1,502 research outputs found

    Managing urban socio-technical change? Comparing energy technology controversies in three European contexts

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    A {\em local graph partitioning algorithm} finds a set of vertices with small conductance (i.e. a sparse cut) by adaptively exploring part of a large graph GG, starting from a specified vertex. For the algorithm to be local, its complexity must be bounded in terms of the size of the set that it outputs, with at most a weak dependence on the number nn of vertices in GG. Previous local partitioning algorithms find sparse cuts using random walks and personalized PageRank. In this paper, we introduce a randomized local partitioning algorithm that finds a sparse cut by simulating the {\em volume-biased evolving set process}, which is a Markov chain on sets of vertices. We prove that for any set of vertices AA that has conductance at most ϕ\phi, for at least half of the starting vertices in AA our algorithm will output (with probability at least half), a set of conductance O(ϕ1/2log⁥1/2n)O(\phi^{1/2} \log^{1/2} n). We prove that for a given run of the algorithm, the expected ratio between its computational complexity and the volume of the set that it outputs is O(ϕ−1/2polylog(n))O(\phi^{-1/2} polylog(n)). In comparison, the best previous local partitioning algorithm, due to Andersen, Chung, and Lang, has the same approximation guarantee, but a larger ratio of O(ϕ−1polylog(n))O(\phi^{-1} polylog(n)) between the complexity and output volume. Using our local partitioning algorithm as a subroutine, we construct a fast algorithm for finding balanced cuts. Given a fixed value of ϕ\phi, the resulting algorithm has complexity O((m+nϕ−1/2)polylog(n))O((m+n\phi^{-1/2}) polylog(n)) and returns a cut with conductance O(ϕ1/2log⁥1/2n)O(\phi^{1/2} \log^{1/2} n) and volume at least vϕ/2v_{\phi}/2, where vϕv_{\phi} is the largest volume of any set with conductance at most ϕ\phi.Comment: 20 pages, no figure

    Popularizing Electoral Politics: Change in the 2016 U.S. Presidential Race

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    This special issue of the European Journal of American Studies examines the popularization of electoral politics during the 2016 U.S. Presidential Election. The popularization processes include the rise of populism penetrating the U.S. political landscape; a media focus on human interest, rather than policy substance questions; personality politics and celebrity culture at the center stage of the election; and the appropriation and dissemination of popular culture discourses by social media users. The articles draw from transdisciplinary American Studies approaches to tackle a range of issues which arose during the election, from contestations of “American-ness” and competing narratives of truth—or “post-truth”—to questions of campaign finance and displays of violence, verbal and physical. The issue also takes a closer look at specific expressions of popular culture as reflected in the media, specifically in relation to the rise of nativism and the alt-right movement, the political impact of comedy on the election, and the significance of memes in the battle over image and meaning-making. The processes of popularizing electoral politics of the 2016 race had distinct consequences, not only in shaping political culture as we know it, but also in destabilizing established rules of political conduct

    Contemporary (2001) and ‘Little Ice Age’ glacier extents in the Buordakh Massif, Cherskiy Range, north east Siberia

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    The Buordakh Massif of the Cherskiy Range of sub-arctic north east Siberia, Russia has a cold continental climate and supports over 80 glaciers. Despite previous research in the region, a georeferenced map of the glaciers has only recently been completed and an enhanced version of it is reproduced in colour here. The mountains of this region reach heights in excess of 3,000 m and the glaciers on their slopes range in size from 0.1 to 10.4 km2. The mapping has been compiled through the interpretation of Landsat 7 ETM+ satellite imagery from August 2001 which has been augmented by data from a field campaign undertaken at the same time. The glaciers of the region are of the cold, ‘firn-less’ continental type and their mass balance relies heavily on the formation of superimposed ice. Moraines which lie in front of the glaciers by up to a few kilometres are believed to date from the Little Ice Age (ca. 1550-1850 AD). Over half of the glaciers mapped have shown marked retreat from these moraines

    Electronic shell and supershell structure in graphene flakes

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    We use a simple tight-binding (TB) model to study electronic properties of free graphene flakes. Valence electrons of triangular graphene flakes show a shell and supershell structure which follows an analytical expression derived from the solution of the wave equation for triangular cavity. However, the solution has different selection rules for triangles with armchair and zigzag edges, and roughly 40000 atoms are needed to see clearly the first supershell oscillation. In the case of spherical flakes, the edge states of the zigzag regions dominate the shell structure which is thus sensitive to the flake diameter and center. A potential well that is made with external gates cannot have true bound states in graphene due to the zero energy band gap. However, it can cause strong resonances in the conduction band.Comment: Presented in the ISSPIC-14 conference, Valladolid, September 200

    Multigrid method for electronic structure calculations

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    A general real-space multigrid algorithm for the self-consistent solution of the Kohn-Sham equations appearing in the state-of-the-art electronic-structure calculations is described. The most important part of the method is the multigrid solver for the Schrödinger equation. Our choice is the Rayleigh quotient multigrid method (RQMG), which applies directly to the minimization of the Rayleigh quotient on the finest level. Very coarse correction grids can be used, because there is, in principle, no need to represent the states on the coarse levels. The RQMG method is generalized for the simultaneous solution of all the states of the system using a penalty functional to keep the states orthogonal. The performance of the scheme is demonstrated by applying it in a few molecular and solid-state systems described by nonlocal norm-conserving pseudopotentials.Peer reviewe

    Developing LCA-based benchmarks for sustainable consumption - for and with users

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    This article presents the development process of a consumer-oriented, illustrative benchmarking tool enabling consumers to use the results of environmental life cycle assessment (LCA) to make informed decisions. Active and environmentally conscious consumers and environmental communicators were identified as key target groups for this type of information. A brochure presenting the benchmarking tool was developed as an participatory, iterative process involving consumer focus groups, stakeholder workshops and questionnaire-based feedback. In addition to learning what works and what does not, detailed suggestions on improved wording and figures were obtained, as well as a wealth of ideas for future applications

    Participation, involvement and peer relationships in children with special educational needs in early childhood education

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    The aim of this study was to obtain new information about the diversity of everyday activities and social relations among children with special education needs (N = 145) in Finnish early childhood education and care (ECEC) units. In this research children ' s daily activities, involvement, target of attention and social relations during play and other social activities in different groups formed according to children's special educational needs are investigated. Results revealed that children with problems in self-regulation and children with major disabilities spent less time with peers and in various social activities than children with developmental language disorder and children without special education needs. The results suggest that inclusive practices are still only under development within the Finnish ECEC units. Practical implications of the results concerning ways to support children's equal participation in daily activities in early childhood education and in building peer relationships, regardless of the amount of needed support are discussed.Peer reviewe
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