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.

Fine structure and primary sensory projections of sensilla on the maxillary palp of Drosophila melanogaster Meigen (Diptera : Drosophilidae)

Abstract: Three types of hairs were identified on the maxillary palp of Drosophila melanogaster Meigen (Diptera : Drosophilidae): (i) single-walled, multiporous sensilla basiconica, which constitute 75% of the innervated hairs; (ii) thick walled non-porous sensilla trichodea, which make up the remaining 25% of the innervated hairs; and (iii) numerous spinules, which are un-innervated. These sensilla basiconica uniformly contain 2 bipolar sense cells, whereas sensilla trichodea have a single dendrite with a tubular body at the base of each hair. A majority of the sensilla basiconica is located on the distal half of the dorsal surface, whereas sensilla trichodea are positioned on the tip and entire ventrolateral ridge of the palp. Approximately 125 axons of the sense cells join to form a single nerve. The structure of sensilla basiconica and sensilla trichodea suggests that they are olfactory and mechanosensory respectively. The contact chemoreceptors (gustatory sensilla) are conspicuously absent on the maxillary palp. Golgi silver impregnations and cobalt fills show that the primary sensory fibres from sensilla trichodea and sensilla basiconica on the maxillary palp project in the posterior suboesophageal ganglion (SOG) and the antennal lobe respectively. A single fibre projects separately either in the SOG or in the antennal lobe. In the antennal lobe, the input received from sensilla basiconica is usually bilateral and at least 5 glomeruli are innervated symmetrically on either side from both the palps. This study suggests that the sensory neurons are capable of making selective projections in the specific regions of the brain. Accordingly, the fibres from a sensillum project to the brain with respect to their functions and the individual glomeruli represent functional units of the brain, receiving inputs in a characteristic combination.

A polarized fast radio burst at low Galactic latitude

Abstract: We report on the discovery of a new fast radio burst (FRB), FRB 150215, with the Parkes radio telescope on 2015 February 15. The burst was detected in real time with a dispersion measure (DM) of 1105.6 +/‐ 0.8 pc cm(‐3), a pulse duration of 2.8(‐0.5)(+1.2) ms, and a measured peak flux density assuming that the burst was at beam centre of 0.7(‐0.1)(+0.2) Jy. The FRB originated at a Galactic longitude and latitude of 24.66 degrees, 5.28 degrees and 25 degrees away from the Galactic Center. The burst was found to be 43 +/‐ 5 per cent linearly polarized with a rotation measure (RM) in the range ‐9 < RM < 12 rad m(‐2) (95 per cent confidence level), consistent with zero. The burst was followed up with 11 telescopes to search for radio, optical, X‐ray, gamma‐ray and neutrino emission. Neither transient nor variable emission was found to be associated with the burst and no repeat pulses have been observed in 17.25 h of observing. The sightline to the burst is close to the Galactic plane and the observed physical properties of FRB 150215 demonstrate the existence of sight lines of anomalously low RM for a given electron column density. The Galactic RM foreground may approach a null value due to magnetic field reversals along the line of sight, a decreased total electron column density from the Milky Way, or some combination of these effects. A lower Galactic DM contribution might explain why this burst was detectable whereas previous searches at low latitude have had lower detection rates than those out of the plane.

Spin-polarized tunneling in the half-metallic ferromagnets La 0.7-x Ho x Sr 0.3 MnO 3 (x=0 and 0.15): Experiment and theory

Abstract: The magnetoresistance (MR) in polycrystalline colossal magnetoresistive compounds follows a behavior different from single crystals below the ferromagnetic transition temperature. This difference is usually attributed to spin-polarized tunneling at the grain boundaries of the polycrystalline sample. Here we derive a theoretical expression for the contribution of spin-polarized tunneling to the magnetoresistance in granular ferromagnetic systems under the mean-field approximation. We apply this model to our experimental data on two half-metallic ferromagnets, ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ and ${\mathrm{La}}_{0.55}{\mathrm{Ho}}_{0.15}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$ in the temperature range 5--300 K. We find that the theoretical predictions agree quite well with the observed dependence of the spin polarized MR on the spontaneous magnetization. We discuss the significance of our results in the light of the recent finding by A. Biswas et al. [Phys. Rev. B 59, 5368 (1999)] regarding the evolution of the total density of states at the Fermi level as a function of temperature in colossal magnetoresistive materials.

Measurement of e+e- →π+π-ψ (2S) via initial state radiation at Belle

Abstract: We report measurement of the cross section of e(+)e(-) -> pi(+)pi(-)psi(2S) between 4.0 and 5.5 GeV, based on an analysis of initial state radiation events in a 980 fb(-1) data sample recorded with the Belle detector. The properties of the Y(4360) and Y(4660) states are determined. Fitting the mass spectrum of pi(+)pi(-)psi(2S) with two coherent Breit-Wigner functions, we find two solutions with identical mass and width but different couplings to electron-positron pairs: M-Y(4360) = (4347 +/- 6 +/- 3) MeV/c(2), Gamma(Y(4360)) = (103 +/- 9 +/- 5) MeV, M-Y(4660) = (4652 +/- 10 +/- 8) MeV/c(2), Gamma(Y(4660)) = (68 +/- 11 +/- 1) MeV; and B[Y(4360) -> pi(+)pi(-)psi(2S)] . Gamma(e+e-)(Y(4360)) = (10.9 +/- 0.6 +/- 0.7) eV and B[Y(4660) -> pi(+)pi(-)psi(2S)] . Gamma(e+e-)(Y(4660)) = (8.1 +/- 1.1 +/- 0.5) eV for one solution; or B[Y(4360) -> pi(+)pi(-)psi(2S)] . Gamma(e+e-)(Y(4360)) = (9.2 +/- 0.6 +/- 0.6) eV and B[Y(4660) -> pi(+)pi(-)psi(2S)] . Gamma(e+e-)(Y(4660)) = (2.0 +/- 0.3 +/- 0.2) eV for the other. Here, the first errors are statistical and the second systematic. Evidence for a charged charmoniumlike structure at 4.05 GeV/c(2) is observed in the pi(+/-)psi(2S) intermediate state in the Y(4360) decays.

Homogenization of elliptic eigenvalue problems: Part 1

Abstract: The aim of this paper is to study the homogenization of elliptic eigenvalue problems, with a second order homogeneous Dirichlet problem as an example. The main homogenization theorem states that the same operator which serves to homogenize the corresponding static problem works for the eigenvalue problem as well and that the structure of eigenvalues and eigenvectors is in some sense preserved. Formulae for first and second order correctors for eigenvalues are proposed and error estimates are obtained. These results are applied to the case of coefficients with a periodic structure and a simple numerical example is presented. Extensions to other types of boundary conditions and to higher order equations are indicated.