2,522 research outputs found

    Exothermic furnace module development

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    An exothermic furnace module was developed to rapidly heat and cool a 0.820-in. (2.1 cm) diameter by 2.75-in. (7.0 cm) long TZM molybdenum alloy crucible. The crucible contains copper, oxygen, and carbon for processing in a low-g environment. Peak temperatures of 1270 C were obtainable 3.5 min after start of ignition, and cooling below 950 C some 4.5 min later. These time-temperature relationships were conditioned for a foam-copper experiment, Space Processing Applications Rocket experiment 77-9, in a sounding rocket having a low-g period of 5 min

    Folding and insertion thermodynamics of the transmembrane WALP peptide

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    The anchor of most integral membrane proteins consists of one or several helices spanning the lipid bilayer. The WALP peptide, GWW(LA)n_n(L)WWA, is a common model helix to study the fundamentals of protein insertion and folding, as well as helix-helix association in the membrane. Its structural properties have been illuminated in a large number of experimental and simulation studies. In this combined coarse-grained and atomistic simulation study, we probe the thermodynamics of a single WALP peptide, focusing on both the insertion across the water-membrane interface, as well as folding in both water and a membrane. The potential of mean force characterizing the peptide's insertion into the membrane shows qualitatively similar behavior across peptides and three force fields. However, the Martini force field exhibits a pronounced secondary minimum for an adsorbed interfacial state, which may even become the global minimum---in contrast to both atomistic simulations and the alternative PLUM force field. Even though the two coarse-grained models reproduce the free energy of insertion of individual amino acids side chains, they both underestimate its corresponding value for the full peptide (as compared with atomistic simulations), hinting at cooperative physics beyond the residue level. Folding of WALP in the two environments indicates the helix as the most stable structure, though with different relative stabilities and chain-length dependence.Comment: 12 pages, 5 figure

    "Building back better": seeking an equitable return to sport-for-development in the wake of COVID-19

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    The COVID-19 pandemic affected sport programming by restricting in-person activities. Concurrently, global outcry for racial justice for Black and racialized communities promoted calls-to-action to assess equitable practices in sport, including Sport for Development (SfD). This study critically examined SfD ‘return to play’ programming to include perspectives from racialized persons’ lived experiences. We present findings based on data collected from MLSE Foundation’s Change the Game (CtG) research, which explored questions of sport inequity to ‘build back better’. Outcomes further SfD discourses challenging (potentially) harmful structures affecting participants, including under reported effects of racialization. The study used a mixed-method methodology with quantitative analysis of survey data, and thematic analysis of personal experience within an anti-racist, anti-oppressive, and decolonial conceptual framework

    Integrated developmental model of life-support capabilities in wheat

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    The objective of this project was to develop a model for CO2, O2, H2O, and nitrogen use during the life cycle of wheat. Spreadsheets and accompanying graphs were developed to illustrate plant population reactions to environmental parameters established in the Controlled Ecological Life Support System (CELSS) program at Kennedy Space Center, Fl. The spreadsheets and graphs were produced using validated biomass production chamber (BPC) data from BWT931. Conditions of the BPC during the 83 day plant growth period were as follows: The BPC area is 27.8 m(exp 2), volume is 113 m(exp 3). Temperatures during the 83 day plant growth period ranged from 16.3 to 24.8 C during the light cycle (except for day 69, when the minimum and maximum temperatures were 7.7 C and 7.9 C, respectively) and 14.5 C and 23.6 C during the dark cycle (except for day 49, when the minimum and maximum temperatures were 11.1 C and 11.3 C, respectively). Relative humidity was 85 percent for the first seven days of plant growth, and 70 percent thereafter. The plant leaf canopy area was 10 m(exp 2). Presented is a list and explanation of each spreadsheet and accompanying graph(s), conditions under which the data were collected, and formulas used to obtain each result

    A tool for assessing error in digital elevation models from a user’s perspective

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    A Digital Elevation Model (DEM) is a representation of geographic reality. The elevations recorded within DEMs have been shown to contain errors pertaining to sampling, measurement and interpolation (Fisher, 1998). Even a small amount of elevation error can greatly affect derivative products (Holmes et al., 2000). This can potentially have a significant impact on the application of DEMs in Geographical Information Systems (GIS) where first and second order derivatives are considered

    Measurement of Government Intervention: A Comparison of Alternative Concepts

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    The variation in protection awarded to agricultural commodities indicates some general patterns of protection across industrialized and developing countries. This paper provides an analytical overview of the political economy market of agricultural protection. A comprehensive comparative analysis of different measurement concepts and their respective polio coverage is discussed. A graphic exposition of the policy effects captured by selected measurement concepts is provided for different market conditions

    Electric Polarizability of Neutral Hadrons from Lattice QCD

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    By simulating a uniform electric field on a lattice and measuring the change in the rest mass, we calculate the electric polarizability of neutral mesons and baryons using the methods of quenched lattice QCD. Specifically, we measure the electric polarizability coefficient from the quadratic response to the electric field for 10 particles: the vector mesons ρ0\rho^0 and K0K^{*0}; the octet baryons n, Σ0\Sigma^0, Λo0\Lambda_{o}^{0}, Λs0\Lambda_{s}^{0}, and Ξ0\Xi^0; and the decouplet baryons Δ0\Delta^0, Σ0\Sigma^{*0}, and Ξ0\Xi^{*0}. Independent calculations using two fermion actions were done for consistency and comparison purposes. One calculation uses Wilson fermions with a lattice spacing of a=0.10a=0.10 fm. The other uses tadpole improved L\"usher-Weiss gauge fields and clover quark action with a lattice spacing a=0.17a=0.17 fm. Our results for neutron electric polarizability are compared to experiment.Comment: 25 pages, 20 figure

    Standard-resolution TOVS observations for the FIRE/SRB Wisconsin experiment region from October 9 through November 2, 1986

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    Maps and concise tables are presented which show TIROS Operational Vertical Sounder (TOVS) box centroid locations, box size, and vertical sounding products from the NOAA-6 and -9 satellites for the FIRE/SRB (First ISCCP Regional Experiment/Surface Radiation Budget) Wisconsin experiment region during October 9 through November 2, 1986. In addition to the operational standard products, relative reflectance is calculated and presented based on values from HIRS/2 Band 20 measurements
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