Dynamical phenomena in complex networks: fundamentals and applications

This special issue presents a series of 33 contributions in the area of dynamical networks and their applications. Part of the contributions is devoted to theoretical and methodological aspects of dynamical networks, such as collective dynamics of excitable systems, spreading processes, coarsening, synchronization, delayed interactions, and others. A particular focus is placed on applications to neuroscience and Earth science, especially functional climate networks. Among the highlights, various methods for dealing with noise and stochastic processes in neuroscience are presented. A method for constructing weighted networks with arbitrary topologies from a single dynamical node with delayed feedback is introduced. Also, a generalization of the concept of geodesic distances, a path-integral formulation of network-based measures is developed, which provides fundamental insights into the dynamics of disease transmission. The contributions from the Earth science application field substantiate predictive power of climate networks to study challenging Earth processes and phenomena

Natural configurations for formation flying around triangular libration points for the elliptic and the bicircular problem in the earth-moon system

The concept of Satellite Formation Flying (SFF) means to have two or more satellites in orbit such that their relative positions remain constant or obeying a certain dynamical configuration along the trajectory. This concept involves the control over the coordinated motion of a group of satellites, with the goal of maintaining a specific geometric space configuration between the elements of the cluster. Assume a constellation of satellites is flying close a given nominal trajectory around L 4 or L 5 in the Earth-Moon system, in such a way that, there is some freedom in the selection of the geometry of the constellation. We are interested in avoiding large variations of the mutual distances between spacecraft. In this case, previous studies about triangular libration points have determined the existence of regions of zero and minimum relative radial acceleration with respect to the nominal trajectory that prevent from the expansion or contraction of the constellation. Similarly, these studies have also shown the existence of regions of maximum relative radial acceleration with respect to the nominal trajectory that produce a larger expansion and contraction of the constellation. However, these studies only considered the gravitational force of the Earth and the Moon using as approximation the Circular Restricted Three Body Problem (CRTBP). Although the CRTBP model is a good approximation for the dynamics of spacecraft in the Earth-Moon system, the stability of constellations flying around L4 and L5 is strongly a ff ected when the primary orbit eccentricity and perturbations from the sun (gravity and light pressure) are considered. As consequence, the previous studies show that, using the CRTBP model, the fuel consumption to maintain the geometry of the constellation computed by the residual acceleration is practically zero. In this manner, the goal of this work is the study and analysis of the best regions to place a constellation that is flying close a given nominal trajectory around L 4 or L 5 , involving a linear approximation of the equations of motion relative to the periodic orbits around triangular libration points and taking into account the Moon’s eccentricity and perturbations from the Sun. This model is not only more realistic for practical engineering applications but permits to determine more accurately the fuel consumption to maintain the geometry of the constellationPostprint (published version

Alterations in brain connectivity due to plasticity and synaptic delay

Brain plasticity refers to brain's ability to change neuronal connections, as a result of environmental stimuli, new experiences, or damage. In this work, we study the effects of the synaptic delay on both the coupling strengths and synchronisation in a neuronal network with synaptic plasticity. We build a network of Hodgkin-Huxley neurons, where the plasticity is given by the Hebbian rules. We verify that without time delay the excitatory synapses became stronger from the high frequency to low frequency neurons and the inhibitory synapses increases in the opposite way, when the delay is increased the network presents a non-trivial topology. Regarding the synchronisation, only for small values of the synaptic delay this phenomenon is observed

Spatial permutation entropy distinguishes resting brain states

We use ordinal analysis and spatial permutation entropy to distinguish between eyes-open and eyes-closed resting brain states. To do so, we analyze EEG data recorded with 64 electrodes from 109 healthy subjects, under two one-minute baseline runs: One with eyes open, and one with eyes closed. We use spatial ordinal analysis to distinguish between these states, where the permutation entropy is evaluated considering the spatial distribution of electrodes for each time instant. We analyze both raw and post-processed data considering only the alpha-band frequency (8–12 Hz) which is known to be important for resting states in the brain. We conclude that spatial ordinal analysis captures information about correlations between time series in different electrodes. This allows the discrimination of eyes closed and eyes open resting states in both raw and filtered data. Filtering the data only amplifies the distinction between states. Importantly, our approach does not require EEG signal pre-processing, which is an advantage for real-time applications, such as brain-computer interfaces.B.R.R.B. and E.E.N.M. acknowledge support of São Paulo Research Foundation (FAPESP), Brazil, Proc. 2018/03211-6 and 2021/09839-0; and Financiadora de Estudos e Projetos (FINEP), Brazil. R.C.B. acknowledges support of Western Institute for Neuroscience Clinical Research Postdoctoral Fellowship and Western Academy for Advanced Research. K.L.R. acknowledges supported of German Academic Exchange Service (DAAD). C.M. acknowledges support of Ministerio de Ciencia, Innovación ������ Universidades (PID2021-123994NB-C21), Spain and Institució Catalana de Recerca i Estudis Avançats (ICREA), Spain.Peer ReviewedPostprint (published version

Una aproximación a las representaciones del alumnado sobre el Universo

This study explains how the children from secondary school (age 14-18) represent the structure of the universe and the way it may be useful in daily teaching. The results obtained describe the same conceptualization difficulties that the younger students already have, as well as the need for studying deeply the process for learning of those students as far as, having dealt with those contents before, they have not reached the expected scientific knowledge concerning the topic

Bailout Embeddings, Targeting of KAM Orbits, and the Control of Hamiltonian Chaos

We present a novel technique, which we term bailout embedding, that can be used to target orbits having particular properties out of all orbits in a flow or map. We explicitly construct a bailout embedding for Hamiltonian systems so as to target KAM orbits. We show how the bailout dynamics is able to lock onto extremely small KAM islands in an ergodic sea.Comment: 3 figures, 9 subpanel

Contenidos, metodología y alumnado : una valoración crítica de la enseñanza en BUP y COU

The aim of this study was to compare the interest of the students in Natural Science in front of three other subjects such as Mathematics, Literature and Geography & History. The selected items of the contents of every subject, and the importance of teaching as an influential factor on students were also studied. The results showed that both the selection of the contents and the methods should have been modified

Within-Person Variation in Personality and Psychological Well-Being

Personality is one of the most broad and complex areas in psychology. This has led to many researchers attempting to reduce this complexity by focusing solely on how habitual personality differs between each individual (inter-individual differences). This is important to study, but it has been focused on so heavily that research into how each individual personality varies within the person (intra-individual differences) has been neglected in comparison. Recent research has started to examine intra-individual variation in personality more thoroughly. One research aim of this programme was to establish the nature of several different types of within person variability including inter-item variation (variation within the test responses for a personality trait), and cross-contextual variation in personality (variation according to context), to see whether these types of variability are associated with psychological outcomes. Three research questions were examined to this end: 1) What is the extent of meaningful variability in personality trait test responding? 2) What are the predictors of intra-individual variability in personality? 3) What is the relative importance of the person and situational factors in personality variability? The first question was developed to try and determine whether the individual can display meaningful inter-item variation in ratings of specific behaviours within personality trait measures. Trait questionnaires are usually only analysed at the between subject level, and within subject variation in inter-item ratings have not been extensively examined in relation to meaningful psychological outcomes. The second and third questions were developed to look into the nature of cross-contextual personality, and establish whether within person personality differences are influenced more strongly by the person or situation. The studies conducted towards answering these questions demonstrated a person-based capacity to display intra-individual variability. A second aim of the research programme was to see whether the capacity to display these types of variability can be utilised in behaviour change. The fourth research question was developed to try and understand how a person can display intra-individual variability, yet still be resistant to changing negative habits: 4) How do the different aspects in personality variability help explain why some people are resistant to change, especially with regard to behaviours that are bad for them? This question was answered by theoretically discussing the findings from the three previous studies which proposed that positive or problematic behaviour could be interpreted with a simple path to understand the process of behavioural action: The individual receives feedback from a behaviour response which either validates or invalidates their action in the situation context (does or does not receive a desired outcome). Reinforcement of the behaviour happens if it is validated by positive feedback. Alternately reconstruction of the situation happens if the behaviour is invalidated. This allows for two types of intra-individual variability. One is flexibility in behaviour responses to different situations under the individual’s control. The other is change according to the situation, where the behaviour is invalidated and an alternative is attempted. A problematic behaviour may have benefit in stopping something invalidating, but if repeated it may become a habit needed for psychological functioning. As part of the second research aim a behaviour change strategy was developed and piloted to try and bring the individual closer to their construct of the ideal self. Instructions were provided for the individual to experiment with that differed from their disposition. The programmes had varied degrees of success depending on the participant. The implications for personality research and behaviour change are discussed