10,624 research outputs found

    Driven From Home

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    https://digitalcommons.library.umaine.edu/mmb-ps/1981/thumbnail.jp

    Integrated technology wing design study

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    The technology development costs and associated benefits in applying advanced technology associated with the design of a new wing for a new or derivative trijet with a capacity for 350 passengers and maximum range of 8519 km, entering service in 1990 were studied. The areas of technology are: (1) airfoil technology; (2) planform parameters; (3) high lift; (4) pitch active control system; (5) all electric systems; (6) E to 3rd power propulsion; (7) airframe/propulsion integration; (8) graphite/epoxy composites; (9) advanced aluminum alloys; (10) titanium alloys; and (11) silicon carbide/aluminum composites. These technologies were applied to the reference aircraft configuration. Payoffs were determined for block fuel reductions and net value of technology. These technologies are ranked for the ratio of net value of technology (NVT) to technology development costs

    Evidence for cooperative interactions between the two motor domains of cytoplasmic dynein

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    AbstractCytoplasmic dynein is a force-transducing ATPase that powers the movement of cellular cargoes along microtubules. Two identical heavy chain polypeptides (> 500 kDa) of the cytoplasmic dynein complex contain motor domains that possess the ATPase and microtubule-binding activities required for force production [1]. It is of great interest to determine whether both heavy chains (DHCs) in the dynein complex are required for progression of the mechanochemical cycle and motility, as observed for other dimeric motors. We have used transgenic constructs to investigate cooperative interactions between the two motor domains of the Drosophila cytoplasmic dynein complex. We show that 138 kDa and 180 kDa amino-terminal fragments of DHC can assemble with full-length DHC to form heterodimeric complexes containing only a single motor domain. The single-headed dynein complexes can bind and hydrolyze ATP, yet do not show the ATP-induced detachment from microtubules that is characteristic of wild-type homodimeric dynein. These results suggest that cooperative interactions between the monomeric units of the dimer are required for efficient ATP-induced detachment of dynein and unidirectional movement along the microtubule

    The common case study: Lockheed design of a supersonic cruise vehicle

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    The objective was to compare the characteristics of SSTs designed for the same mission by Lockheed, McDonnell Douglas, British Aerospace (U.K.), Aerospatiale (France), and the USSR. This comparison was to be used to calibrate parametric design studies of the tradeoff between SST direct operating cost (DOC) and noise levels at the FAR 36 certification points. The guidelines for this common case study were to design an aircraft with the following mission: payload 23 247 kg (51 250 lbm), range - 7000 km (3780 n. mi.), and cruise Mach number - 2.2. Field length was constrained to 3505 m (11 500 ft). Other airfield constraints and fuel reserves were also specified, but no noise constraints were applied

    Oceanic long-distance navigation : do experienced migrants use the earth\u27s magnetic field?

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    Albatrosses and sea turtles are known to perform extremely long-distance journeys between disparate feeding areas and breeding sites located on small, isolated, oceanic islands or at specific coastal sites. These oceanic journeys, performed mainly over or through apparently featureless mediums, indicate impressive navigational abilities, and the sensory mechanisms used are still largely unknown. This research used three different approaches to investigate whether bi-coordinate navigation based on magnetic field gradients is likely to explain the navigational performance of wandering albatrosses in the South Atlantic and Indian Oceans and of green turtles breeding on Ascension Island in the South Atlantic Ocean. The possibility that magnetic field parameters can potentially be used in a bi-coordinate magnetic map by wandering albatrosses in their foraging area was investigated by analysing satellite telemetry data published in the literature. The possibilities for using bi-coordinate magnetic navigation varied widely between different areas of the Southern Oceans, indicating that a common mechanism, based on a bi-coordinate geomagnetic map alone, was unlikely for navigation in these areas. In the second approach, satellite telemetry was used to investigate whether Ascension Island green turtles use magnetic information for navigation during migration from their breeding island to foraging areas in Brazilian coastal waters. Disturbing magnets were applied to the heads and carapaces of the turtles, but these appeared to have little effect on their ability to navigate. The only possible effect observed was that some of the turtles with magnets attached were heading for foraging areas slightly south of the control turtles along the Brazilian coast. In the third approach, breeding female green turtles were deliberately displaced in the waters around Ascension Island to investigate which cues these turtles might use to locate and return to the island; the results suggested that cues transported by wind might be involved in the final stages of navigation

    Childcare, choice and social class: Caring for young children in the UK

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    This paper draws on the results of two qualitative research projects examining parental engagements with the childcare market in the UK. Both projects are located in the same two London localities. One project focuses on professional middle class parents, and the other on working class families, and we discuss the key importance of social class in shaping parents' differential engagement with the childcare market, and their understandings of the role childcare plays in their children's lives. We identify and discuss the different "circuits" of care (Ball et al 1995) available to and used by families living physically close to each other, but in social class terms living in different worlds. We also consider parents' relationships with carers, and their social networks. We conclude that in order to fully understand childcare policies and practices and families' experiences of care, an analysis which encompasses social class and the workings of the childcare market is needed

    Program on Earth Observation Data Management Systems (EODMS), appendixes

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    The needs of state, regional, and local agencies involved in natural resources management in Illinois, Iowa, Minnesota, Missouri, and Wisconsin are investigated to determine the design of satellite remotely sensed derivable information products. It is concluded that an operational Earth Observation Data Management System (EODMS) will be most beneficial if it provides a full range of services - from raw data acquisition to interpretation and dissemination of final information products. Included is a cost and performance analysis of alternative processing centers, and an assessment of the impacts of policy, regulation, and government structure on implementing large scale use of remote sensing technology in this community of users
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