701 research outputs found

    Wind-tunnel investigation of thermal and pressure environments in the base of the Saturn S-IC booster from Mach 0.1 to 3.5

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    Wind tunnel testing of thermal and pressure in base of Saturn S-IC booste

    Probabilistic Inferences for the Sample Pearson Product Moment Correlation

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    Fisher’s correlation transformation is commonly used to draw inferences regarding the reliability of tests comprised of dichotomous or polytomous items. It is illustrated theoretically and empirically that omitting test length and difficulty results in inflated Type I error. An empirically unbiased correction is introduced within the transformation that is applicable under any test conditions

    Finite Mixture Model Specifications Accommodating Treatment Nonresponse in Experimental Research

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    For researchers exploring causal inferences with simple two group experimental designs, results are confounded when using common statistical methods and further are unsuitable in cases of treatment nonresponse. In signal processing, researchers have successfully extracted multiple signals from data streams with Gaussian mixture models, where their use is well matched to accommodate researchers in this predicament. While the mathematics underpinning models in either application remains unchanged, there are stark differences. In signal processing, results are definitively evaluated assessing whether extracted signals are interpretable. Such obvious feedback is unavailable to researchers seeking causal inference who instead rely on empirical evidence from inferential statements regarding mean differences, as done in analysis of variance (ANOVA). Two group experimental designs do provide added benefit by anchoring treatment nonrespondents' distributional response properties from the control group. Obtaining empirical evidence supporting treatment nonresponse, however, can be extremely challenging. First, if indeed nonresponse exists, then basic population means, ANOVA or repeated measures tests cannot be used because of a violation of the identical distribution property required for each method. Secondly, the mixing parameter or proportion of nonresponse is bounded between 0 and 1, so does not subscribe to normal distribution theory to enable inference by common methods. This dissertation introduces and evaluates the performance of an information-based methodology as a more extensible and informative alternative to statistical tests of population means while addressing treatment nonresponse. Gaussian distributions are not required under this methodology which simultaneously provides empirical evidence through model selection regarding treatment nonresponse, equality of population means, and equality of variance hypotheses. The use of information criteria measures as an omnibus assessment of a set of mixture and non-mixture models within a maximum likelihood framework eliminates the need for a Newton-Pearson framework of probabilistic inferences on individual parameter estimates. This dissertation assesses performance in recapturing population conditions for hypotheses' conclusions, parameter accuracy, and class membership. More complex extensions addressing multiple treatments, multiple responses within a treatment, a priori consideration of covariates, and multivariate responses within a latent framework are also introduced

    Influence of Vineyard Management Practices and Cultivar on Grape Berry Properties

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    Factors influencing berry properties of grapes are numerous and include environmental factors, management practices, and cultivar differences. Vintners are continually seeking ways to modify these variables to optimize harvest dates and ensure superior fruit quality. The most widely accepted and commonly used measures of berry maturity include pH,soluble solids concentration (SSC), and titratable acidity

    Going to the exclusive show : exhibition strategies and moviegoing memories of Disneys animated feature films in Ghent (1937-1982)

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    This is a case study of the exploitation and experience of Disney's animated feature films from the 1930s to the 1980s in Ghent (Belgium). It is a historical study of programming practices and financial strategies which constructed childhood memories on watching Disney. The study is a contribution to a historical understanding of the implications of global distribution of film as cultural products and the counter pull of localism. Using a multi-method approach, the argument is made that the scarce screenings were strategically programmed to uplift the moviegoing experience into something out of the ordinary in everyday life. Programming and revenue data characterize the screenings as exclusive and generating high intakes. Consequently, the remembered screenings did not exhale an easy accessible social status nor an image of pervasiveness of popular childhood film, contradictory to conventional accounts of Disney's ubiquity in popular culture

    Reducing pesticide use in Iowa vineyards: Alternatives to herbicides for vineyard weed management

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    Mulches can play a role in vineyard management. This project explored the optimum uses and practices for applying various mulches to grape agroecosystems

    Experience of developing Twitter-based communities of practice in higher education

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    This article presents the results of a case study of the use of a microblogging tool by a university academic to increase their knowledge and experience of social media for educational purposes. The academic had the role of digital steward in a university and attempted to use microblogging (Twitter) to increase professional contacts within the framework of a community of practice. Several types of data were collected and analysed. These included the structure of the network arising from the links formed with others by microblogging, the similarity of stated interests between the academic and others in the network, and the contents of postings such as their external references. It was found that a personal network had been established, with some of the characteristics of a community of practice. The activity demonstrated the utility of social media in supporting the professional development of academic staff using technology

    Social Interactions vs Revisions, What is important for Promotion in Wikipedia?

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    In epistemic community, people are said to be selected on their knowledge contribution to the project (articles, codes, etc.) However, the socialization process is an important factor for inclusion, sustainability as a contributor, and promotion. Finally, what does matter to be promoted? being a good contributor? being a good animator? knowing the boss? We explore this question looking at the process of election for administrator in the English Wikipedia community. We modeled the candidates according to their revisions and/or social attributes. These attributes are used to construct a predictive model of promotion success, based on the candidates's past behavior, computed thanks to a random forest algorithm. Our model combining knowledge contribution variables and social networking variables successfully explain 78% of the results which is better than the former models. It also helps to refine the criterion for election. If the number of knowledge contributions is the most important element, social interactions come close second to explain the election. But being connected with the future peers (the admins) can make the difference between success and failure, making this epistemic community a very social community too

    Scaling of the F_2 structure function in nuclei and quark distributions at x>1

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    We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for x>1x>1, which is sensitive to short range contributions to the nuclear wave-function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the `super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in ^2H and ^3He, but nearly identical for all heavier nuclei.Comment: 5 pages, 4 figures, to be submitted to physical revie
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