15,585 research outputs found

    Integrated fluxes for emission lines in the ultraviolet spectra of several planetaries

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    The IUE satellite observatory was used to obtain absolutely-calibrated emission line fluxes for diagnostic lines of multiply-ionized C, N, O, Si, Ne, and Ar which occur in the ultraviolet spectral region of planetary nebulae. These data, when combined with data from the blue, visual, and near infrared, provide improved estimates of ionic concentrations, plasma temperatures and densities, and elemental abundances

    Injection of clarity needed?

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    The legal status of children who stay in hospital for three months or longer gives rise to considerable confusion among managers in social services and social work departments. And the number of young people affected is significant. NHS statistics for the year ending 31 March 2000 suggest that in England around 2,800 children aged 0-19 on admission were discharged after spending more than two months in hospital, as were more than 500 children in Scotland. (A small number of these would have been discharged as adults.) A two-year study, commissioned by the Joseph Rowntree Foundation1 and carried out by the universities of Stirling, Durham, Newcastle and York, investigated the numbers, characteristics and circumstances of children and young people with complex needs who spend long periods in health care settings. Interviews were conducted in England and Scotland with 11 social services or health managers responsible for these children. The findings show a worrying degree of uncertainty about the position of young people who find themselves in a hospital or other health care setting for at least three months. One social services manager believed such children become looked after under the terms of the Children Act 1989. Another said children are not formally looked after but nevertheless receive the same services and safeguards as those who are. One Scottish social work manager did not know whether children going into health care settings for short-term (respite) care are looked after or not. And discussion with the research team's advisory group indicated that the confusion is not confined to our fieldwork areas

    Recognition of 3-D Objects from Multiple 2-D Views by a Self-Organizing Neural Architecture

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    The recognition of 3-D objects from sequences of their 2-D views is modeled by a neural architecture, called VIEWNET that uses View Information Encoded With NETworks. VIEWNET illustrates how several types of noise and varialbility in image data can be progressively removed while incornplcte image features are restored and invariant features are discovered using an appropriately designed cascade of processing stages. VIEWNET first processes 2-D views of 3-D objects using the CORT-X 2 filter, which discounts the illuminant, regularizes and completes figural boundaries, and removes noise from the images. Boundary regularization and cornpletion are achieved by the same mechanisms that suppress image noise. A log-polar transform is taken with respect to the centroid of the resulting figure and then re-centered to achieve 2-D scale and rotation invariance. The invariant images are coarse coded to further reduce noise, reduce foreshortening effects, and increase generalization. These compressed codes are input into a supervised learning system based on the fuzzy ARTMAP algorithm. Recognition categories of 2-D views are learned before evidence from sequences of 2-D view categories is accumulated to improve object recognition. Recognition is studied with noisy and clean images using slow and fast learning. VIEWNET is demonstrated on an MIT Lincoln Laboratory database of 2-D views of jet aircraft with and without additive noise. A recognition rate of 90% is achieved with one 2-D view category and of 98.5% correct with three 2-D view categories.National Science Foundation (IRI 90-24877); Office of Naval Research (N00014-91-J-1309, N00014-91-J-4100, N00014-92-J-0499); Air Force Office of Scientific Research (F9620-92-J-0499, 90-0083

    Children with complex support needs in healthcare settings for prolonged periods: their numbers, characteristics and experiences

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    This report details the findings of research conducted in England and Scotland to identify how many children with complex support needs are spending longer than one month in healthcare settings in Scotland and England, how and why they are in hospital, why they have not been discharged home or to appropriate alternative community-based facilities, and how well the hospital or healthcare setting is meeting their emotional, social and educational needs. It finds that many of these children could and should be discharged but are not, for a variety of reasons: primarily the lack of appropriate resources in the community and poor discharge planning processes, coupled with the inability of their families to manage their care and supervision without intensive support. Hospitals and healthcare settings in many cases are not meeting their needs and these children are being denied the protection offered by UK legislation governing children's rights and welfare

    Tungsten resonance integrals and Doppler coefficients First quarterly progress report, Jul. - Sep. 1965

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    Resonance integrals and Doppler coefficients of samples of natural tungsten, tungsten isotopes, and uranium oxide tungsten fue

    A Collision Avoidance Strategy for a Potential Natural Satellite around the Asteroid Bennu for the OSIRIS-REx Mission

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    The cadence of proximity operations for the OSIRIS-REx mission may have an extra induced challenge given the potential of the detection of a natural satellite orbiting the asteroid Bennu. Current ground radar observations for object detection orbiting Bennu show no found objects within bounds of specific size and rotation rates. If a natural satellite is detected during approach, a different proximity operation cadence will need to be implemented as well as a collision avoidance strategy for mission success. A collision avoidance strategy will be analyzed using the Wald Sequential Probability Ratio Test

    Representation of Probability Density Functions from Orbit Determination using the Particle Filter

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    Statistical orbit determination enables us to obtain estimates of the state and the statistical information of its region of uncertainty. In order to obtain an accurate representation of the probability density function (PDF) that incorporates higher order statistical information, we propose the use of nonlinear estimation methods such as the Particle Filter. The Particle Filter (PF) is capable of providing a PDF representation of the state estimates whose accuracy is dependent on the number of particles or samples used. For this method to be applicable to real case scenarios, we need a way of accurately representing the PDF in a compressed manner with little information loss. Hence we propose using the Independent Component Analysis (ICA) as a non-Gaussian dimensional reduction method that is capable of maintaining higher order statistical information obtained using the PF. Methods such as the Principal Component Analysis (PCA) are based on utilizing up to second order statistics, hence will not suffice in maintaining maximum information content. Both the PCA and the ICA are applied to two scenarios that involve a highly eccentric orbit with a lower apriori uncertainty covariance and a less eccentric orbit with a higher a priori uncertainty covariance, to illustrate the capability of the ICA in relation to the PCA
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