3
Maggio
ore 12.0014.00
Aula Consiglio 
Sergio
Barbarossa
Topological Signal Processing
Signals are used in our
everyday life to send and receive information or to
extract information from an unknown environment.
Typically, signals are defined over a metric space, i.e.
time and space. The goal of this talk is to present a
set of tools to analyze signals that are defined over a
topological (e.g., not necessarily metric) space, i.e. a
set of points along with a set of neighbourhood
relations for each point. Motivating
applications span from gene regulatory networks to
social networks, etc. We introduce the Graph Fourier
Transform (GFT), derive an uncertainty principle for
signals defined over graphs and set the basis for a
sampling theory over graphs. We start from signals
defined over graphs and then we move to the most general
case of signals defined over simplicial complexes.
Finally, we illustrate some applications to the recovery
of the electromagnetic field from a subset of
observations, the inference of the brain functional
activity network from electrocorticography (ECoG)
signals collected in an epilepsy study and theprediction
of data traffic over telecommunication networks.

5
Aprile
ore 12.0014.00
Aula Consiglio 
Anton
Bovier
Stochastic individual based models: from scaling
limits to modelling of cancer therapies
Stochastic individual
base models, that is, measure valued Markov processes
describing the evolution of interacting biological
populations, have proven over the last years to be
effective models in deriving key features of the theory
of adaptive dynamics, such as the canonical equation of
adaptive dynamics, the
trait substitution sequence and the polymorphic
evolution sequence. In this talk I review these models
an the diverse emerging scaling limits, and I report on
recent progress in applying such models to the modelling
of cancer therapies, and in particular to immunotherapy
and combination therapies of melanoma, based on
experimental data by colleagues from the Bonn university
hospital.

8
Marzo
ore 12.0014.00
Aula Consiglio 
Antonio
De Simone
Flagellar swimming and amoeboid motion in
Euglena gracilis: the how and why of a behavioral
change in a unicellular organism
Euglena gracilis is a
unicellular protist exhibiting different motility
strategies: swimming by flagellar propulsion, or
crawling thanks to large amplitude shape changes of the
whole body (a behavior known as amoeboid motion, or
metaboly).
Swimming is propelled by the nonplanar beating of a
composite flagellum powered by an axoneme, with
molecular motors sliding over microtubule bundles
(arranged according to the “standard” 9+2 architecture).
The
nonplanar beating of the flagellum leads in turn to
helical trajectories coupled with body rotations, and
these rotations play an important role in the
phototactic behavior of E. gracilis.
Confinement triggers a behavioral change, namely, E.
gracilis switches from flagellar swimming to ameboid
motion, which is propelled by peristaltic waves along
the body of the organism. These are powered by molecular
motors driving the relative sliding of pellicle strips
lying underneath the plasma membrane. The mechanisms
controlling the gait switch in this unicellular organism
are still unknown.
Our most recent findings on the motility of E. gracilis,
which are the result of a combined theoretical and
experimental analysis, will be surveyed.
Image: flagellar shapes and resulting
trajectories of the cell body (green) and eyespot
(red) of Euglena gracilis

22
Febbraio
ore 12.0014.00
Aula Consiglio 
Karl
Sigmund
Social learning leads to the recurrence of
corruption
Cooperation can be
sustained by institutions that punish freeriders. Such
institutions, however, tend to be subverted by
corruption if they are not closely watched. Monitoring
can uphold a regime of honesty and cooperation, but
usually comes at a price. The temptation to skip
monitoring regularly leads to outbreaks of corruption
and the breakdown of cooperation. We model the
corresponding cycle by means of evolutionary game
theory, using analytical methods and numerical
simulations. The results confirm the view that
transparency is a major factor in fighting corruption.

18
Gennaio
ore 12.0014.00
Aula Consiglio 
Andrea
Puglisi
Granular Brownian Motion
Granular materials are
made of macroscopic particles, called grains: sand,
rice, sugar and powders are typical examples. They are
important in our everyday life, in many industrial
applications and in the prevention of geophysical
hazards. In
physics, mainly in the realm of nonequilibrium
statistical mechanics, granular systems are an inspiring
source of phenomena and questions. The simplest model of
granular material is a "fluid" made of inelastic hard
spheres. For such a system  in the dilute limit  the
classical program of kinetic theory (Boltzmann equation,
ChapmanEnskogbased hydrodynamics, and much more) has
been developed by physicists and mathematicians in the
last decades. In this seminar, after recalling a few key
results of such a theoretical activity, I will focus on
a series of experiments made in my laboratory in the
last 5 years. They concern the statistical properties of
a massive probe immersed in a steady state granular
fluid. The fluid is obtained by vibrofluidization of a
large number of hard spheres of different materials,
while the probe is a rigid rotator whose angular
displacement and angular velocity are the key
observables. In the dilute limit one conjectures a
Markovian approximation for the rotator's dynamics which
explains many aspects of the experiment, including a
qualitative understanding of "motor effects" in the
presence of rotator's asymmetries. Further noticeable
facts appear when the granular fluid is not dilute,
mainly the violation of the mobilitydiffusivity
Einstein relation, and anomalous diffusion. For these
phenomena a predictive theory is lacking and only
phenomenological models are available.

