CURRICULUM VITAE

Name                    :    Supurna Sinha


Academic Career   :   Ph.D. (Physics)      Syracuse University    1992

:   Title of Thesis    Collective Dynamics in
Dense Fluid Mixtures

:   Ph.D. Advisor     M. Cristina Marchetti

:   M.S.         Syracuse University    1988

Positions Held  in the past :

1. JNC Fellow,
Jawaharlal Nehru Centre for Advanced Scientific Research
and Department of Physics,
Indian Institute of Science, Bangalore, India.

2. Visiting Scientist,
Centre for Theoretical Studies,
Indian Institute of Science, Bangalore, India.

3. Post Doctoral Fellow,
Raman ResearchInstitute
Bangalore, India.

4. Visiting Faculty,
Harish Chandra Research Institute (HRI),

Educational Qualifications:

School   Certificate(1979)       Visvabharati  University    81% (First Division)  (1st Rank)

Higher Secondary (1981)          South Point                          77% (star marks:First Division)
(Letter Marks in Physics).

B.Sc (1984)                                  Jadavpur University           Physics (Hons.) 80%
(First Class: 2ndRank)

MS (1988)                                    Syracuse University             Physics: CGPA 3.92 on a scale of 4.0

PhD (1992)                                   Syracuse University            Title: Collective Dynamics in
Dense Fluid Mixtures''

Synopsis of PhD. Thesis:

My thesis deals with the short wavelength collective dynamics of dense binary fluid mixtures. The analysis shows that at the level of linearised generalised hydrodynamics, the longitudinal modes of the system separate essentially into two parts- one, involves the coupling of partial density fluctuations of the two species and the other involves the coupling of longitudinal momentum and temperature fluctuations. We have shown that the coupling of longitudinal momentum and temperature fluctuations leads to an adequate description of sound propagation in such systems. In particular, we show that structural disorder controls the trapping of sound waves in dense mixtures. The coupling of the partial density fluctuations of the two species leads to a simple description of the partial dynamic structure factors. We find that our results are in agreement with the molecular dynamics simulations of soft sphere mixtures. The partial density fluctuations are the slowest decaying fluctuations on molecular length scales and it turns out that nonlinear coupling of these slow modes lead to important corrections to the long time behavior of the time correlation functions determining the shear viscosity in dense mixtures.

Highlights of Research Publications and their impact:

During my postdoctoral stay at the Indian Institute of Science I had written a single author paper on Dynamic Structure Factors
of a Dense Binary Mixture  in which I had made certain predictions about the diffusional dynamics of glassy mixtures which have
been corroborated by a  Harvard Group of experimentalists  (See for instance, A. D. Dinsmore, E. R. Weeks, V. Prasad, A. Levitt and D. A. Weitz, Applied Optics, Vol. 40, 4152, 2001).  Subsequently, during my postdoctoral tenure at RRI I had written a single author paper
on  Low Temperature Decoherence which has influenced experimental work in this area by a Caltech group of
experimenters (See, for instance,  Webb et al,  Fortschrift  Phys. Vol. 46,  779, 1998). The power law loss of coherence
predicted in my paper has been seen in  NMR spectra of proteins and vibrational spectra
of highly excited molecules at Urbana (See, for instance,  V. Wong et al , Physical Review A, Vol. 63, 022502, 2001).

My  work on dense binary mixtures with M. C. Marchetti has been appreciated by the glass transition research community (for instance, P. T. Visscher, in a letter to M. C. Marchetti
and E. G. D. Cohen, at a stat-mech meeting, have personally acknowledged the importance of our work ). It has also influenced the course of glass transition theory in mixtures ( See for instance,  U. Harbola and S. P. Das, Physical Review E 65, 036138 (2002)).
One of my papers with M. C. Marchetti in this area has been included in a special collection of papers on Thermal and Statistical Physics'.

My paper on Brownian Motion at Absolute Zero written with R. D. Sorkin predicts, on the basis of the fluctuation-dissipation theorem, a logarithmic growth of mean square displacement  with time . W. D.  Phillips ( NIST, 1997 Nobel Prize) had found such a model independent prediction
for the  slow growth of mean square displacement at low temperatures intriguing and had discussed it in some detail with R . D. Sorkin and me and had shown interest in checking the claim experimentally.

My work on  Laser Induced Freezing of Colloids written with J. Chakrabarti led to certain predictions
regarding the effect of fluctuations on the re-entrant phase.  These  predictions have been corroborated  in
state-of-the art experiments ( See, for instance,  Wei et al, PRL, Vol 81, 2606, 1998).

My work with J. Samuel  on  Brownian Motion and Magnetism  where we had mentioned the connection
with polymer distribution functions, has found a very timely and relevant application in the area of semiflexible polymers in
biological physics. Our work in this area of biological physics has been appreciated by active researchers in this area such as
S. Stepanow and Y. Rabin (See, for instance, S. Stepanow and
G. M. Schutz , Europhys. Lett. 60, 546 (2002)).

One of our papers in this area has been described  by the referee
as  a timely contribution to the rapidly growing field of biological physics '' and an important contribution to the field''.

My single author paper Writhe distribution of
stretched polymers'' published in Physical Review E  has been noticed by the American Journal Experts
who have been impressed by the quality of the research
and the thought behind my paper.  It has also been much appreciated
by a referee of the paper who commented:
I do like the paper and its simple results. It is also an exceptionally
honest paper, since it states the limits of this presented analytical
theory in a remarkable way!''

The editor of Journal of Physics Condensed Matter (JPCM)
has brought it to our attention that
our recent paper DNA elasticity :topology of self avoidance'' which
has appeared in JPCM (2006) in the
as recorded till Sep, 2006. [See, http://www.iop.org/journals/jpcm]

Our paper Euler buckling in red blood cells ...'' written in collaboration with a TIFR , Mumbai group of experimenters has
been highlighted by New Scientist [See the coverage of this work
in the August 20, 2005 issue].

Recently, we have developed an intriguing analogy between the
surface tension of membranes in condensed matter and the notion
of cosmological constant in the context of gravity. Our analogy
realizes a compelling idea due to R. D. Sorkin which traces the small
finite observed magnitude of the cosmological constant to the
underlying discreteness of spacetime structure on quantum
gravity scales. We propose a soft condensed matter experiment
to realize this analog quantum gravity prediction.
[See Surface tension and the cosmological constant'', J. Samuel
and Supurna Sinha, Physical Review Letters,  97, 161302, 2006].

Research Interests:

a.  Focus of PhD. work:

My primary research interest is in soft condensed matter physics. During my PhD. years my focus has been on understanding the dynamical mechanism behind glass formation. Glass is a state between a liquid and a crystalline solid. It is a disordered solid which can flow" over very long time scales. My interest was in understanding how the addition of a second component in a one-component liquid affects the rate of glass formation.

b.  Further Research  Interests:

Since my PhD. years my research interests have broadened. I have done research on freezing of colloids in the presence of laser beams, Brownian motion at absolute zero, optics, and have also studied loss of coherence at the absolute zero of temperature.

I have studied the distribution of solid angles (Refs.6,15) in a random walk on a sphere. This study was motivated by the problem of depolarisation which occurs when light is elastically scattered in a random medium. The same problem also comes up in the distribution of Berry phases for a random Hamiltonian and the diffusion of fluorescent molecules on the surface of a spherical micelle. The methods developed in this study have a natural application in polymer physics, which is my present interest.

Semiflexible polymers:program

As I mentioned earlier  J. Samuel and I have worked on a theoretical analysis of elasticity of biological polymers motivated by an
analogy with depolarized light scattering.  The methods developed in Refs.(6,15) can be adapted to produce a complete and exact solution of the Worm Like Chain model (WLC) for semiflexible polymers. This simple model captures much of the physics of the real system with just two parameters.  Experiments on single DNA molecules are being carried out in the RRI in Prof. Shivashankar's lab. I have had an opportunity to interact closely with experimentalists and theorists working in this field at the Raman Research Institute. I intend to continue on an ongoing project (in collaboration with Joseph Samuel and Abhishek Dhar) to work out all the predictions of the Worm Like Chain (WLC) model. Such a study would be of crucial importance in constructing refinements of the model to get better agreement with experimental data.

We are also looking into the possibility of experimentally checking
some qualitatively interesting features
that have come out of Abhishek Dhar and Debashish Chaudhury's simulations, which have
been corroborated by our (J. Samuel and S. Sinha) theoretical work  in this area.
We have had some preliminary discussions with V. A. Raghunathan, Y. Hatwalne and Abhishek Dhar.
Granular materials:Movie

Abhishek Dhar and I have been collaborating on experiments  involving vibrating mustard seeds at the Theorists' Lab at
RRI. This is a scaled up Brownian motion' experiment and we are interested in looking at structural correlations in such  systems.
Such experiments throw up many interesting issues - in what way does inelastic collisions in such systems
affect  say cage' formations in a dense granular system ? How does fluctuation-dissipation theorem work in
such a system and so on.

Onset of shear waves in a Bacterial Bath:

In recent years there have been experiments probing Brownian Motion' of
polysterene
spheres in bacterial baths . These experiments point
to a crossover from superdiffusive to diffusive
behavior of the mean-square
displacement of the polysterene beads suspended in a bacterial bath.
This effect is similar to ballistic to diffusive transition in passive
Brownian systems where the borderline for such a transition is given by
the viscous damping time , which for a polysterene
bead of diameter 10 micron is about 10 micro sec. However, in the case
of an active bacterial bath one notices that such a transition takes
place at a time of about  2 sec .

To sum up, one of the key observations coming out of
these experimental studies is the emergence of a time scale and a
corresponding length scale in the Brownian motion of a polysterene bead
suspended in an active bacterial bath. The time at which this crossover takes place increases
with the increase in the density n of the bacterial bath, indicating the appearance of solid-like ordering over
length scales of the order of  10 micron.
In a simple dense liquid such ordering takes place on molecular length scales. In the present experiments the liquid'
under consideration is an active medium of biological origin. Nonetheless, one
can import some of the ideas from passive liquids to understand certain aspects of
the dynamics of such a bath. In particular, I am focussing  on the fact that
such a structural ordering in the bacterial bath would indicate the appearance of a shear
wave on length scales of the order of 10 micron. This is the
focus of my present theoretical study which has experimental implications.

Theorists' Lab:

At the theorists' lab at RRI  Abhishek Dhar and I have been looking at a scaled up Brownian Motion' experiment, which I have
described in the Granular Materials section.  We also intend to look at scaled up  entropy driven motion of DNA' experiments
using chains and  nylon threads- These experiments, apart from demonstrating conceptual issues in statistical mechanics,
throws up challenging research level questions which we intend to look into.

Teaching Experience:

I have had experience in teaching undergraduate level Classical Mechanics and Electromagnetism at Syracuse University. I have also been a grader in a graduate level Solid State Physics Course at Syracuse. I have given lectures on Hydrodynamics and Mode-Coupling theory to PhD. students at the Indian Institute of Science. During my stay at the Raman Research Institute, I have been involved in presenting elementary optics to school children with practical demonstrations involving lasers.

During the past few years I had worked towards developing educational CDroms and web-based tutorials in Mathematics and Physics at the pre-university and undergraduate levels as part of software companies like SSI, egurucool.com and Hotmath Inc. USA. I have written educational articles combining Mathematics and Physics for the Children's section in Deccan Herald' and also written articles for science education journals such as Resonance' and Jantar Mantar'.

Selected List of Publications:

1. Brownian Motion at Absolute Zero,"
Supurna Sinha and R. D. Sorkin,
Physical Review B,  45,  8123 (1992).

2. Mode-Coupling Theory of the Stress-Tensor Autocorrelation Function of a Dense Binary Fluid Mixture"
Supurna Sinha and M. C. Marchetti ,
Physical Review A,  46,  4942 (1992).

3.Dynamic Structure Factors
of a Dense Mixture,"  Supurna Sinha,
Physical Review E,  49, 3504 (1994).

4.Brownian Motion and Magnetism "
S. Sinha and J. Samuel, Rapid Communication in Physical Review B ,
B50,
13871 (1994).

5. Effect of Fluctuations on Laser Induced
Freezing of Colloidal Suspensions"
J. Chakrabarti and S. Sinha,
Journal de Physique II , 7, 729 (1997).

6. Decoherence at Absolute Zero,''
Supurna Sinha,  Physics Letters A,  228,  1 (1997).

7. Elasticity of Semiflexible polymers,''
J. Samuel and S. Sinha  Physical Review E, 66, 05801 (R)
(2002).[Selected for the Virtual Journal Of Biological Physics Research]

8. Onset Of Shear Waves In A Bacterial Bath: A Novel
Effect,'' Supurna Sinha,  Fluctuation and Noise
Letters, 3, L373 (2003).

9. Writhe Distribution of Stretched Polymers,''
Supurna Sinha,  Physical Review E,  70, 011801 (2004).
[Selected for the Virtual Journal Of Biological Physics Research]

10. Inequivalence Of Ensembles in Single Molecule
Measurements'', S. Sinha and J. Samuel,
Physical Review E ,  71, 021104 (2005).
[Selected for the Virtual Journal Of Biological Physics Research, March 1
2005]

11. Euler buckling-induced folding and rotation
of red blood cells in an optical trap,'' A.
Ghosh, Supurna Sinha, J. Samuel,  J. A. Dharmadhikari,
S. Roy,
A. K. Dharmadhikari, S. Sharma and D. Mathur;
[ Phys. Biol.  Vol.  3,  67-73 (2006)]. ;
(this work has been highlighted in a coverage in New Scientist".
Zeeya Merali, 2513, 20 August 2005).

12.Surface Tension and the Cosmological
Constant,"  Joseph Samuel and  Supurna Sinha,
Physical Review Letters,  97, 161302 (2006).

13.Jamming Dynamics in Grain Mixtures:
An Extended Hydrodynamic Approach,"
Supurna Sinha,
Fluctuation and Noise Letters, 7, L163 (2007).

List of Publications : Technical papers

1. Short Wavelength Collective Modes in a Binary Hard Sphere Mixture," (M. C. Marchetti and S. Sinha), Physical Review A 41 3214 (1990). This paper has been reprinted in a special web based collection of papers on thermal and statistical physics under the heading Mode-Coupling Theory'.

2. Sound Propagation Gap in Fluid Mixtures", (S. Sinha and M. C. Marchetti), Physical Review A 42 5015 (1990).

3. Brownian Motion at Absolute Zero," (S. Sinha and R. D. Sorkin), Physical Review B 45 8123 (1992).

4. Mode-Coupling Theory of the Stress-Tensor Autocorrelation Function of a Dense Binary Fluid Mixture." (S. Sinha and M. C. Marchetti), Physical Review A 46 4942 (1992).

5. Dynamic Structure Factors of a Dense Mixture." , S. Sinha,
Physical Review E
49 3504 (1994).

6. Brownian Motion and Magnetism " (S. Sinha and J. Samuel),Rapid Communication in Physical Review B B50 13871 (1994).

7. Effect of Fluctuations on Laser Induced Freezing of Colloidal Suspensions" (J. Chakrabarti and S. Sinha), Journal de Physique II 7 729 (1997).

8. Short Wavelength Collective Modes in a Binary Hard Sphere Mixture," (M. C. Marchetti and S. Sinha), Bulletin of the American Physical Society 35 268 (1990).

9. Collective Dynamics in a Dense Binary Mixture," S. Sinha, Europhysics Conference Abstracts 14 C (1990) #B1.

10. Large Mode-Coupling Effects in a Dense Mixture," (S. Sinha and M. C. Marchetti), Bulletin of the American Physical Society 37 707 (1992)

11. Quantum Brownian Motion", S. Sinha and R.D. Sorkin) Bulletin of the American Physical Society 37 650 (1992).

12. Decoherence at Absolute Zero'' , S. Sinha,  Physics Letters A228 1 (1997).

13. Thomas Rotation and Polarised Light: A non-Abelian Geometric Phase in Optics" (J. Samuel and S. Sinha), Pramana-J. Phys. 48 969 (1997).

14.  Four-photon interference: a realizable experiment to demonstrate violation of EPR postulates for perfect correlations" (P. Hariharan, J. Samuel and S. Sinha),Journal of Optics B : Quantum and Semiclassical Optics1 199 (1999).

15. Brownian motion on a sphere:distribution of solid angles" (M. M. G. Krishna , J. Samuel and S. Sinha) Journal of Physics A (Mathematical and General)33 5965 (2000)

16. Elasticity of Semiflexible polymers''

(J. Samuel and S. Sinha)  {\it Physical Review E} {\bf 66}, 05801 (R) (2002).
[Selected for the Virtual Journal Of Biological Physics Research]

17. Molecular Elasticity and the Geometric Phase''
(J. Samuel and S. Sinha) {\it Physical Review Letters} {\bf 90} 098305 (2003).
[Selected for the Virtual Journal Of Biological Physics Research]

18. Onset Of Shear Waves In A Bacterial Bath: A Novel
Effect'' , S. Sinha, {\it Fluctuation and Noise
Letters} {\bf 3} L373 (2003).

19. Writhe Distribution of Stretched Polymers'',
S. Sinha, {\it Physical Review E} {\bf 70} 011801 (2004).
[Selected for the Virtual Journal Of Biological Physics Research]

20. Inequivalence Of Ensembles in Single Molecule
Measurements''( S. Sinha and J. Samuel),
{\it Physical Review E} } {\bf 71}, 021104 (2005).
[Selected for the Virtual Journal Of Biological Physics Research, March 1
2005]

21. Euler buckling-induced folding and rotation
of red blood cells in an optical trap''[with A.
Ghosh, J. Samuel,  J. A. Dharmadhikari,
S. Roy,
A. K. Dharmadhikari, S. Sharma and D. Mathur;
[{\it Phys. Biol.} {\bf 3} 67-73 (2006)]. ;
(this work has been highlighted in a coverage in New Scientist".
Zeeya Merali, 2513, 20 August 2005).

22. Dynamics of Vibrated Grains''
(Abhishek Dhar and S. Sinha- cond-mat/0410142).

23. DNA Elasticity: Topology Of Self-Avoidance''
[J. Samuel, S. Sinha and A. Ghosh: Appeared in Journal Of Condensed Matter
as a special issue article as part of the Biopolymer Workshop, Trieste;
Journal of Physics: Condensed Matter, 18,  S253 (2006).]

24. Surface tension and the cosmological constant''

J. Samuel and S. Sinha
Physical Review Letters,  97, 161302 (2006).

25. Jamming Dynamics in Grain Mixtures:
An Extended Hydrodynamic Approach,"
Supurna Sinha,

Fluctuation and Noise Letters, 7, L163 (2007).

List of Publications : Popular Articles

1. The Co-axial Cable: How Cable TV operators view the Laplacian operator'' (with Joseph Samuel) Resonance, August 1997 issue, 2 32 (1997).
2. Order Out of Disorder" Resonance, January 1999 issue, 4 63 (1999).
3. Fun With Tiles" Jantar Mantar, September 1999 issue, 3 21 (1999).
4. Poincare and the Special Theory of Relativity" Resonance, February 2000 issue, 5 12 (2000).
5. Einstein and the Special Theory of Relativity" Resonance, March 2000 issue, 5 6 (2000).
6. Can light travel faster than light?" Resonance, November 2000 issue, 5 90 (2000).
7. Refraction" (with Joseph Samuel)Jantar Mantar, March-April 2001 issue, 2 21 (2001).
8.  Play of Colours(Translation of an article by Jagadananda Ray)" Jantar Mantar, July-August 2002 issue, 10 8 (2002).

9. Biopolymer Elasticity' physics/0308003 - published in Study Circle
(2003).

Some conferences attended:

1.  Conference on Fluid Dynamics, Buffalo, 1987.
2. Rutgers Conference on Statistical Physics, Rutgers, 1988 and 1990.
3. Ist Conference on Liquid Matter, Lyon, 1990.
4. American Physical Society Meeting, Indiannapolis, March 1992.
5. Conference on Common Problems in Condensed Matter
and Low-dimensional Field Theory, Madras, 1993.
6. Indo-French Conference on Mathematical Methods
for Partial Differential Equations, Bangalore, 1994.
7. SERC School on Optics,  Madras, 1995.
8. International Conference on Liquid Crystals,
Bangalore, 1996.
9. International Conference on Liquid Crystals, Bangalore, 2002.
10. International Workshop On Single Molecule Biophysics, NCBS, Bangalore, Jan 4-15, 2004.
11. Workshop on Biopolymers at ICTP, Trieste (May 25, 2005 - June 3, 2005).