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Estudo molecular dos componentes da via de sinalização HGF/MET em insulinomas / Molecular study of the HGF/MET system in insulinomasCahue de Bernardis Murat 27 August 2013 (has links)
Os insulinomas são os tumores neuroendócrinos pancreáticos funcionantes mais frequentes, entretanto, os aspectos moleculares envolvidos em sua tumorigênese precisam ser melhor esclarecidos. As características morfológicas e histoquímicas dos insulinomas não conseguem predizer completamente seu comportamento biológico, apenas o fenótipo invasivo local e a presença de metástase são as formas confiáveis do diagnóstico maligno. A presente investigação teve por objetivos analisar a expressão gênica por reação em cadeia da polimerase (PCR) em tempo real e a expressão protéica por imuno-histoquímica dos componentes da via de sinalização do fator de crescimento hepatocítico (HGF) e seu receptor (c-MET) em 27 amostras de insulinomas, sendo: 16 tumores benignos grau 1 (G1), seis tumores benignos grau 2 (G2), dois insulinomas malignos grau 3 (G3) e três metástases hepáticas. Além disso, realizou-se a pesquisa de mutações somáticas no gene MET. Observou-se (1) o aumento da expressão dos genes HGF, MET e ST14 (codificante para a matriptase) e a baixa expressão do gene HAI-1 (codificante para a protease inibidora tipo-kunitz do tipo 1) nos insulinomas malignos e metástases quando comparados aos insulinomas benignos G1; (2) uma correlação positiva entre a expressão do mRNA do gene MET e o gene ST14 e índice proliferativo Ki-67, bem como uma correlação inversa entre a expressão do mRNA do gene HAI-1 e os genes MET, HGF, ST14 e o índice mitótico; (3) uma correlação positiva entre a expressão do gene ST14 e a expressão do mRNA do gene HGF; (4) maior expressão protéica de c-MET nos insulinomas malignos G3 em relação aos insulinomas G1/G2 e (5) ausência de mutações nos éxons 2, 10, 14, 16, 17 e 19 do gene MET. Concluiu-se que os genes HGF, MET, ST14 e HAI-1 estão diferencialmente expressos entre insulinomas malignos e benignos, o que pode ter implicações diagnósticas e terapêuticas / In an attempt to better understand the molecular processes involved in the tumourigenesis of islet beta-cells, the present study evaluated the expression of genes belonging to the hepatocyte growth factor and its receptor (HGF/MET) system, namely, MET, HGF; HGFAC and ST14 (encode HGF activator and matriptase, respectively, two serine proteases that catalyze conversion of pro-HGF to active HGF); and SPINT1 and SPINT2 (encode serine peptidase inhibitors Kunitz type 1 and type 2, respectively, two potent inhibitors of HGF activator and of matriptase) in 27 sporadic insulinomas; 16 grade 1 (G1), six grade 2 (G2), two grade 3 (G3) and three hepatic metastases. Quantitative reverse-transcriptase polymerase chain reaction was employed to assess RNA expression of the target genes and immunohistochemical analysis was used to evaluate the expression of MET and SPINT1. Somatic mutations of MET gene were searched by direct sequencing of exons 2, 10, 14, 16, 17 and 19. Overexpression of MET was observed in grouped G3 insulinomas and metastases concomitantly with upregulation of the genes encoding HGF and matriptase and downregulation of SPINT1. Positive correlations were observed between MET RNA expression and Ki-67 proliferation index while a negative correlation was detected between SPINT1 expression and the mitotic index. No somatic mutations were found in MET gene. The final effect of the increased expression of HGF, its activator (matriptase) and its specific receptor (MET) together with a decreased expression of one potent inhibitor of matriptase (SPINT1) is probably a contribution to tumoural progression and malignancy in insulinomas
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Tissue-specific gain of wild-type RTK levels combined with screen strategies identify new mechanisms of cell vulnerability in developmental and tumorigenic programsFan, Yannan 18 November 2016 (has links)
Pour étudier la capacité cellulaire à s’adapter aux changements de signalisation dépendante des RTKs, nous utilisons un modèle de souris où l’expression du RTK Met sauvage peut être accrue dans un tissu spécifique. La plupart des tissus se protègent contre cette expression anormale des RTK. Mais certains types cellulaires sont sensibles aux altérations des RTKs, c’est le cas du mésenchyme du membre pendant l’embryogenèse. En effet, l’expression de certains gènes du mésenchyme est modifiée et celui-ci n’est plus accessible aux myoblastes qui le colonisent, conduisant à des déficits des muscles du membre. Chez l’adulte une augmentation de l’expression de Met dans le foie (Alb-R26Met) perturbe l’homéostasie tissulaire, conduisant à la tumorigenèse. Pour identifier des gènes qui coopèrent avec les RTKs pendant l’initiation de la tumorigenèse, nous avons combiné les souris Alb-R26Met avec le système de mutagenèse Sleeping Beauty (SB) transposon. 285 gènes putatifs liés au cancer ont été identifiés. Certains sont des proto-oncogènes ou suppresseurs de tumeurs déjà connus, validant le système. D’autres gènes n’avaient, jusqu’à présent, jamais été associés à ce processus. 9 candidats ont été fonctionnellement validés. Pour identifier des signaux assurant le maintien de la tumeur, nous avons analysé le phosphokinome, testé l’efficacité de composés et identifié de nouvelles combinaisons de drogues qui agissent en synergie pour tuer les cellules cancéreuses dérivées de Alb-R26Met. En conclusion, ces travaux montrent qu’une approche génétique non-biaisée combinée à une approche génomique permet d’identifier de nouveaux mécanismes pertinents pour la biologie du cancer. / We explore the cell competence to deal with slight changes in RTK inputs during embryogenesis and tissue homeostasis using a mouse model in which wild-type RTK Met levels can be moderately enhanced in a tissue specific manner. Most tissues buffer enhanced RTK levels thus avoiding perturbation of developmental programs and tissue homeostasis. Nevertheless, certain cell types are vulnerable to RTK levels. During embryogenesis, the limb mesenchyme is sensitive to alterations of the spatial distribution of RTKs, as illustrated by gene expression changes and by loss of accessibility to incoming myoblasts, which lead to limb muscle defects. At adulthood, liver enhanced Met levels (Alb-R26Met) perturbs tissue homeostasis, leading to tumorigenesis. To uncover new genes that cooperate with RTKs during tumour initiation, we combined Alb-R26Met mice with the Sleeping Beauty (SB) transposon mutagenesis system. 285 putative cancer-related genes have been identified. Some correspond to known proto-oncogenes or tumour suppressors, thus validating the overall strategy we employed for cancer gene discovery. Others have not been previously linked to cancer. 9 new tumour suppressors have been functionally validated, demonstrating the validity of our screen strategy. To identify signals involved in tumour maintenance, we employed a phosphokinome-guided drug screen and identified new synergistic drugs deleterious for cancer cells modelled by the Alb-R26Met genetic setting. The overall strategy and outcomes strengthen the value of combining unbiased genetic and genomic approaches to identify new mechanisms relevant for cancer biology and new therapeutic interventions.
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Urban heat Island mitigation strategies in an arid climate. In outdoor thermal comfort reacheable / Réduction des ilots de chaleur urbains sous climat aride. Le confort extérieur est-il possibleRidha, Suaad 28 April 2017 (has links)
De nombreuses études au cours des dernières décennies ont porté sur l'effet l’îlot de chaleur urbain (ICU). Les efforts initiaux visant à comprendre les facteurs qui influent sur l’ICU ont contribué à la mise en place de solutions et de stratégies d'atténuation adaptées. Les stratégies d'atténuation comprennent généralement l'augmentation de l'albédo urbain (réflectivité au rayonnement solaire) et l'évapotranspiration. Les augmentations d'albedo sont obtenues grâce à des technologies de toiture et de pavage ayant un albédo élevé. Une augmentation de l'évapotranspiration est obtenue par une combinaison de la diminution de la fraction de surfaces imperméables et la plantation de végétation dans les zones urbaines. Le confort thermique extérieur est défini à partir d’indices prenant en compte différents paramètres physiques et traduit la perception et la satisfaction des piétons. Ce confort est très difficile à obtenir en climat chaud et aride. Par conséquent, le travail présenté dans ce document met l'accent sur les méthodes appropriées pour réduire l’ICU et ainsi améliorer le confort thermique en plein air des piétons. Jusqu’à présent, peu de recherches ont été menées sur le confort thermique extérieur dans un climat chaud et aride. Les études sur l'atténuation de l'ICU et le confort thermique extérieur sont pratiquement inexistantes pour la ville de Bagdad. Bagdad a un tissu urbain complexe avec des constructions modernes, des maisons traditionnelles et des éléments caractéristiques du patrimoine local. Le climat en été est chaud, et les mois d'été sont considérés comme la plus longue saison avec près de 7 mois de l'année. Dans un premier temps, cette étude se concentre sur l'étude des stratégies d'atténuation à envisager afin d’évaluer comment le confort des piétons est affecté par les choix de conception des constructions, en comparant un quartier traditionnel à un quartier moderne. L’étude envisage ensuite la façon dont la végétation et les ombrages contribuent à réduire l'effet de l'ICU et à améliorer le confort thermique extérieur. Quatre scénarios différents sont élaborés pour évaluer le rôle d’éléments végétaux tels que les arbres, l'herbe et les différents modèles d'ombrage. L'évaluation a été effectuée le jour le plus chaud de l'été, la température radiante moyenne, l'humidité spécifique, la température de l'air et les distributions de la vitesse du vent ont été analysées à l'aide du logiciel ENVI-met. Le confort thermique est ensuite évalué à l'aide des indices thermiques de la température équivalente physiologique PET et du PMV étendu aux ambiances extérieures. En outre, une proposition de solution est abordée afin d’étudier son impact sur le confort thermique pour la journée la plus chaude (situation extrême) et une journée typique d’été. Les résultats ont révélé une amélioration du confort thermique dans la journée typique d’été. L'étude montre comment les facteurs urbains tels que le rapport d'aspect, la couverture végétale, les ombres et la géométrie du quartier sont des éléments cruciaux que les urbanistes et les municipalités doivent prendre en compte, en particulier pour les nouveaux aménagements urbains dans un climat chaud et aride. Une proposition d’aménagement global pour atténuer les ICU dans le cas d’un nouveau quartier sous climat aride, est détaillée en fin de mémoire. / Numerous studies over the past several decades focused on the effect of the Urban Heat Island. Initial efforts on understanding the factors affecting UHI contributed to proceed the appropriate solutions and mitigation strategies. Mitigation strategies comprise increase both urban albedo (reflectivity to solar radiation), and evapotranspiration. Albedo increases are obtained through high albedo roofing and paving technologies. An increase in evapotranspiration is achieved through a combination of decreasing the fraction of impervious surfaces and planting vegetation in urban areas. The outdoor thermal comfort is influenced by the perception and satisfaction of the pedestrians, especially in hot and arid climates. Consequently, this work focuses on the appropriate methods for reducing the Urban Heat Island and thus to enhance the pedestrians outdoor thermal comfort. However, there is limited research conducted on the outdoor thermal comfort in hot and arid climate. The studies on the mitigation the Urban Heat Island and the outdoor thermal comfort are almost non-existent for Baghdad city. Baghdad has a complex urban fabric with modern design constructions buildings, traditional and heritage houses. The climate in summer is hot, and summer months are considered the longest season with nearly 7 months of the year. This study focuses on investigating possible mitigation strategies to ensure how pedestrian comfort is affected by the constructions design choices comparing a traditional district to a modern one, and on how vegetation and shading patterns contribute to reducing the effect of UHI and improving the outdoor thermal comfort. Four different scenarios are designed to assess the role of vegetation elements such as trees, grass, and different shading patterns. The evaluation was performed on the hottest day in summer, the mean radiant temperature, specific humidity, air temperature, and wind speed distributions have been analyzed using ENVI-met software. Thermal comfort is assessed using the thermal indices the Physiological Equivalent Temperature PET and the Predicted Mean Vote PMV. Also, a proposal model is designed to evaluate the thermal comfort on the hottest day and the typical day in summer. The results revealed an improvement on thermal comfort in the typical day in summer. The study shows how the urban factors such as the aspect ratio, vegetation cover, shadings, and geometry of the canyon are crucial elements that urban planners and municipalities have to take into account, especially for new urban developments in hot, arid climate.
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Role of suppressor of cytokine signalling 1 (SOCS1) in the pathogenesis of prostate cancer / Role of SOCS1 in prostate cancer pathogenesisVillalobos Hernandez, Alberto January 2016 (has links)
Le cancer de la prostate (PCa) est le deuxième cancer le plus courant chez les hommes au niveau mondial. Le suppresseur de la signalisation des cytokines 1 (SOCS1) est considéré comme un suppresseur de tumeur en raison de la fréquente répression épigénétique de ce gène dans de nombreux cancers. Il a été reporté que SOCS1 inhibait l’activation de STAT3 induite par l’IL-6, ainsi que les cyclines et les kinases dépendantes des cyclines dans les cellules malignes de la prostate. D’autre part, il a été montré que SOCS1 n’était pas essentiel lors du contrôle de la signalisation de l’IL-6 dans les hépatocytes dépourvus de cette protéine, cependant elle est essentielle pour atténuer la signalisation du facteur de croissance des hépatocytes (HGF) via son récepteur MET. MET est un récepteur de tyrosine kinases qui est surexprimé dans le PCa agressif et métastatique. Notre hypothèse de recherche propose que la répression de SOCS1 par méthylation du promoteur et la dérégulation de l’expression de MET et de sa signalisation, sont des mécanismes pathogéniques liés au développement et à la progression du PCa. Nous avons généré des lignées de cellules PC3 et DU145 stables exprimant SOCS1. Les cellules ont été stimulées avec HGF et l’activation des voies de signalisation a été évaluée par immunobuvardage. Des essais in vitro de migration, de prolifération et d’invasion ont été effectués en présence de HGF. Des gènes de transition épithélio-mésenchymateuse ont été évalués par PCR quantitatif en présence ou non du facteur de croissance. Les cellules du PCa transfectées ou pas avec SOCS1 ont été inoculées dans des souris NOD SCID gamma de façon sous-cutanée ou orthoptique afin d’évaluer respectivement la croissance tumorale et la formation de métastases. Les tumeurs reséquées ont été analysées histologiquement et biochimiquement. Nos résultats montrent que SOCS1 atténue l'activation de MET induite par HGF et la phosphorylation d’ERK dans les cellules PC3, ainsi que la phosphorylation d’ERK et d’AKT dans les cellules DU145. SOCS1 inhibe également la prolifération cellulaire induite par HGF, ainsi que la migration et l’invasion in vitro. De plus, SOCS1 réduit l’expression des gènes de transition épithélio-mésenchymateuse impliqués dans la dégradation des composants de la matrice extracellulaire dans les cellules DU145 mais pas dans les cellules PC3. La surexpression de SOCS1 a stimulé l’augmentation de déposition de collagène, in vivo. Les tumeurs formées par les cellules exprimant SOCS1 étaient de taille significativement plus petites avec une réduction de la prolifération comparé aux tumeurs provenant des cellules contrôles. En outre, SOCS1 a inhibé la formation de métastases à distance dans un modèle orthotopique. En conclusion, nous suggérons que SOCS1 est un suppresseur de tumeur indispensable de la prostate, et qu’au moins une partie de sa fonction a lieu via la régulation négative de la signalisation du récepteur MET. / Abstract : Prostate cancer (PCa) is the second most common cancer among men worldwide. Suppressor of cytokine signaling 1 (SOCS1) is considered a tumor suppressor due to frequent epigenetic repression of the SOCS1 gene in several human malignancies. Inactivation of SOCS1 also occurs in PCa by gene methylation and micro-RNA-mediated repression. SOCS1 has been reported to inhibit IL-6-induced STAT3 activation and down-regulates cyclins and cyclin-dependent kinases in PCa cells. It has been shown that SOCS1 is not required to control IL-6 signaling in SOCS1-deficient hepatocytes, but is essential to attenuate hepatocyte growth factor (HGF) signaling via its receptor MET. This protein is a receptor tyrosine kinase (RTK), overexpressed in aggressive and metastatic PCa. Thus we hypothesized that the repression of SOCS1 via promoter methylation and deregulated MET expression and signaling are inter-related pathogenic mechanisms in PCa development and progression. We generated stable SOCS1-expressing PCa cell lines (PC3 and DU145) using lentiviral transduction followed by clonal selection via limiting dilution. Cells were stimulated with HGF and downstream signaling events were assessed by Western blot. Proliferation, migration and invasion assays were also conducted in the presence of HGF in vitro. Epithelial mesenchymal transition genes were evaluated by qPCR in the presence or absence of the growth factor. The PCa cells transfected with SOCS1 and non-transfected controls were inoculated into NOD SCID gamma mice as xenografts or as orthotopic tumors to assess tumor growth and metastasis formation, respectively. Resected tumors were further analyzed histologically and biochemically. Our results showed that SOCS1 attenuates HGF-induced MET activation and ERK phosphorylation in PC3 and DU145 PCa cell lines. SOCS1 inhibited HGF induced cell proliferation, migration and invasion in vitro. Additionally, SOCS1 decreased epithelial mesenchymal transition genes involved in the degradation of extracellular matrix components in DU145 cells but not in PC3. In vivo, SOCS1 overexpression leads to an increase of collagen deposition. Tumors formed by SOCS1 expressing cells were significantly smaller in size with reduced cell proliferation compared to tumors arising from control cells. Furthermore, SOCS1 inhibited distant metastasis formation in the orthotopic model. Overall our results suggest that SOCS1 has a tumor suppressor role in PCa evolution and part of this function is mediated by the negative regulation of MET receptor signalling and down-regulation of genes supporting migration and invasion processes such as matrix metalloproteinases.
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Role of Oct4 in pXEN cell differentiation and MET processHan, Dongjun 29 July 2021 (has links)
Primitive extraembryonale Endoderm (pXEN) Stam-Zelllinien der Ratte repraesentieren wahrscheinlich die festgelegten Vorläufer des extraembryonalen. Die im mesenchymalen Zustand gehaltenen pXEN-Zellen können in vitro weiter zu parietalen und viszeralen Endoderm-ähnlichen Zellen differenzieren. pXEN-Zellen zusätzlich halten moderate Konzentrationen des ICM-Markers Oct4 aufrecht. Die Bedeutung von Oct4 in pXEN-Zellen ist jedoch unbekannt.
Bei höheren Zelldichten, beobachteten wir eine erhöhte Oct4-Expression und gleichzeitig eine Tendenz zu Epithelialisierung (MET) und viszeral endodermaler (VE) Differenzierung. Um zu klären, ob die Oct4-Expression kausal beteiligt ist, modulierten wir die Oct4-Konzentration. Transienter Knockdown von Oct4 reduzierte tendenziell die Expression von MET / VE-assoziierten Genen; umgekehrt förderte die Doxycycline-induzierte Expression eines menschlichen Oct4-Transgens die MET / VE-Differenzierung und verhinderte die Bildung charakteristischer Gang-Strukturen. Im letzteren Fall ging dem MET eine anfängliche Zell-Verlängerung und eine erhöhte Zellmotilität voraus.
Da ein GSK3-Inhibitor und Activin A auch den MET / VE-Phänotyp stimulierten, fragten wir uns, ob Oct4 über die Wnt/β-Catenin oder TGFβ Signalwege wirkt. Die verschiedene Schritte der Wnt/β-Catenin Signalgebung hemmen, blockierten die hOct4-induzierte MET- und VE-Expression nicht. Im Gegensatz dazu verhinderte Repsox, ein Inhibitor von Alk5 (TGFBR1), das hOct4-induzierte MET und die Expression von MET- und VE-Genen und stimulierte eher die Expression von parietalen Endoderm (PE) Genen.
Zusammengefasst zeigen diese Daten eine Rolle für Oct4 bei der MET / VE-Differenzierung auf, wahrscheinlich durch Stimulation eines TGFβ Signalweges. Weiterführende Experimente sind erforderlich um zu bestimmen, wie die zwei Prozesse der MET- und VE-Differenzierung innerhalb der extraembryonalen Endoderm-Linie unterschieden und in Beziehung gesetzt werden. / Rat primitive extraembryonic endoderm (pXEN) cell lines appear to represent the committed precursors of the extraembryonic endoderm. The pXEN cells maintained in the mesenchymal state can further differentiate to the parietal endoderm and visceral endoderm like-cells in vitro. In addition, pXEN cells maintain moderate levels of the ICM marker Oct4, a transcription factor that plays important roles in pluripotency, plasticity, and differentiation. However, the significance of Oct4 in pXEN cell lineage specification is unknown.
We observed that rat pXEN cells show increased Oct4 expression at higher densities, a condition that also promotes their epithelialization (MET) and visceral endodermal (VE) differentiation. In order to elucidate whether the Oct4 expression is causally involved, we modulated the Oct4 levels. Transient knockdown of Oct4 tended to reduce the expression of MET/VE-associated genes; conversely, the doxycycline-induced expression of a human Oct4 transgene promoted MET/VE differentiation and prevented the formation of characteristic duct structures. In the latter case, the MET was preceded by an initial elongation and increased cell motility.
Since GSK3 inhibitor and Activin A also stimulated the MET/VE phenotype, we then asked whether Oct4 acts through the Wnt/β-catenin or TGFβ pathways. Wnt inhibitors did not block the hOct4-induced MET and VE expression. By contrast, Repsox, an inhibitor of Alk5 (TGFBR1), prevented the hOct4-induced MET and the expression of MET and VE genes and rather stimulated the expression of parietal endoderm (PE) genes.
Taken together, these data indicate a role for Oct4 in MET/VE differentiation via stimulation of TGFβ signaling. Further work is needed to determine how the two MET and VE differentiation processes are distinguished and related within the extraembryonic endoderm lineage.
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Réactivité fer métal/smectites en milieu hydraté à 80°CLantenois, Sébastien 17 December 2003 (has links) (PDF)
Les dispositifs de stockage envisagés pour les déchets nucléaires de haute activité font intervenir une barrière ouvragée argileuse (smectites) ainsi que des conteneurs métalliques (fer). La diffraction des rayons X, la spectrométrie infrarouge et la microscopie électronique à transmission (pour l'analyse chimique et l'état d'oxydation du fer) permettent de déterminer l'évolution du système fer métal/smectites dans un milieu hydraté à 80°C. Le taux de déstabilisation des smectites en présence de fer métal varie de 0 à 100% en fonction des paramètres structuraux de la smectite (composition chimique, espace interfoliaire, quantité de fer octaédrique). La déstabilisation de la smectite et du fer métal génère de la magnétite ainsi qu'une phase gel à l'intérieur de laquelle cristallise une nouvelle phase argileuse très riche en fer. Cette phase montre deux degrés d'oxydation, avec un rapport fer(II)/fer(III) 20/80 (phase proche des odinites) ou 50/50 (phase proche des cronstedtites).
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Etude et compréhension des mécanismes de vieillissement des alliages de plomb-calciumRossi, Frédéric 11 December 2006 (has links) (PDF)
Les données de la littérature concernant le vieillissement et le survieillissement des alliages plomb-calcium sont bien souvent incomplètes et contradictoires. Ceci est certainement lié aux difficultés expérimentales rencontrées pour observer les transformations et le fait que celles-ci sont nombreuses, entraînant une certaine confusion dans les travaux des auteurs. De plus, de faibles écarts dans les conditions d'élaboration et dans la composition des alliages peuvent avoir de l'importance sur leur comportement. Le présent travail, réalisé pour le CEA-DAM, nous a permis d'obtenir un ensemble de diagrammes TTT plus réalistes et plus justes que ceux donnés dans la littérature. Les moyens techniques mis en place (en particulier, la préservation de la chaîne du froid, condition indispensable pour garantir la répétabilité des résultats), nous ont permis d'étudier plus particulièrement les premières transformations et de mieux maîtriser les cinq étapes de vieillissement et de survieillissement. Nos travaux ont permis de déterminer clairement les cinétiques et les mécanismes des transformations. Ce travail constitue un approfondissement de la compréhension des phénomènes de vieillissement et de survieillissement de ces alliages.
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Internationalising Chinese maritime higher education : developing content and English language integrated teaching and learningPyne, Robyn Morgan January 2012 (has links)
This thesis examines how new maritime nations, which are engaged in the export of seafaring labour, need to respond to the demands of the international maritime industry. In particular, traditional maritime nations are calling for greater internationalisation of maritime education and training. The global labour market for seafarers, which is dominated by employers from traditional maritime nations, demands internationally minded graduates. China’s response to these demands for quality labour exports from new maritime nations is the subject of exploration in this thesis. Within the specific context of Maritime English teaching and learning, a significant opportunity for innovation and change is identified. The research took the form of an international collaborative education project in pursuit of the following question: What teaching and learning development opportunities are there for improving the communicative competence of Chinese Navigation officers? The author of this thesis, formally a seafarer, is a teaching practitioner in higher education in the UK. For the purposes of this thesis, the author became a visi ting researcher, and later a teaching practitioner, at the case maritime higher education institution in China. Becoming a member of the teaching staff at the host institution was a necessary step in order to establish and carry out teaching practitioner -led research as a member of a professional learning community. The aim of this professional learning community has been to collaborate on a Maritime English teaching development project. This development work has since continued beyond this PhD study into a commercially funded project, which demonstrates the necessity and timeliness of the research. This thesis sets out to report on the collaborative process of an international education development project as it was experienced. Research was carried out over a 15.5 month period spent in-situ at the case institution. The institution was selected as it is the most influential maritime university in China in terms of national maritime higher education policy reform, due it being under the direct authority of the Ministry of Transport of the People's Republic of China rather than the Ministry of Education, as is the case with other universities. The author had to work very hard to overcome a number of cultural issues to become accepted as a teaching practitioner in the research setting. Once accepted as a participant researcher, research-based professionalism founded on previous teacher training and experience allowed for a living theory approach to improving both own teaching practice and that of new-found colleagues. The outcomes of this PhD study are multiple: The ethnographic account of the development process in the form of this PhD thesis. The establishment of a professional learning community between teaching practitioners and continued research and development work. The local teaching and learning innovation in the form of a new content and language integrated syllabus for Maritime English teaching, suitable for Chinese learners at maritime higher education institutions. The continued collaboration between an industry stakeholder and the local teaching practitioners in the further development of a new Maritime English syllabus and accompanying teaching resources to ensure that it meets the needs of employers. As understanding grew of how Chinese maritime higher education institutions are preparing their students for employment in the global labour market for seafarers, the research objectives emerged while in-situ. The aim of the research centred on working with local teaching practitioners and industry stakeholders to improve the quality of maritime education graduates’ transferable skills, in terms of their intercultural communicative competence. The key feature of the study was to collaboratively identify teaching and learning development opportunities for improving the preparedness of Chinese maritime higher education graduates to work in a safety critical environment, where they will need to communicate effectively in English. The internationalisation of the Maritime English syllabus, and the wider Navigation curriculum, through content and language integrated learning and teaching is the main recommendation of this thesis. The evidence presented in this thesis has led to the conclusion that this curriculum intervention is necessary for improving the transferable skills of Chinese Maritime Higher Education graduates. The content and language integrated learning approach to teaching was found to offer Chinese maritime higher education institutions with a solution to boost intercultural communicative competence in meeting the demands of the international maritime industry for professionally skilled, and competent-in-English seafarers for labour export.
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Ablation des matériaux carbonés : lien entre la nanotexturation et la réactivité / Ablation of carbon materials : relation between nanotexture and reactivityDelehouzé, Arnaud 06 December 2012 (has links)
La problématique énoncée par l’utilisation de matériaux composites C/C denses implique la connaissance et la maîtrise des processus de dégradation auxquels ils sont soumis. L’utilisation de moyens de caractérisation in-situ de ces voies de dégradation constitue alors un atout considérable pour leur anticipation. Ainsi, l’utilisation de la MEBE en Température associée à une caractérisation cristallographique par MET et une confrontation ex-situ par Analyse thermogravimétrique a abouti à l’obtention de lois cinétiques caractérisant la propagation de l’oxydation dans toutes les directions de l’espace. A la suite de cette étape expérimentale, une approche numérique basée sur l’utilisation d’algorithmes de Monte-Carlo Cinétique, a alors été mise en place pour modéliser ces observations tant sur le plan atomique avec la modélisation de la loi cinétique d’oxydation linéique, que meso et macroscopique par la simulation de la loi cinétique de perte de masse dans le cas particulier du HOPG. / The problem stated by the use of composites C / C dense implies knowledge and control of degradation processes to which they are subjected. The use of in-situ characterization of these means of degradation pathways then is a considerable asset for their advance. Thus, the use of ESEM in temperature associated with a crystallographic characterization by TEM and ex situ confrontation by thermogravimetric analysis resulted in obtaining kinetic laws characterizing the propagation of oxidation in all directions. Following this experimental stage, a numerical approach based on the use of algorithms Kinetic Monte-Carlo, was then introduced to model these observations both at the atomic level with the modeling of the oxidation kinetics law linear, as meso-and macro-simulation by the kinetic law of mass loss in the case of HOPG.
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Mancha-marrom (Alternaria alternata f.sp. citri patótipo \"tangerina\"): processo infeccioso nas cultivares Ponkan, Murcott e Fremont / Alternaria brown spot (Alternaria alternate f.sp. citri \"tangerine\" pathotype): infectious process in the cultivars Ponkan, Murcott e FremontFelipini, Ricardo Barbosa 15 February 2019 (has links)
A mancha-marrom de Alternaria causada pelo fungo Alternaria alternata f.sp. citri patótipo \"tangerina\" é uma das principais doenças que acometem a cultivo de tangerinas (Citrus reticulata) e alguns de seus híbridos. A infecção ocorre principalmente em folhas e frutos jovens que senescem prematuramente. Para realização de estudos com a finalidade de obtenção de cultivares resistentes, ou para a compreensão dos processos de interação planta-patógeno, é necessária a produção massal de esporos in vitro. Este trabalho, no primeiro momento, buscou desenvolver um método eficaz de obtenção de esporos do fungo em meio de cultura. Para isso, comparou os efeitos de diferentes meios de cultura (BDA e CaCO3-A) e tipos de iluminação (LED e NUV). Além do número de esporos, características como germinação, pigmentação, formação de apressórios e patogenicidade foram avaliadas. Descobriu-se que o melhor método de produção de esporos consistiu da manutenção de colônias em meio CaCO3-A por 3 dias sob LED e em seguida por 4 dias sob NUV, com fotoperíodo de 12 h. A partir de então, no segundo momento, realizaram-se testes com técnicas de microscopia e bioquímica fitopatológica para analisar a interação entre o patógeno e folhas das cultivares suscetíveis Ponkan e Murcott e da resistente Fremont. Notou-se por meio de microscopia eletrônica de varredura (MEV) que, independentemente da cultivar, o fungo germinou sobre as folhas, formou apressórios e entrou em cavidades estomáticas. Não foi observada, porém, a colonização de tecidos por meio de microscopia de luz. As cultivares suscetíveis responderam à inoculação com acúmulo de peróxido de hidrogênio e reação de hipersensibilidade. A cultivar resistente, por sua vez, não apresentou reação de hipersensibilidade e aumentou a síntese de enzimas relacionadas ao estresse oxidativo (SOD e CAT) e eliminação de espécies reativas de oxigênio. Como se trata de um fungo necrotrófico capaz de detoxificar espécies reativas de oxigênio, presumiu-se que a reação de hipersensibilidade e a morte celular nas cultivares suscetíveis favorecem a infecção e colonização do patógeno, enquanto que na cultivar resistente a ausência de morte celular e detoxificação de espécies reativas de oxigênio podem estar envolvidas na sua capacidade de defesa. Nas cultivares suscetíveis, verificou-se, por meio de microscopia eletrônica de transmissão (MET), plasmólise e fragmentação de membranas plasmáticas, local indicado como sítio de ação da toxina ACT produzida pelo patógeno. As células da cultivar resistente não apresentaram plasmólise ou alterações nas membranas plasmáticas em decorrência da inoculação do patógeno. / Alternaria brown spot caused by Alternaria alternate f.sp. citri pathotype \"tangerine\" is a important disease that affects tangerine (Citrus reticulate), and some of its hybrids. The infection happens mainly in young leaves and fruits and may cause premature senescence of tissues. To carry out studies in order to obtain resistant cultivars, or to understand the processes of plant-pathogen interaction, it is necessary abundant in vitro spores production. This work, in the first moment, aimed to develop an efficient method for in vitro spore production of the fungus. It was compared the effects of different culture media (BDA and CaCO3-A) and light (LED and NUV). Besides the number of spores, characteristics such as germination, pigmentation, apressoria formation and pathogenicity were investigated. It was found that the best method of spore production consisted of maintaining colonies on CaCO3-A medium for 3 days under LED and then for 4 days under NUV, with photoperiod of 12 h. Thus, in the second moment, assays were carried out using microscopy and phytopathological biochemistry techniques to analyze the interaction between the pathogen and leaves of the susceptible cultivars Ponkan and Murcott, and the resistant Fremont. It was noted by scanning electron microscopy (SEM) that independently of the cultivar, the fungus germinated on the leaves, formed apressoria and grew into stomatal cavities. However, colonization of tissues was not observed by light microscopy. Susceptible cultivars responded to inoculation with accumulation of hydrogen peroxide and hypersensitivity reaction. The resistant cultivar did not show hypersensitivity reaction, but increased the synthesis of enzymes (CAT and SOD) related to oxidative stress and elimination of reactive oxygen species. As a necrotrophic pathogen able to detoxify reactive oxygen species, it was assumed that the hypersensitivity reaction and cell death in the susceptible cultivars contribute to infection and colonization of the pathogen. On the other hand, the absence of cell death and detoxification of reactive oxygen species verified in the resistant cultivar may be involved on its capacity of defense. Cell plamolysis and plasma membranes fragmentation, indicated as the site of action of the ACT toxin produced by the pathogen, were verified in the susceptible cultivars by transmission electron microscopy (TEM). The cells of the resistant cultivar did not show plasmolysis or alterations in the plasma membranes due to pathogen inoculation.
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