22,061 research outputs found

    Evaluation of anomalies observed on film from S-190A flight system calibration test

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    Due to a persistent problem of scratched film from testing of the Skylab S-190A system, a series of tests were designed to identify the cause of the film scratching. The procedures followed in this test for pretest handling and packaging of the film, the makeup of the rolls for processing, and the results of the processed film evaluation are reported

    Compositional redistribution during casting of Hg sub 0.8 Cd sub 0.2 Te alloys

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    A series of Hg(0.8)Cd(0.2)Te ingots was cast both vertically and horizontally under well-defined thermal conditions by using a two-zone furnace with isothermal heat-pipe liners. The main objective of the experiments was to establish correlations between casting parameters and compositional redistribution and to develop ground-based data for a proposed flight experiment of casting of Hg(1-x)Cd(x)Te alloys under reduced gravity conditions. The compositional variations along the axial and radial directions were determined by precision density measurements, infrared transmission spectra, and X-ray energy dispersion spectrometry. Comparison between the experimental results and a numerical simulation of the solidification process of Hg(0.8)Cd(0.2)Te is described

    The NIF LinkOut Broker: A Web Resource to Facilitate Federated Data Integration using NCBI Identifiers

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    This paper describes the NIF LinkOut Broker (NLB) that has been built as part of the Neuroscience Information Framework (NIF) project. The NLB is designed to coordinate the assembly of links to neuroscience information items (e.g., experimental data, knowledge bases, and software tools) that are (1) accessible via the Web, and (2) related to entries in the National Center for Biotechnology Information’s (NCBI’s) Entrez system. The NLB collects these links from each resource and passes them to the NCBI which incorporates them into its Entrez LinkOut service. In this way, an Entrez user looking at a specific Entrez entry can LinkOut directly to related neuroscience information. The information stored in the NLB can also be utilized in other ways. A second approach, which is operational on a pilot basis, is for the NLB Web server to create dynamically its own Web page of LinkOut links for each NCBI identifier in the NLB database. This approach can allow other resources (in addition to the NCBI Entrez) to LinkOut to related neuroscience information. The paper describes the current NLB system and discusses certain design issues that arose during its implementation

    Embedding generic employability skills in an accounting degree: development and impediments

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    This paper explores and analyses the views of, and effects on, students of a project that integrated the development of employability skills within the small group classes of two compulsory courses in the first year of an accounting degree at a UK university. The project aimed to build, deliver and evaluate course materials designed to encourage the development of a broad range of employability skills: skills needed for life-long learning and a successful business career. By analysing students' opinions gathered from a series of focus groups spread throughout the year, three prominent skill areas of interest were identified: time management, modelling, and learning to learn. Further analysis highlighted the complex nature of skills development, and brought to light a range of impediments and barriers to both students' development of employability skills and their subject learning. The analysis suggests the need for accounting educators to see skills development as being an essential element of the path to providing a successful accounting education experience

    Managing Risk in Farming: Concepts, Research, and Analysis

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    The risks confronted by grain and cotton farmers are of particular interest, given the changing role of the Government after passage of the 1996 Farm Act. With the shift toward less government intervention in the post-1996 Farm Act environment, a more sophisticated understanding of risk and risk management is important to help producers make better decisions in risky situations and to assist policymakers in assessing the effectiveness of different types of risk protection tools. In response, this report provides a rigorous, yet accessible, description of risk and risk management tools and strategies at the farm level. It also provides never-before-published data on farmers' assessments of the risks they face, their use of alternative risk management strategies, and the changes they would make if faced with financial difficulty. It also compares price risk across crops and time periods, and provides detailed information on yield variability.crop insurance, diversification, futures contracts, leasing, leveraging, liquidity, livestock insurance, marketing contracts, options contracts, production contracts, revenue insurance, risk, vertical integration, Farm Management, Risk and Uncertainty,

    Photoluminescence Detected Doublet Structure in the Integer and Fractional Quantum Hall Regime

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    We present here the results of polarized magneto-photoluminescence measurements on a high mobility single-heterojunction. The presence of a doublet structure over a large magnetic field range (2>nu>1/6) is interpreted as possible evidence for the existence of a magneto-roton minima of the charged density waves. This is understood as an indication of strong electronic correlation even in the case of the IQHE limit.Comment: submitted to Solid State Communication

    Dental problems and Familismo: social network discussion of oral health issues among adults of Mexican origin living in the Midwest United States

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    Objective: To examine the influence of collectivist orientation (often called familismo when applied to the Latino sub-group in the United States) in oral health discussion networks. Basic Research Design: Through respondent-driven sampling and face-to-face interviews, we identified respondents' (egos) personal social network members (alters). Egos stated whom they talked with about oral health, and how often they discussed dental problems in the preceding 12 months. Participants: An urban community of adult Mexican-American immigrants in the Midwest United States. We interviewed 332 egos (90% born in Mexico); egos named an average of 3.9 alters in their networks, 1,299 in total. Method: We applied egocentric network methods to examine the ego, alter, and network variables that characterize health discussion networks. Results: Kin were most often leveraged when dental problems arose; egos relied on individuals whom they perceive to have better knowledge about dental matters. However, reliance on knowledgeable alters decreased among egos with greater behavioral acculturation. Conclusions: This paper developed a network-based conceptualization of familismo. We describe the structure of oral health networks, including kin, fictive kin, peers, and health professionals, and examine how networks and acculturation help shape oral health among these Mexican-Americans

    Analytic Treatment of Positronium Spin Splittings in Light-Front QED

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    We study the QED bound-state problem in a light-front hamiltonian approach. Starting with a bare cutoff QED Hamiltonian, HBH_{_{B}}, with matrix elements between free states of drastically different energies removed, we perform a similarity transformation that removes the matrix elements between free states with energy differences between the bare cutoff, Λ\Lambda, and effective cutoff, \lam (\lam < \Lam). This generates effective interactions in the renormalized Hamiltonian, HRH_{_{R}}. These effective interactions are derived to order α\alpha in this work, with α≪1\alpha \ll 1. HRH_{_{R}} is renormalized by requiring it to satisfy coupling coherence. A nonrelativistic limit of the theory is taken, and the resulting Hamiltonian is studied using bound-state perturbation theory (BSPT). The effective cutoff, \lam^2, is fixed, and the limit, 0 \longleftarrow m^2 \alpha^2\ll \lam^2 \ll m^2 \alpha \longrightarrow \infty, is taken. This upper bound on \lam^2 places the effects of low-energy (energy transfer below \lam) emission in the effective interactions in the ∣ee‾>| e {\overline e} > sector. This lower bound on \lam^2 insures that the nonperturbative scale of interest is not removed by the similarity transformation. As an explicit example of the general formalism introduced, we show that the Hamiltonian renormalized to O(α)O(\alpha) reproduces the exact spectrum of spin splittings, with degeneracies dictated by rotational symmetry, for the ground state through O(α4)O(\alpha^4). The entire calculation is performed analytically, and gives the well known singlet-triplet ground state spin splitting of positronium, 7/6α2Ryd7/6 \alpha^2 Ryd. We discuss remaining corrections other than the spin splittings and how they can be treated in calculating the spectrum with higher precision.Comment: 46 pages, latex, 3 Postscript figures included, section on remaining corrections added, title changed, error in older version corrected, cutoff placed in a windo
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