Region-dependent vehicle classification using PCA features

Video-based vehicle detection is the focus of increasing interest due to its potential towards collision avoidance. In particular, vehicle verification is especially challenging due to the enormous variability of vehicles in size, color, pose, etc. In this paper, a new approach based on supervised learning using Principal Component Analysis (PCA) is proposed that addresses the main limitations of existing methods. Namely, in contrast to classical approaches which train a single classifier regardless of the relative position of the candidate (thus ignoring valuable pose information), a region-dependent analysis is performed by considering four different areas. In addition, a study on the evolution of the classification performance according to the dimensionality of the principal subspace is carried out using PCA features within a SVM-based classification scheme. Indeed, the experiments performed on a publicly available database prove that PCA dimensionality requirements are region-dependent. Hence, in this work, the optimal configuration is adapted to each of them, rendering very good vehicle verification results.

Essais de Chymie, sur la chaux vive, la matiere elastique et electrique, le feu, et l'acide universel primitif : avec un supplément sur les eléments /

Mode of access: Internet.

Description and critical appraisal of principal components analysis (PCA) methodology applied to pulsed-field gel electrophoresis profiles of methicillin-resistant Staphylococcus aureus isolates

Principal components analysis (PCA) has been described for over 50 years; however, it is rarely applied to the analysis of epidemiological data. In this study PCA was critically appraised in its ability to reveal relationships between pulsed-field gel electrophoresis (PFGE) profiles of methicillin- resistant Staphylococcus aureus (MRSA) in comparison to the more commonly employed cluster analysis and representation by dendrograms. The PFGE type following SmaI chromosomal digest was determined for 44 multidrug-resistant hospital-acquired methicillin-resistant S. aureus (MR-HA-MRSA) isolates, two multidrug-resistant community-acquired MRSA (MR-CA-MRSA), 50 hospital-acquired MRSA (HA-MRSA) isolates (from the University Hospital Birmingham, NHS Trust, UK) and 34 community-acquired MRSA (CA-MRSA) isolates (from general practitioners in Birmingham, UK). Strain relatedness was determined using Dice band-matching with UPGMA clustering and PCA. The results indicated that PCA revealed relationships between MRSA strains, which were more strongly correlated with known epidemiology, most likely because, unlike cluster analysis, PCA does not have the constraint of generating a hierarchic classification. In addition, PCA provides the opportunity for further analysis to identify key polymorphic bands within complex genotypic profiles, which is not always possible with dendrograms. Here we provide a detailed description of a PCA method for the analysis of PFGE profiles to complement further the epidemiological study of infectious disease. © 2005 Elsevier B.V. All rights reserved.

Neuropathological changes in ten cases of neuronal intermediate filament inclusion disease (NIFID):A study using α-internexin immunohistochemistry and principal components analysis (PCA)

Ten cases of neuronal intermediate filament inclusion disease (NIFID) were studied quantitatively. The α-internexin positive neurofilament inclusions (NI) were most abundant in the motor cortex and CA sectors of the hippocampus. The densities of the NI and the swollen achromatic neurons (SN) were similar in laminae II/III and V/VI but glial cell density was greater in V/VI. The density of the NI was positively correlated with the SN and the glial cells. Principal components analysis (PCA) suggested that PC1 was associated with variation in neuronal loss in the frontal/temporal lobes and PC2 with neuronal loss in the frontal lobe and NI density in the parahippocampal gyrus. The data suggest: 1) frontal and temporal lobe degeneration in NIFID is associated with the widespread formation of NI and SN, 2) NI and SN affect cortical laminae II/III and V/VI, 3) the NI and SN affect closely related neuronal populations, and 4) variations in neuronal loss and in the density of NI were the most important sources of pathological heterogeneity. © Springer-Verlag 2005.

Implication de la convertase NARC-1 / PCSK9 au cours de la différenciation neuroectodermale

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

Implication de la convertase NARC-1 / PCSK9 au cours de la différenciation neuroectodermale

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

The application of PCA as a movement pattern recognition technique: A proof of principle

Quantitative methods can help us understand how underlying attributes contribute to movement patterns. Applying principal components analysis (PCA) to whole-body motion data may provide an objective data-driven method to identify unique and statistically important movement patterns. Therefore, the primary purpose of this study was to determine if athletes’ movement patterns can be differentiated based on skill level or sport played using PCA. Motion capture data from 542 athletes performing three sport-screening movements (i.e. bird-dog, drop jump, T-balance) were analyzed. A PCA-based pattern recognition technique was used to analyze the data. Prior to analyzing the effects of skill level or sport on movement patterns, methodological considerations related to motion analysis reference coordinate system were assessed. All analyses were addressed as case-studies. For the first case study, referencing motion data to a global (lab-based) coordinate system compared to a local (segment-based) coordinate system affected the ability to interpret important movement features. Furthermore, for the second case study, where the interpretability of PCs was assessed when data were referenced to a stationary versus a moving segment-based coordinate system, PCs were more interpretable when data were referenced to a stationary coordinate system for both the bird-dog and T-balance task. As a result of the findings from case study 1 and 2, only stationary segment-based coordinate systems were used in cases 3 and 4. During the bird-dog task, elite athletes had significantly lower scores compared to recreational athletes for principal component (PC) 1. For the T-balance movement, elite athletes had significantly lower scores compared to recreational athletes for PC 2. In both analyses the lower scores in elite athletes represented a greater range of motion. Finally, case study 4 reported differences in athletes’ movement patterns who competed in different sports, and significant differences in technique were detected during the bird-dog task. Through these case studies, this thesis highlights the feasibility of applying PCA as a movement pattern recognition technique in athletes. Future research can build on this proof-of-principle work to develop robust quantitative methods to help us better understand how underlying attributes (e.g. height, sex, ability, injury history, training type) contribute to performance.

Eficacia de la ropivacaína 0,1% intraperitoneal en el control del dolor postoperatorio en cirugía ginecológica laparoscópica

Introducción: Determinar la eficacia de la administración preincisional de ropivacaína al 0,1 % intraperitoneal en el control del dolor abdominal y/o de hombro, durante la primera semana de la cirugía laparoscópica ginecológica benigna. Diseño: Ensayo clínico aleatorizado y doble ciego. Material y métodos: Se realizó un ensayo clínico aleatorizado y doble ciego donde participaron 64 pacientes ASA I-III sometidas a cirugía laparoscópica ginecológica por patología benigna. Tras la realización del neumoperitoneo, se administraron 100 ml de ropivacaína 0,1 % o suero fisiológico intraperitoneal, dependiendo del grupo al que pertenecieran. Las pacientes recibieron, además, AINE junto con una bomba de PCA con opción de morfina de rescate como analgesia multimodal asociada. Se evaluó el dolor abdominal y/o de hombro al despertar, en reposo y en movimiento, a los 5, 30, 60 y 120 minutos, así como a las 24 horas. Se registró el consumo de morfina en las primeras 24 horas y la incidencia de náuseas y/o vómitos postoperatorios. A la semana, mediante encuesta telefónica, se registró la presencia de dolor de hombro a partir de las 24 horas, así como de dolor abdominal persistente al 7º día. Resultados: No se observaron diferencias significativas en el ENV durante las primeras 24 horas. Tampoco se observaron diferencias en el consumo de morfina, en la incidencia de náuseas y/o vómitos o en el dolor de hombro. Se evidenciaron diferencias estadísticamente significativas en la incidencia de dolor abdominal persistente al 7º día (18,52 % en grupo tratamiento vs. 57,58 % en grupo control con p = 0,04). Conclusiones: La administración intraperitoneal preincisional de 100 ml de ropivacaína 0,1 % en comparación con la administración de suero fisiológico, en el contexto de una técnica anestésica y analgésica multimodal, no ha demostrado reducir el dolor postoperatorio, el consumo de opioides ni la incidencia de náuseas y vómitos postoperatorios en las primeras 24 horas. Tampoco ha demostrado reducción del dolor de hombro a partir del primer día tras cirugía laparoscópica ginecológica. El uso de ropivacaína al 0,1 % intraperitoneal preincisional presenta una disminución estadísticamente significativa en la incidencia de dolor abdominal persistente al séptimo día de postoperatorio.