286,358 research outputs found
Interacting Individuals Leading to Zipf's Law
We present a general approach to explain the Zipf's law of city distribution.
If the simplest interaction (pairwise) is assumed, individuals tend to form
cities in agreement with the well-known statisticsComment: 4 pages 2 figure
Evolution of magnetic component in Yang-Mills condensate dark energy models
The evolution of the electric and magnetic components in an effective
Yang-Mills condensate dark energy model is investigated. If the electric field
is dominant, the magnetic component disappears with the expansion of the
Universe. The total YM condensate tracks the radiation in the earlier Universe,
and later it becomes thus is similar to the cosmological constant.
So the cosmic coincidence problem can be avoided in this model. However, if the
magnetic field is dominant, holds for all time, suggesting that it
cannot be a candidate for the dark energy in this case.Comment: 12 pages, 4 figures, minor typos correcte
Tuning electronic structure of graphene via tailoring structure: theoretical study
Electronic structures of graphene sheet with different defective patterns are
investigated, based on the first principles calculations. We find that
defective patterns can tune the electronic structures of the graphene
significantly. Triangle patterns give rise to strongly localized states near
the Fermi level, and hexagonal patterns open up band gaps in the systems. In
addition, rectangular patterns, which feature networks of graphene nanoribbons
with either zigzag or armchair edges, exhibit semiconducting behaviors, where
the band gap has an evident dependence on the width of the nanoribbons. For the
networks of the graphene nanoribbons, some special channels for electronic
transport are predicted.Comment: 5 figures, 6 page
Models of Financial Markets with Extensive Participation Incentives
We consider models of financial markets in which all parties involved find
incentives to participate. Strategies are evaluated directly by their virtual
wealths. By tuning the price sensitivity and market impact, a phase diagram
with several attractor behaviors resembling those of real markets emerge,
reflecting the roles played by the arbitrageurs and trendsetters, and including
a phase with irregular price trends and positive sums. The positive-sumness of
the players' wealths provides participation incentives for them. Evolution and
the bid-ask spread provide mechanisms for the gain in wealth of both the
players and market-makers. New players survive in the market if the
evolutionary rate is sufficiently slow. We test the applicability of the model
on real Hang Seng Index data over 20 years. Comparisons with other models show
that our model has a superior average performance when applied to real
financial data.Comment: 17 pages, 16 figure
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