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

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.

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.

Natural Killer (NK) cells are cytotoxic lymphocytes that can recognize and kill virally infected or tumour transformed cells by the secretion of cytolytic granules containing perforin. An individual NK cell can kill several target cells sequentially. Each target cell can trigger NK cell activation via different activating ligands and here we report that the order in which ligands are encountered affects the NK cell response. When NK cells are repeatedly activated via their Fc receptor CD16, with the therapeutic antibody rituximab, perforin secretion decreases with each stimulation. However, perforin secretion is restored to its initial level upon subsequent activation by MICA, which ligates NKG2D. Repeated stimulation of NK cells via MICA also decreases the degranulation capacity of NK cells but, strikingly, this effect cannot be rescued by a subsequent stimulation with rituximab. The strength of perforin secretion is also translated to killing of Daudi target cells, expressing different ligands. When Daudi, opsonised with rituximab is the first target NK cell encounters, the sequential killing of another opsonised rituximab or Daudi, expressing MICA will not be affected. But, when Daudi-MICA is met first, the consecutive killing of Daudi-MICA as well as Daudi-rituximab will be impaired. We found that the mechanism underlying these differential outcomes involves shedding of CD16, which occurs upon NK cell activation through both, CD16 and NKG2D. Shedding of CD16 renders the cells insensitive to further activation via that receptor but they remain competent for further activation through NKG2D. Interestingly, however, we also identified the beneficial role of CD16 shedding for NK cell serial killing. NK cells are more motile on rituximab-coated surfaces than on MICA-coated surfaces and their migration speed decreases upon inhibition of CD16 shedding. Moreover, the inhibition of CD16 shedding also prevents the NK cell detachment from rituximab opsonised Daudi cells. Thus, the shedding of the receptor can serve to augment NK cell motility to move between target cells. Efficient NK cell detachment also correlated with their increased survival. Finally, we report that CD16 is constitutively organised in small, dense nanoclusters and that the ligation with rituximab does not affect their spatial distribution. Despite the shedding of the receptor, leading to less protein molecules at the surface, the area of these clusters remains the same. Together these data suggest that CD16 shedding hinders NK cell cytotoxicity against opsonised targets, but promotes their movements between different targets. Thus, receptor shedding is important for efficient NK cell serial killing. Manipulation of CD16 shedding, perhaps by boosting its recovery, might therefore represent an important target for NK cell-based therapies including treatments with therapeutic antibodies.

O Brasil é o maior produtor mundial de cana-de-açúcar, com uma área cultivada de aproximadamente 10 milhões de hectares. Em se tratando da sustentabilidade ambiental dessas áreas nota-se que há ainda um grande caminho a ser percorrido. Um dos problemas mais agudos é a erosão do solo e as suas implicações que trazem prejuízos ao produtor, à comunidade, à economia e ao meio ambiente. Neste estudo, objetivou-se investigar a erosão hídrica em uma microbacia de 6 hectares, nas duas vertentes cobertas por cana-de-açúcar, e com a presença de floresta na área ripária, em conformidade com o Código Florestal Brasileiro. Para isso, pluviômetros foram instalados para medir o volume e a intensidade das chuvas. A geração de escoamento superficial e da perda de solo foram estimados por parcelas instaladas nas duas vertentes cultivadas com cana-de-açúcar e na floresta ripária. Batimetria foi realizada no canal para avaliar o volume de sedimento depositado no riacho. A origem deste material foi determinada pelas composições isotópicas do carbono, expresso com ? 13C, utilizando-se como referência amostras de solo de áreas manejadas com cana-de-açúcar e floresta ripária. Nos estágios iniciais da cultura, a intensidade da chuva influenciou significativamente a ocorrência de escoamento e a desagregação do solo; que foram minimizadas com o crescimento da cana. Na floresta ripária, o escoamento superficial e a desagregação do solo ocorreram somente durante eventos intensos. Em uma das vertentes, cerca de 5% da precipitação anual foi drenada como escoamento superficial; na outra vertente, esta proporção aumentou para aproximadamente 11% e na floresta ripária diminuiu para menos de 2%. A perda do solo foi de aproximadamente 1.000 g m-2 em uma vertente, aumentou para cerca de 5.000 g m-2 na outra vertente, decrescendo para apenas 50 g m-2 na floresta ripária. Através da batimetria, estimou-se que 3,6 Mg de sedimentos por hectare foram carreados no riacho durante a estação chuvosa. A análise das composições isotópicas indicou que cerca de 30% da matéria orgânica presente no sedimento do riacho foi proveniente das áreas de cana e os outros 70% foram provenientes das áreas de floresta / Brazil is the world largest sugarcane producer, with a cropped area of approximately 10 million hectares. Soil erosion and its implications are some of the neglected environmental problems in sugarcane fields. In this study a plot of 6 hectares cropped with sugarcane, encompassing a 30 meters of riparian forest bordering a stream was chosen. Two pluviometers were installed in an open area in order to measure the amount and intensity of rain during the rainy season. Surface runoff generation and soil detachment were estimated by plots installed in cultivated and riparian areas. Bathymetry was carried out in the stream channel to estimate the soil mass settled on the stream bed. The sources of organic matter were investigated by carbon (?13C) stable isotopic compositions. In the earlier stages of the crop, the rain intensity strongly influenced runoff generation and soil detachment; that were minimized with the plant growth. In riparian areas, runoff and soil detachment occurred only during intense events. The total rainfall was approximately 1,500 mm, in one slope of the sugarcane field, approximately 5% of this rainfall drained from the watershed as surface runoff; in the other slope this proportion increased to approximately 11%, and in the riparian forest decreased to less than 2%. The soil detachment was approximately 1,000 g m-2 in one sugarcane slope, and increased to approximately 5,000 g m-2 in the other slope, decreasing in the riparian forest to only 50 g m-2. Using the bathymetry conducted in the stream channel, we estimated that 3.6 Mg of sediment per hectare were settled on the stream bed during the rainy season. The averages ?13C of soil from forest and sugarcane areas and in the stream bed indicated that 30% of this material was generated in the sugarcane areas and 70% in the riparian forest