Biophysics

Many recent discoveries in biological sciences have been made at the interface of physics and biology. This is not surprising, since behind many biological processes lie physical phenomena. Moreover, theories and methods of physical sciences allow one to create new effective tools for the study of biological systems. Examples are NMR scanners, X-ray devices, electron microscopes, ultrasound and laser techniques and many others. Our research is focussed on the modelling of biological processes and on the development of methods for their control. The research areas include cardiovascular dynamics, neural networks, drug delivery physics, population dynamics and psychoacoustics. Some illustrations of our research are given below.

Physics of embolic stroke: Computational forecast of arterial blockages in a virtual patient has the potential to provide the next generation with advanced clinical monitoring aid for stroke prevention. As a first step towards a physiologically realistic virtual patient, we are creating a computer model that investigates the effect of emboli (particles or gas bubbles) as they become lodged in the brain.

Cardiovascular rhythmic activity: The cardiovascular system is known to be able to demonstrate a variety of rhythmic activities associated with heart beat, respiration, oscillatory processes in blood vessels, etc. In our research we use the methods of nonlinear dynamics to model and to study oscillations in the cardiovascular system. Part of our research is devoted to the development of the techniques for non-invasive control of cardiovascular rhythmic activity. Illustrations of some of our experiments can be found here and here.

Physics of pulmonary drug delivery: Our interest in pulmonary drug delivery is evoked by the recent emergence of inhaled systemic drugs and by the global concern over the sharp rise in respiratory conditions such as asthma and chronic obstructive pulmonary disease. Using physical approaches we try to develop new effective methods for the measurement of drug inhaler performance. We participated in the creation of the VariDose (c) system, which enables pharmaceutical companies to quickly and efficiently test a wide range of drug-device combinations. Data from the VariDose technology can assist with improved use of metered dose inhalers and spacers, and should influence future designs of such devices for improved dose control. See poster for more detail.

Neuron networks: Traditionally neuron networks are associated with the functioning of the nervous system: that is, a large network within which a large number of single cells (neurons) work in a cooperative manner. Today the term “neuron networks” often refers to artificial neurons that mimic the properties of biological neurons. Artificial neuron networks can be used either for understanding of biological neural networks, or for solving artificial intelligence problems without creating a model of a real biological system. One aspect of our research is to study these collective phenomena using a variety of physical methods. Particularly we are interested in cooperative dynamics of neurons and in related phenomena like synchronization, clustering, dynamical complexity, transfer of information, and also in the development of methods to control the above phenomena. Some very simple models of single neurons are illustrated here and here.

One of the main problems that make the analysis of neuron networks extremely difficult is the huge complexity of couplings between single elements. In our research we are developing new theoretical approaches that will apply the mathematical apparatus of modern theoretical physics to computationally difficult problems in neural networks.

Population dynamics: Interaction of populations of different species in an isolated ecosystem can lead to complex dynamics, which is characterized by oscillations of the populations' sizes. The picture becomes even more complex when different ecosystems are connected with each other. We study the collective effects which appear in such systems, and are trying to reveal the common phenomena that characterize the dynamics of interacting populations.

The picture to the left illustrates interaction between the T4-phages (viruses) and bacteria.

Psychoacoustics: For some years research has been carried out in the department into the acoustics of percussion instruments and in particular bells and gongs. These are unusual in that the modes are, in general, inharmonic yet campanologists attribute a specific note to a bell when it is sounded sometimes even if it is an untuned bell. The source of this characteristic ‘strike note’ has been a subject of speculation for over 100 years. Its origin is believed to be due to a psychoacoustic effect but it is still not clear what the exact processes producing the ‘strike note’ are. Work in this area is continuing.