Reducibility of the intersections of components of a Springer fiber

The description of the intersections of components of a Springer fiber is a very complex problem. Up to now only two cases have been described completely. The complete picture for the hook case has been obtained by N. Spaltenstein and J.A. Vargas, and for two-row case by F.Y.C. Fung. They have shown in particular that the intersection of a pair of components of a Springer fiber is either irreducible or empty. In both cases all the components are non-singular and the irreducibility of the intersections is strongly related to the non-singularity. As it has been shown in [8] a bijection between orbital varieties and components of the corresponding Springer fiber in GL_n extends to a bijection between the irreducible components of the intersections of orbital varieties and the irreducible components of the intersections of components of Springer fiber preserving their codimensions. Here we use this bijection to compute the intersections of the irreducible components of Springer fibers for two-column case. In this case the components are in general singular. As we show the intersection of two components is non-empty. The main result of the paper is a necessary and sufficient condition for the intersection of two components of the Springer fiber to be irreducible in two-column case. The condition is purely combinatorial. As an application of this characterization, we give first examples of pairs of componentswith a reducible intersection having components of different dimensions.Comment: 20 pages; the final version, to appear in Indagationes Mathematica

Observations sur une chape rouge de l'ancienne abbaye de Saint-Papoul (Aude)

International audiencePreliminary study on the technique and dating of a remarkable cope whose base fabricseems to come from the mid-17th century, while the fabric of the orphreys and hoodseems to have been made in the East during the first half of the 18th century.Première étude sur la technique et la datation d’une chape insigne dont le tissu de fondsemble du milieu du XVIIe siècle tandis que le tissu des orfrois et du chaperon aurait étéexécuté en Orient durant la première moitié du XVIIIe siècle

Generic fibers of the generalized Springer resolution of type A

AbstractIt is well known that when the Lie algebra is of type A, D, E the Springer fiber above a subregular nilpotent element is described by the Dynkin diagram and is called the Dynkin curve of the Lie algebra. On the other hand, the closure of the minimal nilpotent orbit is obtained by collapsing the zero section of a cotangent bundle of a projective space Pk. In this article, we are interested in the study of the generalized Springer resolution of type A, we give a complete description of the generalized Springer fiber above a generic singularities showing that it is isomorphic to a Dynkin curve or to a projective space

Caprier ou aristoloche ?: Fortune of an idea, birth of a textile design

International audienceThis article focuses on the history of a design that was created around 1510 and realisedusing different techniques, from mural painting to silk textile printing as well as easelpainting. Its popularity through the centuries, the design appearing until the 20th century,and the geographical extent of its success, from England to Turkey, make it an exceptionalcase.Cet article s’attache à l’histoire d’un dessin créé vers 1510 et décliné en différentes techniques,de la peinture murale au textile de soie en passant par la peinture de chevalet.sa longévité, jusqu’au XXe siècle et l’étendue géographique de son succès, de l’Angleterreà la Turquie, en font un motif exceptionnel

A review of online sources of open-access life cycle assessment data for the construction sector

The importance of life cycle sustainability in the construction sector is increasing in the light of rising awareness on sustainability issues in society. A means to identify more sustainable options is to assess and compare their sustainability performance. The standards ISO 21931-2 and EN 15643-1 to 5 establish the framework and requirements for sustainability assessment of buildings and civil engineering works. The standards require life cycle assessment (LCA) to be the basis for the environmental part of the sustainability assessment. LCA is a powerful evidence-based method but it requires extensive data. Access to free, easily available and preferably machine-readable LCA data is essential to increase the use of LCA in the construction sector and to make competition fair for all tenderers. This paper aims to compile existing online sources for open-access LCA data of interest for the construction sector. The purpose is to provide a reference document that facilitates the use of LCA in construction. An in-depth search of publications and internet resources was performed, focusing on European sources of Environmental Product Declarations (EPD) and process-based LCA datasets. A comprehensive overview of the European data sources available online and relevant to the construction sector is presented. This research work reveals the existence of numerous sources, often difficult and time-consuming to find. The overview in the paper facilitates finding online data needed for LCA, in many cases in a machine-readable format. This can contribute to increasing the use of LCA in the construction sector, which is important when developing buildings or civil engineering works that are more sustainable over their whole life cycle. A greater use and better integration of LCA in the design process contributes to evidence-based life cycle sustainability of our built environment

Sustainable development goals and indicators: can they be tools to make national budgets more sustainable?

This article explores the use and added value of the Sustainable Development Goals (SDGs) and indicators in the budgeting process. Several countries have announced in their voluntary national reviews (VNRs) their intention to use the SDGs in their budgetary processes, but few have specified why it would be relevant to do so, or how it could be implemented. Based on nine case studies conducted through interviews, we found that SDG budgeting is still in its infancy. We nevertheless identified four ways in which countries are starting to integrate the SDGs into budgeting processes. Most of the countries we studied either map their budgets against the SDGs or include qualitative reporting in their main budget document. Less often, countries use the SDGs to improve their budget performance evaluation system or as a management tool for resource allocation. Most of the countries follow a technical approach. Only rarely are the SDGs used politically or referenced in the budgetary debate

« Une œuvre inutile » ? La scolarisation des filles par les missionnaires catholiques dans le Sud-Est du Nigéria (1885-1930)

Cet article est tiré d’une recherche sur l’œuvre éducative des Pères du Saint-Esprit et des Sœurs de Saint-Joseph de Cluny, missionnaires catholiques, dans le Sud-Est du Nigeria de 1885 à 1930. En 1925-1926, ils scolarisent 45 000 garçons contre 225 filles seulement dans 1 191 écoles dont 1 école de filles. Malgré une volonté initiale avérée de scolariser les filles, il semble que ces écoles missionnaires soient surtout masculines. Quels ont été les facteurs à l’origine de cette sous-scolarisation féminine ? Les obstacles ou résistances à la scolarisation féminine, recensés dans les archives de ces deux congrégations, sont le fait de tous les acteurs de l’éducation, des Pères et des Sœurs tout comme de la population locale masculine et féminine Igbo, Ibibio et Effik. Ils sont essentiellement d’ordre socio-culturels, puis économiques et enfin liés à un manque de qualification des missionnaires.This article is an extract from a study made three years ago. It is dealing about the Spiritan Fathers and the Holy-Joseph’s Sisters of Cluny, both catholic missionaries, who worked together in the South-East of Nigeria in order to evangelize the local population. They have mainly conducted educational activities. In 1925-1926, they have registered 45 000 boys and 225 girls in their 1 191 schools, which only one is for the girls, despite their first will to scolarize the girls as equally as the boys. What are the factors conducive to this gender discrimination ? They are mainly socio-cultural and economic causes to this under-scolarization of girls, emanating from all the actors of education, the missionaries, Fathers and Sisters and the local population from the men as the women

Review of multi-hazard indices : Focus on methods applicable for a Swedish context

A literature review of methods where different hazards are combined into a multi-hazard index or method are presented in this report. The purpose of the review is to get an insight into approaches to combine different hazards into a multi-hazard index or method. To directly combine hazards, it is necessary to present them with the same unit of measure. This can be done with different measures for normalizing or using weights. Maps are often used to get an understanding of the spatial distribution of the hazard as well as the hazard level. No specific method or tool that can be applied directly for relevant hazards in Sweden have been found in this review. However, several general principles and methods that are considered valuable for the Extreme-Index project are identifie