Differing in vitro biology of equine, ovine, porcine and human articular chondrocytes derived from the knee joint: an immunomorphical study.

in Histochemistry & Cell Biology (2009), 131

For lack of sufficient human cartilage donors, chondrocytes isolated from various animal species are used for cartilage tissue engineering. The present study was undertaken to compare key features of ... [more ▼]

For lack of sufficient human cartilage donors, chondrocytes isolated from various animal species are used for cartilage tissue engineering. The present study was undertaken to compare key features of cultured large animal and human articular chondrocytes of the knee joint. Primary chondrocytes were isolated from human, porcine, ovine and equine full thickness knee joint cartilage and investigated flow cytometrically for their proliferation rate. Synthesis of extracellular matrix proteins collagen type II, cartilage proteoglycans, collagen type I, fibronectin and cytoskeletal organization were studied in freshly isolated or passaged chondrocytes using immunohistochemistry and western blotting. Chondrocytes morphology, proliferation, extracellular matrix synthesis and cytoskeleton assembly differed substantially between these species. Proliferation was higher in animal derived compared with human chondrocytes. All chondrocytes expressed a cartilage-specific extracellular matrix. However, after monolayer expansion, cartilage proteoglycan expression was barely detectable in equine chondrocytes whereby fibronectin and collagen type I deposition increased compared with porcine and human chondrocytes. Animal-derived chondrocytes developed more F-actin fibers during culturing than human chondrocytes. With respect to proliferation and extracellular matrix synthesis, human chondrocytes shared more similarity with porcine than with ovine or equine chondrocytes. These interspecies differences in chondrocytes in vitro biology should be considered when using animal models. [less ▲]

Difficiles libertés de circulation

in Clochard, Olivier (Ed.) Atlas des Migrants en Europe (2012)

Difficultés dans l'utilisation d'instruments de pilotage pour la définition des politiques de sécurité locales-Le cas du moniteur de sécurité en Belgique

in Revue de la Faculté de Droit de l'Université de Liège (2005), 2005/1

"Les difficultés de mise en état d'un litige multipartite non indivisible", note sous J.P. Malmédy Spa Stavelot, siège de Spa, 19 septembre 2002

in Journal des Tribunaux (2003), (6092), 274-275

Les difficultés morphosyntaxiques des enfants présentant des troubles spécifiques du langage oral: une approche constructiviste

in Rééducation Orthophonique (2009), 238

The Construction and Usage-based Theory (CUT) combines two main approaches drawn from cognitive linguistics: construction grammar and usage-based theory. The CUT emphasizes the fact that language ... [more ▼]

The Construction and Usage-based Theory (CUT) combines two main approaches drawn from cognitive linguistics: construction grammar and usage-based theory. The CUT emphasizes the fact that language structures progressively emerge through the use of general cognitive processes. Most new forms produced by a child are built upon his/her own previous productions that he/she complexifies and generalizes to construct more abstract forms. These hypotheses have been tested with normally-developing children but have not yet been tested on children with specific language impairment (SLI). In this paper, we put forward several hypotheses drawn from constructivistic approaches to explain morphosyntactic difficulties displayed by children with SLI. Their goal is to create a theoretical framework for future behavioral studies. [less ▲]

Difficultés scolaires : comment améliorer la méthode de travail par l'Education cognitive

Scientific conference (2013, March 14)

De plus en plus d'élèves ont des difficultés liées à leur façon d'apprendre. Nombre d'entre eux présentent un point commun : ils n'ont pas pleinement développé leurs compétences métacognitives. L'élève n ... [more ▼]

De plus en plus d'élèves ont des difficultés liées à leur façon d'apprendre. Nombre d'entre eux présentent un point commun : ils n'ont pas pleinement développé leurs compétences métacognitives. L'élève n'exploite pas pleinement son potentiel d'apprentissage, il n'a pas développé un niveau suffisant de connaissances sur lui (ses points forts, ses points faibles, son style d'apprentissage ...) ni ses stratégies de haut niveau (anticipation, planification, contrôles et transfert). A cela, s'ajoutent des aspects psychoaffectifs aggravants (faibles objectifs d'apprentissage, faible estime de soi, démobilisation scolaire ...). Incluant une définition de la métacognition, il s'agira notamment d'étudier les actions possibles à l'aide d'outils et de méthodes notamment issus de l'Education cognitive. [less ▲]

A Diffraction Model for Acoustical Ray-Tracing Based on the Energy Flow Lines Concept

in Acta Acustica United with Acustica (2013), 99

Geometrical acoustics models are currently the most popular prediction tools in room-acoustics due to their low computing load. However, they seldom take into account the diffraction occurring at free ... [more ▼]

Geometrical acoustics models are currently the most popular prediction tools in room-acoustics due to their low computing load. However, they seldom take into account the diffraction occurring at free edges. Moreover, the existing diffraction models implemented in geometrical acoustics algorithms are either limited to specularly reflected paths or either present excessive computation load. Recently, a diffraction model based on an approximation of the far-field direction of the Poynting’s vector around half-planes has been introduced for computing the scattering due to faceted dielectric objects. In this article, this model is developed to handle obliquely incident waves and is implemented within an acoustic ray-tracing software using the analogy between the Poynting’s and the acoustic intensity vectors. The proposed model can handle both diffuse and specular reflections and sets no limit in terms of reflection or diffraction order. The first results obtained by ray-tracing agree well with the uniform theory of diffraction and the boundary elements method for single and double diffraction problems even if the interference effects are neglected and as long as the number of emitted rays is sufficient. Moreover, the additional computation load to handle diffraction is shown to be low compared to the one from a classical ray-tracing algorithm. [less ▲]

Diffractive straylight rejection system for wide field imagers. Design, performance and application to the STEREO solar space mission.

Doctoral thesis (2012)

Space-born wide field imagers have become a new tool used in the frame of Solar Physics and in particular in the field of Space Weather. One particular application is the tracking of coronal mass ejection ... [more ▼]

Space-born wide field imagers have become a new tool used in the frame of Solar Physics and in particular in the field of Space Weather. One particular application is the tracking of coronal mass ejection (CME), generated by violent eruptions on the sun’s surface, that propagates in the heliosphere. The CME brightness however rapidly decreases with the distance from the Sun. To reach a sufficient signal to noise ratio and follow CME away from the Sun, a high sensitivity is therefore required and the unwanted parasitic light (so called straylight) must be minimized. In particular, the Sun disk brightness must be occulted by a highly rejecting baffle system. A multi-edge diffractive baffle can provide a very high level of straylight attenuation for nearly collimated light source. A model of the multi-edge diffractive rejection has been implemented on the basis of the Fresnel diffraction theory. It allows the design and optimisation of such diffractive baffle as function of the instrument and observing geometries. The model was validated on a diffractive baffle mock-up, providing rejection down to an un-precedent level of 10-10 of the input flux. The model of multi-edge diffractive baffle has been applied to the specific configuration of the Heliospheric Imager (HI), on-board the NASA scientific Solar Terrestrial Relations Observatory (STEREO) mission, as part of its overall straylight reduction. The STEREO-HI baffle performance has been validated on a prototype and during the final end-to-end calibration of the flight instrument. After launch, the in-flight straylight level has been quantified, showing a very good correspondence with the on-ground measurements. The straylight evolution has also been shown to be stable during the mission, showing the baffle efficiency does not degrade with the space environment. The STEREO-HI instrument achieves a 10-13 rejection level, or greater, of the solar brightness at the detector pixel level. This instrument is the first wide field space imager viewing from outside the Sun-Earth line, and therefore able to directly follow the propagation of CME from the Sun to the Earth with a high accuracy and sensitivity. Since its launch, it provides unprecedented images and information on solar wind and CME propagation and evolution in the heliosphere. The next generation of wide-field solar imagers are under development for the ESA Solar Orbiter and NASA Solar Probe Plus missions. Their concept benefits from of the STEREO-HI front diffractive baffle system and is based on a multi-edge diffractive baffle to protect their cameras from solar disk brightness. The straylight calibration of these two instruments is in preparation and will be performed at the Centre Spatial de Liège with the tools and methods developed in the frame of the present work. [less ▲]

Diffuse dermal angiomatosis: A previously undescribed pattern of immunoglobulin and complement deposits in two cases.

in American Journal of Dermatopathology (2006), 28(2), 150-4

Two cases of diffuse dermal angiomatosis are reported in middle-aged women. This rare disease of unknown origin is characterized by increased dermal angiomatosis and ulceration. The clinical and ... [more ▼]

Two cases of diffuse dermal angiomatosis are reported in middle-aged women. This rare disease of unknown origin is characterized by increased dermal angiomatosis and ulceration. The clinical and histologic presentations of the presently reported lesions were typical for this disorder. Endothelial cells exhibited a normal immunophenotype. The perivascular basement membranes showed a distribution of collagen alpha chains typical for blood vessels, but not for lymphatics. Immunohistochemistry revealed other undescribed features. At the site of the clinical lesions, linear and granular deposits of immunoglobulins A and M, and complement were found around the vessels and at the dermal-epidermal junction. The same deposits were also found restricted to the dermal-epidermal junction in the peripheral clinically intact skin. No serological signs of auto-immune disorder were detected in one patient. A monoclonal gammopathy was disclosed in the other patient. A pattern of immunoreactant deposits similar to that disclosed in the two patients was not found in the control specimens, and has not been described so far in other types of vascular hyperplasia and neoplasia. A pathogenic role of these deposits is unsettled and should be further explored. [less ▲]

Diffuse large B-cell lymphomas of the waldeyer's ring frequently have a germinal center-like phenotype: a clinico-pathological study of 209 patients from the groupe d'étude des lymphomes de l'adulte (GELA).

Poster (2007)