Adaptation multi-niveaux : l'infrastructure au service des applications

National audienceDe plus en plus d'applications sont construites à base de services et exécutées dans des environnements large échelle, dynamiques et distribués. La notion de "cloud" est souvent utilisée pour parler de ces environnements. Le paradigme de cloud computing correspond à un ensemble de niveaux indépendants ayant chacun leurs propres objectifs. Ces objectifs sont aussi bien de garantir la qualité de service fournie aux utilisateurs que de gérer les ressources disponibles. Mais la qualité de service tout comme les ressources disponibles peuvent évoluer au fil de l'exécution et les différents niveaux doivent s'adapter à ces évolutions. Du fait de leur indépendance, ces différents niveaux s'adaptent indépendamment les uns des autres. Pourtant si l'on considère un ensemble d'adaptations s'effectuant sur des niveaux différents, il est possible que ces adaptations soient contradictoires ou redondantes entre elles, ne produisant pas au final l'effet escompté ou bien l'atteignant de manière non performante. Nous présentons dans cet article ce que nous appelons adaptation multi-niveaux ainsi que l'intérêt qu'elle peut avoir. Nous illustrons cet intérêt sur le cas de la migration de service permettant d'adapter une application en utilisant l'infrastructure sous-jacente et ses capacités

Exotic traveling waves for a quasilinear Schr\"odinger equation with nonzero background

We study a defocusing quasilinear Schr\"odinger equation with nonzero conditions at infinity in dimension one. This quasilinear model corresponds to a weakly nonlocal approximation of the nonlocal Gross--Pitaevskii equation, and can also be derived by considering the effects of surface tension in superfluids. When the quasilinear term is neglected, the resulting equation is the classical Gross-Pitaevskii equation, which possesses a well-known stable branch of subsonic traveling waves solution, given by dark solitons. Our goal is to investigate how the quasilinear term affects the traveling-waves solutions. We provide a complete classification of finite energy traveling waves of the equation, in terms of the two parameters: the speed and the strength of the quasilinear term. This classification leads to the existence of dark and antidark solitons, as well as more exotic localized solutions like dark cuspons, compactons, and composite waves, even for supersonic speeds. Depending on the parameters, these types of solutions can coexist, showing that finite energy solutions are not unique. Furthermore, we prove that some of these dark solitons can be obtained as minimizers of the energy, at fixed momentum, and that they are orbitally stable

Distribution and Self-Adaptation of a Framework for Dynamic Adaptation of Services

International audienceThe dynamism and scale of the infrastructure of the Internet of Services bring new needs to build autonomous services. These services have to be able to self-adapt to the variation of the environment. Moreover, these adaptations may span across multiple services and thus have to be coordinated, without breaking their autonomy. To this end we describe in this paper the approach we have chosen for SAFDIS, a framework to make coordinated adaptations of services. In this presentation, a particular emphasis is made on the distribution of the framework and how it helps to coordinate distributed adaptation. Benefits from the self-adaptation of the framework itself are also presented

Représentations graphiques et indicateurs des mobilités et des dynamiques de peuplement : contribution bibliographique

La Base Endnote sera adressée à toute personne en faisant la demande auprès de Françoise Dureau : [email protected] main goal of the MOBIDYC research project (Mobilities and population movement: graphics and indicators) was to contribute to the definition of processing sequences that integrate both temporal and spatial dimensions of information related to spatial mobility (be it migration, residential mobility or daily mobility). Workshops were held on a quarterly basis to bring team members together. Between meetings, members worked separately on their own datasets. A first workshop was dedicated to the sharing of experience from previous work by members of the team. Then we focused on inventorying other experiences through bibliographic research. The aim of this article is to make the results of this research available to the scientific community. After stating the whys and hows of the collection of this bibliographic corpus, we present the material in the appendix: an Endnote set of references, along with a descriptive table synthesizing the content of these references. Finally, we present the main lessons we have learned through the analysis of this bibliographic corpus and from tests we carried out based on the methods described in the literature.L'objectif général du projet MOBIDYC (Mobilités et dynamiques de peuplement : représentations graphiques et production d'indicateurs) était d'avancer dans la définition de chaînes de traitement de l'information sur les mobilités spatiales (biographies migratoires et résidentielles, trajectoires de mobilité quotidienne) intégrant les deux dimensions, temporelles et spatiales, de l'information. La méthode de travail a consisté en un atelier réunissant les membres de l'équipe à un rythme trimestriel ; entre les séances de l'atelier, les chercheurs impliqués dans le projet ont travaillé en parallèle sur leurs corpus de données respectifs. Après une première étape consacrée à la mutualisation de nos expériences respectives, l'accent a été mis sur la recherche bibliographique et la recension des expériences dans le champ du projet. L'objectif de cet article est de mettre à disposition de la communauté scientifique le résultat de ce travail bibliographique. Après avoir rappelé les objectifs et conditions de réalisation de la base de données bibliographiques, nous présentons les informations mises à disposition en annexes de cet article : tableau de description synthétique des références bibliographiques, et la base Endnote des références . Enfin, nous livrons les principaux enseignements que nous avons tirés de l'analyse de ce corpus bibliographique, et des tests effectués à partir des méthodes identifiées dans la littérature

Ouessant: Flexible Integration of Dedicated Coprocessors in Systems On Chip

International audienceIntegration of hardware accelerators in System on Chips is often complex. When dealing with reconfigurable hard- ware, this greatly limits the attainable flexibility. In this paper, we propose an alternative approach to the Molen paradigm [1]. This approach, named Ouessant, is based on a very simple general purpose instruction set designed for close interaction with dedicated hardware accelerators. This instruction set is used to program a dedicated controler, which commands the accelerator's execution and data transfer with minimal CPU intervention. The resulting architecture is flexible, extensible, and can be easily integrated in System on Chips. Adding new accelerators is also made easier. Implementation of the architecture on different FPGA resources show very low footprint and a very small impact on attainable performance. Ouessant is freely available under an open-source license

The Raman spectrum of CaCO3 polymorphs calcite and aragonite: A combined experimental and computational study

Powder and single crystal Raman spectra of the two most common phases of calcium carbonate are calculated with ab initio techniques (using a “hybrid” functional and a Gaussian-type basis set) and measured both at 80 K and room temperature. Frequencies of the Raman modes are in very good agreement between calculations and experiments: the mean absolute deviation at 80 K is 4 and 8 cm−1 for calcite and aragonite, respectively. As regards intensities, the agreement is in general good, although the computed values overestimate the measured ones in many cases. The combined analysis permits to identify almost all the fundamental experimental Raman peaks of the two compounds, with the exception of either modes with zero computed intensity or modes overlapping with more intense peaks. Additional peaks have been identified in both calcite and aragonite, which have been assigned to 18O satellite modes or overtones. The agreement between the computed and measured spectra is quite satisfactory; in particular, simulation permits to clearly distinguish between calcite and aragonite in the case of powder spectra, and among different polarization directions of each compound in the case of single crystal spectra

Breaking the fast: first report of dives and ingestion events in molting southern elephant seals

Southern elephant seals (SES) experience a ‘catastrophic molt’, a costly event characterized by the renewal of both hair and epidermis that requires high peripheral vascular circulation. Molting animals are therefore constrained by high metabolic heat loss and are thought to fast and remain on land. To examine the ability of individuals to balance the energetic constraints of molting on land we investigate the stomach temperature and movement patterns of molting female SES. We find that 79% of females swam and 61% ingested water or prey items, despite the cost of cold-water exposure while molting. This behavior was related to periods of warm and low wind conditions, and females that dived and ingested more often, lost less body mass. We conclude that the paradigm of fasting during the molt in this species, and the fitness consequences of this behavior should be reconsidered, especially in the context of a changing climate

Un Paradis perdu. Restaurer ou les effets de l'intervention humaine sur le cours du temps – à propos de quelques réalités monumentales (France, Cambodge)

Les interventions sur les monuments anciens en milieu rural gagneront à être plus « légères » qu’en milieu urbain, dès lors que la part du temps est prise en considération. En France comme au Cambodge, toute restauration complète appelle d’autres travaux à un rythme plus rapproché, plus difficiles d’exécution, plus importants en moyens et plus impactants sur les architectures et sculptures. Entre le XIIe et le XIXe siècle, les maçonneries des églises romanes d’Auvergne ont été peu entretenues, mais l’épiderme des matériaux de construction a globalement bien tenu. Un siècle après les restaurations du XIXe siècle, du fait de l’utilisation des ciments durs et de matériaux exogènes, la dégradation des parties restaurées et non restaurées impose de nouvelles interventions rapprochées dans le temps, alors que la première période n’avait connu aucune grande phase de restauration, l’entretien seul ayant suffi.La déforestation est quant à elle la principale cause de la dégradation accélérée des maçonneries assemblées à sec des temples khmers, mais on tirera une leçon utile de l’exemple du temple de Ta Prohm à Angkor qui conserve son couvert forestier protecteur. Dès lors que l’exubérance de la végétation est contrôlée, au Cambodge comme en France, un édifice ancien supporte aisément la présence de mousses, lichens et cyanobactéries, voire de graminées, qui enveloppent le site dans un biofilm protecteur. À l’inverse, chaque restauration ou nettoyage déclenche l’installation rapide d’organismes jeunes plus agressifs que les organismes âgés vivant au ralenti et finissant par former une « biopatine » protectrice. Face aux bouleversements industriels, le XIXe siècle a restauré ses édifices emblématiques. Notre siècle doit probablement conserver de manière raisonnée des références monumentales synonymes d’une lente disparition. Pourtant un édifice ayant subi de multiples interventions se corrigeant les unes les autres, produit d’une économie de loisirs, ne produira jamais l’émotion d’une ruine discrètement entretenue dans laquelle il est possible de se perdre, en dehors de tout itinéraire balisé et de toute proposition pédagogique. Le « réensauvagement » de sites ruraux est donc un enjeu qui dépasse « l’absolue nécessité », en réalité toute relative des restaurations.Interventions on ancient monuments in rural areas will benefit from being "lighter" than in urban areas, as long as the time issue is taken into account. In France as in Cambodia, any complete restoration calls for other works at a closer pace, more difficult to carry out, more important in terms of resources and more impacting on architectures and sculptures. Between the 12th and the 19th century, the masonry of Romanesque churches in Auvergne was poorly maintained, but the building materials epidermis has generally held up quite well. A century and a half after the 19th century restorations, due to using hard cements and exogenous materials, degradation of the restored and unrestored parts requires new close in time interventions, whereas the first period had not seen any major restoration phase, maintenance alone did suffice.Deforestation is the main cause of the accelerated degradation of dry-assembled masonry of Khmer temples, but a useful lesson will be learned from the example of Ta Prohm temple in Angkor which retains its protective forest cover. As soon as the vegetation exuberance is controlled, in Cambodia as in France, an old building easily supports the presence of mosses, lichens and cyanobacteria, even grasses, which envelop the site in a protective biofilm. Conversely, each restoration or cleaning triggers the rapid installation of young organisms that are more aggressive than older organisms living in slow motion and eventually forming a protective “biopatin”. Faced with industrial upheavals, the 19th century restored its iconic monuments. Our century must probably preserve in a reasoned way monumental references reflecting a slow disappearance. However, a building that has undergone multiple interventions correcting each other, in a leisure economy, will never produce the emotion of a discreetly maintained ruin in which on can get lost, apart from any marked route and any educational proposal. Rural sites “going back to the wild” is therefore an issue that goes beyond the restorations “absolute – actually all relative – necessity”

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Contribution of quantum chemical methods (DFT and TD-DFT) to the study of metal complexation mechanisms by humic substances models

Les substances humiques sont issues de la dégradation de résidus organiques et représentent la partie la plus importante de la matière organique des sols. Celles-ci sont capables de piéger de nombreux polluants comme les métaux et jouent donc un rôle majeur dans la rétention des ions métalliques. Leurs propriétés complexantes sont dues principalement à certaines fonctions récurrentes : les groupements carboxyliques et phénoliques. La structure de ces macromolécules étant méconnue, une approche pour comprendre les interactions métallo-humiques consiste à étudier des molécules modèles plus simples, et qui possèdent les mêmes groupements fonctionnels. L'acide protocatéchuique présente l'intérêt de mettre en compétition vis-à-vis de la complexation les fonctions acide carboxylique et catéchol (groupement 1,2dihydroxybenzoïque) . Les réactions de complexation d'AI(Ill) et de Pb(ll) par l'acide protocatéchuique ont été suivies pour différents pH. Les méthodes de chimie quantique combinées à la spectroscopie électronique ont permis de caractériser les complexes formés, mais aussi de déterminer les mécanismes de complexation et d'expliquer la régiosélectivité des réactions. Pour les deux ions métalliques un changement de site de fixation a été mis en évidence lorsque le pH augmente. Par ailleurs, l'étude de la complexation d'Al(Ill) et de Pb(ll) par deux isomères de l'acide protocatéchuique : les acides 2pyrocatéchuique et ß-resorcylique, a permis de constater l'influence de la position des fonctions complexantes sur le cycle benzénique sur la fixation métallique.Humic substances result from the degradation of organic residues and represent the greatest part of the soil organic matter. They are able to trap many pollutants like heavy metals and play a major role in the metal ions retention. Their complexing properties are mainly due to sorne recurrent functions: carboxylic and phenolic groups. The macromolecular structure of these molecules being unknown, a way to understand metallo-humic interactions consist in studying simpler model molecules which posses the same functional groups. Protocatechuic acid presents carboxylic acid and catechol (1,2-dihydroxybenzoic group) functions in competition toward metal complexation. Complexation reactions of AI(Ill) and Pb (II) by protocatechuic acid have been followed for different pH. Quantum chemical methods combined with electronic spectroscopy have allowed characterising the formed complexes, as well as to determine the complexation mechanisms and explain the regioselectivity of the reactions. For both metal ions, a change in the fixing site along with an increase of the pH has been higWighted. Besides, the study of Al(Ill) and Pb(II) complexations by two protocatechuic isomers: the 2-pyrocatechuic and ß-resorcylic acids, has allowed the observation of the influence of the complexing functions position around the benzene ring on the metal fixation