30 research outputs found

    On the uniqueness and global dynamics of AdS spacetimes

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    We study global aspects of complete, non-singular asymptotically locally AdS spacetimes solving the vacuum Einstein equations whose conformal infinity is an arbitrary globally stationary spacetime. It is proved that any such solution which is asymptotically stationary to the past and future is itself globally stationary. This gives certain rigidity or uniqueness results for exact AdS and related spacetimes.Comment: 18pp, significant revision of v

    Non-conjugacy of a minimal distal diffeomorphism of the torus to aC 1 skew-product

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    Pricing Private Mortgage Insurance

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    Issues involved in an evaluation of the price of private mortgage insurance are discussed. Cost considerations are emphasized as long-run equilibrium competitive market prices equal long-run marginal and average cost. An empirical evaluation of current insurance premiums vis-a-vis competitive market norms requires more empirical information on the determinants of foreclosures, especially the links between micro and macro determinants. Option pricing models suggest other data comparisons that also may shed light on an evaluation of insurance premiums. Copyright American Real Estate and Urban Economics Association.

    Correlations between physical and chemical defences in plants: tradeoffs, syndromes, or just many different ways to skin a herbivorous cat?

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    � Most plant species have a range of traits that deter herbivores. However, understanding of how different defences are related to one another is surprisingly weak. Many authors argue that defence traits trade off against one another, while others argue that they form coordinated defence syndromes. � We collected a dataset of unprecedented taxonomic and geographic scope (261 species spanning 80 families, from 75 sites across the globe) to investigate relationships among four chemical and six physical defences. � Five of the 45 pairwise correlations between defence traits were significant and three of these were tradeoffs. The relationship between species’ overall chemical and physical defence levels was marginally nonsignificant (P = 0.08), and remained nonsignificant after accounting for phylogeny, growth form and abundance. Neither categorical principal component analysis (PCA) nor hierarchical cluster analysis supported the idea that species displayed defence syndromes. � Our results do not support arguments for tradeoffs or for coordinated defence syndromes. Rather, plants display a range of combinations of defence traits. We suggest this lack of consistent defence syndromes may be adaptive, resulting from selective pressure to deploy a different combination of defences to coexisting species
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