Carlos Aguirre

• Autonomous University of Madrid

Dust devils are important phenomena to take into account to understand the global dust circulation of a planet. On Earth, their contribution to the injection of dust into the atmosphere seems to be secondary. Elsewhere, there are many indications that the dust devil’s role on other planets, in particular on Mars, could be fundamental, impacting the...

Synchronization, that occurs both for non-chaotic and chaotic systems, is a striking phenomenon with many practical implications in natural phenomena. However, even before synchronization, strong correlations occur in the collective dynamics of complex systems. To characterize their nature is essential for the understanding of phenomena in physical...

In this study we consider modelization associated with study of solar radiation at the surface of Mars and the Martian atmosphere. In particular, we present elements concerning retrieval of the solar irradiance spectrum on the surface of Mars from data collected by arrays of photodiodes, such as those onboard the “Curiosity” MSL-rover and other mis...

The inferior olive (IO) is a neural network belonging to the olivo-cerebellar system whose neurons are coupled with electrical synapses and display subthreshold oscillations and spiking activity. The IO generates complex spatio-temporal patterns. The generation and modulation of coherent spiking activity in the IO is one key issue in cerebellar res...

Modulatory effect of the IL in autonomous IO networks. Activity movie showing the modulatory effect of the IL in an autonomous IO network model where each neuron is connected to its eight nearest neighbors with an electrical coupling gc = 0.05 mS/cm2 (cf. Figures 6 and Figures 12D, which shows the DWT analysis).

Synchronized activity in an autonomous strongly coupled IO network model. The network displayed in this video is equivalent to the network in Movie S1 but with a strong electrical coupling (gc < 0.8 mS/cm2). In this situation, there is almost total synchronization among neurons (see Figure 4F), only broken briefly when spiking behavior occurs, and...

Nearly constant spatial pattern topology in the absence of subthreshold oscillations. The video shows the activity of an autonomous IO network of tonically spiking neurons without subthreshold oscillations where each unit is connected to four neighbors with a weak electrical coupling (gc < 0.05 mS/cm2). The spiking behavior is induced in all neuron...

Coexistence and coordination of spatio-temporal patterns induced by stimuli. Activity of an IO network with two external stimuli. The number of connected neighbors is eight with gc = 0.05 mS/cm2. External stimuli are introduced as a constant current injected in clusters of closed neurons. In this case, we consider two clusters of 6 × 6 cells with I...

Nearly independent activity in an autonomous weakly coupled IO network model. Each neuron is connected to four neighbors with a weak electrical coupling (gc < 0.001 mS/cm2). See section 2.3 for a description of the graphical representation. Note that the time scale does not correspond with the simulation time. For low coupling conductances, the act...

Spatio-temporal patterns in an autonomous IO network model with weak coupling extended to further neighbors. Each neuron is connected to 12 neighbors with a weak electrical coupling (gc < 0.01 mS/cm2). The effect of increasing the number of connections between neighbors is equivalent to increasing the coupling strength to a moderate magnitude (cf....

Modulatory effect of the IL in the presence of stimuli. Activity movie showing the modulatory effect of the IL in the same network model as in Movie S10 but in the presence of two external stimuli (cf. Figures 8C and Figures 12D, which shows the DWT analysis).

Spatio-temporal patterns of coordinated activity in an autonomous moderately coupled IO network model. The network displayed in this video is analogous to the network in Movies S1, S2 but with a moderate electrical coupling among cells (gc < 0.08 mS/cm2). In this case, the individual neurons have quasi-synchronized subthreshold activity (see Figure...

Encoding of multiple simultaneous rhythms. The network in this video is equivalent to the network in Movie S6, but with 25 stimulated clusters of 6 × 6 cells with different current injections. Figure 8B shows the approximate position of each cluster. The effect observed here is the same observed in Movie S6, but with many more coexisting spiking rh...

Stimulus reverberation allows short memory mechanisms in the IO models. Activity movie showing the stimulus reverberation effect in an IO network model where each neuron is connected to four nearest neighbors with electrical coupling gc = 0.05 mS/cm2. Individual neuron parameters in this simulation are σ = 2 and Iinj = 0.35 μA/cm2. Note that parame...

The source-sink phenomena allows the IO models to attract the wave fronts to specific locations. Note that in this video the color scale changes with respect to the one used in the rest of IO activity movies. Here, blue color means that the corresponding neuron is under the firing threshold, and red indicates that neurons are firing. To better illu...

Tomograms, a generalization of the Radon transform to arbitrary pairs of non-commuting operators, are positive bilinear transforms with a rigorous probabilistic interpretation which provide a full characterization of the signal and are robust in the presence of noise. Tomograms based on the time-frequency operator pair, were used in the past for co...

Spectral methods allow the estimation of the firing frequency in the activity of a single neuron. However, transient periods, changes in the neuron firing frequency or even changes in the neuron activity regime (rest, tonic firing or spiking) due to different inputs or to the presence of neurotransmitters are not well detected by means of these met...

Sets of coupled neurons can generate many different patterns in response to modulatory or sensory inputs. The study of how these patterns have been generated from the inputs has been object of great interest in the literature. These studies have been mainly performed by means of computer simulations, based on differential models or phenomenological...

Under the conditions prevalent in the late Pleistocene (small hunter-gatherer groups and frequent inter-group conflicts), coevolution of gene-related behavior and culturally transmitted group-level institutions provides a plausible explanation for the parochial altruistic and reciprocator traits of most modern humans. When, with the agricultural re...

In this work we propose the use of the discrete wavelet transform for the detection of multiple encoding rhythms that appear, for example, in spatio-temporal patterns generated by neuronal activity in a set of coupled neurons. The method here presented allows a quantitative characterization of spatio-temporal patterns and is based on the behavior o...

A network attack is a set of network elements that are disabled by an ad- versary. The goal for the attack is to produce the most possible damage to the network in terms of network connectivity by disabling the least possible number of network elements. We show that the problem of finding the optimal attack in a serverless net- work is NP-Complete...

Neural signatures are cell-specific interspike interval distributions found in bursting neurons. These intraburst signatures have been first described for the neurons of the pyloric CPG of crustacean. Their functional role is still unknown and their presence in other CPG systems has not been shown yet. Modeling has shown that neural signatures can...

In this work we study the formation of patterns of neuronal activity when some input are presented to the network. For this task a recently developed model of neuron is utilized. This model requires a very low computational effort but presents many characteristics of more complex models such as, spiking, bursting and sub-threshold oscillations, and...

Models of neurons based on iterative maps allows the simulation of big networks of coupled neurons without loss of biophysical properties such as spiking, bursting or tonic bursting and with an affordable computational effort. These models are built over a phenomenological basis and are mainly implemented by the use of iterative two-dimensional map...

A four-node network consisting of a negative circuit controlling a positive one is studied. It models some of the features of the p53 gene network. Using piecewise linear dynamics with thresholds, the allowed dynamical classes are fully characterized and coded. The biologically relevant situations are identified and conclusions drawn concerning the...

In modern communication networks it is interesting not only to know how fast packets can travel in the network, another parameter object of study is the number of information packets at each node of the network at time t. Some models of traffic in imperfect communication Networks has been proposed for the Internet, important fea-tures such as delay...

Models of neurons based on iterative maps allows the simulation of big networks of coupled neurons without loss of biophysical properties such as spiking, bursting or tonic bursting and with an affordable computational effort. A piecewise linear two dimensional map with one fast and one slow variable is used to model spiking–bursting neural behavio...

Models of neurons based on iterative maps allows the simulation of big networks of coupled neurons without loss of biophysical properties such as spiking, bursting or tonic bursting and with an affordable computational effort. A piecewise linear two dimensional map with one fast and one slow variable is used to model spiking–bursting neural behavio...

Models of neurons based on iterative maps allows the simulation of big networks of coupled neurons without loss of biophisical properties such as spiking, bursting or tonic bursting and with an affordable computational effort. In this work we explore by means of the use of Lyapunov ”energy” functions the asymptotic behavior of a set of coupled neur...

A four-node network consisting of a negative loop controlling a positive one is studied. It models some of the features of the p53 gene network. Using piecewise linear dynamics with thresholds, the allowed dynamical classes are fully characterized and coded. The biologically relevant situations are identified and conclusions drawn concerning the ef...

Internet can be considered as a Complex System where the temporal evolution of the transmission time between two fixed machines in the network it is known to be a chaotic time series of a dynamical system with positive Lyapunov exponents. This effect is due to the highly nonlinear behavior present in modern communication networks. Here a nonlinear...

In this paper we present a panoramic view of numerical simulations associated with nonlinear wave equations which appear in different experimental contexts. Mainly, we deal with scalar wave equations, but also the Maxwell equations in nonlinear media are studied. A basic part of this work is devoted to the construction and verification of numerical...

Cortical circuits are usually modeled as a network of excitatory and inhibitory neurons with a completely regular or a random connectivity pattern. However, neuroanatomy of the macaque and the cat cortex shows that cortical neurons are organized into densely linked groups that are sparsely and reciprocally interconnected. Interesting properties ari...

We present a computational study about the influence of the sensorimotor cortex on the processing of the cuneate nucleus during sleep as well as wakefulness. Realistic computational models were developed supported by experimental data obtained from intact-brain preparations in cat. Furthermore, a physiologically plausible circuit is proposed and pr...

Many real complex networks are believed to belong to a class called small-world (SW) networks. SW networks are graphs with high local clustering and small distances between nodes. A standard approach to constructing SW networks consists of varying the probability of rewiring each edge on a regular graph. As the initial substrate for the regular gra...

Small-World networks are highly clusterized networks with small distances between their nodes. There are some well known biological networks that present this kind of connectivity. On the other hand, the usual models of Small-World networks make use of undirected and unweighted graphs in order to represent the connectivity between the nodes of the...

We have built several networks of inferior olive (IO) model neurons to study the emerging spatio-temporal patterns of neuronal activity. The degree and extent of the electrical coupling, and the presence of stimuli were the main factors considered in the IO networks. The network activity was analyzed using a discrete wavelet transform which provide...

The underlying connection topology between agents in a multi-agent system (MAS) has a decisive inuence in the local and global behavior of the system and, therefore, it affects the measure of the eciency of the MAS at developing a speci c task.

This paper presents a general methodology for the design of dierent topologies in multi-agent networks with the central objective of maximizing agent collaboration.

This paper studies a specific methodology for the design of different topologies in multi-agent networks with the central objective of maximizing agent collaboration. In order to obtain this feature we rely on the use of a recently discovered type of topology, namely the “small world” (SW) topology. This topology has been shown to present several a...

The underlying connection topology between agents in amulti-agent system (MAS) has a decisive inuence in thelocal and global behavior of the system and, therefore, it affectsthe measure of the eciency of the MAS at developinga specic task.

Bank drafts are widely used as agreement documents for the deferred payment of goods and services. As such, they can be effectively negotiated, usually at a discount, by banks and other finacial intermediaries, as they represent money to be cashed at the arrival of a certain date. Since a huge amount of commercial transactions are financed this way...

In this paper a detailed description of the MIP project is presented. MIP (Intelligent Process Monitoring) is a Real-Time Expert System that monitors, diagnoses, and generates suggestions in real time about optimization and stability concerning the operation of a petrochemical plant. MIP software architecture is based on the concept of Blackboard....

In this paper a detailed description of the MIP project is presented. MIP (Intelligent Process Monitoring) is a Real-Time Expert System that monitors, diagnoses, and generates suggestions in real time about optimization and stability concerning the operation of a petrochemical plant. MIP software architecture is based on the concept of Blackboard....

In this work we study the formation of patterns of neuronal activity when some input are presented to the network. For this task a recently devel- oped model of neuron is utilized. This model requires a very low computational effort but presents many characteristics of more complex models such as, spiking, bursting and sub-threshold oscillations, a...