Spatio-Temporal Dynamics Of Phytoplankton Biomass From Ocean Color Remote Sensing And Cmip5 Model Suites

Phytoplankton are the base of the marine food web, and, importantly, drive the biological carbon pump, the combination of photosynthesis, organic carbon sinking and subsurface decomposition of organic matter which effectively sequesters carbon away from the atmosphere. Our knowledge of phytoplankton activity is currently advancing fast through developments of multiple ocean-color remote sensing algorithms and via developments in ecological modules incorporated in climate models. While climate models are projecting relatively clear trends in ocean ecology over the next century, distinguishing between interannual variability and ocean biology trends from satellite observations is difficult. Short record length, satellite data continuity issues and strong interannual variability all impact quantified trends. Additionally, commonly observed chlorophyll-a is not strictly indicative of underlying phytoplankton biomass because of phytoplankton adaptation. This thesis investigates the trends, interannual variability and seasonality in new size-partitioned phytoplankton biomass products, with a focus on the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) mission period (1997-2010). In Chapter 2 we found phytoplankton biomass increases in the warm ocean regions over this period, opposing common expectations of decreases in warming oceans. Biomass increases are due to increased physical mixing of the watercolumn and are partially attributed to the large scale El Nino Southern Oscillation (ENSO) phenomenon. Recent studies have highlighted the emergence of different types of ENSO, with a shift towards more Central Pacific ENSO events. Chapter 3 uses statistical techniques (agglomerative hierarchical clustering (AHC), empirical orthogonal functional analysis (EOF)) on phytoplankton biomass to characterize ENSO “flavors” in the tropical Pacific. For the first time, we empirically derive biological indices for different ENSO types and show high correlations with existing climate indices. In Chapter 4 we examine in depth seasonal in phytoplankton ecology between the North Eastern Pacific subpolar region and contrast it with North Atlantic subpolar ecology. We discuss drivers of biological changes (iron, nutrients, light, mixing). We reveal large differences between biological variables across ocean-color algorithms, as well as across the latest generation Earth System model suite (Carbon Model Intercomparison Project, CMIP5). Chapter 5 summarizes our findings and future work suggestions. Future work should link surface phytoplankton ecology to ocean-atmosphere carbon fluxes and ocean carbon pump efficiency

Damage Studies of Tungsten Samples Using Dense Plasma Focus Devices

Design and studies of plasma facing material for a fusion reactor is an engineering challenge. The focus of this M.Sc. thesis research project studies the interaction between the helium (He) ion beam produced in a dense plasma focus (DPF) device and the tungsten samples (poly-W and nano-W). Re-commissioning and optimization of a 1 kJ Mather-type UofS-I DPF was completed at the University of Saskatchewan. The United Nations University/ International Centre for Theoretical (UNU/ICPT) DPF device operated with helium working gas at the Nanyang Technological University (NTU), Singapore was used to study damage effects of tungsten sample with pulsed plasma irradiation under a simulated damage condition similar to that in a fusion reactor. Effect of irradiation of 2.3×10^28 m^-2 s^-1 helium ion flux on the PLANSEE double forged tungsten samples of size 1×10×10 mm^3 was investigated. Poly-W samples were irradiated for 5, 10, 15 and 20 shots from a distance 7 cm from the central anode of the DPF device. Surface defects due to He exposure were studied with SEM micrograph. High heat loads resulted in blisters and micro-cracks on the sample surface. With increase in the number of shots the density of the blisters increased and the crater-like He bubbles on the W surface were observed. Re-solidification of the melted and sputtered surface have been noticed as well. Nano-structuration of W was realized with UNU/ICPT DPF in argon working gas at 50 Pa pressure. Successive plasma pulses increased size of nanoparticles and led to particle agglomeration. At 10 shots, uniformly distributed highly dense nanoparticles of the size 20-50 nm have been synthesized. Nanostructured samples were then exposed to He plasma under the same conditions used for the poly-W samples. Instead of blisters and holes, micro-cracks and nanopores have been found on the synthesized Nano-W. BSE imaging of the poly-W and nano-W gives an evidence of trapped He bubbles on the poly-W sample surface and He desorption around grain boundaries in nano-W samples. EDX spectra showed the presence of Cu impurities due to sputtering from the anode in the DPF device. The XRD analysis of the exposed sample shows peak shifting toward higher diffraction angles and peak broadening of the prominent peak in the poly-W as well as nano-W samples. The comparative studies between poly-W and nano-W samples under irradiation of He ions seem to support the previous suggestions that nano-W is more favorable to be used as an alternative for plasma facing materials

Women and queer British South Asian Instagrammers

The following thesis centers the socio-digital lives of women and queer members from the British South Asian digital diaspora, providing an account of the ambivalent nature of digital identity work. More specifically, it is invested in engaging participants in reflecting on their own engagements and the engagements of others on Instagram. I then critically analyse how they simultaneously resist and reproduce neoliberal logics of social media platforms. I involve participants in reflective interviews related to their digital usage. This approach is a tool underpinned by three theoretical strands that make fluid diaspora experience and digital experience, as well as centering the affective dimensions of social media platforms through the method of in-depth interviews. Practically, I argue that it serves as an animated space within which to analyse data and imaginatively build a community for research purposes. Unlike digital counterpublics like Black Twitter, my participants are individual users and I therefore have created an analytical space through which I can define them as a particular set of users who will have different as well as similar behaviours and opinions. In contextualising participant perceptions within discourses concerning South Asian digital diasporas, I explore how the intersections of race, ethnicity, class, gender, sexuality and caste are centered and obscured and what this tells us about contemporary configurations of British South Asian identities nationally and globally. Further contextualising these perceptions within wider discourses of neoliberal logics of social media and platform capitalism, I analyse how this technological social mode shapes and is shaped by its users

Corporate Philanthropy: A Systematic Review

A systematic review of the corporate philanthropy literature is conducted. A sample of 60 academic articles was created and analyzed. The sample was examined to (1) develop a definition of corporate philanthropy contrasting it with related concepts; (2) review how corporate philanthropy has been examined theoretically; (3) review how it has been operationalized and determine commonly examined control, independent and dependent variables; (4) the societal implications of corporate philanthropy and (5) identify gaps in the literature and areas for future research. Findings suggest there is little cohesion in the literature regarding a standard definition, wide use of theories to situate corporate philanthropy, and several narrow conceptualizations with opportunities for an empirical and theoretical investigation to enhance the understanding of corporate philanthropy. The gaps identified in the literature review consist of (1) the further study of corporate philanthropy as an independent variable to determine the impacts of corporate action; (2) whether there is a certain amount of optimality associated with corporate donations; (3) whether there are cultural limitations to the findings of attitude towards corporate philanthropy, and (4) a fuller study of the risks and/or benefits posed by corporate philanthropy to society