Protected: Transient spiral arms from far out of equilibrium gravitational evolution: Supplement Material

This content is password protected. To view it please enter your password below:

Read the rest

Rules and Exceptions in Language Dynamics

In all languages, rules have exceptions in the form of irregularities. Since rules make a language efficient, the persistence of irregularity is an anomaly. How language systems become rule governed, how and why they sustain exceptions to rules? Frequent words … Read the rest

Mixing by degree in signed social networks

Social networks have empirically been found to be assortative (i.e., the degree of neighboring nodes are positively correlated), while other networks (e.g., technological, biological) show the opposite pattern (disassortative). Why is that so?
How do these patterns change in signed … Read the rest

Fractures and crack propagation

The intermittent and self-similar fluctuations displayed by a slow crack during the propagation in a heterogeneous medium can be quantitatively described by an extension of a classical statistical model for fracture. The model yields the correct dynamical and morphological scaling, … Read the rest

Synchronization of extended systems

Synchronization is a long known phenomenon dating back to Huygens experiments who observed that suspending two pendula “…in the same wooden beam, the motions of each pendulum in opposite swings were so much in agreement that they never receded Read the rest

Statistical physics modeling of social dynamics

In recent years it has become widely recognized that many large-scale phenomena observed in social systems are the “macroscopic” complex effect of the “microscopic” simple behavior of a large number of interacting agents. This has led social scientists to the … Read the rest

Regularities and universality in large-scale social phenomena

In social phenomena every individual interacts with a limited number of peers, usually negligible as compared with the total number of people in the system. In spite of that, human societies are characterized by stunning global regularities. There are transitions … Read the rest

Fractal analysis of planetary topographies

There exists an overwhelming diversity of landscapes on Earth. A cornerstone of modern geomorphology came with the realization that all the different features of the terrestrial surface result from the accumulated effect of current geological agents [Lyell, 1830]. This principle … Read the rest

GZIP: Galaxy morphology classification by zip algorithm

Even before the identification of galaxies as stellar systems, astronomers have classified them based on their visual appearance. Galaxies in the local universe can organized in a sequence of morphologies (e.g. the Hubble sequence) which must be the result of … Read the rest

Tidal tail characterization

Introduction

A globular cluster (GC) is a spherical collection of stars that orbits a galactic core as a satellite.
Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their … Read the rest

Spatially correlated random walks and turbulence

The wide applicability of the random walks (RW) to natural phenomena relies just on the possibility to introduce appropriate generalizations on the probabilistic nature of displacements. A straightforward generalization is realized by assuming correlations in displacements to obtain the so … Read the rest

Dynamics of self-gravitating systems

A System with long-range interactions is characterized by an inter-particle potential which decays at large distances with a power law exponent which is smaller than the dimension of the embedding space. Classical examples include for instance: self-gravitating systems, unscreened Coulomb … Read the rest

Matter density fields in the early universe

The most prominent feature of the initial conditions of the matter spatial distribution in the early universe, in standard theoretical models, derived from inflationary mechanisms, is that matter density field presents on large scale super-homogeneous features. This means the following. … Read the rest

Total gravitational force and the classification of long range interactions

In equilibrium statistical mechanics the distinction between short and long range interactions is given by the integrability or not of the pair potential. However for what concerns only the clustering dynamics of a particle distribution under the effect of an … Read the rest

Role of microscopic chaos to macroscopic transport

The discovery that simple deterministic nonlinear systems could display dynamical evolution characterized by a randomness similar to stochastic processes changed very much researchers’ attitude toward determinism and predictability of natural phenomena. Determinstic chaos has been successfully invoked to interpret several … Read the rest

Disorder driven non-equilibrium phase transition: the Random field Ising model

In hard magnetic materials, the domain walls movement or even creation is suppressed, and other mechanisms, like domains nucleation and coherent spin rotation enter in the process of magnetization reversal. For these kind of materials a description in terms of … Read the rest

Systems with multiplicative noise

Problems susceptible to be mathematically represented by stochastic Langevin equations including a multiplicative noise abound not only in physics, but also in biology, ecology, economy, or social sciences. In a broad sense a Langevin equation is said to be multiplicative … Read the rest

Metastable states and supersymmetry

Both the static and the dynamical behaviour occurring in mean field spin glass models models can be interpreted as consequences of the complex (free) energy landscape that spin glasses have, with many minima, valleys and saddles. Traditionally, much attention has … Read the rest

Field theory for finite dimensional spin glasses

Many features predicted by mean field spin glass models, such as the behaviour of susceptibilities and correlation functions or the occurrence of aging and off-equilibrium dynamics, are qualitatively observed in experiments, suggesting that the mean field scenario may hold for … Read the rest

The growth of amorphous order in supercooled liquids

Close to the glass transition supercooled liquids display an impressive increase of the relaxation time, without any clear sign of growing thermodynamic order, nor correlation length. This is at variance with physical intuition, which suggests that a large relaxation time … Read the rest

Crackling noise: the Barkhausen effect

The term “crackling noise” refers to the signal that some disordered systems produce as a response to an external driving field smoothly changing in time. Due to the presence of disorder, crackling signals are extremely irregular, despite the … Read the rest

Dynamic hysteresis in thin and ultra-thin films

The physics of thin and ultra-thin magnetic films has been extensively studied in the recent past, because of its important implications for applications to high frequency devices. Power losses in ferromagnetic materials generally depend on the frequency of the applied … Read the rest

Dynamical Processes on Networks

During the last decade it has become clear that the topology in many systems, ranging from technological to social to biological, is not well described by regular lattices nor by random graphs. Complex networks, characterized by small-world effects, large connectivity … Read the rest

Human Dynamics

Until now, the study of human dynamics has been done only qualitatively. Actually, the present possibility to have quantitative data on the kind and nature of social relationships through social networks is driving a rapid change in the field. Thanks … Read the rest

Random Lasers

In a nutshell, a random laser is the coherent emission from active stochastic resonators.

In a series of articles around 1966, a Russian scientist V. S. Letokhov, of the Lebedev Physics Institute in Dubna considered the generation of light in … Read the rest

Spin Glasses: a brief introduction

Spin Glasses are dilute magnetic alloys where the interactions between spins are randomly ferromagnetic or anti-ferromagnetic, and are considered as paradigmatic examples of frozen disorder. The presence of disorder (the random interactions) induces frustration and a greater difficulty for the … Read the rest

What is Econophysics?

Collective phenomena in economics, social sciences and ecology are very attractive for statistical physicists, especially in view of the empirical abundance of non-trivial fluctuation patterns and statistical regularities — think of returns in financial markets or of allometric scaling in … Read the rest

Scale-free networks

Scale-Free Networks are present in a wide list of phenomena. Examples range from the structure of the Internet and that of the WWW (we shall see in the following that they are different systems) to the interconnections between financial agents … Read the rest

Transport in binary mixtures

When a binary fluid mixture at the critical concentration is cooled from a high temperature to a sufficiently low temperature (below a critical one), the original homogeneous phase becomes unstable and spontaneously evolves into two phases separated by an interface. … Read the rest

Lagrangian Turbulence

Recently, part of the research activity on turbulence has focused on temporal properties of turbulent statistics which are much less known than the equivalent spatial properties, and are expected to bring information on some of the mechanisms responsible for intermittency … Read the rest

Scalar Turbulence

The ability of efficiently mixing transported substances is one of the most distinctive properties of turbulence. For instance, it is turbulence (induced by the spoon) that allows cream to rapidly invade a cup of coffee, indeed if only molecular diffusion … Read the rest

Inertial Particles in Turbulent Flows

We already mentioned that enhanced mixing is probably one of the most distinguishing feature of turbulence. When a turbulent flow is seeded with particulate matter having a finite size and/or density different from that of the carrier fluid, new features … Read the rest

Introduction to Turbulence

What is Turbulence?

Turbulence is like pornography. It is hard to define but if you see it, you recognize it immediately.
– G.K. Vallis (1999)


Turbulence is ubiquitous in nature and encompasses phenomena taking place over an extremely wide range

Read the rest