Observations of galaxy environments have revealed numerous correlations associated with their intrinsic properties. It is therefore clear that if we are to understand the processes by which galaxies form and evolve, we have to consider the role of their immediate environment and how these trends change across cosmic time. In this thesis, I investigate the relationship between the environmental densities of galaxies and their associated properties by developing and implementing a novel approach to measuring galaxy environments on individual galaxy scales with Voronoi tessellations. Using optical spectroscopy and photometry from GAMA and SDSS, with 250μm far-infrared observations from the Herschel-ATLAS SDP and Phase-One fields, the environmental and star formation properties of far-infrared detected and non–far-infrared detected galaxies are compared out to z ∼ 0.5. Applying statistical analyses to colour, magnitude and redshift-matched samples, I show there to be significant differences between the normalised density distributions of the optical and far-infrared selected samples, at the 3.5σ level for the SDP increasing to > 5σ when combined with the Phase-One data. This is such that infrared emission (a tracer of star formation activity) favours underdense regions, in agreement with previous studies that have proposed such a correlation. I then apply my method to synthetic light cones generated from semianalytic models (SAMs), finding that over the whole redshift distribution the same correlations between star-formation rate and environmental density are found. However, as the SAMs restrict the role of ram-pressure stripping, the fact that we find the same qualitative results may preclude ram-pressure as a key mechanism in truncating star formation. I also find significant correlations between isothermal dust temperature and environment, such that the coldest sources reside in the densest regions at the 3.9σ level, indicating that the observed far-infrared emission in these densest regions is the product of ISM heating by the older stellar populations. I then extend my analysis to a deeper sample of galaxies out to z ∼ 2.2, combining near-infrared and optical photometry from the VIDEO and CFHTLS-D1 observations, cross-matched in colour, magnitude and redshift against 1.4 GHz VLA radio observations. Across the entire radio sample, galaxies with radio detected emission are found to reside in more overdense environments at a 4.0σ significance level. I then divide my radio sample to investigate environmental dependence on both radio detected star-forming galaxies and radio detected AGN individually, based upon a luminosity selection defined as L = 1023 W Hz−1. The same trends with environment are shown by my Radio-AGN sample (L > 1023 W Hz−1) which favour overdense regions at the 4.5σ level, suggestive of the interaction processes (i.e. major mergers) that are believed to trigger accretion, in agreement with earlier work that has suggested such a relationship. At lower radio luminosities, my Radio-SF sample (L < 1023 W Hz−1) also display a significant trend towards overdense regions in comparison to my nonradio detected sample, at the less significant level of 2.7σ. This is suggestive of the low overall bolometric luminosity of radio emission in star forming galaxies, leading to only the brightest radio emitting star forming galaxies being observed and a bias towards overdense regions. This is in addition to the fact that the luminosity selection used to separate AGN from star forming galaxies is not a perfect selection and open to AGN contamination in the low-luminosity sample. I conclude that the next generation of deep radio surveys, which are expected to reach many orders of magnitude deeper than current observations, will remove radio-loud AGN contamination and allow for the detection of low-luminosity star forming galaxies via radio emission out to high redshifts. This work has allowed for the environments of galaxies to be probed on smallerscales and across both wider and deeper samples than previous studies. With significant environmental correlations being returned, this indicates that the established processes responsible for such trends must have influence on the most local of scales.

En septembre 2011 s’est tenue, à l’Université de Sherbrooke – Campus de Longueuil, la toute première rencontre de la maîtrise renouvelée en enseignement au préscolaire et au primaire. Nous y avons accueilli 31 personnes souhaitant effectuer un travail de nature identitaire, entre autres par le biais d’une démarche réflexive prenant appui sur la création d’un portfolio électronique professionnel. Cette formation s’est déroulée sur trois années au total à raison de six séminaires annuels comptant pour 15 crédits des 45 crédits que comporte la maîtrise. Pendant trois années consécutives, les personnes étudiantes se sont volontairement engagées dans un travail de nature identitaire. La présente enquête porte exclusivement sur la première année de cette formation et vise la modélisation de l’expérience du travail de nature identitaire effectué par les 31 personnes s’étant inscrites dans la formation à la maîtrise renouvelée. Nous avons fait appel à la méthode de l’enquête qualitative pour réaliser cette recherche. Les données qui forment le corpus analysé sont constituées d’un ensemble de productions biographiques émanant des participantes comme travaux dans les séminaires (retours réflexifs et bilans de fin de parcours), de trois entretiens collectifs formels réalisés avec les participantes en fin de parcours, ainsi que du journal de bord de la chercheure. L’analyse des productions biographiques a été faite en trois temps : un examen phénoménologique, une analyse à l’aide des catégories conceptualisantes, et un travail de théorisation/modélisation. Le modèle généré à partir de l’analyse des productions biographiques a été validé par les entretiens collectifs formels ainsi que par le journal de bord de la chercheure. Pour donner à voir l’expérience du travail de nature identitaire dans sa singularité, deux récits phénoménologiques ont été produits. Les résultats de cette enquête montrent que le travail de nature identitaire est un processus dynamique, créatif et interactif de production du sens qui se déroule au cœur d’une vie en perpétuel mouvement. Il concerne d’abord la personne et ses empreintes biographiques. C’est un travail qui est réalisé dans l’interaction et à travers de multiples rencontres : avec soi, en soi, avec l’autre et le monde. Ces rencontres sont génératrices de tensions entre ce qui résiste et ce qui pousse vers l’avant, entre le rejet et l’attraction, entre ce qui est, dans la réalité, et ce qui est souhaité pour l’à-venir. Ces tensions deviennent le point d’appui d’un balancier d’ambivalences qui amène la personne à se questionner et à se remettre en question pour trouver le sens de son existence et de son expérience. Pour être transformateur, un tel travail a eu besoin d’être soutenu par des leviers et a dû répondre à des conditions. Ces leviers et conditions n’ont pas tous eu les mêmes influences sur les personnes, sur leur vie, sur leurs pratiques, mais notre enquête montre qu’ils ont été porteurs d’un cheminement identitaire significatif, à des degrés divers. Ce travail n’est nécessairement facile. Il exige un engagement volontaire profond, de la rigueur, de l’ouverture et « beaucoup de cœur au ventre » de la part de la personne en formation. Il mène, entre autres, à une meilleure connaissance de soi, à une plus grande affirmation de soi et à une plus grande ouverture à soi ainsi qu’à l’autre. La réalisation de cette enquête a permis de faire ressortir plusieurs éléments clés de l’expérience du travail de nature identitaire vécue par les 31 personnes dans ce contexte de formation expérientielle continue offert au programme de la Maîtrise en enseignement au préscolaire et au primaire. Cette étude contribue à l’avancement des connaissances sur l’expérience du travail de nature identitaire en formation continue et, du coup, elle apporte des changements en faveur de l’importance de la prise en compte de cette orientation par les formatrices et les formateurs quand il est question non seulement de former des professionnelles et des professionnels compétents, mais aussi des personnes capables de définir elles-mêmes le chemin qu’elles souhaitent emprunter afin d’acquérir le pouvoir de se créer et de devenir effectivement elles-mêmes, jour après jour.

Les changements dans le réseau de la santé tel que le virage des soins vers le soutien à domicile (SAD) pour les aînés en perte d'autonomie, exigent des infirmières qu'elles mettent à jour leurs connaissances. Cette étude qualitative réalisée au moyen d'entrevues semi-dirigées s'intéresse au rapport à la formation infirmière continue (FIC) chez des infirmières en SAD au Québec. Son cadre de référence s'inspire des modèles de l'American Nurses Association (1994), de Cervero (1985) et de Hegge (1985). Les résultats révèlent que les infirmières sont engagées en FIC, qu'elles réalisent des activités de formation continue (AFC) diversifiées et qu'elles perçoivent certaines retombées dans leur pratique clinique. Cependant, des contraintes de temps, de coûts et d'accessibilité des AFC pertinentes demeurent des enjeux à prendre en considération. Finalement, des recommandations concernant la pratique clinique, l'enseignement, la gestion et la recherche sont proposées.

This dissertation is a study of the physical conditions in star-forming regions, and combines observational data and theoretical calculations. We studied the physical conditions of Orions Veil, which is an absorbing screen that lies along the line of sight to the Orion H II region. We computed photoionization models of the Veil. We combined calculations with UV, radio, and optical spectra that resolve the Veil into two velocity components. We derive many physical parameters for each component seen in 21 cm absorption. We find the magnetic field energy dominates turbulent and thermal energies in one component while the other component is close to equipartition between turbulent and magnetic energies. We observe H2 absorption for highly excited levels. We find that the low ratio of H2/H0 in the Veil is due to the high UV flux incident upon the Veil. We detect blueshifted S+2 and P+2 ions which must arise from ionized gas between the neutral portions of the Veil and the Trapezium and shields the Veil from ionizing radiation. We determine the ionized and neutral layers of the Veil will collide in less than 85,000 years. The second part of this dissertation involved self-consistently calculating the thermal and chemical structure of an H II region and photodissociation region (PDR) that are in pressure equilibrium. This differs from previous work, which used separate calculations for each gas phase. Our calculations span a wide range of initial conditions. We describe improvements made to the spectral synthesis code Cloudy which made these calculations possible. These include the addition of a molecular network with ~1000 reactions involving 68 molecules and improved treatment of the grain physics. Archival data are used to derive important physical characteristics of observed H II regions and PDRs. These include stellar temperatures, electron densities, ionization parameters, UV flux, and PDR density. The contribution of the H II region to PDR emission line diagnostics is also calculated. Finally, these calculations are used to derive emission line ratios than can tell us the equation of state in star-forming regions.

The ignition of the first sources of light marked the end of the cosmic dark ages, an era when the Universe transitioned from the relatively simple conditions following the Big Bang to the complex tapestry of dark matter, baryons, and pervasive cosmic radiation fields we see today. To better understand this uncharted cosmic epoch, we primarily utilize hydrodynamical, N-body simulations to model the assembly of the first galaxies at redshifts greater than ten and the stars that form within them. These simulations begin from cosmological initial conditions, employ a robust, non-equilibrium chemo-thermodynamic model, and take advantage of adaptive-grid-refinement to probe the multi-scale, complex process of star formation from ab initio principles. We explore the consequences that metal enrichment has on the process of star formation, confirming the presence of a critical metallicity for low-mass star formation. To assess the observational prospects of these primeval stellar populations with next-generation telescopes, like the James Webb Space Telescope, we constrain the star formation efficiency of both metal-enriched and metal-free star formation in a typical first galaxy. We also resolve the formation of individual metal-enriched stars in simulations that ultimately began from cosmological scales, allowing meaningful comparisons between our simulations and the recently discovered ultra-faint dwarf satellite galaxies, the suspected analogs of the first galaxies in the local Universe. / text

The upper Llandovery succession across the Jupiter-Chicotte formational contact on Anticosti Island, Québec, allows us to study the sediment dynamics and stratigraphic architecture of a storm-dominated, carbonate ramp. The Anticosti paleotropical ramp was slowly subsiding and recording significant changes in sea level in a far field glacial setting during the early Telychian. Three facies associations, grouping nine facies, are recognized along the E-W outcrop belt, and from top to bottom as the: (FA-1) encrinitic carbonate facies, (FA-2) mixed siliciclastic and carbonate facies, and (FA-3) non-encrinitic carbonate facies. These mid to outer ramp sediments represent deposition mostly from episodic, high-energy storm events as evidenced by hummocky cross-stratification, large wave ripples, gutter casts, and wave-enhanced sediment-gravity flow deposits. Spatial and temporal changes in siliciclastic content imply basin margin depositional environments in the eastern sections and change in climate regime from arid to humid conditions. The Chicotte deposition marks a major faunal change with the domination of crinoids triggered by increasing siliciclastic supply, rapid sea level fluctuations and change in substrates. The recognition of one major transgressive-regressive (TR) sequence subdivided in distinct meter-scale cycles allows a high resolution E-W correlation. The development of the TR sequence and meter-scale cycles is driven by glacio-eustacy where the main sequence is 4th order (~400 Ky) with superimposed meter-scale cycles that are 5th and/or 6th order (~100 Ky). Nevertheless, erosional capping surfaces within the more proximal tempestites represent ancient rocky shorelines that developed during forced sea level falls. In order to explain this stratigraphic architecture, a carbonate open-ramp model is proposed with a concave-up profile and a narrow and steep inner ramp in equilibrium with a high-energy coastline.

Stars are likely to form with non-zero initial angular momentum, and will consequently possess a substantial gaseous protostellar disc in the early phases of their evolution. At this early stage, the disc mass is expected to be comparable to the mass of the protostar. The disc’s self-gravity therefore plays an important role in the subsequent evolution of the system, regulating the accretion of matter onto the protostar, as well as being potentially capable of forming low mass stars and massive planets by disc fragmentation. The protostellar disc may later evolve into a protoplanetary disc, providing the feedstock for planet formation. Therefore, if the current stellar populations and exoplanetary systems are to be understood, an understanding of the evolution of protostellar discs is crucial, especially their earliest self-gravitating phases. I have used various methods of numerical simulation to probe the physics of self-gravitating protostellar discs and their constituents. When constructing a model for self-gravitating protostellar discs, including detailed thermodynamics and radiative transfer is essential. I have developed two distinct numerical techniques for incorporating radiative transfer into Smoothed Particle Hydrodynamics (SPH) simulations. The first allows the modelling of frequency-averaged radiative transfer during the SPH simulation, in effect approximating radiative SPH (RSPH) with only a marginal increase in runtime (around 6%). The second takes the output from SPH simulations, and creates synthetic, wavelength-dependent telescope images and spectra of SPH systems. This allows the direct construction of observables from SPH simulations, providing, for the first time, a direct connection between the output of SPH simulations and observations. I have used these numerical methods to analyse, in detail, the local angular momentum transport induced by self-gravity in protostellar discs, testing the robustness of the “pseudo-viscous” analytical approximation for local disc stresses. I confirm that semi-analytical disc modellers are justified in using the pseudo-viscous approximation in some cases, but I also outline the limits in which non-local transport effects causes the approximation to fail. Also, I have investigated the evolution of protostellar discs when perturbed by a secondary companion, in particular identifying whether such events will in general trigger a) a disc fragmentation event, or b) a stellar outburst event. For case a), I found no significant evidence that perturbation by a companion improves the possibility of disc fragmentation in compact discs - in case b), I found that stellar outburst events do indeed occur, but they are unlikely to be seen by observers due to their rare occurrence, as well as due to self-obscuration effects.

The primary focus of my PhD is to quantify the spatial distribution of star-forming environments from optical to radio wavelengths using data from the Hubble Space Telescope, the Very Large Telescope, the Spitzer Space Telescope, the Herschel Space Observatory, and the Caltech Submillimeter Observatory. Towards the end of my PhD study I have developed theoretical models. With these observational and theoretical avenues I have led a series of research projects to (1) quantify the initial spatial structure of pre-stellar cores and proto-stars, (2) test whether massive stars can form in isolation or not, (3) and develop a theoretical model on how young massive clusters form. These research projects have been fruitful as my collaborators and I have shown that pre-stellar cores and stars form in a smooth continuum of surface densities from a few to thousands of stars per pc^2. These two works have important implications on our understanding of what a young stellar cluster is and how star forming environments can evolve to form field star populations or gravitationally bound clusters. In my second study my collaborators and I found evidence for isolated massive star formation in the active star forming region 30 Doradus, in the Large Magellanic Cloud. The result impacts the field of the initial mass function and star formation models. Massive stars forming in isolation is consistent with a stochastically sampled initial mass function. Additionally, the result would put constraints on theoretical models on massive star formation. Continuing my work on massive star forming environments my collaborators and I have developed a theoretical model on how young massive clusters form. From the models we argue that feedback energies can be contained by the gravitational potential well of the massive progenitors. Furthermore, we predict the physical properties the massive cluster progenitors in terms of initial gas mass, radii and flux brightness to enable a search for these objects in Galactic plane surveys and upcoming telescopes. Using the common thread of spatial distribution analysis of star formation I describe my future research plans, which entails studies on extragalactic scales in the conclusion.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Accurate precipitation-type forecasts are essential in many areas of our modern society andtherefore there is a need to develop proper working methods for this purpose. Focus of thiswork has been to study important physical processes decisive in deciding both the temperatureof the precipitation particles, hence affecting their phase, and the surrounding air. Two majorlatent heating effects have been emphasized, melting effect and cooling byevaporation/sublimation. Melting of the snow flakes subtracts heat from the surroundings andhence acts as a cooling agent. Phase transformation from solid/liquid into the gas phase alsoneeds heat which here results in a cooling tendency. These two mechanisms may sometimeshave a crucial influence for deciding the correct precipitation-type. The melting effect isdiscussed in a paper about a snow event in Tennessee in USA, and another paper describingan event in Japan showing the influence of the evaporation/sublimation process. In the lattercase the wet-bulb temperature, Tiw as a physical correct discriminator between snow and rainis obtained. A numerical weather prediction model (HIRLAM) is being used to study differentcondensation schemes during three weather situations occurring in Sweden. These areRasch/Kristjánsson condensation scheme, Sundqvist original condensation scheme and amodification of the latter scheme. In the modified Sundqvist condensation scheme the Tiw hasbeen implemented as a limit temperature between snow and rain. The results are showingdifferences between the two main schemes concerning the total precipitation (both snow andrain). Comparisons between Sundqvist condensation scheme and this modified version, calledSundqvist scheme with Tiw show that this latter version creates slightly more snow.Differences between them are largest in dryer areas. Differences in the snow accumulationincrease when the forecast length increases. That makes them harder to be compared to snowanalyses from MESAN (mesoscale analysis) because the analyses is partly based ondifferences in the snow depth and this cannot be directly compared to amount of newly fallensnow especially when surface air temperatures are above freezing. Deviations from the dataanalyses are obtained in both Sundqvist and Sundqvist scheme with Tiw but in some regionsthe latter is in better agreement with measurements. Further work is needed in precipitationtypestudies but the physical correct value with Tiw = 0 ºC as melting temperature used inSundqvist with Tiw scheme is an interesting project for the future in the field of precipitationtypeforecasting. / Sammanfattning av ”Regn eller snö? En fråga om våta temperaturen” Noggranna prognoser beträffande nederbördstyp är väldigt viktiga inom många områden isamhället. Det finns därför ett behov att utveckla bra metoder att avgöra om nederbördenfaller som regn eller snö. Viktiga fysikaliska processer är avgörande för nederbördens och denomgivande luftens temperatur; processernas kritiska betydelse för dess fas har satts i fokus.De två största latenta värmeeffekterna, avkylning genom smältning och genomavdunstning/sublimation har betonats. Smältning av snöflingorna extraherar värme frånomgivningen och därmed sänks temperaturen. Avdunstning och sublimation erfordrar värmeför fastransformation vilket även här tas från omgivningen och därmed en kylande effekt somföljd. Dessa två latenta värmeeffekter har ibland kritisk betydelse för nederbördstypen vidmarkytan och detta diskuteras dels i en artikel om en vädersituation från Tennessee (Kain etal., 2000) där smälteffekten fick avgörande betydelse för nederbördsfasen vid markytan, dels istudier från Japan där betydelsen av avdunstning och sublimation på nederbördstypenbetonats (Matsuo and Sasyo, 1981). I det senare fallet tydliggörs isobara våta temperaturenoch dess betydelse som diskriminator mellan regn och snö. En numerisk vädermodell (HIRLAM) har använts för att studera olika typer avkondensationsscheman och deras betydelse för nederbörden under tre olika väderskeenden iSverige. Dessa är Rasch/Kristjánssons kondensationsschema, Sundqvistskondensationsschema samt en något ändrad variant av Sundqvists kondensationsschema dären subrutin för beräknandet av Tiw har implementerats och ersatt den vanliga temperaturen iden del av schemat som beräknar smältning av nederbörd i fast form. Smälttemperaturen harsedan satts till 0ºC. Resultatet visar skillnader mellan Rasch/Kristjánssons schema ochSundqvists schema beträffande total 12 timmars nederbörd (regn och snö). Vissa periodertenderar Sundqvists kondensationsschema att överproducera nederbörden medan under andraperioder är det Rasch/Kristjánssons schema, som överproducerar jämfört mednederbördsobservationer. Jämförelser mellan Sundqvists schema och Sundqvists schema medTiw visar att den senare producerar mer ackumulerad snömängd med de största skillnaderna iområden som avviker mest från mättnad (100 %). Där finner vi också större differensermellan den vanliga temperaturen och Tiw. Skillnaden blir större när vi ökar den totala tiden förackumulerad snömängd men dessa värden blir då också svårare att verifiera med snöanalyserfrån MESAN. Detta då snöanalyserna bygger på skillnader mellan aktuell och föregåendeobserverade snödjup. Detta behöver ej alls vara lika med den verkliga mängden nysnö somfallit, speciellt under mätperioder då det är plusgrader. Avvikelser från snöanalyserna kannoteras i både Sundqvists schema och Sundqvists schema med Tiw. I vissa regioner är docksnöprognosen från den senare något bättre. Det fysikaliskt korrekta värdet av Tiw = 0ºC somsmältgräns mellan regn och snö istället för den vanliga temperaturen, utgör grunden förintressanta framtida studier beträffande nederbörd och nederbördstyp.