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1
Štefek, Martin. "Analýza využití pokročilých nástrojů v budoucí podobě tržního segmentu elektroenergetiky." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442547.
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The diploma thesis introduces distributed generation in context of future state of electricity markets. The subject of the thesis is to introduce new trends in electricity markets, such as flexibility, prosumers, aggregator and energy communities. Moreover, the thesis describes blockchain technology and its utilization in future state of electricity markets.
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Vasquez, Daniel James. "Flexure-based nanomagnetic actuators." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1383481101&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Haustein, Thomas. "Epithelzellinvasion durch Shigella flexneri." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2002. http://dx.doi.org/10.18452/14711.
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Shigellen sind Erreger der bakteriellen Dysenterie beim Menschen. Ein notwendiger Schritt bei der Pathogenese der Shigellose ist die Invasion von Darmepithelzellen durch das Bakterium. Der Mikroorganismus löst dabei in der Wirtszelle Veränderungen des Aktinzytoskeletts aus, die zur Bildung einer blütenähnlichen Membranstruktur und schließlich zur Internalisierung des Pathogens führen. Diese Umbauvorgänge am Zytoskelett sind abhängig von einem Wirtszellprotein, der kleinen GTPase Rho. Drei Isoformen von Rho (A, B und C) sind beschrieben, deren Aminosäuresequenzen zu etwa 90% identisch sind. Während der Zellinvasion durch Shigella akkumulieren verschiedene Rho-Isoformen an unterschiedlichen Lokalisationen des Invasionskomplexes. Dabei werden RhoA vorwiegend um die eindringenden Bakterienherum, RhoB und RhoC hingegen hauptsächlich in die bakterieninduzierten zellulären Protrusionen rekrutiert. Durch Untersuchung von Rho-Hybridkonstrukten konnte gezeigt werden, daß ein prä-C-terminales, acht Aminosäuren umfassendes Modul die Rekrutierungsmuster von RhoA bzw. RhoC bestimmt. Der Austausch zweier Aminosäuren innerhalb des Moduls führte zu einer Konversion des Rekrutierungsmusters von RhoA. Wir konnten zeigen, daß die Rekrutierung von RhoA vom Funktionszustand der GTPase (Bindung von GTP/GDP) sowie von der Phosphorylierung durch die Proteinkinase A unabhängig ist. Schließlich wurde hier nachgewiesen, daß auch RhoD, das zu RhoA, B und C auf der Primärstrukturebene nur zu etwa 50% homolog ist, an die Bakterieneintrittsstelle rekrutiert werden kann. RhoD folgt dabei dem Rekrutierungsmuster von RhoB und RhoC.Shigella causes bacillary dysentery in humans. Bacterial invasion of enterocytes is an essential step in the pathogenesis of shigellosis. Pathogen-triggered rearrangements of the host cell actin cytoskeleton induce a blossom-like membrane structure for internalisation of the microorganism. Actin remodeling requires activity of the host cell small GTPase rho. Three highly homologous rho isoforms (A, B and C) have been described with amino acid identities of about 90%. During Shigella invasion these rho isoforms accumulate at different sites of the invasion complex. While rhoA is chiefly recruited around entering bacteria, rhoB and rhoC are essentially translocated to the bacteria-induced cellular protrusions. Using a variety of rho hybrid constructs in a HeLa cell transfection-infection assay we were able to show that a pre-C-terminal stretch of eight amino acids determines the recruitment patterns of rhoA and rhoC. Exchange of two amino acids was sufficient for conversion of the rhoA recruitment pattern into a rhoC-like pattern. We could demonstrate that rhoA recruitment is independent of its functional state (GDP- or GTP-bound) or phosphorylation by the proteinkinase A (PKA). Finally, we have shown that rhoD, another member of the rho family which shares only 50% of its primary structure with rhoA, B or C, is also recruited to the bacterial entry site exhibiting a rhoB/C-like pattern of distribution.
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Siu, Leung-kei Kris. "Study on b-lactamases in shigella flexneri isolated in Hong Kong and Shanghai /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18635696.
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Gojuri, Arun. "Stability of End Notched Flexure Specimen." Thesis, Högskolan i Skövde, Institutionen för teknik och samhälle, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-4487.
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This paper deals with two-dimensional Finite Element Analysis of the End Notched Flexure (ENF) specimen. The specimen is known to be unstable if the crack length is shorter than some critical crack length acr. A geometric linear two-dimensional Finite Element (FE) analysis of the ENF specimen is performed to evaluate acr for isotropic and orthotropic elastic materials, respectively. Moreover, the Mode II Energy Release Rate (ERR) JII and the compliance of the specimen are calculated. The influence of anisotropy is studied. Comparisons are made with the results from beam theory. This work is an extension of previous work.
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Ray, Katrina. "The intracellular lifestyle of Shigella flexneri." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516483.
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Bildsten, Erika Margit. "Analysis of novel flexure-based joint." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74423.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 53).
As robots and other actuated mechanisms get smaller, so must their moving parts. A novel flexure-based joint was developed for Squishbot1 by a team at MIT, which can be made small (sub-cm), or much larger. Here, pseudo-rigid-body modeling is used in conjunction with the geometry of the joint mechanism in order to create analytic models of the forces at play in the joint, so as to better enable their design and use. Two mechanisms are analyzed: one in which the flexure is pinned to the moving legs, and one in which it is fixed. Systems of equations are generated for fixed flexure and pinned flexure joints, which are provided for the reader to use in order to develop their own mechanisms, and optimize them to their own applications. The fixed flexure, no leg contact model is tested for a particular configuration, and less than 3% error is found between the experimental and model data. The advancement of small (sub-cm) actuated mechanisms will push forward the development of small robots, and expand the terrains and applications in which robots can work.
by Erika Margit Bildsten.
S.B.
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Siu, Leung-kei Kris. "Study on [beta]-lactamases in shigella flexneri isolated in Hong Kong and Shanghai." Click to view the E-thesis via HKUTO, 1996. http://sunzi.lib.hku.hk/hkuto/record/B31236133.
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Barnett, D. N. "Convection, elasticity and flexure inside terrestrial planets." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596394.
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In this dissertation, the large-scale geophysical behaviour of the Earth, Venus and Mars are compared, using data collected by the Magellan spaceprobe (for Venus) and the Viking and Mars Global Surveyor (MGS) probes (for Mars). Neither Venus nor Mars show evidence of plate tectonics operating at the present day. On Venus, the lack of water means the frictional resistance at faults and the viscous drag on the base of the moving lithospheric plates are too high to be overcome by the driving forces for plate tectonics. The high elastic thickness of Mars results in a large frictional resistance to fault motion, although the faults themselves are probably no stronger than those on the Earth, and means large compressive stresses are required to initiate subduction. The likely high viscosity of the martian mantle, a consequence of its probable dryness and low temperature, may also result in large drag forces on the base of the lithosphere. Plate tectonics may have operated in the past on both planets, providing a possible explanation for the rapid resurfacing of Venus required by the crater counts and the linear magnetic anomalies recently discovered on Mars.
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Chen, Jay-San. "Standardisation of flexure testing of engineering ceramics." Thesis, University of Warwick, 2000. http://wrap.warwick.ac.uk/67042/.
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With the increase in usage of engineering ceramics, a new industrial standard is required in order to evaluate its properties and to perform a fair and just trade. The thesis investigates the faults and omissions of existing work and judges today's requirements thereby constructing a framework with which today's and future standards in flexure testing can be based. The draft standard presented in this thesis covers the three major testing methods for determining the biaxial flexural strength (modulus of rupture) of engineering ceramics. The ring-on-ring, ball-on-ring, and 4-Ball test fixtures were all adopted as standard, since it is known that each of these systems is suited for a particular application and each has different advantages and disadvantages. The three major biaxial test methods prescribed in this draft standard have been devised so that more consistent and accurate test results can be obtained. However, the uncertainty of measurement in flexure testing always exists and needs to be estimated. The estimation of uncertainty in flexure testing in this study is based on the methodology provided in the ISO Guide to the expression of uncertainty in measurement. The results of the estimation showed that the uncertainty in measurement for the biaxial flexure test standard proposed in this thesis is very low compared to the inherent variability of the strength of ceramic materials. It was also found that the applied load, thickness of the disc plate, and random effects are the three major components contributing to the overall uncertainty. The total uncertainty of measurement in biaxial flexure testing can be significantly minimised by the reduction of the uncertainty contributed from these components, especially from random effects.
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D'Arrigo, Paolo. "Control of flexure in large astronomical spectographs." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244064.
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Bry, Madeleine. "Flexure of the lithosphere at foreland basins." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439115.
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Tashiro, Yumiko. "Overproduction of recombinant VirG from Shigella flexneri." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/9097.
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The ability of Shigella flexineri to spread within and between epithelial cells is essential for Shigella infection causing bacillary dysentery. This is a particular problem in the developing world. The movement of Shigella within the host cell requires the accumulation of actin at one pole of the bacterium and the protein VirG is responsible for this function. While the C-terminal domain (β-domain) of VirG is integrated into the outer membrane of Shigella, the N-Terminal domain (α-domain) is exposed on the surface of the bacterium. The β-domain acts as autotransporter of the α-domain. The exposed α-domain has multiple binding partners including N-WASP, Vinculin and IcsB that are required for infection in man and cell to cell spread. To understand the molecular basis of VirG’s activity, it is first necessary to produce the protein in quantity; this study investigates the expression of VirG α-domain in E.coli. The optimum construct corresponded to residues 58-506 of VirG expressed in Rossetta-gami cells.
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Pardo, Mayana Cristina da Silva, and 92-98238-7650. "Identificação de epitopos imunogêncos de Shigella flexneri." Universidade Federal do Amazonas, 2016. http://tede.ufam.edu.br/handle/tede/5968.
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FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas
Shigella sp. is responsible for one of the leading causes of child morbidity and mortality, especially in developing countries. Infection by this bacterium is known as shigellosis or bacillary dysentery, a highly contagious inflammatory diarrhea. Antibiotic therapy against shigellosis has become a challenge due to the increasing resistance to antibiotics presented by clinical isolates. Thus, immunoprophylaxis directed towards the development of vaccines has become a priority for the World Health Organization in the fight against shigellosis. Considering the need to develop new vaccination strategies for the control of shigellosis and the absence of a licensed and safe vaccine, the present work proposed to identify B cell epitopes of the OmpA and FimH proteins of Shigella flexneri with immunogenic potential, using in silico analyzes for the prediction, besides evaluating the humoral response of mice immunized with synthetic peptides that mimic these epitopes. Through the IEDB program, 11 epitopes (5 for OmpA and 6 for FimH) were predicted and the corresponding peptides were synthesized. The 3D structure of these antigens was also constructed to facilitate the prediction of epitopes. Peptides that reacted to the anti-Shigella antiserum were selected for immunization of immunocompetent mice. The anti-peptide antisera P1 (positive control), P2, P3 and P4 were produced and tested against 13 wild isolates of Shigella flexneri, and showed 92.3% (12/13) of recognition by the corresponding epitope in the native protein present in the strains Tested. The most immunodominant epitope was P2 with a statistically significant result (P <0.0422), when the level of recognition of P2 was compared with P1, significant differences were also observed (P <0.0155). The P4 epitope was the second immunodominant epitope and is located in one of the loops on the surface of the OmpA, whereas the P2 epitope which was the most immunodominant is located in the globular domain in the periplasmic space. However, the antibodies produced against the P2 and P4 peptides were able to recognize wild isolates of S. flexneri, this result makes it possible to infer that these peptides have potential for a vaccine candidate.
Shigella sp. é responsável por uma das principais causas de morbidade e mortalidade infantil, especialmente em países em desenvolvimento. A infecção por esta bactéria é conhecida como shigelose ou disenteria bacilar, uma diarreia inflamatória altamente contagiosa. A antibioticoterapia contra shigelose tem se tornado um desafio devido à crescente resistência aos antibióticos apresentada pelos isolados clínicos. Dessa maneira, a imunoprofilaxia direcionada para o desenvolvimento de vacinas tem se tornado prioridade pela Organização Mundial de Saúde no combate a shigelose. Considerando a necessidade de desenvolver novas estratégias de vacinação para o controle da shigelose, uma vez que ainda não existe uma vacina licenciada segura e eficaz, o presente trabalho objetivou identificar epitopos de célula B das proteínas OmpA e FimH de Shigella flexneri com potencial imunogênico, utilizando de análises in silico para a predição, além de avaliar a resposta humoral de camundongos imunizados com peptídeos sintéticos que imitam estes epitopos. Através do programa IEDB foram preditas 11 epitopos (5 para OmpA e 6 para FimH) e os peptídeos correspondentes foram sintetizados. A estrutura 3D desses antígenos também foi construída para facilitar a predição dos epitopos. Os peptídeos que reagiram ao antissoro anti-Shigella, foram selecionados para imunização de camundongos imunocompetentes. Os antissoros antipeptídeos P1 (controle positivo), P2, P3 e P4 foram produzidos e testados contra 13 isolados selvagens de Shigella flexneri, e apresentaram 92,3% (12/13) de reconhecimento pelo epitopo correspondente na proteína nativa presente nas cepas testadas. O epitopo mais imunodominante foi o P2 com resultado estatisticamente significativo (P<0,0422), quando o nível de reconhecimento de P2 foi comparado com P1, diferenças significativas também foram observadas (P<0,0155). O epitopo P4 foi o segundo epitopo imunodominante e está localizado em uma das alças na superfície da OmpA, enquanto o epitopo P2 que foi o mais imunodominante está localizado no domínio globular no espaço periplasmático. Entretanto, os anticorpos produzidos contra os peptídeos P2 e P4 foram capazes de reconhecer os isolados selvagens de S. flexneri, este resultado possibilita inferir que esses peptídeos possuem potencial para um candidato a vacina.
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Hunter, Johnny. "Flexure and rheology of Pacific oceanic lithosphere." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:fee30488-1a30-48ae-b47e-b6dbc4e3d4d6.
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The idea of a rigid lithosphere that supports loads through flexural isostasy was first postulated in the late 19th century. Since then, there has been much effort to investigate the spatial and temporal variation of the lithosphere's flexural rigidity, and to understand how these variations are linked to its rheology. In this thesis, flexural modelling is used to first re-assess the variation in the rigidity of oceanic lithosphere with its age at the time of loading, and then to constrain mantle rheology by testing the predictions of laboratory-derived flow laws. A broken elastic plate model was used to model trench-normal, ensemble-averaged profiles of satellite-derived gravity at the trench-outer rise system of circum-Pacific subduction zones, where an inverse procedure was used to find the best-fit Te and loading conditions. The results show a first-order increase in Te with plate age, which is best fit by the depth to the 400 ± 35 °C plate-cooling isotherm. Fits to the observed gravity are significantly improved by an elastic plate that weakens landward of the outer rise, which suggests that bending-induced plate weakening is a ubiquitous feature of circum-Pacific subduction zones. Two methods were used to constrain mantle rheology. In the first, the Te derived by modelling flexural observations was compared to the Te predicted by laboratory-derived yield strength envelopes. In the second, flexural observations were modelled using elastic-plastic plates with laboratory-derived, depth-dependent yield strength. The results show that flow laws for low-temperature plasticity of dry olivine provide a good fit to the observations at circum-Pacific subduction zones, but are much too strong to fit observations of flexure in the Hawaiian Islands region. We suggest that this discrepancy can be explained by differences in the timescale of loading combined with moderate thermal rejuvenation of the Hawaiian lithosphere.
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Lipinski, Cassandra L. "Surface electromyography of the flexor carpi ulnaris and flexor digitorum superficialis during elbow rehabilitation phases." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo14933330998399.
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Drayton, Alexandra Marjorie. "Cramp Threshold Frequency in a Fatgiued Flexor Hallicus Longus Compared to a Rested Flexor Hallicus Longus." Thesis, North Dakota State University, 2014. https://hdl.handle.net/10365/27401.
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Muscle fatigue is thought to cause a person?s exercise associated muscle cramps (EAMCs). However, there is little support that fatigue is the reason EAMCs occur. We examined if a fatigued muscle would make it more susceptible to an EAMC. Subjects were exposed to a cramping protocol, which included two seconds of stimulation with a minute rest until a muscle cramp was induced. The participant rested for 30 minutes and then completed a fatigue protocol. The subject performed reps of toe curls against a resistance band (sets of 10 curls with a one minute break in between sets) until muscle failure. Following fatigue, participants immediately completed the cramping protocol. Paired t-test analysis revealed that the change in cramp threshold frequency was not statistically significantly different in a fatigued flexor hallicus longus than in a rested flexor hallicus longus (t(9)= 1.69, p > .05). Although not statistically significant, results indicated a difference between the mean cramp threshold frequency in a fatigued flexor hallicus longus (25.80Hz ? 7.33) when compared to a rested flexor hallicus longus (28.20Hz ? 7.91) condition. Fatigue does not play a factor on EAMCs. Future studies should focus on a larger sample size and evaluation of other possible factors that influence EAMCs.
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Berglund, Maria. "Biomolecular Aspects of Flexor Tendon Healing." Doctoral thesis, Uppsala universitet, Handkirurgi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-120304.
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Flexor tendon injuries in zone II of the hand (i.e. between the distal volar crease and the distal interphalangeal joint) can be costly for both the afflicted individual and society because of the high cost of a long rehabilitation period, complicated by tendon ruptures or scarring with adhesion formation, causing impaired range of motion. The aim of the present thesis was to characterize more fully the deep flexor tendon, the tendon sheath and their response to injury in a rabbit model in order to find potential targets to improve the outcome of repair. The intrasynovial rabbit deep flexor tendon differed from the extrasynovial peroneus tendon in the expression of collagens and transforming growth factor-β1 gene expression. Differences were also found in collagen III and proteoglycans between regions of the flexor tendon subjected to either compressive or tensile load. After laceration and subsequent repair of the flexor tendon, a shift in collagen gene expression from type I to type III occurred. Proteoglycans were generally increased with the notable exception of decorin, a potential inhibitor of the profibrotic transforming growth factor-β1 which was markedly increased during the first two weeks after repair in tendon tissue but remained unaltered in the sheaths. Both vascular endothelial growth factor and basic fibroblast growth factor mRNA levels remained essentially unaltered, whereas insulin-like growth factor-1 increased later in the healing process, suggesting potential beneficial effects of exogenous addition, increasing tendon strength through stimulating tenocyte proliferation and collagen synthesis. Matrix metalloproteinase-13 mRNA levels increased and remained high in both tendon and sheath, whereas there was only a transient increase of matrix metalloproteinase-3 mRNA in tendon. We could also demonstrate a significant increase of the proportion of myofibroblasts, mast cells and neuropeptide containing nerve fibers in the healing tendon tissue, all components of the profibrotic myofibroblast-mast cell-neuropeptide pathway.Biomolecular aspects of flexor tendon healing
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Sanders, David W. "Biomechanical analysis of flexor tendon repairs." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0021/MQ42197.pdf.
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Edsfeldt, Sara. "Intrasynovial flexor tendon injuries and repair." Doctoral thesis, Uppsala universitet, Handkirurgi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-316559.
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Complications after surgical repair of intrasynovial flexor tendon injuries in the hand occur despite advanced suture techniques and structured postoperative rehabilitation regimens. Early controlled tendon mobilization prevents adhesion formations and improves tendon healing as well as digit range of motion. To allow early postoperative rehabilitation, the strength of the repair must withstand forces created during the rehabilitation maneuvers. Improvements in suture biomechanics have increased repair strength, but up to 18 percent of repaired tendons still rupture. The overarching aim of this thesis was to investigate how to best treat intrasynovial flexor tendon injuries with limited risk of repair rupture, decreased adhesion formations, and to estimate the effect of individual patient and injury characteristics on functional outcome. In two observational studies, we identified risk factors for rupture of repaired intrasynovial flexor digitorum profundus (FDP) tendons, and studied effects of these risk factors on the long-term outcome. Age was associated with increased risk of repair rupture and impaired digital mobility the first year after surgical repair. Concomitant flexor digitorum superficialis (FDS) transection was associated with increased risk of repair rupture without affecting digital mobility. Concomitant nerve transection lowered the rupture risk without affecting digital mobility. To better understand forces generated in the flexor tendons during rehabilitation maneuvers, we measured in vivo forces in the index finger FDP and FDS tendons during rehabilitation exercises. Highest forces were measured during isolated FDP and FDS flexion for the FDP and FDS respectively. For the FDS tendon, higher forces were observed with the wrist at 30° flexion compared to neutral position, and for the FDP tendon, forces were higher during active finger flexion compared to place and hold. PXL01 is a lactoferrin peptide with anti-adhesive effects previously demonstrated in animal studies and a clinical trial to improve digital mobility when administrated around repaired tendons. We studied the mechanism of action of its corresponding rabbit peptide, rabPXL01 in sodium hyaluronate (HA) in a rabbit model of flexor tendon transection and repair and used RT-qPCR to assess mRNA levels for different genes. Increased levels of PRG4 (encoding lubricin) were observed in rabPXL01 in HA treated tendons. The expression of Interleukin 1β, 6, and 8 was repressed in tendon sheaths. RabPXL01 in HA might stimulate the release of lubricin and diminish inflammation, which correspondingly reduces tendon-gliding resistance and adhesion formations during postoperative rehabilitation exercises. The results of this thesis suggest individually adapted treatment plans, depending on repair strength, patient and injury characteristics, as a possible way to improve outcome after flexor tendon repair.
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Meyyappan, Karumbu Nathan. "Failure prediction of wire bonds due to flexure." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1737.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Macpherson, Debbie Freda. "Characterization of the rfb region of Shigella flexneri /." Title page, abstract and contents only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phm172.pdf.
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Mavris, Maria. "Bacteriophage SfII mediated serotype conversion in Shigella flexneri /." Title page, abstract and contents only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phm4608.pdf.
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Haddad, David. "Lithospheric flexure and the evolution of Australian basins." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302396.
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Shilpiekandula, Vijay 1979. "Flexure-based nanopositioning systems : integrated design and control." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/57892.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 209-219).
This thesis deals with the design and control of flexure-based mechanisms for applications requiring multi-degree-of-freedom positioning and alignment. Example applications include positioning a probe or sample in atomic force microscopy, alignment of tool and sample in stamping processes, and fine-positioning of wafer steppers in semiconductor manufacturing. Such applications necessitate nanopositioning systems that satisfy critical functional requirements, such as load-capacity, bandwidth, resolution, and range. Therefore, a systematic approach for design and control is an important tool for research and development for flexure-based nanopositioning systems. In this thesis, a novel methodology is presented for generating flexure-based topologies that can meet performance requirements, such as those dictating structural strength or dynamical behavior. We present performance metrics that allow for the generation of topologies that are tuned for a desired level of structural strength or modal separation. The topology generation is aimed as a valuable addition to the design toolkit, facilitating novel designs that could not have been conceived otherwise. The parameters within any particular topology could be adjusted at a subsequent phase through a detailed shape and size optimization. The thesis also proposes a controller generation approach. Unlike existing controller parameterizations, a novel parameterization formulated in this thesis allows for directly tuning the sensitivity transfer function of the closed-loop system. Tuning sensitivity is critical in mitigating the effects of disturbances affecting the system, as well as those arising from cross-coupling and parasitic error motions. Further, an integrated methodology for design and control is presented. This methodology uses the design topology generation approach and controller generation approach proposed in the thesis. The key distinction of our design for control approach is that the design is iterated over topologies and not just parameters within a selected topology. A simple one-degree-of-freedom positioning system example is worked out to detail the steps of the proposed integrated design and control methodology. A novel design topology that is ideally suited for achieving a desired design and control performance is derived using this methodology. Finally, the hardware design and control of a novel flexure-based nanopositioner implementation for scanning probe microscopy are presented to illustrate the effectiveness of the approaches discussed in this thesis.
by Vijay Shilpiekandula.
Ph.D.
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Sarzynski, Melanie Diane. "Carbon foam characterization: sandwich flexure, tensile and shear response." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/55.
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The focus of this research is characterizing a new material system composed of carbon and graphite foams, which has potential in a wide variety of applications encompassing aerospace, military, offshore, power production and other commercial industries. The benefits of this new material include low cost, light weight, fire-resistance, good energy absorption, and thermal insulation or conduction as desired. The objective of this research is to explore the bulk material properties and failure modes of the carbon foam through experimental and computational analysis in order to provide a better understanding and assessment of the material for successful design in future applications. Experiments are conducted according to ASTM standards to determine the mechanical properties and failure modes of the carbon foam. Sandwich beams composed of open cell carbon foam cores and carbon-epoxy laminate face sheets are tested in the flexure condition using a four point setup. The primary failure mode is shear cracks developing in the carbon foam core at a critical axial strain value of 2,262 με. In addition to flexure, the carbon foam is loaded under tensile and shear loads to determine the respective material moduli. Computational analysis is undertaken to further investigate the carbon foam's failure modes and material characteristics in the sandwich beam configuration. Initial estimates are found using classical laminated plate theory and a linear finite element model. Poor results were obtained due to violation of assumptions used in both cases. Thus, an additional computational analysis incorporating three dimensional strain-displacement relationships into the finite element analysis is used. Also, a failure behavior pattern for the carbon foam core is included to simulate the unique failure progression of the carbon foam on a microstructure level. Results indicate that displacements, strains and stresses from the flexure experiments are closely predicted by this two parameter progressive damage model. The final computational model consisted of a bond line (interface) study to determine the source of the damage initiation, and it is concluded that damage initiates in the carbon foam, not at the bond line.
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Luck, Shelley Narelle. "The SRL pathogenicity island of Shigella flexneri 2a YSH6000." Monash University, Dept. of Microbiology, 2003. http://arrow.monash.edu.au/hdl/1959.1/9549.
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Reeves, Eric E. "Structural reliability of ultra-high performance concrete in flexure." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1177090784.
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Röhrich-Dönitz, Anelia Dorothea. "Regulation of type III secretion hierarchy in Shigella flexneri." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633196.
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Type III secretion systems (T3SS) are protein injection devices used by Gram-negative bacteria to manipulate eukaryotic cells. In Shigella, the T3SS is assembled when the environmental conditions are appropriate for invasion. However, secretion is only activated when physical contact of the injection needle with the host cell generates an activation signal. The signal is transmitted to the cytoplasm where it triggers secretion. First, translocators are secreted which form a pore in the host cell membrane. Second, effector proteins are translocated into the host cell. The activation process is controlled by conserved T3SS components: the needle tip proteins IpaD and IpaB, the needle itself and the intracellular gate-keeper protein MxiC. The major tip protein IpaD provides a scaffold for pore-forming translocators. In its absence no needle tip is formed, the T3SS secretes constitutively and is unable to sense host cell contact. Using random mutagenesis combined with a genetic screen we have mapped the region of IpaD required for activation signal generation/transmission and identified an additional intracellular role for IpaD in secretion control. Thus, IpaD has a dual role in secretion regulation. The gate-keeper protein MxiC is a cytoplasmic protein that plays a key role in mediating secretion hierarchy. In its absence, the secretion of translocator proteins is decreased and effector proteins are leaked. We have used site-directed mutagenesis, genetics and analysis of native protein complexes to further characterise its function. While MxiC seems to be a predominantly cytoplasmic and monomeric protein, we show that it acts in the same intracellular pathway as IpaD to control translocator secretion. We have identified the areas of MxiC required for activation signal reception, promoting translocator secretion, blocking premature effector secretion and for regulating its own secretion. We also provide evidence that a conformational change in MxiC might be involved in its function. Taken together, our work suggests how cytoplasmic mechanisms block premature secretion of translocators and effectors and in which steps secretion activation might occur.
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Eilers, Björn. "Neutrophil antimicrobial proteins enhance Shigella flexneri adhesion and invasion." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2009. http://dx.doi.org/10.18452/16023.
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Shigella flexneri verursacht im Verlauf der Infektion eine massive Enzündungsreaktion sowie Schädigung des humanen Darmepithels. Neutrophile sind die ersten Zellen des angeborenen Immunsystems, welche den Infektionsherd infiltrieren. Diese Zellen greifen Mikroorganismen mittels Phagozytose, Neutrophiler extrazellulärer Fallen (Neutrophil Extracellular Traps, NETs) oder Degranulierung an. In dieser Arbeit haben wir untersucht, wie die Degranulierung von Neutrophilen die Virulenz von Shigellen beeinflußt und konnten zeigen, dass die Exposition von Shigellen mit Proteinen aus den Granula von Neutrophilen die Invasion in Epithelzellen stark erhöht. Während dieser Exposition binden kationische Proteine der Granula an die Oberfläche von Shigella und bewirken eine verstärkte Adhesion, welche dann schließlich zu “Hyperinvasion” führt. Dieser Effekt wird durch Änderungen der Oberflächenladung bewirkt, da eine Lipopolysaccharid (LPS) Mutante mit negativer Oberflächenladung eine zusätzliche erhöhte Hyperinvasion im Vergleich zu Wildtyp Shigellen zeigt. Zusätzlich zur Hyperinvasion bewirkt die Infektion von Epithelzellen mit Shigellen, die mit Granula Proteinen in Kontakt gekommenen sind, eine Verminderung der IL-8 Sekretion. Dieses Zytokin bewirkt eine starke Rekrutierung von Neutrophilen. Daher stellen wir die Hypothese auf, dass Shigella in der Lage ist, antimikrobielle Proteine des Wirtes zur Erhöhung seiner Virulenz durch Hyperinvasion zu verwenden sowie eine weitere Rekrutierung von Neutrophilen durch Inhibition der IL-8 Sekretion zu verhindern. Somit unterwandert Shigella das angeborenen Immunsystem und nutzt dessen Angriff zu seinem Vorteil.Shigella flexneri is an enteric pathogen that causes massive inflammation and destruction of the human intestinal epithelium. Neutrophils are the first cells of the innate immune system recruited to the site of infection. These cells can attack microbes by phagocytosis, Neutrophil Extracellular Trap (NET) formation and degranulation. Here, we investigated how neutrophil degranulation affects virulence and show that exposure of Shigella to granular proteins enhances infection of epithelial cells. During this process, cationic granular proteins bind to the Shigella surface causing increased adhesion which ultimately leads to hyperinvasion. This effect is mediated by changes in the surface charge, since a lipopolysaccharide (LPS) mutant with a negative surface shows enhanced hyperinvasion compared to wild-type Shigella. In addition, infection with Shigella exposed to granular proteins leads to the inhibition of secretion of the neutrophil attracting cytokine IL-8. We propose that Shigella uses host defense molecules to enhance its virulence by increased infection of its host cells and reduced recruitment of neutrophils after hyperinvasion through inhibition of IL-8 secretion. With this Shigella subverts the innate immune system and uses its attack for its own benefit.
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Du, Erica (Erica C. ). "Gameblox Flexidor : adding flexibility to blocks based programming environments." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100343.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (page 75).
Gameblox is an online, graphical programming environment currently being developed by the MIT Scheller Teacher Education Program as a means of making game development more accessible to students with little to no programming background. Through direct manipulation, users can create complex games by simply dragging objects onto specified screens, and attaching blocks as executable instructions. Users can create, modify, and test their games, all in one environment. However, certain users, such as beginners or students, may find that a scoped editor with only a subset of Gameblox features would be easier to use and still fulfill their goals. This thesis outlines the design and implementation of a new tool within Gameblox called the Flexidor Builder, which will allow any user to selectively restrict the view of the full Gameblox editor to create custom Gameblox editors with only a subset of features. This restricted editor is called a flexidor.
by Erica Du.
M. Eng.
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Awtar, Shorya 1977. "Synthesis and analysis of parallel Kinematic XY flexure mechanisms." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17945.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2004.Includes bibliographical references (p. 193-198).
This thesis presents a family of XY flexure mechanisms with large ranges of motion, first-order decoupled degrees of freedom, and small parasitic error motions. Synthesis is based on an systematic and symmetric layout of constraints that are realized by means of common flexure building blocks. An analytical formulation incorporating geometric non-linearities is used in deriving the characteristics of these flexure building blocks. Of concern are issues related to qualification and quantification of undesirable motions, mobility, stiffness variation within the range of motion, determination of center of stiffness, and sensitivity to manufacturing and assembly tolerances. Based on the properties of the building blocks, the performances characteristics of the resulting XY flexure mechanisms are discussed and the influence of symmetry in reducing error motions is analytically illustrated. To verify the design theory, a 300mm x 300mm prototype stage was fabricated, assembled and tested at the National Institute of Standards and Technology (NIST). Measurements using laser interferometry, autocollimation and capacitance gauges indicate levels of performance much better than the capabilities of the current state of the art of precision flexure stages. The prototype flexure stage has a 5mm x 5mm range of motion, with cross-axis errors of the order of one part in one thousand, and motion stage yaw errors of the order of a few arc seconds.
by Shorya Awtar.
Sc.D.
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Duval, Jean-François S. M. Massachusetts Institute of Technology. "FlexSEA : flexible, scalable electronics architecture for wearable robotic applications." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98647.
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Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2015."June 2015." Cataloged from PDF version of thesis.
Includes bibliographical references (pages 135-136).
The work of this thesis aims to enable the fast prototyping of multi-axis wearable robotic systems by developing a new modular electronics system. The flexible, scalable electronics architecture (FlexSEA) developed for this thesis fills the void between embedded systems used in commercial devices and in research prototypes. This system provides the required hardware and software for precise motion control, data acquisition, and networking. Scalability is obtained through the use of fast industrial communication protocols between the modules, and the standardization of the peripheral interfaces. Hardware and software encapsulation is used to provide high-performance, real-time control of the actuators while keeping the high-level control development fast, safe and simple. The FlexSEA kits are composed of two custom circuit boards (advanced brushless motor driver and microcontroller board), one commercial embedded computer, a complete software stack and documentation. During its development it has been integrated into a powered prosthetic knee as well as an autonomous ankle exoskeleton. To assess the usability of the FlexSEA kit, a new user successfully used a kit to read sensors and control an output device in less than three hours. FlexSEA simplifies and accelerates wearable robotics prototyping.
by Jean-François Duval.
S.M.
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Lees, J. M. "Flexure of concrete beams pre-tensioned with aramid FRPs." Thesis, University of Cambridge, 1997. https://www.repository.cam.ac.uk/handle/1810/273030.
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BENJELLOUN, TOUIMI ZINEB. "Caracterisation de sepa, une protease secretee par shigella flexneri." Paris 7, 1997. http://www.theses.fr/1997PA077093.
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La shigellose est une maladie diarrheique strictement humaine due a l'invasion de l'epithelium intestinal par les bacteries du genre shigella. Cette maladie se caracterise par la destruction de l'epithelium colique due a une inflammation aigue au site d'infection. Les facteurs de virulence de shigella deja identifies sont codes par un plasmide de virulence et sont secretes ; il s'agit des proteines ipaa, b, c et d, requises pour l'entree dans les cellules, et de icsa, implique dans le mouvement intracellulaire de la bacterie. Notre etude a porte sur la caracterisation d'une autre proteine secretee, designee sepa. Le gene codant pour cette proteine a ete localise sur le plasmide de virulence, clone, sequence et inactive. L'attenuation de la destruction tissulaire et de l'inflammation provoquees par le mutant sepa dans le modele d'infection des anses ileales de lapin indique que sepa intervient dans l'expression du pouvoir pathogene de shigella et suggere que sepa puisse etre implique dans l'invasion tissulaire. L'invasion de l'epithelium intestinal par s. Flexneri etant favorisee par la reponse inflammatoire, notamment par le recrutement de polynucleaires neutrophiles au site d'entree, un role pro-inflammatoire de sepa pourrait permettre l'amplification du processus invasif. Sepa est synthetise sous la forme d'un precurseur de 146 kda dont l'extremite n-terminale est impliquee dans le passage de la membrane interne et l'extremite c-terminale dans celui de la membrane externe. La proteine secretee mature de 110 kda presente un motif caracteristique des proteases a serine et possede une activite proteolytique sur des peptides synthetiques. L'absence d'activite proteolytique sur differentes proteines - qui constituent une barriere contre l'invasion de l'epithelium intestinal par la bacterie, participent a la structure de la matrice extracellulaire et a son remodelage, ou prennent part a la reaction inflammatoire - indique que sepa est une protease avec une specificite de substrat tres restreinte. L'analyse structurale de sepa, par comparaison de sequence et proteolyse menagee, met en evidence quatre domaines au sein de la proteine mature et suggere que sepa puisse etre une toxine de type a-b dont le domaine catalytique serait transloque dans le cytoplasme de la cellule cible.
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Egile, Coumaran. "Bases moleculaires de la motilite intracellulaire de shigella flexneri." Paris 7, 1999. http://www.theses.fr/1999PA077081.
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Les bacteries du genre shigella sont les agents etiologiques de la dysenterie bacillaire, une pathologie affectant essentiellement les enfants dans les pays en voie de developpement. La virulence de shigella est due a sa capacite a envahir l'epithelium colique et a disseminer au sein de cet epithelium. La dissemination du pathogene est due a la formation d'une comete d'actine polaire. La proteine bacterienne icsa recrute des proteines cellulaires qui sont responsables de l'assemblage de filaments d'actine et de leur reorganisation en une comete polaire a la surface bacterienne. Nous avons combine des approches de genetique microbienne, de biologie cellulaire et de biochimie de l'actine afin d'identifier les differentes proprietes de la proteine icsa de shigella et la fonction des proteines cellulaires interagissant avec icsa. Nous avons identifie la protease sopa qui participe au mecanisme de distribution unipolaire de icsa. Nous avons analyse la fonction du domaine grr de icsa responsable de la polymerisation des filaments d'actine. La comparaison de l'ultrastructure des cometes de shigella et de listeria suggera un mecanisme de motilite commun aux deux bacteries. Afin d'identifier ce mecanisme, le role des proteines rho, de n-wasp, du complexe arp2/3, de vasp et de la profiline dans la motilite de shigella a ete analyse. Nous avons montre que les proteines rho et vasp ne sont pas requises pour la motilite de shigella. En revanche, n-wasp et arp2/3 sont indispensables. Icsa active n-wasp et expose les domaines amino- et carboxy-terminaux de n-wasp. Le domaine carboxyterminal permet le recrutement du complexe arp2/3 et la nucleation des filaments d'actine. Le domaine aminoterminal permet la fixation des filaments d'actine a la surface bacterienne. Ainsi, l'assemblage de la comete d'actine par shigella est medivee via l'activation de n-wasp par icsa. Ce mecanisme differe de celui mis en uvre par listeria qui necessite le recrutement de deux proteines cellulaires (arp2/3 et vasp).
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Zelenka, Marc H. "Prescription for a profession the educational philosophy of Abraham Flexner and cogency in medical education /." [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3238508.
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Thesis (Ph.D.)--Indiana University, School of Education, 2006."Title from dissertation home page (viewed July 12, 2007)." Source: Dissertation Abstracts International, Volume: 67-10, Section: A, page: 3705. Adviser: David J. Flinders.
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Dorosh, Mark Norman. "Damage growth in bending of composite beams." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28376.
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A study has been made of glass fibre reinforced plastic beams in three-point bending. In recent years, the importance of flexural loading in composites has manifested itself in the form of composite leaf springs, helicopter rotors, and other applications. This study is directed at the initiation, growth, characterization and measurement of damage in unidirectional and cross-ply composite beams.
Beams were tested in three-point static and cyclic bending. Following damage initiation, either by a machined notch or by repeated cycling, damage growth has been characterized by two damage parameters: a damage depth encompassing a number of broken fibres on the tensile surface at the central load point, and a damage length or delamination parallel to the beam longitudinal axis.
A model was developed to predict the compliance, or deflection under applied load, as a function of beam properties and damage dimensions. The model is able to predict the compliance of damaged beams with reasonable accuracy. From fracture mechanics concepts it is shown that the two damage dimensions, depth and length, are related. It is concluded that the increase in compliance, a result of the growing damage dimensions, is related to the growth of the damage depth; the damage length follows from the relation between damage parameters and the compliance follows from the compliance model.
The damage state can thus be determined by compliance measurements if the relevant material properties and loading conditions are known. However, in service, compliance measurements may not be practical. Therefore a section of this study is devoted to an alternative damage measurement technique, namely acoustic emission monitoring. Damage initiation, compliance, damage length and damage depth were measured with AE monitoring techniques.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Karjalainen, T. (Teemu). "Nitinol shape memory alloy in flexor tendon repair." Doctoral thesis, Oulun yliopisto, 2012. http://urn.fi/urn:isbn:9789514299803.
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Abstract Early motion is crucial for tendon healing and functional results after flexor tendon repair in the fingers. Motion, however, causes stress in the repair site, which can result in failure of the repair. A flexor tendon repair is made with fine calibre sutures, which sets exceptional requirements for the suture materials used in flexor tendon repair. Nitinol (nickel-titanium alloy) is a shape memory alloy, which can exist in two temperature-dependent forms, soft martensite and stiff austenite. It is possible to fabricate a nitinol wire that is soft and pliable, yet has high tensile strength. It also has excellent biocompatibility. Therefore, it is a potential candidate flexor tendon repair suture material. This study evaluates biomechanical aspects of martensite nitinol wire as a flexor tendon repair suture material. The study hypothesis was that nitinol wire improves the strength of the repairs compared with the repairs made with conventional suture materials. It was found that nitinol core repairs and circumferential repairs performed significantly better when compared with repairs made with commonly used braided polyester and polypropylene of equal calibre. To further optimise the performance of the nitinol wire in tendon surgery, two experimental models were developed to study the suture-tendon interface. The aim was to prevent pull-out of the suture loop so that surgeons could have full advantage of the tensile strength of the nitinol suture. First, it was tested whether it is possible to improve the suture’s ability to grip the tendon tissue by changing the suture type from monofilament to multifilament. Multifilament suture loops reached higher pull-out strength when compared with round monofilament loops when a locking loop was used. Subsequently, the grip of four different previously reported core repair loops was tested. Based on their failure mechanism, two novel loops were developed. The novel loops demonstrated superior ability to grip the tendon. The novel loops can be useful with high tensile strength suture materials and in repairs, which are prone to suture pull-outTiivistelmä Varhainen korjauksen jälkeinen aktiivinen kuntoutus on osoittautunut hyödylliseksi jänteen paranemiselle. Varhainen liike altistaa korjauksen kuormitukselle, joka voi johtaa korjauksen pettämiseen. Korjaukset tehdään ohuilla langoilla. Tämä asettaa erityisiä vaatimuksia jännekorjauksessa käytettävälle ommelainemateriaalille. Nikkeli-titaani (nitinoli) on nk. muistimetalli. Sillä on kaksi lämpötilariippuvaista muotoa: pehmeä martensiitti ja jäykkä austeniitti. Nitinolista voidaan valmistaa ohutta pehmeää ja taipuisaa lankaa, jonka vetolujuus on suuri. Nitinolin siedettävyys jännekudoksessa on todettu hyväksi, minkä vuoksi se on lupaava materiaali käytettäväksi jännekorjauksissa. Tässä tutkimuksessa kokeiltiin martensiittisen nitinolilangan käyttöä jänteen ydinompeleena ja pintaompeleena. Olettamuksena oli, että nitinolilangalla saadaan kestävämpiä korjauksia kuin nykyään käytössä olevilla langoilla. Tulosten mukaan nitinolilangalla tehdyt korjaukset olivat kestävämpiä, kun niitä verrattiin saman paksuiseen punottuun polyesteriin ja polypropyleeniin. Lisäksi kehitimme kaksi mallia, joiden tarkoituksena oli parantaa nitinolilankasilmukan pitoa jännekudoksesta. Tarkoituksena oli löytää keinoja, joilla langan otetta jännekudoksesta voidaan parantaa ja langan hyvät vetolujuusominaisuudet pääsevät oikeuksiinsa. Ensin muutimme langan muotoa perinteisestä yksisäikeisestä pyöreästä monisäikeiseen muotoon. Monisäikeisen langan läpileikkausvoima oli huomattavasti suurempi kuin yksisäikeisen pyöreän langan. Ero oli havaittavissa vain, kun käytettiin lukitsevaa silmukkaa. Tämän jälkeen testasimme neljän perinteisesti käytetyn korjaustekniikan silmukan pitokykyä ja tulosten perusteella kehitimme kaksi uutta silmukkaa. Työssä kehitetyt silmukat pitivät kiinni jänteestä huomattavasti paremmin kuin perinteiset silmukat. Työssä kehitetyillä silmukoilla voidaan optimoida vahvojen ommelainemateriaalien suorituskyky jännekirurgiassa
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Daniels, Craig. "Characterisation of proteins involved in Shigella flexneri O-antigen biosynthesis." Title page, abstract and contents only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phd186.pdf.
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Corrigenda pasted onto back end-papers. Bibliography: leaves 163-182. Analyses the proteins involved in Shigella flexneri O-antigen biosynthesis at the molecular level in order to gain a more concise understanding of the biosynthesis machinery and how it functions.
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Lee, Soo Young. "Dissecting Molecular Mechanisms of Shigella flexneri Cell-to-cell Spread." Thesis, Harvard University, 2014. http://nrs.harvard.edu/urn-3:HUL.InstRepos:13065011.
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Shigella is a causative agent of bacillary dysentery in humans. The ability of Shigella to disseminate in the intestinal epithelium is crucial for disease establishment. This process of cell-to-cell spread involves actin-based motility, which allows movement of Shigella through the cytoplasm, and the ability of Shigella to form filopodia-like membrane protrusions that are engulfed by adjacent cells.
Compared to the process of Shigella actin tail assembly, which requires recruitment and activation of host actin modulators such as N-WASP and Arp2/3, the mechanism of how Shigella moves from an infected cell into neighboring cells and what host factors are involved remain poorly characterized. In this dissertation, I investigate whether members of the Ena/VASP family, as key actin regulators, or Inverse-BAR (I-BAR) family proteins, as coordinators of membrane curvature and actin dynamics, are required in dissemination of S. flexneri in a cell monolayer.
Ena/VASP family proteins regulate cell migration, adhesion, shape, and cell-cell interaction. The members of the family include Vasodilator-Stimulated Phosphoprotein (VASP), Ena-VASP-like (Evl), and Mammalian enabled (Mena). We have previously shown that Mena, despite its localization to the actin tail, has no role in S. flexneri actin-based motility. Here, I investigate the role of Mena, Evl, and VASP in S. flexneri dissemination. I determine that the presence of VASP or Evl restricts cell-to-cell spread of S. flexneri. I further show evidence that the conserved EVH1 domain and phosphorylation of VASP regulate the ability of Shigella to spread.
I-BAR proteins, including IRSp53 and IRTKS, contain a conserved domain that directly binds to membrane lipids and induces convex membrane deformation. This unique property and the ability of these proteins to bind F-actin and actin modulators are necessary for the formation of actin pedestals by pathogenic E. coli and filopodia. Using cells with reduced levels of IRTKS or IRSp53, I examine the role of these proteins in cell-to-cell spread and show that neither IRTKS nor IRSp53 is required for S. flexneri spread.
Collectively, these results advance our understanding of host proteins that participate in S. flexneri dissemination.
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Razak, Hashim Abdul. "Time dependent effects in reinforced concrete sections subjected to flexure." Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/1003/.
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Bauwens, Ciara. "Shigella flexneri Lipopolysaccharide Modifications in the Presence of Bile Salts." Thesis, Boston College, 2019. http://hdl.handle.net/2345/bc-ir:108501.
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Thesis advisor: Christina FahertyShigella, a Gram-negative bacterial pathogen, induces inflammation and diarrhea by invading the colonic epithelium. Annually, millions of Shigella infections occur globally, mainly in malnourished children. Despite extensive research, no effective vaccine exists. This work explores the mechanisms of Shigella proliferation before colonic infection, where an adverse environment is encountered, including bile salts exposure. One means of bile salts evasion is possibly lipopolysaccharide (LPS) modification. LPS—O-antigen, the polysaccharide core, and the lipid A—is a crucial outer membrane component for virulence. Transposon mutant analysis suggested a role of LPS in bile salts resistance; thus, the goal of this study was to define Shigella LPS modifications following bile salts exposure. LPS mutants were investigated to distinguish crucial components of the LPS structure for bile salts resistance. Mutants were analyzed relative to wild type for growth in bile salts and biofilm formation. The LPS from all strains was purified and analyzed by polyacrylamide gel electrophoresis. Stained gels show modifications in the Oag, lipid A, and core components. Key bands were sent for mass spectrophotometry sequencing. Results indicate that the O-antigen regulates Shigella bile salts resistance, as the complete O-antigen deletion mutant and partial deletion mutants exhibited slow growth in bile salts and failed to form a biofilm in the presence of bile salts. This work highlights the importance of bile salts exposure for Shigella in future targeted antibodies against the pathogen
Thesis (BS) — Boston College, 2019
Submitted to: Boston College. College of Arts and Sciences
Discipline: Departmental Honors
Discipline: Biology
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RAMIREZ, JORGE DUENAS. "BLOCK-FLEXURE TOPPLING MECHANISM: CASE NW SLOPE TINTAYA´S MINE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2006. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9597@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Esta tese apresenta o fenômeno de ruptura por tombamento bloco-flexural, que acontece na zona NW da mina Tintaya. O objetivo do presente estudo é contribuir o conhecimento de este tipo de fenômeno de ruptura, quantificando as características do maciço rochoso com as técnicas da mecânica das rochas. O trabalho inicia-se por uma caracterização geral da zona de estudo, com especial relevo das propriedades geomecánicas das descontinuidades presentes, pelo que foram desenvolvidos mapeamentos das caras de bancada e a amostragem da rocha intacta, esta data permitiu estabelecer correlações dos parâmetros geomecânicos e fazer a análise cinemática da zona de estudo. Após de fazer a caracterização e avaliação das características das descontinuidades, foi definido o tombamento bloco-flexural, pelo jeito das descontinuidades presentes no maciço, já que este tipo de ruptura é mais complexo do que os outros tipos de tombamento, porque é uma combinação de tombamento e deslizamento dos blocos. Em vez da ruptura flexural de colunas contínuas, neste caso o tombamento é resultado de deslocamentos acumulados das juntas transversais. Com o objetivo de fazer uma análise numérica, obtou-se por um modelo contínuo- equivalente que inclui os efeitos de orientação e espaçamento das juntas é o modelo de plasticidade de Cosserat. O contínuo de Cosserat, conhecido também como contínuo micropolar acrescenta os graus de liberdade de rotação ao contínuo convencional. Pelo que foi analisado este tipo de ruptura através de uma modelagem computacional com um programa de elementos finitos feito na PUC-Rio, assim, tornar possível a modelagem computacional com a teoria do continuo de Cosserat.
This thesis presents the block - flexural toppling failure phenomenon, which happens at NW zone of the Tintaya´s mine. The objective of the present study is to contribute the knowledge of this type of phenomenon of failure, quantifying the characteristics of rock mass with the techniques of the rock mechanics. The work begins for a general characterization of the zone, with special relief of the geomechanical properties of the discontinuities, which were developed the window sampling (bench face mapping) and sampling of the intact rock, this information allowed to establish correlations of the geomechanical parameters and make feasible kinematics analysis from the zone of study. After doing the rock mass characterization and evaluation of the characteristics of the discontinuities, the block - flexural toppling failure was defined, on those long column rocks crossed by numerous huge subhorizontal joints. The block-flexural type failure is a complex phenomenon compared with other types of toppling failure, because it is a combination of pure toppling and sliding. With the intention of numerical analysis, I have been proposed analyzing this rupture for a continuum - equivalent model of Cosserat, that includes the orientation and the discontinuity´s spacing. This model is known also as continuum micropolar, which adds the degrees of freedom of rotation to a conventional continuum. It was analyzed this type of failure through a computational modeling with a program of finite elements made in the PUC-Rio, so, the computational modeling possible with the theory of continuum of Cosserat.
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Ljubicic, Dean M. "Design and analysis of a monolithic flexure atomic force microscope." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45201.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 175-178).
This thesis details the design, manufacture, and testing of a sub-nanometer accuracy atomic force microscope. It was made to be integrated into the Sub-Atomic Measuring Machine (SAMM) in collaboration with the University of North Carolina at Charlotte (UNCC). The microscope uses a tuning fork sensor to gauge its proximity to the sample surface. The sensor is fixed to a stage that is guided to move in one degree of freedom by a monolithic flexure. A piezoelectric actuator drives the moving stage while three capacitance sensors provide a non-contact direct measurement of the displacement. A decoupling flexure prohibits the error motions of the actuator from propagating into the moving stage. A digital control system uses closed loop control to regulate the vertical displacement of the stage. The positioning system demonstrated a 450 Hz -3db closed loop bandwidth and 0.249 RMS noise positioning. A new probe named after its inventor Dr. Terunobu Akiyama is implemented in a feedback control system that adjusts the displacement of the stage in order to maintain a constant gap between the probe and the sample. The system displayed an 8.3 nm RMS positioning noise when set to measure a stationary block of aluminum. The dynamics of the feedback control loop indicate that the system can operate at 27 Hz upon application of a proportional controller. Advanced methods to self excite the tuning fork sensor at resonance by use of a phase locked loop are explored. Follow-up work to integrate the atomic force microscope into the SAMM stage, diminish the electrical noise in the tuning fork, and to implement the phase locked loop circuit are suggested.
by Dean Marko Ljubicic.
S.M.
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Mertz, David Hunter. "Lift-off performance in flexure pivot pad and hybrid bearings." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3197.
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Thomaz, Felippe Calazans. "Eu, avatar: as flexões do ser a partir dos MMORPGs." Faculdade de Comunicação, 2014. http://repositorio.ufba.br/ri/handle/ri/24247.
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CNPQ
Examinamos, na presente dissertação, os processos de construção identitária e autoapresentação em ambientes simulados online de caráter lúdico. A partir do jogo World of Warcraft, são apresentados e discutidos certos elementos intervenientes no processo de assumir um avatar enquanto extensão de si, realizando atividades que, em sua maioria, reforçam as dinâmicas preestabelecidas do meio – MMORPG, ou RPG de participação online massiva. A escolha do objeto se vale pela posição privilegiada que o mesmo ocupa dentre os jogos da mesma categoria, o que nos permite apontar com maior propriedade que “as flexões do ser”, em função da incorporação de dispositivos digitais, refletem traços do “espírito do tempo” que presenciamos. A partir de uma postura interdisciplinar, o método adotado se aproxima da Filosofia – sobretudo da fenomenologia – e da Psicologia social, relacionando tais campos à Comunicação e aos Gamestudies. Deste modo, refletir sobre o que é compreendido enquanto “presença”, “experiência”, “percepção” e “imersão” nos permite perceber as camadas sociais inerentes à categoria de jogo em questão como peculiares formas de interação humana. A partir de um “mundo virtual”, examinamos o que constitui o corpo e o meio, propondo que ambos são construções visuais-funcionais, estreitamente ligados aos aspectos competitivos e estéticos do jogo. Assim, a discussão sustentada torna possível pensar as chamadas “flexões do ser” enquanto movimentos do jogador ao avatar e, noutra via e em certa medida, do avatar ao jogador.
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Freitas, Leonardo Luiz. "Inativação de Shigella flexneri pela associação de nisina e ultrassom." Universidade Federal de Viçosa, 2017. http://www.locus.ufv.br/handle/123456789/21428.
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Fundação de Amparo à Pesquisa do Estado de Minas Gerais
A bioconservação é uma das técnicas atuais utilizadas na conservação de alimentos, que se baseia na utilização de micro‐organismos e, ou de seus metabólitos, como por exemplo, bacteriocinas. Nisina é uma bacteriocina produzida por Lactococcus lactis subsp. lactis, usada na conservação de alimentos em mais de 50 países, incluindo o Brasil. Nisina é altamente ativa contra ampla gama de bactérias gram-positivas, mas bactérias gram-negativas, como Shigella, são naturalmente resistentes à sua ação. Esta resistência está relacionada à presença da membrana externa, que atua como barreira impedindo a difusão da bacteriocina até a membrana celular, seu local de ação. O uso de estratégias para desestabilizar a membrana externa, como o ultrassom (US), pode favorecer a ação da nisina contra bactérias gram-negativas. Este estudo teve como objetivo avaliar o efeito da nisina associada ao US contra Shigella flexneri 2a em caldo infusão de cérebro e coração (BHI). Foi utilizado o delineamento composto central rotacional (DCCR) e a metodologia de superfície de resposta (MSR) com três variáveis independentes: tempo de sonicação (X 1 : 5 a 20 min), pH (X 2 : 4,0 a 7,0) e concentração de nisina (X 3 : 29,1 μM a 291,1 μM). A diferença entre o logaritmo do número de células viáveis (log UFC/mL) no início e ao final de cada tratamento foi utilizada para construção do modelo preditivo. Análise de variância (ANOVA) e oito condições adicionais foram usadas para validação do modelo. Foi avaliado a sobrevivência de S. flexneri após a sonicação na presença de nisina e estocagem sob refrigeração (7 oC) por 120 h. Para isso, duas condições foram estabelecidas (10 min de US, pH 6,0 e 175 μM de nisina e 20 min de US, pH 4,5 e 175 μM de nisina). O extravasamento de ATP também foi avaliado nestas duas condições. Para comparações dos dados foi utilizado o teste Tukey para verificar a existência de diferenças entre o tratamento combinado (nisina + US) e os grupos controles. O nível de significância adotado foi de 5%. Os resultados indicaram que o US é uma estratégia eficaz para sensibilizar S. flexneri à ação da nisina. A combinação de nisina com US resultou em sinergismo na inativação deste patógeno, sendo que a maior inativação foi observada em baixos valores de pH, concentrações altas de nisina e maior tempo de sonicação, com redução máxima de, aproximadamente, 5 ciclos logarítmicos. O modelo preditivo da combinação (nisina + US) apresentou coeficiente de determinação (R 2 ) de 0,942 e ajustado de 0,916 e o modelo foi validado. A estocagem sob-refrigeração após a sonicação na presença de nisina resultou no declínio da população de S. flexneri ao final do tempo de armazenamento que reduziu de 5,42 para 1,64 ciclo logarítmico em pH 6,0 após tratamento por 10 min de sonicação e 5,69 para 0,80 ciclo logarítmico em pH 4,5 quando tratada por 20 min de sonicação. O tratamento de nisina com US provocou o maior extravasamento de ATP intracelular em ambas as condições testadas. Estes resultados demonstram o potencial uso da nisina combinada ao US como estratégia de sanitização e conservação de alimentos.
Bioconservation is one of the current techniques used in food preservation, which is based on the use of microorganisms and their metabolites such as bacteriocins. Nisin is a bacteriocin produced by Lactococcus lactis subsp. lactis, used as a food preservative in more than 50 countries, including Brazil. Nisin is highly active against a wide range of gram-positive bacteria, but gram-negative bacteria, such as Shigella, are naturally resistant to its action. This resistance is related to the presence of the outer membrane, that acts as barrier preventing the diffusion of the bacteriocin to its site of action. The use of strategies to destabilize the outer membrane, such as ultrasound (US), can favor the action of nisin against gram-negative bacteria. This study aimed to evaluate the effect of nisin associated with US against Shigella flexneri 2a in brain and heart infusion broth (BHI). A Central Composite Rotated Design (CCRD) and response surface methodology (RSM) was performed with three parameters: sonication time (X 1 : 5 to 20 min), pH (X 2 : 4.0 to 7.0) and nisin concentration (X 3 : 29.1 μM to 291.1 μM). The difference among the logarithm of the viable cell number (log CFU/mL) at the beginning of the experiment and at the end of each treatment was used for the construction of predictive model. Analysis of variance (ANOVA) and eight additional conditions were used for model validation. The behavior of S. flexneri after sonication in the presence of nisin and storage on refrigeration (7 oC) for 120 h was evaluated. For this, two conditions were established (10 min of US, pH 6.0 and 175 μM nisin and 20 min of US, pH 4.5 and 175 μM nisin). The leakage of ATP was also evaluated in these two conditions. For comparisons of the data, the teste Tukey was used to verify the existence of differences between the combined treatment (nisin + US) and the control groups. The level of significance was set at 5%. The results indicated that US is an efficient strategy for sensitize S. flexneri to the action of nisin. The combination of nisin with US resulted in synergism in the inactivation of this pathogen being that the higher inactivation observed was low pH, high nisin concentrations and longer sonication time, with a maximum reduction of approximately 5 logarithms cycles. The predictive model of the combination (nisin + US) showed coefficient of determination (R 2 ) of 0.942 and adjusted of 0.916, and the model was validated. Refrigerated storage after sonication in the presence of nisin resulted in the decline of the S. flexneri population at the end of storage time decreasing from 5.42 to 1.64 logarithm cycle at pH 6.0 treated with 10 min of sonication and 5.69 to 0.80 logarithm cycle at pH 4.5 when treated for 20 min sonication. The treatment of nisin with US caused the highest leakage of intracellular ATP, combined with US in both conditions tested. These results demonstrate the potential use of nisin combined to US as strategy for sanitation and food preservation.
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Penno, Christophe. "Contrôle de la virulence de Shigella flexneri par glissement transcriptionnel." Paris 6, 2007. http://www.theses.fr/2007PA066050.
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L’entrée des bactéries du genre Shigella dans les cellules épithéliales fait intervenir un appareil de sécrétion de type III spécifié par l’opéron mxi-spa comportant une vingtaine de gènes dont mxiE codant pour un activateur de transcription. Nous avons montré, dans l’opéron mxi-spa, la présence de 4 sites de glissement transcriptionnels sur lesquels l’ARN polymérase incorpore un nombre de nucléotides différant de celui spécifié par la matrice ADN. Le glissement sur deux de ces sites est requis pour la production de protéines fonctionnelles, MxiE et Spa13, et sur les deux autres sites conduit à la production de protéines tronquées, MxiA et Spa33. La présence de ces sites diminue la production de MxiE et Spa13 de 70%, de MxiA et Spa33 de 15% et de MxiD et Spa32 de 50%. La modulation de l’efficacité de glissement constituerait un moyen de contrôler l’expression des protéines du système de sécrétion de type IIIBacteria of Shigella species enter into epithelial cell using a type three secretion apparatus encoded by the mxi-spa operon containing about 20 genes, including the mxiE gene coding for a transcription activator. We showed, in the mxi-spa operon, the presence of 4 sites of transcriptional slippage on which the RNA polymerase incoporates a number of nucleotides that is different from that specified by the DNA template. Slippage on two of these sites is required for production of functional proteins, MxiE and Spa13, and on the two other sites leads to production of truncated proteins, MxiA and Spa33. The presence of these sites decreases production of MxiE and Spa13 by 70%, of MxiA and Spa33 by 15% and of MxiD and Spa32 by 50%. Modulation of the efficiency of transcriptional slippage might represent a means to control expression of components of the type III secretion system
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Flexeder, Andrea [Verfasser], Helmut [Akademischer Betreuer] Seidl, and Andy [Akademischer Betreuer] King. "Interprocedural Analysis of Low-Level Code / Andrea Flexeder. Gutachter: Helmut Seidl ; Andy King. Betreuer: Helmut Seidl." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/101343708X/34.
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