2,845 research outputs found
Protocol Requirements for Self-organizing Artifacts: Towards an Ambient Intelligence
We discuss which properties common-use artifacts should have to collaborate
without human intervention. We conceive how devices, such as mobile phones,
PDAs, and home appliances, could be seamlessly integrated to provide an
"ambient intelligence" that responds to the user's desires without requiring
explicit programming or commands. While the hardware and software technology to
build such systems already exists, as yet there is no standard protocol that
can learn new meanings. We propose the first steps in the development of such a
protocol, which would need to be adaptive, extensible, and open to the
community, while promoting self-organization. We argue that devices,
interacting through "game-like" moves, can learn to agree about how to
communicate, with whom to cooperate, and how to delegate and coordinate
specialized tasks. Thus, they may evolve a distributed cognition or collective
intelligence capable of tackling complex tasks.Comment: To be presented at 5th International Conference on Complex System
Evolutionary Prisoner's Dilemma game on the Newman-Watts networks
Maintenance of cooperation was studied for a two-strategy evolutionary
Prisoner's Dilemma game where the players are located on a one-dimensional
chain and their payoff comes from games with the nearest and next-nearest
neighbor interactions. The applied host geometry makes possible to study the
impacts of two conflicting topological features. The evolutionary rule involves
some noise affecting the strategy adoptions between the interacting players.
Using Monte Carlo simulations and the extended versions of dynamical mean-field
theory we determined the phase diagram as a function of noise level and a
payoff parameter. The peculiar feature of the diagram is changed significantly
when the connectivity structure is extended by extra links as suggested by
Newman and Watts.Comment: 4 figure
Freezing and Slow Evolution in a Constrained Opinion Dynamics Model
We study opinion formation in a population that consists of leftists,
centrists, and rightist. In an interaction between neighboring agents, a
centrist and a leftist can become both centrists or leftists (and similarly for
a centrist and a rightist). In contrast, leftists and rightists do not affect
each other. The initial density of centrists rho_0 controls the evolution. With
probability rho_0 the system reaches a centrist consensus, while with
probability 1-rho_0 a frozen population of leftists and rightists results. In
one dimension, we determine this frozen state and the opinion dynamics by
mapping the system onto a spin-1 Ising model with zero-temperature Glauber
kinetics. In the frozen state, the length distribution of single-opinion
domains has an algebraic small-size tail x^{-2(1-psi)} and the average domain
size grows as L^{2*psi}, where L is the system length. The approach to this
frozen state is governed by a t^{-psi} long-time tail with psi-->2*rho_0/pi as
rho_0-->0.Comment: 4 pages, 6 figures, 2-column revtex4 format, for submission to J.
Phys. A. Revision contains lots of stylistic changes and 1 new result; the
main conclusions are the sam
Networking Effects on Cooperation in Evolutionary Snowdrift Game
The effects of networking on the extent of cooperation emerging in a
competitive setting are studied. The evolutionary snowdrift game, which
represents a realistic alternative to the well-known Prisoner's Dilemma, is
studied in the Watts-Strogatz network that spans the regular, small-world, and
random networks through random re-wiring. Over a wide range of payoffs, a
re-wired network is found to suppress cooperation when compared with a
well-mixed or fully connected system. Two extinction payoffs, that characterize
the emergence of a homogeneous steady state, are identified. It is found that,
unlike in the Prisoner's Dilemma, the standard deviation of the degree
distribution is the dominant network property that governs the extinction
payoffs.Comment: Changed conten
Hereditary sensory and autonomic neuropathies: types II, III, and IV
The hereditary sensory and autonomic neuropathies (HSAN) encompass a number of inherited disorders that are associated with sensory dysfunction (depressed reflexes, altered pain and temperature perception) and varying degrees of autonomic dysfunction (gastroesophageal reflux, postural hypotention, excessive sweating). Subsequent to the numerical classification of four distinct forms of HSAN that was proposed by Dyck and Ohta, additional entities continue to be described, so that identification and classification are ongoing. As a group, the HSAN are rare diseases that affect both sexes. HSAN III is almost exclusive to individuals of Eastern European Jewish extraction, with incidence of 1 per 3600 live births. Several hundred cases with HSAN IV have been reported. The worldwide prevalence of HSAN type II is very low. This review focuses on the description of three of the disorders, HSAN II through IV, that are characterized by autosomal recessive inheritance and onset at birth. These three forms of HSAN have been the most intensively studied, especially familial dysautonomia (Riley-Day syndrome or HSAN III), which is often used as a prototype for comparison to the other HSAN. Each HSAN disorder is likely caused by different genetic errors that affect specific aspects of small fiber neurodevelopment, which result in variable phenotypic expression. As genetic tests are routinely used for diagnostic confirmation of HSAN III only, other means of differentiating between the disorders is necessary. Diagnosis is based on the clinical features, the degree of both sensory and autonomic dysfunction, and biochemical evaluations, with pathologic examinations serving to further confirm differences. Treatments for all these disorders are supportive
Quantum Games and Quantum Strategies
We investigate the quantization of non-zero sum games. For the particular
case of the Prisoners' Dilemma we show that this game ceases to pose a dilemma
if quantum strategies are allowed for. We also construct a particular quantum
strategy which always gives reward if played against any classical strategy.Comment: 4 pages, 4 figures, typographic sign error in the definition of the
operator J correcte
Diffusing opinions in bounded confidence processes
We study the effects of diffusing opinions on the Deffuant et al. model for
continuous opinion dynamics. Individuals are given the opportunity to change
their opinion, with a given probability, to a randomly selected opinion inside
an interval centered around the present opinion. We show that diffusion induces
an order-disorder transition. In the disordered state the opinion distribution
tends to be uniform, while for the ordered state a set of well defined opinion
clusters are formed, although with some opinion spread inside them. If the
diffusion jumps are not large, clusters coalesce, so that weak diffusion favors
opinion consensus. A master equation for the process described above is
presented. We find that the master equation and the Monte-Carlo simulations do
not always agree due to finite-size induced fluctuations. Using a linear
stability analysis we can derive approximate conditions for the transition
between opinion clusters and the disordered state. The linear stability
analysis is compared with Monte Carlo simulations. Novel interesting phenomena
are analyzed
A Computational Approach for Designing Tiger Corridors in India
Wildlife corridors are components of landscapes, which facilitate the
movement of organisms and processes between intact habitat areas, and thus
provide connectivity between the habitats within the landscapes. Corridors are
thus regions within a given landscape that connect fragmented habitat patches
within the landscape. The major concern of designing corridors as a
conservation strategy is primarily to counter, and to the extent possible,
mitigate the effects of habitat fragmentation and loss on the biodiversity of
the landscape, as well as support continuance of land use for essential local
and global economic activities in the region of reference. In this paper, we
use game theory, graph theory, membership functions and chain code algorithm to
model and design a set of wildlife corridors with tiger (Panthera tigris
tigris) as the focal species. We identify the parameters which would affect the
tiger population in a landscape complex and using the presence of these
identified parameters construct a graph using the habitat patches supporting
tiger presence in the landscape complex as vertices and the possible paths
between them as edges. The passage of tigers through the possible paths have
been modelled as an Assurance game, with tigers as an individual player. The
game is played recursively as the tiger passes through each grid considered for
the model. The iteration causes the tiger to choose the most suitable path
signifying the emergence of adaptability. As a formal explanation of the game,
we model this interaction of tiger with the parameters as deterministic finite
automata, whose transition function is obtained by the game payoff.Comment: 12 pages, 5 figures, 6 tables, NGCT conference 201
A Cognitive Model of an Epistemic Community: Mapping the Dynamics of Shallow Lake Ecosystems
We used fuzzy cognitive mapping (FCM) to develop a generic shallow lake
ecosystem model by augmenting the individual cognitive maps drawn by 8
scientists working in the area of shallow lake ecology. We calculated graph
theoretical indices of the individual cognitive maps and the collective
cognitive map produced by augmentation. The graph theoretical indices revealed
internal cycles showing non-linear dynamics in the shallow lake ecosystem. The
ecological processes were organized democratically without a top-down
hierarchical structure. The steady state condition of the generic model was a
characteristic turbid shallow lake ecosystem since there were no dynamic
environmental changes that could cause shifts between a turbid and a clearwater
state, and the generic model indicated that only a dynamic disturbance regime
could maintain the clearwater state. The model developed herein captured the
empirical behavior of shallow lakes, and contained the basic model of the
Alternative Stable States Theory. In addition, our model expanded the basic
model by quantifying the relative effects of connections and by extending it.
In our expanded model we ran 4 simulations: harvesting submerged plants,
nutrient reduction, fish removal without nutrient reduction, and
biomanipulation. Only biomanipulation, which included fish removal and nutrient
reduction, had the potential to shift the turbid state into clearwater state.
The structure and relationships in the generic model as well as the outcomes of
the management simulations were supported by actual field studies in shallow
lake ecosystems. Thus, fuzzy cognitive mapping methodology enabled us to
understand the complex structure of shallow lake ecosystems as a whole and
obtain a valid generic model based on tacit knowledge of experts in the field.Comment: 24 pages, 5 Figure
Optical and Radio Observations of the Afterglow from GRB990510: Evidence for a Jet
We present multi-color optical and two-frequency radio observations of the
bright SAX event, GRB 990510. The well-sampled optical decay, together with the
radio observations are inconsistent with simple spherical afterglow models. The
achromatic optical steepening and the decay of the radio afterglow both
occuring at day are evidence for hydrodynamical evolution of the
source, and can be most easily interpreted by models where the GRB ejecta are
collimated in a jet. Employing a simple jet model to interpret the
observations, we derive a jet opening angle of , reducing the
isotropic gamma-ray emission of erg by a factor . If the jet interpretation is correct, we conclude that GRB observations
to-date are consistent with an energy for the central source of E \lsim
10^{52} erg.Comment: 12 pages, 2 figures. Version accepted for publication in ApJ Letter
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