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Since 2003, when spontaneous activity in cortical slices was first found to follow scale-free statistical distributions in size and duration, increasing experimental evidences and theoretical models have been reported in the literature supporting the emergence of evidence of scale invariance in the cortex. Although strongly debated, such results refer to many different in vitro and in vivo preparations (awake monkeys, anesthetized rats and cats, in vitro slices and dissociated cultures), suggesting that power law distributions and scale free correlations are a very general and robust feature of cortical activity that has been conserved across species as specific substrate for information storage, transmission and processing. Equally important is that the features reminiscent of scale invariance and criticality are observed at scale spanning from the level of interacting arrays of neurons all the way up to correlations across the entire brain. Moreover, the existing relationship between features of structural connectivity and functional critical states remains partly unclear, although investigated with both analyses of experimental data and in silico models. Thus, if we accept that the brain operates near a critical point, little is known about the causes and/or consequences of a loss of criticality and its relation with brain diseases (e.g. epilepsy). The study of how pathogenetical mechanisms are related to the critical/non-critical behavior of neuronal networks would likely provide new insights into the cellular and synaptic determinants of the emergence of critical-like dynamics and structures in neural systems. At the same time, the relation between the impaired behavior and the disruption of criticality would help clarify its role in normal brain function. The main objective of this Research Topic is to investigate the emergence/disruption of the emergent critical-like states in healthy/impaired neural systems and to link these phenomena to the underlying cellular and network features, with specific attention to structural connectivity. In particular, we would like this Research Topic to collect contributions coming from the study of neural systems at different levels of architectural complexity (from in vitro neuronal ensembles up to the human brain imaged by fMRI).

Neurosciences. --- Nervous system. --- Computational models --- in vitro --- in vivo --- network dynamics --- self-organized criticality --- neuronal avalanches --- power law

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The modern understanding of metal plasticity and fracturing began about 100 years ago, with pioneering work; first, on crack-induced fracturing by Griffith and, second, with the invention of dislocation-enhanced crystal plasticity by Taylor, Orowan and Polanyi. The modern counterparts are fracture mechanics, as invented by Irwin, and dislocation mechanics, as initiated in pioneering work by Cottrell. No less important was the breakthrough development of optical characterization of sectioned polycrystalline metal microstructures started by Sorby in the late 19th century and leading eventually to modern optical, x-ray and electron microscopy methods for assessments of crystal fracture surfaces, via fractography, and particularly of x-ray and electron microscopy techniques applied to quantitative characterizations of internal dislocation behaviors. A major current effort is to match computational simulations of metal deformation/fracturing behaviors with experimental measurements made over extended ranges of microstructures and over varying external conditions of stress-state, temperature and loading rate. The relation of such simulations to the development of constitutive equations for a hoped-for predictive description of material deformation/fracturing behaviors is an active topic of research. The present collection of articles provides a broad sampling of research accomplishments on the two subjects.

dislocation mechanics --- yield strength --- grain size --- thermal activation --- strain rate --- impact tests --- brittleness transition --- fracturing --- crack size --- fracture mechanics --- Hall-Petch equation --- Griffith equation --- size effect --- mechanical strength --- pearlitic steels --- suspension bridge cables --- dislocation microstructure --- fractal analysis --- plasticity --- representative volume element --- dislocation structure --- dislocation correlations --- dislocation avalanches --- nanotwin --- nanograin --- Au–Cu alloy --- micro-compression --- Cu-Zr --- ECAP --- deformation --- quasi-stationary --- subgrains --- grains --- coarsening --- Cu–Zr --- ultrafine-grained material --- dynamic recovery --- transient --- load change tests --- Charpy impact test --- GMAW --- additive manufacturing --- secondary cracks --- anisotropy --- linear flow splitting --- crystal plasticity --- DAMASK --- texture --- EBSD --- crack tip dislocations --- TEM --- grain rotation --- fatigue --- dislocation configurations --- residual stress --- indentation --- serration --- temperature --- dislocation --- artificial aging --- solid solution --- loading curvature --- aluminum alloy --- holistic approach --- dislocation group dynamics --- dynamic factor --- dislocation pile-up --- yield stress --- dislocation creep --- fatigue crack growth rate