1,101 research outputs found

    AMPA experimental communications systems

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    The program was conducted to demonstrate the satellite communication advantages of Adaptive Phased Array Technology. A laboratory based experiment was designed and implemented to demonstrate a low earth orbit satellite communications system. Using a 32 element, L-band phased array augmented with 4 sets of weights (2 for reception and 2 for transmission) a high speed digital processing system and operating against multiple user terminals and interferers, the AMPA system demonstrated: communications with austere user terminals, frequency reuse, communications in the face of interference, and geolocation. The program and experiment objectives are described, the system hardware and software/firmware are defined, and the test performed and the resultant test data are presented

    Agar gel electrophoresis of amylases

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    Agar gel electrophoresis of amylase

    Isolation of g-amylase

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    Isolation of g-amylas

    Metaphoric coherence: Distinguishing verbal metaphor from `anomaly\u27

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    Theories and computational models of metaphor comprehension generally circumvent the question of metaphor versus “anomaly” in favor of a treatment of metaphor versus literal language. Making the distinction between metaphoric and “anomalous” expressions is subject to wide variation in judgment, yet humans agree that some potentially metaphoric expressions are much more comprehensible than others. In the context of a program which interprets simple isolated sentences that are potential instances of cross‐modal and other verbal metaphor, I consider some possible coherence criteria which must be satisfied for an expression to be “conceivable” metaphorically. Metaphoric constraints on object nominals are represented as abstracted or extended along with the invariant structural components of the verb meaning in a metaphor. This approach distinguishes what is preserved in metaphoric extension from that which is “violated”, thus referring to both “similarity” and “dissimilarity” views of metaphor. The role and potential limits of represented abstracted properties and constraints is discussed as they relate to the recognition of incoherent semantic combinations and the rejection or adjustment of metaphoric interpretations

    Adaptive multibeam phased array design for a Spacelab experiment

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    The parametric tradeoff analyses and design for an Adaptive Multibeam Phased Array (AMPA) for a Spacelab experiment are described. This AMPA Experiment System was designed with particular emphasis to maximize channel capacity and minimize implementation and cost impacts for future austere maritime and aeronautical users, operating with a low gain hemispherical coverage antenna element, low effective radiated power, and low antenna gain-to-system noise temperature ratio

    End-to-End Differentiable Molecular Mechanics Force Field Construction

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    Molecular mechanics (MM) potentials have long been a workhorse of computational chemistry. Leveraging accuracy and speed, these functional forms find use in a wide variety of applications from rapid virtual screening to detailed free energy calculations. Traditionally, MM potentials have relied on human-curated, inflexible, and poorly extensible discrete chemical perception rules (atom types) for applying parameters to molecules or biopolymers, making them difficult to optimize to fit quantum chemical or physical property data. Here, we propose an alternative approach that uses graph nets to perceive chemical environments, producing continuous atom embeddings from which valence and nonbonded parameters can be predicted using a feed-forward neural network. Since all stages are built using smooth functions, the entire process of chemical perception and parameter assignment is differentiable end-to-end with respect to model parameters, allowing new force fields to be easily constructed, extended, and applied to arbitrary molecules. We show that this approach has the capacity to reproduce legacy atom types and can be fit to MM and QM energies and forces, among other targets

    A Case for Open Mission Systems in DOD Aircraft Avionics

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    The DOD is adopting open mission systems (OMS) as the future in the military aviation environment. OMS proponents promise reduced costs and truncated schedules through increased competition in the marketplace and reduced coding efforts. To the best of our knowledge, no studies have examined the success of these open architectures in the DOD. Therefore, we investigate costs and schedule for a recent DOD avionics OMS demonstration platform in comparison to 13 historically analogous programs

    Evaluation of Florida Physicians’ Knowledge and Attitudes Toward Accessing the State Prescription Drug Monitoring Program as a Prescribing Tool

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    Objective The purpose of this study is to assess Florida physicians\u27 attitudes and knowledge toward accessing the state\u27s prescription drug monitoring program (PDMP). Design Five thousand medical doctors and osteopathic physicians licensed in Florida were randomly selected for a voluntary and anonymous 15-question self-administered survey approved by the Institutional Review Board. Surveys were distributed through U.S. postal service mail. Likert-scale questions were used to assess prior knowledge (1 = none to 5 = excellent) and attitudes toward accessing the PDMP (1 = strongly disagree to 5 = strongly agree). Results The study yielded a response rate of 7.8%, 71.5% of whom agreed or strongly agreed that the PDMP is a useful tool. Among participants that have access and answered the PDMP usefulness question, 94.8% agree or strongly agree that it is a useful tool. There were 63 out of 64 physicians (98.4%) who conducted 25 or more searches who agreed or strongly agreed that the PDMP is a useful tool for monitoring patients\u27 controlled substance histories. There were 72.5% of participants with access that answered the “doctor shopping” question who agreed that “doctor shopping” will decrease. Among the 64 most frequent PDMP users, 69.4% agreed or strongly agreed that they have prescribed fewer controlled substances after accessing the PDMP. Conclusions The study revealed that a majority of participants believe that the PDMP is a useful tool for monitoring patients\u27 controlled substance histories. More continuing education programs should be provided to Florida physicians to enhance their knowledge regarding PDMPs

    Quantifying the Effects of Aircraft Engine Upgrades on Operating and Support Costs

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    For fixed wing aircraft within the U.S. Air Force, Operating and Support (O&S) costs encompass a large portion of total life cycle costs. O&S costs include fuel, maintenance, and engine upgrades. To the authors’ knowledge, no study to date has attempted to empirically quantify the realized effects of new aircraft engines on sustainment costs. Utilizing the Air Force Total Ownership Cost database, they focused on new engines appearing on the C-5s, C-130s, and C-135s. Although narrow in scope, results suggest newer engines have lower fuel costs. Maintenance costs for newer engines were not consistently higher or lower than the engines they replaced, although Contractor Logistics Support was not tracked by engine in this study. We found that savings from improved fuel efficiency tended to be greater than a potential increase in maintenance costs
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