Research

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Area of Research: Theoretical Statistical (Bio-)Physics and Mathematical Biology.

Current Research Interest: Stochastic thermodynamics & kinetics of molecular machines, self-organization & emergent collective behavior in states driven far from equilibrium by molecular motors in living cells.

Research Summary:

(a) Non-Technical Summary: Molecular Machines: Reverse Engineering Hardwares and Softwares of Engines of Life

“What is life'' and “how did living matter originate from non-living matter” are among the most hotly debated challenging open questions in science. The question “what sustains life” is no less important. A cell is the structural and functional unit of life; the order of magnitude of its typical linear size can vary between a micro-meter to ten micro-meter. But, contrary to old beliefs, it is not a passive bag of chemicals. Instead, it is like an automated “micro-factory” where coordinated operation of a large number of nano-machines (nano-meter size molecular machines) drive processes that are essential for sustaining life.

A biological machine is a naturally occurring protein molecule or a macromolecular complex that, like its macroscopic counterpart, transforms one form of energy (usually, chemical or electro-chemical) into another. For molecular motors, a special class of machines, the output is mechanical work. Many of the movements, which are hallmarks of life, both at the subcellular as well as cellular level, are driven actively by molecular motors. The study force detection or sensing, response to force and adaptation to mechanical environment, as well as force generation in a cell are of great interest in “molecular biomechanics”.

If a machine can undergo repeated cycling among a set of states it is, for obvious reason, called a cyclic machine. Carnot's engine, that works cyclically, is familiar to all physicists (and engineers); the engine itself remains unchanged at the end of each completed cycle. The engine plays the role of a "broker" or "middleman", and couples an energy-releasing process to an energy-consuming process thereby transforming one form of energy into another. Similar cyclic operations of enzymes is familiar to chemists (and biologists); an enzyme speeds up the conversion of one species of molecule (called substrate) into another (called product) while it itself remains unchanged at the end of each enzymatic cycle. Thus, engines and enzymes have at least one common feature, namely, both facilitate transformation; engine facilitates transformation of energy and enzyme facilitates transformation of matter. Many cyclic molecular machines play dual roles in the sense that these not only transform energy in each cycle but, like an enzyme, also speed up (i.e., catalyze) the transformation of a substrate into one or more products. The machine binds to a specific substrate in a particular transition and thereafter catalyzes its conversion to products that are released in a subsequent transition along the cycle the completion of which also results in transformation of energy. In fact, during each cycle, a reaction catalyzed by a chemo-mechanical machine releases chemical energy part of which is utilized by it in the same cycle for performing its mechanical work output. Not surprisingly, research on molecular machines is of great interest also from the perspective of “single molecule (mechano-)enzymatics”.

For sustaining life, the information encoded chemically in a special class of long chain molecules also need frequent processing. Some of the information-processing machines are, effectively, physical realization of a Turing machine which is an idealized device conceptualized for abstract ‘computation’. Understanding the operational mechanisms of nature’s computing machines is likely to assist computer scientists in their quest for design and implementation of artificial “molecular computating devices”.

Molecular motors do not function in isolation. For example, the collective movement of cargo-transporting motors along a `track’ is similar, at least superficially, to a vehicular traffic in a `smart city’. Similarly, information-processing motors that synthesize long-chain molecules, resemble `assembly lines’ in `automated factories’. Such phenomena are of great interest in several disciplines as varied as systems biology, feedback and control theory, operations research, internet of things, etc.

Malfunctioning of these machines are known to cause various types of disorder and disease some of which are potentially life-threatening. Therefore, understanding the design of the `hardwares’ and the system `softwares’ of these machines would provide deep insight not only into the mechanisms of their operation but also into the possible causes and consequences of their malfunctioning. These insights can be utilized to develop strategies for prevention and cure of diseases thereby improving the quality of life.

Understanding the mechanism of natural nano-machines by reverse engineering is just the first phase of progress on molecular machines. But, as Richard P. Feynman said, "what I cannot create, I do not understand.” While awarding the Nobel Prize in Chemistry for 2016 for pioneering work on the synthesis of artificial Molecular Machines, Nobel committee drew analogy with the industrial revolution of the nineteenth century driven by macroscopic machines. They observed that “In a sense, we are at the dawn of a new industrial revolution of the twenty-first century,…”. Developing countries, like India, must not be left behind while the developed world is progressing fast in this era of new industrial revolution following a “bottom-up route of nano-technology”. Thus, this is an area of interdisciplinary research involving statistical physics, physical chemistry, molecular cell biology and biophysics, and even more exotic areas like nano-biotechnology, nano-robotics, nano-medicine, etc.

Just like their macroscopic counterparts, molecular machines are also governed by the laws of physics. Since our main focus is on general principles, our models usually do not incorporate detailed description of the structures of the machines at atomic resolution because such details vary drastically from one machine to another. On the other hand, completely phenomenological description, based on thermodynamics of irreversible processes in the linear response regime, is inadequate to provide insight into even the generic aspects of the kinetics of these machines as these operate under conditions far from equilibrium. Instead, we follow an intermediate approach. We use conceptual frameworks and theoretical formalisms of stochastic processes and non-equilibrium statistical mechanics to study the generic individual- and collective-properties of molecular machines as well as unique features of some specific examples.

So far our work has focussed mainly on molecular biomechanics and mechano-enzymatics of molecular machines. We are now focussing deeper into the accuracy of genetic information transmission (particularly, communication and computation). Our future plan is to explore various strategies of tinkering the structure and dynamics of the machines so as to achieve their optimized and robust performance as energy transducers and information processors. The results of these curiosities will also throw light on the plausible scenarios of evolution of the designs of the hardware and software of the machines through natural (Darwinian) selection. Our final goal to develop a quantitative theoretical framework for describing a cell as an “automated micro-factory” with its supply chain or, alternatively, as a “smart city”.

For further details, see the Youtube video

http://www.ias.ac.in/MYM2017/Speakers/Debashish_Chowdhury

(a) Technical Summary: "Noise and Non-equilibrium in Natural Nano-machine operation: Statistical Physics Perspective"

(I) Weak Molecular Joints in Multi-component Molecular Machines: principles of Non-covalent Specific Interactions, Self-organization, Emergent Chemo-Mechanics and Dissipative Adaptation of Supramolecular Assemblies Driven far from Thermodynamic Equilibrium

Unlike their macroscopic counterparts, molecular machines assemble at the right place at the right time and, after serving their biological function, disassemble so that the components can be recycled or used for assembling some other machine. Moreover, even during its lifetime, the size, position, orientation as well as the architecture of a such a self-organized machine can change with time, as required for its function, and its components turnover rapidly, often dissipating free energy. Unlike their macroscopic counterparts, the molecular joints in these machines are non-permanent. How a molecular component of such an attachment searches for its partner and, eventually, forms a joint by trial and error is itself a highly nontrivial problem of stochastic chemo-mechanical kinetics. Once formed, the transient molecular joints in the machine need to survive, at least for the duration required for the biological function of the machine, even when subjected to tensile forces. Understanding the ``emergent mechanics'' of such a multi-component self-organized macromolecular machine, i.e., how its mechanical properties emerge from the complex dynamics, interactions and feedback of its energy-consuming active building blocks, is one of the challenging open questions at the interface of physics and biology.

(i) Formation of Molecular Joints in Macromolecular Assemblies and Machines by “Search-and-Capture”: understanding Temporal- and Energetic Efficiencies and accuracy of Search in a Crowded Environment using “First-Passage” Formalism, and Probing Evolutionary Optimization of Search Strategy in-silico

This is a new project initiated very recently.

(ii) Rupture of Non-covalent Molecular Joints in Multi-component Machines by “Escape-over-Barrier” in Free-Energy Landscape: understanding "Active Ligand-Receptor Bonds” in the light of extended Kramers-Bell theory, and Probing Dynamics by Molecular Force Spectroscopy in-silico in search of catch bonds

The strength and durability of standard non-covalent ligand-receptor bonds are measured usually under “force-clamp” and “force-ramp” conditions of Dynamic Force Spectroscopy (DFS). The “mechanical signatures” of “slip-bonds” and “catch-bonds” observed in the bond-rupture experiments, under the protocols of DFS in-vitro, are also used to identify the nature of biomolecular ligand-receptor bonds. The “rare events” of bond-rupture are caused by “escape-over-barrier” on the free energy landscape. Formulating the kinetics in terms of Langevin- and/or Fokker-Planck equations and, hence, computing the First-Passage Times on postulated free energy landscapes, we have calculated the statistical distributions of the lifetimes and rupture forces for molecular joints formed by Microtubule filaments with some specific “receptors” in a mitotic spindle. The Microtubules are the analogs of “ligands” while their specific binding partners are the counterparts of “receptors”. The counter-intuitive properties of these bonds are the consequences of the unique features of the kinetics of polymerization/depolymerisation of the microtubules and the tension-dependence of the rates of these kinetic processes. Analyzing the results of our models by drawing analogy with conventional “ligand-receptor” bonds, we have identified the conditions under which the microtubule-receptor attachments behave like a “slip-bond” or a “catch-bond”.

Research Projects:

(a) Microtubule-Kinetochore attachment (External Collaborator: Blerta Shtylla, MBI, Ohio State University, Columbus, USA).

(b) Microtubule-Cortex attachment (External Collaborator: Raymond W. Friddle, Sandia National Lab, California, USA)

(II) Single natural nano-machine: Principles of Stochastic Thermodynamics, Non-equilibrium Statistical Mechanics, Fluctuating Mechano-Enzymatic Kinetics and Graph theory in Energy Transduction & Information Transmission by an Autonomous Machine at Nano-scale

Members of several families of kinesin and dynein motor proteins are often referred to as “porters” because these cytoskeletal motors can walk along a microtubule track carrying molecular cargo. Polymerases and ribosomes are also motors that walk along nucleic acid tracks; however, instead of carrying cargo, these machines “transcribe” and “translate”, respectively, genetic message thereby "decoding" and "transmitting" information. Molecular machines can be assumed to exist in, effectively, a finite number of discrete states. If a machine can undergo repeated cycling among a set of these discrete states it is, for obvious reason, called a cyclic machine. Guided by known experimental facts, we formulate stochastic kinetic models in terms of (i) mechano-chemical states of the machine, (ii) transitions among the states, and (iii) rates of the transitions. The inter-state transitions are caused by the binding/unbinding of ligands and/or chemical reactions. The rates of transitions are assumed to be given, and not computed from any atomic/molecular theory; the functional dependence of these rates on the concentrations of the substrates/products and on the external forces are also assumed on very general grounds. Besides, examples of particular machines can also be analyzed within this theoretical framework by appropriately identifying the states and inter-state transitions that capture the key features of the machine.

(i) Mechano-enzymatic kinetics of a Molecular motor: stochastic translocation and fluctuating enzymatic reaction as Markov Jump Processes

The “dwell time” of a motor at its allowed positions on the track fluctuates from one position to another even if the track is homogeneous. Nevertheless, its probabilistic pause-and-translocation results, on the average, to a directed motion towards a particular end of the track. The motor also performs the role of an enzyme; the “turnover time” fluctuates from one enzymatic cycle to another which is a very common phenomenon in single-molecule enzymology. Discovering the universal laws of fluctuations of dwell times and turnover times of these mechano-enzymes and identifying the range of their validity is one of the challenges at the interface of physics, chemistry and biology.

Research Projects:

(a) Distributions of Dwell Times of RNAP (External Collaborator: Gunter M. Schuetz, Research Center, Julich, Germany)

(b) Distributions of Dwell Times of Ribosome (External Collaborator: T.V. Ramakrishnan, IISc, Bangalore)

(d) Distribution of Turnover times of enzymatic reactions catalysed by a Ribosome:

from first-passage times to generalized Michaelis-Menten equation and graph theoretic analysis.

(External Collaborators: Jeremy Gunawardena (Harvard University, USA), Felix Wong (Harvard University, USA)).

A Case Study Using Cryo-EM and smFRET Investigations of the Ribosome

(External Collaborators: Joachim Frank (Nobel Laureate, 2017, Columbia University, New York, USA), Ruben Gonzalez Jr. (Columbia

University, New York, USA), Colin Kinz-Thompson (Columbia University, New York, USA)).

(ii) Energy Transduction by a Molecular Machine as a Markov Jump Process on a network of mechano-chemical states: fluctuations, efficiency and power of an autonomous nano-machine

The directed motion of the motor is powered by input chemical energy which the motor extracts by catalysing energy-releasing chemical reaction(s). The molecular machines reveal the subtleties of energy transduction at the nano-scale. The performance of individual machines are constrained by the laws of Stochastic Thermodynamics and the principles of non-equilibrium statistical mechanics. The fundamental questions on these phenomena are at the interface of physics and engineering.

Research Projects:

(a) Stochastic Thermodynamics of a Single Ribosome:

extended King-Altman-Hill-Schnackenberg theory, thermodynamic uncertainty and modes of operation.

(b) Large Deviation Theory for Ribosomes in unconventional Translation (External Collaborator: Arvind Ayyar, IISc. Bangalore)

(iii) Template-directed polymerization by a single polymerase/ribosome as "nano-computation" by a “tape-copying Turing machine”: speed-versus-accuracy

DNA, RNA and proteins are made from a limited number of different species of monomeric building blocks. The sequence of the monomeric subunits to be used for synthesis are dictated by the corresponding template. Each of these polymers gets elongated by one monomer as the respective polymerizing machine decodes a chemically-encoded message and "walks" forward by one step on the template which also serves as the track for the machine. Examples of such machines include DNA polymerase (DNAP), RNA polymerase (RNAP), Ribosome, etc. Selection of the correct molecular species of subunit requires a mechanism of ``molecular recognition''. However, if this mechanism is not perfect, errors can occur. Therefore, the molecular machinery also have mechanisms of ``proofreading'' and ``editing'' so as to correct random errors committed during information processing and achieve accuracy far above those demanded by thermodynamics. Moreover, not all errors are random. Some errors are “programmed”, i.e., induced by signals encoded in the sequence and structure of the nucleic acid strands that serve dual function as template and track; these correspond to various modes of “recoding” of genetic message. We develop stochastic models for quantitative understanding of the principles of information coding, communication and computation involved in the operational mechanisms of these machines. Several concepts of Information Theory and the Theory of Computation enrich the theoretical framework of Physics developed for addressing the fundamental questions in the operational mechanisms of these machines.

Research Projects:

(a) Quality Control in DNA Replication through Proofreading and Editing: Polymerase and Exonuclease activities of DNA Polymerase

(b) Random Errors in Translation: Contributions of mis-charging of tRNA and mis-reading of mRNA to random mis-sense error

(III) Molecular Motor Traffic on Filamentous Tracks: Principles of Non-Equilibrium Steady States, Feedback, Control, Signals, Systems, and Methods of Operations Research for Regulations and Optimization of Stochastic Intracellular Cargo Transport and Noisy Gene Expression

Molecular machines do not work in isolation. Using the formalisms of master equation for interacting self-propelled particles and extremal properties of fluctuating currents, we investigate the effects of congestion, coordination, cooperation, conflict and collision of motors on the dynamical phases of the systems in the Non-Equilibrium Steady States. Our works help in quantitative understanding of the principles of (a) motor-driven intracellular transport of cargo and (b) template-directed bio-polymerization by machines for genetic information processing.

(i) Trip to the Tip with MAPs and +TIPs: Regulation of motor-driven Stochastic Cargo Transport on Cytoskeletal Tracks in-vitro and in Long Cell Protrusions:

Long trip of molecular cargo to the tip of long cell protrusions, like axons and flagella, would be unacceptably slow if these cargo were not hauled by cytoskeletal motors. For example, molecular cargoes synthesized in a neuron cell body, that is no larger than a few tens of micro-meters in diameter, are transported to the distal end of an axon whose length can be, typically, as long as a meter. The challenge of this transport problem is equivalent to the following situation: material supplies that are manufactured and packaged in a 10 meters X 10 meters room have to be transported over 300 Kilometers through a pipe that is no wider than about 5 meters in diameter. Upon arrival at the distal tip, are the cargoes targeted to the cell wall and, if so, what is the mechanism of guiding the cargoes to their respective correct destinations? Or, are the cargoes simply picked up by their appropriate recipients while all the cargoes are circulated by the motors like the food items on a conveyor belt in a Japanese sushi bar? What are the plausible mechanisms by which a cell can maintain, or regulate, the length of a protrusion through intracellular anterograde and/or retrograde transport of "building materials" ?

Research Projects:

(a) Traffic of single-headed kinesin KIF1A in-vitro

(External Collaborators: Yasushi Okada (University of Tokyo, Japan), Katsuhiro Nishinari (University of Tokyo, Japan),

Andreas Schadschneider (University of Cologne, Germany), Philip Greulich (University of Cologne, Germany)

(b) Intraflagellar Transport: effects of fusion and fission of cargo trains

(ii) Regulation of Motor Traffic and Control of Noisy Gene Expression: Roles of Signals, Sequence, Structure and Suppressors in Decoding and Recoding

Interestingly, during translation, many ribosomes move along the same mRNA template strand synthesizing distinct copies of the same protein. How is the ribosome traffic influenced by "signals" encoded in the sequence of the monomeric subunits and the secondary structure of the mRNA track as well as by RNA-bound proteins? Similarly, many aspects of DNA metabolism, including transcription and replication, occur simultaneously on the same segment of DNA and interfere with each other. High level of transcription of a gene can suppress that of another because of the interference through either co-directional or head-on collision of RNA polymerase (RNAP) motors engaged in the two transcriptional processes. What are the possible mechanisms of regulation of transcription by such “Transcriptional Interference”? Similarly, conflicts between transcription and replication, arising from the encounter between a replisome and RNAP motors, must be resolved frequently without causing genome instability. What are the traffic rules adopted by nature for such conflict resolution? Long stretches of naked DNA are unlikely to persist in vivo; rather, genomic DNA is coated with proteins that facilitate DNA compaction, organization, and maintenance. The transcription and replication processes must all take place on chromosomes that are occupied by a large number of other proteins? What are the effects of such bottlenecks on traffic flow? How do the traffic of polymerases and ribosomes respond to the intra-cellular as well as extra-cellular signals, including cellular stress? How are these traffic optimized for the given constraints that arise from the available limited resources, like tracks, motors, fuels and other substrates? A multi-disciplinary approach combining physics, systems biology and operations research is being attempted to answer some of these questions.

Research Projects

(a) Spatio-temporal organization of Ribosomes on mRNA track during Translation: effects of mechano-chemical cycles of individual Ribosomes on Polysomes

(b) Regulation of Ribosome Traffic on mRNA template and Control of Unconventional Translation: Consequences of Programmed Error and Recoding

(External Collaborator on Ribosomal Frameshift: Gunter M. Schuetz, Research Center Julich, Germany)

(c) Spatio-temporal organization of RNA Polymerases on DNA track in normal Transcription: effects of in mechano-chemical cycles of individual Polymerases

(d) Regulation of RNAP Traffic on DNA template strand with overlapping genes: Switch-like consequences of Transcriptional Interference

(e) Collision of RNAP motors and Replisome on DNA track during simultaneous Transcription and Replication: resolution of transcription-replication conflict

(External Collaborator: Andreas Schadschneider, University of Cologne, Germany)

Past Research Areas and projects:

(a) Interacting Self-driven Particles; self-organization, traffic and traffic-like collective phenomena:

In contrast to the inanimate particles driven by external fields, the "particles" representing living organisms (e.g., cells, bacteria, ants, etc.) as well as vehicles in the particle-hopping models are "self-driven" in the sense that they transform energy gained from food or fuel into mechanical energy required for the forward movement. We have derived exact analytical results for some minimal models of vehicular traffic, introduced new (more realistic) models and developed novel schemes for highly accurate approximate analytical calculations for such systems. Our pedagogical review article (published in Physics Reports in 2000) on physics of vehicular traffic helped in bridging the communication gap between statistical physicists and traffic engineers working on this inter-disciplinary topic. An expanded and updated version of this review, written from a broader perspective, has been published as a book (by Elsevier in 2011). Applying similar concepts and techniques, we have developed quantitative theories of traffic-like collective movement of ants on ant-trails and intracellular traffic of molecular motors filamentous proteins.

(b) Lattice models of proteins and surfactants:

We showed that, contrary to some earlier conjectures, the self-avoiding linear chain model of polymers with ``bridges" (that represent the hydrogen bonds) is inadequate for explaining the experimentally observed vibrational dynamics of heme proteins. We made pioneering contributions towards understanding the meta-stability and spontaneous bursting of Newton black filmswhich are the thinnest possible soap films. We discovered novel micellar aggregates of pure dimeric surfactants (also called "gemini" surfactants). We also demonstrated that in a mixture of single-chain and dimeric surfactants dispersed in water the geminis can spontaneously crosslink the micelles of single-chain surfactants, thereby forming "super-aggregates" of micellar aggregates.

(c) Spin Glasses, Random Ferro- and Anti-ferro Magnets; phase transition, critical dynamics and kinetics of phase ordering:

I began my research career in 1980 by studying the nature of the spin glass ordering and associated dynamical phenomena, e.g., non-exponential relaxation. Moreover, we theoretically interpreted the experimentally observed behavior of the magnetoresistance of spin glass alloys. I also clarified the role of the Onsager reaction field in the spin glass transition. My review (published in Physics Reports in 1984) and monograph on spin glasses (published in 1986 jointly by Princeton University Press and World Scientific) have been very useful for beginners as well as experts. We resolved a controversy regarding the critical exponents of disordered Ising-like magnets. We also discovered a ``singular" dynamic scaling in strongly disordered Ising-like magnets and demonstrated a ``logarithmically" slow growth of ordered domains in both ferro- and anti-ferro magnets in the presence of quenched random impurities.

Graduate students (Ph.D. students/Ph.D.-M.Sc dual degree students):

Former Graduate Students (Ph.D. students):

Bibhudhananda Biswal, Professor, Cluster Innovation Centre, and Coordinator, Design Innovation Centre, University of Delhi (India).

Prabal K. Maiti, Department Chair and Professor, Department of Physics, Indian Institute of Science, Bangalore (India) (Postdoctoral Research Experience: Humboldt Fellow @ MPI-PF Mainz (Germany), Postdoc @ Colorado, Boulder (USA), Postdoc @ Caltech, Pasadena (USA),

(Prabal was awarded Dr. Shankar Dayal Sharma Medal of IIT Kanpur in 1998 as the best graduating student based on general proficiency including character and conduct and excellence in academic performance, extra-curricular activities, and social service).

Ambarish Kunwar, Associate Professor, Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Mumbai (India) (Postdoctoral Research Experience: Postdoc @ UC-Irvine (USA), Postdoc @ UC-Davis (USA)).

Tripti Tripathi (Bameta), DST Inspire Faculty, Centre for Excellence in Basic Sciences, University of Mumbai & Department of Atomic Energy, Mumbai (India).(Postdoctoral Research Experience: Postdoc @ IIT-B, Mumbai)

Ashok Garai, Associate Professor, L. N. Mittal Institute of Information Technology, Jaipur (India) (Postdoctoral Research Experience: Postdoc @ Bremen (Germany), UCSD (USA) & IISc, Bangalore (India)).

Ajeet Kumar Sharma, Assistant Professor, Department of Physics, Indian Institute of Technology, Jammu (India) ((Postdoctoral Research Experience: Post-Doctoral Fellow @ Department of Systems Biology, Harvard Medical School, Harvard University (USA); Postdoc @ Pennsylvania State University (USA)).

Dipanwita Ghanti (Postdoctoral Research Experience: Postdoc @ Institute of Ruđer Bošković, Zagreb (Croatia)).

Bhavya Misra (Postdoctoral Research Experience: Postdoc @ Johns Hopkins University (USA))

Soumendu Ghosh

Annwesha Dutta, Inspire Faculty @ IISER-Tirupati (Postdoctoral Research Experience: ICTP, Trieste (Italy)).

Swayamshree Patra, (Postdoctoral Research Experience: Postdoc @ Yale University (USA)) (Swayamshree is a recipient of the "Outstanding Ph.D. Thesis Award of IIT Kanpur, 2021).

Former Undergraduate Research Students and collaborators (M.Sc. students):

C. Buragohain, Ph.D. (Physics, Yale Univ.), Ph.D. (Computer Science, University of California at Santa Barbara, USA), at Amazon.com

R. S. Bandhu, Ph.D. (Ohio State Univ.?)

S. Sabhapandit (Ph.D. TIFR, Mumbai, India), faculty member, Raman Research Institute, Bangalore, India.

P. Taneja (Ph.D., TIFR, Mumbai, India)

A. Majumdar, Ph.D. (Boston Univ., USA?)

K. Ghosh, Ph.D. (Univ. of Massachusetts, Amherst, USA), Associate Professor (University of Denver, Colorado, USA)

S. Sinha, Ph.D. (Harvard Univ.?)

A. Pasupathy, Ph.D. (Cornell Univ., USA), Associate Professor (Columbia University, USA)

A. Gopinathan, Ph.D. (Univ. of Chicago, USA), Professor (University of California at Merced, USA)

V. Guttal, Ph.D. (Ohio State University, USA), Postdoctoral Research Associate (Princeton University, USA), Associate Professor (IISc., Bangalore)

A. Basu, Ph.D. (Stanford University, USA), Postdoctoral Research Associate (Rockefeller, University, USA), Postdoctoral Fellow (Johns Hopkins University, USA)

Debanjan Chowdhury, Ph.D. (Harvard University, USA), Gordon & Betty Moore Foundation Postdoctoral Fellow (MIT, USA).

Sumit Sinha, Graduate student (University of Texas at Austin)