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Introduction Acceptance and Commitment Therapy (ACT) has developed from traditional behavioural theory and seeks to reduce experiential avoidance and increase psychological flexibility. It is argued to be distinct from cognitive therapy and has been used to treat a variety of mental health problems in addition to chronic pain. ACT is linked to Relational Frame Theory and the research developments associated with this. One central process of ACT is termed ‘cognitive defusion’ and this process is used to encourage individuals to become less identified with the content of their cognitions. It is important to measure the extent to which individuals become ‘fused’ with their cognitions and a Cognitive Fusion Questionnaire (CFQ) has been developed to do this. The current studies build upon earlier research by subjecting the CFQ to further reliability and validity testing and assessment of its factor structure. Method A community sample was used throughout. The majority of participants took part online, however, some participants completed paper copies of the questionnaires. Study one had a sample of 47 and focused on construct validity of the CFQ where participants completed this measure and also measures of similar and distinct constructs. The other measures included a mindfulness questionnaire, a measure of experiential avoidance and a social desirability questionnaire. Study two concerned the test-retest reliability of the CFQ. There were 82 participants in this study who completed the CFQ on two occasions, one month apart. In this study, participants also completed a measure of anxiety and depression symptoms. Study three had 144 participants and assessed the factor structure of the CFQ. Results Results from study one indicate that the CFQ negatively correlates with a measure of mindfulness and positively correlates with a measure of experiential avoidance. This study also found that the CFQ has no relationship with a measure of conscious attempts to appear more desirable. Results from study two show that there is a strong positive correlation between scores on the CFQ at testing time one and testing time two. The CFQ was also found to correlate positively with a measure of anxiety and depression symptoms and to mediate the relationship between anxiety scores at testing time one and testing time two. Confirmatory factor analysis was used in study three to assess the factor structure of the CFQ and found a two factor model was the best fit for the data. Discussion The results are considered in relation to relevant research. Limitations of the current studies are assessed and possibilities for future research discussed. In particular, cognitive fusion is discussed in relation to anxiety and depression symptoms. The similarities between the CFQ and a measure of experiential avoidance are discussed and the different aspects of measurement are reflected upon.

Background It has been found that both depressed patients and patients who have recovered from depression report more rumination and hold more meta-cognitive beliefs about the benefits of rumination than never-depressed controls. Furthermore, it is suggested that a ruminative cognitive style predicts the onset, length and severity of depressive episodes. Within an ACT (Acceptance and Commitment Therapy) perspective on depression, it is suggested that rumination in depression is a verbal reason-giving behaviour used to „solve‟ the problem of depressed mood. However, it is proposed that an individual‟s fusion with these verbal reasons (i.e. cognitive fusion) perpetuates rumination and impedes the adoption of more functional behaviours. The aim of this study is to investigate the relationships between depression, rumination, cognitive fusion and positive beliefs about rumination. Method A between-groups design was used comparing currently depressed adults (n = 26), recovered depressed adults (n = 21) and never depressed adults (n = 27) on a battery of self-report measures for depressive symptomatology, rumination, positive beliefs about rumination and cognitive fusion. Data were analysed using ANOVAs, post hoc comparisons, and path analysis: an extension of multiple regression. Results Significant differences were found in rumination and cognitive fusion between all three groups, with higher levels of rumination and cognitive fusion found in both the currently depressed and recovered depressed groups compared to never depressed controls. Significant differences in positive beliefs about rumination were found only between the currently depressed group and the never depressed group. Results also indicated that depression severity was best predicted by rumination and cognitive fusion rather than positive beliefs about rumination. Furthermore, the relationships between the variables of cognitive fusion and rumination (β = 0.76, p < .001), and cognitive fusion and depression (β = 0.66, p < .001), were stronger than the relationships between any of the other variables included in this study. Discussion Overall, the findings support the suggestion that cognitive fusion be considered in the conceptualisation of ruminative processes and depression. The results suggest that in individuals who have recovered from depression and are no longer clinically depressed, a difference in cognitive processes such as rumination and cognitive fusion remains. This may indicate that cognitive fusion is not secondary to depression and does appear to be implicated in the ruminative process.

Friction Stir Processing (FSP) is currently being developed for applications including as-cast Nickel- Aluminum Bronze (NAB). Fabrication and repair of the United States Navy's NAB propellers involve fusion welding of as-cast NAB and so it is probable that FSP is likely to encounter as deposited weld metal as well as the more slowly cooled as-cast material. Here, the microstructure and resulting distribution of mechanical properties was examined for a fusion weld overlay, an FSP stir zone and an FSP stir zone that was placed in fusion weld metal. As-deposited weld metal exhibited a refined WidmanstaÌ tten morphology and higher yield and ultimate strengths as well as increased ductility in comparison to base metal. However, the heat affected zone (HAZ) exhibited severely reduced ductility. Strength and ductility varied throughout the FSP stir zone. The reduction in ductility in the thermo-mechanically affected zone (TMAZ) and HAZ was less for FSP than for the fusion weld. FSP over a fusion weld resulted in strengths and ductility's similar to those produced by FSP alone, although a region of low ductility was observed at a location where stir zone weld metal and base metal were all present.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Malgré le développement des opérations de FA bancaires, toutes ne permettent pas d’augmenter la performance des entreprises concernées. En effet, le taux d’échec de ces opérations est élevé et depuis longtemps des chercheurs s’interrogent fortement sur les réelles raisons de ces échecs. Beaucoup de facteurs influençant la performance ont été avancés pour expliquer le succès ou l’échec d’une opération de FA mais ces études se sont souvent basées sur des méthodes de recherches quantitatives ne permettant pas de détecter un seul facteur précis et majeur ressortant le plus de l’ensemble des éléments influençant la performance et expliquant le résultat de l’opération de FA réalisée. En effet, une vison exclusivement financière constitue une vision étroite de ce qu’est une opération de FA bancaire, vu que son succès ou son échec dépend également de la réalisation d’unesynergie concernant les domaines stratégique, processuel, organisationnel et culturel de ces opérations. C’est dans cette optique que notre étude s’est donnée pour ambition d’examiner la problématique suivante : quel facteur déterminant explique le succès ou l’échec perçu des FA dans le secteur bancaire ? C’est donc à travers une étude qualitative, constituée et analysée par la méthode de cas multiples et composée d’un échantillon de 17 entretiens, que nos investigations tentent d’expliquer comment se fait l’arbitrage entre la performance des FA, à savoir un résultat positif ou négatif réalisé, et la perception qu’ont les acteurs, ayant vécu de près ou de loin une opération de rapprochement tel qu’une opérationde FA bancaire, de cette performance. Enfin, notre recherche montre que la dimension organisationnelle est au coeur de nos résultats ayant un impact décisif sur le résultat de l’opération de FA bancaire qu’il soit positif (succès) ou négatif (échec). / Despite of the banking M&A development, all do not allow to increase the performance of theconcerned companies. Indeed, the rate of failure of these operations is hight and since a long time, researchers wonder strongly about the real reasons of these failures. Many factors influencing the performance were moved forward to explain the success or the failure ofa M&A operation ; but these studies, have often based themselves on quantitative esearches methodsnot allowing to detect a single precise and major factor standing out most from all the elements influencing the performance and explaining the merger and acquisition result. Indeed, one exclusively financial vision constitutes a narrow vision of what a banking M&A operation is as its success or its failure also depends on the synergy realization concerning strategic domains, processuel, organizational and cultural of these operations.The mission of our study is to examine the following issue : What determining factor explains the M&A success or failure perceived in the banking sector? Through a qualitative study, constituted and analyzed by the multiples cases method (17 interviews have been conducted), our investigations have tryied to explain how the arbitration between the M&A performance is made, namely a positive or negative result realized, and the performance perceptionwhich have the actors, having lived closely or remotely a M&A opération. Finally , our research shows that the organizational dimension is at the heart of our results having adecisive impact on the M&A result whether it is positive (success) or negative (failure).

Estimation fusion, or data fusion for estimation, is the problem of how to best utilize useful information contained in multiple data sets for the purpose of estimating an unknown quantity — a parameter or a process. Estimation fusion with constraints gives rise to challenging theoretical problems given the observations from multiple geometrically dispersed sensors: Under dimensionality constraints, how to preprocess data at each local sensor to achieve the best estimation accuracy at the fusion center? Under communication bandwidth constraints, how to quantize local sensor data to minimize the estimation error at the fusion center? Under constraints on storage, how to optimally update state estimates at the fusion center with out-of-sequence measurements? Under constraints on storage, how to apply the out-of-sequence measurements (OOSM) update algorithm to multi-sensor multi-target tracking in clutter? The present work is devoted to the above topics by applying the best linear unbiased estimation (BLUE) fusion. We propose optimal data compression by reducing sensor data from a higher dimension to a lower dimension with minimal or no performance loss at the fusion center. For single-sensor and some particular multiple-sensor systems, we obtain the explicit optimal compression rule. For a multisensor system with a general dimensionality requirement, we propose the Gauss-Seidel iterative algorithm to search for the optimal compression rule. Another way to accomplish sensor data compression is to find an optimal sensor quantizer. Using BLUE fusion rules, we develop optimal sensor data quantization schemes according to the bit rate constraints in communication between each sensor and the fusion center. For a dynamic system, how to perform the state estimation and sensor quantization update simultaneously is also established, along with a closed form of a recursion for a linear system with additive white Gaussian noise. A globally optimal OOSM update algorithm and a constrained optimal update algorithm are derived to solve one-lag as well as multi-lag OOSM update problems. In order to extend the OOSM update algorithms to multisensor multitarget tracking in clutter, we also study the performance of OOSM update associated with the Probabilistic Data Association (PDA) algorithm.

BACKGROUND: The psoas major is an important muscle that is part of the iliopsoas complex, which is also known as the hip flexor and contains a major web of nerves called the lumbar plexus. The location of the lumbar plexus within the psoas muscle has been studied on cadaveric dissections previously, particularly with respect to the location of the L4 nerve root but the effect of posture on psoas morphology has not previously been studied. Hip flexion along with the potential changes in spinal alignment while in an upright sitting position may cause significant changes in the positioning and geometry of the psoas and may also change the orientation of the lumbar plexus within the muscle. Current controversy exists in determining patient suitability for Lateral Lumbar Interbody Fusion (LLIF) based on psoas morphology. Oblique and trans-psoas approaches have become a popular minimally invasive lumbar fusion technique in recent years. Lumbar plexus injury, particularly L4 nerve root injury, is a known potential complication of the oblique and trans-psoas approach and may be minimized by careful assessment of the psoas anatomy preoperatively. Quadriceps weakness as a result of L4 nerve root injury is a known potential complication of the trans-psoas approach and may be minimized by careful assessment of the psoas anatomy preoperatively. Patients may present with a sitting MRI rather than supine MRI, however, the effect of posture on the geometry of the psoas muscle, and therefore of the lumbar plexus, has not been previously reported. METHODS: We conducted a retrospective review of a single-spine surgeon practice over a 6-month period to identify patients who had undergone MRI of the lumbar spine for evaluation of degenerative spinal pathologies. Male and female patients were included if aged between 18-90 years presenting with degenerative lumbar spinal pathology between 2015-2016, and excluded if they had previous lumbar fusion, scoliosis, diagnosed with neuromuscular disease, were skeletally immature or had intrinsic abnormalities of the psoas muscles (e.g. tumor, infection or trauma). The anteroposterior (AP) dimension of the psoas muscle was measured at each disc space from L1 to L5 and compared to the AP dimension of the intervertebral disc, as measured at the inferior vertebral endplate. The AP psoas:disc ratio was then calculated and compared between patients undergoing sitting and/or supine MRIs. RESULTS: With a total of 269 patients, 113 of them were male and 157 were female. 209 patients were identified with supine-, and 60 patients with sitting- MRIs, of which 13 patients had undergone both sitting and supine MRIs (BOTH group). A propensity score match (PSM) was performed for patients undergoing either a supine or sitting MRI to match for age, BMI and gender to produce two groups of 43 patients. In the BOTH and PSM group, the sitting MRIs displayed significantly higher AP psoas:disc ratio compared with the supine MRIs at all intervertebral levels except L1-L2. The largest difference observed was a mean 32-37% increase in sitting AP psoas:disc ratio at the L4-L5 disc in sitting MRIs compared to supine MRIs in the BOTH group (range 0-137%). CONCLUSIONS: The psoas muscle and the lumbar plexus became anteriorly displace in sitting MRIs, with a greater effect noted at caudal intervertebral discs. This may have implication in selection suitability for LLIF and intra-operative patient positioning.

P2X4 receptors (P2X4R) are ligand-gated ion channels activated by ATP and with a high permeability to Ca2+. They are predominantly localised to lysosomes and from there can traffic to the cell surface. ATP levels within the lysosome are high but P2X4Rs are inhibited by the acidic pH. Previously, it was shown that the alkalinisation of lysosomes using pharmacological reagents was sufficient to activate P2X4Rs, which promoted homotypic lysosome fusion. The main aim of this study was to identify physiological regulators of lysosomal P2X4Rs and to examine their role in lysosome Ca2+ signalling and fusion. The first candidate I investigated was P2X7R, which is typically co-expressed with P2X4R in immune and epithelial cells, and which has already been shown to induce changes in lysosome properties upon activation. I co-expressed these two receptors in normal rat kidney (NRK) cells and in HeLa cells and looked for a synergistic interaction between them in promoting lysosome fusion, as assessed by measuring the size of lysosomes. My results showed a significant increase in lysosome size following activation of P2X7R but only in the presence of P2X4R. Neither receptor alone was sufficient to promote lysosome fusion in response to the agonist BzATP. LAMP-GECO was used to measure changes in cytosolic [Ca2+] within the vicinity of the lysosome. Fusion of the Ca2+ reporter (GECO) to the C-terminus of LAMP-1 targets GECO to the cytosolic surface of the lysosome. Co-expression of P2X4R with P2X7R augmented the P2X7R-induced Ca2+ signal suggesting that P2X4Rs mediate lysosomal Ca2+ efflux downstream of P2X7R stimulation. Next, I showed that the expression of P2X4R was sufficient to enhance the cytosolic Ca2+ response to the activation of endogenous histamine H1 receptors and to promote lysosome fusion. Similar results were obtained with P2Y2R stimulation, which also couples to the phospholipase C pathway. Further experiments were conducted to look at differences in the trafficking behaviour of human and rat P2X4Rs and to examine a role for P2X4Rs in autophagic flux. My results suggest a synergistic interaction between P2X4R and P2X7R which inhibits autophagic flux, similar to the effect of bafilomycin treatment. Therefore, the effect of P2X4/7R in autophagy may be mediated by the alkalinisation of lysosomes. Altogether the results of my project improve our understanding of how the P2X4R Ca2+ channel regulates lysosome function.