4,195 research outputs found
Scaling laws and universality in the choice of election candidates
Nowadays there is an increasing interest of physicists in finding
regularities related to social phenomena. This interest is clearly motivated by
applications that a statistical mechanical description of the human behavior
may have in our society. By using this framework, we address this work to cover
an open question related to elections: the choice of elections candidates
(candidature process). Our analysis reveals that, apart from the social
motivations, this system displays features of traditional out-of-equilibrium
physical phenomena such as scale-free statistics and universality. Basically,
we found a non-linear (power law) mean correspondence between the number of
candidates and the size of the electorate (number of voters), and also that
this choice has a multiplicative underlying process (lognormal behavior). The
universality of our findings is supported by data from 16 elections from 5
countries. In addition, we show that aspects of network scale-free can be
connected to this universal behavior.Comment: Accepted for publication in EP
Hybrid method for simulating front propagation in reaction-diffusion systems
We study the propagation of pulled fronts in the
microscopic reaction-diffusion process using Monte Carlo (MC) simulations. In
the mean field approximation the process is described by the deterministic
Fisher-Kolmogorov-Petrovsky-Piscounov (FKPP) equation. In particular we
concentrate on the corrections to the deterministic behavior due to the number
of particles per site . By means of a new hybrid simulation scheme, we
manage to reach large macroscopic values of which allows us to show
the importance in the dynamics of microscopic pulled fronts of the interplay of
microscopic fluctuations and their macroscopic relaxation.Comment: 5 pages, 4 figure
Noise Effects on Synchronized Globally Coupled Oscillators
The synchronized phase of globally coupled nonlinear oscillators subject to
noise fluctuations is studied by means of a new analytical approach able to
tackle general couplings, nonlinearities, and noise temporal correlations. Our
results show that the interplay between coupling and noise modifies the
effective frequency of the system in a non trivial way. Whereas for linear
couplings the effect of noise is always to increase the effective frequency,
for nonlinear couplings the noise influence is shown to be positive or negative
depending on the problem parameters. Possible experimental verification of the
results is discussed.Comment: 6 Pages, 4 EPS figures included (RevTeX and epsfig needed). Submitted
to Phys. Re
Efficient design and evaluation of countermeasures against fault attacks using formal verification
This paper presents a formal verification framework and tool that evaluates the robustness of software countermeasures against fault-injection attacks. By modeling reference assembly code and its protected variant as automata, the framework can generate a set of equations for an SMT solver, the solutions of which represent possible attack paths. Using the tool we developed, we evaluated the robustness of state-of-the-art countermeasures against fault injection attacks. Based on insights gathered from this evaluation, we analyze any remaining weaknesses and propose applications of these countermeasures that are more robust
Dynamic renormalization group study of a generalized continuum model of crystalline surfaces
We apply the Nozieres-Gallet dynamic renormalization group (RG) scheme to a
continuum equilibrium model of a d-dimensional surface relaxing by linear
surface tension and linear surface diffusion, and which is subject to a lattice
potential favoring discrete values of the height variable. The model thus
interpolates between the overdamped sine-Gordon model and a related continuum
model of crystalline tensionless surfaces. The RG flow predicts the existence
of an equilibrium roughening transition only for d = 2 dimensional surfaces,
between a flat low-temperature phase and a rough high-temperature phase in the
Edwards-Wilkinson (EW) universality class. The surface is always in the flat
phase for any other substrate dimensions d > 2. For any value of d, the linear
surface diffusion mechanism is an irrelevant perturbation of the linear surface
tension mechanism, but may induce long crossovers within which the scaling
properties of the linear molecular-beam epitaxy equation are observed, thus
increasing the value of the sine-Gordon roughening temperature. This phenomenon
originates in the non-linear lattice potential, and is seen to occur even in
the absence of a bare surface tension term. An important consequence of this is
that a crystalline tensionless surface is asymptotically described at high
temperatures by the EW universality class.Comment: 22 pages, 5 figures. Accepted for publication in Physical Review
Does the quark cluster model predict any isospin two dibaryon resonance?
We analyze the possible existence of a resonance in the channel
with isospin two by means of nucleon- interactions based on the
constituent quark model. We solve the bound state and the scattering problem
using two different potentials, a local and a non-local one. The non-local
potential results to be the more attractive, although not enough to generate
the experimentally predicted resonance.Comment: 9 pages in Latex (revtex), 2 eps figures available under reques
Locating Planetesimal Belts in the Multiple-planet Systems HD 128311, HD 202206, HD 82943, and HR 8799
In addition to the Sun, six other stars are known to harbor multiple planets and debris disks: HD 69830, HD 38529, HD 128311, HD 202206, HD 82943, and HR 8799. In this paper, we set constraints on the location of the dust-producing planetesimals around the latter four systems. We use a radiative transfer model to analyze the spectral energy distributions of the dust disks (including two new Spitzer IRS spectra presented in this paper), and a dynamical model to assess the long-term stability of the planetesimals' orbits. As members of a small group of stars that show evidence of harboring a multiple planets and planetesimals, their study can help us learn about the diversity of planetary systems
Specialization of strategies and herding behavior of trading firms in a financial market
The understanding of complex social or economic systems is an important
scientific challenge. Here we present a comprehensive study of the Spanish
Stock Exchange showing that most financial firms trading in that market are
characterized by a resulting strategy and can be classified in groups of firms
with different specialization. Few large firms overally act as trending firms
whereas many heterogeneous firm act as reversing firms. The herding properties
of these two groups are markedly different and consistently observed over a
four-year period of trading.Comment: 8 pages, 5 figure
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