PREVIOUS COLLOQUIA - 2009

Abstract

08.05.2009

Prof. K. N. Ganesh,

IISER, Pune

DNA Templated nanoassemblies

19.06.2009

Prof. R. Ramaswamy,

JNU, Delhi

The flavours of synchrony

03.07.2009

Prof. Shibaji Raha,

Bose Institute, Kolkata

Climate Change and Cosmic Rays

Climate change has recently been realised as constituting the gravest threat to the present state of civilisation. The facets of climate change (or global change, as some investigators prefer to call it) are indeed diverse. For tropical countries like India, one of the most serious concerns is the stability of monsoon. To this end, a comprehensive understanding of the microphysics of cloud formation, though absolutely essential for successful modelling studies, is still lacking. The role of cosmic rays in cloud condensation has been appreciated only lately.

In this talk, I shall try to discuss some of these ideas and highlight thescope of research on these aspects at the National Facility for Astroparticle Physics & Space Science at the Darjeeling and Salt Lake campuses of Bose Institute.

18.07.2009

Prof. K. A. Muttalib,

University of Florida, USA

Random Systems: when the average is not good enough and the "Tail" can become the "Head"

I will briefly outline why knowing only the average property of a given macroscopic random system may not always be very meaningful, and relying on it can sometimes be downright dangerous! I will highlight the importance of knowing the probability of rare events, or the "tail of the distribution". In particular, I will show that for a highly disordered electrical wire, the distribution of conductance (inverse of resistance) has a long tail, and changes its shape dramatically (so that “the tail becomes the head") as randomness is changed.

14.08.2009

Prof. Abhirup Sarkar

ISI, Kolkata

DEVELOPMENT AND DISPLACEMENT

28.08.2009

Prof. Prasanta Panigrahi

IISER Kolkata

Beauty of cold atoms

11.09.2009

Prof. S.  M. Bhattacharjee,

IOP, Bhuvaneswar

Work, path and thermodynamics

A thermodynamic transformation is a reversible quasi-static process but    a work theorem suggests that the free energy difference between  any two states can also be obtained by arbitrary nonequilibrium processes. We discuss various aspects of this connection between equilibrium thermodynamics    and nonequilibrium path integrals.

09.10.2009

Prof. Mustansir Barma,

TIFR, Mumbai

Ordered State with Giant Fluctuations

When systems are driven far from equilibrium, they often reach nonequilibrium steady states with interesting properties. This is illustrated by a study of simple models of particles sliding down a randomly fluctuating surface. Locally, the density shows giant fluctuations while the density-density correlation function is a singular function of separation and system size. This signals a new sort of statistical state – one in which long range order coexists with giant fluctuations. This is found through numerical simulations and is supported by analytical results for simple models. Ordering with giant fluctuations has also been found recently in other systems such as active nematics and granular gases.

23.10.2009

Prof. Dipti Prasad Mukherjee,

ISI, Kolkata

On exploiting image and video content

In this talk I shall make a presentation on some of our research activities involving image and video. Segmentation of image content into a set of meaningful components is a challenging research problem and I shall present a set of interesting image segmentation applications. The applications for video mainly involve automatic target identification and target tracking. I shall show that our proposed approach is effective both for medical and related video. A related interesting problem that we have investigated is the study of abrupt changes in video content for video key frame estimation. Finally, I shall conclude this talk highlighting some of our recent efforts in authenticating and securing image information.

20.11.2009

Prof. Probir K. Bondyopadhyay,

 Houston, Texas

A Historian's Tribute to P. A. M. Dirac

Nobel Laureate Professor Paul Adrien Maurice Dirac [1902-1984], Lucasian Professor of Mathematics [1932-1969] in the University of Cambridge, Great Britain was the principal founder of quantum mechanics. He is world famous for (1). the quantum theory of the electron, (2). Fermi-Dirac statistics that played a pivotal role in the invention of the junction transistor that brought about the silicon revolution [information technology ], (3). prediction of positron ( anti-matter ) and (4). immortalizing  the name of Professor Satyendra Nath Bose [ April 1947 ].

Professor Dirac played a prominent role in the recognition and  advancement of science research in India. Dr. Homi Jehangir Bhabha and Dr. Harish Chandra (Mehrotra) were his prominent Indian students. This historical presentation for general audience will remember  Professor Dirac the scientist, perhaps the greatest scientist of the twentieth century, and highlight the impact of his contributions  to the benefit of mankind.

11.12.2009

Prof. Diptiman Sen,

IISC, Bangalore

Quenching across quantum critical points and lines

It is known that defects are produced when a parameter in the Hamiltonian of a quantum system is changed slowly so as to take its ground state across a quantum critical point. The density of defects can be shown to scale as a power of the quenching rate, where the power depends on the dimensionality of the system and two of the critical exponents. We will extend this result to the cases of quenching across or along critical lines. We will also show that quenching generates entropy and quantum entanglement. All our results will be illustrated using some exactly solvable spin models like the Ising model in a transverse field in one dimension and the Kitaev model in two dimensions.