La rotation a un impact majeur sur la structure et l'évolution des étoiles. En particulier, elle est connue pour être responsable de processus de mélanges macroscopiques des éléments chimiques et de transport de moment cinétique au sein des zones radiatives des étoiles. Dans la première partie de cette thèse, nous montrons comment l'état actuel de la modélisation stellaire justifie une nouvelle approche bi-dimensionnelle qui ne repose pas sur les hypothèses usuelles de rotation faible ou de rotation différentielle sphérique. Nous développons, dans la deuxième partie, un modèle simplifié (approximation de Boussinesq) d'étoiles en rotation rapide, en deux dimensions, où la rotation différentielle qui s'instaure et la circulation méridienne associée sont calculées de manière cohérente. Nous y identifions les paramètres pertinents à la description de l'écoulement induit par une contraction gravitationnelle dans un environnement stratifié de manière stable. Dans la troisième partie, nous démontrons que cet écoulement de spin-up l'emporte sur l'écoulement barocline à l'issue d'un temps de Kelvin-Helmholtz. La rotation différentielle adopte un profil universel cylindrique et la circulation méridienne est celle d'un écoulement de spin-up. Une couche de Stewartson s'établit aussi sur le cylindre tangent au noyau du modèle et pourrait être la source d'un couplage efficace de la rotation du noyau et de celle de l'enveloppe d'une étoile en fin de Séquence Principale. Dans la dernière partie de cette thèse, nous étudions Achernar, étoile en rotation rapide de type Be à l'aide du code compressible ESTER. Les modèles obtenus tendent à montrer que l'étoile est en contraction gravitationnelle post-Séquence Principale. Pour en rendre compte, le code ESTER a été modifié afin de suivre l'évolution chimique de l'étoile sur une échelle de temps nucléaire. / Rotation greatly impacts stellar structure and evolution. Particularly, it is known to be responsible of macroscopic mixings of chemical elements and transport of angular momentum within the radia­tive zones of stars. In the first part of this thesis, we show how the actual state of stellar modeling calls for a bi-dimensional approach going beyond usual assumptions of slow rotation and spherical differential rotation. We develop, in the second part of this thesis, a simplified model (Boussinesq approximation) of rapidly rotating stars in two dimensions, where the establishing differential rotation and associated meridional circulation are solved self-consistently. We describe the relevant parameters of the flow induced by a gravitational contraction in a stably stratified environment. In the third part, we demonstrate that this spin-up flow outweighs the baroclinic flow on a Kelvin-Helmholtz timescale. The differential rotation adopts an universal cylindrical profile and the meridional circulation is typical of the spin-up flow. A Stewartson layer appears too upon the tangent cylinder to the core and could explain an efficient coupling between the rotation of the core and the one of the envelope for stars at the end of the Main Sequence. In the last part of this thesis, we study Achernar, a rapidly rotating Be star, with the full-compressible ESTER code. Models we obtain tend to show that the star is undergoing a post Main Sequence gravitational contraction. To account this, the ESTER code has been modified to follow the chemical evolution of stars on a nuclear timescale.

We investigate the optical and Wide-field Survey Explorer (WISE) colors of "E+A" identified post-starburst galaxies, including a deep analysis of 190 post-starbursts detected in the 2 mu m All Sky Survey Extended Source Catalog. The post-starburst galaxies appear in both the optical green valley and the WISE Infrared Transition Zone. Furthermore, we find that post-starbursts occupy a distinct region of [3.4]-[4.6] versus [4.6]-[12] WISE colors, enabling the identification of this class of transitioning galaxies through the use of broadband photometric criteria alone. We have investigated possible causes for the WISE colors of post-starbursts by constructing a composite spectral energy distribution (SED), finding that the mid-infrared (4-12 mu m) properties of post-starbursts are consistent with either 11.3 mu m polycyclic aromatic hydrocarbon emission, or thermally pulsating asymptotic giant branch (TP-AGB) and post-AGB stars. The composite SED of extended post-starburst galaxies with 22 mu m emission detected with signal-to-noise ratio >= 3 requires a hot dust component to produce their observed rising mid-infrared SED between 12 and 22 mu m. The composite SED of WISE. 22 mu m non-detections (S/N < 3), created by stacking 22 mu m images, is also flat, requiring a hot dust component. The most likely source of the mid-infrared emission of these E+A galaxies is a buried active galactic nucleus (AGN). The inferred upper limits to the Eddington ratios of post-starbursts are 10(-2)-10(-4), with an average of 10(-3). This suggests that AGNs are not radiatively dominant in these systems. This could mean that including selections capable of identifying AGNs as part of a search for transitioning and post-starburst galaxies would create a more complete census of the transition pathways taken as a galaxy quenches its star formation.

The thesis develops an understanding of the relationship between populism and the changes in the media landscape brought about by the advent of web 2.0. Its aim is to explain the rapid emergence of the Beppe Grillo’s Five Star Movement in Italy. A contextual analysis of the structures of opportunities reveals that the key to understand the ‘success’ of 5SM lays in the fact that the political actor fully exploited the affordances of the Web 2.0, making them resonate with the ‘thin’ ideology of populism. The advent of web 2.0 can then benefit political actors employing a populist ideology in three ways; enhancing the declining trust and separation between people and the political establishment, providing a seemingly more direct form of communication with the electorate and providing a new way of constructing the ‘people’ of populism through the networks. / Graduate

In this thesis we address the problem of understanding the star formation process in giant molecular clouds in a galactic context. Most simulations of molecular clouds to date use an oversimplified set of initial conditions (turbulent spheres/boxes or colliding flows). Full galactic scale models are able to generate molecular clouds with complex morphologies and velocity fields but they fail to reproduce in detail the effects that occur at sub-pc scales (e.g. stellar feedback). Our goal is to build the bridge between these two scenarios, and to model the star formation process in molecular clouds produced in a galactic context. We extract our molecular clouds from full-scale galactic simulations, hence we need to increase the resolution by two orders of magnitude. We introduce the details of the program used to simulate molecular clouds in Chapter 2, and describe in detail the method we follow to increase the resolution of the galactic clouds. In Chapter 3 we compare our simulated galactic clouds with the more conventional approach of using turbulent spheres. We create turbulent spheres to match the virial state of three galactic clouds. We perform isothermal simulations and find that the velocity field inherited from the full-scale galactic simulations plays an important role in the star formation process. Clouds affected by strong galactic shear produce less stars compared with clouds that are compressed. We define (and test) a set of parameters to characterise the dynamical state of our clouds. To include stellar feedback in our simulations we need to introduce a cooling/heating algorithm. In Chapter 4 we analyse how the different velocity fields of our clouds change the temperature distribution even in the absence of feedback. To study the formation of molecules we need to model the chemistry of H2 in our clouds. We also add CO chemistry, and produce synthetic observations of our clouds. The effect of feedback from winds and supernovae in galactic clouds is studied in Chapter 5. We analyse the effect of winds in clouds with very different velocity fields. We find that the effect of winds is stronger in highly virialised, high star forming clouds, with clouds with weak galactic shear, compared to unbound shear-dominated clouds. The steady and continuous action of the winds appears to have a greater effect than the supernovae. In summary, the inherited properties from the galaxy have an impact on many relevant processes in star formation, influencing gravitational collapse, the formation of filamentary structures, the temperature field of the cloud, and have a considerable effect on the impact of feedback in the clouds.

No description available.

New software products, especially those based on innovation, typically originate in startup environment. The reasons are well -- known: small start-ups are quick to market (as marketing and development are close, sometimes one person), able to take decisions quickly, not risk-averse, unburdened by corporate bureaucracy etc. If successful (as they all hope to be), they grow quickly. Here comes the catch -- the same attributes that contributed to success early on can become reasons to fail later. The methods used by few, highly motivated stakeholders (owners/managers, key employees) at the beginning do not support the project organization as more people and complex issues are involved. This transition is the subject of this thesis -- how to make sure that suitable methods to support the alignment of marketing and development are phased in not too early (when they would constitute a drag and straitjacket, robbing the start-up of its advantages) but not too late (when their absence would lead to inconsistencies and mistakes, preventing the start-up to become a mature operation). As each project is unique, it requires different method at different times. Rather than proposing a fixed methodology, the thesis suggests criteria for recognizing when to look for a suitable method, how to choose it and how to apply it with minimum effort and optimum result. The theoretical part of the thesis explains how the methods work, the practical part demonstrates how they contribute to making correct decisions with higher probability.

The formation of stars begins with the fragmentation of molecular clouds and the formation of dense cores. This fragmentation process can either be the result of classical gravitational instabilities or triggered by some external event. The gas and dust of young protoclusters often hold the imprints of the initial conditions and triggers of that specific star forming episode. In this context, my thesis work is a study of the gas properties of young protoclus- ters within the Gould Belt. The first part of my work consists of a detailed study of the young Serpens star forming region with CO isotopologues. This study has revealed a complex temperature, column density and velocity structure. I proposed a scenario where a collision between two filamentary clouds or flows is responsible for the observed complex structure and the most recent burst of star formation in Serpens. This hypothesis was tested with SPH simulations and provides a plausible scenario. I am currently extending this work to other regions with a variety of star formation efficiencies, in search of the particular physical properties and dynamics of a molecular cloud that allow or prevent clouds to be in the verge of forming stars. As such, I have included in this manuscript my study of the gas in the B59 star forming region, the only active clump in the Pipe Nebula. The results from this study have shown it to be very different from Serpens, even though further studies are needed to provide a complete picture of the region. B59 was taken as the starting point for a larger study of the entire Pipe Nebula, driven by the peculiarly low star formation efficiency in the cloud and a test to the physical properties of cores prior to star formation.

Autor no autoriza el acceso a texto completo de su documento hasta el 15/4/2020. / Ingeniero Civil Industrial / Boxeway es una empresa de tecnología que soluciona el problema de la logística de última milla mediante el uso de lockers inteligentes (eLockers), complementados con una plataforma online. Esta solución permite realizar transacciones de objetos o documentos entre distintos actores mediante intercambios automáticos y asincrónicos. Las aplicaciones son tan vastas, desde empresas de retail, e-commerce u operadores logísticos hasta edificios corporativos y habitacionales que requieran gestionar objetos. El potencial es inmenso: Boxeway tendrá una red de eLockers ubicados en distintos puntos de la ciudad para que cualquiera, empresas o personas naturales puedan utilizar la plataforma para realizar intercambios. La propuesta de valor de Boxeway es hacer más cómodo, práctico y barato el intercambio de objetos entre distintas partes. En los últimos años el crecimiento de 20% anual del comercio electrónico ha traído consigo todas las dificultades que implica la logística de despachos, provocando un alza en la cantidad de reclamos realizados al SERNAC. Estos han llegado a más de 12.000 reclamos en 2014. Los beneficios que trae tener menos puntos de entrega, no tener que coincidir con un morador, buscar una dirección, trae consigo una disminución en el costo de despacho de última milla, que según datos entregados por los mismos clientes, puede llegar a ser el 50% del total. La competencia se clasificó en proveedor tecnológico dentro y fuera de Chile y red pública (red de eLockers de Boxeway de uso público). El estudio validó las hipótesis propuestas en el Método Canvas para los distintos segmentos de clientes. Algunas conclusiones son que las personas están dispuestas a usar un eLocker son muy sensibles al precio de despacho, valoran que les llegue una alerta cuando el producto ya está en el eLocker y que les importa las ubicaciones de estos. Se definieron 3 productos (Pick Up, Corporativo y Front Desk) y dos modelos de pricing. Un modelo de precio de arriendo de eLockers fijo y otro que combina un valor fijo menor más un variable en función del número de operaciones realizadas al mes. La inversión necesaria para cumplir con los objetivos comerciales de instalar una red de 400 eLockers al cabo de 5 años es de 1,2 MM CLP, obteniéndose una TIR de 57,6% y un IR de 0,6.

Doctor Educationis / Background: In swimming, a swimmer’s performance is mostly determined by the time spent on starts, stroking and turning. The start of a swimming races, especially sprint races, can account for almost a quarter of race time. Aim: The aim of this study was to analyse the biomechanics and performance of three start techniques off the OSB11 starting platform over 15-meters to determine which of the three is most effective when looking at the three parts that constitute the start: block time, flight time and underwater time. Methods: A Quasi-experimental cross over trial-based study design was used to determine which of three starting techniques (Grab, Track & Kick) was the most effective off the OSB11 starting block. Ten Swimmers who qualified for junior nationals from Vineyard Swimming Club participated in the study. Each participant acted as their own control and were required to perform each start once. All trials were filmed and analysed on Dartfish pro suite 10. The following variables were analysed: shoulder angle, hip angle, knee angle, reaction time, movement time, total block time, flight distance, flight time, flight velocity, entry angle, underwater time, underwater distance, time to 15-meters.

Through the study of accretion onto the young, low-mass stars known as T Tauri Stars (TTS), we can better understand the formation of our solar system. Gas is funneled along stellar magnetic field lines into magnetospheric accretion columns where it reaches free-fall velocities and shocks at the stellar surface, generating emission that carries information about the inner regions of the protoplanetary disk. Accretion is a variable process, with characteristic timescales ranging from minutes to years. In this dissertation, I use simulations, models, and observations to provide insight into the driving forces of mass accretion rate variability on timescales of minutes to weeks and the structure of the inner disk. Using hydrodynamic simulations, I find that steady-state, transonic accretion occurs naturally in the absence of any other source of variability. If the density in the inner disk varies smoothly in time with roughly day-long time-scales (e.g., due to turbulence), traveling shocks develop within the accretion column, which lead to rapid increases in the accretion luminosity followed by slower declines. I present the largest Hubble Space Telescope (HST) spectral variability study of TTS to date. I infer mass accretion rates and accretion column surface coverage using newly updated accretion shock models. I find typical changes in the mass accretion rate of order 10% and moderate changes in the surface coverage for most objects in the sample on week timescales. Individual peculiar epochs are further discussed. I find that the inner disk is inhomogeneous and that dust may survive near the magnetic truncation radius. Next, I link 2-minute cadence light curves from the Transiting Exoplanet Survey Satellite (TESS) to accretion using ground-based U-band photometry. Additional HST observations for one target enable more detailed connections between TESS light curves and accretion. I also use the TESS light curves to identify rotation periods and patterns of quasi-periodicity. Finally, I connect hydrodynamic simulations, accretion shock models, and stellar rotation to predict signatures of a turbulent inner disk. I generate light curves from these models to make comparisons to previous month-long photometric monitoring surveys of TTS using metrics of light curve symmetry and periodicity.