References of "2009"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailCharacterization of spatio-temporal organization of slow waves during human NREM sleep
Schrouff, Jessica ULg; Leclercq, Yves ULg; Foret, Ariane et al

Poster (2009, December 14)

Sleep is a behavior commonly observed in a large number of animal species. However, neuroscientists still poorly understand the meaning of this loss of consciousness absolutely needed for life. In the ... [more ▼]

Sleep is a behavior commonly observed in a large number of animal species. However, neuroscientists still poorly understand the meaning of this loss of consciousness absolutely needed for life. In the present work, we established different methods to characterize the Slow Wave Sleep most recognizable patterns: the Slow Waves (SWs). Since the anatomical structure of white matter tracts that connect various brain regions is not random and thus must constraint the propagation of waves (Hagmann et al., 2008), our basic hypothesis was that large white matter bundles would bias the propagation of SW along specific patterns, which could be identified in homogeneous clusters of waves. To investigate our hypothesis, SWs were detected automatically on the three first periods of SWS using an algorithm based on Massimini et al., 2004. They were then clustered using a two steps procedure involving a hierarchical clustering based on delay maps and a k-means clustering based on the SWs potential in a given time interval around the maximum power of the SW negative peak. To compute the relevance of the final clusters, a mathematical criterion was implemented as well as a visual check. Results of the multisubjects study showed that only bad quality and small clusters could be obtained, suggesting that there is no particular organization of SWs across the night and inforcing the hypothesis that SWs are local phenomena, each one decreasing the homeostatic pressure in only one specific area. [less ▲]

Detailed reference viewed: 17 (4 ULg)
Full Text
See detailPrediction of genetic interactions in yeast using machine learning
Schrynemackers, Marie ULg

Conference (2009, December 14)

Detailed reference viewed: 14 (5 ULg)
See detailThe Spatial Morphology of Equatorial Electron Beams Near Io
Jacobsen, S.; Saur, J. S.; Neubauer, F. M. et al

Conference (2009, December 14)

The Galileo spacecraft observed energetic field-aligned electron beams very close to Io during several flybys. We apply a three-dimensional magnetohydrodynamic (MHD) model of the far-field Io-Jupiter ... [more ▼]

The Galileo spacecraft observed energetic field-aligned electron beams very close to Io during several flybys. We apply a three-dimensional magnetohydrodynamic (MHD) model of the far-field Io-Jupiter interaction to simulate for the first time the location and spatial shape of field-aligned electron beams. Io continuously generates MHD waves by disturbing the Jovian magnetoplasma. Currents carried by Alfvén waves propagate predominantly along the magnetic field lines. As the number of charge carriers decreases along the travelpath, electrons are accelerated towards Jupiter. These energetic electrons precipitate into the Jovian ionosphere, visible as prominent Io footprint (IFP) emission. Electrons are also accelerated towards Io and form the equatorial beams observed by the Galileo spacecraft. Unlike the beam formation, the position and spatial structure of these beams has not been addressed in detail before. We use a 3D MHD model with initial conditions corresponding to the individual Galileo flyby and determine the spatial morphology of the beams in Io's orbital plane. Our results are in good agreement with the Galileo observations. We find that the ratio of the one-way traveltime of the Alfvén wave from Io to Jupiter and the convection time of the plasma past the obstacle controls the location of the beams. This leads to the conclusion that at other satellites with other plasma environments, e.g. Ganymede, Callisto, Europa and Enceladus, the electron beams might not be close to the satellite, but can be shifted significantly downstream along its plasma wake. Thus, the future search for field-aligned electron populations near a satellite should be further extended to the wake region. [less ▲]

Detailed reference viewed: 18 (2 ULg)
See detailMicrobial diversity and activity in temperate forest and grassland ecosystems
Malchair, Sandrine ULg

Doctoral thesis (2009)

Ecosystems currently face widespread biodiversity losses and other environmental disturbances, such as climate warming, related to increased anthropogenic activities. Within this context, scientists ... [more ▼]

Ecosystems currently face widespread biodiversity losses and other environmental disturbances, such as climate warming, related to increased anthropogenic activities. Within this context, scientists consider the effects of such changes on the biodiversity, and hence on the activity, of soil microorganisms. Indeed, soil microorganisms mediate a wide range of soil processes. Currently, knowledge on soil microbial diversity is still limited, partially due to technical limitations. The advent of molecular-based analyses now allows studying the soil microbial diversity. These advances in the study of soil microbial communities have lead to a growing evidence of the critical role played by the microbial community in ecosystem functioning. This relationship is supposed to be relevant for narrow processes, regulated by a restricted group of microorganisms, such as the nitrification process. This PhD thesis aimed at studying ammonia oxidizing bacteria (AOB) community structure and richness as an integrated part of soil functioning. This research aimed at investigating the effect of aboveground plant diversity on ammonia oxidizing bacteria diversity and function in forest and grassland soils with focus on the influence of (a) functional group identity of grassland plants (legumes, grasses, forbs), (b) grassland plant species richness and (c) tree species, on AOB diversity and function. Another objective of this research was to study the effect of a 3°C increase in air temperature on AOB diversity and function. The link between AOB diversity and function (potential nitrification) is also investigated. For grassland ecosystems, a microcosm experiment was realized. An experimental platform containing 288 assembled grassland communities was established in Wilrijk (Belgium). Grassland species were grown in 12 sunlit, climate controlled chambers. Each chamber contained 24 communities of variable species richness (S) (9 S=1, 9 S=3 and 6 S=9).The grassland species belonged to three functional groups: three species of each grasses (Dactylis glomerata L., Festuca arundinacea SCHREB., Lolium perenne L.), forbs (non-N-fixing dicots; Bellis perennis L., Rumex acetosa L., Plantagolanceolata L.), and legumes (N-fixing dicots; Trifolium repens L., Medicago sativa L., Lotus corniculatus L.). Half of these chambers were exposed to ambient temperature and the other half were exposed to (ambient +3°C) temperature. One ambient and one (ambient+3°C) chambers were destructively harvested 4, 16 and 28 months after the start of the experiment. The influence of plant functional group identity on the nitrification process and on AOB community structure and richness (AOB diversity) was assessed in soils collected from the first two destructive amplings (chapter 2). The effect of plant species richness on AOB diversity and function was considered for soils sampled after 16 and 28 months (chapter 3). AOB function was determined by potential nitrification. AOB community structure and richness were assessed by polymerase chain reaction followed by denaturing gradient gel electrophoresis (DGGE) and sequencing of excised DGGE bands. I found that functional group identity can affect AOB community structure. In particular, the presence of legumes, both in monoculture or in mixture with forbs and grasses, lead to AOB community composition changes towards AOB clusters tolerating higher ammonium concentrations. This change in AOB community structure was only linked to increased potential nitrification under monocultures of legumes, when ammonium was supposed to be not limiting. This study revealed that physiological attributes of AOB and resource availability may be important factors in controlling the nitrification process. This research showed that the impact of plant species richness on the nitrification process could be mediated by the interactions between plants and AOB, through competition for substrate. A 3°C increase in air temperature did not affect AOB community structure, richness or function. In forest ecosystems, we studied the effect of tree species in forest sites located in Belgian and in the Grand-Duchy of Luxembourg covered each by several deciduous or coniferous tree species (Fagus sylvatica L., Quercus petraea (Mattuschka) Lieblein, Picea abies (L.) Karst, Pseudotsuga menziesii (Mirbel) Franco). We investigated the influence of these tree species on microbial processes (chapter 5) related to C and N cycling, particularly with emphasize on the nitrification process and on the diversity of AOB (chapter 6). The results showed that the effect of tree species on net N mineralization was likely to be mediated through their effect on soil microbial biomass, reflecting their influence on organic matter content and carbon availability. Influence of tree species on nitrification (potential and relative) might be related to the presence of ground vegetation through its influence on soil ammonium and labile C availability. AOB community structure was more site-specific than tree specific. However, within sites, AOB community structure under broadleaved trees differed from the one under coniferous trees. The effect on tree species on AOB was likely to be driven by the influence of tree species on net N mineralization, which regulates the substrate availability for AOB. The results also demonstrated that the relationship between AOB diversity and function might be related both to AOB abundance and AOB community structure and richness. This thesis showed no clear relationship between AOB community structure or richness and AOB function. However, we revealed that aboveground grassland plant richness, grassland plant functional groups and tree species influence AOB community structure and richness. [less ▲]

Detailed reference viewed: 125 (6 ULg)
Full Text
See detailResistencia desquiciada en El ejército iluminado de David Toscana
Vanden Berghe, Kristine ULg

Conference (2009, December 13)

Detailed reference viewed: 32 (4 ULg)
Full Text
Peer Reviewed
See detailLiposomes loaded with diglyceride esters of methotrexate and melphalan: studies on stability and hemocompatibility
Kuznetsova, N; Kandyba, A; Bovin, N et al

in Proceedings of the International Liposome Society 2009 Meeting (2009, December 12)

Detailed reference viewed: 14 (0 ULg)
See detailVoltaire et l’Optimisme. Candide aujourd’hui
Tilkin, Françoise ULg

Conference given outside the academic context (2009)

Detailed reference viewed: 28 (2 ULg)
See detailEvolution des traditions culturelles dans la vallée du moyen Euphrate de la fin du Bronze ancien au début du Bronze moyen
Colonna d'Istria, Laurent ULg

Doctoral thesis (2009)

The valley of the Middle Euphrates, hyphen between South Mesopotamia and Western Syria, was ruled by a šakkanakku lived in Mari (Tell Hariri, Syria) during the end of the third millennium and early second ... [more ▼]

The valley of the Middle Euphrates, hyphen between South Mesopotamia and Western Syria, was ruled by a šakkanakku lived in Mari (Tell Hariri, Syria) during the end of the third millennium and early second millennium. This time period named "šakkanakku-period" is particularly studied since twenty years An overview of archaeological and historical data from the Middle Euphrates valley during the time of šakkanakku suggest that the kingdom of Mari during that time has established itself as a power independent and prosperous until the 19th century (end of the time of šakkanakku) where data are less explicit historically. The new text data from Mari, and Terqa (north of Mari), of the most dated from the end of šakkanakku-period, shows continuance and ruptures between the end of šakkanakku-period and the next period ("Amorite-period"). This continuance and ruptures are examined in several areas such as language, "scribal tradition" or in the legal tradition. The dialect of this text (19th century) shows that linguistic tradition is deeply rooted in the universe Syria. After the advent of the Amorite Yahdun-Lim who ended the time of the šakkanakku the Syrian characteristics in the dialect remains present, but it is less important because a reform of writing modeled on southern Mesopotamia (Iraq current), probably due to the preponderance of political Ešnunna during the end of the 19th century. Finally, this new text has also allowed dealing the historical interaction of the last šakkanakku Mari with condottieri Amorite whose father Yahdun-Lim in the 19th century. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailTree based ensemble models regularization by convex optimization
Cornélusse, Bertrand ULg; Geurts, Pierre ULg; Wehenkel, Louis ULg

Conference (2009, December 12)

Tree based ensemble methods can be seen as a way to learn a kernel from a sample of input-output pairs. This paper proposes a regularization framework to incorporate non-standard information not used in ... [more ▼]

Tree based ensemble methods can be seen as a way to learn a kernel from a sample of input-output pairs. This paper proposes a regularization framework to incorporate non-standard information not used in the kernel learning algorithm, so as to take advantage of incomplete information about output values and/or of some prior information about the problem at hand. To this end a generic convex optimization problem is formulated which is first customized into a manifold regularization approach for semi-supervised learning, then as a way to exploit censored output values, and finally as a generic way to exploit prior information about the problem. [less ▲]

Detailed reference viewed: 140 (45 ULg)
Full Text
See detailNADH pathway and H2 production in Chlamydomonas reinhardtii
Lecler, Renaud ULg

Scientific conference (2009, December 12)

Detailed reference viewed: 10 (5 ULg)
Peer Reviewed
See detailComparative study of Murid gammaherpesvirus 4 infection in mice and in its natural host, the bank voles.
François, Sylvie ULg; Vidick, Sarah ULg; Koteja, Pawel et al

Poster (2009, December 11)

Gammaherpesviruses are the archetypes of persistent viruses that have been identified in a range of animals from mice to man. They are host-range specific and establish persistent, productive infections ... [more ▼]

Gammaherpesviruses are the archetypes of persistent viruses that have been identified in a range of animals from mice to man. They are host-range specific and establish persistent, productive infections of immunocompetent hosts. Thus, infected individuals simultaneously both elicit antiviral protective immune response and secrete infectious virions. The best studied gammaherpesviruses are Human herpesvirus 4 and Human herpesvirus 8. As these viruses have no well-established in vivo infection model, related animal gammaherpesviruses are an important source of information. We are studying Murid herpesvirus 4 (MuHV-4), a virus that has originally been isolated from bank voles (Myodes glareolus). Although MuHV-4 has not been isolated from house mice (Mus musculus), infection of inbred laboratory mouse strains is commonly accepted as a good model for studying gammaherpesviruses in vivo. It has however never been possible to monitor viral reexcretion and virus transmission in this species suggesting that this model could be imperfect. In this study, we therefore characterized MuHV-4 infection in its natural host, the bank voles, through classical virological methods but also through global luciferase imaging for an anatomical complete view of the infection. Results obtained show that, after intra-nasal infection, the natural route of infection is similar in mice and voles. Following nasal productive infection, the virus spreads to the lung where the infection is accompanied by massive cellular infiltrates. By opposition to extensive viral replication observed in mice, the different analyses indicated that the viral replication was ~1000 fold lower in bank voles. This lower replication did however not affect colonization of latency sites in superficial cervical lymph nodes and spleen as measured by real-time PCR quantification of viral genomes in these organs. In conclusion, this study revealed that MuHV-4 can experimentally infect bank voles, the supposed natural host, but with a lower replicative power. As, gammaherpesvirus epidemiology indicates that transmission correlates with the latent load, our results suggest that gammaherpesviruses may have evolved to infect their hosts without extensive lytic spread. In the future, establishment of experimental transmission in a population of Myodes glareolus should help us to better understand mechanisms used by gammaherpesviruses to evade immune response. [less ▲]

Detailed reference viewed: 16 (6 ULg)