272 research outputs found

    Rocket Performance of Red Fuming Nitric Acid with Blends of Norbornadiene, Carene and Cardanol

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    The fuel blends of nornornadiene and carene (50:50 by weight) and norbornadiene, carene and cardanol (40:40:20 by weight) exhibit synergistic hypergolic ignition with red fuming nitric acid (RFNA) as oxidiser. These fuel blends have been evaluated by theoretical calculations of performance parameters and subsequently verified by static firing in a 10 kg/sub f/ thruster at a chamber pressure of around 20 atm, using RFNA (with 21 per cent N/sub 2/O/sub 4/ by weight) as oxidiser. The theoretical calculations show maximum specific impulse and C*values at the O/F, 3 to be 227.8 s and 1598.7 m/s respectively for the norbornadiene-carene blend. The corresponding values for the norbornadiene, carene and cardanol blend were found to be 226.8 s and 1586.0 m/s respectively at the O/F, 4. For theoretical calculations, the chamber pressure (P/sub c) and the exit pressure (P/sub e/0 were assumed to be 20 and 1 atm, respectively. The static firing of the propellants in a 10 kg thruster exhibited smooth pressure-time curves with the experimental C* values in close agreement with those calculated and the non-deposition of carbon in the nozzle. This indicated low combustion instability and high combustion efficiency under rocket conditions (> 0.9). The fuel blends with their low cost and toxicity and relatively high density can replace G-fuel used in several Indian missiles without impairing the performance

    The workings of the single member plurality electoral system in India and the need for reform

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    India uses single member plurality system (SMPS) to elect the members of the lower house of its national parliament and the state assemblies. Under SMPS, elections are conducted for separate geographical areas, known as constituencies or districts, and the electors cast one vote each for a candidate with the winner being the candidate who gets the plurality of votes. SMPS is traditionally defended primarily on the grounds of simplicity and its tendency to produce winning candidates, which promotes a link between constituents and their representatives. It tends to provide a clear-cut choice for voters between two main parties, and is expected to gives rise to single-party rather than coalition governments. It also has the benefit of excluding extremist parties from gaining representation, unless their support is geographically concentrated

    Co-opting the state: how weak parties can make stable party systems

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    Conventional understandings of party system institutionalisation assume that institutionalised parties are necessary for interparty competition to stabilise. However, this approach neglects the role of the state in shaping party competition. Using survey data from Bangladesh, India and Pakistan, it is shown that weakly institutionalised parties can lead to institutionalised party systems if parties are able to successfully co-opt the state and use state resources to supplement party deficiencies. By developing a relationship that intertwines parties with the state, parties in young democracies do not need to institutionalise for stable party systems to form

    India after the 2014 general elections:BJP dominance and the crisis of the third party system

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    This article critically assesses claims that India has entered a new party system after the 2014 general elections, marked by renationalisation with the BJP as the new 'dominant' party.' To assess these claims, we examine the electoral rise of the BJP in the build-up to and since the 2014 general elections until the state assembly elections in December 2018. Overall, we argue that despite the emerging dominance of the BJP, a core feature of the third party system -a system of binodal interactions- has remained largely intact albeit in a somewhat weaker form. Furthermore, by comparing the post 2014 Indian party system with key electoral features of the first three party systems, we conclude that the rise of the BJP has thrown the third-party system into crisis, but does not yet define the consolidation of a new party system

    Acyl Homoserine Lactones from Culture Supernatants of Pseudomonas aeruginosa Accelerate Host Immunomodulation

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    The virulence of Pseudomonas aeruginosa is multifactorial and under the control of quorum sensing signals, such as acyl homoserine lactones (AHLs). The importance of these molecules in the establishment of infection has been previously reported. These molecules either improve the virulence potential of P. aeruginosa or modulate the host immune response. To establish the immune modulating potential of quorum sensing signal molecules, previous studies have only used synthetic AHLs. However, there can be differences in the biological properties of synthetic and natural AHLs. The use of naturally extracted AHLs from the culture supernatant of P. aeruginosa is likely to simulate natural conditions more than the use of synthetic AHLs. Therefore, in the present study, the immune modulating potential of synthetic and naturally extracted AHLs was compared using a thymidine uptake assay, immunophenotyping and sandwich ELISA in order to assess mouse T-cell proliferation and production of Th1 and Th2 cytokines. Natural AHLs were able to suppress T-cell proliferation, even at low concentrations, compared to synthetic AHLs. The majority of cells undergoing proliferation were CD4+, as revealed by immunophenotyping. The inhibition of T-cells was stronger with natural AHLs compared to synthetic AHLs. Moreover, the natural AHLs were also able to shift immune responses away from host protective Th1 responses to pathogen protective Th2 responses

    Governments, decentralisation, and the risk of electoral defeat

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    <p>In the last three decades several countries around the world have transferred authority from their national to their regional governments. However, not all their regions have been empowered to the same degree and important differences can be observed between and within countries. Why do some regions obtain more power than others? Current literature argues that variation in the redistribution of power and resources between regions is introduced by demand. Yet these explanations are conditional on the presence of strong regionalist parties or territorial cleavages. This article proposes instead a theory that links the government’s risk of future electoral defeat with heterogeneous decentralisation, and tests its effects using data from 15 European countries and 141 regions. The results provide evidence that parties in government protect themselves against the risk of electoral defeat by selectively targeting decentralisation towards regions in which they are politically strong. The findings challenge previous research that overestimates the importance of regionalist parties while overlooking differences between regions.</p

    Prototype tasks: Improving crowdsourcing results through rapid, iterative task design

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    Low-quality results have been a long-standing problem on microtask crowdsourcing platforms, driving away requesters and justifying low wages for workers. To date, workers have been blamed for low-quality results: they are said to make as little effort as possible, do not pay attention to detail, and lack expertise. In this paper, we hypothesize that requesters may also be responsible for low-quality work: they launch unclear task designs that confuse even earnest workers, under-specify edge cases, and neglect to include examples. We introduce prototype tasks, a crowdsourcing strategy requiring all new task designs to launch a small number of sample tasks. Workers attempt these tasks and leave feedback, enabling the requester to iterate on the design before publishing it. We report a field experiment in which tasks that underwent prototype task iteration produced higher-quality work results than the original task designs. With this research, we suggest that a simple and rapid iteration cycle can improve crowd work, and we provide empirical evidence that requester “quality” directly impacts result quality

    The Daemo crowdsourcing marketplace

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    The success of crowdsourcing markets is dependent on a strong foundation of trust between workers and requesters. In current marketplaces, workers and requesters are often unable to trust each other’s quality, and their mental models of tasks are misaligned due to ambiguous instructions or confusing edge cases. This breakdown of trust typically arises from (1) flawed reputation systems which do not accurately reflect worker and requester quality, and from (2) poorly designed tasks. In this demo, we present how Boomerang and Prototype Tasks, the fundamental building blocks of the Daemo crowdsourcing marketplace, help restore trust between workers and requesters. Daemo’s Boomerang reputation system incentivizes alignment between opinion and ratings by determining the likelihood that workers and requesters will work together in the future based on how they rate each other. Daemo’s Prototype tasks require that new tasks go through a feedback iteration phase with a small number of workers so that requesters can revise their instructions and task designs before launch

    Inactivation and sub-lethal injury of salmonella typhi, salmonella typhimurium and vibrio cholerae in copper water storage vessels

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    Background: This study provides information on the antibacterial effect of copper against the water-borne pathogens Salmonella Typhi, Salmonella Typhimurium and Vibrio cholerae. Methods: Suspensions of each pathogen were kept in water within a traditional copper vessel at 30°C for 24 h. Samples were withdrawn, diluted and plated onto suitable growth media. Conventional enumeration of healthy (uninjured) bacteria was carried out using standard aerobic incubation conditions. Additionally, reactive oxygen species-neutralised (ROS-n) conditions were achieved by adding the peroxide scavenger sodium pyruvate to the medium with anaerobic incubation, to enumerate uninjured (ROS-insensitive) and injured (ROS-sensitive) bacteria. Differences between log-transformed means of conventional (aerobic) and ROS-n counts were statistically evaluated using t tests. Results: Overall, all three pathogens were inactivated by storage in copper vessels for 24 h. However, for shorter-term incubation (4-12 h), higher counts were observed under ROS-n conditions than under aerobic conditions, which demonstrate the presence of substantial numbers of sub-lethally injured cells prior to their complete inactivation. Conclusions: The present study has for the first time confirmed that these bacterial pathogens are inactivated by storage in a copper vessel within 24 h. However, it has also demonstrated that it is necessary to account for short-term sub-lethal injury, manifest as ROS-sensitivity, in order to more fully understand the process. This has important practical implications in terms of the time required to store water within a copper vessel to completely inactivate these bacteria and thereby remove the risk of water-borne disease transmission by this route

    Development of a triclosan scaffold which allows for adaptations on both the A- and B-ring for transport peptides

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    The enoyl acyl-carrier protein reductase (ENR) enzyme is harbored within the apicoplast of apicomplexan parasites providing a significant challenge for drug delivery, which may be overcome through the addition of transductive peptides, which facilitates crossing the apicoplast membranes. The binding site of triclosan, a potent ENR inhibitor, is occluded from the solvent making the attachment of these linkers challenging. Herein, we have produced 3 new triclosan analogs with bulky A- and B-ring motifs, which protrude into the solvent allowing for the future attachment of molecular transporters for delivery
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