18,954 research outputs found

    Nonlinear Acoustics at GHz Frequencies in a Viscoelastic Fragile Glass Former

    Get PDF
    Using a picosecond pump-probe ultrasonic technique, we study the propagation of high-amplitude, laser-generated longitudinal coherent acoustic pulses in the viscoelastic fragile glass former DC704. We observe an increase of almost ten percent in acoustic pulse propagation speed of its leading shock front at the highest optical pump fluence which is a result of the supersonic nature of nonlinear propagation in the viscous medium. From our measurement we deduce the nonlinear acoustic parameter of the glass former in the GHz frequency range across the glass transition temperature.Comment: 5 pages, 3 figure

    If You Can't Trust the Farmer, Who Can You Trust? The Effect of Certification Types on Purchases of Organic Produce

    Get PDF
    An information asymmetry exists in the market for organic produce since consumers cannot determine whether produce is organically or conventionally grown. Various methods may solve this problem including signaling, reputation, and certification. Signaling and reputation may not work well, because signals are noisy, and reputation may be difficult for a producer to establish. Certification of the farm and its growing methods shows the most promise. A survey instrument testing the efficacy of certification is presented along with empirical analysis suggesting that no notable difference existed between independent certification methods, although independent certification had significantly different effects than self-certification.Asymmetric information, Certification, Ordered probit, Organic produce, Agribusiness,

    United States Air Force Academy get-away-special flexible beam experiment

    Get PDF
    The Department of Astronautics at the United States Air Force Academy is currently planning to fly an experiment in a NASA Get-Away-Special (GAS) canister. The experiment was named the flex beam experiment. The primary technical objective of the flex beam experiment is to measure the damping of a thin beam in the vacuum and zero G environment of space. By measuring the damping in space, it is hoped to determine the amount of damping the beam normally experiences due to the gravitational forces present on Earth. This will allow validation of models which predict the dynamics of thin beams in the space environment. The experiment will also allow the Academy to develop and improve its ability to perform experiments within the confines of a NASA GAS canister. Several experiments, of limited technical difficulty, were flown by the Academy. More complex experiments are currently planned and it is hoped to learn techniques with each space shuttle flight

    GLUMIP 2.0: SAS/IML Software for Planning Internal Pilots

    Get PDF
    Internal pilot designs involve conducting interim power analysis (without interim data analysis) to modify the final sample size. Recently developed techniques have been described to avoid the type~I error rate inflation inherent to unadjusted hypothesis tests, while still providing the advantages of an internal pilot design. We present GLUMIP 2.0, the latest version of our free SAS/IML software for planning internal pilot studies in the general linear univariate model (GLUM) framework. The new analytic forms incorporated into the updated software solve many problems inherent to current internal pilot techniques for linear models with Gaussian errors. Hence, the GLUMIP 2.0 software makes it easy to perform exact power analysis for internal pilots under the GLUM framework with independent Gaussian errors and fixed predictors.

    Circular 104

    Get PDF

    Reducing in-stent restenosis therapeutic manipulation of miRNA in vascular remodeling and inflammation

    Get PDF
    Background: Drug-eluting stents reduce the incidence of in-stent restenosis, but they result in delayed arterial healing and are associated with a chronic inflammatory response and hypersensitivity reactions. Identifying novel interventions to enhance wound healing and reduce the inflammatory response may improve long-term clinical outcomes. Micro–ribonucleic acids (miRNAs) are noncoding small ribonucleic acids that play a prominent role in the initiation and resolution of inflammation after vascular injury.<p></p> Objectives: This study sought to identify miRNA regulation and function after implantation of bare-metal and drug-eluting stents.<p></p> Methods: Pig, mouse, and in vitro models were used to investigate the role of miRNA in in-stent restenosis.<p></p> Results: We documented a subset of inflammatory miRNAs activated after stenting in pigs, including the miR-21 stem loop miRNAs. Genetic ablation of the miR-21 stem loop attenuated neointimal formation in mice post-stenting. This occurred via enhanced levels of anti-inflammatory M2 macrophages coupled with an impaired sensitivity of smooth muscle cells to respond to vascular activation.<p></p> Conclusions: MiR-21 plays a prominent role in promoting vascular inflammation and remodeling after stent injury. MiRNA-mediated modulation of the inflammatory response post-stenting may have therapeutic potential to accelerate wound healing and enhance the clinical efficacy of stenting

    THE WHEAT AND STOCKER CATTLE ANALYZER: A MICROCOMPUTER DECISION AID FOR EVALUATING WHEAT PRODUCTION AND STOCKER CATTLE GRAZING DECISIONS

    Get PDF
    The Wheat and Stocker Cattle Analyzer is a microcomputer decision aid for evaluating interrelated wheat production and stocker cattle grazing decisions under yield, weight gain, and price uncertainty. An important feature of the model is that wheat commodity program provisions are incorporated into the analysis. A wide range of alternatives including wheat production for grain only, owned stocker cattle grazing, and wheat pasture leasing can be evaluated by the program.Crop Production/Industries, Livestock Production/Industries,
    • 

    corecore