6,851 research outputs found

    The GPRIME approach to finite element modeling

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    GPRIME, an interactive modeling system, runs on the CDC 6000 computers and the DEC VAX 11/780 minicomputer. This system includes three components: (1) GPRIME, a user friendly geometric language and a processor to translate that language into geometric entities, (2) GGEN, an interactive data generator for 2-D models; and (3) SOLIDGEN, a 3-D solid modeling program. Each component has a computer user interface of an extensive command set. All of these programs make use of a comprehensive B-spline mathematics subroutine library, which can be used for a wide variety of interpolation problems and other geometric calculations. Many other user aids, such as automatic saving of the geometric and finite element data bases and hidden line removal, are available. This interactive finite element modeling capability can produce a complete finite element model, producing an output file of grid and element data

    Ultrastructural, Cytochemical, and Immunocytochemical Studies on Bone and its Interfaces

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    Bone cells possess the ability to synthesize, secrete and direct the assembly and maintenance of extracellular matrix to form a functionally rigid and/or weight-bearing mineralized tissue complex, the skeleton. The skeleton not only supports and protects the organs and tissues of the body, but also acts as a mineral ion reservoir for maintaining systemic calcium balance (calcium homeostasis). The remarkable biological precision necessary for the formation, turnover and constant adaptation of bone to external mechanical forces is a dynamic process requiring a coordinated cellular effort relying on a variety of cell-cell and cell-matrix/mineral interactions. Indeed, cell-matrix interfaces found in a variety of locations in bone are sites potentially rich in signalling mechanisms related to bone modeling and remodeling. Detailed examination of the structure, composition and function of bone cells, and the extracellular matrix they produce and continuously remodel, is a complex task for such a mineralized tissue and requires integration and correlation of data from numerous sources. Various morphological approaches have added significantly to our understanding of bone form and function, and have allowed us to partly unravel some of the complex cellmatrix-mineral associations that occur during osteogenesis. In this context, the present article reviews some of our recent ultrastructural, cytochemical and immunocytochemical data on mammalian and avian intramembranous and endochondral bone formation (modeling) and turnover (remodeling)

    The Propagation and Survival of Interstellar Grains

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    In this paper we discuss the propagation of dust through the interstellar medium (ISM), and describe the destructive effects of stellar winds, jets, and supernova shock waves on interstellar dust. We review the probability that grains formed in stellar outflows or supernovae survive processing in and propagation through the ISM, and incorporate themselves relatively unprocessed into meteoritic bodies in the solar system. We show that very large (radii >= 5 micron) and very small grains (radii <= 100 Angstrom) with sizes similar to the pre-solar SiC and diamond grains extracted from meteorites, can survive the passage through 100\kms shock waves relatively unscathed. High velocity (>= 250 km/s) shocks destroy dust efficiently. However, a small (~10%) fraction of the stardust never encountered such fast shocks before incorporation into the solar system. All grains should therefore retain traces of their passage through interstellar shocks during their propagation through the ISM. The grain surfaces should show evidence of processing due to sputtering and pitting due to small grain cratering collisions on the micron-sized grains. This conclusion seems to be in conflict with the evidence from the large grains recovered from meteorites which seem to show little interstellar processing.Comment: 19 pages, 5 figures (.eps), LaTeX, to appear in "Astrophysical Implications of the Laboratory Study of Presolar Materials" AIP Conference Proceedings, 1997 T.J. Bernatowicz and E. Zinner (eds.

    Far-infrared rotational emission by carbon monoxide

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    Accurate theoretical collisional excitation rates are used to determine the emissivities of CO rotational lines 10 to the 4th power/cu cm n(H2), 100 K T 2000 K, and J 50. An approximate analytic expression for the emissitivities which is valid over most of this region is obtained. Population inversions in the lower rotational levels occur for densities n(H2) approximately 10 (to the 3rd to 5th power)/cu cm and temperatures T approximately 50 K. Interstellar shocks observed edge on are a potential source of millimeter wave CO maser emission. The CO rotational cooling function suggested by Hollenbach and McKee (1979) is verified, and accurate numerical values given. Application of these results to other linear molecules should be straightforward

    What might Brexit mean for British tourists travelling to the rest of Europe?

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    Brexit will have profound implications for British tourists visiting the rest of the European Union, in particular because of the likely loss of coverage of healthcare should they be injured or fall ill. This paper compares the cost of travel insurance within the EU and in comparable countries outside it, asking how it varies by age and pre-existing conditions. Fictitious patients, differing by age, pre-existing condition, and destination (France, an EU Member State; Israel and Canada, two high income non-EU frequent destinations) were entered into an insurance price comparison website to assess the influence of these characteristics on prices quoted. Cost of travel insurance increases with age, pre-existing health conditions and by destination. In those with no pre-existing conditions, there is a marked difference between France, where the cost rises steadily with age, and Israel and Canada, where there is a sharp increase after age 75. For individuals with any one pre-existing condition, there is no similar jump in cost but rather a progressive increase with age, although the rate of increase accelerates as the individuals concerned get older. For all travellers, the cost of insurance is highest for Canada and lowest for France. At present, pre-existing health conditions in British tourists travelling in the rest of the EU are covered by the European Health Insurance Card. With the UK's probable exit from the EU and almost certain loss of this coverage, travellers in the older age groups may have to pay much more for their travel insurance, with some possibly tempted to forgo travel insurance coverage because of the cost. It is essential that health professionals understand how leaving the EU may impact on those seeking their advice

    A novel method of supplying nutrients permits predictable shoot growth and root: shoot ratios of pre-transplant bedding plants

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    BACKGROUND AND AIMS: Growth of bedding plants, in small peat plugs, relies on nutrients in the irrigation solution. The object of the study was to find a way of modifying the nutrient supply so that good-quality seedlings can be grown rapidly and yet have the high root : shoot ratios essential for efficient transplanting. METHODS: A new procedure was devised in which the concentrations of nutrients in the irrigation solution were modified during growth according to changing plant demand, instead of maintaining the same concentrations throughout growth. The new procedure depends on published algorithms for the dependence of growth rate and optimal plant nutrient concentrations on shoot dry weight Ws (g m–2), and on measuring evapotranspiration rates and shoot dry weights at weekly intervals. Pansy, Viola tricola ‘Universal plus yellow’ and petunia, Petunia hybrida ‘Multiflora light salmon vein’ were grown in four independent experiments with the expected optimum nutrient concentration and fractions of the optimum. Root and shoot weights were measured during growth. KEY RESULTS: For each level of nutrient supply Ws increased with time (t) in days, according to the equation {Delta}Ws/{Delta}t=K2Ws/(100+Ws) in which the growth rate coefficient (K2) remained approximately constant throughout growth. The value of K2 for the optimum treatment was defined by incoming radiation and temperature. The value of K2 for each sub-optimum treatment relative to that for the optimum treatment was logarithmically related to the sub-optimal nutrient supply. Provided the aerial environment was optimal, Rsb/Ro{approx}Wo/Wsb where R is the root : shoot ratio, W is the shoot dry weight, and sb and o indicate sub-optimum and optimum nutrient supplies, respectively. Sub-optimal nutrient concentrations also depressed shoot growth without appreciably affecting root growth when the aerial environment was non-limiting. CONCLUSION: The new procedure can predict the effects of nutrient supply, incoming radiation and temperature on the time course of shoot growth and the root : shoot ratio for a range of growing conditions

    The political economy of universal health coverage. Background paper for the global symposium on health systems research

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    This paper is one of several in a series commissioned by the World Health Organization for the First Global Symposium on Health Systems Research, held 16-19 November, 2010, in Montreux, Switzerland. The goal of these papers is to initiate a dialogue on the critical issues in health systems research. The opinions expressed in these papers are those of the authors and do not necessarily reflect those of the symposium organizers. This paper has financial support from the Rockefeller Foundation; the Alliance for Health Policy and Systems Research; and the German Federal Ministry for Economic Cooperation and Development (GTZ)

    Post-Foucauldian governmentality: what does it offer critical social policy analysis?

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    This article considers the theoretical perspective of post-Foucauldian governmentality, especially the insights and challenges it poses for applied researchers within the critical social policy tradition. The article firstly examines the analytical strengths of this approach to understanding power and rule in contemporary society, before moving on to consider its limitations for social policy. It concludes by arguing that these insights can be retained, and some of the weaknesses overcome, by adopting a ‘realist governmentality’ approach (Stenson 2005, 2008). This advocates combining traditional discursive analysis with more ethnographic methods in order to render visible the concrete activity of governing, and unravel the messiness, complexity and unintended consequences involved in the struggles around subjectivity

    ECLSS advanced automation preliminary requirements

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    A description of the total Environmental Control and Life Support System (ECLSS) is presented. The description of the hardware is given in a top down format, the lowest level of which is a functional description of each candidate implementation. For each candidate implementation, both its advantages and disadvantages are presented. From this knowledge, it was suggested where expert systems could be used in the diagnosis and control of specific portions of the ECLSS. A process to determine if expert systems are applicable and how to select the expert system is also presented. The consideration of possible problems or inconsistencies in the knowledge or workings in the subsystems is described
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