53 research outputs found

    Origins of the Ambient Solar Wind: Implications for Space Weather

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    The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind. We also discuss where the community stands in its ability to forecast how variations in the solar wind (i.e., fast and slow wind streams) impact the Earth. Although the last few decades have seen significant progress in observations and modeling, we still do not have a complete understanding of the relevant physical processes, nor do we have a quantitatively precise census of which coronal structures contribute to specific types of solar wind. Fast streams are known to be connected to the central regions of large coronal holes. Slow streams, however, appear to come from a wide range of sources, including streamers, pseudostreamers, coronal loops, active regions, and coronal hole boundaries. Complicating our understanding even more is the fact that processes such as turbulence, stream-stream interactions, and Coulomb collisions can make it difficult to unambiguously map a parcel measured at 1 AU back down to its coronal source. We also review recent progress -- in theoretical modeling, observational data analysis, and forecasting techniques that sit at the interface between data and theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue connected with a 2016 ISSI workshop on "The Scientific Foundations of Space Weather." 44 pages, 9 figure

    Charge Transfer Reactions

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    Sterilisation of incompetent mentally handicapped persons: a model for decision making.

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    Doctors are regularly confronted with requests for sterilisation of mentally handicapped people who cannot give consent for themselves. They ought to act in a medical vacuum because there doesn't exist a consensus about a model for decision making on this matter. In this article a model for decision making is proposed, based on a review of the literature and our own research data. We have attempted to select and classify certain factors which could enable us to arrive at an ethically justifiable method of making a medical decision. In doing so we distinguish two major criteria: heredity and parenting competence, and six minor criteria: conception risk, IQ, age, personality, medical aspects and prognosis and finally support and guidance for the mentally handicapped person. The major criteria give rise to a "situation of necessity". In this situation the physician is confronted with a conflict of values and interests. The minor criteria are of an entirely different ethical order. They can only be considered once the major criteria have created a "situation of necessity". Ultimately it comes down to deciding whether the benefits of sterilisation outweigh the drawbacks and whether the means are appropriate to the end, where efficient contraception is the end and irreversible sterilisation is the means
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