Thesis advisor: Zhifeng Ren / Solid-state cooling and power generation based on thermoelectric effects are attractive for a wide range of applications in power generation, waste heat recovery, air-conditioning, and refrigeration. There have been persistent efforts on improving the figure of merit (ZT) since the 1950's; only incremental gains were achieved in increasing ZT, with the (Bi1-xSbx)2(Se1-yTey)3 alloy family remaining the best commercial material with ZT ~ 1. To improve ZT to a higher value, we have been pursuing an approach based on random nanostructures and the idea that the thermal conductivity reduction that is responsible for ZT enhancement in superlattices structures can be realized in such nanostructures. The synthesis and characterization of various nanopowders prepared by wet chemical as well as high energy ball milling methods will be discussed in this dissertation. The solid dense samples from nanopowders were prepared by direct current induced hot press (DC hot press) technique. The thermoelectric properties of the hot pressed samples have been studied in detail. By ball milling ingots of bulk alloy crystals and hot pressing the nanopowders, we had demonstrated a high figure-of-merit in nanostructured bulk bismuth antimony telluride. In this dissertation, we use the same ball milling and hot press technique, but start with elemental chunks of bismuth, antimony, and tellurium to avoid the ingot formation step. We show that a peak ZT of about 1.3 can be achieved. Our material also exhibits a ZT of 0.7 at 250 °C, close to the value reached when ingot was used. This process is more economical and environmentally friendly than starting from bulk alloy crystals. The ZT improvement is caused mostly by the low thermal conductivity, similar to the case using ingot. Transmission electron microscopy observations of the microstructures suggest that the lower thermal conductivity is mainly due to the increased phonon scattering from the high density grain boundaries and defects. The performance of thermoelectric materials is determined by its dimensionless figure-of-merit (ZT) which needs to be optimized within a specific temperature range for a desired device performance. Hence, we show that by varying the Bi/Sb ratio, the peak ZT can be shifted to a higher or lower temperature for power generation applications or a cooling mode operation. A peak ZT of about 1.3 is achieved from a Bi0.4Sb1.6Te3 composition which is highest among the different compositions. These nanostructured bulk samples have a significantly low lattice thermal conductivity compared to the bulk samples due to the increased phonon scattering in the grain boundaries and defects. This study shows that Bi0.5Sb1.5Te3 may potentially perform better for cooling devices, while Bi0.3Sb1.7Te3 should be able to show better power generation efficiency. Several issues related to accurate measurement of thermoelectric properties were identified and many of them were solved during my studies and these are discussed in this thesis. With the data we obtained, it is clear that nanopowder-based thermoelectric materials hold significant promise. Therefore, a review of synthesis of nanostructured materials by solution-based methods, including a hydrothermal process for the Bi2Te3, Bi2Se3, and Bi2Te2.25Se0.75 nanoparticles, a solvothermal route for Sb2Te3 nanostructures, and a polyol process for the preparation of Bi nanostructures is presented in this dissertation. These new nanostructures may find applications in enhancing the thermoelectric performance. Although small sized and well dispersed nanopowders of various thermoelectric materials could be prepared by a solution method in large scale, contamination and partial oxidation are always big challenges in a chemical approach. Hence, a high energy ball milling technique to prepare thermoelectric nanopowders in large scale and without major contamination is still found to be more efficient and preferred. / Thesis (PhD) — Boston College, 2009. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

Dans la critique littéraire française des années 1950-1960, certains éléments apparaissent comme des évidences. Malgré les différences des méthodes, une idée sous-tendait toutes les lectures : il y aurait, dans les textes, des significations cachées qu’une interprétation devrait révéler. Dans les travaux des trois auteurs étudiés (Charles Mauron, Lucien Goldmann et Roland Barthes), on peut repérer des images qui traversent leurs œuvres et qui sont liées à leurs conceptions de l’objet littéraire. Or, ce qui est intéressant dans leur critique, c’est qu’il est impossible de trouver des éléments qui décrivent les textes qui ne soient imaginaires : en suivant le fil des interprétations de ces auteurs, il n’y a pas de moment où l’image cesse d’agir, comme si le propre du texte se dérobait à chaque fois sous le travestissement d’une autre image.Ces images montrent que la critique littéraire de l’époque étudiée accomplissait deux gestes, proches de deux figures de langage. La tautologie est ce qui ne réussit à établir un rapport de l’objet qu’avec lui-même. Le paradoxe fait le mouvement contraire, puisqu’il repose sur l’idée que les différences doivent être authentiques.Or, ce que l’imaginaire des auteurs donne à voir, c’est une certaine notion de la littérature. Leurs images témoignent de la construction de la littérature comme une pratique discursive marginale : ce qui intéresse les auteurs, c’est de voir ces textes comme un acte de résistance, capable d’utiliser un langage qui défie les usages « normaux » de la langue. Mais, paradoxalement, ils tendent à naturaliser cette position marginale et légitimer la place centrale occupée par les sciences et par la philosophie. / In French literary critique of the years 1950-1960, certain elements were seen as evidences. Despite the differences between the methods the authors used, one idea was always present: for them, the texts concealed hidden meanings that their analyses were meant to reveal. In the works of the three authors we chose to study (Charles Mauron, Lucien Goldmann and Roland Barthes), it is possible to find images that are related to a certain conception of literature. It is interesting to note that in their methods, it is impossible to find definitions of the text that are not touched by an imaginary activity. Reading the authors, we realise that images are everywhere, as if the text itself constantly eluded the analysis.The images show that the literary critique of the time performed two different gestures, that correspond to two figures of speech. Tautology is the figure that establishes that an object can only be defined by itself. Paradox does the exact opposite, stating that only in difference can we find its identity.By analysing the authors’ imaginary, one can reconstruct a certain idea of literature. Their images show literature as a marginal discourse: their interest in literary texts lies in the fact that they can resist the “normal” usage of language. But, paradoxically, this way of looking at them tends to naturalise their marginal position and thus legitimate the privilege accorded to science and philosophy as the standard form of expression.

O trabalho apresenta algumas das iniciativas para a retomada da máscara no teatro moderno. No amplo quadro da primeira metade do século XX, escolhemos quatro principais artistas que abordaram esse objeto: Gordon Craig, Meyerhold, Jacques Copeau e Jacques Lecoq. Nestes a máscara não é apenas mais um elemento colocado em cena, mas também um princípio organizador da teatralidade que almejam. Através de seus trabalhos analisamos algumas características da máscara que podem ser reelaboradas no teatro contemporâneo. Em Gordon Craig, abordamos as primeiras proposições dentro do teatro simbolista, além do panorama da máscara no início do século XX; através de Meyerhold, pudemos traçar os elementos grotescos contidos na máscara; com Jacques Copeau, questionamos os conceitos de caráter e de tipo e, através da pedagogia de Jacques Lecoq, pudemos analisar o trabalho da máscara como signo representativo. A partir dos elementos abordados, apontamos uma proposição de trabalho com a máscara que procura aproximá-la do conceito de figura. / This study presents some of the initiatives to reinstate the mask in modern theatre. In the vast spectrum of the first half of the Twentieth Century, I chose four key artists who elaborated this object: Gordon Craig, Meyerhold, Jacques Copeau and Jacques Lecoq. In the work of these artists, the mask is not one scenic element among others, but becomes the organizing keystone for the theatricality that they seek. Through their creations we can analyze some of the mask´s features that are being reelaborated in contemporary theatre. In Gordon Craig, we examine initial propositions within the symbolist theatre, placing this in a panorama of the mask at the beginning of the Twentieth Century; with Meyerhold, one can trace the grotesque elements contained in the mask; in Jacques Copeau, the focus moves to the concepts of character and type, and finally, in Jacques Lecoqs pedagogy, one can probe the mask as representational sign. From the foregoing elements, we outline an operational proposal which aims to approximate the mask to the concept of figure.

Pour résoudre un problème de mathématiques ou comprendre une démonstration, une figure bien choisie est parfois d’un grand secours. Ce fait souvent remarqué peut être vu comme un cas particulier d’un phénomène plus général. Utiliser une figure plutôt que des phrases, reformuler un problème sous la forme d’une équation, employer telles notations plutôt que telles autres : dans tous ces cas, en un sens, on ne fait que représenter sous une nouvelle forme ce qu’on sait déjà, et pourtant, cela peut permettre d’avancer. Comment est-ce possible ? Pour répondre à cette question, la première partie de cette thèse étudie ce qu’apporte un changement notationnel précis introduit par Leibniz à la fin du XVIIe siècle. La suite de ce travail analyse, et confronte à l’exemple précédent, plusieurs manières de penser les différences représentationnelles proposées dans la littérature philosophique récente. Herbert Simon, étudié dans la deuxième partie, s’appuie sur le modèle informatique des structures de données : deux représentations peuvent être « informationnellement » équivalentes, mais « computationnellement » différentes. Les logiciens Barwise et Etchemendy, étudiés dans la troisième partie, cherchent à élargir les concepts de la logique mathématique (en particulier ceux de syntaxe et de sémantique) aux diagrammes et figures. Enfin, certains philosophes des mathématiques contemporains, comme Kenneth Manders, remettent en cause la notion même de représentation, en soutenant qu’elle n’est pas éclairante pour comprendre l’usage de figures, formules ou autres supports externes en mathématiques. C’est à ces critiques qu’est consacrée la quatrième et dernière partie. / When solving a mathematical problem or reading a proof, drawing a well-chosen diagram may be very helpful. This well-known fact can be seen as an instance of a more general phenomenon. Using a diagram rather than sentences, reformulating a problem as an equation, choosing a particular notation rather than others : in all these cases, in a sense, we are only representing in a new form what we already knew; and yet, it can help us make progress. How is this possible? To address this question, the first part of this thesis explores the benefits afforded by a specific notational change introduced by Leibniz in the late seventeenth-century. The rest of this work analyses, and puts to the test of the preceding case study, several ways of understanding representational differences which have been put forward in the recent philosophical literature. Herbert Simon, studied in the second part, relies on a comparison with the notion of data structures in computer science: two representations, he writes, can be “informationally” equivalent yet “computationnally” different. The logicians Barwise and Etchemendy, studied in the third part, try to broaden the concepts of mathematical logic (in particular those of syntax and semantics) to cover diagrams and figures. Finally, some contemporary philosophers of mathematics, for instance Ken Manders, argue that the notion of representation itself is not helpful to understand the use of diagrams, formulas or other external reasoning tools in mathematics. Such arguments are the focus of the fourth (and last) part.

No conjunto da vasta obra de Cabral, em seus quase 50 anos de ateliê, é incontornável o protagonismo da linha, não apenas sob o domínio mais evidente do desenho, mas também em sua pintura e até mesmo em sua escultura. A linha é dotada de uma complexidade extraordinária em suas criações. Buscando apresentar a relação tensiva que a linha desse artista estabelece com a figura, esta pesquisa demonstra, num recorte que perpassa desde grafismos mais recentes até desenhos dos anos de 1970, diversas estratégias encontradas pelo artista para a criação de novos modos de existência da linha, especialmente em sua coextensividade agonística com a figura. Para isso, a pesquisa mobiliza as noções lyotardianas de espaço da significação e espaço do sentido, em suas intersecções conflitivas entre o ler e o ver. Noções que se desdobram na busca de abordar o grafismo a partir do olho que toca (olhar háptico), ou seja, privilegiar o espaço plástico em seu compromisso com o inarticulado, no contraponto ao olho que olha (olhar que lê), como espaço privilegiado do processo de semantização, zona por excelência do discurso. Pode-se dizer que a intenção deste trabalho é a de se constituir como um salto da letra sobre a linha, num embate do qual o traçado de Cabral possa sair ainda mais fecundo de enigma. / Along the vast work of Cabral, in his nearly 50 years of study, the protagonism of the line is undeniable, not only in the drawings as his most evident mastery, but also in his paintings and even sculptures. The line holds an extraordinary complexity in his creations. Aiming at presenting the tense relationship this artist establishes between the line and the figure, this research demonstrates, with a selection from the drawings of the 1970´s until the most recent graphisms, several strategies used by the artist in the creation of new ways for the existence of the line, especially in its agonistic coextensivity with the figure. Therefore, this research mobilizes concepts as the Lyotardian spaces of significance and meaning, in their conflicting intersections between reading and seeing. Such concepts unfold the search for approaching the graphism through the eye that touches (haptic sight), i.e., privileging the plastic space in its commitment with the articulate, as opposite to the eye that sees (reading sight), as a privileged space in the process of semantization, field of discourse par excellence. The main purpose of this investigation is to take a leap from the letter to the line, in a conflict with which Cabral´s tracing can be even more fruitful of enigma.

The dissertation examines the appearance and meanings of corporeal anomaly in the arts of Postclassic Mexico (AD 900–1521). Drawing specifically upon those categories of the human or divine body that are regularly termed aberrant, grotesque, or otherwise “deformed” by scholars of Mesoamerican art, the images discussed here include dwarfs, hunchbacks, twins, animal-human hybrids, disfigured deities, and disembodied limbs, among others. While similarly distinctive images can be identified among earlier Mesoamerican artistic traditions, the variety of idiosyncratic bodies that pervade the arts of the Postclassic period, in addition to the breadth of available historical sources, make it the ideal lens through which to analyze many of the most fundamental issues of indigenous Mexican visual culture. Relative to Classic Maya art, a tradition of naturalism and linear elegance greatly resembling that of early modern European painting and sculpture, the art of the ancient Mixtecs, Toltecs, and Nahuas (Aztecs) is sometimes perceived as rigid, laconic, and hulking—even brutish—by comparison. Featuring complex figural abstractions and esoteric symbolism, these later traditions are further distinguished by the specificity of their physical deformations, including twisted faces, palsied limbs, contorted spines, extra appendages, and other unnatural anatomies. Consequently, Postclassic art offers an inventory of difference that is unique not only among Mesoamerican art but among Western traditions as well, making it doubly challenging to interpret its motivations and significance. However, by analyzing the role of such extraordinary bodies within the broader anthropocentric worldviews of ancient Mesoamerica, this study offers useful strategies for unpacking the complex religious, political, and formal motivations that govern much of Postclassic visual culture. As I argue, extraordinary bodies share a common identity as transformational characters occupying specifically transitory states. As shape-shifters, gatekeepers, divine conduits, and shepherds, it is in the liminal regions of existence—the “betwixt and between” of reality and myth—where such figures live and serve as the custodians of heaven and earth. With tremendous regularity, their irregular forms indicate and define the various “borderlands” of Mesoamerican ideology, from the hinterlands of the urban center to the margins and gutters of hand-painted books. In short, a distinctly Postclassic notion of physical deformation stands at the threshold between creation and dissolution, center and periphery, life and death.

O corpo no cinema está associado a uma ausência. A imagem apresenta um ser humano filmado em outro espaço, outro tempo. O contraste evidente é com o teatro, a dança e a performance, artes nas quais o espectador geralmente está diante de um corpo físico. Surge, então, um questionamento: seria possível, e em que termos, falar de uma materialidade da figura humana cinematográfica? A tese esboça uma resposta ao investigar os modos de presença do corpo, com ênfase em sua forma plástica, seu desejo e sua dimensão coletiva. O debate tem como eixo filmes de Philippe Grandrieux, Tsai Ming-liang, João Pedro Rodrigues, Claire Denis e Pedro Costa. A obra destes realizadores é discutida em cotejo com um heterogêneo repertório iconográfico, sobretudo fílmico e pictórico. A hipótese defendida é a de que a gênese, o significado e a pregnância da figura humana são dependentes de um tipo de circularidade manifesta na imagem cinematográfica, seja por sua natureza plástica, seja pela rede de interação entre corpos, seres inanimados e espaços. / The body in cinema refers to an absence. The image presents a human being filmed in another time, another place. The difference is remarkable in the face of theater, dance and performance, arts in which the spectator is usually in the presence of a physical body. The question that arises is: how it would be possible to speak of a materiality of the cinematographic human figure? In order to answer this question, the thesis investigates modes of body\'s presence, highlighting its plastic shape, desires and collective dimension. The debate is made from films of Philippe Grandrieux, Tsai Ming-liang, João Pedro Rodrigues, Claire Denis and Pedro Costa. The work of these directors is discussed in comparison with an iconographic repertory, especially film and pictorial. The hypothesis defended is that the genesis, meaning and impregnation of the human figure are dependent on a kind of circularity manifest in the cinematographic image by the plasticity or by the interaction between bodies, inanimate beings and spaces.

Na presente Dissertação investigamos como a configuração do narrador em Abdias formaliza, literariamente, a figura do intelectual brasileiro mediano dos anos 1930. Desse modo, propomos a leitura analítica do romance de Cyro dos Anjos numa chave que leve em conta a relação entre a matéria ficcional e os elementos sociais e culturais que ali estão representados. / This dissertation investigates how the configuration of the narrator of Abdias formalaises, literarily, the figure of the brazilian middle-class intelectual of the 1930\'s. In this sense, it proposes an analytical analyses of Cyro dos Anjos\' novel in a perspective that takes into consideration the relation between the fiction and the social and cultural elements that are there represented.

Cette thèse se propose d’étudier la difficulté de l’estimation de la distance dans le cadre de la géométrie de l’espace visuel. En philosophie de la perception, cette thèse est d'abord discutée au plan épistémologique : comment savoir que cette distance n'est pas connue ou connaissable, quoique perçue et discutée. Les travaux de Berkeley nous servent de point de départ et fixent un cadre spéculatif, puisque Berkeley soutient en effet que le jugement porté sur la distance résulte entièrement de l'expérience, quoique cette distance ne puisse être vue phénoménalement. La thèse se propose d'examiner une question essentielle supportée par cette alternative centrale mais au plan ontologique cette fois : comme déterminer de quel type est la distance : est-elle inconsciemment visible ? tangible ? ou visible et tangible à la fois ? Peut-elle être une entité assignable dans un espace hyperbolique, ou sphérique, un espace strictement euclidien, ou hyperbolique et sphérique en même temps qu'euclidien ? Pour appuyer notre propos et notre recherche nous mettrons à l’épreuve différents textes et expériences en passant de Berkeley à I. Rock ou de T. Reid à M. Wagner. Notre but aura été d'explorer les limites argumentatives et de montrer ce qui est impliqué par ces différentes appréciations et assignations de la distance dans tel ou tel espace déterminé. A chaque fois s'affrontent la géométrie de l’espace visuel et l’optique physiologique, mais au sein d'un même débat de fond qui consiste à savoir comment définir philosophiquement l’estimation de la distance ? / This thesis examines the difficulties in estimating the geometrical distance of visual space. Submitted in the field of Philosophy of Perception, this thesis is first discussed from an epistemological standpoint: how does one know that this distance is unknown or unknowable despite being perceived and discussed. The various works of Berkeley serve as a point of depart and establish a speculative framework as Berkeley held that judgment of distance results entirely from experience despite the fact that this distance cannot be seen in a phenomenal way. This thesis examines an essential question supported by this central problem, this time from an ontological position: how is the type of distance to be determined: is it unconsciously visible?tangible? or both visible and tangible at the same time? Can it be categorized in a hyperbolic space, or spherical space, or a strictly Euclidean space, or hyperbolic and spherical at the same time as Euclidean? In support of the thesis and research, various texts and experiences have been examined and contrasted, including those of Berkeley and I. Rock as well as T. Reid and M. Wagner. The goal has been to explore the limits of argumentation and to show what is implicated by these different accounts and assignment of distance in one, versus another, determined space; additionally studying subjects including the experience of the alleys or the so-called the moon illusion, which appeared to be demonstrative examples. In each instance, geometry of visual space and physiological optics confront one another, but at the center of this same fundamental debate is the question of how to define the estimation of distance philosophically?

Apresento um conjunto de figuras - construídas através do desenho, fotografia e gravura- que movem um imaginário de seres e lugares, em trânsito entre o olhar, a memória e o sonho. A forma é proposta em sua materialidade e em correspondência a seus referentes. O enfrentamento de questões técnicas e poéticas está presente necessariamente na realização de cada trabalho e no trânsito entre eles. Da necessidade de invenção das figuras operam o entendimento e as ações em sua construção. O estudo e experimentação dos meios empregados no trabalho constituem-se nesse escopo. Proponho que toda manifestação se singularize e abra-se ao cotejamento, no tempo, entre diversas manifestações. Nesse sentido, permeiam-se as figuras, os meios construtivos e seu imaginário. Imaginar e figurar como sentimento e ação em si e no mundo. / I present a body of artwork - build through drawing, photography and printmaking -that move an imagery of beings and places in transit between the perception, the memory and the dream. The form is proposed in its materiality and in correlation to its referents. The confrontation between technical and poetic matters is necessarily present in the making of each work and the movement among them. It is from the need for the invention of each piece of work that the understanding and the actions through the construction work. The study and experimentation with the media applied in the process are within the scope of this work. I propose that each manifestation is singled out and then cross analyzed, in time, with the other manifestations. This way each work permeates imagination and media. Imagining and figuring as feeling and action in itself and the world.