Dalhousie University
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Advancing coastal inundation forecasting: A multifaceted machine learning approach
No full textA dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geospatial Computer Science.The frequency and severity of coastal inundation events are increasing along most of the world’s shorelines. Global sea levels were remarkably stable for thousands of years but climate change is driving rising sea levels, presenting significant challenges for coastal management and conservation efforts. Other factors such as land subsidence and shifting weather patterns further increase the vulnerability of coastal regions to inundation. Understanding the complex interactions among these factors is necessary for developing effective strategies to mitigate the impacts of coastal inundation and improve coastal resilience. More accurate and actionable predictive models and better monitoring systems are essential in assessing and managing the risks associated with coastal inundation. This dissertation explores and assesses the potential of machine learning techniques to predict coastal inundation for short-term, i.e., hours to days, predictions on the sandy beach adjacent to the instrumented pier of Horace Caldwell Pier in Port Aransas, Texas. Traditionally, short-term water level predictions have been used to alert the public of the potential for inundation events, providing stakeholders with valuable lead time to prepare and implement mitigation measures. However, in cases where longer preparation periods are required, seasonal to multi-year water level prediction models offer extended planning for stakeholders and beach managers. This dissertation contributes to the field of coastal inundation forecasts and assessment in several ways: (1) by assessing and enhancing the performance of deep learning architectures for short-term water level predictions. Sequence-to-sequence was identified as the most appropriate architecture for the problem as it significantly improves upon existing methodologies and pushes the boundaries of reliable predictability from 48 hours to 96 hours and more for inland stations; (2) by exploring the development of machine learning models for seasonal to multi-year water level predictions in the Texas coast region, offering valuable insights for longer-term planning and adaptation strategies with lead times of three months up to three years. (3) Finally, this dissertation introduces the first predictive machine learning model for total water levels, including wave runup, while incorporating metocean variables. The development of this model was possible through the installation of a fixed camera system, resulting in a unique dataset containing 30-minute imagery of the study area for over a year, which, along with bimonthly surveys and further processing, resulted in one of the first total water level time-series data sets. This allowed for a morphological analysis that determined that for the study area, inundation events are triggered by increases in dominant wave period, average wave period, significant wave height, and average water levels. It was also found that a dominant wave period of ten seconds or more leads to temporal beach erosion, with a recovery period under two weeks. Overall, this research contributes to advancing our understanding of predictive capabilities in managing coastal inundation, thereby assisting stakeholders and policymakers in developing proactive measures to safeguard coastal communities and ecosystems.Computing SciencesCollege of Engineerin
The effect of optic flow changes in a virtual reality environment on gait in healthy young adults
No full textCollege of Education and Human Development; Department of Kinesiology Biomechanics Lab; Faculty Mentor: Bryon ApplequistThe use of virtual reality (VR) for rehabilitation and biomechanical gait analysis has been researched in a small capacity. However, there is a lack of information regarding the effect that unmatched VR optic flow conditions and treadmill speeds have on gait kinematics. Investigating optic flow changes is important because we can understand how visual impairments affect an individual’s gait. The purpose of this study was to investigate joint range of motion (ROM) during gait with disconnected optic flow speed and gait speed in a virtual reality environment in healthy young adults. A 180° VR system with a park scene displayed on the screen was used along with a motion capture system and instrumented fixed-speed treadmill. 37 reflective markers were placed on the lower extremity and trunk to collect motion capture data during each trial. 11 participants completed 3 4-minute randomized walking trials at a self-selected pace on the treadmill. Trials included matched VR and treadmill speed, the VR at +/- 20% of their self-selected walking speed.
A repeated measures ANOVA was used to determine any interaction between variables with LSD post hoc analysis conducted if necessary. There were no significant effects from VR speed changes for ankle plantar flexion/ dorsiflexion ROM (P > .05), knee flexion and extension ROM (P > .05), or hip flexion and extension ROM (P > .05). In addition, there were no significant effects for ankle plantar flexion/ dorsiflexion peak velocity (P > .05), knee flexion and extension peak velocity (P > .05), or hip flexion and extension peak velocity (P > .05). Manipulating optic flow speed relative to walking speed does not change ankle, knee, and hip ROM or peak velocity. This indicates that optic flow does not have as much of an effect on joint kinematic variables as previously thought. It is possible that analyzing simple gait measures are not affected by manipulating the sensory system during walking in the VR environment, but that the organization and coordination of the movements may be affected. Future research should investigate the influence of optic flow manipulation on gait variability and the organization of movements
Senator Truan and governor of Massachusetts, Michael Dukakis
No full textSenator Carlos Truan and Michael Dukakis pose for a photograph
Canadian Extradition Law: The Pressing Need for Reform
No full textExtradition—the formal legal surrender between states of individuals sought for criminal prosecution or to serve a sentence—is an essential tool in the worldwide fight against cross-border crime. In a time when the permeability of borders to criminal conduct has reached previously untold levels, the importance of effective international law enforcement cooperation has similarly intensified. Criminal investigation and enforcement powers can, for all practical purposes, only operate within national borders, but criminals themselves are not so constrained. Human trafficking, internet fraud, financial crime, wildlife trafficking—all are running rampant. All states, and their citizens, have a pressing interest in crime suppression, in which extradition plays a key role; in Canada we need only think of the cases of Luka Magnotta, Nicholas Ribic and Gerald Gallant to know that extradition is a process we need; and because criminals are so mobile, we need it to work well.
The authors of the articles in this issue have varying perspectives, but all agree on an essential point: Canada’s extradition laws and practices have significant problems that are producing unjust and wrongful extraditions, and must be reformed
Mapping oyster habitat quality in Matagorda Bay through remote sensing-derived water quality datasets
No full textEvaluating oyster habitat quality is gaining importance as populations face drastic global declines. Oyster Habitat Suitability Index (HSI) models evaluate habitat quality. Environmental and water quality indicators (WQIs) generate these oyster HSIs. In this study, we extracted WQIs from remote sensing data from 2014 to 2023 (Chapter II), then utilized these WQIs alongside other physical variables to produce five oyster HSI models for Matagorda Bay (Chapter III). These oyster HSIs generated used salinity, turbidity, temperature, depth, and water velocity to depict habitat quality. Remote sensing datasets offer a unique opportunity to observe spatial and temporal trends in WQIs, such as chlorophyll-a, salinity, and turbidity, across various aquatic ecosystems. In this study, we used available in-situ WQI measurements (chlorophyll-a: 17, salinity: 478, and turbidity: 173) along with Landsat-8 surface reflectance data to examine the capability of empirical and machine learning (ML) models in retrieving these indicators over Matagorda Bay, Texas, between 2014 and 2023. Models with greatest performance were applied to generate datasets for each WQI from 2018 to 2023. Five oyster HSI models were then generated over Matagorda Bay on both monthly and annual scales from 2018 to 2023. Each model utilized five physical parameters (e.g., model inputs), including salinity, turbidity, water temperature, depth, and water velocity. The developed approach provides a reference context, a structured framework, and valuable insights for utilizing empirical and ML models and Landsat-8 data to retrieve WQIs over aquatic ecosystems. Additionally, oyster HSI models generated from this study suggests locations of optimal, moderate, and unsuitable habitat based on long-term water quality in Matagorda Bay.Physical and Environmental SciencesCollege of Scienc
Vulnerability of Wetlands due to Projected Sea-Level Rise in the Coastal Plains of the South and Southeast United States
No full textCoastal wetlands are vulnerable to accelerated sea-level rise, yet knowledge about their extent and distribution is often limited. We developed a land cover classification of wetlands in the coastal plains of the southern United States along the Gulf of Mexico (Texas, Louisiana, Mississippi, Alabama, and Florida) using 6161 very-high (2 m per pixel) resolution WorldView-2 and WorldView-3 satellite images from 2012 to 2015. Area extent estimations were obtained for the following vegetated classes: marsh, scrub, grass, forested upland, and forested wetland, located in elevation brackets between 0 and 10 m above sea level at 0.1 m intervals. Sea-level trends were estimated for each coastal state using tide gauge data collected over the period 1983–2021 and projected for 2100 using the trend estimated over that period. These trends were considered conservative, as sea level rise in the region accelerated between 2010 and 2021. Estimated losses in vegetation area due to sea level rise by 2100 are projected to be at least 12,587 km2, of which 3224 km2 would be coastal wetlands. Louisiana is expected to suffer the largest losses in vegetation (80%) and coastal wetlands (75%) by 2100. Such high-resolution coastal mapping products help to guide adaptation plans in the region, including planning for wetland conservation and coastal development
Temporal variation in sulfide intrusion in the seagrass Halodule wrightii
No full textSeagrasses are productive ecosystems that form dense meadows in shallow marine waters. Anthropogenic disturbances, particularly nutrient enrichment, have caused the loss of 29% of seagrass meadows in the past century. Sulfide intrusion, a toxic byproduct of microbial processes in sediments, is known to be a significant stressor to seagrasses, leading to reduced photosynthesis, hindered growth, and even die-off. We conducted a nearly year-long study on sulfide intrusion in H. wrightii tissue, measuring d34S and total sulfur values in leaf, rhizome, and root tissues during the summer, fall, and spring seasons. We also investigated the relationship between these intrusion indicators and environmental factors known to affect them, such as sedimentary d34S, porewater H2S, total biomass, total organic content, and iron levels. While the levels of these factors varied across weeks and seasons, we found few significant correlations with intrusion. However, we did observe significant correlations between plant tissue d34S and total sulfur content (Rroots =-0.49, Rrhizome = -0.44), suggesting that sulfide intrusion contributes to total sulfur content in below-ground tissues. In general, it appears that the factors affecting sulfide intrusion are both subtle and complex. By exploring other variables and sampling sites, we may be able to uncover more information about these relationships.Physical and Environmental SciencesCollege of Scienc
Law, Critique and the Believer\u27s Experience
Full text linkI have come to think that, most of the time, radical critics of a given discursive practice were once believers in that practice’s necessities and realities. In particular, I am of the opinion that one comes to appreciate the power of a discourse only when one has genuinely and personally experienced the necessitarian pull as well as the realities such discourse creates. To put it in phenomenological terms, I think that radical scepticism is often the expression of some self-revulsion at one’s earlier beliefs. The phenomenological causality described here is thus not simply about the devastating rage that one can possibly vent after feeling tricked into believing in the necessities and realities of the hard-learnt sophisticated paradigms of a system of thought. What is at stake here is a much greater phenomenological claim. It pertains to the greater potential of those who have experienced the full potency of the necessities of realities created by discourses to develop a very acute sensibility for discourses’ hidden works and thought-governing structures
Why Nothing Works With Anything Else
No full textYou know how your iPhone uses a different charging cable than your friend\u27s Android? Well, imagine you\u27ve just bought a $50,000 tractor ... that only works with parts from the company you bought it from. Or an expensive printer that only takes one kind of ink. Welcome to the fight for interoperability, a battle against the plans of companies to use digital technology to lock customers into their platforms, forever.
How did we let things get this far? Who\u27s fighting back and what regulations are they fighting for? One of the first victories in this war was Apple being forced to move to a universal charger on its\u27 new iPhone. Now what\u27s next?
GUEST: Anthony Rosborough, Assistant Professor of Law & Computer Science at Dalhousie University; doctoral researcher in Law at the European University Institute
Gender According to World Athletics: The Regulation of Racialized Athletes from the Global South
Full text linkIn March 2023, World Athletics, the regulating body for the sport of Athletics introduced The Eligibility Regulations for the Female Classification (Athletes with Differences of Sex Development). These Regulations limit participation in female Athletics events at international competition and to set world records. They require certain athletes to maintain a testosterone threshold below 2.5nmol/L, despite their naturally occurring testosterone levels. On one level, this paper is about gender regulation in sport, particularly regulating testosterone in elite, female athletes. On another level it is about power and privilege at the intersection of race, nationality, and gender. It argues that through its gender regulations, World Athletics is racializing non-western bodies and asserting white, Global North civilization as the appropriate authority on, and representation of, gender in sport.
En mars 2023, World Athletics, l’organisme de réglementation du sport de l’athlétisme, a introduit les règlements d’admissibilité pour la classification féminine (athlètes ayant une différence de développement sexuel). Ces règlements limitent la participation des femmes aux épreuves d’athlétisme lors des compétitions internationales et à l’établissement de records du monde. Elles imposent à certaines athlètes de maintenir un seuil de testostérone inférieur à 2,5nmol/L, en dépit de leur taux de testostérone naturel. D’une part, le présent article traite de la régulation du genre dans le sport, en particulier de la régulation de la testostérone chez les athlètes féminines d’élite. D’autre part, il traite du pouvoir et des privilèges à l’intersection de la race, de la nationalité et du sexe. Il soutient qu’à travers ses réglementations en matière de genre, World Athletics racialise les corps non occidentaux et affirme que la civilisation blanche du Nord est l’autorité appropriée en matière de genre dans le sport et de représentation de ce dernier