10,424 research outputs found

    Predictions of Cockpit Simulator Experimental Outcome Using System Models

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    This study involved predicting the outcome of a cockpit simulator experiment where pilots used cockpit displays of traffic information (CDTI) to establish and maintain in-trail spacing behind a lead aircraft during approach. The experiments were run on the NASA Ames Research Center multicab cockpit simulator facility. Prior to the experiments, a mathematical model of the pilot/aircraft/CDTI flight system was developed which included relative in-trail and vertical dynamics between aircraft in the approach string. This model was used to construct a digital simulation of the string dynamics including response to initial position errors. The model was then used to predict the outcome of the in-trail following cockpit simulator experiments. Outcome included performance and sensitivity to different separation criteria. The experimental results were then used to evaluate the model and its prediction accuracy. Lessons learned in this modeling and prediction study are noted

    Comparative genetic resistance to Ascaridia galli infections of 4 different commercial layer-lines

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    1. The objective of the study was to compare the establishment and effect of Ascaridia galli infections in 4 different layer-lines. 2. A total of 160 birds comprising 4 different commercial layer-lines, ISA Brown, New Hampshire, Skalborg and a cross of New Hampshire(NH) and Skalborg (Sk), were infected with A. galli eggs. The birds were examined for the presence of parasite eggs and parasites at weeks 3, 6 and 9 post infection (pi). 3. At week 6 pi the chickens of the NH line harboured more larvae compared with the three other lines. The Sk line chickens excreted more A. galli eggs throughout the study compared with the other lines. Female worms in the Sk line were more fecund than the worms in the other lines. Male and female worms recovered from the Sk line at week 9 pi were longer. Male worms recovered from the NH line 6 weeks pi were shorter than male worms from the other lines. Female worms recovered from the NH line were shorter than the female worms from the ISA line and the Sk line. No differences were seen in weight gain among the 4 lines. 4. The results suggest that genetic factors are involved in the establishment and survival of A. galli in the intestine of layers. Further studies are needed to elucidate the genetic mechanisms behind the observed parasitological findings

    Herding cats: observing live coding in the wild

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    After a momentous decade of live coding activities, this paper seeks to explore the practice with the aim of situating it in the history of contemporary arts and music. The article introduces several key points of investigation in live coding research and discusses some examples of how live coding practitioners engage with these points in their system design and performances. In the light of the extremely diverse manifestations of live coding activities, the problem of defining the practice is discussed, and the question raised whether live coding will actually be necessary as an independent category

    Prenatal exposure to selective serotonin reuptake inhibitors and childhood overweight at 7 years of age

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    Abstract not availableLuke E. Grzeskowiak, Andrew L. Gilbert, Thorkild I. A. Sørensen, Jørn Olsen, Henrik T. Sørensen, Lars H. Pedersen, Janna L. Morriso

    Positive Effects of Negative Publicity: When Negative Reviews Increase Sales

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    Can negative information about a product increase sales, and if so, when? Although popular wisdom suggests that “any publicity is good publicity,” prior research has demonstrated only downsides to negative press. Negative reviews or word of mouth, for example, have been found to hurt product evaluation and sales. Using a combination of econometric analysis and experimental methods, we unify these perspectives to delineate contexts under which negative publicity about a product will have positive versus negative effects. Specifically, we argue that negative publicity can increase purchase likelihood and sales by increasing product awareness. Consequently, negative publicity should have differential effects on established versus unknown products. Three studies support this perspective. Whereas a negative review in the New York Times hurt sales of books by well-known authors, for example, it increased sales of books that had lower prior awareness. The studies further underscore the importance of a gap between publicity and purchase occasion and the mediating role of increased awareness in these effects

    Partial coherence in the core/halo picture of Bose-Einstein n-particle correlations

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    We study the influence of a possible coherent component in the boson source on the two-, three- and nn-particle correlation functions in a generalized core/halo type of boson-emitting source. In particular, a simple formula is presented for the strengh of the nn-particle correlation functions for such systems. Graph rules are obtained to evaluate the correlation functions of arbitrary high order. The importance of experimental determination of the 4-th and 5-th order Bose-Einstein correlation function is emphasized.Comment: 15 pages, Latex, 3 EPS files, 1 tabl

    Fluctuation and flow probes of early-time correlations in relativistic heavy ion collisions

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    Fluctuation and correlation observables are often measured using multi-particle correlation methods and therefore mutually probe the origins of genuine correlations present in multi-particle distribution functions. We investigate the common influence of correlations arising from the spatially inhomogeneous initial state on multiplicity and momentum fluctuations as well as flow fluctuations. Although these observables reflect different aspects of the initial state, taken together, they can constrain a correlation scale set at the earliest moments of the collision. We calculate both the correlation scale in an initial stage Glasma flux tube picture and the modification to these correlations from later stage hydrodynamic flow and find quantitative agreement with experimental measurements over a range of collision systems and energies.Comment: Proceedings of the 28th Winter Workshop on Nuclear Dynamics, Dorado del Mar, Puerto Rico, April 7-14, 201

    Low temperature spin diffusion in the one-dimensional quantum O(3)O(3) nonlinear σ\sigma-model

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    An effective, low temperature, classical model for spin transport in the one-dimensional, gapped, quantum O(3)O(3) non-linear σ\sigma-model is developed. Its correlators are obtained by a mapping to a model solved earlier by Jepsen. We obtain universal functions for the ballistic-to-diffusive crossover and the value of the spin diffusion constant, and these are claimed to be exact at low temperatures. Implications for experiments on one-dimensional insulators with a spin gap are noted.Comment: 4 pages including 3 eps-figures, Revte

    Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers with nano-supports

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    We demonstrate a new class of hollow-core Bragg fibers that are composed of concentric cylindrical silica rings separated by nanoscale support bridges. We theoretically predict and experimentally observe hollow-core confinement over an octave frequency range. The bandwidth of bandgap guiding in this new class of Bragg fibers exceeds that of other hollow-core fibers reported in the literature. With only three rings of silica cladding layers, these Bragg fibers achieve propagation loss of the order of 1 dB/m.Comment: 9 pages including 5 figure
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