Author: cxdig

Why we live in hierarchies: a quantitative treatise

This book is concerned with the various aspects of hierarchical collective behaviour which is manifested by most complex systems in nature. From the many of the possible topics, we plan to present a selection of those that we think are useful from the point of shedding light from very different directions onto our quite general subject. Our intention is to both present the essential contributions by the existing approaches as well as go significantly beyond the results obtained by traditional methods by applying a more quantitative approach then the common ones (there are many books on qualitative interpretations). In addition to considering hierarchy in systems made of similar kinds of units, we shall concentrate on problems involving either dominance relations or the process of collective decision-making from various viewpoints.


Why we live in hierarchies: a quantitative treatise
Anna Zafeiris, Tamás Vicsek


Self-Organization and The Origins of Life: The Managed-Metabolism Hypothesis

The managed-metabolism hypothesis suggests that a cooperation barrier must be overcome if self-producing chemical organizations are to transition from non-life to life. This barrier prevents un-managed, self-organizing, autocatalytic networks of molecular species from individuating into complex, cooperative organizations. The barrier arises because molecular species that could otherwise make significant cooperative contributions to the success of an organization will often not be supported within the organization, and because side reactions and other free-riding processes will undermine cooperation. As a result, the barrier seriously limits the possibility space that can be explored by un-managed organizations, impeding individuation, complex functionality and the transition to life. The barrier can be overcome comprehensively by appropriate management which implements a system of evolvable constraints. The constraints support beneficial co-operators and suppress free riders. In this way management can manipulate the chemical processes of an autocatalytic organization, producing novel processes that serve the interests of the organization as a whole and that could not arise and persist spontaneously in an un-managed chemical organization. Management self-organizes because it is able to capture some of the benefits that are produced when its management of an autocatalytic organization promotes beneficial cooperation. Selection therefore favours the emergence of managers that take over and manage chemical organizations so as to overcome the cooperation barrier. The managed-metabolism hypothesis shows that if management is to overcome the cooperation barrier comprehensively, its interventions must be digitally coded. In this way, the hypothesis accounts for the two-tiered structure of all living cells in which a digitally-coded genetic apparatus manages an analogically-informed metabolism.


Self-Organization and The Origins of Life: The Managed-Metabolism Hypothesis
John E. Stewart


Thermodynamics of Evolutionary Games

How cooperation can evolve between players is an unsolved problem of biology. Here we use Hamiltonian dynamics of models of the Ising type to describe populations of cooperating and defecting players to show that the equilibrium fraction of cooperators is given by the expectation value of a thermal observable akin to a magnetization. We apply the formalism to the Public Goods game with three players, and show that a phase transition between cooperation and defection occurs that is equivalent to a transition in one-dimensional Ising crystals with long-range interactions. We also investigate the effect of punishment on cooperation and find that punishment acts like a magnetic field that leads to an “alignment” between players, thus encouraging cooperation. We suggest that a thermal Hamiltonian picture of the evolution of cooperation can generate other insights about the dynamics of evolving groups by mining the rich literature of critical dynamics in low-dimensional spin systems.


Thermodynamics of Evolutionary Games
Christoph Adami, Arend Hintze


The Fall of the Empire: The Americanization of English

As global political preeminence gradually shifted from the United Kingdom to the United States, so did the capacity to culturally influence the rest of the world. In this work, we analyze how the world-wide varieties of written English are evolving. We study both the spatial and temporal variations of vocabulary and spelling of English using a large corpus of geolocated tweets and the Google Books datasets corresponding to books published in the US and the UK. The advantage of our approach is that we can address both standard written language (Google Books) and the more colloquial forms of microblogging messages (Twitter). We find that American English is the dominant form of English outside the UK and that its influence is felt even within the UK borders. Finally, we analyze how this trend has evolved over time and the impact that some cultural events have had in shaping it.


The Fall of the Empire: The Americanization of English
Bruno Gonçalves, Lucía Loureiro-Porto, José J. Ramasco, David Sánchez


To slow, or not to slow? New science in sub-second networks

What happens when you slow down part of an ultrafast network that is operating quicker than the blink of an eye, e.g. electronic exchange network, navigational systems in driverless vehicles, or even neuronal processes in the brain? This question just adopted immediate commercial, legal and political importance following U.S. financial regulators’ decision to allow a new network node to intentionally introduce delays of microseconds. Though similar requests are set to follow, there is still no scientific understanding available to policymakers of the likely system-wide impact of such delays. Giving academic researchers access to (so far prohibitively expensive) microsecond exchange data would help rectify this situation. As a by-product, the lessons learned would deepen understanding of instabilities across myriad other networks, e.g. impact of millisecond delays on brain function and safety of driverless vehicle navigation systems beyond human response times.


To slow, or not to slow? New science in sub-second networks

Neil F. Johnson