Enzo Nicosia 26th Nov 2014

On Wednesday 26th November, Enzo Nicosia, from the School of Mathematical Sciences at Queen Mary University will give the talk

Phase transitions in network growth: from street patterns to neural networks

Mountbatten Room 4025A (53/4025A), Highfield Campus, 4pm. All welcome. Refreshments served after the talk.

Abstract: Studying how a system has evolved over time can help unraveling the elementary mechanisms responsible of its formation and understanding the complexity of the wiring patterns connecting its constituent units. We have recently found that the evolution of spatially-embedded systems, such as urban street patterns and neural networks, can be characterised by interesting phase transitions, resulting in abrupt changes of some structural descriptor of the system. In this talk we will discuss two examples of phase transition in the growth of a network, respectively corresponding to the evolution over 200 years of a large metropolitan area in Italy and to the growth of the C.elegans nematode’s neural systems, and we will present reasonable models able to accurately reproduce the observed transitions.

Mervyn Freeman 12th Nov 2014

On Wednesday 12th November, Mervyn Freeman, from the British Antarctic Survey, Cambridge, will give the talk:

Some random walks in space weather

Please note this is being held at an earlier time (2pm)

Mountbatten Room 4025A (53/4025A), Highfield Campus, 2pm. All welcome. Refreshments served after the talk.

Abstract: Space weather – the natural variability of near-Earth space – is a hazard to modern society, with the potential to affect satellite services and electricity supply. It is the fourth highest natural hazard risk on the Government’s National Risk Register, alongside heatwaves and low temperatures. Arguably the greatest source of uncertainty is the substorm – an earthquake-like disruption of near-Earth space that eludes deterministic prediction. In this talk, I will show how substorm occurrence may be understood as a random walk towards an absorbing barrier, similar to the Gerstein-Mandelbrot model of neuron firing in the brain. I will discuss the limits of prediction and similarities to the space weather of Jupiter and Saturn.

Alex Kalloniatis 5th Nov 2014

On Wednesday 5th October, Alex Kalloniatis, from Defence Science and Technology Organisation, Canberra, Australia, will give the talk:

Networks and synchronisation: mathematical modelling of socio-technical decision making systems

Life Sciences Building (85), room 2207, Highfield Campus, 4pm. All welcome. Refreshments served after the talk.

Abstract: Much of the decision making in structured organisations such as military, business and administrative units is distributed across many individuals, each contributing information that spans the spectrum from simple ‘facts’ about who and what is ‘out there’, to an integrated understanding of what is happening and why, and what will happen in the future – so that future actions can be determined. They also involve a variety of technological systems and displays to facilitate such Situation Awareness and Sense-Making. Such decision making systems may be represented as networks, and the process of making decisions may be represented as the evolution of individual and collective states in time. In this talk I will present my own efforts at encoding such a model in terms of a system of differential equations based on the well known system of synchronising oscillators, the Kuramoto model. I present two adaptations of this model. The first represents two adversary organisations engaging in a competitive process, each seeking to outpace the speed of decision making of the other. The second focuses on a single organisation but structured in the manner of a typical Divisional construct with separate branches performing different organisational functions, operating under different time pressures and cycles. In both cases, rich seemingly unexpected behaviour arises from numerical solution or simulation – there is ’emergence’ – and dynamical regimes lying between order and chaos. I discuss the value of such models in their tractability to explore, for example, optimal network structures, and the scope for expanding such models to find a balance between Levins’ dimensions of Realism, Precision and Generality.

Doyne Farmer 29th October 2014

On Wednesday 29th October, Doyne Farmer, from the University of Oxford, will give the talk:

A long-term vision for computational economics

Nightingale Building (67) room 1003, Highfield Campus, 4pm. All welcome. Refreshments served after the talk.

Abstract: The ability to simulate phenomena is probably the biggest driver of theoretical progress in physical science during the last 50 years.  The same is not true in economics and social science in general.   Why is this so?  I will argue that the time is ripe for this to happen and present a plan for how it could be done and what breakthroughs are required.  I will review the accomplishments of agent-based models in economics so far, discuss the key theoretical and practical challenges for creating the next generation of models, and present key lessons from the CRISIS project (for which I am scientific coordinator).   I will particularly focus on the need for large scale simulation models, analogous to the global circulation models used in meteorology and climate, and discuss the similarities and differences with meteorology.  Finally I will present a vision of what such large scale models might be like and what they would enable us to do ten or twenty years from now.

Chris Gordon-Smith 24th September 2014

On Wednesday 24th September, Chris Gordon-Smith, from the SimSoup project, will give the talk

“Molecules Designed for Chemical Network Memory and Non-Genetic Inheritance”

Please note the temporary change of venue.

Nuffield Theatre (Building 6) Room 1081 (Nuffield Room B), Highfield Campus, 4pm. All welcome. Refreshments served after the talk.

Abstract:

In this talk I will present a memory system based on an artificial chemistry. This is relevant as a ‘proof of concept’ for metabolism based Origin of Life theories, and in the field of biological and chemical computing. Each memory unit can be switched between three alternative active states. A unit maintains itself in a particular state using an autocatalytic reaction process. Switching between states occurs when an external stimulus triggers the autocatalytic process for the new state, along with an associated process that inhibits autocatalytic activity for the old state. I will show artificial molecular species with structures that support the autocatalytic and inhibiting processes. I will also present results from the SimSoup artificial chemistry simulator showing the operation of a 5-unit memory system with 243 alternative states (equivalent to just under 8 bits of memory). The design supports systems with more units, but computational requirements to run the simulator increase substantially. I will conclude the talk with a short review of some alternative network architectures for chemical memory and inheritance.

Remi Louf 14th May 2014

On Wednesday 14th May, Remi Louf, Institut de Physique Théorique, will give the talk

“How congestion shapes cities: a physicist’s perspective.”

Building 53 Room 4025, Highfield Campus, 4pm. All welcome. Refreshments served after the talk.

Abstract:

In a rapidly urbanising world, understanding the behaviour of cities has broad implications. Indeed, while cities are known to foster creativity and economic growth, they also engender higher crime rates and pollution levels. It is therefore crucial to quantify these effects and understand the underlying processes if we want to design effective policies and make the urban transition as smooth as possible.
Although the recent availability of data has brought fresh insights, most of the observed regularities remain unexplained. For instance, we find that quantities such as the total surface area, the total length of roads, the total daily driven distance scale non-linearly with population size. In this presentation, I will show how simple physical arguments and a bottom-up modelling approach allow us to understand these behaviours. I will discuss how, with simple approaches of this kind, we are able to identify some of the driving forces behind the evolution of urban systems. In particular, I will highlight the role of congestion, and its consequences on life in cities.

Guillaume Achaz 12th March 2014

On Wednesday 12th March, Dr Guillaume Achaz, Atelier de BioInformatique, will give the talk “Epistatic constraints in evolution, theory and practice.”

Building 53 Room 4025, Highfield Campus, 4pm. All welcome. Refreshments served after the talk.

Abstract:

How constrained is life’s evolution? Can mutations occur in any order? What fundamental processes dictate how evolution can proceed? I will discuss some work on experimental and model fitness landscapes that aims at understanding what is the minimum set of rules that are needed to characterize constraints in evolving genetic systems. The work tries to maximize the fit between real biological data and theroretical models. In particular, I will illustrate how both data analysis and model building can feed each other and may utlimately converge. This project aims at taking a step further in our comprehension of the life as it was, is and will be.

James Dyke 26th Feb 2014

On Wednesday 26th February, Dr James Dyke, Institute for Complex Systems Simulation, University of Southampton, will give the talk “Is the Earth alive? A planetary odyssey”

Building 53 Room 4025, Highfield Campus, 4pm. All welcome. Refreshments served after the talk.

Abstract:
“It seems somewhat eccentric if not a little absurd to suggest that a planet is a living thing. Earth has life on it, but it’s not a biological organism. Any theory or argument which concludes that the Earth is alive could be safely filed under “not even wrong”. So when James Lovelock and Lynn Margulis first proposed the Gaia Hypothesis in the early 1970s, some seized on the possible implication that the Earth is a form of biological organism. The Earth is alive? Nonsense! In the decades since, the Gaia Hypothesis has significantly developed and been instrumental in the creation of the new discipline of Earth Systems Science which seeks to understand both the living and non-living components of the Earth in a holistic manner.

In this talk I will give an overview of some of the developments of the mathematical and conceptual theories that underpin Gaia Theory and argue why such approaches are important in a global change context. Humans are currently affecting the Earth via a spectrum of effects. While there is no danger of us destroying the Earth’s biosphere, we are at risk of nudging it into states that would be deleterious to us.”

https://theconversation.com/even-if-earth-changes-life-will-continue-with-or-without-us-15221

Ondrej Hovorka 5th Feb 2014

On Wednesday 5th February, Dr Ondrej Hovorka, Computational Modelling Group, University of Southampton, will give the talk “Spin models of critical phenomena in systems with multi-scale dynamics”

Building 53 Room 4025, Highfield Campus, 4pm. All welcome. Refreshments served after the talk.

Abstract:

This talk will give a general summary of computational models for studying the emergent non-equilibrium phenomena in interacting spin systems spanning a broad range of length- and time-scales. This will include the Langevin dynamics of a set of coupled stochastic ODEs to model thermal fluctuations in spin systems, the master-equation formalism of long timescale memory effects and hysteresis, and the cellular automaton approach to describe multiscale dynamics of avalanche systems, such as earthquakes for example. The individual approaches will be demonstrated using applications in biomedicine, optimisation of modern hard disk drive technologies, and to analysing the out-of-equilibrium phase transition behaviour in avalanching systems.

Mike Harfoot 29th Jan 2014

On Wednesday 29th January, Dr Mike Harfoot, United Nations Environment Program and Microsoft Research Cambridge will give the talk “Attempting to model all life on earth –  a proof of concept General Ecosystem Model”

Building 53 Room 4025, Highfield Campus, 4pm. All welcome. Refreshments served after the talk.

Abstract:

Over the past few years, Microsoft Research and the United Nations Environment Programme World Conservation Monitoring Centre (UNEP-WCMC), both in Cambridge, UK, have built a global ecosystem model for terrestrial and marine ecosystems. Called the Madingley model, it captures the broad-scale structure and function of ecosystems around the world by simulating processes — including feeding, reproduction and death — that drive the distribution and abundance of organisms. From the relationship between the mass of individual organisms and how long they live, or the effects of  human perturbations such as hunting, to the distribution of biomass across Earth, the model’s outputs are broadly consistent with current understanding of ecosystems. Global ecosystem models such as the Madingley model could radically improve understanding of the biosphere and help inform policy decisions about biodiversity and conservation.