12,022 research outputs found

    Long-term stability test of a triple GEM detector

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    The main aim of the study is to perform the long-term stability test of gain of the single mask triple GEM detector. A simple method is used for this long- term stability test using a radioactive X-ray source with high activity. The test is continued till accumulation of charge per unit area > 12.0 mC/mm2. The details of the chamber fabrication, the test set-up, the method of measurement and the test results are presented in this paper.Comment: 8 pages, 5 figure

    Khat-chewing, Moral Spacing and Belonging: Sociological Insights into the Cultural Space of the mafrish in the Leisure Lives of Older and Middle-aged British-Somali Males

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    This paper explores the relationship between khat-chewing and feelings of collective sociality amongst older and middle-aged men living in Britain's Somali diaspora. The research's core investigates the feeling of moral connectivity, a sense of belonging with others based around a shared reading of Somali-British identity. Here, the paper explores how the leisure practice of khat-chewing in the space of the mafrish symbolises this sense of belonging through promoting conventional understandings of Somaliness, connected to traditional readings of masculinity and identity. While such leisure is understood to offer a site of collective belonging for the older and middle-aged men who chew khat, it is also explored how khat-chewing creates conflicts, particularly amongst those who question the 'imagined community' constructed in such spaces. The analyses highlight how this leisure practice fractures families and the broader community, instigating a feeling of cultural dissonance amongst women and some youth, problematising the cultural foundations of identity and community constructed in khat-chewing sessions

    EFFECT OF SULPHUR DIOXIDE ON GROWTH, CHLOROPHYLL AND SULPHUR CONTENTS OF TOMATO (SOLANUM LYCOPERSICUM L.)

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    The direct toxic effect of atmospheric pollutant such as sulphur dioxide on plants has been well documented. It is essentially a potent phytotoxic gas and its toxicity to plant is manifested in typical chronic or acute foliar symptom injury. The mode and extent of damage caused by this pollutant to tomato has not been precisely and systematically studied. Under such circumstances, the present investigation was undertaken under simulating condition to find out the possible extent of adaptability of tomato in SO2 emission of our state. The effect of varying levels of sulphur dioxide (0.25, 0.5 and 1.0 ppm) fumigated for 1 hour, 2 hours and 3 hours under simulated conditions on tomato revealed that the important traits like leaf number, leaf area, fresh weight, dry weight and chlorophyll content in leaves were adversely affected, the latter treatment (SO2 1.0 ppm with 3 hours exposure) being more uninnocuous in this regards. However, no significant variation was seen amongst the treatments in respect of tissue fresh and dry weight when compared with that of control (ambient SO2). On the other hand, sulphur content in tissues increase progressively with increasing levels of SO2 and time of fumigation and the variation observed within treatments was significant to each other. It is suggested that the lowest concentration of SO2 (0.25 ppm) used in this study is more than sufficient to bring about a significant changes in most of the parameters studied

    Excitations in time-dependent density-functional theory

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    An approximate solution to the time-dependent density functional theory (TDDFT) response equations for finite systems is developed, yielding corrections to the single-pole approximation. These explain why allowed Kohn-Sham transition frequencies and oscillator strengths are usually good approximations to the true values, and why sometimes they are not. The approximation yields simple expressions for G\"orling-Levy perturbation theory results, and a method for estimating expectation values of the unknown exchange-correlation kernel.Comment: 4 pages, 1 tabl

    Effect of Chemistry and Processing Variables on the Mechanical Properties of Thin-wall Ductile Iron Castings

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    Cast iron is an alloy of iron containing more than 2% carbon as an alloying element. It has almost no ductility and must be formed by casting. Ductile iron structure is developed from the melt of cast iron. The presence of silicon in higher amount promotes the graphitization, inhibiting carbon to form carbides with carbide forming elements present. The carbon forms into spheres when Ce, Mg are added to the melt of iron with very low sulphur content. Due to this special microstructure containing graphite in nodular form ductile iron possesses ductility & toughness superior to that of any cast iron & steel structure resulting in numerous successes in industrial application. Ductile iron castings with 3 and 12 mm thickness with varying chemical composition were cast in furan resin sand molds to identify the effect of sample thickness on microstructural changes and selected mechanical properties. The effect of melt chemistry and molten metal processing variables (i.e., pre-conditioning of the base iron, inoculation type and practice, and pouring temperature, etc.) on the tensile and impact properties of thin-wall ductile iron castings has been investigated. Comparison of 3 and 12 mm sections within the same casting showed that section size was the main factor influencing tensile properties of ductile irons. While many samples from 3 mm sections showed low elongation values, likely caused by a high pearlite content or presence of carbides, many others showed higher elongations and superior strengths well above those required in ASTM A536 grades. At moderate to high elongations, the thin-wall samples were significantly stronger than samples from identical irons of 12 mm section. A direct comparison between impact values could not be made due to different test specimen sizes, but it is clear that toughness in the two section sizes was roughly equivalent when account was made for the total cross sectional area. The main difference between the Impact properties in the two section sizes lay in the relative insensitivity of the thin-section specimens to either melt chemistry or molten metal processing variables. Of the elements contained in the iron, silicon had the greatest effect on the tensile properties of the thin-wall sections. The same increase in silicon content of the thin-wall sections had little effect on impact toughness. As expected, any processing variable that led to an increase in nodule count (with a corresponding increase in ferrite content) led to greater ductility, lower strength, and improved toughness. Of the v variables studied the greatest effect was found to be from late inoculation, base iron preconditioning, and the use of an inoculant containing bismuth and rare earths

    Remote terminal system evaluation

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    An Earth Resources Data Processing System was developed to evaluate the system for training, technology transfer, and data processing. In addition to the five sites included in this project two other sites were connected to the system under separate agreements. The experience of these two sites is discussed. The results of the remote terminal project are documented in seven reports: one from each of the five project sites, Purdue University, and an overview report summarizing the other six reports
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