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.
Vaze R.,Tata Institute of Fundamental Research
IEEE Transactions on Wireless Communications | Year: 2011
Delay-reliability (D-R), and throughput-delay-reliability (T-D-R) tradeoffs in an ad hoc network are derived for single hop and multi-hop transmission with automatic repeat request (ARQ) on each hop. The delay constraint is modeled by assuming that each packet is allowed at most D retransmissions end-to-end, and the reliability is defined as the probability that the packet is successfully decoded in at most D retransmissions. The throughput of the ad hoc network is characterized by the transmission capacity, where the transmission capacity is defined to be the maximum density of spatial transmissions that can be simultaneously supported in an ad hoc network under quality of service (QoS) constraints (maximum retransmissions and reliability). The transmission capacity captures the T-D-R tradeoff as it incorporates the dependence between the throughput, the maximum delay, and the reliability. Given an end-to-end retransmission constraint of D, the optimal allocation of the number of retransmissions allowed at each hop is derived that maximizes a lower bound on the transmission capacity. Optimizing over the number of hops, single hop transmission is shown to be optimal for maximizing a lower bound on the transmission capacity in the sparse network regime. © 2011 IEEE.
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..
Muliyil S.,Tata Institute of Fundamental Research |
Narasimha M.,Tata Institute of Fundamental Research
Developmental Cell | Year: 2014
How cues that trigger the wound response result in tissue healing is a question of immense biological and medical importance. Here we uncover roles for mitochondrial reactive oxygen species (mtROS) during Drosophila dorsal closure, a model for wound healing. By using real-time visualization of ROS activity and single-cell perturbation strategies, we demonstrate that stochasticities in ROS generation in the amnioserosa are necessary and sufficient to trigger cell delamination. We identify dose-dependent effects of mtROS on actomyosin and mitochondrial architecture, dynamics, and activity that mediate both stochasticities in cell behavior and the phases of tissue dynamics accompanying dorsal closure. Our results establish that ROS levels tune cell behavior and tissue dynamics qualitatively and quantitatively. They identify a pathway triggered by ROS and mediated by the Rho effector ROCK and its substrates that influences tissue patterning and homeostasis through the coordinate regulation of both mitochondrial morphology and tissue tension. © 2014 Elsevier Inc.
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.
Udgaonkar J.B.,Tata Institute of Fundamental Research
Archives of Biochemistry and Biophysics | Year: 2013
Polypeptide chain collapse is an integral component of a protein folding reaction. In this review, experimental characterization of the interplay of polypeptide chain collapse, secondary structure formation, consolidation of the hydrophobic core and the development of tertiary interactions, is scrutinized. In particular, the polypeptide chain collapse reaction is examined in the context of the three phenomenological models of protein folding - the hydrophobic collapse model, the framework model and the nucleation condensation model - which describe different ways by which polypeptide chains are able to fold in biologically relevant time-scales. © 2012 Elsevier Inc. All rights reserved.
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.
Tata Institute of Fundamental Research | Date: 2015-06-08
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.