10,356 research outputs found

    An implicit method for the calculation of inlet flow fields

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    Inlet flow fields are calculated by an implicit, time marching procedure to solve the thin layer Navier-Stokes equations formulated in body fitted coordinates. Because the method can be used for a flow field with both subsonic and supersonic regions, it is applicable to subcritical as well as supercritical inlet operation. Results are presented and discussed for an inlet of current design practice. Results include inviscid calculations performed for supercritical inlet operation with uniform and nonuniform inflow boundary conditions as well as for subcritical inlet operation with uniform inflow boundary conditions. Results for viscous calculations performed for supercritical inlet operation with uniform inflow boundary conditions are also discussed

    Calculation of two-dimensional inlet flow fields by an implicit method including viscous effects: User's manual

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    Inlet flow fields for airbreathing missiles are calculated by the adaptation of a two dimensional computational method developed for the flow around airfoils. A supersonic free stream is assumed to allow the forebody calculation to be uncoupled from the inlet calculation. The inlet calculation employs an implicit, time marching finite difference procedure to solve the thin layer Navier-Stokes equations formulated in body fitted coordinates. The mathematical formulation of the problem and the solution algorithm are given. Numerical stability and accuracy as well as the initial and boundary conditions used are discussed. Instructions for program use and operation along with the overall program logic are also given

    Measuring the burden of treatment for chronic disease: implications of a scoping review of the literature

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    Background: Although there has been growing research on the burden of treatment, the current state of evidence on measuring this concept is unknown. This scoping review aimed to provide an overview of the current state of knowledge as well as clear recommendations for future research, within the context of chronic disease. Methods: Four health-based databases, Scopus, CINAHL, Medline, and PsychInfo, were comprehensively searched for peer-reviewed articles published between the periods of 2000–2016. Titles and abstracts were independently read by two authors. All discrepancies between the authors were resolved by a third author. Data was extracted using a standardized proforma and a comparison analysis was used in order to explore the key treatment burden measures and categorize them into three groups. Results: Database searching identified 1458 potential papers. After removal of duplications, and irrelevant articles by title, 1102 abstracts remained. An additional 22 papers were added via snowball searching. In the end, 101 full papers were included in the review. A large number of the studies involved quantitative measures and conceptualizations of treatment burden (n = 64; 63.4%), and were conducted in North America (n = 49; 48.5%). There was significant variation in how the treatment burden experienced by those with chronic disease was operationalized and measured. Conclusion: Despite significant work, there is still much ground to cover to comprehensively measure treatment burden for chronic disease. Greater qualitative focus, more research with cultural and minority populations, a larger emphasis on longitudinal studies and the consideration of the potential effects of “identity” on treatment burden, should be considered

    Binary-Binary Interactions and the Formation of the PSR B1620-26 Triple System in M4

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    The hierarchical triple system containing the millisecond pulsar PSR B1620-26 in M4 is the first triple star system ever detected in a globular cluster. Such systems should form in globular clusters as a result of dynamical interactions between binaries. We propose that the triple system containing PSR B1620-26 formed through an exchange interaction between a wide primordial binary and a {\it pre-existing\/} binary millisecond pulsar. This scenario would have the advantage of reconciling the 109\sim10^9\,yr timing age of the pulsar with the much shorter lifetime of the triple system in the core of M4.Comment: 13 pages, uuencoded compressed postscript with figures, IASSNS-AST 94/4

    CLIMATE AND SCALE IN ECONOMIC GROWTH

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    This paper introduces new data on climatic conditions to empirical tests of growth theories. We find that, since 1960, temperate countries have converged towards high levels of income while tropical nations have converged towards various income levels associated with economic scale and the extent of the market. These results hold for a wide range of tests. A plausible explanation is that temperate regions' growth was assisted by their climate, perhaps historically for their transition out of agriculture into sectors whose productivity converges across countries, while tropical countries' growth is relatively more dependent on gains from specialization and trade.International Development,

    Profit Sharing Between Governments and Multinationals in Natural Resource Extraction: Evidence From a Firm-Level Panel

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    The "fairness" of negotiations between countries and resource extracting firms is subject to many accusations and counter-accusations and may be argued, in many instances, to impact the subsequent economic benefit to a host country from extraction. This paper examines the role of host country governance on the share of government take from extraction revenue. We attempt to disentangle a number of competing hypotheses regarding the relationship between governance and government take using panel data for US resource extracting multinational corporations (MNCs) operating abroad from the Bureau of Economic Analysis of the US Department of Commerce over 1982-1999. Using fixed effects regression, we find a statistically significant positive impact of institutional quality on government take. The nature of this relationship -- whether this represents the result of a "corruption premium" paid by US MNCs or the exploitation of poor governance in negotiating government take -- is not completely clear. The evidence presented does, however, indicate that potential forms of bargaining power other than institutional quality (e.g., outside options to the deal) do increase government take, indicating that bargaining power may nonetheless be an important factor.

    Africa's Growth Trap: A Political-Economy Model of Taxation, R&D and Investment

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    Why do so many African governments consistently impose high tax rates and make little investment in productive public goods, when alternative policies could yield greater tax revenues and higher national income? We posit and test an intertemporal political economy model in which the government sets tax and R&D levels while investors respond with production. Equilibrium policy and growth rates depend on initial cost structure. We find that in many (but not all) African countries, low tax/high investment regimes would be time-inconsistent. For pro-growth policies to become sustainable, commitment mechanisms or new production techniques would be needed.time consistency, agricultural policy, economic growth

    A supersonic three-dimensional code for flow over blunt bodies: Program documentation and test cases

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    The use of a computer code for the calculation of steady, supersonic, three dimensional, inviscid flow over blunt bodies is illustrated. Input and output are given and explained for two cases: a pointed code of 20 deg half angle at 15 deg angle of attack in a free stream with M sub infinite = 7, and a cone-ogive-cylinder at 10 deg angle of attack with M sub infinite = 2.86. A source listing of the computer code is provided

    Outsourcing Jobs? Multinationals and US Employment

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    Critics of globalization claim that US manufacturing firms are being driven to shift employment abroad by the prospects of cheaper labor. Others argue that the availability of low-wage labor has allowed US based firms to survive and even prosper. Yet evidence for either hypothesis, beyond anecdotes, is slim. Using firm-level data collected by the US Bureau of Economic Analysis (BEA), we estimate the impact on US manufacturing employment of changes in foreign affiliate wages, controlling for changing demand conditions and technological change. We find that the evidence supports both perspectives on globalization. For firms most likely to perform the same tasks in foreign affiliates and at home ("horizontal" foreign investment), foreign and domestic employees appear to be substitutes. For these firms, lower wages in affiliate locations are associated with lower employment in the US. However, for firms which do significantly different tasks at home and abroad ("vertical" foreign investment), foreign and domestic employment are complements. For vertical foreign investment, lower wages abroad are associated with higher US manufacturing employment. These offsetting effects may be combined to show that offshoring is associated with a quantitatively small decline in manufacturing employment. Other factors, such as declining prices for consumer goods, import competition, and falling prices for investment goods (which substitute for labor) play a more important role.
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