83 research outputs found

    Ricci-flat K\"ahler metrics on crepant resolutions of K\"ahler cones

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    We prove that a crepant resolution of a Ricci-flat K\"ahler cone X admits a complete Ricci-flat K\"ahler metric asymptotic to the cone metric in every K\"ahler class in H^2_c(Y,R). This result contains as a subcase the existence of ALE Ricci-flat K\"ahler metrics on crepant resolutions of X=C^n /G, where G is a finite subgroup of SL(n,C). We consider the case in which X is toric. A result of A. Futaki, H. Ono, and G. Wang guarantees the existence of a Ricci-flat K\"ahler cone metric if X is Gorenstein. We use toric geometry to construct crepant resolutions.Comment: 26 pages. Accepted for publication in Mathematische Annale

    Lev’s en mobiliteitstransitie.

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    Presentatie van resultaten enquete over lichte elektrische voertuigen

    Lev’s en mobiliteitstransitie.

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    Presentatie van resultaten enquete over lichte elektrische voertuigen

    Aviation as public transport: which regions are underserved?

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    The White Book on Transport of the European Union deals with Roads, Rail, Inland waterway, Seaways, Pipelines, Energy-networks but only briefly with airports. The emphasis in the White Book is on the modal shift from aviation to high speed rail transport. The Lisbon-strategy, however, advocates an optimal international connectivity for regions. A high speed rail connection is not a viable option for a lot of less densily populated area’s whereas an air connection is. For this reason the Committee of regions also pleads for aviation as an instrument for territorial cohesion. In several countries public transport (bus tram subway train) within regions is a political priority and is (heavily) subsidized. The regulations to connect regions to the international air-traffic network are very limited. For underdeveloped and underserved regions a Public Service Obligation for aviation is eligible. Some EU-countries (for instance Norway, Portugal, France and Ireland) make use of this instrument whereas other countries spend nothing. These differences in terms of the degree states have adopted the PSO mechanism in respect of air transport services poses an number of questions. What kind of regions are served by a Public Service Obligation ? Is it their geographic position (Islands), their demographic or socio-economic position which make them eligible? Which other (comparable) regions are underserved? What are the costs involved ? In order to answer these type of questions we have investigated the international connectivity by air of all regions within the EU for the period 1996-2005. We compare regions with a PSO with regions without PSO which are underserved by air transport. This paper answers some of the questions which are important for future policy initiatives designed to enhance accessibility and economic and social cohesion

    Geen autoparkeren zonder fietsparkeren.

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    Bijdrage SPHV congres over parkeren en verblijven

    Relative K-stability and extremal Sasaki metrics

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