The biomass from a pilot-scale two-stage (carbon oxidation first stage, ammonia oxidation second stage) fixed-film biological aerated filter (BAF) was divided in three fractions depending on their attachment strength to the media: detached, easily detachable and strongly attached. VSS measurement showed that the detached and easily detachable fractions accounted for 25 to 40% of the biomass in the bed and are present even after backwash. Protein was the major constituent of all fractions of the biomass. The ratio of carbohydrate to protein differed between fractions and between type of biofilms, with a larger value for detached and detachable fractions and a lower value for a largely heterotrophic biofilm, implying a difference in the composition of the biomass matrix that could be related to the attachment state of the biomass. The biomass did not appear to be substrate-limited anywhere in the system, although the specific activity of the biomass was dependent upon the position in the column. Activity of the strongly attached biomass was less than 70% of the total activity, even after backwash. A mass balance on VSS showed that the backwash flushed a mass equivalent to less than 35% to 45% of the detached and detachable fractions, which was less than 15% of the total biomass present in the system. Data also suggested that during backwash, part of the strongly attached biomass was sheared off the media and regenerated the mass of biomass in the detached phase. In conclusion, it can be stated that a non-negligible part of the biomass in a BAF is in a detached state. Actual mechanistic BAF models based solely on biofilm modeling may be overlooking the role of that biomass, especially in the performance recovery of BAF systems after backwash. / Master of Science

Using the functional approach to volunteering as a basis, I investigated the implications of volunteer motivation congruence (i.e., a match between motivations to volunteer and the satisfaction of those motivations) for work recovery and downstream work engagement. I focused on career and understanding-based volunteer motives and psychological detachment and mastery recovery experiences. This was evaluated using a cross-sectional survey with a sample (N = 119) of employees with past volunteering experience. I found that psychological detachment was higher when career motives were greater than career motive satisfaction. Agreement between motives and satisfaction for both career and understanding motivations was also found to be more important than disagreement for predicting mastery experiences. Neither recovery variable (detachment and mastery experiences) was found to predict work engagement. No hypothesized indirect effects of the work recovery variables on the relationship between volunteer congruence and work engagement were supported. Overall, the results show a novel pattern of findings that encourages future research on volunteer motivation congruence and recovery experiences. / Master of Science / Many American employees also participate in volunteer work outside of their jobs. However, it is important to investigate whether this is beneficial for recovering from work stress since volunteering may be additionally taxing. Within this study, I look at whether a match between a person’s motivations to volunteer and the satisfaction of those motivations predicts recovery from work. I additionally look at whether that work recovery subsequently predicts engagement at work. Specifically, I focused on career and understanding-based volunteer motivations. I also focused on the work recovery experiences of psychological detachment from work and mastery experiences. I looked at these relationships using results from 119 participants who took a single survey. I found that psychological detachment was higher when career motives were greater than career motive satisfaction (in other words when the career motives were left unsatisfied). Neither recovery variable (detachment and mastery experiences) was found to predict work engagement.

Stressen inom arbetslivet är högre än någonsin och allt fler väljer att fortsätta arbeta under lunchrasten, eller att hoppa över den helt, till följd av detta. Det finns tecken som tyder på att synen på lunchrasten som ett tillfälle för återhämtning och vila har förändrats. På vissa håll har lunchrasten blivit ett laddat ämne, både för arbetsgivare och anställda, vilket kan få negativa konsekvenser både för individen själv och för arbetsplatsen. Lunchrasten är oftast en av de längsta rasterna under arbetsdagen och ger kontorsarbetare en chans att koppla bort tankar på sina arbetsuppgifter och kanske även möjlighet att lämna arbetsplatsen för ett miljöombyte och är därmed ett bra tillfälle för återhämtning. Syftet med studien var att undersöka upplevda stressnivåer hos kontorsarbetare efter tre olika typer av lunchsituationer (ledig lunch, arbetslunch inom kontorsbyggnaden samt arbetslunch utanför kontorsbyggnaden), och att med detta bidra med kunskap och information som kan vara till hjälp för både arbetsgivare och anställda i arbetet med att skapa en så gynnsam lunchsituation som möjligt, sett ur ett stressperspektiv. Stress mättes med Depression, Anxiety, Stress Scales DASS-21. Resultatet tyder på att vilken typ av lunchsituation man haft påverkar den upplevda stressnivån efter lunch. / The level of job related stress is higher than ever. As a result, an increasing number of people choose to continue working during the lunch break or to skip it altogether. There are signs that the view of the lunch break as an opportunity for recovery and rest has changed. In some places, the lunch break has become a loaded topic, both for employers and employees, which can have negative consequences for both the individual and the workplace. The lunch break is usually one of the longest breaks during the working day and gives office workers a chance to disconnect thoughts on their work tasks and perhaps also the opportunity to leave the workplace for a change of environment and are thus a good opportunity for recovery. The purpose of the study was to investigate perceived stress levels in office workers after three different types of lunch situations (free lunch, work lunch in the office building and work lunch outside the office building) and with this contribute with knowledge and information that could be helpful to both employers and employees, in creating as favorable a lunch situation as possible, from a stress perspective. Stress was measured with Depression, Anxiety, Stress Scales DASS-21. The result indicates that the type of lunch break you have had affects the perceived stress level after lunch.

In nature, cells are not randomly clustered to form tissues. The tissue is a more complicated system with functions that go beyond what any single cell type could accomplish. While studying single-cell mechanics and dynamics is relevant from an investigative point of view, this approach loses, or fail to gather information about the tissue. The tissue investigated in this study is the neurosensory retina which seeing as extension of the brain is a very convenient model for the central nervous system due to its accessibility. The retina is constantly subjected to different mechanical stresses from development to adulthood. Although the majority of the phenomena where mechanical stresses are involved are well-studied, the mechanics behind them is not well understood. However, knowledge about the ability of the retina to adjust to mechanical stresses is essential, for example, for improving retinal surgery. Establishing a method to mechanically probe the retina is a challenge due to the extremely delicate nature of this multilayered neural tissue and to the short-time survival ex vivo. The organotypic tissue culture is a powerful tool because it allows to maintain with high accuracy the complex multicellular anatomy and the microenvironment of the original tissue. One of the limitations of the organotypic culture techniques has been until recently due to the ability to use only post-natal/juvenile tissues for long-term culture. The importance of using adult tissue is incontestable when the investigation focuses on age-related pathologies such as vitreous shrinkage or macula degeneration. In this work, TiO2 nanotube arrays are presented as the innovative substrate for long-term organotypic culture of adult neural tissue. The retinal whole-mount of adult guinea pig and the brain slices of adult mouse were cultures for 14 days without showing any sign of edema or swelling. Furthermore, in order to study the behavior of the retinal tissue under shear stress new set-ups were designed. For the first time, the behavior of the retinal layers were observed showing that the retina does not act as an homogeneous material in response to an applied stress. The methods developed here can be used for future quantitative studies, to provide an exact knowledge of retinal biomechanics which will help retinal surgeons to optimize their methods.

Diese Dissertation untersucht, ob, wie und unter welchen Umständen mit Informations- und Kommunikationstechnologien (IKT) zusammenhängende Arbeitsanforderungen für Beschäftigte im digitalen Zeitalter eher ein Segen oder ein Fluch sind. In der ersten von zwei Längsschnittstudien wird basierend auf dem Stressor-Detachment-Modell (Sonnentag & Fritz, 2015) die Interaktion zwischen IKT-Arbeitsbelastung und emotionaler Erschöpfung untersucht. In der zweiten Studie wird auf der Grundlage des Job Demands-Resources Modells (Bakker & Demerouti, 2007) die Beziehung zwischen erweiterter Erreichbarkeit und kontextueller Leistung analysiert. Zusätzlich werden in den moderierten Mediationsmodellen jeweils mediierende Pfade (z.B. gedankliches Abschalten von der Arbeit) und IKT-bezogene individuelle sowie organisationale Faktoren (z.B. Workplace Telepressure, Segmentierungspräferenz) als moderierende Variablen kombiniert. Die Dissertation zeigt, dass die IKT-Arbeitsanforderungen das Wohlbefinden beeinträchtigen (erhöhte emotionale Erschöpfung), was möglicherweise auf einen Mangel an Erholung zurückzuführen ist. Auf der anderen Seite ist erweiterte Erreichbarkeit mit erhöhtem Arbeitsengagement und kontextueller Leistung assoziiert. IKT-bezogene individuelle Faktoren spielen nachweislich auch eine Rolle, da starke individuelle Segmentierungspräferenzen und ein hohes Maß an Workplace Telepressure die Effekte von beeinflussen. Zusammengefasst untersucht die Dissertation mögliche positive und negative Effekte von IKT-Arbeitsanforderungen längsschnittlich und untersucht erstmalig, wie und für wen Erreichbarkeit mit erhöhter kontextueller Leistung verbunden ist. Da sowohl leistungssteigernde als auch das Wohlbefinden beeinträchtigende Effekte der IKT-Arbeitsanforderungen und entsprechender Mechanismen in der Arbeit aufgezeigt werden, werden zudem theoretische Implikationen für die Forschung und praktische Implikationen für Beschäftigte und Organisationen abgeleitet. / This thesis investigates if, how and under which circumstances job demands that are related to information and communication technologies (ICTs) – so called ICT demands – are more of a boon or a bane for employees working in the digital era. In the first of two longitudinal studies, based on the stressor-detachment model (Sonnentag & Fritz, 2015), the interaction between ICT workload and emotional exhaustion is examined. In the second study, based on the job demands-resources model (Bakker & Demerouti, 2007), the relationship of extended work availability with contextual performance is investigated. Moreover, mediating pathways (e.g., psychological detachment) and ICT-related individual as well as organizational factors (e.g., workplace telepressure, segmentation preference) as moderating variables are combined within each moderated mediation model. On the one hand, the thesis demonstrates well-being-impairing effects of the investigated ICT demands (increased emotional exhaustion), potentially due to a lack of recovery. On the other hand, extended work availability is associated with increased work engagement and contextual performance. Overall, the studies reveal the crucial role of ICT-related individual factors by showing that strong individual segmentation preferences and high levels of workplace telepressure influence the impact of ICT demands. In sum, the present thesis explores potential positive and negative effects of the novel ICT demands over time and sheds new light on beneficial effects of extended work availability by exploring how and for whom it is associated with higher levels of contextual performance. Consequently, by showing performance-enhancing as well as well-being-impairing effects of the investigated ICT demands and the corresponding mechanisms, important theoretical implication for future research and practical implications for employees and organizations in the digital era are provided.

Retina is a unique site in the human body where the microcirculation can be imaged directly and non-invasively, allowing us to study in vivo the structure and pathology of the human microcirculation. Retinal images can be quantitatively assessed with computerized imaging techniques, enabling us to measure several different quantitative traits derived from the retinal vasculature. Arterial and venular calibres are the most extensively studied traits of the retinal microvasculature and numerous epidemiological studies demonstrated promising associations with systemic and ocular diseases as well as with disease markers. However, there has been a lack of research into pathophysiological processes leading to retinal vascular signs, and how they link retinal microcirculation with coronary and cerebral microvasculature change. Information about genetic determinants underlying retinal vascular structure is therefore important for understanding the processes leading to microvascular pathophysiology. Two genome wide association studies have been published so far revealing four loci associated with retinal venular calibre and one locus with arteriolar calibre. Here the results from the genome-wide association analysis of 10 different retinal vessel traits in two population based cohorts are presented. Retinal images were measured in non-mydriatic fundus images from 808 subjects in the Orkney Complex Disease Study (ORCADES) and 390 subjects from the Croatian island of Korcula, using the semi-automated retinal vasculature measurement programme SIVA and VAMPIRE. Using pairwise estimates of kinship based on genomic sharing, heritability was calculated for each trait. Estimates of tortuosity measure and fractal dimensions present first published reports of heritability estimates for those traits. In addition correlation analysis with systemic risk factor was also completed, confirming already published results as well as revealing some new associations. A genome wide association analysis of retinal arteriolar width revealed a genome wide significant hit (1.8x10-7) in a region of chromosome 2q32 (within TTN gene). Replication was sought in a further independent Scottish population (LBC) and additional 400 retinal images were graded. The result did not replicate, however the direction of the effect was consistent and a larger sample size is required. Analysis of the remaining traits did not yield genome wide significant result,s and will also require larger sample sizes. Genetic analysis of a binary retinal trait was also explored in a case control study of retinal detachment, which is an important cause of vision loss. A two-stage genetic association discovery phase followed by a replication phase in a combined total of 2,833 RRD cases and 7,871 controls was carried out. None of the SNPs tested in the discovery phase reached the threshold for association. Further testing was carried out in independent case-control series from London (846 cases) and Croatia (120 cases). The combined meta-analysis identified one association reaching genome-wide significance for rs267738 (OR=1.29, p=2.11x10-8), a missense coding SNP and eQTL for CERS2 encoding the protein ceramide synthase 2. Additional genetic risk score, pathway analysis and genetic liability analysis were also carried out.

Intense heat fluxes from the divertor incident on material surfaces represent a “bottleneck” problem for the next generation of tokamaks. Advanced divertors, such as the X-Divertor (XD) and Super X-Divertor (SXD), offer a magnetic solution to the heat flux problem by (a) increasing the plasma-wetted area via flux expansion at the targets, and (b) possibly opening regimes of stable, detached operation of the divertor via flux tube flaring, as quantified by the Divertor Index. The benefits of the XD and SXD are derived from their unique magnetic geometries, foregoing the need for excessive gas puffing or impurity injection to mitigate divertor heat fluxes. Using the CORSICA magnetic equilibrium code, XDs and SXDs appear feasible on current- and next-generation tokamaks, with no required changes to the tokamak hardware, and respecting coil conductor limits. Divertor heat and particle transport modeling is performed in SOLPS 5.1 for XD or SXD designs in NSTX-Upgrade, Alcator C-Mod, and CFNS/FNSF. Incident heat fluxes at the targets are kept well below 10 MW/m², even for narrow SOL widths in high-power scenarios. In C-Mod and CFNS, parallel temperature profiles imply the arrestment of the detachment front near the targets. Finally, an X-Divertor for ITER is presented. / text

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Thesis advisor: Yvette D. Kuiper / The Hudson Valley fold-thrust belt (HVB) is a narrow belt of deformed Upper Ordovician to Middle Devonian clastic and carbonate strata exposed in the western Hudson Valley of New York State. Geologic mapping at a scale of 1:10,000 was carried out near the town of Catskill. The southern portion of the map area includes a large doubly-plunging structure which features a fault-dominated southern portion plunging towards 017° and a northern fold-dominated, 206° trending, southerly plunging segment. A relay structure between two major faults or fault systems is interpreted as existing between the two domains. Farther north, the HVB narrows and folds plunge shallowly towards 212°, and then widens with folds plunging shallowly towards 017°. The changes can be explained by a localized increase in slip on the Austin Glen Detachment in the center of the map area, and subsequent loss of slip towards the north. / Thesis (BA) — Boston College, 2010. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: College Honors Program. / Discipline: Geology and Geophysics.

La croissance et le détachement des bulles formées sur une paroi par injection ou ébullition sont présents dans de nombreuses situationsindustrielles (les contacteurs gaz/liquide, les évaporateurs ou des dispositifs d’impression à jet d’encre). Dans la plupart des applications, les bulles grossissent dans un écoulement cisaillé ou au repos et la plupart des études visent à prévoir le rayon de détachement par une analyse de l’équilibre des forces. Ainsi, une bonne modélisation des forces capillaires et hydrodynamiques est nécessaire pour prédire correctement le rayonau détachement. Dans un premier temps, la croissance quasi-statique d’une bulle d’air formée sur la paroi d’une cuve et d’un canal rectangulaire est étudiée. Trois substrats différents sont utilisés pour observer l’influence des conditions de mouillage. La dynamique de la croissance de la bulle et le détachement sont alors enregistrés différentes configurations : canal horizontal, canal incliné, avec et sans écoulement liquide. Ensuite,le comportement des bulles de vapeurs en croissance sur une paroi en ébullition en vase et convective est étudié. Les expériences sonteffectuées en gravité terrestre et en microgravité dans un liquide sous-refroidi (HFE 7000) à basse pression (1-2bars). Des bulles de vapeurssont nuclées sur la paroi par l’intermédiaire d’un générateur de bulles. Ce dernier chauffe le liquide environnant au-dessus de sa température de saturation. Les bulles croient sur le site de nucléation dans un écoulement cisaillé et se détachent soit directement soit en glissant le long de la paroi. Une copie de la cellule d’essai appelée RUBI développée par l’ESA est implémentée dans le dispositif expérimental pour effectuer lespremières expériences en microgravité avant son lancement dans la station spatiale ISS. Toutes les acquisitions sont filmées à l’aide d’une caméra rapide et l’extraction du contour de la bulle est réalisée par traitement d’images. Différentes forces agissant sur une bulle sont calculées à partir des paramètres géométriques de la bulle. Un modèle prédictif de détachement de bulles est proposé. Enfin, un bilan thermique diphasique est effectué. / The growth and departure of bubbles nucleated on a wall are of particular interest in industrial situations such as gas/liquid contactors in chemicalprocessing, vapor nucleation in evaporators or inkjet printing devices. In most of these industrial applications, the bubbles grow in a shear flow and most studies aim topredict the radius at detachment by a force balance analysis. Thus a good modeling of both the hydrodynamic and capillary forces is needed to predict correctly this radius. First, the quasi-static growth of an air bubble nucleated on the wall of a tank and a rectangular channel is investigated. Three different substrates are used to observe the wettability effect. The dynamics of the bubble growth and detachment is then recorded for different configurations : horizontal channel, inclined channel, with and without a shear flow. Then, behavior of vapor bubbles growing at a wall in pool boiling and flow boiling is investigated. Experiments are performed in normal and microgravity environments with a subcooled test liquid HFE-7000 at low pressure (1-2 bars). Vapor bubbles are nucleated on the wall by a bubble generator that heats the liquid above its saturation temperature. This bubble generator was designed to provide nucleation on an isolated site. These bubbles grow on this nucleation site under an imposed shear flow and depart downstream either along the wall or perpendicularly. A copy of the test cell called RUBI developed by ESA is included in our experiment to perform the first experiments in microgravity before its launch to the ISS. Geometric and kinematic features of the air bubbles and vapor bubblesare measured by processing images obtained by high-speed video recordings. Different forces acting on the bubbles are calculated from these measurements, using a point force approach. The validity of this mechanistic approach to the bubble dynamics is discussed. At last, heat transfer balance is estimated on the bubble.