Online social networks are ubiquitous, have billions of users, and produce large amounts of data.... more Online social networks are ubiquitous, have billions of users, and produce large amounts of data. While platforms like Reddit are based on a forum-like organization where users gather around topics, Facebook and Twitter implement a concept in which individuals represent the primary entity of interest. This makes them natural testbeds for exploring individual behavior in large social networks. Underlying these individual-based platforms is a network whose “friend” or “follower” edges are of binary nature only and therefore do not necessarily reflect the level of acquaintance between pairs of users. In this paper,we present the network of acquaintance “strengths” underlying the German Twittersphere. To that end, we make use of the full non-verbal information contained in tweet–retweet actions to uncover the graph of social acquaintances among users, beyond pure binary edges. The social connectivity between pairs of users is weighted by keeping track of the frequency of shared content ...
<p>Dependence of the coefficients (a) <i>C</i><sub>0</sub>, (b) <... more <p>Dependence of the coefficients (a) <i>C</i><sub>0</sub>, (b) <i>C</i><sub>1</sub>, and (c) <i>C</i><sub>2</sub> in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190448#pone.0190448.e004" target="_blank">Eq (4)</a> on the activation frequency <i>f</i>; (d) the <i>R</i><sup>2</sup> values of the corresponding fits.</p
<p>Dependence of the coefficients in <a href="http://www.plosone.org/article/info:d... more <p>Dependence of the coefficients in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190448#pone.0190448.e026" target="_blank">Eq (5)</a> on the activation frequency <i>f</i>, where the symbol assignment refers to the different APD<sub><i>n</i></sub> as given in the inset of the last graph, which shows the <i>R</i><sup>2</sup> values of the corresponding fits [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190448#pone.0190448.e026" target="_blank">Eq (5)</a>].</p
We analyze the empirical series of malaria incidence, using the concepts of autocorrelation, Hurs... more We analyze the empirical series of malaria incidence, using the concepts of autocorrelation, Hurst exponent and Shannon entropy with the aim of uncovering hidden variables in those series. From the simulations of an agent model for malaria spreading, we first derive models of the malaria incidence, the Hurst exponent and the entropy as functions of gametocytemia, measuring the infectious power of a mosquito to a human host. Second, upon estimating the values of three observables—incidence, Hurst exponent and entropy—from the data set of different malaria empirical series we predict a value of the gametocytemia for each observable. Finally, we show that the independent predictions show considerable consistency with only a few exceptions which are discussed in further detail.
With the aim of improving the reconstruction of stochastic evolution equations from empirical tim... more With the aim of improving the reconstruction of stochastic evolution equations from empirical time-series data, we derive a full representation of the generator of the Kramers–Moyal operator via a power-series expansion of the exponential operator. This expansion is necessary for deriving the different terms in a stochastic differential equation. With the full representation of this operator, we are able to separate finite-time corrections of the power-series expansion of arbitrary order into terms with and without derivatives of the Kramers–Moyal coefficients. We arrive at a closed-form solution expressed through conditional moments, which can be extracted directly from time-series data with a finite sampling intervals. We provide all finite-time correction terms for parametric and non-parametric estimation of the Kramers–Moyal coefficients for discontinuous processes which can be easily implemented—employing Bell polynomials—in time-series analyses of stochastic processes. With ex...
We study fully synchronized (coherent) states in complex networks of chaotic oscillators, reviewi... more We study fully synchronized (coherent) states in complex networks of chaotic oscillators, reviewing the analytical approach of determining the stability conditions for synchronizability and comparing them with numerical criteria. As an example, we present detailed results for networks of chaotic logistic maps having three different scale-free topologies: random scale-free topology, deterministic pseudo-fractal scale-free network and Apollonian network. For random scale-free topology we find that the lower boundary of the synchronizability region scales approximately as k−μ, where k is the outgoing connectivity and μ depends on the local nonlinearity. For deterministic scale-free networks coherence is observed only when the coupling is heterogeneous, namely when it is proportional to some power of the neighbour connectivity. In all cases, stability conditions are determined from the eigenvalue spectrum of the Laplacian matrix and agree well with numerical results based on histograms ...
In this paper we described how to build an inexpensive eye-tracker and to apply it to social incl... more In this paper we described how to build an inexpensive eye-tracker and to apply it to social inclusion and educational activities in schools. The building of the device includes both the construction of the eye-tracking headset as well as the implementation of the code for translating eye trajectories into output data which can afterwards be analyzed and modeled. The procedure is cheap and can be easily implemented in high-schools and first-years undergraduate courses, to teach specific matters in computer sciences, physical sciences and mathematics. Moreover, we also discuss up to which extension such a cheap device can substitute commercial solutions for promoting social inclusion, particularly to develop empathy in communities by showing the difficulties behind eye-movement languages used by non-verbal paralyzed individuals.
Using an agent-based model of malaria, we present numerical evidence that in communities of indiv... more Using an agent-based model of malaria, we present numerical evidence that in communities of individuals having an affinity varying within a broad range of values, disease transmission may increase up to 300%. Moreover, our findings provide new insight into how to combine different strategies for the prevention of malaria transmission. In particular, we uncover a relationship between the level of heterogeneity and the level of conventional and unconventional anti-malarial drug administration (ivermectin and gametocidal agents), which, when taken together, will define a control parameter, tuning between disease persistence and elimination. Finally, we also provide evidence that the entomological inoculation rate, as well as the product between parasite and sporozoite rates are both good indicators of malaria incidence in the presence of heterogeneity in disease transmission and may configure a possible improvement in that setting, upon classical standard measures such as the basic rep...
Online social networks are ubiquitous, have billions of users, and produce large amounts of data.... more Online social networks are ubiquitous, have billions of users, and produce large amounts of data. While platforms like Reddit are based on a forum-like organization where users gather around topics, Facebook and Twitter implement a concept in which individuals represent the primary entity of interest. This makes them natural testbeds for exploring individual behavior in large social networks. Underlying these individual-based platforms is a network whose “friend” or “follower” edges are of binary nature only and therefore do not necessarily reflect the level of acquaintance between pairs of users. In this paper,we present the network of acquaintance “strengths” underlying the German Twittersphere. To that end, we make use of the full non-verbal information contained in tweet–retweet actions to uncover the graph of social acquaintances among users, beyond pure binary edges. The social connectivity between pairs of users is weighted by keeping track of the frequency of shared content ...
<p>Dependence of the coefficients (a) <i>C</i><sub>0</sub>, (b) <... more <p>Dependence of the coefficients (a) <i>C</i><sub>0</sub>, (b) <i>C</i><sub>1</sub>, and (c) <i>C</i><sub>2</sub> in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190448#pone.0190448.e004" target="_blank">Eq (4)</a> on the activation frequency <i>f</i>; (d) the <i>R</i><sup>2</sup> values of the corresponding fits.</p
<p>Dependence of the coefficients in <a href="http://www.plosone.org/article/info:d... more <p>Dependence of the coefficients in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190448#pone.0190448.e026" target="_blank">Eq (5)</a> on the activation frequency <i>f</i>, where the symbol assignment refers to the different APD<sub><i>n</i></sub> as given in the inset of the last graph, which shows the <i>R</i><sup>2</sup> values of the corresponding fits [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0190448#pone.0190448.e026" target="_blank">Eq (5)</a>].</p
We analyze the empirical series of malaria incidence, using the concepts of autocorrelation, Hurs... more We analyze the empirical series of malaria incidence, using the concepts of autocorrelation, Hurst exponent and Shannon entropy with the aim of uncovering hidden variables in those series. From the simulations of an agent model for malaria spreading, we first derive models of the malaria incidence, the Hurst exponent and the entropy as functions of gametocytemia, measuring the infectious power of a mosquito to a human host. Second, upon estimating the values of three observables—incidence, Hurst exponent and entropy—from the data set of different malaria empirical series we predict a value of the gametocytemia for each observable. Finally, we show that the independent predictions show considerable consistency with only a few exceptions which are discussed in further detail.
With the aim of improving the reconstruction of stochastic evolution equations from empirical tim... more With the aim of improving the reconstruction of stochastic evolution equations from empirical time-series data, we derive a full representation of the generator of the Kramers–Moyal operator via a power-series expansion of the exponential operator. This expansion is necessary for deriving the different terms in a stochastic differential equation. With the full representation of this operator, we are able to separate finite-time corrections of the power-series expansion of arbitrary order into terms with and without derivatives of the Kramers–Moyal coefficients. We arrive at a closed-form solution expressed through conditional moments, which can be extracted directly from time-series data with a finite sampling intervals. We provide all finite-time correction terms for parametric and non-parametric estimation of the Kramers–Moyal coefficients for discontinuous processes which can be easily implemented—employing Bell polynomials—in time-series analyses of stochastic processes. With ex...
We study fully synchronized (coherent) states in complex networks of chaotic oscillators, reviewi... more We study fully synchronized (coherent) states in complex networks of chaotic oscillators, reviewing the analytical approach of determining the stability conditions for synchronizability and comparing them with numerical criteria. As an example, we present detailed results for networks of chaotic logistic maps having three different scale-free topologies: random scale-free topology, deterministic pseudo-fractal scale-free network and Apollonian network. For random scale-free topology we find that the lower boundary of the synchronizability region scales approximately as k−μ, where k is the outgoing connectivity and μ depends on the local nonlinearity. For deterministic scale-free networks coherence is observed only when the coupling is heterogeneous, namely when it is proportional to some power of the neighbour connectivity. In all cases, stability conditions are determined from the eigenvalue spectrum of the Laplacian matrix and agree well with numerical results based on histograms ...
In this paper we described how to build an inexpensive eye-tracker and to apply it to social incl... more In this paper we described how to build an inexpensive eye-tracker and to apply it to social inclusion and educational activities in schools. The building of the device includes both the construction of the eye-tracking headset as well as the implementation of the code for translating eye trajectories into output data which can afterwards be analyzed and modeled. The procedure is cheap and can be easily implemented in high-schools and first-years undergraduate courses, to teach specific matters in computer sciences, physical sciences and mathematics. Moreover, we also discuss up to which extension such a cheap device can substitute commercial solutions for promoting social inclusion, particularly to develop empathy in communities by showing the difficulties behind eye-movement languages used by non-verbal paralyzed individuals.
Using an agent-based model of malaria, we present numerical evidence that in communities of indiv... more Using an agent-based model of malaria, we present numerical evidence that in communities of individuals having an affinity varying within a broad range of values, disease transmission may increase up to 300%. Moreover, our findings provide new insight into how to combine different strategies for the prevention of malaria transmission. In particular, we uncover a relationship between the level of heterogeneity and the level of conventional and unconventional anti-malarial drug administration (ivermectin and gametocidal agents), which, when taken together, will define a control parameter, tuning between disease persistence and elimination. Finally, we also provide evidence that the entomological inoculation rate, as well as the product between parasite and sporozoite rates are both good indicators of malaria incidence in the presence of heterogeneity in disease transmission and may configure a possible improvement in that setting, upon classical standard measures such as the basic rep...
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Papers by Pedro G. Lind