Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

The need for assessment of benthic habitat characteristics may arise for many reasons. Such reasons may include but are not limited to, habitat mapping, environmental concerns and identification of submerged aquatic vegetation. Oftentimes, such endeavors employ the use of aerial photography, satellite imagery, diving transects and extensive sampling. Aerial photography and remote sensing techniques can be severely limited by water clarity and depth, whereas diver transects and extensive sampling can be time consuming and limited in spatial extent. Acoustic methods of seabed mapping, such as the acoustic sediment classification system QTC are not hampered by water clarity issues. The acoustic sediment classification system QTC is capable of providing greater spatial coverage in fractions of the time required by divers or point sampling. The acoustic classification system QTC VIEW VTM was used to map benthic habitats within Tampa Bay. The QTC system connected in parallel to an echo-sounder is capable of digitally extracting and recording echoes returning from the seabed. Recorded echoes were processed using QTC IMPACTTM software. This software partitions echo waveforms into groups or classes based on their similarity to one another using multivariate statistics, namely Principal Component Analysis and K-Means clustering. Data was collected at two frequencies, 50 kHz and 200 kHz. Side-scan sonar data was collected coincident with the QTC data and used to produce mosaics of the various habitats in Tampa Bay. Side-scan sonar data was classified using QTC SideviewTM in an attempt to identify changes in benthic habitats. Sediment samples used for ground-truth were subjected to grain size analysis. Also, the percentage of organic matter and carbonate within samples was determined. Results of acoustic classification appear to accurately reflect changes in the sediment type and structure of the seabed. Grain size, particularly percent mud, appears to have a strong influence on classification. Carbonate hard bottom habitats were found to be acoustically complex, a characteristic useful for their identification. The QTC system was able to detect seagrass, although some misclassification occurred between vegetated and non-vegetated seabeds.

A single-beam acoustic seabed classification system was used to map coral reef environments in the upper Florida Keys, USA, and the Bahamas. The system consisted of two components, both produced by the Quester Tangent Corporation. A QTCView Series V, operating with a 50 kHz sounder, was used for data acquisition, and IMPACT software was used for data processing and classification. First, methodological aspects of system performance were evaluated. Second, the system was applied to the assessment of grouper and snapper habitat. Two methodological properties were explored: transferability (i.e. mapping the same classes at multiple sites) and reproducibility (i.e. surveying one site multiple times). The transferability results showed that a two-class scheme of hard bottom and sediment could be mapped at four sites with overall accuracy ranging from 73% to 86%. The locations of most misclassified echoes had one of two characteristics: a thin sediment veneer overlying hard bottom or within-footprint relief on the order of 0.5 m or greater. Reproducibility experiments showed that consistency of acoustic classes between repeat transects over the same area on different days varied, for the most part, between 50% and 65%. Consistency increased to between 78% and 92% when clustering was limited to two acoustic classes, to between approximately 70% and 100% when only echoes acquired within two degrees of nadir in the pitch direction were used, and to between 81% and 87% when a limited set of features was used for classification. The assessment of grouper and snapper habitat addressed the question whether areas of high fish abundance were associated with characteristic acoustic or geomorphological signatures. The results showed, first, that the hard bottom / sediment classification scheme was a useful first step for stratifying survey areas to increase efficiency of grouper census efforts. Second, an index of acoustic variability complemented the hard bottom / sediment classification by further targeting areas of potential grouper habitat. Finally, five grouper and snapper spawning aggregation sites were all found to have similar associations with drowned shelf edge reefs in the upper Florida Keys.

Myxedema coma and pituitary apoplexy are well-known life-threatening endocrine emergencies. The coincidence of these entities is exceedingly rare. Myxedema coma occurring as a result of pituitary lesion is a much less seen entity. A high index of suspicion is often required for early diagnosis as it is of particular importance in improving survival outcomes. We present a rare case of a patient with myxedema coma presenting as bradycardia and hypotension secondary to pituitary apoplexy, which was confirmed on magnetic resonance imaging (MRI). The patient was managed conservatively with levothyroxine and stress doses of steroid, with the resolution of hemodynamic changes and a decrease in the size of the suprasellar mass.

Hand proprioception is crucial for daily activities and may be compromised by diseases or injuries,impacting patients' independence. The lack of feasible, accurate, and affordable clinical tools forhand proprioception assessment poses a significant challenge, essential for identifying dysfunctionand evaluating treatment effects.The purpose of this study was to evaluate the concurrent validity of the LeapMotion controller(LMC) for assessing hand proprioception. We compared the LMC with a 3D camera system formotion analysis (Qualisys Motion Capture, QTM), known for its high measurement accuracy as thegold standard. Twenty participants (10 men, 10 women), 15 without, and 5 with hand injury or pain,took part in this cross-sectional study. Assessments included pointing acuity with open and closedeyes using the right and left hand. There were moderate to good correlations between LMC andQTM performed with closed eyes, with intraclass correlation coefficient (ICC) values of 0.6 and0.89. Contrary, tests with open eyes showed a poor overall correlation with ICC between 0.003 and0.3. Bland-Altman analysis showed median biases of≤ 1.5 mm between LMC and QTM with eyes open, and ≤ 5.1 mm with eyes closed. Limits ofagreement ranged from -0.4 to 3.5 mm with eyes open and -31.6 to 21.5 mm with eyes closed.The results indicate that the LMC could be a cost-effective and feasible tool for quantifying handproprioception with a clinically acceptable bias. Although the median biases were small formeasurements with eyes open, the ICCs were poor. This may be due to a high pointing acuity withinthe group combined with limited variability between the participants in the eyes open tests.

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In 2011 Manitoba experienced an extreme flood. The operation of the Assiniboine River Diversion resulted in the addition of approximately 1.72 million cubic decameters of water to Lake Manitoba and an increase in water levels to 1.5 m above normal. Although this event resulted damage to farmland and many local homes, it also provided me the unique opportunity to utilize previously impractical methods of bathymetric and substrata distribution analysis in the adjoining Delta Marsh. Combined with satellite imagery taken in 2011 I was able to classify the vegetation classes within the study area and explore the relationship between vegetation distributions and water depth as well as those between water depth and substrata distribution. A seed bank study was carried out to explore the diversity of viable seeds in the area. In addition, satellite imagery taken in 2009 was used to evaluate the effects of the flood event experienced in 2011. / October 2015

At present, doctors are not consistent in the way they set the QTc interval in the recovery phase. The main goal of this study was to screen healthy subjects in the two different exercise stress tests and to compare the obtained data from both tests. We wanted to explore whether the heart rate and the QTc interval differs from each other when performed in two different body positions during the recovery phase. The main purpose was to present evidence that would prove or disprove a hypothesis that the figures differ in the different body positions. In the theoretical part we submitted the main information about the heart rate, the QT interval and the relationship between them. We compared the behaviour of the obtained data during the exercise and during the recovery phase. We described the causes of the QTc prolongation and how it is related to the cardiac arrhythmias. In the practical part we examined 20 healthy subjects. Each of them underwent two exercise stress tests on the bicycle ergometer, up to the subjective maximum level of the exercise intensity. The subjects then recovered in two different positions. The first one was a supine position. The second rest position was on the bicycle ergometer set to very low intensity. We found out that the 4-minute recovery phase, the most important for...

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A growing recognition of the need for effective marine environmental management as a result of the increasing exploitation of marine biological resources has highlighted the need for high speed ecological seabed mapping. The practice of mapping making extensive use of satellite remote sensing and airborne platforms is well established for terrestrial management. Marine biological resource mapping however is not readily available except in part from that derived for surface waters from satellite based ocean colour mapping. Perhaps the most fundamental reason is that of sampling difficulty, which involves broad areas of seabed coverage, irregularities of seabed surface and depth. Conventional grab sample techniques are widely accepted as a standard seabed mapping methodology that has been in use long before the advent of acoustic techniques and continue to be employed. However. they are both slow and labour intensive, factors which severely limit the spatial coverage available from practical grab sampling programs. While acoustic techniques have been used for some time in pelagic biomass assessment, only recently have acoustic techniques been applied to marine biological resource mapping of benthic communities. Two commercial bottom classifiers available in the market that use normal incidence echosounders are the RoxAnn and QTC View systems. Users and practitioners should be cautious however when using black box implementations of the two commercial systems without a proper quality control over raw acoustic data since some researchers in their studies have indicated problems with these two bottom classifiers such as, among others, a depth dependence. In this thesis, an alternative approach was adopted to the use of echosounder returns for bottom classification. / The approach used in this study is similar to,~ used in the commercial RoxAnn system. In grouping bottom types however, Multivariate analysis (Principal Component Analysis and Cluster Analysis) was adopted instead of the allocation system normally used in the RoxAnn system, called RoxAnn squares. In addition, the adopted approach allowed for quality control over acoustic data before further analysis was undertaken. As a working hypothesis, it was assumed that on average 0 and aE2 = 0 where E1 and E2 are the roughness and hardness indices, respectively, and RO is the depth. For roughness index (E1), this was achieved by introducing a constant angular integration interval to the tail of the first OM returns whereas for hardness index (E2), this was achieved by introducing a constant depth integration interval. Since three different frequencies, i.e. 12, 38 and kHz, were operated, Principal Component Analysis was used here to reduce the dimensionality of roughness and hardness indices, formed from the three operated qu frequencies separately. The k-means technique was applied to the first principal component of roughness index and the first principal comp component of hardness index to produce separable seabed types. This produced four separable seabed types, namely soft-smooth, soft-rough, hard-smooth and hard-rough seabeds. / Principal Component Analysis was also used to reduce the dimensionality of the area backscattering coefficient sA, a relative measure of biomass of benthic mobile biota. The bottom classification results reported here appear to be robust in that, where independent ground truthing was available, acoustic classification was generally congruent with ground truth results. When investigating the relationship between derived bottom type and acoustically assessed total biomass of benthic mobile biota, no trend linking the two parameters, however, appears. Nevertheless, using the hierarchical agglomerative technique applied to a set of variables containing average first principal component of the area backscattering coefficient sA, the average first principal component of roughness and hardness indices, the centroids of first principal component of roughness and hardness indices associated with the four seabed types and species composition of fish group of the common species in trawl stations available, two main groups of quasi acoustic population are observed in the North West Shelf (NWS) study area and three groups are observed in the South East Fisheries (SEF) study area. The two main groups of quasi acoustic population in the NWS study area and the three main groups of quasi acoustic population in the study area are associated with the derived seabed types and fish groups of the common species.