3,160 research outputs found

    Ablative response of a silica phenolic to simulated liquid propellant rocket engine operating conditions

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    Ablative response of silica phenolic to simulated liquid propellant rocket engine operating condition

    Interpretation of runaway electron synchrotron and bremsstrahlung images

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    The crescent spot shape observed in DIII-D runaway electron synchrotron radiation images is shown to result from the high degree of anisotropy in the emitted radiation, the finite spectral range of the camera and the distribution of runaways. The finite spectral camera range is found to be particularly important, as the radiation from the high-field side can be stronger by a factor 10610^6 than the radiation from the low-field side in DIII-D. By combining a kinetic model of the runaway dynamics with a synthetic synchrotron diagnostic we see that physical processes not described by the kinetic model (such as radial transport) are likely to be limiting the energy of the runaways. We show that a population of runaways with lower dominant energies and larger pitch-angles than those predicted by the kinetic model provide a better match to the synchrotron measurements. Using a new synthetic bremsstrahlung diagnostic we also simulate the view of the Gamma Ray Imager (GRI) diagnostic used at DIII-D to resolve the spatial distribution of runaway-generated bremsstrahlung.Comment: 21 pages, 11 figure

    Stability and electronic structure of the complex K2_2PtCl6_6 structure-type hydrides

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    The stability and bonding of the ternary complex K2_2PtCl6_6 structure hydrides is discussed using first principles density functional calculations. The cohesion is dominated by ionic contributions, but ligand field effects are important, and are responsible for the 18-electron rule. Similarities to oxides are discussed in terms of the electronic structure. However, phonon calculations for Sr2_2RuH6_6 also show differences, particularly in the polarizability of the RuH6_6 octahedra. Nevertheless, the yet to be made compounds Pb2_2RuH6_6 and Be2_2FeH6_6 are possible ferroelectrics. The electronic structure and magnetic properties of the decomposition product, FeBe2_2 are reported. Implications of the results for H storage are discussed

    Policy instruments in the Common Agricultural Policy

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    Policy changes in the Common Agricultural Policy (CAP) can be explained in terms of the exhaustion and long-term contradictions of policy instruments. Changes in policy instruments have reoriented the policy without any change in formal Treaty goals. The social and economic efficacy of instruments in terms of evidence-based policy analysis was a key factor in whether they were delegitimized. The original policy instruments were generally dysfunctional, but reframing the policy in terms of a multifunctionality paradigm permitted the development of more efficacious instruments. A dynamic interaction takes place between the instruments and policy informed by the predominant discourses

    “I don’t know anything about their Culture”: The Disconnect between Allopathic and Traditional Maternity Care Providers in Rural Northern Ghana

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    The provision of maternal and neonatal health care in rural northern Ghana is pluralistic, consisting of traditional and allopathic providers. Although  women often use these providers interchangeably, important differences exist. This study explored the differences in approaches to maternal and neonatal care provision by these two different types of providers. This  research was part of the Stillbirth and Neonatal Death Study (SANDS),  conducted in northern Ghana in 2010. Trained field staff of the Navrongo Health Research Centre conducted in-depth interviews with 13 allopathic and 8 traditional providers. Interviews were audio-recorded, transcribed, and analyzed using in vivo coding and discussion amongst the research team. Three overarching themes resulted: 1) many allopathic providers were isolated from the culture of the communities in which they practiced, while traditional providers were much more aware of the local cultural  beliefs and practices. 2) Allopathic and traditional healthcare providers have different frameworks for understanding health and disease, with  allopathic providers relying heavily on their biomedical knowledge, and traditional providers drawing on their knowledge of natural remedies. 3) All providers agreed that education directed at pregnant women, providers (both allopathic and traditional), and the community at large is needed to improve maternal and neonatal outcomes. Our findings suggest that, among other things, programmatic efforts need to be placed on the cultural education of allopathic providers. (Afr J Reprod Health 2014; 18[2]: 36-45).Keywords: Allopathic medicine, traditional medicine, maternal health, delivery care, cultur

    Chebyshev approach to quantum systems coupled to a bath

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    We propose a new concept for the dynamics of a quantum bath, the Chebyshev space, and a new method based on this concept, the Chebyshev space method. The Chebyshev space is an abstract vector space that exactly represents the fermionic or bosonic bath degrees of freedom, without a discretization of the bath density of states. Relying on Chebyshev expansions the Chebyshev space representation of a bath has very favorable properties with respect to extremely precise and efficient calculations of groundstate properties, static and dynamical correlations, and time-evolution for a great variety of quantum systems. The aim of the present work is to introduce the Chebyshev space in detail and to demonstrate the capabilities of the Chebyshev space method. Although the central idea is derived in full generality the focus is on model systems coupled to fermionic baths. In particular we address quantum impurity problems, such as an impurity in a host or a bosonic impurity with a static barrier, and the motion of a wave packet on a chain coupled to leads. For the bosonic impurity, the phase transition from a delocalized electron to a localized polaron in arbitrary dimension is detected. For the wave packet on a chain, we show how the Chebyshev space method implements different boundary conditions, including transparent boundary conditions replacing infinite leads. Furthermore the self-consistent solution of the Holstein model in infinite dimension is calculated. With the examples we demonstrate how highly accurate results for system energies, correlation and spectral functions, and time-dependence of observables are obtained with modest computational effort.Comment: 18 pages, 13 figures, to appear in Phys. Rev.

    Nurses\u27 Alumnae Association Bulletin, April 1961

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    Alumnae Meetings 1960 Social Committee Clara Melville Scholarship Fund Bulletin Committee Private Duty Nurse\u27s Section Report of the School of Nursing and Nursing Service Staff Nurses Association Student Activities Personal Items of Interest Expansion of Jefferson Artificial Kidney Unit Medical Work in the Congo Marriages New Arrivals Necrology Annual Giving Fun
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