1,442 research outputs found

    Manufacturing an Airplane

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    A case study of open source and public participation in catalyzing social innovations

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    Our study investigates the use of a new open source platform in catalyzing social innovations and participation of its members over time. We empirically examined how the nature of project designs and social pressure affect contribution to the open source platform. In the twenty-one projects (3,998 contributions) from 2004 to 2009, we find that the average number of contributions is higher when the projects are highly visible, when the project is designed to require specific skills from participants, and when it requires outcome measurement from participants' proposals. Also, we verified that actors join collective action when they believe their contribution is meaningful and they would stop when they believe their contribution could be marginal. These results provide implications for open source platform design in the philanthropic sector. © 2010 IEEE.published_or_final_versio

    Investigation of the growth of garnet films by liquid phase epitaxy

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    Liquid phase expitaxy was investigated to determine its applicability to fabricating magnetic rare earth garnet films for spacecraft data recording systems. Two mixed garnet systems were investigated in detail: (1) Gd-Y and (2) Eu-Yb-Y. All films were deposited on Gd3Ga5012 substrates. The uniaxial anisotropy of the Gd-Y garnets is primarily stress-induced. These garnets are characterized by high-domain wall mobility, low coercivity and modest anisotropy. Characteristic length was found to be relatively sensitive to temperature. The Eu-Yb-Y garnets exhibit acceptable mobilities, good temperature stability and reasonable quality factors. The uniaxial anisotropy of these garnets is primarily growth-induced. The system is well suited for compositional "tailoring" to optimize specific desirable properties. Liquid phase epitaxy can be used to deposit Gd3Ga5012 spacing layers on magnetic garnet films and this arrangement possesses certain advantages over more conventional magnetic filmspacing layer combinations. However, it cannot be used if the magnetic film is to be ion implanted

    The Correlation of Dyslipidemia with the Extent of Coronary Artery Disease in the Multiethnic Study of Atherosclerosis.

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    BackgroundThe extent of coronary artery calcium (CAC) improves cardiovascular disease (CVD) risk prediction. The association between common dyslipidemias (combined hyperlipidemia, simple hypercholesterolemia, metabolic Syndrome (MetS), isolated low high-density lipoprotein cholesterol, and isolated hypertriglyceridemia) compared with normolipidemia and the risk of multivessel CAC is underinvestigated.ObjectivesTo determine whether there is an association between common dyslipidemias compared with normolipidemia, and the extent of coronary artery involvement among MESA participants who were free of clinical cardiovascular disease at baseline.MethodsIn a cross-sectional analysis, 4,917 MESA participants were classified into six groups defined by specific LDL-c, HDL-c, or triglyceride cutoff points. Multivessel CAC was defined as involvement of at least 2 coronary arteries. Multivariate Poisson regression analysis evaluated the association of each group with multivessel CAC after adjusting for CVD risk factors.ResultsUnadjusted analysis showed that all groups except hypertriglyceridemia had statistically significant prevalence ratios of having multivessel CAC as compared to the normolipidemia group. The same groups maintained statistical significance prevalence ratios with multivariate analysis adjusting for other risk factors including Agatston CAC score [combined hyperlipidemia 1.41 (1.06-1.87), hypercholesterolemia 1.55 (1.26-1.92), MetS 1.28 (1.09-1.51), and low HDL-c 1.20 (1.02-1.40)].ConclusionCombined hyperlipidemia, simple hypercholesterolemia, MetS, and low HDL-c were associated with multivessel coronary artery disease independent of CVD risk factors and CAC score. These findings may lay the groundwork for further analysis of the underlying mechanisms in the observed relationship, as well as for the development of clinical strategies for primary prevention

    Occupational Health and Safety Management Systems Assessment Training

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    An occupational health and safety management system (OHSMS) is required for all Federal agencies by Executive Order 12196 – Occupational safety and health programs for Federal employees. Development of the Occupational Health and Safety Management Systems Assessment Training Manual was supported jointly by the U.S. Veterans Health Administration (VHA) and the Occupational Safety and Health Administration (OSHA). The manual was designed to be used in the training of government personnel on how to assess the OHSMS of Federal establishments and agencies. The manual is organized sequentially through each step in the process of conducting an OHSMS assessment. Trainees start by learning about how to prepare for an assessment and the training concludes with a discussion on how to incorporate multiple establishments’ OHSMS assessment scores into an agency-wide assessment. Each module includes exercises designed to aid Federal personnel in learning the skills necessary to complete an OHSMS assessment

    Peregrine Falcon Eggs: Egg Size, Hatchling Sex, and Clutch Sex Ratios

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    Eggs (n = 367) collected from wild Peregrine Falcon (Falco peregrinus anatum) nests between 1976 and 1990 in Colorado and New Mexico were artificially incubated and hatched. We retrospectively examined these data for variation in egg length, breadth, and initial mass of hatchlings to resolve questions about relationships among egg size, chick size, and sex; and egg size related to first and second clutches and years. Egg length and breadth were significantly related to chick mass at hatching. Neither egg size nor hatchling mass were related to sex. Egg breadth slightly increased and then decreased over the years eggs were collected, which possibly reflects a re-established and then aging wild falcon population or other environmental variation. We also evaluated clutch sex ratios relative to theory based on sexual size dimorphism and local resource competition. Sex ratios did not significantly differ from 1:1 within first or second clutches separately or when combined. Thus, Peregrine Falcons in this population apparently did not skew clutch sex ratios in accordance with local resource competition or Fisherian theory

    The factorization method for inverse scattering from periodic inhomogeneous media

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    This book addresses the identification of the shape of penetrable periodic media by means of scattered time-harmonic waves. Mathematically, this is about the determination of the support of a function which occurs in the governing equations. Our theoretical analysis shows that this problem can be strictly solved for acoustic as well as for electromagnetic radiation by the so-called Factorization Method. We apply this method to reconstruct a couple of media from numerically simulated field data
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