68,734 research outputs found

    Computer/PERT technique monitors actual versus allocated costs

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    A computer method measures the users performance in cost-type contracts utilizing the existing nasa program evaluation review technique without imposing any additional reporting requirements. progress is measured by comparing actual costs with a value of work performed in a specific period

    Economic evaluations of non-communicable disease interventions

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    Background Demographic projections suggest a major increase in non-communicable disease (NCD) mortality over the next two decades in developing countries. In a climate of scarce resources, policy-makers need to know which interventions represent value for money. The prohibitive cost of performing multiple economic evaluations has generated interest in transferring the results of studies from one setting to another. This paper aims to bridge the gap in the current literature by critically evaluating the available published data on economic evaluations of NCD interventions in developing countries. Methods We identified and reviewed the methodological quality of 32 economic evaluations of NCD interventions in developing countries. Developing countries were defined according to the World Bank classification for low- and lower middle-income countries. We defined NCDs as the 12 categories listed in the 1993 World Bank report Investing in Health. English language literature was searched for the period January 1984 and January 2003 inclusive in Medline, Science Citation Index, HealthStar, NHS Economic Evaluation Database and Embase using medical subheading terms and free text searches. We then assessed the quality of studies according to a set of pre-defined technical criteria. Results We found that the quality of studies was poor and resource allocation decisions made by local and global policy-makers on the basis of this evidence could be misleading. Furthermore we have identified some clear gaps in the literature, particularly around injuries and strategies for tackling the consequences of the emerging tobacco epidemic. Conclusion In the face of poor evidence the role of so-called generalised cost-effectiveness analyses has an important role to play in aiding public health decision-making at the global level. Further research is needed to investigates the causes of variation among cost, effects and cost-effectiveness data within and between settings. Such analyses still need to take a broad view, present data in a transparent manner and take account of local constraints

    Embedded function methods for compressible high speed turbulent flow

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    Fundamental issues relating to compressible turbulent flow are addressed. The focus has been on developing methods and testing concepts for attached flows rather than trying to force a conventional law of the wall into a zone of backflow. Although the dynamics of the near-wall flow in an attached turbulent boundary layer are relatively well documented, the dynamical features of a zone of reversed turbulent flow are not, nor are they well understood. Incompressibility introduces effects and issues that have been dealt with only marginally in the literature, therefore, the present work has been focussed on attached high-speed flows. The wall function method has been extended up through the supersonic to hypersonic speeds. Algorithms have been successfully introduced into the code that calculates the flow all the way to the wall, and testing is being carried out for progressively more complex flow situations

    Wall-layer eruptions in turbulent flows

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    The near-wall region of a turbulent flow is investigated in the limit of large Reynolds numbers. When low-speed streaks are present, the governing equations are shown to be of the boundary-layer type. Physical processes leading to local breakdown and a strong interaction with the outer region are considered. It is argued that convected vortices, predominantly of the hairpin type, will provoke eruptions and regenerative interactions with the outer region

    Lunar igneous rocks and the nature of the lunar interior

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    Lunar igneous rocks are interpreted, which can give useful information about mineral assemblages and mineral chemistry as a function of depth in the lunar interior. Terra rocks, though intensely brecciated, reveal, in their chemistry, evidence for a magmatic history. Partial melting of feldspathic lunar crustal material occurred in the interval 4.6 to 3.9 gy. Melting of ilmenite-bearing cumulates at depths near 100 km produced parent magmas for Apollo 11 and 17 titaniferous mare basalts in the interval 3.8 to 3.6 gy. Melting of ilmenite-free olivine pyroxenites at depths greater than 200 km produced low-titanium mare basalts in the interval 3.4 to 3.1 gy. No younger igneous rocks have yet been recognized among the lunar samples and present-day melting seems to be limited to depths greater than 1000 km

    Experimental petrology and origin of Fra Mauro rocks and soil

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    Melting experiments over the pressure range 0 to 20 kilobars were conducted on Apollo 14 igneous rocks 14310 and 14072 and on comprehensive fines 14259. The mineralogy and textures of rocks 14310 and 14072 are presumed to be the result of near-surface crystallization. The chemical compositions of the samples show special relationships to multiply-saturated liquids in the system: anorthite-forsterite-fayalite-silica at low pressure. Partial melting of a lunar crust consisting largely of plagioclase, low calcium pyroxene, and olivine, followed by crystal fractionation at the lunar surface is proposed as a mechanism for the production of the igneous rocks and soil glasses sampled by Apollo 14

    Behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming

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    The behavior of the sodium and hydroxyl nighttime emissions during a stratospheric warming has been studied principally by use of data from the airglow photometers on the OGO-4 satellite. It was found that during the late stages of a major warming, both emissions increase appreciably, with the sodium emission returning to normal levels prior to the decrease in hydroxyl emission. The emission behaviors are attributed to temperature and density variations from 70 to 94 km, and a one-dimensional hydrostatic model for that altitude range is used to calculate the effects on the emissions and on the mesospheric ozone densities

    Use of Skylab EREP data in a sea-surface temperature experiment

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    The author has identified the following significant results. A sea surface temperature experiment was studied, demonstrating the feasibility of a procedure for the remote measurement of sea surface temperature which inherently corrects for the effect of the intervening atmosphere without recourse to climatological data. The procedure was applied to Skylab EREP S191 spectrometer data, and it is demonstrated that atmospheric effects on the observed brightness temperature can be reduced to less than 1.0 K

    Ground effects on Loran-C signals

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    In conjunction with the test and evaluation of the position fixing capabilities of the Army Manpack Loran Receiver AN/PSN-6, an extensive series of time difference and signal amplitude measurements were made within a 100 km map grid square encompassing Fort Monmouth, New Jersey. The test location is within the coverage area of the East Coast Loran-C Chain. The data were used to develop a simple smooth-earth model for the test area as well as to estimate the magnitude and distributions of deviations from this model. Local propagation processes associated with topographic features and the grid of overhead wires in the test area are shown to contribute to the deviations from the model
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