Memorial University Research Repository

The Memorial University Research Repository is an open access initiative to showcase and preserve Memorial University's creative and intellectual output, including theses, journal articles, conference papers, lectures, presentations, reports, and performances.

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Recent Submissions

Access status: Open Access ,
Molecular dynamics simulations of peptides in aqueous nanodroplets and nanofilms
(Memorial University of Newfoundland, 2026-02) Huang, Yiming; Saika-Voivod, Ivan; Wallin, Stefan; Malek, Shahrazad
Peptides in nanoscale aqueous environments are exposed to solvent conditions that are significantly different from those of bulk water. Using all-atom molecular dynamics (OPLS-AA/L, TIP4P/2005), we investigate five peptides—CBS-5, CBS-9, KKKDDD, DKDKDK, and GAD-1—in water nanodroplets (radius of approximately 2–3 nm) and nanofilms (thickness of approximately 5 nm), with bulk systems serving as references, across a temperature range of 180–300 K. The principal conclusion of this thesis is that temperature-dependent density changes and heterogeneities, surface water charge layering, and curvature affect the position, orientation, and secondary structure of peptides in aqueous nanoconfinement. We analyze the solvent structure through mass and charge density profiles for pure water nanodroplet and nanofilm systems. For droplet systems, we analyze peptide localization via radial distributions of Cα and charged sites, and water dynamics using a system-wise neighbour correlation function (NCF) and NCF resolved in concentric shells to derive a radial relaxation time τ(r). The peptide–droplet dynamics are assessed in comparison to the pure droplet using a normalized metric, τₙ(r). We compare the Cα and charged sites distributions in the nanodroplets with those in the nanofilms, and also analyze the pure bulk water and nanofilm using the mean square displacement and the system-wise NCF. Water in nanodroplets exhibits a neutral, slow-relaxing core and a charge-rich, more densely packed and faster-relaxing subsurface below around 240 K, and these density anomalies, as well as the radial dynamical heterogeneity, diminish upon warming. The location of peptides depends on both temperature and amino acid sequence: amphipathic GAD-1 and the hydrophobic CBS peptides preferentially sample the surface or subsurface, while charge-dense DK sequences favour the interior at higher temperatures and react to cooling. Charged regions in the nanodroplet subsurface affect the stabilization of charged amino acids. Above 240 K in nanodroplets, CBS- 9 maintains a polarized orientation of its termini (C-terminus inward, N-terminus outward) but its N-terminus shows bimodal distributions at lower temperature, while CBS-5 shows this orientation except at 300 K, where the termini occupy similar radial positions. The CBS peptides that are simulated in the nanofilm configurations across 180 K to 300 K also exhibit this polarization. Additionally, peptides can alter local water mobility; most notably, at 240 K, DK sequences inhibit relaxation close to their loci. With implications for electrospray, interfacial biophysics, and nanomedicine, these findings collectively paint a mechanistic picture of how peptide localization and conformational response are jointly governed by electrostatic confinement, curvature-dependent adsorption, and temperature-dependent solvent structural heterogeneity.
Access status: Open Access ,
13 years of change? Exploring the climate change debate on Reddit through topic modeling
(Memorial University of Newfoundland, 2026-02) Funke, Laura; Stoddart, Mark C.J.; Stokes, Allyson
A growing body of academic literature analyses the public climate change debate carried out on social media platforms. As most studies focused on Twitter/X, little is known about long-term developments on other platforms, despite their popularity. The present study addresses this by analyzing a 13-year timespan during which five million posts and comments discussing climate change were published on Reddit, one of the most popular social media platforms in anglophone countries. Through topic modeling (LDA) and subsequent analyses, the main themes of discussion, the most popular communities, and changes over time are examined to describe the climate change debate on Reddit as well as how it relates to the general public debate and that on other platforms. The debate populates thousands of subreddit communities, and several recurring themes were found, discussing climate change in relation to environmental impact, scientific evidence, politics, and the economy, as well as extreme weather events. Similar to evidence from news media and other social media, the results attest to growing attention to the debate, while also noting how it becomes increasingly intertwined with political day-to-day business and popular discourse. This politicization is also evident in the dependence on mostly political events to generate and sustain significant levels of attention. Meanwhile, discussions pertaining to climate justice appear only marginally in the dominant themes.
Access status: Open Access ,
Dissociating the self: representations of mental illness in graphic memoir
(Memorial University of Newfoundland, 2026-02) Velentzas, Irene; Pedri, Nancy
Although the field of graphic medicine is burgeoning, the rapid proliferation of mental illness graphic memoir over the past two decades has yet to receive sustained scholarly attention (Velentzas 2021). This dissertation aims to correct that oversight by examining how mental illness graphic memoir operates as an essential vehicle for engaging with verbal-visual representations of mental illness through pictorial embodiment, graphic style, verbal-visual tensions, factors of visual coherence, visual metaphor, multiple textual delivery systems, and self-reflexivity. This study relies on foundational scholarship in the fields of disability studies, life-writing, comics formalism, and graphic medicine to examine the underlying constructions of mental illness representations in graphic memoir through close reading analysis and “research creation” (Loveless 2019). The dissertation’s academic portion closely examines seven mental illness graphic memoirs – Becoming Unbecoming (2016), Depresso (2010), Hyperbole and a Half (2013), Inside Out (2007), Lighter than My Shadow (2013), Marbles (2012) Solutions and Other Problems (2020) – alongside seventeen additional texts to determine patterns of representation that address and challenge stigmatic mental illness language and constructions. Its creative component, the graphic memoir Undiagnosed (2025), further applies and extends the foundational theory and the dissertation’s academic findings. “Dissociating the Self: Visual and Verbal Representations of Mental Illness in Graphic Memoir” reveals the ubiquitous use of a representational strategy I term dissociation – a visual mode that communicates the separation of the narratorprotagonist’s understanding of self from stigmatic understandings of mental illness embodied by a double. Visual dissociation is shown to operate through different stylistic appearances of the self and the double (Chapter 1), which encodes the moral, medical, and social paradigms of disability (Chapter 2). The double dissociates from stigmatic understandings of mental illness through the use and conceptual alteration of common visual metaphors for encoding mental illness, such as monsters and darkness (Chapter 3 and 4). Following the introduction (Chapter 5) and examination of Undiagnosed (Chapter 6), several verbal dissociation strategies are noted operating in mental illness graphic memoir, including differentiated font styles for personal and medical narratives; purposeful silence; disembodied speech balloons; and the inclusion, ironizing, and overwriting of medical texts (Chapter 7). Ultimately, “Dissociating the Self: Visual and Verbal Representations of Mental Illness in Graphic Memoir” demonstrates and theorizes the unique multimodal affordances of mental illness graphic memoir that enable cartoonists to encode, challenge, and overturn stigmatic understandings of mental illness to construct new understandings founded on empathy.
Access status: Open Access ,
Agricultural management in boreal regions alters soil respiration burst profiles
(Memorial University of Newfoundland, 2026-02) Vallotton, Jeremiah Daniel; Unc, Adrian
Land use conversion and climate change represent major threats to carbon (C) storage in boreal soils. Chapter I (literature review) of this dissertation shows that natural boreal soils are well-equipped to handle climate change, given that these ecosystems are already shaped by disturbance and possess natural mechanisms to resist or compensate for C loss under climate change. Much less is known about converted boreal soils under agricultural management, despite rapid and ongoing conversion. Chapters II-V of this dissertation thus combined four studies at different resolutions (within-field, within-farm, within-region, and global) to examine the fate of soil C in converted boreal soils through intensive soil abiotic property and soil respiration testing. Chapter II (within-field) examined a chronosequence of converted organic and podzolic soils and found that agricultural management rapidly homogenized soil to agricultural norms but also lost C rapidly under mineral management; surprisingly, high C presence resisted homogenization. Chapter III (within-farm) compared paired agricultural fields under normal management or amended with pulverized rock, and found that pulverization does not affect soil properties immediately; soil pedogenic type was more important in determining behavior. Chapter IV (within-region) compared soils under four land uses (LUs), and found that respiration patterns in each LU were distinct enough from each other (forest, agriculture, grassland) to allow for accurate prediction of LU. Chapter V (global) compared four LUs worldwide (agricultural, grassland, forest, and transitional) and found that global patterns of forest and agriculture could be accurately predicted via respiration, but grassland and transitional were too heterogeneous. Furthermore, respiration could indicate underlying management effects more accurately than abiotic factors on the global scale. This dissertation reveals that 1) boreal land conversion can cause <5yr shifts to agricultural norms accompanied by rapid C loss; 2) traditional management of boreal abiotic fertility fails to address questions of soil health and C cycling; 3) the status of boreal soils can be understood through LU-specific patterns of proportional respiration; and 4) conversion to agriculture creates anthropic soils with distinct behavior patterns that can be accurately predicted globally and must thus be managed differently from natural sites.
Access status: Open Access ,
A pilot study of a novel sleep scoring system to measure insomnia treatment response in breast cancer survivors
(Memorial University of Newfoundland, 2026-02) White, Emily A.; Garland, Sheila
Insomnia is prevalent among breast cancer survivors and Cognitive Behavioural Therapy for Insomnia (CBT-I) is an effective treatment. Research using polysomnography (PSG) to objectively measure sleep outcomes in response to CBT-I is limited. This single-arm study of nine breast cancer survivors examined sleep response to CBT-I using an in-home PSG device. The first objective examined feasibility of using the Cerebra Sleep System, an in-home PSG device, pre- and post-treatment. Recruitment and retention rates were relatively low, but the device was feasible to use. Attitudes towards using the device were mixed; some felt it was fine while others felt it was awkward and may have impacted their sleep. The second objective examined CBT-I sleep outcomes measured with sleep diaries and in-home PSG. Sleep diary measures of sleep onset latency, sleep efficiency, and wake after sleep onset significantly improved. PSG-measured sleep efficiency and wake after sleep onset significantly improved but time spent in sleep stages did not significantly change. Using an in-home PSG device may be feasible with changes to improve recruitment and retention rates and lessen the burden on participants. CBT-I may result in objective improvements in sleep continuity metrics. Future research should consider a largescale study with changes in methodology.