84,917 research outputs found

    Test summary for advanced H2 cycle NI-CD cell

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    To improve operational tolerances and mass, the H2 gas recombination design provisions of the Ni-H2 system were incorporated into the sealed Ni-Cd system. Produced is a cell design capable of operating on the H2 cycle versus the normal O2 cycle. Three test cells have now completed approximately 4,330 LEO (90 minute) cycles at 20 percent depth of discharge (DOD). Performance remains stable although one cell exhibited a temporary pressure anomaly

    Parents and children talk: the family dynamics of English language proficiency

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    This paper extends the analysis of the acquisition of destination language proficiency among immigrants by explicitly incorporating dynamics among family members— mother, father and children. Single equation, bivariate, and four-state (multivariate) probit analyses are employed. Immigrant English language skills are greater the younger the age at migration, the longer the duration of residence, the higher the level of education, and for immigrants not from Asia. Large positive correlations in the unmeasured determinants of proficiency exist between spouses, between siblings, and between parents and children, although the latter relationship is stronger for the mother

    Policy Barriers to School Improvement: What's Real and What's Imagined?

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    Some of the most promising reforms are happening where school leaders are thinking differently about how to get the strongest student outcomes from the limited resources available. But even principals who use their autonomy to aggressively reallocate resources say that persistent district, state, and federal barriers prohibit them from doing more.What are these barriers? What do they block principals from doing? Is there a way around them?CRPE researchers probed these questions with principals in three states (NH, CT, MD). These principals cited numerous district, state, and federal barriers standing in the way of school improvement. The barriers, 128 in all, fell into three categories: 1) barriers to instructional innovations, 2) barriers to allocating resources differently, and 3) barriers to improving teacher quality.Upon investigation, researchers found that principals have far more authority than they think. Only 31% of the barriers cited were "real" -- immovable statutes, policies, or managerial directives that bring the threat of real consequences if broken.The report recommends educating principals on the authority they already possess, to help them find workarounds to onerous rules. The report also outlines a number of specific state and district policy changes to grant schools the autonomy they need to improve student outcomes

    Reading Habits in Different Communities

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    Reading is foundational to learning and the information acquisition upon which people make decisions. For centuries, the capacity to read has been a benchmark of literacy and involvement in community life. In the 21st Century, across all types of U.S. communities, reading is a common activity that is pursued in myriad ways. As technology and the digital world expand and offer new types of reading opportunities, residents of urban, suburban, and rural communities at times experience reading and e-reading differently. In the most meaningful ways, these differences are associated with the demographic composition of differentkinds of communities -- the age of the population, their overall level of educational attainment, and the general level of household income.Several surveys by the Pew Research Center's Internet & American Life Project reveal interesting variations among communities in the way their residents read and use reading-related technology and institutions

    Construction of Readership in \u3cem\u3eEbony\u3c/em\u3e, \u3cem\u3eEssence\u3c/em\u3e, and \u3cem\u3eO, the Oprah Magazine\u3c/em\u3e

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    Miller et al examine the construction of readership in Ebony, Essence and O, The Oprah magazine, three popular magazines that purport to be a vehicle of identity and awareness for their target audience. Upon evaluation, they found that Ebony and Essence both challenge the hegemonic process with the incorporation of cultural artifacts that call upon collective memory to form reader association

    Transverse Quark Distribution in Mesons - QCD Sum Rule Approach -

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    QCD sum rules are used to compute the first few moments of the mesonic quark momentum. Transverse, longitudinal and mixed transverse-longitudinal components are examined. The transverse size of the pion is shown to be dictated by the gluon condensate, even though the mass and the longitudinal distribution are dominated by the quark condensate. The implications of our results for color transparency physics and finite temperature QCD are discussed.Comment: 8 pages, Latex, Univ. of Washington preprint DOE/ER/40427-24-N9

    Multi-mission Ni-H2 battery cells for the 1990's

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    A sufficient production, test and operational database is now available to permit design technology optimization for the next decade. The evolved battery cell design features standardized technology intended to support multiple type missions (e.g., both GEO and LEO). Design analysis and validation test cells demonstrate that improved performance plus attractive specific-energy characteristics will be achieved

    Stochastic Infinite Horizon Forecasts for Social Security and Related Studies

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    This paper consists of three reports on stochastic forecasting for Social Security, on infinite horizons, immigration, and structural time series models. 1) In our preferred stochastic immigration forecast, total net immigration drops from current levels down to about one million by 2020, then slowly rises to 1.2 million at the end of the century, with 95% probability bounds of 800,000 to 1.8 million at the century's end. Adding stochastic immigration makes little difference to the probability distribution of the old age dependency ratio. 2) We incorporate parameter uncertainty, stochastic trends, and uncertain ultimate levels in stochastic models of wage growth and fertility. These changes sometimes substantially affect the probability distributions of the individual input forecasts, but they make relatively little difference when embedded in the more fully stochastic Social Security projection. 3) Using a 500-year stochastic projection, we estimate an infinite horizon balance of -5.15% of payroll, compared to the -3.5% of the 2004 Trustees Report, probably reflecting different mortality projections. Our 95% probability interval bounds are -10.5 and -1.3%. Such forecasts, which reflect only "routine" uncertainty, have many problems but nonetheless seem worthwhile.

    Multi-mission Ni-H2 battery cell for the 1990's

    Get PDF
    A sufficient production, test and operational database is now available to permit design technology optimization for the next decade. The evolved battery cell design features standardized technology intended to support multiple type missions (e.g., both GEO and LEO). Design analyses and validation test cells demonstrate improved performance plus attractive specific-energy characteristics will be achieved
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