462 research outputs found

    Exceptional geometry and tensor fields

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    We present a tensor calculus for exceptional generalised geometry. Expressions for connections, torsion and curvature are given a unified formulation for different exceptional groups E_n(n). We then consider "tensor gauge fields" coupled to the exceptional generalised gravity. Many of the properties of forms on manifolds are carried over to these fields.Comment: 22 pp., plain tex. v3: improved reference

    Spatial analysis of urban material stock with clustering algorithms: A Northern European case study

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    A large share of construction material stock (MS) accumulates in urban built environments. To attain a more sustainable use of resources, knowledge about the spatial distribution of urban MS is needed. In this article, an innovative spatial analysis approach to urbanMS is proposed. Within this scope, MSindicators are defined at neighborhood level and clusteredwith k-mean algorithms. The MS is estimated bottom-up with (a) material-intensity coefficients and (b) spatial data for three built environment components: buildings, road transportation, and pipes, using sevenmaterial categories. The city of Gothenburg, Sweden is used as a case study. Moreover, being the first case study in Northern Europe, the results are explored through various aspects (material composition, age distribution, material density), and, finally, contrasted on a per capita basis with other studies worldwide. The stock is estimated at circa 84 million metric tons. Buildings account for 73% of the stock, road transport 26%, and pipes 1%. Mineral-binding materials take the largest share of the stock, followed by aggregates, brick, asphalt, steel, and wood. Per capita, the MS is estimated at 153 metric tons; 62 metric tons are residential, which, in an international context, is a medium estimate. Denser neighborhoodswith a mix of nonresidential and residential buildings have a lower proportion of MS in roads and pipes than low-density single-family residential neighborhoods. Furthermore, single-family residential neighborhoods cluster in mixed-age classes and show the largest content of wood. Multifamily buildings cluster in three distinct age classes, and each represent a specific material composition of brick, mineral binding, and steel. Future work should focus on megacities and contrasting multiple urban areas and, methodologically, should concentrate on algorithms,MS indicators, and spatial divisions of urban stock

    The Need for Systems Development Capability in Design Science Research – Investigating the Role of An Innovation Lab as Part of The Academy

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    Information systems as an artefact-oriented discipline require a strong interaction between researches, developers and users regarding, design of, development of, and the study of the use of digital artefacts in social settings. During latter years performing research in a design science research spirit has gained increasing interest. In larger scale design research endeavours access to systems development capabilities becomes necessary. Such a unit, an InnovationLab, was established in 2006 in a university setting in Sweden. In this paper we are investigating the five years of experience from running this InnovationLab. Our findings point to an innovation lab being valuable for research in general and especially for design science research. However, in order to balance the business of an innovation lab it will be necessary to provide services for other stakeholders (such as administrative units, teachers, and students) as means for developing systems development capability aimed for supporting researchers

    Competition vs. Regulation in Mobile Telecommunications

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    This paper questions whether competition can replace sector-specific regulation of mobile telecommunications. We show that the monopolistic outcome may prevail independently of market concentration when access prices are determined in bilateral negotiations. A light-handed regulatory policy can induce effective competition. Call prices are close to the marginal cost if the networks are sufficiently close substitutes. Neither demand nor cost information is required. A unique and symmetric call price equilibrium exists under symmetric access prices, provided that call demand is sufficiently inelastic. Existence encompasses the case of many networks and high network substitutability

    Bubble dynamics inside a compliant blood vessel Strongly coupled FSI on a dynamic wedge mesh

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    Abstract In medical applications, ultrasound is no longer used exclusively for diagnostical purposes but also in a more intense and highly focused modification (HIFU) for interventional applications such as tumor treatment The goal of our present work is to develop a microscale model of the interaction between gas-filled microbubbles, blood and the respective blood vessel walls. A partitioned multi region black box interaction system that can accommodate the respective physical models for each region is envisaged (see The solver used for modeling the blood-wall interaction is based on icoFsiFoam (available in OF-1.5-dev) which provides interface coupling and dynamic mesh motion. Because the density ratio of blood and vessel wall is very close to unity, the components of the system show strong mutual influence and a strong coupling scheme has to be employed The bubble is represented in our model by the respective boundary of the fluid region (see Currently, we are running our calculations on a wedge mesh (see We kindly acknowledge the financial support of the Swiss National Science Foundation through NCCR Co-Me

    Intense Network Competition

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    First, we demonstrate how unregulated price setting in mobile telecommunications may lead to monopolization, even when networks are highly substitutable. Second, we demonstrate that a menu of structural rules, including (i) mandatory interconnection, (ii) reciprocal access prices and (iii) a ban on price discrimination of calls to other networks may restore competition. This regulation requires neither demand data nor information about call costs

    Which Tail Matters? Inequality and Growth in Brazil

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    We estimate the effect of initial income inequality on subsequent income per capita growth using sub-national data from Brazil over the period 1970-2000. Holding initial income per capita and standard confounders constant, we find that places with higher initial inequality exhibit higher subsequent growth. This effect is entirely driven by the lower tail of the initial income distribution: compared to more equal places, sub-national units with a higher share of income going to the middle quintile at the expense of the bottom quintile grow more rapidly, while places with a higher share of income going to the top quintile at the expense of the middle quintile get no growth boost at all. We document that both physical and human capital accumulation in places with higher inequality in the lower tail of the initial income distribution outpace capital accumulation in more equal places, while inequality in the upper tail of the distribution is uncorrelated with subsequent physical or human capital growth. These results are consistent with theories on credit constraints and setup costs for human and physical capital investments.JEL Classification Codes: D3, O1, O4http://www.grips.ac.jp/list/jp/facultyinfo/litschig-stephan/http://doi.org/10.24545/0000166
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