388,672 research outputs found

    Characterizations of Ordered Self-adjoint Operator Spaces

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    In this paper, we generalize the work of Werner and others to develop two abstract characterizations for self-adjoint operator spaces. The corresponding abstract objects can be represented as self-adjoint subspaces of B(H)B(H) in such a way that both a metric structure and an order structure are preserved at each matrix level. We demonstrate a generalization of the Arveson Extension Theorem in this context. We also show that quotients of self-adjoint operator spaces can be endowed with a compatible operator space structure and characterize the kernels of completely positive completely bounded maps on self-adjoint operator spaces.Comment: 20 pages. Updated references and corrected typos. The statement of Corollary 3.17 has been strengthene

    The importance of being alkaline

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    The earliest forms of "protolife" on Earth must have been able to reproduce and replicate; it is likely that they were also cellular. How might such systems have formed? In his Perspective, Russell highlights the report by Hanczyc et al., who show that clay particles can catalyze the formation of lipid vesicles. These particles also adsorb RNA. If the vesicles are forced to divide, RNA is distributed among the daughter vesicles. Similar conditions to those used in the experiments may have existed at mounds created by alkaline, hydrothermal seepages on the ancient ocean floor. However, instead of lipids, polypeptides formed from amino acids may have formed the first organic membranes

    Review of The Price of Alliance: The Politics and Procurement of Leopard Tanks for Canada’s NATO Brigade by Frank Maas

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    Review of The Price of Alliance: The Politics and Procurement of Leopard Tanks for Canada’s NATO Brigade by Frank Maas

    Review of Always at War: Organizational Culture in Strategic Air Command, 1946-62 by Melvin G. Deaile

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    Review of Always at War: Organizational Culture in Strategic Air Command, 1946-62 by Melvin G. Deaile

    The Dear Son

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    1999 Professorial Address: Nau te rourou, naku te rourou… Māori education: setting an agenda.

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    Current educational policies and practices in Aotearoa/New Zealand were developed and continue to be developed within a framework of power imbalances, which effects Maori the greatest. An alternative model that seeks to address indigenous Māori aspirations and Treaty of Waitangi guarantees for self determination is presented here. This model suggests how a tertiary teacher education institution might create learning contexts wherein power-sharing images, principles and practices will facilitate successful participation by Māori students in mainstream classrooms. This model constitutes the classroom as a place where young people's sense-making processes (cultures) are incorporated and enhanced, where the existing knowledges of young people are seen as "acceptable" and "official" and where the teacher interacts with students in such a way that new knowledge is co-created. Such a classroom will generate totally different interaction and participation patterns and educational outcomes from a classroom where knowledge is seen as something that the teacher makes sense of and then passes on to students

    Dispersal costs set the scene for helping in an atypical avian cooperative breeder

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    The ecological constraints hypothesis is suggested to explain the evolution of cooperative breeding in birds. This hypothesis predicts that the scene for cooperative breeding is set when ecological factors constrain offspring from dispersal. This prediction was tested in the atypical cooperative breeding system of the long-tailed tit, Aegithalos caudatus, by comparing the degree of philopatry and cooperation in an isolated and a contiguous site whilst experimentally controlling for confounding aspects of reproduction. No difference was found between the two sites in the survival of offspring but a greater proportion were found to remain philopatric in the isolated site. This difference was caused by greater philopatry of normally dispersive females suggesting, as predicted, that dispersal costs were greater from this site. Furthermore, a greater proportion of males and females cooperated following breeding failure in the isolated site than in the contiguous site. Thus, as has been suggested for typical avian cooperative breeders, dispersal costs, relative to philopatric benefits, appear to set the scene for cooperative breeding in long-tailed tits
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