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Recent Submissions
Marsh-estuarine benthic foraminiferal distributions and Holocene sea-level reconstructions along the South Carolina coastline.
(Dalhousie University, 1996) Collins, Eric Stephen.; Ph.D.; Department of Earth and Environmental Sciences; N/A; N/A; N/A
Using EEG to Endophenotype Schizophrenia
(2025-01-22) Anderson, T-Jay; No; Doctor of Philosophy; Department of Psychology and Neuroscience; Received; Dr. Michael Kiang; No; Dr. Philip Tibbo; Dr. Aaron Newman; Dr. Derek Fisher
This dissertation investigates EEG-derived endophenotypes to elucidate the neurophysiological underpinnings of schizophrenia through three interconnected studies.
Study 1: Meta-Analysis of Resting State Microstate Differences in Schizophrenia
The first study is a meta-analysis of EEG-derived microstates in schizophrenia. Microstates are brief, stable patterns of synchronized brain activity. This meta-analysis consolidates data from numerous studies to identify consistent alterations in microstates in individuals with schizophrenia compared to healthy controls. The findings reveal significant differences in microstate classes, particularly an increase in the duration and occurrence of microstate class C and a reduction in class D. These alterations suggest disrupted neural dynamics in schizophrenia, highlighting microstate parameters as a potential endophenotype for the disorder.
Study 2: Resting-State Microstate Differences in Early Psychosis as an Endophenotype Candidate. The second study explores resting-state EEG recordings to examine intrinsic brain activity in individuals with early-phase psychosis. Resting-state conditions reveal baseline brain functions, often associated with the default mode network. The study compares these microstates between individuals with early psychosis (n = 27) and healthy controls (n = 30) to determine if aberrant neural dynamics persist in the absence of external stimuli. The results indicate that individuals with early psychosis exhibit distinct microstate patterns, suggesting fundamental disruptions in brain function that could serve as reliable biomarkers for early diagnosis and monitoring of schizophrenia.
Study 3: Mismatch Negativity as an Endophenotype of Schizophrenia. The third study focuses on auditory processing, a critical domain affected in schizophrenia. Using EEG, this research study investigated event-related potentials (ERPs), particularly the mismatch negativity (MMN) component, which reflects automatic auditory change detection. The study found no group differences. However, MMN measures were associated with clinical symptoms.
General Conclusion: The collective findings of these studies advance our understanding of the neurophysiological abnormalities in schizophrenia. By identifying microstate alterations, this research provides evidence for EEG-derived markers as potential endophenotypes. These biomarkers offer promising avenues for early diagnosis, targeted interventions, and monitoring treatment efficacy, ultimately contributing to improved outcomes for individuals with schizophrenia.
In Memoriam: Robert Sandeski
(Dalhousie University, 2025)
Numerical Study of Interactions between surface waves, currents and hydrography in extreme weather conditions
(2025-01-15) Hughes, Colin; Yes; Doctor of Philosophy; Department of Oceanography; Not Applicable; Oliver Fringer; Yes; Ian Folkins; Michael Dowd; Jinyu Sheng; William Perrie
Surface gravity waves significantly affect air-sea interactions, turbulent vertical mixing, ocean currents and hydrography in the upper ocean, particularly during extreme weather events such as hurricanes and winter storms. Currents in the upper ocean also influence surface waves via the Doppler shift, relative wind effect, refraction and advection. This thesis examines the impact of wave breaking (WB), Langmuir turbulence (LT) and conservative wave effects on the upper ocean dynamics and effects of currents on surface waves during hurricane conditions using a coupled circulation-wave model. The wave-current interactions (WCIs) are investigated numerically in two cases using (a) idealized hurricanes moving at three translational speeds and (b) Hurricane Arthur (2014) over the northwest Atlantic Ocean. Model results in the fully coupled run are examined in comparison with results in other runs in which wave effects are selectively disabled to quantify main physical processes of WCIs, with a special focus on wave-induced changes to the upper ocean turbulent kinetic energy (TKE), thermal structure and currents. For the case of idealized hurricanes, analyses of model results reveal that LT has a larger impact on upper ocean currents, temperature and TKE, compared to the other considered processes. The combined wave effects reduce the surface currents in the front two quadrants of the hurricane and enhance the cold wake and near-surface cooling, predominantly to the right of the storm track. For the case of Hurricane Arthur, both the LT and WB driven acceleration are found to be important to storm-induced changes in the upper ocean temperature and circulation. By contrast, the WB induced surface flux of TKE has a limited effect on the temperature, salinity and currents in the surface layer. Over pathways of the Gulf Stream, the large WCIs reduce the significant wave heights (SWHs) of surface waves during Hurricane Arthur, with the biggest differences occurring to the right of the storm track. SWHs on the left hand side of the storm are limited by the shorter fetch, shallower water depths and coastline.
A City Transformed? Urban Development and the Role of Canadian Railway Policy in Halifax, Nova Scotia, 1900-1920
(1992-03) Hodgins, Murray B.; Not Applicable; Master of Arts; Department of History; Not Applicable; unknown; Not Applicable; David Sutherland; Henry Roper; Michael Cross
This thesis analyzes the development of the city of Halifax in the first two decades of the twentieth century, emphasizing the themes of suburban growth, the rise of municipal boosterism, and the drive for industrial development. During this period the notions of privacy and autonomy of the traditional leadership of Halifax were challenged by Ottawa's decision to build a modern wharf and rail complex in the heart of Halifax's genteel south end. This challenge and the responses it generated within the city's business elite, civic administration, and Civic Improvement League, a group committed to the planned and orderly development of the city, provide an opportunity to explore major elements of the city building process in post Confederation Atlantic Canada.
The federal design, a massive departure from the existing course of development, was announced as a fait accompli. Fear of the project's vulnerability to political opposition compelled the booster element in the business elite to support the proposal as presented, despite the fact that the elite residential district would be destroyed. The municipal administration and the Civic Improvement League yielded to pressure and "rubber stamped" elite approval of the project. The League rose to assume the role of advocate for the city's interests, and used this position to continue its pursuit of comprehensive planning and orderly development. Its progressive goals were reduced to the enactment of protective zoning legislation for the residential area, however. The decline in national economic fortunes after 1913, and the onset of post-war economic deflation in 1921, slowed the city's growth to a halt. This decline rendered obsolete the optimistic projections behind the Ocean Terminals, and left the city of Halifax with a large, federally-controlled transportation complex in its formerly proud south end.
TREATMENT PERFORMANCE ASSESSMENT AND MODELING OF A SOIL-BASED WASTEWATER TREATMENT SYSTEM IN NORTHERN CANADA
(2025-01-14) Carvalho Boratto, Débora; Not Applicable; Master of Applied Science; Department of Civil and Resource Engineering; Not Applicable; n/a; Not Applicable; Dr. Lauren Somers; Dr. Azadeh Kermanshahi pour; Dr. Rob Jamieson; Dr. Barret Kurylyk
Wastewater treatment in northern communities is an ongoing challenging. This research focused on the performance assessment and modeling of a passive soil-based wastewater infiltration system in Fort Good Hope, Northwest Territories. A combination of year-round site-specific field data and physically-based numerical modeling of subsurface contaminant transport was used. The investigations reveal that site conditions allow satisfactory system performance despite harsh operating routines, with accumulation of nitrate in groundwater being the most prominent concern. Wintertime conditions have a significant impact on the system’s hydrodynamics and microbial community structure. Model results indicate that an improved effluent distribution system would be required to avoid system failure from excessive mounding in more restrictive scenarios. Atypical operation routines can exhibit advantages from a hydraulic perspective but decrease pollutant removal efficiency compared to conventional procedures. Ultimately, the research findings contribute to addressing knowledge gaps related to the use of soil-based wastewater treatment systems in northern regions.