232 research outputs found

    Apollo Lightcraft Project

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    This second year of the NASA/USRA-sponsored Advanced Aeronautical Design effort focused on systems integration and analysis of the Apollo Lightcraft. This beam-powered, single-stage-to-orbit vehicle is envisioned as the shuttlecraft of the 21st century. The five person vehicle was inspired largely by the Apollo Command Module, then reconfigured to include a new front seat with dual cockpit controls for the pilot and co-pilot, while still retaining the 3-abreast crew accommodations in the rear seat. The gross liftoff mass is 5550 kg, of which 500 kg is the payload and 300 kg is the LH2 propellant. The round trip cost to orbit is projected to be three orders of magnitude lower than the current space shuttle orbiter. The advanced laser-driven 5-speed combined-cycle engine has shiftpoints at Mach 1, 5, 11 and 25+. The Apollo Lightcraft can climb into low Earth orbit in three minutes, or fly to any spot on the globe in less than 45 minutes. Detailed investigations of the Apollo Lightcraft Project this second year further evolved the propulsion system design, while focusing on the following areas: (1) man/machine interface; (2) flight control systems; (3) power beaming system architecture; (4) re-entry aerodynamics; (5) shroud structural dynamics; and (6) optimal trajectory analysis. The principal new findings are documented. Advanced design efforts for the next academic year (1988/1989) will center on a one meter+ diameter spacecraft: the Lightcraft Technology Demonstrator (LTD). Detailed engineering design and analyses, as well as critical proof-of-concept experiments, will be carried out on this small, near-term machine. As presently conceived, the LTD could be constructed using state of the art components derived from existing liquid chemical rocket engine technology, advanced composite materials, and high power laser optics

    Assessing the value of orphan drugs using conventional cost-effectiveness analysis:Is it fit for purpose?

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    Conventional cost-effectiveness analysis-i.e., assessing pharmaceuticals through a cost per quality-adjusted life year (QALY) framework-originated from a societal commitment to maximize population health given limited resources. This "extra-welfarist" approach has produced pricing and reimbursement systems that are not well- aligned with the unique considerations of orphan drugs. This framework has been slow to evolve along with our increased understanding of the impact of rare diseases, which in turn has complicated the assessment of orphan drugs meant to treat rare diseases. Herein, we (i) discuss the limitations of conventional cost-effectiveness analysis as applied to assessing access to, as well as the pricing and reimbursement of, orphan drugs, (ii) critically appraise alternative and supplemental approaches, and (iii) offer insights on plausible steps forward

    Weaving the Strands of Life (Iiná Bitł’ool): History of Genetic Research Involving Navajo People

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    To date, some genetic studies offer medical benefits, but lack a clear pathway to benefit for people from underrepresented backgrounds. Historically Indigenous people, including the Diné (Navajo people), have raised concerns about the lack of benefits, misuse of DNA samples, lack of consultation, and ignoring cultural and traditional ways of knowing. Shortly after the Navajo Nation Human Research Review Board was established in 1996, the Navajo Nation recognized growing concerns about genetic research and established a moratorium on human genetic research studies in 2002. The moratorium effectively has protected their citizens from potential genetic research harms. Despite the placement of the moratorium, some genetic research studies have continued using blood and DNA samples from Navajo people. In order to understand the history of genetic research involving Navajo people, we conducted a literature review of 79 genetic or genetic-related research publications that involved Navajo people from the years 1925 to 2018. In this review, we divided the genetic research studies into the following general classifications: a) bacteria or virus genetics studies, b) blood and human leukocyte antigen, c) complex diseases, d) forensics, e) hereditary diseases, and f) population genetics and migration. We evaluated the methods for each study, described the number of Navajo individuals included in each study, recorded the academic or tribal approval statements, and noted whether the study considered Diné cultural values. Several studies focused on Severe Combined Immunodeficiency Disease, population history, neuropathy, albinism, eye and skin disorders that affect Navajo people. We found genetic research publications involving Navajo people spanning over the course of 93 years. To our knowledge, no known literature reviews have examined the history of genetic research in the Navajo community. In our Discussion, we contextualize Diné ways of knowing related to genetics and health with Western scientific concepts to acknowledge the complex philosophy and belief system that guides Diné people and recognizes Indigenous science. We encourage researchers consider cultural perspectives and traditional knowledge that has the potential to create stronger conclusions and better informed, ethical, and respectful science

    Deweyan tools for inquiry and the epistemological context of critical pedagogy

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    This article develops the notion of resistance as articulated in the literature of critical pedagogy as being both culturally sponsored and cognitively manifested. To do so, the authors draw upon John Dewey\u27s conception of tools for inquiry. Dewey provides a way to conceptualize student resistance not as a form of willful disputation, but instead as a function of socialization into cultural models of thought that actively truncate inquiry. In other words, resistance can be construed as the cognitive and emotive dimensions of the ongoing failure of institutions to provide ideas that help individuals both recognize social problems and imagine possible solutions. Focusing on Dewey\u27s epistemological framework, specifically tools for inquiry, provides a way to grasp this problem. It also affords some innovative solutions; for instance, it helps conceive of possible links between the regular curriculum and the study of specific social justice issues, a relationship that is often under-examined. The aims of critical pedagogy depend upon students developing dexterity with the conceptual tools they use to make meaning of the evidence they confront; these are background skills that the regular curriculum can be made to serve even outside social justice-focused curricula. Furthermore, the article concludes that because such inquiry involves the exploration and potential revision of students\u27 world-ordering beliefs, developing flexibility in how one thinks may be better achieved within academic subjects and topics that are not so intimately connected to students\u27 current social lives, especially where students may be directly implicated

    Theoretical studies of ion bombardment: Many-body interactions

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    Many-body forces obtained by the embedded-atom method are incorporated into the description of low-energy collisions and surface ejection processes in molecular dynamics simulations of sputtering from metal targets. Bombardment of small, single-crystal Cu targets (400–500 atoms) in three different orientations ({100}, {110}, {111}) by 5-keV Ar + ions have been simulated. The results are compared to simulations using purely pairwise additive interactions. Significant differences in the spectra of ejected atoms are found

    The HTA risk analysis chart: visualising the need for and potential value of managed entry agreements in health technology assessment

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    Background Recent changes to the regulatory landscape of pharmaceuticals may sometimes require reimbursement authorities to issue guidance on technologies that have a less mature evidence base. Decision makers need to be aware of risks associated with such health technology assessment (HTA) decisions and the potential to manage this risk through managed entry agreements (MEAs). Objective This work develops methods for quantifying risk associated with specific MEAs and for clearly communicating this to decision makers. Methods We develop the ‘HTA risk analysis chart’, in which we present the payer strategy and uncertainty burden (P-SUB) as a measure of overall risk. The P-SUB consists of the payer uncertainty burden (PUB), the risk stemming from decision uncertainty as to which is the truly optimal technology from the relevant set of technologies, and the payer strategy burden (PSB), the additional risk of approving a technology that is not expected to be optimal. We demonstrate the approach using three recent technology appraisals from the UK National Institute for Health and Clinical Excellence (NICE), each of which considered a price-based MEA. Results The HTA risk analysis chart was calculated using results from standard probabilistic sensitivity analyses. In all three HTAs, the new interventions were associated with substantial risk as measured by the P-SUB. For one of these technologies, the P-SUB was reduced to zero with the proposed price reduction, making this intervention cost effective with near complete certainty. For the other two, the risk reduced substantially with a much reduced PSB and a slightly increased PUB. Conclusions The HTA risk analysis chart shows the risk that the healthcare payer incurs under unresolved decision uncertainty and when considering recommending a technology that is not expected to be optimal given current evidence. This allows the simultaneous consideration of financial and data-collection MEA schemes in an easily understood format. The use of HTA risk analysis charts will help to ensure that MEAs are considered within a standard utility-maximising health economic decision-making framework

    Understanding Dwarf Galaxies in order to Understand Dark Matter

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    Much progress has been made in recent years by the galaxy simulation community in making realistic galaxies, mostly by more accurately capturing the effects of baryons on the structural evolution of dark matter halos at high resolutions. This progress has altered theoretical expectations for galaxy evolution within a Cold Dark Matter (CDM) model, reconciling many earlier discrepancies between theory and observations. Despite this reconciliation, CDM may not be an accurate model for our Universe. Much more work must be done to understand the predictions for galaxy formation within alternative dark matter models.Comment: Refereed contribution to the Proceedings of the Simons Symposium on Illuminating Dark Matter, to be published by Springe

    Submicron Structures Technology and Research

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    Contains reports on fourteen research projects.Joint Services Electronics Program (Contract DAAG29-83-K-0003)U.S. Navy - Office of Naval Research (Contract N00014-79-C-0908)National Science Foundation (Grant ECS82-05701)Semiconductor Research Corporation (Grant 83-01-033)U.S. Department of Energy (Contract DE-ACO2-82-ER-13019)Lawrence Livermore National Laboratory (Contract 2069209)National Aeronautics and Space Administration (Contract NAS5-27591)Defense Advanced Research Projects Agency (Contract N00014-79-C-0908)National Science Foundation (Grant ECS80-17705)National Aeronautics and Space Administration (Contract NGL22-009-638

    Submicron Structures Technology and Research

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    Contains reports on fifteen research projects.Joint Services Electronics Program (Contract DAALO3-86-K-0002)National Science Foundation (Grant ECS 87-09806)Semiconductor Research Corporation (Contract 87-SP-080)National Science Foundation (Grant ECS 85-03443)U.S. Air Force - Office of Scientific Research (Grant AFOSR 85-0376)National Science Foundation (Grant ECS 85-06565)U.S. Air Force - Office of Scientific Research (Grant AFOSR 85-0154)Lawrence Livermore National Laboratory (Subcontract 2069209)National Aeronautics and Space Adminstration (Grant NGL22-009-683)Collaboration with KMS Fusion, Inc
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