Tata Institute of Fundamental Research

www.tifr.res.in www.tifrh.res.in/index.html/
Mumbai, India

The Tata Institute of Fundamental Research is a research institution in Mumbai, India, dedicated to basic research in mathematics and the science. It is a Deemed University and works under the umbrella of the Department of Atomic Energy of the Government of India. It is located at Navy Nagar, Colaba, Mumbai. TIFR conducts research primarily in natural science, mathematics, biological science and theoretical computer science and is considered one of the outstanding research centres in India. TIFR has a graduate program leading to a PhD in all the major fields of study.The TIFR is rated with “A” grade as per MHRD. It is the only one among 4 in Maharashtra State, the other 3 being centrally funded UDCT , TISS and CIFE. Wikipedia.

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News Article | May 19, 2017
Site: cerncourier.com

One of the most brilliant theorists of his time, Pierre Binétruy, passed away on 1 April. Binétruy received his doctorate on gauge theories in 1980 under the direction of Mary K Gaillard, and held several positions including a CERN fellowship and postdocs in the US. In 1986, he was recruited as a researcher at LAPP in Annecy-le-Vieux and, four years later, he moved to the University of Paris XI. Since 2003 he was a professor at Paris Diderot University. He helped to found the Astroparticle and Cosmology Laboratory (APC) in 2005 and was its director until 2013. We also owe to him the involvement of the APC in space sciences, Earth sciences, and the realisation of the importance of data science. Binétruy’s research interests evolved from high-energy physics (notably supersymmetry) to cosmology and gravitation, and in particular the intersection between the primordial universe and fundamental theories. His recent interests included inflation models, dark energy and gravitational-wave cosmological backgrounds. During his prolific career, he published seminal papers that approached 1000 citations each and received several awards, including the Thibaud Prize and the Paul Langevin Award. But he will also be remembered for his spirit and courage. He knew that it was necessary not only to seek scientific truth but also to have the courage to prepare the community for the scientific goals that this truth demands and to fight to defend them. Older members of IN2P3 remember the extraordinary intellectual atmosphere that animated the Supersymmetry Research Group, which he proposed and directed from 1997 to 2004, transforming it into an unprecedented crossroads for experimenters and theorists. By that time, when the detection of gravitational waves was for many a distant dream, he also had the intuition to involve France in the field of gravitational-wave detection via the LISA Pathfinder programme – a scientific choice to which he devoted great dynamism right up to his death. Binétruy was also an inspiration to hundreds of students. Through the MOOC Gravity project, which he developed in collaboration with George Smoot, his courses reached tens of thousands of students. He viewed MOOC not just as a simple way to improve the visibility of the university, but as a revolution in the way knowledge is diffused. In parallel with these activities, Binétruy found time to be president of the Fundamental Physics Advisory Group (2008–2010) and the Fundamental Physics Roadmap Committee (2009–2010) of ESA; the French consortium of the LISA space mission; the theory division of the French Physical Society (1995–2003); and the theory section of CNRS (2005–2008). He was also a member of the IN2P3 Scientific Committee (1996–2000) and numerous other panels. Alongside his scientific activities, which he pursued with enthusiasm and unfailing rigor, Binétruy had a deep appreciation and knowledge of broader culture. He had a profound knowledge of the arts, where he was the driving force behind several interactions between art and science. As one of his eminent colleagues said of him: “Pierre was one of those very exceptional people who was at the top of the game and, at the same time, a remarkably pleasant colleague.” Our mentor, colleague and close friend Gösta Ekspong passed away peacefully on 24 February at the age of 95. His life as a particle physicist covered the nuclear-emulsion epoch, the bubble-chamber years, experiments at CERN’s Large Electron–Positron (LEP) and Super Proton Synchrotron colliders. In his retirement he closely followed the results from the LHC, in particular the search for the Higgs boson. In 1950 Ekspong was working with Cecil Powell’s group in Bristol, UK, which had become a world-leading centre for cosmic-ray emulsion work. In a brilliant experiment with Hooper and King he identified the decay π0 → γγ. By observing e+e– pairs from the conversion of the photons close to cosmic-ray interactions, it was possible to determine the mass of the π0 and set an upper limit for its lifetime. Ekspong obtained his doctorate at Uppsala University, Sweden, in 1955, and immediately took up a postdoc position in Emilio Segré’s group at Berkeley where he was involved in the discovery of the antiproton at the Bevatron. Scanning emulsions one evening, he found the first evidence for an annihilation interaction in an emulsion, and on the 50th anniversary of the discovery of the antiproton he was invited to Berkeley to talk about the discovery. Ekspong was appointed to the first chair in particle physics in Sweden, at Stockholm University, in 1960. There he founded a large particle-physics group that over the years made important contributions to many experiments with data mostly from CERN. He strongly supported the use of CERN, where he was a member and chair of the Emulsion Committee in the early 1960s and a member of the Scientific Policy Committee from 1969 to 1975. He was Swedish delegate to CERN Council for many years and was a catalyst for the development of Swedish particle physics. He was elected to the Royal Swedish Academy of Sciences in 1969 and was a member of its Nobel Committee for physics from 1975 to 1988, chairing the committee from 1987 to 1988. His deep knowledge of statistics allowed Ekspong to clarify general features of high-energy interactions. Data from CERN’s Proton Synchrotron and bubble chambers had suggested that the multiplicity distributions of charged particles obeyed so-called “KNO” scaling, but this relationship was found not to be valid in later collider data recorded at higher energies with the UA5 experiment. In a discovery reported and discussed by him at many conferences, Ekspong showed that the distributions instead followed a negative binomial distribution. In the early studies of physics possibilities at the planned LEP collider, Ekspong also made a convincing contribution to the search strategy for observing the Higgs boson by carefully examining the experimental mass resolution. This strategy was later employed by the LEP experiments to exclude the Higgs mass up to about 115 GeV. He also took part in the technical development of one of the LEP experiments, DELPHI. Gösta Ekspong inspired many with his lectures, discussions, and stories about Nobel-prize discoveries. In many articles in Swedish he made physics available and understandable for the general public. Gareth Hughes joined the high-energy physics group at Lancaster University in 1970, following his undergraduate and postgraduate studies at Oxford University. He was born in Wales and was a proud supporter of the Welsh Rugby Union team, although he had never played the game. He used to say that he was among the few Welshmen who never played rugby, who could not sing and who did not like leeks. Ironically, he died on the feast day of St David, the patron saint of Wales. Following his appointment in Lancaster, Gareth played a central role in the work of the Manchester–Lancaster experiment (dubbed “Mancaster”) at Daresbury Laboratory to study the electro-production of nucleon resonances (by which the components of the nucleon are converted to more highly energetic states). He subsequently went on to work on the JADE experiment at DESY, the ALEPH and then ATLAS experiments at CERN – all of which have been key in establishing the Standard Model of particle physics. Gareth’s main strength was computing. In the 1990s, as well as being a member of the CERN Central Computing Committee, he was chairman of the committee that produced the policy on computing for UK particle physics. This was a very rapidly changing field at the time but a subject in which Gareth’s insight and guidance was to prove invaluable. He was also a prominent member of the Particle Physics Grants Committee and other bodies that manage funding for UK particle physics. He was an excellent teacher, his gentle sense of humour and infinite patience making him a much sought after member of staff by both undergraduate and postgraduate students. He eventually became director of undergraduate courses within the physics department at Lancaster. Gareth’s quick grasp of a situation and clear insight made him an extremely valuable colleague with whom to discuss problems. He was widely known and, in turn, seemed to know everyone. This proved to be a great help on numerous occasions. He retired from the physics department in 2007 but continued his involvement with the ATLAS experiment as an emeritus staff member until his death following a short illness. He will be sorely missed by us all but especially by his wife Jane, daughter Siân and son Owain, and his four grandchildren. Thomas Massam received his undergraduate degree in physics in 1956 at the Chadwick Laboratory, Cambridge, and his PhD at the University of Liverpool in 1960. Jovial but very serious and tireless at work, Tom devoted his life to experimental-physics research and to his family. I had the privilege of meeting Tom at the Fermi Summer School of Physics in Varenna, Italy, in 1962. The topics discussed at the school were the results of the Blackett group on the unexpected V particles, later called “strange” by Gell-Mann, and the effects of “virtual physics” in properties of the elementary particles and the experimental-plus-theoretical research needed. Tom was the most active student of the school, and soon afterwards he joined my group at Bologna University and remained there until his retirement in 2002. Together we performed experiments in all of the important laboratories in Europe, including CERN, DESY, ADONE and Gran Sasso. Tom had an extraordinary intelligence, work capacity and “scientific fidelity”. He is also one of the founders of the Ettore Majorana International Centre for Scientific Culture, established at CERN in the early 1960s with its headquarters in Erice, Sicily. In 1972, Tom initiated an International School of Theory Application of Computers. Tom played a major role, contributing with his extraordinary experimental talents, in experiments that established evidence for the Standard Model during the 1960s and afterwards. He helped to set up the first large-scale non-bubble-chamber facility at CERN, and was a close collaborator in our adoption of electromagnetic calorimeters as a tool to separate leptons from hadrons to allow searches for new particle states. Together, we started the first heavy-lepton search and developed a new technology to measure the time-of-flight of particles with a very high precision, leading to the first experimental observation of anti-deuteron production. Tom, research director in the INFN unit of Bologna, was also giving regular physics courses to the students at the ISSP International School of Subnuclear Physics in Erice, established in 1963. Tom is no longer with us. On 1 December 2016 he left his beloved family, Veronica with three children Peter, Steven, Paul, and his friends and colleagues with the unforgettable memory of his extraordinary life. Arthur H Rosenfeld, a long-time member of the faculty at the University of California, Berkeley, and distinguished senior scientist at the Lawrence Berkeley National Laboratory, passed away in Berkeley on 27 January at the age of 90. A student of Enrico Fermi, he was a leading participant in the revolutionary advances in particle physics in the 1950s and 1960s before striking out in a new direction, where he became legendary. A fitting tribute to Art was the award in 2006 of the Enrico Fermi Award of the US Department of Energy “for a lifetime of achievements ranging from pioneering scientific discoveries in experimental nuclear and particle physics to innovations in science, technology, and public policy for energy conservation that continue to benefit humanity. His vision not only underpins national policy but has helped launch an industry in energy efficiency”. Art’s first impact on the physics community was with Jay Orear and Robert Schluter, when the three of them produced the book Nuclear Physics consisting of the notes from Fermi’s course at the University of Chicago. Art came to Berkeley from Chicago and was part of Luis Alvarez’s team, which used bubble chambers to discover many of the meson and baryon resonances, including the omega meson and the Σ*(1385), which led to the recognition of SU(3) flavour symmetry. Art co-authored papers not only with experimenters, but also with Murray Gell-Mann, Shelly Glashow, and Sam Treiman. The 1957 Annual Review of Nuclear Science paper with Gell-Mann, “Hyperons and Heavy Mesons (Systematics and Decay)”, was the beginning of the Particle Data Group. Today’s Particle Data Group and the Review of Particle Physics are, 60 years later, Art’s legacy to the physics community. Much greater still is Art’s legacy to the US and international communities, which benefit today from his relentless pursuit of increased efficiency in the use of energy through both technological advances and political advocacy. The oil embargo of 1973 led Art to wonder why he saw so many obviously wasteful practices in the use of energy. He devoted the rest of his career to rectifying this. That per-capita usage of energy in California remained essentially constant from 1973 to 2006, while it rose by 50% elsewhere in the US, was given the name “The Rosenfeld Effect,” because of Art’s success in getting the state to adopt policies encouraging efficient use of energy. Art, together with a number of nuclear and particle physicists, and with the backing of Andrew Sessler, the director of the Lawrence Berkeley Laboratory in the mid-1970s, developed programmes in energy efficiency for buildings, appliances and lighting, which became a major part of the Laboratory’s programme. Art’s efforts extended beyond the laboratory. He was a founder of the American Council for an Energy-Efficient Economy, a non-profit organisation that continues today to push for policies that increase energy efficiency. Art served in the Clinton administration from 1994 to 1999 as senior adviser to the DOE’s assistant secretary for energy efficiency and renewable energy, and subsequently as commissioner at the California Energy Commission under two state administrations. Among the numerous honours Art received was the National Medal of Science and of Technology and Innovation presented by president Barack Obama in 2011 for “extraordinary leadership in the development of energy-efficient building technologies and related standards and policies”. Art showed that the analytical skills and pragmatism the physics community values could be put to use on practical problems facing humanity. The result of his dedication was profound and lasting contributions to energy efficiency. Despite Art’s ever growing fame, he remained an unassuming colleague, and we remember him as a friend whose achievements transcended the scope of our ordinary research endeavours. Durga Prasad Roy, or DP as he was popularly known, passed away on 17 March in Cuttack, India, after a brief illness. He was active until his last days, having posted a review on the arXiv preprint server in August 2016, participated in conferences in 2017 and having given a series of lectures on the Standard Model at the University of Hyderabad just a few days before he fell ill. DP completed his PhD in particle physics in 1966 at the Tata Institute of Fundamental Research (TIFR), Mumbai, and was a postdoctoral fellow at the University of California (1966–1968), CERN (1968–1969) and the University of Toronto (1969–1970). He moved to the Rutherford Laboratory in the UK (1970–1974), and was a reader at Visva Bharati University, India, from 1974 to 1976. He joined TIFR in 1976 and retired 30 years later in 2006. He then became a member of the Homi Bhabha Centre of Science Education. Scientifically, DP had an instinct for recognising what is important. He made pioneering contributions in particle- and astroparticle-physics phenomenology. His early research work was in the area of “Regge phenomenology and duality”, which addresses the dominant part of cross-sections for hadron–hadron collision processes. Using these ideas, DP predicted exotic mesons called baryonium (now termed tetraquarks) as well as exotic pentaquark baryons – robust predictions that continue to attract the attention of experimentalists and lattice-QCD experts. Along with his collaborators, he suggested to look for a hard isolated lepton and jets as a signature of the top quark, a methodology widely adopted at the CERN and Tevatron proton–antiproton colliders. He also worked extensively on many popular theories of physics beyond the Standard Model, such as supersymmetry. He suggested a promising signature with which to search for charged Higgs bosons using tau decays and the distinctive polarisation of these particles, which is currently being used in the ongoing search for charged Higgs boson at the LHC. Likewise, the missing transverse-momentum signature for supersymmetric particles suggested by DP is being widely used in the ongoing collider searches for these particles. DP and collaborators, and other groups, employed global fits of the solar-neutrino data, including the SNO neutral-current data from 2002, to pin down the large-mixing-angle (LMA) Mikheyev–Smiron–Wolfenstein (MSW) solution to the solar-neutrino problem. This was tested by two impressive sets of neutrino-spectrum results published by the KamLAND experiment in 2003 and 2004. Incorporating these data further in their analysis, and focussing on the LMA–MSW solution in the two-neutrino framework, DP and collaborators ruled out the high-mass-squared-difference LMA solution by more than three standard deviations and converged on the low-mass-squared difference LMA as the unique solution. His scientific achievements were recognised by the Meghnad Saha Award and the SN Bose Medal. He was elected fellow of the Indian Academy of Sciences, Indian National Science Academy and National Academy of Sciences. Along with his colleague Probir Roy, DP started a series of workshops in high-energy physics phenomenology called WHEPP that still initiate a lot of collaborative work today. He was passionate about undergraduate teaching, but also had many interests outside science. He was a weightlifting champion of Orissa, an expert swimmer, and a connoisseur of Indian classical music and dance. His passion for adventure always showed up in the after-work evening activities at WHEPP workshops. He also had strong views on the lack of experimental investigations in ancient India, and published them in an article in the Indian Journal of History of Science in 2016.

News Article | May 19, 2017
Site: cerncourier.com

On 4 April, CERN alumnus Tim Berners-Lee received the 2016 A M Turing Award for his invention of the World Wide Web, the first web browser, and the fundamental protocols and algorithms allowing the web to scale. Named in honour of British mathematician and computer scientist Alan Turing, and often referred to as the Nobel prize of computing, the annual award of $1 million is given by the Association for Computing Machinery. In 1989, while working at CERN, Berners-Lee wrote a proposal for a new information-management system for the laboratory, and by the end of the following year he had invented one of the most influential computing innovations in history – the World Wide Web. Berners-Lee is now a professor at Massachusetts Institute of Technology and the University of Oxford, and director of the World Wide Web Consortium and the World Wide Web Foundation. The International Centre for Theoretical Physics 2016 Dirac Medal has been awarded to Nathan Seiberg of the Institute for Advanced Study in Princeton, and Mikhail Shifman and Arkady Vainshtein of the University of Minnesota. The award recognises the trio’s important contributions to field theories in the non-perturbative regime and in particular for exact results obtained in supersymmetric field theories. The second edition of the Guido Altarelli Award, given to young scientists in the field of deep inelastic scattering and related subjects, was awarded to two researchers during the 2017 Deep Inelastic Scattering workshop held in Birmingham, UK, on 3 April. Maria Ubiali of Cambridge University in the UK was recognised for her theoretical contributions in the field of proton parton density functions, and in particular for her seminal contributions to the understanding of heavy-quark dynamics. Experimentalist Paolo Gunnellini of DESY, who is a member of the CMS collaboration, received the award for his innovative ideas in the study of double parton scattering and in Monte Carlo tuning. Four members of the IceCube neutrino observatory, based at the South Pole, have independently won awards recognising their contributions to the field. Aya Ishihara of Chiba University in Japan was awarded the 37th annual Saruhashi Prize, given each year to a female scientist under the age of 50 for exceptional research accomplishments. This year’s prize, presented in Tokyo on 27 May, cites Ishihara’s contributions to high-energy astronomy with the IceCube detector. Fellow IceCube collaborator Subir Sarkar of the University of Oxford, UK, and the Niels Bohr Institute in Denmark has won the 4th Homi Bhabha prize. Awarded since 2010 by the Tata Institute of Fundamental Research (TIFR) in India and the International Union of Pure and Applied Physics, the prize recognises an active scientist who has made distinguished contributions in the field of high-energy cosmic-ray and astroparticle physics over an extended academic career. Sarkar has also worked on the Pierre Auger Observatory and is a member of the Cherenkov Telescope Array collaboration. Meanwhile, former IceCube spokesperson Christian Spiering from DESY has won the O’Ceallaigh Medal for astroparticle physics, awarded every second year by the Dublin Institute for Advanced Studies. Spiering, who led the collaboration from 2005 to 2007 and also played a key role in the Lake Baikal Neutrino Telescope, was honoured “for his outstanding contributions to cosmic-ray physics and to the newly emerging field of neutrino astronomy in particular”. Both he and Sarkar will receive their awards at the 35th International Cosmic Ray Conference in Busan, South Korea, on 13 July. Finally, IceCube member Ben Jones of the University of Texas at Arlington has won the APS 2017 Mitsuyoshi Tanaka Dissertation Award in Experimental Particle Physics, for his thesis “Sterile Neutrinos in Cold Climates”. An awards ceremony took place at CERN on 3 April recognising companies that have won contracts to start building the prototype phase of the Helix Nebula Science Cloud (HNSciCloud). Initiated by CERN in 2016, HNSciCloud is a €5.3 million pre-commercial procurement tender driven by 10 leading research organisations and funded by the European Commission. Its aim is to establish a European cloud platform to support high-performance computing and big-data capabilities for scientific research. The April event marked the official beginning of the prototype phase, which covers the procurement of R&D services for the design, prototype development and pilot use of innovative cloud services. The three winning consortia are: T-Systems, Huawei, Cyfronet and Divia; IBM; and RHEA Group, T-Systems, Exoscale and SixSq. Each presented its plans to build the HNSciCloud prototype and the first deliverables are expected by the end of the year, after which two consortia will proceed to the pilot phase in 2018. The CERN Accelerator School (CAS) organised a specialised course devoted to beam injection, extraction and transfer in Erice, Sicily, from 10 to 19 March. The course was held in the Ettore Majorana Foundation and Centre, and was attended by 72 participants from 25 countries including China, Iran, Russia and the US. The intensive programme comprised 32 lectures and two seminars, with 10 hours of case studies allowing students to apply their knowledge to real problems. Following introductory talks on electromagnetism, relativity and the basics of beam dynamics, different injection and extraction schemes were presented. Detailed lectures about the special magnetic and electrostatic elements for the case of lepton and hadron beams followed. State-of-the-art kicker and septa designs were discussed, as were issues related to stripping-injection and resonant extraction as used in medical settings. An overview of optics measurements in storage rings and non-periodic structures completed the programme, with talks about the production of secondary and radioactive beams and exotic injection methods. The next CAS course, focusing on advanced accelerator physics, will take place at Royal Holloway University in the UK from 3–15 September. Later in the year, CAS is participating in a joint venture in collaboration with the accelerator schools of the US, Japan and Russia. This school is devoted to RF technologies and will be held in Japan from 16–26 October. Looking further ahead, schools are currently planned in 2018 on accelerator physics at the introductory level, on future colliders and on beam instrumentation and diagnostics. See https://www.cern.ch/schools/CAS. Around 100 participants from 15 countries attended the 2017 Testing Gravity Conference at the Simon Fraser University, Harbour Centre, in Vancouver, Canada, on 25 to 28 January. The conference, the second such meeting following the success of the 2015 event, brought together experts exploring new ways to test general relativity (GR). GR, and its Newtonian limit, work very well in most circumstances. But gaps in our understanding appear when the theory is applied to extremely small distances, where quantum mechanics reigns, or extremely large distances, when we try to describe the universe. Advancing technologies across all areas of physics open up opportunities for testing gravity in new ways, thus helping to fill these gaps. The conference brought together renowned cosmologists, astrophysicists, and atomic, nuclear and particle physicists to share their specific approaches to test GR and to explore ways to address long-standing mysteries, such as the unexplained nature of dark matter and dark energy. Among the actively discussed topics were the breakthrough discovery in February 2016 of gravitational waves by the LIGO observatory, which has opened up exciting opportunities for testing GR in detail (CERN Courier January/February 2017 p34), and the growing interest in gravity tests among the CERN physics community – specifically regarding attempting to measure the gravitational force on antihydrogen with three experiments at CERN’s Antiproton Decelerator (CERN Courier January/February 2017 p39). Among other highlights there were fascinating talks from pioneers in their fields, including cosmologist Misao Sasaki, one of the fathers of inflationary theory; Eric Adelberger, a leader in gravity tests at short distances; and Frans Pretorius, who created the first successful computer simulations of black-hole collisions. This is an exciting time for the field of gravity research. The LIGO–Virgo collaboration is expected to detect many more gravitational-wave events from binary black holes and neutron stars. Meanwhile, a new generation of cosmological probes currently under development, such as Euclid, LSST and SKA, are stimulating theoretical research in their respective domains (CERN Courier May 2017 p19). We are already looking forward to the next Testing Gravity in Vancouver in 2019. On 12 April, CERN hosted the seven-member high-level group of scientific advisers to the European Commission, which provides independent scientific advice on specific policy issues. Led by former CERN Director-General Rolf Heuer, the group toured ATLAS and the AMS Payload Operations Control Centre. On 18 April, Czech minister of health Miloslav Ludvik visited CERN, during which he toured the ALICE experiment and signed the guestbook with head of Member State relations Pippa Wells. Minister for higher education and science in Denmark Søren Pind visited CERN on 25 April, touring the synchrocyclotron, the Antiproton Decelerator, ALICE and ATLAS. Here he is pictured (centre) meeting ATLAS spokesperson Karl Jakobs. Dr Viktoras Pranckietis MP and speaker of the Seimas, Republic of Lithuania, visited CERN on 26 April, taking in CMS, ISOLDE and MEDICIS. He signed the guestbook with senior adviser for Lithuania Tadeusz Kurtyka (left) and director for finance and human resources Martin Steinacher.

Sane S.P.,Tata Institute of Fundamental Research
Current Opinion in Neurobiology | Year: 2016

Miniature insects can be as small as a few hundred micrometres in size, making them among the smallest metazoan animals ever described. Yet, even at these length scales, they display remarkably sophisticated flight behaviours. For flight at such low Reynolds numbers, miniature insects have evolved biomechanical and neural adaptations that push the boundaries of what is possible in the realm of physics and neurobiology of flight. After several decades of relative dormancy, this question has recently been revisited by researchers working in diverse areas ranging from systematics and neurobiology to dispersal behaviours. In this review, I cover recent findings in this area, and point towards the many open questions that still remain unanswered. © 2016 Elsevier Ltd

Jaiswal A.,Tata Institute of Fundamental Research
Physical Review C - Nuclear Physics | Year: 2013

Starting from the Boltzmann equation with the relaxation time approximation for the collision term and using a Chapman-Enskog-like expansion for the distribution function close to equilibrium, we derive hydrodynamic evolution equations for the dissipative quantities directly from their definition. Although the form of the equations is identical to those obtained in traditional Israel-Stewart approaches employing Grad's 14-moment approximation and the second moment of the Boltzmann equation, the coefficients obtained are different. In the case of a one-dimensional scaling expansion, we demonstrate that our results are in better agreement with a numerical solution of the Boltzmann equation as compared to Israel-Stewart results. We also show that including approximate higher-order corrections in viscous evolution significantly improves this agreement, thus justifying the relaxation time approximation for the collision term. © 2013 American Physical Society.

Jaiswal A.,Tata Institute of Fundamental Research
Physical Review C - Nuclear Physics | Year: 2013

We present the derivation of a novel third-order hydrodynamic evolution equation for the shear stress tensor from kinetic theory. The Boltzmann equation with a relaxation time approximation for the collision term is solved iteratively using a Chapman-Enskog-like expansion to obtain the nonequilibrium phase-space distribution function. Subsequently, the evolution equation for the shear stress tensor is derived from its kinetic definition up to third order in gradients. We quantify the significance of the new derivation within a one-dimensional scaling expansion and demonstrate that the results obtained using the third-order viscous equations derived here provides a very good approximation to the exact solution of the Boltzmann equation in a relaxation time approximation. We also show that the time evolution of pressure anisotropy obtained using our equations is in better agreement with transport results than that obtained with an existing third-order calculation based on the second law of thermodynamics. © 2013 American Physical Society.

Krishnan Y.,Tata Institute of Fundamental Research | Simmel F.C.,TU Munich
Angewandte Chemie - International Edition | Year: 2011

In biology, nucleic acids are carriers of molecular information: DNA's base sequence stores and imparts genetic instructions, while RNA's sequence plays the role of a messenger and a regulator of gene expression. As biopolymers, nucleic acids also have exciting physicochemical properties, which can be rationally influenced by the base sequence in myriad ways. Consequently, in recent years nucleic acids have also become important building blocks for bottom-up nanotechnology: as molecules for the self-assembly of molecular nanostructures and also as a material for building machinelike nanodevices. In this Review we will cover the most important developments in this growing field of nucleic acid nanodevices. We also provide an overview of the biochemical and biophysical background of this field and the major "historical" influences that shaped its development. Particular emphasis is laid on DNA molecular motors, molecular robotics, molecular information processing, and applications of nucleic acid nanodevices in biology. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Manoharan P.K.,Tata Institute of Fundamental Research
Astrophysical Journal | Year: 2012

This paper presents an analysis of three-dimensional evolution of solar wind density turbulence and speed at various levels of solar activity between solar cycles 22 and 24. The solar wind data used in this study have been obtained from the interplanetary scintillation (IPS) measurements made at the Ooty Radio Telescope, operating at 327MHz. Results show that (1) on average, there was a downward trend in density turbulence from the maximum of cycle 22 to the deep minimum phase of cycle 23; (2) the scattering diameter of the corona around the Sun shrunk steadily toward the Sun, starting from 2003 to the smallest size at the deepest minimum, and it corresponded to a reduction of 50% in the density turbulence between the maximum and minimum phases of cycle 23; (3) the latitudinal distribution of the solar wind speed was significantly different between the minima of cycles 22 and 23. At the minimum phase of solar cycle 22, when the underlying solar magnetic field was simple and nearly dipole in nature, the high-speed streams were observed from the poles to 30° latitudes in both hemispheres. In contrast, in the long-decay phase of cycle 23, the sources of the high-speed wind at both poles, in accordance with the weak polar fields, occupied narrow latitude belts from poles to 60° latitudes. Moreover, in agreement with the large amplitude of the heliospheric current sheet, the low-speed wind prevailed in the low- and mid-latitude regions of the heliosphere. (4) At the transition phase between cycles 23 and 24, the high levels of density and density turbulence were observed close to the heliospheric equator and the low-speed solar wind extended from the equatorial-to-mid- latitude regions. The above results in comparison with Ulysses and other in situ measurements suggest that the source of the solar wind has changed globally, with the important implication that the supply of mass and energy from the Sun to the interplanetary space has been significantly reduced in the prolonged period of low solar activity. The IPS results are consistent with the onset and growth of the current solar cycle 24, starting from the middle of 2009. However, the width of the high-speed wind at the northern high latitudes has almost disappeared and indicates that the ascending phase of the current cycle has almost reached the maximum phase in the northern hemisphere of the Sun. However, in the southern part of the hemisphere, the solar activity has yet to develop and/or increase. © 2012. The American Astronomical Society. All rights reserved..

Choudhury S.,Tata Institute of Fundamental Research
Nuclear Physics B | Year: 2015

In this paper my prime objective is to explain the generation of large tensor-to-scalar ratio from the single field sub-Planckian inflationary paradigm within Randall-Sundrum (RS) single braneworld scenario in a model independent fashion. By explicit computation I have shown that the effective field theory prescription of brane inflation within RS single brane setup is consistent with sub-Planckian excursion of the inflaton field, which will further generate large value of tensor-to-scalar ratio, provided the energy density for inflaton degrees of freedom is high enough compared to the brane tension in high energy regime. Finally, I have mentioned the stringent theoretical constraint on positive brane tension, cut-off of the quantum gravity scale and bulk cosmological constant to get sub-Planckian field excursion along with large tensor-to-scalar ratio as recently observed by BICEP2 or at least generates the tensor-to-scalar ratio consistent with the upper bound of Planck (2013 and 2015) data and Planck+BICEP2+Keck Array joint constraint. © 2015 The Author.

Ravinder S.,Tata Institute of Fundamental Research
Translational psychiatry | Year: 2013

Selective serotonin reuptake inhibitors (SSRIs) are reported to exacerbate symptoms of anxiety when treatment is initiated. These clinical findings have been extended to animal models wherein SSRIs also potentiate anxiety and fear learning, which depend on the amygdala. Yet, little is known about the role of specific amygdalar circuits in these acute effects of SSRIs. Here, we first confirmed that a single injection of fluoxetine 1 h before auditory fear conditioning potentiated fear memory in rats. To probe the neural substrates underlying this enhancement, we analyzed the expression patterns of the immediate early gene, Arc (activity-regulated cytoskeleton-associated protein). Consistent with previous reports, fear conditioning induced Arc protein expression in the lateral and basal amygdala. However, this was not enhanced further by pre-treatment with fluoxetine. Instead, fluoxetine significantly enhanced expression of Arc in the central amygdala (CeA) and the bed nucleus of the stria terminalis (BNST). Next, we tested whether direct targeted infusions of fluoxetine into the CeA, or BNST, leads to the same fear-potentiating effect. Strikingly, direct infusion of fluoxetine into the BNST, but not the CeA, was sufficient to enhance fear memory. Moreover, this behavioral effect was also accompanied by robust Arc expression in the CeA, similar to the systemic injection. Our results identify a novel role for the BNST in the acute fear-enhancing effects of SSRIs. These findings highlight the need to look beyond the traditional focus on input nuclei of the amygdala and add to accumulating evidence implicating these microcircuits in gating fear and anxiety.

The present invention discloses a method for securing information flow in an information system. The method comprises intercepting access requests to information in the information system by all applications running in the information system, intuitively assigning labels to all the information and the applications depending on the application requirements, combining the application making the access request and the information for which the access request is made with their respective labels, checking allowance of the access request based on comparison of the label corresponding to the application making the access request and the label corresponding to the information for which the access request is made and accordingly providing access of the information to the application on detection of allowable access request else denying the access request.

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