Litter Quality of Populus Species as Affected by Free-Air CO2

The effect of elevated CO2 and nitrogen fertilization on the molecular chemistry of litter of three Populus species and associated soil organic matter (SOM) was investigated by pyrolysis-gas chromatography/mass spectrometry. The results are based on 147 quantified organic compounds in 24 litter samples. Litter of P. euramerica was clearly different from that of P. nigra and P. alba. The latter two had higher contents of proteins, polysaccharides, and cutin/cutan, while the former had higher contents of phenols and benzofurans/pyrans. The difference between replications was at least as large as the effect of treatments, so that no systematic chemical changes were attributable to CO2 effect or N-fertilization effect. The chemistry of SOM under the various species and treatments did not show significant changes either. The low number of available replicates that is two was clearly insufficient to overcome the effect of spatial variation on litter chemistry and detect small differences in molecular litter chemistry

Member-to-member generalisation in trust behaviour: How do prior experiences inform prosocial behaviour towards novel ingroup and outgroup members

Trust in individuals is strongly guided by group membership; ingroup favouritism in trust is a very robust finding in the literature on pro-social behaviour. We know, however, that group attitudes can change based on discrete encounters with group members (i.e., intergroup contact). This research examines how people use previous experiences with ingroup and outgroup members to inform decisions to trust novel, unknown group members. This process, which we refer to as member-to-member generalisation, was examined in two studies using a student sample (N = 135) and a larger and more representative online sample (N = 226). The moderating effects of group membership (ingroup vs outgroup vs unknown) and interaction valence (positive vs negative) on member-to-member generalisation were explored in ten sequential Trust Games. We examined changes in investment behaviour based on feedback from the previous partner, where feedback was either positive (high reciprocation) or negative (no reciprocation). We observed consistent evidence for member-to-member generalisation. People did not just rely on initial group attitudes to guide their trust behaviour, but adjusted their behaviour towards novel individuals based on previous experiences. Generalisation was stronger for interactions that were negative and seemingly unexpected. When people showed strong distrust of the outgroup (Study 1) or were highly identified with the ingroup (Study 2), they changed their behaviour towards novel partners more after experiencing incongruent interactions. These findings are discussed in relation to intergroup contact theory, outgroup homogeneity, and expectancy violation effects

Group-based biases influence learning about individual trustworthiness

People often have generalised expectations of trustworthiness about ingroup and outgroup members, based on previous direct and indirect experience with these groups. How do these prior biases interact with new experiences when learning about individual group members’ trustworthiness? These three studies are the first to examine the effect of group-level biases on learning about individuals’ trustworthiness. Participants from the Netherlands and the United Kingdom played iterated Trust Games with trustworthy and untrustworthy members of both ingroups and outgroups. We show that the influence of group membership on trust decisions depended on the valence of the interactions with individual group members. When interacting with trustworthy partners, people displayed outgroup favouritism throughout the game, investing higher in outgroup members than ingroup members. However, for untrustworthy partners, initial outgroup favouritism disappeared, and ingroup and outgroup members were equally distrusted by the end of the game. Our work suggests that when individual experience is integrated with group-based biases, group membership influences trust decisions over time, but mostly when experiences are positive. These findings are discussed in relation to complexity-extremity theory and previous work on learning in the Trust Game

Remembering the past, experiencing the present, and predicting the future: Social-cognitive perspectives on intergroup contact

One of the most robust interventions for reducing prejudice is intergroup contact. Whilst the affective processes involved in prejudice reduction via intergroup contact are becoming well understood, this thesis explores novel social-cognitive factors surrounding intergroup contact. Two strands of research explore how people look back at past contact and look forward to future interactions with unfamiliar group members. Experiments 1 to 4 examine how experiences of fluency in recalling past contact may influence people’s perceptions of their intergroup contact, and in turn influence outgroup attitudes and future contact intentions. Utilising two different paradigms in Chapter 2 and 3, no effect of the manipulation of contact retrieval fluency was found on any of the outcome variables. Potential reasons for this null-effect are discussed, including memory biases, inference processes regarding the contact-attitude relationship, and affective and normative components of prejudice. The second strand of research described in Chapter 4 and 5 moves focus from the past to the future, to examine generalisation of intergroup contact to trust behaviour towards novel group members. This process of member-to-member generalisation was examined within a Trust Game paradigm, where group membership and interaction valence were manipulated. Experiments 5 to 8 demonstrate that people use their experiences with group members to inform decisions to trust unknown individuals in the future. Member-to-member generalisation was enhanced for negative compared to positive experiences, but was particularly attuned to violations of previous group-based beliefs. Together, this thesis highlights the importance of social-cognitive processes involved in intergroup contact generalisation to attitudes and behaviour, and shows the potential of using laboratory-based behavioural measures to examine intergroup contact

On the Ambiguity of Rank-Based Evaluation of Entity Alignment or Link Prediction Methods

In this work, we take a closer look at the evaluation of two families of methods for enriching information from knowledge graphs: Link Prediction and Entity Alignment. In the current experimental setting, multiple different scores are employed to assess different aspects of model performance. We analyze the informativeness of these evaluation measures and identify several shortcomings. In particular, we demonstrate that all existing scores can hardly be used to compare results across different datasets. Moreover, we demonstrate that varying size of the test size automatically has impact on the performance of the same model based on commonly used metrics for the Entity Alignment task. We show that this leads to various problems in the interpretation of results, which may support misleading conclusions. Therefore, we propose adjustments to the evaluation and demonstrate empirically how this supports a fair, comparable, and interpretable assessment of model performance. Our code is available at https://github.com/mberr/rank-based-evaluation

Contribution à l'évaluation multicritère des systèmes de culture en protection intégrée contre les adventices : cas des émissions de protoxyde d'azote

In the context of the multicriteria evaluation of Integrated Weed Management (IWM) cropping systems, our study highlights the impacts of the combination of alternative agricultural practices to herbicide reliance on N2O emissions from soils. The study was located at the INRA experimental site of Dijon-Epoisses (47 ° 20'N, 5 ° 2'E) and considered 4 cropping systems, a reference system designed to maximize financial returns (S1) and three IWM systems (S2, S3, S5). The setup of high resolution measuring devices, combining the non-steady state chamber method with infrared gas analysis, allowed to estimate the intensity of N2O emissions from the calcareous clay soil, which is specific of Dijon plain, with average fluxes laying between -6 and 257 g N2O-N ha-1 day-1. The intensity of fluxes was closely related to environmental parameters (temperature, water filled pore space, inorganic N amount) and particular agricultural practices, leading to significant differences between systems. N2O emissions were notably affected by soil management and nature of crops. The conversion of S2 system to no-till in 2008 increased the N2O emissions, fluxes being at least 6 times more important than those emitted by the other cropping systems, during the year 2012. Moreover, these emissions, equivalent to 0.7 ha-1 C-CO2 ha-1, could have offset the soil additional carbon sequestration induced by reduced tillage during the studying period. Similarly, the degradation of legume crop residues in the S3 and S5 systems respectively enhanced N2O emissions in 2011 and 2012, by comparison with the S1 reference system. Elsewhere, the monthly monitoring of the soil microbial communities sizes has also helped to highlight temporal variability induced by the agricultural practices (tillage, harvest) as well as the seasonal variability. However, in this study the fluctuations of nitrifying and denitrifying communities sizes observed did not explain the variability of N2O emissions, whatever the considered cropping system. Finally, the modeling of N2O emitted from the 4 cropping systems, using NOE and DNDC models, allowed to identify the mains factors regulating the emissions. In addition, the NOE model accurately identified the S2 system, without tillage, as the most N2O emitter, in accordance with field observations. Thus, our study reinforces the relevance of modeling to estimate and explain N2O emissions in different cropping systems.Dans le cadre de l’évaluation multicritère des systèmes en protection intégrée contre les adventices (PIC-Adventices), cette étude a eu pour objectif d’étudier l’impact de la combinaison de pratiques alternatives à l’usage d’herbicides sur les émissions de N2O par les sols. L’étude a été conduite sur quatre systèmes de culture, un système de référence en agriculture raisonnée (S1) et trois systèmes PIC-Adventices (S2, S3, S5), sur le site expérimental Dijon-Epoisses (47°20'N, 5°2'E). La mise en place de dispositifs de mesure à haute résolution, alliant la méthode des chambres d’accumulation de gaz en surface du sol aux analyses de gaz par infrarouge, a permis d’estimer l’intensité des émissions de N2O pour les sols argilo-calcaires caractéristiques de la plaine dijonnaise, avec des flux moyens compris entre -6 et 257 g N-N2O ha-1 jour-1. Cette intensité s’est avérée étroitement liée à certains paramètres environnementaux (température, part de porosité occupée par l’eau, teneur en azote), et certaines pratiques agricoles, induisant des différences significatives entre les systèmes. Les émissions de N2O ont notamment été affectées par le mode de gestion des sols et la nature des cultures constituant la succession de chaque système. L’absence de travail du sol depuis 2008 dans le système S2 s’est traduite par une amplification des émissions de N2O d’un facteur multiplicatif d’au moins six par rapport aux autres systèmes pour l’année 2012. Par ailleurs, ces émissions équivalentes à 0.7 t C-CO2 ha-1 pourraient avoir compensé la séquestration de carbone additionnelle induite par le travail réduit du sol pendant la période de mesure. De la même manière, la dégradation des résidus de culture légumineuse, dans les systèmes S3 et S5 ont respectivement stimulé les émissions de N2O en 2011 et en 2012, en comparaison avec le système de référence S1. Par ailleurs, le suivi mensuel de la taille des communautés microbiennes du sol a également permis de mettre en évidence une variabilité temporelle liée aux pratiques culturales (travail du sol, récolte), en plus de la variabilité saisonnière. En revanche, dans cette étude les variations de taille des communautés microbiennes nitrifiantes et dénitrifiantes ne sont pas apparues comme un facteur d’explication de la variabilité des émissions de N2O, quel que soit le système. Enfin, l’approche par la modélisation des émissions de N2O sur les quatre systèmes, à l’aide des modèles NOE et DNDC, a permis d’identifier les principaux facteurs de régulation de ces émissions. De surcroît, le modèle NOE a bien identifié le système de culture S2, sans travail du sol, comme étant le système le plus émetteur de N2O, conformément aux observations de terrain. Cette étude renforce donc la pertinence de la modélisation pour estimer et analyser les émissions de N2O dans différents systèmes de culture

Visit to Papermaking Studio; Letterpress Studio; Media Archaeology Collection

Aimee Lee: Papermaking StudioLocation: Hales Gym Ed Vermue: Letterpress Studio Demo and Open HouseLocation: Mary Church Terrell Main Library Rian Brown-Orso and Heath Patten: Media Archaeology Collection of Objects and Screening of Rian Brown-Orso\u27s animated shortsLocation: Goodrich Room, Mary Church Terrell Main Librar