923 research outputs found

    K3 surfaces with a symplectic automorphism of order 4

    Full text link
    Given XX a K3 surface admitting a symplectic automorphism τ\tau of order 4, we describe the isometry τ\tau^* on H2(X,Z)H^2(X,\mathbb Z). Having called Z~\tilde Z and Y~\tilde Y respectively the minimal resolutions of the quotient surfaces Z=X/τ2Z=X/\tau^2 and Y=X/τY=X/\tau, we also describe the maps induced in cohomology by the rational quotient maps XZ~, XY~X\rightarrow\tilde Z,\ X\rightarrow\tilde Y and Y~Z~\tilde Y\rightarrow\tilde Z: with this knowledge, we are able to give a lattice-theoretic characterization of Z~\tilde Z, and find the relation between the N\'eron-Severi lattices of X,Z~X,\tilde Z and Y~\tilde Y in the projective case. We also produce three different projective models for X,Z~X,\tilde Z and Y~\tilde Y, each associated to a different polarization of degree 4 on XX.Comment: 38 page

    An indicator framework for assessing ecosystem services in support of the EU Biodiversity Strategy to 2020

    Get PDF
    Maes, Joachim... et al.-- 10 pages, 2 figures, 3 tables, supplementary material https://doi.org/10.1016/j.ecoser.2015.10.023In the EU, the mapping and assessment of ecosystems and their services, abbreviated to MAES, is seen as a key action for the advancement of biodiversity objectives, and also to inform the development and implementation of related policies on water, climate, agriculture, forest, marine and regional planning. In this study, we present the development of an analytical framework which ensures that consistent approaches are used throughout the EU. It is framed by a broad set of key policy questions and structured around a conceptual framework that links human societies and their well-being with the environment. Next, this framework is tested through four thematic pilot studies, including stakeholders and experts working at different scales and governance levels, which contributed indicators to assess the state of ecosystem services. Indicators were scored according to different criteria and assorted per ecosystem type and ecosystem services using the common international classification of ecosystem services (CICES) as typology. We concluded that there is potential to develop a first EU wide ecosystem assessment on the basis of existing data if they are combined in a creative way. However, substantial data gaps remain to be filled before a fully integrated and complete ecosystem assessment can be carried outBalint Czúcz was supported by the Bolyai Grant of the Hungarian Academy of Sciences under grant number BO/00138/12/8Peer Reviewe

    Uses of Innovative Modeling Tools within the Implementation of the Marine Strategy Framework Directive

    Get PDF
    In Europe and around the world, the approach to management of the marine environment has developed from the management of single issues (e.g., species and/or pressures) toward holistic Ecosystem Based Management (EBM) that includes aims to maintain biological diversity and protect ecosystem functioning. Within the European Union, this approach is implemented through the Marine Strategy Framework Directive (MSFD, 2008/56/EC). Integrated Ecosystem Assessment is required by the Directive in order to assess Good Environmental Status (GES). Ecological modeling has a key role to play within the implementation of the MSFD, as demonstrated here by case studies covering a range of spatial scales and a selection of anthropogenic threats. Modeling studies have a strong role to play in embedding data collected at limited points within a larger spatial and temporal scale, thus enabling assessments of pelagic and seabed habitat. Furthermore, integrative studies using food web and ecosystem models are able to investigate changes in food web functioning and biological diversity in response to changes in the environment and human pressures. Modeling should be used to: support the development and selection of specific indicators; set reference points to assess state and the achievement of GES; inform adaptive monitoring programs and trial management scenarios. The modus operandi proposed shows how ecological modeling could support the decision making process leading to appropriate management measures and inform new policy.This manuscript is a result of DEVOTES (DEVelopment Of innovative Tools for understanding marine biological diversity and assessing good Environmental Status) project, funded by the European Union under the 7th Framework Programme, “The Ocean of Tomorrow” Theme (grant agreement no. 308392), www.devotes-project.eu.Peer reviewedPeer Reviewe

    A branch and bound approach for the design of decentralized supervisors in Petri net models

    Get PDF
    The paper addresses the design of compact and maximally permissive decentralized supervisors for Petri nets, based on generalized mutual exclusion constraints. Decentralization constraints are formulated with respect to the net transitions, instructing each local supervisor to detect and disable transitions of its own control site only. A solution is characterized in terms of the states it allows and its feasibility is assessed by means of two separate tests, one checking the required behavioral properties (e.g., liveness, reversibility and controllability) of the induced reachability subgraph and the other ensuring the existence of a decentralized supervisor enforcing exactly the considered set of allowed states. The second test employs an integer linear programming formulation. Maximal permissivity is ensured by efficiently exploring the solution space using a branch and bound method that operates on the reachable states. Particular emphasis is posed on the obtainment of the controllability property, both in the structural and the behavioral interpretation

    On the transcendental lattices of Hyperk\"ahler manifolds

    Full text link
    We introduce the notion of a Hyper-K\"{a}hler manifold XX induced by a Hodge structure of K3-type. We explore this notion for the known deformation types of hyper-K\"{a}hler manifolds studying those that are induced by a K3 or abelian surface, giving lattice-theoretic criteria to decide whether or not they are birational to a moduli space of sheaves over said surface. We highlight the different behaviors we find for the particular class of hyper-K\"{a}hler manifolds of O'Grady type.Comment: 24 page

    vitamin e as a functional and biocompatibility modifier of synthetic hemodialyzer membranes an overview of the literature on vitamin e modified hemodialyzer membranes

    Get PDF
    Along with one century of history, research has provided many solutions for hemodialysis (HD) biomaterials, encompassing several generations of copolymers that have found wide application in the deve

    Capabilities of Baltic Sea models to assess environmental status for marine biodiversity

    Get PDF
    Abstract To date there has been no evaluation of the capabilities of the Baltic Sea ecosystem models to provide information as outlined by the Marine Strategy Framework Directive. This work aims to fill in this knowledge gap by exploring the modelling potential of nine Baltic Sea ecosystem models to support this specific European policy and, in particular, models' capabilities to inform on marine biodiversity. Several links are found between the Model-Derived Indicators and some of the relevant biodiversity-related descriptors (i.e. biological diversity and food webs), and pressures (i.e. interference with hydrological processes, nutrient and organic matter enrichment and marine acidification). However several gaps remain, in particular in the limited representation of habitats other than the pelagic that the models are able to address for descriptor sea-floor integrity and inability to assess descriptor non-indigenous species. The general outcome is that the Baltic Sea models considered do not adequately cover all the requested needs of the MSFD, but can potentially do so to a certain extent, while for some descriptors/ criteria/indicators/pressures new indicators and/or modelling techniques need to be developed in order to satisfactorily address the requirement of the MSFD and assess the environmental status of the Baltic Sea

    Non-pharmaceutical Interventions and Social Distancing as Intersubjective Care and Collective Protection

    Get PDF
    The paper discusses non-pharmaceutical interventions (NPIs) as a collective form of protection that, in terms of health justice, benefits groups at risk, allowing them to engage in social life and activities during health crises. More specifically, the paper asserts that NPIs that realize social distancing are justifiable insofar as they are constitutive of a type of social protection that allows everyone, especially social disadvantaged agents, to access the public health sphere and other fundamental social spheres, such as the family and civil society.publishedVersionPeer reviewe
    corecore