From temporal network data to the dynamics of social relationships

Networks are well-established representations of social systems, and temporal networks are widely used to study their dynamics. Temporal network data often consist in a succession of static networks over consecutive time windows whose length, however, is arbitrary, not necessarily corresponding to any intrinsic timescale of the system. Moreover, the resulting view of social network evolution is unsatisfactory: short time windows contain little information, whereas aggregating over large time windows blurs the dynamics. Going from a temporal network to a meaningful evolving representation of a social network therefore remains a challenge. Here we introduce a framework to that purpose: transforming temporal network data into an evolving weighted network where the weights of the links between individuals are updated at every interaction. Most importantly, this transformation takes into account the interdependence of social relationships due to the finite attention capacities of individuals: each interaction between two individuals not only reinforces their mutual relationship but also weakens their relationships with others. We study a concrete example of such a transformation and apply it to several data sets of social interactions. Using temporal contact data collected in schools, we show how our framework highlights specificities in their structure and temporal organization. We then introduce a synthetic perturbation into a data set of interactions in a group of baboons to show that it is possible to detect a perturbation in a social group on a wide range of timescales and parameters. Our framework brings new perspectives to the analysis of temporal social networks

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Conception, synthèse par chimie douce et caractérisation de revêtements sol-gel hybrides multifonctionnels sur polycarbonate

Le polycarbonate (PC) est un matériau polymère très répandu, fort apprécié pour sa faible densité, sa transparence, ses bonnes propriétés mécaniques et surtout pour son faible coût. Même s’il présente quelques limites essentiellement liées à sa faible résistance à l’abrasion, à la rayure et à sa dégradation dans le temps (sous UV ou hydrolyse), le PC trouve sa place dans un large spectre d’applications (bâtiment, automobile, médical, optique…). Il reste à ce jour indispensable sur ce marché car aucun autre polymère ne présente d’aussi bonnes propriétés mécaniques à prix égal. C’est dans ce contexte que ces travaux de thèse ont permis de développer une solution permettant de protéger le PC de toute agression extérieure par le dépôt d’un revêtement protecteur. L’étude s’est orientée vers le dépôt d’un film hydride organique / inorganique à base de silice, préparé par voie sol-gel, ce procédé permettant une élaboration à une température compatible avec la température de transition vitreuse du PC (Tg) (148°C). Les solutions retenues pour obtenir un revêtement performant sont basées sur la synthèse de revêtements hybrides à base d’oxydes de silicium et de zirconium. Une attention particulière a été portée sur l’augmentation de l’adhérence du film au substrat d’une part, et l’optimisation du procédé (synthèse et traitement de densification), d’autre part. Les résultats sont présentés d’un point de vue physico-chimique (IR, XRR, RMN) et mécanique (nanoindentation, adhésion et test à la rayure).The polycarbonate is a widespread polymer material, highly appreciated for its low density, its transparency and its good mechanical properties. This material is used for divert applications (automotive, medical, optical...) and is very competitive in terms of quality and prices. However, it displays some weaknesses, essentially due to its poor abrasion and scratch resistance and its possible degradation under UV or hydrolysis. In this context, the PhD aim is to design and develop a new hybrid organic / inorganic protective coating with silica and zirconia based precursors prepared by the sol gel process, which allow a curing compatible with the polycarbonate's Tg (148°C). Here, it is discussed on the solutions retained to obtain a scratch resistant, hydrophobic and transparent coating. It is showed that, scratch resistant protective coatings can be deposited on pristine PC thanks to a performing hybrid organic / inorganic coating by modulating its bulk properties. Moreover, results demonstrate the key role played by a phenylsilane precursor in enhancing the adherence. Nanoindentation, scratch-test, NMR and FTIR analysis will be discussed

Conception, synthèse par chimie douce et caractérisation de revêtements sol-gel hybrides multifonctionnels sur polycarbonate

Le polycarbonate (PC) est un matériau polymère très répandu, fort apprécié pour sa faible densité, sa transparence, ses bonnes propriétés mécaniques et surtout pour son faible coût. Même s’il présente quelques limites essentiellement liées à sa faible résistance à l’abrasion, à la rayure et à sa dégradation dans le temps (sous UV ou hydrolyse), le PC trouve sa place dans un large spectre d’applications (bâtiment, automobile, médical, optique…). Il reste à ce jour indispensable sur ce marché car aucun autre polymère ne présente d’aussi bonnes propriétés mécaniques à prix égal. C’est dans ce contexte que ces travaux de thèse ont permis de développer une solution permettant de protéger le PC de toute agression extérieure par le dépôt d’un revêtement protecteur. L’étude s’est orientée vers le dépôt d’un film hydride organique / inorganique à base de silice, préparé par voie sol-gel, ce procédé permettant une élaboration à une température compatible avec la température de transition vitreuse du PC (Tg) (148°C). Les solutions retenues pour obtenir un revêtement performant sont basées sur la synthèse de revêtements hybrides à base d’oxydes de silicium et de zirconium. Une attention particulière a été portée sur l’augmentation de l’adhérence du film au substrat d’une part, et l’optimisation du procédé (synthèse et traitement de densification), d’autre part. Les résultats sont présentés d’un point de vue physico-chimique (IR, XRR, RMN) et mécanique (nanoindentation, adhésion et test à la rayure).The polycarbonate is a widespread polymer material, highly appreciated for its low density, its transparency and its good mechanical properties. This material is used for divert applications (automotive, medical, optical...) and is very competitive in terms of quality and prices. However, it displays some weaknesses, essentially due to its poor abrasion and scratch resistance and its possible degradation under UV or hydrolysis. In this context, the PhD aim is to design and develop a new hybrid organic / inorganic protective coating with silica and zirconia based precursors prepared by the sol gel process, which allow a curing compatible with the polycarbonate's Tg (148°C). Here, it is discussed on the solutions retained to obtain a scratch resistant, hydrophobic and transparent coating. It is showed that, scratch resistant protective coatings can be deposited on pristine PC thanks to a performing hybrid organic / inorganic coating by modulating its bulk properties. Moreover, results demonstrate the key role played by a phenylsilane precursor in enhancing the adherence. Nanoindentation, scratch-test, NMR and FTIR analysis will be discussed

Mechanical properties of sol–gel coatings on polycarbonate: a review

International audienc

Analyse de trajectoires de transition agroécologique des systèmes agricoles

National audienc

Strategies for co-existence of GM and non-GM soy from import fo feed processing

Regulations 1829/2003/CE and 1830/2003/CE have allowed the placing on the European market of GM products in food and feed chains, and have defined their rules of traceability and labeling. For some supply chains, like for soy and its derived products that are used in the production of feed, manufacturers have to face both non-GM and GM production, although there are no labeling requirements for animal products derived from animals fed with GMOs. This study presents the strategies of stakeholders involved in the feed production chain to maintain concurrent production of compound feed with GM and non-GM soy products, by dealing with the coexistence between those two crops. The stakeholders include importers, traders, soy processors, feed processors and retailers. The study shows that many tools are in place to ensure andmaintain the current coexistence. However, a profound harmonization of procedures and methods at a European level should be encouraged

A rapidly developing market of white LEDs requires new solutions for replacing the rare earth-based phosphors, as 95 % of these materials come from China, creating a monopoly disadvantageous for other countries and a risk for the wide deployment of white LED technology in the coming years. Ona alternative to these rare-earth based phosphors is ZnO. It is a wide bandgap semiconductor, cheap, non-harmful and abundant in nature and it can emit visible light, from yellow to red, depending on the nature of the crystalline and surface defects [1]. IRCELyon recently developed a quick and convenient chemical sol-gel approach to obtain a unique mesospheric self-assembly of ZnO nanoparticles in a hybrid system with intense and stable photoluminescent quantum yield (PL QY) of 40-75 % [1]. This high PL QY is possible thanks to a so-called down-shifting (DS) process, a variant of the down-conversion. This synthesis route uses the mixture of commercially available polyacrylic acid (PAA)-based polymers and can provide large scale amounts of ZnO NPs in clear water suspensions which can be dried and dispersed again in water without compromising the performance (e.g. transparency and PL QY) of the final DS layer. We present the effects of the ZnO NPs surface functionalization and the influence of various doping atoms in ZnO NPs on their photoluminescence spectrum and the PL QY, in order to be able to favor and boost a desired color of emission.References:1.Y. Zhu, A. Apostoluk, P. Gautier, A. Valette, T. Cornier, J. Bluet, K. Masenelli-Varlot, S. Danièle, B. Masenelli, Scientific Reports 6, pp. 23557 (1-11), 2016.

International audienc

Pressure-Induced Phase Transitions in TiO 2 Rutile Nanorods

SSCI-VIDE+CDFA+TCO:SDAInternational audienc