728 research outputs found
Reinventing the future of plastic
At a time when plastic is under the spotlight, two seemingly opposed solutions are often mentioned. Some people dream of a deplastified world, where plastic is replaced by alternative materials. Many of these alternatives are yet to be invented, but one of the solutions proposed is to boost the amount of bio-sourced plastic produced (bio-PE, bio-PET etc.). Although more of this material has been produced in recent years, it remains controversial as it uses farm land to grow non-food goods but..
Value and limitations of plastics
Plastic has become indispensable to our modern lifestyles. It helps to save energy, reduce CO2 emissions and conserve resources. It has become vital to the food industry as it helps to cut food waste by increasing product shelf-lives. In the automotive sector, where plastics account for some 20% of materials in a car, plastics are used to cut vehicle weights and thereby improve fuel consumption. Similarly, plastics account for 60% of materials used in textile manufacture, a total of over 70 m..
Plastics: from apogee to controversy
A century after plastic was invented, its properties â being lightweight, strong and cheap â have swept it into every corner of our throwaway society, from food to health, automotive to fashion. The amount of plastic produced worldwide has grown exponentially, from 1.5 million metric tons in 1950 to 335 million metric tons in 2016. It has also created wealth, with plastics accounting for over 1.5 million jobs in Europe and contributing âŹ27.5 billion to European public finances. Beach covered ..
GEoTweet: exploration des tweets géolocalisés à GenÚve
Que dĂ©couvre-t-on sur la sociĂ©tĂ© genevoise quand on modĂ©lise des frontiĂšres au sein dâun rĂ©seau social tel que Twitter ? Comment la visualisation des tweets gĂ©olocalisĂ©s nous permet-elle de saisir la variĂ©tĂ© des communautĂ©s linguistiques Ă GenĂšve ? Le projet GEoTweet propose des rĂ©ponses Ă ces questions de recherche, Ă travers la mise en place dâune infrastructure permettant de rĂ©colter les tweets, de les explorer et de les interroger. Il implĂ©mente des modalitĂ©s techniques dâaccĂšs, de stockage et dâexploitation des tweets gĂ©olocalisĂ©s Ă partir du streaming public mis Ă disposition par Twitter via son API, explore les tweets gĂ©olocalisĂ©s dans un contexte spatio-temporel dĂ©fini (GenĂšve et ses alentours), et teste des formes de visualisation des donnĂ©es gĂ©olocalisĂ©es en considĂ©rant leur potentiel analytique. Le premier axe de recherche concerne les frontiĂšres linguistiques virtuelles. Les tweets gĂ©olocalisĂ©s donnent des informations sur la population rĂ©sidente et, en mĂȘme temps, sur les flux volatiles dâautres catĂ©gories dâutilisateurs de lâespace urbain genevois. Le deuxiĂšme axe de recherche concerne les convergences et les divergences entre les frontiĂšres gĂ©opolitiques et les frontiĂšres virtuelles, et met en Ă©vidence leur permĂ©abilitĂ© et leur influence rĂ©ciproque. Le troisiĂšme axe de recherche concerne la qualitĂ© de donnĂ©es rĂ©coltĂ©es et leur fiabilitĂ©, Ă travers lâanalyse de lâintĂ©gration entre diffĂ©rents media sociaux gĂ©olocalisĂ©s, les procĂ©dures dâĂ©limination des robots et lâimportance des sauvegardes pour le stockage. Le projet GEoTweet ouvre des perspectives additionnelles dâexploration et dâanalyse des donnĂ©es, et est le point de dĂ©part dâune sĂ©rie dâĂ©vĂ©nements grand public visant Ă la vulgarisation du big data
Les ressources audiovisuelles Ă lâUniversitĂ© de GenĂšve, site Uni Mail: Ă©tat des lieux, usages et avenir
La dĂ©matĂ©rialisation des supports, notamment dans le domaine de lâaudiovisuel, a engendrĂ© de profonds changements dans les pratiques des consommateurs. Que ce soit par le biais du streaming, le tĂ©lĂ©chargement ou encore les plateformes de vidĂ©o Ă la demande, lâoffre audiovisuelle en ligne est en train de sâimposer sur le marchĂ© face au DVD dont la disparition prochaine parait inĂ©vitable. Les bibliothĂšques sont alors directement impactĂ©es par ces bouleversements et se doivent de repenser leurs offres et services afin quâils soient en adĂ©quation avec les pratiques et besoins de leurs publics. Câest dans cet environnement en profonde mutation que sâinscrit le prĂ©sent travail. Il a pour objet lâĂ©tude du fonds DVD de la BibliothĂšque de lâUniversitĂ© de GenĂšve, site Uni Mail, composĂ© de plus de 11'000 films. Ce travail propose une rĂ©flexion de fond portant sur la collection qui prend en compte les Ă©volutions technologiques prĂ©sentes et futures, ainsi que les pratiques des usagers. Il offre une Ă©valuation de lâĂ©tat actuel du fonds et propose des scĂ©narios dâĂ©volution avec des recommandations portant notamment sur son dĂ©veloppement, ses modes de mise Ă disposition et sa valorisation. Pour rĂ©aliser notre Ă©tude, nous avons tout dâabord effectuĂ© un Ă©tat des lieux dĂ©taillĂ© de lâEspace audiovisuel de la bibliothĂšque, puis nous avons procĂ©dĂ© Ă une revue de littĂ©rature dans le but de mieux comprendre certains aspects de notre problĂ©matique. Nous avons dĂšs lors rĂ©alisĂ© une enquĂȘte par questionnaire auprĂšs du public afin de mieux connaĂźtre leurs usages du fonds et leurs besoins. ParallĂšlement, nous avons rĂ©alisĂ© trois entretiens auprĂšs de bibliothĂšques acadĂ©miques pour connaĂźtre leur positionnement face Ă la pertinence dâun fonds audiovisuel dans ce type dâinstitution. Ces diffĂ©rentes Ă©tapes nous ont permis de soumettre Ă la BibliothĂšque de lâUniversitĂ© de GenĂšve une sĂ©rie de recommandations relatives au dĂ©veloppement et Ă la mise en valeur de lâoffre. La redĂ©finition des critĂšres dâacquisition, le stockage de certains documents sur un serveur institutionnel sĂ©curisĂ© accessible en ligne et Ă distance ainsi quâune intĂ©gration des documentaires sur support DVD aux collections papier sont quelques-unes des suggestions quâaborde le prĂ©sent travail
Hedonic appreciation and verbal description of pleasant and unpleasant odors in untrained, trainee cooks, flavorists and perfumers
Olfaction is characterized by a salient hedonic dimension. Previous studies have shown that these affective responses to odors are modulated by physicochemical, physiological, and cognitive factors. The present study examined expertise influenced processing of pleasant and unpleasant odors on both perceptual and verbal levels. For this, performance on two olfactory tasks was compared between novices, trainee cooks, and experts (perfumers and flavorists): Members of all groups rated the intensity and pleasantness of pleasant and unpleasant odors (perceptual tasks). They were also asked to describe each of the 20 odorants as precisely as possible (verbal description task). On a perceptual level, results revealed that there were no group-related differences in hedonic ratings for unpleasant and pleasant odors. On a verbal level, descriptions of smells were richer (e.g., chemical, olfactory qualities, and olfactory sources terms) and did not refer to pleasantness in experts compared to untrained subjects who used terms referring to odor sources (e.g., candy) accompanied by terms referring to odor hedonics. In conclusion, the present study suggests that as novices, experts are able to perceptually discriminate odors on the basis of their pleasantness. However, on a semantic level, they conceptualize odors differently, being inclined to avoid any reference to odor hedonics
Sémiotique et visualisation de l'identité numérique: une étude comparée de Facebook et Myspace
Digital identity is divided into 3 sign sets: (1) declarative identity, (2) acting identity and (3) calculated identity. This typology allows leading a quantitative analysis of cultural influence of identity representation in social web, through the comparative study of two social networks: Facebook and MySpace. Unlike early web, social web makes possible identification of a user without having to declare describing elements. The comparative analysis presented here continues this analysis by specifying the procedures of this new paradigm of identity and highlighting two different ideologies of identity, on the one hand, a normative one to stimulate socialization, on the other hand, an egocentric one for the sake of self-expression. âCalculated identityâ encourages users to make comparisons between them and feed their representation, but increasing disproportionately the number of friends is not sufficient to play the social game as it is structured by Facebook: visualization shows that the social network is maintained by sharing. Sharing photos, participating in shared groups is a part of regular social interaction announcing the emergence of a new intersubjective language.Un modĂšle sĂ©miotique de l'identitĂ© numĂ©rique construit prĂ©cĂ©demment distingue 3 ensembles de signes : l'identitĂ© dĂ©clarative, agissante et calculĂ©e. Ce modĂšle est utilisĂ© pour dĂ©velopper une analyse quantitative appliquĂ©e de l'emprise culturelle du web 2.0 sur la reprĂ©sentation de l'identitĂ© Ă travers l'Ă©tude comparative de deux logiciels de rĂ©seaux sociaux, Facebook et Myspace. Contrairement au premier web, le web social rend possible l'identification personnelle d'un utilisateur sans qu'il ait Ă dĂ©clarer des Ă©lĂ©ments qui le dĂ©crivent ; l'analyse comparĂ©e ici prĂ©sentĂ©e poursuit cette analyse en prĂ©cisant les procĂ©dĂ©s de ce nouveau paradigme identitaire et mettant en Ă©vidence des idĂ©ologies identitaires diffĂ©rentes, l'une normative par souci de socialisation, l'autre Ă©gocentrĂ©e par souci d'expression de soi. L'identitĂ© calculĂ©e incite les utilisateurs Ă Ă©tablir des comparaisons entre eux et Ă nourrir leur reprĂ©sentation, mais il ne s'agit pas pour autant de jouer Ă accroĂźtre dĂ©mesurĂ©ment un critĂšre comme le nombre d'amis pour jouer le jeu social : les graphes nĆud-lien montrent que le rĂ©seau s'entretient par le partage. Partager des photographies, participer Ă des groupes communs fait partie des Ă©changes sociaux rĂ©guliers qui annoncent l'Ă©mergence d'un nouveau langage intersubjectif
High-Yielding Diastereoselective syn -Dihydroxylation of Protected HBO: An Access to D-(+)-Ribono-1,4-lactone and 5- O -Protected Analogues
International audienceA diastereoselective chemoenzymatic synthetic pathway to Dâ(+)âribonoâ1,4âlactone, a versatile chiral sugar derivative widely used for the synthesis of various natural products, has been designed from celluloseâbased levoglucosenone (LGO). This route involves a sustainable BaeyerâVilliger oxidation of LGO to produce enantiopure (S)âÎłâhydroxymethylâα,ÎČâbutenolide (HBO) that is further functionalized with various protecting groups to provide 5âOâprotected Îłâhydroxymethylâα,ÎČâbutenolides. The latter then undergo a diastereoselective and highâyielding synâdihydroxylation of the α,ÎČâunsaturated lactone moiety followed by a deprotection step to give Dâ(+)âribonoâ1,4âlactone. Through this 4âstep synthetic route from LGO, Dâ(+)âribonoâ1,4âlactone is obtained with d.r. varying from 82:18 to 97:3 and in overall yields between 32 and 41â% depending on the protecting group used. Moreover, valuable synthetic intermediates 5âOâtertâbutyldimethylsilylâ, 5âOâtertâbutyldiphenylsilylâ as well as 5âOâbenzylâribonoâ1,4âlactones are obtained in 3 steps from LGO in 58, 61 and 40â%, respectively
La loi SRU incite-t-elle les maires Ă construire du logement social ?Les enseignements dâune analyse principal-agent
Cet article analyse les propriĂ©tĂ©s incitatives de la loi SRU, promulguĂ©e en France en dĂ©cembre 2000, dont lâune des finalitĂ©s est dâaccroĂźtre lâoffre de logements sociaux dans les communes qui en sont relativement dĂ©pourvues. Il apporte notamment des Ă©clairages sur les raisons pour lesquelles les communes se sont trĂšs inĂ©galement conformĂ©es aux objectifs de la loi. GrĂące Ă un modĂšle principal-agent, nous montrons que lâeffort rĂ©alisĂ© par les Ă©lus locaux dĂ©pend des arbitrages Ă©conomiques et politiques quâils opĂšrent. Le modĂšle thĂ©orique a Ă©galement une portĂ©e normative puisquâil permet de formuler plusieurs amĂ©liorations susceptibles dâaccroĂźtre lâeffet incitatif du dispositif.In 2000, an innovative regulatory mechanism called âSRU lawâ (âsolidarity and urban renewalâ) compels municipalities to offer at least 20% of social housing. Municipalities that do not comply with this quota are sanctioned by financial penalties. This paper studies the incentive properties of this rule using a principal-agent framework. Results indicate that the willingness of mayors to comply with the new rule depends on local economic and political trade-offs. The model has also a normative outcome since it proposes several improvements which may increase the incentive effect of this law
La loi SRU incite-t-elle les maires Ă construire du logement social ?Les enseignements dâune analyse principal-agent
Cet article analyse les propriĂ©tĂ©s incitatives de la loi SRU, promulguĂ©e en France en dĂ©cembre 2000, dont lâune des finalitĂ©s est dâaccroĂźtre lâoffre de logements sociaux dans les communes qui en sont relativement dĂ©pourvues. Il apporte notamment des Ă©clairages sur les raisons pour lesquelles les communes se sont trĂšs inĂ©galement conformĂ©es aux objectifs de la loi. GrĂące Ă un modĂšle principal-agent, nous montrons que lâeffort rĂ©alisĂ© par les Ă©lus locaux dĂ©pend des arbitrages Ă©conomiques et politiques quâils opĂšrent. Le modĂšle thĂ©orique a Ă©galement une portĂ©e normative puisquâil permet de formuler plusieurs amĂ©liorations susceptibles dâaccroĂźtre lâeffet incitatif du dispositif.In 2000, an innovative regulatory mechanism called âSRU lawâ (âsolidarity and urban renewalâ) compels municipalities to offer at least 20% of social housing. Municipalities that do not comply with this quota are sanctioned by financial penalties. This paper studies the incentive properties of this rule using a principal-agent framework. Results indicate that the willingness of mayors to comply with the new rule depends on local economic and political trade-offs. The model has also a normative outcome since it proposes several improvements which may increase the incentive effect of this law
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