"Networks made life, life makes networks" – Thematic Session (HAS)     18.11.2011

This thematic session chaired by , E. Sylvester Vizi, former President of Hungarian Academy of Sciences. Was dedicated to the various scientific approaches recently developed in network research, the presentations focused on the role and impact that biological, mathematical, computational and communicational networks have on society.

 All neuronal networks contain mutually interconnected excitatory and inhibitory neurons, stated Mr László Acsády analysing neocortical cell types and their connections. Operation critically depends on the balance of excitation. It is problematic even today how to record the activity of naturally interconnected excitatory and inhibitory neurons, the network researcher said adding that an ideal network would consist of spatially segregated excitatory and inhibitory neurons with topographic and reciprocal connections. Its advantage can be tested in the thalamus which is the major gateway of information flow to the neocortex.

Mr Albert-László Barabási of Northeastern University was dealt with the Controllability of complex networks, and how network topology affects its controllability. According to his conclusion a system is controllable if it can be driven from any initial state to any desired final state in finite time. For real networks it is true that driver nodes tend to avoid hubs, denser networks need fewer driver nodes. That is, it is exponentially easier to control the system if it is denser. The more interconnected the network is the fewer driver nodes are needed. Sparse and heterogenerous networks are the hardest to be controlled which is true in most real networks like society - said Barabási.

Mr Tamás Vicsek of Eötvös Lóránd University, Budapest was talking about networks formed by groups of moving entities, the hierarchical organisation or dominance hierarchy within a flock of pigeons for example. They conclude that clustering increases by directional persistence and high directional persistence facilitates cell segregation. Newcomers hardly perturb the original hierarchy which is stable and well preserved.

Networks made life, life makes networks, said Mr Eörs Szathmári referring at the same time to a reflexively autocatalytic process where food, metabolites, housekeeping enzymes, genes, informational enzymes etc. have an impact on each other vice versa. Enzymes are catalyzing the actions.

Mr Kimmo Kaski from Aalto University was examining whether social complexity can be analyzed or modelled dealing with biology, brain-mind and social systems. Complexity is not in numbers but rather about interactions. Communicational systems are linked with diverse interactions, properties of the system's structure, functions, response – that is the paradigm of social life: values, ideas, other cultural resources are channeled through network activities. Tie-strength between two people increases with the overlap of their friendship circles.

Mr Guiodo Caldarelli from Italy (Sapienza, Rome) dealt with economic networks raising the question how networks affect traditional financial agent activity. Analyzing the social network of the investors (the web of property) it becomes clear: if property is diffused bankruptcy is limited to a single company and a few subcompanies. He concluded by saying: “economy is composed by a series of networks. In a complex system even reasonable requests can produce unexpected results”.

 

You can find more details on this session here.