2,267 research outputs found

    ESIM_DSN Web-Enabled Distributed Simulation Network

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    In this paper, the eSim(sup DSN) approach to achieve distributed simulation capability using the Internet is presented. With this approach a complete simulation can be assembled from component subsystems that run on different computers. The subsystems interact with each other via the Internet The distributed simulation uses a hub-and-spoke type network topology. It provides the ability to dynamically link simulation subsystem models to different computers as well as the ability to assign a particular model to each computer. A proof-of-concept demonstrator is also presented. The eSim(sup DSN) demonstrator can be accessed at http://www.jsc.draper.com/esim which hosts various examples of Web enabled simulations

    Schottky-based band lineups for refractory semiconductors

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    An overview is presented of band alignments for small-lattice parameter, refractory semiconductors. The band alignments are estimated empirically through the use of available Schottky barrier height data, and are compared to theoretically predicted values. Results for tetrahedrally bonded semiconductors with lattice constant values in the range from C through ZnSe are presented. Based on the estimated band alignments and the recently demonstrated p-type dopability of GaN, we propose three novel heterojunction schemes which seek to address inherent difficulties in doping or electrical contact to wide-gap semiconductors such as ZnO, ZnSe, and ZnS

    Macroscopic polarization and band offsets at nitride heterojunctions

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    Ab initio electronic structure studies of prototypical polar interfaces of wurtzite III-V nitrides show that large uniform electric fields exist in epitaxial nitride overlayers, due to the discontinuity across the interface of the macroscopic polarization of the constituent materials. Polarization fields forbid a standard evaluation of band offsets and formation energies: using new techniques, we find a large forward-backward asymmetry of the offset (0.2 eV for AlN/GaN (0001), 0.85 eV for GaN/AlN (0001)), and tiny interface formation energies.Comment: RevTeX 4 pages, 2 figure

    Wikipedia as an encyclopaedia of life

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    In his 2003 essay E O Wilson outlined his vision for an “encyclopaedia of life” comprising “an electronic page for each species of organism on Earth”, each page containing “the scientific name of the species, a pictorial or genomic presentation of the primary type specimen on which its name is based, and a summary of its diagnostic traits.” Although the “quiet revolution” in biodiversity informatics has generated numerous online resources, including some directly inspired by Wilson's essay (e.g., "http://ispecies.org":http://ispecies.org, "http://www.eol.org":http://www.eol.org), we are still some way from the goal of having available online all relevant information about a species, such as its taxonomy, evolutionary history, genomics, morphology, ecology, and behaviour. While the biodiversity community has been developing a plethora of databases, some with overlapping goals and duplicated content, Wikipedia has been slowly growing to the point where it now has over 100,000 pages on biological taxa. My goal in this essay is to explore the idea that, largely independent of the efforts of biodiversity informatics and well-funded international efforts, Wikipedia ("http://en.wikipedia.org/wiki/Main_Page":http://en.wikipedia.org/wiki/Main_Page) has emerged as potentially the best platform for fulfilling E O Wilson’s vision

    Tumor necrosis factor-alpha levels in HIV-1 seropositive injecting drug users.

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    TNF-alpha is a highly pleiotropic cytokine and plays an important role in regulating HIV-1 replication. It may compromise the integrity of the blood-brain-barrier and, thus, may contribute to the neurotoxicity of HIV-1-infection. Both intravenous drug abuse (IDU) and HIV infection can increase TNF-alpha activity, but little information is available on the effects of a combination of these factors on TNF-alpha. We investigated plasma TNF-alpha levels and mRNA in the peripheral monocytes of 166 men and women in three groups: HIV-1-positive IDUs, HIV-1-negative IDUs, and HIV-negative non-IDU control participants. HIV-1-positive IDUs had higher TNF-alpha levels than HIV-1-negative IDUs who, in turn, had higher levels than controls. TNF-alpha mRNA expression in peripheral monocytes was significantly increased in both HIV-1-positive and negative IDUs compared to controls. These findings show that the effects of HIV infection and intravenous drug use may be additive in increasing TNF-alpha levels. Given the multiple effects of TNF-alpha in HIV infection, additional investigation of its role is needed

    Tiburce\u27s kiss and other extraordinary happenings in Chaucer\u27s Second nun\u27s tale

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    The following is a close reading of Chaucer\u27s Second Nun’s Tale. The goal of this reading is to note the humor and sexuality that can be found in the Tale. As I surveyed the critical literature and studied the tradition of hagiography of which the Second Nun\u27s Tale is a part, I found an overwhelming tendency among critics to either dismiss the Tale as insignificant or to regard it with a stone-faced seriousness. I hope that I have established in the following pages that the Second Nun\u27s Tale is an integral part of the Canterbury Tales and has within it much of the same humor, sexuality and thematic complexity found in the tales told by the other pilgrims
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