Science
Ongoing debate about proper interpretation
of DNA sequence polymorphisms and their ability to reconstruct
human population history illustrates a important change in
perspective that we have achieved in the past 20 years of
population genetics. To what extent does the history of a locus
represent the history of a population? Tools originally developed
for molecular systematics, where genetic lineages have been
separated by speciation events, are routinely applied to the
analysis of variation within our species, with conflicting
results.
Paleolithic Technology and Human Evolution, Science
Human biological and cultural evolution
are closely linked to technological innovations. Direct evidence
for tool manufacture and use is absent before 2.5 million years
ago (Ma), so reconstructions of australopithecine technology are
based mainly on the behavior and anatomy of chimpanzees. Stone
tool technology, robust australopithecines, and the genus Homo
appeared almost simultaneously 2.5 Ma. Once this adaptive
threshold was crossed, technological evolution was accompanied by
increased brain size, population size, and geographical range.
Isotopic Evidence For Microbial Sulphate Reduction In The Early Archaean Era, Nature
Our results provide the oldest evidence of microbial
sulphate reduction in the geological record, pre-dating previous
evidence by more than 0.75 Gyr. They also give the earliest
indication of a specific microbial metabolism. Sulphate reduction
is a complex metabolic process requiring advanced membrane-bound
transport enzymes (…). Therefore, by 3.47 Gyr ago (…)
microbes had already developed many of the critical cellular
systems shared by their modern descendants. (…)
This placement (…) represents the oldest evolutionary
event thus far dated on the tree of life.
The Origin Of Atmospheric Oxygen On Earth: The Innovation Of Oxygenic Photosynthesis, PNAS
Abstract: The evolution of
O2-producing cyanobacteria that use water as terminal
reductant transformed Earth's atmosphere to one suitable for the
evolution of aerobic metabolism and complex life. The innovation
of water oxidation freed photosynthesis to invade new environments
and visibly changed the face of the Earth. We offer a new
hypothesis for how this process evolved, which identifies two
critical roles for carbon dioxide in the Archean period. First, we
present a thermodynamic analysis showing that bicarbonate (formed
by dissolution of CO2) is a more efficient alternative
substrate than water for O2 production by oxygenic
phototrophs. This analysis clarifies the origin of the long
debated "bicarbonate effect" on photosynthetic O2
production. We propose that bicarbonate was the thermodynamically
preferred reductant before water in the evolution of oxygenic
photosynthesis. Second, we have examined the speciation of
manganese(II) and bicarbonate in water, and find that they form
Mn-bicarbonate clusters as the major species under conditions that
model the chemistry of the Archean sea. These clusters have been
found to be highly efficient precursors for the assembly of the
tetramanganese-oxide core of the water-oxidizing enzyme during
biogenesis. We show that these clusters can be oxidized at
electrochemical potentials that are accessible to anoxygenic
phototrophs and thus the most likely building blocks for assembly
of the first O2 evolving photoreaction center, most
likely originating from green nonsulfur bacteria before the
evolution of cyanobacteria.
Crystals Prove Life on Mars, Discovery
A crystal found in a meteorite from Mars could only
have been formed by a microbe and may be evidence of the oldest
life form ever found, researchers say.
Scientists at the Johnson Space Center in Houston say that a
crystallized magnetic mineral, called magnetite, found in a
Martian meteorite is similar to crystals formed on Earth by
bacteria.(…)
Thomas-Keprta said there is no report of such magnetites
being formed by any but biologic means.
Chains Of Magnetite Crystals In The Meteorite ALH84001: Evidence Of Biological Origin, PNAS
Abstract: The presence of magnetite
crystal chains, considered missing evidence for the biological
origin of magnetite in ALH84001 [Thomas-Keprta, K. L.,
Bazylinski, D. A., Kirschvink, J. L., Clemett, S. J., McKay, D.
S., Wentworth, S. J., Vali, H., Gibson, E. K., Jr., & Romanek,
C. S. (2000) Geochim. Cosmochim. Acta 64, 4049-4081], is
demonstrated by high-power stereo backscattered scanning electron
microscopy. Five characteristics of such chains (uniform crystal
size and shape within chains, gaps between crystals, orientation
of elongated crystals along the chain axis, flexibility of chains,
and a halo that is a possible remnant of a membrane around
chains), observed or inferred to be present in magnetotactic
bacteria but incompatible with a nonbiological origin, are shown
to be present. Although it is unlikely that magnetotactic bacteria
were ever alive in ALH84001, decomposed remains of such organisms
could have been deposited in cracks in the rock while it was still
on the surface on Mars.
Power Laws of Wealth, Market Order Volumes and Market Returns, arXiv
Abstract: Using the Generalised Lotka Volterra (GLV)
model adapted to deal with muti agent systems we can investigate
economic systems from a general viewpoint and obtain generic
features common to most economies. Assuming only weak generic
assumptions on capital dynamics, we are able to obtain very
specific predictions for the distribution of social wealth. First,
we show that in a 'fair' market, the wealth distribution among
individual investors fulfills a power law. We then argue that
'fair play' for capital and minimal socio-biological needs of the
humans traps the economy within a power law wealth distribution
with a particular Pareto exponent $\alpha \sim 3/2$. In particular
we relate it to the average number of individuals L depending on
the average wealth: $\alpha \sim L/(L-1)$. Then we connect it to
certain power exponents characterising the stock markets. We
obtain that the distribution of volumes of the individual (buy and
sell) orders follows a power law with similar exponent $\beta \sim
\alpha \sim 3/2$. Consequently, in a market where trades take
place by matching pairs of such sell and buy orders, the
corresponding exponent for the market returns is expected to be of
order $\gamma \sim 2 \alpha \sim 3$. These results are consistent
with recent experimental measurements of these power law exponents
([Maslov 2001] for $\beta$ and [Gopikrishnan et al.
1999] for $\gamma$).
Quantifying Dynamics Of The Financial Correlations, arXiv
Abstract: A novel application of the correlation
matrix formalism to study dynamics of the financial evolution is
presented. This formalism allows to quantify the memory effects as
well as some potential repeatable intradaily structures in the
financial time-series. The present study is based on the
high-frequency Deutsche Aktienindex (DAX) data over the
time-period between November 1997 and December 1999 and
demonstrates a power of the method. In this way two significant
new aspects of the DAX evolution are identified: (i) the memory
effects turn out to be sizably shorter than what the standard
autocorrelation function analysis seems to indicate and (ii) there
exist short term repeatable structures in fluctuations that are
governed by a distinct dynamics. The former of these results may
provide an argument in favour of the market efficiency while the
later one may indicate origin of the difficulty in reaching a
Gaussian limit, expected from the central limit theorem, in the
distribution of returns on longer time-horizons.
- Quantifying
Dynamics Of The Financial
Correlations, S.
Drozdz, J. Kwapien, F. Gruemmer, F. Ruf, J.
Speth,,arxiv, Talk Presented By The First Author At
The Nato Arw On Econophysics, Prague, February 8-10,
2001; To Be Published In Proceedings (Physica A),
cond-mat/0102402 , 01/02/22
Complex Structures In Generalized Small Worlds, arXiv
Abstract: We propose a generalization of small
world networks, in which the reconnection of links is governed by
a function that depends on the distance between the elements to be
linked. An adequate choice of this function lets us control the
clusterization of the system. Control of the clusterization, in
turn, allows the generation of a wide variety of topologies.
-
Summary: We developed artificial societies of
adaptive autonomous agents, that we consider intelligent, in order
to understand adaptive and social behaviour, creating a system
that is able to simulate these behaviours. We developed a model
for social action, where sociality emerges from the simple
interactions of the members of a society. But first, we present a
behaviours production system, capable of reproducing in an
emergent way several properties of adaptive animal behaviour in
artificial creatures. We test our models in a Behaviours Virtual
Laboratory, available via Internet, where the user can perform
several experiments to test our models and to understand adaptive
and social behaviours.
A Novel Microbial Habitat In The Mid-Ocean Ridge Subseafloor, PNAS
Abstract: The subseafloor at the mid-ocean ridge
is predicted to be an excellent microbial habitat, because there
is abundant space, fluid flow, and geochemical energy in the
porous, hydrothermally influenced oceanic crust. These
characteristics also make it a good analog for potential
subsurface extraterrestrial habitats. Subseafloor environments
created by the mixing of hot hydrothermal fluids and seawater are
predicted to be particularly energy-rich, and hyperthermophilic
microorganisms that broadly reflect such predictions are ejected
from these systems in low-temperature (15°C), basalt-hosted
diffuse effluents. Seven hyperthermophilic heterotrophs isolated
from low-temperature diffuse fluids exiting the basaltic crust in
and near two hydrothermal vent fields on the Endeavour Segment,
Juan de Fuca Ridge, were compared phylogenetically and
physiologically to six similarly enriched hyperthermophiles from
samples associated with seafloor metal sulfide structures. The 13
organisms fell into four distinct groups: one group of two
organisms corresponding to the genus Pyrococcus and three groups
corresponding to the genus Thermococcus. Of these three groups,
one was composed solely of sulfide-derived organisms, and the
other two related groups were composed of subseafloor organisms.
There was no evidence of restricted exchange of organisms between
sulfide and subseafloor habitats, and therefore this phylogenetic
distinction indicates a selective force operating between the two
habitats. Hypotheses regarding the habitat differences were
generated through comparison of the physiology of the two groups
of hyperthermophiles; some potential differences between these
habitats include fluid flow stability, metal ion concentrations,
and sources of complex organic matter.
-
Abstract: Recent studies of microorganisms have
revealed diverse complex social behaviors, including cooperation
in foraging, building, reproducing, dispersing and communicating.
These microorganisms should provide novel, tractable systems for
the analysis of social evolution. The application of evolutionary
and ecological theory to understanding their behavior will aid in
developing better means to control the many pathogenic bacteria
that use social interactions to affect humans.
Structural Colour: Now You See It --- Now You Don't, Nature
Excerpt: The second, more striking effect arising from
the tilted multilayering accounts for the strongly bistable nature
of the wing reflectivity in diffuse white light: it is either
'on', when an observer sees one of a broad range of colours, or it
is 'off' and produces no reflected iridescence. (…)
This structural arrangement is important in signalling by
the butterfly. On or near the edge of the A. meliboeus dark zone,
wing movements of no more than a few degrees generate
ultra-high-contrast colour flicker in reflectivity.
Invariant Scaling Relationships For Interspecific Plant Biomass Production Rates And Body Size, PNAS
Abstract: The allometric relationships for plant
annualized biomass production ("growth") rates, different measures
of body size (dry weight and length), and photosynthetic biomass
(or pigment concentration) per plant (or cell) are reported for
multicellular and unicellular plants representing three algal
phyla; aquatic ferns; aquatic and terrestrial herbaceous dicots;
and arborescent monocots, dicots, and conifers. Annualized rates
of growth G scale as the 3/4-power of body mass M over 20 orders
of magnitude of M (i.e., G M3/4); plant body length L
(i.e., cell length or plant height) scales, on average, as the
1/4-power of M over 22 orders of magnitude of M (i.e., L
M1/4); and photosynthetic biomass Mp scales as the
3/4-power of nonphotosynthetic biomass Mn (i.e., Mp
Mn3/4). Because these scaling relationships are
indifferent to phylogenetic affiliation and habitat, they have
far-reaching ecological and evolutionary implications (e.g., net
primary productivity is predicted to be largely insensitive to
community species composition or geological age).
Scaling Of Growth: Plants And Animals Are Not So Different, PNAS
Excerpt: The relationship of body
size to the anatomical, physiological, behavioral, and ecological
characteristics of animals has long been a focus of interest in
zoology. As one considers animal species of different sizes,
regular, predictable changes are seen in the relative proportions
of the body's organs and the relative rates of physiological
processes such as metabolism and growth. Students of zoology are
familiar with these scaling relationships (also called
allometries) and many of their ecological and adaptive
implications (1-3). For example, the relative scaling of
metabolism versus that of the volume of the digestive tract
affects the potential diets of herbivorous mammals, which in turn
influences their social behavior (4, 5).
Circuit Training, Nature
Abstract: Robots that can assemble themselves from
components smaller than bacteria are beginning to seem less like
science fiction. A team at Pennsylvania State University has used
DNA to encourage gold wires millionths of a millimetre across to
take up specific positions on a gold surface, bringing self-wiring
nano-circuitry within the bounds of possibility.(…)
The wires whose DNA strands matched those on the surface
were up to four times more likely to become attached than those
with non-complementary DNA tags, Mallouk's group found.
Nanohedra: Using Symmetry To Design Self Assembling Protein Cages, Layers, Crystals, And Filaments, PNAS
Abstract: A general strategy is described for
designing proteins that self assemble into large symmetrical
nanomaterials, including molecular cages, filaments, layers, and
porous materials. In this strategy, one molecule of protein A,
which naturally forms a self-assembling oligomer, An,
is fused rigidly to one molecule of protein B, which forms another
self-assembling oligomer, Bm. The result is a fusion
protein, A-B, which self assembles with other identical copies of
itself into a designed nanohedral particle or material,
(A-B)p. The strategy is demonstrated through the
design, production, and characterization of two fusion proteins: a
49-kDa protein designed to assemble into a cage approximately 15
nm across, and a 44-kDa protein designed to assemble into long
filaments approximately 4 nm wide. The strategy opens a way to
create a wide variety of potentially useful protein-based
materials, some of which share similar features with natural
biological assemblies.
Recent Improvements In Prediction Of Protein Structure By Global Optimization Of A Potential Energy Function, PNAS
Abstract: Recent improvements of a
hierarchical ab initio or de novo approach for predicting both
a and b
structures of proteins are described. The united-residue energy
function used in this procedure includes multibody interactions
from a cumulant expansion of the free energy of polypeptide
chains, with their relative weights determined by Z-score
optimization. The critical initial stage of the hierarchical
procedure involves a search of conformational space by the
conformational space annealing (CSA) method, followed by
optimization of an all-atom model. The procedure was assessed in a
recent blind test of protein structure prediction (CASP4). The
resulting lowest-energy structures of the target proteins (ranging
in size from 70 to 244 residues) agreed with the experimental
structures in many respects. The entire experimental structure of
a cyclic a -helical
protein of 70 residues was predicted to within 4.3 Å
a -carbon
(Ca) rms
deviation (rmsd) whereas, for other a
-helical proteins, fragments of roughly 60 residues
were predicted to within 6.0 Å Ca
rmsd. Whereas b
structures can now be predicted with the new
procedure, the success rate for a
/b- and
-proteins is lower than that for a
-proteins at present. For the b
portions of a
/b
structures, the Ca
rmsd's are less than 6.0 Å for contiguous
fragments of 30-40 residues; for one target, three fragments (of
length 10, 23, and 28 residues, respectively) formed a compact
part of the tertiary structure with a Ca
rmsd less than 6.0 Å. Overall, these results
constitute an important step toward the ab initio prediction of
protein structure solely from the amino acid sequence.
- Recent
Improvements In Prediction Of Protein Structure By
Global Optimization Of A Potential Energy
Function, Jaroslaw
Pillardy, Cezary Czaplewski, Adam Liwo, Jooyoung Lee,
Daniel, R. Ripoll, Rajmund Kazmierkiewicz, Stanislaw
Oldziej, William J. Wedemeyer, Kenneth D. Gibson,
Yelena A. Arnautova, Jeff Saunders, Yuan-Jie Ye, and
Harold A. Scheraga, PNAS 2001;98 2329-2333
Solvent Effects On The Energy Landscapes And Folding Kinetics Of Polyalanine, PNAS
Abstract: The effect of a solvation on the
thermodynamics and kinetics of polyalanine (Ala12) is
explored on the basis of its energy landscapes in vacuum and in an
aqueous solution. Both energy landscapes are characterized by two
basins, one associated with a
-helical structures and the other with coil and
b-structures of the
peptide. In both environments, the basin that corresponds to the
a -helical structure is
considerably narrower than the basin corresponding to the
b -state, reflecting
their different contributions to the entropy of the peptide. In
vacuum, the a -helical
state of Ala12 constitutes the native state, in
agreement with common helical propensity scales, whereas in the
aqueous medium, the a
-helical state is destabilized, and the
b -state becomes the
native state. Thus solvation has a dramatic effect on the energy
landscape of this peptide, resulting in an inverted stability of
the two states. Different folding and unfolding time scales for
Ala12 in hydrophilic and hydrophobic chemical
environments are caused by the higher entropy of the native state
in water relative to vacuum. The concept of a helical propensity
has to be extended to incorporate environmental solvent effects.
Two Different Neurodegenerative Diseases Caused By Proteins With Similar Structures, PNAS
Abstract: The downstream prion-like protein
(doppel, or Dpl) is a paralog of the cellular prion protein,
PrPC. The two proteins have ~25%
sequence identity, but seem to have distinct physiologic roles.
Unlike PrPC, Dpl does not support prion replication;
instead, overexpression of Dpl in the brain seems to cause a
completely different neurodegenerative disease. We report the
solution structure of a fragment of recombinant mouse Dpl
(residues 26-157) containing a globular domain with three helices
and a small amount of b-structure.
Overall, the topology of Dpl is very similar to that of
PrPC. Significant differences include a marked kink in
one of the helices in Dpl, and a different orientation of the two
short b-strands. Although
the two proteins most likely arose through duplication of a single
ancestral gene, the relationship is now so distant that only the
structures retain similarity; the functions have diversified along
with the sequence.
Brain Cells Research Fuels Debate, Financial Times
US scientists have produced laboratory mice in which
as much as a quarter of the brain cells are human, in a
development that could carry great promise for treating disease
but poses questions about the boundaries between people and
animals.
The scientists are now considering a research project to
grow a mouse whose brain is populated almost entirely with human
cells, but are worried by the ethics.
The research could lead to treatments for diseases such as
Parkinson's, Alzheimer's and stroke by regenerating patients'
brains with healthy cells.
-
A mouse with a brain that is
biochemically human would be a scientific goldmine. It would help
basic research in neurobiology, while giving pharmacologists the
best possible system for testing drugs on the brain before
starting clinical trials.
In the short term, the risks of going ahead are small.
(…) Scientists would just be taking advantage of the fact
that the biological and genetic gap between us and other living
creatures turns out to be much smaller than anyone had
suspected.
Synergistic Contributions Of Cyclin-Dependant Kinase 5/P35 And Reelin/Dab1 To The Positioning Of Cortical Neurons In The Developing Mouse Brain, PNAS
Abstract: Cyclin-dependent kinase (Cdk) 5 is a
unique member of the Cdk family, because Cdk5 kinase activity is
detected only in the nervous tissue. Two neuron-specific
activating subunits of Cdk5, p35 and p39, have been identified.
Overlapping expression pattern of these isoforms in the embryonic
mouse brain and the significant residual Cdk5 kinase activity in
brain homogenate of the p35/ mice indicate the redundant functions
of the Cdk5 activators in vivo. Severe neuronal migration defects
in p35/Cdk5 +/ mice further support the idea that the redundant
expression of the Cdk5 activators may cause a milder phenotype in
p35/ mice compared with Cdk5/ mice. Mutant mice lacking either
Cdk5 or p35 exhibit certain similarities with Reelin/Dab1-mutant
mice in the disorganization of cortical laminar structure in the
brain. To elucidate the relationship between Cdk5/p35 and
Reelin/Dab1 signaling, we generated mouse lines that have combined
defects of these genes. The addition of heterozygosity of either
Dab1 or Reelin mutation to p35/ causes the extensive migration
defects of cortical neurons in the cerebellum. In the double-null
mice of p35 and either Dab1 or Reelin, additional migration
defects occur in the Purkinje cells in the cerebellum and in the
pyramidal neurons in the hippocampus. These additional defects in
neuronal migration in mice lacking both Cdk5/p35 and Reelin/Dab1
indicate that Cdk5/p35 may contribute synergistically to the
positioning of the cortical neurons in the developing mouse brain.
- Synergistic
Contributions Of Cyclin-Dependant Kinase 5/P35 And
Reelin/Dab1 To The Positioning Of Cortical Neurons In
The Developing Mouse
Brain,Toshio Ohshima,
Masaharu Ogawa, null Veeranna, Motoyuki Hirasawa,
Glenn Longenecker, Koichi Ishiguro, Harish C. Pant,
Roscoe O. Brady, Ashok B. Kulkarni, and Katsuhiko
Mikoshiba, PNAS 2001;98 2764-2769
Chaos On Centre Court, Nature
When bouncing a tennis ball, we instinctively navigate
our way around the complex world of mathematical chaos, new
research reveals.
On the face of it, the maths governing how a ball bounces on
a tennis racket are straightforward. But lurking inside the
equations is something called dynamical chaos.
Under certain conditions, the ball bounces regularly. But
change things just slightly and it all unravels: small
disturbances grow until the ball could end up anywhere.
Dynamics Of A Bouncing Ball In Human Performance, Rhys. Rev. E
Abstract: On the basis of a modified
bouncing-ball model, we investigated whether human movements
utilize principles of dynamic stability in their performance of a
similar movement task. Stability analyses of the model provided
predictions about conditions indicative of a dynamically stable
period-one regime. In a series of experiments, human subjects
bounced a ball rhythmically on a racket and displayed these
conditions supporting that they attuned to and exploited the
dynamic stability properties of the task.
-
Exerpts: Jokes are funny partly because they lead you
along one line of thought, only to take you in an unexpected
direction. (…).
The researchers used functional MRI to scan 14 healthy
people while they listened to two types of jokes. Half the jokes
were "semantic", for instance, "Why don't sharks bite lawyers?
Professional courtesy". The other half were puns, such as "Why did
the golfer wear two pairs of pants? He had a hole in one." Control
jokes were set-ups with punchless punchlines.(…)
Semantic jokes used a bilateral network in the temporal
lobes, whereas the puns used areas near those for speech
production, on the left side.
Did You Hear The One About The Prefrontal Cortex?, Nature
Excerpt: So although getting jokes might
be specific to different regions, responding to them happens in
the same place. "Irrespective of the kind of joke," says Dolan,
"it's the same system that's being accessed."
What's more, because this region is activated when humans
and primates receive rewards, it seems that the brain itself feels
rewarded by finding something funny. This, says Dolan, lends
credence to the idea that laughter might be therapeutic: "For some
people it's almost like a drug."
U.S. Scuttles Latest Chance to Avert Global Warming Catastrophe, Foreign Policy In Focus
Excerpt: Nonetheless, the U.S. insisted that it meet
its paltry obligation under the Kyoto Protocol (emissions
reductions of seven percent below 1990 levels) simply by planting
trees (known as carbon sinks), and by "emissions trading" with
countries too poor even to pollute. Refusing to cave to U.S.
pressure, the Europeans insisted that the U.S. get no more than
50% of its commitment from sinks and trading. The result was a
flameout of the talks.
In contrast, Europeans are deadly serious about the climate
crisis. Holland will cut emissions by 80% in the next 40 years.
Britain is committed to 60% cuts by 2050. Germany is considering
50% reductions over a similar period. They will achieve those cuts
not by planting trees but by drawing increasing proportions of
their energy from fuel cells, windfarms, and solar
systems.
Not only is the foot-dragging by the U.S. courting real
ecological catastrophe, it is also withholding from the U.S. and
the rest of the world a huge surge in jobs. In order to cut
emissions by 70% to allow the climate to stabilize, the planet
must be rewired with low-carbon and renewable technologies,
dramatically expanding the amount of wealth in the global
economy.
MIT Professor Claude Shannon Dies, MIT News Release
MIT Professor Emeritus Claude E. Shannon, known as the
father of modern digital communications and information theory,
died Saturday, February 24 at the Courtyard Nursing Care Center in
Medford, Mass., after a long battle with Alzheimer’s disease.
He was 84 years old.
Professor Shannon, a distant relative of Thomas Edison, was
affiliated with Bell Laboratories from 1941 to 1972, during which
time he wrote the landmark A Mathematical Theory of Communication
(1948). This pioneering paper on information theory begins by
observing that "the fundamental problem of communication is that
of reproducing at one point either exactly or approximately a
message selected at another point."
The information content of a message, he theorized, consists
simply of the number of 1s and 0s it takes to transmit it. "Nobody
had come close to this idea before," said MIT Professor emeritus
Robert G. Gallager, who worked with Professor Shannon. "This was
not something somebody else would have done for a very long time."
Links & Snippets
Other Articles
- The
Emergent Ego: Complexity And Coevolution In The
Psychoanalytic Process,
Harold I. Eist, Am. J. Psychiatry 2001 March 1; 158(3):
p. 505
- Spatiotemporal
Connectionist Networks: A Taxonomy and
Review, Stefan C.
Kremer, Neural Comp. 2001 February 1; 13(2): p.
249-306
- A
Competitive-Layer Model for Feature Binding and Sensory
Segmentation, Heiko
Wersing, Jochen J. Steil, Helge Ritter, Neural Comp. 2001
February 1; 13(2): p. 357-387
Pub Alert
These references can be found in http://www.thescientificworld.com/.
To retrieve the articles connect to the site and search for the
title.
- Joyce, Chaos, and Complexity, by
Thomas Jackson Rice, Dasenbrock, R. W.; Mines, R., JAMES
JOYCE QUARTERLY
- p53 from complexity to simplicity:
mutant p53 stabilization, gain-of-function, and
dominant-negative effect, Blagosklonny, M. V., FASEB
JOURNAL
- A Relative Complexity Metric for
Decision-theoretic Applications in Complex Systems,
Bendett, R. M.; Neelakanta, P. S., COMPLEX SYSTEMS
-CHAMPAIGN-
- Environmental risk assessment of a
complex solid waste product from a pesticide factory,
Winther-Nielsen, M.; Rasmussen, D.; Samsoe-Petersen, L.,
EUROPEAN WATER MANAGEMENT
- Fats in the new millennium: more
complexity but a better understanding? editorial
comment, Calder, P. C.; Deckelbaum, R. J., CURRENT OPINION
IN CLINICAL NUTRITION AND METABOLIC CARE
- Evaluation in Complex Policy
Systems, Sanderson, I., EVALUATION -LONDON-
- Development of Complex Scheme of
Ferruginous Waste Utilization, Smirnov, L. A.,
STAL'
- The complex decisions on the
transportation, dosing/dispensing and storage of powder-like
and granulated products, Unknown Author, PISHCHEVAIA
PROMYSHLENNOST' -MOSKVA- AGROPROMIZDAT-
- The search for complex disease genes:
fault by linkage or fault by association?, Baron, M.,
MOLECULAR PSYCHIATRY
- Minimum Wage and Overtime Rules are
Complex Issues for RNs, Unknown Author, KANSAS
NURSE
- Characterization of Complex
Chromosomal Abnormalities in Uveal Melanoma by Fluorescence
In Situ Hybridization, Spectral Karyotyping, and Comparative
Genomic Hybridization, Naus, N. C.; van Drunen, E.; de
Klein, A.; Luyten, G. P. M.; Paridaens, D. A.; Alers, J. C.;
Ksander, B. R.; Beverloo, H. B.; Slater, R. M., GENES
CHROMOSOMES AND CANCER
- The complexity of phenotypic
plasticity in the intertidal snail Nodilittorina
australis, Yeap, K. L.; Black, R.; Johnson, M. S.,
BIOLOGICAL JOURNAL- LINNEAN SOCIETY
- The Salience of Visuospatial and
Organizational Skills in Reproducing the Rey-Osterreith
Complex Figure in Subjects with High and Low IQs, Fujii,
D. E.; Lloyd, H. A.; Miyamoto, K., CLINICAL
NEUROPSYCHOLOGIST
Announcements
- Advances in Complex Systems (ACS) now
published by World
Scientific
- The
Evolution of Strong
Reciprocity, Santa Fe
Institute, Santa Fe, New Mexico, 01/03/9-11:
- Self-Organized
Complexity in the Physical, Biological and Social
Sciences, Arthur M.
Sackler Colloq. of the Natl. Acad. Sc., 01/03/23-24, Irvine,
CA
- SFI Workshop on The
Internet as a Large-Scale Complex
System", Santa Fe, NM,
01/03/29-31
- SFI Wkshp on Complexity
- Unifying Themes for the Sciences and New Frontiers for
Mathematics, MPI for Math in
Sci, Leipzig, Germany, 01/05/14-18
- SFI Workshop on Hierarchies
and Scale, Santa Fe, NM,
01/05/17-19
- Complex
Systems and Art,
NECSI/Santa Fe Art Institute, Santa Fe, NM, USA,
01/06/08
- 2nd
Europ Interdisp School on Nonlin Dyn for Syst & Sig Anal
, EUROATTRACTOR2001, Inst
Biocyb & Biomed Eng, Polish Acad Sci, Warsaw,
01/06/19-28
- SFI Graduate Workshop in
Computational
Economics, Santa Fe, NM,
01/07/15-28
- SFI Complex
Systems Summer School, Santa
Fe, NM, 01/06/10-07/07
- The 3nd Symp. on Systems Res.
in the Arts "Music,
Environmental Design, and the Choreography of
Space" , Baden-Baden,
Germany, 01/07/30-08/04
- SFI Complex
Systems Summer School,
Budapest, Santa Fe,
NM, 01/07/16-08/10
- SFI Workshop on Poverty
Traps," Santa Fe, NM,
01/07/20-22
- Intl. Conf.
DYNAMICAL NETWORKS IN COMPLEX
SYSTEMS, Kiel, Germany,
01/07/25-27
- SFI
Summer Workshop: Mathematical Models in Molecular and
Cellular Biology, Santa Fe,
New Mexico, 01/07/29-08/10
- 11th
Annual International Conference The Society For Chaos Theory
in Psychology & Life
Sciences, Madison, WI, USA,
01/08/3-6
- 5th
Intl Conf on COMPUTING ANTICIPATORY
SYSTEMS, Liege, Belgium,
August 13-18, 2001
- SFI Workshop on Economic
Inequality and Economic
Sustainability, Santa Fe,
NM,, 01/09/21-23
- Interdis.
Appl. of Ideas from Nonext. Stat. Mech. &
Thermodyn, Santa Fe, NM,
01/10/1-5
- Workshop on Intergenerational
Inequality, Santa Fe, NM,
01/10/19-21
- Chalmers
University of Technology in
Goteborg, Sweden, offers an
international Master's program in complex adaptive systems
starting in Sept. 2001
