Dissertations / Theses on the topic 'Persistent cycle'

Identifying business cycle stylised facts is essential as these often form the basis for the construction and validation of theoretical business cycle models. Furthermore, understanding the cyclical patterns in economic activity, and their causes, is important to the decisions of both policymakers and market participants. This is of particular concern in developing countries where, in the absence of full risk sharing mechanisms, the economic and social costs of swings in the business cycle are very high. Previous analyses of developing country stylised facts have tended to feature only small samples, for example the seminal paper by Agénor et al. (2000) considers just twelve middle-income economies. Consequently, the results are subjective and dependent on the chosen countries. Motivated by the importance of these business cycle statistics and the lack of consistency amongst existing research, this thesis makes an important contribution to the literature by extending and generalising the developing country stylised facts; examining both classical and growth cycles for a sample of thirty-two developing countries. One significant finding that emerges is the persistence of output fluctuations in developing countries and the strong positive relationship between the magnitude of this persistence and the level of economic development. The observation of procyclical real wages and significant price persistence indicates the suitability of a New Keynesian dynamic general equilibrium model with sticky prices, to explore this relationship; thus, the vertical production chain model of Huang and Liu (2001) was implemented. This model lends itself to such an analysis, as by altering the number of production stages (N) it is possible to represent economies at different levels of development. There was found to be a strong significant positive relationship between the magnitude of output persistence generated by the model and economic development. However, a very significant finding of this analysis is that the model overestimates output persistence in high inflation countries and underestimates output persistence in low inflation countries. This has important implications not only for this model, but also for any economist attempting to construct a business cycle model capable of replicating the observed patterns of output persistence.

Les méthodes de calcul en fatigue à grande durée de vie sont en cours de développement depuis des décennies et sont utilisées par les ingénieurs pour dimensionner les structures. Généralement, ces méthodes se basent sur la mise en équations de quantités mécaniques calculées à l'échelle macroscopique ou mésoscopique. Les critères de fatigue multiaxiale reposent généralement sur des hypothèses de changement d'échelle dont l'objectif est d'accéder à l'état de contraintes ou de déformations à l'échelle du grain. Dans les approches de type plan critique (Dang Van, Papadopoulos, Morel), l'amorçage d'une fissure de fatigue est considéré comme piloté par une quantité mécanique liée à une orientation matérielle particulière (plan critique). Si ces phénomènes sont bien établis dans le cas des chargements uniaxiaux, la nature des mécanismes liés à l'activation des systèmes de glissement, à la multiplicité du glissement et aux différents sites préférentiels d'amorçage de fissures sous chargements complexes reste peu connue.Afin de mieux comprendre les mécanismes d'endommagement en fatigue multiaxiale, les techniques d'analyse et de caractérisation de l'activité plastique (activation des systèmes de glissements, bandes de glissement persistantes) et d'observation de l'endommagement par fatigue ont été mises en place en se basant principalement sur des observations MEB et analyses EBSD. Ces investigations ont permis de mettre en lumière les effets des chargements non proportionnels sur la multiplicité du glissement sur du cuivre pur OFHC. L'étude statistique des sites préférentiels d'amorçage de fissures montre que les grains à glissement multiple présentent une forte probabilité d'amorçage de fissures, surtout sous les chargements non proportionnels. Nous avons également mis en évidence le rôle des joints de grains et des joints de macle sur le développement de la plasticité à l'échelle de la microstructure. Les résultats expérimentaux sont confrontés à ceux du calcul éléments finis (EF) en plasticité polycristalline sur des microstructures synthétiques 3D semi-périodiques. L'application du critère de Dang Van à l'échelle mésoscopique (le grain) montre une forte variabilité de la contrainte hydrostatique et du cisaillement. Cette variabilité est plus importante pour un modèle de comportement cristallin élastique anisotrope. Le rôle de la plasticité cristalline se révèle secondaire. Ces analyses permettent de remettre en perspective les hypothèses usuelles de changement d'échelle utilisées en fatigue multiaxiale. Enfin, une méthode basée sur la statistique des valeurs extrêmes est proposée pour le dépouillement des calculs EF sur agrégats. Cette analyse a été appliquée sur la contrainte équivalente associée au critère de fatigue de Dang Van pour les calculs d'agrégats polycristallins avec différentes morphologies et orientations des grains. Les effets de la surface libre, du type de chargement et du modèle de comportement mécanique des grains ont été analysés. Les résultats offrent des perspectives intéressantes sur la modélisation de l'amorçage des fissures en fatigue multiaxiale des matériaux et des structures avec une prise en compte de la microstructure.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.
Includes bibliographical references (p. 197-202).
by Robert Xavier Black.
Ph.D.

Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xi, 126 p.; also includes graphics. Includes bibliographical references (p. 121-126). Available online via OhioLINK's ETD Center

Multiple step tests under cyclic strain control have been performed using cylindrical specimens of cast polycrystalline Inconel 738LC superalloy at 23, 700, 500, 800 and 900 °C in laboratory atmosphere to obtain cyclic stress-strain curves. During cyclic straining of specimen were obtained cyclic hardening-softening curves. Their progress changed with temperature and strain amplitude. Evaluated cyclic stress-strain curves are shifted to lower stresses with increasing temperature. Surface relief was observed in fatigued specimens under SEM and metalography under optic microscopy. Slip markings were studied on specimen surface fatigued at 700 °C .Stress-strain response is compared and discussed in relation to the surface observations - persistent slip markings.

The role of Chlamydia trachomatis HtrA (CtHtrA) for the growth and pathogenesis of this organism is presented. Inhibition of CtHtrA led to loss of infectious progeny in Chlamydia, particularly during heat stress or recovery from penicillin persistence. Isolation of CtHtrA inhibitor resistant mutants identified positive selection for mutants in fatty acid related pathways. Importantly, HtrA inhibition was effective against clinical isolates of C. trachomatis. Thus the findings combined indicate that CtHtrA is an important chlamydial growth factor that has the potential to be targeted for the development of anti-chlamydial drugs in the future.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.
Includes bibliographical references (p. 259-267).
by Peter Paul Neilley.
Ph.D.

La tesis consta de dos partes. En la primera parte se analiza la relación entre las fricciones en los flujos de información que llegan a la empresa y la persistencia del patrón de la inflación. En particular, se presenta un nuevo estimador por el modelo de Makiw y Reis (2002) "Sticky Information Phillips Curve", y se aplica usando datos trimestrales de EE.UU. El resultado principal es que el modelo tan solo puede explicar la persistencia de la inflación asumiendo que la variancia de la inflación sea mucho mas grande de la que observamos o, equivalentemente, que el modelo no puede explicar conjuntamente la variancia y la persistencia de la inflación.

En la segunda parte se presentan nuevas evidencias sobre la publicidad agregada en EE.UU. y se estudian los efectos de la publicidad en la economía usando un modelo dinámico estocástico de equilibrio general. En particular, el capitulo 2 se enfoca en las relaciones de corto plazo entre las mas comunes variables macroeconómicas - consumo agregado, producto interno bruto, totalidad de horas trabajadas en la economía - y la publicidad agregada, con particular atención a la relación de causalidad entre publicidad y consumo. En cambio, el capitulo 3 se enfoca sobre las relaciones de largo plazo, enseñando como la publicidad agregada afecte el nivel de trabajo de la economía. A través del modelo presentado en el capitulo 2, se demuestra que un mayor nivel de publicidad implica un mayor números de oras trabajadas asociadas con un menor nivel de bienestar por los consumidores.
This thesis is organized in two parts. In the first one, I seek to understand the relationship between frictions in information flows among firms and inflation persistence. To this end, I present a novel estimator for the Sticky Information Phillips Curve (Mankiw and Reis, 2002), and I use it to estimate this model with U.S. postwar data. The main result is that the Sticky Information Phillips Curve can match inflation persistence only at the cost of mispredicting inflation variance. I conclude that the Sticky Information Phillips Curve is a valid model to explain inflation persistence but not an overall valid theory of inflation.

The second part presents new evidence about aggregate advertising expenditures in U.S., and analyzes the effect of advertising in the aggregate economy by the mean of a dynamic stochastic general equilibrium model. Chapter 2 focuses on the short run impact of advertising on the aggregate dynamics, and shows that an increase in aggregate advertising significantly increases the aggregate consumption. Chapter 3 focuses on the long run effects of advertising on the labor supply, showing that in economies where aggregate advertising is higher, agents supply more hours of works and are generally worse off in terms of welfare.

Members of the important disease causing bacterial generas, Chlamydia and Chlamydophila, are characterised by a complex developmental cycle which is comprehensively described by microscopy. The inability to use standard genetic techniques for this obligate intracellular bacterium, however, means that significant gaps in our understanding of the molecular mechanisms used to control growth and development of Chlamydia still exist. The current study investigated the function of bacterial guanosine triphosphatases (GTPases), components of the organism's limited signal transduction arsenal, in regulatory control of the chlamydial development cycle. Initial analysis of the gene transcription of chlamydial GTPases and other predicted signal transduction genes using real time RT-PCR, in a Chlamydophila pneumoniae A-03 tryptophan depletion model of persistence, revealed significant differential expression of genes in response to the addition of interferon gamma (IFN-γ). Predicted chlamydial GTPase encoding genes, ychF, yhbZ and yphC, associated with ribosome function amongst other processes were strongly up-regulated, while hflX was down-regulated in the persistent cultures. Analysis of an additional model of Cp. pneumoniae persistence, induced by limitation of host cell iron, revealed that ychF, yhbZ and yphC were also up-regulated in the persistent cultures. This study provided the most comprehensive analysis of Cp. pneumoniae gene transcription to date and suggest that chlamydial GTPases serve a role in generation of the persistent chlamydial phenotype. Cloning and expression of Cp. pneumoniae and Cp. abortus yhbZ, including demonstration of in vitro GTPase activity, indicates that this chlamydial gene encodes a member of the universally conserved and essential bacterial Obg subfamily of GTPases. Evidence is building that members of this latter family of bacterial GTPases are important regulators of bacterial growth and morphological differentiation in developmentally complex bacteria. Over-expression of chlamydial YhbZ subfamily GTPases in Escherichia coli revealed inhibition of bacterial growth and disruption of cell division and chromosome functions leading to the generation of elongated cells with limited chromosome segregation, as described for Obg subfamily members from E. coli and other bacteria. Although more analysis is required, we suggest a novel mechanism of chlamydial Obg GTPase regulation involving sensing of host cell GTP/GDP pools to control secondary differentiation of reticulate bodies (RBs) back to elementary bodies (EBs). Analysis of the chlamydial complement of bacterial GTPases was extended to HflX, a previously uncharacterised and only predicted GTPase conserved in bacteria. HflX sequence analysis revealed conservation of G motifs responsible for nucleotide binding and hydrolysis (G1, G3, G4) and protein interaction (G2), although the latter was unique to HflX subfamily GTPases. Recombinant Cp. pneumoniae HflX displays GTPase activity with nucleotide specificity for GTP. We tested Cp. pneumoniae HflX function by over-expression in E. coli which led to inhibition of growth in E. coli and elongation of cells with normal chromosome partitioning. This phenotype was the probable result of disruption of a stage in cell division subsequent to chromosome segregation. This present study provides the first evidence to show that bacterial HflX is a GTPase and suggests a regulatory role in bacterial cell cycle control.

Members of the important disease causing bacterial generas, Chlamydia and Chlamydophila, are characterised by a complex developmental cycle which is comprehensively described by microscopy. The inability to use standard genetic techniques for this obligate intracellular bacterium, however, means that significant gaps in our understanding of the molecular mechanisms used to control growth and development of Chlamydia still exist. The current study investigated the function of bacterial guanosine triphosphatases (GTPases), components of the organism's limited signal transduction arsenal, in regulatory control of the chlamydial development cycle. Initial analysis of the gene transcription of chlamydial GTPases and other predicted signal transduction genes using real time RT-PCR, in a Chlamydophila pneumoniae A-03 tryptophan depletion model of persistence, revealed significant differential expression of genes in response to the addition of interferon gamma (IFN-γ). Predicted chlamydial GTPase encoding genes, ychF, yhbZ and yphC, associated with ribosome function amongst other processes were strongly up-regulated, while hflX was down-regulated in the persistent cultures. Analysis of an additional model of Cp. pneumoniae persistence, induced by limitation of host cell iron, revealed that ychF, yhbZ and yphC were also up-regulated in the persistent cultures. This study provided the most comprehensive analysis of Cp. pneumoniae gene transcription to date and suggest that chlamydial GTPases serve a role in generation of the persistent chlamydial phenotype. Cloning and expression of Cp. pneumoniae and Cp. abortus yhbZ, including demonstration of in vitro GTPase activity, indicates that this chlamydial gene encodes a member of the universally conserved and essential bacterial Obg subfamily of GTPases. Evidence is building that members of this latter family of bacterial GTPases are important regulators of bacterial growth and morphological differentiation in developmentally complex bacteria. Over-expression of chlamydial YhbZ subfamily GTPases in Escherichia coli revealed inhibition of bacterial growth and disruption of cell division and chromosome functions leading to the generation of elongated cells with limited chromosome segregation, as described for Obg subfamily members from E. coli and other bacteria. Although more analysis is required, we suggest a novel mechanism of chlamydial Obg GTPase regulation involving sensing of host cell GTP/GDP pools to control secondary differentiation of reticulate bodies (RBs) back to elementary bodies (EBs). Analysis of the chlamydial complement of bacterial GTPases was extended to HflX, a previously uncharacterised and only predicted GTPase conserved in bacteria. HflX sequence analysis revealed conservation of G motifs responsible for nucleotide binding and hydrolysis (G1, G3, G4) and protein interaction (G2), although the latter was unique to HflX subfamily GTPases. Recombinant Cp. pneumoniae HflX displays GTPase activity with nucleotide specificity for GTP. We tested Cp. pneumoniae HflX function by over-expression in E. coli which led to inhibition of growth in E. coli and elongation of cells with normal chromosome partitioning. This phenotype was the probable result of disruption of a stage in cell division subsequent to chromosome segregation. This present study provides the first evidence to show that bacterial HflX is a GTPase and suggests a regulatory role in bacterial cell cycle control.

Superaustenitická korozivzdorná ocel typu 22Cr25NiWCoCu určená pro vysokoteplotní aplikace v energetickém průmyslu byla studována za podmínek nízkocyklové únavy při pokojové a zvýšené teplotě. Jednotlivé vzorky byly podrobeny různým zátěžným procedurám, což umožnilo studium materiálové odezvy spolu s mechanismem poškození. Křivky cyklického zpevnění/změkčení, cyklického napětí a Coffin-Mansonovy křivky byly vyhodnoceny. Únavová životnost materiálu byla diskutována s ohledem na uplatňované mechanismy poškození, které se vyvinuly za specifických zátěžných podmínek. Standardní izotermální únavové experimenty byly provedeny při pokojové a zvýšené teplotě. Hysterezní smyčky zaznamenané během cyklického zatěžování byly analyzovány pomocí zobecněné statistické teorie hysterezní smyčky. Pro různé amplitudy napětí byla určena jak distribuce hustoty pravděpodobnosti interních kritických napětí (dále PDF), tak rovněž zjištěn její vývoj během cyklického namáhání. Zjištěné průběhy PDF byly korelovány s vývojem povrchového reliéfu a vnitřního dislokačního uspořádání zdokumentované pro obě teploty pomocí rastrovací elektronové mikroskopie (SEM) vybavené technikou fokusovaného iontového svazku (FIB), která umožnila rovněž efektivní studium nukleace povrchových únavových trhlin. Při cyklickém zatížení při pokojové teplotě byla pozorována lokalizace cyklické plastické deformace do perzistentních skluzových pásů (PSP). V místech, kde tyto PSP vystupují na povrch materiálu byly pozorovány perzistentní skluzové stopy (PSS) tvořené extruzemi a intruzemi. Postupné prohlubování intruzí, zejména na čele nejhlubší intruze, vede k iniciaci únavové trhliny. Odlišný mechanismus tvorby trhlin byl zjištěn při únavové zkoušce při zvýšené teplotě, kde zásadní roli hrál vliv prostředí. Rychlá oxidace hranic zrn a jejich následné popraskání představuje dominantní mechanismus v I. stádiu nukleace trhlin. Aplikace desetiminutové prodlevy v tahové části zátěžného cyklu vedlo k vývoji vnitřního (kavitačního) poškozování. Mechanismy vnitřního poškozování byly studovány na podélných řezech rovnoběžných s napěťovou osou zkušebních vzorků. Trhliny a jejich vztah k hranicím zrn a dvojčat byly studovány pomocí difrakce zpětně odražených elektronů (EBSD). Vliv prodlevy na únavovou životnost byl korelován s vývojem povrchového reliéfu a vnitřního poškození. Vzorky z uvedené oceli byly rovněž podrobeny zkouškám termomechanické únavy (TMF), při nichž se v čase mění jak zátěžná síla tak i teplota. Termomechanické únavové zkoušky v režimu soufázném (in-phase) a protifázném (out-of-phase) byly provedeny jak s prodlevou, tak i bez ní. Ve všech případech bylo pozorováno rychlé cyklické zpevnění bez ohledu na použitou amplitudu deformace, u vzorků testovaných v out-of-phase režimu byla zjištěna tendence k saturaci. Zkoumáním povrchového reliéfu za pomocí technik SEM a FIB byla odhalena přednostní oxidace hranic zrn a následné praskání těchto hranic kolmo k ose zatížení. Prodlevy v cyklech při maximálním napětí vedly ke zvýšení amplitudy plastické deformace a následně ke creepovému poškození ve formě vnitřních kavit a trhlin. Interkrystalické šíření trhlin bylo pozorováno na vzorcích testovaných v režimu in-phase. Vývoj poškození v režimu out-of-phase nebyl principiálně ovlivněn zařazením prodlevy do zátěžného cyklu. Charakteristickým znakem namáhání v režimu out-of-phase je nukleace několika trhlin v homogenní oxidické vrstvě jdoucích napříč zrny kolmo k ose zatěžování.

Pokročilá vysoce legovaná austenitická nerezová ocel Sanicro 25 s Fe-Ni-Cr matricí byla studována za podmínek nízkocyklové únavy za pokojové a vysoké teploty 700 °C. Široká škála moderních experimentálních technik byla použita ke studiu vzájemně souvisejících efektů chemického složení slitiny, mikrostrukturních změn a deformačních mechanismů, které určují odolnost materiálu vůči poškození. Hlavní úsilí bylo zaměřeno na studium iniciace únavových trhlin a růstu krátkých trhlin, tedy dvě stádia, která hrají zásadní roli ve výsledné celkové délce únavového života materiálu v provozu. • Vnitřní deformační mechanismy byly korelovány s vývojem povrchového reliéfu, který je pozorován ve formě persistentních skluzových stop na povrchu. Bylo zjištěno, že vysoce planární charakter dislokačního skluzu způsobuje vysokou lokalizaci cyklické plastické deformace do persistentních skluzových pásů, což v důsledku vede k nukleaci “Stage I” trhlin, která je spojena s přítomností persistentních skluzových stop na povrchu ve všech studovaných vzorcích. Bylo zjištěno, že praskání dvojčatových hraníc je taktéž spojeno s přítomností persistentních skluzových stop podél povrchové stopy dvojčatové roviny. • Interkrystalická iniciace únavové trhliny byla pozorována pouze zřídka, a to za podmínek zatěžování amplitudami vysoké deformace. Bylo zjištěno že interkrystalická iniciace je spojena s přítomností persistentních skluzových stop na hranicích zrn. Hranice zrn praskají za podmínek externího tahového zatížení zejména z důvodu vysokého počtu nekompatibilit na hranicích zrn, které jsou způsobené tvarem persistentních skluzových stop. • Mechanismy růstu přirozených krátkých trhlin byly studovány na vzorcích vystavených nízkocyklove únava s nízkou i vysokou deformací. Role mikrostruktury byla analyzována pomocí experimentálních technik a diskutována. • Rychlosti šíření nejdelších trhlin byly měřeny na vzorcích s mělkým vrubem. Výsledky byly analyzovány použitím přístupů lomové mechaniky založených na amplitudě KI a J-integrálu stejně jako na amplitudě plastické deformace. Všechny přístupy byly diskutovány v souvislosti s Mansonovými-Coffinovými křivkami únavové životnosti. Jednoduchý mocninový zákon růstu krátkých trhlin založený na amplitudě plastické deformace ukazuje velice dobrou korelaci se zákonem únavové životnosti. • Byla studována role oxidace v podmínkách cyklického zatěžování za vysokých teplot. Bylo zjištěno, že křehké praskání zoxidovaných hranic zrn hraje hlavní roli v počátečních stádiích nukleace trhlin. Později po iniciaci se dráha růstu trhliny mění preferenčně na transkrystalickou. Dráha šíření trhlin je velmi podobná dráze zjištěné při cyklování za pokojové teploty.

Depuis les années 1950, l'intensification des pratiques agricoles concourt à une augmentation de la pression anthropique entraînant une raréfaction des espèces spécialistes des parcelles cultivées, ce qui contribue à l'érosion de la diversité biologique des agroécosystèmes. Parmi les espèces en déclin, on compte de nombreuses messicoles dont le bleuet (Centaurea cyanus L.), fleur emblématique des moissons. Or, cette espèce peut rendre des services écosystémiques comme hôte de prédateurs de ravageurs des cultures et ressource privilégiée de certains pollinisateurs qui justifieraient son maintien dans les champs. Nous étudions ici des facteurs biologiques qui pourraient potentiellement contribuer à son déclin : distribution spatiale, potentialité de croissance, diversité génétique des populations, survie des semences, système de reproduction. Nous avons montré, par deux campagnes de relevés, que C. cyanus n'est pas une espèce indicatrice de diversité floristique dans la parcelle cultivée. Toutefois, lorsque que le bleuet est rare dans une région, il est associé à d'autres messicoles peu fréquentes. Par contre, s'il est commun, il est associé aux zones ayant la plus forte diversité végétale. Une expérience de semis dans différents compartiments de l'agrosystème, en absence de traitements herbicides, a mis en évidence que la potentialité de croissance des bleuets est plus élevée dans le plein champ du blé que dans la moutarde et les interfaces blé/bordure. Cette croissance est limitée de manière variable par les communautés adventices présentes dans les compartiments hors champs (bordures). L'analyse de la diversité génétique à l'aide de marqueurs microsatellites de bleuets dans une petite zone agricole montre que les populations sont connectées par des flux de gènes importants. Les barrières écologiques telles que les chemins, semblent être des facteurs de structuration plus importants que la distance géographique séparant les populations. La répartition du bleuet dans le paysage agricole n'est donc pas aléatoire et apparaît dépendante de la fréquence de l'espèce dans la région ainsi que des différents éléments du paysage. Les caractéristiques du cycle biologique du bleuet ont été étudiées grâce à des expériences au champ et en serre. Nous avons montré que la longévité des akènes enfouis dans le sol chute rapidement après deux ans. Le cycle saisonnier de la dormance permet deux cohortes de levées (automne et printemps). L'étude du système de reproduction a permis de mettre en évidence que les pollinisateurs sont nécessaires pour la fécondation et que les populations sont majoritairement auto-incompatibles. Il existe cependant des individus pseudo auto-incompatibles mais leur fréquence n'est pas liée à la taille des populations ou à leur niveau d'isolement spatial. Par ailleurs, dès que le coefficient de consanguinité augmente dans les populations, la valeur phénotypique des individus baisse. La dépression de consanguinité s'exprime alors principalement pendant la phase de la germination. L'ensemble de ces caractéristiques biologiques peuvent s'avérer défavorables au bleuet dans les agroécosystèmes simplifiés actuels et ont pu entraîner son déclin dans certaines régions

La dengue circule en Polynésie française sur un mode épidémique depuis plus de 35 ans. Néanmoins, en dépit de la taille relativement faible de la population de Polynésie française, la circulation de la dengue peut persister à de faibles niveaux pendant de nombreuses années. L’objectif de ce travail de thèse est de déterminer si l'épidémiologie de la dengue dans le système insulaire de la Polynésie française répond aux critères d’un contexte de métapopulation. Après avoir constitué une base de données regroupant les cas de dengue répertoriés sur les 35 dernières années, nous avons réalisé des analyses épidémiologiques descriptives et statistiques. Celles-ci ont révélé des disparités spatio-temporelles distinctes pour l’incidence de la dengue des archipels et des îles, mais la structure de l'épidémie globale à l’échelle de la Polynésie française pour un même sérotype ne semble pas être affectée. Les analyses de la métapopulation ont révélé l'incidence asynchrone de la dengue dans un grand nombre d’îles. Celle-ci s’observe plus particulièrement par la différence de dynamique de l’incidence entre les îles plus peuplées et celles ayant une population plus faible. La taille critique de la communauté nécessaire à la persistance de la dengue n’est même pas atteinte par la plus grande île de Polynésie Française, Tahiti. Ce résultat suggère que la dengue peut uniquement persister grâce à sa propagation d’île en île. L'incorporation de la connectivité des îles à travers des modèles de migration humaine dans un modèle mathématique a produit une dynamique de la dengue davantage en adéquation avec les données observées, que les tentatives de modélisation traitant la population dans son ensemble. Le modèle de la métapopulation a été capable de simuler la même dynamique que les cas de dengue observés pour l'épidémie et la transmission endémique qui a suivi pour la période de 2001 à 2008. Des analyses complémentaires sur la différenciation de l'incidence de la maladie et de l'infection seront probablement instructives pour affiner le modèle de métapopulation de l'épidémiologie de la dengue en Polynésie française
Dengue has been epidemic in French Polynesia for the past 35 years. Despite the relatively small population size in French Polynesia, dengue does not disappear and can persist at low levels for many years. In light of the large number of islands comprising French Polynesia, this thesis addresses the extent to which a metapopulation context may be the most appropriate to describe the epidemiology and persistence of dengue in this case. After compiling a database of dengue cases over the last 35 years, we used a number of descriptive and statistical epidemiological analyses that revealed distinct spatio-temporal disparity in dengue incidence for archipelago and islands. But the global structure of the epidemics of the same serotype were not affected. Metapopulation analyses revealed asynchronous dengue incidence among many of the islands and most notably larger islands lagged behind the smaller islands. The critical community size, which determines dengue persistence, was found to exceed even the largest island of Tahiti, suggesting that dengue can only exist by island-hopping. Incorporation of island connectedness through patterns of human migration into a mathematical model enabled a much better fit to the observed data than treating the population as a whole. The metapopulation model was able to capture to some extent the epidemic and low level transmission dynamics observed for the period of 2001-2008. Further analyses on differentiating incidence of disease and infection will likely prove informative for the metapopulation model of dengue epidemiology in French Polynesia

碩士
東吳大學
會計學系
102
Earnings is an important information in valuing firm’s value, but information content of negative earnings companies is weaker. Therefore, how to evaluate these companies is an important issue. In addition to value drivers mentioned in the literature, this study consider the loss characteristics of the negative earnings company and corporate life cycle stage, may have different information content of earnings, thereby affecting the value drivers. This study consider the loss characteristic of the negative earnings company, to distinguish between temporary losses and persistent losses, and examine its earnings information, investment activities, sustainability and corporate life cycle stage. The empirical results that persistent loss company have negative relation between earnings and market value, but after including value drivers of investment activities and sustainability, which will reduce the negative relationship. Finally, in the different life cycle stage, the relationship between the earnings and market value, in growth stage of temporary loss company have significant positive relationship, in the mature stage of persistent loss company does not exist negative relationship, and other stages of persistent still have significant negative relationship.

碩士
國立中興大學
會計學研究所
98
Earnings persistence is not discussed extensively in Taiwan. This paper examines the factors of affecting earnings persistence through the prior foreign studies and additional factor which add the business life cycle. The result is that the earnings persistence of grow and mature companies are more persistence than stagnant companies, but the earnings persistence of mature companies are not significant greater than grow companies. Beside, my additional finding is earnings persistence of operating cash flow which is more persistence than total accrual. After discompose total accrual to discretionary and non-discretionary accrual, I find the persistence of non-discretionary accrual more persistence than discretionary accrual. I also use the level of reliability to classify different net asset groups. My finding is that the more reliable net asset group is more persistence. In addition, this paper also adds other three factors which is different from earnings systematic risk, abnormal earnings and other operating income (loss). The result is that the systematic risk and other operating income (loss) are significant negative relation with earnings persistence. Abnormal earning is significant positive relation with earnings persistence.

Business organisations today are faced with the complex problem of dealing with evolution in their software information systems. This effectively concerns the accommodation and facilitation of change, in terms of both changing user requirements and changing technological requirements. An approach that uses the software development life-cycle as a vehicle to study the problem of evolution is adopted. This involves the stages of requirements analysis, system specification, design, implementation, and finally operation and maintenance. The problem of evolution is one requiring proactive as well as reactive solutions for any given application domain. Measuring evolvability in conceptual models and the specification of changing requirements are considered. However, even "best designs" are limited in dealing with unanticipated evolution, and require implementation phase paradigms that can facilitate an evolution correctly (semantic integrity), efficiently (minimal disruption of services) and consistently (all affected parts are consistent following the change). These are also discussed
Computing
M. Sc. (Information Systems)

碩士
輔仁大學
會計學系碩士班
101
In this research, we observed the loss for the year turnaround in the future state of the company to investigate the loss of the relevant variables on the impact of corporate turnaround continuing. Modeling to predict the probability of correct degree turnaround is divided into two phases: the first reference Joos and Plesko (2005) model, extending Joos and Plesko (2005) correction to join an influential financial indicators, the second stage considerations corporate life cycle changes possible impact, and then postponed due to the company at different stages of the life cycle, its earnings persistence have significant differences. Compare the predictive power of the regression model, the forecast does not consider the life cycle of the next year 's third annual turnaround observed probability , empirical results show that adding filters to the financial indicators with relevance , its high degree of predictive models correctly predict accurately 66.9 % . We found if consider which of the enterprise with different life cycle may influent six MJP LC Model, the prediction accuracy will be up to 69.5% . This indicates, the life cycle of sustained turnaround in the future there is a considerable degree of probability of impact, with a predictive capability. For the observation of the next 2-3 years consecutive year of continued turnaround for the company forecast losses in the first turnaround in year t +1 , t +2 in the first years of the first year t +3 earnings persistence, and then compare the predictive power of the regression model , the kind of empirical mode detection accuracy is high, predicting the future of t +2 and t +3 years of sustained turnaround correct rate , the results of Accession has influence financial indicators and consider enterprise in which the different life cycle stages , the model 's predictive power and explanatory power optimization . The research indicated that the modified MJP by LC Model results most predictive ability of the losses the company sustained losses degree rotation most explanatory power.

Dissertação de mestrado em Genética Molecular
As bactérias do género Acinetobacter são ubíquas no solo, esgotos e água. Tendo como objectivo avaliar a persistência e possíveis rotas de dispersão das Acinetobacter spp. no ciclo urbano da água, uma colecção de 254 isolados foram recuperados da água de uma estação de tratamento de águas (ETA) e de 12 torneiras. Numa triagem inicial, os isolados foram identificados preliminarmente usando primers específicos para 16S ARNr de Acinetobacter spp., levando à selecção de 179 isolados. Depois desta triagem, foi usado um esquema de mini-Multilocus Sequencing Typing (MLST) de maneira a conseguir a identificação ao nível da espécie, e quando possível, avaliar padrões de variação intra-específica. Foi determinada a resistência aos antibióticos amoxicilina, ticarcilina, cefalotina, ceftazidime, meropenemo, gentamicina, ciprofloxacina, sulfametoxazol, sulfametoxazol/trimetoprim, tetraciclina, sulfato de colistina e estreptomicina, pelo método de difusão de disco. Os padrões do mini-MLST e os perfis de resistência a antibióticos foram analisados como função do local de isolamento. Visto que não foram observados tipos de sequências (ST) idênticos nos dois ambientes amostrados, concluiu-se que Acinetobacter spp. isolados de torneiras não tinham origem na ETA. Não obstante, foi possível inferir a existência de uma fonte comum de Acinetobacter spp. nas torneiras, visto ter sido observado o mesmo ST em diferentes torneiras, assim como em distintos sistemas de distribuição de água. A respeito da persistência de Acinetobacter spp. nos diferentes locais de amostragem, os isolados com sequências de rpoB ou recA idênticas, que foram observadas nos diferentes períodos, foram distinguidos pelo fenótipo de resistência a antibióticos. Além disso, os dados obtidos sugerem que a densidade de Acinetobacter spp. no ciclo urbano da água pode aumentar durante o período de Verão, diminuindo durante o Inverno, podendo haver uma nova colonização no ano seguinte. Sete isolados pertencentes ao mesmo grupo de ST, apresentavam distintos perfis de resistência a antibióticos, sugerindo que, ou essas resistências foram adquiridas após a colonização do sistemas de águas, ou o método de tipagem tem baixa resolução. Neste aspecto, admite-se que a análise de sequências nucleotídicas de outros genes contribuirá para uma melhor diferenciação de estirpes e portanto, permitirá ultrapassar a referida limitação.
Members of the genus Acinetobacter are ubiquitous in soil, sewage and water. Aiming the assessment of the persistence and possible routes of dispersion of Acinetobacter spp. in the urban water cycle, a collection of 254 bacterial isolates were recovered from two different types of water, from a water treatment plant (WTP) and from 12 taps. In the initial screening, isolates were presumptively identified using an Acinetobacter spp. specific 16S rRNA primer, leading to the selection of a set of 179 isolates. After this screening, a mini-MLST approach was used in order to achieve the identification to the species level and, whenever possible, to assess patterns of intra-specific variation. The antibiotic resistance to amoxicillin, ticarcillin, cephalothin, ceftazidime, meropenem gentamicin, ciprofloxacin, sulphamethoxazole, sulphamethoxazole/trimethoprim, tetracycline, colistin-sulphate, and streptomycin was determined using the diffusion disc method. The mini-MLST patterns and the antibiotic resistance profile were analyzed as a function of the isolation site. Given that no identical sequencing type (ST) was observed in both types of sampling site, it was concluded that Acinetobacter spp. isolated from the taps did not have origin in the WTP. Nevertheless, a common source of tap water Acinetobacter spp. was hinted by the observation of the same ST in different taps and water distribution systems (WDS). In respect to Acinetobacter spp. persistence in the different sampling sites, the isolates with identical rpoB or recA nucleotide sequences in the different sampling periods, were distinguished by antibiotics resistance patterns. Moreover, it was suggested that the presence of Acinetobacter spp. in the urban water cycle rises during the summer period and vanishes during winter, with a new colonization in the following year. Seven isolates belonging to the same ST group, could be distinguished on basis of the antibiogram phenotype, suggesting either that those resistance phenotypes were acquired after the water system colonization, or that the typing method had a the poor resolution . The use of additional gene sequences for strain differentiation will contribute to overcome this limitation.

碩士
明新科技大學
企業管理研究所
96
Equity fund is the most rapid earnings in the fund market, but it brings the highest risk investment. Investors will take the past performance of fund while they will choose to invest which fund in the past. Because investors believe that performance is persistency. But Lee and Swaminathan advanced “the momentum life cycle theory” in 2000, it was verification that the Fund didn’t have the performance persistency in specific circumstances. My research is based on turnover and return of internal equity fund market in April 2002 to April 2008 for the research sample. My research will use the Spearman’s rank correlation coefficient, t-test and Probit model to analyze the performance persistency of internal equity fund by momentum life cycle theory. However, the result means that the momentum life cycle theory isn’t appear my research. The result means that the reversal and overreaction effect were not appear in the winners of high turnover and losers of low turnover. And the performance of internal equity fund no matter in the winners (losers) of high（low）turnover are persistency.

abstract: Existing literature consistently documents a relationship between book-tax differences and future financial performance. Specifically, large book-tax differences are associated with lower earnings persistence. I contend that one reason the tax information contained in financial statements is informative about future earnings is that the relationship between book income and taxable income captures information about a firm's life cycle stage. Using a life cycle measure from the literature, I use fundamental analysis to group firm-year observations into life cycle stages and document a link between book-tax differences and firm life cycle. I build on prior studies that find a relation between earnings persistence and book-tax differences, and earnings persistence and firm life cycle. I find that after controlling for firm life cycle stage, the association between large positive book-tax differences and lower earnings persistence does not hold. My results offer an economic theory based explanation for the relation between book-tax differences and earnings persistence as an alternative explanation to findings in prior research.
Dissertation/Thesis
Ph.D. Accountancy 2012

碩士
國立中興大學
會計學研究所
101
As the transition of the economy in Taiwan, the OEM industry which built the national economy decreased its profits day by day. Accordingly, this situation stimulates the enterprise to establish a brand and to create values added. There is so many brands stand out conspicuously in the world, however, could this method maintain the earnings efficiently and stable the earnings persistence? That’s the main question to think about. Therefore, the following is going to focus on the earnings persistence between the OBM and the OEM firms. In the meantime, with the conception of the business life cycle, this paper tries to discuss the different earnings persistence and observe the dissimilarity between the OBM and the OEM firms in each life cycle phase. This paper use Taiwanese listed companies as the sample from 2007 to 2011. This paper use Sloan (1996) model to estimate the earnings persistence, and employ the Anthony and Ramesh’s (1992) method to divide sample to different corporate life cycle stage. First, the empirical results show that the earnings persistence of the OBM firms is better than the OEM firms in Taiwan. Second, after considering the life-cycle factors, the earnings persistence of the OBM firms are better than the OEM firms in the growth, maturity and recession stage. Third, for OBM firms, the earnings persistence of growth are more persistence than recession stage, but the earnings persistence of mature companies are not significant greater than the growth and recessional companies. Finally, for OEM firms, the earnings persistence of maturity stage are greater than growth and recession stage, but the earnings persistence are no significant different between mature and recession stage.

碩士
國立中興大學
會計學研究所
103
This paper examines the earnings persistence between the conventional industry and the high-tech industry. Furthermore, with the concept of the business life cycle, this paper tries to discuss the difference of earnings persistence between the conventional industry and the high-tech industry in each life cycle stage. Moreover, this paper examines the coefficient of earnings persistence for each industry under the conventional industry and the high-tech industry. This paper uses listed companies in Taiwan as the sample from 2003 to 2012. We use Sloan (1996) model adding industrial dummy variable to estimate the earnings persistence, and employ the Anthony and Ramesh’s (1992) method to divide sample into three business life cycle stages. The empirical results show that the earnings persistence of the high-tech industry is greater than the conventional industry in Taiwan. After considering the life-cycle factors, the earnings persistence of the high-tech industry is still higher than the conventional industry in the growth, mature and stagnant stage separately. Furthermore, for the conventional industry, the earnings persistence of stagnant stage is less persistence than growth and mature stage, but the earnings persistence is no significant different between the growth and mature stage. Meanwhile, for the high-tech industry, the earnings persistence is no significant different in each business life cycle stage. Finally, additional test points that the steel industry, the textile industry and the construction industry are the major reasons why the earnings persistence of the conventional industry is less persistence than the high-tech industry in Taiwan. Overall, the earnings persistence of the high-tech industries are greater than the conventional industries in Taiwan.

碩士
銘傳大學
金融研究所碩士在職專班
90
A Study on the Persistence and Momentum Life Cycle of Mutual Fund Performance－A Premier Method for Constructing Well Performed Fund of Funds Student：Shih-Tsung Kuo Advisors：Dr. Yang-Cheng Lu Dr. Chung-Jung Lee Abstract Instead of previous works primarily relying on track-records of such a mutual fund. This paper is to examine the trading strategies for open-end stock mutual fund in Taiwan based on the momentum life cycle model of Lee & Swaminathan (2000). It starts with the testing momentum strategy and then shareholder ratio will be put into the model to account for the trading strategies over the observed period. The empirical evidences are summarized as follows: (1) Over the observed period, the market is inefficient, so the proper strategies make profit. (2) Momentum strategy is profitable for fund market in Taiwan over short term to long term. (3) The shareholder ratio and its change are good indicator to reversal signals of trading cycle: the loser with low shareholder ratio persists over the short and mediate term and the one with high shareholder ratio will reverse; meanwhile, the winner with low shareholder ratio will reverse and the one with high shareholder ratio persists. (4) With the same shareholder ratio, the winner of today will be more profitable in the future than the loser of the last period. (5) With empirical evidence that stock mutual fund with high shareholder ratio is more profitable than one with low shareholder ratio and the amount of profit form the winner portfolio is larger than that of the loser portfolio, the trading strategy of buying the winner with high shareholder ratio and short-selling the loser with low one today results in the best performance; Meanwhile, one-dimension momentum works better than the later momentum of life cycle with portfolio based on such a trading strategy that buys the winner with high shareholder ratio and short-sells the loser with high one. Keywords：momentum life cycle, underreaction, overreaction, fund performance

Depuis la mise en place de la réforme, il y a plus de dix ans, les directions d’établissement sont tenues de trouver des solutions alternatives au redoublement, afin d’aider les élèves en difficulté à rattraper leur retard. C’est afin de répondre à cet impératif que la classe de prolongation de cycle a été mise en place dans les écoles secondaires. Des élèves en fin de 1er cycle, jugés incapables de poursuivre au cycle supérieur, y sont regroupés et pendant une année, ils bénéficient de mesures de soutien afin d’atteindre le niveau de compétence attendu (plus précisément en français en en mathématiques) pour pouvoir vivre un passage réussi au second cycle. Peu de résultats de recherches sont toutefois disponibles quant à l’efficacité de cette modalité. La présente étude vise donc à estimer l’incidence de deux modèles de prolongation de cycle (co-enseignement et avec enseignant unique), sur la motivation et l’adaptation psychosociale des élèves. Ainsi, les élèves qui expérimentent un modèle de co-enseignement demeurent en groupe fermé et sont accompagnés par trois enseignants titulaires qui se partagent la responsabilité de la quasi-totalité des composantes du programme de formation. Les élèves qui expérimentent un modèle avec enseignant unique demeurent eux aussi en groupe fermé, mais sont encadrés par une seule enseignante titulaire qui assume la responsabilité des enseignements en français et en mathématiques. Les autres matières sont enseignées par des spécialistes. Cent trente-quatre élèves au total, fréquentant trois écoles secondaires francophones montréalaises situées en milieu défavorisé, ont donc formé les groupes expérimentaux et témoins. En début et en fin d’année, les participants ont répondu à un questionnaire d’enquête mesurant l’évolution de leur motivation générale pour les apprentissages, de leur motivation spécifique aux disciplines, de leur adaptation psychosociale, de même que certaines facettes de leurs relations avec leurs pairs, leurs enseignants et leurs parents. Les résultats d’analyses de variance multivariées à mesures répétées (MANOVA) et des tests univariés subséquents permettent d’observer, chez les élèves qui ont expérimenté la prolongation de cycle en co-enseignement, une augmentation de leur sentiment de compétence général vis-à-vis l’école. De plus, leurs buts de performance-évitement et leur anxiété sociale ont diminué. Chez les élèves qui ont expérimenté la prolongation de cycle avec enseignant unique, ce même sentiment de compétence vis-à-vis l’école et celui spécifique au français ont augmenté. En revanche, ces derniers s’expriment plus négativement que leurs homologues en ce qui concerne leur intérêt général envers l’école, leur sentiment d’appartenance à leur école et leurs relations avec leurs pairs. Ces résultats indiquent donc que cette mesure a un effet mitigé sur la motivation et l’adaptation psychosociale des élèves. De plus, les quelques bénéfices perçus peuvent être la conséquence du fait de se retrouver dans un environnement scolaire moins compétitif. Cela dit, il apparaît important de préciser que les enseignants qui ont testé le modèle de co-enseignement en étaient à une première expérience. Leurs pratiques sont susceptibles de se bonifier, ce qui laisse croire que des résultats plus disparates pourraient éventuellement être observés entre ces deux modèles de prolongation. Par ailleurs, la pérennité des gains observés est inconnue. En conséquence, il conviendrait de poursuivre cette étude pour être en mesure de déterminer si ceux-ci sont durables dans le temps et afin de constater la pleine mesure de l’efficacité du modèle de prolongation de co-enseignement.
Since the implementation of the education reform, over ten years ago, school administrators are required to focus on other measures to help students with difficulties catch up rather than grade retention. It is with this intent that the prolongation class was set up in high schools. Students at the end of the 1st cycle, deemed unable to continue to the upper level, are grouped together in this class, for a year, and enjoy different support measures to achieve the level of competency expected (more specifically in Language arts and mathematics), in order to experience a successful transition to the 2nd cycle. Very little empirical research is available regarding the effectiveness of this modality. This study aims to estimate the impact of two different prolongation models (co-teaching and single teacher) on students’ motivation and psychosocial adjustment. Students in the co-teaching model remain in a closed group and are accompanied by three teachers who share the responsibility for almost all components of the program. Students with a single teacher also remain in a closed group, they have a home room teacher who handles lessons in Language arts and mathematics while other subjects are taught by specialist teachers. One hundred and thirty four students, attending three French high schools, located in low SES (socioeconomic status) districts of Montreal, formed experimental and control groups. At the onset and at the end of their year of prolongation, participants completed a questionnaire that targeted their general academic motivation, their domain-specific motivation, their psychosocial adjustment, and some aspects of their relations with their peers, their teachers and their parents. Results of multivariate analysis of variance (repeated measures MANOVA) and subsequent univariate tests show that competency beliefs increased among students who experienced the co-teaching prolongation model. In addition, their performance-avoidance goals and social anxiety decreased. Among students experiencing prolongation with a single teacher, general and Language arts competency beliefs increased, however, they expressed themselves more negatively than their counterparts regarding their interest in schooling, their sense of belonging to their school and their relationships with their peers.These results indicate that this measure has a mixed effect on students’ motivation and psychosocial adjustment. Perceived gains may be due to being in a less competitive school environment. That being said, it is important to mention that teachers who tested the co-teaching model were using it for the first time. Their practices are likely to improve, in which case, more disparate results could potentially be observed between the two prolongation models. Since the sustainability of these gains is unknown, this study should continue in order to observe whether they are long lasting as well as, to measure and determine the full effectiveness of the co-teaching prolongation model.

Toxoplasma gondii ist einer der häufigsten intrazellulären Protozoen weltweit und ein wichtiger Krankheitserreger des Menschen. Er kommt in drei Lebensstadien vor: Sporozoiten, Tachyzoiten und Bradyzoiten. Während Sporozoiten nach sexueller Vermehrung im Endwirt (Katzenartige) und Freisetzung in die Umwelt gebildet werden, entstehen Tachyzoiten und Bradyzoiten asexuell durch Endodyogenie in Zwischenwirten wie Vögeln, Säugetieren und dem Menschen. Tachyzoiten sind schnell replizierende Parasiten, die nahezu jede nukleäre Zelle des Körpers infizieren können. Dagegen bilden die nach Differenzierung von Tachyzoiten entstehenden, weitgehend ruhenden Bradyzoiten Gewebszysten und persistieren bevorzugt in neuronalen oder muskulären Geweben der Zwischenwirte. Der Verzehr von Bradyzoiten-haltigem, rohem oder ungegartem Fleisch von T. gondii-infizierten Nutztieren ist einer der Hauptübertragungswege des Parasiten auf den Menschen und kann zum Ausbruch der Toxoplasmose-Krankheit führen. Die Toxoplasmose ist vor allem bei immunsupprimierten Patienten und erstmalig infizierten Schwangeren nach Übertragung auf den Fötus klinisch gefährlich und kann sogar tödlich enden. Da Fleischverzehr infizierter Nutztiere einen der Hauptinfektionswege darstellt, weisen Skelettmuskelzellen (SkMZ) eine enorme Bedeutung für die Übertragung von Toxoplasma auf den Menschen auf. Das Ziel dieser Arbeit war es daher, zelltyp-spezifische Faktoren zu identifizieren und zu charakterisieren, die die Toxoplasma-Entwicklung und Bradyzoitenbildung in SkMZ regulieren. Die Untersuchungen wurden mithilfe der murinen C2C12-SkMZ-Linie in vitro durchgeführt, die von proliferierenden Myoblasten in Pferdeserum-haltigem Medium oder aufgrund erhöhter Zelldichte effektiv zu polykernigen Myotuben differenzierten. Die Effektivität der terminalen Differenzierung von C2C12-SkMZ wurde durch den Nachweis muskelspezifischer Marker wie MyoD, Myogenin und Myosin Heavy Chain (MyHC) mittels Reverse Transkriptase-qPCR (RT qPCR), Immunfluoreszenz sowie Nachweis des Zellzyklusarrests mittels BrdU-Markierung validiert. Die Infektion von terminal differenzierten C2C12-Myotuben, proliferierenden C2C12-Myoblasten und murinen NIH3T3-Kontrollfibroblasten mit T. gondii zeigte, dass der Parasit in Myotuben deutlich mehr bradyzoitenspezifische ENO1- bzw. BAG1-Transkripte exprimierte als in Myoblasten und Fibroblasten. Außerdem war die Gewebszystenbildung bei gleichzeitig reduzierter Parasitenreplikation in terminal differenzierten C2C12-Myotuben deutlich erhöht. Demgegenüber förderten proliferierende C2C12-Myoblasten und NIH3T3-Fibroblasten die Replikation von Toxoplasma bei gleichzeitig geringer Bradyzoitenbildung. Diese Daten weisen erstmalig auf die Bedeutung des Zelltyps und dessen Differenzierung für die Parasitenentwicklung und die Stadienkonversion in SkMZ hin. Für genauere Untersuchungen von Zelltyp-spezifischen Interaktionen mit T. gondii wurden die Transkriptome von terminal differenzierten C2C12-Myotuben und Neuronen sowie von proliferierenden NIH3T3-Fibroblasten und Astrozyten vor und nach Infektion mit T. gondii für 24 Stunden mittels High-Throughput RNA-Sequenzierung ermittelt. Die Analysen zeigten einen deutlich größeren Einfluss der zelltyp-spezifische Genexpression auf das Gesamttranskiptom der vier Zelltypen als die Expressionsveränderungen aufgrund der Toxoplasma-Infektion. Allerdings wurden auch Gengruppen identifiziert, die in den terminal differenzierten SkMZ und Neuronen im Vergleich zu Fibroblasten und Astrozyten differentiell exprimiert waren. Des Weiteren bewirkte die T. gondii-Infektion eine signifikante Expressionssteigerung u. a. von Zellzyklus-regulierenden Transkripten spezifisch in terminal differenzierten SkMZ und Neuronen, was auf ihre mögliche Beteiligung an der Toxoplasma-Stadienkonversion hindeutete. Daher wurden anschließend die Expressionsprofile ausgesuchter Zellzyklusregulatoren im Laufe der terminalen C2C12-SkMZ-Differenzierung und der Toxoplasma-Infektion mittels RT qPCR- und Western Blot-Analysen untersucht. Während die Transkription der negativen Zellzyklus-Modulatoren Tspyl2 und dem ‚down stream‘-liegenden Targetgen p21 im Laufe der terminalen Differenzierung von C2C12-Myoblasten zunahm, sank begleitend die Transkription der Uhrf1- und Ccnb1- (CyclinB1) Aktivatoren. Nach Infektion wurde spezifisch in Myotuben, nicht aber in Myoblasten oder Fibroblasten, eine weitere Steigerung der Tspyl2-Transkripte durch RT-qPCR-Analysen nachgewiesen. Gleichzeitig reagierten C2C12-Myotuben auch mit Hochregulation der Uhrf1- und Ccnb1-Transkription auf Toxoplasma-Infektion. Allerdings wurde durch BrdU-Markierung nachgewiesen, dass die spezifische Modulation von Zellzyklusregulatoren nach Infektion von Myotuben den Zellzyklusarrest nicht aufhob und C2C12-Myotuben nicht zur Zellteilung anregte. Da Überexpression von CDA-1 (humanes Tspyl2-Ortholog) in humanen Fibroblasten die Stadienkonversion von T. gondii fördert, wurde die Funktion des Tspyl2-Zellzyklusregulators in SkMZ analysiert. ‚Knock-down‘ von Tspyl2 mittels shRNA unterdrückte effektiv die terminale C2C12-Myoblastendifferenzierung. Bemerkenswerterweise führte dies nach T. gondii-Infektion zweier ausgesuchter Tspyl2 shRNA-C2C12-Transfektanten zu einer verstärkten Toxoplasma-Replikation im Vergleich zu Kontrolltransfektanten und WT Myotuben. Gleichzeitig war in Tspyl2-‚Knock-down‘-Mutanten die Parasitendifferenzierung zum Bradyzoitenstadium sowie die Gewebezystenbildung vermindert. Diese Ergebnisse zeigen erstmalig, dass in SkMZ die spontane Differenzierung von T. gondii zum Bradyzoiten wesentlich von dem Zellzyklusregulator Tspyl2 und der terminalen Myotubendifferenzierung abhängt. Differenzierung von SkMZ führte u.a. auch zu veränderten Expressionsprofilen von Zytokinen und Chemokinen in C2C12-Myotuben, -Myoblasten und Kontrollfibroblasten. So wurden mehrere pro-inflammatorischen Zytokine in Myotuben deutlich stärker als in Myoblasten oder Fibroblasten exprimiert. Nach Infektion von C2C12-Myotuben stiegen die Transkriptmengen von IL-23, IL 1α und IL 1β an. Diese Ergebnisse könnten neben Zellzyklusregulatoren auch auf den Einfluss von Immunfaktoren bei der Zelltyp-spezifischen Stadienkonversion in differenzierten SkMZ hindeuten In dieser Arbeit wurde zum ersten Mal gezeigt, dass der Differenzierungsstatus der SkMZ die Stadienkonversion und die Gewebszystenbildung eindeutig beeinflusst. Da die terminale SkMZ-Differenzierung von Zellzyklusregulatoren eingeleitet wird und ihre Expressionen offensichtlich unter dem Einfluss der T. gondii-Infektion stehen, könnten sie einen Einflus auf die Induktion der Stadiendifferenzierung von schnell replizierenden Tachyzoiten zu persistierenden Bradyzoiten ausüben, was am Beispiel des negativen Zellzyklusregulators Tspyl2 in dieser Arbeit nachgewiesen wurde. Des Weiteren wurde gezeigt, dass Myotuben mit der Produktion von proinflammatorischen Molekülen aktiv auf die Toxoplasma-Infektion reagieren und ihre Expression zur lokalen Immunantwort der SkMZ beitragen dürften.