1,896 research outputs found
Transparency effect in the emergence of monopolies in social networks
Power law degree distribution was shown in many complex networks. However, in
most real systems, deviation from power-law behavior is observed in social and
economical networks and emergence of giant hubs is obvious in real network
structures far from the tail of power law. We propose a model based on the
information transparency (transparency means how much the information is
obvious to others). This model can explain power structure in societies with
non-transparency in information delivery. The emergence of ultra powerful nodes
is explained as a direct result of censorship. Based on these assumptions, we
define four distinct transparency regions: perfect non-transparent, low
transparent, perfect transparent and exaggerated regions. We observe the
emergence of some ultra powerful (very high degree) nodes in low transparent
networks, in accordance with the economical and social systems. We show that
the low transparent networks are more vulnerable to attacks and the
controllability of low transparent networks is harder than the others. Also,
the ultra powerful nodes in the low transparent networks have a smaller mean
length and higher clustering coefficients than the other regions.Comment: 14 Pages, 3 figure
Synchronization in complex networks
Synchronization processes in populations of locally interacting elements are
in the focus of intense research in physical, biological, chemical,
technological and social systems. The many efforts devoted to understand
synchronization phenomena in natural systems take now advantage of the recent
theory of complex networks. In this review, we report the advances in the
comprehension of synchronization phenomena when oscillating elements are
constrained to interact in a complex network topology. We also overview the new
emergent features coming out from the interplay between the structure and the
function of the underlying pattern of connections. Extensive numerical work as
well as analytical approaches to the problem are presented. Finally, we review
several applications of synchronization in complex networks to different
disciplines: biological systems and neuroscience, engineering and computer
science, and economy and social sciences.Comment: Final version published in Physics Reports. More information
available at http://synchronets.googlepages.com
Rethinking network reciprocity over social ties: local interactions make direct reciprocity possible and pave the rational way to cooperation
Since Nowak & May's (1992) influential paper, network reciprocity--the fact
that individuals' interactions repeated within a local neighborhood support the
evolution of cooperation--has been confirmed in several theoretical models.
Essentially, local interactions allow cooperators to stay protected from
exploiters by assorting into clusters, and the heterogeneity of the network of
contacts--the co-presence of low- and high-connected nodes--has been shown to
further favor cooperation. The few available large-scale experiments on humans
have however missed these effects. The reason is that, while models assume that
individuals update strategy by imitating better performing neighbors,
experiments showed that humans are more prone to reciprocate cooperation than
to compare payoffs. Inspired by the empirical results, we rethink network
reciprocity as a rational form of direct reciprocity on networks--networked
rational reciprocity--indeed made possible by the locality of interactions. We
show that reciprocal altruism in a networked prisoner's dilemma can invade and
fixate in any network of rational agents, profit-maximizing over an horizon of
future interactions. We find that networked rational reciprocity works better
at low average connectivity and we unveil the role of network heterogeneity.
Only if cooperating hubs invest in the initial cost of exploitation, the
invasion of cooperation is boosted; it is otherwise hindered. Although humans
might not be as rational as here assumed, our results could help the design and
interpretation of new experiments in social and economic network
Designing fuzzy rule based classifier using self-organizing feature map for analysis of multispectral satellite images
We propose a novel scheme for designing fuzzy rule based classifier. An SOFM
based method is used for generating a set of prototypes which is used to
generate a set of fuzzy rules. Each rule represents a region in the feature
space that we call the context of the rule. The rules are tuned with respect to
their context. We justified that the reasoning scheme may be different in
different context leading to context sensitive inferencing. To realize context
sensitive inferencing we used a softmin operator with a tunable parameter. The
proposed scheme is tested on several multispectral satellite image data sets
and the performance is found to be much better than the results reported in the
literature.Comment: 23 pages, 7 figure
Engineering Robust and Programmable Biological Systems
The ability to engineer programmable biological systems using complex artificial gene networks has great potential to unlock important innovative solutions to many biotechnological challenges. While cells have been engineered to implement complex information processing algorithms and to produce food, materials, and pharmaceuticals, many innovative applications are yet to be realized due to our poor understanding of how robust, reliable, and predictable artificial gene circuits are built. In this work, we demonstrate that robust complex cellular behaviors (e.g., bistability and gene expression dynamics) can be achieved by engineering gene regulatory architecture and increasing the complexity of genetic networks. We further demonstrate that increasing demand for cellular resources causes resource-associated interference among noninteracting genetic devices of various complexities. Importantly, we show that feedback systems can be engineered to enhance the robustness and reliability of genetic circuits by reducing such resource-associated interference among independent circuits. Taken together, this work contributes to understanding the design principles that govern biological robustness and represents an important step towards construction of robust, tunable, reliable, and predictable complex artificial genetic circuits for a wide range of biotechnological applications
Connections Between Adaptive Control and Optimization in Machine Learning
This paper demonstrates many immediate connections between adaptive control
and optimization methods commonly employed in machine learning. Starting from
common output error formulations, similarities in update law modifications are
examined. Concepts in stability, performance, and learning, common to both
fields are then discussed. Building on the similarities in update laws and
common concepts, new intersections and opportunities for improved algorithm
analysis are provided. In particular, a specific problem related to higher
order learning is solved through insights obtained from these intersections.Comment: 18 page
Invited review: Epidemics on social networks
Since its first formulations almost a century ago, mathematical models for
disease spreading contributed to understand, evaluate and control the epidemic
processes.They promoted a dramatic change in how epidemiologists thought of the
propagation of infectious diseases.In the last decade, when the traditional
epidemiological models seemed to be exhausted, new types of models were
developed.These new models incorporated concepts from graph theory to describe
and model the underlying social structure.Many of these works merely produced a
more detailed extension of the previous results, but some others triggered a
completely new paradigm in the mathematical study of epidemic processes. In
this review, we will introduce the basic concepts of epidemiology, epidemic
modeling and networks, to finally provide a brief description of the most
relevant results in the field.Comment: 17 pages, 13 figure
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