A técnica de \"Inflow Occlusion\" pode ser utilizada em cirurgias cardíacas quando se pretende manter o coração aberto apenas por alguns minutos, para realização de pequenos reparos. No entanto, a parada circulatória total, evento decorrente da técnica em questão, pode acarretar severas alterações metabólicas e neurológicas, sendo necessária monitorização trans e pósoperatória do paciente. Neste estudo foram utilizados 12 cães sem raça definida, os quais foram divididos em dois grupos, A e B, submetidos a 7 e 8 minutos de parada circulatória total, respectivamente, utilizando-se da técnica de \"Inflow Occlusion\". Tentou-se estabelecer normotermia dos animais durante os procedimentos cirúrgicos. Foram realizados exames hemogasométricos, e avaliações clínica e neurológica nos momentos preconizados. Alterações neurológicas transitórias foram observadas em ambos os grupos. Ocorreram dois óbitos transoperatórios no grupo B, e um animal do mesmo grupo apresentou cegueira permanente no período pós-operatório. Apesar da acidose metabólica observada durante os procedimentos, o pH, pressão parcial de dióxido de carbono no sangue arterial, e bicarbonato plasmático arterial de ambos os grupos, retornaram aos valores normais após trinta minutos da parada circulatória. Apesar das alterações observadas, é lícito afirmar que o \"Inflow Occlusion\" é seguro por até 7 minutos. Após este período, no entanto, é contra-indicado, segundo resultados obtidos e óbitos transoperatórios relatados. / \"Inflow Occlusion\" technique can be used in heart surgeries when heart is required to be opened just for few minutes, to allow quick repairs. However, circulatory arrest, event occasioned by this technique, can produce serious metabolic and neurologic consequences to the patient, and monitorization on trans, and postoperatory moments is well recommended. In this study, 12 mongrel dogs were used, and were divided into two groups, A and B, submmited to 7 and 8 minutes of total circulatory arrest, respectively, using \"Inflow Occlusion\" technique. Normothermia was tried during surgical procedures. Hemogasometric analysis, and clinical and neurological exams were made, each of them, on the moments established for the experiment. There were some transitory neurological problems related to both groups. There were two transoperatory deaths in group B and one case of permanent blindness in the same group, on postoperatory period. Despite metabolic acidosis occurred during procedures, pH values, arterial dioxide carbon parcial pressure, and arterial plasmatic bicarbonate related to both groups, returned to basal levels thirty minutes after surgery. Even occuring some hemogasometric and neurologic alterations, we can say that \"Inflow Occlusion\" is safe for periods up to 7 minutes. After this period of time, however, it is contraindicated, as seen after these results and because transoperatory deaths.

PURPOSE: This study aims to quantify the retinal vascular blood flow in eyes affected by unilateral central retinal vein occlusions (CRVO) or branch retinal vein occlusions (BRVO). We created and explored a new, unitless metric for the severity of these diseases: relative blood flow (RBF). We then contextualized RBF in terms of patient demographics, ocular presentation and other systemic conditions, as well as explored its efficacy as a predictor of future outcomes. METHODS: Data was collected from 20 control subjects and 32 patients with clinically diagnosed retinal vein occlusions (15 CRVO and 17 BRVO). Laser speckle flowgraphy was then used to quantify retinal vascular blood flow in terms of mean blur rate, a metric shown to be highly heterogeneous between patients but fairly consistent in intra-patient repeated measurements over time. After confirming this and establishing a strong correlation between a healthy patient’s two eyes, we used an RVO patient’s fellow eye as a nondiseased expectation and presented relative blood flow as the ratio between their diseased and healthy eye. We then correlated this data with demographic variables and disease characteristics from patients’ medical history. RESULTS: We found an average blood flow decrease of 26% in CRVO eyes relative to healthy eyes in the same patients and an average decrease of 7% in BRVO eyes. In CRVO, duration of occlusion, central macular thickness, intraocular pressure, diabetes, previous laser and injection treatments, and an injection within three months after blood flow measurement were significantly associated with relative blood flow. In BRVO, no demographic variables or disease characteristics were significantly associated with relative blood flow. CONCLUSIONS: Relative blood flow represents a promising new, consistent and informative metric for quantifying the severity of unilateral retinal vein occlusions. With both descriptive and predictive properties in eyes with CRVO, future work should explore its great potential.

BACKGROUND:We tested the hypothesis that ventilatory drive in hypoxia and hypercapnia is inversely correlated with the number of hypopneas and obstructive apneas per hour of sleep (obstructive apnea hypopnea index, OAHI) in children.METHODS:Fifty children, 6 to 12 years of age were studied. Participants had an in-home unattended polysomnogram to compute the OAHI. We subsequently estimated ventilatory drive in normoxia, at two levels of isocapnic hypoxia, and at three levels of hyperoxic hypercapnia in each subject. Experiments were done during wakefulness, and the mouth occlusion pressure measured 0.1 seconds after inspiratory onset (P0.1) was measured in all conditions. The slope of the relation between P0.1 and the partial pressure of end-tidal O2 or CO2 (PETO2 and PETCO2) served as the index of hypoxic or hypercapnic ventilatory drive.RESULTS:Hypoxic ventilatory drive correlated inversely with OAHI (r = -0.31, P = 0.041), but the hypercapnic ventilatory drive did not (r = -0.19, P = 0.27). We also found that the resting PETCO2 was significantly and positively correlated with the OAHI, suggesting that high OAHI values were associated with resting CO2 retention.CONCLUSIONS:In awake children the OAHI correlates inversely with the hypoxic ventilatory drive and positively with the resting PETCO2. Whether or not diminished hypoxic drive or resting CO2 retention while awake can explain the severity of sleep-disordered breathing in this population is uncertain, but a reduced hypoxic ventilatory drive and resting CO2 retention are associated with sleep-disordered breathing in 6-12 year old children.

This thesis deals with the problem of online visual tracking of multiple humans in an enclosed environment. The focus is to develop techniques to deal with the challenges of varying number of targets, inter-target occlusions and interactions when every target gives rise to multiple measurements (pixels) in every video frame. This thesis contains three different contributions to the research in multi-target tracking. Firstly, a multiple target tracking algorithm is proposed which focuses on mitigating the inter-target occlusion problem during complex interactions. This is achieved with the help of a particle filter, multiple video cues and a new interaction model. A Markov chain Monte Carlo particle filter (MCMC-PF) is used along with a new interaction model which helps in modeling interactions of multiple targets. This helps to overcome tracking failures due to occlusions. A new weighted Markov chain Monte Carlo (WMCMC) sampling technique is also proposed which assists in achieving a reduced tracking error. Although effective, to accommodate multiple measurements (pixels) produced by every target, this technique aggregates measurements into features which results in information loss. In the second contribution, a novel variational Bayesian clustering-based multi-target tracking framework is proposed which can associate multiple measurements to every target without aggregating them into features. It copes with complex inter-target occlusions by maintaining the identity of targets during their close physical interactions and handles efficiently a time-varying number of targets. The proposed multi-target tracking framework consists of background subtraction, clustering, data association and particle filtering. A variational Bayesian clustering technique groups the extracted foreground measurements while an improved feature based joint probabilistic data association filter (JPDAF) is developed to associate clusters of measurements to every target. The data association information is used within the particle filter to track multiple targets. The clustering results are further utilised to estimate the number of targets. The proposed technique improves the tracking accuracy. However, the proposed features based JPDAF technique results in an exponential growth of computational complexity of the overall framework with increase in number of targets. In the final work, a novel data association technique for multi-target tracking is proposed which more efficiently assigns multiple measurements to every target, with a reduced computational complexity. A belief propagation (BP) based cluster to target association method is proposed which exploits the inter-cluster dependency information. Both location and features of clusters are used to re-identify the targets when they emerge from occlusions. The proposed techniques are evaluated on benchmark data sets and their performance is compared with state-of-the-art techniques by using, quantitative and global performance measures.

published_or_final_version / Dentistry / Master / Master of Dental Surgery

In order to grasp an object in their visual field, humans orient their visual axis to targets of interest. While scanning their environment, humans perform multiple saccades (rapid eye movements that correct for a position error between eye and target) to align their visual axis with objects of interest. Humans are also able to track objects that move in their environment by means of smooth pursuit eye movements (slow eye movements that correct for any velocity error between eye and target, i.e. for any retinal slip). The appearance of a moving stimulus in the environment elicits smooth pursuit eye movements with a latency of around 100ms. Accordingly, the smooth pursuit system accounts for a change in the trajectory of a moving target with a similar delay. Due to this delay, the oculomotor system needs to develop strategies to avoid the build up of position error during tracking of a moving target. To do so, the oculomotor system uses prediction to try and anticipate the future target trajectory. However, this strategy is limited to conditions where target trajectory is predictable. Otherwise, primates have to combine pursuit and saccades in visual tracking of unpredictable moving targets to avoid large position error. This thesis focuses on both the prediction mechanisms and the interactions between saccades and pursuit. In order to investigate prediction mechanisms, we asked human subjects to pursue a moving target when it was transiently occluded. During occlusions, subjects continued to pursue the invisible target. This thesis demonstrates that this predictive pursuit response is based on a dynamic internal representation of target motion, i.e. a representation that evolves with time. This internal representation could be either built up by repetition of the same target motion or extrapolated on the basis of the pre-occlusion target motion. In addition, it is shown that during occlusions, saccades are adjusted in order to account for the large variability of the smooth pursuit response. As a consequence, it shows that the smooth pursuit command is used by internal models in order to predict future smooth pursuit response. These results demonstrate that both prediction and internal models are necessary to track the invisible and the visible.

Objective: The purpose was to compare orthodontists’ and parents’ perception of orthodontic treatment outcomes in the anterior-posterior (AP) dimension. Assessment of treatment time and compliance were also investigated. Material and Methods: Parallel surveys for orthodontists (n=1000) and parents (n=750) displayed occlusions from 3 mm Class III (Cl III:3) to 3 mm Class II. Participants rated occlusal relationships on a 100 mm VAS from least to most acceptable (0-100). Results: 233 orthodontists (23%) and 243 parents (32%) responded. Orthodontists (mean=93.9, 25.9) and parents (mean=80.7, 40.9) rated Class I (Cl I) occlusion most and Cl III:3 least acceptable. No significant difference was found between outcomes at 18 months versus 24 months. For all cases, parents were willing to extend treatment duration longer than orthodontists. Conclusions: Orthodontists and parents viewed treatment outcomes in the AP dimension differently, rating Cl I as most acceptable. Parents were willing to extend treatment longer than orthodontists.

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

Devido à incompatibilidade entre as medidas cefalométricas e a análise facial de alguns casos de retrusão de maxila, e a ausência de estudos que indiquem essa variação e sua implicação no diagnóstico e tratamento dos pacientes, o objetivo desta pesquisa foi determinar: a média e o desvio padrão do ângulo nasolabial (ANL) e da medida linear Prn-A em repouso e sorrindo e a diferença entre sorriso e repouso, em indivíduos com oclusão normal e harmonia facial, além de avaliar a presença de dimorfismo sexual. A amostra constituiu-se de 40 participantes brasileiros, sendo 20 de cada sexo, leucodermas, de faixa etária de 20 a 30 anos de idade, com oclusão normal, perfil facial agradável e harmonia facial. Foram analisadas, nas fotografias de perfil em repouso e sorrindo, com uma régua milimetrada à frente do perfil, e com a utilização do programa Dolphin, as medidas ANL e Prn-A. A análise estatística incluiu a estatística descritiva, testes t dependentes para comparar as variáveis em repouso e sorrindo, e testes t independentes para avaliar o dimorfismo sexual. Como resultados, observou-se que: a média do ANL em repouso foi de 104,93º, com desvio padrão de 8,04, e sorrindo, foi de 110,67º, com desvio padrão de 9,01, sendo que a diferença entre eles foi estatisticamente significante, com média 5,74º e desvio de padrão de 4,11. A média da variável linear Prn-A em repouso foi de 23,25mm, com desvio padrão de 1,95, e sorrindo, foi de 24,04mm, com desvio padrão de 2,07, sendo que a diferença entre eles foi estatisticamente significante, com média 0,79mm e desvio de padrão de 0,65. Não houve dimorfismo sexual para o ANL. A medida Prn-A em repouso e sorrindo se mostrou maior para o sexo masculino quando comparado ao sexo feminino. / Due to the incompatibility of the cephalometric measurements and the facial analysis in some cases of maxillary retrusion, and the absence of studies that indicate this variation and implication in diagnosis and treatment of the patients, the objective of this study was to determine: the mean and standard deviation of the nasolabial angle (NLA) and the linear measure Prn-A during rest and smile and the difference between smile and rest, in subjects with normal occlusion and facial harmony, besides of evaluating the presence of sexual dimorphism. The sample comprised 40 Brazilian subjects, 20 of each sex, leucoderms, aging from 20 to 30 years, with normal occlusion, pleasant facial profile and facial harmony. It was analyzed, in profile photographs in rest and during smile, with a millimeter ruler in front of the profile, and using the Dolphin software, the measures NLA and Prn-A. The statistical analysis included descriptive statistics and dependent t tests to compare the rest and smiling variables and independent t tests to evaluate sexual dimorphism. As results, it was observed that: the mean of the NLA in rest was 104,93º, with a standard deviation of 8,04, and during smile, it was of 110,67º, with standard deviation of 9,01, and the difference between them was statistically significant, with mean of 5,74º and standard deviation of 4,11. The mean of the linear variable Prn-A in rest was of 23,25mm, with standard deviation of 1,95, and during smile, it was of 24,04mm, with standard deviation of 2,07, and the difference between them was statistically significant, with mean of 0,79mm and standard deviation of 0,65. There was no sexual dimorphism for the NLA. The measure Prn-A in rest and during smile showed greater for the males, when compared to females.

A relação oclusal dos arcos dentários de 105 bebês brasileiros com idades entre 1 a 3 anos, foi avaliada neste estudo. Estes apresentaram os seguintes requisitos para participarem da amostra: presença de dentes decíduos hígidos (sem cárie ou qualquer tipo de anomalia de forma e estrutura), sem histórico de traumatismo dentário e assimetrias, maxilar e facial. A amostra foi dividida em 4 grupos: Grupo 1: Bebês que apresentem no mínimo quatro incisivos, sendo dois superiores e dois inferiores irrompidos; Grupo 2: Bebês que apresentem incisivos e primeiros molares irrompidos; Grupo 3: Bebês que apresentem incisivos, primeiros molares e caninos irrompidos; Grupo 4 : Bebês que apresentem incisivos, primeiros molares, caninos e segundos molares irrompidos. A avaliação constou de exame clínico de cada criança e a análise das respostas dos questionários preenchidos pelos responsáveis. Os dados encontrados foram tabulados e analisados através de análise descritiva. Os resultados deste estudo sugerem que as más oclusões aparecem em uma época precoce do desenvolvimento da dentição decídua em 19,05% das crianças estudadas. / The aim of the present study was to evaluate the oclusal relationship of the dental arch of 105 brasilian babies with age from 1 to 3 years old. The sample showed the following characteristics: presence of primary teeth (without dental decay or any kind of size or structure anomaly), without dental injuries or maxilar/mandibular assimetry. The sample was divided into 4 following groups: Group 1: Babies showing four incisors at least, being two upper and two lower erupted incisive teeth; Group 2: Babies showing incisors and erupted first molars; Group 3: Babies showing incisors, first molars and erupted canines; Group 4: Babies showing incisors, first molars, canines and erupted second molars. The evaluation was compound by clinical exam of each child and by analysis of the answers from questionary given to the guardians. The data was analyzed through descriptive analysis. The results pointed out that malocclusions presented in 19,05% of the sample on early age of the primary teeth development.