Last 7 days
Bookmark and Share    
See detailInfrastructures in the Making: The Case of a Public Broadcasting Operator
Jemine, Grégory ULg; Pichault, François ULg; Dubois, Christophe ULg

Conference (2017, June 29)

This contribution explores how actors redefine infrastructures through an analysis of a project of “modernisation” in the making. Nowadays several companies undertake serious reflexions about their work ... [more ▼]

This contribution explores how actors redefine infrastructures through an analysis of a project of “modernisation” in the making. Nowadays several companies undertake serious reflexions about their work environments, tools and practices according to the “Bricks”, “Bytes” and “Behaviours” motto (De Leede, 2017). Relying on digital solutions they aim to enhance more flexible work practices in time and space. For that purpose various strategic and operational actors contribute actively to foreseeing the future of both facility, technological and social infrastructures. By means of adjustment mechanisms such as coordination meetings and alignment speeches, the actors take various actions in order to ensure the continuity of the organisation; they perform what Ribes and Finholt named the “Long Now”, an ongoing work to generate a “sustainable future” (2009, p. 377). Our interest lies in exploring simultaneously the incremental deconstruction of the existing infrastructures and the progressive construction of the forthcoming work environment. This innovation process may be seized by studying successive waves of problematisation using the actor-network theory. In the perspective of the ANT, an organisation is always a precarious agency made of both people and artefacts (Latour, 2005). Material issues, technological opportunities and constraints as well as power games emerge through the analysis of “controversies” which make parts of the infrastructures noticeable and subject to discussion and negotiation. Those controversies evolve through time, revealing various “range of visibilities” of people and things at different times in the process (Larkin, 2013, p. 336). Our research shows how actors simultaneously make sense of the existing infrastructure while enacting its future developments. We point out how the actors themselves perceive, describe and draw on the infrastructure in order to make sense of the strategic objectives, to conduct the change project and to maintain their institution. We shed light on the process of redefining and reshaping the infrastructure itself through controversies and adjustments. [less ▲]

Detailed reference viewed: 26 (3 ULg)
Full Text
See detailInfluence of Si precipitates on fracture mechanisms of AlSi10Mg parts processed by Selective Laser Melting
Delahaye, Jocelyn ULg; Rigo, Olivier; Lecomte-Beckers, Jacqueline ULg et al

Conference (2017, June 28)

Al alloy AlSi10Mg processed by Selective Laser Melting displays a very fine cellular eutetic microstructure (melt pool fine, MP fine) due to fast cooling rate from the melt. Such microstructural ... [more ▼]

Al alloy AlSi10Mg processed by Selective Laser Melting displays a very fine cellular eutetic microstructure (melt pool fine, MP fine) due to fast cooling rate from the melt. Such microstructural refinement results in high tensile strength and hardness. Studies have shown that a coarser cells region (melt pool coarse, MP coarse) as well as a heat affected zone (HAZ) can be observed at the melt pool boundary caused by a change of thermal history [1]. Those microstructural inhomogeneities act like a weak zone as demonstrated by the laser tracks observed on fracture features after tensile test [2]. This study aims at investigating in which zone fracture occurs. To do so, MP fine, MP coarse and HAZ were analyzed. Si precipitates spacing was compared with dimples size observed on fracture features. The Si precipitates fraction were quantified by image analysis. Hardness tests were performed in the 3 different zones by nanoindentation. [1] Thijs et al., Acta Mater. 61 (2013) pp. 1809-1819 [2] Tang et al., JOM 69 (2017) pp. 516-522 [less ▲]

Detailed reference viewed: 61 (7 ULg)
Peer Reviewed
See detail"Exploring Experiences of Inequality in European Urban Centers: Towards an Intersectional and Transnational Approach."
Vivas Romero, Maria ULg; Ramos, Cristina

Conference (2017, June 28)

What strategies do migrants living in European cities use to challenge inequalities in access to healthcare, participation in the labor market and the creation of social support networks? The papers in ... [more ▼]

What strategies do migrants living in European cities use to challenge inequalities in access to healthcare, participation in the labor market and the creation of social support networks? The papers in this panel aim to respond to this question by drawing from transnational and intersectional approaches conceptualizing inequalities as sets of relationships between people and broader structures in which interactions generate better opportunity for some more than for others (Tilly, 2000). Panel participants consider that these interactions and the benefits that can be obtained through migration are affected by various social categories such as gender, class, sexual identity, transnational connections, and citizenship. Intersectional approaches allow to examine how these axes of inequality (Crenshaw, 1989; Anthias, 2001) simultaneously affect migration outcomes and also how they operate differently according to the geographical space in which they develop: origin and host societies as well as transnationally. Nonetheless, the papers presented in this panel will also emphasize migrants’ agency to resist or conform to the inequalities they face. Overall, this panel aims to contribute to the study of migration and inequality at the conceptual and methodological levels. At the theoretical level, the panel will build on new debates on the reproduction of intersectional inequalities in transnational settings (Faist, 2016, Amelina, 2017). At the methodological level, all paper presenters have use multi-sited ethnographic methods (working in cities such as Madrid, London, Milan, Brussels and Frankfurt) and will therefore use the panel as an opportunity to discuss the strengths and weaknesses of such method. [less ▲]

Detailed reference viewed: 58 (4 ULg)
Full Text
See detailThermal history modelling to understand microstructures observed in repair technology of Ti-6Al-4V
Tomé Jardin, Ruben Antonio ULg; Tchuindjang, Jérôme Tchoufack ULg; Paydas, Hakan ULg et al

Conference (2017, June 28)

Study of laser cladding as a possible technology to repair Ti-6Al-4V. Development of a FEM thermal to predict microstructure.

Detailed reference viewed: 26 (6 ULg)
Full Text
See detailAn integrated logistics decision support model for city logistics
Limbourg, Sabine ULg

Scientific conference (2017, June 28)

Today, more than 50% of the world's population lives in cities; the urban population is projected to reach 85% by 2100. Mainly due to urbanization and e-commerce, the demand for urban freight transport ... [more ▼]

Today, more than 50% of the world's population lives in cities; the urban population is projected to reach 85% by 2100. Mainly due to urbanization and e-commerce, the demand for urban freight transport (both forward flows and reverse flows) is clearly growing. But, transport is also responsible for a large share of urban air pollution as well as noise nuisance. Thus, an integrated logistics system to optimize transport network and service design, as well as vehicles routing of a variety of modes has to be developed. The objective is to determine how to efficiently move freight by means of these services and vehicles, while reducing negative environmental impacts. The topic includes research questions related to the demand to be serviced, the type and number of facilities needed to store and consolidate freight, the better utilization of vehicle capacity (fill rate and fewer empty trips: on average, 25% of goods vehicles in Europe run empty) and the reduction of energy consumption. [less ▲]

Detailed reference viewed: 35 (1 ULg)
See detailFrom internal experts to external interlocutors? EU agencies and procedures assessing the equivalence of third country legal rules with EU regulatory standards
Van Cleynenbreugel, Pieter ULg

Scientific conference (2017, June 28)

this paper will offer an overview of procedures allowing EU agencies to determine the equivalence of third country regulatory regimes and conceptualise the accountability challenges they pose. Proceeding ... [more ▼]

this paper will offer an overview of procedures allowing EU agencies to determine the equivalence of third country regulatory regimes and conceptualise the accountability challenges they pose. Proceeding in three parts, the first part will identify and classify the different third country equivalence procedures in place. Analysing the legal basis for agency intervention and the specific powers granted to the respective agencies in that respect, this part will allow to develop a topology of two different equivalence roles conferred on EU agencies. Building upon this descriptive analysis, the second part will identify two accountability challenges associated with each of the identified third country equivalence procedure categories. Seeking to overcome those challenges, the third part of the paper will make four pointed suggestions aimed at recognising explicitly and in a more centralised way the external action powers conferred on EU agencies. Doing so would at the very least allow better to tailor modifications to the external action frameworks against the background of which existing equivalence procedures currently already implicitly operate. [less ▲]

Detailed reference viewed: 11 (1 ULg)
Full Text
Peer Reviewed
See detailDecreasing cloud cover drives the recent mass loss on the Greenland Ice Sheet
Hofer, S.; Tedstone, A.; Fettweis, Xavier ULg et al

in Science (2017), 3(6),

The Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate since the mid-1990s. This has been due to both increased ice discharge into the ocean and melting at the surface, with the ... [more ▼]

The Greenland Ice Sheet (GrIS) has been losing mass at an accelerating rate since the mid-1990s. This has been due to both increased ice discharge into the ocean and melting at the surface, with the latter being the dominant contribution. This change in state has been attributed to rising temperatures and a decrease in surface albedo. We show, using satellite data and climate model output, that the abrupt reduction in surface mass balance since about 1995 can be attributed largely to a coincident trend of decreasing summer cloud cover enhancing the melt-albedo feedback. Satellite observations show that, from 1995 to 2009, summer cloud cover decreased by 0.9 ± 0.3% per year. Model output indicates that the GrIS summer melt increases by 27 ± 13 gigatons (Gt) per percent reduction in summer cloud cover, principally because of the impact of increased shortwave radiation over the low albedo ablation zone. The observed reduction in cloud cover is strongly correlated with a state shift in the North Atlantic Oscillation promoting anticyclonic conditions in summer and suggests that the enhanced surface mass loss from the GrIS is driven by synoptic-scale changes in Arctic-wide atmospheric circulation. [less ▲]

Detailed reference viewed: 19 (3 ULg)
Full Text
Peer Reviewed
See detailOn the transition between symmetric and asymmetric flow in rectangular shallow reservoirs - a case of maximum energy dissipation?
Westhoff, Martijn; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

Conference (2017, June 28)

Shallow reservoirs are often used as sediment traps or storage basins, in which sedimentation depends on the flow pattern. Short rectangular reservoirs reveal a straight jet from inlet to outlet with ... [more ▼]

Shallow reservoirs are often used as sediment traps or storage basins, in which sedimentation depends on the flow pattern. Short rectangular reservoirs reveal a straight jet from inlet to outlet with identical recirculation zones on both sides. In longer reservoirs, the main jet reattaches to the side of the reservoir leading to small and large recirculation zones. Previous studies have found an empirical geometric relation describing the switch between these two flow patterns. In this study, we demonstrate, with a simple analytical model, that this switch coincides with a maximization of energy dissipation in the shear layer between the main jet and recirculation zones: Short reservoirs dissipate more energy when the flow pattern is symmetric, while longer reservoirs dissipate more energy with an asymmetric pattern. This approach enables the prediction of the flow patterns without detailed knowledge of small scale processes, potentially useful in the early phase of reservoir design. [less ▲]

Detailed reference viewed: 24 (0 ULg)
Full Text
See detailHolomorphic cohomological convolution
Dubussy, Christophe ULg

Poster (2017, June 28)

In his thesis, T. Pohlen succeeded in defining a Hadamard product between holomorphic functions defined on star-eligible subsets of the Riemann sphere. We show how this theory is actually a particular ... [more ▼]

In his thesis, T. Pohlen succeeded in defining a Hadamard product between holomorphic functions defined on star-eligible subsets of the Riemann sphere. We show how this theory is actually a particular case of the holomorphic cohomological convolution, defined in a general way thanks to the integration map on complex Lie groups. [less ▲]

Detailed reference viewed: 24 (5 ULg)
Full Text
See detailWear behaviour of laser clad High Speed Steels thick deposits
Hashemi, Seyedeh Neda ULg; Tchuindjang, Jérôme Tchoufack ULg; Dedry, Olivier ULg et al

Conference (2017, June 28)

The wear behaviour of 4 different High Speed Steel (HSS) thick coatings (one cast material and 3 laser clad deposits with varying Mo, V and W contents) was investigated at 2 different test temperatures, i ... [more ▼]

The wear behaviour of 4 different High Speed Steel (HSS) thick coatings (one cast material and 3 laser clad deposits with varying Mo, V and W contents) was investigated at 2 different test temperatures, i.e. at room temperature and at 300°C. For all four materials under both test conditions, oxidative wear was identified as the main wear mechanism. The 3 laser clad deposits exhibit a higher wear resistance compared to the conventional cast reference material, and this effect was mainly attributed to their strongly refined microstructures. Moreover, a detailed comparison of the wear behaviour of the 3 laser clad deposits, in correlation with their microstructures, allows a better understanding of the effect of the different carbides and of their morphology. [less ▲]

Detailed reference viewed: 44 (12 ULg)
Full Text
Peer Reviewed
See detailFrom local initiatives to territorial transition project: case study of a grassroots food belt project in Liège (Belgium)
Feyereisen, Marlène ULg; Stassart, Pierre M ULg; Jonet, Christian

Conference (2017, June 28)

This study analyses a local food initiatives in Liege (Belgium) linked to the Transition Network movement: Ceinture Aliment-Terre Liégeoise (CATL). The study aims to analyse how CATL evolved from a ... [more ▼]

This study analyses a local food initiatives in Liege (Belgium) linked to the Transition Network movement: Ceinture Aliment-Terre Liégeoise (CATL). The study aims to analyse how CATL evolved from a marginal grassroots movement, to a project of transition of the agri-food system which is considered exemplary by Belgian institutional actors. [less ▲]

Detailed reference viewed: 38 (5 ULg)
Full Text
See detailAntimicrobial activities of key intermediate plant oxylipins
Deboever, Estelle ULg

Conference (2017, June 28)

Nowadays, biopesticides have emerged as a main alternative to conventional agriculture. In this context, plant oxylipins, a vast and diverse family of secondary metabolites originated from polyunsaturated ... [more ▼]

Nowadays, biopesticides have emerged as a main alternative to conventional agriculture. In this context, plant oxylipins, a vast and diverse family of secondary metabolites originated from polyunsaturated fatty acids (PUFAs), appear to be crucial agents in plant defense mechanisms. Among plant oxylipins, the 13-hydroperoxy oxylipins (13-HPO) constitute key intermediate oxylipins (KIOs) as they can be converted into jasmonic acid, OPDA, dn-OPDA or traumatic acid, well-characterized components involved in plant resistance mechanisms. Their presumed functions include direct antimicrobial effect, stimulation of plant defense gene expression, and/or regulation of plant cell death. However, the precise contribution of each KIOs to plant defense remains essentially unknown. In this work, we focus on two h13-HPO, the 13(S)-hydroperoxy-octadecadienoic acid (13-HPOD) and the 13(S)-hydroperoxy-octadecatrienoic acid (13-HPOT). In vitro growth inhibition assays were performed to investigate the direct antimicrobial activities against 7 pathogens of agronomic interest including bacteria, oomycetes and fungi. This study showed unambiguously that 13-HPO are able to hinder growth of some plant microbial pathogens, generally with a higher efficacity for 13-HPOT. In order to get a better insight into their mechanism of action, a complementary in silico and experimental biophysical approach was applied. Biomimetic pathogen plasma membranes are used to study the mechanism at the molecular level. Slight conformational differences may have significant impacts on their ability to interact with pathogens lipids and plasma membranes. [less ▲]

Detailed reference viewed: 27 (1 ULg)
Full Text
Peer Reviewed
See detailAbsent, yet present? Tracing "Responsible Research and Innovation" in Radiation Protection Research
Van Oudheusden, Michiel ULg

Conference (2017, June 28)

In this paper, I argue that although the notion of responsible research and innovation (RRI) is manifestly absent in research programs for radiation protection and nuclear research and training, RRI is ... [more ▼]

In this paper, I argue that although the notion of responsible research and innovation (RRI) is manifestly absent in research programs for radiation protection and nuclear research and training, RRI is increasingly recognized, and mobilized, by various actors in the field; is an essentially contested concept; and facilitates the development of a sizeable network comprising actors with a variety of roles, expectations and stakes, including researchers in the social sciences and humanities (SSH). To sustain these points, I draw on my experiences as an embedded social scientist in nuclear research, singling out sites and instances (e.g. the crafting and dissemination of the 2015 Ricomet Public Declaration, SSH research within the EU-Concert framework, conversations with radiation protection researchers) where RRI is explicitly discussed, propagated, negated, or transformed. This exploration highlights recurring challenges of “translating” RRI to radiation protection research, such as the strong evaluative connotation of RRI and its top-down character; the lack of industry involvement in RRI processes; the tight connection between RRI and new and emerging technologies; and the hybridization of SSH through inter- and transdisciplinary research. I discuss each of these challenges in turn, with the aims of reflexively considering how RRI is co-produced in radiation protection research through negotiations between stakeholders and the interplay of practices and artifacts; and what the potential implications of these processes are for SSH engagement in the field. [less ▲]

Detailed reference viewed: 13 (0 ULg)
Full Text
See detailThe behavior of pesticide during beer brewing and the toxicity of pesticide using state-of-the-art omic tools
Kong, Zhiqiang ULg

Doctoral thesis (2017)

Beer is an extremely popular beverage worldwide, representing the third-most popular drink after water and tea. And barley is the major raw material used for beer production. However, various combinations ... [more ▼]

Beer is an extremely popular beverage worldwide, representing the third-most popular drink after water and tea. And barley is the major raw material used for beer production. However, various combinations of pesticides are widely used at several stages of barley culti¬vation and during post-harvest storage to control pest and fungal disease. Hence, traces of these pesticides might remain in the beer produced from the treated ingredients. Hence, monitoring trace levels of pesticide residues during beer brewing and investigated the effects of pesticide residue on the quality of beer is essential. First, the behavior and fate of 3 pesticides (triadimefon, malathion, and dichlorvos) and the main metabolites (triadimenol and malaoxon) during barley storage or beer processing were assessed using a pilot-plant equipment. The residues of all products were determined using liquid chromatography coupled with tandem mass spectrometry. Field investigation of the dissipation rate kinetics for triadimefon and malathion during storage indicated that their half-life was twice as high when 5 times the recommended dosage was used. Milling had little effect on removing dichlorvos and malathion residues, whereas they were substantially removed when the spent grains were mashed. The calculated processing factors after processing were all <1, indicating that the residual ratios of dichlorvos and malathion were reduced during the entire process. In conclusion, storage and processing extensively reduced pesticide residue levels in barley and beer; however, greater focus needs to be paid to the toxicity of their metabolites in commercial by-products. Then we selected the triadimefon as the target fungicide to further study its behavior, the dissipation kinetics of TF during fermentation mediated by two different yeast strains, Saccharomyces cerevisiae IAPPST 1401 (Y1) and CICC 1202 (Y2), and found that Y2 promoted the degradation of TF. Response surface methodology was used to optimize fermentation process variables, in order to achieve the maximum removal rate of TF and the minimum production of its corresponding metabolite, triadimenol (TN). Triadimefon is also a widely used triazole fungicide with one chiral carbon center, Stereoselective degradation of triadimefon was found during barley storage, the half-life of S-(+)-triadimefon was 36.5d, 31.5d and 30.1d, while R-(-)-traidmefon was 69.3d, 53.3d and 33d under 4°C, 25°C and 40°C, respectively. During brewing process, both enantiomers of triadimefon were easily degraded. After fermentation, little triadimefon detected in the beer, while RS-(+) and SS-(-)-triadimenol were detectable. This research provides accurate information for evaluating the risk of food safety. Furthermore, we investigated the effect of triadimefon affect the quality and flavor of the fermented beer, The effect of triadimefon on yeast growth and the sensory quality of beer were studied. There were significant differences in sensory quality between beer samples fermented with and without triadimefon based on data obtained with an electronic tongue and nose. Such an effect was most likely underlain by changes in yeast fermentation activity, including decreased utilization of maltotriose and most amino acids, reduced production of isobutyl and isoamyl alcohols, and increased ethyl acetate content in the fungicide treated samples. Furthermore, yeast metabolic profiling by phenotype microarray and UPLC/TOF-MS showed that triadimefon caused significant changes in the metabolism of glutathione, phenylalanine and sphingolipids, and in sterol biosynthesis. Thus, triadimefon negatively affects beer sensory qualities by influencing the metabolic activity of S. cerevisiae during fermentation, emphasizing the necessity of stricter control over fungicide residues in brewing by the food industry. [less ▲]

Detailed reference viewed: 43 (3 ULg)
See detailRôle des lymphocytes T TCR γδ dans la progression des lésions associées à l'infection par les papillomavirus humains
Van Hede, Dorien ULg

Doctoral thesis (2017)

Cervical cancer was the fourth most frequent cancer in women in 2012, with the majority of cases occurring in less developed countries. Although this cancer is induced by Human Papillomavirus (HPV ... [more ▼]

Cervical cancer was the fourth most frequent cancer in women in 2012, with the majority of cases occurring in less developed countries. Although this cancer is induced by Human Papillomavirus (HPV) infections that have a high prevalence, only a very few percentage of infected women will developed this disease. Host immune defenses are essential to clear infection and to kill virus-infected transformed cells. Indeed, majority of infected women clear the virus within two years while immunocompromised patients are more likely to develop cervical preneoplastic lesions and cancers. γδ T cells have been shown to protect against the formation of squamous cell carcinoma (SCC) in several models. Nowadays, the contribution of γδ T cells in HPV associated uterine cervical SCC is unknown. Here we investigated the impact of γδ T cells in a transgenic mouse model of carcinogenesis induced by HPV16-oncoproteins. Surprisingly, γδ T cells promoted the development of HPV16-oncoprotein-induced lesions. These oncoproteins induced a decrease in epidermal Skint-1 expression and modification of the associated anti-tumor Vγ5+ γδ T cells (or DETC), which were joined by other γδ T cell subsets actively producing IL-17. Consistent with a proangiogenic role, γδ T cells promoted the formation of blood vessels in the dermis underlying the HPV-induced lesions. In human cervical, IL-17+ γδ T cells could be only observed at the cancer stage (SCC) (but not in less advanced cervical lesions), where HPV oncoproteins are highly expressed, supporting the clinical relevance of our observations in mice. Overall, our results suggest that HPV16-oncoproteins induce a reorganization of the local epithelial-associated γδ T cell Subpopulations thereby promoting angiogenesis and cancer development. [less ▲]

Detailed reference viewed: 28 (0 ULg)
Full Text
See detailSpatial diversification of agroecosystems towards biological control of insect pests: A focus on intercropping and wildflower strips
Hatt, Séverin ULg

Doctoral thesis (2017)

Facing the limits of input-intensive agriculture, agroecology aims at thinking ways to design a sustainable agriculture that is economically viable and socially relevant. It notably invites to mobilize ... [more ▼]

Facing the limits of input-intensive agriculture, agroecology aims at thinking ways to design a sustainable agriculture that is economically viable and socially relevant. It notably invites to mobilize ecological processes within agroecosystems in order to enhance the delivery of ecosystem services towards reducing the use of external inputs – among others insecticides. For enhancing biological control of insect pests, a strategy is to spatially diversify agroecosystems at the field scale. Whereas increasing plant diversity could directly negatively affect pest development on the one hand (i.e. bottom-up effect), providing flowering features could allow the enhancement of natural enemies and their direct effect on pest populations on the other hand (i.e. top-down effect). The present thesis focused on intercropping (i.e. the cultivation of at least two crop species simultaneously in a same field) as a way to diversify crop habitat, and the sowing of wildflower strips as a non-crop feature. A systematic analysis of the literature revealed that, in most of studies, wheat (Triticum aestivum L.)-based intercropping allows a reduction of insect pests on crops, without necessarily favouring their natural enemies, compared to pure-stands. Besides, the provision of flowering resources, by for instance sowing wildflower strips, can attract and support flower visiting predators and parasitoids. Hence, in a first set of field experiments, combining the two tactics of increasing crop diversity and providing flowering resources was tested. First in China, wheat crop was associated with oilseed rape (Brassica napus L.), but it neither allowed reducing aphid (Hemiptera: Aphididae) abundance nor enhancing their natural enemies compared to pure stands. Instead, aphid density – independently from the treatments – affected natural enemy abundance, and interspecific relations between aphids and their natural enemies were observed. Second in Belgium, wildflower strips were sown within a wheat field, which led to a reduction of aphid density in wheat plots in between flowering features and an increase of aphidophagous hoverflies (Diptera: Syrphidae) compared to pure-stand wheat. Nevertheless, the presence of flowering strips did not affect the other natural enemies, i.e. lacewings (Neuroptera: Chrysopidae), ladybeetles (Coleoptera: Coccinellidae) and parasitoid wasps (Hymenoptera: Braconidae). Therefore, a second set of field experiments focussed on ways to compose mixtures of wild flowers attractive to a diversity of natural enemies. Flower functional traits were considered due to their effect on insect behaviour. First, the hypothesis that mixtures with high functional diversity attract and support a high abundance and diversity of aphid flower visiting predators was tested. This hypothesis was not verified. Instead, the high density in the plots of some flower species (especially the Asteraceae Leucanthemum vulgare Lam.) known to be attractive to flower visitors was supposed to have overwhelmed the effect of functional diversity. Second, a methodology was developed to identify which flower traits significantly affect natural enemy abundance – in this experiment parasitoids of oilseed rape beetle pests (i.e. Meligethes spp. [Coleoptera: Nitidulidae] and Ceutorhynchus spp. [Coleoptera: Curculionidae]) – in flower mixtures. Among seven traits, visual traits (i.e. colour, ultra-violet reflectance) and the one related to food availability (i.e. corolla morphology) were found to significantly affect parasitoid abundance. These results highlight that (i) increasing plant diversity at the field scale can – but not systematically – favour a reduction of insect pests, (ii) including flowering features can enhance some – but not all – of their natural enemies, and (iii) in order to compose flower mixes attractive to natural enemies, specific flower traits – rather than functional diversity at the mixture level – can be considered. These results are discussed in a broader perspective. Indeed, strategies to spatially diversify crop and non-crop habitats in agroecosystems are various, as well as the ways to compose, manage and design such habitats. Also, processes at larger scales than the field may be determinant. Moreover, insects are not the only pests, and pests are not the only biotic or abiotic elements that need to be regulated in agroecosystems. Controlling multiple pests simultaneously but also enhancing the provision of multiple regulating services represent challenges for future research in agriculture. [less ▲]

Detailed reference viewed: 77 (19 ULg)
Full Text
See detailProxima Cen b: theoretical spectral signatures for different atmospheric scenarios
Defrere, Denis ULg; Léger, Alain; Grenfell, John Lee et al

Speech/Talk (2017)

Proxima Cen b is possibly the nearest rocky exoplanet orbiting in the habitable zone of its star and might represent by consequent a formidable opportunity for astrobiology. In this presentation, we ... [more ▼]

Proxima Cen b is possibly the nearest rocky exoplanet orbiting in the habitable zone of its star and might represent by consequent a formidable opportunity for astrobiology. In this presentation, we discuss several possible atmospheric compositions and present the corresponding infrared spectrum computed with modern planetary atmosphere models. To be specific, we consider (1) a bare planet, which has lost its atmosphere; (2) a water-ocean planet; (3) an Earth-analog planet; and (4) a planet similar to Earth but with a lower O2 pressure (< 1mbar) that produces a false positive for the triple signature (H20, O3, and CO2). We discuss the information contained in each infrared spectrum and the possibility to constrain the nature of the planet by remote sensing. We end this presentation by describing an instrumental concept recently proposed to ESA and optimised for this task. [less ▲]

Detailed reference viewed: 26 (1 ULg)