Computer-assisted interventions designed to remediate low numeracy and developmental dyscalculia (mathematical learning disability) have been utilised in preschools and kindergartens with some efficacy for over thirty years (Clements, 2002). A recent development in this field is ‘adaptive game’ technology, which adapts task difficulty online as children learn. The Number Race is the first such package for mathematics. Previous efficacy studies suggest its use results in an improvement in core measures of early numeracy, such as speed at enumerating 1-3 objects (subitizing) and comparison of numerals and groups of objects. The present study tested the efficacy of a new version of The Number Race (version 3.0) using New Zealand English and incorporating new instructional factors, in a younger population than most previously tested. Participants were twelve 5-to-7-year-old children and a typically developing control group matched on age and sex (n = 12). Following pre-testing using standardised tests and a computerised battery, children in the intervention group used The Number Race for twenty minutes each school night, for one month. Post-testing results showed that there was a significant improvement in counting and subitizing speed for the intervention group. Participants also became faster and more accurate at comparing numerals. There were no significant changes in standardised mathematics scores. The mental number line task did not show any significant differences before and after intervention but a wide variety of patterns and possible use of strategies were revealed. Overall, this new version of The Number Race seems to have modest effects in this population.

L’utilisation de systèmes d’imagerie à rayons X lors de chirurgies mini-invasives expose patients et staff médical à des radiations ionisantes. Même si les doses absorbées peuvent être faibles, l’exposition chronique peut causer des effets nocifs (e.g. cancer). Dans cette thèse, nous proposons des nouvelles méthodes pour améliorer la sécurité vis-à-vis des radiations ionisantes en salle opératoire hybride dans deux directions complémentaires. Premièrement, nous présentons des approches pour rendre les cliniciens plus conscients des irradiations grâce à des visualisations par réalité augmentée. Deuxièmement, nous proposons une méthode d'optimisation pour suggérer une pose de l’imageur réduisant la dose au personnel et patient, tout en conservant la qualité de l’image. Pour rendre ces applications possibles, des nouvelles approches pour la perception de la salle grâce à des caméras RGBD et pour la simulation en temps-réel de la propagation et doses de radiation ont aussi été proposées. / The use of X-ray imaging technologies during minimally-invasive procedures exposes both patients and medical staff to ionizing radiation. Even if the dose absorbed during a single procedure can be low, long-term exposure can lead to noxious effects (e.g. cancer). In this thesis, we therefore propose methods to improve the overall radiation safety in the hybrid operating room by acting in two complementary directions. First, we propose approaches to make clinicians more aware of exposure by providing in-situ visual feedback of the ongoing radiation dose by means of augmented reality. Second, we propose to act on the X-ray device positioning with an optimization approach for recommending an angulation reducing the dose deposited to both patient and staff, while maintaining the clinical quality of the outcome image. Both applications rely on approaches proposed to perceive the room using RGBD cameras and to simulate in real-time the propagation of radiation and the deposited dose.