39,397 research outputs found

    What\u27s So Funny \u27Bout Peace, Love, and Understanding

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    Last Saturday I stood on Stine Lake with a group of friends to pray and spread a message of “Peace for Syria.” This event was sponsored by the Newman Association in response to Pope Francis’s request that “Christians, and our brothers and sisters of other religions and every man and woman of good will, cry out forcefully: Violence and war are never the way to peace!” Students of all religions and backgrounds came to support us, and it was a very rewarding day for me as a Catholic and as a human longing for world peace and understanding. [excerpt

    Leaf cuticular morphology links Platanaceae and Proteaceae

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    Int. J. Plant Sci. 166(5):843–855. © 2005 by The University of Chicago.The leaf cuticular morphology of extant species of Platanus was investigated using light and scanning electron microscopy. All species are shown to possess trichome bases of the same type as those commonly found in Proteaceae. Of particular significance are compound forms that consist of an annular surface scar associated with more than one underlying epidermal cell. These are found on the adaxial leaf surfaces of all species of Platanus and are also clearly evident on the abaxial surface of Platanus orientalis. This type of trichome base is therefore interpreted as the first detected nonreproductive morphological synapomorphy linking Proteaceae and Platanaceae. Also, the laterocytic, sometimes paracytic, or anomocytic arrangement of subsidiary cells in Platanus is distinct from the general state in Proteaceae, which is brachyparacytic and presumably derived. In Bellendena, possibly the most basal genus of extant Proteaceae, subsidiary cell arrangements resemble those of Platanus. These results are discussed with respect to leaf fossil records of Proteales, where it is concluded that the combination of brachyparacytic stomata and compound trichome bases is strong evidence for Proteaceae.Raymond J. Carpenter, Robert S. Hill, and Gregory J. Jorda

    A Gedanken spacecraft that operates using the quantum vacuum (Dynamic Casimir effect)

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    Conventional rockets are not a suitable technology for deep space missions. Chemical rockets require a very large weight of propellant, travel very slowly compared to light speed, and require significant energy to maintain operation over periods of years. For example, the 722 kg Voyager spacecraft required 13,600 kg of propellant to launch and would take about 80,000 years to reach the nearest star, Proxima Centauri, about 4.3 light years away. There have been various attempts at developing ideas on which one might base a spacecraft that would permit deep space travel, such as spacewarps. In this paper we consider another suggestion from science fiction and explore how the quantum vacuum might be utilized in the creation of a novel spacecraft. The spacecraft is based on the dynamic Casimir effect, in which electromagnetic radiation is emitted when an uncharged mirror is properly accelerated in the vacuum. The radiative reaction produces a dissipative force on the mirror that tends to resist the acceleration of the mirror. This force can be used to accelerate a spacecraft attached to the mirror. We also show that, in principal, one could obtain the power to operate the accelerated mirror in such a spacecraft using energy extracted from the quantum vacuum using the standard Casimir effect witha parallel plate geometry. Unfortunately the method as currently conceived generates a miniscule thrust, and is no more practical than a spacewarp, yet it does provide an interesting demonstration of our current understanding of the physics of the quantized electromagnetic field in vacuum.Comment: 18 pages, 3 figure

    Multiprocessor sparse L/U decomposition with controlled fill-in

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    Generation of the maximal compatibles of pivot elements for a class of small sparse matrices is studied. The algorithm involves a binary tree search and has a complexity exponential in the order of the matrix. Different strategies for selection of a set of compatible pivots based on the Markowitz criterion are investigated. The competing issues of parallelism and fill-in generation are studied and results are provided. A technque for obtaining an ordered compatible set directly from the ordered incompatible table is given. This technique generates a set of compatible pivots with the property of generating few fills. A new hueristic algorithm is then proposed that combines the idea of an ordered compatible set with a limited binary tree search to generate several sets of compatible pivots in linear time. Finally, an elimination set to reduce the matrix is selected. Parameters are suggested to obtain a balance between parallelism and fill-ins. Results of applying the proposed algorithms on several large application matrices are presented and analyzed

    The Role of Variations of Central Density Of White Dwarf Progenitors Upon Type Ia Supernovae

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    The discovery of the accelerated expansion of the universe using Type Ia supernovae (SNe Ia) has stimulated a tremendous amount of interest in the use of SNe Type Ia events as standard cosmological candles, and as a probe of the fundamental physics of dark energy. Recent observations of SNe Ia have indicated a significant population difference depending on the host galaxy. These observational findings are consistent with SNe Ia Ni-56 production in star-forming spiral galaxies some 0.1 solar masses higher - and therefore more luminous than in elliptical galaxies. We present recent full-star, 3D simulations of Type Ia supernovae which may help explain the nature of this systematic variation in SNe Ia luminosities, as well as the nature of the Ia explosion mechanism. These insights may in turn eventually shed light on the mystery of dark energy itself.Comment: 10 Pages, 3 Figures, Submitted to Proceedings of The Ninth Asia-Pacific International Conference on Gravitation and Astrophysics (ICGA9) held June 29 to July 3, 2009, at Huazhong University of Science & Technology in Wuhan, China

    Community development, higher education institutions and the Big Society: opportunities or opportunism?

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    In his Prison Notebooks, written between 1929-35, Gramsci claimed that 'all men are intellectuals: but not all men have in society the function of intellectuals.' He used this term 'organic intellectuals' to illustrate that those working at grassroots level who have significant knowledge(s) about the way communities of all types work, are as important to the development of society as academic intellectuals. This article explores the current idea of a 'Big Society' as a hegemonic idea. This exploration is undertaken in relation to the current economic, social and political situation and with reference to the practice of community development, lifelong learning and the role of the Higher Education Institutions (HEIs) in supporting this field of activity. In this article we use the term 'community development' as Tett defines in Morgan-Klein and Osborne (2007:104). She claims it means to 'increase the capacity of particular communities through targeted resources for particular areas'. We specifically explore the following areas: <p> • challenging the hegemonic ideas and policies • practising within the restrictions of cuts and limited resources • setting up supportive networks which will sustain workers • making meaningful international links abroad and using international examples of good practice • turning the ideology of the Big Society into an opportunity</p> We will pose the critical questions that we think need to be addressed and which we hope will help us to find direction and an understanding of the way forward at a deeper level. We hope to create both useful and innovative knowledge which will be a valid contribution to the field of community development
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