Tata Institute of Fundamental Research

About: Tata Institute of Fundamental Research is a education organization based out in Mumbai, Maharashtra, India. It is known for research contribution in the topics: Magnetization & Large Hadron Collider. The organization has 7786 authors who have published 21742 publications receiving 622368 citations. The organization is also known as: TIFR.

Hairy black holes and solitons in global AdS5

Abstract: We use a mix of analytic and numerical methods to exhaustively study a class of asymptotically global AdS solitons and hairy black hole solutions in negative cosmological constant Einstein Maxwell gravity coupled to a charged massless scalar field. Our results depend sensitively on the charge e of the scalar field. The solitonic branch of solutions we study hits the Chandrashekhar limit at finite mass at small e, but extends to arbitrarily large mass at larger e. At low values of e no hairy black holes exist. At intermediate values of e hairy black holes exist above a critical charge. At large e hairy black holes exist at all values of the charge. The lowest mass hairy black hole is a smooth zero entropy soliton at small charge, but a (probably) singular nonzero entropy hairy black hole at larger charge. In a phase diagram of solutions, the hairy black holes merge with the familiar Reissner-Nordstrom−AdS black holes along a curve that is determined by the onset of the superradiant instability in the latter family.

The magnetic susceptibility, specific heat and dielectric constant of hexagonal YMnO3, LuMnO3 and ScMnO3

Abstract: We report the magnetic susceptibility, specific heat and dielectric constant for high-purity polycrystalline samples of three hexagonal manganites: YMnO3, LuMnO3 and ScMnO3. These materials can exhibit a ferroelectric transition at very high temperatures (TFE>700 K). At lower temperatures there is magnetic ordering of the frustrated Mn3+ spins (S = 2) on a triangular Mn lattice (YMnO3: TN = 71 K; LuMnO3: TN = 90 K and ScMnO3: TN = 130 K). The transition is characterized by a sharp kink in the magnetic susceptibility at TN below which it continues to increase due to the frustration on the triangular lattice. The specific heat shows one clear continuous phase transition at TN, which is independent of external magnetic field up to 9 T with an entropy content as expected for Mn3+ ions. The temperature-dependent dielectric constant displays a distinct anomaly at TN.

Evidence for Large-Scale Solar Magnetic Reconnection from Radio and X-Ray Measurements

Abstract: Utilizing Yohkoh Soft X-ray Telescope and Nancay radioheliograph data, we present, for the first time, observations of expanding twisted X-ray loops and a series of nonthermal radio bursts that follow the loop expansion in time and space up to ∼12′ distance. The loops were produced during a long-duration C4.7 flare close to disk center on 1994 October 25 at 1049 UT. The series of radio bursts were observed on the southern hemisphere above a weak positive-polarity region. The Kitt Peak magnetogram shows the existence of a weak negative-polarity region on the northern hemisphere at the same heliolongitude. Simultaneously with the nonthermal radio bursts, we observed the appearance of two remote X-ray brightenings and subsequent formation of two coronal holes above these weak (quiet) magnetic regions of opposite polarity, which strongly suggest the involvement of these remote regions in the event. During the 6 hr-long gradual phase of the flare, new X-ray loop connections developed among the active region and the remote quiet regions. A nonthermal radio continuum emission originating from the active region was also observed. We propose that the series of radio bursts, two remote X-ray brightenings, and new coronal loop connections were all signatures of a large-scale reconnection process between the expanding twisted flare loops and overlying transequatorial loops connecting quiet-Sun regions. The reconnection was only partial; the external part of the overlying large-scale fields were pushed out in the solar wind by the expanding twisted loops, leading to the formation of the coronal holes. The interaction between the active region and the large-scale fields seemed to be active during the entire gradual phase of the flare. This scenario may also explain the measurement of high-energy electrons in the interplanetary medium from 74° south heliolatitude as observed by Ulysses. © 1996. The American Astronomical Society. All rights reserved.

Raman Tweezers Spectroscopy of Live, Single Red and White Blood Cells

Abstract: An optical trap has been combined with a Raman spectrometer to make high-resolution measurements of Raman spectra of optically-immobilized, single, live red (RBC) and white blood cells (WBC) under physiological conditions. Tightly-focused, near infrared wavelength light (1064 nm) is utilized for trapping of single cells and 785 nm light is used for Raman excitation at low levels of incident power (few mW). Raman spectra of RBC recorded using this high-sensitivity, dual-wavelength apparatus has enabled identification of several additional lines; the hitherto-unreported lines originate purely from hemoglobin molecules. Raman spectra of single granulocytes and lymphocytes are interpreted on the basis of standard protein and nucleic acid vibrational spectroscopy data. The richness of the measured spectrum illustrates that Raman studies of live cells in suspension are more informative than conventional micro-Raman studies where the cells are chemically bound to a glass cover slip.