Upcoming Seminars on Thursday, 11 June

[Quantitative Life Sciences]

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UPCOMING SEMINARS - Spring College on the Physics of Complex Systems
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THURSDAY, 11 JUNE
GIAMBIAGI Lecture Hall - ICTP Adriatico Guest House

14:30 - 15:10: Valentina Ros (SISSA PhD student)

Title:
Many body localization and integrals of motion

Abstract:
Interacting quantum systems in a disordered environment can be in a
many-body localized phase, in which transport is suppressed and memory
of the initial condition is retained in local observables for
arbitrarily long times. In this talk I will introduce the notion of
localization for disordered quantum systems, and discuss how it
implies ergodicity breaking and absence of thermalization. I will then
shortly discuss the existence of conserved quasi-local quantities for
many-body localized systems, and comment on the explicit construction
of these quantities for a particular model of interacting fermions on
the lattice.


15:10 - 15:50: Edoardo Sarti (SISSA PhD student)
Title:
Statistical scoring functions for protein folding and docking pose recognition

Abstract:
Although it is widely accepted that the tridimensional structure - and
thus, function - of a protein depends only on its amino acid sequence,
the issue of finding a correspondence between a particular sequence
and its stable conformation is still far from being solved.
A key role in investigating this problem is played by statistical
potentials. In particular, scoring functions constitute a wide class
of algorithms whose aim is to assess the quality of some collection of
objects. In this context, they are employed to evaluate the stability
of a number of different putative conformations (poses) of a protein
whose stable (native) state is unknown.
First, the theoretical foundations of the subject will be delineated,
then an example will be given by introducing BACH, a knowledge-based,
statistical scoring function to assess the quality of both folding and
docking poses.


15:50 - 16:30: Romain Brasselet (SISSA PostDoc)
Title:
Isometric representation of sensory stimulations by the temporal
structure of neural activity

Abstract:
Sensory neural activity mediates all perceptions and must thus provide
an efficient representation of the environment. In particular, the
firing dynamics of population of neurons has to be such that the
central nervous system can recognize the stimulation that elicited it.
One crucial feature of the code is that it must be unambiguous,
meaning that two different stimulations cannot elicit the same pattern
of activity. Such a feature allows a recognition of the stimulation
provided templates exist. However, given the complexity of the
manifold of stimulations, there is a need for a capacity to recognize
a continuum of stimulations. It still remains unclear how the decoding
task can be carried to the level of an infinite number of possible
contexts. Here, using data from human tactile microneurography, we
show that, if readout in an efficient way, peripheral activity is
unambiguous at the utmost point. We show that properly tuned decoders
can capture some geometrical regularities of the input space encoded
by primary afferent spiking signals. This provides strong evidence
that the neural activity can be endowed with a geometry that mimics
that of the tactile stimulations. We argue here that such a faithful
geometric organisation may be crucial in order to understand human
cognitive abilities such as learning, generalizing and categorizing.
Our results also suggest that while first-spike latencies are enough
to guarantee maximum information transmission of tactile stimuli,
entire primary spike trains constitute a necessary condition to encode
isometric input-output mappings, a likely basis for generalization in
sensory coding. Thus, spikes gradually shape the representation of the
stimulation until a faithful one is attained


Erica Sarnataro
Secretariat
Spring College on the Physics of Complex Systems (smr2704)
ICTP
Strada Costiera, 11
34151 Trieste
Italy

Tel: 00 39 040 2240623
http://indico.ictp.it/event/a14244