323,148 research outputs found
Replication codes for: "Epidemiology models explain rumour spreading during France’s Great Fear of 1789" by S. Zapperi et al.
No full textCodes to reproduce the analysis and the figures for the paper "Epidemiology models explain rumour spreading during France’s Great Fear of 1789" by S. Zapperi et al.
Intstructions: The codes are included in three jupyther notebooks running python3.9. Dowload the code and load it within jupyter together with the data
Phase transitions in cell migration
No full textCaterina La Porta and Stefano Zapperi discuss how a suitable identification of the control and order parameters can shed light on the nature of phase transitions in cell migration.
Phase transitions from a static to a moving phase are observed in a variety of physical systems and are thought to play a key role in cellular assemblies such as healthy and cancerous tissue. Caterina La Porta and Stefano Zapperi discuss how a suitable identification of the control and order parameters can shed light on the nature of phase transitions in cell migration
Crackling Noise : Statistical Physics of Avalanche Phenomena
No full textThe response of materials and the functioning of devices is often associated with noise. In this book, Stefano Zapperi concentrates on a particular type of noise, known as crackling noise, which is characterized by an intermittent series of broadly distributed pulses. While representing a nuisance in many practical applications, crackling noise can also tell us something useful about the microscopic processes ruling the materials behavior. Each crackle in the noise series usually corresponds to a localized impulsive event, an avalanche, occurring inside the material. A distinct statistical feature of crackling noise, and of the underlying avalanche behavior, is the presence of scaling, observed as power-law distributed noise pulses, long-range correlation, and scale free spectra. These are the hallmarks of critical phenomena and phase transitions.
This work summarizes the current understanding of crackling noise, reviewing research undertaken in the past 30 years, from the early and influential ideas on self-organized criticality in sandpile models, to more modern studies on disordered systems. Crackling Noise covers the main theoretical models used to investigate avalanche phenomena, describes the statistical tools needed to analyze crackling noise, and provides a detailed discussion of a set of relevant examples of crackling noise in materials science. These include acoustic emission in fracture, strain bursts in amorphous and crystal plasticity, granular avalanches, magnetic noise in ferromagnets and superconductors, and fluid flow in porous media. The book concludes by considering the wider application of these models in the natural sciences
Estimating the Binding of Sars-CoV-2 Peptides to HLA Class I in Human Subpopulations Using Artificial Neural Networks
No full textEpidemiological studies show that SARS-CoV-2 infection leads to severe symptoms only in a fraction of patients, but the determinants of individual susceptibility to the virus are still unknown. The major histocompatibility complex (MHC) class I exposes viral peptides in all nucleated cells and is involved in the susceptibility to many human diseases. Here, we use artificial neural networks to analyze the binding of SARS-CoV-2 peptides with polymorphic human MHC class I molecules. In this way, we identify two sets of haplotypes present in specific human populations: the first displays weak binding with SARS-CoV-2 peptides, while the second shows strong binding and T cell propensity. Our work offers a useful support to identify the individual susceptibility to COVID-19 and illustrates a mechanism underlying variations in the immune response to SARS-CoV-2. A record of this paper's transparent peer review process is included in the Supplemental Information. © 2020 Elsevier Inc.
The response to SARS-CoV-2 infection differs from person to person, with some patients developing more severe symptoms than others. In this paper, Caterina La Porta and Stefano Zapperi show that the immune recognition of SARS-CoV-2 viral peptides differs widely among individuals and could thus explain why they may respond differently to the virus
Loss separation for dynamic hysteresis in ferromagnetic thin films
No full textWe develop a theory for dynamic hysteresis in ferromagnetic thin films, on the basis of the phenomenological principle of loss separation. We observe that, remarkably, the theory of loss separation, originally derived for bulk metallic materials, is applicable to disordered magnetic systems under fairly general conditions regardless of the particular damping mechanism. We confirm our theory both by numerical simulations of a driven random-field Ising model, and by reexamining several experimental data reported in the literature on dynamic hysteresis in thin films. All the experiments examined and the simulations find a natural interpretation in terms of loss separation. The power losses' dependence on the driving field rate predicted by our theory fits satisfactorily all the data in the entire frequency range, thus reconciling the apparent lack of universality observed in different materials
Current challenges for statistical physics in fracture and plasticity
No full textStatistical physics has been applied in the last decades to several problems in mechanics, including fracture and plasticity. Concept drawn from percolation, fractal geometry, phase-transitions, and interface depinning have been used with varying degrees of success to understand these problems. In this colloquium, I describe recent successes and current challenging problems for statistical physics in fracture and plasticity, focusing on the roughness of cracks, fracture size effects and micron-scale plasticity
Avalanche localization and crossover scaling in amorphous plasticity
No full textWe perform large-scale simulations of a two-dimensional lattice model for amorphous plasticity with random local yield stresses and long-range quadrupolar elastic interactions. We show that as the external stress increases towards the yielding phase transition, the scaling behavior of the avalanches crosses over from mean-field theory to a different universality class. This behavior is associated with strain localization, which significantly depends on the short-range properties of the interaction kernel
Looking at How Things Slip
No full textNew measurement techniques are overturning some long-held assumptions related to the microscopic processes controlling friction
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