2 QLS seminars - Thursday, 22 March 10:30-12:30

[Quantitative Life Sciences]

*2 QLS SEMINARS*

Thursday, 22 March 2018 from 10:30 to 12:30
ICTP, Central Area, 2nd floor, old SISSA building, Via Beirut


Speaker: Andrea Mazzolini, QLS Postdoctoral Fellow

Title: Statistical Laws in Complex Component Systems

Abstract: A wide variety of complex systems can be described as 
component systems, i.e. sets of objects (genomes, books, or LEGO toys) 
composed of elementary components (genes, words, or LEGO bricks). 
Several emerging statistical laws regarding the statistics of components 
can be empirically observed in such diverse systems. Our work tackles 
the general questions of what can be learned from these simple 
statistical laws about what laws are a “universal” property of very 
different component system and what are instead specific of the system 
in analysis, how and if these laws are related to each other, and what 
simple stochastic processes can be used to understand their origins.

In this regard, we focus on the "distribution of shared genes", or 
"occurrence distribution", where the component occurrence is defined as 
the fraction of realizations (genomes) in which the component (gene or 
protein domain family) is present. The origin of its apparently 
universal “U”-shape is central to the current debate in evolutionary 
genomics. By generalizing the law within the component system framework 
and employing a null model based on random sampling of components, we 
show that a U-shaped distribution can be typically expected in every 
system with a broad distribution of component abundances, e.g. Zipf’s 
law, regardless of the nature and the generative dynamics of the system. 
Therefore, the occurrence statistics can be seen as a statistical 
consequence of Zipf’s law, or, in other words, the occurrence 
distribution carries redundant information (i.e. already contained in 
the abundance statistics). The proposed random-sampling model takes into 
account such a “redundancy”, and by looking at the small deviation 
between model and data, one can highlight specific patterns that can be 
used to validate generative models.



Speaker: Anjan Roy, QLS Postdpctoral Fellow

Title: Simulating Genetic Circuits in Bacterial Populations with Growth 
Heterogeneity

Abstract: We present a computational formalism to study gene circuits in 
proliferating bacterial populations. Additionally, we present a
modification to the Gillespie algorithm which makes simulations of such 
large set of clustered reactions more efficient. With these we show that
the statistics of various observables like population fraction, protein 
distributions etc. will depend on the experimental setup being studied.

Everyone interested is most welcome to attend!

-- 
Erica Sarnataro
Group Secretary
Quantitative Life Sciences
The Abdus Salam International Centre for Theoretical Physics (ICTP)
Trieste,  Italy
Tel. +39-040-2240623
www.ictp.it/research/qls.aspx
e-mail: qls at ictp.it