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Covid-19 brought various challenges that the world that was not fully prepared to face since 2019. The pandemic came with both health and economic repercussions, and various organizations had to adapt their Organization Design to confront these new challenges posed by this Black Swan event. Since the pandemic is still recent, most of the research related to Organization Design and Covid-19 has focused on the changes during the pandemic. What has been missing in the research is a perspective on the evolution of Organization Design over time. Two research questions were addressed. The first question explored how individuals from different positions perceived changes in Organization Design during the pandemic using Jay Galbraith's Star Model. The findings revealed variations in perceptions across positions, particularly regarding hiring growth, structure, communication, rewards, and the hiring process. The second research question uses a combination of Path Dependence Theory and Jay Galbraith's Star Model to compare the short-term and long-term effects of contingencies on Organization Design within a Medical Manufacturing Company. Some changes, like temporary Covid-19 protocols and rewards, were phased out, while others, including remote work, digital transformation, hybrid work models, and certain structural changes, became permanent. The thesis contributes to the understanding of how Black Swan events impact Organization Design in the Medical Manufacturing Industry, providing practical recommendations for decision-making during crises and emphasizing the significance of organizational resilience and change management. The study's theoretical contributions include exploring path dependence in crisis-induced transformations, highlighting the dynamic nature of organizational responses, and suggesting future research avenues. Overall, this research enhances knowledge of Organization Design dynamics and offers guidance for organizations in crisis response and resilience-building. / Covid-19 förde med sig olika utmaningar och konsevenser såväl ekonomiskt som hälsomässigt. Pandemin kan ses som ett exempel på en svart svan-händelse, dvs. en osannolik händelse med omfattande konsekvenser. Organisationer var tvungna att anpassa sig för att möta utmaningarna som denna svarta svan-händelse medförde, i synnerhet när det gäller organisationsdesign. Eftersom pandemin fortfarande ligger relativt nära i tiden, har en stor del av forskningen kring organisationsdesign och Covid-19 fokuserat på förändringarna under pandemin. Det som har saknats i forskningen är ett perspektiv på utvecklingen av organisationsdesign över tid. Denna uppsats bidrar till att fylla detta kunskapsgap genom en fallstudie av ett medicinskt tillverkningsföretag. Två forskningsfrågor behandlas, den första frågan fokuserar på hur individer på olika positioner i företaget uppfattade förändringar i organisationsdesign under pandemin. Med utgångspunkt i Jay Galbraiths Star Model visar uppsatsen att uppfattningar om förändringar skiljer sig åt mellan olika positioner, särskilt med avseende på personaltillväxt, struktur, kommunikation, belöningar och rekryteringsprocesser. Den andra forskningsfrågan behandlar hur organisationsdesignen utvecklats i ett stigberoende perspektiv.Vissa förändringar, som rutiner för hantering av Covid-19 och specifika belöningsmodeller, fasades ut, medan andra, som distansarbete, digitalisering, hybridarbetsmodeller och vissa strukturella förändringar, förblev permanenta. Uppsatsen bidrar till en ny förståelse för hur en svarta svan-händelse kan påverka organisationsdesign inom ett företag och ger rekommendationer för beslutsfattande under kriser samt betonar betydelsen av organisationsresiliens och förändringshantering. Studiens teoretiska bidrag ligger i kombinationen av stigberoendeteori och omvandling under en extern kris av svart svan-typ.

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The wall effect is known to present difficulties when attempting to predict the pressure drop over randomly packed beds. The Nuclear Safety Standard Commission, “Kerntechnischer Auss-chuss" (KTA), made considerable efforts to develop an equation which predicts the pressure drop over cylindrical randomly packed beds consisting of mono-sized spheres. The KTA was able to estimate a limiting line, which defines the region for which the wall effect is negligible, however the theoretical basis for this line is unclear. The goal of this investigation was to determine the validity of the KTA limiting line, using an explicit approach. Packed beds were generated using Discrete Element Modelling (DEM), and the flow through the beds simulated using Computational Fluid Dynamics (CFD). STAR-CCM+R was used for both DEM and CFD operations, and the methods developed for this explicit approach were validated with empirical data. The KTA correlation predictions for friction factors were com- pared with the CFD results, as well as the predictions from a few other correlations. The KTA correlation predictions for friction factors did not correspond well with the CFD results at low aspect ratios and low modified Reynolds numbers, due to the influence of the wall effect. The KTA limiting line was found to be valid, but not exact. A new limiting line for the KTA correlation was suggested, however the new limiting line improved little on the existing line and was the result of some major assumptions. In order to improve the determination of the position of the KTA limiting line further, criteria need to be established which determine how small the error in predicted friction factor must be before the KTA correlation can be accepted as accurate. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

The wall effect is known to present difficulties when attempting to predict the pressure drop over randomly packed beds. The Nuclear Safety Standard Commission, “Kerntechnischer Auss-chuss" (KTA), made considerable efforts to develop an equation which predicts the pressure drop over cylindrical randomly packed beds consisting of mono-sized spheres. The KTA was able to estimate a limiting line, which defines the region for which the wall effect is negligible, however the theoretical basis for this line is unclear. The goal of this investigation was to determine the validity of the KTA limiting line, using an explicit approach. Packed beds were generated using Discrete Element Modelling (DEM), and the flow through the beds simulated using Computational Fluid Dynamics (CFD). STAR-CCM+R was used for both DEM and CFD operations, and the methods developed for this explicit approach were validated with empirical data. The KTA correlation predictions for friction factors were com- pared with the CFD results, as well as the predictions from a few other correlations. The KTA correlation predictions for friction factors did not correspond well with the CFD results at low aspect ratios and low modified Reynolds numbers, due to the influence of the wall effect. The KTA limiting line was found to be valid, but not exact. A new limiting line for the KTA correlation was suggested, however the new limiting line improved little on the existing line and was the result of some major assumptions. In order to improve the determination of the position of the KTA limiting line further, criteria need to be established which determine how small the error in predicted friction factor must be before the KTA correlation can be accepted as accurate. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2014

We will consider the scenario of the co-rotation of a fluid star (in specific, a neutron star) and a black hole. The neutron star (or primary)is assumed to have constant angular velocity. The tidal effects on the primary are investigated. First, the centrally condensed approximation is applied, where both bodies are considered as point sources. In the second treatment, the primary is treated as an incompressible and homogeneous fluid mass, which in addition to its own gravity is subject to centrifugal and Coriolis forces, derived from fluid motions. The black hole (or secondary) is treated as a rigid sphere and can be regarded as a point mass. The equilibrium figure is derived. The problem is then adapted to include vorticity and a pseudo-Newtonian potential. The coalescence of neutron star - black hole binaries and their importance to gravitational wave detection is also discussed. / Mathematical Sciences / M. Sc. (Applied Mathematics)

In this dissertation, we present three complementary studies of the processes that drive planetary migration. The first is a radial-velocity survey in search of giant planets in adolescent (<1 >Gyr) open clusters. While several different mechanisms may act to drive giant planets inward, only some mechanisms will excite high eccentricities while doing so. Measuring the eccentricities of young hot Jupiters in these clusters (at a time before the orbits have had a chance to circularize due to tidal friction with their host stars) will allow us to identify which mechanisms are most important. Through this survey, we detect the first 3 hot Jupiters in open clusters (and at least 4 long-period planets), and we measure the occurrence rate of hot Jupiters in clusters to be similar to that of the field (~1%). We determine via analyses of hot Jupiter eccentricities and outer companions in these systems that high eccentricity migration mechanisms (those requiring the presence of a third body) are important for migration. The second project, an adaptive optics imaging survey for stellar companions to known hot Jupiter hosts, aims to determine the role that stellar companions in particular play in giant planet migration. Through a preliminary analysis, we derive a lower limit on the binary frequency of 45% (greater than that of the typical field star), and we find that the presence of a companion is correlated with misalignment of the spin-orbit angle of the planetary system, as would be expected for stellar Kozai-Lidov migration: at least 74% of misaligned systems reside in binaries. We thus conclude that among high eccentricity migration mechanisms, those requiring a stellar companion play a significant role. Finally, we describe simulations of measurements of the planet population expected to be discovered by TESS, and use these to demonstrate that a strong constraint on the obliquity distribution of small planets can be derived using only TESS photometry, Gaia astrometry, and vsin(i) measurements of the host stars. This obliquity distribution will be a key piece of evidence to help detemine the likely formation and migration histories of small planets, and can contribute to the assessment of the potential for Earth-like planets to harbor life.

In the last few decades, the emergence of large-scale infrared surveys has led to a revolution in the study of star formation. In particular, NASA’s Spitzer Space Telescope has recently carried out mid- and far-infrared observations of numerous star formation regions with unprecedented resolution and sensitivity, and has uncovered thousands of forming stars. In combination with present and future large-scale near-infrared and sub-mm surveys, spectral energy distributions from near-infrared to mm wavelengths will be available for these thousands of young stars. Never before has there been such a wealth of multi-wavelength data for so many young stars. Traditional techniques for studying the physical properties of young stars through their spectral energy distributions have usually focused either on the analysis of many sources using simple observational diagnostics such as colours or spectral indices, or on the analysis of a few sources through the detailed modelling of their full spectral energy distributions. The work presented in the first part of this thesis aims to bridge these two techniques through the efficient modelling of the spectral energy distributions of many young stars. In particular, the technique developed for this work makes it straightforward to find out how well different physical parameters are constrained, whether any parameters are degenerate, and whether additional data would resolve the degeneracies. In the second part of this thesis, a census of intrinsically red sources observed by Spitzer in the Galactic plane is presented, including a catalogue of over 11,000 likely young stellar objects. This sample of sources is the largest uniformly selected sample of young stars to date, and effectively provides a map of the sites of star formation in the mid-plane of the Milky-Way. In parallel, this census has uncovered over 7,000 candidate asymptotic giant branch stars, of which over 1,000 are variable at 4.5 or 8.0 microns.

This dissertation explores embodiments of citizenship in three historical pageants of 1913. As historical pageantry reached the height of its popularity in the early twentieth century, the form was criticized by those who felt it represented a limited understanding of community and citizenship. Historical pageants came to prominence at a time in the nation’s history when lynching plagued the south, women agitated for the right to vote, and labor unions organized to demand better working conditions. Popular historical pageants presented a history which ignored these pressing social issues and supported the status quo. As a result, while pageants gained popularity the form was taken up by groups seeking to use pageants for different political purposes. My dissertation interrogates embodiments of citizenship in Progressive Era pageantry through three case studies: W.E.B. Du Bois wrote and staged Star of Ethiopia, devoted to re-telling African-American history; John Reed organized members of the Industrial Workers of the World (IWW) for a performance of The Paterson Strike Pageant to aid laborers on strike; and Hazel MacKaye staged Allegory in support of women’s suffrage. While each pageant aimed to promote diversity, once each pageant’s historiography landed on live bodies, the gaps between what the pageant argued for and who the pageant simultaneously excluded were made visible. Allegory crafted an argument for white women’s suffrage by excluding recent immigrant and women of color; Du Bois sought to promote the African American middle class by denigrating the working classes; John Reed painted an image of the IWW as a fully united working class while ignoring the racial and ethnic differences that had led to tensions among the group. Despite their progressive intentions, once each pageant moved its political arguments on stage, the choices they made in performance belied their inclusive aspirations. / text

In this thesis, we construct a new hydrodynamical algorithm able of handling general compressible reactive flow problems, based on a finite-volume method inspired by the original MUSCL scheme of van Leer (1979). The algorithm is of second-order in the smooth part of the flow and avoids dimensional splitting. It uses MPI to achieve parallelism, and includes an astrophysical equation of state and a nuclear reaction network. It proves to be robust to tests cases. In particular it reproduces quite well the reactive and non-reactive results obtained with two different numerical methods (Fryxell & al. 1989, Busegnies & al. 2007). Moreover the time-dependent results are in agreement with the corresponding steady state solution. This gives us confidence in applying it to an astrophysical situation which has never been studied, the propagation of a detonation in conditions relevant to superbursts. The algorithm is described in (Noel & al. 2007). In a firt step we obtain the detonation profiles in pure carbon and in a mixture of carbon and iron. In both cases we underline the large difference between the total reaction length and the length on which some species burn. This difference leads to enormous numerical difficulties because all the length scales cannot be resolved at the same time in a single simulation. We show that the carbon detonation might be studied in a partial resolution approach like the one of Gamezo & al. (1999). In a second step we construct a new reduced nuclear reaction network able to reproduce the energy production due to the photo-disintegrations of heavy elements, like ruthenium, which are thought to occur during superbursts in mixed H/He accreting systems. Using this new nuclear network we simulate detonations in mixture of carbon and ruthenium. An interesting feature is that, in this case, all the reaction lengths can be resolved in the same simulation. This makes the C/Ru detonations easier to study in future multi-dimensional simulations than the pure carbon ones (Noel & al. 2007b). Finally we perform some numerical experiments which show that our algorithm is able to deal with initially inhomogeneous medium, and that the multi-dimensional simulations are attainable even if they are quite computational time consuming. - B. Van Leer, J. Comp. Phys., 21, 101, 1979 - Fryxell, B.A., Muller, E., and Arnett, W.D., Technical report MPA 449, 1989 - Busegnies, Y., Francois, J. and Paulus, G., Shock Waves, 11, 2007 - Gamezo, V.N., Wheeler, J.C., Khokhlov, A.M., and Oran, E.S., ApJ, 512, 827, 1999 - Noël, C., Busegnies, Y., Papalexandris, M.V. & al., A&A, 470, 653, 2007 - Noël, C., Goriely, S., Busegnies, Y. & Papalexandris, M.V., submitted to A&A, 2007b / Un algorithme parallèle basé sur une méthode aux volumes finis inspirée du schéma MUSCL de Van Leer (1979) a été construit. Il a été développé sur base de la méthode de Lappas & al. (1999) qui permet de résoudre simultanément toutes les dimensions spatiales. Cette méthode se base sur la construction de surfaces appropriées dans l'espace-temps, le long desquelles les équations de bilan se découplent en équations plus simples à intégrer. Cet algorithme est actuellement le seul à éviter le "splitting" des dimensions spatiales. Dans les modèles conventionnels (PPM, FCT, etc.), l'intégration spatiale des équations est réalisée de manière unidimensionnelle pour chaque direction. Un réseau de réactions nucléaires ainsi qu'une équation d'état astrophysique ont été inclus dans l'algorithme et celui-ci a ensuite été soumis à une grande variété de cas tests réactifs et non réactifs. Il a été comparé à d'autres codes généralement utilisés en astrophysique (Fryxell & al. 1989, Fryxell & al. 2000, Busegnies & al. 2007) et il reproduit correctement leurs résultats. L'algorithme est décrit dans Noël & al. (2007). Sur base de cet algorithme, les premières simulations de détonation dans des conditions thermodynamiques représentatives des Superbursts ont été réalisées. Différentes compositions du milieu ont été envisagées (carbone pur, mélange de carbone et de fer, mélange de carbone et de cendres du processus rp). Dans la plupart des systèmes où des Superbursts ont été observés, la matière accrétée est un mélange d'hydrogène et d'hélium. Dans ce cas, des phases de combustion précédant le Superburst produisent des nucléides plus lourd que le fer (Schatz & al. 2003). Ces nucléides peuvent être photodésintégrés durant le Superburst. Pour prendre en compte ces réactions endothermiques de photodésintégration, nous avons construit un nouveau réseau réduit de réactions nucléaires qui a été incorporé dans l'algorithme hydrodynamique (Noël & al. 2007b). Ce réseau réduit reproduit globalement l'énergétique d'un réseau complet et a permis de faire la première simulation numérique de détonation dans des conditions caractéristiques de systèmes accréteurs d'un mélange hydrogène-hélium. Finallement quelques simulations multidimensionelles préliminaires ont éte réalisées. - Busegnies, Y., Francois, J. and Paulus, G., Shock Waves, 11, 2007 - Fryxell, B.A., Muller, E., and Arnett, W.D., Technical report MPA 449, 1989 - Fryxell, B.A., Olson, K., Ricker, P. & al., ApJS, 131, 273, 2000 - Lappas, T., Leonard, A. and Dimotakis, P.E., SIAM J. Sci. Comput., 20, 1064, 1999 - Noël, C., Busegnies, Y., Papalexandris, M.V. & al., A&A, 470, 653, 2007 - Noël, C., Goriely, S., Busegnies, Y. & Papalexandris, M.V., submitted to A&A, 2007b - Röpke, F. K. PhD thesis, Technischen Universitat Munchen, 2003 - Schatz, H., Bildsten, L., Cumming, A. and Ouellette, M., Nuclear Physics A, 718, 247, 2003 - Van Leer, B. Comp. Phys., 21, 101, 1979 - Weinberg, N.N. and Bildsten, L., ArXiv e-prints, 0706.3062, 2007