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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Un coup de dés : o testamento do espaço mallarmeano

Dick, André Henrique January 2002 (has links)
Tendo como base a idéia de que a Modernidade configura a própria tradição da ruptura, extraída de Octavio Paz, este estudo propõe-se a examinar o poema Un coup de dés, de Stéphane Mallarmé, aproximado-o de alguns poetas e músicos. Realizado no auge da Modernidade, esse poema foi retomado, na segunda metade do século XX, pelo movimento da poesia concreta, produzido no Brasil, como referência para suas teorias, através de sua estrutura espácio-temporal. Seus criadores, Augusto e Haroldo de Campos e Décio Pignatari, também resgataram a visão que Oswald de Andrade, Mário de Andrade e Manuel Bandeira, poetas do Modernismo, tiveram sobre Mallarmé. Assim como o Concretismo demonstrou interesse especial pelo poeta francês, parte da crítica literária estruturalista e pós-estruturalista estudou a revolução empreendida por Un coup de dés como uma extensão da transparência do espaço da escritura, em textos de Jacques Derrida, Roland Barthes, Michel Foucault, Julia Kristeva e Maurice Blanchot. Nesse sentido, Un coup de dés também faz com que seja necessário compor um conjunto teórico sobre a concepção do “acaso” utilizado em sua concepção. Visto desse ângulo, Octavio Paz serve de referência para equacionar diversas questões que o poema suscita, no contexto da Modernidade, inclusive sua relação com a música. Este campo é aberto pela revelação de que Mallarmé queria realizar, em Un coup de dés, um poema ligado intrinsecamente ao universo musical em que estava mergulhado no final do século XIX, à sombra das obras de Wagner, Debussy e Stravinski. A importância que Mallarmé atribuía à música, acompanhada por seu gesto de “acaso crítico”, chamou a atenção de dois músicos do século XX, John Cage e Pierre Boulez: o primeiro trabalhando o acaso de Mallarmé não só em peças musicais, mas também em poemas, compostos a partir da década de 1960 e o segundo, tomando Mallarmé como referência em ensaios e trabalhos. Tal universo musical incide em dois criadores da poesia concreta: Augusto de Campos, tanto em sua série musical Poetamenos quanto em seus poemas visuais feitos durante a fase ortodoxa e posterior à do Concretismo, e Haroldo de Campos, para o qual Mallarmé constitui a representação mais exemplar de seu percurso teórico-crítico e criativo. Mais do que eleger Mallarmé como referência em sua poesia, Haroldo de Campos o configura como o poeta mais relevante para sua noção de escritura da Modernidade. Perseguindo a mesma tradição sincrônica, baseada na concepção de Roman Jakobson, Ezra Pound e T. S. Eliot, escritores-críticos, Haroldo, ao longo de sua trajetória poética, recupera a musicalidade do poeta francês e as formas de articulação com os limites da palavra no espaço da página, eixo nuclear do presente estudo. Pretende-se, pois, demonstrar, nessa investigação, que Un coup de dés, estabelecido seu contato com a música, é produto de um acaso racional e crítico, instigando a exploração da palavra poética. O diálogo da literatura com a música, que os concretos buscar sublinhar através do poema de Mallarmé, é o caminho que este trabalho quer traçar. / Taking as a basis the idea that Modernity configures its own tradition of rupture, extracted from Octavio Paz, this study is going to examine the poem Un coup de dés, by Stephane Mallarmé, approximating him to some poets and musicians. This poem was written in the climax of Modernity and was retaken in the second half of the twentieth century by the concrete poetry trend, which happened in Brazil, as a reference for its theories, through its spatial and temporal structure. Its creators, Augusto e Haroldo de Campos, also reaffirmed the view that Oswald de Andrade, Mário de Andrade and Manuel Bandeira, poets of Modernism, had about Mallarmé. In the same way as ‘Concretism’ showed special interest for the French poet, part of the structuralist and post-structuralist literary criticists studied the revolution presented by Un coup de dés as an extension of the transparency of the writing space in texts by Jacques Derrida, Roland Barthes, Michel Foucault, Julia Kristeva and Maurice Blanchot. In this sense, Un coup de dés also makes it necessary to compose a theoretical ensemble about the conception of “chance” used in its conception. Seen from this angle, Octavio Paz is a reference to counterbalance several questions the poem stirs up, in the context of Modernity, including its relation to music. This area is opened by the revelation that Mallarmé wanted to create, in Un coup de dés, a poem linked intrinsically to the universe of music in which he was immersed at the end of the nineteenth century, in the shadow of Wagner’s, Debussy’s and Stravinski’s works. The importance that Mallarmé attributed to music, accompanied by his gesture of “critical chance”, called the attention of two musicians of the twentieth century John Cage and Pierre Boulez: the first working Mallarmé’s “chance” not only in musical works, but also in poems, composed in the 1960’s, and the second, taking Mallarmé as a reference in essays and works. Such musical universe falls on two creators of concrete poetry: Augusto de Campos not only in his series Poetamenos but also in his visual poems composed during an orthodox phase posterior to Concretism, and Haroldo de Campos, for whom Mallarmé is the most outstanding guide of his theoretical, critical and creative course. More than just electing Mallarmé as a reference in his poetry, Haroldo de Campos, configures him as the most relevant poet for his notion of writing of Modernity. Following the same synchronical tradition, based on the conception of Roman Jakobson, Ezra Pound and T. S. Eliot, critical writers, Haroldo, along his poetic course, recovers the musicality of the French poet and the forms of articulating the nuclear axis of the present study. We intend, then, to demonstrate, in this study, that Un coup de dés establishes its contact with the music, is a product of the rational and critical ‘chance’ leading towards the exploration of the poetical word. The dialogue between literature and music, that the concretes intend to reinforce through Mallarmé’s poem, is the course that this work intends to bring forth.
102

Un coup de dés : o testamento do espaço mallarmeano

Dick, André Henrique January 2002 (has links)
Tendo como base a idéia de que a Modernidade configura a própria tradição da ruptura, extraída de Octavio Paz, este estudo propõe-se a examinar o poema Un coup de dés, de Stéphane Mallarmé, aproximado-o de alguns poetas e músicos. Realizado no auge da Modernidade, esse poema foi retomado, na segunda metade do século XX, pelo movimento da poesia concreta, produzido no Brasil, como referência para suas teorias, através de sua estrutura espácio-temporal. Seus criadores, Augusto e Haroldo de Campos e Décio Pignatari, também resgataram a visão que Oswald de Andrade, Mário de Andrade e Manuel Bandeira, poetas do Modernismo, tiveram sobre Mallarmé. Assim como o Concretismo demonstrou interesse especial pelo poeta francês, parte da crítica literária estruturalista e pós-estruturalista estudou a revolução empreendida por Un coup de dés como uma extensão da transparência do espaço da escritura, em textos de Jacques Derrida, Roland Barthes, Michel Foucault, Julia Kristeva e Maurice Blanchot. Nesse sentido, Un coup de dés também faz com que seja necessário compor um conjunto teórico sobre a concepção do “acaso” utilizado em sua concepção. Visto desse ângulo, Octavio Paz serve de referência para equacionar diversas questões que o poema suscita, no contexto da Modernidade, inclusive sua relação com a música. Este campo é aberto pela revelação de que Mallarmé queria realizar, em Un coup de dés, um poema ligado intrinsecamente ao universo musical em que estava mergulhado no final do século XIX, à sombra das obras de Wagner, Debussy e Stravinski. A importância que Mallarmé atribuía à música, acompanhada por seu gesto de “acaso crítico”, chamou a atenção de dois músicos do século XX, John Cage e Pierre Boulez: o primeiro trabalhando o acaso de Mallarmé não só em peças musicais, mas também em poemas, compostos a partir da década de 1960 e o segundo, tomando Mallarmé como referência em ensaios e trabalhos. Tal universo musical incide em dois criadores da poesia concreta: Augusto de Campos, tanto em sua série musical Poetamenos quanto em seus poemas visuais feitos durante a fase ortodoxa e posterior à do Concretismo, e Haroldo de Campos, para o qual Mallarmé constitui a representação mais exemplar de seu percurso teórico-crítico e criativo. Mais do que eleger Mallarmé como referência em sua poesia, Haroldo de Campos o configura como o poeta mais relevante para sua noção de escritura da Modernidade. Perseguindo a mesma tradição sincrônica, baseada na concepção de Roman Jakobson, Ezra Pound e T. S. Eliot, escritores-críticos, Haroldo, ao longo de sua trajetória poética, recupera a musicalidade do poeta francês e as formas de articulação com os limites da palavra no espaço da página, eixo nuclear do presente estudo. Pretende-se, pois, demonstrar, nessa investigação, que Un coup de dés, estabelecido seu contato com a música, é produto de um acaso racional e crítico, instigando a exploração da palavra poética. O diálogo da literatura com a música, que os concretos buscar sublinhar através do poema de Mallarmé, é o caminho que este trabalho quer traçar. / Taking as a basis the idea that Modernity configures its own tradition of rupture, extracted from Octavio Paz, this study is going to examine the poem Un coup de dés, by Stephane Mallarmé, approximating him to some poets and musicians. This poem was written in the climax of Modernity and was retaken in the second half of the twentieth century by the concrete poetry trend, which happened in Brazil, as a reference for its theories, through its spatial and temporal structure. Its creators, Augusto e Haroldo de Campos, also reaffirmed the view that Oswald de Andrade, Mário de Andrade and Manuel Bandeira, poets of Modernism, had about Mallarmé. In the same way as ‘Concretism’ showed special interest for the French poet, part of the structuralist and post-structuralist literary criticists studied the revolution presented by Un coup de dés as an extension of the transparency of the writing space in texts by Jacques Derrida, Roland Barthes, Michel Foucault, Julia Kristeva and Maurice Blanchot. In this sense, Un coup de dés also makes it necessary to compose a theoretical ensemble about the conception of “chance” used in its conception. Seen from this angle, Octavio Paz is a reference to counterbalance several questions the poem stirs up, in the context of Modernity, including its relation to music. This area is opened by the revelation that Mallarmé wanted to create, in Un coup de dés, a poem linked intrinsically to the universe of music in which he was immersed at the end of the nineteenth century, in the shadow of Wagner’s, Debussy’s and Stravinski’s works. The importance that Mallarmé attributed to music, accompanied by his gesture of “critical chance”, called the attention of two musicians of the twentieth century John Cage and Pierre Boulez: the first working Mallarmé’s “chance” not only in musical works, but also in poems, composed in the 1960’s, and the second, taking Mallarmé as a reference in essays and works. Such musical universe falls on two creators of concrete poetry: Augusto de Campos not only in his series Poetamenos but also in his visual poems composed during an orthodox phase posterior to Concretism, and Haroldo de Campos, for whom Mallarmé is the most outstanding guide of his theoretical, critical and creative course. More than just electing Mallarmé as a reference in his poetry, Haroldo de Campos, configures him as the most relevant poet for his notion of writing of Modernity. Following the same synchronical tradition, based on the conception of Roman Jakobson, Ezra Pound and T. S. Eliot, critical writers, Haroldo, along his poetic course, recovers the musicality of the French poet and the forms of articulating the nuclear axis of the present study. We intend, then, to demonstrate, in this study, that Un coup de dés establishes its contact with the music, is a product of the rational and critical ‘chance’ leading towards the exploration of the poetical word. The dialogue between literature and music, that the concretes intend to reinforce through Mallarmé’s poem, is the course that this work intends to bring forth.
103

Interactions pédagogiques "fortement multimodales" en ligne : le cas de tuteurs en formation / Interactions in online “strongly multimodal” teaching : the case of tutor training

Vincent, Caroline 26 October 2012 (has links)
Les activités interactives en ligne connaissent une utilisation grandissante, notamment dans le domaine de l’enseignement des langues. L’amélioration technique des dispositifs permet en effet aujourd’hui des échanges synchrones à distance avec un locuteur natif.Le tuteur inscrit dans une communication via une plateforme synchrone en ligne doit alors coordonner un ensemble complexe d'opérations à des fins d’apprentissage. Différents modes de communication (textuel, visuel, auditif) sont à sa disposition et il les combine dans son discours. Nous analysons, dans le cadre de cours de français à distance via Skype, quels modes sont utilisés par chacun des quatre tuteurs qui composent notre étude. Nous postulons que les modes sont utilisés différemment par chaque tuteur et nous cherchons donc à savoir dans quelle proportion et avec quel « degré d’investissement » (Develotte, Guichon, Vincent, 2011). Nous cherchons également à comprendre quelles conséquences ces choix d’utilisations des modes ont sur la nature de l’interaction. Nous émettons en effet deux hypothèses. Premièrement, nous pensons que le profil initial des tuteurs (compétences individuelles, expériences professionnelles en présentiel ou à distance, habitude de l’environnement informatique) et le contexte des interactions (perturbations extérieures, problèmes techniques, type de tâche, besoin exprimé des apprenants) ont une influence sur la façon dont le tuteur utilise les modes à disposition.Deuxièmement, nous pensons que les choix d’utilisations influencent la nature de l’interaction et la relation entre tuteurs et apprenants. Nous proposons ainsi une grille d’analyse des interactions multimodales en ligne, afin d’apporter des réponses à nos hypothèses de recherche. / Online interactive activities are increasingly used, notably in the field of language teaching. The technical improvements enable synchronous long distance exchanges with a native speaker. The tutor engaged in a communication via a synchronous online platform must coordinate a complex set of operations for learning purposes. He can combine the different communication modes which are at his disposal (textual, visual and aural). We analyze, in the case of French lessons via Skype, which modes are used by each of the four tutors in our study. We postulate that the modes are differently used by each tutor and we seek to know in what proportion and with which “degree of utilization” (Develotte, Guichon, Vincent, 2011). We also try to understand what consequences the choice of the method has on the nature of the interaction. We present two hypotheses. First, we think that the initial profile of the tutors (individual skills, professional experience with face to face or distance teaching, comfort with the computer environment) and the context of the interactions (exterior perturbations, technical problems, type of task, needs expressed by the learners) have an influence on the way the tutor uses the modes. Secondly, we think that the choices influence the nature of the interaction and the relation between tutors and learners. We propose a grid of analysis of the multimodal online interactions in order to sustain our research hypotheses.
104

A comparative approach to social learning from the bottom up

O'Sullivan, Eóin P. January 2015 (has links)
The aim of this thesis is to examine the cognitive processes of social learning from the bottom up. In the field of comparative psychology, an overemphasis on understanding complex cognitive processes in nonhuman animals (e.g. empathy, imitation), may be detrimental to the study of simpler mechanisms. In this thesis, I report five studies of simple cognitive processes related to social learning. A series of experiments with human children and capuchin monkeys (Sapajus sp.), examined action imitation and identified a possible role for associative learning in the development of this ability. An analysis of observational data from captive capuchins explored a number of lesser-studied social learning phenomena, including behavioural synchrony, the neighbour effect, and group-size effects. The results of this study emphasise the importance of exploring behaviour at a number of levels to appreciate the dynamic nature of social influence. Two final experiments examined social contagion in capuchin monkeys, and highlight the importance of describing the relationship between behaviour and emotion to properly understand more complex social cognition. Together, these studies demonstrate how approaching human and nonhuman behaviour from the bottom up, as well as from the top down, can contribute to a better comparative science of social learning.
105

Un coup de dés : o testamento do espaço mallarmeano

Dick, André Henrique January 2002 (has links)
Tendo como base a idéia de que a Modernidade configura a própria tradição da ruptura, extraída de Octavio Paz, este estudo propõe-se a examinar o poema Un coup de dés, de Stéphane Mallarmé, aproximado-o de alguns poetas e músicos. Realizado no auge da Modernidade, esse poema foi retomado, na segunda metade do século XX, pelo movimento da poesia concreta, produzido no Brasil, como referência para suas teorias, através de sua estrutura espácio-temporal. Seus criadores, Augusto e Haroldo de Campos e Décio Pignatari, também resgataram a visão que Oswald de Andrade, Mário de Andrade e Manuel Bandeira, poetas do Modernismo, tiveram sobre Mallarmé. Assim como o Concretismo demonstrou interesse especial pelo poeta francês, parte da crítica literária estruturalista e pós-estruturalista estudou a revolução empreendida por Un coup de dés como uma extensão da transparência do espaço da escritura, em textos de Jacques Derrida, Roland Barthes, Michel Foucault, Julia Kristeva e Maurice Blanchot. Nesse sentido, Un coup de dés também faz com que seja necessário compor um conjunto teórico sobre a concepção do “acaso” utilizado em sua concepção. Visto desse ângulo, Octavio Paz serve de referência para equacionar diversas questões que o poema suscita, no contexto da Modernidade, inclusive sua relação com a música. Este campo é aberto pela revelação de que Mallarmé queria realizar, em Un coup de dés, um poema ligado intrinsecamente ao universo musical em que estava mergulhado no final do século XIX, à sombra das obras de Wagner, Debussy e Stravinski. A importância que Mallarmé atribuía à música, acompanhada por seu gesto de “acaso crítico”, chamou a atenção de dois músicos do século XX, John Cage e Pierre Boulez: o primeiro trabalhando o acaso de Mallarmé não só em peças musicais, mas também em poemas, compostos a partir da década de 1960 e o segundo, tomando Mallarmé como referência em ensaios e trabalhos. Tal universo musical incide em dois criadores da poesia concreta: Augusto de Campos, tanto em sua série musical Poetamenos quanto em seus poemas visuais feitos durante a fase ortodoxa e posterior à do Concretismo, e Haroldo de Campos, para o qual Mallarmé constitui a representação mais exemplar de seu percurso teórico-crítico e criativo. Mais do que eleger Mallarmé como referência em sua poesia, Haroldo de Campos o configura como o poeta mais relevante para sua noção de escritura da Modernidade. Perseguindo a mesma tradição sincrônica, baseada na concepção de Roman Jakobson, Ezra Pound e T. S. Eliot, escritores-críticos, Haroldo, ao longo de sua trajetória poética, recupera a musicalidade do poeta francês e as formas de articulação com os limites da palavra no espaço da página, eixo nuclear do presente estudo. Pretende-se, pois, demonstrar, nessa investigação, que Un coup de dés, estabelecido seu contato com a música, é produto de um acaso racional e crítico, instigando a exploração da palavra poética. O diálogo da literatura com a música, que os concretos buscar sublinhar através do poema de Mallarmé, é o caminho que este trabalho quer traçar. / Taking as a basis the idea that Modernity configures its own tradition of rupture, extracted from Octavio Paz, this study is going to examine the poem Un coup de dés, by Stephane Mallarmé, approximating him to some poets and musicians. This poem was written in the climax of Modernity and was retaken in the second half of the twentieth century by the concrete poetry trend, which happened in Brazil, as a reference for its theories, through its spatial and temporal structure. Its creators, Augusto e Haroldo de Campos, also reaffirmed the view that Oswald de Andrade, Mário de Andrade and Manuel Bandeira, poets of Modernism, had about Mallarmé. In the same way as ‘Concretism’ showed special interest for the French poet, part of the structuralist and post-structuralist literary criticists studied the revolution presented by Un coup de dés as an extension of the transparency of the writing space in texts by Jacques Derrida, Roland Barthes, Michel Foucault, Julia Kristeva and Maurice Blanchot. In this sense, Un coup de dés also makes it necessary to compose a theoretical ensemble about the conception of “chance” used in its conception. Seen from this angle, Octavio Paz is a reference to counterbalance several questions the poem stirs up, in the context of Modernity, including its relation to music. This area is opened by the revelation that Mallarmé wanted to create, in Un coup de dés, a poem linked intrinsically to the universe of music in which he was immersed at the end of the nineteenth century, in the shadow of Wagner’s, Debussy’s and Stravinski’s works. The importance that Mallarmé attributed to music, accompanied by his gesture of “critical chance”, called the attention of two musicians of the twentieth century John Cage and Pierre Boulez: the first working Mallarmé’s “chance” not only in musical works, but also in poems, composed in the 1960’s, and the second, taking Mallarmé as a reference in essays and works. Such musical universe falls on two creators of concrete poetry: Augusto de Campos not only in his series Poetamenos but also in his visual poems composed during an orthodox phase posterior to Concretism, and Haroldo de Campos, for whom Mallarmé is the most outstanding guide of his theoretical, critical and creative course. More than just electing Mallarmé as a reference in his poetry, Haroldo de Campos, configures him as the most relevant poet for his notion of writing of Modernity. Following the same synchronical tradition, based on the conception of Roman Jakobson, Ezra Pound and T. S. Eliot, critical writers, Haroldo, along his poetic course, recovers the musicality of the French poet and the forms of articulating the nuclear axis of the present study. We intend, then, to demonstrate, in this study, that Un coup de dés establishes its contact with the music, is a product of the rational and critical ‘chance’ leading towards the exploration of the poetical word. The dialogue between literature and music, that the concretes intend to reinforce through Mallarmé’s poem, is the course that this work intends to bring forth.
106

Pai e filho(a) deficiente: o brincar e a intersubjetividade inata

Kampa, Alethea Valim 26 January 2009 (has links)
Made available in DSpace on 2016-03-15T19:40:40Z (GMT). No. of bitstreams: 1 Alethea Valim Kampa.pdf: 419504 bytes, checksum: ac0afb608176469c48b342d5deae18a3 (MD5) Previous issue date: 2009-01-26 / Fundo Mackenzie de Pesquisa / This study aimed to observe the existence or not of interactions between the father and his disabled child in playing situations, based upon the Theory of Innate Intersubjectivity. Two disabled children, aged 1 and 1-and-a-half year and their fathers were selected and filmed in their homes, during playtime, for a 30-minute period. Based in the assertion that the child has the ability to respond affective and adequately to the other and synchronically interact, observed behaviors were divided into two main categories: negotiatory and emotional. Playing was analyzed according to the children s ability to maintain them, based in Occupational Therapy s theories on the subject. Results showed that interactions between father and child occurred, although there were frequent breaking in synchrony and the presence of irritation in one of the children, as well as the ability of creating and sustaining a game, despite their limitations, with their fathers help. / Este estudo teve como objetivo observar a existência ou não de interação entre o pai e seu filho com deficiência em situação de brincar, usando como base a Teoria da Intersubjetividade Inata. Para tanto, foram selecionadas duas crianças de um ano e meio a dois anos e meio de idade com deficiência e seus pais para serem filmados em suas casas, num período de recreação, durante 30 minutos. Partindo do pressuposto de que a criança tem a capacidade de responder afetiva e adequadamente ao outro e interagir em sincronia, os comportamentos observados foram divididos em duas categorias principais: negociadoras e emocionais. As brincadeiras foram analisadas segundo a capacidade de manutenção delas pelas crianças, de acordo com as teorias da Terapia Ocupacional sobre o brincar. Os resultados indicaram que houve interação entre os pais e suas crianças, apesar de quebras freqüentes da sincronia e presença de comportamentos de irritação por parte de uma das crianças, além da capacidade delas em criar e sustentar uma brincadeira apesar de suas limitações, com a devida ajuda dos pais.
107

Stimulus Coding and Synchrony in Stochastic Neuron Models

Cieniak, Jakub January 2011 (has links)
A stochastic leaky integrate-and-fire neuron model was implemented in this study to simulate the spiking activity of the electrosensory "P-unit" receptor neurons of the weakly electric fish Apteronotus leptorhynchus. In the context of sensory coding, these cells have been previously shown to respond in experiment to natural random narrowband signals with either a linear or nonlinear coding scheme, depending on the intrinsic firing rate of the cell in the absence of external stimulation. It was hypothesised in this study that this duality is due to the relation of the stimulus to the neuron's excitation threshold. This hypothesis was validated with the model by lowering the threshold of the neuron or increasing its intrinsic noise, or randomness, either of which made the relation between firing rate and input strength more linear. Furthermore, synchronous P-unit firing to a common input also plays a role in decoding the stimulus at deeper levels of the neural pathways. Synchronisation and desynchronisation between multiple model responses for different types of natural communication signals were shown to agree with experimental observations. A novel result of resonance-induced synchrony enhancement of P-units to certain communication frequencies was also found.
108

Dynamique de l'évolution de la denture en rapport avec l'habitat, le comportement et le régime alimentaire chez les poissons perroquets (Scarinae, Labriformes) / Evolutionnary dynamics of the dentition in relationship with habitat, behaviour and diet in parrotfishes (Scarinae, Labriformes)

Viviani, Jérémie 07 November 2019 (has links)
Les poissons-perroquets, séparés en deux tribus les Scarini et les Sparisomatini, se sont diversifiés au sein des Labridae à partir d’ancêtres carnivores. L’un des facteurs essentiels pour expliquer cette diversification est leur exploitation d’une nouvelle niche trophique : les microorganismes. La plupart des Sparisomatini paissent des macroalgues pour y extraire les micro-organismes épiphytiques tandis que les poissons-perroquets brouteurs (tous les Scarini, certains Sparisoma) raclent ou creusent le substrat rocheux pour y récolter les microorganismes épilithiques et endolithiques. Ces changements de comportement alimentaire se sont accompagnés de nombreuses évolutions dentaires avec notamment la présence de plaques dentaires chez les brouteurs mais aussi certains paisseurs. Les phylogénies moléculaires ont contredit le précédent scénario évolutif sur la denture des poissons-perroquets qui stipulait l’apparition progressive de plaques dentaires à partir de dentures à dents non recouvertes d’os (dents libre s). Cette thèse se propose de réexaminer l’évolution de la denture chez les poissons -perroquets en se basant sur les progrès phylogénétiques mais aussi techniques (microtomographie 3D), tout en faisant le lien avec leur régime et leur fonction écologique. / Parrotfishes, divided into the tribes Scarini and Sparisomatini , are labrid fishes that arouse from carnivorous ancestors. One of the main factors that explain this radiation is the exploitation of microorganisms as a food source. While most Sparisomatini browse macroalgae to get epiphytic microorganisms, grazing parrotfishes (all Scarini and some Sparisoma) scrap or excavate hard substrate to obtain epilithic and endolithic microorganisms. Changes in feeding behaviour are associated with dentition specialization with notably dental plates in grazing but also some browsing parrotfishes. Gene-based phylogenies contradicted the previous evolutionary scenario about parrotfish dentition evolution, which states the progressive emergence of dental plates from non-coalesced dentitions. This thesis manuscript aims to re-examine the evolution of parrotfish dentitions in the light of the new phylogenies by using X-ray 3D microtomography, and to link this evolution with diet and ecology.
109

Modeling Temporal Patterns of Neural Synchronization: Synaptic Plasticity and Stochastic Mechanisms

Joel A Zirkle (9178547) 05 August 2020 (has links)
Neural synchrony in the brain at rest is usually variable and intermittent, thus intervals of predominantly synchronized activity are interrupted by intervals of desynchronized activity. Prior studies suggested that this temporal structure of the weakly synchronous activity might be functionally significant: many short desynchronizations may be functionally different from few long desynchronizations, even if the average synchrony level is the same. In this thesis, we use computational neuroscience methods to investigate the effects of (i) spike-timing dependent plasticity (STDP) and (ii) noise on the temporal patterns of synchronization in a simple model. The model is composed of two conductance-based neurons connected via excitatory unidirectional synapses. In (i) these excitatory synapses are made plastic, in (ii) two different types of noise implementation to model the stochasticity of membrane ion channels is considered. The plasticity results are taken from our recently published article, while the noise results are currently being compiled into a manuscript.<br><br>The dynamics of this network is subjected to the time-series analysis methods used in prior experimental studies. We provide numerical evidence that both STDP and channel noise can alter the synchronized dynamics in the network in several ways. This depends on the time scale that plasticity acts on and the intensity of the noise. However, in general, the action of STDP and noise in the simple network considered here is to promote dynamics with short desynchronizations (i.e. dynamics reminiscent of that observed in experimental studies) over dynamics with longer desynchronizations.
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Towards a Brain-inspired Information Processing System: Modelling and Analysis of Synaptic Dynamics: Towards a Brain-inspired InformationProcessing System: Modelling and Analysis ofSynaptic Dynamics

El-Laithy, Karim 19 December 2011 (has links)
Biological neural systems (BNS) in general and the central nervous system (CNS) specifically exhibit a strikingly efficient computational power along with an extreme flexible and adaptive basis for acquiring and integrating new knowledge. Acquiring more insights into the actual mechanisms of information processing within the BNS and their computational capabilities is a core objective of modern computer science, computational sciences and neuroscience. Among the main reasons of this tendency to understand the brain is to help in improving the quality of life of people suffer from loss (either partial or complete) of brain or spinal cord functions. Brain-computer-interfaces (BCI), neural prostheses and other similar approaches are potential solutions either to help these patients through therapy or to push the progress in rehabilitation. There is however a significant lack of knowledge regarding the basic information processing within the CNS. Without a better understanding of the fundamental operations or sequences leading to cognitive abilities, applications like BCI or neural prostheses will keep struggling to find a proper and systematic way to help patients in this regard. In order to have more insights into these basic information processing methods, this thesis presents an approach that makes a formal distinction between the essence of being intelligent (as for the brain) and the classical class of artificial intelligence, e.g. with expert systems. This approach investigates the underlying mechanisms allowing the CNS to be capable of performing a massive amount of computational tasks with a sustainable efficiency and flexibility. This is the essence of being intelligent, i.e. being able to learn, adapt and to invent. The approach used in the thesis at hands is based on the hypothesis that the brain or specifically a biological neural circuitry in the CNS is a dynamic system (network) that features emergent capabilities. These capabilities can be imported into spiking neural networks (SNN) by emulating the dynamic neural system. Emulating the dynamic system requires simulating both the inner workings of the system and the framework of performing the information processing tasks. Thus, this work comprises two main parts. The first part is concerned with introducing a proper and a novel dynamic synaptic model as a vital constitute of the inner workings of the dynamic neural system. This model represents a balanced integration between the needed biophysical details and being computationally inexpensive. Being a biophysical model is important to allow for the abilities of the target dynamic system to be inherited, and being simple is needed to allow for further implementation in large scale simulations and for hardware implementation in the future. Besides, the energy related aspects of synaptic dynamics are studied and linked to the behaviour of the networks seeking for stable states of activities. The second part of the thesis is consequently concerned with importing the processing framework of the dynamic system into the environment of SNN. This part of the study investigates the well established concept of binding by synchrony to solve the information binding problem and to proposes the concept of synchrony states within SNN. The concepts of computing with states are extended to investigate a computational model that is based on the finite-state machines and reservoir computing. Biological plausible validations of the introduced model and frameworks are performed. Results and discussions of these validations indicate that this study presents a significant advance on the way of empowering the knowledge about the mechanisms underpinning the computational power of CNS. Furthermore it shows a roadmap on how to adopt the biological computational capabilities in computation science in general and in biologically-inspired spiking neural networks in specific. Large scale simulations and the development of neuromorphic hardware are work-in-progress and future work. Among the applications of the introduced work are neural prostheses and bionic automation systems.

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