Dissertations / Theses: 'Photo face' – Grafiati (2024)

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[Non communiqué]
In the past decade, 3D statistical face model (3D Morphable Model) has received much attention by both the commercial and public sectors. It can be used for face modeling for photo-realistic personalized 3D avatars and for the application 2D face recognition technique in biometrics. This thesis describes how to achieve an automatic 3D face reconstruction system that could be helpful for building photo-realistic personalized 3D avatars and for 2D face recognition with pose variability. The first systems we propose Combined Active Shape Model for 2D frontal facial landmark location and its application in 2D frontal face recognition in degraded condition. The second proposal is 3D Active Shape Model (3D-ASM) algorithm which is presented to automatically locate facial landmarks from different views. The third contribution is to use biometric data (2D images and 3D scan ground truth) for quantitatively evaluating the 3D face reconstruction. Finally, we address the issue of automatic 2D face recognition across pose using 3D Morphable Model

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Faces, along with the personal identities behind them, are effective elements in organizing a collection of consumer photos, as they represent who was involved. However, the accurate discrimination and subsequent recognition of face appearances is still very challenging. This can be attributed to the fact that faces are usually neither perfectly lit nor captured, particularly in the uncontrolled environments of consumer photos. Unlike, for instance, passport photos that only show faces stripped of their surroundings, Consumer Photo Collections contain a vast amount of meaningful context. For example, consecutively shot photos often correlate in time, location or scene. Further information can also be provided by the people appearing in photos, such as their demographics (ages and gender are often easier to surmise than identities), clothing, or the social relationships among co-occurring people. Motivated by this ubiquitous context, we propose and research people recognition approaches that consider contextual information within photos, as well as across entire photo collections. Our aim of leveraging additional contextual information (as opposed to only considering faces) is to improve recognition performance. However, instead of requiring users to explicitly label specific pieces of contextual information, we wish to implicitly learn and draw from the seemingly coherent content that exists inherently across an entire photo collection. Moreover, unlike conventional approaches that usually predict the identity of only one person’s appearance at a time, we lay out a semi-supervised approach to jointly recognize multiple peoples’ appearances across an entire photo collection simultaneously. As such, our aim is to find the overall best recognition solution. To make context-based joint recognition of people feasible, we research a sparse but efficient graph-based approach that builds on Markov Networks and utilizes distance-based face description methods. We show how to exploit the following specific contextual cues: time, social semantics, body appearances (clothing), gender, scene and ambiguous captions. We also show how to leverage crowd-sourced gamified feedback to iteratively improve recognition performance. Experiments on several datasets demonstrate and validate the effectiveness of our semisupervised graph-based recognition approach compared to conventional approaches.

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Wearable photo-cameras offer a hands-free way to record images from the camera- wearer perspective of daily experiences as they are lived, without the necessity to interrupt recording due to the device battery or storage limitations. This stream of images, known as egocentric photo-streams, contains important visual data about the living of the user, where social events among them are of special interest. Social interactions are proven to be a key to longevity and having too few interactions equates the same risk factor as smoking regularly. Considering the importance of the matter, there is no wonder that automatic analysis of social interactions is largely attracting the interest of the scientific community.Analysis of unconstrained photo-streams however, imposes novel challenges to the social signal processing problem with respect to conventional videos. Due to the free motion of the camera and to its low temporal resolution, abrupt changes in the field of view, in illumination condition and in the target location are highly frequent. Also, since images are acquired under real-world conditions, occlusions occur regularly and appearance of the people undergoes intensive variations from one event to another.Given a user wearing a photo-camera during a determined period, this thesis, driven by the social signal processing paradigm presents a framework for comprehensive social pattern characterization of the user. In social signal processing, the second step after recording the scene is to track the appearance of multiple people who are involved in the social events. Hence, our proposal begins by introducing a multi-face tracking which holds certain characteristics to deal with challenges imposed by the egocentric photo-streams. Next step forward in social signal processing, is to extract the so-called social signals from the tracked people. In this step, besides the conventionally studied social signals, clothing as a novel social signal is proposed for further studies within the social signal processing. Finally, the last step is social signal analysis, itself. In this thesis, social signal analysis is essentially defined as reaching an understanding of social patterns of a wearable photo-camera user by reviewing captured photos by the worn camera over a period of time. Our proposal for social signal analysis is comprised of first, to detect social interactions of the user where the impact of several social signals on the task is explored. The detected social events are inspected in the second step for categorization into different social meetings. The last step of the framework is to characterize social patterns of the user. Our goal is to quantify the duration, the diversity and the frequency of the user social relations in various social situations. This goal is achieved by the discovery of recurrences of the same people across the whole set of social events related to the user.Each step of our proposed pipeline is validated over relevant datasets, and the obtained results are reported quantitatively and qualitatively. For each section of the pipeline, a comparison with related state-of-the-art models is provided. A discussion section over the obtained results is also given which is dedicated to highlighting the advantages, shortcomings, and differences of the proposed models, and with regards to the state-of-the-art.
Las cámaras portables ofrecen una forma de capturar imágenes de experiencias diarias vividas por el usuario, desde su propia perspectiva y sin la intervención de éste, sin la necesidad de interrumpir la grabación debido a la batería del dispositivo o las limitaciones de almacenamiento. Este conjunto de imágenes, conocidas como secuencias de fotos egocéntricas, contiene datos visuales importantes sobre la vida del usuario, donde entre ellos los eventos sociales son de especial interés. Las interacciones sociales han demostrado ser clave para la longevidad, el tener pocas interacciones equivale al mismo factor de riesgo que fumar regularmente. Teniendo en cuenta la importancia del asunto, no es de extrañar que el análisis automático de las interacciones sociales atraiga en gran medida el interés de la comunidad científica.Sin embargo, el análisis de secuencias de fotos impone nuevos desafíos al problema del procesamiento de las señales sociales con respecto a los videos convencionales. Debido al movimiento libre de la cámara y a su baja resolución temporal, los cambios abruptos en el campo de visión, en la iluminación y en la ubicación del objeto son frecuentes. Además, dado que las imágenes se adquieren en condiciones reales, las oclusiones ocurren con regularidad y la apariencia de las personas varía de un evento a otro.Dado que un individuo usa una cámara fotográfica durante un período determinado, esta tesis, impulsada por el paradigma del procesamiento de señales sociales, presenta un marco para la caracterización integral del patrón social de dicho individuo. En el procesamiento de señales sociales, el segundo paso después de grabar la escena es rastrear la apariencia de varias personas involucradas en los eventos sociales. Por lo tanto, nuestra propuesta comienza con la introducción de un seguimiento de multiples caras que posee ciertas características para hacer frente a los desafíos impuestos por las secuencias de fotos egocéntricas. El siguiente paso en el procesamiento de señales sociales es extraer las señales sociales de las personas bajo análisis. En este paso, adema´s de las señales sociales estudiadas convencionalmente, en esta tesis se propone la vestimenta como una nueva señal social para estudios posteriores dentro del procesamiento de señales sociales. Finalmente, el último paso es el análisis de señales sociales. En esta tesis, el análisis de señales sociales se define esencialmente como la comprensión de los patrones sociales de un usuario de cámara portable, mediante la revisión de fotos capturadas por la cámara llevada durante un período de tiempo. Nuestra propuesta para el análisis de señales sociales se compone de diferentes pasos. En primer lugar, detectar las interacciones sociales del usuario donde se explora el impacto de varias señales sociales en la tarea. Los eventos sociales detectados se inspeccionan en el segundo paso para la categorización en diferentes reuniones sociales. El último paso de la propuesta es caracterizar los patrones sociales del usuario. Nuestro objetivo es cuantificar la duración, la diversidad y la frecuencia de las relaciones sociales del usuario en diversas situaciones sociales. Este objetivo se logra mediante el descubrimiento de apariciones recurrentes de personas en todo el conjunto de eventos sociales relacionados con el usuario.Cada paso de nuestro método propuesto se valida sobre conjuntos de datos relevantes, y los resultados obtenidos se evalúan cuantitativa y cualitativamente. Cada etapa del modelo se compara con los trabajos relacionados más recientes. También, se presenta una sección de discusión sobre los resultados obtenidos, que se centra en resaltar las ventajas, limitaciones y diferencias de los modelos propuestos, y de estos con respecto al estado del arte.

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As relações entre Trabalho e Saúde neste estudo tiveram por base possíveis agravos originados de exposições prolongadas e repetidas ao sol sem a devida proteção. Objetivou-se analisar as atitudes e práticas face à exposição solar dos carteiros do Município de Juazeiro do Norte-CE, identificando quais os recursos e como são utilizados por eles para se protegerem da ação nociva do sol. Objetivou- se também identificar a existência de iniciativa por parte da Empresa de Correios e Telégrafos no sentido de fornecer aos trabalhadores a adoção de recursos para fotoproteção. Tratou-se de um estudo de corte transversal, com abordagem quantitativa. O estudo foi realizado na Empresa de Correios e Telégrafos da cidade de Juazeiro do Norte- CE, envolvendo 25 carteiros, sendo 23 homens e 2 mulheres, com média de idade 35,84 anos. A coleta dos dados foi realizada por meio de um questionário contemplando variáveis de caracterização do grupo, conhecimento sobre os efeitos nocivos dos RUVs, práticas de exposição solar e medidas preventivas relevantes à fotoexposição. Para análise estatística, foi utilizado o programa Statistical Package for the Social Sciences (SPSS) versão 13.0 e realizou- se uma análise descritiva.Dos carteiros pesquisados a maioria foi do sexo masculino (92%) e a média da idade foi de 35,84 anos e todos tinham um bom nível de escolaridade. Em relação ao tempo de vinculo empregatício, a maioria dos carteiros tem mais de 9 anos de trabalho. Quanto ao horário de trabalho externo, todos os carteiros o realizam a partir das 11h00min e retornam a sede dos correios entre às 16h00min e 18h00min. Em relação ao fototipo cutâneo, 56% dos carteiros enquadram- se no fototipo III e o restante distribui- se entre os II, IV e V.Em relação ao fator de proteção 22 carteiros utilizam o fator 30. Quanto ao fornecimento dos correios do filtro solar, 56% responderam que ocorre semanalmente, independentemente de estar faltando ou não o produto.Pode-se concluir que a maioria dos carteiros utiliza meios para proteção solar, no entanto não realizam esta proteção da forma mais adequada. Quanto aos Correios, identificamos que a instituição contribui parcialmente no sentido de fornecer aos trabalhadores investigados recursos para fotoproteção.
The relations between Work and Health in this study have been based on likely damages from long, repeated exposition to the sun without the necessary protection. It has been aimed to analyze the attitudes and practices to solar exposition of Juazeiro do Norte mailmen, we have identified what resources and how they are used by the mailmen in order to protect them from the sun’s harmful rays. It has also been aimed to identify the existence of initiative from the Brazilian Post Company in Juazeiro do Norte city, there are 25 mailmen involved all in all, they are 23 men and 2 women and their age is 34. 84 at average. The data collect has been made through a questionnaire covering variables of group characterization, knowledge about harmful effects of UVRs practices of solar expositions and preventive steps relevant to photo exposure. For statistics analyses, the Statical Package for the Social Sciences program was used (SSPS) 13.0 version and a descriptive analysis. Among the post officers surveyed, most of them are male (92%) and the age average has been 35.85 years and all had a good education level. When it comes to time of employing link, most of post officers have worked for over nine years. In relation to working time, most post officers work from 11:00 am and they get back to the headquarters at about 4:00 pm to 6:00 pm. In relation to cutaneous photo type, 56% post officers fit in photo type III and the rest in II, IV and V groups. In relation to protection factor, 22 post officers utilize factor 30. In relation to the supply of sun screen, 56% answered that it happens every week, independently to lack or not the product. In conclusion, every post man uses some kind of sun protection, nevertheless, they do not do this protection correctly. In relation to the Post Office, we have observed that the company contributes partly in order to supply its investigated clerks resources to protection.
TEDE

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Trois modèles invasifs à large répartition en Europe, le long d'un gradient latitudinal Norvège-Portugal, ont été choisis : Sargassum muticum, Codium fragile et Gracilaria vermiculophylla. Cette thèse a pour objectif l'étude de la phénologie, de l'écophysiologie et du métabolome de ces macrophytes invasifs face à une variation de facteurs environnementaux 1) à une échelle locale, 2) à l'échelle du gradient latitudinal (en lien avec le changement climatique global) ainsi que l'étude 3) des voies de valorisation possibles des métabolites de stress par bio-inspiration. Le gradient latitudinal, se traduisant par un gradient thermique, permet de mimer le réchauffement climatique car les conséquences de ce changement climatique sur les espèces en milieu naturel ne sont généralement appréciables qu'à l'échelle de dizaines d'années. Les suivis de l'écologie, dumétabolome ainsi que des impacts potentiels de ces espèces à une échelle locale en France, a permis d'étudier le développement et le cycle de vie des espèces. En particulier, G. vermiculophylla se caractérise par une phénologie spécifique (avec la prépondérance de petit* fragments végétatifs, <3cm) en Rade de Brest et par une tolérance accrue à l'envasem*nt jusqu'à 12 cm de profondeur en acclimatant son métabolome tout en maintenant une physiologie dormante. Cette espèce ingénieur impacte en profondeur l'écosystème vaseux de la Rade. Le suivi le long du gradient latitudinal a permis d'illustrer la plasticité phénologique des espèces et notamment un potentiel invasif contrasté de C. fragile entre les différentes latitudes. Lors de marée basse de vives eaux, les espèces présentent une acclimatation de leur photo-physiologie en fonction de la latitude avec la mise en évidence d'une photoinhibition du PSll, lié au stress engendré par les conditions environnementales.Enfin, ce travail a illustré les propriétés multifonctionnelles d'extraits enrichis en composés phénoliques, présentant des activités antioxydantes mais également photoprotectrices ou ostéogéniques, soulignant l'émergence de voies de valorisation originales par bio-inspiration pour divers secteurs tels que la cosmétologie et les biomatériaux en santé humaine
Three model species with a large distribution along European coasts, along a latitudinal gradient from Norway to Portugal was chosen: Sargassum muticum, Codium fragile and Gracilaria vermiculophylla. The aims of this PhD thesis were to study the phenology, ecophysiology and the metabolom of these non-native marine macrophytes and their ability to cope with a variation of environmental factors 1) at a population scale, 2) along the latitudinal gradient (in relation with the global climatic change) and to propose 3) bio-inspired molecules for industrial purposes. The latitudinal gradient corresponding to a thermic gradient, allows to imitate the global warming as climatic change ¡mpacts are most of the time only visible at decennial scale.Monitorings of ecology, metabolome and potential impacts of these macroalgae, at a population scale, allowed to study the development and life cycle of these models. In particular, G. vermiculophylla exhibited a specific phenology (with a majority of small vegetative fragments, <3cm) in the Bay of Brest and a highly tolerance to burial until 12 cm depth in the sediment by acclimatizing its metabolome together with the ability to maintain a dormancy physiology. This engineer species modifies deeply muddy shores of this Bay. Latitunal gradients's monitoring highlighted the phenological plasticity and a contrasted invasive potential of C.fragile between latitudes. During low spring tides, species exhibited an acclimation of their photophysiology between latitudes with photoinhibition process related to induce environmental stress. Furthermore, this work showed the multifunctional properties of polyphenols enriched extracts with antioxidant, photoprotective or osteogenic activities, highlighting the emergence of original bio-inspired pathways for cosmetic or biomaterial applications

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У сучасному інформаційному суспільстві збільшується сегмент систем людино-машинної взаємодії на базі інтелектуальних компонентів. Серед задач, що вирішують ці компоненти, варто виділити персоналізацію та аутентифікацію користувача інформаційних баз чи соціальних сервісів, які перспективно вирішувати на базі вбудованих відеокамер через їх поширеність в складі мобільних пристроїв.

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Ce mémoire décrit mes travaux de thèse menés au sein de l'équipe ComSee (Computers that See) rattachée à l'axe ISPR (Image, Systèmes de Perception et Robotique) de l'Institut Pascal. Celle-ci a été financée par la société Vesalis par le biais d'une convention CIFRE avec l'Institut Pascal, subventionnée par l'ANRT (Association Nationale de la Recherche et de la Technologie). Les travaux de thèse s'inscrivent dans le cadre de l'automatisation de la fouille d'archives vidéo intervenant lors d'enquêtes policières. L'application rattachée à cette thèse concerne la création automatique d'un album photo des individus apparaissant sur une séquence de vidéosurveillance. En s'appuyant sur un détecteur de visages, l'objectif est de regrouper par identité les visages détectés sur l'ensemble d'une séquence vidéo. Comme la reconnaissance faciale en environnement non-contrôlé reste difficilement exploitable, les travaux se sont orientés vers le suivi visuel multi-cibles global basé détections. Ce type de suivi est relativement récent. Il fait intervenir un détecteur d'objets et traite la vidéo dans son ensemble (en opposition au traitement séquentiel couramment utilisé). Cette problématique a été représentée par un modèle probabiliste de type Maximum A Posteriori. La recherche de ce maximum fait intervenir un algorithme de circulation de flot sur un graphe, issu de travaux antérieurs. Ceci permet l'obtention d'une solution optimale au problème (défini par l'a posteriori) du regroupement des détections pour le suivi. L'accent a particulièrement été mis sur la représentation de la similarité entre les détections qui s'intègre dans le terme de vraisemblance du modèle. Plusieurs mesures de similarités s'appuyant sur différents indices (temps, position dans l'image, apparence et mouvement local) ont été testées. Une méthode originale d'estimation de ces similarités entre les visages détectés a été développée pour fusionner les différentes informations et s'adapter à la situation rencontrée. Plusieurs expérimentations ont été menées sur des situations complexes, mais réalistes, de scènes de vidéosurveillance. Même si les qualités des albums construits ne satisfont pas encore à une utilisation pratique, le système de regroupement de détections mis en œuvre au cours de cette thèse donne déjà une première solution. Grâce au point de vue partitionnement de données adopté au cours de cette thèse, le suivi multi-cibles développé permet une extension simple à du suivi autre que celui des visages.

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Виконано огляд існуючих способів реконструкції поверхні, розроблено, програмно реалізовано, тапротестовано інформаційну технологію 3D-реконструкції обличчя людини за 2D-зображенням.Мовою C++ з використанням бібліотек OpenGL та OpenCV розроблено систему збору статистичнихданих, необхідних для розрахунку коваріаційної матриці, що лежить в основі запропонованогопідходу. Підхід разом із системою проведення експериментів розроблено мовою Matlab.

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CNPq
Capes
A popularidade das câmeras digitais tem gerado um novo problema: comoarmazenar e recuperar de forma eficiente um grande número de fotografias digitaiscapturadas e caoticamente armazenadas em múltiplas localizações sem qualquer anotação. Em algumas pesquisas, mostra-se que a anotação de informações relacionadas ao contexto no qual uma determinada fotografia foi capturada auxilia na busca das fotografias, sendo as informações mais relevantes para uma pessoa recordar de uma fotografia: a identificação das pessoas que estão presentes na fotografia (Quem); a localização geográfica (Onde); e informações temporais (Quando). Para anotar essas informações, podem ser utilizados mecanismos manuais, automáticos e semiautomáticos. Os mecanismos manuais não possuem muitos adeptos devido ao processo oneroso e tedioso. Os mecanismos automáticos utilizam os algoritmos de análise de conteúdo, sendo o reconhecimento de faces a principal estratégia, a qual só possui bons resultados com faces frontais e sem oclusões. Já os mecanismos de anotação semiautomática, utilizam algoritmos de recomendação de anotações para auxiliar o usuário. Nesta pesquisa, propõem-se algoritmos para a anotação automática e semiautomática de pessoas e eventos em fotografias. Para a anotação de pessoas, utiliza-se o reconhecimento de faces para a anotação automática e informações de contexto mais conteúdo para a geração de listas de sugestões de pessoas para a anotação semiautomática. Para a anotação de eventos, propõe-se um método para a detecção de eventos em coleções pessoais de fotografias e um método para detecção de eventos compartilhados, nos quais as fotografias são capturadas por usuários distintos em um mesmo evento. A partir do método de detecção de eventos compartilhados proposto, pretende-se melhorar a busca de fotografias de um evento em uma rede social, a realização de anotação cruzada e a detecção de inconsistências nas anotações de fotografias. Nos resultados, comprova-se que a ponderação e a filtragem deestimadores para os algoritmos de anotação semiautomática de pessoas presentes nasfotografias baseados em estimadores melhoram os resultados desses algoritmos. Alémdisso, é possível fazer a detecção de eventos compartilhados em uma rede social utilizando informações de quem, onde e quando das fotografias.
The popularity of digital cameras has created a new problem: how to store andretrieve efficiently a large number of captured and chaotically stored digital photos inmultiple locations without annotation. The photo context assists in search of photographs.The most relevant information for a person remember a photograph are: who are present,where and when was captured. To annotate this information, manual, automatic and semiautomatic mechanisms can be used. The manuals mechanisms did not have many fans due to the costly and tedious process. Content analysis and face recognition are the main strategy to automatic mechanisms, which has only front faces with good results andwithout occlusions. In the semiautomatic annotation, recommendation of annotations areused to assist the user. In this research, we propose algorithms for the automatic and semiautomatic annotation of people and events in photos. For the annotation of people, we use face recognition for automatic annotation and content and context information forgenerate suggestions from people for semi-automatic annotation. For the annotation ofevents, we propose a method for detecting events in personal photo collections and amethod for detection of shared events, in which the photographs are captured by differentusers in the same event. The method to detect shared events aims to improve the search of photographs of an event in a social network, conducting cross-annotation and detection of inconsistencies in the annotations of photographs. The results prove that the weighting and filtering algorithms estimators for semi-automatic annotation of persons in photographs based estimators improve the results of these algorithms. Furthermore, it is possible to detect shared events in a social network using information of who, where and when of thephotos.

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Cette thèse présente quelques avancées sur la représentation efficace de l'apparence matérielle dans une simulation de l'éclairage. Nous présentons deux contributions : un algorithme pratique de simulation interactive pour rendre la réflectance mesurée avec une géométrie dynamique en utilisant une analyse fréquentielle du transport de l'énergie lumineuse et le shading hiérarchique et sur-échantillonnage dans un contexte deferred shading, et une nouvelle fonction de distribution pour le modèle de BRDF de Cook-Torrance. Dans la première partie, nous présentons une analyse fréquentielle de transport de l'éclairage en temps réel. La bande passante et la variance sont fonction de l'éclairage incident, de la distance parcourue par la lumière, de la BRDF et de la texture, et de la configuration de la géométrie (la courbure). Nous utilisons ces informations pour sous-échantillonner l'image en utilisant un nombre adaptatif d'échantillons. Nous calculons l'éclairage de façon hiérarchique, en un seul passage. Notre algorithme est implémenté dans un cadre de deferred shading, et fonctionne avec des fonctions de réflectance quelconques, y compris mesurées. Nous proposons deux extensions : pré-convolution de l'éclairage incident pour plus d'efficacité, et anti-aliasing utilisant l'information de fréquence. Dans la deuxième partie, nous nous intéressons aux fonction de réflectance a base de micro-facette, comme le modèle de Cook-Torrance. En nous basant sur les réflectances mesurées, nous proposons une nouvelle distribution des micro-facettes. Cette distribution, Shifted Gamma Distribution, s'adapte aux donnée avec plus de précision. Nous montrons également comment calculer la fonction d'ombrage et de masquage pour cette distribution. Dans un deuxième temps, nous observons que pour certains matériaux, le coefficient de Fresnel ne suit pas l'approximation de Schlick. Nous proposons une généralisation de cette approximation qui correspond mieux aux données mesurées. Nous proposons par ailleurs une nouvelle technique d'optimisation, canal par canal, en deux étapes. Notre modèle est plus précis que les modèles existants, du diffus au spéculaire.

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The type of media shared through social media channels has shifted from text content to include an increasingly large number of images.Visual traces resulting from people's online social behavior have the potential to reveal insights about our habits, activities and preferences. The role of social network-related factors have been well studied in previous research.Yet, few studies have sought to understand how user behavior in social networks is dependent on the image itself. The goal of my dissertation is to understand how people engage with image content, and I seek to uncover the role of presentation and image content on people's preferences. To achieve this goal, I study the image sharing communities, Flickr, Instagram and Pinterest, using quantitative and qualitative methods. First, I show how colors -- a fundamental property of an image -- could impact the virality of an image on Pinterest. I consider three dimensions of color: hue, saturation and brightness and evaluate their role in the diffusion of the image on Pinterest, while controlling for social network reach and activity. Next, I shift the focus from abstract colors to a higher-level presentation of images. I study the role of filters on the Flickr mobile application as proxies to visual computation. To understand how people use filters, I conduct an interview study with 15 Flickr mobile users about their filter use. I analyze Flickr mobile images to discover the role of filters in engaging users.Presentation is not the only factor that makes an image interesting. To gain deeper insights in what makes an image more engaging in social image sharing sites, I study the images of people on the Instagram network. I compare images of people with those that do not have faces and find that images with human faces are more engaging. I also look at the role of age and gender of people in the image in engaging users.Finally, I examine different content categories, with and without filters, and study the impact of content category on engagement. I use large-scale data from Flickr and interviews with Flickr mobile users to draw insights into filter use and content engagement.This dissertation takes a first step toward understanding content and presentation of images and how they impact one aspect of user behavior online. It provides several theoretical and design implications for effective design, creation and imposition of rules on image sharing communities.This dissertation opens up a new direction for future research in multimedia-mediated communication.

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Contaminants of emerging concern (CECs) are continuously being released into the environment mainly because of their incomplete removal in the sewage treatment plants (STPs). The CECs selected for the study include antibiotics (macrolides, sulfonamides and ciprofloxacin), sucralose (an artificial sweetener) and dioctyl sulfosuccinate (DOSS, chemical dispersant used in the Deepwater Horizon oil spill). After being discharged into waterways from STPs, photo degradation is a key factor in dictating the environmental fate of antibiotics and sucralose. Photodegradation efficiency depends on many factors such as pH of the matrix, matrix composition, light source and structure of the molecule. These factors exert either synergistic or antagonistic effects in the environment and thus experiments with isolated factors may not yield the same results as the natural environmental processes. Hence in the current study photodegradation of 13 CECs (antibiotics, sucralose and dicotyl sulfosuccinate) were evaluated using natural water matrices with varying composition (deionized water, fresh water and salt water) as well as radiation of different wavelengths (254 nm, 350 nm and simulated solar radiation) in order to mimic natural processes. As expected the contribution of each factor on the overall rate of photodegradation is contaminant specific, for example under similar conditions, the rate in natural waters compared to pure water was enhanced for antibiotics (2-11 fold), significantly reduced for sucralose (no degradation seen in natural waters) and similar in both media for DOSS. In general, it was observed that the studied compounds degraded faster at 254 nm, while when using a simulated sunlight radiation the rate of photolysis of DOSS increased and the rates for antibiotics decreased in comparison to the 350 nm radiation. The photo stability of the studied CECs followed the order sucralose > DOSS > macrolides > sulfonamides > ciprofloxacin and a positive relationship was observed between photo stability and their ubiquitous presence in natural aquatic matrices. An online LC-MS/MS method was developed and validated for sucralose and further applied to reclaimed waters (n =56) and drinking waters (n = 43) from South Florida. Sucralose was detected in reclaimed waters with concentrations reaching up to 18 µg/L. High frequency of detection (> 80%) in drinking waters indicate contamination of ground waters in South Florida by anthropogenic activity.

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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
A pesquisa ora em curso tem como objetivo compor a partir de fatos, documentos e fotos, a biografia do Professor Francisco Josà de Abreu Matos, apresentando sua vida escolar, sua trajetÃria de professor da Faculdade de FarmÃcia e Odontologia do CearÃ, posteriormente, como professor da Universidade do CearÃ, como tambÃm, as suas pesquisas cientÃficas e os seus projetos de extensÃo no perÃodo de 1924-2008. Proveniente de uma famÃlia que a geraÃÃes forma farmacÃuticos, seria o maior pesquisador cearense em relaÃÃo a Plantas Medicinais e AromÃticas do Nordeste, projeto vinculado ao LaboratÃrio de Produtos Naturais da Universidade Federal do Cearà â UFC. Foi descobridor de centenas de espÃcies da flora nordestina e brasileira e lhe empresta o seu nome para a nomenclatura dessas plantas. Foi o criador do Projeto FarmÃcia Viva da UFC que se espalhou pelo paÃs. Seu percurso pela docÃncia, pesquisa e extensÃo sempre foi pautado pelo trabalho social, que ele via como uma questÃo de hÃbito, no sentido de democratizar o acesso da populaÃÃo mais carente a medicamentos fitoterÃpicos.
This research aims to understand from facts, documents and photos, as unfolded the life and work of Professor Francisco Josà de Abreu Matos, presenting his school life, his teaching career at the Faculty of Pharmacy and Dentistry of Cearà later as professor at the University of CearÃ, but also their scientific research and its extension projects in the 1924-2008 period. Coming from a family that pharmaceutical form generations, would be the greatest researcher cearense regarding Medicinal and Aromatic Plants of the Northeast, project linked to the Natural Products Laboratory of the Federal University of Cearà - UFC. It was discoverer of hundreds of species of flora and northeastern and lends his name to the nomenclature of these plants. He was the creator of the Living Pharmacy Project that has spread across the country. His journey through teaching, research and extension has always been guided by social work, which he saw as a matter of habit, to democratize the access of the poor to herbal medicines population. The Living Pharmacy Project is the result of the will of a researcher, teacher, idealist and foremost a citizen aware of their role in society. For dreamed, she ran to put into practice a desire, the desire to bring the people a pharmaceutical social assistance program.

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One of the foundations of the actual technology is the Quantum Mechanics. ThroughQuantum Mechanics, with the development of semiconductors physics, we are able to builddevices which, manipulate particles for certain purposes. As an example of these devices,we have the diode and transistor. In this thesis we seek physical systems, to obtain somequantum effects, theorically. The quantum effects which we want to obtain, are a bandstructure for photons and charged particles, the Aharonov-Bohm effect for photons andgeometric phases for relativistic particles described by non-Hermitian Hamiltonian. For thispurpose, the issues addressed here are: the study of photons in photonic crystals formed bytopological insulators, the description of systems of charged particles of varying mass, thestudy of dynamics of the charged particles with periodic mass, the study of the Aharonov-Bohm for the photon through a viscous uid, and the appearance of geometric phases forrelativistic particles described by non hermitian Hamiltonian. The main contributions ofour work was the proposal for a Hamiltonian which describes particles with variable mass,obtaining a structure of energy bands for a charged particle with periodic mass, obtaininga structure of frequency bands for photons in a photonic crystal formed by topologicalinsulators , showing the Aharonov-Bohm effect for the photon, where the vorticity of aviscous uid is the role of magnetic fields confined, and show that relativistic particlessubject to non-Hermitian Hamiltonian which varies slowly, has complex geometric phases.
A tecnologia que usamos nos dias de hoje tem como uma de suas bases principais, a Mecânica Quântica. Através da Mecânica Quântica, com o desenvolvimento da física dos semicontutores, somos capazes de construir dispositivos os quais, manipulam partículas para determinados fins. Como exemplo destes dispositivos, temos o diodo e o transistor, que são o coração da eletrônica. Nesta tese, buscamos teoricamente sistemas físicos para a obtenção de certos efeitos quânticos. Tais efeitos que desejamos obter são, uma estrutura de bandas para fótons e partículas carregadas, o efeito Aharonov-Bohm para fótons, efases geométricas para partículas relativísticas descritas por hamiltonianos não hermitianos.Para tal finalidade, os problemas tratados aquisição: o estudo de fótons em cristais fotônicos formados por isolantes topológicos, a descrição de sistemas de partículas carregadas de massa variável, o estudo da dinâmica de partículas carregadas de massa periódica, o estudo do efeito Aharonov-Bohm para o fóton através de um fluido viscoso, e o surgimento de fasesgeométricas para partículas relativísiticas sujeitas a hamiltonianos não hermitianos e que variam lentamente. As principais contribuições do nosso trabalho, foram a proposta paraum hamiltoniano que descreve partículas com massa variável, a obtenção de uma estruturade bandas de energia para uma partícula carregada com massa periódicas, a obtençãode uma estrutura de bandas de frequência para fótons num cristal fotônico formado porisolantes topológicos, á obtenção de um análogo do efeito Aharonov-Bohm para o fóton,onde a vorticidade de um uido viscoso faz o papel do campo magnético confinado, emostrar que partículas relativísticas sujeitas a hamiltonianos não hermitianos e que variamlentamentem, apresentam fases geométricas complexas.

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Abstract:

La physique quantique fut introduite au début du 20e siècle. Elle

apporte une nouvelle description du monde qui nous entoure et en

particulier de ce qu'on appelle le monde de l'infiniment

petit. Cette nouvelle théorie permet une description adéquate

notamment de l'effet photoélectrique, des niveaux énergétiques des

atomes, des réactions nucléaires, Elle apporte également une

réponse à de nombreuses problématiques telles que la catastrophe

ultraviolette. Néanmoins aussi séduisante que soit cette théorie,

les prédictions pour le moins contre-intuitives qu'elle apporte,

amène rapidement la controverse. Par exemple, en 1935, A.

Einstein, B. Podolski et N. Rosen en arrivent à mettre en doute la

physique quantique à cause d'une particularité que l'on y

rencontre, à savoir l'enchevêtrement. Il s'en

suit le célèbre débat avec N. Bohr et l'école de Copenhagen. Parmi

les autres aspects propres au monde quantique on peut encore citer

la superposition des états, le postulat de la mesure, le principe

d'incertitude d'Heisenberg, la dualité onde-corpuscule, le

théorème de non clonage, Toutes ces spécificités font de la

physique quantique un monde passionnant dans lequel, à l'instar du

pays des merveilles d'Alice, l'intuition est souvent dépassée.

Cette thèse est le fruit de quatre années de travail au cours

desquelles nous avons tenté d'observer et d'étudier certains des

effets intrigants que nous propose la physique quantique. Plus

précisément nous avons utilisé des états particuliers de la

lumière afin d'explorer une partie de ce qu'on appelle

l'optique quantique.

Dans un premier temps nous nous sommes intéressés aux possibilités

offertes par l'utilisation d'états cohérents de la lumière. En

utilisant ces états particuliers nous nous sommes penchés sur

l'étude ainsi que sur la réalisation expérimentale d'une tâche qui

se révèle impossible classiquement sans hypothèse computationelle.

Cette tâche consiste à réaliser un pile ou face entre deux joueurs

éloignés l'un de l'autre, par exemple deux joueurs communiquant

par téléphone. En effet, classiquement, un des deux joueurs pourra

toujours tricher de manière à avoir 100% de chance de gagner le

pile ou face.

Au contraire, si on utilise les ressources offertes par la

communication quantique, il est possible de construire des

protocoles ne permettant plus à aucun des deux joueurs de tricher

parfaitement et ce, sans aucune hypothèse supplémentaire. Même si

aucun protocole quantique ne peut empêcher totalement toute

tricherie, leur démonstration constitue une preuve de principe

quant aux possibilités offertes par la physique quantique dans la

réalisation de tâches classiquement impossibles.

Lors de notre étude du problème, nous avons développé un protocole

de pile ou face quantique et étudié ses performances. Nous avons

montré que les tentatives de tricherie des deux joueurs avaient

une probabilité de succès limitée à 99,7%<100% (biais inférieur

à 0,497). L'originalité de cette étude se situe dans le fait que

les imperfections expérimentales (efficacité des détecteurs,

pertes de transmission, visibilité réduite, ) furent prises en

compte, ce qui à notre connaissance n'avait jamais été réalisé. En

outre nous avons réalisé une implémentation en optique fibrée de

notre protocole et démontré la réalisation d'un pile ou face

unique au cours duquel aucun des deux joueurs ne pouvait

influencer parfaitement le résultat, ce qui à notre connaissance

n'avait également jamais été démontré. L'emploi d'états cohérents

de la lumière fortement atténués nous a donc permis de concevoir

un protocole de pile ou face quantique et de réaliser une

démonstration expérimentale en optique fibrée, d'une tâche

impossible à réaliser classiquement.

Après avoir travaillé avec des états cohérents fortement atténués,

nous nous sommes intéressés à un autre état quantique de la

lumière, à savoir les paires de photons. Ces états constituent non

seulement une ressource essentielle pour sonder les effets

quantiques de la lumière mais également une ressource

incontournable pour l'information et la communication quantique.

Nous nous sommes donc attelés à la réalisation d'une source

produisant ces paires de photons.

Les premières sources de paires

de photons furent basées sur l'utilisation de cristaux dans

lesquels il existe une interaction non linéaire entre la lumière

et le matériau du cristal. Malheureusem*nt le désavantage majeur

de ces sources est la difficulté à collecter les paires de photons

générées. Nous avons donc étudié la possibilité de générer des

paires de photons directement dans une fibre optique, la

collection des paires y étant réalisée de facto.

La première solution que nous avons envisagée consiste à utiliser

la non-linéarité du troisième ordre de la silice composant les

fibres optiques. Plus précisément le phénomène utilisé est appelé

l'instabilité de modulation. Ce phénomène permet de détruire deux

photons de pompe afin de générer une paire de photons vérifiant

les conservations de l'énergie et de l'impulsion. En outre nous

avons choisi d'utiliser une fibre optique microstructurée. Ces

fibres permettent en effet un plus grand confinement de la lumière

que les fibres standards. Il en résulte une interaction non

linéaire plus importante, permettant ainsi de générer des paires

de photons de manière plus efficace. La fibre utilisée est en

outre biréfringente, ce qui permet d'avoir accès à deux types

particuliers d'instabilité de modulation: l'instabilité scalaire

et l'instabilité vectorielle.

Dans un premier temps, nous avons observé le processus

d'instabilité de modulation dans un régime classique. Les

paramètres particuliers de notre fibre microstructurée - forte

dispersion anormale et biréfringence modérée

- nous ont permis d'observer un régime

d'instabilité dans lequel l'instabilité de modulation vectorielle

se produit à des fréquences proches de la fréquence de pompe

($Omegasim 1$THz). Il en résulte que les bandes de gain liées à

l'instabilité de modulation vectorielle sont très proches des

bandes de gain liées à l'instabilité de modulation scalaire. Nous

avons observé que dans ce régime particulier, les densités

d'énergie générées par instabilité de modulation vectorielle sont

supérieures à celles générées par instabilité de modulation

scalaire. A notre connaissance, il s'agit de la première

observation expérimentale permettant de mettre en évidence un gain

vectoriel supérieur au gain scalaire.

La génération de paires de photons grâce à ce processus nécessite

de diminuer la puissance de pompe envoyée dans la fibre.

Malheureusem*nt nous avons mesuré que dans ce régime de faible

puissance (régime quantique), la qualité des paires de photons

générées était fortement dégradée par la présence de photons

parasites générés par diffusion Raman spontanée. Nous avons estimé

que lorsque la puissance de pompe est abaissée suffisamment pour

générer en moyenne 0,1~photons dans la bande de gain d'instabilité

de modulation vectorielle ($sim$1543 nm), environ 75% des

photons détectés auront été générés par diffusion Raman spontanée.

Afin de mettre en oeuvre des expériences d'optique quantique

utilisant des paires de photons, des solutions doivent donc être

appliquées à notre source afin de réduire le nombre de photons

générés par diffusion Raman spontanée. Parmi ces solutions nous

pouvons citer la discrimination en polarisation des photons

générés ainsi que le refroidissem*nt de la fibre grâce à de

l'azote liquide. Ces solutions permettraient de réduire le nombre

de photons Raman anti-Stokes d'un facteur 18 et le nombre de

photons Raman Stokes d'un facteur 4. Malheureusem*nt la tenue de

la fibre microstructurée à de très basses températures reste

incertaine et l'implémentation de ces solutions rendrait la source

difficilement utilisable.

Notre première tentative pour générer des paires de photons dans

une fibre optique nous a montré que les paires de photons générées

grâce à un processus d'interaction non linéaire du troisième ordre

étaient polluées par des photons générés par diffusion Raman

spontanée. Une source de paires de photons efficace ne pouvait

donc pas être obtenue sans l'aide de solutions technologiques

assez lourdes à mettre en oeuvre.

Nous avons donc investigué une deuxième solution afin de réaliser

une source produisant des paires de photons dans une fibre

optique. Puisque les non-linéarités du troisième ordre semblent

être peu adaptées pour la génération de paires de photons, nous

sommes revenus à une non-linéarité du second ordre. Dans ces

processus c'est un photon de pompe qui est détruit afin de générer

une paire de photons, tout en respectant les conservations de

l'énergie et de l'impulsion. Malheureusem*nt les fibres optiques

ne permettent pas l'apparition de non-linéarités du second ordre

et ce, à cause de la centrosymétrie macroscopique du verre de

silice qui compose ces fibres.

Afin d'induire une non-linéarité du second ordre dans une fibre

optique nous avons travaillé en collaboration avec l'équipe du

Prof. P. G. Kazansky de l'université de Southampton. En utilisant

les techniques de poling thermique et d'effacement par

illumination UV, ils réalisèrent une fibre optique twin-hole

périodiquement polée dans laquelle les non-linéarités du second

ordre furent possibles.

Grâce à cette fibre nous avons réalisé une source de paires de

photons combinant les avantages des effets non linéaires du second

ordre, i.e. la puissance de pompe nécessaire est moindre

que dans le cas d'une non-linéarité du troisième ordre, la

diffusion Raman spontanée n'influence aucunement les paires de

photons générées, et les avantages de la fibre optique,

i.e. la collection des paires de photons y est réalisée

de facto, le mode spatial transverse des paires de photons

est bien défini. La mesure du pic de coïncidences de notre source

fournit un rapport entre le sommet du pic et le niveau des

coïncidences accidentelles de 7,5. Une efficacité conversion

$P_s/P_p=1,2,10^{-11}$ fut obtenue en utilisant 43~mW de

puissance de pompe. En outre les paires de photons générées

possèdent une longueur d'onde de 1556~nm se trouvant ainsi dans la

bande C des télécommunications optiques (1530-1565~nm). Elles sont

donc bien adaptées à une éventuelle application en communication

quantique, dans les réseaux de fibres optiques actuellement

utilisés pour les télécommunications optiques. Enfin nous avons

utilisé ces paires de photons afin de réaliser l'expérience de

Hong-Ou-Mandel permettant de mettre en évidence un effet propre à

la physique quantique, à savoir le photon bunching. Une visibilité

nette de 40% fut obtenue pour le Mandel dip dans une

configuration où la visibilité maximale vaut 50%. En outre cette

expérience nous a permis de développer une expertise dans la

réalisation d'interféromètres fibrés, stabilisés et contrôlés en

température.

La source de paires de photons que nous avons réalisée constitue

une démonstration de principe quant à la faisabilité d'une telle

source. A l'époque de ce travail, la fibre dont nous disposions

était l'une des premières fibres twin-hole périodiquement polées.

Aujourd'hui de nombreux paramètres de la fibre ont été améliorés

et permettent la réalisation d'une source de paires de photons

tout à fait compétitive avec les autres sources existantes. Ainsi

l'équipe du Prof. Kazansky est capable de réaliser des fibres

périodiquement polées de 20 cm de long possédant une efficacité de

conversion normalisée de seconde harmonique de

$eta_{SH}=8;10^{-2}$\\%/W. Si l'on suppose toujours une puissance

de pompe de 43 mW, cela mène à une efficacité de conversion de

$1,0;10^{-9}$ pour le processus de fluorescence paramétrique,

soit une amélioration de deux ordres de grandeurs par rapport à

notre démonstration. La réalisation d'une source de paires de

photons dans une fibre optique périodiquement polée qui serait non

seulement utilisable dans des expériences de physique fondamentale

mais également dans des applications en communication quantique,

est donc tout à fait envisageable dans un futur proche.

Pour résumer, nous avons, au cours de cette thèse, réalisé, dans

un premier temps, la tâche classiquement impossible qui consiste à

jouer à pile ou face à distance. Ensuite dans l'optique de générer

des paires de photons, nous avons étudié le processus

d'instabilité de modulation dans une fibre microstructurée. Nous

avons ainsi observé un régime particulier dans lequel

l'instabilité de modulation vectorielle possède un gain supérieur

à celui de l'instabilité de modulation scalaire. Enfin toujours en

quête d'une source de paires de photons, nous avons réalisé une

source produisant des paires de photons par fluorescence

paramétrique dégénérée au sein d'une fibre optique twin-hole

périodiquement polée. Les trois principaux sujets abordés au cours

de cette thèse ont donc en commun l'utilisation de l'optique

fibrée pour la manipulation ou la génération d'états quantiques de

la lumière. Il en a résulté l'obtention de trois résultats

originaux qui nous ont ainsi permis d'explorer une partie du monde

intrigant et fascinant de l'optique quantique.

/

Quantum physics was introduced early in the 20th century. It

brings a whole new description of our world, mostly at the

microscopic level. Since then, this new theory has allowed one to

explain and describe lots of physical features like the

photoelectric effect, the energy levels of atoms, nuclear

reactions, It also brought an answer to lots of remaining

unanswered questions like the so-called ultraviolet catastrophe.

Though, as attractive as this new theory was at that time, some of

its counter-intuitive predictions quickly gave rise to

controversy. For instance, in 1935, due to one quantum physics

feature called entanglement, A. Einstein, B. Podolski and N. Rosen

asked the question: "Can quantum-mechanical description of

physical reality be considered complete?". This led to

the famous debate with N. Bohr and his Copenhagen interpretation.

Amongst other particular features of quantum physics one can cite:

the superposition principle, the wave function collapse, the

Heisenberg uncertainty principle, the wave-particle duality, the

no-cloning theorem, As in Alice in wonderland, all those

features actually make quantum physics a fascinating world where

intuition is most of the time useless.

In this thesis we tried to observe and study some of the

intriguing features of quantum physics. More precisely we tried to

use specific light states to explore part of what is called

quantum optics.

First we studied the use of coherent states of light to perform

tasks you can not perform using classical physics. For instance in

1984, Ch. Bennett and G. Brassard proposed the first quantum

cryptography protocol which has an absolute security

while classical protocol security still relies on some

computational assumptions (the assumption is that today

computers computational power is not sufficient to threaten the

security of classical protocols. Though this means that classical

protocols are not intrinsically secure). Since then quantum

physics has been proven useful to perform lots of classically

impossible tasks like bit commitment, quantum computation, random

number generation, In this work we were interested in the

problem of coin tossing by telephone introduced by M. Blum

in 1981. In this problem two untrustful and distant

players try to perform a coin flip. Classically one can show that,

if no computational assumptions are made, one of the players can

always force the outcome of the coin flip.

On the opposite if one uses quantum communication resources, a

protocol in which none of the players can cheat perfectly can be

built, i.e. none of the players have 100\\% chance of

winning the protocol even by using the best possible cheating

strategy. Moreover this is possible without any other assumption

than the validity of the laws of physics. Though a quantum

protocol for coin tossing can not completely prevent from cheating, the demonstration of such a protocol would

be a proof of principle of the potential of quantum communication

to implement classically impossible tasks.

In our work, we have developed a quantum coin tossing protocol and

studied its performances. We have shown that the success cheating

probability of the players is bounded by 99,7%<100%, which is

better than what is achieved in any classical protocol. One of the

originalities of our work is that, for the first time to our

knowledge, experimental imperfections (detectors efficiency,

losses, limited interference visibility, ) have been taken into

account in the theoretical analysis. Moreover, using coherent

states of light, we have demonstrated a fiber optic experimental

implementation of our protocol and performed a single coin flip

where none of the two players could perfectly influence the

outcome. This is to our knowledge the first experimental

demonstration of single quantum coin tossing.

After coherent states of light, we wanted to work with a more

complex quantum state: photon pairs. Not only those states are

useful for fundamental physics tests but they also are an

important resource for quantum communication. For those reasons

our first objective was to build a source that would generate

those photon pairs.

First photon pairs sources were based on bulk nonlinear crystals.

Unfortunately the main drawback of those sources is the low

collection efficiency of the generated photon pairs. That's why we

investigated the possibility of generating the photon pairs

directly in a waveguiding structure where they would be readily

collected.

The first solution that we envisaged was to use the natural third

order nonlinearity of silica fibers. More precisely the phenomenon

we wanted to used is called modulation instability. In this

process, two pump photons are destroyed and a photon pair is

created with energy and momentum conservations. Moreover we

decided to use this process in a photonic crystal fiber. The high

confinement of light in this kind of fiber allows a higher

nonlinearity and thus a more efficient generation of photon pairs.

Finally the fiber we used was birefringent which enables both

vectorial and scalar modulation instability to occur.

As a first experiment, we decided to observe modulation

instability in a classical regime where a lot of photons are

created. The specific parameters of our photonic crystal fiber -

high anomalous dispersion and moderate birefringence - allowed us

to observe a regime where the vectorial instability gain band has

a similar detuning from the pump as the scalar instability gain

band. In this regime we also observed an enhancement of the

vectorial gain above the scalar gain which has been confirmed

theoretically. To our knowledge this was the first experimental

observation of this particular regime of instability.

To generate photon pairs with this instability process we need to

lower down the pump power. Unfortunately we measured that, when

pump power was sufficiently lowered to generate ~0,1 photon

pairs per pump pulse sent in the fiber, about 75% of generated

photons were created by spontaneous Raman scattering and not

modulation instability. In order to build an efficient photon pair

s secteurs financiers et, en particulier, au rôle de la religion musulmane. Nous montrons que, en moyenne, la finance islamique favorise le développement du secteur bancaire dans les pays musulmans. Plusieurs pays ont en effet réussi à développer un nouveau secteur bancaire compatible avec la Shariah, sans porter ombrage au secteur bancaire non islamique avec lequel il co-existe. Notre analyse empirique est fondée sur une base de données nouvelle et originale. Celle-ci a pour intérêt de fournir des indicateurs de taille et de performance des banques islamiques de dépôt dans le monde, pour la période 2000-2005.

Dans le deuxième essai, nous explorons les rendements inconditionnels obtenus sur les marchés boursiers, en particulier les marchés émergents d'actions. Notre analyse d'un large panel de 53 marchés émergents "Majeurs" et "Frontières" confirme les résultats traditionnellement observés dans la littérature. Ainsi, pour l'essentiel, les deux types de marchés sont volatils et émaillés d'événements extrêmes. De plus, les rendements des marchés émergents sont faiblements corrélés avec ceux du reste du monde, même si ces corrélations ont augmenté au cours des derniers décennies. Malgré d'importantes différences en terme de taille et de liquidité, les rendements sur marchés "Frontières" sont qualitativement similaires à ceux des marchés "Majeurs", à l'exception des corrélations. Ces dernières sont en effet actuellement plus faibles dans les marchés "Frontières", qui continuent dès lors à offrir d'importants bénéfices de diversification aux investisseurs internationaux.

Dans le dernier essai, nous examinons la relation entre les transferts d'argent des migrants et la croissance économique. Nous confirmons l'idée que les transferts de fonds des migrants sont importants pour les pays en voie de développement. Mais surtout, nous démontrons, de manière théorique et empirique, qu'il est crucial de faciliter dans ces pays l'accès aux comptes de dépôt bancaires, afin de transformer une plus grande part des transferts des migrants en investissem*nts productifs. Ceci est d'autant plus vrai quand l'accès aux autres sources de capitaux internationaux est coûteux.

on pairs well defined). A coincidence

measurement was performed resulting in a coincidence peak with a

7,5 ratio between the peak and the accidental coincidences level.

A conversion efficiency $P_s/P_p=1,2,10^{-11}$ was obtained using

43 mW of pump power. Moreover photon pairs were generated around

1556~nm in the optical communications C-band, which makes them

suitable for quantum communication applications using installed

fiber optic networks. Finally using the generated photon pairs we

performed the Hong-Ou-Mandel experiment highlighting the bosonic

nature of photons. We obtained a Mandel dip with a net visibility

of 40% in a configuration where the maximum visibility is 50%.

The photon pair source that we realized is a proof of principle of

the high potential of poled fibers in quantum applications. Indeed

today, Prof. P. G. Kazansky's team is able to make a 20 cm poled

fiber with a nonlinearity $eta_{SH}=8;10^{-2}$\\%/W. If we still

suppose 43~mW of pump power, this leads to a $1,0;10^{-9}$

conversion efficiency for parametric fluorescence, improving our

result by two orders of magnitude. The realization of an efficient

photon pair source based on parametric fluorescence in

periodically poled twin-hole fiber suitable for quantum

applications is thus absolutely possible in a very near future.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

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Submitted by Isaac Francisco de Souza Dias (isaac.souzadias@ufpe.br) on 2016-03-02T19:08:33ZNo. of bitstreams: 2license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5)Tese José Ferraz.pdf: 2743054 bytes, checksum: 9154337dac4a587934aab71697b77a90 (MD5)
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CNPQ
Neste trabalho, utilizamos as técnicas de controle temporal coerente e de manipulação da faseóptica do campo óptico para investigar e controlar os diferentes caminhos quânticos induzidosem transições de dipolo elétrico envolvendo a absorção de dois fótons no átomo de rubídio. Astransições foram excitadas por pares de pulsos de separação temporal variável e analisamos aresposta do meio atômico em função dessa separação. Três situações experimentais são analisadasenvolvendo transições com diferentes características.No primeiro experimento, utilizamos luz incoerente de um laser de corante com duração temporalde nanosegundos, mas com tempo de coerência de picosegundos, para excitar a transiçãode dois fótons, envolvendo níveis altamente excitados, níveis de Rydberg. A resposta do sistemaé analisada através de um processo de mistura de quatro ondas, resolvida no tempo, e a seleçãodos diferentes caminhos quânticos envolvidos no processo é feita a partir do controle da polarizaçãodos campos do laser incidente. Interferências na freqüência central do laser, interferências"ópticas", e no dobro dessa freqüência, interferências quânticas, são observadas.Nos outros dois estudos, a transição de dois fótons é excitada por pulsos com duração temporalda ordemde 100 fentosegundos. No primeiro caso, investigamos uma transição de dois fótons pura,entre os níveis 5S e 7S do rubídio, onde uma fase externa, dependente da freqüência, é adicionadaem um dos pulsos, enquanto o outro tem seu atraso temporal controlado. A fluorescência detectadaé uma medida direta da população do estado excitado. Novamente, um sinal interferométrico éobservado, cujo controle coerente é efetuado por uma combinação da fase externa e do atrasotemporal.O último experimento envolve uma transição seqüencial, cuja ressonância de um fóton leva aefeitos de propagação observados no sinal de interesse. Outro aspecto importante é que a taxa derepetição do laser era maior que as taxas de relaxação dos níveis envolvidos, de forma que efeitosde acumulação na população e na coerência também estão presentes. A resposta do sistema éanalisada através do processo de mistura paramétrica de quatro ondas, resolvido no tempo. Osinal interferométrico, com controle de polarização e da freqüência de detecção, permite umademonstração clara da origem quântica nas interferências "ópticas".
In this work, we use the techniques of temporal coherent control and phase manipulation of theoptical field to investigate and control different quantum pathways in the two-photon absorptionin rubidium atoms. Three experimental situations are studied involving transitions with differentcharacteristics. In all of them, the medium response is analyzed as a function of the temporal delaybetween the pulse pairs responsible for the two-photon transition.In the first experiment, we use incoherent light from a dye laser with pulse duration in thenanosecond scale, but with coherence time in the picosecond scale, to excite the two-photon transition,which involves highly excited levels, Rydberg states. The system response is analyzedthrough a time-resolved four-wave mixing process, and the quantum pathway selection is realizedby polarization control of the incident laser fileds. Interferences in the central laser frequency -"optical" interferences - and at twice this frequency - quantum interferences - are observed.In the subsequent two studies, the two-photon transition is excited with 100 fs pulses. In thefirst case, we investigate a pure two-photon transition, the 5S - 7S rubidium transition, where anexternal frequency depedent phase is added in one pulse, while the temporal delay of a secondpulse is controlled. We observe an interferometric signal, in which coherent control is achievedwith external phase and temporal delay combination.The last experiment involves a sequential transition, which has a one-photon resonance thatleads to propagation effects observed in the signal. The laser repetition rate is greater than theatomic system relaxation rates, leading to accumulation effects in the population and coherence,which leads to important effects. A time-resolved parametric four-wave mixing is used to investigatethe system response. The interferometric signal, with polarization and detection frequencycontrol, allows us to clearly demonstrate the quantum origin of the "optical" interferences.

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La microscopie non linéaire a transformé le domaine de la neurobiologie depuis les années 1990, en permettant d'acquérir des images tridimensionnelles de tissus épais avec une résolution subcellulaire. Cependant, les profondeurs d'imagerie accessibles sont limitées à quelques centaines de micromètres dans des tissus diffusants tels que le tissu cérébral. Au cours des dernières années, plusieurs stratégies ont été développées pour dépasser cette limitation de profondeur et accéder à de plus grands volumes de tissu. Ces avancées récentes ont jusqu'à présent été limitées en terme de modes de contrastes accessibles, et ont souvent été réduites à des approches monochromes. Ce travail de thèse vise à développer des techniques d'imagerie non linéaires de grands volumes et de grande profondeur dotées de diverses possibilités de contrastes, indispensables pour l'étude de tissus complexes tels que le tissu cérébral. Dans un premier chapitre, nous présentons les difficultés associées à l'imagerie de grand volume de tissu cérébral, avec une emphase particulière sur les puissantes stratégies de marquages génétiques dont l'usage à jusqu'à présent été limité à des faibles étendues. Ensuite, nous introduisons la microscopie Chrom-SMP (chromatic serial multiphoton), une méthode développée au cours de cette thèse et consistant à combiner l’excitation deux-photon multicouleurs par mélange de fréquences avec une technique d'histologie automatisée (i.e découpe sériée) pour accéder à plusieurs contrastes non linéaires à travers de grands volumes de tissus ex vivo, allant de plusieurs mm3 à des cerveaux entiers, avec une résolution micrométrique et un coalignement intrinsèque des canaux spectraux. Dans un troisième chapitre, nous explorons le potentiel de cette nouvelle approche pour la neurobiologie. En particulier, nous démontrons l'histologie multicouleur de plusieurs mm3 de tissu "Brainbow" avec une résolution constante dans l’ensemble du volume imagé. Nous illustrons le potentiel de notre approche à travers l'analyse de la morphologie, des interactions et du lignage des astrocytes du cortex cérébral de souris. Nous explorons également l’apport du Chrom-SMP pour le suivi multiplexé de projections neuronales marquées par des traceurs de couleurs distinctes sur de grandes distances. Enfin, nous présentons dans un quatrième chapitre le développement de la microscopie à trois photons multimodale, approche permettant d’augmenter la profondeur d’imagerie sur tissus vivants
Multiphoton microscopy has transformed neurobiology since the 1990s by enabling 3D imaging of thick tissues at subcellular resolution. However the depths provided by multiphoton microscopy are limited to a few hundreds of micrometers inside scattering tissues such as the brain. In the recent years, several strategies have emerged to overcome this depth limitation and to access larger volumes of tissue. Although these novel approaches are transforming brain imaging, they currently lack efficient multicolor and multicontrast modalities. This work aims at developing large-scale and deep-tissue multiphoton imaging modalities with augmented contrast capabilities. In a first chapter, we present the challenges of high-content large-volume brain imaging, with a particular emphasis on powerful multicolor labeling strategies which have so far been restricted to limited scales. We then introduce chromatic serial multiphoton (Chrom-SMP) microscopy, a method which combines automated histology with multicolor two-photon excitation through wavelength-mixing to access multiple nonlinear contrasts across large volumes, from several mm3 to whole brains, with submicron resolution and intrinsic channel registration. In a third chapter, we explore the potential of this novel approach to open novel experimental paradigms in neurobiological studies. In particular, we demonstrate multicolor volumetric histology of several mm3 of Brainbow-labeled tissues with preserved diffraction-limited resolution and illustrate the strengths of this method through color-based tridimensional analysis of astrocyte morphology, interactions and lineage in the mouse cerebral cortex. We further illustrate the potential of the method through multiplexed whole-brain mapping of axonal projections labeled with distinct tracers. Finally, we develop multimodal three-photon microscopy as a method to access larger depths in live settings

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碩士
國立臺灣科技大學
資訊工程系
103
Recently on the app store, a few apps that use a single photo to model human faces have been released. The most obvious flaw of the apps is the results are not as similar to the original face as expected, since the most common method they use is to apply a 2D face image directly to a predefined 3D face template model. Therefore, the similarity between the final result and the original face photo can be observed from the similarity between the 3D template model and the original face photo. In this paper, we propose a novel method for creating a 3D model that has more likeness to the original human face.

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碩士
中華大學
資訊工程學系(所)
98
Face detection has been studied for a variety of applications. Computer recognition of face detection in digital images has been put to use in security monitoring, digital cameras to name a few. In this project, a prototype algorithm for automating the detection of human faces in digital photographs was developed and can serve as an introduction for future work in detecting people in images.The skin detection is performed using a skin filter which relies on color and texture information. The face detection is performed on a grayscale image containing only the detected skin areas. A combination of skin color, rectangle feature and cascade classifier are used to extract face features that would be easier to detect a human face in image. We can reduce both the computational complexity and the memory usage, and make the face detection algorithm put in to low cost digital photo frame.

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碩士
臺灣大學
資訊工程學研究所
95
One of the main challenges faced by the current face recognition techniques lies in the difficulties of collecting samples. A large number of representative training samples are required to capture the considerable amounts of variations one face may undergo due to illumination, pose, expression, etc. In this paper, a classification framework is introduced as an attempt to alleviate the tedious effort spent on collecting training samples (i.e. speed up the annotation process). The user is required to annotate a small number of faces detected from the input photo set as different subjects (i.e. different clusters). Then, based on the technique of so-called generic learning, we classify the remaining faces into one of these clusters by comparing their pair-wise face similarities. A novel automatic face alignment algorithm is also devised for saving the user efforts on labeling eye coordinates. To boost the recognition performance in this one training sample application scenario, we extract context information as another cue for recognizing people. In addition, relevance feedback can also be added in a novel and intuitive way to iteratively refine the classifacation result. At the end of this article, experiments on real consumer photo albums are performed to demonstrate the effectiveness of the proposed framework.

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碩士
國立臺北科技大學
資訊工程系研究所
97
With the increasing availability of digital cameras, one can easily collect a largenumber of photos. In this paper, we present a prototype system aimed to achieveefficient management of photos of people. Using current face detection andrecognition technologies, we provide both automatic and semi-automatic methods tofacilitate the job of associating photos to people. A series of preprocessing methodsare taken to improve recognition rate for faces captured in varying lighting conditionsand poses. We found that a personal photo collection of a single event may containonly a limited group of people. We can set up a face classifier specific for the group ofpeople. A threshold scheme separates people not in the group or faces that can not beconfidently identified apart. The organized result helps pick out incorrectly identifiedfaces. A semi-automatic approach is used to deal with the leftovers by giving threecandidates to choose from. Our proposed system is equipped with comprehensive userinterface designed for these tasks. We conducted a simulation of this usage showingthat it can dramatically reduce the amount of work on a very large set of photos.

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Thesis (M.S.)--Florida State University, 2004.
Advisor: Dr. David C. Banks, Florida State University, College of Arts and Sciences, Dept. of Computer Science. Title and description from dissertation home page (viewed Oct. 27, 2004). Includes bibliographical references.

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碩士
國立清華大學
電機工程學系
105
With the development of social media and personal cloud service, everyone can upload their media data easily. According to statistics, the number of photos uploaded to Facebook can reach 300 million. With that, how to manage the personal photo album efficiently has becomes an issue. Face clustering plays as an important role in it. Face clustering is a technique to perform clustering on an unlabeled face dataset. Although face recognition has been well developed in the past decades that good representations can well describe faces. The difficulty of face clustering is that facial features may be very different for the same person or features maybe similar for different person due to various expression, lightning, poses. Face clustering only depends on visual feature often over-clustered (clusters with high precision but very low recall). Other than visual information of image itself, personal album contains other metadata like: whether faces are taken in same photo (co-occurrence); when the photo was taken ..., this additional information may lead to a better cluster result that visual information is not capable of. For instance, faces detected in the same photo must not be the same person, while photos in the same scene usually contain the same group of people. We call this kind of information “social information”. In this thesis, we will try to mine social information from a personal photo album and improve the purely visual based clustering result. Feeding back the results improved by social information to the feature extraction step, the initial clustering can provide results considering both visual and social information. Our experiments show that the clustering performance is improved by the iterative procedure.

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碩士
長庚大學
資訊工程學系
103
In recent years, facial expression recognition is the subject of many experts and scholars, in the study of development of this paper is to develop an automated face recognition system. The human images is captured by the video system and send it to SVM model for feature extraction. Then classification is done based upon the extracted feature values which is our main goal.Most of face recognition system is seeking to track certain facial features (such as eyes, eyebrows, mouth or nose) automatically. But the results showed that, capturing of facial features are in efficient due to the image quality, light, and angles on other confounding factors.According to these ideas, the first image is provided the human face, we defined 68 feature points on the face, will do first after normalization standard feature points out some crooked positive image. We also define 18 feature values made after the feature point calculation using the ratio of the ways to solve problems caused by errors face distance. We use CK+ database and self-built database to train SVM model using SVM classifier. After the training phase of SVM model, the system is now ready to capture the facial expression and classify them accordingly. Our experimental results show that, the system will perform well with good accuracy to classify the facial expression.

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Morphable guidelines are a 3D structure that helps users achieve better face warping on 2D portrait images. Faces can be difficult to warp accurately because the rotation of the head affects the shape of the facial features. I bypass the problem by utilizing the popular Loomis ‘ball and plane’ head drawing guideline as a proxy structure. The resulting ‘morphable guidelines’ consist of a simple 3D head model that can be reshaped by the user and aligned to their input image. The vertices of the model go on to act as deformation points for a 2D image deformation algorithm. Thus, the user can seamlessly transform the face proportions in the 2D image by transforming the proportions of the morphable guidelines. This system can be used for both retouching and caricature warping purposes, as it is well-suited for both subtle and extreme modifications. This system is advantageous over previous work in face warping because our morphable guidelines can be used on a wide range of head orientations and do not require the generation of a full 3D model.
Graduate
0984
syugao@gmail.com

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Collective memory has recently become one of the most explored topics in the social sciences and has led to the emergence of a separate and independent subdiscipline called memory studies. The thesis investigates the awakening of collective memory in two borderlands of Central Europe: the former Sudetes region in the Czech Republic and the southern part of former East Prussia in Poland. The thesis provides an overview of the current theories about collective memory with a focus on the interactional and visual character of the studied phenomenon. In line with this, the thesis presents, discusses, and elaborates on research conducted in the two borderlands in 2016 and 2017. The aim of the research was to study the role and form of collective memory (shared remembrance) in ethnic, cultural, and historical borderlands. The contributions of the thesis are both methodological and theoretical. Firstly, the discussed research revealed that between particularly family-based communicative memory and official, institution-generated cultural memory, there is ritualised communicative memory, maintained through interactions among members of the borderland community (community of memory). Secondly, the thesis contributes to various studies within the interactionist paradigm and proves the usability of Goffman's...

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碩士
國立中正大學
電機工程研究所
92
In this thesis, we combine three techniques including face detection, feature points location and feature vectors verification to develop our face recognition system for complex environment applications. However, when persons are recognized in a complex environment, the correct positions of their faces and their facial feature points are difficult to locate owing to complex background, head angle and various lighting. In order to improve these problems, we adopt dynamic skin segmentation technique, robust feature location algorithms and Viterbi algorithm for face detection, feature points location and verification respectively. In our face detection stage, we first generate a 7-line dynamic polygon which can change its shape varying with the luminance in YCbCr space to separate skin color from other colors and bound the range of human face. In our feature point location stage, we utilize some digital image processing techniques to search the accurate coordinates of feature points. After locating the feature points, we transform the feature points into feature vectors and then compare them with database. In our verification stage, human face is divided into five regions with Viterbi algorithm to search the best matching in database. The Viterbi algorithm can reduce the influence of error locations of feature points and output the true result by the principal of minimum cost. Experimental results show that our system can recognize quickly with high recognition rate.

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碩士
國立中正大學
資訊工程所
97
With the thriving market of digital cameras, people could record their daily life with ease. Organizing digital photos with efficiency is an indispensable requirement for digital camera users. To organize photos, we may sort them by timestamps, locations, topics or human faces. Among various means of photo classification, browsing by human faces is one of the most appealing manners for photo management. As mentioned above, the objective of this thesis is to advance photo management through clustering photo effectively and automatically into the same face’s category. For consumer photos, this work becomes tough because photos are with large variations in lighting, pose and expression. For conquering the uncertain environment in daily photos, we leverage Scale-Invariant Feature Transform (SIFT), which is the most commonly used algorithm in computer vision field for these years. We expect to increase performance by employing SIFT, which is robust to reasonable changes in scale, rotation, viewpoint and illumination. After matching face images by local feature points, we transform matching results into a novel representation called visual sentences. Thereupon visual language models are constructed to describe face matching situations. With the probabilistic framework based on visual language models, we develop a clustering algorithm to group the same individual’s face images into the same cluster. For evaluating, we compare the proposed visual language model method with a Baseline approach, and we demonstrate the superiority of our method.

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Abstract:

碩士
元智大學
資訊工程學系
96
In the past few years, the need of detecting human faces plays an important role in many visual applications, and the amount of related technologies are growing rapidly. There are many technologies of human face location, and the method by using the skin color of face to segment the face scope is one of the most commonly used technologies. However, there are many problems about this method, so it is difficult to segment the human face correctly from the background when the background color is close to the skin color.In this paper, we propose an automatic system for locating human face and determining the best representative among face photos. We combine several methods, including moving detection, skin color detection, and feature detection, to locate the positions of human face. When all detections is finished, the system will select the best representative among face photos.

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Abstract:

碩士
國立中正大學
電訊傳播研究所
94
The emergence of online photo albums offers a channel for self-expression with assistance of pictures alone with words. Meanwhile, the interaction of online users also has an influence on the way in which the photo albums are being used.The technique of diffused audience circle of the Spectacle/Performance Paradigm (SPP) is being adopted in this study in an attempt to investigate online photo album users in terms of their performance and narcissism process. Furthermore, the correlation between SPP and Internet Addiction will be explored through the analysis of “instrumental usage” as contrast with “ceremonial usage.”This study combines the methods of quantitative research (questionnaire) and qualitative research (in-depth interview). The results of questionnaire identify seven motives for people using online photo albums; namely “Information Seeking”, “Friendship Making”, “Diversion and Fun”, “Relationship Maintenance”, and “Aesthetics Seeking” for ceremonial usage, and “Interface Convenience” and “Monetary Compensation” for instrumental usage. On the other hand, in-depth interview suggests people would use online photo albums on the purpose of self-expression in a way to share their lives with others. In addition, results also indicate that people with motives concerning ceremonial usage have the tendency to Internet Addition, and that student group together with those online for a longer period of time is subject to Internet Addition as well.Also through the analysis of regression method with regard to diffused audience, ceremonial usage and Internet Addition, positive correlations have been identified among those three. Respondents with signs of diffused audience would be prone to stay online longer and be more involved in online activities, thus leading to an inclination to Internet Addition.The results of in-depth interviews suggest that online photo albums have caused a significant influence on interviewees in terms of their lives in that they spend lots of time not only online but offline as well. As for online celebrities thanks to the emergence of online photo albums, they have accumulated a growing popularity to an extent that they even have more exposure on media, let alone a growing number of fan base. The fans sometimes achieve a sense of self-identification in admiration of online celebrities. On the other hand, the interaction between online celebrities and fans has led to the way in which the former express themselves and post pictures.The roles of spectators and performers have some degree of interchangeability. When performing, the performers are aware of the fact that they are being watched, and in order to present an ideal side of themselves, they would do something extra in attainment of better appearances. In other words, self-image is of importance so far as the respondents are concerned; they would weigh against their perspective of self-image to decide how they would like to present themselves.

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碩士
國立成功大學
地球科學系
104
The black-faced spoonbill (BFS) is a globally endangered species. The annual international BFS census (IBFSC) thus serves as an important initiative to manage and protect the population of this bird. This work attempts to investigate the feasibility of supporting the annual IBFSC with a low-cost unmanned aerial vehicle system (UAVS). The flight plan for each mission was made through the automatic mission planning system. All photographs taken in one mission were stitched to a seamless and color-balanced mosaic that can be geo-referenced and displayed on a Web-based platform, such as Google Earth. A close-up photograph of a few BFSs was acquired at a low altitude of 50 m to validate the proposed approach of image processing, including unsupervised classification, hit or miss transform, objective and spatial statistics analyses. The results show that the selection of one statistical attribute (maximum value in red channel) and two geometrical attributes (size and circularity) is appropriate for identifying BFS without ambiguity. The success of this work encourages us to conduct a large-scale deployment of UAVS in the coming IBFSC.

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This thesis presents the search for the dark sector process h -> Zd Zd -> 4l in events collected by the ATLAS detector at the Large Hadron Collider in 2015--2018. In this theorized process, the Standard Model Higgs boson (h) decays to four leptons via two intermediate Beyond-the-Standard-Model particles each called Zd. This process arises from interactions of the Standard Model with a dark sector. A dark sector consists of one or more new particles that have limited or zero interaction with the Standard Model, such as the new vector boson Zd (dark photon). It could have a rich and interesting phenomenology like the visible sector (the Standard Model) and could naturally address many outstanding problems in particle physics. For example, it could contain a particle candidate for dark matter. In particular, Higgs decays to Beyond-the-Standard-Model particles are well-motivated theoretically and are not tightly constrained; current measurements of Standard Model Higgs properties permit the fraction of such decays to be as high as approximately 30%. The results of this search do not show evidence for the existence of the h -> Zd Zd -> 4l process and are therefore interpreted in terms of upper limits on the branching ratio B(h -> Zd Zd) and the effective Higgs mixing parameter kappa^prime.
Graduate