775 research outputs found
Ethylenedithio--Tetrathiafulvalene--Helicenes: Electroactive Helical Precursors with Switchable Chiroptical Properties
International audienceElectroactive fused ethylenedithio-tetrathiafulvalene-[4]helicene and -[6]helicenes have been synthesized through a strategy involving the preparation of 2,3-dibromo-helicene derivatives as intermediates. The dihedral angles between the terminal helicenes, as determined by single crystal X-ray analyses, amount to 22.7° and 50.7° for the [4]helicene and [6]helicene, respectively. The solid state architectures show interplay between S···S and ··· intermolecular interactions. The chiroptical properties of the enantiopure EDT-TTF-[6]helicene derivatives have been investigated and supported by TD DFT calculations. Remarkable redox switching of the circular dichroism signal between the neutral and radical cation species has been achieved
Estimating daily yield and content of major fatty acids from single milking
Reducing the frequency of milk recording and the number of recorded samples per test-day could be a solution in order to reduce costs of official milk recording. However, fewer samples lead to a decrease in the accuracy of predicted daily yields. Unfortunately, the current published equations use the milking interval that is often not available and/or reliable in practice. The first objective of this study was to propose models using easily available traits. Therefore the milking interval was replaced by a combination of data easily recorded by milk recording. The second objective of this study was to enlarge the previous investigations to milk fatty acids (FA) in order to propose a practical method for estimating accurate daily milk, fat and major FA yields from single milking. The fit goodness of proposed models was evaluated based on the correlation values between the estimated and observed daily yields in addition to the calculation of the mean square error. Obtained results are promising. Correlation values were comprised between 96.4% and 97.6% when daily yield were estimated from morning milking, and from 96.9% to 98.3% when daily yield were estimated from evening milking. The combination of records related to lactation stage, month of test, milk yield, and fat could replace the milking interval effect. Because of their simplicity, proposed models would be easy to implement
Helically chiral NHC‐gold(I) complexes: synthesis, chiroptical properties and electronic features of the [5]helicene‐imidazolylidene ligand
The golden twist: Monodentate [5]helicene-imidazolylidene gold(I) complexes were prepared in good yields and structurally characterized. Benefiting from the presence of the configurationally stable [5]helicenic unit, they exhibit appealing chiroptical features, such as strong circular dichroism, moderate circularly polarized phosphorescence and dual emission with phosphorescence lifetimes up to the millisecond range
Synthesis and chiral recognition ability of helical polyacetylenes bearing helicene pendants
International audienceNovel polyacetylenes bearing an optically active or racemic [6]helicene unit as the pendant groups directly bonded to the main-chain (poly-1s) were prepared by the polymerization of the corresponding acetylenes (1-rac, 1-P, and 1-M) with a rhodium catalyst. The optically active polyacetylenes (poly-1-P and poly-1-M) formed a preferred-handed helical conformation biased by the optically active helicene pendants, resulting in the induced circular dichroism (ICD) in their π-conjugated polymer backbone regions. The optically active helical polymers, when employed as an enantioselective adsorbent, showed a high chiral recognition ability towards racemates, such as the monomeric [6]helicene and 1,1’-binaphthyl analogues, and enantioselectively adsorbed one of the enantiomers
Ruthenium-Grafted Vinylhelicenes: Chiroptical Properties and Redox Switching
International audienceThe properties of mono- and bis-Ru-vinyl[6]helicene complexes (2 a and 2 b, respectively), recently synthesized by using molecular engineering of helicenes based on the grafting of lateral organometallic substituents on the π-helical backbone through a vinyl bridge, are presented. These helicene derivatives are thoroughly characterized, with special attention given to their chiroptical properties and redox switching activity. The UV/Vis and electronic circular dichroism (ECD) spectra of P and M enantiopure species, both in the neutral and oxidized states ([2 a](·+), [2 b](·+), and [2 b](2+)), are analyzed with the aid of quantum-chemical calculations. The extended π-conjugation facilitated by the vinyl moiety, clearly visible in the electronic structures of 2 a,b, introduces new active bands in the ECD spectra that consequently lead to a significant increase in optical rotation of Ru-vinylhelicenes compared with the organic precursors. The vibrational circular dichroism (VCD) spectra were measured and calculated for both the organic and organometallic species and constitute the first examples of VCD for metal-based helicene derivatives. Finally, the redox-triggered chiroptical switching activity of 2 a,b is examined in detail by using ECD spectroscopy. The modifications of the ECD spectra in the UV/Vis and NIR region are well reproduced and rationalized by calculations
: Rapport final du projet ANR 2006-2008 (annexes scientifiques)
As a 24 months platform project, Lutin Game Lab was designed for making academic researchers and game companies cooperate in order to reach a new stage in the process of game quality assessment, before and after they are available on the market. The project was organized along 6 WP, all of them having fulfilled their specific goals, although we had to endure some delays due to the time required for settling the technical platform and due to the lack of time available for the companies to collaborate during the year 2008.The project results can be summed up in 4 different aspects:* A platform is now open to companies as well as to academic labs, equipped with all the devices and the softwares needed for conducting evaluation of gamers behaviour, including all game platforms, excepted for on-line games. Two eye-tracking devices and sensorial analysis tools are part of the equipment of the platform. This technical platform is operated by the UMS CNRS Lutin at the Cité des Sciences in Paris.* The methods created for analyzing the existing games and the ones in development phase were scientifically validated and adapted to the requirements of companies (time needed, display of the results, prerequisites and modes of cooperation with developers). These methods have not yet been tested in the developing phase of real games except for one of them (QRC), due to the workload of developers during this period. * The methods are the following:o Artificial expert for the prediction of gamers judgments based on a description framework of game properties. A subjective evaluation database has been designed using the data collected during the tests of 240 gamers (experts and naives) expressing judgments in a 11 items questionnaire, using the data from an objective description of game properties and the data obtained through an "objectivated subjective" description of games qualities retrieved from experts who designed and filled up a framework of 56 items per game genre (126 iterations). This expert allows companies to test their games while they are still in the design phase through the description framework in order to predict the judgments from the gamers and to optimize their various choices in game design using the 15 fuzzy models selected for each game genre.o Usability testing method adapted specifically to videogames (Quick Reality Check, QRC), based on a test protocol involving 10 gamers, on logs tracking the gamer behaviour (implemented by the developers in their prototype), on synthetic visualization tools displaying the results, and on remediation method in cooperation with game designers (game doctor). This method focuses on ergonomics features and acceptability issues.o An eyetracking method dedicated to gamers behaviour analysis. It helps to explore in-depth the areas or phases of concern discovered with the previous method. This allows the game designers to reshape some features in the interfaces and to compare their results with the patterns of each game genre that the research was able to modelize.o A method for tracking emotional states during the game, through sensors placed on the gamers bodies, in order to explore and better understand the reasons of the problems pointed out by the other methods. This is a much more innovative methodology and field of research and this explains the need for focusing on specific features in order to validate the whole framework with the existing scientific state of the art. This is a very promising field and a very attractive one for the game designers, one that would require much more research efforts.o An artificial expert providing diagnosis through the gathering of every piece of data collected during the various tests, with added results from on line questionnaires. The expert software provides an integrative view of the results for a specific game and can refer it to the various models available in the literature.* In the gameplay evaluation field, the project evolves from a review of literature to the design of a wiki open to the community of game designers, which aim is to create de knowledge database about gameplay qualities for each game genre. The wiki includes a list of rules shared by the community and examples of games displaying the uses of these rules, extracted from a corpus of the most famous games. The database can be enriched with new cases, rules can be adapted, through the revision process of the wiki which includes collective validation. Developers can access the wiki as a resource for validation of their choices.In brief, the platform offers a set of devices, a set of methods, available for the game industry, operated by Lutin experts, and a website including the wiki. Lutin Game lab platform represents an European reference center in the field of game evaluation. Lutin plans to design a quality label for games that could be used before the games are placed on the market. LUtin Game Lab requires a new research project devoted to the extension of the methods to on-line games (Lutin Game Lab on line). The next year will be devoted to dissemination and validation on real game being developed.Le projet annonçait ainsi ses objectifs en 2006 : " Lutin Game Lab, projet de plate-forme de 24 mois, se propose de fédérer les forces de recherche académiques et de développement des entreprises pour faire faire un pas significatif aux méthodologies d'évaluation de la qualité d'un jeu vidéo fini ou en cours de développement. " Le travail a comporté 6 sous -projets qui ont tous été menés à bien conformément au programme prévu avec des décalages non négligeables dus notamment au temps nécessaire au montage technique de la plate-forme et à la difficulté des entreprises à dégager du temps pour leur collaboration au moment voulu alors qu'elles sont sous haute pression concurrentielle. Le bilan du projet peut se résumer en 4 points : * il existe désormais en France une plate-forme ouverte aux entreprises et aux laboratoires, équipée de tous les matériels et logiciels nécessaires pour faire l'évaluation des comportements des joueurs de jeux vidéo, toutes plates-formes de jeu confondus, à l'exception des jeux multi joueurs en ligne. Cette plate-forme technique, comportant notamment des dispositifs d'oculométrie opérationnels de divers types, et des dispositifs d'analyse sensorielle, est opérationnelle en permanence dans le cadre des missions de l'UMS CNRS Lutin 2803 à la Cité des Sciences. * Les méthodes élaborées pour l'analyse des jeux existants et des jeux en cours de développement ont été validées scientifiquement et opérationnellement selon les critères des entreprises de jeux vidéo (délais, présentation des résultats, prérequis et formes de coopération). Ces méthodes devront cependant être validées en situation de jeux en cours de développement car les délais de coopération avec les entreprises n'ont permis de mettre en œuvre cette étape que pour une seule de ces méthodes (dite QRC)* Les méthodes comportent 5 volets : o un expert artificiel prédictif qui permet de prédire l'appréciation subjective des joueurs à partir d'une description formalisée des propriétés d'un jeu. Une base de données d'évaluation subjective a été constituée à partir de tests réalisés par 240 joueurs de tous niveaux et de leur appréciation subjective (11 items), à partir de description des propriétés objectives du jeu (106 items) et à partir d'une description subjective objectivée des qualités d'un jeu par genre (56 items par genre de jeu) et de 126 itérations de cette grille réalisée à partir d'une extraction d'expertise auprès de game designers et élèves game designers. Il est proposé aux entreprises de jeux vidéo de tester leur jeu dans une phase amont du développement pour prédire les scores de leurs jeux et ensuite optimiser les choix effectués, en exploitant les 15 modèles en logique floue sélectionnés pour chaque genre de jeu. o Une méthode en usability (Quick Reality Check) qui comporte un protocole de tests auprès de 10 joueurs minimum, des outils de suivi des déplacements par implantation de logs dans le jeu en cours de développement, de modes de visualisation synthétique des résultats et une méthode de correction associant les développeurs (Game Doctor). Cette méthode traite avant tout les questions d'ergonomie et d'acceptabilité. o Une méthode de suivi du regard des joueurs permettant d'affiner les résultats de la méthode précédente, sur des zones ou des phases problématiques pour repositionner le game design et l'ergonomie en fonction des patterns, ou signatures, identifiés par la recherche pour chaque type de jeux. o Une méthode de suivi de l'engagement émotionnel durant le jeu à partir de capteurs d'analyse sensorielle placés sur les joueurs, permettant là aussi d'affiner la recherche éventuelle de problèmes pour des phases plus précises selon les stratégies du game designer. Cette méthode est la plus innovante en termes de recherche et nos résultats restent donc limités à certains points précis qui sont cependant très prometteurs et nécessiteraient des travaux supplémentaires.o Un expert artificiel diagnostic permettant de traiter et de synthétiser toutes les données recueillies lors des tests des autres méthodes, de les compléter par des questionnaires en ligne si nécessaire et de les rapporter à des modèles issus de la littérature pour proposer un diagnostic intégré sur les qualités d'un jeu donné. * Dans le domaine du gameplay, le projet a évolué à partir d'un recensement exhaustif de la littérature sur la mise en place d'un wiki permettant à toute la communauté des développeurs de constituer une base de connaissances partagées sur les qualités du gameplay selon les genres. Ce wiki comporte un énoncé de règles reconnues par la communauté mais aussi leur exemplification à partir d'un corpus de jeux parmi les plus connus dans tous les genres. La base peut être enrichie par d'autres études de cas, les règles peuvent être affinées, et les développeurs peuvent la consulter en tant que de besoin pour valider les choix qu'ils effectuent. La mise en place de la plate-forme comporte ainsi une partie d'équipements localisés à la cité des sciences, une expertise en méthodes, directement opérationnelles et proposées déjà aux entreprises par les différents partenaires membres de Lutin, et un site collaboratif qui rassemble la communauté autour de son expertise propre. Lutin Game Lab peut ainsi prétendre devenir un centre de références européen en termes de méthodes qualité pour les jeux vidéo et nous prévoyons de travailler à proposer un label pour qualifier les jeux vidéo avant leur mise sur le marché, ainsi qu'à une extension de ses compétences pour les jeux vidéo multi joueurs en ligne (Lutin Game Lab on line). Le projet a ainsi atteint son objectif général ainsi que ses objectifs particuliers, à l'exception du temps de validation encore nécessaire auprès des entreprises qui n'a pu être pris en compte durant le projet
More Filtering on SNP Calling Does Not Remove Evidence of Inter-Nucleus Recombination in Dikaryotic Arbuscular Mycorrhizal Fungi
Evidence for the existence of dikaryote-like strains, low nuclear sequence diversity and inter-nuclear recombination in arbuscular mycorrhizal fungi has been recently reported based on single nucleus sequencing data. Here, we aimed to support evidence of inter-nuclear recombination using an approach that filters SNP calls more conservatively, keeping only positions that are exclusively single copy and homozygous, and with at least five reads supporting a given SNP. This methodology recovers hundreds of putative inter-nucleus recombination events across publicly available sequence data from individual nuclei. Challenges related to the acquisition and analysis of sequence data from individual nuclei are highlighted and discussed, and ways to address these issues in future studies are presented
Lactobacillus paracasei Reduces Intestinal Inflammation in Adoptive Transfer Mouse Model of Experimental Colitis
Studies showed that specific probiotics provide therapeutic benefits in inflammatory bowel disease. In vitro evidence suggested that Lactobacillus paracasei also called ST11 (CNCM I-2116) is a potent strain with immune modulation properties. However, little is known about its capacity to alleviate inflammatory symptoms in vivo In this context, the main objective of this study was to investigate the role of ST11 on intestinal inflammation using the adoptive transfer mouse model of experimental colitis. Rag2−/− recipient mice were fed with ST11 (109 CFU/day)a month prior toinduce colitis by adoptive transfer of naive T cells. One month later, in clear contrast to nonfed mice, weight loss was significantly reduced by 50% in ST11-fed mice. Further analysis of colon specimens revealed a significant reduction neutrophil infiltration and mucosal expression of IL1β, IL-6, and IL12 proinflammatory cytokines, whereas no consistent differences in expression of antibacterial peptides or tight junction proteins were observed between PBS and ST11-fed mice. All together, our results demonstrate that oral administration of ST11 was safe and had a significant preventive effect on colitis. We conclude that probiotics such as Lactobacillus paracasei harbor worthwhile in vivo immunomodulatory properties to prevent intestinal inflammation by nutritional approaches
Recent Increase in Meningitis Caused by Neisseria meningitidis Serogroups A and W135, Yaoundé, Cameroon
From 1991 to 1998, Neisseria meningitidis serogroups A, B, and C represented 2%-10% of strains isolated from cases of bacterial meningitis in Yaoundé. During 1999 to 2000, the percentage of meningococci reached 17%, a proportion never reported since recordkeeping began in 1984. The increase of serogroup A meningococci and the emergence of W135 strains highlight the need for increased surveillance for better diagnosis and prevention
Rhenium complexes bearing phosphole-pyridine chelates: simple molecules with large chiroptical properties.
International audienceThe synthesis and chiroptical properties of chiral rhenium complexes bearing mono- or di-topic phosphole ligands are described. [on SciFinder(R)
- …