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1
Abou, Serhal Daou Pascale. "The role of the diaphanous-related formins DRF1, DRF2 and DRF3 in ErbB2-dependent cell motility and microtubule dynamics." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5037.
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Les formines de la famille des DRF sont des puissants nucleateurs d'actine. Précédemment, nous avons montré que DRF1 participe à la capture des microtubules (MTs) au niveau du cortex cellulaire, en aval du récepteur ErbB2. Ceci impliquait le recrutement d'APC et ACF7. Dans cette étude, nous avons examiné la contribution de DRF1, DRF2 et DRF3 à la capture des MT corticaux et à la migration cellulaire ErbB2- dépendante. La déplétion individuelle de DRF1/2 ou 3 à l'aide de siRNA perturbe fortement la migration chimiotactique ErbB2-dépendante. Les DRF sont toutes trois requises pour la capture des MT au niveau du cortex cellulaire. Des mutants de DRF1 déficients pour leur association avec l'actine sont toujours actifs pour la capture des MT. Nous avons aussi pu montrer qu'une construction limitée au domaine FH2 des DRF était parfaitement fonctionnelle. Nous avons alors procéder à une recherche systématique des protéines se liant au domaine FH2, par purification d'affinité et spectrométrie de masse. Nous avons observé que les domaines FH2 de DRF1, DRF2 et DRF3 se lient à des groupes de partenaires distincts. Ainsi, seul le domaine FH2 de DRF1 lie la protéine Rab6-Interacting Protein 2 (RB6IP2). De plus, DRF1 contrôle le recrutement de RB6IP2 au cortex cellulaire et la déplétion concomitante de RB6IP2 et d'IQGAP1 perturbe fortement la capture des MT. Ces résultats démontrent l'implication de l'interaction entre DRF1 et RB6IP2 dans la capture des MT dans les cellules en migrationDiaphanous-related formins (DRF) nucleate single linear filaments, binding to and protecting from capping their growing barbed ends. We have previously found that DRF1 participated to the tethering of microtubules (MTs) to the cell cortex, downstream of the ErbB2 receptor tyrosine kinase. This involved the recruitment of APC and ACF7. We have now further investigated the contribution of DRF1, and of the closely related DRF2 and DRF3, to the capture of cortical MTs and ErbB2-dependent breast carcinoma cell migration.Using siRNA to knock down individual DRFs, we found that depletion of DRF1/2 or3 strongly disturbed ErbB2-dependent chemotaxis. All three DRFs were required for the formation of cortical MTs, in a non-redundant manner. DRF1 mutant proteins defective for actin binding were still active for MT capture. We also found that, upon truncation of the Formin Homology (FH) 1 domain, the FH2 domain remained fully functional. In a systematic search for proteins binding to the FH2 domains via affinity purification and mass spectrometry analysis, we observed that the FH2 domains of DRF1, DRF2 and DRF3 engaged with distinct sets of proteins. For instance, only FH2 domain of DRF1 pulled down Rab6-Interacting Protein 2 (RB6IP2). Interestingly, DRF1 controlled the cortical localization of RB6IP2 and concomitant depletion of RB6IP2 and IQGAP1 strongly disturbed capture of cortical MTs, showing the involvement of the DRF1/IQGAP1/RB6IP2 interaction in MT tethering at the cell leading edge
2
Prigent-Cossard, Magali. "Caractérisation fonctionnelle des protéines ypt/rabgap, Gyp5p et Gyl1p et de leur interaction avec une protéine à domaine N-BAR, Rvs167p chez Saccharomyces cerevisiae." Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112154.
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Chez la levure Saccharomyces cerevisiae, la croissance est orientée et nécessite l’apport de membranes et d’enzymes pour la synthèse de la paroi cellulaire. La régulation du transport des vésicules permettant cet apport est assuré par les GTPases de la famille Ypt/Rab. Sec4p, une Ypt/Rab GTPase, est impliquée dans l’exocytose en assurant la spécificité de l’ancrage des vésicules post-golgiennes envoyées aux sites de croissance. La régulation de son activité GTPase est essentielle pour sa fonction.Nous nous intéressons aux protéines Gyp5p et Gyl1p, deux membres de la famille des protéines activatrices des GTPases Ypt/Rab chez S. cerevisiae. Le laboratoire a montré l’implication du complexe Gyp5p-Gyl1p dans l’exocytose polarisée vraisemblablement par la régulation de Sec4p. Notre étude a montré une interaction directe in vitro de ces deux protéines, ainsi qu’une interdépendance pour une bonne localisation du complexe aux sites de croissance polarisée, c'est-à-dire au sommet du bourgeon durant la croissance apicale et au cou du bourgeon durant la cytocinèse. Cette localisation dépend de deux formines, d’éléments du polarisome et des câbles d’actine. De plus, nous avons montré par des expériences d’immunofluorescence et de microscopie électronique en collaboration avec J.-M. Verbavatz (iBiTec-S, CEA), que ces protéines sont transportées sur des vésicules de sécrétion jusqu’aux sites de croissance polarisée.Notre étude de l’interaction du complexe Gyp5p-Gyl1p avec Rvs167p, une protéine à domaine BAR (Bin1-Amphiphysin-Rvs167p) a montré que Gyp5p et Gyl1p sont nécessaires pour la bonne localisation de Rvs167p au sommet du petit bourgeon et que ces complexes se forment principalement dans des fractions enrichies en membrane plasmique. Pour mieux caractériser ces interactions, nous avons réalisé une mutation de la proline 473 dans le domaine SH3 de Rvs167p et des délétions des séquences riches en proline de Gyp5p et Gyl1p. Ces mutations entraînent un défaut d’interaction de Rvs167p avec Gyp5p et Gyl1p et la perte de la localisation de Rvs167p au sommet du petit bourgeon. Afin de comprendre la fonction de ces interactions, nous avons réalisé des expériences de microscopie électronique et des tests de sécrétion de l’endo-β-1,3-glucanase, Bgl2p dans une souche Δrvs167. Nous avons mis en évidence une accumulation de vésicules de sécrétion au niveau du petit bourgeon et un défaut de sécrétion de Bgl2p à 13°C dans cette souche. De plus, nous avons également observé une accumulation de vésicules de sécrétion dans une souche exprimant Rvs167p mutée pour la proline 473 et un défaut de sécrétion de Bgl2p dans une souche exprimant Gyp5p et Gyl1p dépourvues de leurs séquences riches en proline. Ces résultats montrent que Rvs167p joue un rôle dans l’exocytose polarisée au stade du petit bourgeon et que cette fonction dépend de son recrutement par Gyp5p et Gyl1p au sommet du petit bourgeonIn Saccharomyces cerevisiae, growth is oriented and requires the contribution of membranes and enzymes for the synthesis of the cell wall. Regulation of vesicles transport allowing this contribution is provided by the Ypt/Rab GTPases family. Sec4p, a Ypt/Rab GTPase, is involved in exocytosis by controlling the tethering of post-Golgi vesicles at sites of growth. Regulation of Sec4p GTPase activity by is essential for its function.We studied the proteins Gyp5p and Gyl1p, two members of the Ypt/Rab GTPases activiting proteins (RabGAP) family in S. cerevisiae. Gyp5p and Gyl1p interact with Sec4p and are involved in the control of exocytosis at the small-bud stage. Our study showed that Gyp5p and Gyl1p interact directly in vitro and are interdependent for their correct localization to the sites of polarized growth, e.g. the bud tip during apical growth and the bud neck during cytokinesis. We showed that the localization of Gyp5p and Gyl1p to the sites of polarized growth depends on the formins Bni1 and Bnr1, but also on polarisome components and actin cables. Moreover, we showed by immunofluorescence and electron microscopy (in collaboration with J.-M. Verbavatz), that Gyp5p and Gyl1p are transported onto secretory vesicles to access the sites of polarized growth.We studied the interaction of Gyp5p and Gyl1p with Rvs167p, a BAR domain (Bin1-Amphiphysin-Rvs167p) protein and showed that Gyp5p and Gyl1p are necessary for the recruitment of Rvs167p to the small-bud tip. Both the mutation of the proline 473 in the SH3 domain of Rvs167p and the deletion of the proline-rich regions of Gyp5p and Gyl1p disrupt the interaction of Rvs167p with Gyp5p and Gyl1p and impair the localization of Rvs167p to the tips of small buds. Electron microscopy experiments unraveled an accumulation of secretory vesicles in small buds of rvs167Δcells and β-1,3-endoglucanase Bgl2p secretion assays showed Bgl2p secretion defects in cultures enriched in small buds at 13°C. In addition, an accumulation of secretory vesicles was observed in Rvs167pP473L strain, and Bgl2p secretion defect were found in strains expressing Gyp5p and Gyl1p deleted of their proline-rich sequences. These results show that Rvs167p plays a role in polarized exocytosis at the small bud stage and that its function in exocytosis depends on its recruitment to the tip of small buds by the RabGAP proteins Gyp5p and Gyl1p
3
Klee, Saskia Kirsten. "The molecular function and regulation of formins in the yeast Saccharomyces cerevisiae Die molekulare Funktion und Regulation von Forminen in der Hefe Saccharomyces cerevisiae /." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964584816.
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Ramalingam, Nagendran. "Diaphanous-related formins." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-106803.
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Kulacz, Wojciech. "Regulation of Inverted Formin-1 (INF1) by Microtubule-Affinity Regulating Kinase 2 (MARK2)." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22801.
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The actin and microtubule cytoskeleton plays a critical role in the establishment of cell polarity. Cell processes like mitosis and migration rely on the reorganization of the cytoskeleton to properly function. One driver of cell polarity is the formin, Inverted Formin-1 (INF1). INF1 is able to induce F-actin formation, activate the Serum Response Factor (SRF) pathway, stabilize microtubules, associate with microtubules, and disperse the Golgi body. Regulation of INF1 is unique, since it does not possess conserved formin regulatory domains. However, INF1 does possess many potential phosphorylation sites. In this study, we demonstrate that INF1’s ability to induce F-actin stress fibers and activate SRF is inhibited by Microtubule-Affinity Regulating Kinase 2 (MARK2). Inhibition of INF1’s actin polymerization activity by MARK2 likely occurs near INF1’s C-terminus. However, MARK2 was unable to inhibit INF1’s ability to stabilize microtubules, associate with microtubules, and disperse the Golgi. Furthermore, we show that INF1 overexpression is associated with primary cilium absence and in some cases, the presence of long cilia, suggesting that INF1 plays a role in primary cilium formation.
6
Cristea, Laura G. "The Expression, Identification and Biochemical Characterization of the Extracellular Domain of Arabidopsis AFH2." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1417707960.
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Kerleau, Mikaël. "Régulation biochimique et mécanique de l'assemblage de filaments d'actine par la formine." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS583/document.
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Pour la cellule, l’assemblage du cytosquelette d’actine joue un rôle central dans son déplacement, sa division ou sa morphogenèse. Cette réorganisation est orchestrée par des protéines régulatrices et des contraintes mécaniques. Savoir comment les combinaisons de ces actions biochimiques et physiques régulent les différentes architectures d’actine reste un véritable défi.La formine protéine est un régulateur essentiel de l’actine. Ancrée à la membrane, elle assemble les filaments d’actine (nucléation et élongation) présents dans des architectures linéaires et non branchées. La formine est impliquée notamment dans la génération de filopodes, protrusions guidant la locomotion cellulaire.Une propriété remarquable est sa capacité à suivre processivement le bout barbé d’un filament qu’elle allonge, tout en stimulant son élongation en présence de profiline. La régulation de cette processivité de la formine est encore à clarifier. C’est une caractéristique importante, intervenant dans le contrôle de la longueur des filaments, dont les connaissances sont à approfondir.L’étude de cette processivité est facilitée par l’utilisation d’un outil microfluidique novateur pour l’étude de la dynamique de multiples filaments individuels d’actine in vitro. Au sein d’une chambre en PDMS, les filaments sont ancrés à la surface par un seul bout, le reste s’alignant avec le flux. Nous pouvons précisément y changer l’environnement biochimique,tandis que la friction visqueuse sur les filaments permet d’exercer une tension contrôlée sur chacun d’entre eux.Simultanément à l’action de la formine au bout barbé, j’étudie l’effet d’autres protéines ou de la vitesse d’élongation sur sa processivité, en mesurant son taux de détachement. Par ailleurs nous pouvons reproduire l’ancrage membranaire cellulaire en attachant spécifiquement nos formines à la surface. Dans la chambre, par l’intermédiaire du filament qu’elle allonge, nous pouvons alors exercer des forces et en étudier l’effet sur la formine.Premièrement, j’ai étudié l’impact de la protéine de coiffe (CP) sur l’activité de la formine au bout barbé. La liaison de ces deux protéines aubout barbé a jusqu’ici été considérée mutuellement exclusive. Nous avons observé qu’elles peuvent toutefois se retrouver simultanément liées au bout barbé, au sein d’un complexe à courte durée de vie. Ce complexe ternaire est capable de stopper l’activité du bout barbé même si l’affinité d’une protéine est réduite par la présence de l’autre. Nous proposons qu’une compétition entre la protéine de coiffe et la formine régule la dynamique du bout barbé dans des architectures où les longueurs doivent être hautement contrôlées.J’ai ensuite étudié l’influence de divers facteurs sur la processivité. La processivité est très sensible à la présence du sel et à la fraction demarquage fluorescent utilisée dans nos expériences. Nous avons également observé l’effet de la vitesse d’élongation, qui peut être modifiée en changeant la concentration en actine ou en profiline. D’une part, l’actine réduit la processivité, à n’importe quelle concentration de profiline. D’autre part, la concentration en profiline augmente cette processivité,indépendamment du taux d’élongation. Cela suggère qu’une incorporation de monomère diminue la processivité, tandis que la profiline, par sa présence au bout barbé, l’augmente.Enfin, la tension exercée sur les formines abaisse fortement la processivité : quelques piconewtons réduisent la processivité de plusieurs ordres de grandeurs. Cet effet, purement mécanique, prédomine sur les facteurs biochimiques. Ces résultats nous indiquent que les contraintes mécaniques de tension joueraient un rôle prédominant dans le contexte cellulaire. Cette étude nous aide à construire un modèle plus complet de l’élongation processive par les formines.En conclusion, ce projet permet de mieux comprendre le fonctionnement moléculaire de la formine, en particulier le mécanisme de l’élongation processive et de sa régulationActin filament assembly plays a pivotal role in cellular processes such as cell motility, morphogenis or division. Elucidating how the actin cytoskeleton is globally controlled remains a complex challenge. We know that it is orchestrated both by actin regulatory proteins and mechanical constraints.The formin protein is an essential actin regulator. Anchored to the cell membrane, it is responsible for the assembly (nucleation and elongation) of actin filaments found in linear and unbranched architectures. It is notably involved in the generation of filopodia protrusions at the leading edge of a motile cell. One important feature is that it processively tracks the barbed end of an actin filament, while stimulating its polymerization in the presence of profilin.Formin processivity and its regulation is not yet completely understood. As an important factor determining the length of the resulting filament, it must be investigated further.A perfect assay to look at formin processivity in vitro is an innovative microfuidics assay coupled to TIRF microscopy, pioneered by the team, to simultaneously track tens of individual filaments. In a designed chamber,filaments are anchored to the surface by one end, and aligned with the solution flow. We can precisely control the biochemical environment of the filaments. Moreover, we can exert and modulate forces on filaments, due to the viscous drag of flowing solutions. By varying chemical conditions during formin action at the barbed end, I investigated how others proteins or the elongation rate can modulate formin processivity, by looking at the detachment rate of formins.Moreover, we can mimic the membrane anchoring in the cell by specifically attaching formins at the surface. In our chamber, through the filament they elongate, we can apply force to formins.In complement to biochemical studies, we then investigate the effect oftension on their processivity.I first investigated the impact of a capping protein on formin action at the barbed end. Their barbed end binding is thought to be mutually exclusive.We measured that the affinity of one protein is reduced by the presence of the other. However we observed they both can bind simultaneously the barbed end, in a transient complex, which block barbed end elongation.Competition of formin and CP would regulate barbed end dynamics in a cell situation where length is tightly controlled.I next studied formin processivity dependence on various parameters. We show that processivity is sensitive to salt and labelling fraction used in our solutions. We also looked at how processivity is affected by the elongation rate, which can either be varied by actin or profilin concentration. On one hand, actin concentration reduces processivity, at any given concentrationsof profilin. On the other hand, raising the concentration of profilin increasesprocessivity, regardless of the elongation rate. This indicates that theincorporation of actin monomers decreases processivity while in contrast,the presence of the profilin at the barbed end increases it.Moreover, tension exerted on formin was observed to largely favor its detachment. In a quantitative matter, the effect of tension prevails over anyothers biochemical factor on processivity : only a few piconewtons decreaseit by several orders of magnitude. This important effect helps us build amore complete model of processive elongation. These results indicate thatmechanical stress is likely to play an important role in a cellular context.In conclusion, this project brings insights into the molecular properties offormin and helps to decipher the mechanism of processive elongation and its regulation
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Shouler, Daniel Reginald. "Expanded forming limit testing for sheet forming processes." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609473.
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Gontijo, Alexandre Bahia. "Estudo e modelagem das dinâmicas estruturais de assembléias de formigas tropicais em diferentes escalas ecológicas." Programa de Pós-Graduação em Ecologia de Biomas Tropicais. Departamento de Biodiversidade, Evolução e Meio Ambiente, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, 2009. http://www.repositorio.ufop.br/handle/123456789/3029.
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A teoria ecológica é construída através de modelos que possam explicar as relações entre organismos e ambiente. No entanto, esta se trata de uma ciência integradora de conhecimentos e beneficiada por abordagens interdisciplinares devido à enorme complexidade observada nos ecossistemas. Nesse contexto, o uso de ferramentas matemáticas tem se mostrado extremamente importante para a compreensão dos sistemas ecológicos. Neste trabalho foram estudadas assembléias de formigas em duas áreas da região neotropical, Caxiuanã (Pará) e Volcan Barva (Costa Rica). A partir da analise de suas dinâmicas populacionais e estruturas de dominância sob diferentes escalas espaciais e ecológicas (composição de gêneros e guildas tróficas), foram desenvolvidos modelos computacionais que permitissem avaliar alguns dos principais modelos de suporte à Ecologia Teórica. Esses modelos buscam explicar tanto as dinâmicas e estruturas populacionais como também os mecanismos e processos por trás da funcionalidade de ecossistemas ditos complexos. Foram observadas diferenças marcantes na estrutura de dominância das populações entre as duas escalas ecológicas consideradas.onde diferentes níveis de informação foram obtidos com cada uma das abordagens. As análises sob a escala de gêneros mostraram grande instabilidade temporal associada a diferenças de configuração hierárquica entre escalas espaciais distintas. Em contrapartida, as análises feitas sob a escala de guildas tróficas evidenciaram comportamentos relativamente mais estáveis quando comparados aos gêneros. Tais resultados foram interpretados a luz de duas teorias principais, o “nicho construtivismo” e “sistemas complexos adaptativos". Por fim, ambas teorias foram atreladas, onde a emersão das funcionalidades do ecossistema com sistemas complexos adaptativos se mostrou possível a partir dos mecanismos de nicho construção. __________________________________________________________________________________________
ABSTRACT: The ecological theory is built on models that can explain the relationships between organisms and their environment. However, if this is a science that integrates knowledge and benefited from interdisciplinary approaches due to the enormous complexity observed in ecosystems. In this context, the use of mathematical tools has been extremely important for the understanding of ecological systems. In this study ant assemblages in two areas of the Neotropics, Caxiuanã (Pará) and Volcan Barva (Costa Rica). From the analysis of their population dynamics and structures of dominance under different spatial scales and ecological (gender composition and feeding guilds) were developed computer models that help to assess some of the main support models to Theoretical Ecology. These models seek to explain both the dynamics and population structure but also the mechanisms and processes behind the functionality of so-called complex ecosystems. Considerable differences were observed in the structure of dominance of populations between the two ecological scales with different levels of information were obtained with each approach. The analysis under the range of genres showed great temporal instability associated with differences in configuration hierarchy between different spatial scales. In contrast, the analysis done under the range of feeding guilds showed relatively more stable behavior compared to those genres. These results were interpreted in light of two main theories, the "niche constructivism" and "complex adaptive systems." Finally, both theories have been linked, where the emergence of the features of the ecosystem with complex adaptive systems proved possible from the mechanisms niche construction.
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Grasty, Lawrence Victor. "Shot peen forming." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260449.
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Ellison, Samuel C. "Forming Ritual Reality." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282576025.
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Sanay, Berkay. "Prediction Of Plastic Instability And Forming Limits In Sheet Metal Forming." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612486/index.pdf.
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The Forming Limit Diagram (FLD) is a widely used concept to represent the formability of thin metallic sheets. In sheet metal forming processes, plastic instability may occur, leading to defective products. In order to manufacture defect free products, the prediction of the forming limits of sheet metals is a very important issue. FLD&rsquos can be obtained by several experimental, empirical and theoretical methods. However, the suitability and the accuracy of these methods for a given material may vary. In this study, FLD&rsquo
s are predicted by simulating Nakazima test using finite element software Pam-Stamp 2G. Strain propagation phenomenon is used to evaluate the limit strains from the finite element simulations. Two different anisotropic materials, AA2024-O and SAE 1006, are considered throughout the study and for each material, 7 different specimen geometries are analyzed. Furthermore, FLD&rsquo
s are predicted by theoretical approaches namely
Keeler&rsquo
s model, maximum load criteria, Swift-Hill model and Storen-Rice model. At the end of the study, the obtained FLD&rsquo
s are compared with the experimental results. It has been found that strain propagation phenomenon results for SAE 1006 are in a good agreement with the experimental results
however it is not for AA2024-O. In addition, theoretical models show some variations depending on the material considered. It has been observed that forming limit prediction using strain propagation phenomena with FE method can substantially reduce the time and cost for experimental work and trial and error process.
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Kamal, Manish. "A uniform pressure electromagnetic actuator for forming flat sheets." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1127230699.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xxi, 261 p.; also includes graphics (some col.). Includes bibliographical references (p. 244-254). Available online via OhioLINK's ETD Center
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Tangirala, Sailesh Kumar. "EXPERIMENTAL AND NUMERICAL INVESTIGATION OF PLASMA-JET FORMING." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_theses/361.
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Sheet metal forming has found increasing applications in modern industries. To eliminate use of expensive tools during product development, thermal forming, a rapid prototyping process that is flexible enough to decrease costs has been developed. Thermal forming processes use a heat source to perform the required deformation mainly by creating a thermal difference along the thickness of the sheet. Gas flames, lasers and plasma heat sources have been used for sheet metal bending by thermal forming. An alternative to laser and gas flames, plasma-jet forming has been developed that uses a non-transferred plasma arc as a heat source. The plasma-jet forming system uses a highly controllable non-transferred plasma torch as a heat source to create the necessary thermal gradient in the sheet metal that causes the required plastic deformation. Various experiments to produce simple linear bends and other complex shapes have been conducted by using different scanning options and coupling techniques. A computer simulated model using finite element method is being developed to study key parameters affecting this process and also to measure the thermal transient temperature distribution during the process. A predictive model to relate the deformation to the temperature gradient for various materials is being developed. Simulation results that are in accordance to experimental observations will further improve this material forming process to be highly controllable and more accurate
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Bailleul, Carine Alice. "High-speed film forming." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/19129.
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Ali, Ahmed. "Incremental sheet metal forming." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0020/MQ54441.pdf.
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Tabatabai, Mohammad Reza Majdzadeh. "Dominant channel forming discharge." Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389364.
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Stones, P. A. "New ring forming reactions." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373984.
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Karvinen, T. (Tuulikki). "Ultra high consistency forming." Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526222639.
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Abstract This study focused on web forming at a 5–10% consistency range, termed Ultra High Consistency (UHC). The study continued work done by Gullichsen with his research groups (1981–2007) and combined it with the HC forming research done by Valmet (HC, 1999–2004). The hypothesis was that by utilizing a rotor to fluidize suspension and a wedge to eliminate the free jet and thus prevent reflocculation, web forming at UHC is feasible at commercial speeds. The research method was experimental. The bulk of the research was conducted at pilot scale. A new UHC headbox was designed and mounted on a pilot former. The key elements of the headbox are the rotor and the wedge. As fluidization forms the base for UHC forming, this was evaluated at the pilot former using image analysis. In addition, fluidization was studied using a laboratory-scale device. Besides basic paper analysis, X-ray microtomography and sheet splitting methods were utilized to analyze the sheet structure. The results show that forming is possible within the focus area, 5–10% consistency and machine speeds of 150–600 m/min, although the operation potential of the UHC former is even wider. The results demonstrate that the wedge is needed for successful UHC forming, but the rotor is not required, providing the flow rate is sufficiently high. This indicates that various forces induced by the flow itself can be adequate to fluidize suspension for forming. The critical Reynolds number of full fluidization was found to be 200–250. The Reynolds numbers were estimated utilizing the linear dependencies found between the apparent viscosity and consistency, using the maximum mean flow velocities inside the headbox, and neglecting the possible rotation of the rotor. The corresponding critical flow velocities at 10% consistency are 12 and 19 m/s for a eucalyptus and pine pulp. The velocities are on average 70 and 60% lower than those given in the literature (40–50 m/s). The results reveal that the fiber orientation of UHC sheets is planar, the floc size of the web increases with consistency, the internal bond increases linearly with the floc size, and the tensile strength appears to decrease with increasing floc size. In consequence, it is postulated that the increase in the out-of-plane strength at the expense of in-plane strength with the consistency increase results from a more flocculated structureTiivistelmä Tutkimus keskittyi rainanmuodostukseen 5–10 % sakeudessa. Sakeusalue nimitettiin ultra korkeaksi (lyhenne UHC). Tämä työ jatkoi Gullichsenin ja hänen tutkimusryhmiensä tutkimustyötä (1981–2007) ja samalla yhdisti sen Valmetin tekemään suursakeusrainaustutkimukseen (HC, 1994–2004). Työn hypoteesina oli, että käyttämällä roottoria massan fluidisoimiseen sekä ns. wedgeä eliminoimaan vapaa suihku ja estämään jälleenflokkaantuminen, rainanmuodostus UHC-sakeudessa on mahdollista kaupallisissa nopeuksissa. Tutkimusmetodi oli kokeellinen. Pääosa tutkimuksesta suoritettiin koekonemittakaavassa. Uusi UHC-perälaatikko suunniteltiin ja asennettiin koeformeille. Perälaatikon pääelementit ovat pyörivä roottori ja wedge. Koska fluidisointi muodostaa UHC-rainauksen perustan, fluidisointia evaluoitiin koekoneella käyttäen kuva-analyysiä sekä tutkittiin lisäksi käyttäen röntgenmikrotomografia ja arkin halkaisu -metodeja. Tulokset osoittavat, että rainaaminen on mahdollista määritellyllä fokusalueella, 5–10 %sakeudessa ja konenopeudella150–600 m/min, joskin UHC-formerin toimintapotentiaali on vieläkin laajempi. Tulokset osoittavat, että wedge tarvitaan onnistuneeseen UHC-muodostamiseen, mutta roottoria ei tarvita, mikäli virtausnopeus on riittävän suuri. Tämä tarkoittaa, että virtauksen aikaansaamat voimat voivat itsessään olla riittäviä massan fluidisoimiseksi rainaamista varten. Täyden fluidisaation kriittisen Reynoldsin luvun havaittiin olevan välillä 200–250. Reynoldsin luvut arvioitiin käyttäen löydettyjä viskositeetin ja sakeuden välisiä lineaarisia riippuvuuksia, päävirtauksen maksiminopeuksia perälaatikossa ja jättäen huomioon ottamatta mahdollinen roottorin pyöriminen. Reynoldsin lukuja vastaavat kriittiset virtausnopeudet 10 % sakeudessa ovat eukalyptus- ja mäntymassalla 12 ja 19 m/s. Nopeudet ovat keskimäärin 70 ja 60 % pienempiä kuin kirjallisuudessa annetut (40–50 m/s). Tulokset osoittavat, että UHC-arkeissa kuituorientaatio on tasomainen, rainan flokkikoko kasvaa sakeuden kasvaessa, palstautumislujuus kasvaa lineaarisesti flokkikoon kanssa ja vetolujuus näyttäisi laskevan flokkikoon kasvaessa. Näin ollen esitetään, että sakeuden kasvaessa tapahtuva palstautumislujuuden kasvu tasolujuuksien kustannuksella johtuu flokkaantuneemmasta rakenteesta
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Gearing, Brian P. (Brian Paul) 1972. "Friction in sheet forming." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9413.
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Hayakawa, Tomoyasu. "Black-Hole forming Supernovae." Kyoto University, 2020. http://hdl.handle.net/2433/253091.
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McSorley, Charles P. "Forming A Culinary Architecture." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9662.
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Architecture seeks to find harmony between pragmatics and poetics through phenomenological relationships of tectonics, placement, and culture. The choreography of these events, both physical and metaphysical,leads to a depth in the art of place making. The act of building in a certain way or attitude is read as aphorism – the statement imbedded in the physical existence of a construction is manifest in the way which its existence is made.
We (civilization) make both out of physical need and desire,the question in art is whether our motive is purely physical or becomes spiritual. How is institution achieved? What defines place and how is it made? Does tradition bind us to the past or is it the freedom to inform the present and beyond ?Master of Architecture
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Pie, Marcio Roberto. "Ecologia comportamental de Ectatomma opaciventre (Formicidae, Ponerinae) : forrageamento e organização social." [s.n.], 1998. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316170.
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Orientador: Paulo Sergio Moreira Carvalho de OliveiraDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A formiga Ectatomma opaciventre possui atividade de forrageamento exclusivamente diurna, restringindo a atividade durante as horas mais quentes do dia. A sua dieta é tipicamente omnívora, com cupins e formigas como os ítens mais importantes. Ao contrário de outras Ectatomma, não foi registrado nenhum caso de coleta de néctar extrafloral ou exsudato de homópteros. As operárias mostraram fidelidade individual de rota, mas os caminhos não foram tão precisos e estáveis como nos casos já descritos para outros poneríneos. A estratégia de forrageamento empregada por E. opaciventre foi o forrageamento individual, ou seja, não houve cooperação entre forrageadoras na busca ou coleta de itens alimentares, tanto por deposição de trilhas químicas como por tandem. Apesar da distribuição espacial dos ninhos mostrarem uma tendência significativa à distribuição regular, os ninhos tenderam a ocorrem em microhábitats específicos. O repertório comportamental de uma colônia madura foi descrito. Vinte e oito diferentes atos comportamentais foram registrados a partir de 4538 registros individuais. Houve evidência de polietismo temporal, com operárias mais jovens realizando significativamente mais cuidado à prole e limpeza social do que operárias adultas. E. opaciventre apresenta uma forma organizada de relocação de ninhos, com algumas operárias especializando-se em transportar outras formigas adultas. A postura de carregamento é similar à encontrada em outros poneríneos, embora algumas características peculiares foram detectadas
Abstract: The ant Ectatomma opaciventre is exc1usively diurnal, restraining theforaging activity at midday. The diet is typically omnivorous, where termites workers and leaf-cutting ants were the most important food items. Contrary to other Ectatomma species, no liquid food like homopteran honeydew or plant nectar was collected. The foragers showed individual foraging area fidelity, but the paths were not so precise and stable as reported for other ponerine species. The foraging strategy employed by E. opaciventre was ofindividual foraging, i.e., there was no cooperation between foragers in the search for or retrieval of food, neither by tandem running nor by trail laying. Even though the spatial distribution of nests showed significant hyperdispersion, the nests tended to occur in specific microenvironments. The behavioral repertoire of a mature colony is described. Twenty eight different behavioral acts were recorded from 4538 individual records. There was evidence oftemporal polyethism, with young workers performing significantly more brood care and allogrooming than older workers. E. opaciventre shows an organized form of nest relocation, with a few workers specializing in transporting other adult workers. The carrying posture is similar to other ponerines, although some idiosyncratic features are detected.
Mestrado
Ecologia
Mestre em Ciências Biológicas
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Arshad, Saad. "Single Point Incremental Forming : A study of Forming Parameters, Forming limits and Part accuracy of Aluminium 2024, 6061 and 7475 alloys." Thesis, KTH, Industriell produktion, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103006.
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Nowadays there is an increasingly demanding need for the development of agile manufacturing techniques that can easily be adaptable to a constant introduction of new products in the market. Single point incremental forming (SPIF) is a new innovative and feasible solution for the rapid prototyping and the manufacturing of small batch sheet parts. The process is carried out at room temperature (cold forming) and requires a CNC machining centre, a spherical tip tool and a simple support to fix the sheet being formed. This work studied the effects of step size, angle, spindle speed, and feed rate on the forming limits of Aluminium alloys namely AA 2024, AA 6061 and AA 7475 in soft annealed condition. The Study also includes measuring the strain path and determination of maximum forming limit angles for the above mentioned alloys. This thesis provides a better understanding of the influence of rotating tool in the occurrence of fracture without previous necking or fracture following previous necking. Surface and geometric accuracy of the parts manufactured was also studied and comparisons were made between the CAD files and the actual manufactured parts and then corrections were made accordingly. The main contribution of this thesis to Single stage SPIF was the successful manufacturing of a Cone shaped parts with almost vertical walls.
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Mumal, Iqra. "The Role of Formins in Endothelial Adherens Junction Regulation." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34274.
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Adherens junctions are cadherin-dependent structures that mediate intercellular
signaling and structural integrity of the endothelial barrier. Formins are a highly
conserved family of cytoskeletal remodeling proteins whose activity has been implicated
in regulating adherens junction formation in other cell-types. Therefore, we tested the
hypothesis that formin activity is essential for adherens junction assembly in endothelial
cells. A small-molecule formin inhibitor (smiFH2) was used to determine the effect of
formin inhibition on junction formation using an in vitro vascular permeability assay. We
determined that smiFH2 treatment caused a dose-dependent inhibition of junction
formation. We used siRNAs to knockdown expression of the seven formins shown to be
expressed in TIME cells and determined that individual knockdown of FHOD1, FHOD3
and Dia1 significantly increased the permeability of the endothelial monolayer.
Interestingly, FMNL2 knockdown actually potentiated barrier function. Knockdown of
the remaining formins had little or no effect on junction formation. Knockdown of
FHOD3 had the greatest inhibitory effect on junction assembly; VE-cadherin protein
levels were decreased in FHOD3-depleted cells. The FHOD3 knockdown cells were also
elongated in comparison to controls and formed thin linear adherens junctions and few
focal adherens junctions. In contrast, the morphology of FMNL2-depleted cells did not
appear obviously different from controls. In conclusion, our results suggest that multiple
formins play diverse roles in adherens junction formation and maintenance in endothelial
cells.
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Lindgren, Michael. "Experimental and computational investigation of the roll forming process." Doctoral thesis, Luleå : Division of Material Mechanics, Luleå University of Technology, 2009. http://pure.ltu.se/ws/fbspretrieve/3340038.
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Pic, Mireille. "Fatores locais estruturadores da riqueza de espécies de formigas arborícolas em cerrado." Universidade Federal de Viçosa, 2001. http://www.locus.ufv.br/handle/123456789/11161.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Comunidades estruturadas por fatores locais são limitadas pelas interações biológicas, ou pelos recursos e pelas condições existentes no habitat. Com a finalidade de se testar a influência de fatores locais em comunidades de formigas arborícolas, buscou-se determinar se (i) a riqueza, o volume da vegetação e a heterogeneidade do habitat influenciam a diversidade das comunidades de formigas e se (ii) existe alguma evidência de competição entre espécies de formigas e se esta competição é uma importante força estruturadora destas comunidades. As coletas de formigas foram realizadas em 300 árvores, distribuídas dentro de 30 parcelas de 20 x 50 m, na Área de Proteção Ambiental (APA) Gama-Cabeça-de-Veado. As formigas foram amostradas por meio de coleta manual e com pitfalls colocados nas árvores. Em cada parcela, foram amostrados todos os indivíduos lenhosos com diâmetro superior a 5 a 30 cm do solo. Para analisar a influência das variáveis da vegetação sobre a riqueza de espécies de formigas arborícolas, utilizaram-se análises de regressão simples, em que a variável resposta foi sempre a riqueza da comunidade de formigas e a variável explicativa, cada uma das variáveis da vegetação anteriormente descritas. Não foi encontrada relação significativa entre a riqueza da vegetação arbórea e a riqueza de espécies de formigas e entre a heterogeneidade da estrutura do habitat e a riqueza de espécies de formigas. Esses resultados sugerem que as formigas arborícolas podem ser principalmente generalistas tanto em relação aos recursos quanto ao habitat. O volume da vegetação influenciou positivamente a riqueza de espécies de formigas nas parcelas. Para explicar essa relação, foi sugerida a seguinte hipótese: maior volume da vegetação significa maior quantidade de recursos disponíveis e condições microambientais mais adequadas. Essa maior quantidade de recursos e condições mais adequadas poderá favorecer a entrada de novas espécies, em vez de favorecer o aumento das populações já existentes. Os resultados deste trabalho indicam que a quantidade de recursos pode ser limitante nessas comunidades de formigas arborícolas. A fim de verificar se existem evidências de competição nessas comunidades, utilizou-se uma análise de modelos nulos de co-ocorrência. Essas análises foram feitas em duas escalas: parcela e árvores. A análise das comunidades de formigas da parcela indicou que as espécies destas comunidades ocorrem independentemente umas das outras, sugerindo que a parcela não representa a unidade espacial que as formigas utilizam como território. A análise de modelos nulos das comunidades de formigas em árvores detectou que estas são estruturadas por fatores biológicos. O padrão obtido pode estar relacionado a três processos: históricos ou filogenéticos, especialização das formigas quanto ao habitat e competição interespecífica. Como a quantidade de recursos para formigas arborícolas em cerrado pode ser limitante, conclui-se que a competição pode ser a força estruturadora dessas comunidades.
Communities structured by local factors are limited by biologic interactions or by the resources and conditions which exist in the habitat. In order to test the influence of local factors in communities of arboricole ants, there was on attempt to determine if (i) the richness, the vegetation volume and the habitat heterogeneity influence the diversity of the ant communities, and if (ii) there is some evidence of competition among ant species and if this competition is a main force of structuration of these communities. Collection of ants was done on 300 trees distributed in 30 plots with 20 x 50 m, in the Environmental Protection Area (APA) called Gama-Cabeça-de-Veado. The ants were sampled through manual collection and pitfalls placed on the trees. In each plot, all the woody individuals with a diameter of more than 5 cm at 30 cm of ground level were sampled. To analyse the influence of the vegetation variables upon the species richness of arboricole ants, simple regression analyses were used, where the response variable always was the richness of ant communities, and the explicative variable was each of the variables of the vegetation above described. A significant relation was not found between the richness of arboreous vegetation and the richness of ant species, and between the heterogeneity of the habitat structure and richness of species of ants. These results suggest that the arboricole ants could be mainly generalist both in relation to the resources and the habitat. The volume of vegetation influenced positively the richness of ant species in the plots. To explain this relation, the author suggests the following hypothesis: a greater volume of vegetation signifies a greater amount of available resources and more suitable microenvironmental conditions. This greater amount of resources and more suitable conditions can favour the entrance of new ant species instead of favouring an increase of the already existent populations. The results of this work indicate that the amount of resources can be a limitant factor for these communities of arboricole ants. To verify if there is evidence of competition in these communities analysis of nul models of co-occurrence were used. These analyses were done in two scales: plot and trees. The analysis of ant coomunities in the plot indicated that the species of these communities occur independent of one or of the others, suggesting that the plot does not represent the spatial unit that the ants use as territory. The analysis of nul models of the ant communities on trees detected that these communities are structured by biologic factors. The pattern obtained could be related to three processes: historic or phyllogenetic, specialization of the ants to the habitat and interspecific competitions. As the amount of resources for arboricole ants in the cerrado can be limitant, it can be concluded that the competition could be the force which structures these communities.
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Cao, Jian Ph D. Massachusetts Institute of Technology. "Design and control of forming parameters for sheet metal forming using finite element analysis." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11776.
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Karlsson, Mikael. "Beam-Forming-Aware Link-Adaptation for Differential Beam-Forming in an LTE FDD System." Thesis, Linköpings universitet, Kommunikationssystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-129109.
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The ability for base stations to be able to beam-form their signals, directing the signal energy to specific users, is a topic of research that has been heavily studied during the last decades. The beam-forming technique aims to increase the signal-to-interference-and-noise-ratio of the user and, consequently, increase the capacity and coverage of the communication system. One such method is the Differential Beam-Forming technique, that has been developed at Ericsson Research. In this version of beam-forming, the beams can be dynamically sharpened and widened when tracking a specific terminal, to try to optimize the signal energy sent to that terminal. Beam-forming, however, makes the link-adaptation algorithm process substantially harder to perform. The reason for this is that the link-adaptation algorithm now has to take into account not only the changing radio environment, but also the changing transmit signal that is being beam-formed. Fortunately, since the beam-formed signal is known at the point of transmission, there should be a potential to utilize this knowledge to make the link-adaptation more efficient. This thesis, investigates how the link-adaptation algorithm could be changed to perform better in beam-forming setups, as well as what information from the beam-forming algorithm that could be included and utilized in the link-adaptation algorithm. This is done by designing and investigating three new link-adaptation algorithms, in the context of Differential Beam-Forming in an LTE FDD system. The algorithms that has been designed are both of a beam-forming-aware and beam-forming-unaware character, meaning if the beam-forming information is utilized within the algorithm, or not. These algorithms have been simulated for different base station antenna array-sizes. Unfortunately, due to simulator restrictions, the terminals have been simulated in a stationary environment, which has proven to be a limiting factor for the results. However, the results still show that smarter beam-forming-aware link-adaptation could possibly be used to increase the performance of the link-adaptation when using beam-forming.
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Bution, Murillo Lino [UNESP]. "Morfologia do trato digestivo de formigas." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/99488.
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A presença de microorganismos no trato digestivo de formigas da tribo Cephalotini (Subfamília Myrmicinae) e do gênero Dolichoderus (Subfamília Dolichoderinae), tem sido motivo de várias especulações entre os mirmecologistas. Entretanto não existem dados sobre muitas das características da relação destes microorganismos descobertos a menos de 25 anos, principalmente no que concerne os aspectos histoquímicos, enzimológicos e também ultramorfológicos. Assim sendo, foram realizados estudos comparados do proventrículo, ventrículo e do íleo de três espécies pertencentes ao gênero Cephalotes: C. atratus, C. clypeatus e C. pusillus, e do ventrículo de uma espécie do gênero Dolichoderus: Dolichoderus (=Monacis) bispinosus, objetivando buscar relações entre as espécies, assim como, diferenças enzimológicas e histoquímicas tanto da parede como do conteúdo de destas porções do trato digestivo, que possam ser utilizadas para a compreensão da função intestinal, bem como esclarecer quais e como os recursos alimentares são aproveitados em cada parte do trato digestivo. Das espécies de Cephalotes foram feitas análises ultramorfológicas. Os resultados tanto de natureza enzimológica quanto de natureza histoquímica de todas as regiões estudadas, apresentaram o mesmo padrão para todas as espécies. De 2 mesma maneira, a secreção das células digestivas colunares para todas as espécies estudadas, foi considerada como do tipo apócrino. Na tribo Cephalotini (Myrmicinae) e em Dolichoderus (=Monacis) bispinosus (Dolichoderinae) o pH levemente ácido presente tanto no lúmen do ventrículo, quanto no lúmen do íleo, permite a sobrevivência dos microorganismos nestas regiões do trato digestivo.
The presence of microorganisms in the digestive tract of Cephalotini tribe (subfamilly Myrmicinae) and Dolichoderus (subfamily Dolichoderinae) ants has been causing several speculations among the myrmecologists. However, the data concerning the relationship of these microorganisms (discovered less than 25 years ago) to the ants are scarce at the histochemical, enzymological and ultramorphological point of view. Thus, we carried out studies on the proventriculus, midgut and ileum in three species of Cephalotes (C. atratus, C, clypeatus and C. pusillus) and the midgut of Dolichoderus (=Monacis) bispinosus. The histochemical and enzymological aspects of the epithelium of these structures and their contents were compared among these species. We tried to understand the function of these organs and establish how each of them takes advantage of the alimentary sources. Some ultramorphological studies were also carried out in Cephalotini. The enzymological and histochemical techniques showed that each studied organ presented the same pattern when compared among species. In the same way, the secretion 4 of the digestive cells was also similar. Besides, all of these digestive cells were classified as apocrine. In Dolichoderus (=Monacis) bispinosus and all species of Cephalotini studied the slightly acid pH allows the survival of the microorganisms as in the midgut lumen, as in ileum's lumen. We propose that, in Cephalotini, the stability of the pH is related to the intensive secretion of Ca++ by the digestive cells in the midgut. The morphological adaptations of the ileum in Cephalotini tribe provide high supply of oxygen and metabolites that also explain the strong presence of microorganisms in this region. Besides it, the absorptive and digestive capacity of this epithelium indicates that it could be a very specialized region adapted to maintain microorganisms.
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Bution, Murillo Lino. "Morfologia do trato digestivo de formigas /." Rio Claro : [s.n.], 2006. http://hdl.handle.net/11449/99488.
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Resumo: A presença de microorganismos no trato digestivo de formigas da tribo Cephalotini (Subfamília Myrmicinae) e do gênero Dolichoderus (Subfamília Dolichoderinae), tem sido motivo de várias especulações entre os mirmecologistas. Entretanto não existem dados sobre muitas das características da relação destes microorganismos descobertos a menos de 25 anos, principalmente no que concerne os aspectos histoquímicos, enzimológicos e também ultramorfológicos. Assim sendo, foram realizados estudos comparados do proventrículo, ventrículo e do íleo de três espécies pertencentes ao gênero Cephalotes: C. atratus, C. clypeatus e C. pusillus, e do ventrículo de uma espécie do gênero Dolichoderus: Dolichoderus (=Monacis) bispinosus, objetivando buscar relações entre as espécies, assim como, diferenças enzimológicas e histoquímicas tanto da parede como do conteúdo de destas porções do trato digestivo, que possam ser utilizadas para a compreensão da função intestinal, bem como esclarecer quais e como os recursos alimentares são aproveitados em cada parte do trato digestivo. Das espécies de Cephalotes foram feitas análises ultramorfológicas. Os resultados tanto de natureza enzimológica quanto de natureza histoquímica de todas as regiões estudadas, apresentaram o mesmo padrão para todas as espécies. De 2 mesma maneira, a secreção das células digestivas colunares para todas as espécies estudadas, foi considerada como do tipo apócrino. Na tribo Cephalotini (Myrmicinae) e em Dolichoderus (=Monacis) bispinosus (Dolichoderinae) o pH levemente ácido presente tanto no lúmen do ventrículo, quanto no lúmen do íleo, permite a sobrevivência dos microorganismos nestas regiões do trato digestivoAbstract: The presence of microorganisms in the digestive tract of Cephalotini tribe (subfamilly Myrmicinae) and Dolichoderus (subfamily Dolichoderinae) ants has been causing several speculations among the myrmecologists. However, the data concerning the relationship of these microorganisms (discovered less than 25 years ago) to the ants are scarce at the histochemical, enzymological and ultramorphological point of view. Thus, we carried out studies on the proventriculus, midgut and ileum in three species of Cephalotes (C. atratus, C, clypeatus and C. pusillus) and the midgut of Dolichoderus (=Monacis) bispinosus. The histochemical and enzymological aspects of the epithelium of these structures and their contents were compared among these species. We tried to understand the function of these organs and establish how each of them takes advantage of the alimentary sources. Some ultramorphological studies were also carried out in Cephalotini. The enzymological and histochemical techniques showed that each studied organ presented the same pattern when compared among species. In the same way, the secretion 4 of the digestive cells was also similar. Besides, all of these digestive cells were classified as apocrine. In Dolichoderus (=Monacis) bispinosus and all species of Cephalotini studied the slightly acid pH allows the survival of the microorganisms as in the midgut lumen, as in ileum's lumen. We propose that, in Cephalotini, the stability of the pH is related to the intensive secretion of Ca++ by the digestive cells in the midgut. The morphological adaptations of the ileum in Cephalotini tribe provide high supply of oxygen and metabolites that also explain the strong presence of microorganisms in this region. Besides it, the absorptive and digestive capacity of this epithelium indicates that it could be a very specialized region adapted to maintain microorganisms
Orientador: Flávio Henrique Caetano
Coorientador: Fernando José Zara
Banca: Vera Nisaka Solferini
Banca: Maeli Dal Pai Silva
Mestre
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Dehra, Mala Seth. "High velocity formability and factors affecting it." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1143214139.
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Raithatha, Ankor Mahendra. "Incremental sheet forming : modelling and path optimisation." Thesis, University of Oxford, 2008. http://ora.ox.ac.uk/objects/uuid:89b0ac1e-cab4-4d80-b352-4f48566c7668.
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Incremental sheet forming (ISF) is a novel metal shaping technology that is economically viable for low-volume manufacturing, customisation and rapid-prototyping. It uses a small tool that is controlled by a computer-numerically controlled sequence and the path taken by this tool over the sheet defines the product geometry. Little is currently known about how to design the tool-path to minimise geometric errors in the formed part. The work here addresses this problem by developing a model based tool-path optimisation scheme for ISF. The key issue is how to generate an efficient model for ISF to use within a path optimisation routine, since current simulation methods are too slow. A proportion of this thesis is dedicated to evaluating the applicability of the rigid plastic assumption for this purpose. Three numerical models have been produced: one based on small strain deformation, one based on limit analysis theory and another that approximates the sheet to a network of rods. All three models are formulated and solved as second-order cone programs (SOCP) and the limit analysis based model is the first demonstration of an upper-bound shell finite element (FE) problem solved as an SOCP. The models are significantly faster than commercially available FE software and simulations are compared with experimental and numerical data, from which it is shown the rigid plastic assumption is suitable for modelling deformation in ISF. The numerical models are still too slow for the path optimisation scheme, so a novel linearised model based on the concept of spatial impulse responses is also formulated and used in an optimal control based tool-path optimisation scheme for producing axisymmetric products with ISF. Off-line and on-line versions of the scheme are implemented on an ISF machine and it is shown that geometric errors are significantly reduced when using the proposed method. This work provides a new structured framework for tool-path design in ISF and it is also a novel use of feedback to compensate for geometrical errors in ISF.
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Woodward, Steven T. "Springback Calibration of Sheet Metal Components Using Impulse Forming Methods." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306683543.
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Gåård, Anders. "Wear in sheet metal forming." Licentiate thesis, Karlstad University, Faculty of Technology and Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1592.
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The general trend in the car body manufacturing industry is towards low-series production and reduction of press lubricants and car weight. The limited use of press lubricants, in combination with the introduction of high and ultra-high strength sheet materials, continuously increases the demands of the forming tools. To provide the means of forming new generations of sheet material, development of new tool materials with improved galling resistance is required, which may include tailored microstructures, introducing of specific(MC, M(C,N))carbides and nitrides, coatings and improved surface finish. In the present work, the wear mechanisms in real forming operations have been studied and emulated on a laboratory scale by developing a test equipment. The wear mechanisms identified in the real forming process, were distinguished into a sequence of events consisting of initial local adhesive wear of the sheets resulting in transfer of sheet material to the tool surfaces. Successive forming operations led to growth of the transfer layer and initiation of scratching of the sheets. Finally, scratching changed into severe adhesive wear, associated with gross macroscopic damage. The wear process was repeated in the laboratory test-equipment in sliding between several tool materials, ranging from cast iron to conventional ingot cast tool steels to advanced powder metallurgy tool steel, against dual-phase carbon steel sheets. By use of the test-equipment, selected tool materials were ranked regarding wear resistance in sliding against ferritic-martensitic steel sheets at different contact pressures.
Wear in sheet metal forming is mainly determined by adhesion; initially between the tool and sheet surface interaction and subsequently, after initiation of material transfer, between a sheet to sheet contact. Atomic force microscopy force curves showed that adhesion is sensitive to both chemical composition and temperature. By alloying of iron with 18wt.% Cr and 8wt.% Ni, alloying in itself, or changes in crystal structure, led to an increase of 3 times in adhesion at room temperature. Hence, alloying may be assumed a promising way for control of adhesive properties. Additionally, frictional heating should be controlled to avoid high adhesion as, generally, adhesion was found to increase with increasing temperature for all investigated materials.
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Bewlay, B. P. "The spray forming of alloys." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382684.
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Grant, Patrick S. "Spray forming of aluminium alloys." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302790.
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Muhamad, N. "Modelling of spray forming process." Thesis, Swansea University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638270.
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This thesis reports the results of a theoretical investigation into the Osprey Preform Process. It focuses on the fluid and heat transfer phenomena associated with the liquid metal spray, the billet buildup and the solidification behaviour of the metal as the preform is produced. In the first part of the study, a nonlinear lumped parameter numerical model has been developed to model the physical processes taking place in the two phase spray and both fluid and thermal influences have been addressed. The analyses show the importance of the momentum exchange with the entrained gas on both velocity profiles and the temperature histories of the spray and this reflects the need to consider the total thermal design of the deposition chamber. The effect of a small amount of undercooling was also included where it was found to result in a wetter spray arriving at the deposit. The above model was incorporated in the buildup simulation for a cylindrical billet deposited onto a substrate having an axis in the horizontal plane. A series of sensitivity studies were carried out to assess the influence of some of the important chamber parameters which are mainly concerned with the position and movement of the scanner and the substrate under the spray. Although a direct comparison between the predicted billet shape and those manufactured was not posible due to the absence of data, the analyses confirmed the significant parameters which influence the billet shape produced and which have to be optimised in actual practice. These findings are compatible with the experience of Osprey Metal Ltd. Finally, the solidification history of the billet preform was analysed using a two dimensional thermal network method. It was found that the thermal history of the billet is sensitive to the thermal boundary conditions applied. Therefore, an appropriate choice of the spraying conditions needs to be established to produce uniform material properties throughout the billet extent.
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Deng, Li. "Cyanophages of bloom-forming cyanobacteria." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492570.
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Cyanobacteria are an important and a diverse group of photo synthetic prokaryotes found in marine, freshwater and terrestrial environments. Over the past two decades, research has shown that cyanobacterial community structures are influenced through infection by cyanobacterial viruses (cyanophages). In marine systems cyanophages have been shown to play roles in the mortality of their hosts, as well as in driving the succession and evolution of phenotypes.
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Islam, Yousuf Mahboobul. "A study of injection forming." Thesis, University of Glasgow, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304876.
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Christian, Jeff M. "Preaching as character-forming discourse." Theological Research Exchange Network (TREN), 2007. http://www.tren.com/search.cfm?p050-0159.
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Hoskins, Travis Justin Christopher. "Carbon-carbon bond forming reactions." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29769.
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Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Dr. Christopher Jones; Committee Co-Chair: Dr. Pradeep Agrawal; Committee Member: Dr. Sujit Banerjee; Committee Member: Dr. Tom Fuller. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Gåård, Anders. "Wear in sheet metal forming /." Karlstad : Faculty of Technology and Science, Materials Engineering, Karlstad University, 2008. http://www.diva-portal.org/kau/abstract.xsql?dbid=1592.
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Saunders, Frederick I. "Forming of tailor-welded blanks." Connect to resource, 1994. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1240337228.
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Chen, Chun-Ling Jocelyn 1972. "Forming processes for advanced composites." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/31063.
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Roy, Matthew J. "Rotary forming of cast aluminum." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44789.
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The application of rotary forming to A356 offers a potential improvement in material use, simplified castings and ameliorated fatigue resistance. To investigate the utility of adopting this process industrially, an extensive characterization and modelling effort was undertaken.
The constitutive behaviour of A356 in the as-cast condition was assessed with compression tests performed over a range of deformation temperatures (30-500°C) and strain rates (~0.1-10/s). The flow stress as a function of temperature and strain rate was quantified via an extended Ludwik-Hollomon and Kocks-Mecking framework.
The through-process microstructural effects on A356 subjected to rotary forming at elevated temperatures was also investigated. This was conducted on material at 350°C with an industrially-scaled, purpose-built apparatus, inducing varying levels of spinning deformation. This was also conducted on commercially flow formed material with high levels of deformation at the same temperature. Macro and micro-hardness testing was used to track the changes from the as-cast and as-formed states, as well as following a T6 heat treatment. Further EDX analysis indicate that precipitation aspects of heat treatment is not appreciably affected by forming. Forming was found to principally affect the eutectic-Si particle size, resulting in a finer particle post heat treatment.
An explicit finite element rotary forming model reciprocating experimental forming conditions was developed incorporating the Ludwik-Hollomon description. This forming model was found to be computationally expensive; however, demonstrated reasonable agreement with experimental geometry and phenomena.
In evaluating the effect of forming on fatigue, multiaxial testing of A356-T6 was conducted to apprehend the basic fatigue mechanisms. Endurance limits are found to be generally governed by porosity and maximum principal stress for high cycle fatigue. Uniaxial fatigue tests of both experimentally and commercially formed material showed a 30% increase in endurance limits over unformed material, principally through mitigating porosity.
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Wang, Bo. "Integrated analyses in plastics forming." Thesis, Sheffield Hallam University, 1996. http://shura.shu.ac.uk/19363/.
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This is the thesis which explains the progress made in the analysis, simulation and testing of plastics forming. This progress can be applied to injection and compression mould design. Three activities of plastics forming have been investigated, namely filling analysis, cooling analysis and ejecting analysis. The filling section of plastics forming has been analysed and calculated by using MOLDFLOW and FILLCALC V. software. A comparing of high speed compression moulding and injection moulding has been made. The cooling section of plastics forming has been analysed by using MOLDFLOW software and a finite difference computer program. The latter program can be used as a sample program to calculate the feasibility of cooling different materials to required target temperatures under controlled cooling conditions. The application of thermal imaging has been also introduced to determine the actual process temperatures. Thermal imaging can be used as a powerful tool to analyse mould surface temperatures and to verify the mathematical model. A buckling problem for ejecting section has been modelled and calculated by PATRAN/ABAQUS finite element analysis software and tested. These calculations and analysis are applied to the special case but can be use as an example for general analysis and calculation in the ejection section of plastics forming.
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Hutchinson, Mark Ian. "Bulge forming of tubular components." Thesis, Sheffield Hallam University, 1988. http://shura.shu.ac.uk/19849/.
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The bulge forming process is a method for shaping tubular components using an internal hydrostatic pressure combined with a compressive axial load. Initial investigations involved carrying out an extensive literature survey to determine the components which could be formed and the effects of using lubricants and different tube materials. Die-blocks were designed to produce tee pieces, cross joints and off-set joints, and electronic on-line instrumentation was incorporated so that the forming pressures and loads could be accurately monitored. A series of tests were carried out in the forming of: (1) tee pieces, cross joints and off-set joints from copper tubes of two different wall thicknesses, (2) tee pieces using different types of plungers, (3) tee pieces using die-blocks coated with various lubricants, (4) tee pieces from aluminium, copper and steel tubes, (5) tee pieces using die-blocks with various branch radii. From the resulting components, formed with various combinations of internal pressure and compressive axial load, the limits for a successful forming operation were established. Further analysis of these components was then undertaken to evaluate the effects of the internal pressure and axial load on the bulge height and the wall thickness in the deformation zone. From these results, which have been illustrated graphically, the greatest effect on the resulting bulge can be seen to be the compressive axial load. Theoretical analyses are presented, which predict the wall thickness distribution around the bulge zone and also the axial loads required in the forming process. Comparison of these predictions with the experimental results shows fairly good agreement.
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Bruton, Paul. "Forming of steel polymer laminates." Thesis, Swansea University, 2001. https://cronfa.swan.ac.uk/Record/cronfa42933.
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Beglinger, Jarrod (Jarrod Thomas) 1976. "Forming of advanced composite materials." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/31077.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.Includes bibliographical references (p. 45).
Two significant aspects of advanced composite material forming are examined. First, the fiber deformation of aligned fiber composites formed to double curvature parts is analyzed. Aligned fiber composite lay-ups were formed over hemispherical tools and the fiber deformation was mapped. The data were intended to support the model which predicts trellising of composite fibers in double curvature. The data are, in general, too ambiguous to clearly support this model. Second, springback of woven fiber material-single curvature parts is investigated. A 90° bend was formed for varying laminate lay-ups at varying temperatures via a double diaphragm process. Principal objectives were to qualify the effects of varying lay-ups and temperatures on the net amount of springback observed. The data show that 0/90 woven lay-ups experience more springback than either +45 degree or quasi-isotropic woven lay-ups, and that heating the laminates marginally decreases the springback experienced.
by Jarrod Beglinger.
S.B.