The problem of face detection and recognition within a given database has become one of the important problems in computer vision. A simple approach for Face Detection in video is to run a learning based face detector every frame. But such an approach is computationally expensive and completely ignores the temporal continuity present in videos. Moreover the search space can be reduced by utilizing visual cues extracted based on the relevant task at hand(top down approach). Once detection is done next step is to perform a face recognition based on the available database. But the faces detected from face detect or output is neither aligned nor well cropped and is prone to scale change. We call such faces as free form faces. But the current existing algorithms on face recognition assume faces to be properly aligned and cropped, and having the same scale as the faces in the database, which is highly constrained. In this thesis, we propose an integrated detect-track framework for Multiview face detection in videos. We overcome the limitations of the frame based approaches, by utilizing the temporal continuity present in videos and also incorporating the top down information of the task. We model the problem based on the concept from Experiential sampling [2]. This consists of determining certain key positions which are relevant to the task(face detection). These key positions are referred to as attention samples and Multiview face detection is performed only at these locations. These statistical samples are estimated based on the visual cues, past experience and the temporal continuity and is modeled as a Bayesian filtering problem, which is solved using Particle Filters. In order to detect all views we use a tracker integrated with the detector and come out with a novel track termination algorithm using the concepts from Track Before Detect(TBD)[26]. Such an approach is computationally efficient and also results in lower false positive rate. We provide experiments showing the efficiency of the integrated detect-track approach over the multiview face detector approach without a tracker. For free form face recognition we propose to use the concept of Principal Geodesic Analysis(PGA) of the Covariance descriptors obtained from Gabor filters. This is similar to Principal Component Analysis in Euclidean spaces (Covariance descriptors lie on a Riemannian manifold). Such a descriptor is robust to alignment and scaling problems and also are of lower dimensions. We also employ sparse modeling technique for Face recognition task using these Covariance descriptor which are dimensionally reduced by transforming them on to a tangent space, which we call PGA feature. Further, we improve upon the recognition results of linear sparse modeling, by non-linear mapping of the PGA features by employing “Kernel Trick” for these sparse models. We show that the Kernelized sparse models using the PGA features are indeed very efficient for free form face recognition by testing on two standard databases namely AR and YaleB database.

Eyewitness recognition is acknowledged to be prone to error but there is less understanding of difficulty in discriminating unfamiliar faces. This thesis examined the effects of face perception on identification of facial composites, and on unfamiliar face image comparison. Facial composites depict face memories by reconstructing features and configurations to form a likeness. They are generally reconstructed from an unfamiliar face memory, and will be unavoidably flawed. Identification will require perception of any accurate features, by someone who is familiar with the suspect and performance is typically poor. In typical face perception, face images are processed efficiently as complete units of information. Chapter 2 explored the possibility that holistic processing of inaccurate composite configurations will impair identification of individual features. Composites were split below the eyes and misaligned to impair holistic analysis (cf. Young, Hellawell, & Jay, 1987); identification was significantly enhanced, indicating that perceptual expertise with inaccurate configurations exerts powerful effects that can be reduced by enabling featural analysis. Facial composite recognition is difficult, which means that perception and judgement will be influence by an affective recognition bias: smiles enhance perceived familiarity, while negative expressions produce the opposite effect. In applied use, facial composites are generally produced from unpleasant memories and will convey negative expression; affective bias will, therefore, be important for facial composite recognition. Chapter 3 explored the effect of positive expression on composite identification: composite expressions were enhanced, and positive affect significantly increased identification. Affective quality rather than expression strength mediated the effect, with subtle manipulations being very effective. Facial image comparison (FIC) involves discrimination of two or more face images. Accuracy in unfamiliar face matching is typically in the region of 70%, and as discrimination is difficult, may be influenced by affective bias. Chapter 4 explored the smiling face effect in unfamiliar face matching. When multiple items were compared, positive affect did not enhance performance and false positive identification increased. With a delayed matching procedure, identification was not enhanced but in contrast to face recognition and simultaneous matching, positive affect improved rejection of foil images. Distinctive faces are easier to discriminate. Chapter 5 evaluated a systematic caricature transformation as a means to increase distinctiveness and enhance discrimination of unfamiliar faces. Identification of matching face images did not improve, but successful rejection of non-matching items was significantly enhanced. Chapter 6 used face matching to explore the basis of own race bias in face perception. Other race faces were manipulated to show own race facial variation, and own race faces to show African American facial variation. When multiple face images were matched simultaneously, the transformation impaired performance for all of the images; but when images were individually matched, the transformation improved perception of other race faces and discrimination of own race faces declined. Transformation of Japanese faces to show own race dimensions produced the same pattern of effects but failed to reach significance. The results provide support for both perceptual expertise and featural processing theories of own race bias. Results are interpreted with reference to face perception theories; implications for application and future study are discussed.

A idade gestacional é uma medida importante, pois quando o bebê nasce antes da 37ª semana há riscos para alterações do desenvolvimento. A relação dos bebês com pais fornece base para o desenvolvimento dos padrões de autorregulação, para o aumento da sensibilidade materna, e para o desenvolvimento do apego. Permeando a hipótese de que, a idade gestacional pode influenciar no desenvolvimento infantil, o objetivo do estudo foi verificar a influência da idade gestacional nas habilidades do desenvolvimento infantil (motora grossa, motora fina-adaptativa, pessoal-social e de linguagem) e a qualidade da interação na díade mãe-bebê, ao longo do primeiro ano de vida (três, nove e 12 meses). Cumpriram-se os princípios éticos. Participaram do estudo 28 díades mãe-bebê, com crianças nascidas entre a 32ª a 40ª semana de gestação, recrutadas ao nascimento. Aos três meses os familiares foram contatados para a primeira avaliação, que constou da aplicação do protocolo de anamnese, aplicação do procedimento Face to Face Still-Face (FFSF) e do Teste de Screnning de Desenvolvimento Denver II (TSDD-II). Aos nove meses repetiu-se a aplicação do FFSF, TSDD-II e foi verificada a qualidade da interação por meio do Child-Adult Relationship Experimental Index (CARE-Index). Aos 12 meses repetiu-se a medida do desenvolvimento TSDD-II e foi aplicada o paradigma laboratorial da Situação Estranha (SE). O tratamento estatístico constou de análise descritiva e aplicação do Teste de Correlação de Spearman, Teste exato de Fischer, Teste de Mann-Whitney e Teste Anova de Medições Repetidas. Os resultados indicaram influência da idade gestacional nas habilidades do desenvolvimento infantil (motora grossa, motora finaadaptativa, pessoal-social e de linguagem), aos três, nove e doze meses, com valor maior nível de significância aos três meses. A qualidade da interação avaliada por meio do CARE-index, indicou predomínio de mães com alto nível de sensibilidade (81,82%). Os padrões de autorregulação avaliados por meio do procedimento FFSF indicaram que 57,14% da casuística apresentaram orientação social não positiva e 42,86% orientação social positiva aos três e aos nove meses 78,57% orientação social não positiva e 21,43% orientação social positiva. O padrão de Apego, avaliado pela SE, verificou apego inseguro para 60,71% e apego seguro em 39,29% da casuística. / Gestational age is an important baseline because when the infant is born before the 37th week there are risks for developmental changes. The relationship between infants and parents provides a basis for the development of self-regulation standards, for the increase of maternal sensitivity, and for the development of attachment. Permeating the hypothesis that gestational age may influence infant development, this study aimed to verify the influence of gestational age on infants developmental skills (gross motor, fine-adaptive motor, personal-social and language), and the quality of gestational age of the mother-infant dyad interaction during the first year of life (three, nine and 12 months). Ethical principles were fulfilled. The study included 28 mother-infant dyads, with children born between the 32nd and 40th weeks of gestation, recruited at birth. At three months old the family members were contacted for the first evaluation, which included the application of the protocol of anamnesis, application of the Face to Face Still-Face (FFSF) procedure and the Denver Development Screening Test II (DDST-II). At nine months the FFSF, DDST-II was repeated and the quality of the interaction was verified through the Child-Adult Relationship Experimental Index (CARE-Index). At 12 months the DDST-II development measurement was repeated and the laboratory paradigm of the Strange Situation (SE) was applied. The statistical treatment consisted of descriptive analysis and application of Spearman\'s Correlation Test, Fischer\'s Exact Test, Mann-Whitney Test and Repeated Measures Anova Tests. The results indicated the influence of gestational age on infant\'s developmental abilities (gross motor, fine-adaptive motor, personal-social and language) at three, nine and twelve months, with a higher level of significance at three months old. The quality of the interaction evaluated through CARE-index, indicated predominance of mothers with a high level of sensitivity (81.82%). Self-regulation standards assessed through the FFSF procedure indicated that 57.14% of the case analysis had non-positive social guidance and 42.86% had positive social guidance at three, and at nine months 78.57% non-positive social guidance and 21.43% positive social orientation. The Attachment pattern, evaluated by the SE, found unsafe attachment to 60.71% and Secure attachment in 39,29% of the cases analysis.

While the area of face recognition has been extensively studied in recent years, it remains a largely open problem, despite what movie and television studios would leave you to believe. Frontal, still face recognition research has seen a lot of success in recent years from any different researchers. However,the accuracy of such systems can be greatly diminished in cases such as increasing the variability of the database,occluding the face, and varying the illumination of the face. Further varying the pose of the face (yaw, pitch, and roll) and the face expression (smile, frown, etc.) adds even more complexity to the face recognition task, such as in the case of face recognition from video. In a more realistic video surveillance setting, a face recognition system should be robust to scale, pose, resolution, and occlusion as well as successfully track the face between frames. Also, a more advanced face recognition system should be able to improve the face recognition result by utilizing the information present in multiple video cameras. We approach the problem of face recognition from video in the following manner. We assume that the training data for the system consists of only still image data, such as passport photos or mugshots in a real-world system. We then transform the problem of face recognition from video to a still face recognition problem. Our research focuses on solutions to detecting, tracking and extracting face information from video frames so that they may be utilized effectively in a still face recognition system. We have developed four novel methods that assist in face recognition from video and multiple cameras. The first uses a patch-based method to handle the face recognition task when only patches, or parts, of the face are seen in a video, such as when occlusion of the face happens often. The second uses multiple cameras to fuse the recognition results of multiple cameras to improve the recognition accuracy. In the third solution, we utilize multiple overlapping video cameras to improve the face tracking result which thus improves the face recognition accuracy of the system. We additionally implement a methodology to detect and handle occlusion so that unwanted information is not used in the tracking algorithm. Finally, we introduce the average-half-face, which is shown to improve the results of still face recognition by utilizing the symmetry of the face. In one attempt to understand the use of the average-half-face in face recognition, an analysis of the effect of face symmetry on face recognition results is shown. / text

Submitted by Maike Costa (maiksebas@gmail.com) on 2017-03-24T13:02:51Z No. of bitstreams: 1 arquivototal.pdf: 3351670 bytes, checksum: d7ffdd58b6eb19c7d97b4c7a15558b59 (MD5) / Made available in DSpace on 2017-03-24T13:02:51Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 3351670 bytes, checksum: d7ffdd58b6eb19c7d97b4c7a15558b59 (MD5) Previous issue date: 2016-08-08 / Cette thèse a pour but analyser les situations sociales produites dans l'enseignement de la Langue Maternelle comme un contexte pour la formation citoyenne des apprentis. Ainsi, cette recherche vise à comprendre comment les interactions entre professeur et étudiants contribuent à la capacité d'adapter les discours de ces élèves citoyens aux conditions de production et réception de différents évènements communicatifs. Cette recherche a comme base les axes théoriques de la Sociolinguistique Interactionnelle (GOFFMAN 2011, 2012, 2013 a, b c; GUMPERZ 1982, 2013) dirigée à l'Analyse de la Conversation (KERBRAT-ORECCHIONI 2010, MARCUSCHI 2004, 2005, 2008 a, b), en particulier, l'interaction face à face dans le processus d'enseignement-apprentissage. Ces approches considèrent le langage un phénomène social, en autre, celui du langage humain qui correspond à l'utilisation langagère diverse, selon les situations sociales où elles s'insèrent (BAKHTIN, 2006, e 2010; LABOV, 2011). Ainsi, l'analyse des cours de Langue Maternelle est une ocasion d'étudier la pratique pédagogique, car il est entendu qu'elle doit favoriser l'analyse critique des réalités et des contextes qui sont historiquement et socialement construits. Il est nécessaire encore, produire des discours sensibles au pouvoir et que leur permette d'interagir avec les autres discours et formes d'interpréter et de s'assurer dans le monde, de manière à vivre des expériences multiples et participer avec des différentes positions d'interaction, favorisant donc l'expression de voix plusieurs, complexes et différentes. Il est clair que le cours est une ambiance communicative dont l'interaction face à face est faite par l'interaction verbale et aussi par les signes non-verbaux, à travers les indices de contextualisation et d'autres ressources. Dans ce contexte, quand les intentions du parlant sont reconnues par les interlocuteurs et vice versa, le succès du procès communicatif et de l'enseignement-apprentissage est assuré. Cette recherche aura une approche ethnographique, de manière prédominante, qualitative et dont l'origine est situé dans les études d'Anthropologie Culturelle et correspond à une analyse descriptive des cours dans une Escola de Referência (Grande École) situé à la ville de Recife – PE. La méthode interprétative a été utilisée, fondé en concepts de la Sociolinguistique Interactionnelle et de l'Analyse de la Conversation et à partir la collecte de données originaires d'observations, entretiens, conversations informelles, journal de terrain et analyse des documents. Par rapport aux résultats obtenus, il est considéré que la relation enseignement-apprentissage en cours n'est pas toujours favorable pour l'autonomie des étudiants, car le ce rôle social établit une relation trop spécifique avec le savoir. Cela se passe car les cours n'ont pas toujours représenté un lieu où les interactions sociales et échanges conversationnelles étaient ouvertes, ce qui donnerait force aux relations des étudiants à travers la confrontation de l'autre et en conséquent, il n'y a pas toujours de conditions de former une perception de soi-même et de sa citoyenneté. / The aim of this thesis is to analyze social situations produced in a context of mother tongue teaching as opportunities of citizenship education. The purpose of this study was to understand how does the interaction between teachers and learners help pupils to become citizens capable to adapt their discourse to different communicative events, both as a producer and receptor. This research is based on the theory of Interactional Sociolinguistics (GOFFMAN 2011, 2012, 2013 a, b c; GUMPERZ 1982, 2013), with the contribution of Conversational Analysis (KERBRAT-ORECCHIONI 2010, MARCUSCHI 2004, 2005, 2008 a, b), particularly face-to-face interaction in teaching-learning process. These views rest on the assumption that the language is a social phenomenon, i.e. a human language phenomenon related to diverse discursive practices, according to social situations (BAKHTIN, 2006 and 2010; LABOV, 2011). From this perspective, analyzing lessons is an opportunity of deliberating on teaching, assuming that the educational practices need to facilitate the critical thinking of reality and historical context socially and historically built. Furthermore, it is necessary to create sensible discourses enabled to interact with other discourses and ways of seeing and being in the world. Consequently, it will be possible to live multiple experiences and interact with people from different hierarchical positions, supporting many complex and diverse voices. For one, the classroom is a surrounding communicative place where face-to-face interaction occurs verbally and not verbally as well, through contextualization cues and other means. In this atmosphere, when the speaker‘s intentions are recognized by the listener, and vice versa, communication process and teaching-learning process are successful. This work has, mostly, an ethnographic and qualitative approach, originally from Cultural Anthropology, related to a descriptive analysis of classrooms in a Reference School located in Recife-PE-Brazil. It was used an interpretive method based on concepts in Interactional Sociolinguistics concept and Conversational Analysis, using data collected during lesson observations, interviews, informal conversation, research journal and document analysis. The results showed that teaching-learning process in the classroom not always contribute to emancipate the learners, because pupil‘s role established a very specific relation with the knowledge. Moreover, the classroom was not always a place where occurred social interactions and conversation exchanges able to consolidate learner‘s relations in a viewpoint of encountering with the other. As a result, the students are not able to foster a sense of self and their citizenship. / Esta tese tem por objetivo analisar as situações sociais produzidas no ensino de Língua Materna como espaços para a formação da cidadania dos aprendizes. Buscou-se entender como as interações entre professor e estudantes contribuem para tornar os estudantes cidadãos capazes de adequar seu discurso às condições de produção e recepção dos diferentes eventos comunicativos. Esta investigação insere-se nas bases teóricas da Sociolinguística Interacional (GOFFMAN 2011, 2012, 2013 a, b c; GUMPERZ 1982, 2013) direcionada à Análise da Conversação (KERBRAT-ORECCHIONI 2010, MARCUSCHI 2004, 2005, 2008 a, b), particularmente, a interação face a face em processo de ensino-aprendizagem. Essas linhas trabalham a linguagem enquanto um fenômeno social, ou seja, o fenômeno da linguagem humana corresponde ao exercício de práticas discursivas diversas, conforme as situações sociais em que essas práticas se inserem (BAKHTIN, 2003 e 2006; LABOV, 2008 e 2009). Nessa perspectiva, a análise de aulas é uma oportunidade para reflexão sobre o fazer pedagógico, pois se pressupõe que a prática pedagógica precisa favorecer o exame crítico das realidades e dos contextos históricos e socialmente construídos. Necessita, ainda, produzir discursos sensíveis ao poder que lhes permita interagir com outros discursos e formas de ver e estar no mundo, de modo a vivenciar múltiplas experiências e interagir com posições diferentes, favorecendo, dessa forma, a expressão de muitas, complexas e diferentes vozes. A justificativa pela temática e pelo desenvolvimento desta pesquisa parte da ideia de que as aulas em língua materna devem favorecer uma tomada de consciência da cidadania, isto é, auxiliar o estudante a saber praticá-la e compreendê-la. O domínio do uso da língua materna possibilita ao estudante uma segurança para expressar suas ideias e se posicionar quando inserido em um grupo. Nessa troca ele amplia não só o conhecimento sobre si mesmo e o outro, mas também avança em sua competência comunicativa, que é essencial para sua inserção social. Além disso, a compreensão da rotina interacional estabelecida em sala de aula viabiliza o entendimento das razões pelas quais as aulas de língua materna parecem não potencializar a apreensão de conhecimentos práticos e úteis não só à vida acadêmica dos estudantes de ensino médio, mas também às exigências de sua cultura. Nessa perspectiva, investigar as interações no processo de ensino-aprendizagem em uma sala de aula é relevante, porque a sala de aula é um espaço onde ocorrem as interações sociais e trocas conversacionais que fortalecem as relações do estudante por um viés de confrontação com o outro, construindo, assim, uma percepção de si mesmo e de sua cidadania. O presente trabalho terá uma abordagem etnográfica, predominantemente, qualitativa e corresponde a uma análise descritiva de sala de aula de uma Escola de Referência localizada na cidade de Recife – PE. Utilizou-se o método interpretativo baseado em conceitos da Sociolinguística Interacional e da Análise da Conversação, a partir da coleta de dados oriundos de observações, entrevistas, conversas informais, diário de campo e análise documental. Quanto aos resultados obtidos, considera-se que a relação ensino-aprendizagem em sala de aula nem sempre contribui para a emancipação dos estudantes, pois a responsabilidade de estudante estabelece uma relação muito específica com o saber e nem sempre a sala de aula representa um espaço onde ocorrem interações sociais e trocas conversacionais que fortalecem as relações do estudante por um viés de confrontação com o outro, não havendo, consequentemente, para ele condições de fomentar uma percepção de si mesmo e de sua cidadania.

A idade gestacional é uma medida importante, pois quando o bebê nasce antes da 37ª semana há riscos para alterações do desenvolvimento. A relação dos bebês com pais fornece base para o desenvolvimento dos padrões de autorregulação, para o aumento da sensibilidade materna, e para o desenvolvimento do apego. Permeando a hipótese de que, a idade gestacional pode influenciar no desenvolvimento infantil, o objetivo do estudo foi verificar a influência da idade gestacional nas habilidades do desenvolvimento infantil (motora grossa, motora fina-adaptativa, pessoal-social e de linguagem) e a qualidade da interação na díade mãe-bebê, ao longo do primeiro ano de vida (três, nove e 12 meses). Cumpriram-se os princípios éticos. Participaram do estudo 28 díades mãe-bebê, com crianças nascidas entre a 32ª a 40ª semana de gestação, recrutadas ao nascimento. Aos três meses os familiares foram contatados para a primeira avaliação, que constou da aplicação do protocolo de anamnese, aplicação do procedimento Face to Face Still-Face (FFSF) e do Teste de Screnning de Desenvolvimento Denver II (TSDD-II). Aos nove meses repetiu-se a aplicação do FFSF, TSDD-II e foi verificada a qualidade da interação por meio do Child-Adult Relationship Experimental Index (CARE-Index). Aos 12 meses repetiu-se a medida do desenvolvimento TSDD-II e foi aplicada o paradigma laboratorial da Situação Estranha (SE). O tratamento estatístico constou de análise descritiva e aplicação do Teste de Correlação de Spearman, Teste exato de Fischer, Teste de Mann-Whitney e Teste Anova de Medições Repetidas. Os resultados indicaram influência da idade gestacional nas habilidades do desenvolvimento infantil (motora grossa, motora finaadaptativa, pessoal-social e de linguagem), aos três, nove e doze meses, com valor maior nível de significância aos três meses. A qualidade da interação avaliada por meio do CARE-index, indicou predomínio de mães com alto nível de sensibilidade (81,82%). Os padrões de autorregulação avaliados por meio do procedimento FFSF indicaram que 57,14% da casuística apresentaram orientação social não positiva e 42,86% orientação social positiva aos três e aos nove meses 78,57% orientação social não positiva e 21,43% orientação social positiva. O padrão de Apego, avaliado pela SE, verificou apego inseguro para 60,71% e apego seguro em 39,29% da casuística. / Gestational age is an important baseline because when the infant is born before the 37th week there are risks for developmental changes. The relationship between infants and parents provides a basis for the development of self-regulation standards, for the increase of maternal sensitivity, and for the development of attachment. Permeating the hypothesis that gestational age may influence infant development, this study aimed to verify the influence of gestational age on infants developmental skills (gross motor, fine-adaptive motor, personal-social and language), and the quality of gestational age of the mother-infant dyad interaction during the first year of life (three, nine and 12 months). Ethical principles were fulfilled. The study included 28 mother-infant dyads, with children born between the 32nd and 40th weeks of gestation, recruited at birth. At three months old the family members were contacted for the first evaluation, which included the application of the protocol of anamnesis, application of the Face to Face Still-Face (FFSF) procedure and the Denver Development Screening Test II (DDST-II). At nine months the FFSF, DDST-II was repeated and the quality of the interaction was verified through the Child-Adult Relationship Experimental Index (CARE-Index). At 12 months the DDST-II development measurement was repeated and the laboratory paradigm of the Strange Situation (SE) was applied. The statistical treatment consisted of descriptive analysis and application of Spearman\'s Correlation Test, Fischer\'s Exact Test, Mann-Whitney Test and Repeated Measures Anova Tests. The results indicated the influence of gestational age on infant\'s developmental abilities (gross motor, fine-adaptive motor, personal-social and language) at three, nine and twelve months, with a higher level of significance at three months old. The quality of the interaction evaluated through CARE-index, indicated predominance of mothers with a high level of sensitivity (81.82%). Self-regulation standards assessed through the FFSF procedure indicated that 57.14% of the case analysis had non-positive social guidance and 42.86% had positive social guidance at three, and at nine months 78.57% non-positive social guidance and 21.43% positive social orientation. The Attachment pattern, evaluated by the SE, found unsafe attachment to 60.71% and Secure attachment in 39,29% of the cases analysis.

Human face detection and recognition techniques play an important role in applica- tions like face recognition, video surveillance, human computer interface and face image databases. Using color information in images is one of the various possible techniques used for face detection. The novel technique used in this project was the combination of various techniques such as skin color detection, template matching, gradient face de- tection to achieve high accuracy of face detection in frontal faces. The objective in this work was to determine the best rotation angle to achieve optimal detection. Also eye and mouse template matching have been put to test for feature detection.

In the last twenty years, important advances have been made in the field of automatic face processing, given the importance of human faces for personal identification, emotional expression and verbal and non verbal communication. The very first step in a face processing algorithm is the detection of faces; while this is a trivial problem in controlled environments, the detection of faces in real environments is still a challenging task. Until now, the most successful approaches for face detection represent the face as a grey-level pattern, and the problem itself is considered as the classification between "face" and "non-face" patterns. Satisfactory results have been achieved in this area. The main disadvantage is that an exhaustive search has to be done on each image in order to locate the faces. This search normally involves testing every single position on the image at different scales, and although this does not represent an important drawback in off-line face processing systems, in those cases where a real-time response is needed it is still a problem. In the different proposed methods for face detection, the "observer" is a disembodied entity, which holds no relationship with the observed scene. This thesis presents a framework for an efficient location of faces in real scenes, in which, by considering both the observer to be situated in the world, and the relationships that hold between the two, a set of constraints in the search space can be defined. The constraints rely on two main assumptions; first, the observer can purposively interact with the world (i.e. change its position relative to the observed scene) and second, the camera is fully calibrated. The first source constraint is the structural information about the observer environment, represented as a depth map of the scene in front of the camera. From this representation the search space can be constrained in terms of the range of scales where a face might be found as different positions in the image. The second source of constraint is the geometrical relationship between the camera and the scene, which allows us to project a model of the subject into the scene in order to eliminate those areas where faces are unlikely to be found. In order to test the proposed framework, a system based on the premises stated above was constructed. It is based on three different modules: a face/non-face classifier, a depth estimation module and a search module. The classifier is composed of a set of convolutional neural networks (CNN) that were trained to differentiate between face and non-face patterns, the depth estimation modules uses a multilevel algorithm to compute the scene depth map from a sequence of images captured the depth information and the subject model into the image where the search will be performed in order to constrain the search space. Finally, the proposed system was validated by running a set of experiments on the individual modules and then on the whole system.

MA, Faculty of Humanities, University of the Witwatersrand, 2009 / Even though investigations of knowledge construction within CMC have been conducted (e.g. Gunawardena, Lowe and Anderson, 1997; Schellens & Valcke, 2004), no research has compared F2F communication and CMC in terms of the ability to solve complex tasks and to develop group cohesion. Group cohesion has been found to be vital for group cooperation and performance. Eight self-formed groups of 5 student participants each volunteered to participate in this study. Each group was required to solve two standardised, complex tasks in the same order. Student groups were randomly assigned to one of four medium combinations with two groups per combination. The combinations were: F2F communication for both tasks, CMC for both tasks, F2F communication for the first task and CMC for the second task, and CMC for the first task and F2F communication for the second task. Measures of knowledge construction were taken using the IAM (Gunawardena et al., 1997), group cohesion (assessed before and after the tasks) using the GAS (Evans & Jarvis, 1986), and a self-developed scale to assess satisfaction with the process and the outcome. The results showed that CMC groups produced significantly fewer contributions, and took a longer time to complete tasks, but there was no significant difference between the two mediums in terms of knowledge construction. The medium combination of F2F communication followed by CMC, achieved the least time to completion; the second most effective medium for knowledge construction, the greatest satisfaction with respect to group processes and the decision in the first task, and achieved a significantly higher level of post-manipulation group cohesion.

O objetivo do presente estudo foi avaliar, em humanos, a associação entre polimorfismos genéticos no sistema RANK/RANKL/OPG com as dimensões craniofaciais. Foram incluídos neste estudo um total de 100 indivíduos caucasianos brasileiros não relacionados. O DNA foi extraído da saliva de cada um dos participantes e os polimorfismos rs3826620, rs9594738 e rs2073618 em RANK, RANKL e OPG, respectivamente, foram analisados por PCR em tempo real. Para avaliação das dimensões craniofaciais foram avaliadas três medidas angulares (SNA, SNB e ANB) e quatro medidas lineares (Co-Gn, Go-Pg, Co-Go e PTM-A), obtidas de traçados cefalométricos. Para avaliar a distribuição dos genótipos de acordo com os padrões esqueléticos faciais (Classe I, Classe II e Classe III) foi utilizado o teste do qui-quadrado. Para comparar as médias das dimensões maxilares e mandibulares de acordo com os genótipos utilizou-se o teste de Kruskal-Wallis, com o pós-teste de Dunn para comparações múltiplas, ou ANOVA com pós-teste de Tukey. Foi utilizada a análise de regressão linear multivariada para ajustar a possível influência da idade e do gênero em cada medida. O equilíbrio de Hardy-Weinberg foi avaliado utilizando o teste do qui-quadrado para cada polimorfismo. O nível de significância adotado para todas as análises foi 5%. Os resultados obtidos evidenciaram que não houve associação estatisticamente significante entre a distribuição genotípica de RANK, RANKL e OPG com as médias dos ângulos SNA e SNB, nem com a distribuição fenotípica (padrão esquelético Classe I, II ou III) (p>0,05). Observou-se diferença estatisticamente significante entre a distribuição das medidas do comprimento da base mandibular, de acordo com os genótipos de RANK, onde o genótipo GG apresentou maior medida de Go-Pg (p=0,039). Na análise multivariada, observou-se associação significante para os polimorfismos em RANK e medidas mandibulares (Go-Pg e Co-Gn) (p<0,05). A medida da maxila não foi associada a nenhum polimorfismo. Conclui-se que houve associação entre o polimorfismo genético rs3826620 em RANK com maiores dimensões mandibulares, onde o comprimento da mandíbula (Co-Gn) e o comprimento da base da mandíbula (Go-Pg) estavam aumentados. / The objective of the present study was to evaluate, in humans, the association between genetic polymorphisms in the RANK/ RANKL/OPG system with alterations in craniofacial dimensions. A total of 100 unrelated Brazilian Caucasians were included in this study. DNA was extracted from the saliva of each of the participants and the polymorphisms rs3826620, rs9594738 and rs2073618 in RANK, RANKL and OPG, respectively, were analyzed by real-time PCR. To evaluate the craniofacial dimensions, three angular measurements (SNA, SNB and ANB) and four linear measurements (Co-Gn, Go-Pg, Co-Go and PTM-A) were obtained from cephalometric tracings. To compare the difference between the means of the linear and angular measurements according to the genotype, Kruskal-Wallis followed by Dunn post test or ANOVA followed by the Tukey post test was used. Linear regression analysis was also used to adjust the possible influence of age and gender on each linear maxillary and mandibular measure. The Hardy-Weinberg equilibrium was also evaluated using the chi-square test within each polymorphism. The level of significance was 5%. The results demonstrated that there were no statistically significant association between the genotypic distribution of RANK, RANKL, OPG, and the angules SNA, SNB and according to the phenotypic distribution (Class I, Class II or Class III of skeletal pattern) (p> 0.05). A statistically significant difference was observed between the distribution of mandibular base length measurements according to the RANK genotypes, where the GG genotype showed a higher Go-Pg measurement (p=0.039). In the multivariate analysis, a statistically significant association was found for RANK and mandibular (Go-Pg and Co-Gn) polymorphisms (p<0.05). Measurement of the maxilla was not associated with any polymorphism. It was concluded that there was an association between genetic polymorphism rs3826620 in RANK with a greater mandibular dimension, in which the length of the mandible (Co-Gn) and the length of the base of the mandible (Go-Pg) were increased.