65 research outputs found

    Milnor open books and Milnor fillable contact 3-manifolds

    Get PDF
    We say that a contact manifold is Milnor fillable if it is contactomorphic to the contact boundary of an isolated complex-analytic singularity (X,x). Generalizing results of Milnor and Giroux, we associate to each holomorphic function f defined on X, with isolated singularity at x, an open book which supports the contact structure. Moreover, we prove that any 3-dimensional oriented manifold admits at most one Milnor fillable contact structure up to contactomorphism. * * * * * * * * In the first version of the paper, we showed that the open book associated to f carries the contact structure only up to an isotopy. Here we drop this restriction. Following a suggestion of Janos Kollar, we also give a simplified proof of the algebro-geometrical theorem 4.1, central for the uniqueness result.Comment: 17 page

    Variabilité protéique observée par électrophorÚse bidimensionnelle sur neuf isolats d'Heterodera schachtii provenant de six pays européens et sur deux isolats d'H. trifolii f.sp. beta

    Get PDF
    La variabilité protéique de neuf isolats européens d'#Heterodera schachtii et de deux isolats d'#H. trifolii f. sp. #beta élevés en conditions contrÎlées sur colza, #Brassica napus L. var. #napus$ cv. Samouraï a été étudiée par électrophorÚse bidimensionnelle (E2D). Les gels électrophorétiques sont comparés à l'aide d'un systÚme informatique d'analyse d'images. Les indices de similarité (F) et les distances génétiques (D = 1-F) sont calculés à partir des taches homologues. Le dendrogramme est obtenu avec la méthode UPGMA. Les résultats montrent une assez grande similitude protéique des deux espÚces. Les principales différences interspécifiques sont mises en évidence, ainsi que deux zones communes caractéristiques. Concernant la variabilité infraspécifique, des taches caratéristiques de certains isolats ont été repérées. La possibilité d'utiliser l'E2D pour identifier des protéines liées à la virulence est envisagée, ce qui nécessitera l'étude d'un grand nombre d'isolats. (Résumé d'auteur

    Brieskorn manifolds as contact branched covers of spheres

    Full text link
    We show that Brieskorn manifolds with their standard contact structures are contact branched coverings of spheres. This covering maps a contact open book decomposition of the Brieskorn manifold onto a Milnor open book of the sphere.Comment: 8 pages, 1 figur

    Ultrametric spaces of branches on arborescent singularities

    Get PDF
    Let SS be a normal complex analytic surface singularity. We say that SS is arborescent if the dual graph of any resolution of it is a tree. Whenever A,BA,B are distinct branches on SS, we denote by A⋅BA \cdot B their intersection number in the sense of Mumford. If LL is a fixed branch, we define UL(A,B)=(L⋅A)(L⋅B)(A⋅B)−1U_L(A,B)= (L \cdot A)(L \cdot B)(A \cdot B)^{-1} when A≠BA \neq B and UL(A,A)=0U_L(A,A) =0 otherwise. We generalize a theorem of P{\l}oski concerning smooth germs of surfaces, by proving that whenever SS is arborescent, then ULU_L is an ultrametric on the set of branches of SS different from LL. We compute the maximum of ULU_L, which gives an analog of a theorem of Teissier. We show that ULU_L encodes topological information about the structure of the embedded resolutions of any finite set of branches. This generalizes a theorem of Favre and Jonsson concerning the case when both SS and LL are smooth. We generalize also from smooth germs to arbitrary arborescent ones their valuative interpretation of the dual trees of the resolutions of SS. Our proofs are based in an essential way on a determinantal identity of Eisenbud and Neumann.Comment: 37 pages, 16 figures. Compared to the first version on Arxiv, il has a new section 4.3, accompanied by 2 new figures. Several passages were clarified and the typos discovered in the meantime were correcte

    Regionally aggregated, stitched and de‐drifted CMIP‐climate data, processed with netCDF‐SCM v2.0.0

    Get PDF
    The world's most complex climate models are currently running a range of experiments as part of the Sixth Coupled Model Intercomparison Project (CMIP6). Added to the output from the Fifth Coupled Model Intercomparison Project (CMIP5), the total data volume will be in the order of 20PB. Here, we present a dataset of annual, monthly, global, hemispheric and land/ocean means derived from a selection of experiments of key interest to climate data analysts and reduced complexity climate modellers. The derived dataset is a key part of validating, calibrating and developing reduced complexity climate models against the behaviour of more physically complete models. In addition to its use for reduced complexity climate modellers, we aim to make our data accessible to other research communities. We facilitate this in a number of ways. Firstly, given the focus on annual, monthly, global, hemispheric and land/ocean mean quantities, our dataset is orders of magnitude smaller than the source data and hence does not require specialized ‘big data’ expertise. Secondly, again because of its smaller size, we are able to offer our dataset in a text-based format, greatly reducing the computational expertise required to work with CMIP output. Thirdly, we enable data provenance and integrity control by tracking all source metadata and providing tools which check whether a dataset has been retracted, that is identified as erroneous. The resulting dataset is updated as new CMIP6 results become available and we provide a stable access point to allow automated downloads. Along with our accompanying website (cmip6.science.unimelb.edu.au), we believe this dataset provides a unique community resource, as well as allowing non-specialists to access CMIP data in a new, user-friendly way

    Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5

    Get PDF
    We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, and a comprehensive representation of aerosols. As it represents the principal dynamical, physical, and bio-geochemical processes relevant to the climate system, it may be referred to as an Earth System Model. However, the IPSL-CM5 model may be used in a multitude of configurations associated with different boundary conditions and with a range of complexities in terms of processes and interactions. This paper presents an overview of the different model components and explains how they were coupled and used to simulate historical climate changes over the past 150 years and different scenarios of future climate change. A single version of the IPSL-CM5 model (IPSL-CM5A-LR) was used to provide climate projections associated with different socio-economic scenarios, including the different Representative Concentration Pathways considered by CMIP5 and several scenarios from the Special Report on Emission Scenarios considered by CMIP3. Results suggest that the magnitude of global warming projections primarily depends on the socio-economic scenario considered, that there is potential for an aggressive mitigation policy to limit global warming to about two degrees, and that the behavior of some components of the climate system such as the Arctic sea ice and the Atlantic Meridional Overturning Circulation may change drastically by the end of the twenty-first century in the case of a no climate policy scenario. Although the magnitude of regional temperature and precipitation changes depends fairly linearly on the magnitude of the projected global warming (and thus on the scenario considered), the geographical pattern of these changes is strikingly similar for the different scenarios. The representation of atmospheric physical processes in the model is shown to strongly influence the simulated climate variability and both the magnitude and pattern of the projected climate changes
    • 

    corecore