86 research outputs found
Hypergame Analysis in E-Commerce: A Preliminary Report
In usual game theory, it is normally assumed that "all the players see the same game", i.e., they are aware of each other's strategies and preferences. This assumption is very strong for real life where differences in perception affecting the decision making process seem to be the rule rather the exception. Attempts have been made to incorporate misperceptions of various types, but most of these attempts are based on quantities (as probabilities, risk factors, etc.) which are too subjective in general. One approach that seems to be very attractive is to consider that the players are trying to play "different games" in a hypergame. In this paper, we present a hypergame approach as an analysis tool in the context of multiagent environments. Precisely, we first sketch a brief formal introduction to hypergames. Then we explain how agents can interact through communication or through a mediator when they have different views and particularly misperceptions on others' games. After that, we show how agents can take advantage of misperceptions. Finally, we conclude and present some future work. Dans les jeux classiques, il est supposĂ© que "tous les joueurs voient le mĂȘme jeu'', i.e., que les joueurs sont au courant des stratĂ©gies et des prĂ©fĂ©rences des uns et des autres. Aux vu des applications rĂ©elles, cette supposition est trĂšs forte dans la mesure oĂč les diffĂ©rences de perception affectant la prise de dĂ©cision semblent plus relevĂ©es de la rĂšgle que de l'exception. Des tentatives ont Ă©tĂ© faites, par le passĂ©, pour incorporer les distorsions aux niveaux des perceptions, mais la plupart de ces tentatives ont Ă©tĂ© essentiellement basĂ©es sur le "quantitatif" (comme les probabilitĂ©s, les facteurs de risques, etc.) et par consĂ©quent, trop subjectives en gĂ©nĂ©ral. Une approche qui semble ĂȘtre attractive pour pallier Ă cela, consiste Ă voir les joueurs comme jouant "diffĂ©rents jeux'' dans une sorte d'hyper-jeu. Dans ce papier, nous prĂ©sentons une approche "hyper-jeu'' comme outil d'analyse entre agents dans le cadre d'un environnement multi-agent. Nous donnons un aperçu (trĂšs succinct) de la formalisation d'un tel hyper-jeux et nous expliquerons ensuite, comment les agents pourraient intervenir via un agent-mĂ©diateur quand ils ont des perceptions diffĂ©rentes. AprĂšs cela, nous expliquerons comment les agents pourraient tirer avantage des perceptions diffĂ©rentes.Game Theory, Hypergame, Mediation, ThĂ©orie des jeux, hyper-jeux, mĂ©diation
Ălectrocatalyse de la rĂ©duction du dioxyde de carbone par une monocouche de cuivre sur un substrat de palladium
La conversion du CO2 en produit Ă valeur ajoutĂ©e est une avenue technologique apportant des solutions concrĂštes Ă divers problĂšmes contemporains tels que la dĂ©pendance aux combustibles fossiles, lâĂ©mission du CO2 dans lâatmosphĂšre, puis lâentreposage de lâĂ©nergie de source renouvelable. La conversion du CO2 par voie Ă©lectrochimique est largement Ă©tudiĂ©e dans la perspective dâapplications Ă grande Ă©chelle en raison des conditions douces de tempĂ©rature et pression quâelle nĂ©cessite, en plus de la possibilitĂ© dâorienter la sĂ©lectivitĂ© de la rĂ©action vers les hydrocarbures et alcools simples. Ce projet de recherche sâintĂ©resse aux phĂ©nomĂšnes associĂ©s Ă la conversion du CO2 par rĂ©duction sur les surfaces mĂ©talliques servant dâĂ©lectrocatalyseurs. La combinaison de mĂ©taux Ă ces surfaces est une stratĂ©gie commune utilisĂ©e pour optimiser leur performance catalytique et orienter la sĂ©lectivitĂ© de la rĂ©action vers diffĂ©rents produits. Lâobjectif de ce projet est dâĂ©tudier les phĂ©nomĂšnes microscopiques de rĂ©duction du CO2 sur un matĂ©riau bimĂ©tallique modĂšle pour ĂȘtre en mesure de comprendre lâinfluence du caractĂšre bimĂ©tallique de cette surface sur les dynamiques molĂ©culaires qui sây produisent durant la catalyse. Ce type de comprĂ©hension, peu rĂ©pandue dans la littĂ©rature pour lâinstant, permettra de contribuer Ă faciliter la conception intelligente des catalyseurs de type bimĂ©tallique dans le futur. La surface modĂšle choisie dans le cadre de ce projet est une monocouche de Cu sur un substrat de Pd. Ce choix est motivĂ© par la diversitĂ© et la complĂ©mentaritĂ© des phĂ©nomĂšnes catalytiques promus par ces deux surfaces; le Cu Ă©tant efficace pour la rĂ©duction du CO2 vers les alcools et les hydrocarbures, puis le Pd Ă©tant efficace pour la rĂ©duction de H+ et la sorption de H neutre Ă sa surface et dans sa structure cristalline. La combinaison du Cu et du Pd est dâintĂ©rĂȘt pour vĂ©rifier comment les fonctions catalytiques de chacun des mĂ©taux sont influencĂ©es par leur combinaison et, de maniĂšre particuliĂšre, si ces fonctions peuvent interagir pour gĂ©nĂ©rer un comportement bifonctionnel ou synergique. Le comportement bifonctionnel visĂ© pour le catalyseur bimĂ©tallique modĂšle est la coopĂ©ration entre la fonction de rĂ©duction du CO2 du Cu et lâenvironnement chimique riche en H atomique promu par le Pd, qui favoriseraient ensemble lâhydrogĂ©nation accrue des produits de rĂ©duction du CO2. La premiĂšre partie du projet comprend la fabrication et lâĂ©tude sommaire de la surface catalytique modĂšle par une variĂ©tĂ© de techniques et dâexpĂ©riences Ă©lectrochimiques. Le phĂ©nomĂšne de dĂ©position sous-Nernstienne du Cu sur le Pd a premiĂšrement Ă©tĂ© explorĂ© Ă©lectrochimiquement pour le diffĂ©rencier de la dĂ©position en masse du Cu et pour dĂ©velopper une mĂ©thodologie de fabrication de la monocouche de Cu sur le substrat de Pd. Cette monocouche Ă©tant sensible Ă lâoxydation, deux mĂ©thodes de transfert du catalyseur bimĂ©tallique depuis la solution de prĂ©paration vers dâautres environnements ont Ă©tĂ© dĂ©veloppĂ©es. La premiĂšre mĂ©thode, qui comprend une dilution de la solution de fabrication de la monocouche et un contrĂŽle serrĂ© du potentiel appliquĂ© Ă lâĂ©lectrode, permet de transfĂ©rer le catalyseur vers les solutions aqueuses nĂ©cessaires Ă sa caractĂ©risation Ă©lectrochimique. La seconde mĂ©thode, qui correspond plutĂŽt Ă une technique de compensation de la charge de Cu oxydĂ©, a Ă©tĂ© dĂ©veloppĂ©e pour assurer le transfert du catalyseur vers lâenvironnement gazeux nĂ©cessaire Ă sa caractĂ©risation spectroscopique. Conduite par une sĂ©rie de balayages cathodiques, de voltampĂ©romĂ©tries cycliques et dâĂ©lectrolyses, la caractĂ©risation Ă©lectrochimique a dĂ©montrĂ© que la fonction de rĂ©duction et dâabsorption de H dans la structure du Pd est conservĂ©e dans le matĂ©riau bimĂ©tallique. La conservation de la fonction de rĂ©duction du CO2 au Cu de la monocouche de Cu, ainsi que le comportement gĂ©nĂ©ral du matĂ©riau bimĂ©tallique pour la rĂ©duction de cette molĂ©cule, nâont pas pu ĂȘtre Ă©tudiĂ©s efficacement en raison de la rĂ©action rapide de rĂ©duction de lâeau qui se produit dans les mĂȘmes conditions que la rĂ©action de rĂ©duction du CO2. Le dĂ©veloppement de mĂ©thodes analytiques suffisamment sensibles pour mesurer les produits de rĂ©action tels que la spectromĂ©trie de masse diffĂ©rentielle Ă©lectrochimique serait nĂ©cessaire pour une Ă©valuation plus efficace des capacitĂ©s de rĂ©duction du CO2 des catalyseurs dâintĂ©rĂȘt. La seconde partie du projet comprend lâĂ©tude du catalyseur bimĂ©tallique modĂšle et des mĂ©taux purs qui le composent par spectroscopie photoĂ©lectronique X Ă pression ambiante. Plusieurs catalyseurs bimĂ©talliques modĂšles composĂ©s de la monocouche partielle ou complĂšte de Cu sur le substrat de Pd, ainsi que des catalyseurs de Pd et de Cu, ont fait lâobjet dâune premiĂšre caractĂ©risation spectroscopique pour en confirmer la structure. Ces surfaces ont ensuite Ă©tĂ© Ă©tudiĂ©es spectroscopiquement alors quâelles Ă©taient exposĂ©es au CO2 et au CO pour dĂ©terminer comment les populations de ces molĂ©cules et de leurs diffĂ©rents intermĂ©diaires de conversion adsorbĂ©s y Ă©voluent. H2 et H2O, deux molĂ©cules de premiĂšre importance lors de lâĂ©lectrorĂ©duction du CO2, ont Ă©tĂ© ajoutĂ©es dans lâenvironnement chimique des catalyseurs durant cette Ă©tude pour entrainer la rĂ©action des molĂ©cules carbonĂ©es adsorbĂ©es Ă leur surface et mettre en Ă©vidence les diffĂ©rentes fonctions catalytiques qui y prennent place. Les donnĂ©es spectrales ont rĂ©vĂ©lĂ© que la surface de Cu favorise efficacement lâadsorption du CO2 sous deux configurations distinctes, alors que la surface de Pd favorise la conversion du CO2 vers les intermĂ©diaires adsorbĂ©s COOH(ads) et CO(ads). Une premiĂšre observation dâimportance est que ces deux fonctions catalytiques sont conservĂ©es aux surfaces bimĂ©talliques. Une seconde observation importante concerne lâadsorption du COOH(ads) aux surfaces bimĂ©talliques modĂšles, qui est significativement plus importante sur les surfaces bimĂ©talliques quâĂ la surface des mĂ©taux purs. Bien que cette capacitĂ© dâadsorption non intermĂ©diaire reprĂ©sente un constat important en soi, il est intĂ©ressant de noter que cette capacitĂ© dâadsorption suit une relation de type volcan avec lâaffinitĂ© des surfaces pour les molĂ©cules carbonĂ©es de diffĂ©rents degrĂ©s dâoxydation. Une derniĂšre observation importante est celle de lâinteraction directe entre les adsorbats situĂ©s sur le Cu et le Pd Ă la surface bimĂ©tallique. Cette interaction, qui mĂšne Ă la formation du CO2, a Ă©tĂ© observĂ©e entre le CO adsorbĂ© prĂ©fĂ©rentiellement sur les atomes de Pd et une molĂ©cule oxydante, soit H2O ou OH-, adsorbĂ©e prĂ©fĂ©rentiellement sur les atomes de Cu. Les observations rĂ©alisĂ©es Ă lâaide des expĂ©riences spectroscopiques rĂ©pondent Ă lâobjectif de ce projet de recherche en caractĂ©risant lâinfluence de la bimĂ©tallicitĂ© sur les phĂ©nomĂšnes microscopiques de conversion du CO2 par lâentremise de trois cas de figure; la conservation par le matĂ©riau bifonctionnel des fonctions catalytiques individuelles des mĂ©taux purs, lâapparition dâune capacitĂ© catalytique non intermĂ©diaire suivant une relation de type volcan, puis lâinteraction directe entre les molĂ©cules adsorbĂ©es sur les deux mĂ©taux
La production de thiols biogéniques par les microorganismes aquatiques
Les thiols Ă faible masse molĂ©culaire (FMM) peuvent affecter la biodisponibilitĂ© du mercure et mener Ă une plus grande production de mĂ©thylmercure par les microorganismes mĂ©thylants. Les rĂ©sultats dâune Ă©tude rĂ©alisĂ©e au sein de la matrice extracellulaire du pĂ©riphyton de la zone littorale dâun lac des Laurentides ont dĂ©montrĂ© que les concentrations en thiols Ă FMM retrouvĂ©es dans cette matrice sont jusquâĂ 1000 fois supĂ©rieures Ă celles de la colonne dâeau avoisinante. Ces thiols sont significativement corrĂ©lĂ©s Ă la chlorophylle a du pĂ©riphyton, suggĂ©rant une production par les algues. Le mercure de la matrice extracellulaire, plus spĂ©cifiquement dans la fraction colloĂŻdale mobile, est aussi corrĂ©lĂ© aux thiols dâorigine algale. Ces rĂ©sultats suggĂšrent quâune accumulation de thiols sâopĂšre dans lâespace extracellulaire du pĂ©riphyton et quâils peuvent favoriser le transfert du mercure vers les microorganismes produisant le mĂ©thylmercure. Les rĂ©sultats dâune seconde Ă©tude menĂ©e sur les mĂ©thodes de prĂ©servation dâĂ©chantillons dâeau pour la conservation des thiols Ă FMM ont dĂ©montrĂ© que la tempĂ©rature optimale dâentreposage Ă©tait de -80 °C et que la lyophilisation menait Ă une sous-estimation des concentrations mesurĂ©es. Les taux de dĂ©gradation Ă©taient plus rapides lors de la conservation Ă -20 °C et variables selon la chimie de lâeau utilisĂ©e et les espĂšces de thiols observĂ©es. Suivant ces rĂ©sultats, nous proposons un cadre de recherche pour de futures Ă©tudes sur la spĂ©ciation du mercure dans le pĂ©riphyton et nous suggĂ©rons des prĂ©cautions lors de la manipulation et de la conservation des thiols Ă FMM dâĂ©chantillons naturels.Low molecular weight (LMW) thiols can affect the bioavailability of mercury and by enhancing methylmercury production by methylating microorganisms. Results of a study conducted within periphyton extracellular matrix in the littoral zone of a lake of the Laurentians have shown that LMW thiol concentrations found in this matrix are up to 1000 fold higher than those in the water column of surrounding waters. Relationships between these thiols and periphyton chlorophyll a were significant, suggesting production by algae. Mercury in the extracellular matrix, especially in the mobile colloidal fraction, was also correlated to thiols from algal sources. These results suggest thiol accumulation in the periphyton extracellular space, and that thiols likely promote mercury transfer to methylating microorganisms. A second study on preservation methods of natural water samples for LMW thiols conservation showed that a storage temperature of -80 °C was optimal and that freeze-drying led to an under-estimation of measured concentrations. Degradation rates were faster with storage at -20 °C and varied substantially depending on the chemistry of the water used as depending on thiol species observed. In regards of these results, we propose a research framework for future studies on mercury speciation processes in periphyton. We also suggest precautions on handling and storing natural samples for LMW thiol analyses
Photodemethylation of methylmercury in Eastern Canadian Arctic thaw pond and lake ecosystems
Permafrost thaw ponds of the warming Eastern Canadian Arctic are major landscape constituents and often display high levels of methylmercury (MeHg). We examined photodegradation potentials in high-dissolved organic matter (DOC) thaw ponds on Bylot Island (BYL) and a low-DOC oligotrophic lake on Cornwallis Island (Char Lake). In BYL, the ambient MeHg photodemethylation (PD) rate over 48 h of solar exposure was 6.1 Ă 10â3 m2 Eâ1, and the rate in MeHg amended samples was 9.3 Ă 10â3 m2 Eâ1. In contrast, in low-DOC Char Lake, PD was only observed in the first 12 h, which suggests that PD may not be an important loss process in polar desert lakes. Thioglycolic acid addition slowed PD, while glutathione and chlorides did not impact northern PD rates. During an ecosystem-wide experiment conducted in a covered BYL pond, there was neither net MeHg increase in the dark nor loss attributable to PD following re-exposure to sunlight. We propose that high-DOC Arctic thaw ponds are more prone to MeHg PD than nearby oligotrophic lakes, likely through photoproduction of reactive species rather than via thiol complexation. However, at the ecosystem level, these ponds, which are widespread through the Arctic, remain likely sources of MeHg for neighboring systems
Cooking and co-ingested polyphenols reduce in vitro methylmercury bioaccessibility from fish and may alter exposure in humans
Fish consumption is a major pathway for mercury exposure in humans. Current guidelines and risk assessments assume that 100% of methylmercury (MeHg) in fish is absorbed by the human body after ingestion. However, a growing body of literature suggests that this absorption rate may be overestimated. We used an in vitro digestion method to measure MeHg bioaccessibility in commercially-purchased fish, and investigated the effects of dietary practices on MeHg bioaccessibility. Cooking had the greatest effect, decreasing bioaccessibility on average to 12.5 ± 5.6%. Polyphenol-rich beverages also significantly reduced bioaccessibility to 22.7 ± 3.8% and 28.6 ± 13.9%, for green and black tea respectively. We confirmed the suspected role of polyphenols in tea as being a driver of MeHg's reduced bioaccessibility, and found that epicatechin, epigallocatechin gallate, rutin and cafeic acid could individually decrease MeHg bioaccessibility by up to 55%. When both cooking and polyphenol-rich beverage treatments were combined, only 1% of MeHg remained bioaccessible. These results call for in vivo validation, and suggest that dietary practices should be considered when setting consumer guidelines for MeHg. More realistic risk assessments could promote consumption of fish as a source of fatty acids, which can play a protective role against cardiovascular disease
Understanding food web mercury accumulation through trophic transfer and carbon processing along a river affected by recent run-of-river dams
Unlike large dams which favor methylation of Hg in flooded soils over long periods, run-of-river dams are designed to flood a limited area of soils and are therefore not expected to significantly affect mercury (Hg) cycling or carbon processing. We studied the Hg and carbon cycles within food webs from several sectors along the Saint-Maurice River, Quebec, Canada, that differ in how they are influenced by two run-of-river dams and other watershed disturbances. We observed peak Hg concentrations in fish five-year postimpoundment, but these levels were reduced three years after this peak. Methylmercury concentrations in low trophic level fish and invertebrates were related to their carbon source (ÎŽ13C) rather than their trophic positions (ÎŽ15N). Biomagnification, measured by trophic magnification slopes, was driven mainly by methylmercury concentrations in low-trophic level organisms and environmental factors related to organic matter degradation and Hg-methylation. River sectors, ÎŽ13C and ÎŽ15N, predicted up to 80% of the variability in food web methylmercury concentrations. The installation of run-of-river dams and the related pondages, in association with other watershed disturbances, altered carbon processing, promoted Hg-methylation and its accumulation at the base of the food web, and led to a temporary increase in Hg levels in fish
Conclusion
Based on the Baconian imperative that "knowledge is power", the drive for transparency gathers up ever-more speed. Especially in politics and economics, transparency has become a widely used catchphrase. Transparency is supposed to alter information asymmetries, improve market efficiency and establish a more inclusive and fair political praxis. While transparency is hoped to alter power relations, and thus to be a revolutionary or at least a reformative tool, surveillance is the privilege of those already in power, and thus regarded as a reactionary tool.       The studies in this joint volume have investigated this dichotomy by looking at various actors in regard to their possibility to change or cement existing power relations, symmetries, improve market efficiency, and establish a more inclusive and fair political praxis. While transparency is hoped to alter power relations, and thus to be a revolutionary or at least a reformative tool, surveillance is the privilege of those already in power. Each contribution, in its unique way, took a skeptical stance towards potential power shifts induced through societal or behavioral changes. This book examined a multitude of societal actors and the power relations between them. Although all contributions highlighted very different subject matters, some common themes emerged. These common themes ought to be highlighted in this final section. Moreover, this final chapter allows us to briefly summarise the central themes and most important finding of each article.       The first contribution treats surveillance and transparency as two sides of the same coin in the sense that both are attempts at changing behaviour by increasing the visibility of actors. Zeijl examines several attempts at transparency from a wide variety of actors. He argues that transparency, as it is currently put in practice by governments and companies, is more lip service than real concern with accountability and openness. Zeijl claims that these attempts at transparency are influenced by the logic of surveillance and therefore consolidate already existing power relations. While there are alternative ways of constructing transparency, they all have possible adverse effects that cannot and should not be easily cast aside. Therefore, one needs to critically assess what the exact benefits of transparency are in order to reach a balanced judgement on whether these possible adverse effects are worth the risk. Since transparency is more often invoked than defined, it is absolutely crucial to pay attention to the structure that transparency is supposed to assume, its organisation, its agents, and its potential impacts. Otherwise, transparency becomes a metaphysical catchphrase to graze (political) support rather than a real concern for accountability and openness
Acknowledgments
From January to June 2015, eleven students from the Bachelor Programmes Arts and Culture and European Studies participated in the course Transparency in Perspective at Maastricht University. This course was organised in the context of the Maastricht University Research Based Learning Project (MaRBLe), and was supervised by Dr. Nico Randeraad. This book includes shortened versions of the original papers of the students who have participated in the course. We would like to thank the organisers of the MaRBLe project, our external advisers, and in particular Dr. Nico Randeraad, for their support throughout the entire research process
Introduction
"Scientia potentia est" â knowledge is power. Many people seem to read this phrase, attributed to Francis Bacon, as a mission statement. If knowledge is power, then it is easy to understand why people demand more transparency and why at the same time surveillance increases. Transparency and surveillance are means to acquire knowledge and information. For centuries, governments have been surveilling their people to ensure that they behave according to their wishes
Designing small multiple-target artificial RNAs
MicroRNAs (miRNAs) are naturally occurring small RNAs that regulate the expression of several genes. MiRNAsâ targeting rules are based on sequence complementarity between their mature products and targeted genesâ mRNAs. Based on our present understanding of those rules, we developed an algorithm to design artificial miRNAs to target simultaneously a set of predetermined genes. To validate in silico our algorithm, we tested different sets of genes known to be targeted by a single miRNA. The algorithm finds the seed of the corresponding miRNA among the solutions, which also include the seeds of new artificial miRNA sequences potentially capable of targeting these genes as well. We also validated the functionality of some artificial miRNAs designed to target simultaneously members of the E2F family. These artificial miRNAs reproduced the effects of E2Fs inhibition in both normal human fibroblasts and prostate cancer cells where they inhibited cell proliferation and induced cellular senescence. We conclude that the current miRNA targeting rules based on the seed sequence work to design multiple-target artificial miRNAs. This approach may find applications in both research and therapeutics
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