How closely are Pericopsis elata (Fabaceae) patches linked to past human disturbances in South-Eastern Cameroon
Bourland, Nils ; ; Daïnou, Kasso et al
Conference (2013, June 26)
Studies conducted in the Congo Basin forests concluded that soil parameters and large disturbances induced by human activities since 3000–2000 BP could be the main driver for the persistence of long lived ... [more ▼]
Studies conducted in the Congo Basin forests concluded that soil parameters and large disturbances induced by human activities since 3000–2000 BP could be the main driver for the persistence of long lived light-demanding tall tree species. Today most of the timber species belong to this group, among them Pericopsis elata (Fabaceae). Like many other light-demanding trees, this species suffers from important regeneration problems. While the conditions for its establishment must have been met in the past, they obviously have become unfavourable. Because of ongoing logging activities and a natural decline of its populations, this species is recorded in both the IUCN Red List and the CITES Appendix II listings. Our goal was to investigate the roles of both pedological and anthropogenic factors in the persistence of forest patches characterized by this clustered species. Soil surveys, botanical inventories and anthracological excavations were conducted in three different forest sites located in south-eastern Cameroon. P. elata patches (3.3-14.7 ha) were studied and compared to their close surroundings. No statistical differences were observed between the results of botanical inventories conducted inside and outside the patches (Morisita-Horn indices from 0.69-0.77). Soils only differed in Fe content, but otherwise no significant differences could be observed. Charcoal is widespread and abundant in study sites, mostly inside the patches. Charcoal radiocarbon dating (2,150-195 BP) was consistent with decoration techniques of archaeological materials that we discovered. The average age of P. elata individuals coincides with fire events that occurred in a region where fires rarely occur naturally. We present evidence of past anthropogenic disturbances (human settlement, slash-and-burn cultivation) in the Congolese mixed moist semi-evergreen forest in south-eastern Cameroon. We discuss the potential influence of our findings on the management of light-demanding tall trees populations in a context of logging activities. [less ▲]Detailed reference viewed: 108 (25 ULg)
How compatible is perfect competition with transmission loss allocation methods?
; ; et al
in Proceedings of the 5th International Conference on the European Electricity Market (EEM-08) (2008)
This paper addresses the problem of transmission loss allocation in a power system where the generators, the demands and the system operator are independent. We suppose that the transmission losses are ... [more ▼]
This paper addresses the problem of transmission loss allocation in a power system where the generators, the demands and the system operator are independent. We suppose that the transmission losses are exclusively charged to the generators, which are willing to adopt a perfectly competitive behavior. In this context, their offers must reflect their production costs and their transmission loss costs, the latter being unknown beforehand and having to be predicted. We assume in this paper that the generators predict their loss costs from the past observations by using a weighted average of their past allocated costs. Under those assumptions, we simulate the market dynamics for different types of transmission loss allocation methods. The results show that the transmission loss allocation scheme can lead to a poorly efficient market in terms of social welfare. [less ▲]Detailed reference viewed: 91 (6 ULg)
How complex can be the Unimolecular Decomposition of a simple Molecule? The case of Acetylene. An Electron Impact and PIPECO Investigation.
Locht, Robert ; Servais, Christian
in Zeitschrift für Physikalische Chemie (1996), 195
The dissociative ionization of C2H2, C2D2 and C2HD is presented in this work. Excepting the H2+ formation, all dissociation channels are thoroughly investigated by electron impact. The translational ... [more ▼]
The dissociative ionization of C2H2, C2D2 and C2HD is presented in this work. Excepting the H2+ formation, all dissociation channels are thoroughly investigated by electron impact. The translational energy distribution as a function of the impinging electron energy and the appearance energy as a function of the translational energy are measured for all fragment ions. KE versus AE diagrams are obtained and the isotope effect is examined. All observed thresholds are analyzed in detail and dissociation mechanisms are proposed. For the C2H+ ion the PIPECO technique has also been used. From these discussions the H-C2H, HC-CH and H-C2 binding energy values are proposed, i.e. 5.33+/-0.23 eV, 9.83+/0.10 eV and 5.44+/-0.40 eV respectively. The fragmentation path leading to C+, CH2+ and C2+ are discussed in terms of dissociation mechanisms involving the transient vinylidene structure of the molecular ion as an intermediate. [less ▲]Detailed reference viewed: 73 (5 ULg)
How conditioning by one’s job leads to visual misrepresentation: Evidence from Rorschach test in nurse population
Englebert, Jérôme ; Blavier, Adelaïde
Poster (2011, May 27)
Exner (1974, 2003, 2005) has developed an empirical method for analyzing answers at Rorschach test. This analysis is not focused on the answer content but more on perception, information processing and ... [more ▼]
Exner (1974, 2003, 2005) has developed an empirical method for analyzing answers at Rorschach test. This analysis is not focused on the answer content but more on perception, information processing and quality of the answer. Thus, contrary to psychoanalysis, the content and its interpretation are not systematically studied in this empirical approach. In this perspective, our purpose was to empirically study how answers and performance at Rorschach test were conditioning by one’s job. We administrated Rorschach test to 38 nurses and 38 paired subjects (matched for gender and age). Our data showed nurses gave significantly more anatomical answers than control subjects, this first result confirmed a clinical assumption that was never objectified by previous studies: conditioning by one’s job influences the answer content at the Rorschach test (e.g., people from medical sector tend to see organs). The second main result is the formal qualities of anatomical answers given by nurses were significantly worse and more unusual than anatomical answers given by the control group. These findings suggest that conditioning by one’s job is so strong that it overrides the other choices of answers and can lead to a deformation of the visual perception. Furthermore, the content is the main answer element subjects can control in this test and thus, it could be a means of affirming his/her identity (e.g., nurse’s identity by anatomical content). Moreover, in regard to the bad formal quality of anatomical answers, it seems that nurse’s identity takes precedence over the reality and the actual form perception. [less ▲]Detailed reference viewed: 47 (11 ULg)
How convection and diffusion processes might affect biological imprints, a challenge for modelers
; Zhou, Jiayun ; et al
Conference (2012, April)Detailed reference viewed: 8 (2 ULg)
How could Mosan agriculture be impacted by climate change and future droughts?
Bauwens, Alexandra ; Sohier, Catherine ; Deraedt, Deborah et al
in Geophysical Research Abstracts (2012), 14
Despite the great uncertainties regarding the future climatic context, lots of studies have focused on hydrological effects of climate change on the Meuse catchment. It appears that both winter high flows ... [more ▼]
Despite the great uncertainties regarding the future climatic context, lots of studies have focused on hydrological effects of climate change on the Meuse catchment. It appears that both winter high flows and summer low flows could be exacerbated. Climate change and its impacts on hydrology will thus affect various socio-economic sectors. High flows have been widely studied compared to low-flows. This poster will put the emphasis on a methodology developed in order to study impacts of droughts on agriculture. Agriculture is among the most impacted sectors due to climate change. The consequences could be both positive as negative in accordance with the range of predicted changes and the adaptation capacity of agricultural systems. Most of the existing studies related to climate change on agriculture focused on specific territory. Within the AMICE Interreg IVB project, a transnational approach has been developed to assess droughts impacts on agriculture through the Meuse basin. The project’s previous works gave us a common scenario of climate trends and of the evolution of the hydrology in the Meuse basin. The methodology is based on the use of a physically-based model able to simulate the water-soil-plant continuum (derived from EPIC model). In order to be transferable from one country to another, the methodology proposed used data available at the basin scale. The UE soil data base was complemented with local information on agricultural practices and statistics. Three crops have been studied: maize, wheat and barley. The basic cultural calendar is supposed to be the same for the different countries. The methodology developed permits to study the evolution of yields, leaf area index, crops stress due to excess or lack of water through time under different scenarios build up in the frame of the project. It appears that corn is negatively affected by climate change, and thus despite the CO2 fertilization effect. Wheat and barley have similar behavior and are positively affected by climate change and CO2 fertilization. Leaf Area Index study reveals that the different crops start earlier and reach earlier maturity. These first results will be completed with other economic sectors’analysis like drinkable water production, electricity production and navigation. Therefore, the project will progress towards a better understanding of economic effects of future droughts and low-flows. [less ▲]Detailed reference viewed: 50 (18 ULg)
How could the Io footprint disappear?
; Bonfond, Bertrand ;
in Planetary and Space Science (2013), 89
The interaction of Io with the Jovian magnetosphere is the best known – and the most intense – case of satellite-magnetosphere interaction. The interaction involves a power of more than a TeraWatt, a few ... [more ▼]
The interaction of Io with the Jovian magnetosphere is the best known – and the most intense – case of satellite-magnetosphere interaction. The interaction involves a power of more than a TeraWatt, a few percent of which are transferred to electrons. These electrons precipitate in the Jovian ionosphere where they light-up bright auroral emissions (several 100's kR to a few 1000's kR). The brightness of the Io-controlled UV auroras is known to vary, due to the Jovian magnetic field tilt, which induces longitudinal variations, and due to the Io torus ever changing parameters (possibly due to Io's volcanic activity), which induce a temporal variation. As Io-controlled UV auroras have been monitored for a long time, the variation of their brightness is well-documented, and the typical amplitude of these variations has been established. However, on June, 7th 2012 an unusual event occurred in the plasma torus surrounding Io, which triggered its own UV emissions on Jupiter in a region mapping to Io's orbit. When Io reached that region, Io's auroral footprint disappeared, its brightness dimming by at least a factor of three to be below the background aurora brightness. Both the auroral event at such a low latitude and the Io footprint disappearance are events that have never been observed before and should be quite rare. However, the question of how the bright Io footprint becomes that weak remains. From a theoretical point-of-view, the Io-Jupiter interaction has been widely studied. In the 80's, it was shown that Alfvén waves are radiated from Io, carrying currents to Jupiter. In the late-2000's, studies showed that dispersive Alfvén waves were likely to cause the acceleration of the electrons powering the auroral emissions, although Io-scale Alfvén waves should be non-dispersive. More recently, a model was built which permits one to compute the ratio between dispersive and non-dispersive waves in the auroral region for satellite-magnetosphere interactions, and thus the brightness of the related aurorae. We use this model to investigate which variation of the interaction parameters could lead to the Io footprint disappearance. [less ▲]Detailed reference viewed: 40 (3 ULg)
How Cristiano Ronaldo performs his knuckleball?
; Darbois-Texier, Baptiste ; et al
Conference (2012, November 19)
A soccer ball kicked at very low spin can exhibit a zigzag trajectory. Along its straight path, the ball deviates laterally from about 0.2 m, that is to say one ball diameter. One zig zag happens as the ... [more ▼]
A soccer ball kicked at very low spin can exhibit a zigzag trajectory. Along its straight path, the ball deviates laterally from about 0.2 m, that is to say one ball diameter. One zig zag happens as the ball travelled about 15 m. As the deviation direction seems unpredictable, this effect is highly annoying for goalkeepers. That why Cristiano Ronaldo and many soccer players are looking for this phenomenon. Those trajectories called knuckleballs are also observed on volleyball and baseball. We study experimentally indoor knuckleballs for different balls varying from soccer balls to smooth spheres. We show that knuckle effect doesn't derive from ball deformations at foot impact or ball seams. Actually, aerodynamic lift forces on a smooth sphere are fluctuating and are responsible for knuckleballs. From this study, we deduce side force intensity exerted on smooth spheres and sport balls for typical game Reynolds number (Re∼10^4−10^6). Finally we discuss required conditions to observe a knuckleball on the sport field. [less ▲]Detailed reference viewed: 104 (1 ULg)
How Daphnia copes with excess carbon in its food
Darchambeau, François ; ;
in Oecologia (2003), 136(3), 336-346
Animals that maintain near homeostatic elemental ratios may get rid of excess ingested elements from their food in different ways. C regulation was studied in juveniles of Daphnia magna feeding on two ... [more ▼]
Animals that maintain near homeostatic elemental ratios may get rid of excess ingested elements from their food in different ways. C regulation was studied in juveniles of Daphnia magna feeding on two Selenastrum capricornutum cultures contrasting in P content (400 and 80 C:P atomic ratios). Both cultures were labelled with C-14 in order to measure Daphnia ingestion and assimilation rates. No significant difference in ingestion rates was observed between P-low and P-rich food, whereas the net assimilation of C-14 was higher in the treatment with P-rich algae. Some Daphnia were also homogeneously labelled over 5 days on radioactive algae to estimate respiration rates and excretion rates of dissolved organic C (DOC). The respiration rate for Daphnia fed with high C:P algae (38.7% of body C day(-1)) was significantly higher than for those feeding on low C:P algae (25.3% of body C day(-1)). The DOC excretion rate was also higher when animals were fed on P-low algae (13.4% of body C day(-1)) than on P-rich algae (5.7% of body C day(-1)) . When corrected for respiratory losses, total assimilation of C did not differ significantly between treatments (around 60% of body C day(-1)). Judging from these experiments, D. magna can maintain its stoichiometric balance when feeding on unbalanced diets (high C:P) primarily by disposing of excess dietary C via respiration and excretion of DOC. [less ▲]Detailed reference viewed: 19 (0 ULg)
How democracies deal with disasters. A comparison between the 3.11 disaster in Japan and the Katrina disaster in the U.S
Conference (2013, January 31)Detailed reference viewed: 25 (3 ULg)
How did endemic cyprinids and exotic european catfish move in a large river ecosystem?
; ; Ovidio, Michaël
Conference (2013, October 03)Detailed reference viewed: 29 (2 ULg)
How Discourse about Music makes ‘Music'. The case of American Experimental Music in the 20th Century
Conference (2016, November 19)Detailed reference viewed: 23 (1 ULg)
How do auditory verbal hallucinations in patients differ from those in nonpatients?
in Frontiers in Human Neuroscience (2012), 6Detailed reference viewed: 29 (2 ULg)
How do climate warming and plant species richness affect water use in experimental grasslands?
; ; et al
in Plant and Soil (2006), 288
Climate warming and plant species richness loss have been the subject of numerous experiments, but studies on their combined impact are lacking. Here we studied how both warming and species richness loss ... [more ▼]
Climate warming and plant species richness loss have been the subject of numerous experiments, but studies on their combined impact are lacking. Here we studied how both warming and species richness loss affect water use in grasslands, while identifying interactions between these global changes. Experimental ecosystems containing one, three or nine grassland species from three functional groups were grown in 12 sunlit, climate-controlled chambers (2.25 m(2) ground area) in Wilrijk, Belgium. Half of these chambers were exposed to ambient air temperatures (unheated), while the other half were warmed by 3 degrees C (heated). Equal amounts of water were added to heated and unheated communities, so that warming would imply drier soils if evapotranspiration (ET) was higher. After an initial ET increase in response to warming, stomatal regulation and lower above-ground productivity resulted in ET values comparable with those recorded in the unheated communities. As a result of the decreased biomass production, water use efficiency (WUE) was reduced by warming. Higher complementarity and the improved competitive success of water-efficient species in mixtures led to an increased WUE in multi-species communities as compared to monocultures, regardless of the induced warming. However, since the WUE of individual species was affected in different ways by higher temperatures, compositional changes in mixtures seem likely under climatic change due to shifts in competitiveness. In conclusion, while increased complementarity and selection of water-efficient species ensured more efficient water use in mixtures than monocultures, global warming will likely decrease this WUE, and this may be most pronounced in species-rich communities. [less ▲]Detailed reference viewed: 66 (5 ULg)
How do climate warming, plant species richness and plant functional group affect ammonia oxidizing bacteria diversity and function in experimental grasslands?
Malchair, Sandrine ; Carnol, Monique
Poster (2011, June 27)
How do climate warming, plant species richness and plant functional group affect ammonia oxidizing bacteria diversity and function in experimental grasslands? Malchair S. and Carnol M. Laboratory of Plant ... [more ▼]
How do climate warming, plant species richness and plant functional group affect ammonia oxidizing bacteria diversity and function in experimental grasslands? Malchair S. and Carnol M. Laboratory of Plant and Microbial Ecology Department of Sciences and Environmental Management University of Liege, Belgium Background: There is increasing evidence of diversity-function relationship and impact of warming for aboveground vegetation. Belowground effects of warming and plant species richness remain however largely unknown, although bacteria regulate many soil processes and some groups, like ammonia oxidizing bacteria (AOB) were, have been suggested highly sensitive to environmental stress. Objectives: 1. Investigation of the response of AOB richness, community composition and function to warming, plant species richness and functional group 2. Exploration of the AOB richness-function link Methods: Soil samples were taken at 2 depths from grassland model ecosystems with different species richness levels (1, 3, 9) and temperature treatments (ambient, ambient+3°C). Selected species belonged to 3 plant functional groups: forbs, legumes and grasses. AOB function: potential nitrification assay (shaken soil slurry method) AOB diversity: polymerase chain reaction followed by denaturing gradient gel electrophoresis (PCR-DGGE) Results: 1. All retrieved AOB sequences were Nitrosospira-like ones 2. Warming had no effect on AOB richness and function 3. Higher plant species richness leads to increased AOB richness and modified community structure. AOB function was increased only at lower depth under warming 4. No difference in AOB richness between the plant functional groups 5. AOB community structure was different and AOB function higher under legumes. 6. The AOB richness-function link was negative under legumes. Conclusions: 1. Plant species influenced AOB richness and community composition. Plant functional group seems to be more important that species richness. 2. Legumes may impact AOB diversity and function through ammonia availability. [less ▲]Detailed reference viewed: 59 (4 ULg)
How do CSR Standards Affect Stakeholder Management? An Integrative Framework Grounded in Pratice
El Abboubi, Manal ; Cornet, Annie
Conference (2010)Detailed reference viewed: 60 (12 ULg)