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Keyword: biology

Interactive Lotka-Volterra model

1 pav. Lotka-Volterra lygčių sistemos sprendinys. Parametrai: a1=20, a2=30, c12=c21=1.

Previously on Physics of Risk we have wrote about Lotka-Volterra equations. At that time we didn’t provide an interactive applet with the text. Only recently we have updated the text and provided an interactive Wolfram CDF applet. This applet was replaced by HTML5 app, yet it is still available for download.

We encourage you to try it!

On the stochastic theory of nonequilibrium steady states

ruseckas

In October 2012 our group has familiarized themselves with this interesting theory. Few seminars, which were held at VU ITPA, on the stochastic theory of nonequilibrium steady states were read by dr. Julius Ruseckas, one the researchers in our group. This theory is discussed in two articles recently published in the Physical Reports journal 1, 2. Read on Continue reading “On the stochastic theory of nonequilibrium steady states” »

Seminar at VU Faculty of Physics: Brief introduction into the Physics of Risk

kononovicius

Topic: “Physics is not a risk: Brief introduction into the Physics of Risk”
Speaker: Aleksejus Kononovičius
Briefly: Social sciences have accomplished many different things. Yet it should be evident that there is a place for improvements – to look into the old and new social problems a bit differently. As many of the social problems are strongly non-linear and very complex, the physicists’ point of view is very useful. This, new, point of view is known as Physics of Risk.
When? 18th of October, 17:00.
Where? VU Faculty of Physics (Saulėtekio al. 9, III rūmai, Vilnius), 201 auditorium.
Organized by: VU Faculty of Physics Students Scientific Association.
Facebook event: here.

Slides: download (in Lithuanian).

Agent based prey-predator model

lv-agent

The simplest ecological system can be constructed from the two interacting species, ex. prey and predator. This kind of system is very interesting in the terms of Physics of Risk primarily because it is nonlinear 1, and due to being real life example of competition (conflict). Also there are few known simple models for the prey-predator interaction. Among them there are both macroscopic, Lotka-Volterra equations, and microscopic, agent-based, models. In this text we continue the previous discussion by considering the agent-based model. Continue reading “Agent based prey-predator model” »

Lotka-Volterra equations

1 pav. Lotka-Volterra lygčių sistemos sprendinys. Parametrai: a1=20, a2=30, c12=c21=1.

The simplest ecological system can be constructed from the two interacting species, ex. prey and predator. This kind of system is very interesting in the terms of Physics of Risk primarily because it is nonlinear 1, and due to being real life example of competition (conflict). Also there are few known simple models for the prey-predator interaction. Among them there are both macroscopic, Lotka-Volterra equations, and microscopic, agent-based, models. We will start our discussion from the macroscopic Lotka-Volterra model. Continue reading “Lotka-Volterra equations” »

Experimental biology on social inequality

“Chicago University” school economists claim that unemployment is purely voluntary. But what does a capuchin monkey think about it? Continue reading “Experimental biology on social inequality” »

Fractals in pork!

ham

Previously (ex. while speaking about the multifractality of time series) we have already discussed that fractals are observed in many daily phenomena. Interestingly enough we can eat fractals for our breakfast! Recently we have found an article 1 which studies fractal structures, 1/f-like noise in ham! Continue reading “Fractals in pork!” »

Stochastic ant colony model

ants_stochastic

Previously on Physics of Risk website we have presented Kirman’s ant colony agent based model 1, where each ant was represented as an agent. In this article we will move from the agent based model framework to the stochastic differential equation framework. Thus showing that in case of simple agent based models full transition to stochastic framework is possible. This transition is very important as stochastic framework is very popular and well developed in quantitative finance. The problem is that stochastic framework mainly gives only a macroscopic insight into the modeled system, while microscopic behavior currently is also of big interest.
Continue reading “Stochastic ant colony model” »

Kirman’s ant colony model

[:lt]Iš openclipart.org (autorius F.Rollandin)[:en]From openclipart.org (author F.Rollandin)

There is an interesting phenomenon concerning behavior of ant colony. It appears that if there are two identical food sources nearby, ants exploit only one of them at a given time. The interesting thing is that used food source is not certain at any point of time. At some times switch between food sources occur though the quality of food sources remains the same. In 1993 Alan Kirman proposed that this could happen due to importance of herding behavior in ant colonies 1. Continue reading “Kirman’s ant colony model” »