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See detailCharge Migration in the Bifunctional PENNA Cation Induced and Probed by Ultrafast Ionization: A Dynamical Study.
Mignolet, Benoît ULg; Levine, R. D.; Remacle, Françoise ULg

in Journal of Physics : B Atomic Molecular & Optical Physics (2014), 47

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See detailWorkshop on Pitch Analysis for Singing
Larrouy, Pauline ULg

Conference (2014, June 28)

Two methods are actually used in order to determine if a vocal performance is “in tune” or “out of tune”, to better understand the causes of poor-pitch singing or to evaluate the quality/progression of a ... [more ▼]

Two methods are actually used in order to determine if a vocal performance is “in tune” or “out of tune”, to better understand the causes of poor-pitch singing or to evaluate the quality/progression of a singer. The "subjective" method makes use of judges whereas the "objective" method uses computer tools to perform pitch analysis and to estimate the accuracy of sung performances. While the first method allows a rapid assessment, it lacks precision, which explains that the “objective” method seems currently preferred. However, several computer tools are available and each laboratory has its preference. In addition, the analytical procedure will depend on the purpose and data of the study. This workshop aims to provide an overview of the tools available and to discuss the advantages and limitations of existing methods. [less ▲]

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See detailPitch fluctuations in accurate and inaccurate singers: are they the same?
Larrouy, Pauline ULg; Pfordresher, Peter Q

Conference (2014, June 28)

The research presented here attempts to explore the fine-control of pitch during singing among accurate occasional singers and individuals whose singing reflects a Vocal Pitch Imitation Deficit (VPID ... [more ▼]

The research presented here attempts to explore the fine-control of pitch during singing among accurate occasional singers and individuals whose singing reflects a Vocal Pitch Imitation Deficit (VPID). Most past research addresses individual differences at the level of entire sung notes or melodies. By contrast, in the present research we addressed whether VPID singers differ from accurate singers with respect to the way to reach, maintain, and stop a sung tone. In order to describe the “scoops” at the beginning and ends of tone, as well as other forms of instability, we adapted the model of Large et al. (2002), originally designed to model entrainment of timing during synchronization. This model was applied to 1461 notes performed by 12 VPID and 17 accurate singers from the database of Pfordresher and Mantell (2014). Finally, the parameter values across the VPID and accurate singers were compared. The results showed that the model fits tones performed by accurate and VPID singers similarly well. As expected, the median pitch across the entire sung note deviated from the target to imitate for VPID singers; at the same time, the proportion of these deviations that were overshoots (“sharp”) versus undershoots (“flat”) were the same for VPID and accurate singers (2/3rd under and 1/3rd above). Thus accurate and VPID singers differ in the magnitude but not the type of overall deviation they exhibit. Whereas no difference occurred between the singers regarding the direction of the scoop (up or down) at the start and the end of the tone, the amplitude of the scoops was significantly different between VPID and accurate singers. The present study highlights the difficulty of VPID singers to reach and stop a sung tone, which supports the hypothesis of a fine motor control deficit in this population. Furthermore, the pitch fluctuations described by the model would have to be investigated in research on pitch accuracy perception. [less ▲]

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See detailLe questionnaire en recherche !
Pétré, Benoît ULg; Guillaume, Michèle ULg

Conference (2014, June 28)

Les pratiques médicales et paramédicales doivent prendre appui aujourd’hui sur les données dites probantes. Autrement dit, les données issues de la recherche guident l’action des professionnels de santé ... [more ▼]

Les pratiques médicales et paramédicales doivent prendre appui aujourd’hui sur les données dites probantes. Autrement dit, les données issues de la recherche guident l’action des professionnels de santé! La qualité des résultats attendus au terme d’un processus de recherche dépend profondément de la qualité de l’outil de collecte des données utilisé. Parmi les outils disponibles, le questionnaire est certainement celui le plus utilisé dans le domaine de la recherche médicale et paramédicale. Si la conception d’un questionnaire parait simple aux premiers abords, une lecture plus fine des principes qui sous-tendent la mesure (fidélité, validité, objectivité) rend compte des difficultés rencontrées pour développer un outil de qualité. Après avoir resitué le questionnaire dans le processus plus général de la recherche, les étapes de construction du questionnaire seront précisées et les qualités de l’outil seront discutées. Cette présentation permettra la mise en lumière des avantages et des limites inhérentes au questionnaire. Il sera démontré que nul questionnaire n’est parfait et que les inférences et les interprétations qui peuvent être tirées des informations recueillies à partir de cet outil, doivent être réalisées avec précaution. [less ▲]

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See detailLes botanistes verviétois au XIXème siècle
Genin, Vincent ULg

Conference (2014, June 28)

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See detailPopulation ecology of coastal bottlenose dolphins (Tursiops truncatus) in Northern Patagonia Argentina
Vermeulen, Els ULg

Doctoral thesis (2014)

The population ecology of bottlenose dolphins (Tursiops truncatus) was assessed between 2006 and 2011 in Northern Patagonia, Argentina. Over these years, 356 systematic photo-identification surveys were ... [more ▼]

The population ecology of bottlenose dolphins (Tursiops truncatus) was assessed between 2006 and 2011 in Northern Patagonia, Argentina. Over these years, 356 systematic photo-identification surveys were conducted in Bahía San Antonio, of which 227 were land-based and 129 were conducted from a small outboard-powered rigid-hull inflatable boat. In total, 1472 h was spend searching for dolphins, and resulted in 215 h of observation of 415 dolphin groups. Photo-identification data resulted in the identification of 67 individual dolphins. Based on mark-recapture analysis, total abundance had a maximum corrected estimate of 83 (95%CI = 46 - 152) individuals. Adult survival rates varied between 0.97 (SE = 0.04) and 0.99 (SE = 0.01). Average calving interval of the 14 reproducing females equalled 3.5 ± 1.0 years. This results in 3.5 births/year in the entire population and a minimum annual birth rate of 4.2%. However, data suggest that calves may have been born and lost before being documented, underestimating birth rate, calf mortality and possibly the number of reproductive females. Either way, the recruitment rate of calves appears to be insufficient to compensate the overall mortality in the population. Additional data further indicated the genetic isolation and extremely low genetic diversity within this community, thus indicating this community of bottlenose dolphins is highly vulnerable and at risk. Association patterns within the studied community were relatively strong (HWI 0.30 ± 0.08), re-indicating the small size of the population. Nonetheless, the fluctuation in prey density and availability appeared to be the most important factor determining their fission-fusion dynamics. It appears that a combination of aspects inherent to the species and this habitat, such as low cost of locomotion, low predation pressure and food predictability, has helped reduce the costs of fission in response to intraspecific competition. Behavioural data indicated that Bahía San Antonio is mainly used to rest and forage, with a marked diurnal and seasonal pattern in their activity. Furthermore, dolphins appeared to show a preference for the shallower waters inside their core area; they moved in and out with the tide to remain in the intertidal zone as much as possible. The observed variation in foraging activity and spatial distribution is suggested to be driven by a seasonal and locally predictable variation in prey density and availability. Most of the identified dolphins showed a yearlong residency and long term site-fidelity to Bahía San Antonio, suggesting it is the core area within the larger home range of this community. Furthermore, based on the frequent presence of calves and high residency of reproductive females, this protected coastal environment appears to provide shelter for nursing calves. Many individuals of this community ranged along the entire northern coastline of the San Matías Gulf, up to the Río Negro Estuary (approx. 200 km). Further to the north, in the southern part of the Province of Buenos Aires, a neighbouring community of bottlenose dolphins was shown to exist. Both communities are largely isolated from each other, and the environmental discontinuities between two adjacent oceanic regimes in which these communities live are hypothesised to promote their co-existence. Additionally, four individuals from another community, originating from the more southern Province of Chubut, are known to reside in Bahía San Antonio. These individuals are genetically differentiated from all other individuals in the area, clearly shown in their distinct morphology. The apparent fine-scale population structure of bottlenose dolphins over the relative small geographical distances in Argentina has conservation implications and indicates the need for further detailed research. Currently, the populations of bottlenose dolphins in the Provinces of Buenos Aires and Chubut are reported to have nearly vanished. However, this disappearance has been largely ignored in the past 40 years resulting in the studied communities to be one of the last ones remaining in the country. It seems that the coastal lifestyle and site-fidelity of coastal bottlenose dolphins, and the belief of the species to be common, may have obfuscated the need for more extensive research and conservation efforts in Argentina in former years. Local declines of common species are easily overlooked when establishing priorities for conservation, and Argentina is not a unique case. An ever-increasing number of coastal bottlenose dolphin populations are reported to be vulnerable or declining worldwide. This study provides insight into how the failure to recognise local population declines can threaten the regional status of a common species like the bottlenose dolphin. Continued research and urgent conservation measures are therefore strongly recommended to prevent the disappearance of the bottlenose dolphin from the coasts of this South American country. [less ▲]

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See detail"La leçon d'Anatomie nerveuse"
Bonnet, Pierre ULg

Conference (2014, June 27)

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See detailAgisme et jeunisme: Conséquences trop méconnues par les cliniciens et les chercheurs
Adam, Stéphane ULg

Scientific conference (2014, June 26)

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See detailRasa3 Controls Megakaryocyte Rap1 Activation, Integrin Signaling and Differentiation into Proplatelet
Molina Ortiz, Patricia ULg; Polizzi, Séléna; Ramery, Eve ULg et al

in PLoS Genetics (2014), 10(6), 1004420

Rasa3 is a GTPase activating protein of the GAP1 family which targets Ras and Rap1. Ubiquitous Rasa3 catalytic inactivation in mouse results in early embryonic lethality. Here, we show that Rasa3 ... [more ▼]

Rasa3 is a GTPase activating protein of the GAP1 family which targets Ras and Rap1. Ubiquitous Rasa3 catalytic inactivation in mouse results in early embryonic lethality. Here, we show that Rasa3 catalytic inactivation in mouse hematopoietic cells results in a lethal syndrome characterized by severe defects during megakaryopoiesis, thrombocytopenia and a predisposition to develop preleukemia. The main objective of this study was to define the cellular and the molecular mechanisms of terminal megakaryopoiesis alterations. We found that Rasa3 catalytic inactivation altered megakaryocyte development, adherence, migration, actin cytoskeleton organization and differentiation into proplatelet forming megakaryocytes. These megakaryocyte alterations were associated with an increased active Rap1 level and a constitutive integrin activation. Thus, these mice presented a severe thrombocytopenia, bleeding and anemia associated with an increased percentage of megakaryocytes in the bone marrow, bone marrow fibrosis, extramedular hematopoiesis, splenomegaly and premature death. Altogether, our results indicate that Rasa3 catalytic activity controls Rap1 activation and integrin signaling during megakaryocyte differentiation in mouse. [less ▲]

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See detailDétection de l'érosion dans un bassin versant agricole par comparaison d'images multidates acquises par drone
Lisein, Jonathan ULg; Pineux, Nathalie ULg; Pierrot-Deseilligny, Marc et al

Conference (2014, June 26)

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See detailA probabilistic model of the adhesive contact forces between rough surfaces in the MEMS stiction context
Hoang Truong, Vinh ULg; Wu, Ling ULg; Arnst, Maarten ULg et al

Conference (2014, June 26)

Stiction is a common failure mechanism in microelectromechanical systems (MEMS) in which two interacting bodies permanently adhere together. This problem is due to the comparability of adhesive surface ... [more ▼]

Stiction is a common failure mechanism in microelectromechanical systems (MEMS) in which two interacting bodies permanently adhere together. This problem is due to the comparability of adhesive surface forces (e.g. Van der Waals forces, capillary forces) and body forces in the MEMS context. To predict the adhesive contact forces coupled with stiction phenomenon, the combination of the Nayak statistical approach with the asperity-based theories is a common solution. However, this method contains some limitations due to the underlying assumptions: infinite size of the interacting rough surfaces and negligibility of asperity interactions. Furthermore, the Nayak solution suffers from a considerable dependency on the choice of the minimum wave length considered in the surface representation, which remains diXcult to select. The main goal of our research is to propose an improved method (i) which accounts for the Vnite size of the interacting surfaces, (ii) accounts for the uncertainties related to these surface topologies, (iii) in which the minimum wave length selection is physically based, and (iv) in which the validity of the asperity-based theories is demonstrated. From the topology measurements of MEMS samples, an analysis of the power spectral density function is carried out to determine the minimum relevant wave length for the problem of interest (here capillary stiction). We also show that at this scale of interest the asperity-based theories remain valid for polysilicon materials. Moreover, instead of considering inVnite surfaces as in the Nayak approach, a set of surfaces, whose sizes are representative of the MEMS structure, is generated based on the approximated power spectral density analysis and using the Monte Carlo method. From this description of the contacting surfaces, the adhesive contact forces can be evaluated by applying the asperity contact theories, leading to a probabilistic distribution of the adhesive contact forces. In addition, as the contact forces are rooted from the micro-scale adhesive forces, while their consequence, stiction, happens at the macro-scale of the considered device, the multi-scale nature of the phenomenon is accounted for. To predict this macro-scale behavior in a probabilistic form, the uncertainty quantiVcation process is coupled with a multiscale analysis. [less ▲]

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See detailPLANTIGRADY DUE TO A LOCALIZED MYOPATHY IN TWO NEWBORN BELGIAN BLUE CALVES
Genart, Marie; Evrard, Laurence ULg; Garcia da Fonseca et al

Poster (2014, June 26)

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See detailEtude des racémases RacX et YlmE et de la protéine PBP4* de Bacillus subtilis en relation avec la désintégration de biofilms
Vanden Broeck, Arnaud ULg

Master's dissertation (2014)

Bacillus subtilis is a PGPR (Plant Growth Promoting Rhizobacterium) Gram positive bacterium and a model for studying the in vitro formation, maturation or disruption of biofilms. Biofilms have been ... [more ▼]

Bacillus subtilis is a PGPR (Plant Growth Promoting Rhizobacterium) Gram positive bacterium and a model for studying the in vitro formation, maturation or disruption of biofilms. Biofilms have been studied for many years because of their adverse effects in the medical sphere. Some D-amino acids have been reported among the factors playing a role in the disassembly of B. subtilis biofilms and a double ylmE and racX mutant (in which both YlmE and RacX racemases are absent) shows a delay in pellicle disruption [I. Kolodkin et al. Science (2010) 328:627-629]. The racX encoding gene is part of a bicistronic operon in which the first gene (pbpE) codes for a putative Penicillin-Binding Protein, the PBP4* whose function is not characterized. Results from DNA microarrays and Proteomics [D. Ren et al. Biotechnology and Bioengineering (2004) 86:344-364] have shown that in B. subtilis biofilms, the expression of the gene coding for PBP4* is increased. Our study in this master thesis aimed to investigate the functions and the structures of the RacX, YlmE and PBP4* proteins. A wide range of techniques such as cloning, into expression vectors, purification, treatment of the recombinant proteins by specific proteases to eliminate the chromatography affinity tags, structural and biochemical characterizations of the proteins have been used. According to sequence analyses, RacX belongs to the Asp/Glu racemase family. We succeeded to produce and purify 34 mg of RacX whose His-tag has been completely eliminated. The protein appeared active on D-Glutamate as substrate but inactive on D-Aspartate. A physiological role is proposed for RacX in the recovery of D-Glu from the peptidoglycan peptides. However, its implication in the biofilm disassembly process is still elusive. The YlmE racemase was also produced and purified (46 mg). Although a role in the in vivo production of D-Tyrosine in B. subtilis ageing biofilms has been proposed for this protein, our attempts to detect an activity on L-Tyr or any other amino acid remained unsuccessful. Bioinformatic studies relate YlmE to type III PLP dependent enzymes close to Alanine racemases. Alignments of YlmE with Alanine racemases pointed out that a C-terminal domain was missing in YlmE. A model has been proposed to explain the absence of YlmE activity. Several constructs were performed to restore a racemase activity: e.g. a fusion of YlmE to the C-terminal domain of the AlaR2 racemase from B. subtilis, but the chimeric protein was insoluble, or the fusion of the AlaR2 C-terminal domain to TrxA in view to obtain in trans complementation with purified YlmE. PBP4* (encoded by pbpE) has been purified (63 mg) and two activities were detected: L-aminopeptidase and DD-carboxypeptidase activities. This PBP is composed of two distinct domains : a N-Terminal catalytic domain related to the D-aminopeptidase from Ochrobactrum anthropic and a C-terminal one that has a lipocalin-like fold. This domain seems involved in the oligomerization of the protein. First attempts of X-Ray diffraction of the entire protein crystals did not give data with sufficient resolution. Therefore, each domain has been separately produced to determine the 3D structure of this unusual PBP. [less ▲]

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See detailL’ancrage dans les herbiers à Posidonia oceanica. Conséquences chimiques de la destruction mécanique ?
Abadie, Arnaud ULg

Poster (2014, June 26)

La plante marine endémique de Méditerranée Posidonia oceanica, ou posidonie, forme en Corse des herbiers colonisant les substrats depuis la surface jusqu’à 40 m de profondeur. Ces herbiers constituent un ... [more ▼]

La plante marine endémique de Méditerranée Posidonia oceanica, ou posidonie, forme en Corse des herbiers colonisant les substrats depuis la surface jusqu’à 40 m de profondeur. Ces herbiers constituent un véritable écosystème, l’un des plus riches en espèces de Méditerranée. Ils jouent un rôle écologique essentiel en oxygénant le milieu grâce à la photosynthèse et en séquestrant du CO2 au sein de leur complexe racinaire dans le sédiment (ou "matte"). Ces activités métaboliques entraînent une importante modification des conditions biogéochimiques du substrat qui favorisent le maintien de la plante. Les herbiers ont également une grande importance économique servant de nurserie pour de nombreuses espèces exploitées par la pêche commerciale et récréative. Les herbiers de posidonie se développant dans les zones côtières, ils sont impactés par les activités anthropiques (urbanisation, pollution, fermes aquacoles, ancrage) qui peuvent entraîner d’importantes destructions et des régressions de leur zone de recouvrement. L’ancrage intensif dans les herbiers à faible profondeur y génère des trouées, ou "intermattes". Les destructions engendrées par les navires de petite taille (< 10 m) peuvent, dans certaines conditions, être recolonisées par la posidonie. Cependant, dans la plupart des zones d’ancrage intensif en Corse, les intermattes ne sont pas recolonisées et leur surface peut souvent augmenter. De plus, certaines zones sont soumises à l’ancrage intensif de navires de plaisance de grande taille (> 20m), susceptibles de générer des intermattes d’une étendue plus importante. Ce phénomène d’expansion ne peut s’expliquer par la seule destruction mécanique. L’arrachage de la strate foliaire de la posidonie par les ancres semble entraîner de profondes modifications physiques et chimiques dans le sédiment. La photosynthèse via les feuilles étant ainsi altérée, il n’y a plus d’oxygénation du sédiment via les racines de la posidonie et un milieu anoxique défavorable à son développement paraît se créer. Des composés toxiques pour la plante, tel que le sulfure d’hydrogène (H2S), pourraient alors s’introduire dans ses tissues entraînant une limitation de son développement, voire sa disparition menant ainsi à une amplification des dégâts mécaniques de l’ancrage. Des observations seront réalisées tout autour de la Corse et notamment dans la Baie de Calvi, site atelier de la Méditerranée, qui a été définie pour mener la phase d’expérimentation. Les données récoltées à l’issue de ces travaux de recherches, réalisés dans le cadre d’un doctorat en entreprise (bourse CIFRE), seront compilées afin de mettre au point de nouveaux outils d’analyse de l’impact de l’ancrage. [less ▲]

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See detailBone markers in patients with CKD
CAVALIER, Etienne ULg

Conference (2014, June 26)

Detailed reference viewed: 9 (0 ULg)