12,933 research outputs found
Coevolution of Camouflage
Camouflage in nature seems to arise from competition between predator and
prey. To survive, predators must find prey, and prey must avoid being found.
This work simulates an abstract model of that adversarial relationship. It
looks at crypsis through evolving prey camouflage patterns (as color textures)
in competition with evolving predator vision. During their "lifetime" predators
learn to better locate camouflaged prey. The environment for this 2D simulation
is provided by a set of photographs, typically of natural scenes. This model is
based on two evolving populations, one of prey and another of predators. Mutual
conflict between these populations can produce both effective prey camouflage
and predators skilled at "breaking" camouflage. The result is an open source
artificial life model to help study camouflage in nature, and the perceptual
phenomenon of camouflage more generally.Comment: 16 pages, 20 figure
Magnetism, FeS colloids, and Origins of Life
A number of features of living systems: reversible interactions and weak
bonds underlying motor-dynamics; gel-sol transitions; cellular connected
fractal organization; asymmetry in interactions and organization; quantum
coherent phenomena; to name some, can have a natural accounting via
interactions, which we therefore seek to incorporate by expanding the horizons
of `chemistry-only' approaches to the origins of life. It is suggested that the
magnetic 'face' of the minerals from the inorganic world, recognized to have
played a pivotal role in initiating Life, may throw light on some of these
issues. A magnetic environment in the form of rocks in the Hadean Ocean could
have enabled the accretion and therefore an ordered confinement of
super-paramagnetic colloids within a structured phase. A moderate H-field can
help magnetic nano-particles to not only overcome thermal fluctuations but also
harness them. Such controlled dynamics brings in the possibility of accessing
quantum effects, which together with frustrations in magnetic ordering and
hysteresis (a natural mechanism for a primitive memory) could throw light on
the birth of biological information which, as Abel argues, requires a
combination of order and complexity. This scenario gains strength from
observations of scale-free framboidal forms of the greigite mineral, with a
magnetic basis of assembly. And greigite's metabolic potential plays a key role
in the mound scenario of Russell and coworkers-an expansion of which is
suggested for including magnetism.Comment: 42 pages, 5 figures, to be published in A.R. Memorial volume, Ed
Krishnaswami Alladi, Springer 201
How the Dimension of Space Affects the Products of Pre-Biotic Evolution: The Spatial Population Dynamics of Structural Complexity and The Emergence of Membranes
We show that autocatalytic networks of epsilon-machines and their population
dynamics differ substantially between spatial (geographically distributed) and
nonspatial (panmixia) populations. Generally, regions of spacetime-invariant
autocatalytic networks---or domains---emerge in geographically distributed
populations. These are separated by functional membranes of complementary
epsilon-machines that actively translate between the domains and are
responsible for their growth and stability. We analyze both spatial and
nonspatial populations, determining the algebraic properties of the
autocatalytic networks that allow for space to affect the dynamics and so
generate autocatalytic domains and membranes. In addition, we analyze
populations of intermediate spatial architecture, delineating the thresholds at
which spatial memory (information storage) begins to determine the character of
the emergent auto-catalytic organization.Comment: 9 pages, 7 figures, 2 tables;
http://cse.ucdavis.edu/~cmg/compmech/pubs/ss.ht
Aerospace medicine and biology: A continuing bibliography with indexes, supplement 125
This special bibliography lists 323 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1974
Applying Membrane Systems in Food Engineering
Food engineering deals with manufacturing, packaging and distributing systems
for drug and food products. In this work, we discuss about the applicability of
membrane systems to model environmental conditions and their e ects on the produces
during storage of fresh fruits and vegetables. In particular, we are interested in abstract
molecular interactions that occur between produce, lm and surrounding atmosphere
factors involved in fresh fruit and vegetable package designs. We present a basic implementation
to simulate the dynamical behaviour of these systems, due to gas exchanges
and temperature
uctuations. Additionally, we reveal the bene ts of this modelling approach
and suggest some extensions as future directions to be considered
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