128 resultados para Labyrinth


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A turn towards documentary modes of practice amongst contemporary fine art video and filmmakers towards the end of the 20th Century, led to moving image works that represent current social realities. This drew some comparisons of these forms of art to journalism and industrial documentary. The practical research is embodied in a single screen film that responds to recent political and ecological realities in Spain. These include the mass demonstrations that led to the occupation of Madrid’s Plaza del Sol and Spain’s in 2011 and largest recorded forest fires that spread through Andalusia in August of the following year. The film, titled Spanish Labyrinth, South from Granada, is a response to these events and also relates to political avant-garde film of the 1930’s by re-tracing a journey undertaken by three revolutionary filmmakers, Yves Allegret, René Naville and Eli Lotar, in 1931. The theoretical research for this project establishes an historical root of artists’ film that responds to current social realities, in contrast to news media, in the Soviet and European avant-garde movements of the 1920s and 1930s. The main aim of this method is to argue the status of the works that I identify, both avant-garde and contemporary, as a form of art that preceded a Griersonian definition of documentary film.

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The OED reminds us as surely as Ovid that a labyrinth is a “structure consisting of a number of intercommunicating passages arranged in bewildering complexity, through which it is it difficult or impossible to find one’s way without guidance”. Both Shaun Tan’s The Arrival (2006) and Matt Ottley’s Requiem for a Beast: A Work for Image, Word and Music (2007) mark a kind of labyrinthine watershed in Australian children’s literature. Deploying complex, intercommunicating logics of story and literacy, these books make high demands of their reader but also offer guidance for the successful navigation of their stories; for their protagonists as surely as for readers. That the shared logic of navigation in each book is literacy as privileged form of meaning-making is not surprising in the sense that within “a culture deeply invested in myths of individualism and self-sufficiency, it is easy to see why literacy is glorified as an attribute of individual control and achievement” (Williams and Zenger 166). The extent to which these books might be read as exemplifying desired norms of contemporary Australian culture seems to be affirmed by the fact of Tan and Ottley winning the Australian “Picture Book of the Year” prize awarded by the Children’s Book Council of Australia in 2007 and 2008 respectively. However, taking its cue from Ottley’s explicit intertextual use of the myth of Theseus and from Tan’s visual rhetoric of lostness and displacement, this paper reads these texts’ engagement with tropes of “literacy” in order to consider the ways in which norms of gender and culture seemingly circulated within these texts might be undermined by constructions of “nation” itself as a labyrinth that can only partly be negotiated by a literate subject. In doing so, I argue that these picture books, to varying degrees, reveal a perpetuation of the “literacy myth” (Graff 12) as a discourse of safety and agency but simultaneously bear traces of Ariadne’s story, wherein literacy alone is insufficient for safe navigation of the labyrinth of culture.

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The inner ear originates from an ectodermal thickening called the otic placode. The otic placode invaginates and closes to an otic vesicle, the otocyst. The otocyst epithelium undergoes morphogenetic changes and cell differentiation, leading to the formation of the labyrinth-like mature inner ear. Epithelial-mesenchymal interactions control inner ear morphogenesis, but the modes and molecules are largely unresolved. The expressions of negative cell cycle regulators in the epithelium of the early-developing inner ear have also not been elucidated. The mature inner ear comprises the hearing (cochlea) and balance (vestibular) organs that contain the nonsensory and sensory cells. In mammals, the inner ear sensory cells, called hair cells, exit the cell cycle during embryogenesis and are mitotically quiescent during late-embryonic differentiation stages and postnatally. The mechanisms that maintain this hair cell quiescense are largely unresolved. In this work I examined 1) the epithelial-mesenchymal interactions involved in inner ear morphogenesis, 2) expression of negative cell cycle regulators in the epithelium of the early developing inner ear and 3) the molecular mechanisms that maintain the postmitotic state of inner ear sensory cells. We observed that during otocyst stages, epithelial fibroblast growth factor 9 (Fgf9) communicates with the surrounding mesenchyme, where its receptors are expressed. Fgf9 inactivation leads to reduced proliferation of the surrounding vestibular mesenchyme and to the absence of semicircular canals. Semicircular canal development is blocked, since fusion plates do not form. These results show that the mesenchyme directs fusion plate formation and give direct evidence for the existence of reciprocal epithelial-mesenchymal interactions in the developing inner ear. Cyclin-dependent kinase inhibitors (CKIs) are negative regulators of proliferation. We show that the members of the Cip/Kip family of CKIs (p21Cip1, p27Kip1 and p57Kip2) are expressed in the early-developing inner ear. Our expression data suggest that CKIs divide the otic epithelium into proliferative and nonproliferative compartments that may underlie shaping of the otocyst. At later stages, CKIs regulate proliferation of the vestibular appendages, and this may regulate their continual growth. In addition to restricting proliferation, CKIs may play a role in regional differentiation of various epithelial cells. Differentiating and adult inner ear hair cells are postmitotic and do not proliferate in response to serum or mitogenic growth factors. In our study, we show that this is the result of the activity of negative cell cycle regulators. Based on expression profiles, we first focused on the retinoblastoma (Rb) gene, which functions downstream of the CKIs. Analysis of the inner ear phenotype of Rb mutant mice show, that the retinoblastoma protein regulates the postmitotic state of hair cells. Rb inactivation leads to hyperplasia of vestibular and cochlear sensory epithelia that is a result of abnormal cell cycle entry of differentiated hair cells and of delayed cell cycle exit of the hair cell precursor cells. In addition, we show that p21Cip1 and p19Ink4d cooperate in maintaining the postmitotic state of postnatal auditory hair cells. Whereas inactivation of p19Ink4d alone leads to low-level S-phase entry (Chen et al., 2003) and p21Cip1 null mutant mice have a normal inner ear phenotype, codeletion of p19Ink4d and p21Cip1 triggers high-level S-phase entry of auditory hair cells during early postnatal life, which leads to supernumerary hair cells. The ectopic hair cells undergo apoptosis in all of the mutant mice studied, DNA damage being the immediate cause of this death. These findings demonstrate that the maintenance of the postmitotic state of hair cells is regulated by Rb and several CKIs, and that these cell cycle regulators are critical for the lifelong survival of hair cells. These data have implications for the future design of therapies to induce hair cell regrowth.

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The continuous production of blood cells, a process termed hematopoiesis, is sustained throughout the lifetime of an individual by a relatively small population of cells known as hematopoietic stem cells (HSCs). HSCs are unique cells characterized by their ability to self-renew and give rise to all types of mature blood cells. Given their high proliferative potential, HSCs need to be tightly regulated on the cellular and molecular levels or could otherwise turn malignant. On the other hand, the tight regulatory control of HSC function also translates into difficulties in culturing and expanding HSCs in vitro. In fact, it is currently not possible to maintain or expand HSCs ex vivo without rapid loss of self-renewal. Increased knowledge of the unique features of important HSC niches and of key transcriptional regulatory programs that govern HSC behavior is thus needed. Additional insight in the mechanisms of stem cell formation could enable us to recapitulate the processes of HSC formation and self-renewal/expansion ex vivo with the ultimate goal of creating an unlimited supply of HSCs from e.g. human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPS) to be used in therapy. We thus asked: How are hematopoietic stem cells formed and in what cellular niches does this happen (Papers I, II)? What are the molecular mechanisms that govern hematopoietic stem cell development and differentiation (Papers III, IV)? Importantly, we could show that placenta is a major fetal hematopoietic niche that harbors a large number of HSCs during midgestation (Paper I)(Gekas et al., 2005). In order to address whether the HSCs found in placenta were formed there we utilized the Runx1-LacZ knock-in and Ncx1 knockout mouse models (Paper II). Importantly, we could show that HSCs emerge de novo in the placental vasculature in the absence of circulation (Rhodes et al., 2008). Furthermore, we could identify defined microenvironmental niches within the placenta with distinct roles in hematopoiesis: the large vessels of the chorioallantoic mesenchyme serve as sites of HSC generation whereas the placental labyrinth is a niche supporting HSC expansion (Rhodes et al., 2008). Overall, these studies illustrate the importance of distinct milieus in the emergence and subsequent maturation of HSCs. To ensure proper function of HSCs several regulatory mechanisms are in place. The microenvironment in which HSCs reside provides soluble factors and cell-cell interactions. In the cell-nucleus, these cell-extrinsic cues are interpreted in the context of cell-intrinsic developmental programs which are governed by transcription factors. An essential transcription factor for initiation of hematopoiesis is Scl/Tal1 (stem cell leukemia gene/T-cell acute leukemia gene 1). Loss of Scl results in early embryonic death and total lack of all blood cells, yet deactivation of Scl in the adult does not affect HSC function (Mikkola et al., 2003b. In order to define the temporal window of Scl requirement during fetal hematopoietic development, we deactivated Scl in all hematopoietic lineages shortly after hematopoietic specification in the embryo . Interestingly, maturation, expansion and function of fetal HSCs was unaffected, and, as in the adult, red blood cell and platelet differentiation was impaired (Paper III)(Schlaeger et al., 2005). These findings highlight that, once specified, the hematopoietic fate is stable even in the absence of Scl and is maintained through mechanisms that are distinct from those required for the initial fate choice. As the critical downstream targets of Scl remain unknown, we sought to identify and characterize target genes of Scl (Paper IV). We could identify transcription factor Mef2C (myocyte enhancer factor 2 C) as a novel direct target gene of Scl specifically in the megakaryocyte lineage which largely explains the megakaryocyte defect observed in Scl deficient mice. In addition, we observed an Scl-independent requirement of Mef2C in the B-cell compartment, as loss of Mef2C leads to accelerated B-cell aging (Gekas et al. Submitted). Taken together, these studies identify key extracellular microenvironments and intracellular transcriptional regulators that dictate different stages of HSC development, from emergence to lineage choice to aging.

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- Background/Aims Liver sinusoidal endothelial cell (LSEC) fenestrae are membrane-bound pores that are grouped in sieve plates and act as a bidirectional guardian in regulating transendothelial liver transport. The high permeability of the endothelial lining is explained by the presence of fenestrae and by various membrane-bound transport vesicles. The question as to whether fenestrae relate to other transport compartments remains unclear and has been debated since their discovery almost 40 years ago. - Methods In this study, novel insights concerning the three-dimensional (3D) organization of the fenestrated cytoplasm were built on transmission electron tomographical observations on isolated and cultured whole-mount LSECs. Classical transmission electron microscopy and atomic force microscopy imaging was performed to accumulate cross-correlative structural evidence. - Results and Conclusions The data presented here indicate that different arrangements of fenestrae have to be considered: i.e. open fenestrae that lack any structural obstruction mainly located in the thin peripheral cytoplasm and complexes of multifolded fenestrae organized as labyrinth-like structures that are found in the proximity of the perinuclear area. Fenestrae in labyrinths constitute about one-third of the total LSEC porosity. The 3D reconstructions also revealed that coated pits and small membrane-bound vesicles are exclusively interspersed in the non-fenestrated cytoplasmic arms.

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The zinc-finger transcription factors GATA2 and GATA3 in vertebrates belong to the six-member family that are essential regulators in the development of various organs. The aim of this study was to gain new information of the roles of GATA2 and GATA3 in inner ear morphogenesis and of the function of GATA2 in neuronal fate specification in the midbrain using genetically modified mouse and chicken embryos as models. A century ago the stepwise process of inner ear epithelial morphogenesis was described, but the molecular players regulating the cellular differentiation of the otic epithelium are still not fully resolved. This study provided novel data on GATA factor roles in several developmental processes during otic development. The expression analysis in chicken suggested that GATA2 and GATA3 possess redundant roles during otic cup and vesicle formation, but complementary cell-type specific functions during vestibular and cochlear morphogenesis. The comparative analysis between mouse and chicken Gata2 and Gata3 expression revealed many conserved aspects, especially during later stages of inner ear development, while the expression was more divergent at early stages. Namely, expression of both Gata genes was initiated earlier in chicken than mouse otic epithelium relative to the morphogenetic stages. Likewise, important differences concerning Gata3 expression in the otic cup epithelium were detected between mouse and chicken, suggesting that distinct molecular mechanisms regulate otic vesicle closure in different vertebrate species. Temporally distinct Gata2 and Gata3 expression was also found during otic ganglion formation in mouse and chicken. Targeted inactivation of Gata3 in mouse embryos caused aberrant morphology of the otic vesicle that in severe cases was disrupted into two parts, a dorsal and a ventral vesicle. Detailed analyses of Gata3 mutant embryos unveiled a crucial role for GATA3 in the initial inner ear morphogenetic event, the invagination of the otic placode. A large-scale comparative expression analysis suggested that GATA3 could control cell adhesion and motility in otic epithelium, which could be important for early morphogenesis. GATA3 was also identified as the first factor to directly regulate Fgf10 expression in the otic epithelium and could thus influence the development of the semicircular ducts. Despite the serious problems in the early inner ear development, the otic sensory fate establishment and some vestibular hair cell differentiation was observable in pharmacologically rescued Gata3-/- embryos. Cochlear sensory differentiation was, however, completely blocked so that no auditory hair cells were detected. In contrast to the early morphogenetic phenotype in Gata3-/- mutants, conditional inactivation of Gata2 in mouse embryos resulted in a relatively late growth defect of the three semicircular ducts. GATA2 was required for the proliferation of the vestibular nonsensory epithelium to support growing of the three ducts. Concurrently, with the role in epithelial semicircular ducts, GATA2 was also required for the mesenchymal cell clearance from the vestibular perilymphatic region between the membranous labyrinth and bony capsule. The gamma-aminobutyric acid-secreting (GABAergic) neurons in the midbrain are clinically relevant since they contribute to fear, anxiety, and addiction regulation. The molecular mechanisms regulating the GABAergic neuronal development, however, are largely unknown. Using tissue-specific mutagenesis in mice, GATA2 was characterized as a critical determinant of the GABAergic neuronal fate in the midbrain. In Gata2-deficient mouse midbrain, GABAergic neurons were not produced, instead the Gata2-mutant cells acquired a glutamatergic neuronal phenotype. Gain-of-function experiments in chicken also revealed that GATA2 was sufficient to induce GABAergic differentiation in the midbrain.

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Genetic algorithms provide an alternative to traditional optimization techniques by using directed random searches to locate optimal solutions in complex landscapes. We introduce the art and science of genetic algorithms and survey current issues in GA theory and practice. We do not present a detailed study, instead, we offer a quick guide into the labyrinth of GA research. First, we draw the analogy between genetic algorithms and the search processes in nature. Then we describe the genetic algorithm that Holland introduced in 1975 and the workings of GAs. After a survey of techniques proposed as improvements to Holland's GA and of some radically different approaches, we survey the advances in GA theory related to modeling, dynamics, and deception

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Eutectic growth is an interesting example for exploring the topic of pattern-formation in multi-phase systems, where the growth of the phases is coupled with the diffusive transport of one or more components in the melt. While in the case of binary alloys, the number of possibilities are limited (lamellae, rods, labyrinth etc.), their number rapidly increases with the number of components and phases. In this paper, we will investigate pattern formation during three-phase eutectic solidification using a state-of-the art phase-field method based on the grand-canonical density formulation. The major aim of the study is to highlight the role of two properties, which are the volume fraction of the solid phases and the solid-liquid interfacial energies, in the self-organization of the solid phases during directional growth. Thereafter, we will show representative phase-field simulations of a micro-structure in a real alloy (Ag-Al-Cu) using an asymmetric phase diagram as well as interfacial properties.

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Resumen: La expresión “Laberinto del continuo” se debe a Leibniz. Sin embargo, Leibniz carecía de los instrumentos conceptuales necesarios para tratar el tema adecuadamente. La teoría de conjuntos de Cantor hizo posible resolver el problema del continuo de modo satisfactorio desde el punto de vista conjuntista. Se debe atribuir a R. Dedekind una resolución más cabal del problema. No obstante, el autor sostiene que la concepción de éste último tampoco pone de manifiesto todos los aspectos involucrados en el continuo.

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O envelhecimento populacional no Brasil sobreleva a necessidade de organização de serviços de saúde, sendo a estimulação do autocuidado uma estratégia privilegiada para orientar programas de promoção da saúde para pessoas idosas. Face à busca das mais variadas formas de viver bem, abrem-se fronteiras possibilitando o surgimento de modelos de envelhecimento saudável. Partindo do pressuposto de que as pessoas possuem uma dimensão imaginativa no acrescentar qualidade aos anos de vida, delimitou-se como objeto de estudo o imaginário de um grupo da terceira idade na construção das ações de autocuidado. Objetivos: descrever a poética sobre as ações de autocuidado construídas por um grupo de pessoas idosas; e analisar os significados (conceitos/confetos) atribuídos por essas pessoas ao envelhecer. Utilizou-se como marco referencial a Teoria de Promoção da Saúde de Nola Pender. Trata-se de pesquisa descritiva, qualitativa, considerando o paradigma naturalista. Foi aplicado o método sociopoético por meio do dispositivo analítico Grupo Pesquisador, composto por 11 idosos participantes da Unati da Universidade do Estado do Rio de Janeiro, que desenvolveram a investigação no período de outubro a dezembro de 2008, mediante as técnicas de pesquisa: Dinâmica de Corpo como Território Mínimo e a Vivência de Lugares Geomíticos. Foram questões norteadoras do estudo, respectivamente: Como vocês se cuidam para o caminho do bom envelhecer? E Como é o autocuidado para o envelhecer saudável se ele for um lugar geomítico?. Os dados produzidos foram submetidos à análise categorial, dos estudos sociopoéticos. No estudo filosófico, observou-se haver coexistência da autoimagem realista revelando que os idosos estão mais aptos aos desafios da vida, pois seu comportamento é coerente com a ideia que faz de si, além de intenções, aspirações e tendências. O classificatório ressaltou as dicotomias das ações de autocuidado tendo: O Autocuidado através dos Limites e Possibilidades; e Transcender para Experienciar o Dom do Envelhecer; O transversal revelou O Autocuidado como Reconhecimento das Necessidades de Saúde, enquanto no surreal sobrelevam-se Aceitar o Novo para um Renascer Saudável; Perseverança para Conviver com o Envelhecimento; e Procurar Assistência pode Desvelar Temores para a Finitude do Viver. Conclui-se que a compreensão do imaginário dos sujeitos de pesquisa mediada pela teoria de Pender permitiu identificar fatores que influenciam e motivam o autocuidado para comportamentos saudáveis. Assim, o grupo vislumbra para seu futuro uma imagem de envelhecer mais dinâmica, adotando para si próprio um viver mais autônomo, ativo e bem-sucedido. À contribuição do estudo, propõe-se aos enfermeiros a apropriação de conceitos teóricos como forma de traduzir a realidade e demonstrar alternativas viáveis de ações de cuidado/saúde, bem como a utilização das práticas de dinâmicas de criatividade e sensibilidade nas atividades assistenciais.

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Esta pesquisa teve por objetivo compreender como vêm sendo desempenhadas as práticas dos psicólogos que atuam em instituições de referência para atendimentos em casos de alegação de abuso sexual contra a criança. Para este fim, foram analisadas as declarações de dez pais acusados de abusar sexualmente dos filhos, por meio de questionário enviado e recebido por correio eletrônico. Este material permitiu apreender como os pais acusados compreendem a alegação de abuso sexual imputada contra eles e como operam no sentido de provar a inocência. Também foi possível registrar-lhes as impressões, dúvidas e sentimentos eliciados pelas acusações, o que deu subsídio à realização de entrevistas presenciais com psicólogos em etapa posterior. Foram realizadas entrevistas individuais semiestruturadas com cinco psicólogas de cinco instituições diferentes. As informações prestadas permitiram analisar aspectos como a abordagem teórica e os métodos de avaliação psicológica em casos de alegações de abuso sexual contra criança, incluindo uma discussão acerca da ocorrência de falsas denúncias de abuso sexual. A partir dessas informações, foi possível concluir que tais práticas tendem a privilegiar a palavra da criança, esta última, vista, por muitos, como aquela que deverá anunciar e qualificar a denúncia. Nesses termos, os pais são silenciados, enquanto as crianças são colocadas no lugar de responsáveis por decidir questões jurídicas em nome de seus direitos.

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A formação do pensamento social e educacional brasileiro a partir dos estudos sobre as matrizes do ideário autoritário concebido no transcorrer da República Brasileira. O Histórico da Universidade no Brasil e a identificação de uma linhagem de intelectuais, suas filiações político-doutrinárias e que formularam o pensamento social brasileiro, suas visões de mundo diante de um projeto nacional de desenvolvimento. A modernização realizada pelo alto, expressão que resumiu a presença das elites políticas quando pensaram o país, reflexão permanente como princípio e ação política no transcorrer da República Brasileira. O regime civil-militar e a imposição de uma ordem e mentalidade que conduziram o país a mais uma etapa de autoritarismo, seus desdobramentos na legislação educacional que definiram a política de pós-graduação ao final dos anos de 1960. Os anos de 1980, o cenário de transição negociada entre o regime civil-militar e o poder civil num ambiente de forte presença de uma sociedade civil em ascensão pela defesa da democracia. A educação brasileira vista numa perspectiva de um elenco de intelectuais educadores que constituíram um consenso teórico-metodológico pautado num marxismo eclético e determinando um olhar interpretativo diante da escola e dos conceitos de democracia e participação

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Gas turbine engine performance requires effective and reliable internal cooling over the duty cycle of the engine. Life predictions for rotating components subject to the main gas path temperatures are vital. This demands increased precision in the specification of the internal air system flows which provide turbine stator well cooling and sealing. This in turn requires detailed knowledge of the flow rates through rim seals and interstage labyrinth seals. Knowledge of seal movement and clearances at operating temperatures is of great importance when prescribing these flows. A test facility has been developed at the University of Sussex, incorporating a two stage turbine rated at 400 kW with an individual stage pressure ratio of 1.7:1. The mechanical design of the test facility allows internal cooling geometry to be rapidly re-configured, while cooling flow rates of between 0.71 CW, ENT and 1.46 C W, ENT, may be set to allow ingress or egress dominated cavity flows. The main annulus and cavity conditions correspond to in cavity rotational Reynolds numbers of 1.71×106< Reφ <1.93×106. Displacement sensors have been used to establish hot running seal clearances over a range of stator well flow conditions, allowing realistic flow rates to be calculated. Additionally, gas seeding techniques have been developed, where stator well and main annulus flow interactions are evaluated by measuring changes in gas concentration. Experiments have been performed which allow rim seal and re-ingestion flows to be quantified. It will be shown that this work develops the measurement of stator well cooling flows and provides data suitable for the validation of improved thermo-mechanical and CFD codes, beneficial to the engine design process. Copyright © 2011 by Rolls-Royce plc.