Biocompatibility of an x-shaped zirconium implant in deep sclerectomy in rabbits

Background: The aim of this study was to evaluate the mid-term biocompatibility of a new x-shaped implant made of zirconium in an animal model of glaucoma surgery. Methods: Preoperatively, ultrasound biomicroscopy (UBM), intraocular pressure (IOP) and outflow facility (OF) data were acquired. Upon surgery, one eye was chosen randomly to receive an implant, while the other received none. Ten rabbits went through a 1-, 2-, 3-, 4- and 6-month follow-up. IOP was measured regularly, UBM performed at 1, 3 and 6months after surgery. At the end of the follow-up, OF was again measured. Histology sections were analyzed. Results: For both groups IOP control was satisfactory, while OF initially increased at month 1 to resume preoperative values thereafter. Eyes with implants had larger filtration blebs which decreased faster than in eyes without the implant. Drainage vessel density, inflammatory cell number and fibrosis were higher in tissues near the implant. Conclusions: The zirconium implant initially promoted the positive effects of the surgery (IOP control, OF increase). Nevertheless, after several months, foreign body reactions and fibrosis had occurred on some implants that restrained the early benefit of such a procedure. Modifications of the zirconium implant geometry could enhance the overall success rat

La campagne des néoruraux : motifs de migration, territoires valorisés et usages de l’espace domestique

Si la « néoruralité » est aujourd’hui un phénomène largement répandu, son interprétation sociologique demeure incomplète. Malgré l’étendue des territoires concernés et l’ampleur des changements sociodémographiques en cause, les travaux au Québec sur ce sujet font défaut. Sans prétendre dresser un portrait exhaustif du phénomène, notre étude vise trois objectifs : cerner les motifs de migration des néoruraux, déceler les attributs du rural qu’ils valorisent et décrire les usages de la campagne qu’ils privilégient. Quoique présentant des profils hétérogènes, les migrants rencontrés expriment certaines motivations convergentes. En s’établissant dans Havelock (Haut-Saint-Laurent), ils ont choisi une campagne « vivante ». Attirés par les espaces verts propices aux activités de plein air, ils ont quitté la ville afin d’agrandir leur espace domestique. Les expressions qu’ils utilisent pour qualifier leur propriété et l’usage qu’ils en font attestent de la vocation plurielle du rural. Lieu de réminiscence, d’isolement et d’expérimentation, la campagne des néoruraux se révèle a priori différente de celle des « locaux ». En règle générale, ces nouveaux résidants se gardent notamment d’effectuer des ponctions sur les ressources naturelles locales.While “neoruralism” is a fairly widespread phenomenon nowadays, it has not yet been fully interpreted from a sociological viewpoint. Despite the vast areas of land involved and the scale of the socio-demographic changes in question, there is a shortage of research on this topic in Québec. Without claiming to present an exhaustive portrait of the phenomenon, this paper pursues three goals : to identify the motivation factors of migration among neorural folk, to identify the features of the rural setting that they value, and to describe the uses of rural land that they prefer. Although there is some diversity among the profiles presented, there are some common features to the motivations expressed by these migrants. Those settling in Havelock (Haut-Saint-Laurent) have chosen a countryside with a “life-focus”. Attracted to green spaces suitable for outdoor activities, they have left the city in order to widen their domestic space. The expressions through which they describe their property and the use that they make of it confirm the multiple vocation of the rural sphere : a place for reminiscence, to be alone, to experiment, the countryside of the neorural folk appears a priori to be different from that of the local inhabitants. As a general rule, these new residents tend not to exploit the local natural resources

Examining the impact of trait anxiety on the recognition of facial emotional expressions

Question : Cette thèse comporte deux articles portant sur l’étude d’expressions faciales émotionnelles. Le processus de développement d’une nouvelle banque de stimuli émotionnels fait l’objet du premier article, alors que le deuxième article utilise cette banque pour étudier l’effet de l’anxiété de trait sur la reconnaissance des expressions statiques. Méthodes : Un total de 1088 clips émotionnels (34 acteurs X 8 émotions X 4 exemplaire) ont été alignés spatialement et temporellement de sorte que les yeux et le nez de chaque acteur occupent le même endroit dans toutes les vidéos. Les vidéos sont toutes d’une durée de 500ms et contiennent l’Apex de l’expression. La banque d’expressions statiques fut créée à partir de la dernière image des clips. Les stimuli ont été soumis à un processus de validation rigoureux. Dans la deuxième étude, les expressions statiques sont utilisées conjointement avec la méthode Bubbles dans le but d’étudier la reconnaissance des émotions chez des participants anxieux. Résultats : Dans la première étude, les meilleurs stimuli ont été sélectionnés [2 (statique & dynamique) X 8 (expressions) X 10 (acteurs)] et forment la banque d’expressions STOIC. Dans la deuxième étude, il est démontré que les individus présentant de l'anxiété de trait utilisent préférentiellement les basses fréquences spatiales de la région buccale du visage et ont une meilleure reconnaissance des expressions de peur. Discussion : La banque d’expressions faciales STOIC comporte des caractéristiques uniques qui font qu’elle se démarque des autres. Elle peut être téléchargée gratuitement, elle contient des vidéos naturelles et tous les stimuli ont été alignés, ce qui fait d’elle un outil de choix pour la communauté scientifique et les cliniciens. Les stimuli statiques de STOIC furent utilisés pour franchir une première étape dans la recherche sur la perception des émotions chez des individus présentant de l’anxiété de trait. Nous croyons que l’utilisation des basses fréquences est à la base des meilleures performances de ces individus, et que l’utilisation de ce type d’information visuelle désambigüise les expressions de peur et de surprise. Nous pensons également que c’est la névrose (chevauchement entre l'anxiété et la dépression), et non l’anxiété même qui est associée à de meilleures performances en reconnaissance d’expressions faciales de la peur. L’utilisation d’instruments mesurant ce concept devrait être envisagée dans de futures études.Question: This thesis describes a new database of facial emotional expressions; created specifically for eye-tracking and classification image experiments. This database serves as a basis for the second study, which explores the effect of trait anxiety on the perception of static facial emotional expressions. Methods: Actors were recruited to express facial emotional expressions. Thousands of 1-second movie clips that contained the least head movement and appeared genuine were extracted from the raw videos and selected for the validation. A total of 1088 clips (34 actors X 8 expressions X 4 exemplar) were spatially aligned so that facial features across the stimuli occupied the same space. They were also temporally aligned so that all clips began on the last neutral frame and truncated on the 15th frame (500ms). The last frame (apex) of the clips was extracted to form the static database. Two groups of participants validated the dynamic (N35) and static (N35) stimuli. The static images were used in the 2nd study where participants (N27) varying in trait anxiety were asked to recognize emotional faces, partially revealed through Gaussian apertures (Bubbles). Results: Study 1 describes the process by which the STOIC database was created. It showcases the 80 dynamic (and 80 static) emotional expressions (8 emotions X 10 actors) with the lowest entropy scores. Study 2 shows that trait anxiety is associated with performance and differential use of information. Anxious individuals use low spatial frequency (LSF) information from the mouth region and are better at recognizing negative emotions, especially fear and not anger. Discussion: This thesis presents a new and freely downloadable emotion recognition database containing static and dynamic stimuli. The database possesses unique characteristics that will make it useful to the scientific community and clinicians. We used the static images in the second study to establish a baseline and gain a better understanding about the use of information contained in faces to recognized emotional expressions. The next phase of the project will be to explore the effects of anxiety and depression on the perception of dynamic expressions. We speculate that the use of LSF information in our anxious group disambiguated fear from surprise and led to better performance for that emotion. In addition, we think the overlap between anxiety and depression, which was associated with better performances, may be attributed to concept of neuroticism

Generalizing Robot Imitation Learning with Invariant Hidden Semi-Markov Models

Generalizing manipulation skills to new situations requires extracting invariant patterns from demonstrations. For example, the robot needs to understand the demonstrations at a higher level while being invariant to the appearance of the objects, geometric aspects of objects such as its position, size, orientation and viewpoint of the observer in the demonstrations. In this paper, we propose an algorithm that learns a joint probability density function of the demonstrations with invariant formulations of hidden semi-Markov models to extract invariant segments (also termed as sub-goals or options), and smoothly follow the generated sequence of states with a linear quadratic tracking controller. The algorithm takes as input the demonstrations with respect to different coordinate systems describing virtual landmarks or objects of interest with a task-parameterized formulation, and adapt the segments according to the environmental changes in a systematic manner. We present variants of this algorithm in latent space with low-rank covariance decompositions, semi-tied covariances, and non-parametric online estimation of model parameters under small variance asymptotics; yielding considerably low sample and model complexity for acquiring new manipulation skills. The algorithm allows a Baxter robot to learn a pick-and-place task while avoiding a movable obstacle based on only 4 kinesthetic demonstrations.Comment: accepted in WAFR 201

Deep sclerectomy with the Ex-PRESS X-200 implant for the surgical treatment of glaucoma

The efficacy and safety of a newly designed Ex-PRESS X-200 drainage device for the surgical treatment of glaucoma was evaluated. A clinical, prospective, monocentric, non-randomised, unmasked study on patients with medically uncontrolled glaucoma was performed. A superficial scleral flap was created. A posterior deep sclerectomy (DS) was dissected without opening the Schlemm's canal and an Ex-PRESS X-200 device was inserted under the scleral flap into the anterior chamber to drain aqueous humour into the intrascleral space. Biomicroscopy, best-corrected visual acuity (BCVA), applanation intra-ocular pressure (IOP) measurements, and fundus examination were performed before surgery, on the first day, the first week, and 1, 2, 3, 6, 12 and 18months after surgery. The mean follow-up was 18.6±2.4months (mean±SD) for the 26 eyes that were treated with the Ex-PRESS X-200 device. Pre-operatively, the mean BCVA was 0.6±0.3, the mean IOP was 22.0±5.1mmHg, and the mean number of medications per patients was 2.8±0.8. Eighteen months after surgery the mean BCVA was 0.5±0.4, the mean IOP was reduced to 12.0±3.9mmHg, and the mean number of medications per patient was 0.6±1.2. Eighty-five percent of patients achieved an IOP<18mmHg with or without medication and 69% without medication. Post-operative complications were hyphaema (15%), Seidel (15%), encysted blebs (54%) and bleb fibrosis in 8% of patients. Mitomycin C(MMC) was administered to 15 patients (58%) with needling being performed on 10 (38%) of these patients. Mid-term results of DS with the Ex-PRESS X-200 implant demonstrated its efficacy in controlling IOP with few post-operative complications in difficult eyes with an increased risk of surgery failur

Contrôle attentionnel et vieillissement normal : contribution à la mémoire de travail et variabilité interindividuelle

Dans le contexte actuel du vieillissement de la population, il importe de s’intéresser aux changements qui surviennent avec l’avancement en âge. Le vieillissement s’accompagne de modifications pour différentes fonctions cognitives, dont la mémoire de travail (MdeT), un système permettant le maintien temporaire et la manipulation d’une petite quantité d’informations. Les travaux de cette thèse portent sur le vieillissement normal de la MdeT et des fonctions de contrôle attentionnel (FCA) qui la sous-tendent (l’alternance, l’inhibition et la mise à jour). D’abord, la première étude (Chapitre II) visait à préciser l’effet du vieillissement normal sur la MdeT et sur chacune des FCA qui la sous-tendent. Elle avait également pour but d’identifier les FCA qui contribuent à la réalisation de différentes tâches de MdeT, et si cette contribution diffère selon le groupe d’âge. Des tâches mesurant chacune des FCA ainsi que des tâches de MdeT ont été administrées à des personnes âgées et à des jeunes adultes. Les analyses contrôlant pour le ralentissement cognitif ont révélé que les habiletés d’alternance et de mise à jour sont préservées chez les personnes âgées, mais que l’inhibition est atteinte comparativement aux jeunes adultes. Les analyses ont également montré que l’impact du vieillissement sur la MdeT dépend de la tâche utilisée. Enfin, les résultats ont indiqué que la contribution des FCA à la MdeT dépend à la fois de la tâche de MdeT et du groupe d’âge. En particulier, la mise à jour contribue davantage à la MdeT des personnes âgées qu’à celle des jeunes, ce qui pourrait refléter une tentative de compensation. La seconde étude (Chapitre III) avait pour objectif de caractériser la variabilité interindividuelle au niveau des FCA, pour les personnes âgées et pour les jeunes adultes. Des analyses hiérarchiques en grappes réalisées sur les habiletés d’alternance, d’inhibition et de mise à jour, ont permis de déterminer si différents profils de contrôle attentionnel étaient présents. L’étude cherchait également à déterminer si les individus appartenant à des profils de contrôle attentionnel distincts diffèrent quant à certaines variables intellectuelles ou de santé. Les analyses ont mis en évidence trois profils de contrôle attentionnel distincts parmi les personnes âgées, l’inhibition étant une FCA critique pour distinguer entre les trois sous-groupes. Trois profils de contrôle attentionnel ont également été identifiés chez les jeunes adultes, et ces profils étaient caractérisés par moins de variabilité intra-individuelle que ceux des âgés. Les analyses ont par ailleurs montré que les profils de contrôle attentionnel se distinguent sur certaines variables intellectuelles et de santé. Les implications théoriques et cliniques de ces résultats seront discutées en fin de thèse (Chapitre IV).As the population is aging, it is increasingly important to study the changes that occur with advancing age. Normal aging is characterized by changes in various cognitive functions, such as working memory (WM), a limited capacity system that temporarily holds and manipulates a small quantity of information. The work presented in this thesis focused on the normal aging of WM and of the attentional control functions (ACFs) that underlie this system (shifting, inhibition, and updating). The first study (Chapter II) aimed at exploring the impact of normal aging on WM and on each of the ACFs. We also sought to determine which ACFs contribute to performance on different WM tests, and whether age group has an impact on those contributions. Tasks measuring each ACF as well as WM tasks were administered to healthy older adults and to younger adults. The analyses controlling for cognitive slowing revealed that older adults’ shifting and updating abilities are preserved, but that their inhibition abilities are impaired compared to younger adults. Moreover, the impact of normal aging on WM is task-dependent. The results also indicated that the relative contribution of the ACFs to WM depends on both the WM task used and the age group. In particular, older adults relied more than younger adults on updating to perform WM tasks, which might reflect a compensation attempt. The second study (Chapter III) aimed at characterizing interindividual variability in the ACFs of both older and younger adults. Cluster analyses were performed on the shifting, inhibition, and updating abilities, in order to determine whether different attentional control profiles were present. This study also explored whether the individuals that belonged to distinct attentional control profiles differed as to intellectual and health variables. The analyses revealed three attentional control profiles among older adults, and inhibition was the ACF for which the three profiles differed the most. Three attentional control profiles were also identified among younger adults, and their profiles were characterized by less intra-individual variability than those of older adults. The results also showed that individuals belonging to different attentional control profiles differed on some intellectual and health variables. The theoretical and clinical implications of those findings are discussed in Chapter IV

Outflow mechanisms after deep sclerectomy with two different designs of collagen implant in an animal model

Background: To study experimentally two different shapes of collagen implants (CI) used in deep sclerectomy (DS). The ability to promote drainage vessels, outflow mechanisms, success rates, and biodegradability, were studied prospectively in an animal model. Materials and methods: DS was performed in 20 eyes of ten rabbits. Each rabbit randomly received a cylindrical CI in one eye, while the other eye received a flat CI. Intraocular pressure (IOP) measurement, ultrasound biomicroscopy (UBM) examination of DS site and simultaneous fluorescein and indocyanin green anterior-segment angiography were performed preoperatively, at 1 and 2 weeks, 1, 2, 3, 6 and 9 months for each eye. At the end of the follow-up period, outflow facility (OF) was measured and histological examinations of the filtration site were performed. Results: In the cylindrical implant group, IOP significantly dropped from a mean preoperative value of 14.8±2.2mmHg to a mean postoperative values of 10.9±3.3, 12.5±2.2, 11.8±2.6, 11.2±2.3, 10.7±1.9, 14.0± 3.2, 12.6±2.4mmHg at 1, 2 weeks, and 1, 2, 3, 6, and 9 months, respectively. In the flat CI group, IOP significantly dropped from a mean preoperative value of 14.1±1.8mmHg to a mean postoperative values of 10.4±2.7, 12.7±1.9, 12.5±3.2, 11.2±1.6, 11.6±1.8, 11.5±2.3, 11.0±2.2mmHg at 1, 2 weeks, and at 1, 2, 3, 6, and 9 months, respectively. UBM images showed a gradual resorption of both type of CI during the first 3 months, and angiographies showed progressive growth of drainage vessels around the filtration site in both groups. The mean OF 9 months postoperatively for the cylindrical CI was 0.53 (SD ± 0.23) ml/min per mmHg and was 0.56 (SD±0.17) ml/min per mmHg for the flat CI (P=0.6). Histological examination revealed excellent biocompatibilty and a high density of drainage vessels in the sclera around the operative site in both groups. Conclusion: Using IOP and OF measurements, UBM, angiography, and histology, we were able to compare two types of CI used as space maintainer in DS. Both CIs showed efficient IOP lowering effect and outflow facility increase, possibly explained by stimulation of drainage vessels growth. Both implants showed excellent biocompatibility. The flat CI showed a slight tendency towards better overall performance