Dynamical and anharmonic effects on the electron-phonon coupling and the zero-point renormalization of the electronic structure

The renormalization of the band structure at zero temperature due to electron-phonon coupling is investigated in diamond, BN, LiF and MgO crystals. We implement a dynamical scheme to compute the frequency-dependent self-energy and the resulting quasiparticle electronic structure. Our calculations reveal the presence of a satellite band below the Fermi level of LiF and MgO. We show that the renormalization factor (Z), which is neglected in the adiabatic approximation, can reduce the zero-point renormalization (ZPR) by as much as 40%. Anharmonic effects in the renormalized eigenvalues at finite atomic displacements are explored with the frozen-phonon method. We use a non-perturbative expression for the ZPR, going beyond the Allen-Heine-Cardona theory. Our results indicate that high-order electron-phonon coupling terms contribute significantly to the zero-point renormalization for certain materials

Accounting for end-user preferences in earthquake early warning systems

Earthquake early warning systems (EEWSs) that rapidly trigger risk-reduction actions after a potentially-damaging earthquake is detected are an attractive tool to reduce seismic losses. One brake on their implementation in practice is the difficulty in setting the threshold required to trigger pre-defined actions: set the level too high and the action is not triggered before potentially-damaging shaking occurs and set the level too low and the action is triggered too readily. Balancing these conflicting requirements of an EEWS requires a consideration of the preferences of its potential end users. In this article a framework to define these preferences, as part of a participatory decision making procedure, is presented. An aspect of this framework is illustrated for a hypothetical toll bridge in a seismically-active region, where the bridge owners wish to balance the risk to people crossing the bridge with the loss of toll revenue and additional travel costs in case of bridge closure. Multi-attribute utility theory (MAUT) is used to constrain the trigger threshold for four owners with different preferences. We find that MAUT is an appealing and transparent way of aiding the potentially controversial decision of what level of risk to accept in EEW

Earthquake early warning and operational earthquake forecasting as real-time hazard information to mitigate seismic risk at nuclear facilities

Based on our experience in the project REAKT, we present a methodological framework to evaluate the potential benefits and costs of using Earthquake Early Warning (EEW) and Operational Earthquake Forecasting (OEF) for real-time mitigation of seismic risk at nuclear facilities. We focus on evaluating the reliability, significance and usefulness of the aforementioned real-time risk-mitigation tools and on the communication of real-time earthquake information to end-users. We find that EEW and OEF have significant potential for the reduction of seismic risk at nuclear plants, although much scientific research and testing is still necessary to optimise their operation for these sensitive and highly-regulated facilities. While our test bed was Switzerland, the methodology presented here is of general interest to the community of EEW researchers and end-users and its scope is significantly beyond its specific application within REAKT

Feasibility study on earthquake early warning and operational earthquake forecasting for risk mitigation at nuclear power plants

International audienceWithin the framework of the EC-funded project REAKT (Strategies and Tools for Real Time Earthquake Risk Reduction, FP7, contract no. 282862, 2011-2014, www.reaktproject.eu), a task concerns feasibility study and initial implementation of Earthquake Early Warning (EEW) and timedependent seismic hazard analyses aimed at mitigating seismic risk at nuclear power plants (NPPs) in Switzerland. This study is jointly carried out by academic institutions (the Swiss Seismological Service at ETHZ and BRGM) and in cooperation with swissnuclear, the nuclear energy section of swisselectric, an umbrella organisation for the nuclear power plants in Switzerland, which provide about 40% of the electricity needs of the country. Briefly presented in this contribution are the main investigations carried out and results obtained throughout the development of this task, with special focus on: a) evaluating the performances of the selected EEW algorithm (the Virtual Seismologist, VS) in Switzerland and California, in terms of correct detections, false alerts, and missed events; b) embedding the VS algorithm into the earthquake monitoring software SeisComP3 (www.seiscomp3.org) routinely used by the Swiss Seismological Service for earthquake detections and locations; c) customising the User Display (a graphical interface originally developed at the California Institute of Technology (Caltech) during Phase II of the ShakeAlert project in California) for optimised use at Swiss NPPs; d) presenting synthetic time-dependent hazard scenarios for Switzerland and e) attempting to associate the above input data with potential mitigation actions and related cost and benefits for NPPs in Switzerland

Seismic damage scenarios for Mayotte: a tool for disaster management

A new marine volcano is erupting offshore Mayotte since May 2018, generating numerous earthquakes. The population felt many of them and the stronger shaking of the ongoing sequence caused slight damage to buildings. Historical records also confirm that damaging earthquakes had occurred in the past in this region. Seismic damage scenarios are a key tool for supporting the decision-making process, the preparedness, and for designing appropriate emergency responses. This paper provides the outcomes of a work consisting in improving the seismic risk assessment as a part of disaster risk governance and exposes the scientific background of this workflow. It illustrates its use with two earthquakes. Related post-seismic surveys provide observations that are useful to check the validity of the reference dataset. The paper also discusses the main characteristics of the rapid loss assessment tool that has been developed to provide operational information for crisis management

Targeting the histone methyltransferase G9a activates imprinted genes and improves survival of a mouse model of Prader–Willi syndrome

Prader–Willi syndrome (PWS) is an imprinting disorder caused by a deficiency of paternally expressed gene(s) in the 15q11–q13 chromosomal region. The regulation of imprinted gene expression in this region is coordinated by an imprinting center (PWS-IC). In individuals with PWS, genes responsible for PWS on the maternal chromosome are present, but repressed epigenetically, which provides an opportunity for the use of epigenetic therapy to restore expression from the maternal copies of PWS-associated genes. Through a high-content screen (HCS) of >9,000 small molecules, we discovered that UNC0638 and UNC0642—two selective inhibitors of euchromatic histone lysine N-methyltransferase-2 (EHMT2, also known as G9a)—activated the maternal (m) copy of candidate genes underlying PWS, including the SnoRNA cluster SNORD116, in cells from humans with PWS and also from a mouse model of PWS carrying a paternal (p) deletion from small nuclear ribonucleoprotein N (Snrpn (S)) to ubiquitin protein ligase E3A (Ube3a (U)) (mouse model referred to hereafter as m+/pΔS−U). Both UNC0642 and UNC0638 caused a selective reduction of the dimethylation of histone H3 lysine 9 (H3K9me2) at PWS-IC, without changing DNA methylation, when analyzed by bisulfite genomic sequencing. This indicates that histone modification is essential for the imprinting of candidate genes underlying PWS. UNC0642 displayed therapeutic effects in the PWS mouse model by improving the survival and the growth of m+/pΔS−U newborn pups. This study provides the first proof of principle for an epigenetics-based therapy for PWS

Séisme à la Martinique. 29 novembre 2007. Le Lorrain. Mouvement de terrain

Land movement at the place called Morne Capot on loose formations (red clay), on the edge of gullies following the earthquake of November 29, 2007 in Martinique.This locality is located near Lorrain, the third largest commune on the island. The progressive amplification of the noise, accompanied by a very strong tremor, brutal and interminable according to witnesses, generated panic among the inhabitants of Lorraine and was very strongly felt.This photo was taken during the field mission that took place from December 5 to 11 following the earthquake of November 29, 2007 in Martinique. This earthquake was of magnitude 7.4 (MW), its epicenter being located in the north of the island, at sea. Lorrain is located 22km from the epicenter and the intensity of the tremors felt is VI on the European intensité́ EMS-98 scale. Martinique is, with Guadeloupe, classified in seismicity zone III (decree n°2007-1467 of October 12, 2007) which is the highest seismic hazard level for the French territory. From the point of view of intensities, with a maximum intensity of VI-VII, the earthquake of November 29, 2007 is the most important one felt in Martinique since the earthquake of June 8, 1999 (intensity VII). Macro-seismic intensity reached (in order of distance from the epicenter) VI-VII in the communes of Sainte-Marie, La Trinité, Fort-de-France, Le François, Trois Ilets, Le Marin and Sainte-Anne. The analysis of this earthquake mobilized many people, research laboratories and technical centers. The French Central Seismological Office has prepared a report based on the data processed by the Volcanological and Seismological Observatory of Martinique of the IPGP. The macro-seismic data were collected thanks to the survey forms distributed to the town halls and gendarmerie services by the SIDPC of the prefectures of Martinique and Guadeloupe, thanks to the testimonies filed on the BCSF website and thanks to the information collected during the BCSF field survey that took place from December 5 to 11, 2007. The BCSF's mission is to collect data on the earthquakes felt in France, to gather useful information and to facilitate its dissemination to the actors concerned by the seismic risk or conducting studies or research requiring the use of these observations. It is a member of the Transversal Seismicity Action of the Résif research infrastructure (French Seismological and Geodetic Network).Mouvement de terrain au lieu-dit Morne Capot sur des formations meubles (argiles rouges), en bordures de ravines suite au séisme du 29 novembre 2007 en Martinique.Ce lieu-dit se situe à proximité du Lorrain, troisième commune de l'île par sa superficie. L'amplification progressive du bruit, accompagnée par une très forte secousse, brutale et interminable d'après les témoins, a génèré la panique des Lorinois et a été très fortement ressentie.Cette photo a été prise lors de la mission de terrain qui s'est déroulée du 5 au 11 décembre suite au séisme du 29 novembre 2007 à la Martinique. Ce séisme était de magnitude 7.4 (MW), son épicentre se situant au nord de l’île, en mer. Le Lorrain se situe à 22km de l’épicentre et l’intensité des secousses ressenties est de VI sur l’échelle d’intensité́ européenne EMS-98. La Martinique est, avec la Guadeloupe, classée en zone de sismicité III (décret n°2007-1467 du 12 octobre 2007) qui est le niveau d'aléa sismique le plus élevé pour le territoire français. Du point de vue des intensités, avec une intensité maximale de VI-VII, le séisme du 29 novembre 2007 est le plus important ressenti en Martinique depuis le séisme du 8 juin 1999 (intensité VII). L’intensité macrosismique a atteint (par ordre de distance à l'épicentre) VI-VII dans les communes de Sainte-Marie, La Trinité, Fort-de-France, Le François, Trois Ilets, le Marin et Sainte-Anne. L’analyse de ce séisme a mobilisé de nombreuses personnes, laboratoires de recherche et centres techniques. Le Bureau Central Sismologique Français a élaboré un rapport qui s’est appuyé sur les données traitées par l’Observatoire Volcanologique et Sismologique de Martinique de l’IPGP. Les données macrosismiques ont été collectées grâce aux formulaires d’enquête distribués auprès des mairies et des services de gendarmerie par le SIDPC des préfectures de Martinique et de Guadeloupe, grâce aux témoignages déposés sur le site Internet du BCSF et grâce aux informations recueillies lors de l’enquête BCSF sur le terrain qui s'est déroulée du 5 au 11 décembre 2007. Le BCSF a pour mission de collecter les données sur les séismes ressentis en France, de rassembler les informations utiles et de faciliter leur diffusion vers les acteurs concernés par le risque sismique ou menant des études ou recherches nécessitant l’usage de ces observations. Il est membre de l’Action transverse sismicité de l’infrastructure de recherche Résif (Réseau sismologique et géodésique français)

Développement d'un nouveau connecteur pour garantir la ductilité des structures composites en bois-béton

Tableau d'honneur de la Faculté des études supérieures et postdorales, 2015-2016Les structures composites bois-béton sont largement utilisées aujourd’hui grâce à l’optimisation des performances et du coût de la structure qu’elles permettent. Le comportement de ces structures dépend fortement de la connexion entre les deux matériaux. La conception de ce type d’ouvrage peut rapidement devenir complexe, car il existe une multitude de connecteurs qui ont tout un chacun des comportements qui peuvent être très différents des uns des autres. Dans ce mémoire de maîtrise, un modèle numérique qui permet de calculer avec précision les fréquences naturelles d’une poutre composite est présenté et implémenté. De plus, un modèle qui permet de prédire le comportement statique d’un connecteur ponctuel et d’une poutre composite en tenant compte du comportement non linéaire de chacun des matériaux est présenté et implémenté. Ces modèles reproduisent très bien les essais expérimentaux. Avec les simulations effectuées, il a pu être conclu qu’un connecteur dimensionnable serait l’idéal pour achever une performance ductile d’une poutre composite bois-béton. L’idée de ce type de connecteur est donc explorée et testée en laboratoire. Garantir une performance ductile rend la structure plus sécuritaire et permet ainsi d’augmenter l’utilisation du bois dans le secteur non résidentiel de la construction.The timber-concrete composite structures are widely used today because they allow the performance optimization and the structure cost. The behaviour of timber concrete composite (TCC) structures depends heavily on the connection between the two materials. The design of this type of structure can quickly become complex because there are a host of connectors whose behaviour may be very different from each other. In this master thesis, a numerical model that can accurately calculate the natural frequencies of a composite beam is introduced and implemented. In addition, a model that predicts the static behaviour of a discrete connector and of a composite beam by taking into account the non linear behaviour of each material is presented and implemented. These models reproduce very well the experimental tests.With simulations, it has been found that an engineered connector would be ideal to provide for a ductile performance of a TCC beam. The idea of this type of connector is explored and tested in a laboratory. Ensure ductile performance makes the structure more secure and thus can increase the use of wood in non-residential construction sector