Research
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Neuronal
impulses, cardiac activity, circadian rhythms, bacterial colonies, intricate
patterns in nature, spiral galaxies, vortices in fluids, food chain in
ecological systems, financial markets and business cycles, weather forecasting
and reaction-diffusion systems, all have something in common. They belong to
a wide class of nonlinear systems. Nonlinearity in the realm of dynamics has
far-reaching significance in various processes occurring in the real world.
Starting from the fields of chemistry, physics and biology, its roots extend
into astronomy, engineering, ecology, economics and medicine. Research Motivation : Ventricular
fibrilation and other not-completely-understood and
abnormal cardiac activities has been a field of intensive research in the
present century. Knowing the seriousness of these phenomenon and the unfathomableness and lack of external control of their
characteristics and mechanism in the living creature, makes it imperative for
us to find some other systems that show similar properties, but are far
easier to handle. It has been realized that the heart is an excitable medium,
that is, it has the ability to propagate signals through it without damping.
Luckily for scientists, reaction diffusion systems are also another class of
excitable media. It was found by researchers that these systems show similar
spontaneous formation of wave-forms and vortices and response to external
stimuli. We use these reaction-diffusion systems as laboratory models to
generate and study the dynamics and control of various phenomena occurring in
the more complex biological world. Theoretical analysis of the results and
observations also reveal astonishing resemblance to problems in mathematics,
physics and engineering. Research
activities at IIT Guwahati Our
current focus is the study of spiral waves and their three dimensional
counterpart, scroll waves. In the heart, it is found that their occurrence
leads to the rapid, unsynchronized contraction of the ventricles which
thereby reduces the heart’s ability to pump blood. This is expressed in the
form of medical conditions such as arrhythmia and fibrillation, which may be
fatal to cardiac health. So the understanding and control of these wave forms
is of utmost importance. We use the Belousov Zhabotinsky reaction, to study the spiral and scroll
waves and try to control them using external field gradients. Some of our
recent experimental findings are listed below.
Unpinning of Scroll Waves Under the Influence of
Thermal Gradient Scroll
waves can attach themselves to unexcitable obstacles and this sometimes
highly elongates their life span. Hence the unpinning and annihilation of
these vortices has attracted much attention over the past decades. In this
work we study the influence of a thermal gradient on scroll waves pinned to
inert obstacles, in the Belousov-Zhabotinsky
reaction. Under a temperature gradient, scroll rings were seen to unpin from
these obstacles, thus strikingly reducing their lifetimes. These results were
also reproduced by numerical simulations using the Barkley model. N. P. Das, D. Mahanta and S. Dutta, Phys. Rev. E, 90, 022916 (2014 Previous
Research Understanding excitable media: Experiment and
theory
Physico-chemical instabilities
in spatially extended systems : Effect of external fields
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