14589 research outputs found
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Investigating galaxy size growth and stellar mass assembly through the buildup of stellar haloes since z ∼ 1.1
Get PDF1 online resource (ix, 158 pages) : illustrations (some colour), charts (some colour), graphs (some colour)Includes abstract and appendices.Includes bibliographical references (pages 145-158).In our current theoretical framework of galaxy formation and evolution, galaxies assemble stellar halo components through galaxy-galaxy interactions and accretion of ex-situ material. Studying this buildup of stellar haloes helps us better understand the processes driving the size growth and mass assembly of galaxies. In this work, we investigate the stellar halo assembly of ∼500,000 galaxies over 0.2≤ z ≤1.1, by analyzing the evolution in their radial surface brightness and colour profiles. We find that since z=1.1 more massive galaxies assemble larger and brighter stellar haloes, and this assembly is inducing negative colour gradients. Quiescent galaxies grow more through ex-situ accretion than star-forming galaxies of similar masses, which results in faster evolution of quiescent galaxy sizes (Re). Our results suggest that minor mergers drive the size growth of galaxy haloes since z=1.1, while major mergers fuel the mass assembly and further size growth of the most massive (M⋆≥1010.5M⊙) quiescent galaxies
Female-perpetrated sexual homicide : a systematic review
Get PDF1 online resource (56 pages) : chartsIncludes abstract and appendices.Includes bibliographical references (pages 33-39).Research into the aetiology of sexual homicide perpetrators often highlights the impact of
adverse childhood experiences and deviant sexual interests on offence commission. However, this research traditionally focuses on samples of male offenders. In attempts to facilitate the generation of knowledge concerning female sexual homicide offenders (FSHO), a systematic review was conducted to establish the current state of literature on this population. In identifying how the developmental antecedents of adverse childhood experiences and deviant sexual interests impact FSHOs, we can further identify how they differ from male sexual murderers. According to the current literature, a population of North American FSHO reflect a balanced ethnic distribution and target individuals within their own ethnic group. Additionally, FSHO were far more likely to use a weapon whilst killing a victim that they were previously acquainted with. Besides differentiating them from their male counterparts, this suggests that there is further heterogeneity within the motivations behind female sex offending based on the ethnic distribution and weapon preferences. While all developmental factors were absent from the literature gathered, heterogeneity within the sexual murderer population is reflected in the demographics, victimology, and modus operandi of FSHO. Implying not only are they distinguishable from male perpetrators but may further be distinguished from each other. This review highlights a knowledge gap concerning the developmental processes and relevant factors to female sexual offending and establishes that more research into this population is necessary
Gene expression in response to salt stress mediated by genome doubling in Hordeum bulbosum
Get PDF1 online resource (52 pages) : illustrations, graphs (some colour)Includes abstract and appendices.Includes bibliographical references (pages 43-49).Soil salinity impacts crop plants globally and can lead to the death of the plant due to incapacitation of cellular processes. To increase survival, plants have evolved many adaptation mechanisms to tolerate salt stress including genome duplication resulting in polyploid plants and molecular modifications like N6-methyladenosine (m6A) RNA modification. How beneficial the m6A modification is to plant survival when faced with salt stress is still being largely studied. The species of study included the diploid and autotetraploid species of wild-type barley (Hordeum bulbosum) which are common in nature, with the tetraploids being known for surviving in high salinity environments. This study aimed to compare differences in gene expression of the diploid and tetraploid treated and control environments using salt response and m6A genes. To analyze salt tolerance, control plants were watered with tap water, and treatment plants were watered with a salt solution. RNA was collected from both control and treatment plants to be used for gene expression analysis. The expected results are that the salt treated plants will have changed gene expression for salt response and m6A genes compared to the control plant
Two-dimensional liquid chromatography (2D-LC) : a novel technique for the analysis of bisphenol contaminants in canned food items
No full text1 online resource (xiii, 112 pages) : illustrations (some colour), charts (some colour), graphs (some colour)Includes abstract and appendix.Includes bibliographical references (pages 82-88).Bisphenols (BPs) are chemicals prevalent in the manufacture of epoxy resins and polycarbonate plastics.1 For example, epoxy resin is used to line canned food items to prevent the can from corroding. Bisphenols, and BPA in particular, are known endocrine disruptors.4 Human exposure to BPA can have adverse effects on the reproductive and metabolic health.4 Given that ingestion of packaged food items constitutes the largest source of exposure to BPA, Health Canada has encouraged the phase-out of BPA in food contact materials. As a result, the food industry began replacing BPA with bisphenol analogues. Owing to the concerning toxicity of BPs to human health, it is essential to continuously identify and accurately monitor bisphenols that are unintentionally ingested, as a result of contaminated canned food items.
This thesis research proposes the first-ever use of a state-of-art technique, two-dimensional liquid chromatography (2D-LC), to identify and quantify BPA, BPB, BPF, BPS, BPZ, and BPAF in canned food items. To selectively and sensitively analyze the six targeted bisphenols, a multiple heart-cutting 2D-LC method was first developed. The coefficient of variation (CV) of peak areas and retention times for all analytes in both dimensions ranged from 0.050-2.960%. The recovery of the whole procedure was determined to be 67.41±0.05% in the first dimension, and 64.3±0.13% in the second dimension. Internal standard calibration curves were constructed for each analyte, using 4,4’-difluorobenzophenone as the internal standard. The coefficient of determination (R2) for the least-squares regression of the internal standard calibration curves, ranged from 0.982-0.997. The limit of detection (LOD) values, determined in the second dimension for the analytes, ranged from 0.082-0.301 ppm. Finally, four canned food items were obtained by solid-liquid extraction, and surveyed for BPA, BPB, BPF, BPS, BPZ, and BPAF. The 2D separation space played a key role by allowing peaks of interest in the first dimension to further separate. BPF (0.093 ±0.351 ppm) and BPAF (2.656 ±0.442 ppm) were thus accurately detected in two separate samples, respectively.</p
Investigating high-velocity stars ejected from the cores of globular clusters
Get PDF1 online resource (xii, 81 pages) : colour illustrations, colour charts, graphs (some colour)Includes abstract and appendices.Includes bibliographical references (pages 79-81).The dense environment in the cores of globular clusters enables three-body
interactions involving a binary system and a single star to occur frequently, which
can eject high-velocity stars from the cluster. The velocities of these stars reflect the
masses involved in the interactions which accelerated them, making them promising
tracers of stellar remnants in globular clusters, particularly the black hole population. We use Gaia Data Release 3 data to locate high-velocity stars in the regions around a large number of Milky Way globular clusters, finding over 2000 candidates for 53 of the investigated clusters. Thirteen of these clusters are selected for further analysis in order to determine the potential origins of the observed high-velocity stars. The velocity distribution of the ejected high-velocity stars is predicted analytically and compared to the observed samples for a number of scenarios of different three-body interactions, mostly involving compact objects such as black holes. We can determine that the likely object which has been involved in the interaction that produced these stars must be a black hole for some cases. We have found evidence of the presence of black holes in nine globular clusters. We discuss future directions and improvements to this work which will allow for further constraints on black hole populations within globular cluster
Advanced forecasting algorithms for renewable power systems
Get PDF1 online resource (x, 112 pages) : illustrations (some colour), charts (some colour), graphs (some colour)Includes abstract.Includes bibliographical references (pages 100-112).Wind and solar power prediction is a challenging but important area of research. The thesis you described explores various statistical models and deep learning methods to improve the accuracy of wind speed and solar radiation predictions. The use of autoregressive integrated moving average (ARIMA) models, long short-term memory (LSTM) based recurrent neural network (RNN) models, and multilayer perceptron (MLP) neural networks were studied to predict future wind speed values and the performance of a photovoltaic (PV) system. The results showed that the proposed models can effectively improve the accuracy of wind speed and solar radiation prediction and that the LSTM network outperformed the MLP network in predicting solar radiation and energy for different time periods. It is important to note that the performance of the models may
vary depending on the specific dataset used, the hyperparameters, and the model architecture. Therefore, it is essential to carefully tune these parameters to achieve the best possible performance. Accurately predicting the performance of a PV system at short time intervals is particularly important in the context of renewable energy sources, as it can help optimize the usage of these resources and improve overall efficiency. This research can contribute to the development of more accurate and reliable prediction models, which can lead to more efficient use of wind and solar power, reduce costs, and promote the adoption of renewable energy sources
Effects of jumping worms on European earthworms and soil properties
Get PDF1 online resource (49 pages) : colour maps, colour graphsIncludes abstract.Includes bibliographical references (pages 41-49).Earthworms are ecosystem engineers which alter soil structure and impact other organisms and ecosystem functioning. In 2014, pheretimoid “jumping worms” (Megascolecidae spp.) were discovered in Ontario, Canada, with later discoveries in New Brunswick (2021), and Nova Scotia (2022). Jumping worms are having substantial impacts in the northeastern United States, including effects on nutrient cycling and other soil organisms. In Canada, little research has been done to examine spread or effects of jumping worms since they have established only recently. Thus, we sampled at a residential property in Oromocto, New Brunswick, which was the first location where jumping worms were found in the province. Our objectives were to evaluate: (1) how jumping worms impact soil properties (i.e., nitrogen, carbon); (2) how their presence
impacts the abundance of European earthworms; and (3) the effectiveness of two jumping worm sampling methods. We found that jumping worms did not have significant impacts on European earthworm species or soil carbon, but they did have significant impacts on soil nitrogen levels. Our results suggest the existence of a positive relationship between jumping worm abundance and soil nitrogen levels when jumping worm abundance is low. Also, both sampling methods (i.e., mustard solution and wooden discs) were equally effective at detecting the presence of jumping worms at a site. Over the longer term, we hope to track the expansion of this population in order to determine rates of spread
Integrative ArcGIS mapping study of direct hydrocarbon indicators within the Shelburne Subbasin of the Scotian Slope, Nova Scotia
Get PDF1 online resource (182 pages) : illustrations (chiefly colour), colour maps, charts (chiefly colour), graphs (chiefly colour)Includes abstract and appendices.Includes bibliographical references (pages 138-147).Seepage data can provide evidence for hydrocarbon migration from underlying mature
source rocks. In this study, ArcGIS coupled with seismic analysis of the Shelburne 3D seismic survey is used to better constrain the prospectivity of petroleum systems underlying the Scotian Slope. In this study, the seismic attributes root mean square amplitude (RMS) and coherence were used to identify near-surface expressions of hydrocarbon migration from the Shelburne 3D seismic volume. The RMS amplitude maps reveal amplitude anomalies including direct hydrocarbon indicators (DHIs) above salt features that are likely related to the presence of hydrocarbon-bearing sediments. Coherence maps were used to highlight seafloor and subsurface discontinuities such as
paleo-pockmarks and polygonal faults, which are subsurface fluid escape mechanisms. The DHIs are commonly associated with these fluid escape structures. The presence of these two features suggest hydrocarbons are migrating from deeper within the Shelburne Subbasin implying the presence of an active petroleum system within the deeper Scotian Slope
The social and economic impact of co-creation : sub-Saharan African enterprises
Get PDF1 online resource (86 pages) : illustrations, charts, graphsIncludes abstract.Includes bibliographical references (pages 67-85).Co-creation is a collaborative innovation process that involves stakeholders in product or
service development, ensuring offerings align with customer needs. It can create adaptable, responsive, and market-relevant solutions. However, its implementation is
constrained by factors like the innovation ecosystem, country infrastructure, and resources, with developed countries supporting it through regulations and initiatives.
This thesis explores the social and economic impacts of co-creation in sub-Saharan
African businesses. It uses World Bank Enterprise and Innovation Surveys to measure cocreation intensity and its effect on financial and social performance. The results show that co-creation fosters democratization by fostering inclusive environments where diverse
voices can shape outcomes. Co-creation enables more democratic and inclusive structures, enhancing collaboration and solutions that better represent the needs and
aspirations of all involved
2023-12-15 Senate Minutes and Agendas
No full textMinutes and agenda for the December 15th, 2023 meeting of Saint Mary’s University Senate