7,254 research outputs found
Power accretion in social systems
We consider a model of power distribution in a social system where a set of agents plays a simple game on
a graph: The probability of winning each round is proportional to the agent’s current power, and the winner
gets more power as a result. We show that when the agents are distributed on simple one-dimensional and
two-dimensional networks, inequality grows naturally up to a certain stationary value characterized by a clear
division between a higher and a lower class of agents. High class agents are separated by one or several lower
class agents which serve as a geometrical barrier preventing further flow of power between them. Moreover,
we consider the effect of redistributive mechanisms, such as proportional (nonprogressive) taxation. Sufficient
taxation will induce a sharp transition towards a more equal society, and we argue that the critical taxation level
is uniquely determined by the system geometry. Interestingly, we find that the roughness and Shannon entropy
of the power distributions are a very useful complement to the standard measures of inequality, such as the Gini
index and the Lorenz curveWe acknowledge financial support from the Spanish Government through
Grants No. FIS2015-69167-C2-1-P, No. FIS2015-66020-C2-
1-P, and No. PGC2018-094763-B-I0
Flux through a time-periodic gate: Monte Carlo test of a homogenization result
We investigate via Monte Carlo numerical simulations and theoretical
considerations the outflux of random walkers moving in an interval bounded by
an interface exhibiting channels (pores, doors) which undergo an open/close
cycle according to a periodic schedule. We examine the onset of a limiting
boundary behavior characterized by a constant ratio between the outflux and the
local density, in the thermodynamic limit. We compare such a limit with the
predictions of a theoretical model already obtained in the literature as the
homogenization limit of a suitable diffusion problem
La comunidad por-venir
El presente ensayo reflexiona sobre el concepto de comunidad y sobre las formas de pensamiento en grado de interrumpir la totalizadora y a menudo violenta homogeneidad de la identidad (o de la diferencia), es decir, sobre la prioridad del sujeto y el pap
Influence of the notch-sharpening technique on styrene-acrylonitrile fracture behavior
The Centre Catala del Plastic and Universidad Rey Juan Carlos laboratories joined forces to investigate the effect of the notch-sharpening technique on the fracture parameters of styrene-acrylonitrile. Contact notch-sharpening techniques, such as razor tapping, razor sliding, and razor broaching, and a noncontact procedure, femtolaser, were analyzed. The fracture values of the samples with notches sharpened via contact techniques were divided into two groups: one with pop-in and the other with no pop-in in the load-displacement records; this resulted in the lowest and highest fracture toughnesses, respectively. The fracture parameters of the specimens with notches sharpened via a femtolaser were between those of the samples with notches sharpened via contact procedures in which pop-in occurred and those in which it did not. To explain these results, the crack front of the nontested specimens after sharpening was investigated in depth, we identified the type of damage and measured its size and the crack tip radii. The morphology of the crack front was related to the fractographic study.Postprint (author's final draft
Constraining Fundamental Physics with Future CMB Experiments
The Planck experiment will soon provide a very accurate measurement of Cosmic
Microwave Background anisotropies. This will let cosmologists determine most of
the cosmological parameters with unprecedented accuracy. Future experiments
will improve and complement the Planck data with better angular resolution and
better polarization sensitivity. This unexplored region of the CMB power
spectrum contains information on many parameters of interest, including
neutrino mass, the number of relativistic particles at recombination, the
primordial Helium abundance and the injection of additional ionizing photons by
dark matter self-annihilation. We review the imprint of each parameter on the
CMB and forecast the constraints achievable by future experiments by performing
a Monte Carlo analysis on synthetic realizations of simulated data. We find
that next generation satellite missions such as CMBPol could provide valuable
constraints with a precision close to that expected in current and near future
laboratory experiments. Finally, we discuss the implications of this
intersection between cosmology and fundamental physics.Comment: 11 pages, 14 figure
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