Speaker
Esteban Moro

Description We investigate the temporal patterns of human communication and its influence on the spreading of information in social networks. The analysis of mobile phone calls of 20 million people in one country shows that human communication is bursty and happens in group conversations. These features have opposite effects in information reach: while bursts hinder propagation at large scales, conversations favor local rapid cascades. To explain these phenomena we define the dynamical strength of social ties, a quantity that encompasses both the topological and temporal patterns of human communication. We also investigate how this dynamical strength correlates with the social structure.

Speaker
Lucia Marucci

Description The functioning and development of living organisms is controlled on the molecular level by networks of genes, proteins, small molecules, and by their mutual interactions. Prediction, control, and understanding of these systems, named gene regulatory networks, arise mainly from modelling them using iterated computer simulations and non-linear mathematical analysis. Biotechnological advances in quantitative high-throughput technology, in combination with the growing inter-disciplinarity between biology with engineering and natural sciences, have made this challenge achievable thanks to the emerging fields of Systems and Synthetic biology. In the seminar we will first present an introduction to the mentioned disciplines, and to the mathematical tools commonly used. Secondly, we will provide, as example, results about the mathematical modelling and non-linear analysis of IRMA, a novel synthetic network built in the yeast for benchmarking different computational methods. It is composed of five genes and includes one positive and two negative feedback loops; it can be switched “on” or “off”. The derived mathematical model consists of five non-linear Delay Differential Equations that describe production rates of the five mRNAs concentrations. The time delay is fixed and the 33 unknown parameters were estimated from time-series data. The model was further used to understand if and how IRMA can be turned into a biochemical oscillator. This study was carried on via simulations and numerical continuation on one and two parameters using DDE-BIFTOOL. We found that changing the values of at least 4 parameters from the estimated values gives rise to sustained oscillation, with physically feasible period and amplitude. We found that at least two mechanisms cause the occurrence of Hopf bifurcation: multistep processing of gene products in the negative feedback loop and strong cooperativity in gene regulation. Using the mentioned software we analyzed the robustness of the oscillations to parameters changes and varying initial conditions.

Speaker
Yuri Braiman

Speaker
Álvaro Corral

Speaker
Blanca Rodriguez

Description In 1960, Denis Noble published the first mathematical model of a cardiac cell action potential based on the Hodgkin-Huxley formulation. Since then, computational cardiac electrophysiology has developed into a mature discipline in which advanced computational, mathematical and engineering techniques are used to investigate heart rhythm mechanisms in health and disease. A large body of research in computational cardiac electrophysiology has aimed at investigating the mechanisms of cardiac arrhythmias. The main reason for this is the huge burden cardiac arrhythmias impose to society, as they can often result in sudden cardiac death. In fact, sudden cardiac death subsequent to lethal ventricular arrhythmias is the leading cause of mortality in industrialised societies. In this presentation, we will describe the state-of-the-art in multiscale modelling and simulation of ventricular electrophysiology, and we will illustrate their use in the investigation of drug-induced abnormalities in heart rhythm mechanisms. The ultimate goal of the research described here is to contribute to the improvement of the diagnosis and treatment of cardiac arrhythmias to reduce the burden they impose to society.