How does elicitor and antimicrobial fengycin interact with plasma membranes of sensitive cells ?
Nasir, Mehmet Nail ; ; Lins, Laurence et al
Conference (2012, April)
Fengycin is characterized by its strong antifungal and low hemolytic activities. It has also been recently demonstrated that it has plant elicitor properties and is also able to enhance the elicitors’ ... [more ▼]
Fengycin is characterized by its strong antifungal and low hemolytic activities. It has also been recently demonstrated that it has plant elicitor properties and is also able to enhance the elicitors’ activity of surfactin. The cell target of its biological activities is supposed to be plasma membrane. In spite of these interesting biological activities, fengycin has not been extensively investigated probably because of the difficulties related to its production. In a first time; we have characterized the interfacial properties of fengycin by tensiometry measurements and demonstrated that this surface activity was pH-dependent. In a second time; we have investigated the interactions of the lipopeptide with membrane lipids using model membranes such as Langmuir monolayers and multilammelar vesicles (MLVs). Our results indicate that the lipopeptide was able to penetrate into different lipid monolayers showing a preference for sterol-containing monolayers. In order to better understand the mechanism of the interactions of fengycin with membranes at the molecular level, MLVs with or without fengycin have been analyzed by spectroscopic techniques. We have shown that conformational changes of the lipopeptide occurred in the presence of lipids and they were more significant in the presence of sterol. Moreover, tyrosine residues of the lipopeptide seem to play an important role in these interactions. In conclusion, we have determined that the surface-active behavior as well as the conformation of fengycin depends on its environment. We have also showed that the lipopeptide does not interact with all class of lipids in the same way and presents a preference for sterols. The presence of key groups within peptide cycle has also been supposed for the biological activities of the lipopeptide. [less ▲]Detailed reference viewed: 145 (17 ULg)
How does engagement in reading predict digital reading proficiency among 15 year-olds?
Lafontaine, Dominique ; Monseur, Christian ; Baye, Ariane
Conference (2012, September)
In PISA 2009, 19 countries took part to an optional assessment of digital reading. In each country, a subsample of 15 year-olds was administered not only the paper and pencil PISA test, but also different ... [more ▼]
In PISA 2009, 19 countries took part to an optional assessment of digital reading. In each country, a subsample of 15 year-olds was administered not only the paper and pencil PISA test, but also different reading tasks online. The aim of our study is to investigate the relationships between engagement in reading, especially online reading practices, and digital reading proficiency of 15 year-olds in the 11 European countries which took part to this option (11 out of 19). [less ▲]Detailed reference viewed: 62 (5 ULg)
How does engagement in reading predict digital reading proficiency among 15 years-olds ?
Baye, Ariane ; Lafontaine, Dominique ; Monseur, Christian
Conference (2012, April 15)Detailed reference viewed: 9 (0 ULg)
How does gender socialisation influence teenagers' behaviors ? : Contribution of ISRD-2 and ISRD-3 to this question
Conference (2014, November 21)
In both gender groups, young people entering the spiral of violence negatively often react against personal insecurity, against a hostile and little promising environment. But those environments still ... [more ▼]
In both gender groups, young people entering the spiral of violence negatively often react against personal insecurity, against a hostile and little promising environment. But those environments still differ between girls and boys according to the sphere which remains the most valorized, 'suitable' for them (public and competitive sphere for the boys, family and emotional sphere for the girls). ISRD data allow to show links between, on one side, the production of not authorized and violent behaviors and, on the other side, gendered concrete life, gendered attitudes and values. The theory of the societal vulnerability (Walgrave, Vettenburg) and the theory of recognition (Honneth) are confirmed. [less ▲]Detailed reference viewed: 33 (2 ULg)
How does governmental versus private venture capital backing affect a firm's efficiency? Evidence from Belgium
; Hübner, Georges ;
in Journal of Business Venturing (in press)
We investigate the implications of venture capital (VC) investor type (government or private) on the operating efficiency of a sample of 515 Belgian portfolio firms up to 3 years after the investment. We ... [more ▼]
We investigate the implications of venture capital (VC) investor type (government or private) on the operating efficiency of a sample of 515 Belgian portfolio firms up to 3 years after the investment. We find that the government VC-backed firms display significant reductions in productivity. No significant differences in efficiency are found in firms backed by private VC compared with their non-VC-backed peers. Finally, significant reductions in efficiency exist in targets of government VC compared to their non-VC-backed peers. [less ▲]Detailed reference viewed: 25 (1 ULg)
How Does Pollen Chemistry Impact Development and Feeding Behaviour of Polylectic Bees?
; ; et al
in PLoS ONE (2014), 9(1), 9
Larvae and imagos of bees rely exclusively on floral rewards as a food source but host-plant range can vary greatly among bee species. While oligolectic species forage on pollen from a single family of ... [more ▼]
Larvae and imagos of bees rely exclusively on floral rewards as a food source but host-plant range can vary greatly among bee species. While oligolectic species forage on pollen from a single family of host plants, polylectic bees, such as bumblebees, collect pollen from many families of plants. These polylectic species contend with interspecific variability in essential nutrients of their host-plants but we have only a limited understanding of the way in which chemicals and chemical combinations influence bee development and feeding behaviour. In this paper, we investigated five different pollen diets (Calluna vulgaris, Cistus sp., Cytisus scoparius, Salix caprea and Sorbus aucuparia) to determine how their chemical content affected bumblebee colony development and pollen/syrup collection. Three compounds were used to characterise pollen content: polypeptides, amino acids and sterols. Several parameters were used to determine the impact of diet on micro-colonies: (i) Number and weight of larvae (total and mean weight of larvae), (ii) weight of pollen collected, (iii) pollen efficacy (total weight of larvae divided by weight of the pollen collected) and (iv) syrup collection. Our results show that pollen collection is similar regardless of chemical variation in pollen diet while syrup collection is variable. Micro-colonies fed on S. aucuparia and C. scoparius pollen produced larger larvae (i.e. better mates and winter survivors) and fed less on nectar compared to the other diets. Pollen from both of these species contains 24-methylenecholesterol and high concentrations of polypeptides/total amino acids. This pollen nutritional “theme” seems therefore to promote worker reproduction in B. terrestris micro-colonies and could be linked to high fitness for queenright colonies. As workers are able to selectively forage on pollen of high chemical quality, plants may be evolutionarily selected for their pollen content, which might attract and increase the degree of fidelity of generalist pollinators, such as bumblebees. [less ▲]Detailed reference viewed: 26 (6 ULg)
How does polytheism work?
Pirenne-Delforge, Vinciane ;
in Eidinow, Esther; Kindt, Julia (Eds.) Oxford Handbook of Ancient Greek Religion (in press)
Trying to describe polytheism is a difficult enterprise because the whole system can be seen as a complex structure, each element of which (a deity with its proper name) is both itself a complex set of ... [more ▼]
Trying to describe polytheism is a difficult enterprise because the whole system can be seen as a complex structure, each element of which (a deity with its proper name) is both itself a complex set of prerogatives, and at the same time, must be considered in concert with the other elements. After a brief historiographical overview, this paper focuses on the first aspect by using the notion of ‘network’ as a metaphor to refer to the complexity of the ancient Greek gods. It provides two case studies, of the Moirai and the goddess Hera. The paper concludes that polytheism can be described if one conceptualises the complexity of the gods—their unity and diversity—together at every level (Panhellenic and local, cult and myths, and so on). [less ▲]Detailed reference viewed: 39 (1 ULg)
How does the age of hoverfly females affect their reproduction?
; Verheggen, François ; Francis, Frédéric et al
Conference (2007)Detailed reference viewed: 9 (2 ULg)
How does the age of hoverfly females affect their reproduction?
; Verheggen, François ; Francis, Frédéric et al
in Communications in Agricultural and Applied Biological Sciences (2007), 72(3),Detailed reference viewed: 28 (5 ULg)
How does the efficacy of Protelos translate into patient benefits ?
in Osteoporosis International (2009, March), 20(Suppl.1), 178Detailed reference viewed: 28 (1 ULg)
How does the ocean surrounding the Greenland ice sheet impact its surface mass balance ?
; Watelet, Sylvain ; Fettweis, Xavier et al
Poster (2013, April)Detailed reference viewed: 25 (7 ULg)
How does the organizational context influence the Competitive Intelligence process among Walloon SMEs?
Master's dissertation (2012)
In this increasingly turbulent, global and competitive context, it becomes critical for companies to create and sustain a competitive advantage. Competitive Intelligence (CI), defined as “the process by ... [more ▼]
In this increasingly turbulent, global and competitive context, it becomes critical for companies to create and sustain a competitive advantage. Competitive Intelligence (CI), defined as “the process by which organizations gather information on competitors and the competitive environment [...]” (Wright, Eid & Fleisher, 2009, p.942), can contribute to do so by enabling managers to be aware of and respond to changes in their competitive environment. The CI process includes four steps: (a) planning and focus, (b) data collection, (c) data analysis and (d) communication. First, this paper assesses the level of deployment of CI among Walloon SMEs. Second, it examines the influence of context variables on the CI process. A questionnaire was distributed to 423 Walloon SMEs’ executives, of whom 81 answered. SMEs’ executives were surveyed about their companies’ CI practices as well as their perception of their company’s formal structure, employee involvement and organizational awareness. We found that Walloon SMEs are not very active to conduct CI effectively. Indeed, while Walloon SMEs have recognized that, theoretically, CI is a necessary activity for maintaining a competitive advantage, in practice, most of them do not have yet a well-established CI process in their company. Then, we established the influence of the context in which CI takes place on the success of the CI process. Specifically, we supported that better formal structure, employee involvement and organizational awareness improve the CI process. Finally, we examined the impact of two extra potential antecedents, namely the innovation orientation and the company’s size. We found that innovation-oriented companies tend to exploit CI more than followers. The results lead to several recommendations for SMEs. First, managers should be aware that CI is critical for their company’s survival since the context in which they operate is increasingly competitive. Second, businesses, especially those that are innovation-oriented, should note that an improvement in their formal infrastructure, organizational awareness and employee involvement processes could significantly enhance their CI efficiency. [less ▲]Detailed reference viewed: 139 (28 ULg)
How Does Your Formulation of Lesion-Induced States of Diminished Consciousness Fit with AIM? Do You Suppose That Brain Stem Damage Affects Activation (A) and Modulation (M)?
Charland-Verville, Vanessa ; Laureys, Steven
in J. Allan Hobson, Nicholas Tranquillo (Ed.) Dream Consciousness: A New Approach to the Brain and Its Mind (2014)
Allan Hobson’s AIM model (Hobson, 1998) is build according to three main dimensions. The first component, Activation, describes brain’s activation processes and is closely linked to the level of ... [more ▼]
Allan Hobson’s AIM model (Hobson, 1998) is build according to three main dimensions. The first component, Activation, describes brain’s activation processes and is closely linked to the level of consciousness. According to the model, the brain is highly active in wakefulness and REM sleep but will show much less activity during NREM sleep. The second component, Input/output gateway, controls the inhibition of external stimuli. When slowly falling asleep, the gateway shuts down and inhibits the external stimuli; the brain is no longer involved in processing external perceptions. Then the brain starts its oniric phase and the focus switches to internal inputs. Finally, the third dimension, Modulation, refers to the different ways of cognitive processing (executive functions), judgment, volition and memory. According to the model, those cognitive processes are lacking in REM sleep (i.e., the brain cannot keep a record of its conscious experience during dreaming as opposed to waking state) because of the changes between the aminergic system (norepinephrine and serotonin; dominant in waking but ineffective in REM sleep) and the cholinergic system (acetylcholine; unfettered in REM sleep). These three dimensions maintain a dynamic and reciprocal interaction over the sleep-wake cycle’s variations (wakefulness, NREM and REM sleep) and each of them can be expressed with lower or higher intensities depending on the level of consciousness. [less ▲]Detailed reference viewed: 16 (2 ULg)
How dynamical clustering triggers Maxwell's demon in microgravity
Opsomer, Eric ; Noirhomme, Martial ; Vandewalle, Nicolas et al
in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2013), 88
In microgravity, the gathering of granular material can be achieved by a dynamical clustering whose existence depends on the geometry of the cell that contains the particles and the energy that is ... [more ▼]
In microgravity, the gathering of granular material can be achieved by a dynamical clustering whose existence depends on the geometry of the cell that contains the particles and the energy that is injected into the system. By compartmentalizing the cell in several subcells of smaller volume, local clustering is triggered and the so formed dense regions act as stable traps. In this paper, molecular dynamics simulations were performed in order to reproduce the phenomenon and to analyze the formation and the stability of such traps. Depending on the total number N of particles present in the whole system, several clustering modes are encountered and a corresponding bifurcation diagram is presented. Moreover, an iterative model based on the measured particle flux F as well as a theoretical model giving the asymptotical steady states are used to validate our results. The obtained results are promising and can provide ways to manipulate grains in microgravity. [less ▲]Detailed reference viewed: 22 (8 ULg)
How ergodic is the Fragmentation of the Pyridine Cation ? A Maximum Entropy Ananlysis
; Locht, Robert ; Lorquet, Andrée et al
in Anton, J.; Cederquist, H.; Larsson, M. (Eds.) et al 23rd International Conference on the Photonic, Electronic and Atomic Collisions: Book of Abstracts. (2003)
The experimental KER and the statistical distributions are compared by the Maximum Entropy Method. An Ergodicity Index F(E) is defined to measure the phase space sampling efficiency. This is applied to ... [more ▼]
The experimental KER and the statistical distributions are compared by the Maximum Entropy Method. An Ergodicity Index F(E) is defined to measure the phase space sampling efficiency. This is applied to the KERD of C4H4+ cation produced by the C5H5N+ -> HCN+C4H4+ fragmentation path. In this particular case the F(E) is found to decrease steadily with increasing internal energy. [less ▲]Detailed reference viewed: 31 (6 ULg)
How ergodic is the fragmentation of the pyridine cation? A maximum entropy analysis
; Locht, Robert ; Lorquet, Andrée et al
in International Journal of Mass Spectrometry (2003), 228(2-3), 389-402
The kinetic energy released to the C4H4+ and HCN fragments produced by the dissociation of the pyridine ion has been determined by a retarding field technique up to an internal energy of 4eV above the ... [more ▼]
The kinetic energy released to the C4H4+ and HCN fragments produced by the dissociation of the pyridine ion has been determined by a retarding field technique up to an internal energy of 4eV above the reaction threshold. This extends our previous study limited to the metastable domain [Int. J. Mass Spectrom. Ion Process. 185/186/187 (1999) 155]. Retarding potential curves resulting from dissociative photoionization using the He(I), Ne(I), and Ar(II) resonance lines have been analyzed by the maximum entropy method. The comparison between the experimentally measured curves and those calculated for the prior (i.e., most statistical) situation reveals the existence of dynamical constraints that prevent phase space from being fully explored. The "ergodicity index" F(E) that measures the efficiency of phase space sampling as a function of the internal energy E of the molecular ion is found to decrease steadily as a function of E and to level off at a value of about 50% when E greater than or equal to 2.5 eV At these high internal energies where phase space exploration no longer decreases, spontaneous intramolecular vibrational energy redistribution (i.e., resulting from the anharmonicity of the molecular vibrations) is thought to contribute to internal energy randomization to a limited extent only. When the lifetime is short, phase space exploration is believed to result instead from the relaxation of the electronic energy via a cascade of non-radiative transitions, which leads to a great diversity of initial conditions, and thus, contributes to statisticity. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]Detailed reference viewed: 34 (2 ULg)
How eye movements and expertise can explain memory of visual items of central or marginal interest
Blavier, Adelaïde ; Nyssen, Anne-Sophie
in Journal of Vision (2009)
In complex scene, memory for central interest items is better than memory for marginal interest items and this difference remains stable independently of the scene presentation duration (Melcher, 2006 ... [more ▼]
In complex scene, memory for central interest items is better than memory for marginal interest items and this difference remains stable independently of the scene presentation duration (Melcher, 2006). However, without eye movement recording, it is not possible to know whether central interest items are better remembered because they are more fixated or because they are more meaningful. In order to answer this question, we analysed the memory of complex scenes (paintings) according to the eye movements and subjects’ expertise. 15 novice subjects and 15 art historians (experts) were asked to look at 6 paintings that were separately and randomly presented for 10 seconds. After each painting presentation, subjects were asked questions about painting knowledge (author’s name, painting’s name) in order to evaluate their painting knowledge and about pictorial details of 3 categories: details of central or marginal interest and background information. If the expert and novice groups significantly differed concerning the knowledge they had about all paintings, the accuracy of answers about the painting details did not differ between both groups. Moreover, we showed novice’s answers were more accurate when they looked longer at the asked detail and when this detail was watched early on in the presentation while in the expert group, the accuracy of the answer was not influenced by the duration and moment they watched the asked detail. These findings suggest experts have some wrong representations which are not influenced by eye movements contrary to novices whom memory accuracy is influenced by their eye movements. [less ▲]Detailed reference viewed: 85 (8 ULg)
How far and how fast do bryophytes travel at the landscape scale?
Hutsemekers, Virginie ; Dopagne, Claude ; Vanderpoorten, Alain
in Diversity & Distributions (2008), 14(3), 483-492
Dispersal ability is a factor of prime importance to explain biotic distributions. Yet, it is extremely difficult to measure directly. In this study, we take advantage of the natural experimental design ... [more ▼]
Dispersal ability is a factor of prime importance to explain biotic distributions. Yet, it is extremely difficult to measure directly. In this study, we take advantage of the natural experimental design of slag heap colonization in Belgium to document the timing and range of dispersal of bryophytes at the landscape scale. On the basis of a species atlas with a 4 × 4 km grid, the minimum distance separating species found on 52 slag heaps from potential source populations was determined. Minimum dispersal rates were inferred by coupling the information on minimum distance between slag heap and source populations with time since colonization. The number of species per slag heap is significantly correlated with time since colonization and area size. The frequency distribution of the longest dispersal events is highly skewed, with 44% of the species recruited within the nearest 6 km. In the remaining 56% of the species, recruitments from source populations located within a range of at least 6–86 km occurred within a period of less than 50 years. The majority of the species that are not recruited within the nearest vicinity of the slag heaps, including rare species at the regional scale, occur on slag heaps that have been colonized for 25–50 years. Most recently colonized slag heaps are indeed characterized by 'fugitive', weedy species, whereas slag heaps that have been colonized for > 50 years tend to accumulate perennial species with a 'stayer' life strategy. These observations suggest that rare species may display the dispersal ability to travel across the landscape, but are subsequently limited by their ability to establish a viable community because of more competitive neighbours. Rare species therefore tend to accumulate at intermediate colonization stages, which represent a trade-off between an increasing probability of colonization with time and a decreasing probability of establishment due to competition. [less ▲]Detailed reference viewed: 49 (5 ULg)
How fertilizer and soil nitrogen are distributed into winter wheat plant
; Destain, Jean-Pierre ; Bodson, Bernard et al
(2007, September 16)Detailed reference viewed: 23 (0 ULg)
How good are we at extracting personal information from voices?
Dehon, Hedwige ;
Poster (2009, June)Detailed reference viewed: 4 (0 ULg)