6,946 research outputs found

    Water management in post-colonial Darjeeling: the promise and limits of decentralised resource provision

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    Water crises are spreading across the length of South Asia at an alarming rate, and some of the pockets of stress include unexpected locations such as Darjeeling, West Bengal, where rainfall is plentiful. This article explores the problems of post-colonial water management in the former British hill station to illuminate the prospects for integrated resource provision. We argue that to improve the scope of water distribution and provision, post-colonial townships such as Darjeeling need to acknowledge and address the multiple ways in which people get water from the centralised supply as well as the decentralised solutions that have arisen through community organisation in collectives known as samaj. Notably, the samaj have a distinct character based on histories of colonial neglect that prompted villages throughout the Darjeeling region to solve socioeconomic problems independently of centralised systems. The discussion overlaps the numerous resource pathways with the plethora of social and political organisations operating in Darjeeling to argue that municipalities would do well to harness the varied ways in which water flows through the township. Integrated within larger questions of sustainable development in India’s urbanising townships, the text offers a glimpse into the possibilities for more holistic and equitable water management.Georgina Drew & Roshan P. Ra

    An equatorial wind from the massive young stellar object S140 IRS 1

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    The discovery of the second equatorial ionized stellar wind from a massive young stellar object is reported. High resolution radio continuum maps of S140 IRS 1 reveal a highly elongated source that is perpendicular to the larger scale bipolar molecular outflow. This picture is confirmed by location of a small scale monopolar near-IR reflection nebula at the base of the blueshifted lobe. A second epoch of observations over a five year baseline show little ordered outward proper motion of clumps as would have been expected for a jet. A third epoch, taken only 50 days after the second, did show significant changes in the radio morphology. These radio properties can all be understood in the context of an equatorial wind driven by radiation pressure from the central star and inner disc acting on the gas in the surface layers of the disc as proposed by Drew et al. (1998). This equatorial wind system is briefly compared with the one in S106IR, and contrasted with other massive young stellar objects that drive ionized jets.Comment: 19 pages, 5 figures, accepted by ApJ, minor changes in light of referees repor

    Temperature dependent optical studies of Ti1−x_{1-x}Cox_xO2_2

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    We present the results of Raman and photoluminescence (PL) studies on epitaxial anatase phase Ti1−x_{1-x}Cox_xO2_2 films for xx = 0-0.07, grown by pulsed laser deposition. The low doped system (xx=0.01 and 0.02) shows a Curie temperature of ~700 K in the as-grown state. The Raman spectra from the doped and undoped films confirm their anatase phase. The photoluminescence spectrum is characterized by a broad emission from self-trapped excitons (STE) at 2.3 eV at temperatures below 120 K. This peak is characteristic of the anatase-phase TiO2_2 and shows a small blueshift with increasing doping concentration. In addition to the emission from STE, the Co-doped samples show two emission lines at 2.77 eV and 2.94 eV that are absent in the undoped film indicative of a spin-flip energy.Comment: 8 pages, 4 figure

    Galactic Plane Hα\alpha Surveys: IPHAS & VPHAS+

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    The optical Galactic Plane Hα\alpha surveys IPHAS and VPHAS+ are dramatically improving our understanding of Galactic stellar populations and stellar evolution by providing large samples of stars in short lived, but important, evolutionary phases, and high quality homogeneous photometry and images over the entire Galactic Plane. Here I summarise some of the contributions these surveys have already made to our understanding of a number of key areas of stellar and Galactic astronomy.Comment: 5 pages, 2 figures, refereed proceeding of the "The Universe of Digital Sky Surveys" conference, November 2014, to be published in the Astrophysics and Space Science Proceeding

    Evolution of Chloroplast Transcript Processing in Plasmodium and Its Chromerid Algal Relatives

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    Chloroplasts contain their own genomes, containing two broad functional types of gene: genes encoding proteins directly involved in photosynthesis, and genes with a non-photosynthesis function, such as cofactor biosynthesis, assembly of protein complexes, or expression of the chloroplast genome. Thus far, to our knowledge, no chloroplast gene expression pathways in any lineage have been found to target one functional category of gene specifically. Here, we show that a chloroplast RNA processing pathway – the addition of a 3′ poly(U) tail – is specifically associated with photosynthesis genes in two species of algae, the ‘chromerids’ Chromera and Vitrella. The addition of the poly(U) tail enables the precise processing of mature photosynthesis gene transcripts from precursor RNA, and is likely to be essential for expression of the chromerid photosynthesis machinery. The chromerid algae are the closest photosynthetic relatives of a parasitic group of eukaryotes, the apicomplexans, which include the malaria pathogen Plasmodium. Apicomplexans are descended from algae, and retain a reduced chloroplast, which contains genes only of non-photosynthesis function. We have confirmed that 3′ poly(U) tails are not added to Plasmodium chloroplast transcripts. The expression pathways associated with photosynthesis genes have therefore been lost in the evolution of the apicomplexan chloroplast, and this loss could potentially have driven the transition from photosynthesis to parasitism

    Origin of the anomalous Hall Effect in overdoped n-type cuprates: current vertex corrections due to antiferromagnetic fluctuations

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    The anomalous magneto-transport properties in electron doped (n-type) cuprates were investigated using Hall measurements at THz frequencies. The complex Hall angle was measured in overdoped Pr2−x_{\rm 2-x}Cex_{\rm x}CuO4_{\rm 4} samples (x=0.17 and 0.18) as a continuous function of temperature above TcT_c at excitation energies 5.24 and 10.5 meV. The results, extrapolated to low temperatures, show that inelastic scattering introduces electron-like contributions to the Hall response. First principle calculations of the Hall angle that include current vertex corrections (CVC) induced by electron interactions mediated by magnetic fluctuations in the Hall conductivity reproduce the temperature, frequency, and doping dependence of the experimental data. These results show that CVC effects are the source of the anomalous Hall transport properties in overdoped n-\text{-}type cuprates.Comment: 5 pages, 3 figure
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