Macroscopic systems are often endowed with a large number of different scales and features. While controlling one single system often demands to properly describe all its complexity, different systems can express similar behaviours which are scale-invariant and depend on a minimal set of parameters.
The last two features allow to reproduce these phenomena at the laboratory scale and describe them with a minimal analytical model, thus characterising the observed phenomena in a very general way.
 
Following this approach I focus on the stability of different macroscopic systems, from the human scale (suitcases and bikes), to the geophysical (vortices and currents in the ocean) and astrophysical scales (accretion disks).
I show that in all these systems the macroscopic behaviour relies on
the balance or inbalance between few parameters.
Also, depending on the relative importance of these parameters, these systems can show the appearing of longevous and well organised patterns.
 
Finally I introduce a new project which focuses on the complex structure of the arboreal nests built by Nasute termites. I aim to characterise these objects using the same minimal approach than before while facing the additional biological aspects. I will try to answer three connected questions: what are the biological functions of the macroscopic structure, how it is built by many simply interacting agents, and at which extent these two elements are related to the form of the nest.