I am a theoretical physicist working
in the general area of Non-equilibrium Statistical Physics and its applications
to some interdisciplinary fields. My interests include
Non-equilibrium phase transitions, Novel correlations in
non-equilibrium steady state , Exactly solvable driven diffusive
systems,
Structure and functionig of Networks. I would like to
pursue future research in the follwing
three important directions :
Novel-correlations
in non-equilibrium steady states:
Classical non-equilibrium systems do
not ensure existence of the state functions like Hamiltonian and
entropy as these systems are known to have non-zero current in the
configutaion space. Thus the steady
states of these systems posses interesting and non-trivial
correlations which are usually absent in
equilibrium. One of my main research interests is to unfold
these novel correlations. Recently we proposed a method,
which can provide an exact steady state and spatial correlations
in a class of non-equilibrium models.
The method has been used successfully in Extended Katz Lebowitz
Spoon (EKLS) model, Restricted Assymetric Exclusion Process (RASEP),
Exclusion process with internal
degrees of freedom, Tonks gas, DNA denaturation transition etc.
Absorbing
state phase transitions beyond DP :
One of the most interesting properties of non-equilibrium
systems is the possibility of phase transition, even in one spatial
dimensions.
Transition from an active phase to an absorbing state is one such
phenomenon which has no counterpart in equilibrium statistical
mechanics. The idea of universality classes, characterised by only a
few critical exponents, extends to the non-equilibrium
transitions too. Generic absorbing state phase transitions
(APT), governed by a fluctuating scalar orderparameter belong
to the Directed percolation (DP) universality class, the
queen of non-equilibrium phase transitions. However, there are
several exceptions.
APT beyond DP is a less understood area of research
and we are trying to understand these sytems by
studying some simple and analytically tractable models. Recently
we have introduced a model, namely RASEP, where hard core particles on
a ring can move to one of the neighbouring vacant sites when the
other neighbour is occupied. This model shows AAPT different from DP at
density r=1/2. The
spatial correlations and the exact critical exponents are obtained
analytically. The orderparameter of the model satisfies the
requirements of DP-conjecture and we are trying to reason why
this class of models shows non-DP behaviour. Are there
perturbations which makes this critical point flow to
DP ?
miRNA
co-target network :
One of the main research activity
which I am going to pursue in future is the microRNA
co-target networks in Biology. microRNAs (miRNA) are small
(about 23 base long) RNAs transcribed
from the DNA. These miRNAs usually downregulate
gene-expression by binding themselves to the UTRs of the
mRNAs which translates into proteins. The diversity of miRNA
targets offer enormous level of combinatorial possibilities by
forming
complex regulatory networks; constructed from the pairwise
co-targets of miRNAs. It turns out that these relevant set of
miRNAs form several small clusters.
We
claim
that
the
miRNA
clusters
are
building blocks of
biological functions as many of these clusters are expressed
maximally in specific tissues. Those miRNAs which are known to
deregulate the genes involved in genetic diseases are also
found to be cluster specific. Our recent study of 20 other
animals
also indicate that the clustering of miRNAs is a universal
feature. Thus, we propose that the genes are better regulated by
co-targeting of clusters of miRNAs, compared to individual regulation.
We are planning some experiments here (SINP) to verify this. We
sincerely believe that these studies will help
biologists in their search for miRNAs that target the genes
involved in any specicific phenotypes. Recently we started
collaborating with U.
Kolthur in TIFR, India on glucose
metabolism. We are also trying to study
(with A. Erzan
and E.
Gungor , ITU,
Istanbul) the the relevant set of miRNAs
involved in Mediterian Fever.
In all these studies the weighted network of miRNA pairs is
created from the number of common targets (genes) they have. One
can construct similar networks from the common disease or the common
Transcription factors and obtain miRNA clusters. It is important
to compare these clusters obtained from different
scenarios. We are planning to built a database of miRNA clusters
at SINP.