178 research outputs found

    Effects of impingement of rocket exhaust gases and solid particles on a spacecraft Interim report, Mar. 18 - Oct. 25, 1966

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    Impingement damage to spacecraft from rocket exhaust gases and micron sized metal particle

    Discurso pronunciado por el Dr. Lewis W. Hackett agradeciendo cena de despedida: Septiembre 12 de 1949

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    Colegas y amigos. Estoy algo cohibido por esta demostración de aprecio y estima. Tengo una pequeña dificultad en identificarme con la persona motivo de este homenaje, y me hago la ilusión de ser un espectador. Esto es en parte, supongo, debido a que mi subconciencia desea eludir esta despedida final de los amigos y de las actividades que han llenado mi vida durante un servicio activo de 35 años. Pero la razón principal sin duda por qué me siento un podo extraño y un poco incómodo en esta reunión es debido a que cuando personas como yo alcanzan la edad de retrospección, sabernos muy bién que nosotros dejamos de conocer tanto como lo que pretendemos, y que no hemos cumplido la mitad de lo que se nos atribuye [...].Fil: Hackett, Lewis W.. Fundación Rockefeller; Estados UnidospapelEpson ScanEpson Stylus L210Política científicaUnidad documental simpleBiblioteca Bernardo A. Houssay-0

    ATR-FTIR Spectroscopic Studies of Polymer-Based Identification Cards

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    Counterfeit production of polymer identity cards poses a significant economic cost to society and a threat to national security. Identifying these counterfeits is a challenge for ‘frontline’ personnel who lack training in specialised document examination. This study investigates the use of attenuated total reflectance Fourier Transform infrared (ATR-FTIR) spectroscopy with chemometrics as a potential approach to assessing polymer card authenticity. In situ analysis of several cards found that differentiation could be achieved based on the core polymer composition. A chemometric model was thus built for three driver’s licence series produced in Western Australia and tested using a separate set of seven licences. The majority of test samples were correctly matched to the series of issue, with atypical samples recognisable based on their discriminant values. Synchrotron FTIR imaging revealed that differentiation between each series was possibly related to the adhesive used between the core layers. The approach presented in this work has the potential to be developed as a rapid screening method to identify suspect polymer cards warranting further examination

    Quark contributions to baryon magnetic moments in full, quenched, and partially quenched QCD

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    The chiral nonanalytic behavior of quark-flavor contributions to the magnetic moments of octet baryons is determined in full, quenched and partially quenched QCD, using an intuitive and efficient diagrammatic formulation of quenched and partially quenched chiral perturbation theory. The technique provides a separation of quark-sector magnetic-moment contributions into direct sea-quark loop, valence-quark, indirect sea-quark loop and quenched valence contributions, the latter being the conventional view of the quenched approximation. Both meson and baryon mass violations of SU(3)-flavor symmetry are accounted for. Following a comprehensive examination of the individual quark-sector contributions to octet baryon magnetic moments, numerous opportunities to observe and test the underlying structure of baryons and the nature of chiral nonanalytic behavior in QCD and its quenched variants are discussed. In particular, the valence u-quark contribution to the proton magnetic moment provides the optimal opportunity to directly view nonanalytic behavior associated with the meson cloud of full QCD and the quenched meson cloud of quenched QCD. The u quark in Σ+ provides the best opportunity to display the artifacts of the quenched approximation.Derek B. Leinwebe

    Affordances, constraints and information flows as ‘leverage points’ in design for sustainable behaviour

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    Copyright @ 2012 Social Science Electronic PublishingTwo of Donella Meadows' 'leverage points' for intervening in systems (1999) seem particularly pertinent to design for sustainable behaviour, in the sense that designers may have the scope to implement them in (re-)designing everyday products and services. The 'rules of the system' -- interpreted here to refer to affordances and constraints -- and the structure of information flows both offer a range of opportunities for design interventions to in fluence behaviour change, and in this paper, some of the implications and possibilities are discussed with reference to parallel concepts from within design, HCI and relevant areas of psychology

    Defending the genome from the enemy within:mechanisms of retrotransposon suppression in the mouse germline

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    The viability of any species requires that the genome is kept stable as it is transmitted from generation to generation by the germ cells. One of the challenges to transgenerational genome stability is the potential mutagenic activity of transposable genetic elements, particularly retrotransposons. There are many different types of retrotransposon in mammalian genomes, and these target different points in germline development to amplify and integrate into new genomic locations. Germ cells, and their pluripotent developmental precursors, have evolved a variety of genome defence mechanisms that suppress retrotransposon activity and maintain genome stability across the generations. Here, we review recent advances in understanding how retrotransposon activity is suppressed in the mammalian germline, how genes involved in germline genome defence mechanisms are regulated, and the consequences of mutating these genome defence genes for the developing germline

    Recommendations for environmental risk assessment of gene drive applications for malaria vector control

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    This is the final version. Available on open access from BMC via the DOI in this record. Building on an exercise that identified potential harms from simulated investigational releases of a population suppression gene drive for malaria vector control, a series of online workshops identified nine recommendations to advance future environmental risk assessment of gene drive applications.Bill and Melinda Gates FoundationOpen Philanthrop
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