The influence of macroclumps for free–free spectral energy distributions (SEDs) of ionized winds is considered. The goal is to emphasize distinctions between microclumping and macroclumping effects. Microclumping can alter SED slopes and flux levels if the volume filling factor of the clumps varies with radius; however, the modifications are independent of the clump geometry. To what extent does macroclumping alter SED slopes and flux levels? In addressing the question, two specific types of macroclump geometries are explored: shell fragments (pancake-shaped) and spherical clumps. Analytic and semi-analytic results are derived in the limiting case that clumps never obscure one another. Numerical calculations based on a porosity formalism is used when clumps do overlap. Under the assumptions of a constant expansion, isothermal, and fixed ionization wind, the fragment model leads to results that are essentially identical to the microclumping result. Mass-loss rate determinations are not affected by porosity effects for shell fragments. By contrast, spherical clumps can lead to a reduction in long-wavelength fluxes, but the reductions are only significant for extreme volume filling factors.

The blue hypergiant Cyg OB2 12 (B3Ia+) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using the Chandra observatory. PoWR model atmospheres were calculated to provide realistic wind opacities and to establish the wind density structure. We find that collisional de-excitation is the dominant mechanism depopulating the metastable upper levels of the forbidden lines of the He-like ions Si xivand Mg xii. Comparison between the model and observations reveals that X-ray emission is produced in a dense plasma, which could reside only at the photosphere or in a colliding wind zone between binary components. The observed X-ray spectra are well-fitted by thermal plasma models, with average temperatures in excess of 10 MK. The wind speed in Cyg OB2 12 is not high enough to power such high temperatures, but the collision of two winds in a binary system can be sufficient. We used archival data to investigate the X-ray properties of other blue hypergiants. In general, stars of this class are not detected as X-ray sources. We suggest that our new Chandra observations of Cyg OB2 12 can be best explained if Cyg OB2 12 is a colliding wind binary possessing a late O-type companion. This makes Cyg OB2 12 only the second binary system among the 16 known Galactic hypergiants. This low binary fraction indicates that the blue hypergiants are likely products of massive binary evolution during which they either accreted a significant amount of mass or already merged with their companions.

Context. High spectral resolution and long exposure times are providing unprecedented levels of data quality of massive stars at X-ray wavelengths. Aims. A key diagnostic of the X-ray emitting plasma are the fir lines for He-like triplets. In particular, owing to radiative pumping effects, the forbidden-to-intercombination line luminosity ratio, R = f∕i, can be used to determine the proximity of the hot plasma to the UV-bright photospheres of massive stars. Moreover, the era of large observing programs additionally allows for investigation of line variability. Methods. This contribution is the second to explore how variability in the line ratio can provide new diagnostic information about distributed X-rays in a massive star wind. We focus on wind integration for total line luminosities, taking account of radiative pumping and stellar occultation. While the case of a variable stellar radiation field was explored in the first paper, the effects of wind variability are emphasized in this work. Results. We formulate an expression for the ratio of line luminosities f∕i that closely resembles the classic expression for the on-the-spot result. While there are many ways to drive variability in the line ratio, we use variable mass loss as an illustrative example for wind integration, particularly since this produces no variability for the on-the-spot case. The f∕i ratio can be significantly modulated owing to evolving wind properties. The extent of the variation depends on how the timescale for the wind flow compares to the timescale over which the line emissivities change. Conclusions. While a variety of factors can ellicit variable line ratios, a time-varying mass-loss rate serves to demonstrate the range of amplitude and phased-dependent behavior in f∕i line ratios. Importantly, we evaluate how variable mass loss might bias measures of f∕i. For observational exposures that are less than the timescale of variable mass loss, biased measures (relative to the time-averaged wind) can result; if exposures are long, the f∕i ratio is reflective of the time-averaged spherical wind.

Les disruptions sont des pertes violentes et très rapides (environ 20 ms) du confinement des plasmas de tokamak qui peuvent conduire à des endommagements de la structure du tokamak. Elles génèrent des charges thermiques sur les composants face au plasma, des forces électromagnétiques dans les structures de la machine et produisent des électrons découplés relativistes pouvant perforer l'enceinte à vide. Pour des futurs réacteurs, il sera indispensable d'amortir ces effets. L'injection massive de gaz est une des méthodes proposées dans ce but. Son étude expérimentale et numérique est l'objet de la thèse. Des expériences menées sur les tokamaks Tore Supra et JET ont montré que l'injection de gaz légers comme l'hélium empêchaient la production d'électrons découplés, au contraire des gaz plus lourds. Les gaz légers sont en effet capables d'accroître suffisamment la densité du plasma pour empêcher la création de ces électrons. En revanche, les gaz lourds permettent de dissiper par rayonnement et de façon plus bénigne une partie de l'énergie thermique du plasma. Tous les gaz diminuent les forces électromagnétiques. Des mélanges de gaz ont également été testés avec succès pour profiter des avantages des deux types de gaz. La pénétration du gaz dans le plasma semble liée à des instabilités MHD augmentant le transport radial du gaz ionisé vers le centre, mais empêchant la propagation des neutres au-delà d'une surface critique. Des simulations d'injections massives ont été réalisées avec le code 3D MHD Jorek, en y ajoutant un modèle de fluide neutre. Les résultats montrent que la croissance des instabilités MHD est plus rapide lorsque de grandes quantités de gaz sont injectées et que les surfaces rationnelles sont successivement ergodisées lors de la pénétration du front de densité dans le plasma, conformément aux observations expérimentales.

Le sulfure de Nickel (NiS) peut former des inclusions dans les verres trempés conduisant à une frac-ture due à la transformation de phase avec changement de volume. Un traitement thermique, provo-quant cette transformation de phase, est actuellement utilisé afin de réduire cet effet. Pour proposer des traitements plus efficaces, une étude allant des mécanismes de transformation jusqu'à la modéli-sation a été menée. Selon la composition et la température, deux mécanismes de transformation (avec ou sans partition) ont été mis en évidence par l'étude microstructurale et calorimétrique donne les lignes directrices de la modélisation. Une étude in situ en microscope optique a fourni les informa-tions complémentaires indispensables (taux de germination, mobilité des interfaces) pour construire des modèles cinétiques. La modélisation décrit la transformation en condition isotherme pourra être adaptée aux conditions anisothermes proches du traitement industrie

<p>Massiva onlinerollspel är idag mycket populära och försäljningen och spelandet utav dessa ökar markant. I och med detta väcks frågan om vad det är i dessa onlinespel som gör att människor spelar och fortsätter spela. Denna uppsats inriktas främst mot MMORPG:s, Massively Multiplayer Online Role-Playing Games, då författarna anser att det är i denna onlinespelsgenre den största möjligheten att finna och definiera de faktorer, som påverkar</p><p>spelares vilja att spela, finns. För att ta reda på dessa faktorer skapades en enkät vars frågor utformades med en gameflowmodell i baktanken. Denna enkät lades sedan ut på sex olika onlinespelsanknutna forum, där totalt 105 spelare anonymt deltog. Den bygger dock även på tidigare gjorda undersökningar och rapporter om onlinespelandets anledningar, analyserade artiklar inom ämnet MMORPG spel och sist men inte minst författarnas egna erfarenheter utav MMORPG spel.</p>

Ce mémoire s'intéresse à la représentation de l'Iran par l'administration George W. Bush, telle que véhiculée par la rhétorique officielle de cette administration. Par une analyse de discours poststructuraliste portant sur le lexique, les tropes et les liens intertextuels employés par le président et la Maison-Blanche dans les communications orales et écrites officielles, et en particulier celles publiées durant le deuxième mandat de cette administration (2005-2009), le mémoire mettra en évidence trois modes de représentation de l'Iran: (1) comme État soutenant le terrorisme; (2) comme État dédié à la prolifération et à l'utilisation d'armes de destruction massive; et (3) comme État tyran. Le mémoire soutiendra que, pris ensembles, ces trois modes de représentation ou discours contribuent à imposer une identité à l'État iranien, de même qu'à constituer ce dernier comme ennemi des États-Unis et comme menace à la sécurité nationale américaine et à la paix mondiale. En outre, le mémoire arguera que ces discours sur l'Iran concourent à consacrer une identité nationale positive pour l'Amérique, en représentant cette dernière comme une puissance exceptionnelle ayant la destinée manifeste de répandre les valeurs libérales dans le monde. Le mémoire soutiendra que ces discours sur l'Iran et les États-Unis participent, par extension, à consolider une hiérarchie morale américaine du monde, fortement genrée et racialisée, au sein de laquelle les États-Unis occupent la place prédominante. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Identité nationale, Analyse de discours, États-Unis, George W. Bush, République islamique d'Iran.

The ferromagnetic bulk metallic glasses (BMGs) started to be investigated only in the last 10 years.They are difficult to cast, but their properties are uniques. The work deals with casting, mechanical and soft magnetic properties of new Fe-based BMGs. Such alloys can be cast directly in samples with various geometries and they can be use as magnetic parts in different devices.

The history of recent galactic nucleosynthesis activity can be studied by <br />measurements of the 1.809 MeV gamma-ray line arising from the decay of <br />radioactive 26Al.<br />The COMPTEL telescope aboard the Compton Gamma-Ray Observatory, launched on <br />April 5, 1991, permits for the first time an extensive investigation of the <br />1.8 MeV radiation throughout the entire sky.<br />The aim of this thesis is to infer the galactic distribution of 26Al from <br />these measurements and to identify the dominant sources of this <br />radioactive isotope.<br /><br />The first part of the thesis is dedicated to the reconstruction of <br />the 1.8 MeV intensity distribution from the measured data.<br />It is demonstrated that the use of conventional deconvolution <br />algorithms, like maximum likelihood or maximum entropy inversion, <br />leads to lumpy, noise-dominated intensity distributions.<br />Nevertheless, simulations can help to assess the uncertainties in the <br />reconstructed images, which permits the scientific exploitation of the <br />recovered skymaps.<br />Alternatively, a multiresolution approach is proposed, which largely <br />reduces the uncertainties in the reconstructed 1.8 MeV intensity <br />distribution.<br />In summary, 1.8 MeV emission is mainly concentrated towards the <br />galactic plane, which clearly demonstrates that the bulk of 26Al is of <br />galactic rather than local origin.<br />However, distinct emission features towards Cygnus, Carina, and the <br />Auriga-Camelopardalis-Perseus region are inconsistent with a smooth <br />galactic 1.8 MeV emission profile, pointing towards a massive star <br />origin of 26Al.<br /><br />The second part of the thesis consists of a multi-wavelength <br />comparison of COMPTEL 1.8 MeV data which aims in the <br />identification of the origin of galactic 26Al.<br />For the comparison, a rigorous Bayesian analysis is applied, which <br />is the only consistent framework that allows inference based on the <br />comparison.<br />It turned out that the 1.8 MeV distribution follows very closely <br />the distribution of free electrons in the Galaxy which is traced by <br />thermal bremsstrahlung, observable in the microwave domain.<br />The similarity of the 1.8 MeV intensity distribution to the<br />thermal bremsstrahlung distribution implies a direct proportionality <br />between the 26Al and the massive star column densities, which strongly <br />supports that massive stars are the origin of galactic 26Al.<br />In particular, ONeMg-novae and AGB stars can be excluded as dominant <br />26Al sources since their galactic distribution is not expected to <br />correlate with the distribution of free electrons.<br /><br />The correlation between 26Al and free electrons established, the <br />analysis of 1.8 MeV gamma-ray line emission can complement our knowledge <br />about star formation and the distribution of ionized gas throughout <br />the entire Galaxy. <br />While COMPTEL made the first step in providing the first all-sky map <br />in the light of the 1.809 MeV line, INTEGRAL, the next generation gamma-ray spectrometer, will allow a detailed study of current star formation <br />in the Galaxy.

MOOCs實現了高等教育的跨國性、大量性與開放性，成功將世界各地的學習者、教學者與相關機構帶進全球網絡，為全球知識與傳播提供一個全新的平台。這場由世界頂尖大學所引發的MOOCs風暴，短時間內便席捲全球，在高等教育界掀起一陣波瀾。《紐約時報》甚至將MOOCs形容成一場「校園海嘯」，以迅雷不及掩耳的速度，衝擊高等教育的百年現場。 然而，究竟這場MOOCs風暴是如何一路延燒到世界各地？不同階段的影響因素又有何不同？為了釐清這些問題，本研究利用複雜理論「系統性」與「動態性」的觀點，探討MOOCs創新擴散之動態歷程，分析相關因素如何影響各個階段的歷程演變，以及因素之間互動後所產生的回饋關係。 本研究採用歷史研究法，並參考王美雅（2005）的創新擴散之動態模型，做為研究架構之基礎，探討MOOCs各階段擴散歷程之初始狀態、演化與正向回饋效果以及自我組織的現象。 研究結果發現，MOOCs的擴散事實上是一個自我組織的過程。在MOOCs擴散過程中，以「創新者的網路位置」與「理解創新的難易程度」兩項變數的影響尤其顯著。而各項變數之間不僅擁有正向回饋效果，亦存在著負向回饋效果，進而影響MOOCs的擴散與演化。 / MOOCs successfully brought global students, educators, and related organization into a global network, forming a platform for global diffusion of knowledge. Started by top universities around the globe, MOOCs’ forces have swept around the globe in a short amount of time, creating ripples in the higher education web. The New York Times describes MOOCs as a “Campus Tsunami,” sweeping through the sectors of higher education. How did this “Campus Tsunami” sweep around the globe? What are the factors that affect its dynamic diffusion process? In order to clarify these questions, this study employs the systematic and dynamic point of view of the complex theory to analyze how the factors influence each of MOOCs diffusion stages and what effects the factors create after interaction. This study employs the historical study method and Mei Ya, Wang’s (2005) dynamic innovation diffusion model as the fundamental structure to explore the initial conditions, evolution and positive reinforcements, and self-organization of each diffusion stage. The results demonstrate that MOOCs’ diffusion is based on self-organization. Within the seven factors, innovator networks and the difficulties in understanding innovation are the foremost influential factors. During MOOCs diffusion stages, the different factors interact with each other, producing both positive reinforcements and negative reinforcements, thus influencing MOOCs continuous diffusion and development.