92 research outputs found

    Orbital motions of a solar sail around the L2 Earth-Moon libration point

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    Multi-Body Orbit Architectures for Lunar South Pole Coverage

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    A potential ground station at the lunar south pole has prompted studies of orbit architectures that ensure adequate coverage. Constant communications can be achieved with two spacecraft in different combinations of Earth-Moon libration point orbits. Halo and vertical families, as well as other orbits near L1 and L2 are considered. The investigation includes detailed results using nine different orbits with periods ranging from 7 to 16 days. Natural solutions are generated in a full ephemeris model, including solar perturbations. A preliminary station-keeping analysis is also completed

    A Class of Selenocentric Retrograde Orbits With Innovative Applications to Human Lunar Operations

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    Selenocentric distant retrograde orbits with radii from approx. 12,500 km to approx. 25,000 km are assessed for stability and for suitability as crewed command and control infrastructure locations in support of telerobotic lunar surface operations and interplanetary human transport. Such orbits enable consistent transits to and from Earth at virtually any time if they are coplanar with the Moon's geocentric orbit. They possess multiple attributes and applications distinct from NASA's proposed destination orbit for a redirected asteroid about 70,000 km from the Moon

    Alternative sources of n-3 long-chain polyunsaturated fatty acids in marine microalgae

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    The main source of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) in human nutrition is currently seafood, especially oily fish. Nonetheless, due to cultural or individual preferences, convenience, geographic location, or awareness of risks associated to fatty fish consumption, the intake of fatty fish is far from supplying the recommended dietary levels. The end result observed in most western countries is not only a low supply of n-3 LC-PUFA, but also an unbalance towards the intake of n-6 fatty acids, resulting mostly from the consumption of vegetable oils. Awareness of the benefits of LC-PUFA in human health has led to the use of fish oils as food supplements. However, there is a need to explore alternatives sources of LC-PUFA, especially those of microbial origin. Microalgae species with potential to accumulate lipids in high amounts and to present elevated levels of n-3 LC-PUFA are known in marine phytoplankton. This review focuses on sources of n-3 LC-PUFA, namely eicosapentaenoic and docosahexaenoic acids, in marine microalgae, as alternatives to fish oils. Based on current literature, examples of marketed products and potentially new species for commercial exploitation are presented.NPST Program of King Saud University [11-ENE1719-02]; SEABIOMED [PTDC/MAR/103957/2008]; Foundation for Science and Technology (FCT); Portuguese National Budgetinfo:eu-repo/semantics/publishedVersio

    Minds at Work: Managing for Success in the Knowledge Economy

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    The Relationship of Some Parental Variables to Achievement and Values in College Women

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    The Disposition of 14

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    Looking back on technology to look forward on collaboration and learning

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    Seeing With Our Senses: An Exploration of the Origins of Analytic Knowing

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    Hallah tray with dish

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