347 research outputs found
Bipartisanship Breakdown, Functional Networks, and Forensic Analysis in Spanish 2015 and 2016 National Elections
In this paper we present a social network and forensic analysis of the vote
counts of Spanish national elections that took place in December 2015 and their
sequel in June 2016. Vote counts are extracted at the level of municipalities,
yielding an unusually high resolution dataset with over 8000 samples. We
initially consider the phenomenon of Bipartisanship breakdown by analysing
spatial distributions of several Bipartisanship indices. We find that such
breakdown is more prominent close to cosmopolite and largely populated areas
and less important in rural areas where Bipartisanship still prevails, and its
evolution mildly consolidates in the 2016 round, with some evidence of
Bipartisanship reinforcement which we hypothesize to be due to psychological
mechanisms of risk aversion. On a third step we explore to which extent vote
data are faithful by applying forensic techniques to vote statistics. We first
explore the conformance of first digit distributions to Benford's law for each
of the main political parties. The results and interpretations are mixed and
vary across different levels of aggregation, finding a general good
quantitative agreement at the national scale for both municipalities and
precincts but finding systematic nonconformance at the level of individual
precincts. As a complementary metric, we further explore the co-occurring
statistics of voteshare and turnout, finding a mild tendency in the clusters of
the conservative party to smear out towards the area of high turnout and
voteshare, what has been previously interpreted as a possible sign of
incremental fraud. In every case results are qualitatively similar between 2015
and 2016 elections.Comment: 23 pages, 21 figures, accepted for publication in Complexit
Joint effect of ageing and multilayer structure prevents ordering in the voter model
The voter model rules are simple, with agents copying the state of a random
neighbor, but they lead to non-trivial dynamics. Besides opinion processes, the
model has also applications for catalysis and species competition. Inspired by
the temporal inhomogeneities found in human interactions, one can introduce
ageing in the agents: the probability to update decreases with the time elapsed
since the last change. This modified dynamics induces an approach to consensus
via coarsening in complex networks. Additionally, multilayer networks produce
profound changes in the dynamics of models. In this work, we investigate how a
multilayer structure affects the dynamics of an ageing voter model. The system
is studied as a function of the fraction of nodes sharing states across layers
(multiplexity parameter q ). We find that the dynamics of the system suffers a
notable change at an intermediate value q*. Above it, the voter model always
orders to an absorbing configuration. While, below, a fraction of the
realizations falls into dynamical traps associated to a spontaneous symmetry
breaking in which the majority opinion in the different layers takes opposite
signs and that due to the ageing indefinitely delay the arrival at the
absorbing state.Comment: 10 pages, 8 figure
Election Forensics: Quantitative methods for electoral fraud detection
The last decade has witnessed an explosion on the computational power and a
parallel increase of the access to large sets of data (the so called Big Data
paradigm) which is enabling to develop brand new quantitative strategies
underpinning description, understanding and control of complex scenarios. One
interesting area of application concerns fraud detection from online data, and
more particularly extracting meaningful information from massive digital
fingerprints of electoral activity to detect, a posteriori, evidence of
fraudulent behavior. In this short article we discuss a few quantitative
methodologies that have emerged in recent years on this respect, which
altogether form the nascent interdisciplinary field of election forensics.Comment: Accepted for publication in Forensic Science Internationa
Surgical clavicle reconstruction after aneurysmal bone cyst resection in a child: A simple method
The clavicle is an infrequent location for primary tumors in general, and aneurysmal bone cyst (ABC) of the clavicle is particularly rare. The challenge of the functional and esthetic result in the treatment of these lesions in the pediatric population is high when considering the reconstruction of critical bone defects. In this article, we present the case of a seven -year -old boy with an ABC in the middle third of the clavicle, treated by resection and reconstruction with free autograft of the fibula stabilized by using an intramedullary titanium nail. We offer a description of the used technique, considerations about treatment options in children, and a follow-up of more than two -and -a -half years
Flow behaviour of glycolated water suspensions of functionalized graphene nanoplatelets
The heat transfer performance of the conventional fluids
used in heat exchange processes improves by dispersing
nanoparticles with high thermal conductivity, as many
researches have shown in the last decades. The heat transfer
capability of a fluid depends on several physical properties
among which the rheological behavior is very relevant, as we
have previously pointed out.
In this study, different samples of nanofluids have been
analyzed by using a DHR-2 rotational rheometer of TA
Instruments with concentric cylinder geometry in the
temperature range from (278.15 to 323.15) K. The used base
fluids were two different binary mixtures of propylene glycol
and water at (10:90)% and (30:70)% mass ratios. Two different
mass concentrations (viz. 0.25 and 0.5 wt.%) of graphene
nanoplatelets functionalized with sulfonic acid (graphenit-
HW6) were dispersed in these two base fluids.
Firstly, with the goal of checking and calibrating the
operation of the rheometer, the viscosity-shear stress curves for
pure propylene glycol, Krytox GPL102 oil, and the two base
fluids were experimentally determined. A detailed comparative
study with those well-known data over the entire range of
temperature was stabilized obtaining deviations in viscosity less
than 3.5%. Then, the flow curves of the different nanofluid
samples were studied at different temperatures to characterize
their flow behavior.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016
Zero Temperature Limit of Holographic Superconductors
We consider holographic superconductors whose bulk description consists of
gravity minimally coupled to a Maxwell field and charged scalar field with
general potential. We give an analytic argument that there is no "hard gap":
the real part of the conductivity at low frequency remains nonzero (although
typically exponentially small) even at zero temperature. We also numerically
construct the gravitational dual of the ground state of some holographic
superconductors. Depending on the charge and dimension of the condensate, the
infrared theory can have emergent conformal or just Poincare symmetry. In all
cases studied, the area of the horizon of the dual black hole goes to zero in
the extremal limit, consistent with a nondegenerate ground state.Comment: 27 pages, 8 figure
Ultraspinning instability: the missing link
We study linearized perturbations of Myers-Perry black holes in d=7, with two
of the three angular momenta set to be equal, and show that instabilities
always appear before extremality. Analogous results are expected for all higher
odd d. We determine numerically the stationary perturbations that mark the
onset of instability for the modes that preserve the isometries of the
background. The onset is continuously connected between the previously studied
sectors of solutions with a single angular momentum and solutions with all
angular momenta equal. This shows that the near-extremality instabilities are
of the same nature as the ultraspinning instability of d>5 singly-spinning
solutions, for which the angular momentum is unbounded. Our results raise the
question of whether there are any extremal Myers-Perry black holes which are
stable in d>5.Comment: 19 pages. 1 figur
A scalar field condensation instability of rotating anti-de Sitter black holes
Near-extreme Reissner-Nordstrom-anti-de Sitter black holes are unstable
against the condensation of an uncharged scalar field with mass close to the
Breitenlohner-Freedman bound. It is shown that a similar instability afflicts
near-extreme large rotating AdS black holes, and near-extreme hyperbolic
Schwarzschild-AdS black holes. The resulting nonlinear hairy black hole
solutions are determined numerically. Some stability results for (possibly
charged) scalar fields in black hole backgrounds are proved. For most of the
extreme black holes we consider, these demonstrate stability if the ``effective
mass" respects the near-horizon BF bound. Small spherical
Reissner-Nordstrom-AdS black holes are an interesting exception to this result.Comment: 34 pages; 13 figure
Informed consent and approval by institutional review boards in published reports on clinical trials
The Rich Structure of Gauss-Bonnet Holographic Superconductors
We study fully backreacting, Gauss-Bonnet (GB) holographic superconductors in
5 bulk spacetime dimensions. We explore the system's dependence on the scalar
mass for both positive and negative GB coupling, . We find that when
the mass approaches the Breitenlohner-Freedman (BF) bound and
the effect of backreaction is to increase the
critical temperature, , of the system: the opposite of its effect in the
rest of parameter space. We also find that reducing below zero
increases and that the effect of backreaction is diminished. We study the
zero temperature limit, proving that this system does not permit regular
solutions for a non-trivial, tachyonic scalar field and constrain possible
solutions for fields with positive masses. We investigate singular, zero
temperature solutions in the Einstein limit but find them to be incompatible
with the concept of GB gravity being a perturbative expansion of Einstein
gravity. We study the conductivity of the system, finding that the inclusion of
backreaction hinders the development of poles in the conductivity that are
associated with quasi-normal modes approaching the real axis from elsewhere in
the complex plane.Comment: 26 pages, 11 figures, V3, Added discussion of non-tachyonic scalars,
alterations to figures and tex
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