72 research outputs found
Image And Signal-Based Modelling
No full textPatient specific modelling and simulation of human body imply accessing the structural, functional and biological characteristics of individual subjects. Medical signals and images provide us with a powerful way to evaluate in vivo these characteristics…Fil: Frangi, Alejandro. Universitat Pompeu Fabra; EspañaFil: Friboulet, Denis. Universidad de Lyon 3; FranciaFil: Ayache, Nicholas. Institut National de Recherche en Informatique et en Automatique; FranciaFil: Delingette, Hervé. Institut National de Recherche en Informatique et en Automatique; FranciaFil: Glatard, Tristan. Universidad de Lyon 3; FranciaFil: Hoogendoorm, Corne. Universitat Pompeu Fabra; EspañaFil: Humbert, Ludovic. Universitat Pompeu Fabra; EspañaFil: Lekadir, Karim. Universitat Pompeu Fabra; EspañaFil: Larrabide, Ignacio. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Grupo de Plasmas Densos Magnetizados. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Grupo de Plasmas Densos Magnetizados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Martelli, Yves. Universitat Pompeu Fabra; EspañaFil: Peyrin, Françoise. Universidad de Lyon 3; FranciaFil: Planes, Xavier. Universitat Pompeu Fabra; EspañaFil: Sermesant, Maxime. Institut National de Recherche en Informatique et en Automatique; FranciaFil: Villa Uriol, Maria-Cruz. Universitat Pompeu Fabra; EspañaFil: Whitmarsh, Tristan. Universitat Pompeu Fabra; Españ
3D reconstruction of the proximal femur and lumbar vertebrae from dual-energy x-ray absorptiometry for osteoporotic risk assessment
No full textIn this thesis a method was developed to reconstruct both the 3D shape and the BMD distribution of bone structures from Dual-energy X-ray Absorptiometry (DXA) images. The method incorporates a statistical model built from a large dataset of Quantitative Computed Tomography (QCT) scans together with a 3D-2D intensity based registration process.
The method was evaluated for its ability to reconstruct the proximal femur from a single DXA image. The resulting parameters of the reconstructions were subsequently evaluated for their hip fracture discrimination ability. The reconstruction method was finally extended to the reconstruction of the lumbar vertebrae from anteroposterior and lateral DXA, thereby incorporating a multi-object and multi-view approach.
These techniques can potentially improve the fracture risk estimation accuracy over current clinical practice.En esta tesis se desarrolló un método para reconstruir tanto la forma 3D de estructuras óseas como la distribución de la DMO a partir de una sola imagen de DXA. El método incorpora un modelo estadístico construido a partir de una gran base de datos de QCT junto con una técnica de registro 3D-2D basada en intensidades.
Se ha evaluado la capacidad del método para reconstruir la parte proximal del fémur a partir de una imagen DXA. Los parámetros resultantes de las reconstrucciones fueron evaluados
posteriormente por su capacidad en discriminar una fractura de cadera. Por fin, se extendió el método a la reconstrucción de las vértebras lumbares a partir de DXA anteroposterior y lateral incorporando así un enfoque multi-objeto y multi-vista.
Estos técnicas pueden potencialmente mejorar la precisión en la estimación del riesgo de fractura respecto a la estimación que ofrece la práctica clínica actual.Programa de doctorat en Tecnologies de la Informació i les Comunicacion
3D reconstruction of the proximal femur and lumbar vertebrae from dual-energy x-ray absorptiometry for osteoporotic risk assessment
No full textIn this thesis a method was developed to reconstruct both the 3D shape and the BMD distribution of bone structures from Dual-energy X-ray Absorptiometry (DXA) images. The method incorporates a statistical model built from a large dataset of Quantitative Computed Tomography (QCT) scans together with a 3D-2D intensity based registration process. The method was evaluated for its ability to reconstruct the proximal femur from a single DXA image. The resulting parameters of the reconstructions were subsequently evaluated for their hip fracture discrimination ability. The reconstruction method was finally extended to the reconstruction of the lumbar vertebrae from anteroposterior and lateral DXA, thereby incorporating a multi-object and multi-view approach. These techniques can potentially improve the fracture risk estimation accuracy over current clinical practice.En esta tesis se desarrolló un método para reconstruir tanto la forma 3D de estructuras óseas como la distribución de la DMO a partir de una sola imagen de DXA. El método incorpora un modelo estadístico construido a partir de una gran base de datos de QCT junto con una técnica de registro 3D-2D basada en intensidades. Se ha evaluado la capacidad del método para reconstruir la parte proximal del fémur a partir de una imagen DXA. Los parámetros resultantes de las reconstrucciones fueron evaluados posteriormente por su capacidad en discriminar una fractura de cadera. Por fin, se extendió el método a la reconstrucción de las vértebras lumbares a partir de DXA anteroposterior y lateral incorporando así un enfoque multi-objeto y multi-vista. Estos técnicas pueden potencialmente mejorar la precisión en la estimación del riesgo de fractura respecto a la estimación que ofrece la práctica clínica actual.Programa de doctorat en Tecnologies de la Informació i les Comunicacion
3D reconstruction of the proximal femur and lumbar vertebrae from dual-energy x-ray absorptiometry for osteoporotic risk assessment
No full textIn this thesis a method was developed to reconstruct both the 3D shape and the BMD distribution of bone structures from Dual-energy X-ray Absorptiometry (DXA) images. The method incorporates a statistical model built from a large dataset of Quantitative Computed Tomography (QCT) scans together with a 3D-2D intensity based registration process.
The method was evaluated for its ability to reconstruct the proximal femur from a single DXA image. The resulting parameters of the reconstructions were subsequently evaluated for their hip fracture discrimination ability. The reconstruction method was finally extended to the reconstruction of the lumbar vertebrae from anteroposterior and lateral DXA, thereby incorporating a multi-object and multi-view approach.
These techniques can potentially improve the fracture risk estimation accuracy over current clinical practice.En esta tesis se desarrolló un método para reconstruir tanto la forma 3D de estructuras óseas como la distribución de la DMO a partir de una sola imagen de DXA. El método incorpora un modelo estadístico construido a partir de una gran base de datos de QCT junto con una técnica de registro 3D-2D basada en intensidades.
Se ha evaluado la capacidad del método para reconstruir la parte proximal del fémur a partir de una imagen DXA. Los parámetros resultantes de las reconstrucciones fueron evaluados
posteriormente por su capacidad en discriminar una fractura de cadera. Por fin, se extendió el método a la reconstrucción de las vértebras lumbares a partir de DXA anteroposterior y lateral incorporando así un enfoque multi-objeto y multi-vista.
Estos técnicas pueden potencialmente mejorar la precisión en la estimación del riesgo de fractura respecto a la estimación que ofrece la práctica clínica actual.Programa de doctorat en Tecnologies de la Informació i les Comunicacion
Livius Andronicus, Lucius, c. 280/270–200 BCE
No full textLucius Livius Andronicus (c. 280/70–200 BCE) was a Latin author of probable Greek origin who is credited with initiating the tradition of scripted dramatic performance at Rome and composing the first epic poem in Latin. Andronicus’s life appears to have spanned a large part of the 3rd century BCE; the only firmly transmitted date concerns the performance of a hymn to Juno for which he was commissioned during the Second Punic War (207 BCE). He is often linked to the year 240 BCE, a widely accepted but controversial date for his first staging of Latin plays during the Ludi Romani (“Roman Games”). His translation of the Odyssey was influential, although its initial audience and level of circulation are debated. His works survive exclusively in fragments. Andronicus’s skeletal ancient biography suggests his status as a formerly enslaved person who was trafficked to Rome from Magna Graecia in the aftermath of war. Latin literature’s first author was thus a forcibly displaced migrant for whom Latin was a second or third language. This account may not be wholly accurate, but it aligns with other near- contemporary authorial biographies and various attested trends in Roman sociopolitical and cultural history during the increasingly mobile Middle Republic
An I for an I: Reading Fictional Autobiography
No full textThe distinction between author and narrator is central to narratology, and to modern literary criticism in general. Why is it that ancient critics seem so often to ignore it, and to confuse the narrator's words with authorial autobiography? This chapter argues that antiquity had a different way of understanding first person narration, which was conceived of more in terms of illusionistic role playing: the author is imagined as playing the part of a character in a fiction. As with other varieties of illusionism in ancient thought, fictional autobiography has a double aspect: the author both is and, at once, is not the character in question. The chapter concludes by claiming that the fictional 'I' is metaleptic, in Gerard Genette's sense: it creates a space in which the author shuttles between an internal and an external perspective on narrative action
Characterization of the composition and activity of the photosynthetic apparatus in chloroplasts
No full textThe effect of growth light intensity on the photosynthetic apparatus of pea thylakoid membranes was investigated. Peas were grown either in a growth chamber at light intensities that ranged from 8 to 1050 E/m\sp2 s, or outside under natural sunlight. In thylakoid membranes the amounts of the following photosynthetic components were determined: active and inactive photosystem II, photosystem I, cytochrome b/f, high-potential cytochrome b-559, the rate of uncoupled electron transport, and the ratio of chlorophyll a to b. In leaves the amounts of the photosynthetic components per leaf area, the fresh weight per leaf area, the rate of electron transport and the light compensation point were determined. The maximum difference in the concentrations of the photosynthetic components in peas grown above the light compensation point (20 to 40 E/m\sp2 s) was about 30% in thylakoids isolated from plants grown over a ten-fold range in light intensity, 100 to 1050 E/m\sp2 s. Peas grown under natural sunlight were virtually indistinguishable from plants grown in growth chambers at the higher light intensities. On a leaf area basis, over the same growth light regime, the maximum difference in the concentration of the photosynthetic components was also about 30%. For peas grown at 1050 E/m\sp2 s we found the concentrations of active photosystem II, photosystem I, and cytochrome b/f were about 2.1 mmol/mol chlorophyll. There was an additional 20 to 33% of photosystem II complexes that were inactive. In our view, these data do not constitute convincing evidence that the stoichiometries of the electron transport components in the thylakoid membrane, the size of the light-harvesting system serving the reaction centers, or the concentration of the photosynthetic components per leaf area, are regulated in response to different growth light intensities. The concept that emerges from this work is of a relatively fixed photosynthetic apparatus in thylakoid membranes of peas grown above the light compensation point.Made available in DSpace on 2011-05-07T14:16:14Z (GMT). No. of bitstreams: 2
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Investigation of photoprotection of photosystem II by cytochrome b559
No full textThe objective of this project has been to study molecular mechanisms that plants use to avoid damage caused by excess light. Light that exceeds the photosynthetic capacity of a plant can impair the ability of photosystem II to evolve oxygen and can ultimately lead to degradation of proteins within the reaction center. Photoinhibitory reactions caused by ultraviolet B radiation (280-320 nm) are of particular concern since decreased stratospheric ozone is predicted to enhance levels of this radiation incident on the earth's surface. Photoinhibition can be initiated by inopportune events that create damaging redox states within the photosystem II complex. One mechanism for protection against high light involves thermal deactivation of energy within pigment beds. In addition, there is increasing evidence that secondary electron transport pathways within photosystem II can protect against potentially damaging redox states. Experiments using photosynthetic membranes poised at different ambient redox potentials demonstrate that light-induced damage to photosystem II is controlled by a redox component within the reaction center with a pH-independent midpoint potential of +20 mV in thylakoid membranes and +100 mV in photosystem II-enriched membranes. The rate of photoinhibition is slow when the redox component is oxidized, but increases up to 30-fold when the component is reduced. Here, evidence is provided that the redox component is cytochrome b559, an intrinsic heme protein of the photosystem II reaction center, and that the photoprotective pathway involves electron transfer to the cytochrome from the reduced form of pheophytin. The results of this dissertation support a model in which the low potential (LP) form of cytochrome b559 protects photosystem II against photoinhibition by deactivating a rarely formed, but unfavorable redox state of photosystem II, namely, P680/Pheo\sp{-}/Q\sb{\rm A}\sp{-}. Although photoinhibition occurred rapidly in photosynthetic membranes irradiated with visible light with Cyt b559LP poised in the reduced state, irradiation with ultraviolet-B light did not decrease photosynthetic capacity in thylakoid membranes even at an irradiance more than 20 times ambient. In addition, growth of Pisum sativum and Cucumis sativus under a light environment with up to 3 times the ambient dose did not adversely affect whole leaf photosynthetic rates.Made available in DSpace on 2011-05-07T14:03:59Z (GMT). No. of bitstreams: 2
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Characterization of cytochromes and plastocyanin in the cyanobacterium Synechocystis sp. PCC 6803
No full textThe main objective of this project is to study the components involved in electron transport between the cytochrome bf complex and photosystem I in the unicellular cyanobacterium Synechocystis 6803. Two soluble proteins, the heme-protein cytochrome c553 and the copper protein plastocyanin, were isolated from this species and specific antibodies were raised to each protein. Using antibodies as probes, the reciprocal accumulation of the two proteins in response to the copper concentration in the medium was characterized. Cytochrome c553 was present when cells were grown in the copper deficient medium, while plastocyanin was present when cells were provided with sufficient copper. The gene of cytochrome c553 was cloned and sequenced from Synechocystis 6803. The 360 bp open-reading frame encodes a 35 amino acid pre-sequence and a 85 amino acid mature protein. Northern analysis indicates that regulation of the cytochrome c553 gene expression by copper is at a stage prior to translation and that the transcript is a monocistronic mRNA. Mutants were constructed in which the gene for cytochrome c553 was deleted and the gene for plastocyanin was interrupted by insertional inactivation. When the synthesis of plastocyanin was inhibited by copper deprivation in the cytochrome c553 deletion mutant, or when the synthesis of cytochrome c553 was inhibited by the presence of copper in plastocyanin deficient mutant, both mutant strains exhibited normal photoautotrophic growth and steady-state photosynthetic electron transport rates. These observations indicate that electrons are transferred from the cytochrome bf complex to photosystem I in the absence of both cytochrome c553 and plastocyanin. Analysis of cytochrome composition did not reveal any induced cytochrome component that could substitute for the role of plastocyanin or cytochrome c553 in the mutant strains. However, we have evidence that there is an unknown membrane bound redox component with an absorption peak near 560 nm in an ascorbate minus hydroquinone chemical difference spectrum that may be a b-type cytochrome.Made available in DSpace on 2011-05-07T14:25:03Z (GMT). No. of bitstreams: 2
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