40,880 research outputs found
Study of a model for the distribution of wealth
An equation for the evolution of the distribution of wealth in a population
of economic agents making binary transactions with a constant total amount of
"money" has recently been proposed by one of us (RLR). This equation takes the
form of an iterated nonlinear map of the distribution of wealth. The
equilibrium distribution is known and takes a rather simple form. If this
distribution is such that, at some time, the higher momenta of the distribution
exist, one can find exactly their law of evolution. A seemingly simple
extension of the laws of exchange yields also explicit iteration formulae for
the higher momenta, but with a major difference with the original iteration
because high order momenta grow indefinitely. This provides a quantitative
model where the spreading of wealth, namely the difference between the rich and
the poor, tends to increase with time.Comment: 12 pages, 2 figure
f(R) brane cosmology
Despite the nice features of the Dvali, Gabadadze and Porrati (DGP) model to
explain the late-time acceleration of the universe, it suffers from some
theoretical problems like the ghost issue. We present a way to self-accelerate
the normal DGP branch, which is known to be free of the ghost problem, by means
of an f(R) term on the brane action. We obtain the de Sitter self-accelerating
solutions of the model and study their stability under homogeneous
perturbations.Comment: 4 pages, 2 figures. Contribution to the proceedings of Spanish
Relativity Meeting 2009, Bilbao, Spain, 7-11 September 200
Detecting synchronization in spatially extended discrete systems by complexity measurements
The synchronization of two stochastically coupled one-dimensional cellular
automata (CA) is analyzed. It is shown that the transition to synchronization
is characterized by a dramatic increase of the statistical complexity of the
patterns generated by the difference automaton. This singular behavior is
verified to be present in several CA rules displaying complex behavior.Comment: 4 pages, 2 figures; you can also visit
http://add.unizar.es/public/100_16613/index.htm
Valadier-like formulas for the supremum function II: The compactly indexed case
We generalize and improve the original characterization given by Valadier
[20, Theorem 1] of the subdifferential of the pointwise supremum of convex
functions, involving the subdifferentials of the data functions at nearby
points. We remove the continuity assumption made in that work and obtain a
general formula for such a subdifferential. In particular, when the supremum is
continuous at some point of its domain, but not necessarily at the reference
point, we get a simpler version which gives rise to Valadier formula. Our
starting result is the characterization given in [10, Theorem 4], which uses
the epsilon-subdiferential at the reference point.Comment: 23 page
Banking industry evolution along the Texas-Mexico border
Maquiladora ; Income ; Remittances ; Emerging markets ; Federal Reserve Bank of Dallas ; Debit cards
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