Solar Coronal Density Turbulence and Magnetic Field Strength at the Source Regions of Two Successive Metric Type II Radio Bursts

We report spectral and polarimeter observations of two weak, low-frequency (≈85–60 MHz) solar coronal type II radio bursts that occurred on 2020 May 29 within a time interval ≈2 minutes. The bursts had fine structures, and were due to harmonic plasma emission. Our analysis indicates that the magnetohydrodynamic shocks responsible for the first and second type II bursts were generated by the leading edge (LE) of an extreme-ultraviolet flux rope/coronal mass ejection (CME) and interaction of its flank with a neighboring coronal structure, respectively. The CME deflected from the radial direction by ≈25° during propagation in the near-Sun corona. The estimated power spectral density and magnetic field strength (B) near the location of the first burst at heliocentric distance r ≈ 1.35 Re are ≈2 × 10−3 W2m and ≈1.8 G, respectively. The corresponding values for the second burst at the same r are ≈10−3 W2 m and ≈0.9 G. The significant spatial scales of the coronal turbulence at the location of the two type II bursts are ≈62–1 Mm. Our conclusions from the present work are that the turbulence and magnetic field strength in the coronal region near the CME LE are higher compared to the corresponding values close to its flank. The derived estimates of the two parameters correspond to the same r for both the CME LE and its flank, with a delay of ≈2 minutes for the latter.Peer reviewe

Low-Frequency Radio Observations of the "Quiet" Corona During the Descending Phase of Sunspot Cycle 24

We carried out a statistical study of the "quiet" solar corona during the descending phase of the Sunspot Cycle 24 (i.e., January 2015 to May 2019) using data obtained with the Gauribidanur RAdioheliograPH (GRAPH) at 53 and 80 MHz simultaneously. Our results show that the equatorial (east-west) diameters of the solar corona at the above two frequencies shrunk steadily. The decrease was found to be due to a gradual reduction in the coronal electron density (N-e). Independent estimates ofN(e)in the equatorial region of the "background" corona using white-light coronagraph observations indicate a decline consistent with our findings.Peer reviewe

A research in sustainable competitive positional advantage of english dailies in Tamilnadu (India)

The aim of this study is to identify and to describe the sustainable competitive positional advantage of various English Dailies in Tamilnadu (India) in general. Cost leaderships (price) and the differentiations based on demographics, psychographics, reading activity, opinion and interest are particularly considered. In order to reach this scope a theory of sustainable competitive positional advantage is proposed, in the context of print media in India

Simple ruthenium-catalyzed reductive amination enables the synthesis of a broad range of primary amines

The production of primary benzylic and aliphatic amines, which represent essential feedstocks and key intermediates for valuable chemicals, life science molecules and materials, is of central importance. Here, we report the synthesis of this class of amines starting from carbonyl compounds and ammonia by Ru-catalyzed reductive amination using H2. Key to success for this synthesis is the use of a simple RuCl2(PPh3)3 catalyst that empowers the synthesis of >90 various linear and branched benzylic, heterocyclic, and aliphatic amines under industrially viable and scalable conditions. Applying this catalyst, −NH2 moiety has been introduced in functionalized and structurally diverse compounds, steroid derivatives and pharmaceuticals. Noteworthy, the synthetic utility of this Ru-catalyzed amination protocol has been demonstrated by upscaling the reactions up to 10 gram-scale syntheses. Furthermore, in situ NMR studies were performed for the identification of active catalytic species. Based on these studies a mechanism for Ru-catalyzed reductive amination is proposed

A structural and biochemical model of processive chitin synthesis

Chitin synthases (CHS) produce chitin, an essential component of the fungal cell wall. The molecular mechanism of processive chitin synthesis is not understood, limiting the discovery of new inhibitors of this enzyme class. We identified the bacterial glycosyltransferase NodC as an appropriate model system to study the general structure and reaction mechanism of CHS. A high throughput screening-compatible novel assay demonstrates that a known inhibitor of fungal CHS also inhibit NodC. A structural model of NodC, on the basis of the recently published BcsA cellulose synthase structure, enabled probing of the catalytic mechanism by mutagenesis, demonstrating the essential roles of the DD and QXXRW catalytic motifs. The NodC membrane topology was mapped, validating the structural model. Together, these approaches give insight into the CHS structure and mechanism and provide a platform for the discovery of inhibitors for this antifungal target

Tests & Calibration on Ultra Violet Imaging Telescope (UVIT)

Ultra Violet Imaging Telescope on ASTROSAT Satellite mission is a suite of Far Ultra Violet (FUV; 130 to 180 nm), Near Ultra Violet (NUV; 200 to 300 nm) and Visible band (VIS; 320 to 550nm) imagers. ASTROSAT is a first multi wavelength mission of INDIA. UVIT will image the selected regions of the sky simultaneously in three channels & observe young stars, galaxies, bright UV Sources. FOV in each of the 3 channels is about 28 arc-minute. Targeted angular resolution in the resulting UV images is better than 1.8 arc-second (better than 2.0 arc-second for the visible channel). Two identical co-aligned telescopes (T1, T2) of Ritchey-Chretien configuration (Primary mirror of 375 mm diameter) collect the celestial radiation and feed to the detector system via a selectable filter on a filter wheel mechanism; gratings are available in the filter wheels of FUV and NUV channels for slit-less low resolution spectroscopy. The detector system for each of the 3 channels is generically identical. One telescope images in the FUV channel, and other images in NUV and VIS channels. One time open-able mechanical cover on each telescope also works as Sun-shield after deployment.We will present the optical tests and calibrations done on the two telescopes. Results on vibrations test and thermo-vacuum tests on the engineering model will also be presented.Comment: 9 pages, 7 figures, to be published in Proc. SPIE 8443, "Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray

Return and Volatility Spillovers of Asian Pacific Stock Markets’ Energy Indices

The aim of the study was to investigate the presence of volatility among the Energy Indices of Asia Pacific Stock Markets. To test the volatility among the daily returns of Energy Indices of Asia Pacific Stock Markets, the study selected five sample Asian Pacific stock markets’ Energy Indices on the basis of availability of data. The findings of descriptive statistics and the ADF Test revealed, that the daily returns of the sample energy indices of Asian Pacific stock markets were not normally distributed and achieved stationarity at level difference, over the research period. Hence the data may be used for additional analysis. The data were then analysed, by using the GARCH (1,1) model to assess the considerable volatility of daily returns of sample energy indices and the study, which revealed that during the study period, all of the sample energy indices were volatile