222 research outputs found
Adaptation multi-niveaux : l'infrastructure au service des applications
National audienceDe plus en plus d'applications sont construites Ă base de services et exĂ©cutĂ©es dans des environnements large Ă©chelle, dynamiques et distribuĂ©s. La notion de "cloud" est souvent utilisĂ©e pour parler de ces environnements. Le paradigme de cloud computing correspond Ă un ensemble de niveaux indĂ©pendants ayant chacun leurs propres objectifs. Ces objectifs sont aussi bien de garantir la qualitĂ© de service fournie aux utilisateurs que de gĂ©rer les ressources disponibles. Mais la qualitĂ© de service tout comme les ressources disponibles peuvent Ă©voluer au fil de l'exĂ©cution et les diffĂ©rents niveaux doivent s'adapter Ă ces Ă©volutions. Du fait de leur indĂ©pendance, ces diffĂ©rents niveaux s'adaptent indĂ©pendamment les uns des autres. Pourtant si l'on considĂšre un ensemble d'adaptations s'effectuant sur des niveaux diffĂ©rents, il est possible que ces adaptations soient contradictoires ou redondantes entre elles, ne produisant pas au final l'effet escomptĂ© ou bien l'atteignant de maniĂšre non performante. Nous prĂ©sentons dans cet article ce que nous appelons adaptation multi-niveaux ainsi que l'intĂ©rĂȘt qu'elle peut avoir. Nous illustrons cet intĂ©rĂȘt sur le cas de la migration de service permettant d'adapter une application en utilisant l'infrastructure sous-jacente et ses capacitĂ©s
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. BeneïŹts 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 auprÚs 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 chaßnes 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 parallÚle sur leurs corpus de données respectifs. AprÚs une premiÚre 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. AprÚs 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 âhybridâ 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 cmâ1 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 âcatastrophic moltâ, 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 â Ă propos de quelques rĂ©alitĂ©s monumentales (France, Cambodge)
Les interventions sur les monuments anciens en milieu rural gagneront Ă ĂȘtre plus « lĂ©gĂšres » quâen milieu urbain, dĂšs lors que la part du temps est prise en considĂ©ration. En France comme au Cambodge, toute restauration complĂšte appelle dâautres travaux Ă un rythme plus rapprochĂ©, plus difficiles dâexĂ©cution, plus importants en moyens et plus impactants sur les architectures et sculptures. Entre le XIIe et le XIXe siĂšcle, les maçonneries des Ă©glises romanes dâAuvergne ont Ă©tĂ© peu entretenues, mais lâĂ©piderme des matĂ©riaux de construction a globalement bien tenu. Un siĂšcle aprĂšs les restaurations du XIXe siĂšcle, du fait de lâutilisation des ciments durs et de matĂ©riaux exogĂšnes, la dĂ©gradation des parties restaurĂ©es et non restaurĂ©es impose de nouvelles interventions rapprochĂ©es dans le temps, alors que la premiĂšre pĂ©riode nâavait connu aucune grande phase de restauration, lâentretien seul ayant suffi.La dĂ©forestation est quant Ă elle la principale cause de la dĂ©gradation accĂ©lĂ©rĂ©e des maçonneries assemblĂ©es Ă sec des temples khmers, mais on tirera une leçon utile de lâexemple du temple de Ta Prohm Ă Angkor qui conserve son couvert forestier protecteur. DĂšs lors que lâexubĂ©rance de la vĂ©gĂ©tation est contrĂŽlĂ©e, au Cambodge comme en France, un Ă©difice ancien supporte aisĂ©ment la prĂ©sence de mousses, lichens et cyanobactĂ©ries, voire de graminĂ©es, qui enveloppent le site dans un biofilm protecteur. Ă lâinverse, chaque restauration ou nettoyage dĂ©clenche lâinstallation rapide dâorganismes jeunes plus agressifs que les organismes ĂągĂ©s vivant au ralenti et finissant par former une « biopatine » protectrice. Face aux bouleversements industriels, le XIXe siĂšcle a restaurĂ© ses Ă©difices emblĂ©matiques. Notre siĂšcle doit probablement conserver de maniĂšre raisonnĂ©e des rĂ©fĂ©rences monumentales synonymes dâune lente disparition. Pourtant un Ă©difice ayant subi de multiples interventions se corrigeant les unes les autres, produit dâune Ă©conomie de loisirs, ne produira jamais lâĂ©motion dâune ruine discrĂštement entretenue dans laquelle il est possible de se perdre, en dehors de tout itinĂ©raire balisĂ© et de toute proposition pĂ©dagogique. Le « rĂ©ensauvagement » de sites ruraux est donc un enjeu qui dĂ©passe « lâabsolue nĂ©cessité », en rĂ©alitĂ© 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 âbiopatinâ. 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 âgoing back to the wildâ is therefore an issue that goes beyond the restorations âabsolute â actually all relative â necessityâ
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 60â109 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:
âTypicalâ 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 (â€â18 years: 69, 48, 23; 85%), older adults (â„â70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each Pâ<â0.001). 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 dĂ©gradation de rĂ©sidus organiques et reprĂ©sentent la partie la plus importante de la matiĂšre organique des sols. Celles-ci sont capables de piĂ©ger de nombreux polluants comme les mĂ©taux et jouent donc un rĂŽle majeur dans la rĂ©tention des ions mĂ©talliques. Leurs propriĂ©tĂ©s complexantes sont dues principalement Ă certaines fonctions rĂ©currentes : les groupements carboxyliques et phĂ©noliques. La structure de ces macromolĂ©cules Ă©tant mĂ©connue, une approche pour comprendre les interactions mĂ©tallo-humiques consiste Ă Ă©tudier des molĂ©cules modĂšles plus simples, et qui possĂšdent les mĂȘmes groupements fonctionnels. L'acide protocatĂ©chuique prĂ©sente l'intĂ©rĂȘt de mettre en compĂ©tition vis-Ă -vis de la complexation les fonctions acide carboxylique et catĂ©chol (groupement 1,2dihydroxybenzoĂŻque) . Les rĂ©actions de complexation d'AI(Ill) et de Pb(ll) par l'acide protocatĂ©chuique ont Ă©tĂ© suivies pour diffĂ©rents pH. Les mĂ©thodes de chimie quantique combinĂ©es Ă la spectroscopie Ă©lectronique ont permis de caractĂ©riser les complexes formĂ©s, mais aussi de dĂ©terminer les mĂ©canismes de complexation et d'expliquer la rĂ©giosĂ©lectivitĂ© des rĂ©actions. Pour les deux ions mĂ©talliques un changement de site de fixation a Ă©tĂ© mis en Ă©vidence lorsque le pH augmente. Par ailleurs, l'Ă©tude de la complexation d'Al(Ill) et de Pb(ll) par deux isomĂšres de l'acide protocatĂ©chuique : les acides 2pyrocatĂ©chuique et Ă-resorcylique, a permis de constater l'influence de la position des fonctions complexantes sur le cycle benzĂ©nique sur la fixation mĂ©tallique.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 Ă-resorcylic acids, has allowed the observation of the influence of the complexing functions position around the benzene ring on the metal fixation
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