603 research outputs found

    (1,0) superconformal theories in six dimensions and Killing spinor equations

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    We solve the Killing spinor equations of 6-dimensional (1,0) superconformal theories in all cases. In particular, we derive the conditions on the fields imposed by the Killing spinor equations and demonstrate that these depend on the isotropy group of the Killing spinors. We focus on the models proposed by Samtleben et al in \cite{ssw} and find that there are solutions preserving 1,2, 4 and 8 supersymmetries. We also explore the solutions which preserve 4 supersymmetries and find that many models admit string and 3-brane solitons as expected from the M-brane intersection rules. The string solitons are smooth regulated by the moduli of instanton configurations.Comment: 26 page

    unreinforced masonry buildings

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    A recent earthquake of M=4.9 occurred on 29 October 2007 in C, ameli, Denizli, which is located in a seismically active region at southwest Anatolia, Turkey. It has caused extensive damages at unreinforced masonry buildings like many other cases observed in Turkey during other previous earthquakes. Most of the damaged structures were non-engineered, seismically deficient, unreinforced masonry buildings. This paper presents a site survey of these damaged buildings. In addition to typical masonry damages, some infrequent, event-specific damages were also observed. Reasons for the relatively wide spread damages considering the magnitude of the event are discussed in the paper

    Polarization-engineered GaN/InGaN/GaN tunnel diodes

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    We report on the design and demonstration of polarization-engineered GaN/InGaN/GaN tunnel junction diodes with high current density and low tunneling turn-on voltage. Wentzel-Kramers-Brillouin (WKB) calculations were used to model and design tunnel junctions with narrow bandgap InGaN-based barrier layers. N-polar p-GaN/In0.33Ga0.67N/n-GaN heterostructure tunnel diodes were grown using molecular beam epitaxy. Efficient zero bias tunneling turn-on with a high current density of 118 A/cm2 at a reverse bias of 1V, reaching a maximum current density up to 9.2 kA/cm2 were obtained. These results represent the highest current density reported in III-nitride tunnel junctions, and demonstrate the potential of III-nitride tunnel devices for a broad range of optoelectronic and electronic applications.Comment: 3 pages, 3 figure

    Overcoming cross-cultural group work tensions: mixed student perspectives on the role of social relationships

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    As universities worldwide rapidly internationalise, higher education classrooms have become unique spaces for collaboration between students from different countries. One common way to encourage collaboration between diverse peers is through group work. However, previous research has highlighted that cross-cultural group work can be challenging and has hinted at potential social tensions. To understand this notion better, we have used robust quantitative tools in this study to select 20 participants from a larger classroom of 860 students to take part in an in-depth qualitative interview about cross-cultural group work experiences. Participant views on social tensions in cross-cultural group work were elicited using a unique mediating artefact method to encourage reflection and in-depth discussion. In our analysis of emergent interview themes, we compared student perspectives on the role of social relationships in group work by their academic performance level. Our findings indicated that all students interviewed desired the opportunity to form social relationships with their group work members, but their motivations for doing so varied widely by academic performance level

    M-Horizons

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    We solve the Killing spinor equations and determine the near horizon geometries of M-theory that preserve at least one supersymmetry. The M-horizon spatial sections are 9-dimensional manifolds with a Spin(7) structure restricted by geometric constraints which we give explicitly. We also provide an alternative characterization of the solutions of the Killing spinor equation, utilizing the compactness of the horizon section and the field equations, by proving a Lichnerowicz type of theorem which implies that the zero modes of a Dirac operator coupled to 4-form fluxes are Killing spinors. We use this, and the maximum principle, to solve the field equations of the theory for some special cases and present some examples.Comment: 36 pages, latex. Reference added, minor typos correcte

    VOLTTRON Lite: Integration Platform for the Transactional Network

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    In FY13, Pacific Northwest National Laboratory (PNNL) with funding from the Department of Energy’s (DOE’s) Building Technologies Office (BTO) designed, prototyped and tested a transactional network platform. The platform is intended to support energy, operational and financial transactions between any networked entities (equipment, organizations, buildings, grid, etc.). Initially, in FY13, the concept demonstrated transactions between packaged rooftop units (RTUs) and the electric grid using applications or “agents” that reside on the platform, on the equipment, on local building controller or in the Cloud. This document describes the core of the transactional network platform, the Volttron Liteℱ software and associated services hosted on the platform. Future enhancements are also discussed. The appendix of the document provides examples of how to use the various services hosted on the platform
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