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: 37 (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: 45 (0 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: 18 (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: 23 (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: 27 (2 ULg)
How do auditory verbal hallucinations in patients differ from those in nonpatients?
in Frontiers in Human Neuroscience (2012), 6Detailed reference viewed: 23 (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: 63 (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: 53 (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: 50 (8 ULg)
How do cumulative live birth rates and cumulative multiple live birth rates over complete courses of assisted reproductive technology treatment per woman compare among registries?
; ; et al
in Human Reproduction (2015)Detailed reference viewed: 6 (1 ULg)
How do education systems care of low engaged readers ? Institutional and socioeconomic factors influencing the reading engagement
Baye, Ariane ; Monseur, Christian ; Lafontaine, Dominique
Conference (2009, September)Detailed reference viewed: 10 (2 ULg)
How do Foreigners and Immigrants in Belgium View the Legal System ?
Martiniello, Marco ; ; et al
in Journal of Immigration, Asylum and Nationality Law (2007), 21(4), 263-283Detailed reference viewed: 69 (5 ULg)
How do harpacticoid copepods colonize detrital seagrass leaves?
Mascart, Thibaud ; ; Lepoint, Gilles et al
in Marine Biology (2015), 162(5), 929-943
An experiment was carried out investigating the colonization ability and specific pattern of copepods towards a provisional benthic habitat. Since copepods are known to disperse passively and actively ... [more ▼]
An experiment was carried out investigating the colonization ability and specific pattern of copepods towards a provisional benthic habitat. Since copepods are known to disperse passively and actively, the experiment aimed to investigate the pool of colonizers of macrophytodetritus and the species-specific active colonization pathways. The experiment was performed in a Mediterranean seagrass Posidonia oceanica meadow on defaunated macrophytodetritus accumulations (mainly dead seagrass leaves) for two time intervals (24 h and 96 h). Active colonization by copepods, independently of their adjacent potential source pool habitat (bare sandy sediments, P. oceanica canopy, water column and macrophytodetritus) occurred within 24 h. Natural densities (as in the control treatments) were only reached by active colonization through the water column. Both neither diversities nor species composition of natural macrophytodetritus were ever reached by one single migratory pathway, therefore only a combination of interstitial migration and water column migration can explain the species occurrence under natural condition. Moreover, every potential adjacent source pool habitat, contributed species to the newly colonized macrophytodetritus. However, the main colonizers were mostly species with good swimming capabilities. The diverse pool of species present in the newly colonized macrophytodetritus underlines the complex communities and dispersion capabilities of copepods. Hence, macrophytodetritus possesses the potential ability to be a colonizer source pool for every adjacent habitat and thus behaves as a copepod hub for the entire seagrass ecosystem. [less ▲]Detailed reference viewed: 33 (8 ULg)
How do ice sheets impact on climate sensitivity and ocean meridional overturning circulation?
; ; et al
Poster (2008, April 17)Detailed reference viewed: 14 (0 ULg)
How Do Information and Experience Play a Role in the Discovery of Entrepreneurial Opportunities? The Case of Latin-American Immigrants in Barcelona
Aliaga Isla, Rocio
in Latin American Business Review (2012)
This study contributes to expand the knowledge available on immigrant entrepreneurship. Consistent with the notion of entrepreneurship as a process, a qualitative explora- tion of information and ... [more ▼]
This study contributes to expand the knowledge available on immigrant entrepreneurship. Consistent with the notion of entrepreneurship as a process, a qualitative explora- tion of information and experiences acquired by immigrants in the catering sector was performed to ascertain their role in dis- covering entrepreneurial opportunities. Our sample consisted of four cases of Latin American immigrants. The findings showed that the discovery process is based on the interrelation estab- lished between information per se and the experiences acquired throughout the migration periods. The knowledge acquired in their home country constituted the bases for our study, while that acquired in the host country is supplementary as it fine-tunes, expands, and influences the discovery process. Furthermore, findings revealed that immigrants trust information coming from their social environment and consider it sufficient to take a decision to set up a business. Finally, this study suggests further lines of inquiry. [less ▲]Detailed reference viewed: 3 (0 ULg)