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Auto-inflammation de mélanges pauvres assistée par plasma / Plasma assisted auto-ignition of lean mixturesPrevost, Vivien 28 October 2013 (has links)
Le durcissement des normes d’émission, tout autant que l’impératif d’économie,poussent à étudier de nouveaux modes de combustion pour les moteurs. L’autoallumage decharges homogènes à basse température offre de bonnes perspectives quant au rejet de NOx,suies, et CO2. Cependant son control reste délicat, car il est extrêmement sensible à latempérature et la cinétique de l’hydrocarbure. L’assistance par plasma hors-équilibre pourraitfournir une solution. Les expériences sont menées dans une MCR avec des mélanges pauvresd’isooctane/air et un prototype d’allumeur Renault. La combustion obtenue identifiée commeSICI se déroule en deux phases: la propagation d’une flamme comprime les gaz restantjusqu’à leur autoallumage. Le réchauffement du système expérimental est intégré dans leprotocole d’exploitation, afin de quantifier l’effet SICI relativement à l’autoallumage pur.L’effet du plasma semble avant tout dépendre de l’énergie déposée, bien qu’il convergerapidement, quel que soit l’avance du déclenchement. Le comportement asymptotique à hauteénergie s’explique par la thermalisation des filaments, soulignée par comparaison avec l’effetSICI d’un arc classique. A l’inverse, le seuil minimal d’énergie nécessaire semble lié à lacapacité à générer un noyau de flamme viable, rapprochant le phénomène d’un problèmeclassique d’allumage en conditions difficiles. La propagation de la flamme détermine ledéclenchement de l’autoallumage selon une caractéristique linéaire particulièrementremarquable, car indépendante des conditions thermodynamiques du mélange. L’existenced’une flamme froide est mise en avant par des acquisitions de PLIF formaldéhyde. Lapréréaction semble accélérer la propagation du front de flamme. / Emission standards tightening as well as economical needs urge to study newcombustion modes for engines. Low-temperature homogeneous charge auto-ignition offersgood prospects for NOx, soot, and CO2 emissions. However, its control remains sharp for it isextremely influenced by temperature and fuel chemistry. Assisting non-equilibrium plasmascould provide a solution. Experiments are RCM managed with lean isooctane/air mixtures andprototype Renault ignition devise. Combustion occurs in a two steps mode known as SICI:flame propagation compresses the remaining gas to auto-ignition. The experimental settemperature rise is computed in order to measure the SICI effect compared to pure autoignition.The plasma seems to act mainly through the energy dropped, albeit its effect quicklyreaches a maximum, no matter how early it starts. This asymptomatic high energy behaviorrelies on the streamers overheating, as underlined by the look-like SICI effect from a regulararc discharge. On the contrary, minimal required energy appears to be linked to the capabilityof generating a sustainable flame kernel, making it closer to a standard ignition issue in roughconditions. Flame propagation sets auto-ignition start, according to an astonishingly linearcharacteristic not even influenced by charge’s thermodynamic conditions. Cool flame is putforward through formaldehyde PLIF imaging. Prereaction seems to enhance front propagationspeed.
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Analyses multivariées et multiblocs d'images hyperspectrales pour la prédiction de la corrosion sur le long terme : application à la corrosion atmosphérique d'alliages ferreux historiques / Multivariate and multibloc analysis of hyperspectral images in order to predict long term corrosion : application to atmospheric corrosion of historical iron alloysLe Penglau, Robin 12 December 2017 (has links)
Ce travail consiste en le développement d'une méthodologie pour comprendre les mécanismes de corrosion atmosphérique du fer sur le long terme à l'aide d'outils chimiométriques. Les données structurales et de composition élémentaire sont acquises par microspectrométrie Raman et Microscopie Electronique à Balayage couplée à la Spectroscopie en Dispersion d'Energie (MEB-EDS) sur deux échantillons provenant de barres de fer des cathédrales d'Amiens et de Metz. Ces deux jeux de données sont couplés puis étudiés selon différentes approches multiblocs. La première partie de ce projet étudie les données spectrales couplées pour préserver le maximum d'information des acquisitions et la deuxième étudie les mêmes données réduites en nombre de variables pour en simplifier l'étude. Ces deux approchent convergent vers une même conclusion : des éléments mineurs sont présents au sein de certaines phases cristallines de corrosion, notamment la ferrihydrite qui est associée au silicium, au phosphore et au potassium. Ceci peut à terme influencer les propriétés physicochimiques des phases présentes dans les couches de produits de corrosion et modifier les vitesses de corrosion. / This work aims to develop a methodology in order to understand atmospheric long term corrosion mechanism with chemometric tools on iron materials. Structural and elementary data are acquired with Raman microspectrometry and Scanning Electron Microscopy coupled to Energy Dispersive X-Ray spectroscopy (SEM-EDX) on two samples, one extracted from Amiens’ cathedral and one from Metz’s cathedral. These two datasets are coupled together then studied with several multibloc approaches. The first studies spectral data in order to avoid information loss and the second use the same reduced data in order to simplify the study. These two approaches give same results which leads to: minor elements are colocalized with some crystalline phases. For example, ferrihydrite is colocalized with minor elements (silicon, phosphorus and potassium). This can influence crystalline phase’s physicochimico reactivity properties in corrosion product layer and the corrosion rate.
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Výskyt rezistence ke kolistinu u izolátů klinicky významných enterobakterií / Colistin resistance in clinically important EnterobacteriaceaeSmělíková, Eva January 2020 (has links)
Colistin is a last-resort antibiotic used to treat serious infections caused by Enterobacteriaceae and other multidrug resistant gram-negative bacteria. Recently discovered plasmid-borne colistin resistance, mediated by the mcr genes, poses a serious risk to colistin therapy. The aim of this diploma thesis was to map the occurrence of Enterobacteriaceae carrying the mcr-1 to 8 genes in hospitalized patients, travellers, prospective colistin-resistant clinical isolates and in a retrospective collection of Enterobacteriaceae using a combination of selective cultivation and qPCR. Isolates with a detected mcr gene were characterized by Whole-Genome Sequencing. The localization of mcr genes was determined and other resistance genes and plasmids were identified. Furthermore, the physiological profile of selected colistin- resistant Escherichia coli isolates was characterized. In the presence of a subinhibitory amount of colistin, a strain carrying the mcr-1 gene may be favored. Later, the mcr-9 gene was described and its occurence was subsequently tested retrospectively. Enterobacter spp. isolates carrying the mcr-9 gene were mostly colistin-sensitive but, in some cases, resistance was induced after exposure to sublethal doses of colistin. The results of the study show that the incidence of plasmid-mediated...
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Complement-Related Regulates Autophagy in Neighboring CellsLin, Lin 13 June 2017 (has links)
Autophagy is a conserved process that cells use to degrade their own cytoplasmic components by delivery to lysosomes. Autophagy ensures intracellular quality control and is associated with diseases such as cancer and immune disorders. The process of autophagy is controlled by core autophagy (Atg) genes that are conserved from yeast to mammal. Most Atg proteins and their regulators were identified through pioneering studies of the single cell yeast Saccharomyces cerevisiae, and little is known about factors that systematically coordinate autophagy within the tissues of multicellular animals. The goal of this thesis is to identify new autophagy regulators and provide a better understanding of the regulatory mechanisms within multicellular animals. My research determined Macroglobulin complement-related (Mcr), a Drosophila complement orthologue, can activate autophagy during developmental cell death. Unlike most known autophagy regulators, Mcr functions in a cell non-autonomous manner to trigger autophagy in neighboring cells. To my knowledge, this is the first identified autophagy factor that cell non-autonomously activates autophagy. Additionally, I found that Mcr, a secreted protein, instructs the autophagy machinery through the immune receptor Draper, suggesting a relationship between autophagy and the control of inflammation. Lastly, Mcr is dispensable for both nutrient deprivation-induced autophagy in the fat body and developmentally programmed autophagy in the dying midgut of Drosophila. Therefore, this study unveils a mechanism in a multicellular organism by which autophagy is systematically controlled in distinct cell contexts.
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Continuous multi-step synthesis by extrusion - telescoping solvent-free reactions for greater efficiencyCrawford, Deborah E., Miskimmin, C.K., Cahir, J., James, S.L. 13 February 2020 (has links)
Yes / Chemical manufacturing typically requires more than one step,
involving multiple batch processes, which makes synthesis at scale
laborious and wasteful. Herein, we demonstrate that several reactions can be telescoped into a single continuous process and/or be
carried out as a continuous multi-component reaction (MCR), by
twin screw extrusion (TSE), in the complete absence of solvent. / EPSRC (EP/L019655/1).
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The development and implementation of software for palaeoenvironmental and palaeoclimatological research : the Bugs Coleopteran Ecology Package (BugsCEP)Buckland, Philip January 2007 (has links)
<p>This thesis documents the development and application of a unique database orientated software package, BugsCEP, for environmental and climatic reconstruction from fossil beetle (Coleoptera) assemblages. The software tools are described, and the incorporated statistical methods discussed and evaluated with respect to both published modern and fossil data, as well as the author’s own investigations.</p><p>BugsCEP consists of a reference database of ecology and distribution data for over 5 800 taxa, and includes temperature tolerance data for 436 species. It also contains abundance and summary data for almost 700 sites - the majority of the known Quaternary fossil coleopteran record of Europe. Sample based dating evidence is stored for a large number of these sites, and the data are supported by a bibliography of over 3 300 sources. Through the use of built in statistical methods, employing a specially developed habitat classification system (Bugs EcoCodes), semi-quantitative environmental reconstructions can be undertaken, and output graphically, to aid in the interpretation of sites. A number of built in searching and reporting functions also increase the efficiency with which analyses can be undertaken, including the facility to list the fossil record of species found by searching the ecology and distribution data. The existing Mutual Climatic Range (MCR) climate reconstruction method is implemented and improved upon in BugsCEP, as BugsMCR, which includes predictive modelling and the output of graphs and climate space maps.</p><p>The evaluation of the software demonstrates good performance when compared to existing interpretations. The standardization method employed in habitat reconstructions, designed to enable the inter-comparison of samples and sites without the interference of differing numbers of species and individuals, also appears to be robust and effective. Quantitative climate reconstructions can be easily undertaken from within the software, as well as an amount of predictive modelling. The use of jackknifing variants as an aid to the interpretation of climate reconstructions is discussed, and suggested as a potential indicator of reliability. The combination of the BugStats statistical system with an enhanced MCR facility could be extremely useful in increasing our understanding of not only past environmental and climate change, but also the biogeography and ecology of insect populations in general.</p><p>BugsCEP is the only available software package integrating modern and fossil coleopteran data, and the included reconstruction and analysis tools provide a powerful resource for research and teaching in palaeo-environmental science. The use of modern reference data also makes the package potentially useful in the study of present day insect faunas, and the effects of climate and environmental change on their distributions. The reconstruction methods could thus be inverted, and used as predictive tools in the study of biodiversity and the implications of sustainable development policies on present day habitats.</p><p>BugsCEP can be downloaded from http://www.bugscep.com</p>
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Information practices in midwifery: a case study of an antenatal and intrapartum care environment in the Western Cape, South AfricaMustafa, Alrasheed January 2015 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology in Information Technology in the Faculty of Informatics & Design at the Cape Peninsula University of Technology / Research on health informatics has seen a steady increase during this decade as the role of information technology in the health sector becomes pertinent. Findings of previous research in this domain have uncovered vast information needs of health workers, particularly in developing countries. However, there is a need to continue with multidisciplinary research in priority areas such as midwifery practice and in the environment of marginalised settings. This study explores the significance of the information needs and information-seeking behaviour or practice of midwives during the antenatal and intrapartum care within the environment of a midwifery unit. Additionally, the researcher obtained permission from Faculty of Informatics and Design – CPUT and Health department authority – Western Cape Government in South Africa, to conduct research in the Elsies River Midwifery Obstetric Unit (ERMOU). The research was carried out as case study in a Midwifery Obstetric Unit in the Western Cape, South Africa. The investigator conducted semi-structured interviews and observations to collect qualitative data of the antenatal and intrapartum care environment. The data was transcribed and analysed using thematic analysis and essomenic modelling.
The findings comprehensively point to the importance of this research context. The study found that midwives acquired patients’ information from a handwritten Maternity Case Record (MCR) book and midwives’ colleagues, and often during handovers. In addition, midwives also communicate with each other during care activities in the ERMOU. It was apparent that the use of such communication practices is inadequate, and midwives did not always have sufficient information to make appropriate decisions in the ERMOU. All patient information, referral notes, and reporting is paper-based.
In addition, essomenic models were used to depict the midwives’ work activities in the antenatal and intrapartum care environment in the Unit. Furthermore, essomenic models defined all the systematic processes that occur in the ERMOU which is described by midwives’ activities and work environment. To improve communication, future research is recommended to consider the importance of the continuity of the education of midwives. Further research will be on the implementation of nursing informatics and the electronic health record system in the Elsies River Midwifery Obstetric Unit.
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Espectroscopia e cromatografia l?quida com espectrometria de massa associadas ? quimiometria na classifica??o e avalia??o de perfil lipid?mico de classes bacterianas / Spectroscopy and liquid chromatography with spectrometry of mass associated to chemometry in the classification and evaluation of lipidomic of bacterial classesMarques, Aline de Sousa 18 August 2017 (has links)
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Previous issue date: 2017-08-18 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Esta tese de doutorado ? um aporte te?rico-pr?tica para o desenvolvimento de estudos que utilizem a bioanal?tica, particulamente materiais biol?gicos provenientes de bact?rias, podendo estes ser isolados, DNA, entre outros, em conjunto com ferramentas quimiom?ticas de an?lise. Para isso, buscou-se identificar diferen?as bacterianas quando submetidas a uma fonte de estresse a partir de diferentes t?cnicas anal?ticas. A primeira abordagem foi realizada partindo da bioespectroscopia, utilizando-se de dados espectrosc?picos obtidos na regi?o do infravermelho. A bioespectroscopia na regi?o do infravermelho ? descrita como uma t?cnica n?o invasiva, de alto rendimento, baixo custo (quando comparado com t?cnica padr?es de an?lise) e objetivas, e que possui um enorme potencial na an?lise de bact?rias, complementando ou mesmo substituindo m?todos de diagn?stico de doen?as convencionalmente conduzidos por especialistas atrav?s de m?todos padr?es de an?lises de alto custo e que necessitam de reagentes espec?ficos. Os dados obtidos a partir da bioespectroscopia em amostras bacterianas s?o complexos e apresentam muitas bandas de sobreposi??o sendo necess?ria a aplica??o de ferramentas matem?ticas para superar estas dificuldades. Para isso, algumas ferramentas matem?ticas, como os m?todos de sele??o de vari?veis, que utilizam a an?lise discriminante linear com Algoritmo de Proje??o Sucessiva (SPA-LDA) e Algoritmo Gen?tico (GA-LDA), geralmente s?o utilizadas com a finalidade de facilitando a extra??o de informa??es relevantes. A espectroscopia na regi?o do infravermelho, em espec?fico infravermelho pr?ximo (NIR) e infravermelho com trasformata de Fourier e reflect?ncia total atenuada (ATR-FTIR), em conjunto com m?todos de sele??o de vari?veis (SPA-LDA e GA-LDA) foram utilizadas na discrimina??o de amostras de bact?rias (Sthaphylococcus aureus, Klebsiella pneumoneae e Pseudomonas aeruginosa). Foram identificados prov?veis biomarcadores como lip?deos e prote?nas em ~1550 cm-1 e 1400 cm-1 e vibra??es de DNA em ~1080 cm-1. Valores de sensibilidade de 75% e 95% para modelos de SPA-LDA e 100% e 93% para modelos GA-LDA foram encontrados. Com base nesses resultados, pode-se concluir que o SPA-LDA e GA-LDA em conjunto com a espectroscopia na regi?o do infravermelho mostraram-se ferramentas eficientes melhorando o tempo e custo de diagn?stico possibilitando o tratamento mais r?pido em rela??o aos m?todos padr?es de diagn?stico e, consequentemente, sendo poss?vel evitar a evolu??o de uma poss?vel infec??o. A segunda abordagem foi avaliar poss?veis mudan?as no perfil lipid?mico de bact?rias resultante de sua exposi??o a uma fonte de estresse externa (Ars?nio (III)), utilizando as cianobact?rias Anabaena sp. e Planktothrix agardhii. Os dados foram obtidos a partir a Cromatografia L?quida- Espectrometria de Massas (LC-MS) que por gerar uma matriz de dados muito extensa foi necess?ria a utiliza??o de uma estrat?gia de sele??o proposta recentemente, definida como ROI (do ingl?s regions of interests) que diminui significativamente o tamanho da matriz de dados obtidas por LC-MS. Resolu??o Multivariada de Curvas com M?nimos Quadrados Alternantes (MCR-ALS) foi utilizado como m?todo de resolu??o das fontes de varia??o, recuperando as informa??es de seus componentes puros que se encontravam misturadas. As massas majorit?rias encontradas, sendo algumas delas 766.54, 565.40 e 871.56 (m/z), determinam que as cianobact?rias estudadas, ao serem submetidas a As(III), sofrem mudan?as relacionadas a estruturas que comp?em os processos fotossint?ticos das mesmas. / This doctoral thesis is a theoretical-practical contribution for the development of studies that use bioanalytical, particularly biological materials from bacteria, which can be isolated, DNA, among others, in conjunction with chemistry analysis tools. For this, it was sought to identify bacterial differences when submitted to a source of stress from different analytical techniques. The first approach was based on biospectroscopy, using spectroscopic data obtained in the infrared region. Biospectroscopy in the infrared region is described as a non-invasive, high-throughput, low-cost (when compared with standard analytical techniques) and objective techniques, and has a huge potential in the analysis of bacteria, complementing or even replacing diagnostic methods of diseases conventionally conducted by skilled persons by standard methods of expensive analyzes and requiring specific reagents. The data obtained from biospectroscopy in bacterial samples are complex and have many overlapping bands and it is necessary to apply mathematical tools to overcome these difficulties. For this, some mathematical tools, such as variable selection methods, using Linear Discriminant Analysis with Successive Projection Algorithm (SPA-LDA) and Genetic Algorithm (GA-LDA), are generally used for the purpose of solving these data, facilitating the extraction of information. Infrared spectroscopy, in specific Near Infrared (NIR) and infrared spectroscopy with Fourier transform and Attenuated Total Reflectance (ATR- FTIR), in conjunction with variable selection methods (SPA-LDA and GA-LDA) was used in the discrimination of bacterial samples (Sthaphylococcus aureus, Klebsiella pneumoneae and Pseudomonas aeruginosa). Possible biomarkers such as lipids and proteins were identified at ~ 1550 cm -1 and 1400 cm -1 and DNA vibrations at ~ 1080 cm -1. Sensitivity values of 75% and 95% for SPA-LDA models and 100% and 93% for GA-LDA models were found. Based on these results, it can be concluded that the SPA-LDA and GA- LDA in conjunction with the infrared spectroscopy showed efficient tools improving the time and cost of diagnosis allowing the treatment faster than the standard methods of diagnosis, and consequently, it is possible to avoid the evolution of a possible infection. The second approach was to evaluate possible changes in the lipid profile of bacteria resulting from its exposure to an external stress source (Arsenic (III)), using the cyanobacteria Anabaena sp. and Planktothrix agardhii. The data were obtained from Liquid Chromatography-Mass Spectrometry (LC-MS), which, in order to generate a very extensive data matrix, required the use of a recent selection strategy, defined as ROI (regions of interest), which significantly decreased the Size of the data matrix obtained by LC-MS. Multivariate Curve Resolution - Alternating Least Squares (MCR-ALS) was used as a method to solve variation sources, retrieving the information of its pure components that were mixed. The majority masses found, such as 766.54, 565.40 and 871.56 (m/z), determine that the studied cyanobacteria, when subjected to As (III), undergo changes related to structures that make up the photosynthetic processes of the same.
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Challenges working from home and its impact on Code reviews - Multiple Case StudyTallari, Rohith Girikshith, Kataray, Ravi Theja January 2022 (has links)
Background: COVID-19 is a dangerous contagious infection which was declared as a global pandemic by World Health Organisation (WHO) in March 2020. It was rapidly spreading worldwide, forcing the world to move into isolation and the software developing companies to change their work settings into remote working. Quality of the software is a significant attribute that determines the success of a project. Code reviews are an essential software development practice and are the first step towards improving the quality of the software. Objectives: The main objective of this research study is to list the challenges that the developers are facing while working from home and investigate the impact of challenges on code review practices. Methods: A multiple case study has been conducted in 5 organizations to understand and analyze the effect of transition on the code review process. We achieved this by conducting semi-structured interviews and participant observation with developers involved in code review practices of each organization considered for the study and qualitatively analyzed the gathered data using thematic analysis. Results: The results indicated challenges concerning team collaboration, infrastructure, productivity and burnout in the early stages of the pandemic. However, later, organizations’ mitigating strategies have helped them cope with the situation, and no significant impact due to working from home were observed on the code review process. Conclusions: Our findings highlight that there is no considerable impact of the challenges factored in due to working from home on the code review process. The major reasons behind that was the modernization of the tools used for code reviews and timely implementation of mitigation strategies by organizations. Based on the mitigation strategies taken by the organisations we formulated guidelines, which can be taken into consideration by the organisations still suffering with the transition to work from home.
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Synthèse de structures macromoléculaires aromatiques et hétérocycliques originales par voies non conventionnelles / Synthesis of original aromatic and heterocyclic macromolecular structures by unconventional pathwaysSaxer, Samantha 03 May 2018 (has links)
Le travail réalisé dans cette thèse concerne la synthèse de nouvelles structures macromoléculaires aromatiques et hétérocycliques. La synthèse de ces polymères a été envisagée par des procédés de polycondensation non conventionnels. A la différence des réactions classiques utilisées en polycondensation, des réactions de condensation « multi-composants » faisant intervenir trois ou quatre fonctions réactives ont été considérées. Les réactions de Debus-Radziszewski, Hantzsch, et Chichibabin, permettant la formation directe de structures aromatiques et ou hétérocycliques ont été plus particulièrement choisies. Ces polymérisations ont été réalisées à la fois par voie thermique classique et sous irradiation micro-ondes. Trois types de familles de polymères ont été synthétisés avec succès (PIM/PTAI, PPP, P-CNTP). Les résultats obtenus montrent que l’irradiation micro-ondes est bénéfique pour la synthèse de certaines structures, mais cet effet n’est pas systématique. En revanche, la technique d’irradiation sous micro-ondes s’impose comme outil très performant pour le développement de nouvelles structures macromoléculaires de par la réduction significative des temps de polymérisation. L’ensemble de ce travail souligne l’intérêt de la polycondensation par réaction multi-composant et ouvre de nouvelles perspectives pour le développement de nouveaux matériaux polymères aromatiques / hétérocycliques. / In this thesis, the synthesis of new aromatic and heterocyclic macromolecular structures is reported. These polymers have been synthetized by unconventional polycondensation processes. Unlike classic reactions used in polycondensation, "multicomponent" condensation involving three or four reactive functions were here described. More particularly, the reactions of Debus-Radziszewski, Hantzsch, and Chichibabin, allowing the direct formation of aromatic and heterocyclic structures have been chosen. These polymerizations were carried out both by conventional thermal method and under microwave irradiation. Three types of polymer families have been synthesized successfully (PIM / PTAI, PPP, P-CNTP). The results show that microwave irradiation is beneficial for the synthesis of some structures, but this effect is not systematic. On the other hand, microwave irradiation is a powerful tool to develop new macromolecular structures by significantly reducing the time of polymerization. This work underlines the interest of polycondensation by multicomponent reaction and opens perspectives for the development of new aromatic / heterocyclic polymeric materials.
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