Next week - 3 Quantitative Life Sciences guest seminars

[Quantitative Life Sciences]

*_3 Quantitative Life Sciences Guest Semina__rs:_

*Monday 15 May at 14:30
ICTP, Central Area, 2nd floor, old SISSA building, Via Beirut

Title: " Bacterial finite-size effects for population expansion under flow"

Speaker: Federico Toschi, Technische Universiteit Eindhoven, The Netherlands

Abstract:
For organisms living in a liquid ecosystem, flow and flow gradients have 
a dual role as they transport nutrient while, at the same time, 
dispersing the individuals. In absence of flow and under homogeneous 
conditions, the growth of a population towards an empty region is 
usually described by a reaction-diffusion equation. The effect of fluid 
flow is not yet well understood and the interplay between transport of 
individuals and growth opens a wide scenario of possible behaviors. In 
this work, we study experimentally the dynamics of non-motile E. coli 
bacteria colonies spreading inside rectangular channels, in PDMS 
microfluidic devices. By use of a fluorescent microscope we analyze the 
dynamics of the population density subjected to different co- and 
counter-flow conditions and shear rates. A simple model incorporating 
growth, dispersion and drift of finite size beads is able to explain the 
experimental findings. This indicates that models based on the 
Fisher-Kolmogorov-Petrovsky-Piscounov equation (FKPP) may have to be 
supplemented with bacterial finite-size effects in order to be able to 
accurately reproduce experimental results for population spatial growth.

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A*PPLIED PHYSICS-QUANTITATIVE LIFE SCIENCES SPECIAL SEMINAR*
Tuesday 16 May at 11:00
ICTP, Central Area, 2nd floor, old SISSA building, Via Beirut

Title: "Digital Epidemiology: Challenges in Data Collection in 
Developing Countries"

Speaker: Eiko Yoneki, University of Cambridge

Abstract:
Respiratory and other close-contact infectious diseases, such as TB, 
measles and pneumonia, are major killers in much of the developing 
world. Understanding how the diseases spread and for identifying how 
best to control it can be tackled by modelling the spread diseases. 
Although central to the models, few quantitative data are available on 
relevant contact patterns, and no study to measure these factors has yet 
been attempted in developing countries.
We have originally exploited device connectivity traces from the real 
world for modelling social network structure. The initial motivation was 
providing delay tolerant networks among smart phones formed by people. 
The empirical study of contact networks shares many issues with 
network-based epidemiology, and our work has been extended towards 
understanding the epidemic spread of infectious diseases. Capturing 
human interactions will provide an empirical, quantitative measurement 
of social mixing patterns to underpin mathematical models of the spread 
of close-contact diseases.
I will describe remote sensing platform to collect human mobility data 
using RFID sensors, Raspberry Pis and mobile phones, recording 
proximity, to gather information on human interactions in rural and 
urban communities in developing countries.
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Wednesday 17 May at 15:00
ICTP, Central Area, 2nd floor, old SISSA building, Via Beirut

Title: "Extracting information from simple statistical laws in complex 
component systems"

Speaker: Andrea Mazzolini, University of Turin

Abstract:
Several complex systems in various fields 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. These laws may be the 
consequence of  the underlying architectural constrains, thus in 
principle can provide information about the system properties.
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 presentation I will focus on two specific examples. The first 
example concerns the "U"-shaped distribution of  shared genes across 
genomes, which is central to the current debate in evolutionary 
genomics. We show that its characteristic shape can be obtained by a 
null model simply based on the empirical heterogeneity of the component 
abundances. This implies that the distribution of shared genes is mainly 
a statistical consequence of other known system properties. This result 
shows that to extract the relevant biological information it is 
necessary to build null models. In this way it is possible to take into 
account general emerging features and thus extract the systems specific 
properties.
The second example considers the growth of the book/object "vocabulary" 
(i.e. how many distinct words/components are present) as a function of 
its "size" (i.e. the total number of components),  a law known in 
linguistics as  Heaps’ law. We focused on how the vocabulary 
fluctuations scale with its average value, showing a non-trivial and 
general behavior across different systems. Specifically, the standard 
deviation grows linearly with the average (Taylor’s law). We have found 
that the minimal stochastic growth processes that can reproduce this 
scaling belong to a class of models that includes  the Chinese 
Restaurant process. This suggests a general rich-gets-richer mechanism 
in the innovation dynamics of thus component systems, leading to 
interesting system-specific interpretations.


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
e-mail:qls at ictp.it