624 research outputs found

    Documentation of GEMASS entry to touchdown simulation

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    The entry-to-touchdown space shuttle orbiter simulation capability incorporated into the GEMASS subprogram 33 (3-DOF) is documented. A digital autopilot interfaces between GEMASS and the guidance. Vehicle attitude is determined by use of the ability of GEMASS to integrate differential equations in addition to the equations of motion. Vehicle aerodynamic characteristics are obtained from an aerodynamic data tape and control surface deflections required to trim the vehicle, and trimmed aerodynamic coefficients are determined internally. Several indicators to allow evaluation of subsystem performance are included; as is the ability of the user to activate any of several error dispersion sources. The performance of the simulation compares well with more sophisticated simulations

    Citizenship rights for immigrants. National political processes and cross-national convergence in Western Europe, 1980–2008

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    Immigrant citizenship rights in the nation-state reference both theories of cross-national convergence and the resilience of national political processes. This article investigates European countries' attribution of rights to immigrants: Have these rights become more inclusive and more similar across countries? Are they affected by EU membership, the role of the judiciary, the party in power, the size of the immigrant electorate, or pressure exerted by anti-immigrant parties? Original data on 10 European countries, 1980-2008, reveal no evidence for cross-national convergence. Rights tended to become more inclusive until 2002, but stagnated afterward. Electoral changes drive these trends: growth of the immigrant electorate led to expansion, but countermobilization by right-wing parties slowed or reversed liberalizations. These electoral mechanisms are in turn shaped by long-standing policy traditions, leading to strong path dependence and the reproduction of preexisting cross-national differences. © 2012 by The University of Chicago. All rights reserved

    Technical guidelines for economic valuation of inland small-scale fisheries in developing countries

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    These ĂŽTechnical Guidelines for Economic Valuation of Inland Small-scale Fisheries in Developing Countriesö are one of the outputs of the project on ĂŽFood security and poverty alleviation through improved valuation and governance of river fisheries in Africaö. The guidelines draw upon research results and experience gained during the course of the project. The project was coordinated and implemented by the WorldFish Center and was carried out in cooperation with the National Agricultural Research Institutes (NARs) from the participating countries: the Nigeria Institute for Freshwater Fisheries Research, the Departments of Fishery of Niger, Malawi and Zambia, and the Cameroonian MinistΩre de lÆElevage, des PΩches et de lÆIndustrie Animale; and three advanced research institutes (ARIs): the Leibniz University of Hannover in Germany, the Institute for Sustainable Development and Aquatic Resources in UK, and the University of Cape Town in South Africa.Rural development, Sustainable development, Livelihoods, Economic analysis, Research, Artisanal fishing

    Synthesis and Encapsulation of Uniform Star‐Shaped Block‐Macromolecules

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    Linear uniform oligomers synthesized via a two‐step iterative cycle are postmodified with uniform octaethylene glycol monomethyl ether and finally coupled via azide‐alkyne cycloaddition to yield uniform star‐shaped block macromolecules with a mass ranging from 10 to 14 kDa. Each of the molecules is carefully characterized by NMR, electrospray ionization mass spectrometry (ESI‐MS), and size exclusion chromatography (SEC) to underline their purity as well as their uniformity. The obtained star‐shaped macromolecules are investigated in their ability to encapsulate dye molecules by carrying out qualitative solid–liquid phase transfer experiments

    A more sustainable and highly practicable synthesis of aliphatic isocyanides

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    Synthesis protocols to convert N-formamides into isocyanides using three different dehydration reagents (i.e. p-toluenesulfonyl chloride (p-TsCl), phosphoryl trichloride (POCl3) and the combination of triphenylphosphane (PPh3) and iodine) were investigated and optimized, while considering the principles of green chemistry. Comparison of the yield and the E-factors of the different synthesis procedures revealed that, in contrast to the typically applied POCl3 or phosgene derivatives, p-TsCl was the reagent of choice for non sterically demanding aliphatic mono- or di-N-formamides (yields up to 98% and lowest E-factor 6.45). Apart from a significantly reduced E-factor, p-TsCl is cheap, offers a simplified reaction protocol and work-up, and is less toxic compared to other dehydration reagents. Thus, this procedure offers easier and greener access to aliphatic isocyanide functionalities

    Hispidulin And Other Constituents Of Scoparia dulcis Linn

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    Phytochemical investigation of the ethanol extract of the whole plant of Scoparia dulcis, has resulted in the isolation of 4, 5, 7-trihydroxy-6-methoxyflavone, commonly called hispidulin and a steroidal glycoside, ÎČ-sitosterol-ÎČ-D-glucoside.  This is the first isolation of the two compounds from S. dulcis. Also isolated and characterized were the previously reported 6-me-thoxybenzoxazolinone, friedelan-3-one and scopadulcic acid B. Structural elucidation was done on the basis of spectroscopic data interpretations (IR, UV, NMR and EIMS).  Using the Tetrazolium-based colorimetric selective assay, hispidulin was found to be inactive against HIV-1/IIIB in MT-4 cells whereas the same test on the aqueous extract of the plant was positive

    Endoscopic Treatment of Stump Infection of the Residual Synovial Cavity After Through-the-Knee Amputation: A Case Report

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    CASE We report the case of a 35-year-old patient who presented with a septic residual synovial cavity infection 8 weeks after a through-the-knee amputation because of a parosteal sarcoma. An endoscopic evacuation of the turbid fluid and synovial debridement through parapatellar portals as in a standard knee arthroscopy was performed, in conjunction with appropriate antibiotic therapy. One year postoperatively, there were no signs of residual infection. CONCLUSION Endoscopic treatment of a septic stump infection of the residual synovial cavity after through-the-knee amputation is feasible. In our case, this approach resulted in rapid wound healing and early prosthesis mobility

    One‐Pot Synthesis of Thiocarbamates

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    An efficient isocyanide-based synthesis of S-thiocarbamates was discovered and thoroughly investigated. The new reaction protocol is a one-pot procedure and allows the direct conversion of N-formamides into thiocarbamates by initial dehydration with p-toluene sulfonyl chloride to the respective isocyanide and subsequent addition of a sulfoxide component. Contrary to recent literature, which also uses isocyanides as starting material, but with other sulfur reagents than sulfoxides, in this protocol, no isolation and purification of the isocyanide component is necessary, thus significantly decreasing the environmental impact and increasing the efficiency of the synthesis. The new protocol was applied to synthesize a library of sixteen thiocarbamates, applying four N-formamides and four commercially available sulfoxides. Furthermore, experiments were conducted to investigate the reaction mechanism. Finally, four norbornene-based thiocarbamate monomers were prepared and applied in controlled ring-opening metathesis polymerization (ROMP) reactions. The polymers were characterized by size-exclusion chromatography (SEC) and their properties were investigated utilizing differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)
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