4,707 research outputs found

    PLU-E: a proposed framework for planning and conducting evaluation studies with children.

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    While many models exist to support the design process of a software development project, the evaluation process is far less well defined and this lack of definition often leads to poorly designed evaluations, or the use of the wrong evaluation method. Evaluations of products for children can be especially complex as they need to consider the different requirements and aims that such a product may have, and often use new or developing evaluation methods. This paper takes the view that evaluations should be planned from the start of a project in order to yield the best results, and proposes a framework to facilitate this. This framework is particularly intended to support the varied and often conflicting requirements of a product designed for children, as defined by the PLU model, but could be adapted for other user groups

    Molecular Model of the Microvillar Cytoskeleton and Organization of the Brush Border

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    BACKGROUND. Brush border microvilli are ~1-µm long finger-like projections emanating from the apical surfaces of certain, specialized absorptive epithelial cells. A highly symmetric hexagonal array of thousands of these uniformly sized structures form the brush border, which in addition to aiding in nutrient absorption also defends the large surface area against pathogens. Here, we present a molecular model of the protein cytoskeleton responsible for this dramatic cellular morphology. METHODOLOGY/PRINCIPAL FINDINGS. The model is constructed from published crystallographic and microscopic structures reported by several groups over the last 30+ years. Our efforts resulted in a single, unique, self-consistent arrangement of actin, fimbrin, villin, brush border myosin (Myo1A), calmodulin, and brush border spectrin. The central actin core bundle that supports the microvillus is nearly saturated with fimbrin and villin cross-linkers and has a density similar to that found in protein crystals. The proposed model accounts for all major proteinaceous components, reproduces the experimentally determined stoichiometry, and is consistent with the size and morphology of the biological brush border membrane. CONCLUSIONS/SIGNIFICANCE. The model presented here will serve as a structural framework to explain many of the dynamic cellular processes occurring over several time scales, such as protein diffusion, association, and turnover, lipid raft sorting, membrane deformation, cytoskeletal-membrane interactions, and even effacement of the brush border by invading pathogens. In addition, this model provides a structural basis for evaluating the equilibrium processes that result in the uniform size and structure of the highly dynamic microvilli.Boston University (Graduate Student Research Fellowship); National Institutes of Health (GM62886

    Nonlinear analysis of an axisymmetric structure subjected to non-axisymmetric loading

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    The development of the SHELPC finite element computer program is detailed. This program is specialized to simulate the nonlinear material behavior which results from combustor liner hot streaks. This problem produces a nonlinear Fourier Series type loading on an axisymmetric structure. Example cases are presented

    The 3D inelastic analysis methods for hot section components

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    Advanced 3-D inelastic structural/stress analysis methods and solution strategies for more accurate and yet more cost-effective analysis of combustors, turbine blades, and vanes are being developed. The approach is to develop four different theories, one linear and three higher order with increasing complexities including embedded singularities. Progress in each area is reported

    Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures

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    Accomplishments are described for the first year effort of a 5-year program to develop a methodology for coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures. These accomplishments include: (1) the results of the selective literature survey; (2) 8-, 16-, and 20-noded isoparametric plate and shell elements; (3) large deformation structural analysis; (4) eigenanalysis; (5) anisotropic heat transfer analysis; and (6) anisotropic electromagnetic analysis

    In-flight measurement of ice growth on an airfoil using an array of ultrasonic transducers

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    Results of preliminary tests to measure ice growth on an airfoil during flight icing conditions are presented. Ultrasonic pulse echo measurements of ice thickness are obtained from an array of eight ultrasonic transducers mounted flush with the leading edge of the airfoil. These thickness measurements are used to document the evolution of the ice shape during the encounter in the form of successive ice profiles. Results from 3 research flights are presented and discussed. The accuracy of the ultrasonic measurements is found to be within 0.5 mm of mechanical and stereo photograph measurements of the ice accretion

    Icing flight research: Aerodynamic effects of ice and ice shape documentation with stereo photography

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    Aircraft icing flight research was performed in natural icing conditions. A data base consisting of icing cloud measurements, ice shapes, and aerodynamic measurements is being developed. During research icing encounters the icing cloud was continuously measured. After the encounter, the ice accretion shapes on the wing were documented with a stereo camera system. The increase in wing section drag was measured with a wake survey probe. The overall aircraft performance loss in terms of lift and drag coefficient changes was obtained by steady level speed/power measurements. Selective deicing of the airframe components was performed to determine their contributions to the total drag increase. Engine out capability in terms of power available was analyzed for the iced aircraft. It was shown that the stereo photography system can be used to document ice shapes in flight and that the wake survey probe can measure increases in wing section drag caused by ice. On one flight, the wing section drag coefficient (c sub d) increased approximately 120 percent over the uniced baseline at an aircraft angle of attack of 6 deg. On another flight, the aircraft darg coefficient (c sub d) increased by 75 percent over the uniced baseline at an aircraft lift coefficient (C sub d) of 0.5

    The weird and the wonderful – The scientific study of a miniature mummy

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    A human-faced oddity purported to be a ‘human baby, animal mummy or fake’ constructed in an ancient Egyptian style, was analysed at the KNH Centre for Biomedical Egyptology, University of Manchester, UK. Radiographic analysis using conventional radiography (X-ray) and computed tomography (CT) highlighted the nature of the bundle contents and identified marked similarities to mummified animal remains from ancient Egypt. Small samples were analysed using microscopy, environmental scanning electron microscopy (ESEM) and energy dispersive spectroscopy (EDS). ESEM was used to assess the homogeneity of the sample and the materials used in its construction. EDS was conducted for analysis of the elemental composition.Comparatively few miniature mummies of this type are known and they represent an intriguing area of mummy studies. The results of this research have allowed comparisons with contemporary human and animal mummies to be made.Based on residues of tin plating found on the underside of the mask, it is possible that this feature is a recent addition. Further analysis of the materials used in the construction of the artefact is required to ascertain if the mask is a contemporary feature
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