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International audience; This study explores the informal statistical inference (ISI) experiences through the graph construction of young children regarding the pictograph as one of the conventional data displays. Within a case study approach, interviews with 7 years-old children were conducted through a module including a task. The task designed here presents a statistical context structure which focuses on the eye colors observed in a class. Through forming a pictograph, children responded the questions in order to investigate their informal inferential reasoning ability. Findings revealed that young children’s graph construction experiences could be expressed as a construct of ISI. Besides, it was concluded that the integration of context with data helped their graph construction since they analyzed data within the context.

International audience; With the aim of contributing to the study of the statistical knowledge of pre-service primary school teachers, here we present the creation of a system of categories of analysis to characterize the written reports of a group of students who carried out a task that reflected the five stages of the statistical investigative cycle. The analysis answers to a deductive/inductive process, since we look at the theory to understand our data and, at the same time, themes emerge that had not yet been described in the literature. Our contribution is a system of categories for the characterization of the statistical investigative cycle, which consolidates, refines and extends what has been published so far. The proposal presented here may be useful not only for researchers and teacher educators, but also for pre-service teachers themselves to understand the investigative cycle.

The recent introduction of the phenyl-β-D-galactopyranoside (P-gal)-based positive-selection system for screening of λlacZ phages originating from the λlacZ transgenic mouse (Muta Mouse) has made the determination of mutant frequencies (MF) a much simpler task. Previously, MF data from these mice have been collected by means of the 5-bromo-4-chloro-3- indolyl-β-D-galactopyranoside (X-gal) colour-screening procedure. To determine whether data obtained with the two systems are comparable, the MF in h phages recovered from liver and brain of transgenic mice treated with N-ethyl-N-nitrosourea (ENU) and liver of benzo(a)pyrene (B(α)P)-treated mice was determined with both procedures. For the livers of mice treated with ENU, both methods yielded approximately the same MF values. No induction of mutants, relative to the control animals, was seen after 1.5 h, but a clear 4-fold increase was measured with both assays at the 14-day time point. No induction of mutants was found in the brain with either method. In the B(α)P-treated mice, both methods showed a substantial induction in MF after 21, 28 and 35 days. The values generated by the X-gal and P-gal methods were not significantly different, with the exception of the 35-day post-treatment point that appeared higher in the X-gal assay. When the mutants isolated by use of the X-gal method were tested in the P-gal assay, a number of these did not turn up as mutants, and the significance disappeared, In conclusion, the data obtained with the two screening procedures agree to such an extent as to permit a direct comparison between the earlier results generated with X-gal and P-gal values generated with the new positive-selection method. This is likely to apply also to other organs and mutagens than those studied here.

International audience; The study attempted to investigate the ways a prospective teacher, Elif, responded to contingent moments in her teaching practice. In addition, her perceptions regarding changes in the nature of the tasks based on the students’ unanticipated thinking after the teaching were examined. Elif attended to a two-hour class of teaching seminar in which categorizations of mathematical tasks were presented. Then, during her enrollment in teaching practicum course, she taught a lesson on algebra by considering the categorization of the tasks. The lesson plan, her video record of teaching, semi-structured pre and post interviews were analyzed based on contingent trigger categories and kinds of teachers’ responses to them and tasks during the phase of selecting, enacting and revising were analyzed based on its cognitive demand. Results showed that the contingent moments lead her to reanalyze the content and implementation of the designed tasks for further teaching.

Cette thèse aborde l'étude de la fonction cérébrale en Imagerie par Résonance Magnétique (IRM) à l'aide de deux séquences : l'IRM fonctionnelle (IRMf) BOLD et l'imagerie de perfusion par marquage de spins (ASL). Dans ce contexte, les analyses de groupe jouent un rôle important dans l'identification des dysfonctionnements globaux associés à une pathologie. D'autre part, les études individuelles, qui fournissent des conclusions au niveau d'un sujet unique, présentent un intérêt croissant. Dans ce travail, nous abordons à la fois les études de groupe et les analyses individuelles. Dans un premier temps, nous réalisons une analyse de groupe en IRMf BOLD en vue d'étudier la dysphasie chez l'enfant, une pathologie peu explorée en neuroimagerie. Nous mettons ainsi en évidence un fonctionnement et une latéralisation atypiques des aires langagières. Ensuite, nous nous concentrons sur les analyses individuelles. Nous proposons l'utilisation d'estimateurs robustes pour calculer les cartographies de débit sanguin cérébral en ASL. Ensuite, nous étudions la validité des hypothèses qui sous-tendent les analyses statistiques standard dans le contexte de l'ASL. Finalement, nous proposons une nouvelle méthode localement multivariée basée sur une approche a contrario. La validation de cette nouvelle approche est réalisée dans deux contextes applicatifs : la détection d'anomalies de perfusion en ASL et la détection de zones d'activation en IRMf BOLD. This thesis deals with the analysis of brain function in Magnetic Resonance Imaging (MRI) using two sequences: BOLD functional MRI (fMRI) and Arterial Spin Labelling (ASL). In this context, group statistical analyses are of great importance in order to understand the general mechanisms underlying a pathology, but there is also an increasing interest towards patient-specific analyses that draw conclusions at the patient level. Both group and patient-specific analyses are studied in this thesis. We first introduce a group analysis in BOLD fMRI for the study of specific language impairment, a pathology that was very little investigated in neuroimaging. We outline atypical patterns of functional activity and lateralisation in language regions. Then, we move forward to patient-specific analysis. We propose the use of robust estimators to compute cerebral blood flow maps in ASL. Then, we analyse the validity of the assumptions underlying standard statistical analyses in the context of ASL. Finally, we propose a new locally multivariate statistical method based on an a contrario approach and apply it to the detection of atypical patterns of perfusion in ASL and to activation detection in BOLD functional MRI.

To choose suitable resources for personal competence development in the vast amount of open educational resources is a challenging task for a learner. Starting with a needs analysis of lifelong learners and learning designers we introduce two wayfinding services that are currently researched and developed in the framework of the Integrated Project TENCompetence. Then we discuss the role of these services to support learners in finding and selecting open educational resources and finally we give an outlook on future research.

International audience; Image-guided external beam radiotherapy (EBRT) allows radiation dose deposition with a high degree of accuracy and precision. Guidance is usually achieved by estimating the displacements, via image registration, between cone beam computed tomography (CBCT) and computed tomography (CT) images acquired at different stages of the therapy. The resulting displacements are then used to reposition the patient such that the location of the tumor at the time of treatment matches its position during planning. Moreover, ongoing research aims to use CBCT-CT image registration for online plan adaptation. However, CBCT images are usually acquired using a small number of X-Ray projections and/or low beam intensities. This often leads to the images being subject to low contrast, low signal-to-noise ratio and artifacts, which ends-up hampering the image registration process. Previous studies addressed this by integrating additional image processing steps into the registration procedure. However, these steps are usually designed for particular image acquisition schemes, therefore limiting their use on a case-by-case basis. In the current study we address CT to CBCT and CBCT to CBCT registration by the means of the recently proposed EVolution registration algorithm. Contrary to previous approaches, EVolution does not require the integration of additional image processing steps in the registration scheme. Moreover, the algorithm requires a low number of input parameters, is easily parallelizable and provides an elastic deformation on a point-by-point basis. Results have shown that for typical CBCT images, the intrinsic image artifacts only have a sub-millimeter impact on the accuracy and precision of the estimated deformation. In addition, the algorithm has low computational requirements, which are compatible with online image-based guidance of EBRT treatments.

Schizophrenia is a complex psychiatric illness which is caused by multiple genes and gene-environment interactions. This complex etiology has a negative impact on the power of molecular genetic studies. To improve this situation, attempts are made to define traits that are more intimately related to the genetic factors of schizophrenia, and have a more straightforward genotype-phenotype relationship. These traits are called endophenotypes. The deficit of patients to suppress reflexive saccades during antisaccades has been suggested as endophenotype for schizophrenia. Recent evidence suggests that functional magnetic resonance imaging (fMRI)-brain activation maps can further strengthen the genotype-phenotype relationship. In a series of studies, the suitability of brain activation maps during antisaccades as endophenotype for schizophrenia is assessed. In the first study, an event related fMRI design was developed for measuring the brain activation associated with saccades and saccadic inhibition. This study demonstrated that fMRI could pick up brain activation in all areas that are known to be involved in oculomotor functioning from studies in primates. In addition, the results of this study stress the importance of using event related fMRI for this particular saccade paradigm. An endophenotype should be related to the illness. In the second study, the fMRI design was used to find the functional brain abnormalities that underlie the saccadic inhibition deficit in schizophrenia. It was found that patients did not activate the striatum during inhibition of saccades. These results indicate that the impairment of patients in saccadic inhibition can be related to a dysfunction in the striatum, or in the frontostriatal circuitry. An endophenotype is more frequently present in those with genetic risk for schizophrenia. Accordingly, the third study found the same striatal abnormality in healthy siblings of patients during antisaccades. However, the siblings did not demonstrate an behavioural abnormality, suggesting that fMRI activation maps can increase sensitivity. When subjects are phenotyped based on brain activation, age differences between subjects can ad noise to the data. In the fourth study, effects of aging on brain activation during the antisaccade paradigm were assessed in a group covering a broad age range. Age did not only alter the cognitive strategy for the task, but also the neuronal vascular coupling. Good endophenotypes should be stable traits. The fifth study assessed the reproducibility of brain activation during antisaccades over a one week period in a group of healthy subjects. The results demonstrated large differences between subjects in the test-retest reliability of brain activation maps, which was caused largely by stable differences between subjects in signal to noise ratios. Differences between subjects in signal to noise can result in overestimation of between subject variance. In conclusion, fMRI is capable of detecting saccade related brain activation and abnormalities in patients and their siblings, even when no behavioural abnormalities could be detected. Hence the use of fMRI could potentially strengthen the genotype-phenotype relationship. Although fMRI is not yet capable of to obtain reliable activation maps in all subjects, this situation is likely to improve in the future with increasing MR-field strengths and more sophisticated acquisition techniques.

Communication between people is difficult. A well-known example of this premise stems from asking directions in an unknown city. This can result in elaborate stories in which the narrator gives detailed and correct information concerning turns that need to be taken and landmarks that will be encountered. Yet, when left alone, the person who needs to find his way is clueless whether to turn left or right at the first crossing. These types of problems in (spatial) communication gives rise to certain questions, which are addressed in the present thesis. Are people actually able to imagine route descriptions? Or more general, how do people represent spatial information when it is "only" communicated through language? The research that is described in this thesis examines both simple spatial sentences that describe a single spatial relations and complex spatial descriptions such as a route description. Several findings from the behavioral and neuroimaging (fMRI and EEG) studies presented here support the idea that people can form spatial representations on the basis of verbal descriptions.