This work presents my research about the use of Convolutional Neural Network (CNNs) for transfer learning through its application for colonic polyp classification and iris super-resolution. Traditionally, machine learning methods use the same feature space and the same distribution for training and testing the tools. Several problems in this approach can emerge as, for example, when the number of samples for training (especially in a supervised training) is limited. In the medical field, this problem is recurrent mainly because obtaining a database large enough with appropriate annotations for training is highly costly and may become impractical. Another problem relates to the distribution of textural features in a image database which may be too large such as the texture patterns of the human iris. In this case a single and specific training database might not get enough generalization to be applied to the entire domain. In this work we explore the use of texture transfer learning to surpass these problems for two applications: colonic polyp classification and iris super-resolution. The leading cause of deaths related to intestinal tract is the development of cancer cells (polyps) in its many parts. An early detection (when the cancer is still at an early stage) can reduce the risk of mortality among these patients. More specifically, colonic polyps (benign tumors or growths which arise on the inner colon surface) have a high occurrence and are known to be precursors of colon cancer development. Several studies have shown that automatic detection and classification of image regions which may contain polyps within the colon can be used to assist specialists in order to decrease the polyp miss rate. However, the classification can be a difficult task due to several factors such as the lack or excess of illumination, the blurring due to movement or water injection and the different appearances of polyps. Also, to find a robust and a global feature extractor that summarizes and represents all these pit-patterns structures in a single vector is very difficult and Deep Learning can be a good alternative to surpass these problems. One of the goals of this work is show the effectiveness of CNNs trained from scratch for colonic polyp classification besides the capability of knowledge transfer between natural images and medical images using off-the-shelf pretrained CNNs for colonic polyp classification. In this case, the CNN will project the target database samples into a vector space where the classes are more likely to be separable. The second part of this work dedicates to the transfer learning for iris super-resolution. The main goal of Super-Resolution (SR) is to produce, from one or more images, an image with a higher resolution (with more pixels) at the same time that produces a more detailed and realistic image being faithful to the low resolution image(s). Currently, most iris recognition systems require the user to present their iris for the sensor at a close distance. However, at present, there is a constant pressure to make that relaxed conditions of acquisitions in such systems could be allowed. In this work we show that the use of deep learning and transfer learning for single image super resolution applied to iris recognition can be an alternative for Iris Recognition of low resolution images. For this purpose, we explore if the nature of the images as well as if the pattern from the iris can influence the CNN transfer learning and, consequently, the results in the recognition process. / Diese Arbeit pr¨asentiert meine Forschung hinsichtlich der Verwendung von ”Transfer-Learning” (TL) in Kombination mit Convolutional Neural Networks (CNNs), um dadurch die Klassifikation von Dickdarmpolypen und die Qualit¨at von Iris Bildern (”Iris-Super-Resolution”) zu verbessern. Herk¨ommlicherweise verwenden Verfahren des maschinellen Lernens den gleichen Merkmalsraum und die gleiche Verteilung zum Trainieren und Testen der abgewendeten Methoden. Mehrere Probleme k¨onnen bei diesem Ansatz jedoch auftreten. Zum Beispiel ist es m¨ oglich, dass die Anzahl der zu trainierenden Daten (insbesondere in einem ”supervised training” Szenario) begrenzt ist. Im Speziellen im medizinischen Anwendungsfall ist man regelm¨aßig mit dem angesprochenen Problem konfrontiert, da die Zusammenstellung einer Datenbank, welche ¨ uber eine geeignete Anzahl an verwendbaren Daten verf ¨ ugt, entweder sehr kostspielig ist und/oder sich als ¨ uber die Maßen zeitaufw¨andig herausstellt. Ein anderes Problem betrifft die Verteilung von Strukturmerkmalen in einer Bilddatenbank, die zu groß sein kann, wie es im Fall der Verwendung von Texturmustern der menschlichen Iris auftritt. Dies kann zu dem Umstand f ¨ uhren, dass eine einzelne und sehr spezifische Trainingsdatenbank m¨oglicherweise nicht ausreichend verallgemeinert wird, um sie auf die gesamte betrachtete Dom¨ane anzuwenden. In dieser Arbeit wird die Verwendung von TL auf diverse Texturen untersucht, um die zuvor angesprochenen Probleme f ¨ ur zwei Anwendungen zu ¨ uberwinden: in der Klassifikation von Dickdarmpolypen und in Iris Super-Resolution. Die Hauptursache f ¨ ur Todesf¨alle im Zusammenhang mit dem Darmtrakt ist die Entwicklung von Krebszellen (Polypen) in vielen unterschiedlichen Auspr¨agungen. Eine Fr ¨uherkennung kann das Mortalit¨atsrisiko bei Patienten verringern, wenn sich der Krebs noch in einem fr ¨uhen Stadium befindet. Genauer gesagt, Dickdarmpolypen (gutartige Tumore oder Wucherungen, die an der inneren Dickdarmoberfl¨ache entstehen) haben ein hohes Vorkommen und sind bekanntermaßen Vorl¨aufer von Darmkrebsentwicklung. Mehrere Studien haben gezeigt, dass die automatische Erkennung und Klassifizierung von Bildregionen, die Polypen innerhalb des Dickdarms m¨oglicherweise enthalten, verwendet werden k¨onnen, um Spezialisten zu helfen, die Fehlerrate bei Polypen zu verringern. Die Klassifizierung kann sich jedoch aufgrund mehrerer Faktoren als eine schwierige Aufgabe herausstellen. ZumBeispiel kann das Fehlen oder ein U¨ bermaß an Beleuchtung zu starken Problemen hinsichtlich der Kontrastinformation der Bilder f ¨ uhren, wohingegen Unsch¨arfe aufgrund von Bewegung/Wassereinspritzung die Qualit¨at des Bildmaterials ebenfalls verschlechtert. Daten, welche ein unterschiedlich starkes Auftreten von Polypen repr¨asentieren, bieten auch dieM¨oglichkeit zu einer Reduktion der Klassifizierungsgenauigkeit. Weiters ist es sehr schwierig, einen robusten und vor allem globalen Feature-Extraktor zu finden, der all die notwendigen Pit-Pattern-Strukturen in einem einzigen Vektor zusammenfasst und darstellt. Um mit diesen Problemen ad¨aquat umzugehen, kann die Anwendung von CNNs eine gute Alternative bieten. Eines der Ziele dieser Arbeit ist es, die Wirksamkeit von CNNs, die von Grund auf f ¨ ur die Klassifikation von Dickdarmpolypen konstruiert wurden, zu zeigen. Des Weiteren soll die Anwendung von TL unter der Verwendung vorgefertigter CNNs f ¨ ur die Klassifikation von Dickdarmpolypen untersucht werden. Hierbei wird zus¨atzliche Information von nichtmedizinischen Bildern hinzugezogen und mit den verwendeten medizinischen Daten verbunden: Information wird also transferiert - TL entsteht. Auch in diesem Fall projiziert das CNN iii die Zieldatenbank (die Polypenbilder) in einen vorher trainierten Vektorraum, in dem die zu separierenden Klassen dann eher trennbar sind, daWissen aus den nicht-medizinischen Bildern einfließt. Der zweite Teil dieser Arbeit widmet sich dem TL hinsichtlich der Verbesserung der Bildqualit¨at von Iris Bilder - ”Iris- Super-Resolution”. Das Hauptziel von Super-Resolution (SR) ist es, aus einem oder mehreren Bildern gleichzeitig ein Bild mit einer h¨oheren Aufl¨osung (mit mehr Pixeln) zu erzeugen, welches dadurch zu einem detaillierteren und somit realistischeren Bild wird, wobei der visuelle Bildinhalt unver¨andert bleibt. Gegenw¨artig fordern die meisten Iris- Erkennungssysteme, dass der Benutzer seine Iris f ¨ ur den Sensor in geringer Entfernung pr¨asentiert. Jedoch ist es ein Anliegen der Industrie die bisher notwendigen Bedingungen - kurzer Abstand zwischen Sensor und Iris, sowie Verwendung von sehr teuren hochqualitativen Sensoren - zu ver¨andern. Diese Ver¨anderung betrifft einerseits die Verwendung von billigeren Sensoren und andererseits die Vergr¨oßerung des Abstandes zwischen Iris und Sensor. Beide Anpassungen f ¨ uhren zu Reduktion der Bildqualit¨at, was sich direkt auf die Erkennungsgenauigkeit der aktuell verwendeten Iris- erkennungssysteme auswirkt. In dieser Arbeit zeigen wir, dass die Verwendung von CNNs und TL f ¨ ur die ”Single Image Super-Resolution”, die bei der Iriserkennung angewendet wird, eine Alternative f ¨ ur die Iriserkennung von Bildern mit niedriger Aufl¨osung sein kann. Zu diesem Zweck untersuchen wir, ob die Art der Bilder sowie das Muster der Iris das CNN-TL beeinflusst und folglich die Ergebnisse im Erkennungsprozess ver¨andern kann.

Triangle-mesh modeling, as one of the approaches for representing images based on nonuniform sampling, has become quite popular and beneficial in many applications. In this thesis, image representation using triangle-mesh models and its application in image scaling are studied. Consequently, two new methods, namely, the SEMMG and MIS methods are proposed, where each solves a different problem. In particular, the SEMMG method is proposed to address the problem of image representation by producing effective mesh models that are used for representing grayscale images, by minimizing squared error. The MIS method is proposed to address the image-scaling problem for grayscale images that are approximately piecewise-smooth, using triangle-mesh models. The SEMMG method, which is proposed for addressing the mesh-generation problem, is developed based on an earlier work, which uses a greedy-point-insertion (GPI) approach to generate a mesh model with explicit representation of discontinuities (ERD). After in-depth analyses of two existing methods for generating the ERD models, several weaknesses are identified and specifically addressed to improve the quality of the generated models, leading to the proposal of the SEMMG method. The performance of the SEMMG method is then evaluated by comparing the quality of the meshes it produces with those obtained by eight other competing methods, namely, the error-diffusion (ED) method of Yang, the modified Garland-Heckbert (MGH) method, the ERDED and ERDGPI methods of Tu and Adams, the Garcia-Vintimilla-Sappa (GVS) method, the hybrid wavelet triangulation (HWT) method of Phichet, the binary space partition (BSP) method of Sarkis, and the adaptive triangular meshes (ATM) method of Liu. For this evaluation, the error between the original and reconstructed images, obtained from each method under comparison, is measured in terms of the PSNR. Moreover, in the case of the competing methods whose implementations are available, the subjective quality is compared in addition to the PSNR. Evaluation results show that the reconstructed images obtained from the SEMMG method are better than those obtained by the competing methods in terms of both PSNR and subjective quality. More specifically, in the case of the methods with implementations, the results collected from 350 test cases show that the SEMMG method outperforms the ED, MGH, ERDED, and ERDGPI schemes in approximately 100%, 89%, 99%, and 85% of cases, respectively. Moreover, in the case of the methods without implementations, we show that the PSNR of the reconstructed images produced by the SEMMG method are on average 3.85, 0.75, 2, and 1.10 dB higher than those obtained by the GVS, HWT, BSP, and ATM methods, respectively. Furthermore, for a given PSNR, the SEMMG method is shown to produce much smaller meshes compared to those obtained by the GVS and BSP methods, with approximately 65% to 80% fewer vertices and 10% to 60% fewer triangles, respectively. Therefore, the SEMMG method is shown to be capable of producing triangular meshes of higher quality and smaller sizes (i.e., number of vertices or triangles) which can be effectively used for image representation. Besides the superior image approximations achieved with the SEMMG method, this work also makes contributions by addressing the problem of image scaling. For this purpose, the application of triangle-mesh mesh models in image scaling is studied. Some of the mesh-based image-scaling approaches proposed to date employ mesh models that are associated with an approximating function that is continuous everywhere, which inevitably yields edge blurring in the process of image scaling. Moreover, other mesh-based image-scaling approaches that employ approximating functions with discontinuities are often based on mesh simplification where the method starts with an extremely large initial mesh, leading to a very slow mesh generation with high memory cost. In this thesis, however, we propose a new mesh-based image-scaling (MIS) method which firstly employs an approximating function with selected discontinuities to better maintain the sharpness at the edges. Secondly, unlike most of the other discontinuity-preserving mesh-based methods, the proposed MIS method is not based on mesh simplification. Instead, our MIS method employs a mesh-refinement scheme, where it starts from a very simple mesh and iteratively refines the mesh to reach a desirable size. For developing the MIS method, the performance of our SEMMG method, which is proposed for image representation, is examined in the application of image scaling. Although the SEMMG method is not designed for solving the problem of image scaling, examining its performance in this application helps to better understand potential shortcomings of using a mesh generator in image scaling. Through this examination, several shortcomings are found and different techniques are devised to address them. By applying these techniques, a new effective mesh-generation method called MISMG is developed that can be used for image scaling. The MISMG method is then combined with a scaling transformation and a subdivision-based model-rasterization algorithm, yielding the proposed MIS method for scaling grayscale images that are approximately piecewise-smooth. The performance of our MIS method is then evaluated by comparing the quality of the scaled images it produces with those obtained from five well-known raster-based methods, namely, bilinear interpolation, bicubic interpolation of Keys, the directional cubic convolution interpolation (DCCI) method of Zhou et al., the new edge-directed image interpolation (NEDI) method of Li and Orchard, and the recent method of super-resolution using convolutional neural networks (SRCNN) by Dong et al.. Since our main goal is to produce scaled images of higher subjective quality with the least amount of edge blurring, the quality of the scaled images are first compared through a subjective evaluation followed by some objective evaluations. The results of the subjective evaluation show that the proposed MIS method was ranked best overall in almost 67\% of the cases, with the best average rank of 2 out of 6, among 380 collected rankings with 20 images and 19 participants. Moreover, visual inspections on the scaled images obtained with different methods show that the proposed MIS method produces scaled images of better quality with more accurate and sharper edges. Furthermore, in the case of the mesh-based image-scaling methods, where no implementation is available, the MIS method is conceptually compared, using theoretical analysis, to two mesh-based methods, namely, the subdivision-based image-representation (SBIR) method of Liao et al. and the curvilinear feature driven image-representation (CFDIR) method of Zhou et al.. / Graduate

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2018-11-12T10:55:35Z No. of bitstreams: 1 Pablo Ribeiro Cardoso.pdf: 4461936 bytes, checksum: 63c9955bd9b623838e08da4bcc3fde5b (MD5) / Made available in DSpace on 2018-11-12T10:55:35Z (GMT). No. of bitstreams: 1 Pablo Ribeiro Cardoso.pdf: 4461936 bytes, checksum: 63c9955bd9b623838e08da4bcc3fde5b (MD5) Previous issue date: 2018-09-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This research has as its main objective to discuss overcoming the organic limits of the body through biotechnological interventions, taking as basis the superhero characters. Starting from the field of changes in the biopowers listed by Nikolas Rose and the anthropogenic effects of biotechnologies, it initially seeks to understand the emergence of the posthuman concept and how it implies new ways of thinking the body in the contemporary, especially from the proposals for human enhancement. The posthuman is thought of as an umbrella term to refer to a variety of different movements and schools of thought, including scientific, philosophical, artistic, and mystical discussions of the most varied aspects. Aiming to offer contributions on the subject, contemporary projects of human enhancement through biomedical/biotechnology paths are studied, thus excluding from this research transcendental approaches or the ones that preach the total substitution of the biological body for digital. Once these projects have been explored, based on Lucia Santaella's conceptualization of prostheses, ways of overcoming the limits of the human body through biotechnological interventions are discussed, with biotechnological hybridization of the new prostheses as the main focus. Choosing superheroes as interlocutors in this debate, the research rescues their historical and social backgrounds, delineates who these characters are, and analyze the bodies portrayed by them, named by Scott Jeffery as superhuman bodies. It explores, therefore, the different ways in which superheroes illustrate the idea of an improved human body. Finally, to support the role of superheroes as basis of the discussions proposed in the research, the text dialogues with descriptions of adventures and images from comic books or films which these characters are the protagonists / Esta pesquisa tem como seu objetivo central discutir superação dos limites orgânicos do corpo a partir de intervenções biotecnocientíficas, tomando como disparadores os personagens super-heróis. Partindo do campo das mudanças no âmbito dos biopoderes elencadas por Nikolas Rose e dos efeitos antropogênicos das biotecnologias, busca-se inicialmente compreender a emergência do conceito pós-humano e como ele implica novos modos de se pensar o corpo no contemporâneo, especialmente a partir das propostas de melhoramento humano. O pós-humano é pensado como um conceito guarda-chuva que abriga uma multiplicidade de saberes que envolvem tanto discussões científicas quanto filosóficas, artísticas e místicas das mais variadas vertentes. Visando oferecer contribuições acerca do tema, são estudados projetos contemporâneos de melhoramento humano por vias biomédicas/biotecnocientíficas, excluindo, assim, dessa pesquisa as abordagens transcendentais ou que pregam a substituição total do corpo biológico pelo digital. Uma vez explorados tais projetos, fundamentados na conceituação de Lucia Santaella sobre próteses, são discutidos modos de superação dos limites do corpo humano a partir das intervenções biotecnológicas, com principal destaque para o hibridismo biotecnológico das novas próteses. Elegendo os super-heróis como interlocutores desse debate, a pesquisa resgata seus antecedentes históricos e sociais, delimita quem são esses personagens e analisa os corpos retratados por eles, nomeados por Scott Jeffery como corpos super-humanos. Explora-se, portanto, os diferentes modos em que os super-heróis ilustram a ideia de um corpo sobre-humano. Por fim, para sustentar o papel destinado aos super-heróis como disparadores das discussões propostas na pesquisa, o texto dialoga com descrição de aventuras e imagens oriundas de histórias em quadrinhos ou filmes protagonizados por essas figuras

Using Time of Arrival (TOA) as ranging metric is the most popular technique for accurate indoor positioning. Accuracy of measuring the distance using TOA is sensitive to the bandwidth of the system and the multipath condition between the wireless terminal and the access point. In a telecommunication-specific application, the channel is divided into Line of Sight (LOS) and Obstructed Line of Sight (OLOS) based on the existence of physical obstruction between the transmitter and receiver. In indoor geolocation application, with extensive multipath conditions, the emphasis is placed on the behavior of the first path and the channel conditions are classified as Dominant Direct Path (DDP), Nondominant Direct Path (NDDP) and Undetected Direct Path (UDP). In general, as the bandwidth increases the distance measurement error decreases. However, for the so called UDP conditions the system exhibits substantially high distance measurement errors that can not be eliminated with the increase in the bandwidth of the system. Based on existing measurements performed in CWINS, WPI a measurement database that contains adequate number of measurement samples of all the different classification is created. Comparative analysis of TOA estimation in different multipath conditions is carried out using the measurement database. The performance of super-resolution and traditional TOA estimation algorithms are then compared in LOS, OLOS DDP, NDDP and UDP conditions. Finally, the analysis of the effect of system bandwidth on the behavior of the TOA of the first path is presented.

There has been significant progress in the optical resolution of microscopes over the last two decades. However, the majority of currently used methods (e.g. STED, PALM, STORM) have a number of drawbacks, including high intensities of light that result in damage to living specimens in STED, and long data acquisition time leading to limitations on live-cell imaging. Therefore, there is a niche for faster image acquisition at lower intensities while maintaining resolution beyond the diffraction limit. Here, we have developed a new methodology - Quantum Dot-based Optical Spectral Separation (QDOSS) - which relies on using Quantum Dots (QDs) as fluorophores, and on their separation and localisation based on their spectral signatures. We utilise the key advantages of QDs over the usual organic fluorophores: broad excitation, narrow emission spectra and high resistance to photobleaching. Besides, since QDOSS is based on spectral differences for separation, QDs can be deterministically localised in a relatively short time - milliseconds and, potentially, microseconds. Last but not least, QDOSS is suitable for obtaining super-resolution images using a standard confocal fluorescence microscope equipped with a single laser excitation wavelength and capable of spectral signal separation (e.g. Leica TCS SP series or Zeiss LSM series). First, we demonstrated resolution down to 60 nm using triangular DNA origami as a reference. Furthermore, we labelled and imaged the alpha-tubulin structure in HEK293T cells. We showed that using a mixture of standard off-the-shelf QDs of different sizes, resolution down to 40 nm could be achieved via spectroscopic separation of QDs. Finally, we demonstrated that QDOSS could also be used for multicolour imaging of synaptic proteins distributed around synapsis in neurons within diffraction limit. All in all, we believe that these features of QDOSS make it a potential method for long-term live super-resolution imaging, which is going to have a high impact in biological sciences.

Made available in DSpace on 2016-04-26T18:18:36Z (GMT). No. of bitstreams: 1 Luis Fernando dos Reis Pereira.pdf: 15618526 bytes, checksum: 7c4a48c46f9ef0aaaa328e95ab03933c (MD5) Previous issue date: 2010-05-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This thesis analyzes the fictional narratives of the comics books series Sandman, written by the British author Neil Gaiman, originally published by DC Comics and, in Brazil, by Globo, from 1989 to 1996, noting the translation and appropriation of elements from different cultural contexts for the construction of the narrative, in order to demonstrate that Sandman has a higher tendency to mobility and articulation than the superhero s comic books, which generally emphasize the structures of permanence and isolation. We investigate how the principle of identity, developed by certain core of Western thought is used, as well as different characteristics from other cultural backgrounds, bringing into play concepts such as centrality and periphery, reality/fiction, stability/instability, etc. In support of our journey, we turn to theories about the processes and semiotic systems of culture, exploring and articulating studies of Yuri Lotman, Severo Sarduy, Amálio Pinheiro, Jesus Martín-Barbero and Edgar Morin, while the theories of Scott McCloud and Will Eisner served as basis for studying the recent and still in process language of the "comics" as art and media; we counted, as well, with the major contributions of Bakhtin s theories of novel and literary genres carnavalization, to support aspects of narrative language on the studied comics. The Sandman series, with 75 editions and some special publications, combines aspects of the American superhero comics, mythology, pop culture, literature, religion, paganism, magic, fantasy, gothic horror, historical facts, philosophical references, elements of the classic epic and folklore to tell the story of Dream, also called Oneiros, Morpheus, etc., ruler of the Dreaming, and their complex relations with humanity and other beings, including his siblings Destiny, Death, Destruction, Desire, Despair and Delirium; modern gods and those who have been forgotten; their mortal and immortal lovers; Lucifer and his demons; and even the angels. In the periphery of such a mosaic plot, perverting the classic epic elements, remnants of the drama of a missing hero, unfinished and absurd, unable to remain equal to himself, and who insists in to inhabit different borders: islands between reality and the Dreaming; soft regions where time becomes malleable (local of translations between the familiar and the foreign), and his own kingdom, which is a metaphorical border between life and death. Such arrangements allow the discussion of the signic operating environment proposed by Lotman, the semiosphere, and its mobile/translation borders, a key concept to understanding the trends of permanence and change of the cultural texts Finally, Dream, occasional actor, the personification of the dream itself, questions, over the stories, the objective notions of identity, truth and immutability, as well as we may question, similarly, the principle of identity in self-centered and self-referencing cultures based on binary logic and mainly closed systems that tend to generate several ways of exclusion, through the idea of truth and tolerance, unlike the Sandman s realm environments, linked to Derrida's discussion of the idea of hospitality / A tese analisa as narrativas ficcionais da série de revistas em quadrinhos Sandman, do autor britânico Neil Gaiman, publicadas originalmente nos EUA pela editora estadunidense DC Comics e no Brasil, a princípio, pela editora Globo, entre 1989 e 1996, a partir da tradução e apropriação de elementos provenientes de diferentes contextos culturais para as construções da narrativa, com o objetivo de demonstrar que Sandman apresenta maior tendência à mobilidade e à articulação do que os gibis de super-heróis, que geralmente enfatizam as estruturas de permanência e isolamento. Em nosso trajeto, investigamos como o princípio de identidade, desenvolvido por determinados núcleos do pensamento ocidental, é aproveitado, assim como características distintas, de outros contextos culturais, colocando em jogo conceitos como centralidade/descentralidade, realidade/ficção, estabilidade/instabilidade, etc. Para fundamentar nosso percurso, recorremos às teorias sobre processos e sistemas semióticos da cultura, explorando e articulando estudos de Iuri Lotman, Severo Sarduy, Amálio Pinheiro, Jésus Martín-Barbero e Edgar Morin, enquanto as teorias de Scott McCloud e Will Eisner embasaram o estudo da linguagem recente e ainda em formação da mídia quadrinhos em conjunto com as teorias do romance e da carnavalização de gêneros de Bakhtin, dando suporte aos aspectos da linguagem narrativa da série analisada. Sandman, composta por 75 edições e algumas publicações especiais, combina aspectos dos quadrinhos de super-heróis estadunidenses, mitologia, cultura pop, literatura, religiosidade, paganismo, magia, fantasia, horror gótico, fatos históricos, referências filosóficas, elementos da epopeia clássica e do folclore para contar a história de Sonho, também chamado Oneiros, Morpheus, Tecedor de Formas, etc., soberano do Sonhar, e suas complexas relações com a humanidade e outros seres, entre eles seus irmãos Destino, Morte, Destruição, Desejo, Desespero e Delírio; os deuses modernos e os que já foram esquecidos; suas amantes mortais e imortais; Lúcifer e seus demônios e mesmo os anjos. Na periferia de tal trama em mosaico, pervertendo os elementos épicos clássicos, há resquícios do drama de um herói ausente , inacabado e absurdo, incapaz de permanecer igual a si mesmo e que insiste em habitar vários aspectos fronteiriços: ilhas entre a realidade e o Sonhar, regiões brandas, onde o tempo se torna maleável (locais de tradução entre o familiar e o estrangeiro), e seu próprio reino, fronteira metafórica entre a vida e a morte. Tais articulações possibilitam que sejam discutidos o ambiente de operação sígnica proposto por Lotman, a semiosfera, e suas fronteiras móveis/tradutórias, noção-chave para a compreensão das tendências de permanência e de mudança dos textos da cultura. Finalmente, Sonho, protagonista ocasional que é a personificação dos sonhos, questiona, ao longo das histórias, as noções objetivas de identidade, de verdade e de imutabilidade. Pode ser questionado, analogamente, o princípio de identidade de culturas autocentradas e autorreferentes baseadas em lógicas binárias e em sistemas preponderantemente fechados que costumam gerar exclusão, por meio da ideia de verdade e de tolerância, ao contrário dos ambientes do reino do Sonhar de Sandman, afeitos à ideia de hospitalidade discutida por Derrida

No description available.

Natural Killer (NK) cells are cytotoxic lymphocytes that can recognize and kill virally infected or tumour transformed cells by the secretion of cytolytic granules containing perforin. An individual NK cell can kill several target cells sequentially. Each target cell can trigger NK cell activation via different activating ligands and here we report that the order in which ligands are encountered affects the NK cell response. When NK cells are repeatedly activated via their Fc receptor CD16, with the therapeutic antibody rituximab, perforin secretion decreases with each stimulation. However, perforin secretion is restored to its initial level upon subsequent activation by MICA, which ligates NKG2D. Repeated stimulation of NK cells via MICA also decreases the degranulation capacity of NK cells but, strikingly, this effect cannot be rescued by a subsequent stimulation with rituximab. The strength of perforin secretion is also translated to killing of Daudi target cells, expressing different ligands. When Daudi, opsonised with rituximab is the first target NK cell encounters, the sequential killing of another opsonised rituximab or Daudi, expressing MICA will not be affected. But, when Daudi-MICA is met first, the consecutive killing of Daudi-MICA as well as Daudi-rituximab will be impaired. We found that the mechanism underlying these differential outcomes involves shedding of CD16, which occurs upon NK cell activation through both, CD16 and NKG2D. Shedding of CD16 renders the cells insensitive to further activation via that receptor but they remain competent for further activation through NKG2D. Interestingly, however, we also identified the beneficial role of CD16 shedding for NK cell serial killing. NK cells are more motile on rituximab-coated surfaces than on MICA-coated surfaces and their migration speed decreases upon inhibition of CD16 shedding. Moreover, the inhibition of CD16 shedding also prevents the NK cell detachment from rituximab opsonised Daudi cells. Thus, the shedding of the receptor can serve to augment NK cell motility to move between target cells. Efficient NK cell detachment also correlated with their increased survival. Finally, we report that CD16 is constitutively organised in small, dense nanoclusters and that the ligation with rituximab does not affect their spatial distribution. Despite the shedding of the receptor, leading to less protein molecules at the surface, the area of these clusters remains the same. Together these data suggest that CD16 shedding hinders NK cell cytotoxicity against opsonised targets, but promotes their movements between different targets. Thus, receptor shedding is important for efficient NK cell serial killing. Manipulation of CD16 shedding, perhaps by boosting its recovery, might therefore represent an important target for NK cell-based therapies including treatments with therapeutic antibodies.

Optical cell manipulation allows precise and non-invasive exploration of mammalian cell function and physiology for medical applications. Plants, however, represent a vital component of the Earth's ecosystem and the knowledge gained from using optical tools to study plant cells can help to understand and manipulate useful agricultural and ecological traits. This thesis explores the potential of several biophotonic techniques in plant cells and tissue. Laser-mediated introduction of nucleic acids and other membrane impermeable molecules into mammalian cells is an important biophotonic technique. Optical injection presents a tool to deliver dyes and drugs for diagnostics and therapy of single cells in a sterile and interactive manner. Using femtosecond laser pulses increases the tunability of multiphoton effects and confines the damage volume, providing sub-cellular precision and high viability. Extending current femtosecond photoporation knowledge to plant cells could have sociological and environmental benefits, but presents different challenges to mammalian cells. The effects of varying optical and biological parameters on optical injection of a model plant cell line were investigated. A reconfigurable optical system was designed to allow easy switching between different spatial modes and pulse durations. Varying the medium osmolarity and optoinjectant size and type affected optoinjection efficacy, allowing optimisation of optical delivery of relevant biomolecules into plant cells. Advanced optical microscopy techniques that allow imaging beyond the diffraction limit have transformed biological studies. An ultimate goal is to merge several biophotonic techniques, creating a plant cell workstation. A step towards this was demonstrated by incorporating a fibre-based optical trap into a commercial super-resolution microscope for manipulation of cells and organelles under super-resolution. As proof-of-concept, the system was used to optically induce and quantify an immunosynapse. The capacity of the super-resolution microscope to resolve structure in plant organelles in aberrating plant tissue was critically evaluated.

Orientador: Gustavo Michel Mendoza La Torre / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Física, 2009.