منابع مشابه
Virtually impossible: limiting Australian children and adolescents daily screen based media use
BACKGROUND Paediatric recommendations to limit children's and adolescents' screen based media use (SBMU) to less than two hours per day appear to have gone unheeded. Given the associated adverse physical and mental health outcomes of SBMU it is understandable that concern is growing worldwide. However, because the majority of studies measuring SBMU have focused on TV viewing, computer use, vide...
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A key result of the Capital Asset Pricing Model (CAPM) is that the market portfolio— the portfolio of all assets in which each asset’s weight is proportional to its total market capitalization—lies on the mean-variance-efficient frontier, the set of portfolios having mean-variance characteristics that cannot be improved upon. Therefore, the CAPM cannot be consistent with efficient frontiers for...
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The idea that quotidian, middle-level concepts typically have internal structure-definitional, statistical, or whatever—plays a central role in practically every current approach to cognition. Correspondingly, the idea that words that express quotidian, middle-level concepts have complex representations "at the semantic level" is recurrent in linguistics; it is the defining thesis of what is of...
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Impossible objects are a type of optical illusion involving ambiguous visual descriptions of figures that cannot physically exist. It is shown by way of example that such objects can be further developed using standard fractal techniques to create new, more complex designs that retain the perceptual illusion, sometimes allowing additional illusions to emerge from the process. The balanced Pytha...
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William Thurston conjectured over twenty years ago that every compact hyperbolic 3manifold whose boundary is a possibly empty union of tori is finitely covered by a manifold which fibres over the circle. If true, it provides a significant amount of global information about the topology of such manifolds. The first non-trivial examples supporting the conjecture were obtained by Gabai [Ga1] (1986...
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ژورنال
عنوان ژورنال: British Dental Journal
سال: 2007
ISSN: 0007-0610,1476-5373
DOI: 10.1038/bdj.2007.747