881 research outputs found

    Compilation of rocket spin data. Volume 2 - Literature survey Final report, Nov. 1966 - Aug. 1968

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    Literature survey of acceleration spin effects on solid propellant rocket engine

    Compilation of rocket spin data. Volume 3 - Data evaluation and recommendations Final report, Nov. 1964 - Aug. 1968

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    Qualitative analysis of spin acceleration effects on solid propellant rocket engine performanc

    Farmer participation in radio campaigns for technology adoption: Lessons from AFFRI’s hybrid maize campaign in Mangochi, Malawi

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    This ethnographic study used focus group discussions to investigate and gather ideographical information about why statistics from the Nankumba region of Mangochi in Malawi, where, from 2008 to 2010, Farm Radio International implemented the African Farm Radio Research Initiative (AFRRI) - a meticulously and almost flawlessly planned hybrid maize variety promotion radio campaign - consistently showed that farmers preferred local to the promoted hybrid maize varieties before, during, and after the participatory community radio campaigns. The study found that in determining which maize varieties to opt for, farmers consider not only volume of yield per unit area but also taste, smell, flour extraction rate, and storability of the maize. The study further observes that preference of local maize varieties over hybrid is not restricted to rural farmers. Thus, farmer exposure to and participation in radio campaigns may increase awareness and knowledge as did the AFRRI campaign, but may not necessarily lead the farmers and consumers into adopting new maize varieties, technologies or innovations.Key words: radio campaign, participation, radio production, adoption, innovation, hybrid maize, Malaw

    The impact of electronic information resource use on research output: experiences from Universities in Tanzania

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    This paper examines the impact of the use of electronic information resources on research output in the universities in Tanzania. Research for this paper was conducted in five public universities in Tanzania with varied levels of access to electronic information resources. The selection of the sample universities was purposive. Data was collected using face-to-face interviews, questionnaires and key informant interviews. Analysis of data employed descriptive and quantitative techniques. Empirical data revealed that the use of online information resources has a positive impact on various research activities and milestones such as research proposal submission, research proposal funding, research report writing and journal article publishing. The results therefore provide empirical support for a positive relationship between the use of electronic information resources and research output and publishing in general. This was demonstrated in the increased number of proposals prepared, submitted and funded, research reports submitted, journal articles published and chapters in books and books published with increased access to and use of electronic information resources. Results also show that although researchers who are actually using the scholarly databases are small in number the core group of researchers using these resources is growing and the use of resources is becoming more frequent and diverse. The major challenges observed include ineffective marketing strategies on the availability of the resources, inadequate training of end users, questionable content relevance of some of the resources and issues of sustainability of access given high levels of donor dependency for subscriptions. Finally, limited variations in terms of intensity of use of resources were observed between junior and higher ranking academics; and younger and older members of faculty. The paper makes a number of recommendations

    Compilation of rocket spin data. Volume 1 - Acceleration test facilities Final report

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    Spin and centrifuge test facilities for testing solid rocket propellant engines - annotated bibliograph

    Work function determination of promising electrode materials for thermionic energy converters

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    The work function determinations of candidate materials for low temperature (1400 K) thermionics through vacuum emission tests are discussed. Two systems, a vacuum emission test vehicle and a thermionic emission microscope are used for emission measurements. Some nickel and cobalt based super alloys were preliminarily examined. High temperature physical properties and corrosion behavior of some super alloy candidates are presented. The corrosion behavior of sodium is of particular interest since topping cycles might use sodium heat transfer loops. A Marchuk tube was designed for plasma discharge studies with the carbide and possibly some super alloy samples. A series of metal carbides and other alloys were fabricated and tested in a special high temperature mass spectrometer. This information coupled with work function determinations was evaluated in an attempt to learn how electron bonding occurs in transition alloys

    Practicing neurosurgery in the United States

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    Journal ArticleCompared with other developed countries, the U.S. spends a high percentage of its gross domestic product on healthcare: 16 percent in 2005, up from 15 percent in 2004. This is far and away the greatest percentage of GDP spent on healthcare of any nation for which such data is collected. However, the high level of healthcare spending is not reflected in globally accepted indicators of quality such as comparatively longer life expectancy and lower infant mortality. Moreover, the U.S. government pays for the healthcare of less than half its population, and the percentage of uninsured people is a relatively high 15.3 percent

    The poverty impacts of improved cowpea varieties in Nigeria: a counterfactual analysis

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    Open Access Article; Published online: 12 June 2019Adoption of improved agricultural technologies has long been recognized as critical for reducing poverty through increased productivity, incomes, and asset accumulation. Using a nationally representative survey data from a sample of over 1500 households in Nigeria, this paper evaluates the impacts of adoption of improved cowpea varieties on income and asset poverty reduction using an endogenous switching regression model. The results showed that adoption of improved cowpea varieties increased per capita household income and asset ownership by 17 and 24 percentage points, respectively. The results based on the observed and counterfactual income and asset distributions further showed that adoption reduced both income poverty and asset poverty by 5 percentage points. The paper concludes with a discussion of the policy options for increasing adoption and impacts of improved cowpea varieties in Nigeria

    Correcting CIV-Based Virial Black Hole Masses

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    The CIV broad emission line is visible in optical spectra to redshifts exceeding z~5. CIV has long been known to exhibit significant displacements to the blue and these `blueshifts' almost certainly signal the presence of strong outflows. As a consequence, single-epoch virial black hole (BH) mass estimates derived from CIV velocity-widths are known to be systematically biased compared to masses from the hydrogen Balmer lines. Using a large sample of 230 high-luminosity (log LBolL_{\rm Bol} = 45.5-48 erg/s), redshift 1.5<z<4.0 quasars with both CIV and Balmer line spectra, we have quantified the bias in CIV BH masses as a function of the CIV blueshift. CIV BH masses are shown to be a factor of five larger than the corresponding Balmer-line masses at CIV blueshifts of 3000 km/s and are over-estimated by almost an order of magnitude at the most extreme blueshifts, >5000 km/s. Using the monotonically increasing relationship between the CIV blueshift and the mass ratio BH(CIV)/BH(Hα\alpha) we derive an empirical correction to all CIV BH-masses. The scatter between the corrected CIV masses and the Balmer masses is 0.24 dex at low CIV blueshifts (~0 km/s) and just 0.10 dex at high blueshifts (~3000 km/s), compared to 0.40 dex before the correction. The correction depends only on the CIV line properties - i.e. full-width at half maximum and blueshift - and can therefore be applied to all quasars where CIV emission line properties have been measured, enabling the derivation of un-biased virial BH mass estimates for the majority of high-luminosity, high-redshift, spectroscopically confirmed quasars in the literature.Comment: Accepted for publication in MNRAS; fixed typo in CIV wavelengt
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