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Kamagaju, Léocadie. "Problem of skin depigmentation in Rwanda: modulators of tyrosinase extracted from plants used in traditional medicine." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209316.
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La dépigmentation volontaire est une pratique bien connue en Afrique sub-saharienne. Elle se définit comme une pratique par laquelle une personne, de sa propre initiative, tente de diminuer la pigmentation mélanique physiologique de sa propre peau. Les utilisateurs appliquent sur le corps, généralement sans surveillance médicale, de manière soutenue et prolongée, des produits ou des mélanges chimiques composés d’actifs dépigmentants souvent d’une grande nocivité.<p>Cette pratique est documentée dans plusieurs pays d’Afrique sub-saharienne (Sénégal, Mali, Burkina Faso, Togo, Nigéria, ….), et sur d’autres continents. Face à l’absence de données chiffrées pour le Rwanda, nous avons réalisé une étude des pratiques de la dépigmentation volontaire dans la capitale du pays, Kigali. <p>Au Rwanda, certaines plantes étaient utilisées lors des grandes cérémonies comme le mariage, spécialement par les femmes et les jeunes filles, pour éclaircir la peau. Une peau claire semble en fait un critère de beauté dans certaines traditions africaines. Nous avons donc réalisé une enquête ethnobotanique auprès de 61 tradipraticiens rwandais, afin de connaître les plantes qui, avant l’arrivée de la cosmétique moderne, étaient utilisées pour « embellir » (éclaircir) la peau, afin de vérifier si ces plantes pourraient interférer avec la production de la mélanine. <p>Notre enquête nous a permis de documenter 28 espèces, dont cinq [Brillantaisia cicatricosa LINDAU; Chenopodium ugandae (Aellen) Aellen ;Dolichopentas longiflora Oliv. Protea madiensis Oliv. subsp. Madiensis et Sesamum angolense Welw.] se sont distinguées par leur pourcentage de citation par les tradipraticiens. Ces dernières ont fait objet de notre étude de laboratoire. <p>Des extraits de polarité croissante, préparés à partir de ces cinq plantes, ont été testés pour leur modulation de la mélanogénèse et de la tyrosinase (enzyme clé de la mélanogenèse) sur une série de modèles: (i) sur la tyrosinase humaine dans les extraits totaux de mélanocytes normaux; (ii) sur des mélanocytes malins en culture (pour évaluer l’effet global des extraits de plante sur la mélanogenèse); (iii) sur la tyrosinase de champignon en solution et sur chromatoplaque de silice; et enfin (iv) sur l’activité tyrosine hydroxylase de l'enzyme. <p>Deux extraits à l’acétate d’éthyle de Protea madiensis Oliv. et de Sesamum angolense Welw. ont été sélectionnés pour leur activité, respectivement inhibitrice et activatrice de la tyrosinase de champignon. Ces deux extraits ont été soumis à une série de fractionnements dans le but d’isoler et d’identifier des composés actifs. Trois composés ont été isolés de Protea madiensis (2-tridécanone, acide oléique et β-sitostérol). La 2-tridécanone et l’acide oléique ont montré une inhibition de la tyrosinase de champignon sur chromatoplaque et de la tyrosinase humaine dans les extraits cellulaires. De plus, la 2-tridécanone a montré une inhibition de l’activité tyrosine hydroxylase. Le β-sitostérol n’a pas montré d’effet sur nos modèles mais il a déjà été isolé dans d’autres études en tant qu'inhibiteur de la tyrosinase. De l’extrait à l’acétate d’éthyle de Sesamum angolense Welw. nous avons isolé l’acide ursolique qui a montré une augmentation de l’activité de la tyrosinase de champignon sur chromatoplaque.<p>L’enquête ethnobotanique nous a permis de constater que la flore rwandaise regorge de plantes aux vertus cosmétiques intéressantes; celles-ci pourraient représenter une alternative aux actifs dépigmentants connus pour leurs nombreux effets secondaires mais néanmoins largement disponibles sur le marché rwandais. <p>L’enquête réalisée dans la ville de Kigali, nous a permis de constater que 27 % de notre population d’étude sont des utilisateurs conscients de produits dépigmentants. Ce pourcentage nous semble fort élevé et des mesures devraient être prises pour la sensibilisation et la conscientisation de la population quant aux risques encourus et à l’existence de médecines traditionnelles à visée dépigmentante. Ces mesures devraient être combinées avec la recherche de composés naturels dans l'espoir d'identifier des molécules actives et faiblement toxiques, voire atoxiques. <p>L’étude de la modulation de la pigmentation par les extraits des cinq plantes sélectionnées, nous a permis de confirmer l’information reçue des tradipraticiens. Cette étude nous a également montré que ces extraits de plantes renferment des activateurs de la mélanogenèse, qui pourraient être exploités pour le bronzage recherché par les sujets de peau claire.<p>L’isolement et identification de molécules à partir des extraits de deux plantes, nous a permis de constater que notre méthode de bioguidage fonctionne correctement; des mesures de déréplications devraient cependant être prises pour éviter autant que possible de retomber sur des molécules déjà connues./<p><p><p>Voluntary depigmentation, well-known in sub-Saharan Africa, is defined as a practice by which a person, by his/her own initiative, attempts to reduce his/her skin physiological melanin pigmentation. Users apply on the body, usually without medical supervision, in a sustained and prolonged manner, depigmenting compounds, single or in mixtures.<p>This quite harmful practice is documented in several sub-Saharan African countries (Senegal, Mali, Togo, Nigeria…) and in other continents. The absence of Rwandese data prompted us to conduct a study of the practices of voluntary depigmentation in the capital, Kigali.<p>In Rwanda, some plants were used during important ceremonies like wedding (marriage) especially by women and girls to lighten their skin. Fair skin is actually considered as a beauty criterion in some African traditions.<p>We conducted an ethnobotanical survey of 61 Rwandan traditional healers to identify the plants that were used before the introduction of modern cosmetics to "beautify" (lighten) the skin in order to check wether these plants could interfere with the production of melanin.<p>Our survey allowed us to identify and collect 28 species, of which 5 were selected (retained) for their higher percentage of citation by traditional healers [Brillantaisia cicatricosa LINDAU; Chenopodium ugandae (Aellen) Aellen ;Dolichopentas longiflora Oliv. Protea madiensis Oliv. subsp. madiensis and Sesamum angolense Welw.]. These five species have been used for our laboratory study.<p><p>Extracts of increasing polarities were prepared from the five plants and tested for their ability to modulate melanogenesis and tyrosinase (the key enzyme of melanogenesis) in a series of models: (i) human tyrosinase in total extracts from normal melanocytes; (ii) malignant melanocytes in culture (in order to assess the global effect of plant extracts on melanogenesis); (iii) mushroom tyrosinase in solution and on TLC plate; and finally (iv) tyrosine hydroxylase activity of the enzyme.<p>Two ethyl acetate extracts of Protea madiensis Oliv. and of Sesamum angolense Welw have been selected according to their respective inhibitory and activating effect on mushroom tyrosinase. These two extracts were fractionated to isolate and identify active compounds. Three compounds have been isolated from Protea madiensis (2-tridecanone, oleic acid and β-sitosterol). The 2-tridecanone and the oleic acid showed an inhibition of mushroom tyrosinase on TLC and human tyrosinase in cellular extracts. In addition, 2-tridecanone showed an inhibition of the tyrosine hydroxylase activity. β-sitostérol showed no effect on our models but has been identified, in other studies, as a tyrosinase inhibitor. From the ethyl acetate extract of Sesamum angolense, we isolated ursolic acid which increases the mushroom tyrosinase activity on TLC.<p>The ethnobotanical survey allowed us to (state) notice that Rwandan flora contains plants that have interesting cosmetic properties and could be an alternative to the use of harmful depigmenting products which are sold on Rwandese markets.<p>The survey conducted in Kigali city indicates that 27 % of surveyed persons are conscious users of depigmenting products. This percentage seems very high so that measures should be taken to raise awareness about the involved risks and of the existence of traditional medicines with such depigmenting effects. These measures should be accompanied (combined) with the search for natural compounds with depigmenting effect in the hope to identify actives that would be weakly or even non toxic at all.<p>The study of the pigmentation modulation by five selected plant extracts allowed to confirm the information obtained from traditional healers. It also indicates that, apart from an inhibitory effect, some of our plant extracts also contain melanogenesis activators that could be further exploited for tanning, an aspiration of fair-skinned individuals.<p>The isolation and identification of molecules from two plants extracts led us to conclude that our “bioguidance” method performs adequately. Nevertheless, some dereplication measures should be implemented to avoid spending time on isolating already known molecules. <p><p> <p><br>Doctorat en Sciences biomédicales et pharmaceutiques<br>info:eu-repo/semantics/nonPublished
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Faria, Rodrigo Augusto Dias. "Human skin segmentation using correlation rules on dynamic color clustering." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/45/45134/tde-01102018-101814/.
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Human skin is made of a stack of different layers, each of which reflects a portion of impinging light, after absorbing a certain amount of it by the pigments which lie in the layer. The main pigments responsible for skin color origins are melanin and hemoglobin. Skin segmentation plays an important role in a wide range of image processing and computer vision applications. In short, there are three major approaches for skin segmentation: rule-based, machine learning and hybrid. They differ in terms of accuracy and computational efficiency. Generally, machine learning and hybrid approaches outperform the rule-based methods but require a large and representative training dataset and, sometimes, costly classification time as well, which can be a deal breaker for real-time applications. In this work, we propose an improvement, in three distinct versions, of a novel method for rule-based skin segmentation that works in the YCbCr color space. Our motivation is based on the hypotheses that: (1) the original rule can be complemented and, (2) human skin pixels do not appear isolated, i.e. neighborhood operations are taken into consideration. The method is a combination of some correlation rules based on these hypotheses. Such rules evaluate the combinations of chrominance Cb, Cr values to identify the skin pixels depending on the shape and size of dynamically generated skin color clusters. The method is very efficient in terms of computational effort as well as robust in very complex images.<br>A pele humana é constituída de uma série de camadas distintas, cada uma das quais reflete uma porção de luz incidente, depois de absorver uma certa quantidade dela pelos pigmentos que se encontram na camada. Os principais pigmentos responsáveis pela origem da cor da pele são a melanina e a hemoglobina. A segmentação de pele desempenha um papel importante em uma ampla gama de aplicações em processamento de imagens e visão computacional. Em suma, existem três abordagens principais para segmentação de pele: baseadas em regras, aprendizado de máquina e híbridos. Elas diferem em termos de precisão e eficiência computacional. Geralmente, as abordagens com aprendizado de máquina e as híbridas superam os métodos baseados em regras, mas exigem um conjunto de dados de treinamento grande e representativo e, por vezes, também um tempo de classificação custoso, que pode ser um fator decisivo para aplicações em tempo real. Neste trabalho, propomos uma melhoria, em três versões distintas, de um novo método de segmentação de pele baseado em regras que funciona no espaço de cores YCbCr. Nossa motivação baseia-se nas hipóteses de que: (1) a regra original pode ser complementada e, (2) pixels de pele humana não aparecem isolados, ou seja, as operações de vizinhança são levadas em consideração. O método é uma combinação de algumas regras de correlação baseadas nessas hipóteses. Essas regras avaliam as combinações de valores de crominância Cb, Cr para identificar os pixels de pele, dependendo da forma e tamanho dos agrupamentos de cores de pele gerados dinamicamente. O método é muito eficiente em termos de esforço computacional, bem como robusto em imagens muito complexas.
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Iliescu, Florin Mircea. "Unravelling the genetics of human pigmentation in India." Thesis, University of Cambridge, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709532.
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Barros, Renan Sales. "Simulation of human skin pigmentation disorders." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/78876.
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Nosso trabalho apresenta um modelo de simulação de transtornos de pigmentação humana. Nosso modelo é formado por um conjunto de equações diferenciais que definem um sistema reação-difusão. Nosso sistema simula algumas características do sistema pigmentar humano. Alterações nesse sistema podem levar a desequilíbrios na distribuição de melanina na pele resultando em artefatos conhecidos como lesões de pigmentação. Nosso modelo tem como objetivo reproduzir essas alterações e assim sintetizar lesões de pigmentação humanas. Nosso sistema reação-difusão foi elaborado tomando como base dados biológicos a respeito da pele humana, do sistema pigmentar e do ciclo de vida dos melanócitos, que são as principais células envolvidas nesse tipo de transtorno. A simulação desse tipo de transtorno apresenta diversas aplicações em dermatologia como, por exemplo, suporte para o treinamento de dermatologistas e auxílio no diagnóstico de transtornos de pigmentação. No entanto, nosso trabalho se concentra em aplicações relacionadas com computação gráfica. Assim, nós também apresentamos um método para transferir os resultados do nosso modelo de simulação para texturas e imagens de pele humana. Nesse contexto, o nosso modelo contribui para a geração de texturas de pele mais realistas e consequentemente para a geração de modelos de serem humanos mais realistas. Além disso, nós também comparamos os resultados da nossa simulação com lesões de pigmentações reais objetivando avaliar a qualidade das lesões geradas pelo nosso modelo. Para realizar essa comparação nós extraímos métricas das lesões sintetizadas e das lesões reais e comparamos os valores dessas métricas. Com base nessa comparação, nós observamos que as lesões sintetizadas apresentam as mesmas características das lesões reais. Ainda, para efeito de comparações visuais, nós também apresentamos imagens de lesões reais lado a lado com imagens sintetizadas e podemos observar que o método utilizado para produzir imagens de lesões a partir do resultado do nosso modelo de simulação produz resultados que são indistinguíveis das imagens reais.<br>Our work presents a simulation model of human pigmentation disorders. Our model is formed by a set of differential equations that defines a reaction-diffusion system. Our system simulates some features of the human pigmentary system. Changes in this system can lead to imbalances in the distribution of melanin in the skin resulting in artifacts known as pigmented lesions. Our model aims to reproduce these changes and consequently synthesize human pigmented lesions. Our reaction-diffusion system was developed based on biological data regarding human skin, pigmentary system and melanocytes life cycle. The melanocytes are the main cells involved in this type of human skin disorders. The simulation of such disorders has many applications in dermatology, for example, to assist dermatologists in diagnosis and training related to pigmentation disorders. However, our study focuses on applications related to computer graphics. Thus, we also present a method to transfer the results of our simulation model for textures and images of human skin. In this context, our model contributes to the generation of more realistic skin textures and consequently for the generation of more realistic human models. Moreover, we also compared the results of our simulation with real pigmented lesions to evaluate the quality of the lesions generated by our model. To perform this comparison we measured some features of real and synthesized pigmented lesions and we compared the results of these measurements. Based on this comparison, we observed that synthesized lesions exhibit the same characteristics of real lesions. Still, for the purpose of visual comparisons, we also present images of real lesions along with images of synthesized lesions. In this visual comparison, we can note that the method used to produce lesions images from the results of our simulation generates images that are indistinguishable from real images.
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Stephen, Ian D. "Skin colour, pigmentation and the perceived health of human faces." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/753.
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PORTER, CORNELIA PAULINE. "SOCIALIZATION, BLACK SCHOOL-AGE CHILDREN AND THE COLOR CASTE HIERARCHY (SOCIAL COGNITION, PSYCHOLOGY, NURSING)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188010.
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The purpose of the descriptive research was to investigate the relationship between an adherence to the Black community's belief and value system about Black skin tones and Black school-age children's skin tone preferences and perceptions of occupational life opportunities. Six Black skin tones were scaled via Thurstone's method of paired comparisons and the law of comparative judgment. The result was an interval level Skin Tone Scale on which the skin tones were positioned from most to least preferred by the children. The most preferred skin tones ranged from medium to honey brown. The least preferred were the extreme tones of very light yellow and very dark brown. Data collection was accomplished with the Porter Skin Tone Connotation Scale (PSTCS). The instrument was constructed from the forced choice preference paradigm. Data were obtained from a volunteer sample of 98 Black school-age children who resided in a city in Arizona. Data collection and analyses were constructed to test two hypotheses: (1) Black school-age children's skin tone classifications for differential status occupations will be related to gender, age, and perception of own skin tone as indexed by the skin tone values of the Skin Tone Scale, and (2) with increasing age, Black school-age children's skin tone preferences will be more systematically related to the skin tone values of the Skin Tone Scale. Testing of the first hypothesis with multiple regression indicated that the independent variables did not account for enough variance to support the hypothesis. Analysis of the second hypothesis with coefficient gamma suggested a trend toward more systematic agreement with the Skin Tone Scale with increasing age. Results of the first hypothesis were discussed in relation to composition of the sample, gender differences, the achievement value of the Black sociocultural system, and these Black children's lived experience. Results of the second hypothesis reflected those from similar investigations conducted in the 1940s. The results suggested Black children still most prefer brown skin tones and least prefer extreme light and dark skin tones. Black children's preferences for Black skin tones have not altered in approximately forty years.
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Natividad, Beverly Romero. "Rendering whiteness visible in the Filipino culture through skin-whitening cosmetic advertisements." CSUSB ScholarWorks, 2006. https://scholarworks.lib.csusb.edu/etd-project/2974.
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Gosin, Monika. "(Re) framing the nation the Afro-Cuban challenge to Black and Latino struggles for American identity /." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3355784.
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Thesis (Ph. D.)--University of California, San Diego, 2009.<br>Title from first page of PDF file (viewed June 25, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 296-311).
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Clemens, Alexander. "Investigating the Inclusivity of Face Detection." Scholarship @ Claremont, 2018. http://scholarship.claremont.edu/cmc_theses/1836.
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Face detection refers to a number of techniques that identify faces in images and videos. As part of the senior project exercise at Pomona College, I explore the process of face detection using a JavaScript library called CLMtrackr. CLMtrackr works in any browser and detects faces within the video stream captured by a webcam. The focus of this paper is to explore the shortcomings in the inclusivity of the CLMtrackr library and consequently that of face detection. In my research, I have used two datasets that contain human faces with diverse backgrounds, in order to assess the accuracy of CLMtrackr. The two datasets are the MUCT and PPB. In addition, I investigate whether skin color is a key factor in determining face detection's success, to ascertain where and why a face might not be recognized within an image. While my research and work produced some inconclusive results due to a small sample size and a couple outliers in my outputs, it is clear that there is a trends toward the CLMtrackr algorithm recognizing faces with lighter skin tones more often than darker ones.
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O'Mara, David Thomas John. "Automated facial metrology." University of Western Australia. School of Computer Science and Software Engineering, 2002. http://theses.library.uwa.edu.au/adt-WU2003.0015.
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Automated facial metrology is the science of objective and automatic measurement of the human face. There are many reasons for measuring the human face. Psychologists are interested in determining how humans perceive beauty, and how this is related to facial symmetry [158]. Biologists are interested in the relationship between symmetry and biological fitness [124]. Anthropologists, surgeons, forensic experts, and security professionals can also benefit from automated facial metrology [32, 101, 114]. This thesis investigates the concept of automated facial metrology, presenting original techniques for segmenting 3D range and colour images of the human head, measuring the bilateral symmetry of n-dimensional point data (with particular emphasis on measuring the human head), and extracting the 2D profile of the face from 3D data representing the head. Two facial profile analysis techniques are also presented that are incremental improvements over existing techniques. Extensive literature reviews of skin colour modelling, symmetry detection, symmetry measurement, and facial profile analysis are also included in this thesis. It was discovered during this research that bilateral symmetry detection using principal axes is not appropriate for detecting the mid-line of the human face. An original mid-line detection technique that does not use symmetry, and is superior to the symmetry-based technique, was developed as a direct result of this discovery. There is disagreement among researchers about the effect of ethnicity on skin colour. Some researchers claim that people from different ethnic groups have the same skin chromaticity (hue, saturation) [87, 129, 206], while other researchers claim that different ethnic groups have different skin colours [208, 209]. It is shown in this thesis that people from apparently different ethnic groups can have skin chromaticity that is within the same Gaussian distribution. The chromaticity-based skin colour model used in this thesis has been chosen from the many models previously used by other researchers, and its applicability to skin colour modelling has been justified. It is proven in this thesis that the Mahalanobis distance to the skin colour distribution is Gaussian in both the chromatic and normalised rg colour spaces. Most facial profile analysis techniques use either tangency or curvature to locate anthropometric features along the profile. Techniques based on both approaches have been implemented and compared. Neither approach is clearly superior to the other, but the results indicate that a hybrid technique, combining both approaches, could provide significant improvements. The areas of research most relevant to facial metrology are reviewed in this thesis and original contributions are made to the body of knowledge in each area. The techniques, results, literature reviews, and suggestions presented in this thesis provide a solid foundation for further research and hopefully bring the goal of automated facial metrology a little closer to being achieved.
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Judilla, Judy Fondales. "Introduction to cosmetology: Color seasons and palettes." CSUSB ScholarWorks, 2000. https://scholarworks.lib.csusb.edu/etd-project/1757.
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Whitehead, Ross David. "Dietary effects on skin colour : appearance-based incentives to improve fruit and vegetable consumption." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3371.
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Poor diet precipitates significant social and economic burden, necessitating effective and economical dietary intervention strategies. Current population-level campaigns provide guidelines for living healthily and focus on the impact of lifestyle on chronic disease risk. Behavioural interventions which capitalise on individuals' existing cognitions are likely to be more effective. A programme of work is presented here which evaluates the feasibility and efficacy of an appearance-based dietary intervention approach. This project aims to improve fruit and vegetable consumption by illustrating the associated benefits to skin appearance. The impact of fruit and vegetable consumption on skin colour is assessed (Chapter 6), corroborating previous between-subjects evidence which finds that dermal yellowness (CIE b*) is positively associated with fruit and vegetable intake. This work also discovers that modest within-subject dietary change is sufficient to perceptibly alter skin colour within six weeks (Chapter 7). Perceptual preferences are examined (Chapters 5 to 9), finding that optimally healthy skin colouration is that associated with increased fruit and vegetable consumption. Two behavioural intervention trials are conducted (Chapters 6 and 9) to evaluate whether visualising the impact of fruit and vegetable consumption on skin colour motivates dietary improvement. Relative to control groups, participants receiving an appearance-based intervention (in which the above effects are illustrated and explained) reported improvements in diet, particularly when illustrations were performed upon images of one's own face. It may be valuable to disseminate such an intervention at a population level, though a number of further longitudinal studies are necessary to determine the wider effectiveness of this approach.
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REEDY, CRYSTAL A. "Kids! On Race: How teaching the evolutionary story of human skin color can challenge children to question arbitrary categories of race and the myth of white supremacy in grade school." Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent155592254864772.
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Junior, Osvaldo Severino. "Mistura de cores: uma nova abordagem para processamento de cores e sua aplicação na segmentação de imagens." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/18/18152/tde-02072009-141121/.
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Inspirado nas técnicas utilizadas por pintores que sobrepõem camadas de tintas de diversos matizes na geração de uma tela artística e também observando-se a distribuição da quantidade dos cones na retina do olho humano na interpretação destas cores, este trabalho propõe uma técnica de processamento de imagens baseada na mistura de cores. Trata-se de um método de quantização de cores estático que expressa a proporção das cores preto, azul, verde, ciano, vermelho, magenta, amarelo e branco obtida pela representação binária da cor que compõe os pixels de uma imagem RGB com 8 bits por canal. O histograma da mistura é denominado de misturograma e gera planos que interceptam o espaço RGB, definindo o espaço de cor HSM (Hue, Saturation and Mixture). A posição destes planos dentro do cubo RGB é modelada por meio da distribuição dos cones sensíveis aos comprimentos de onda curta (Short), média (Middle) e longa (Long) consideradas para a retina humana. Para demonstrar a aplicabilidade do espaço de cor HSM, é proposta, neste trabalho, a segmentação dos pixels de uma imagem digital em pele humana ou não pele com o uso dessa nova abordagem. Para análise de desempenho da mistura de cores foi implementado um método tradicional no espaço de cor RGB e também usando uma distribuição Gaussiana nos espaços de cores HSV e HSM. Os resultados obtidos demonstram o potencial da técnica que emprega a mistura de cores para a segmentação de imagens digitais coloridas. Verificou-se também que, baseando-se apenas na camada mais significativa da mistura de cores, gera-se a imagem esboço de uma imagem facial denominada esboço da face. Os resultados obtidos comprovam o bom desempenho do esboço da face em aplicações CBIR.<br>Inspired on the techniques used by painters to overlap layers of various hues of paint to create oil paintings, and also on observations of the distribution of cones in human retina for the interpretation of these colors, this thesis proposes an image processing technique based on color mixing. This is a static color quantization method that expresses the mixture of black, blue, green, cyan, red, magenta, yellow and white colors quantified by the binary weight of the color that makes up the pixels of an RGB image with 8 bits per channel. The mixture histogram, called a mixturegram, generates planes that intersect the RGB color space, defining the HSM (Hue, Saturation and Mixture) color space. The position of these planes inside the RGB cube is modeled by the distribution of cones sensitive to the short (S), middle (M) and long (L) wave lengths of the human retina. To demonstrate the applicability of the HSM color space, this thesis proposes the segmentation of the pixels of a digital image of human skin or non-skin using this new approach. The performance of the color mixture is analyzed by implementing a traditional method in the RGB color space and by a Gaussian distribution in the HSV and HSM color spaces. The results demonstrate the potential of the proposed technique for color image segmentation. It was also noted that, based only on the most significant layer of the colors mixture, it is possible generates the face sketch image. The results show the performance of the face sketch image in CBIR applications.
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Bernard, Arnaud Jean Marc. "Human computer interface based on hand gesture recognition." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42748.
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With the improvement of multimedia technologies such as broadband-enabled HDTV, video on demand and internet TV, the computer and the TV are merging to become a single device. Moreover the previously cited technologies as well as DVD or Blu-ray can provide menu navigation and interactive content.
The growing interest in video conferencing led to the integration of the webcam in different devices such as laptop, cell phones and even the TV set. Our approach is to directly use an embedded webcam to remotely control a TV set using hand gestures. Using specific gestures, a user is able to control the TV. A dedicated interface can then be used to select a TV channel, adjust volume or browse videos from an online streaming server.
This approach leads to several challenges. The first is the use of a simple webcam which leads to a vision based system. From the single webcam, we need to recognize the hand and identify its gesture or trajectory. A TV set is usually installed in a living room which implies constraints such as a potentially moving background and luminance change. These issues will be further discussed as well as the methods developed to resolve them. Video browsing is one example of the use of gesture recognition. To illustrate another application, we developed a simple game controlled by hand gestures.
The emergence of 3D TVs is allowing the development of 3D video conferencing. Therefore we also consider the use of a stereo camera to recognize hand gesture.
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Gingir, Emrah. "Hand Gesture Recognition System." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612532/index.pdf.
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This thesis study presents a hand gesture recognition system, which replaces input devices like keyboard and mouse with static and dynamic hand gestures, for interactive computer applications. Despite the increase in the attention of such systems there are still certain limitations in literature. Most applications require different constraints like having distinct lightning conditions, usage of a specific camera, making the user wear a multi-colored glove or need lots of training data. The system mentioned in this study disables all these restrictions and provides an adaptive, effort free environment to the user. Study starts with an analysis of the different color space performances over skin color extraction. This analysis is independent of the working system and just performed to attain valuable information about the color spaces. Working system is based on two steps, namely hand detection and hand gesture recognition. In the hand detection process, normalized RGB color space skin locus is used to threshold the coarse skin pixels in the image. Then an adaptive skin locus, whose varying boundaries are estimated from coarse skin region pixels, segments the distinct skin color in the image for the current conditions. Since face has a distinct shape, face is detected among the connected group of skin pixels by using the shape analysis. Non-face connected group of skin pixels are determined as hands. Gesture of the hand is recognized by improved centroidal profile method, which is applied around the detected hand. A 3D flight war game, a boxing game and a media player, which are controlled remotely by just using static and dynamic hand gestures, were developed as human machine interface applications by using the theoretical background of this study. In the experiments, recorded videos were used to measure the performance of the system and a correct recognition rate of ~90% was acquired with nearly real time computation.
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Feitosa, Rafael Divino Ferreira. "Modelos matemáticos para redução do espectro provável e detecção de tons de pele humana em imagens coloridas representadas nos espaços de cores RGB e HSV." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/4756.
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Previous issue date: 2015-04-14<br>Skin detection techniques are widely applied to locate and to track parts of the human
body with the objective of posterior recognition, having received great attention in recent
years in the development of research in reason to the innumerable possible applications
with the detection and tracking of faces, identification of naked people, identification
of hand movements, among others. The present work proposed the construction of
mathematical models for the detection of human skin tones such as, white, yellow, brown
and black in digital color images in the RGB and HSV color spaces. Using a set of
human skin tone samples, mathematical models were constructed describing how the
variables of each color pixel in the RGB and HSV systems interrelate. To understand
the answer of the proposed system, the mechanistic model was chosen, dividing it into
components, observing the behavior of each part and the interactions that occurred
between them. The proposed RGB filter reached a 98.3657% reduction index of the
spectrum, classifying only 1.6343% (253,159 tones) as possible skin tones and the HSV
model reduced the likely spectrum to 2.5352% (94,030 tones), discarding 97.4648% of
the colors as candidates for human skin tones. When the proposed filters, were applied
to the reduction of the probable range of human skin tones, well-defined bands in the
geometric representation of the color spaces were selected. The experimental validation
of the effectiveness of the RGB model showed that the proposed filter has conservative
characteristics in the detection of skin, mistakenly classifying as skin only 6.7163% of
the sample space. The proposed RGB filter has low sensitivity of 61.0831% and high
specificity of 95.2769% in the detection of human skin in digital images. The HSV model
had rates of (54,6333%) low sensitivity and (92,6390%) high specificity, considered low
when compared to the performance of the other algorithms.<br>Técnicas de detecção de pele são amplamente aplicadas para localizar e rastrear partes
do corpo humano com o objetivo de posterior reconhecimento, tendo recebido nos
últimos anos grande atenção no desenvolvimento de pesquisas em razão das inúmeras
aplicações possíveis como detecção e rastreamento de faces, identificação de pessoas
nuas, identificação de movimentos das mãos, entre outras. O presente trabalho propôs
construir 2 modelos matemáticos para detecção de tons de pele humana branca, amarela,
parda e preta em imagens digitais coloridas nos espaços de cores RGB e HSV. Utilizandose
de um conjunto de amostras de tons de pele humana foram construídos modelos
matemáticos que descrevem como as variáveis de cada pixel de cor nos sistemas RGB
e HSV se relacionam. Para compreender a resposta do sistema proposto, foi escolhido
o modelo mecanístico, dividindo-o em componentes e observando o comportamento de
cada parte e das interações que ocorreram entre elas. O filtro RGB proposto alcançou
o índice de redução de 98,3657% do espectro, classificando apenas 1,6343% (253.159
tons) como possíveis tons de pele e o modelo HSV reduziu para 2,5352% (94.030 tons)
o espectro provável, descartando 97,4648% das cores como candidatas a tons de pele
humana. Os filtros propostos, quando aplicados à redução do espectro provável de tons de
pele humana, selecionaram faixas bem definidas na representação geométrica dos espaços
de cores. A validação experimental da eficácia do modelo RGB mostrou que o filtro
proposto apresenta características conservadoras na detecção de pele classificando como
pele, erroneamente, apenas 4,5075% do espaço amostral. O filtro RGB proposto possui
baixa sensibilidade de 56,9698% e elevada especificidade de 95,4925% na detecção de
pele humana em imagens digitais. O modelo HSV apresentou taxas de baixa sensibilidade
(54,6333%) e alta especificidade (92,6390%), quando comparadas ao desempenho dos
demais algoritmos propostos na literatura.
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Oliveira, Paulo Edison de. "O sistema de classificação de cor e raça do estado brasileiro na formação da identidade afro-brasileira." Pontifícia Universidade Católica de São Paulo, 2017. https://tede2.pucsp.br/handle/handle/20737.
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Previous issue date: 2017-12-13<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>The system of classification of color and race of the brazilian state in the training of afro-brazilian identity is a research that problematizes how the Brazilian state fomented racism in the course of its history and, in a very historical moment prevented, in others it discouraged and today it makes difficult that Afro-Brazilians relied on their ancestry.
The research is divided into 5 chapters: i) The African Diaspora: From Humanity to Dehumanization, reflection on the dehumanization process that these African People suffered and suffer, particularly by Institutions; ii) Racism in Contemporary Brazil, a report of a surprising data that remains in the 21st century remains to prevent the humanization of the human being; iii) Afro-Brazilian Identity: an identity among diverse identities, the complex discussion of identity in the contemporary and the search of Afro-Brazilians for a reencounter with its origin. iv) The Brazilian State Census in the historical context: the system of classification of color and race, a historical analysis on the color and race requirements in official documents of the Brazilian state that defines how society should classify its citizens. The final considerations that present us with questions still to be solved by the Brazilian society<br>O sistema de classificação de cor e raça do estado brasileiro na formação da identidade afro-brasileira é uma pesquisa que problematiza como o estado brasileiro fomentou o racismo no decorrer da sua história e, em muitos momentos históricos, impediu ou desencorajou e ainda dificulta que os afro-brasileiros se religuem com sua ancestralidade.
A pesquisa está dividida em quatro capítulos. No capítulo 1, A diáspora africana: da humanidade a desumanização, há uma reflexão sobre o processo de desumanização que esses povos africanos sofreram e sofrem, sobretudo pelas instituições. No capítulo 2, O Racismo no Brasil Contemporâneo, constam relatos de dados surpreendentes que, em pleno século XXI, permanecem impedindo a humanização do ser humano. O capítulo 3, Identidade afro-brasileira: uma identidade dentre as diversas identidades, apresenta a complexa discussão de identidade no contemporâneo e a busca dos afro-brasileiros por um reencontro com sua origem. No capítulo 4, Os Censos do Estado brasileiro no contexto histórico: o sistema de classificação de cor e raça, há uma análise histórica sobre os quesitos de cor e raça nos documentos oficiais do estado brasileiro que define como a sociedade deve classificar os seus cidadãos. E, por fim, as considerações finais que nos apresenta questões ainda a serem resolvidas pela sociedade brasileira
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El, Hajj Petra. "New prognosis markers and new targets for therapy in high risk melanoma: evaluation of TYRP1 as a melanoma prognostic marker and its regulation by miRNA(s)." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209064.
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L’espérance de vie des patients atteints de mélanome à haut risque ne peut être prédite d’une façon<p>fiable en se basant sur les analyses d’histopathologies de la lésion primitive et est souvent ajustée<p>durant la progression de la maladie. Notre étude vise à élargir nos observations initiales au niveau<p>des métastases cutanées et d’évaluer la valeur pronostique de tyrosinase related protein 1 (TYRP1)<p>dans les métastases ganglionnaires des patients atteints de mélanome de stades III et IV. TYRP1 est<p>une enzyme mélanosomale qui partage des similitudes structurelles avec la tyrosinase, l'enzyme clé<p>de la mélanogenèse.<p>L’expression de l'ARNm de TYRP1 a été quantifiée dans 104 métastases ganglionnaires par PCR<p>en temps réel et normalisée par rapport à l’expression de l’ARNm de S100B (marqueur reconnu du<p>mélanome) pour corriger l’expression de TYRP1 suivant la charge tumorale de l’échantillon. Le<p>rapport TYRP1/S100B a été calculé et la médiane a été utilisée en tant que valeur seuil. Ensuite<p>nous avons étudié la relation entre les valeurs de TYRP1/S100B, le suivi clinique et les<p>caractéristiques histopathologiques de la tumeur primitive.<p>Un rapport élevé de l’ARNm TYRP1/S100B corrélait significativement avec une survie sans<p>récidive et une survie globale plus courtes, avec une épaisseur de Breslow plus élevée et avec la<p>présence d'une ulcération au niveau de la tumeur primitive. En outre, une expression élevée de<p>TYRP1/S100B était de meilleure valeur pronostique pour la survie globale que l'épaisseur de<p>Breslow et l'ulcération des primitifs. De plus, cette expression est bien conservée au cours de la<p>progression de la maladie par rapport aux groupes de TYRP1 bas/élevé.<p>Nous avons constaté qu’une expression élevée de TYRP1/S100B dans les métastases de patients<p>atteints de mélanome est associée à un résultat clinique défavorable et une survie courte. Menée sur<p>des patients atteints d'un mélanome à haut risque de récidive, cette première étude a suggéré que<p>l'ARNm de TYRP1 dans les métastases pourrait servir de biomarqueur pour affiner le pronostic<p>initial des patients surtout ceux ayant des lésions primitives de localisation inconnues ou non<p>évaluables et peut permettre une gestion différente des deux groupes de patients. Son expression<p>conservée au cours de la progression de la maladie est en faveur de son utilisation comme cible<p>thérapeutique.<p>En second lieu, en évaluant l’expression de la protéine TYRP1 par immunohistochimie dans les<p>métastases cutanées et ganglionnaires, nous avons observé qu’elle n'était pas détectée dans la moitié <p>7<p>des tissus exprimant bel et bien l'ARNm correspondant et qu’elle, contrairement à l'ARNm, n’était<p>pas associée à la survie.<p>Des données récentes ont indiqué que le 3'-UTR de l’ARNm de TYRP1 contient trois sites de<p>liaison putatifs de miR-155 dont deux présentant un polymorphisme d'un seul nucléotide (SNPs:<p>rs683 et rs910) qui favorisent la dégradation en cas d’hybridation miARN-ARNm parfaite de<p>l’ARNm ou non en cas d’hybridation imparfaite. Nous avons cherché à examiner si miR-155 peut<p>affecter l’expression de l’ARNm et de la protéine TYRP1 en fonction de ces SNPs. Tout d'abord,<p>nous avons transfecté deux lignées de mélanome ayant chacune l’une ou l’autre de l’allèle (au<p>niveau rs683 et rs910) avec différentes concentrations de pré-miR-155 et nous avons évalué<p>l’expression du miR-155 et l’ARNm TYRP1 par PCR en temps réel ainsi que l’expression de la<p>protéine TYRP1 par western blot. Nous avons constaté qu’une surexpression de miR-155 a induit<p>une dégradation importante des ARNm TYRP1 et a perturbé sa traduction en protéine dans la lignée<p>avec le génotype “hybridation parfaite”. Ensuite, nous avons examiné l'expression des ARNm et<p>protéines de TYRP1, le niveau de miR-155 et les SNPs rs683 et rs910 dans 192 échantillons de<p>métastases cutanées et ganglionnaires de mélanome. Nous avons trouvé que le groupe d'échantillons<p>avec le génotype “hybridation parfaite” était significativement associé à un niveau de protéine de<p>TYRP1 plus bas alors qu'aucune différence de niveau d’expression n'a été trouvée pour l’ARNm de<p>TYRP1 ou miR-155 entre les deux groupes de génotype, confirmant que les SNPs au niveau de 3’-<p>UTR de TYRP1 peuvent spécifiquement affecter l'expression de la protéine TYRP1. En outre, nous<p>avons montré que l’ARNm de TYRP1 est inversement corrélé avec l’expression miR-155, mais pas<p>avec la protéine TYRP1 dans le groupe " hybridation parfaite", alors qu'il corrèle positivement avec<p>la protéine mais pas avec miR-155 dans le groupe "hybridation imparfaite" où la protéine corrélait<p>inversement à la survie. Cela montre que les SNPs dans le 3'-UTR de l'ARNm TYRP1 affectent la<p>régulation de l’ARNm par miR-155 et la traduction en protéine. Ces SNPs rendent la régulation de<p>l’ARNm et la protéine de TYRP1 indépendante de miR-155 et confèrent une valeur pronostique à<p>la protéine TYRP1<br>Doctorat en Sciences biomédicales et pharmaceutiques<br>info:eu-repo/semantics/nonPublished
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Breugnot, Josselin. "Modélisation surfacique et volumique de la peau : classification et analyse couleur." Phd thesis, Université Jean Monnet - Saint-Etienne, 2011. http://tel.archives-ouvertes.fr/tel-00693348.
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Grâce aux innovations technologiques récentes, l'exploration cutanée est devenue de plus en plus facile et précise. Le relevé topographique de la surface de peau par projection de franges ainsi que l'exploration des structures intradermiques par microscopie confocale in-vivo en sont des exemples parfaits. La mise en place de ces techniques et les développements sont présentés dans cette thèse. L'apport de l'imagerie est évident tant pour le traitement des acquisitions de ces appareils que pour l'évaluation de paramètres cutanés à partir de photographie par exemple. L'extension du modèle LIP niveaux de gris à la couleur a été réalisée pour apporter une évaluation proche de celle d'un expert grâce aux fondements logarithmiques du modèle, proches de la vision humaine. Enfin, la classification de données dans une image, sujet omniprésent dans le traitement d'images, a été abordée par les classifications hiérarchiques ascendantes, utilisant un cadre mathématique rigoureux grâce aux métriques ultramétriques.
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Ribeiro, Hebert Luchetti. "Reconhecimento de gestos usando segmentação de imagens dinâmicas de mãos baseada no modelo de mistura de gaussianas e cor de pele." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-27112006-132158/.
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O objetivo deste trabalho é criar uma metodologia capaz de reconhecer gestos de mãos, a partir de imagens dinâmicas, para interagir com sistemas. Após a captação da imagem, a segmentação ocorre nos pixels pertencentes às mãos que são separados do fundo pela segmentação pela subtração do fundo e filtragem de cor de pele. O algoritmo de reconhecimento é baseado somente em contornos, possibilitando velocidade para se trabalhar em tempo real. A maior área da imagem segmentada é considerada como região da mão. As regiões detectadas são analisadas para determinar a posição e a orientação da mão. A posição e outros atributos das mãos são rastreados quadro a quadro para distinguir um movimento da mão em relação ao fundo e de outros objetos em movimento, e para extrair a informação do movimento para o reconhecimento de gestos. Baseado na posição coletada, movimento e indícios de postura são calculados para reconhecimento um gesto significativo.<br>The purpose of this paper is to develop a methodology able to recognize hand gestures from dynamic images to interact with systems. After the image capture segmentation takes place where pixels belonging to the hands are separated from the background based on skin-color segmentation and background extraction. The image preprocessing can be applied before the edge detection. The recognition algorithm uses edges only; therefore it is quick enough for real time. The largest blob from the segmented image will be considered as the hand region. The detected regions are analyzed to determine position and orientation of the hand for each frame. The position and other attributes of the hands are tracked per frame to distinguish a movement from the hand in relation to the background and from other objects in movement, and to extract the information of the movement for the recognition of dynamic gestures. Based in the collected position, movement and indications of position are calculated to recognize a significant gesture.
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Canotal, Eugene Espejo. "An overseas example of "lighter is better" the implications of colorism among male sex workers in Thailand : a project based upon an independent investigation /." 2009. http://hdl.handle.net/10090/9847.
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Lee, Chia-Wei, and 李家崴. "Using Artificial Neural Network to Detect Human Skin in Color Spaces." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/60963213472426101317.
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碩士<br>中國文化大學<br>數位機電科技研究所<br>97<br>In this article, it makes the analysis discussion of the human skin detection. It detects the main characteristics of skin between non-skin both using RGB colors and chromatic components (Cb&Cr) ratios. By selecting an identification criterion, it can distinguish the skin pixels and non-skin pixels in a color image. At the beginning, the detection process will require a training image and it manually differentiates this image into two parts: skin and non-skin pixels. This discrimination process is called as global knowledge which is a foundation for our detecting processing. After that different color ratios of these separated skin and non-skin pixels are calculated and their relationships between two parts are analyzed. The analyzed results will be used for separating our target objects from a given image. The first method is to use a statistical histogram method to detect skin part in a color image. The histograms of different color ratios are derived from the new given images. By selecting proper thresholds, one can make a best decision to determine whether one pixel is skin or not. The second method is using Backpropagation Neural Network (BPNN) to detect skin pixels. A network is trained by using color ratios obtained above. Then the trained neural network is used to detect a new image and directly classifies the skin and non-skin parts from the given data. Finally the experimental results of two methods are shown and a comparison of two methods has been discussed. Follow-up have joined to deal with some simple division. Experimental results show both proposed methods of this paper can effectively identify most of the skin pixels from a color image and there is also a fairly good accuracy in the recognition process.
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Li, I.-Pin, and 李怡頻. "The Effects of High Brightness LED Phototherapy on Human Skin Color and Fineness." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/34779405102255245480.
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碩士<br>台南應用科技大學<br>生活應用科學研究所<br>100<br>The effects of phototherapy on skin color and fineness were studies and compared to evaluate the difference using red, green, blue, and yellow LED lights.
3W LED light sources were used with red in 629.6nm (Full Width Half Maximum 14.0nm), green in 526.9nm ( 36.3nm), blue in 460.6nm ( 20.3nm), and yellow in 590.9nm ( 13.1nm) and a three-week continuous exposure on the right hand of the patients was conducted while the right hand was used as a comparison. Questionnaires of 5 grade assessment were used to evaluate the psychological felling of the skin quality improvement by the patient himself or by objective observers. The results show
1. the skin color is whiter and finer week by week using red light phototherapy compared with other three different LED lights.
2. the yellow light phototherapy can also improve the skin quality as the red light therapy but the effect is significant only in the early first and second weeks.
3. the green light phototherapy can improve the skin fineness in the first two weeks, but not significant in improving the skin color.
4. the blue light phototherapy can also improve the skin fineness, but the effect is significant after two-week irradiation. The improvement in skin color is also not as significant.
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Wu, Tsai-Fong, and 吳彩鳳. "Moving Object Extraction in DCT compressed Videoand Skin Color Classification of Human Races." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/43712278373515037287.
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碩士<br>國立臺灣大學<br>電信工程學研究所<br>94<br>Research of image segmentation has been studied for many years. Image segmentation techniques are important but difficult in many image processing topics, such as object recognition and content-based image retrieval. In order to solve those problems, a successful image segmentation method is essential for splitting an image into meaningful regions, such as the discrimination between foreground and background of the segmentation of moving object and constant background. Then, make again these fundamental units (such as pixels or blocks) into further significant processing.
In Part A, the task of Segmentation in video sequence based on DCT domain is dividing the video sequence into frames, and dividing 8X8 pixels element block each frame. Then passes through a continually string to calculate after determining this block is belongs to the foreground or the background. The main framework is to transfer each 8X8 block into 2 dimension-DCT domain in order to get the information of frequency domain, and then utilize the relation in the identical position block to calculate the threshold of background and foreground. This method has the quite good performance of catching moving object and also show to be low sensitive to illumination change and to noise.
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With the growing technique of communication between human and robot, the problem of human face recognition has attached more importance and become the current research in the popular domain of computer vision and recognition model. Thus, human’s skin color is always an important mechanism and principle basis of human face detection. Human’s skin color has the relative stability with the difference of the majority background object appearance. The skin color does not rely on the face detail characteristic and do not change with the face expression and rotation. Therefore, utilizing skin color to examine human face in color image is an important context of human face recognition.
In Part B, we provide a fast algorithm to identify human race with face skin color. The basic construction is roughly dividing human race into three parts: white, yellow and black race, then using Gaussian Mixture Model to train the feature parameter of each human race with large number of training images. Afterward, utilize Bayesian Decision Rule to determine the human race of test images.
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Tsai-Fong, Wu. "Moving Object Extraction in DCT compressed Video and Skin Color Classification of Human Races." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-1707200615541000.
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Daniels, Claretta D. "Echoes of racism an exploration into skin color bias within the African American community : a project based upon an independent investigation /." 2009. http://hdl.handle.net/10090/9845.
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Komane, Baatile Mmammoti. "Traditional use of Trichilia emetica for treatment of post-inflammatory hyperpigmentation." Thesis, 2010. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000634.
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Thesis (MTech. degree in Pharmaceutical Sciences)--Tshwane University of Technology, 2010.<br>Aims to assess the efficacy and adverse effects of Trichilia emetica in reducing post-inflammatory hyperpigmentation on black skin.
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"Biochemical evaluation of the hypopigmentary effects of selected Chinese medicines and the constituent compounds." 2012. http://library.cuhk.edu.hk/record=b5549421.
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黑色素生成是為了保護皮膚細胞免受紫外光傷害的一個生化過程。在這過程中，黑色素在人類表皮底層的黑色素細胞的黑色素體內產生。該過程可以被基因，荷爾蒙或環境因素所影響。黑色素的製造量是依賴速度限制酶酪氨酸酶的活性，黑色素體的數量和大小，黑色素體通過黑色素細胞的偽足傳送致角質細胞的速度及黑色素體在角質細胞內的分佈。這些細胞過程會受皮膚顏色或紫外光曝光量的變化而影響。當黑色素的產生超過黑色素的降解，黑色素沉著毛病便出現。根據不同的皮膚類型，年齡組別及累積紫外光曝光程度而引發雀斑或黃褐斑的形成。很多治療方法市面上能夠提供，它們包括人工合成化粧品，激光，整容手術等。這些治療方法通常會產生副作用及蘊藏高風險。因此從天然物質裏尋找治療藥物便成了美容學的一個新的研究方向。在這研究裏，十種草本植物就從自古以來用作治療黑色素沉著毛病的傅統中藥中被挑選出來。那些草本植物被四種擁有不同極性的溶劑提取。小鼠黑色素細胞被用以篩選提取物的降黑色素能力。結果發現當歸的正己烷及二氯甲烷的提取物有正面效用。當歸的化學成份4-乙基間苯二酚、4-乙基苯酚及1-十四烷醇也能降低小鼠黑色素細胞的黑色素量。數種生化技術繼而被應用作研究有效化學物的藥理。他們包括西方墨點法、環磷酸腺苷測試、蛋白激酶A活性測試及酪氨酸酶活性測試。<br>Melanogenesis is a biochemical process designated for protecting skin cells from ultraviolet (UV)-induced damage. During the process, melanin is produced in the melanosomes of the melanocytes located at the basal epidermis of human. The process could be affected by genetic, hormonal or environmental factors. Amount of melanin synthesized depending on the activity of the rate-limiting enzyme tyrosinase, number and size of melanosomes, the transfer rate of melanosomes to keratinocytes through the melanocyte dendritic projections and the distribution pattern of melanosomes within keratinocytes. These cellular processes are influenced by variations in skin color or UV exposure amount. When melanin synthesis exceeds melanin degradation, hyperpigmentation disorder arises. This lead to the formation of freckles or chloasma according to different skin types, age groups and degree of cumulative UV exposure. A number of treatments are commercially available, they include applying synthetic cosmetics, laser, plastic surgery, etc. These treatments usually produce side-effects and possess high risk. Therefore, searching for therapeutic agents from natural compounds has become a new research direction in cosmetology. In this study, ten herbs were chosen from traditional Chinese medicine (TCM) which had been applied for treating hyperpigmentation. The herbs were extracted by four solvents with different polarity. The extracts were screened for their hypopigmentary ability by using melan-a cells. It was found that the hexane and dichloromethane extracts of Angelica sinensis possessed positive effects. 4-ethylresorcinol, 4-ethylphenol and 1-tetradecanol, the chemical constituents of A. sinensis, also attenuated melanin amount in melan-a cells. Moreover, several biochemical techniques were utilized to study the pharmaceutical mechanisms of the potent compounds. They include Western blot, cyclic adenosine monophosphate (cAMP) assay, protein kinase A (PKA) activity assay and tyrosinase activity assay.<br>Detailed summary in vernacular field only.<br>Lam, Rosanna Yen Yen.<br>Thesis (Ph.D.)--Chinese University of Hong Kong, 2012.<br>Includes bibliographical references (leaves 127-146).<br>Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.<br>Abstract also in Chinese.<br>Abstract --- p.i<br>Chinese Abstract --- p.iii<br>Acknowledgements --- p.iv<br>List of Publications --- p.v<br>Table of Contents --- p.vi<br>List of Abbreviations --- p.xii<br>List of Figures --- p.xv<br>List of Tables --- p.xviii<br>Chapter Chapter 1 --- Introduction --- p.1<br>Chapter 1.1 --- Demand of cosmetics --- p.1<br>Chapter 1.2 --- Skin structures and functions --- p.1<br>Chapter 1.2.1 --- Epidermis --- p.3<br>Chapter 1.2.1.1 --- Stratum corneum --- p.4<br>Chapter 1.2.1.2 --- Stratum granulosum --- p.4<br>Chapter 1.2.1.3 --- Stratum spinosum --- p.4<br>Chapter 1.2.1.4 --- Stratum basale --- p.4<br>Chapter 1.2.2 --- Dermis --- p.5<br>Chapter 1.2.3 --- Hypodermis --- p.5<br>Chapter 1.3 --- Sun irradiation --- p.5<br>Chapter 1.4 --- Variety of skin types --- p.6<br>Chapter 1.5 --- Biochemical reactions within melanocyte --- p.7<br>Chapter 1.6 --- Pigmentation disorder --- p.14<br>Chapter 1.7 --- From the view of traditional Chinese medicine --- p.16<br>Chapter 1.8 --- Treatments available for hyperpigmentation --- p.18<br>Chapter 1.9 --- Aims of study and application of strategies --- p.19<br>Chapter Chapter 2 --- Investigation of the inhibitory effect of herbal extracts and their constituent compounds on melanin synthesis --- p.20<br>Chapter 2.1 --- Introduction --- p.20<br>Chapter 2.2 --- Materials and methods --- p.21<br>Chapter 2.2.1 --- Materials --- p.21<br>Chapter 2.2.2 --- Herbal extraction --- p.23<br>Chapter 2.2.3 --- Cell culture --- p.25<br>Chapter 2.2.4 --- Growth curve and melanin production curve --- p.25<br>Chapter 2.2.5 --- SRB assay --- p.26<br>Chapter 2.2.6 --- Calibration curve for SRB assay --- p.27<br>Chapter 2.2.7 --- Measurement of melanin production --- p.27<br>Chapter 2.2.8 --- Calibration curve for melanin production assay --- p.28<br>Chapter 2.2.9 --- Statistical analysis --- p.28<br>Chapter 2.3 --- Results --- p.29<br>Chapter 2.3.1 --- Growth curve and melanin production curve for assay development --- p.29<br>Chapter 2.3.2 --- Calibration curves of SRB assay and melanin production assay --- p.32<br>Chapter 2.3.3 --- Hypopigmentary effect of 40 herbal extracts --- p.35<br>Chapter 2.3.4 --- Hypopigmentary effects of chemical components of A. sinensis --- p.41<br>Chapter 2.4 --- Discussion --- p.49<br>Chapter Chapter 3 --- Study of the effect of potential compounds on melanogenic protein expression by Western blot --- p.54<br>Chapter 3.1 --- Introduction --- p.54<br>Chapter 3.2 --- Materials and methods --- p.56<br>Chapter 3.2.1 --- Materials --- p.56<br>Chapter 3.2.2 --- Cell culture --- p.56<br>Chapter 3.2.3 --- Preparation of cell lysates --- p.57<br>Chapter 3.2.4 --- Protein assay --- p.57<br>Chapter 3.2.5 --- SDS-PAGE and membrane transfer --- p.58<br>Chapter 3.2.6 --- Washing of blotted antibodies and film exposure --- p.59<br>Chapter 3.3 --- Results --- p.61<br>Chapter 3.4 --- Discussion --- p.70<br>Chapter Chapter 4 --- Study of the effect of potential compounds on melanogenic gene expression by RT-PCR --- p.76<br>Chapter 4.1 --- Introduction --- p.76<br>Chapter 4.2 --- Materials and methods --- p.76<br>Chapter 4.2.1 --- Materials --- p.77<br>Chapter 4.2.2 --- Cell culture --- p.77<br>Chapter 4.2.3 --- RNA extraction --- p.78<br>Chapter 4.2.4 --- cDNA synthesis --- p.78<br>Chapter 4.2.5 --- PCR --- p.80<br>Chapter 4.3 --- Results --- p.83<br>Chapter 4.4 --- Discussion --- p.85<br>Chapter Chapter 5 --- Study of the effect of potential compounds on cAMP level by EIA --- p.85<br>Chapter 5.1 --- Introduction --- p.86<br>Chapter 5.2 --- Materials and methods --- p.86<br>Chapter 5.2.1 --- Materials --- p.86<br>Chapter 5.2.2 --- Cell culture --- p.86<br>Chapter 5.2.3 --- Preparation of cell lysates --- p.86<br>Chapter 5.2.4 --- Protein assay --- p.87<br>Chapter 5.2.5 --- The cAMP assay --- p.88<br>Chapter 5.2.6 --- Preparation of cAMP calibration curve --- p.88<br>Chapter 5.2.7 --- Calculation --- p.89<br>Chapter 5.2.8 --- Statistical analysis --- p.89<br>Chapter 5.3 --- Results --- p.90<br>Chapter 5.4 --- Discussion --- p.94<br>Chapter Chapter 6 --- Study of the effect of potential compounds on PKA activity by PKA activity assay --- p.96<br>Chapter 6.1 --- Introduction --- p.96<br>Chapter 6.2 --- Materials and methods --- p.96<br>Chapter 6.2.1 --- Materials --- p.97<br>Chapter 6.2.2 --- Cell culture --- p.97<br>Chapter 6.2.3 --- Preparation of cell lysates --- p.98<br>Chapter 6.2.4 --- Protein assay --- p.98<br>Chapter 6.2.5 --- The PKA kinase activity assay --- p.100<br>Chapter 6.2.6 --- Calculation --- p.100<br>Chapter 6.2.7 --- Statistical analysis --- p.100<br>Chapter 6.3 --- Results --- p.101<br>Chapter 6.4 --- Discussion --- p.104<br>Chapter Chapter 7 --- Study of the effect of potential compounds on tyrosinase activity by enzyme inhibition assay --- p.107<br>Chapter 7.1 --- Introduction --- p.107<br>Chapter 7.2 --- Materials and methods --- p.108<br>Chapter 7.2.1 --- Materials --- p.108<br>Chapter 7.2.2 --- Assay development for mushroom tyrosinase --- p.109<br>Chapter 7.2.3 --- Mushroom tyrosinase inhibition assay --- p.109<br>Chapter 7.2.4 --- Cell culture --- p.110<br>Chapter 7.2.5 --- Preparation of cellular tyrosinase --- p.110<br>Chapter 7.2.6 --- Protein assay --- p.111<br>Chapter 7.2.7 --- Cellular tyrosinase inhibition assay --- p.111<br>Chapter 7.2.8 --- Calculation --- p.112<br>Chapter 7.2.9 --- Statistical analysis --- p.112<br>Chapter 7.3 --- Results --- p.113<br>Chapter 7.4 --- Discussion --- p.120<br>Chapter Chapter 8 --- General discussion --- p.123<br>References --- p.127
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Merriweather, Tarani Joy. "A [K]ink in the Armor: How the Intersection of Gender and Racial Prototypicality Affect Perceptions of Black Women Aspiring to be Managers." Thesis, 2020. https://doi.org/10.7916/d8-mzep-4z61.
Full textAbstract:
Intersectional analyses have made clear that Black women as a group fare far worse in employment outcomes than their race and gender counterparts. However, there is little research that examines differences among Black women. The purpose of this dissertation is to examine how Black women are perceived intra-intersectionally, or within the intersection of race and gender. Black women are not monolithic and it is important to illuminate how they are perceived differently from one another. This dissertation explores the effects of differences in skin tone and hair texture among Black women seeking a management position. It was hypothesized that Black women with lighter skin and/or straight hair would be characterized more positively than Black women with darker skin and/or kinky hair; this hypothesis was not supported. However, for negative characteristics, the hypothesis that Black women with darker skin would be characterized more negatively than Black women with lighter skin was confirmed. Further, it was found that hair texture significantly interacts with skin tone such that darker-skinned Black women with kinky hair were characterized more negatively than light-skinned women with kinky hair. There were no significant differences found between the skin tone and hair texture of Black women on salary offers, but there was a marginally significant skin tone effect for perceptions of success in that lighter-skinned Black women are perceived to be more successful than darker-skinned Black women. This study sheds light on the need to look at the intersection of both skin tone and hair texture in order to fully understand how negative stereotypes apply to Black women.
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Nogemane, Noluyolo. "Propagation and quality assessment for the introduction of Greyia Radlkoferi into commercialization." Thesis, 2017. http://hdl.handle.net/10500/23603.
Full textAbstract:
Greyia radlkoferi is a South African indigenous tree, which has recently been discovered to be a source of extracts that have a potential in the development of cosmeceutical herbal products having the ability to treat hyperpigmentation disorders. For product development however, G. radlkoferi would need to be available in a commercial scale. Greyia radlkoferi grows naturally in the wild and is often available for cultivation as an ornamental plant. In order to establish this plant into cultivation, suitable propagation techniques must be established for rapid multiplication of trees and thus a sustainable leaf production. For consistent and improved leaf supply to the market, agronomic practices that will enhance leaf production were investigated in the current study. Furthermore, in order to meet market demand in terms of good quality extracts with guaranteed therapeutic efficiency, pre-harvest and post-harvest factors that affect the chemical composition of the extracts were investigated. Recently developed biotechnology techniques such as metabolomics using 1H-NMR and multivariate data analysis offered a platform to study the chemical variation of extracts. Therefore, the current study was aimed at understanding the requirements for propagation and optimum leaf production as well as conditions that favour optimum production of secondary metabolite of G. radlkoferi plant material (at pre and post-harvest) and thus assess its commercial viability.
To understand the effects of temperature on seed germination of G. radlkoferi, seeds were exposed to five temperatures (10°C, 15°C, 20°C, 25°C and 30°C) in the incubators in the laboratory. Germination of G. radlkoferi by seeds was discovered to be temperature dependent. The optimum germination temperature of 81% was obtained at 25°C. In the case of vegetative propagation by stem cuttings, the effect of cutting position (basal or apical), exogenous rooting hormone (Seradix1, Seradix 2, 0.1% IBA, 0.3% IBA and 0.8% IBA) and cutting position were investigated in the glasshouse. The cutting position had a significant effect on rooting of G. radlkoferi cuttings with basal cuttings exhibiting 35% rooting as compared to 6% rooting attained for the apical cuttings. A clear trend in rooting response to application of rooting hormones was observed, with 0.1% Indole butyric acid (IBA) showing the highest rooting percentage of 63%. Considering the outcomes of the propagation studies as well as the limited material for vegetative propagation, seed propagation appears to be the most suitable technique for large-scale multiplication of G. radlkoferi.
The effect of different pruning techniques as well as harvesting frequencies on fresh and dry weights of G. radlkoferi leaves were evaluated. Factors considered were four pruning treatments (‘pruned but not tipped’, ‘tipped but not pruned’, ‘not pruned nor tipped’ as well as ‘pruned and tipped’) and three harvesting periods (monthly, bimonthly and once–off). Bimonthly harvests highly increased leaf production compared to trees that were harvested monthly and once-off with higher leaf fresh weight yield of 238 g per tree or 2.38 tons/per hectare as well as dry weight yield of 83 g per tree or 0.830 tons/hectare. This outcomes of this study further suggested that a suitable pruning practice for G. radlkoferi would be to either ‘prune only’ or ‘cut back the main stem’ rather than a combination of the two treatments.
The influence of seasons (summer, autumn, winter and spring) on the anti-tyrosinase activity and metabolomics profile of G. radlkoferi leaf extracts were investigated. Seasons significantly influenced the chemical composition and the efficacy of the plant extracts. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) with kojic acid as positive control. The highest tyrosinase inhibition concentration with IC50 (50% tyrosinase inhibition concentration) value of 30.3±1.8 μg/ml were obtained in winter harvested leaves compared to the other seasons. The lowest IC50 values were obtained in spring. Metabolomics analysis using orthogonal partial least square discriminant analysis (OPLS-DA) provided a clear class separation according to the harvest season. Extracts from winter harvested leaves contained sucrose, acetamide, alanine and a compound of the catechin group (gallocatechin-(4 alpha->8)-epigallocatechin) as revealed by 1H-NMR metabolomics with assistance of LC-MS. Since compounds of the catechin group are well-known tyrosinase inhibitors, the high tyrosinase activity exhibited in extracts of winter harvested G. radlkoferi leaves could be ascribed to the presence of gallocatechin-(4 alpha->8)-epigallocatechin. Based on the outcomes of the seasonal study, we suggest that in order to obtain extracts with high bioactivity, the best suitable time for harvesting leaf samples is in late autumn-early winter.
Processing leaf material using three different drying methods (sun, oven and air drying) significantly influenced chemical composition and the efficacy of the plant extracts. Extracts prepared from air-dried leaf material showed the highest tyrosinase inhibition with IC50 value of 17.80 μg/ml compared to extracts of the other drying methods. Extracts of leaves processed with air drying preserved most metabolites during processing while extracts of sun-dried and oven-dried leaves clearly depleted some metabolites especially amino acids and some aromatic compounds. 1H-NMR metabolomics approach with the assistance of LC-MS data successfully determined a positive association of alanine, acetamide, sucrose and gallocatechin-(4 alpha->8)-epigallocatechin as the chemical constituents contributing to the variation in the air-dried leaves compared to the oven-dried leaves. A positive association of valine, alanine, leucine, isoleucine, gallocatechin-(4 alpha->8)-epigallocatechin and glucose contributed to the variation in air-dried group, compared to the sun-dried group. The highest tyrosinase inhibitory activity exhibited in air-dried samples compared to the other drying methods was associated with the presence of gallocatechin-(4 alpha->8)-epigallocatechin. Because air drying preserved most leaf metabolites compared to sun and oven drying, it was regarded as the most suitable method for processing G. radlkoferi leaf material.
This study is the first scientific account that provides guidelines and recommendations to (1) establish G. radlkoferi as a cultivated plant for commercialization, (2) optimize leaf production for sustainable supply to the commercial markets and (3) optimize medicinal content of G. radlkoferi related to harvesting time and post-harvest processing (drying), for enhanced quality of extracts and its products<br>Agriculture, Animal Health and Human Ecology<br>Ph. D. (Agriculture)