2,418 research outputs found

    Spectroscopic Observations and Modelling of Impulsive Alfv\'en Waves Along a Polar Coronal Jet

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    Using the Hinode/EIS 2"" spectroscopic observations, we study the intensity, velocity, and FWHM variations of the strongest Fe XII 195.12 \AA\ line along the jet to find the signature of Alfv\'en waves. We simulate numerically the impulsively generated Alfv\'en waves within the vertical Harris current-sheet, forming the jet plasma flows, and mimicking their observational signatures. Using the FLASH code and the atmospheric model with embedded weakly expanding magnetic field configuration within a vertical Harris current-sheet, we solve the two and half-dimensional (2.5-D) ideal magnetohydrodynamic (MHD) equations to study the evolution of Alfv\'en waves and vertical flows forming the plasma jet. At a height of 5 Mm\sim 5~\mathrm{Mm} from the base of the jet, the red-shifted velocity component of Fe XII 195.12 \AA\ line attains its maximum (5 kms15~\mathrm{km\,s}^{-1}) which converts into a blue-shifted one between the altitude of 510 Mm5-10~\mathrm{Mm}. The spectral intensity continously increases up to 10 Mm10~\mathrm{Mm}, while FWHM still exhibits the low values with almost constant trend. This indicates that the reconnection point within the jet's magnetic field topology lies in the corona 510 Mm5-10~\mathrm{Mm} from its footpoint anchored in the Sun's surface. Beyond this height, FWHM shows a growing trend. This may be the signature of Alfv\'en waves that impulsively evolve due to reconnection and propagate along the jet. From our numerical data, we evaluate space- and time- averaged Alfv\'en waves velocity amplitudes at different heights in the jet's current-sheet, which contribute to the non-thermal motions and spectral line broadening. The synthetic width of Fe XII 195.12 A˚195.12~\mathrm{\AA} line exhibits similar trend of increment as in the observational data, possibly proving the existence of impulsively generated (by reconnection) Alfv\'en waves which propagate along the jet

    On Thermal-Pulse-Driven Plasma Flows in Coronal Funnels as Observed by Hinode/EUV Imaging Spectrometer (EIS)

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    Using one-arcsecond-slit scan observations from the Hinode/EUV Imaging Spectrometer (EIS) on 05 February 2007, we find the plasma outflows in the open and expanding coronal funnels at the eastern boundary of AR 10940. The Doppler velocity map of Fe XII 195.120 A shows that the diffuse close-loop system to be mostly red-shifted. The open arches (funnels) at the eastern boundary of AR exhibit blue-shifts with a maximum speed of about 10-15 km/s. This implies outflowing plasma through these magnetic structures. In support of these observations, we perform a 2D numerical simulation of the expanding coronal funnels by solving the set of ideal MHD equations in appropriate VAL-III C initial temperature conditions using the FLASH code. We implement a rarefied and hotter region at the footpoint of the model funnel, which results in the evolution of slow plasma perturbations propagating outward in the form of plasma flows. We conclude that the heating, which may result from magnetic reconnection, can trigger the observed plasma outflows in such coronal funnels. This can transport mass into the higher corona, giving rise to the formation of the nascent solar wind.Comment: 17 Pages; 7 Figure

    Photon redshift and the appearance of a naked singularity

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    In this paper we analyze the redshift as observed by an external observer receiving photons which terminate in the past at the naked singularity formed in a Tolman-Bondi dust collapse. Within the context of models considered here it is shown that photons emitted from a weak curvature naked singularity are always finitely redshifted to an external observer. Certain cases of strong curvature naked singularities, including the self-similar one, where the photons are infinitely redshifted are also pointed out.Comment: Latex file, 14 pages, no figures, one change in the reference. Accepted for publication in Phys. Rev.

    Assessment of roof water harvesting potential of Navsari city of Gujarat State, India by Remote sensing and Geographic information system (GIS)

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    Due to the water scarcity scenario in many parts of the Navsari city, Gujarat State in India, it is imperative to adopt cost-effective technologies that could harvest rainwater for satisfying drinking water requirements. The study was conducted with the aim of assessing the rainwater harvesting potential of Navsari city using remote sensing and Geographic Information System (GIS). The built-up areas of Navsari that could harness rainwater were identified by remote sensing and GIS. The effective built-up area contributing to rainwater harvesting was found to be 3.37 km2. The classification was carried out using “Remap” to assess the extent of the built-up area. The city was divided into equal grids and classification of each grid was implemented. The ground truth data was used for the evaluation of the built-up area. The roof water harvesting potential was estimated considering the average annual rainfall of 1621 mm and adopting suitable runoff coefficients. The rainwater harvesting potential of roofs for rainfall of different probabilities was estimated. For return periods of 10 years, 25 years, 50 years and 100 years, the roof water harvesting potentials were estimated to be 0.226, 0.261, 0.287 and 0.312 Million Cubic Metres (MCM), respectively. The estimated average roof water harvesting potential of Navsari city was 164 million litres per year, capable of satisfying the drinking water demand of approximately 1.12 lakh people annually. The rainwater harnessed from the rooftop could augment the current water supply and immensely help in fulfilling the drinking water demand of Navsari

    Polyherbal Formulation used in the Treatment of Jaundice

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    Plants have traditionally served as man\u27s most important weapon against pathogens. Herbal medicines are widely used by all sections of the community, either as folk remedies or as medicaments in the indigenous as well as modern system of medicine. The present work was performed to enumerate the medicinal herbs that tribes and rural people uses for the treatment of jaundice. Data were collected by interviewing local traditional therapists and tribes of the region. Details of 10 herbs and 03 formulations were gathered along with their doses, duration and formulations during the course of present investigation in the study area. Our study revealed that all above herbs and their formulations have been used since quite a long time by the tribes and rural people and no side/ adverse effects were reported

    Formulation and Evaluation of Polyherbal Anthelmintic Preparation

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    The present study was done with the aim to formulate an anthelmintic preparation and to evaluate anthelmintic activity of formulation containing traditionally user herbs viz., Plumbago zeylanica (leaves), Hyoscyamus niger (roots) and Abultion indicum (leaves) using adult earthworm Pheritima posthuma. The aqueous and ethanolic extract of the crude drug of different concentration were tested which involve determination of paralysis time and time to kill the worms. Piperazine citrate was used as standard and it was found that the PHFEE activity is higher than PHFAE

    Photochemical Investigations of Ce(III)-V(V) System in Glasses

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    1092-109

    Evaluation of Grass Bales Stored under Cover and Plinth System of Storage

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    The feed and fodder requirement for dairy animals is primarily met by roughages, green fodder and homemade concentrate mixtures. Roughages are high in crude fibrous material which essentially consists of cellulose, hemi-cellulose and to some extent lignin. Livestock production is backbone of Indian Agriculture and source of employment in rural areas for centuries. To meet the demand of feeding these huge livestock population an adequate supply of feed throughout the year is the prerequisite for successful animal production programmes. A huge gap between demand and supply of feed and fodder exists in our country. This huge gap between requirement and availability of livestock feeds like dry fodders, green fodders could however be bridged by proper post harvest management of all kind of forage resources and search for alternate source of protein rich forage supplement. The most common livestock feed resources are crop reduces (straw, stover, haulms etc). All of these fodder resources are highly voluminous and having lower density varying from 40-70 kg/m3 due to which there transportation, storage and handling are very cumbersome and expensive and therefore cannot be utilized up to a maximum extent. Storage is a repeated phase during transit of agricultural produce and the product needs to be stored from one harvest to next thus, demanding additional carry over as safe guard, against speculation in price and market demand or against shortage and famine
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